Who discovered mitochondrial DNA?
Mitochondrial matrix
The cytosolic, intermembrane space, compartment has a water content of 3.8 μl/mg protein, while the mitochondrial matrix 0.8 μl/mg protein. It is not known how mitochondria maintain osmotic balance across the inner mitochondrial membrane, although the membrane contains aquaporins that are believed to be conduits for regulated water transport. Mitochondrial matrix has a pH of about 7.8. Mitochondrial DNA was discovered by Nash and Margit in 1963. One to many double stranded mainly circular DNA is present in mitochondrial matrix. Mitochondrial DNA is 1% of total DNA of a cell. It is rich in Guanine and Cytosine content. Mitochondria of mammals have 55s ribosomes.
Allan Wilson
In the early 1980s, Wilson further refined traditional anthropological thinking with his work with PhD students Rebecca Cann and Mark Stoneking on the so-called "Mitochondrial Eve" hypothesis. In his efforts to identify informative genetic markers for tracking human evolutionary history, he focused on mitochondrial DNA (mtDNA) – genes that are found in mitochondria in the cytoplasm of the cell outside the nucleus. Because of its location in the cytoplasm, mtDNA is passed exclusively from mother to child, the father making no contribution, and in the absence of genetic recombination defines female lineages over evolutionary timescales. Because it also mutates rapidly, it is possible to measure the small genetic differences between individual within species by restriction endonuclease gene mapping. Wilson, Cann, and Stoneking measured differences among many individuals from different human continental groups, and found that humans from Africa showed the greatest inter-individual differences, consistent with an African origin of the human species (the Recent African origin of modern humans hypothesis). The data further indicated that all living humans shared a common maternal ancestor, who lived in Africa only a few hundreds of thousands of years ago. This common ancestor became widely known in the media and popular culture as the Mitochondrial Eve. This had the unfortunate and erroneous implication that only a single female lived at that time, when in fact the occurrence of a coalescent ancestor is a necessary consequence of population genetic theory, and the Mitochondrial Eve would have been only one of many humans (male and female) alive at that time. This finding was, like his earlier results, not readily accepted by anthropologists. Conventional hypothesis was that various human continental groups had evolved from diverse ancestors, over several million of years since divergence from chimpanzees. The mtDNA data, however, strongly suggested that all humans descended from a common, quite recent, African mother.
DNA paternity testing
Comparing the DNA sequence of an individual to that of another individual can show whether one of them was derived from the other. However, DNA paternity tests are not currently 100% accurate. Specific sequences are usually looked at to see whether they were copied verbatim from one of the individual's genome to the other. If that was the case, then the genetic material of one individual could have been derived from that of the other (i.e. one is the parent of the other). Besides the nuclear DNA in the nucleus, the mitochondria in the cells also have their own genetic material termed the mitochondrial DNA. Mitochondrial DNA comes only from the mother, without any shuffling.
Mitochondrial disease
The first pathogenic mutation in mitochondrial DNA was identified in 1988; from that time to 2016, around 275 other disease-causing mutations were identified.
Mark Stoneking
Stoneking came to prominence both in the academic and media circles with his work on mitochondrial DNA variation among different human populations. He started under the supervision of Allan Wilson and following the pioneering work of his senior graduate student, Rebecca Cann. Cann had collected data from different human populations, including those of Asians, Africans, and Europeans. Then Stoneking added data from aboriginal Australians and New Guineans. In 1987, after a year of pending, their paper was published in "Nature" in which their findings indicated that all living humans were descended through a single mother, who lived ~200,000 years ago in Africa. The common hypothetical mother is dubbed Mitochondrial Eve, and the concept directly implies recent African origin of modern humans, hence, the underpinning of the so-called "Recent Out of Africa" theory. In spite of criticisms, and religious antagonisms, even after two decades he still holds this view to be as valid as any scientific theory since a number independent research also corroborates their original human mtDNA phylogenetic tree.Stoneking has appeared in
Recent African origin of modern humans
In the 1980s, Allan Wilson together with Rebecca L. Cann and Mark Stoneking worked on genetic dating of the matrilineal most recent common ancestor of modern human populations (dubbed "Mitochondrial Eve"). To identify informative genetic markers for tracking human evolutionary history, Wilson concentrated on mitochondrial DNA (mtDNA), passed from mother to child. This DNA material mutates quickly, making it easy to plot changes over relatively short times. With his discovery that human mtDNA is genetically much less diverse than chimpanzee mtDNA, Wilson concluded that modern human populations had diverged recently from a single population while older human species such as Neanderthals and "Homo erectus" had become extinct. With the advent of archaeogenetics in the 1990s, the dating of mitochondrial and Y-chromosomal haplogroups became possible with some confidence. By 1999, estimates ranged around 150,000 years for the mt-MRCA and 60,000 to 70,000 years for the migration out of Africa.
Cheddar Man
The mitochondrial DNA of Cheddar Man was of haplogroup U5b1. Some 65% of western European Mesolithic hunter-gatherers had haplogroup U5; today it is widely distributed, at lower frequencies, across western Eurasia and northern Africa. In 1996, Bryan Sykes of the University of Oxford first sequenced the mitochondrial DNA from one of Cheddar Man's molars.
Molecular anthropology
Mitochondrial DNA became an area of research in phylogenetics in the late 1970s. Unlike genomic DNA, it offered advantages in that it did not undergo recombination. The process of recombination, if frequent enough, corrupts the ability to create parsimonious trees because of stretches of amino acid subsititions (SNPs). When looking between distantly related species, recombination is less of a problem since recombination between branches from common ancestors is prevented after true speciation occurs. When examining closely related species, or branching within species, recombination creates a large number of 'irrelevant SNPs' for cladistic analysis. MtDNA, through the process of organelle division, became clonal over time; very little, or often none, of that paternal mtDNA is passed. While recombination may occur in mtDNA, there is little risk that it will be passed to the next generation. As a result, mtDNA become clonal copies of each other, except when a new mutation arises. As a result, mtDNA does not have pitfalls of autosomal loci when studied in interbreeding groups. Another advantage of mtDNA is that the hyper-variable regions evolve very quickly; this shows that certain regions of mitochondrial DNA approach neutrality. This allowed the use of mitochondrial DNA to determine that the relative age of the human population was small, having gone through a recent constriction at about 150,000 years ago (see #Causes of errors).
DNA repair
In human cells, and eukaryotic cells in general, DNA is found in two cellular locations – inside the nucleus and inside the mitochondria. Nuclear DNA (nDNA) exists as chromatin during non-replicative stages of the cell cycle and is condensed into aggregate structures known as chromosomes during cell division. In either state the DNA is highly compacted and wound up around bead-like proteins called histones. Whenever a cell needs to express the genetic information encoded in its nDNA the required chromosomal region is unravelled, genes located therein are expressed, and then the region is condensed back to its resting conformation. Mitochondrial DNA (mtDNA) is located inside mitochondria organelles, exists in multiple copies, and is also tightly associated with a number of proteins to form a complex known as the nucleoid. Inside mitochondria, reactive oxygen species (ROS), or free radicals, byproducts of the constant production of adenosine triphosphate (ATP) via oxidative phosphorylation, create a highly oxidative environment that is known to damage mtDNA. A critical enzyme in counteracting the toxicity of these species is superoxide dismutase, which is present in both the mitochondria and cytoplasm of eukaryotic cells.
