title: Nonlinear visuoauditory integration in the mouse superior colliculus

abstract: Sensory information from different modalities is processed in parallel, and then integrated in associative brain areas to improve object identification and the interpretation of sensory experiences. The Superior Colliculus (SC) is a midbrain structure that plays a critical role in integrating visual, auditory, and somatosensory input to assess saliency and promote action. Although the response properties of the individual SC neurons to visuoauditory stimuli have been characterized, little is known about the spatial and temporal dynamics of the integration at the population level. Here we recorded the response properties of SC neurons to spatially restricted visual and auditory stimuli using large-scale electrophysiology. We then created a general, population-level model that explains the spatial, temporal, and intensity requirements of stimuli needed for sensory integration. We found that the mouse SC contains topographically organized visual and auditory neurons that exhibit nonlinear multisensory integration. We show that nonlinear integration depends on properties of auditory but not visual stimuli. We also find that a heuristically derived nonlinear modulation function reveals conditions required for sensory integration that are consistent with previously proposed models of sensory integration such as spatial matching and the principle of inverse effectiveness.


title: Maximum likelihood estimation of the geometric niche preemption model

abstract: The geometric series or niche preemption model is an elementary ecological model in biodiversity studies. The preemption parameter of this model is usually estimated by regression or iteratively by using Mays equation. This article proposes a maximum likelihood estimator for the niche preemption model, assuming a known number of species and multinomial sampling. A simulation study shows that the maximum likelihood estimator outperforms the classical estimators in this context in terms of bias and precision. We obtain the distribution of the maximum likelihood estimator and use it to obtain confidence intervals for the preemption parameter and to develop a preemption t test that can address the hypothesis of equal geometric decay in two samples. We illustrate the use of the new estimator with some empirical data sets taken from the literature and provide software for its use.

category: ecology


title: Neural Basis for Regulation of Vasopressin Secretion by Anticipated Disturbances in Osmolality

abstract: Water balance, tracked by extracellular osmolality, is regulated by feedback and feedforward mechanisms. Feedback regulation is reactive, occurring as deviations in osmolality are detected. Feedforward or presystemic regulation is proactive, occurring when disturbances in osmolality are anticipated. Vasopressin (AVP) is a key hormone regulating water balance and is released during hyperosmolality to limit renal water excretion. AVP neurons are under feedback and feedforward regulation. Not only do they respond to disturbances in blood osmolality, but they are also rapidly suppressed and stimulated, respectively, by drinking and eating, which will ultimately decrease and increase osmolality. Here, we demonstrate that AVP neuron activity is regulated by multiple anatomically-and functionally-distinct neural circuits. Notably, presystemic regulation during drinking and eating are mediated by non-overlapping circuits that involve the lamina terminalis and hypothalamic arcuate nucleus, respectively. These findings reveal neural mechanisms that support differential regulation of AVP release by diverse behavioral and physiological stimuli.

category: physiology


title: Aureochromes are necessary for maintaining polyunsaturated fatty acid content in Nannochloropsis oceanica

abstract: Nannochloropsis oceanica, as other stramenopile microalgae, is rich in long-chain polyunsaturated fatty acids (LC-PUFA) such as eiconsapentaenoic acid (EPA). We observed that fatty acid desaturases (FAD) involved in LC-PUFA biosynthesis were among the strongest blue light induced genes in N. oceanica CCMP1779. Blue light was also necessary for maintaining LC-PUFA levels in CCMP1779 cells, and growth under red light led to a reduction in EPA content. Aureochromes are stramenopile specific proteins that contain a light-oxygen-voltage-sensing (LOV) domain that associates with a flavin mononucleotide and is able to sense blue light. These proteins also contain a bZIP DNA binding motif and can act as blue light regulated transcription factors by associating with a E-box like motif, which we found enriched in the promoters of blue light induced genes. We demonstrated that, in vitro, two CCMP1779 aureochromes were able to absorb blue light. Moreover, the loss or reduction of any of the three aureochromes led to a decrease in the blue light specific induction of several FADs in CCMP1779. EPA content was also significantly reduced in NoAureo 2 and NoAureo 4 mutants. Taken together, our results indicate that aureochromes mediate blue light dependent regulation of LC-PUFA content in N. oceanica CCMP1779 cells.

category: plant biology


title: Historical trade routes for diversification of domesticated chickpea inferred from landrace genomics

abstract:
According to archaeological records, chickpea (Cicer arietinum) was first domesticated in the Fertile Crescent 10 thousand years ago. Its subsequent diversification in South Asia, Ethiopia, and the Western Mediterranean, however, remains obscure and cannot be resolved using only archeological and historical evidence. In particular, chickpea has two market types:  desi, which has a similar flower and seed coat color to chickpeas wild relatives; and  kabuli, which has light-colored seed, and is linguistically tied to Central Asia but has an unknown geographic origin.

Based on the genetic data from 421 chickpea landraces from six geographic regions, we tested complex historical hypotheses of chickpea migration and admixture on two levels: within and between major regions of cultivation. For the former, we developed popdisp, a Bayesian model of population dispersal from a regional center towards sample locations, and confirmed that chickpea spread within each region along trade routes rather than by simple diffusion.

For the latter, migration between regions, we developed another model, migadmi, that evaluates multiple and nested admixture events. Applying this model to desi populations, we found both Indian and Middle Eastern traces in Ethiopian chickpea, suggesting presence of a seaway from South Asia to Ethiopia -- and the cultural legacy of the Queen of Sheba. As for the origin of kabuli chickpeas, we found significant evidence for an origin from Turkey rather than Central Asia.


title: Leaf-to-whole plant spread bioassay for pepper and 	Ralstonia solanacearum interaction determines inheritance of resistance to bacterial wilt for further breeding

abstract: Bacterial wilt (BW) disease by Ralstonia solanacearum is a serious disease and causes severe yield losses in chili peppers worldwide. Resistant cultivar breeding is the most effective in controlling BW. Thus, a simple and reliable evaluation method is required to assess disease severity and to investigate the inheritance of resistance for further breeding programs. Here, we developed a reliable leaf-to-whole plant spread bioassay for evaluating BW disease and then, using this, determined the inheritance of resistance to R. solanacearum in peppers. Capsicum annuum  MC4 displayed a completely resistant response with fewer disease symptoms, a low level of bacterial cell growth, and significant up-regulations of defense genes in infected leaves compared to those in susceptible  Subicho. We also observed the spreading of wilt symptoms from the leaves to the whole susceptible plant, which denotes the normal BW wilt symptoms, similar to the drenching method. Through this, we optimized the evaluation method of the resistance to BW. Additionally, we performed genetic analysis for resistance inheritance. The parents, F1 and 90 F2 progenies, were evaluated, and the two major complementary genes involved in the BW resistance trait were confirmed. These could provide an accurate evaluation to improve resistant pepper breeding efficiency against BW.


title: Abolished miR158 activity leads to 21-nucleotide tertiary phasiRNA biogenesis that targets NHX2 in Arabidopsis thaliana

abstract: Small RNAs including microRNAs (miRNAs) are short 20-24-nucleotide non-coding RNAs. They are key regulators of gene expression in plants and other organisms. Some small RNAs, mostly 22-nucleotide long trigger biogenesis of secondary small interfering RNAs (siRNAs). Those siRNAs having distinctive phased configuration are known as phased siRNAs (phasiRNAs) and act either in cis or trans enhancing silencing cascade. Here, we report natural variants of MIR158 having deletions or insertions led to negligible or reduced expression of miR158. The deletion/insertion events affected processing of primary transcript of miR158 to precursor and to mature miR158. We show that miR158 targets a pseudo-pentatricopeptide gene and its abolished activity led to 21-nucleotide tertiary phasiRNA generation from its target. The biogenesis of these phasiRNAS is triggered by TAS2 derived two siRNAs. Accordingly, small RNA analyses of these natural variants, mutants and over-expression lines of MIR158 or its target exhibited enhanced or reduced phasiRNA biogenesis. Finally, we functionally validated the highest expressed tertiary phasiRNA that targets NHX2 thereby regulating transpiration and stomatal conductance. Overall, we deciphered a new module of small RNA network, miRNA-TAS-siRNA-pseudogene-tertiary phasiRNA-NHX2, suggesting an additional layer of gene regulation and larger role of pseudogene in plants.


title: Signal processing basics applied to Ecoacoustics

abstract: Ecoacoustics is a research field that has attracted attention of researchers from areas as diverse as ecology, biology, engineering, and human sciences, to cite a few. Ecoacoustics studies the sounds that emanates from the environments, by gaining insights of landscape dynamics from acoustic patterns and particularities at different places. With recent advance in technology, it is common to obtain sound datasets recorded 24-h a day for several months. The analysis of these long-term sound recordings represents several challenges. Investigators already involved in acoustic are familiar with signal processing methods, which are essential tools for sound analysis. However, in general beginners interested in Ecoacoustics do not share this background formation. The present work illustrates basic topics of digital signal processing in a comprehensible style, and an effective pipeline for long-term sound explorative data analysis (EDA) is presented. Finally, the described signal processing fundamentals are applied for EDA of 1-month underwater acoustic data recorded in a Brazilian marine protected area. The Matlab codes used for the analysis will be available as supplementary material.

category: scientific communication and education


title: Iron-loading is a prominent feature of activated microglia in Alzheimer's disease patients

abstract: Brain iron accumulation has been found to accelerate disease progression in Amyloid {beta}-positive Alzheimer patients, though the mechanism is still unknown. Microglia have been identified as key-players in the disease pathogenesis, and are highly reactive cells responding to aberrations such as increased iron levels. Therefore, using histological methods, multispectral immunofluorescence and an automated in-house developed microglia segmentation and analysis pipeline, we studied the occurrence of iron-accumulating microglia and the effect on its activation state in human Alzheimer brains. We identified a subset of microglia with increased expression of the iron storage protein ferritin light chain (FTL), together with increased Iba1 expression, decreased TMEM119 and P2RY12 expression. This activated microglia subset represented iron-accumulating microglia and appeared morphologically dystrophic. Multispectral immunofluorescence allowed for spatial analysis of FTL+Iba1+-microglia, which were found to be the predominant A{beta}-plaque infiltrating microglia. Finally, an increase of FTL+Iba1+-microglia was seen in patients with high Amyloid-{beta} load and Tau load. These findings suggest iron to be taken up by microglia and to influence the functional phenotype of these cells, especially in conjunction with A{beta}.