Human mitochondrial genetics
Because of the complex ways in which mitochondrial and nuclear DNA "communicate" and interact, even seemingly simple inheritance is hard to diagnose. A mutation in chromosomal DNA may change a protein that regulates (increases or decreases) the production of another certain protein in the mitochondria or the cytoplasm; this may lead to slight, if any, noticeable symptoms. On the other hand, some devastating mtDNA mutations are easy to diagnose because of their widespread damage to muscular, neural, and/or hepatic tissues (among other high-energy and metabolism-dependent tissues) and because they are present in the mother and all the offspring.
Mitochondrial DNA
The brains of individuals with Alzheimer’s disease have elevated levels of oxidative DNA damage in both nuclear DNA and mtDNA, but the mtDNA has approximately 10-fold higher levels than nuclear DNA. It has been proposed that aged mitochondria is the critical factor in the origin of neurodegeneration in Alzheimer’s disease.
Mitochondrial DNA
Nuclear and mitochondrial DNA are thought to be of separate evolutionary origin, with the mtDNA being derived from the circular genomes of the bacteria that were engulfed by the early ancestors of today's eukaryotic cells. This theory is called the endosymbiotic theory. Each mitochondrion is estimated to contain 2–10 mtDNA copies. In the cells of extant organisms, the vast majority of the proteins present in the mitochondria (numbering approximately 1500 different types in mammals) are coded for by nuclear DNA, but the genes for some, if not most, of them are thought to have originally been of bacterial origin, having since been transferred to the eukaryotic nucleus during evolution.
Science and technology in Switzerland
Friedrich Miescher was a Swiss physician who was the first researcher to isolate and characterize Nucleic acid (DNA). Today, a research institute in Basel (the Friedrich Miescher Institute, FMI) is named after him. Emil Theodor Kocher (Nobel Prize in Physiology or Medicine 1909) was known for his work in the physiology, pathology and surgery of the thyroid. The neurologist Walter Rudolf Hess (Nobel Prize in Physiology or Medicine 1949) mapped the areas of the brain that were responsible for the control of several vital bodily functions. The biochemist Werner Arber (Nobel Prize in Physiology or Medicine 1978) is known for his discovery of restriction endonucleases which are essential for all modern biotechnology. The Swiss born Edmond H. Fischer (Nobel Prize in Physiology or Medicine 1992) discovered how reversible phosphorylation works as a switch to activate proteins. Rolf M. Zinkernagel (Nobel Prize in Physiology or Medicine 1996) is famous for his work on the immune system.
Mitochondrial DNA
Doubly uniparental inheritance of mtDNA is observed in bivalve mollusks. In those species, females have only one type of mtDNA (F), whereas males have F type mtDNA in their somatic cells, but M type of mtDNA (which can be as much as 30% divergent) in germline cells. Paternally inherited mitochondria have additionally been reported in some insects such as fruit flies, honeybees, and periodical cicadas.
Who We Are and How We Got Here
Since 2010, population geneticists have been able to sequence ancient human DNA, recovering complete genomes, in contrast to earlier approaches which relied on the far more abundant (and hence more easily recovered) mitochondrial DNA, which is present in many copies in each cell, and transmitted only via the maternal line. That early work gave the "exciting" result that all modern humans are related to "Mitochondrial Eve", a woman who lived in Africa only about 160,000 years ago.
Mitochondrial DNA
There is only one mitochondrial genome type found in animal cells. This genome usually contains one circular molecule with between 11–28 kbp of genetic material (type 1).
DNA
DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages. As it resided in the nuclei of cells, he called it "nuclein". In 1878, Albrecht Kossel isolated the non-protein component of "nuclein", nucleic acid, and later isolated its five primary nucleobases.
Albert L. Lehninger
Albert Lester Lehninger (February 17, 1917 – March 4, 1986) was an American biochemist in the field of bioenergetics. He made fundamental contributions to the current understanding of metabolism at a molecular level. In 1948, he discovered, with Eugene P. Kennedy, that mitochondria are the site of oxidative phosphorylation in eukaryotes, which ushered in the modern study of energy transduction. He is the author of a number of classic texts, including: "Biochemistry, The Mitochondrion, Bioenergetics " and, most notably, his series "Principles of Biochemistry". The latter is a widely used text for introductory biochemistry courses at the college and university levels.
DNA history of Egypt
A study published in 2017 described the extraction and analysis of DNA from 151 mummified ancient Egyptian individuals, whose remains were recovered from Abusir el-Meleq in Middle Egypt. Obtaining well-preserved, uncontaminated DNA from mummies has been a problem for the field of archaeogenetics and these samples provided "the first reliable data set obtained from ancient Egyptians using high-throughput DNA sequencing methods". The specimens were living in a period stretching from the late New Kingdom to the Roman era (1388 BCE–426 CE). Complete mitochondrial DNA (mtDNA) sequences were obtained for 90 of the mummies and were compared with each other and with several other ancient and modern datasets. The scientists found that the ancient Egyptian individuals in their own dataset possessed highly similar mitochondrial profiles throughout the examined period. Modern Egyptians generally shared this maternal haplogroup pattern, but also carried more Sub-Saharan African clades. However, analysis of the mummies' mtDNA haplogroups found that they shared greater mitochondrial affinities with modern populations from the Near East and the Levant compared to modern Egyptians. Additionally, three of the ancient Egyptian individuals were analysed for Y-DNA, two were assigned to the Middle-Eastern haplogroup J and one to haplogroup E1b1b1 common in North Africa. The researchers cautioned that the affinities of the examined ancient Egyptian specimens may not be representative of those of all ancient Egyptians since they were from a single archaeological site.
Alexei Rezepkin
Together with the geneticist A.V. Nedoluzhko, he conducted Russia's first complete sequencing of the DNA of ancient mitochondrial genome. This DNA sample was isolated from the mitochondria of skeletal remains from the burial ground Klady.
Human mitochondrial genetics
Mitochondrial DNA had traditionally had the two strand of the DNA designated the heavy and the light strand, due to their boyant densities during separation in cesium chloride gradients, which was found to be related to the relative G+T nucleotide content of the strand. However, confusion of labeling of this strands is widespread, and appears to originate with a identification of the majority coding strand as the heavy in one influential article in 1999. In humans, the light strand of mtDNA carries 28 genes and the heavy strand of mtDNA carries only 9 genes. Eight of the 9 genes on the heavy strand code for mitochondrial tRNA molecules. Human mtDNA consists of 16,569 nucleotide pairs. The entire molecule is regulated by only one regulatory region which contains the origins of replication of both heavy and light strands. The entire human mitochondrial DNA molecule has been mapped.
Uniparental inheritance
Although most of the eukaryotic sub-cellular parts do not have their own DNA nor are capable of replication independent of the nucleus, there are some exceptions such as mitochondria and chloroplasts. Not only are these organelles capable of independent DNA replication, translation, and transcription, they are commonly known to inherit genes from only one parental type. In the case of mitochondria, maternal inheritance is almost the exclusive form of inheritance. Although, during egg cell fertilization, mitochondria are brought into the fertilized cell both by the egg cell and the sperm, the paternal mitochondria are usually marked with ubiquitin and are later destroyed. Even if they are not destroyed, the DNA's of different mitochondria rarely genetically recombine with one another. Thus, mitochondria in most animals are inherited from the maternal type only.