category: neuroscience


title: Foveal vision at the time of microsaccades

abstract: Humans use rapid eye movements (saccades) to inspect stimuli with the foveola, the region of the retina where receptors are most densely packed. It is well established that visual sensitivity is generally attenuated during these movements, a phenomenon known as saccadic suppression. This effect is commonly studied with large, often peripheral, stimuli presented during instructed saccades. However, little is known about how saccades modulate the foveola and how the resulting dynamics unfold during natural visual exploration. Here we measured the foveal dynamics of saccadic suppression in a naturalistic high-acuity task, a task designed after primates social grooming, which--like most explorations of fine patterns--primarily elicits minute saccades (microsaccades). Leveraging on recent advances in gaze-contingent display control, we were able to systematically map the peri-saccadic time-course of sensitivity across the foveola. We show that contrast sensitivity is not uniform across this region and that both the extent and dynamics of saccadic suppression vary within the foveola. Suppression is stronger and faster in the most central portion, where sensitivity is generally higher and selectively rebounds at the onset of a new fixation. These results shed new light on the modulations experienced by foveal vision during the saccade-fixation cycle and explain some of the benefits of microsaccades.


title: A reservoir of stem-like CD8 T cells in the tumor-draining lymph node maintains the ongoing anti-tumor immune response

abstract: "Stem-like" TCF1+ CD8+ T cells (TSL) are necessary for long-term maintenance of T cell responses and the efficacy of immunotherapy but, as tumors contain signals that should drive T-cell terminal-differentiation, how these cells are maintained in tumors remains unclear. We found that a small number of TCF1+ tumor-specific CD8+ T cells were present in tumors throughout development. Yet, most intratumoral T cells differentiated as tumors progressed, corresponding with an immunologic shift in the tumor microenvironment (TME) from "hot" to "cold". By contrast, most tumor-specific CD8+ T cells in tumor-draining lymph nodes (dLNs) had functions and gene expression signatures similar to TSL from chronic LCMV infection and this population was stable over time, despite the changes in the TME. dLN T cells were the precursors of their more-differentiated intratumoral counterparts, and maintenance of TCF1 by intratumoral T cells required continuous migration from dLNs. Finally, TSL CD8 T cells were also present in LNs from lung adenocarcinoma patients, suggesting this population is also relevant in human disease. Thus, we propose that the dLN TSL reservoir has a critical function during tumor development in sustaining antitumor T cells during tumor development and protecting them from the terminal differentiation that occurs in the TME.

category: immunology


title: Targeted knockdown of the PAF49 component of the PAF53/PAF49 heterodimer causes the degradation of PAF53.

abstract: There are significant differences in the components of the ribosomal DNA transcription apparatuses of yeast and mammals. Moreover, the patterns of regulation between mammals and yeast are also different. To overcome, deficits in our understanding of mammalian rDNA transcription, we have developed a system to introduce an inducible degron into the endogenous genes of mammalian cells. This allows us to combine a knock out the endogenous gene product and replace it with mutant proteins in order to study their function in ribosomal DNA transcription. Using this system, we show that the knockout of PAF49, the mammalian ortholog of yeast A34, results in the relatively rapid degradation of PAF53, the ortholog of yeast A49. Interestingly, the steady-state levels of the core subunits of RNA polymerase I are unaffected.

category: molecular biology


title: Evaluation of solubility and histological effect of 11-keto-β-Boswellic acid on the diabetic mice liver using FTIR-PCA analysis and microscopy

abstract:
This study was designed to develop a rapid, sensitive, accurate, and inexpensive Fourier Transform Infrared Reflectance (FT-IR) Spectroscopy coupled with Principle Component Analysis (PCA) as a detection technique to evaluate the solubility of 11-Keto-{beta}-Boswellic acid (KBA), from the gum resin extracted from the Omani frankincense, (Boswellia sacra) in the liver of STZ induced diabetic mice. This study also investigated the effect of KBA on the histological changes of hepatocytes of diabetic mice. Liver tissue samples from three groups of mice included normal control group, diabetic control group and diabetic group treated IP with KBA were scanned with FT-IR spectrophotometer in the reflection mode. FT-IR Spectra were collected in the wavenumber range from 400 to 4000cm-1 using ATR accessorry. The results of FT-IR Spectra were analyzed by using multivariate method Principle Component Analysis. The PCA score plot is an exploratory multivariate method indicated that there was a complete segregation among the three groups of liver samples based on change in variation of position of wavenumber in FT-IR spectra, which revealed that there is a clear effect of KBA solubility on treatments. The histological features showed an improvement in the liver tissues with normal structures of hepatocytes with exhibiting mild vacuolations in their cytoplasm. In conclusion, reflectance FT-IR spectroscopy coupled with PCA could be deployed as a new detection method for rapid, low cost and non-destructive method for evaluating of treatment effects in diseased liver tissue based on the solubility of KBA. Histological findings demonstrated the protective effective of KBA on improving the morphology of liver tissue in diabetic mice which resulted in complete recovery to the damage observed in diabetic control group.

Summary StatementReflectance FT-IR spectroscopy coupled with PCA has been deployed as a new rapid, inexpensive and non-destructive detection method to examine the solubility of 11-keto-{beta}-Boswellic acid (KBA) in streptozotocin (STZ) induced-diabetes mice liver tissue following intraperitoneal treatment. Moreover, microscopic study of liver tissue histopathology revealed that KBA has a protecting effect against STZ damage.

category: developmental biology


title: Ecology drives the evolution of diverse siderophore-production strategies in the opportunistic human pathogen Pseudomonas aeruginosa

abstract: Bacteria often cooperate by secreting molecules that can be shared as public goods between cells. Because the production of public goods is subject to cheating by mutants that exploit the good without contributing to it, there has been great interest in elucidating the evolutionary forces that maintain cooperation. However, little is known on how bacterial cooperation evolves under conditions where cheating is unlikely of importance. Here we use experimental evolution to follow changes in the production of a model public good, the iron-scavenging siderophore pyoverdine, of the bacterium Pseudomonas aeruginosa. After 1200 generations of evolution in nine different environments, we observed that cheaters only reached high frequency in liquid medium with low iron availability. Conversely, when adding iron to reduce the cost of producing pyoverdine, we observed selection for pyoverdine hyper-producers. Similarly, hyper-producers also spread in populations evolved in highly viscous media, where relatedness between interacting individuals is higher. Whole-genome sequencing of evolved clones revealed that hyper-production is associated with mutations/deletions in genes encoding quorum-sensing communication systems, while cheater clones had mutations in the iron-starvation sigma factor or in pyoverdine biosynthesis genes. Our findings demonstrate that bacterial social traits can evolve rapidly in divergent directions, with particularly strong selection for increased levels of cooperation occurring in environments where individual dispersal is reduced, as predicted by social evolution theory. Moreover, we establish a regulatory link between pyoverdine production and quorum-sensing, showing that increased cooperation at one trait (pyoverdine) can be associated with the loss (quorum-sensing) of another social trait.

category: evolutionary biology


title: Detecting unreported recalls in memory experiments

abstract: In experiments on free recall from lists of items, not all memory retrievals are necessarily reported. Previous studies investigated unreported retrievals by attempting to induce their externalization. We show that, without any intervention, their statistics may be directly estimated through a model-free analysis of inter-response times - the silent intervals between recalls. A delay attributable to unreported recalls emerges in three situations: if the final item was already recalled ("silent recency effect"); if the item that, within the list, follows the latest recalled item was already recalled ("silent contiguity effect"); and in sequential recalls within highly performing trials ("sequential slowdown"). We then turn to reproducing all these effects by a minimal model where the discarding of memories ("bouncing") occurs either if they are repetitious or, in strategically organized trials, if they are not sequential. Based on our findings, we propose various approaches to further probing the submerged dynamics of memory retrieval.

category: animal behavior and cognition


title: Decoding silence in free recall


title: CloudReg: Automatic Terabyte-Scale Cross-Modal Brain Volume Registration

abstract: Quantifying terabyte-scale multi-modal human and animal imaging data requires scalable analysis tools. We developed CloudReg, an open-source, automatic, terabyte-scale, cloud-based image analysis pipeline that pre-processes and registers cross-modal volumetric datasets with artifacts via spatially-varying polynomial intensity transform. CloudReg accurately registers the following datasets to their respective atlases: in vivo human and ex vivo macaque brain magnetic resonance imaging, ex vivo mouse brain micro-computed tomography, and cleared murine brain light-sheet microscopy.

category: bioengineering


title: Structure and Function of an in vivo Assembled Type III-A CRISPR-Cas Complex Reveal Critical Roles of Dynamics in Activity Control

abstract:
The small RNA-mediated immunity in bacteria depends on foreign RNA-activated and self RNA-inhibited enzymatic activities. The multi-subunit Type III-A CRISPR-Cas effector complex (Csm) exemplifies this principle, but its molecular basis for regulation remains unexplained. Recognition of the foreign RNA, or cognate target RNA (CTR), triggers its single-stranded deoxyribonuclease (DNase) and cyclic oligoadenylate (cOA) synthesis activities. The same activities remain dormant in the presence of the self-RNA, or noncognate target RNA (NTR) that differs from CTR only in its 3-protospacer flanking sequence. Here we captured four structures of in vivo assembled Lactococcus lactis Csm (LlCsm) by electron cryomicroscopy representing both the active and the inactive states. Surprisingly, in absence of bound RNA, LlCsm largely forms a minimal assembly lacking the Csm2 subunit with a stably bound catalytic subunit Csm1. Comparison of the minimal LlCsm structure and activities, both in vitro and in vivo, with those of fully assembled LlCsm reveals a molecular mechanism responsible for the viral RNA-activated and self RNA-inhibited activity of Csm1 through protein dynamics.

Graphic Art Summary

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=91 SRC="FIGDIR/small/428455v1_ufig1.gif" ALT="Figure 1">
View larger version (30K):
org.highwire.dtl.DTLVardef@1e9c428org.highwire.dtl.DTLVardef@4d3397org.highwire.dtl.DTLVardef@76184dorg.highwire.dtl.DTLVardef@1359dd5_HPS_FORMAT_FIGEXP  M_FIG C_FIG

category: biophysics


title: MOLECULAR LANDSCAPE OF OLD AGE MELANOMA BY SURVIVAL AND IMMUNOTHERAPY RESPONSE

abstract:
Melanoma mortality particularly affects older patients, and age is a powerful independent predictor of death. The pathogenic mutations and transcriptomic changes associated with poor survival in aged patients are not known.

We analyzed 5 cohorts of metastatic (N=324, N=18, N=66) and primary melanomas (N=103, N=30) to establish the effect of age on prognosis, identify age-specific driver genes and transcriptomic changes linked to survival and immunotherapy response.

We identify the pathogenic mutations and transcriptomic changes associated with poor survival by age, and show mutations in BRAF, NRAS, CDKN2A or IDH1 identify metastatic and primary melanoma aged patients with worse outcome. In contrast, activation of immune-regulatory pathways is a hallmark of long-term survival. We tested if mutations in genes linked to poor outcome are associated to immunotherapy responders, exploring combinations of agespecific mutations in metastatic immune checkpoint inhibitor aged responders. Strikingly, aged patients with BRAF, NRAS, CDKN2A or IDH1 mutations and high tumor mutation burden treated with immunotherapy have an improved median survival of 12 months. These data highlight the molecular landscape of melanoma varies by age, and age stratification can refine prognosis and therapy rationales. A set of mutations identifies patients at highest risk of death who are likely immunotherapy responders.

category: cancer biology


title: Inhibition of HSP90 reversed STAT3 mediated muscle wasting induced by cancer cachexia

abstract: Cancer cachexia is one of the most common causes of death among cancer patients, no effective anti-cachectic treatment is currently available. In experimental cachectic models, aberrant activation of STAT3 in skeletal muscle has been found to contribute to muscle wasting. However, its clinical association, the factors regulating STAT3 activation, and the molecular mechanisms of STAT3-induced muscle atrophy in cancer cachexia remain incompletely understood. Here, we show that an enhanced interaction between STAT3 and HSP90, which causes the persistent STAT3 activation in the skeletal muscle of cancer cachexia patients, is the crucial event for the development of cachectic muscle wasting. Administration of HSP90 inhibitors alleviated the muscle wasting in C26 tumor-bearing cachetic mice model or C26 conditional medium induced C2C12 myotube atrophy. A mechanistic study indicated that in cachectic skeletal muscle, prolonged STAT3 activation triggered muscle wasting in a FOXO1-dependent manner, STAT3 activated FOXO1 by binding directly to its promoter. Our results provide key insights into the role of the HSP90/STAT3/FOXO1 axis in cachectic muscle wasting, which shows promising therapeutic potential as a target for the treatment of cancer cachexia.

category: pathology


title: AAV-Txnip prolongs cone survival and vision in mouse models of retinitis pigmentosa

abstract: Retinitis pigmentosa (RP) is an inherited retinal disease, affecting >20 million people worldwide. Loss of daylight vision typically occurs due to the dysfunction/loss of cone photoreceptors, the cell type that initiates our color and high acuity vision. Currently, there is no effective treatment for RP, other than gene therapy for a limited number of specific disease genes. To develop a gene-agnostic therapy, we screened {approx}20 genes for their ability to prolong cone photoreceptor survival in vivo. Here, we report an adeno-associated virus (AAV) vector expressing Txnip, which prolongs the survival of cone photoreceptors and improves visual acuity in RP mouse models. A Txnip allele, C247S, which blocks the association of Txnip with thioredoxin, provides an even greater benefit. Additionally, the rescue effect of Txnip depends on lactate dehydrogenase b (Ldhb), and correlates with the presence of healthier mitochondria, suggesting that Txnip saves RP cones by enhancing their lactate catabolism.


title: Suberin plasticity to developmental and exogenous cues is regulated by a set of MYB transcription factors

abstract: Suberin is a hydrophobic biopolymer that can be deposited at the periphery of cells, forming protective barriers against biotic and abiotic stress. In roots, suberin forms lamellae at the periphery of endodermal cells where it plays crucial roles in the control of water and mineral transport. Suberin formation is highly regulated by developmental and environmental cues. However, the mechanisms controlling its spatiotemporal regulation are poorly understood. Here, we show that endodermal suberin is regulated independently by developmental and exogenous signals to fine tune suberin deposition in roots. We found a set of four MYB transcription factors (MYB41, MYB53, MYB92 and MYB93), that are regulated by these two signals, and are sufficient to promote endodermal suberin. Mutation of these four transcription factors simultaneously through genome editing, lead to a dramatic reduction of suberin formation in response to both developmental and environmental signals. Most suberin mutants analyzed at physiological levels are also affected in another endodermal barrier made of lignin (Casparian strips), through a compensatory mechanism. Through the functional analysis of these four MYBs we generated plants allowing unbiased investigations of endodermal suberin function without accounting for confounding effects due to Casparian strip defects, and could unravel specific roles of suberin in nutrient homeostasis.


title: Enhanced Cas12a multi-gene regulation using a CRISPR array separator

abstract: The type V-A Cas12a protein can process its CRISPR array, a feature useful for multiplexed gene editing and regulation. However, CRISPR arrays often exhibit unpredictable performance due to interference between multiple crRNAs. Here, we report that Cas12a array performance is hypersensitive to the GC content of crRNA spacers, as high-GC spacers can impair activity of the downstream crRNA. We analyzed naturally occurring CRISPR arrays and observed that repeats always contain an AT-rich fragment that separates crRNAs; we term this fragment a CRISPR separator. Inspired by this observation, we designed short, AT-rich synthetic separators (synSeparators) that successfully removed the disruptive effects between crRNAs. We demonstrate enhanced simultaneous activation of seven endogenous genes in human cells using an array containing the synSeparator. These results elucidate a previously unknown feature of natural CRISPR arrays and demonstrate how nature-inspired engineering solutions can improve multi-gene control in mammalian cells.

category: synthetic biology


title: UNC-2 CaV2 channel localization at presynaptic active zones depends on UNC-10/RIM and SYD-2/Liprin-α in Caenorhabditis elegans.

abstract:
Presynaptic active zone proteins couple calcium influx with synaptic vesicle exocytosis. However, the control of presynaptic calcium channel clustering by active zone proteins is not completely understood. In a C. elegans forward genetic screen, we find that UNC-10/RIM (Rab3-interacting molecule) and SYD-2/Liprin- regulate presynaptic clustering of UNC-2, the CaV2 channel ortholog. We further quantitatively analyzed live animals using endogenously GFP-tagged UNC-2 and active zone components. Consistent with the interaction between RIM and CaV2 in mammals, the intensity and number of UNC-2 channel clusters at presynaptic terminals were greatly reduced in unc-10 mutant animals. To understand how SYD-2 regulates presynaptic UNC-2 channel clustering, we analyzed presynaptic localization of endogenous SYD-2, UNC-10, RIMB-1/RIM-BP (RIM binding protein), and ELKS-1. Our analysis revealed that while SYD-2 is the most critical for active zone assembly, loss of SYD-2 function does not completely abolish presynaptic localization of UNC-10, RIMB-1, and ELKS-1, suggesting an existence of SYD-2-independent active zone assembly. UNC-2 localization analysis in double and triple mutants of active zone components show that SYD-2 promotes UNC-2 clustering by partially controlling UNC-10 localization, and ELKS-1 and RIMB-1 also contribute to UNC-2 channel clustering. In addition, we find that core active zone proteins are unequal in their abundance. While the abundance of UNC-10 at the active zone is comparable to UNC-2, SYD-2 and ELKS-1 are twice more and RIMB-1 four times more abundant than UNC-2. Together our data show that UNC-10, SYD-2, RIMB-1, and ELKS-1 control presynaptic UNC-2 channel clustering in redundant yet distinct manners.

Significance StatementPrecise control of neurotransmission is dependent on the tight coupling of the calcium influx through voltage-gated calcium channels (VGCCs) to the exocytosis machinery at the presynaptic active zones. However, how these VGCCs are tethered to the active zone is incompletely understood. To understand the mechanism of presynaptic VGCC localization, we performed a C. elegans forward genetic screen and quantitatively analyzed endogenous active zones and presynaptic VGCCs. In addition to RIM (Rab3-interacting molecule), our study finds that SYD-2/Liprin- is critical for presynaptic localization of VGCCs. Yet, the loss of SYD-2, the master active zone scaffolding protein, does not completely abolish the presynaptic localization of the VGCC, showing that the active zone is a resilient structure assembled by redundant mechanisms.


title: Seroprevalence of Toxoplasma gondii among sylvatic rodents in Poland

abstract: Toxoplasma gondii is a significant pathogen affecting humans and animals. We conducted seromonitoring for T. gondii in four sylvatic rodent species in Poland. We report an overall seroprevalence of 5.5% (3.6% for Myodes glareolus and 20% for other vole species). Seroprevalence in bank voles varied significantly between host age and sex.

category: microbiology


title: The worm affair: Genetic diversity in two species of symbionts that co-occur in tubeworms from the Mediterranean Sea

abstract: The symbioses between the vestimentiferan tubeworms and their chemosynthetic partners (Gammaproteobacteria, Chromatiales, Sedimenticolaceae) hallmark the success of these organisms in hydrothermal vent and hydrocarbon seep deep-sea habitats. The fidelity of these associations varies, as both the hosts and the symbionts can be loose in partner choice. Some tubeworms may host distinct symbiont phylotypes, which often co-occur in a single host individual. To better understand the genetic basis for the  promiscuity of tubeworm symbioses, we curated and investigated metagenome-assembled genomes of two symbiont phylotypes (species, based on the average nucleotide identity <95%) in Lamellibrachia anaximandri, a vestimentiferan endemic to the Mediterranean Sea, in individuals collected from Palinuro hydrothermal vents (Italy) and hydrocarbon seeps (Eratosthenes seamount and Palmahim disturbance). Using comparative genomics, we show that mainly mobilome and defense mechanism-related features distinguish the symbiont genotypes. While many central metabolic functions are conserved in the tubeworm symbionts, nitrate respiration (Nar, Nap and Nas proteins) is modular, yet this modularity is not linked to speciation, but rather to local adaptation. Our results hint that variation in a single moonlighting protein may be responsible for the host-symbiont fidelity.