List of dreams
Nobel laureate James Watson opens TED 2005 with the frank and funny story of how he and his research partner, Francis Crick, discovered the structure of DNA. James Watson, co-discoverer of the structure of DNA, reported stumbling upon the double helix image for the DNA chain through his dream of a spiral staircase.
John E. Walker
From 1969 to 1971, Walker worked at the University of Wisconsin–Madison, and from 1971–1974 in France. He met Fred Sanger in 1974 at a workshop at the University of Cambridge. This resulted in an invitation to work at the Laboratory of Molecular Biology of the Medical Research Council, which became a long-term appointment. Among the other staff was Francis Crick, who was well known for his discovery of the molecular structure of DNA. At first, he analyzed the sequences of proteins and then uncovered details of the modified genetic code in mitochondria. In 1978, he decided to apply protein chemical methods to membrane proteins. In this way, Walker characterized the subunit composition of proteins in the mitochondrial membrane and the DNA sequence of the mitochondrial genome.
Alan J. Cooper
Cooper is known as one of the pioneers of ancient DNA research, performing some of the first Polymerase chain reaction-based studies with Svante Paabo and Allan C. Wilson at UC Berkeley in 1989. In 2001, he used these methods to characterise the first complete genome sequences from an extinct species, mitochondrial genomes from two New Zealand moa.
Douglas C. Wallace
Wallace is a pioneer in the study of mitochondrial DNA. Wallace and his colleagues introduced human mitochondrial genetics into the field of molecular genetics. In 1975, for the first time ever, Wallace could associate a genetic disorder with the mitochondrial DNA region (resistance to chloramphenicol) and in 1990 he described a mitochondrial DNA mutation as the cause of a particular form of myoclonic epilepsy. He has been instrumental in the study of the mitochondrial genome and has developed new methods for the analysis of mitochondrial DNA.
Friedrich Miescher
Miescher isolated various phosphate-rich chemicals, which he called "nuclein" (now nucleic acids), from the nuclei of white blood cells in 1869 in Felix Hoppe-Seyler's laboratory at the University of Tübingen, Germany, paving the way for the identification of DNA as the carrier of inheritance. The significance of the discovery, first published in 1871, was not at first apparent, and it was Albrecht Kossel who made the initial inquiries into its chemical structure. Later, Friedrich Miescher raised the idea that the nucleic acids could be involved in heredity.
Leigh syndrome
Mitochondria are essential organelles in eukaryotic cells. Their function is to convert the potential energy of glucose, amino acids, and fatty acids into adenosine triphosphate (ATP) in a process called oxidative phosphorylation. Mitochondria carry their own DNA, called mitochondrial DNA (mtDNA). The information stored in the mtDNA is used to produce several of the enzymes essential to the production of ATP.
Rosalind Franklin and DNA
The discovery of the structure of DNA in 1953 is regarded as "the greatest and most important scientific discovery of the 20th Century". Francis Crick, James Watson and Maurice Wilkins received the Nobel Prize in Physiology or Medicine in 1962 for the discovery. This discovery laid the foundation for modern biology, including medical and molecular researches. The discoverers earned a lasting worldwide fame. But the contribution made by Rosalind Franklin, who died in 1958, was largely forgotten. The main motive for Sayre's book came from James Watson's memoir "The Double Helix : A Personal Account of the Discovery of the Structure of DNA". Published in 1968, "The Double Helix" reflected the account of the discovery in which Franklin was portrayed as "uninteresting", "belligerent", and "sharp, stubborn mind", referring her as "Rosy", the name she did not want to be called. Watson described her as having "all the imagination of English blue-stocking adolescents", and "the product of an unsatisfied mother".
Human mitochondrial genetics
Mitochondrial DNA (mtDNA) is not transmitted through nuclear DNA (nDNA). In humans, as in most multicellular organisms, mitochondrial DNA is inherited only from the mother's ovum. There are theories, however, that paternal mtDNA transmission in humans can occur under certain circumstances.
Jodi Nunnari
Nunnari was born in Cleveland, Ohio, and studied chemistry at the College of Wooster before obtaining a Ph.D. in pharmacology from Vanderbilt University, working with Lee Limbird. As a postdoctoral fellow with Peter Walter at the University of California, San Francisco, Nunnari pioneered the use of green fluorescent protein to visualize mitochondria in budding yeast, helping to establish the field of mitochondrial dynamics. Since obtaining an independent position at the University of California, Davis, Nunnari and colleagues have investigated the molecular mechanisms underlying mitochondrial fission and fusion and explored the structure and function of membrane contact sites that link mitochondria with other organelles.
Genomics
Following Rosalind Franklin's confirmation of the helical structure of DNA, James D. Watson and Francis Crick's publication of the structure of DNA in 1953 and Fred Sanger's publication of the Amino acid sequence of insulin in 1955, nucleic acid sequencing became a major target of early molecular biologists. In 1964, Robert W. Holley and colleagues published the first nucleic acid sequence ever determined, the ribonucleotide sequence of alanine transfer RNA. Extending this work, Marshall Nirenberg and Philip Leder revealed the triplet nature of the genetic code and were able to determine the sequences of 54 out of 64 codons in their experiments. In 1972, Walter Fiers and his team at the Laboratory of Molecular Biology of the University of Ghent (Ghent, Belgium) were the first to determine the sequence of a gene: the gene for Bacteriophage MS2 coat protein. Fiers' group expanded on their MS2 coat protein work, determining the complete nucleotide-sequence of bacteriophage MS2-RNA (whose genome encodes just four genes in 3569 base pairs [bp]) and Simian virus 40 in 1976 and 1978, respectively.
Mitophagy
Mitophagy in yeast was first presumed after the discovery of Yeast Mitochondrial Escape genes (yme), specifically yme1. Yme1 like other genes in the family showed increase escapes of mtDNA, but was the only one that showed in increase in mitochondrial degradation. Through work on this gene that mediates the escape of mtDNA, researchers discovered that mitochondrial turnover is triggered by proteins.
DNA profiling
For highly degraded samples, it is sometimes impossible to get a complete profile of the 13 CODIS STRs. In these situations, mitochondrial DNA (mtDNA) is sometimes typed due to there being many copies of mtDNA in a cell, while there may only be 1-2 copies of the nuclear DNA. Forensic scientists amplify the HV1 and HV2 regions of the mtDNA, and then sequence each region and compare single-nucleotide differences to a reference. Because mtDNA is maternally inherited, directly linked maternal relatives can be used as match references, such as one's maternal grandmother's daughter's son. In general, a difference of two or more nucleotides is considered to be an exclusion. Heteroplasmy and poly-C differences may throw off straight sequence comparisons, so some expertise on the part of the analyst is required. mtDNA is useful in determining clear identities, such as those of missing people when a maternally linked relative can be found. mtDNA testing was used in determining that Anna Anderson was not the Russian princess she had claimed to be, Anastasia Romanov.