title: Commensal bacterial-derived retinoic acid primes host defense to intestinal infection

abstract: Interactions between the microbiota and mammalian host are essential for effective defense against pathogenic infection; however, the microbial-derived cues that mediate this beneficial relationship remain unclear. Here, we find that the intestinal epithelial cell (IEC)-associated commensal bacteria, Segmented Filamentous Bacteria (SFB), promotes early protection against the bacterial pathogen, Citrobacter rodentium, independently of CD4+ T cells. Global analyses demonstrated that SFB induced histone modifications in IECs at sites enriched for the retinoic acid receptor (RAR) motif. Interestingly, SFB-colonized mice exhibited greater expression of RAR targets during infection relative to germ-free mice, suggesting SFB may enhance defense through retinoic acid (RA) signaling. Consistent with this, supplementing germ-free mice with RA decreased pathogen levels. Further, mice with impaired RA-responsiveness in IECs displayed increased susceptibility to C. rodentium infection. RA was elevated in the intestine of mice colonized with SFB, indicating that the presence of commensal bacteria can modulate intestinal RA levels. However, this regulation by SFB was not dependent on mammalian RA production. Sequence analyses suggested that RA-generating enzymes are expressed by a subset of commensal bacteria. Remarkably, RA was produced by intestinal bacteria including SFB, and inhibiting RA signaling blocked SFB-induced protection against C. rodentium infection. These data collectively reveal RA as an unexpected microbiota-derived metabolite that primes innate intestinal defense and suggests that pre- and probiotic approaches to elevate RA could prevent or combat pathogenic infection.


title: Tau aggregates are RNA-protein assemblies that mis-localize multiple nuclear speckle components

abstract: Tau aggregates contribute to neurodegenerative diseases including frontotemporal dementia and Alzheimers disease (AD). Although RNA promotes tau aggregation in vitro, whether tau aggregates in cells contain RNA is unknown. We demonstrate in cell culture and mouse brains that both cytosolic and nuclear tau aggregates contain RNA, with enrichment for snRNAs and snoRNAs. Nuclear tau aggregates colocalize with and alter the composition, dynamics, and organization of nuclear speckles, which are membraneless organelles involved in pre-mRNA splicing. Moreover, several nuclear speckle components, including SRRM2, mislocalize to cytosolic tau aggregates in cells, mouse brains, and patient brains with AD, frontotemporal dementia (FTD), and corticobasal degeneration (CBD). Consistent with these alterations we observe the presence of tau aggregates is sufficient to alter pre-mRNA splicing. This work identifies tau alteration of nuclear speckles as a feature of tau aggregation that may contribute to the pathology of tau aggregates.


title: Modified E. coli strains enhance baculovirus production by elimination of aberrant transposition events

abstract: Baculovirus technology has been the most commonly used expression system for insect cells both due to its potential to generate a large amount of recombinant protein as well as the benefit of post-translational modifications. The most commonly used system to generate recombinant baculoviruses is the Tn7 transposition-based technology known as Bac-to-Bac. Although improvements have been made to this system to further improve quality and reproducibility of baculovirus production, recent data suggests that improved strains still have potential issues with contamination of non-recombinant baculovirus caused by improper transposition into a Tn7 site in the E. coli chromosome. Here we describe a new option for alteration of the E. coli genome to completely block the native Tn7 attachment site, leading to far fewer false positive bacmid colonies being selected and eliminating all risk of non-recombinant baculovirus production.


title: Caspase3-deficient cells require fibronectin for protection against autophagy-dependent death

abstract: Caspases are required for execution of apoptosis. However, in their absence, signals that typically induce apoptosis can still result in cell death. Our laboratory previously demonstrated that Casp3-deficient mouse embryonic fibroblasts (MEFs) have increased fibronectin (FN) secretion, and an adhesion-dependent survival advantage compared to wild type (WT) MEFs. Here, we show that FN is required for survival of Casp3-deficient MEFs following serum withdrawal. Furthermore, when FN is silenced, serum withdrawal-induced death is caspase-independent. However, procaspase-7 is cleaved, suggesting that MOMP is taking place. Indeed, in the absence of FN, cytochrome c release is increased following serum withdrawal in Casp3-deficient MEFs. Yet death does not correspond to cytochrome c release in Casp3-deficient MEFs. This is true both in the presence and absence of FN. Additionally, caspase-independent death is inhibited by Bcl-XL overexpression. These findings suggest that Bcl-XL is not inhibiting death through regulation of Bax/Bak insertion into the mitochondria, but through a different mechanism. One such possibility is autophagy and induction of autophagy is associated with caspase-independent death in Casp3-deficient cells. Importantly, when ATG5 is ablated in Casp3-deficient cells, autophagy is blocked and death is largely inhibited. Taken together, our data indicate that Casp3-deficient cells incapable of undergoing canonical serum withdrawal-induced apoptosis, are protected from autophagy-dependent death by FN-mediated adhesion.

category: cell biology


title: Inhibition of BMP and FGF signaling prior to wound epithelium formation leads to an aberrant regenerative response in teleost fish Poecilia latipinna

abstract:
The BMP and FGF pathways play a pivotal role in the successful regeneration of caudal fin of teleost fish. Individual inhibition of these pathways led to impaired caudal fin regeneration until the pharmacologic inhibitor of FGF (SU5402) and BMP (LDN193189) were metabolized off. Therefore, in the current study both these pathways were inhibited collectively wherein inhibition of BMP and FGF during the wound epithelium formation led to stalling of the process by bringing down the established levels of shh and runx2. In members of the treatment group, it was observed that, each blastema grows crouched rather than linear and the regrown lepidotrichia therefore remain tilted down. Amongst the other irregularities observed, the transition from epithelial to mesenchymal cells was found hindered due to down-regulation of snail and twist, brought about by BMP and FGF inhibition. Compromised expression of Snail and twist deranged the normal levels of cadherins causing disruption in the transition of cells. Lastly, blocking BMP and FGF delayed blastema formation and proliferation due to diminished levels of fgf2, fgf8, fgf10 and bmp6, while casp3 and casp9 levels remained heightened causing accelerated cell death. This study not only highlights the axial role of BMP and FGF pathways in regeneration but also accentuates the collaboration amongst the two. This ingenious coordination of signalling further reinforces the involvement of relaying messenger molecules between these crucial pathways.

Summary StatementBMP and FGF collectively control the process of blastema formation in fish and inhibiting them prior to wound epithelium stage leads to irrevocable damage to the regenerating caudal fin.


title: Transcriptome profiling of human pluripotent stem cell-derived cerebellar organoids reveals fastercommitment under dynamic conditions

abstract: Human induced pluripotent stem cells (iPSCs) have great potential for disease modeling. However, generating iPSC-derived models to study brain diseases remains a challenge. In particular, the ability to recapitulate cerebellar development in vitro is still limited. We presented a reproducible and scalable production of cerebellar organoids by using the novel Vertical-Wheel single-use bioreactors, in which functional cerebellar neurons were obtained. Here, we evaluate the global gene expression profiles by RNA sequencing (RNA-seq) across cerebellar differentiation, demonstrating a faster cerebellar commitment in this novel dynamic differentiation protocol. Furthermore, transcriptomic profiles suggest a significant enrichment of extracellular matrix (ECM) in dynamic-derived cerebellar organoids, which can better mimic the neural microenvironment and support a consistent neuronal network. Thus, an efficient generation of organoids with cerebellar identity was achieved for the first time in a continuous process using a dynamic system without the need of organoids encapsulation in ECM-based hydrogels, allowing the possibility of large-scale production and application in high-throughput processes. The presence of factors that favors angiogenesis onset was also detected in dynamic condition, which can enhance functional maturation of cerebellar organoids. We anticipate that large-scale production of cerebellar organoids may help developing models for drug screening, toxicological tests and studying pathological pathways involved in cerebellar degeneration.


title: Ubiquitin-Specific-Processing Protease 47, A Novel 53BP1 regulator

abstract: DNA double strand breaks (DSBs) are repair by homology-based repair or non-homologous end joining and multiple sub-pathways exist. 53BP1 is a key DNA double strand break repair protein that regulates repair pathway choice. It is key for joining DSBs during immunoglobulin heavy chain class switch recombination. Here we identify USP47 as a deubiquitylase that associates with and regulates 53BP1 function. USP47 loss results in 53BP1 instability in proteasome dependent manner, and defective 53BP1 ionizing radiation induced foci (IRIF). USP47 catalytic activity is required for maintaining 53BP1 protein level. Similar to 53BP1, USP47 depletion results in sensitivity to DNA DSB inducing agents and defective immunoglobulin CSR. Our findings establish a function for USP47 in DNA DSB repair at least partially through 53BP1.


title: Genome and transcriptome of a pathogenic yeast, Candida nivariensis

abstract: We present a highly contiguous genome and transcriptome of the pathogenic yeast, Candida nivariensis. We sequenced both the DNA and RNA of this species using both the Oxford Nanopore Technologies (ONT) and Illumina platforms. We assembled the genome into an 11.8 Mb draft composed of 16 contigs with an N50 of 886 Kb, including a circular mitochondrial sequence of 28 Kb. Using direct RNA nanopore sequencing and Illumina cDNA sequencing, we constructed an annotation of our new assembly, supplemented by lifting over genes from Saccharomyces cerevisiae and Candida glabrata.

category: genomics


title: Discovery of an IKK2 Site that Allosterically Controls Its Activation

abstract:
I{kappa}B kinase 2/{beta} (IKK2) is a critical regulator of inflammation which is inducibly activated by a host of stimuli. Aberrant activation of IKK2 is the leading cause of most inflammatory diseases and many associated cancers. Efforts to prevent these diseases by small-molecule inhibitors of IKK2 activity have not been successful. Most inhibitors developed for IKK2 are ATP-competitive, and they are toxic in vivo due to their off-target effects. Here we focused on identifying inhibitors to block IKK2 activity from an allosteric site, not the ATP-binding pocket. Using virtual screening, we first identified several candidate allosteric sites and screened for potential small-molecule binders, and then selected candidates inhibitory to IKK2 activity using cell-based functional assays. Hydrogen deuterium exchange coupled to mass-spectrometry (HDX-MS) and MS-MS assays revealed that a class of benzoyl conjugates of pyrrolidinedione covalently bound to a site located at the interface of the kinase domain (KD) and the helical domain (SDD), and inhibited IKK2 activation allosterically by preventing phosphorylation of its activation loop serines. Additionally, this class of inhibitor partially blocks IKK2s catalytic activity by enhancing dynamics within the ATP binding pocket and likely the general active site. Hydrogen deuterium exchange (HDX) experiments further revealed that while binding of substrate ATP perturbs only the local structure surrounding its binding site, binding to ATP-competitive or allosteric inhibitors induces structural perturbations in an expansive area including the helical domain. We propose that these allosteric sites can act as specific targets for the development of novel potent IKK inhibitors.

SIGNIFICANCEAberrant activation of IKK2 is the leading cause of most inflammatory diseases and many associated cancers. Most inhibitors developed for IKK2 are ATP-competitive, and they are toxic in vivo due to their off-target effects. By combination of virtual screening and cell-based functional assays, we identified small-molecule binders of the class of benzoyl conjugates of pyrrolidinedione that block IKK2 activity from an allosteric site through covalent attachment and could be specific only for IKK2. HDX-MS and MS-MS assays identified a binding pocket with a  Cys-Cys motif for these inhibitors, and revealed specific differences in IKK2 dynamics upon binding to substrate ATP vs ATP-competitive and allosteric inhibitors. Present work provides a framework for the development of allosteric inhibitors to combat IKK2-induced diseases inhibitors.

category: biochemistry


title: CNVpytor: a tool for CNV/CNA detection and analysis from read depth and allele imbalance in whole genome sequencing

abstract: Detecting copy number variations (CNVs) and copy number alterations (CNAs) based on whole genome sequencing data is important for personalized genomics and treatment. CNVnator is one of the most popular tools for CNV/CNA discovery and analysis based on read depth (RD). Herein, we present an extension of CNVnator developed in Python -- CNVpytor. CNVpytor inherits the reimplemented core engine of its predecessor and extends visualization, modularization, performance, and functionality. Additionally, CNVpytor uses B-allele frequency (BAF) likelihood information from single nucleotide polymorphism and small indels data as additional evidence for CNVs/CNAs and as primary information for copy number neutral losses of heterozygosity. CNVpytor is significantly faster than CNVnator--particularly for parsing alignment files (2 to 20 times faster)--and has (20-50 times) smaller intermediate files. CNV calls can be filtered using several criteria and annotated. Modular architecture allows it to be used in shared and cloud environments such as Google Colab and Jupyter notebook. Data can be exported into JBrowse, while a lightweight plugin version of CNVpytor for JBrowse enables nearly instant and GUI-assisted analysis of CNVs by any user. CNVpytor release and the source code are available on GitHub at https://github.com/abyzovlab/CNVpytor under the MIT license.

category: bioinformatics


title: Astrocytic VMAT2 in the developing prefrontal cortex is required for normal grooming behavior in mice

abstract: Astrocytes control synaptic activity by modulating peri-synaptic concentrations of ion and neurotransmitters including dopamine and, as such, can be critically involved in the modulation of some aspect of mammalian behavior. Here we report that genetic mouse model with a reduced medial prefrontal cortex (mPFC) dopamine levels, arising from astrocyte-specific conditional deletion of vesicular monoamine transporter 2 (VMAT2; aVMTA2cKO mice) shows excessive grooming and anxiety-like behaviour. The VMAT2cKO mice also develop a synaptic pathology, expressed through increased relative AMPA vs. NMDA receptor currents in synapses of the dorsal striatum receiving inputs from the mPFC. Importantly, behavioural and synaptic phenotypes are prevented by reexpression of mPFC VMAT2, showing that the deficits are driven by mPFC astrocytes. By analysing human tissue samples, we found that VMAT2 is expressed in human mPFC astrocytes, corroborating the potential translational relevance of our observations in mice. Our study shows that impairments of the astrocytic-control of dopamine in the mPFC has a profound impact on circuit function and behaviours, which resemble symptoms of anxiety disorders and obsessive compulsive disorder (OCD).


title: Structural insight into Pichia pastoris fatty acid synthase

abstract: Type I fatty acid synthases (FASs) are critical metabolic enzymes which are common targets for bioengineering in the production of biofuels and other products. Serendipitously, we identified FAS as a contaminant in a cryoEM dataset of virus-like particles (VLPs) purified from P. pastoris, an important model organism and common expression system used in protein production. From these data, we determined the structure of P. pastoris FAS to 3.1 [A] resolution. While the overall organisation of the complex was typical of type I FASs, we identified several differences in both structural and enzymatic domains through comparison with the prototypical yeast FAS from S. cerevisiae. Using focussed classification, we were also able to resolve and model the mobile acyl-carrier protein (ACP) domain, which is key for function. Ultimately, the structure reported here will be a useful resource for further efforts to engineer yeast FAS for synthesis of alternate products.


title: Eya1-dependent homeostasis of morphogenetic territories during collective cell migration

abstract: Tissue remodeling presents an enormous challenge to the stability of intercellular signaling domains. Here we investigate this issue during the development of the posterior lateral line in zebrafish. We find that the transcriptional co-activator and phosphatase Eya1, mutated in the branchio-oto-renal syndrome in humans, is essential for the homeostasis of the Wnt/{beta}-catenin and FGF morphogenetic domains during the collective migration of lateral-line primordial cells. Loss of Eya1 strongly diminishes the expression of Dkk1, expanding Wnt/{beta}-catenin activity in the primordium, which in turn abrogates FGFR1 expression. Deficits in Eya1 also abolishes the expression of the chemokine receptor CXCR7b, disrupting primordium migration. These results reinforce the concept that morphogenetic domains in dynamically remodeling tissues are formed by cellular states maintained by continuous signaling.


title: Obligate movements of an active site-linked surface domain control RNA polymerase elongation and pausing via a Phe-pocket anchor

abstract:
The catalytic trigger loop (TL) in RNA polymerase (RNAP) alternates between unstructured and helical hairpin conformations to admit and then contact the NTP substrate during transcription. In many bacterial lineages, the TL is interrupted by insertions of 2-5 surface-exposed, sandwich-barrel hybrid motifs (SBHMs) of poorly understood function. The 188-aa, 2-SBHM E. coli insertion, called SI3, occupies different locations in halted, NTP-bound, and paused transcription complexes, but its dynamics during active transcription and pausing are undefined. Here we report design, optimization, and use of a Cys-triplet reporter to measure the positional bias of SI3 in different transcription complexes and to determine the effect of restricting SI3 movement on nucleotide addition and pausing. We describe use of H2O2 as a superior oxidant for RNAP disulfide reporters. NTP binding biases SI3 toward the closed conformation whereas transcriptional pausing biases SI3 toward a swiveled position that inhibits TL folding. We find that SI3 must change location in every round of nucleotide addition and that restricting its movements inhibits both transcript elongation and pausing. These dynamics are modulated by a crucial Phe pocket formed by the junction of the two SBHM domains. This SI3 Phe pocket captures a Phe residue in the RNAP jaw when the TL unfolds, explaining the similar phenotypes of alterations in the jaw and SI3. Our findings establish that SI3 functions by modulating the TL folding to aid transcriptional regulation and to reset secondary channel trafficking in every round of nucleotide addition.

SIGNIFICANCERNA synthesis by cellular RNA polymerases depends on an active-site component called the trigger loop that oscillates between an unstructured loop that admits NTP substrates and a helical hairpin that positions the NTP in every round of nucleotide addition. In most bacteria, the trigger loop contains a large, surface-exposed insertion module that occupies different positions in halted transcription complexes but whose function during active transcription is unknown. By developing and using a novel disulfide reporter system, we find the insertion module also must alternate between in and out positions for every nucleotide addition, must swivel to a paused position to support regulation, and, in enterobacteria, evolved a "Phe pocket" that captures a key phenylalanine in the out and swivel positions.


title: Transcriptome profile of the zebrafish atrioventricular canal reveals molecular signatures of pacemaker and valve mesenchyme

abstract:
The atrioventricular canal (AVC) is an essential feature of the heart, which separates the atrium from the ventricle. During heart morphogenesis, it is a hub of molecular processes necessary for distinguishing heart regions; most importantly, for the formation of the AV conduction system and cardiac valves. To better understand the molecular processes underlying AVC development and function, we utilized the transgenic zebrafish line sqet31Et with EGFP expression in the AVC region to isolate this cell population by FACS and profiled its transcriptome by RNA-seq at 48 and 72 hours post fertilization (hpf). Compared to the rest of the heart, the AVC is enriched for the expression of molecular markers associated with mammalian AVC and AV node, including cx36.7 and cx45 which encode connexins forming low conductance gap junctions. Using the transgenic line Tg(myl7:mermaid) encoding the voltage-sensitive fluorescent protein, we showed that loss of function of Isl1 abolished the pacemaker-containing sinoatrial ring (SAR) and resulted in an erratic spread of excitation pattern from the SAR to AVC, indicating the dysfunction of the primary pacemaker. Concurrently, ectopic excitation in the AVC region was observed, suggesting that the zebrafish AVC possesses inherent automaticity although insufficient to replace the primary pacemaking activity of the SAR. Comparisons between the SAR and AVC transcriptomes revealed partially overlapping expression profiles of various ion channels and gap junction proteins which reflects their diversified functions. Lastly, we observed dynamic expression of epithelial-to-mesenchymal transition markers, as well as components of TGF-{beta}, Notch, and Wnt signaling pathways, which have been implicated in the formation of AVC conduction and cardiac valves. Our results uncovered the molecular hallmarks of the developing AVC region and demonstrated its role in the structural and electrophysiological separation between the atrium and ventricle.