Cynthia Kenyon
Cynthia Kenyon graduated valedictorian in chemistry and biochemistry from the University of Georgia in 1976. She received her PhD in 1981 from MIT where, in Graham Walker's laboratory, she looked for genes on the basis of their activity profiles, discovering that DNA-damaging agents activate a battery of DNA repair genes in E. coli. She then did postdoctoral studies with Nobel laureate Sydney Brenner at the MRC Laboratory of Molecular Biology in Cambridge, England, studying the development of "C. elegans."
Extrachromosomal DNA
The mitochondria present in eukaryotic cells contain multiple copies of mitochondrial DNA referred to as mtDNA which is housed within the mitochondrial matrix. In multicellular animals, including humans, the circular mtDNA chromosome contains 13 genes that encode proteins that are part of the electron transport chain and 24 genes that produce RNA necessary for the production of mitochondrial proteins; these genes are broken down into 2 rRNA genes and 22 tRNA genes. The size of an animal mtDNA plasmid is roughly 16.6 kb and although it contains genes for tRNA and mRNA synthesis, proteins produced as a result of nuclear genes are still required in order for the mtDNA to replicate or for mitochondrial proteins to be translated. There is only one region of the mitochondrial chromosome that does not contain a coding sequence and that is the 1 kb region known as the D-loop to which nuclear regulatory proteins bind. The number of mtDNA molecules per mitochondria varies from species to species as well as between cells with different energy demands. For example, muscle and liver cells contain more copies of mtDNA per mitochondrion than blood and skin cells do. Due to the proximity of the electron transport chain within the mitochondrial inner membrane and the production of reactive oxygen species (ROS), and due to the fact that the mtDNA molecule is not bound by or protected by histones, the mtDNA is more susceptible to DNA damage than nuclear DNA. In cases where mtDNA damage does occur, the DNA can either be repaired via base excision repair pathways, or the damaged mtDNA molecule is destroyed (without causing damage to the mitochondrion since there are multiple copies of mtDNA per mitochondrion).
Mitochondrial DNA
The fact that mitochondrial DNA is maternally inherited enables genealogical researchers to trace maternal lineage far back in time. (Y-chromosomal DNA, paternally inherited, is used in an analogous way to determine the patrilineal history.) This is usually accomplished on human mitochondrial DNA by sequencing the hypervariable control regions (HVR1 or HVR2), and sometimes the complete molecule of the mitochondrial DNA, as a genealogical DNA test. HVR1, for example, consists of about 440 base pairs. These 440 base pairs are compared to the same regions of other individuals (either specific people or subjects in a database) to determine maternal lineage. Most often, the comparison is made with the revised Cambridge Reference Sequence. Vilà "et al." have published studies tracing the matrilineal descent of domestic dogs from wolves.
The concept of the Mitochondrial Eve is based on the same type of analysis, attempting to discover the origin of humanity by tracking the lineage back in time.
Mitochondrial DNA
In human mitochondrial DNA (and probably in that of metazoans in general), 100–10,000 separate copies of mtDNA are usually present per somatic cell. (Egg and sperm cells are exceptions.) In mammals, each double-stranded circular mtDNA molecule consists of 15,000–17,000 base pairs. The two strands of mtDNA are differentiated by their nucleotide content, with a guanine-rich strand referred to as the heavy strand (or H-strand) and a cytosine-rich strand referred to as the light strand (or L-strand). However, confusion in the labeling of these strands is widespread; the confusion appears to have originated from the identification of the majority coding strand as the heavy in one influential article in 1999. The light strand encodes 28 genes and the heavy strand encodes 9 genes, for a total of 37 genes. Of these 37 genes, 13 are for proteins (polypeptides), 22 are for transfer RNA (tRNA), and two are for the small and large subunits of ribosomal RNA (rRNA). The human mitogenome contains overlapping genes (ATP8 and ATP6 as well as ND4L and ND4: see the human mitochondrial genome map), a feature that is rare in animals' nuclear genomes. The 37-gene pattern is also seen in most metazoans, although the mtDNA size range is greater and in some cases one or more of these genes is absent.
Health of Charles Darwin
The pathologist John A. Hayman of the University of Melbourne has presented a case that Darwin's symptoms indicate that he suffered from cyclic vomiting syndrome (CVS), an illness associated with mitochondrial DNA abnormalities. His paper on the topic was accepted by the "BMJ" and the "Medical Journal of Australia", and was published in December 2009. In a supplement published in February 2012, he proposed that stroke-like episodes of memory loss and partial paralysis which do not occur with CVS are characteristic of the MELAS syndrome. An A3243G mtDNA mutation has been found in 80% of patients with this syndrome, and has also been described in those with CVS. This mutation in mitochondria is associated with symptoms of intestinal problems, seasickness and Ménière's disease as well as CVS and MELAS syndrome, thus giving a shared source of the various problems that affected Darwin. Any mitochondrial disease would have been inherited from his mother Susannah Darwin, whose own mother had 8 other children. Some of them had illnesses which could have been related to the same mutation.
DNA
DNA was first isolated by Friedrich Miescher in 1869. Its molecular structure was first identified by Francis Crick and James Watson at the Cavendish Laboratory within the University of Cambridge in 1953, whose model-building efforts were guided by X-ray diffraction data acquired by Raymond Gosling, who was a post-graduate student of Rosalind Franklin. DNA is used by researchers as a molecular tool to explore physical laws and theories, such as the ergodic theorem and the theory of elasticity. The unique material properties of DNA have made it an attractive molecule for material scientists and engineers interested in micro- and nano-fabrication. Among notable advances in this field are DNA origami and DNA-based hybrid materials.
Mitochondrion
General
Anzick-1
MtDNA is DNA located in mitochondria, an organelle that is found in human cells. The mitochondria is maternally inherited by all persons, and analysis of the mtDNA can provide information about maternal ancestry. MtDNA genomes are classified into different haplogroups based on a shared common ancestor. These distinct haplogroups provide information about ancient migration patterns.
Microsporum nanum
Mitochondrial DNA sequences have been used for phylogenetic studies in the dermatophytes. A typical fungal mitochondrial DNA usually contains 14 conserved protein-coding genes, 22 to 26 tRNA gene, and 2 rRNA genes. The difference of mitochondrial DNA between fungal species is due to the variations in intergenic region, intron, and gene order. The complete sequences of "Trichophyton rubrum", "T. mentagrophytes", "T. ajelloi", "M. canis", "M. nanum", and "Epidermophyton floccosum" show that these 6 species in dermatophytes are closely related because their mitochondrial genomes are highly conserved. Genome size of mitochondrial DNA in "M. nanum" is 24,105 basepairs. The DNA is AT-rich and the GC content is only 24.47%. "M. nanum" mtDNA has 15 protein-coding genes, including ATP synthase subunits "atp6", "atp8", and "atp9", cytochrome oxidase subunits "cox1", "cox2", and "cox3", apocytochrome b "cob", a ribosomal protein "rps5", and NADH dehydrogenase subunits "nad1", "nad2", "nad3", "nad4", "nad5", and "nad6". The gene order of the 15 conserved protein coding genes in "M. nanum" mtDNA is identical to that of "T. rubrum", "T. mentagrophytes", "T. ajelloi", and "M. canis". The "Microsporum nanum" mtDNA also contains 2 rRNAs and 25 tRNAs. In addition, this mitochondrial genome is highly compact because 83.76% are structural genes. Moreover, the genome contains one intron and one intronic ORF.
Neanderthal genetics
In 2008 Richard E. Green et al. from Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, published the full sequence of Neanderthal mitochondrial DNA (mtDNA) and suggested "Neanderthals had a long-term effective population size smaller than that of modern humans."
In the same publication, it was disclosed by Svante Pääbo that in the previous work at the Max Planck Institute, "Contamination was indeed an issue," and they eventually realised that 11% of their sample was modern human DNA. Since then, more of the preparation work has been done in clean areas and 4-base pair 'tags' have been added to the DNA as soon as it is extracted so the Neanderthal DNA can be identified.
The project first sequenced the entire genome of a Neanderthal in 2013 by extracting it from the phalanx bone of a 50,000-year-old Siberian Neanderthal.
Human mitochondrial genetics
Using these techniques, it is estimated that the first mitochondria arose around 1.5 billion years ago. A generally accepted hypothesis is that mitochondria originated as an aerobic prokaryote in a symbiotic relationship within an anaerobic eukaryote.
Mitochondrial Eve
By 1985, data from the mtDNA of 145 women of different populations, and of two cell lines, HeLa and GM 3043, derived from a Black American and a !Kung respectively, was available. After more than 40 revisions of the draft, the manuscript was submitted to "Nature" in late 1985 or early 1986 and published on 1 January 1987. The published conclusion was that all current human mtDNA originated from a single population from Africa, at the time dated to between 140,000 and 200,000 years ago.
Maurice Sanford Fox
Maurice Sanford Fox (born New York, October 11, 1924) is an American geneticist and molecular biologist, and professor Emeritus of Biology at the Massachusetts Institute of Technology (MIT), where he served as department chair between 1985 and 1989. His pioneering investigations of bacterial transformation helped illuminate the mechanisms by which donor DNA enters and is integrated into a host cell. His research also contributed to our understanding of mechanisms of DNA mutation, recombination, and mismatch repair more generally. Ancillary activities include his critical role in the establishment of the Council for a Livable World. He was married to photo researcher Sally Fox for over 50 years, has three sons (Jonathan, Gregory, and Michael).
Mitochondrion
Although most of a cell's DNA is contained in the cell nucleus, the mitochondrion has its own independent genome that shows substantial similarity to bacterial genomes. Mitochondrial proteins (proteins transcribed from mitochondrial DNA) vary depending on the tissue and the species. In humans, 615 distinct types of protein have been identified from cardiac mitochondria, whereas in rats, 940 proteins have been reported. The mitochondrial proteome is thought to be dynamically regulated.
Mitochondrial DNA
Mitochondrial DNA was admitted into evidence for the first time ever in a United States courtroom in 1996 during "State of Tennessee v. Paul Ware".
Matthew Meselson
In the famous Meselson–Stahl experiment of 1958 he and Frank Stahl demonstrated through nitrogen isotope labeling that DNA is replicated semi-conservatively. In addition, Meselson, François Jacob, and Sydney Brenner discovered the existence of messenger RNA in 1961. Meselson has investigated DNA repair in cells and how cells recognize and destroy foreign DNA, and, with Werner Arber, was responsible for the discovery of restriction enzymes.
Human mitochondrial DNA haplogroup
The rate at which mitochondrial DNA mutates is known as the mitochondrial molecular clock. It's an area of ongoing research with one study reporting one mutation per 8000 years.
Haplogroup H (mtDNA)
Haplogroup H is a human mitochondrial DNA (mtDNA) haplogroup. The clade is believed to have originated in Southwest Asia, around 20,000 to 25,000 years ago. Mitochondrial haplogroup H is today predominantly found in Europe, and is believed to have evolved before the Last Glacial Maximum (LGM). It first expanded in the northern Near East and Southern Caucasus soon, and later migrations from Iberia suggest that the clade reached Europe before the Last Glacial Maximum. The haplogroup has also spread to parts of Africa, Siberia and inner Asia. Today, around 40% of all maternal lineages in Europe belong to haplogroup H.
Mitochondrial DNA (journal)
Mitochondrial DNA is an academic journal that publishes review articles on the current and developing technologies around mitochondrial DNA research and discovery. It is published by Informa Healthcare.
Paternal mtDNA transmission
The mixing of maternal and paternal mtDNA was thought to have been found in chimpanzees in 1999 and in humans in 1999 and 2018, resulting this last finding quite impressive, as biparental mtDNA was observed in subsequent generations in three different familias, leading to the conclusion that, although the maternal transmission dogma remains strong, there is evidence that paternal transmission do exist and there is a probably a mechanism which, if elucidated, can be a new tool in reproductive field, for example, avoiding the mitochondrial replacement therapy, and just using this mechanism so that the offspring inherit the paternal mitochondria. However, there has been only a single documented case of 90% human paternal mitochondrial DNA transmission.
P. Michael Conneally
P. Michael Conneally, Ph.D., (December 4, 1931 – February 17, 2017) was the Distinguished Professor Emeritus at the Indiana University School of Medicine in the Department of Medical and Molecular Genetics. He was certified in medical genetics by the American Board of Medical Genetics and a founding fellow of the American College of Medical Genetics. He was a human geneticist interested in discovering the location of human genes that cause disease, specifically the mapping of Mendelian and complex inherited diseases including the study of Huntington's disease, genetics of alcoholism, diabetes and manic depressive illness. In collaboration with researchers from Columbia University and James F. Gusella of Harvard University, he was the first to use DNA techniques to map a human gene. In the past twenty years he has helped map approximately 20 human genes and his work has resulted in the identification of 20% of the human genome. Conneally received his bachelor's degree in Agriculture with Honors from University College Dublin in 1954 and Master’s and Ph.D. from the University of Wisconsin, Madison.
Mitochondrion
Uniparental inheritance leads to little opportunity for genetic recombination between different lineages of mitochondria, although a single mitochondrion can contain 2–10 copies of its DNA. For this reason, mitochondrial DNA is usually thought to reproduce by binary fission. What recombination does take place maintains genetic integrity rather than maintaining diversity. However, there are studies showing evidence of recombination in mitochondrial DNA. It is clear that the enzymes necessary for recombination are present in mammalian cells. Further, evidence suggests that animal mitochondria can undergo recombination. The data are a bit more controversial in humans, although indirect evidence of recombination exists. If recombination does not occur, the whole mitochondrial DNA sequence represents a single haplotype, which makes it useful for studying the evolutionary history of populations.
Tell Halula
Eva Fernández Domínguez extracted samples of mitochondrial DNA from human bones from Tell Halula as part of the studies for her PhD thesis accepted at the University of Barcelona in 2005. The methodology used was later superseded, so a first publication of the results in 2008 was corrected in a subsequent publication in 2014. In the latter publication the mtDNA haplogroups were given as U, R0, K, HV, H, N and L3.
Masayori Inouye
Masayori Inouye is a Japanese biochemist who, along with his team, discovered natural antisense RNA.