Author summaryThe atrioventricular canal is a structure in the embryonic heart which separates the atrium from the ventricle. It gives rise to the AV node and cardiac valves - two important structures which ensure unidirectional blood flow between heart chambers. The AV node serves to regulate the propagation of electrical impulses between the two chambers, such that they contract consecutively. Using the zebrafish as model organism, we performed gene expression profiling and characterized electrical conduction patterns between the sinoatrial primary pacemaker and AVC. We discovered that the zebrafish AVC possesses similar features to the mammalian AV node, including slow conduction, inherent pacemaking activity, and the expression of conserved developmental genes. The molecular profile of the AVC is distinct from that of the sinoatrial pacemaker, which reflects their distinct roles. In addition, we found that genes regulating cardiac valve development were also expressed in the AVC, illustrating the importance of this region for establishing both electrophysiological and structural separation between the heart chambers. Besides establishing conserved aspects between zebrafish and mammalian conduction system, the data generated in this study constitutes a valuable resource for studying AVC development and discovery of novel candidate genes implicated in regulating cardiac rhythm and cardiac valve formation.


title: The emergence of cooperation by evolutionary generalization

abstract: In principle, any cooperative behaviour can be evolutionarily stable as long as it is incentivized by a reward from the beneficiary, a mechanism that has been called reciprocal cooperation. However, what makes this mechanism so powerful also has an evolutionary downside. Reciprocal cooperation faces a chicken-and-egg problem of the same kind as communication: it requires two functions to evolve at the same time -cooperation and response to cooperation. As a result, it can only emerge if one side first evolves for another reason, and is then recycled into a reciprocal function. Developping an evolutionary model in which we make use of machine learning techniques, we show that this occurs if the fact to cooperate and reward others cooperation become general abilities that extend beyond the set of contexts for which they have initially been selected. Drawing on an evolutionary analogy with the concept of generalization, we identify the conditions necessary for this to happen. This allows us to understand the peculiar distribution of reciprocal cooperation in the wild, virtually absent in most species -or limited to situations where individuals have partially overlapping interests, but pervasive in the human species


title: SARS-CoV-2 emerging complexity

abstract: The novel SARS_CoV-2 virus, prone to variation when interacting with spatially extended ecosystems and within hosts1 can be considered a complex dynamic system2. Therefore, it behaves creating several space-time manifestations of its dynamics. However, these physical manifestations in nature have not yet been fully disclosed or understood. Here we show 4-3 and 2-D space-time patterns of rate of infected individuals on a global scale, giving quantitative measures of transitions between different dynamical behaviour. By slicing the spatio-temporal patterns, we found manifestations of the virus behaviour such as cluster formation and bifurcations. Furthermore, by analysing the morphogenesis processes by entropy, we have been able to detect the virus phase transitions, typical of adaptive biological systems3. Our results for the first time describe the virus patterning behaviour processes all over the world, giving for them quantitative measures. We know that the outcomes of this work are still partial and more advanced analyses of the virus behaviour in nature are necessary. However, we think that the set of methods implemented can provide significant advantages to better analyse the viral behaviour in the approach of system biology4, thus expanding knowledge and improving pandemic problem solving.


title: Cortical representation variability aligns with in-class variances and can help one-shot learning

abstract: Learning invariance across a set of transformations is an important step in mapping high-dimensional inputs to a limited number of classes. After understanding the set of\ invariances, can a new class be learned from one element? We propose a representation which can facilitate such learning: if the variability in representing individual elements across trials aligns with the variability among different elements in a class, then class boundaries learned from the variable representations of one element should be representative of the entire class. In this study, we test whether such a representation occurs in mouse visual systems. We use Neuropixels probes recording single unit activity in mice observing 200 repeats of natural movies taken from a set of 9 continuous clips. We observe that the trial-by-trial variability in the representation of individual frames is well aligned to the variability in representation of multiple frames from the same clip, but not well aligned to the variability among frames from different clips. Thus, the variable representations of images in the mouse cortex can be efficiently used to classify images into their clips. We compare these representations to those in artificial neural networks. We find that, when introducing noise in networks trained for classification (both feed-forward and recurrent networks), the variability in the representation of elements aligns with the in-class variance. The networks which best reproduce the in-vivo observed directions of variability were those trained on a hierarchical classification task. Taken together, these results point to a solution which the cortex can use for one-shot learning of a class: by using noise as a mechanism for generalization. This is a potential computational explanation for the high level of noise observed in the cortex.


title: Development of white matter tracts between and within the dorsal and ventral streams

abstract:
The degree of interaction between the ventral and dorsal visual streams has been discussed in multiple scientific domains for decades. Recently, several white matter tracts that directly connect cortical regions associated with the dorsal and ventral streams have become possible to study due to advancements in automated and reproducible methods. The developmental trajectory of this set of tracts, here referred to as the posterior vertical pathway (PVP), has yet to be described. We propose an input-driven model of white matter development and provide evidence for the model by focusing on the development of the PVP. We used reproducible, cloud-computing methods and diffusion imaging from adults and children (ages 5-8 years) to compare PVP development to that of tracts within the ventral and dorsal pathways. PVP microstructure was more adult-like than dorsal stream microstructure, but less adult-like than ventral stream microstructure. Additionally, PVP microstructure was more similar to the microstructure of the ventral than the dorsal stream and was predicted by performance on a perceptual task in children. Overall, results suggest a potential role for the PVP in the development of the dorsal visual stream that may be related to its ability to facilitate interactions between ventral and dorsal streams during learning. Our results are consistent with the proposed model, suggesting that the microstructural development of major white matter pathways is related, at least in part, to the propagation of sensory information within the visual system.

Significance StatementUnderstanding white matter development is important to building predictive models that can inform interventions and targeted educational methods. We propose and provide evidence for an input-driven model of white matter development. We tested an uncharacterized aspect of human brain development. Namely, how the recently described posterior vertical white matter tracts develop. Our results suggest a developmental progression along the known, direct anatomical connections from posterior visual areas to anterior ventral and dorsal areas. Our results suggest fundamental biological mechanisms that clarify the role of white matter in predicting human learning and behavior.


title: Selection and Validation of Reference Genes Desirable for Gene Expression Analysis by qRT-PCR on Seed Germination of Castanea henryi

abstract: Seed germination is the beginning of the plants life cycle, and seed biology is one of the most extensively researched areas in plant physiology, however, Castanea henryi as an important seed plant, the stable internal reference gene during germination is not clear. In this study, seven candidate genes (TUA, TUB, TIF, UBC, RPL21, RPL30, RPL34) were screened out from transcriptome data, we analyzed the expression of seven candidate reference genes in C. henryi at different germination stages with RT-qPCR, and using common algorithms including NormFinder, geNorm and BestKeeper to evaluate the candidate genes stability. The results showed that RPL34 and RPL30 were selected as the most stable genes by NormFinder; TIF was the most stable gene identified by BestKeeper; RPL34 and RPL21 were the most stable genes ranked by geNorm, and TUB was the most unstable gene identified by all of the three software. The RPL34 gene was used as the reference gene, to detected the expression trend of two starch synthetase genes SS1 and SS2 during germination by RT-qPCR, the results of RT-qPCR and transcriptome sequencing were basically consistent, which verified the stability of RPL34 candidate gene. Our result is not only showed functional genes for germination of C. henryi seeds and provide useful guidelines for the selection of reliable reference genes for the normalization of RT- qPCR data for germination of seed plants.


title: Pore structure controls stability and molecular flux in engineered protein cages

abstract:
Protein cages are a common architectural motif used by living organisms to compartmentalize and control biochemical reactions. While engineered protein cages have recently been featured in the construction of nanoreactors and synthetic organelles, relatively little is known about the underlying molecular parameters that govern cage stability and molecular flux through their pores. In this work, we systematically designed a 24-member library of protein cage variants based on the T. maritima encapsulin, each featuring pores of different size and charge. Twelve encapsulin pore variants were successfully assembled and purified, including eight designs with exceptional and prolonged thermal stability. While pores lined with negatively charged residues resulted in more robust assemblies than their corresponding positively charged variants, we were able to form stable assemblies covering a full range of pore sizes and charges, as observed in seven new cryo-EM structures of pore variants elucidated at resolutions between 2.5-3.6 [A]. Alongside these structures, molecular dynamics simulations and stopped flow kinetics experiments reveal the importance of considering both pore size and surface charge, together with flexibility and rate determining steps, when designing protein cages for controlling molecular flux.

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=176 SRC="FIGDIR/small/428512v3_ufig1.gif" ALT="Figure 1">
View larger version (70K):
org.highwire.dtl.DTLVardef@725e76org.highwire.dtl.DTLVardef@97a497org.highwire.dtl.DTLVardef@1b6ea1forg.highwire.dtl.DTLVardef@1c4d17f_HPS_FORMAT_FIGEXP  M_FIG C_FIG


title: The post-translational modification landscape of commercial beers

abstract: Beer is one of the most popular beverages worldwide. As a product of variable agricultural ingredients and processes, beer has high molecular complexity. We used DIA/SWATH-MS to investigate the proteomic complexity and diversity of 23 commercial Australian beers. While the overall complexity of the beer proteome was modest, with contributions from barley and yeast proteins, we uncovered a very high diversity of post-translational modifications (PTMs), especially proteolysis, glycation, and glycosylation. Proteolysis was widespread throughout barley proteins, but showed clear site-specificity. Oligohexose modifications were common on lysines in barley proteins, consistent with glycation by maltooligosaccharides released from starch during malting or mashing. O-glycosylation consistent with oligomannose was abundant on secreted yeast glycoproteins. We developed and used data analysis pipelines to efficiently extract and quantify site-specific PTMs from SWATH-MS data, and showed incorporating these features into proteomic analyses extended analytical precision. We found that the key differentiator of the beer glyco/proteome was the brewery, with beer from independent breweries having a distinct profile to beer from multinational breweries. Within a given brewery, beer styles also had distinct glyco/proteomes. Targeting our analyses to beers from a single brewery, Newstead Brewing Co., allowed us to identify beer style-specific features of the glyco/proteome. Specifically, we found that proteins in darker beers tended to have low glycation and high proteolysis. Finally, we objectively quantified features of foam formation and stability, and showed that these quality properties correlated with the concentration of abundant surface-active proteins from barley and yeast.


title: Transcription activation is enhanced by multivalent interactions independent of liquid-liquid phase separation

abstract: Transcription factors (TFs) consist of a DNA binding and an activation domain (AD) that are considered to be independent and exchangeable modules. However, recent studies conclude that also the physico-chemical properties of the AD can control TF assembly at chromatin by driving a phase separation into transcriptional condensates. Here, we dissected transcription activation by comparing different synthetic TFs at a reporter gene array with real-time single-cell fluorescence microscopy readouts. In these experiments, binding site occupancy, residence time and co-activator recruitment in relation to multivalent TF interactions were compared. While phase separation propensity and activation strength of the AD were correlated, the actual formation of liquid-like TF droplets had a neutral or inhibitory effect on transcription activation. Rather, we conclude that multivalent AD mediated interactions increase the transcription activation capacity of a TF by stabilizing chromatin binding and mediating the recruitment of co-activators independent of phase separation.