Inouye was also a key scientist involved in the discovery and characterization of retrons, which are retroviral-like elements found in various bacterial genomes. Retrons produce small satellite DNA known as multi-copy single stranded DNA (msDNA) and have recently been demonstrated to be important virulence determinants for gastrointestinal disease (Elfenbein et al., 2013)
Genealogical DNA test
All humans descend in the direct female line from Mitochondrial Eve, a female who lived probably around 200,000 years ago in Africa. Different branches of her descendants are different haplogroups. Most mtDNA results include a prediction or exact assertion of one's mtDNA Haplogroup. Mitochrondial haplogroups were greatly popularized by the book "The Seven Daughters of Eve", which explores mitochondrial DNA.
Extrachromosomal DNA
In prokaryotes, nonviral extrachromosomal DNA is primarily found in plasmids whereas in eukaryotes extrachromosomal DNA is primarily found in organelles. Mitochondrial DNA is a main source of this extrachromosomal DNA in eukaryotes. The fact that this organelle contains its own DNA supports the hypothesis that mitochondria originated as bacterial cells engulfed by ancestral eukaryotic cells. Extrachromosomal DNA is often used in research of replication because it is easy to identify and isolate.
Human genome
Due to the lack of a system for checking for copying errors, mitochondrial DNA (mtDNA) has a more rapid rate of variation than nuclear DNA. This 20-fold higher mutation rate allows mtDNA to be used for more accurate tracing of maternal ancestry. Studies of mtDNA in populations have allowed ancient migration paths to be traced, such as the migration of Native Americans from Siberia or Polynesians from southeastern Asia. It has also been used to show that there is no trace of Neanderthal DNA in the European gene mixture inherited through purely maternal lineage. Due to the restrictive all or none manner of mtDNA inheritance, this result (no trace of Neanderthal mtDNA) would be likely unless there were a large percentage of Neanderthal ancestry, or there was strong positive selection for that mtDNA (for example, going back 5 generations, only 1 of your 32 ancestors contributed to your mtDNA, so if one of these 32 was pure Neanderthal you would expect that ~3% of your autosomal DNA would be of Neanderthal origin, yet you would have a ~97% chance to have no trace of Neanderthal mtDNA).
Paternal mtDNA transmission
In human mitochondrial genetics, there is debate over whether or not paternal mtDNA transmission is possible. Many studies hold that paternal mtDNA is never transmitted to offspring. This thought is central to mtDNA genealogical DNA testing and to the theory of mitochondrial Eve. The fact that mitochondrial DNA is maternally inherited enables researchers to trace maternal lineage far back in time. Y chromosomal DNA, paternally inherited, is used in an analogous way to trace the agnate lineage.
Peter Ritchie Calder
Sir Lawrence Bragg's original announcement of the discovery of the structure of DNA was made at a Solvay conference on proteins in Belgium on 8 April 1953 but went unreported by the UK press. He then gave a talk at Guy's Hospital Medical School in London on Thursday 14 May 1953, which resulted in an article by Ritchie Calder in the "News Chronicle" of London on Friday 15 May 1953, entitled "Why You Are You. Nearer Secret of Life".
Douglas C. Wallace
Douglas Cecil Wallace (born November 6, 1946) is a geneticist and evolutionary biologist at the University of Pennsylvania and the Children's Hospital of Philadelphia in Pennsylvania. He pioneered the use of human mitochondrial DNA as a molecular marker.
Mitochondrial DNA
Unlike nuclear DNA, which is inherited from both parents and in which genes are rearranged in the process of recombination, there is usually no change in mtDNA from parent to offspring. Although mtDNA also recombines, it does so with copies of itself within the same mitochondrion. Because of this and because the mutation rate of animal mtDNA is higher than that of nuclear DNA, mtDNA is a powerful tool for tracking ancestry through females (matrilineage) and has been used in this role to track the ancestry of many species back hundreds of generations.
Mario Capecchi
Mario Capecchi received his Bachelor of Science in chemistry and physics in 1961 from Antioch College in Ohio. Capecchi came to MIT as a graduate student intending to study physics and mathematics, but during the course of his studies, he became interested in molecular biology. He subsequently transferred to Harvard to join the lab of James D. Watson, co-discoverer of the structure of DNA. Capecchi received his Ph.D. in biophysics in 1967 from Harvard University, with his doctoral thesis completed under the tutelage of Watson.
Anthony William Linnane
Anthony William Linnane (1930–2017) was an Australian professor of biochemistry, known for his work on mitochondria.
Mitochondrial DNA
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, adenosine triphosphate (ATP). Mitochondrial DNA is only a small portion of the DNA in a eukaryotic cell; most of the DNA can be found in the cell nucleus and, in plants and algae, also in plastids such as chloroplasts.
Human mitochondrial genetics
Human mitochondrial genetics is the study of the genetics of human mitochondrial DNA (the DNA contained in human mitochondria). The human mitochondrial genome is the entirety of hereditary information contained in human mitochondria. Mitochondria are small structures in cells that generate energy for the cell to use, and are hence referred to as the "powerhouses" of the cell.
Human mitochondrial genetics
In humans, mitochondrial DNA (mtDNA) forms closed circular molecules that contain 16,569 DNA base pairs, with each such molecule normally containing a full set of the mitochondrial genes. Each human mitochondrion contains, on average, approximately 5 such mtDNA molecules, with the quantity ranging between 1 and 15. Each human cell contains approximately 100 mitochondria, giving a total number of mtDNA molecules per human cell of approximately 500.
Friedrich Miescher Institute for Biomedical Research
The Friedrich Miescher Award is Switzerland's highest honor for up-and-coming biochemical researchers. The award is granted every year by the Swiss Society for Biochemistry to the best scientific contribution in this field. Prize winners must be under 40 and must either be Swiss citizens or have conducted the prize-winning research in this country. The award was instituted in 1970, proposed and donated by the FMI. It is named after the Basel scientist who discovered DNA, Friedrich Miescher.
Denisovan
The mitochondrial DNA (mtDNA) from the finger bone discovered in Denisova Cave differs from that of modern humans by 385 bases (nucleotides) out of approximately 16,500, whereas the difference between modern humans and Neanderthals is around 202 bases. In contrast, the difference between chimpanzees and modern humans is approximately 1,462 mtDNA base pairs. This suggested a divergence time around one million years ago. The more divergent Denisovan mtDNA has been interpreted as evidence of admixture between Denisovans and an unknown archaic population. Studies suggest that a population related to modern humans contributed mtDNA to the Neanderthal lineage, but not to the Denisovan mitochondrial genomes yet sequenced. It has suggested the species could be "Homo heidelbergensis", but that species is now generally considered to be too closely related to the Neanderthals. That it could have been a "Homo erectus"-like introgression into the Denisovans about 53,000 years ago that is responsible for the anomalously-divergent mtDNA has also been proposed.
Baldomero Olivera
Baldomero Olivera (born 1941) is a Filipino chemist known for discovery of many cone snail toxins important for neuroscience. These molecules, called conotoxins, led to a breakthrough in the study of ion channels and neuromuscular synapses.
He discovered and first characterized E. coli DNA ligase, a key enzyme of genetic engineering and recombinant DNA technology.
Mitochondrial DNA (journal)
Rob DeSalle (American Museum of Natural History) is the Editor-in-Chief of "Mitochondrial DNA".
Aurochs
The first complete mitochondrial genome (16,338 base pairs) DNA sequence analysis of "Bos primigenius" from an archaeologically verified and exceptionally well preserved aurochs bone sample was published in 2010, followed by the publication in 2015 of the complete genome sequence of "Bos primigenius" using DNA isolated from a 6,750-year-old British aurochs bone. Further studies using the "Bos primigenius" whole genome sequence have identified candidate microRNA-regulated domestication genes
Susan Hockfield
Following a postdoctoral fellowship at the University of California, San Francisco, Hockfield joined the staff of the Cold Spring Harbor Laboratory in 1980: she was hired by James Watson, who, with Francis Crick had discovered the structure of DNA.
Douglas C. Wallace
Wallace and his colleagues demonstrated that human mitochondrial DNA is inherited exclusively from the mother and reconstructed the origin and ancient migration patterns of women using variations in mitochondrial DNA sequences.
Mitochondrion
In 1939, experiments using minced muscle cells demonstrated that cellular respiration using one oxygen atom can form two adenosine triphosphate (ATP) molecules, and, in 1941, the concept of the phosphate bonds of ATP being a form of energy in cellular metabolism was developed by Fritz Albert Lipmann. In the following years, the mechanism behind cellular respiration was further elaborated, although its link to the mitochondria was not known. The introduction of tissue fractionation by Albert Claude allowed mitochondria to be isolated from other cell fractions and biochemical analysis to be conducted on them alone. In 1946, he concluded that cytochrome oxidase and other enzymes responsible for the respiratory chain were isolated to the mitochondria. Eugene Kennedy and Albert Lehninger discovered in 1948 that mitochondria are the site of oxidative phosphorylation in eukaryotes. Over time, the fractionation method was further developed, improving the quality of the mitochondria isolated, and other elements of cell respiration were determined to occur in the mitochondria.
Mitochondrion
There are two hypotheses about the origin of mitochondria: endosymbiotic and autogenous. The endosymbiotic hypothesis suggests that mitochondria were originally prokaryotic cells, capable of implementing oxidative mechanisms that were not possible for eukaryotic cells; they became endosymbionts living inside the eukaryote. In the autogenous hypothesis, mitochondria were born by splitting off a portion of DNA from the nucleus of the eukaryotic cell at the time of divergence with the prokaryotes; this DNA portion would have been enclosed by membranes, which could not be crossed by proteins. Since mitochondria have many features in common with bacteria, the endosymbiotic hypothesis is more widely accepted.
Gottfried Schatz
Schatz played a leading role in elucidating the biogenesis of mitochondria and in discovering mitochondrial DNA. He recognized that this DNA encoded only a small number of mitochondrial proteins which was decisive for his further research on the import of proteins into the mitochondria and the degradation of proteins within these organelles. Schatz discovered a complex transport system that recognizes mitochondrial proteins made in the cytoplasm by specific signals attached to these proteins and then transfers them into the mitochondria. This system comprises two protein complexes, TOM and TIM, which are localized in the outer and inner mitochondrial membranes respectively. Mutations in these complexes can disrupt protein import and cause illnesses such as the neurodegenerative Mohr-Tranebjaerg syndrome, which leads to deafness. Schatz also demonstrated that the energy-requiring protease Lon regulates protein turnover within the mitochondria, thus maintaining the integrity and the proper functioning of mitochondrial DNA. Gottfried Schatz is the author of more than 200 scientific publications, three volumes of essays, an autobiography and a novel. His books have appeared in English, French, Greek and Czech translation.
Human mitochondrial genetics
In total, the mitochondrion hosts about 3000 different types of proteins, but only about 13 of them are coded on the mitochondrial DNA. Most of the 3000 types of proteins are involved in a variety of processes other than ATP production, such as porphyrin synthesis. Only about 3% of them code for ATP production proteins. This means most of the genetic information coding for the protein makeup of mitochondria is in chromosomal DNA and is involved in processes other than ATP synthesis. This increases the chances that a mutation that will affect a mitochondrion will occur in chromosomal DNA, which is inherited in a Mendelian pattern. Another result is that a chromosomal mutation will affect a specific tissue due to its specific needs, whether those may be high energy requirements or a need for the catabolism or anabolism of a specific neurotransmitter or nucleic acid. Because several copies of the mitochondrial genome are carried by each mitochondrion (2–10 in humans), mitochondrial mutations can be inherited maternally by mtDNA mutations which are present in mitochondria inside the oocyte before fertilization, or (as stated above) through mutations in the chromosomes.
Human mitochondrial genetics
Human mtDNA can also be used to help identify individuals. Forensic laboratories occasionally use mtDNA comparison to identify human remains, and especially to identify older unidentified skeletal remains. Although unlike nuclear DNA, mtDNA is not specific to one individual, it can be used in combination with other evidence (anthropological evidence, circumstantial evidence, and the like) to establish identification. mtDNA is also used to exclude possible matches between missing persons and unidentified remains. Many researchers believe that mtDNA is better suited to identification of older skeletal remains than nuclear DNA because the greater number of copies of mtDNA per cell increases the chance of obtaining a useful sample, and because a match with a living relative is possible even if numerous maternal generations separate the two. American outlaw Jesse James's remains were identified using a comparison between mtDNA extracted from his remains and the mtDNA of the son of the female-line great-granddaughter of his sister. Similarly, the remains of Alexandra Feodorovna (Alix of Hesse), last Empress of Russia, and her children were identified by comparison of their mitochondrial DNA with that of Prince Philip, Duke of Edinburgh, whose maternal grandmother was Alexandra's sister Victoria of Hesse. Similarly to identify Emperor Nicholas II remains his mitochondrial DNA was compared with that of James Carnegie, 3rd Duke of Fife, whose maternal great-grandmother Alexandra of Denmark (Queen Alexandra) was sister of Nicholas II mother Dagmar of Denmark (Empress Maria Feodorovna).
Cytochrome c oxidase subunit I
One of 37 mitochondrial genes, the "MT-CO1" gene is located from nucleotide pairs 5904 to 7444 on the guanine-rich heavy (H) section of mtDNA. The gene product is a 57 kDa protein composed of 513 amino acids..
Most recent common ancestor
Mitochondrial DNA (mtDNA) is nearly immune to sexual mixing, unlike the nuclear DNA whose chromosomes are shuffled and recombined in Mendelian inheritance. Mitochondrial DNA, therefore, can be used to trace matrilineal inheritance and to find the Mitochondrial Eve (also known as the "African Eve"), the most recent common ancestor of all humans via the mitochondrial DNA pathway.
Robin Crutchfield
With DNA
Mitochondrial DNA
Great variation in mtDNA gene content and size exists among fungi and plants, although there appears to be a core subset of genes that are present in all eukaryotes (except for the few that have no mitochondria at all).
Some plant species have enormous mitochondrial genomes, with "Silene conica" mtDNA containing as many as 11,300,000 base pairs. Surprisingly, even those huge mtDNAs contain the same number and kinds of genes as related plants with much smaller mtDNAs.
The genome of the mitochondrion of the cucumber ("Cucumis sativus") consists of three circular chromosomes (lengths 1556, 84 and 45 kilobases), which are entirely or largely autonomous with regard to their replication.