title: Transcription activation is enhanced by multivalent interactions independent of phase separation


title: Single-cell transcriptomics defines heterogeneity of epicardial cells and fibroblasts within the infarcted heart

abstract: In the adult heart, the epicardium becomes activated after injury, contributing to cardiac healing by secretion of paracrine factors. Here we analyzed by single-cell RNA sequencing combined with RNA in situ hybridization and lineage tracing of WT1+ cells the cellular composition, location, and hierarchy of epicardial stromal cells (EpiSC) in comparison to activated myocardial fibroblasts/stromal cells in infarcted mouse hearts. We identified 11 transcriptionally distinct EpiSC populations, that can be classified in three groups each containing a cluster of proliferating cells. Two groups expressed cardiac specification makers and sarcomeric proteins suggestive of cardiomyogenic potential. Transcripts of HIF-1 and HIF-responsive genes were enriched in EpiSC consistent with an epicardial hypoxic niche. Expression of paracrine factors was not limited to WT1+ cells but was a general feature of activated cardiac stromal cells. Our findings provide the cellular framework by which myocardial ischemia may trigger in EpiSC the formation of cardioprotective/regenerative responses.


title: Tethered NOS-3, a nematode Nanos RNA-binding protein, enhances reporter expression and mRNA stability

abstract: Robust methods are critical for testing the in vivo regulatory mechanism of RNA binding proteins. Here we report improvement of a protein-mRNA tethering assay to probe the function of an RNA binding protein in its natural context within the C. elegans adult germline. The assay relies on a dual reporter expressing two mRNAs from a single promoter and resolved by trans-splicing. The gfp reporter 3UTR harbors functional binding elements for {lambda}N22 peptide, while the mCherry reporter 3UTR carries mutated nonfunctional elements. This strategy enables internally controlled quantitation of reporter protein by immunofluorescence and mRNA by smFISH. To test the new system, we analyzed a C. elegans Nanos protein, NOS-3, which serves as a post-transcriptional regulator of germ cell fate. Unexpectedly, tethered NOS-3 enhanced reporter expression. We confirmed this enhancement activity with a second reporter engineered at an endogenous germline gene. NOS-3 enhancement of reporter expression was associated with its N-terminal intrinsically disordered region, not its C-terminal zinc fingers. RNA quantitation revealed that tethered NOS-3 enhances stability of the reporter mRNA. We suggest that this direct NOS-3 enhancement activity may explain a paradox: classically Nanos proteins are expected to repress RNA, but nos-3 had been found to promote gld-1 expression, an effect that could be direct. Regardless, the new dual reporter dramatically improves in situ quantitation of reporter expression after RBP tethering to determine its molecular mechanism in a multicellular tissue.


title: Arabidopsis inositol polyphosphate kinases IPK1 and ITPK1 modulate crosstalks between SA-dependent immunity and phosphate-starvation responses

abstract: The propensity for polyphosphorylation makes myo-inositol derivatives, the inositol polyphosphates (InsPs), especially phytic acid or inositol hexakisphosphate (InsP6) the major form of phosphate storage in plants. Acts of pyrophosphorylation on InsP6 generates InsP7 or InsP8 containing high-energy phosphoanhydride bonds that are harnessed during energy requirements of a cell. Also implicated as co-factors for several phytohormone signaling networks, InsP7/InsP8 modulate key developmental processes. With recent identification as the common moeity for transducing both jasmonic acid (JA) and phosphate-starvation responses (PSR), InsP8 is the classic example of a metabolite that may moonlight crosstalks to different cellular pathways during diverse stress adaptations. We show here that Arabidopsis thaliana INOSITOL PENTAKISPHOSPHATE 2-KINASE (IPK1), INOSITOL 1,3,4-TRISPHOSPHATE 5/6-KINASE 1 (ITPK1), and DIPHOSPHOINOSITOL PENTAKISPHOSPHATE KINASE 2 (VIH2), but not other InsP-kinases, suppress basal salicylic acid (SA)-dependent immunity. In ipk1, itpk1 or vih2 mutants, elevated endogenous SA levels and constitutive activation of defense signaling lead to enhanced resistance against the virulent Pseudomonas syringae pv tomato DC3000 (PstDC3000) strain. Our data reveal that activated SA-signaling sectors in these mutants modulate expression amplitudes of phosphate-starvation inducible (PSI)-genes, reported earlier. In turn, via mutualism the heightened basal defenses in these mutants require upregulated PSI-gene expressions likely highlighting the increased demand of phosphates required to support immunity. We demonstrate that SA is induced in phosphate-deprived plants, however its defense-promoting functions are likely diverted to PSR-supportive roles. Overall, our investigations reveal selective InsPs as crosstalk mediators among diverse signaling networks programming stress-appropriate adaptations.

category: plant biology


title: Evaluation of the rapidBACpro(R) II kit for the rapid identification of microorganisms directly from blood cultures using MALDI-TOF MS

abstract:
ObjectivesIdentification of microorganisms directly from blood cultures (BCs) using MALDI-TOF MS has shown to be the application with most impact in this methodology. In this study, a novel commercial method, the rapidBACpro(R) II, was evaluated in four clinical microbiology laboratories.

MethodsPositive blood culture samples (n=801) were processed using the rapidBACpro(R) II kit and then compared with routine gold standard. A subset of monomicrobial BCs (n=560) were analyzed in parallel with the Sepsityper(R) kit (Bruker Daltonics, Bremen, Germany) and compared with the rapidBACpro(R) II kit. In addition, the rapidBACpro(R) II kit was also compared with two different in-house methods.

ResultsOverall, 80.0% of the monomicrobial isolates (609/761) were correctly identified by the rapidBACpro(R) II kit at the species level (92.3% of the Gram negative and 72.4% of the Gram positive bacteria). The comparison with the Sepsityper(R) kit yielded higher rates of correct species-level identification provided by the rapidBACpro(R) II kit for all categories (p>0.0001) except for yeasts identified with score values >1.7. It also proved superior to the ammonium chloride method (p>0.0001) but the differential centrifugation method allowed higher rates of correct identification for Gram negative bacteria (p>0.1).

ConclusionsThe rapidBACpro(R) II kit allowed a high rate of microorganisms correctly identified. The percentage of accurate species-level identification of Gram positive bacteria was particularly noteworthy in comparison with other commercial and in-house methods. This fact was especially interesting in the case of Staphylococcus sp. and Streptococcus sp. in order to elucidate their clinical impact, for example in device-associated bacteremia.


title: Gas6 drives Zika virus-induced neurological complications in humans and congenital syndrome in immunocompetent mice

abstract: Zika virus (ZIKV) has the ability to cross placental and brain barriers, causing congenital malformations in neonates and neurological disorders in adults. However, the pathogenic mechanisms of ZIKV-induced neurological complications in adults and congenital malformations remain unknown. Gas6 is a soluble TAM receptor ligand able to promote flavivirus internalization and downregulation of immune responses. Here we demonstrate high Gas6 levels in the serum of patients with neurological complications which correlated with downregulation of genes associated with the type I IFN responses as consequence of Socs1 upregulation. Gas6 gamma-carboxylation is essential for ZIKV replication in monocytes, the main source of this protein. Gas6 also facilitates ZIKV replication in adult immunocompetent mice enabled susceptibility to transplacental infection and congenital malformations. Our data thus indicate that ZIKV promotes the upregulation of its ligand Gas6, which contributes to viral infectivity and drives the development of severe adverse outcomes during ZIKV infection.


title: Elevation-related climate trends dominate fungal co-occurrence patterns on Mt. Norikura, Japan

abstract:
Although many studies have explored patterns of fungal community diversity and composition along various environmental gradients, the trends of co-occurrence networks across similar gradients remain elusive. Here, we constructed co-occurrence networks for fungal community along a 2300 m elevation gradient on Mt Norikura, Japan, hypothesizing a progressive decline in network connectivity with elevation due to reduced niche differentiation caused by declining temperature and ecosystem productivity. Results agreed broadly with predictions, with an overall decline in network connectivity with elevation for all fungi and the high abundance phyla. However, trends were not uniform with elevation, most decline in connectivity occurred between 700 m and 1500 m elevation, remaining relatively stable above this. Temperature and precipitation dominated variation in network properties, with lower mean annual temperature (MAT) and higher mean annual precipitation (MAP) at higher elevations giving less network connectivity, largely through indirect effects on soil properties. Among keystone taxa that played crucial roles in network structure, the variation in abundance along the elevation gradient was also controlled by climate and also pH. Our findings point to a major role of climate gradients in mid-latitude mountain areas in controlling network connectivity. Given the importance of the orographic precipitation effect, microbial community trends seen along elevation gradients might not be mirrored by those seen along latitudinal temperature gradients.

ImportanceAlthough many studies have explored patterns of fungal community diversity and composition along various environmental gradients, it is unclear how the topological structure of co-occurrence networks shifts across environmental gradients. In this study, we found that the connectivity of the fungal community decreased with increasing elevation, and that climate was the dominant factor regulating co-occurrence patterns, apparently acting indirectly through soil characteristics. Assemblages of keystone taxa playing crucial roles in network structure varied along the elevation gradient and were also largely controlled by climate. Our results provide insight into the shift of soil fungal community co-occurrence structure along elevational gradients, and possible driving mechanisms behind this.

Graphic abstract

O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=159 SRC="FIGDIR/small/428196v1_ufig1.gif" ALT="Figure 1">
View larger version (27K):
org.highwire.dtl.DTLVardef@12e555aorg.highwire.dtl.DTLVardef@e5c4d7org.highwire.dtl.DTLVardef@de00bdorg.highwire.dtl.DTLVardef@102967c_HPS_FORMAT_FIGEXP  M_FIG C_FIG


title: A trigger phosphodiesterase modulates the global c-di-GMP pool, motility and biofilm formation in Vibrio parahaemolyticus.

abstract:
Vibrio parahaemolyticus cells transit from free swimming to surface adapted lifestyles, such as swarming colonies and three-dimensional biofilms. These transitions are regulated by sensory modules and regulatory networks that involve the second messenger cyclic dimeric guanosine monophosphate (c-di-GMP). In this work, we show that a previously uncharacterized c-di-GMP phosphodiesterase (VP1881) from V. parahaemolyticus plays an important role in modulating the c-di-GMP pool. We found that the product of VP1881 promotes its own expression when the levels of c-di-GMP were low or when the phosphodiesterase was catalytically inactive. This behavior has been observed in a class of c-di-GMP receptors called Trigger phosphodiesterases, hence we named the product of VP1881 TpdA, for Trigger phosphodiesterase A. The absence of tpdA showed a negative effect on swimming motility while its overexpression from an IPTG inducible promoter showed a positive effect on both swimming and swarming motility, and a negative effect on biofilm formation. Changes in TpdA abundance altered the expression of representative polar and lateral flagellar genes as well as the biofilm related gene cpsA. Our results also revealed that autoactivation of the native PtpdA promoter is sufficient to alter c-di-GMP signaling responses such as swarming and biofilm formation in V. parahaemolyticus, an observation that could have important implications in the dynamics of this social behaviors.

ImportanceC-di-GMP trigger phosphodiesterases (PDEs) could play a key role in controlling the heterogeneity of biofilm-matrix composition, a property that endows characteristics that are potentially relevant for sustaining integrity and functionality of biofilms in a variety of natural environments. Trigger PDEs are not always easy to identify based on their sequence, hence not many examples of these type of signaling proteins have been reported in the literature. Here we report on the identification of a novel trigger PDE in V. parahaemolyticus and provide evidence suggesting that its autoactivation could play an important role in the progression of swarming motility and biofilm formation, multicellular behaviors that are important for the survival and dissemination of this environmental pathogen.


title: A novel adhesive complex at the base of intestinal microcilli

abstract: Intestinal epithelial cells form dense arrays of microvilli at the apical membrane to enhance their functional capacity. Microvilli contain a protocadherin-based intermicrovillar adhesion complex localized at their tips which regulates microvillar length and packaging. Here, we identify a second adhesive complex in microvilli of intestinal epithelial cells. This complex is localized at the basal region of microvilli and consists of the adhesion molecule TMIGD1, the phosphoprotein EBP50 and the F-actin - plasma membrane cross-linking protein ezrin. Ternary complex formation requires unmasking of the EBP50 PDZ domains by ezrin binding and is strongly enhanced upon mutating Ser162 located in PDZ domain 2 of EBP50. Dephosphorylation of EBP50 at S162 is mediated by PP1, a serine/threonine phosphatase localized at the microvillar base and involved in ezrin phosphocycling. Importantly, the binding of EBP50 to TMIGD1 enhances the dynamic turnover of EBP50 at microvilli in a Ser162 phosphorylation-dependent manner. We identify an adhesive complex at the microvillar base and propose a potential mechanism that regulates microvillar dynamics in enterocytes.


title: A novel adhesive complex at the base of intestinal microvilli


title: Revealing the human mucinome

abstract: Mucin domains are densely O-glycosylated modular protein domains found in a wide variety of cell surface and secreted proteins. Mucin-domain glycoproteins are key players in a host of human diseases, especially cancer, but the scope of the mucinome remains poorly defined. Recently, we characterized a bacterial mucinase, StcE, and demonstrated that an inactive point mutant retains binding selectivity for mucins. In this work, we leveraged inactive StcE to selectively enrich and identify mucins from complex samples like cell lysate and crude ovarian cancer patient ascites fluid. Our enrichment strategy was further aided by an algorithm to assign confidence to mucin-domain glycoprotein identifications. This mucinomics platform facilitated detection of hundreds of glycopeptides from mucin domains and highly overlapping populations of mucin-domain glycoproteins from ovarian cancer patients. Ultimately, we demonstrate our mucinomics approach can reveal key molecular signatures of cancer from in vitro and ex vivo sources.


title: Oscillations support co-firing of neurons in the service of human memory formation

abstract: Theta and gamma oscillations in the medial temporal lobe are suggested to play a critical role for human memory formation via establishing synchrony in neural assemblies. Arguably, such synchrony facilitates efficient information transfer between neurons and enhances synaptic plasticity, both of which benefit episodic memory formation. However, to date little evidence exists from humans that would provide direct evidence for such a specific role of theta and gamma oscillations for episodic memory formation. Here we investigate how oscillations shape the temporal structure of neural firing during memory formation in the medial temporal lobe. We measured neural firing and local field potentials in human epilepsy patients via micro-wire electrode recordings to analyze how brain oscillations promote co-incidences of firing between neurons during successful and unsuccessful encoding of episodic memories. The results show that phase-coupling of neurons to faster theta and gamma oscillations correlates with co-firing at short latencies ([~]20-30 ms) and occurs during successful memory formation. Phase-coupling at slower oscillations in these same frequency bands, in contrast, correlates with longer co-firing latencies and occurs during memory failure. Thus, our findings provide evidence which implicate neural oscillations into the synchronization of neural firing in the medial temporal lobe during the encoding of episodic memories.

category: neuroscience


title: Oscillations support short latency co-firing of neurons during human episodic memory formation.


title: Age dependency and lateralization in the three branches of the human superior longitudinal fasciculus

abstract: The superior longitudinal fascicle/fasciculus (SLF) is a major white matter tract connecting the frontal and parietal cortices in humans. Although the SLF has often been analyzed as a single entity, several studies have reported that the SLF is segregated into three distinct branches (SLF I, II, and III). They have also reported the right lateralization of the SLF III volume and discussed its relationship with lateralized cortical functions in the fronto-parietal network. However, to date, the homogeneity or heterogeneity of the age dependency and lateralization properties of SLF branches have not been fully clarified. Through this study, we aimed to clarify the age dependency and lateralization of SLF I-III by analyzing diffusion-weighted MRI (dMRI) and quantitative R1 (qR1) map datasets collected from a wide range of age groups, mostly comprising right-handed children, adolescents, adults, and seniors (6 to 81 years old). The age dependency in dMRI measurement (fractional anisotropy, FA) was heterogeneous among the three SLF branches, suggesting that these branches are regulated by distinct developmental and aging processes. Lateralization analysis on SLF branches revealed that the right SLF III was larger than the left SLF III in adults, replicating previous reports. FA measurement also suggested that, in addition to SLF III, SLF II was lateralized to the right hemisphere in adolescents and adults. We further found a left lateralization of SLF I in qR1 data, a microstructural measurement sensitive to myelin levels, in adults. These findings suggest that the SLF sub-bundles are distinct entities in terms of age dependency and lateralization.


title: Unique Protein Interaction Networks Define The Chromatin Remodeling Module of The NuRD Complex

abstract: The combination of four proteins and their paralogues including MBD2/3, GATAD2A/B, CDK2AP1, and CHD3/4/5, which we refer to as the MGCC module, form the chromatin remodeling module of the Nucleosome Remodeling and Deacetylase (NuRD) complex, a gene repressor complex. Specific paralogues of the MGCC subunits such as MBD2 and CHD4 are amongst the key repressors of adult-stage fetal globin and provide important targets for molecular therapies in beta ({beta})-thalassemia. However, mechanisms by which the MGCC module acquires paralogue-specific function and specificity have not been addressed to date. Understanding the protein-protein interaction (PPI) network of the MGCC subunits is essential in defining underlying mechanisms and developing treatment strategies. Therefore, using pulldown followed by mass spectrometry analysis (PD-MS) we report a proteome-wide interaction network of the MGCC module in a paralogue-specific manner. Our data also demonstrate that the disordered C-terminal region of CHD3/4/5 is a gateway to incorporate remodeling activity into both the ChAHP (CHD4, ADNP, HP1{gamma}) and NuRD complexes in a mutually exclusive manner. We define a short aggregation prone region (APR) within the C-terminal segment of GATAD2B that is essential for the interaction of CHD4 and CDK2AP1 with the NuRD complex. Finally, we also report an association of CDK2AP1 with the Nuclear Receptor Co-Repressor (NCOR) complex. Overall, this study provides insight into the possible mechanisms through which the MGCC module can achieve specificity and diverse biological functions.


title: Machine Translation between paired Single Cell Multi Omics Data

abstract: Single-cell multi-omics technologies enable profiling of several data-modalities from the same cell. We designed LIBRA, a Neural Network based framework, for learning translations between paired multi-omics profiles into a shared latent space. We demonstrate LIBRA to be state-of-the-art for multi-omics clustering. In addition, LIBRA is more robust with decreasing cell-numbers compared with existing tools. Training LIBRA on paired data-sets, LIBRA predicts multi-omic profiles using only a single data-modality from the same biological system.


title: Design principles of plant root morphogenesis

abstract: Plants grow roots to adjust their bodies to dynamic changes in the surrounding environment. How do plant roots emerge from the stem cell reservoir during embryogenesis is however poorly understood. Here, we present a bottom-up strategy to address this challenge by combining empirical observations with advanced computer modeling techniques. We demonstrate that the anisotropy of root growth results from differential growth rates of adjacent tissues, whereas the root meristem development incorporates a multi-level feedback loop between complex transport network of phytohormone auxin, auxin-dependent cell growth and cytoskeleton rearrangements. In silico model predictions are in close agreement with in vivo patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Our findings reveal a minimal set of design principles connecting tissue mechanics, cell anisotropy, and directional transport that are sufficient for self-organization of the root meristem shape. A mobile auxin signal transported through immobile cells orchestrates polarity and growth mechanics to instruct the morphogenesis of an independent organ.


title: A coupled mechano-biochemical framework for root meristem morphogenesis


title: Improved spatio-temporal measurements of visually evoked fields using optically-pumped magnetometers

abstract: Recent developments in performance and practicality of optically pumped magnetometers have enabled new capabilities in non-invasive brain function mapping through magnetoencephalography. In particular the lack of need of cryogenic operating conditions allows for more flexible placement of the sensor heads closer to the brain surface, leading to improved spatial measurement resolution and increased source localisation capabilities. Through the recording of visually evoked brain fields (VEF), we demonstrate that the closer sensor proximity can be further exploited to improve the temporal resolution. We use optically pumped magnetometers (OPMs), and for reference superconducting quantum interference devices (SQUIDs), to measure brain responses to standard flash and pattern reversal stimuli. We find highly reproducible signals with consistency across multiple healthy participants, stimulus paradigms and sensor modalities. The temporal resolution advantage of OPMs is manifest in a fourfold improvement of the ratio of magnetic signal peak height to temporal width, compared to SQUIDs. The resulting capability of improved spatio-temporal signal tracing is illustrated by simultaneous vector recordings of VEFs in the primary (V1) and associative (V2) visual cortex, where a time lag on the order of 10-20 ms is consistently found. This paves the way for further studies of spatio-temporal neurophysiological signal tracking in visual stimulus processing and other brain responses with potentially far-reaching consequences for time-critical mapping of functionality in the healthy and pathological brains.