Macro-haplogroup L (mtDNA)
In human mitochondrial genetics, L is the mitochondrial DNA macro-haplogroup that is at the root of the human mtDNA phylogenetic tree. As such, it represents the most ancestral mitochondrial lineage of all currently living modern humans, also dubbed "Mitochondrial Eve".
Peer M. Schatz
Schatz is married to Nadine Schatz-Grandjean-Perrenoud-Contesse, a Swiss citizen and likewise an alumna of the University of St. Gallen. He is the son of famous biochemist Gottfried Schatz, who co-discovered mitochondrial DNA.
Mendel Lectures
The Mendel Lectures are also connected with the establishment of the Mendel Museum and revitalization of scientific activities in the Augustinian Abbey in Old Brno in 2003 in the event of the 50th anniversary of the discovery of the structure of deoxyribonucleic acid (DNA). The British Council donated a copy of the original photograph of James Watson and Francis Crick and a copy of their model of DNA from 1953 is on loan from Gustav Ammerer to the Mendel Museum.
Human variability
Mitochondrial DNA, which is only passed from mother to child. The first human population studies based on mitochondrial DNA were performed by restriction enzyme analyses (RFLPs) and revealed differences between the four ethnic groups (Caucasian, Amerindian, African, and Asian). Differences in mtDNA patterns have also been shown in communities with a different geographic origin within the same ethnic group
Mitochondrial disease
Mitochondrial DNA mutations occur frequently, due to the lack of the error checking capability that nuclear DNA has (see Mutation rate). This means that mitochondrial DNA disorders may occur spontaneously and relatively often. Defects in enzymes that control mitochondrial DNA replication (all of which are encoded for by genes in the nuclear DNA) may also cause mitochondrial DNA mutations.
Mitochondrial DNA (journal)
Coverage includes:Previously published under the title "DNA Sequence" (Vols 1-19.3), "Mitochondrial DNA" accepts original high-quality reports based on mapping, sequencing and analysis of mitochondrial DNA and RNA. Descriptive papers on DNA sequences from mitochondrial genomes, and also analytical papers in the areas of population genetics, medical genetics, phylogenetics and human evolution that use mitochondrial DNA as a source of evidence for studies will be considered for publication. The editorial board will also consider manuscripts that examine population genetic and systematic theory that specifically address the use of mitochondrial DNA sequences, as well as papers that discuss the utility of mitochondrial DNA information in medical studies and in human evolutionary biology.
Human mitochondrial genetics
It was originally incorrectly believed that the mitochondrial genome contained only 13 protein-coding genes, all of them encoding proteins of the electron transport chain. However, in 2001, a 14th biologically active protein called humanin was discovered, and was found to be encoded by the mitochondrial gene MT-RNR2 which also encodes part of the mitochondrial ribosome (made out of RNA):
Mitochondrial DNA
An IVF technique known as mitochondrial donation or mitochondrial replacement therapy (MRT) results in offspring containing mtDNA from a donor female, and nuclear DNA from the mother and father. In the spindle transfer procedure, the nucleus of an egg is inserted into the cytoplasm of an egg from a donor female which has had its nucleus removed, but still contains the donor female's mtDNA. The composite egg is then fertilized with the male's sperm. The procedure is used when a woman with genetically defective mitochondria wishes to procreate and produce offspring with healthy mitochondria. The first known child to be born as a result of mitochondrial donation was a boy born to a Jordanian couple in Mexico on 6 April 2016.
Mitochondrial disease
Most mitochondrial function and biogenesis is controlled by nuclear DNA. Human mitochondrial DNA encodes 13 proteins of the respiratory chain, while most of the estimated 1,500 proteins and components targeted to mitochondria are nuclear-encoded. Defects in nuclear-encoded mitochondrial genes are associated with hundreds of clinical disease phenotypes including anemia, dementia, hypertension, lymphoma, retinopathy, seizures, and neurodevelopmental disorders.
Roger Hendrix (biologist)
Roger W. Hendrix (July 7, 1943 – August 15, 2017) was an American biologist, focusing in bacteriophage biology, and a Distinguished Professor at University of Pittsburgh.. He studied biology at the California Institute of Technology and went on to obtain his Ph.D. from Harvard University under the supervision of James Watson, the co-discoverer of the structure of DNA. In 2009, he received the NAS Award for Scientific Reviewing.
Multiregional origin of modern humans
A 1987 analysis of mitochondrial DNA from 147 people by Cann "et al". from around the world indicated that their mitochondrial lineages all coalesced in a common ancestor from Africa between 140,000 and 290,000 years ago. The analysis suggested that this reflected the worldwide expansion of modern humans as a new species, replacing, rather than mixing with, local archaic humans outside of Africa. Such a recent replacement scenario is not compatible with the Multiregional hypothesis and the mtDNA results led to increased popularity for the alternative single replacement theory. According to Wolpoff and colleagues:
Mitochondrion
The near-absence of genetic recombination in mitochondrial DNA makes it a useful source of information for scientists involved in population genetics and evolutionary biology. Because all the mitochondrial DNA is inherited as a single unit, or haplotype, the relationships between mitochondrial DNA from different individuals can be represented as a gene tree. Patterns in these gene trees can be used to infer the evolutionary history of populations. The classic example of this is in human evolutionary genetics, where the molecular clock can be used to provide a recent date for mitochondrial Eve. This is often interpreted as strong support for a recent modern human expansion out of Africa. Another human example is the sequencing of mitochondrial DNA from Neanderthal bones. The relatively large evolutionary distance between the mitochondrial DNA sequences of Neanderthals and living humans has been interpreted as evidence for the lack of interbreeding between Neanderthals and anatomically modern humans.
Mitochondrial Eve
Because mtDNA mapping of humans is very incomplete, the discovery of living mtDNA lines which predate our current concept of "Mitochondrial Eve" could result in the title moving to an earlier woman. This happened to her male counterpart, "Y-chromosomal Adam," when older Y lines from Africa were discovered.
Mitochondrial disease
Nuclear DNA has two copies per cell (except for sperm and egg cells), one copy being inherited from the father and the other from the mother. Mitochondrial DNA, however, is strictly inherited from the mother and each mitochondrial organelle typically contains between 2 and 10 mtDNA copies. During cell division the mitochondria segregate randomly between the two new cells. Those mitochondria make more copies, normally reaching 500 mitochondria per cell. As mtDNA is copied when mitochondria proliferate, they can accumulate random mutations, a phenomenon called heteroplasmy. If only a few of the mtDNA copies inherited from the mother are defective, mitochondrial division may cause most of the defective copies to end up in just one of the new mitochondria (for more detailed inheritance patterns, see human mitochondrial genetics). Mitochondrial disease may become clinically apparent once the number of affected mitochondria reaches a certain level; this phenomenon is called "threshold expression".
Temperature gradient gel electrophoresis
According to a recent investigation by Wong, Liang, Kwon, Bai, Alper and Gropman, TGGE can be utilized to examine the mitochondrial DNA of an individual. According to these authors, TGGE was utilized to determine two novel mutations in the mitochondrial genome: "A 21-year-old woman who has been suspected of mitochondrial cytopathy, but negative for common mitochondrial DNA (mtDNA) point mutations and deletions, was screened for unknown mutations in the entire mitochondrial genome by temperature gradient gel electrophoresis".