Somatic cell nuclear transfer - wikipedia Somatic cell nuclear transfer Jump to : navigation , search Somatic cell nuclear transfer can create clones for both reproductive and therapeutic purposes . The diagram depicts the removal of the donor nucleus for schematic purposes ; in practice the whole donor cell is transferred . In genetics and developmental biology , somatic cell nuclear transfer ( SCNT ) is a laboratory strategy for creating a viable embryo from a body cell and an egg cell . The technique consists of taking an enucleated oocyte ( egg cell ) and implanting a donor nucleus from a somatic ( body ) cell . It is used in both therapeutic and reproductive cloning . Dolly the Sheep became famous for being the first successful case of the reproductive cloning of a mammal . `` Therapeutic cloning '' refers to the potential use of SCNT in regenerative medicine ; this approach has been championed as an answer to the many issues concerning embryonic stem cells ( ESC ) and the destruction of viable embryos for medical use , though questions remain on how homologous the two cell types truly are . Contents ( hide ) 1 Process 2 Applications 2.1 Stem cell research 2.2 Reproductive cloning 2.3 Interspecies nuclear transfer 3 Limitations 4 Controversy 5 Policies regarding human SCNT 6 See also 7 References 8 Further reading 9 External links Process ( edit ) The process of somatic cell nuclear transplant involves two different cells . The first being a female gamete , known as the ovum ( egg / oocyte ) . In human SCNT ( Somatic Cell Nuclear Transfer ) experiments , these eggs are obtained through consenting donors , utilizing ovarian stimulation . The second being a somatic cell , referring to the cells of the human body . Skin cells , fat cells , and liver cells are only a few examples . The nucleus of the donor egg cell is removed and discarded , leaving it ' deprogrammed . ' What is left is a somatic cell and an unnucleated egg cell . These are then fused by inserting the somatic cell into the ' empty ' ovum . After being inserted into the egg , the somatic cell nucleus is reprogrammed by its host egg cell . The ovum , now containing the somatic cell 's nucleus , is stimulated with a shock and will begin to divide . The egg is now viable and capable of producing an adult organism containing all the necessary genetic information from just one parent . Development will ensue normally and after many mitotic divisions , this single cell forms a blastocyst ( an early stage embryo with about 100 cells ) with an identical genome to the original organism ( i.e. a clone ) . Stem cells can then be obtained by the destruction of this clone embryo for use in therapeutic cloning or in the case of reproductive cloning the clone embryo is implanted into a host mother for further development and brought to term . Applications ( edit ) Stem cell research ( edit ) Somatic cell nuclear transplantation has become a focus of study in stem cell research . The aim of carrying out this procedure is to obtain pluripotent cells from a cloned embryo . These cells genetically matched the donor organism from which they came. This gives them the ability to create patient specific pluripotent cells , which could then be used in therapies or disease research . Embryonic stem cells are undifferentiated cells of an embryo . These cells are deemed to have a pluripotent potential because they have the ability to give rise to all of the tissues found in an adult organism . This ability allows stem cells to create any cell type , which could then be transplanted to replace damaged or destroyed cells . Controversy surrounds human ESC work due to the destruction of viable human embryos . Leading scientists to seek an alternative method of obtaining stem cells , SCNT is one such method . Human Embryonic Stem cell colony on mouse embryonic fibroblast feeder layer . A potential use of stem cells genetically matched to a patient would be to create cell lines that have genes linked to a patient 's particular disease . By doing so , an in vitro model could be created , would be useful for studying that particular disease , potentially discovering its pathophysiology , and discovering therapies . For example , if a person with Parkinson 's disease donated his or her somatic cells , the stem cells resulting from SCNT would have genes that contribute to Parkinson 's disease . The disease specific stem cell lines could then be studied in order to better understand the condition . Another application of SCNT stem cell research is using the patient specific stem cell lines to generate tissues or even organs for transplant into the specific patient . The resulting cells would be genetically identical to the somatic cell donor , thus avoiding any complications from immune system rejection . Only a handful of the labs in the world are currently using SCNT techniques in human stem cell research . In the United States , scientists at the Harvard Stem Cell Institute , the University of California San Francisco , the Oregon Health & Science University , Stemagen ( La Jolla , CA ) and possibly Advanced Cell Technology are currently researching a technique to use somatic cell nuclear transfer to produce embryonic stem cells . In the United Kingdom , the Human Fertilisation and Embryology Authority has granted permission to research groups at the Roslin Institute and the Newcastle Centre for Life . SCNT may also be occurring in China . In 2005 , a South Korean research team led by Professor Hwang Woo - suk , published claims to have derived stem cell lines via SCNT , but supported those claims with fabricated data . Recent evidence has proved that he in fact created a stem cell line from a parthenote . Though there has been numerous successes with cloning animals , questions remain concerning the mechanisms of reprogramming in the ovum . Despite many attempts , success in creating human nuclear transfer embryonic stem cells has been limited . There lies a problem in the human cell 's ability to form a blastocyst ; the cells fail to progress past the eight cell stage of development . This is thought to be a result from the somatic cell nucleus being unable to turn on embryonic genes crucial for proper development . These earlier experiments used procedures developed in non-primate animals with little success . A research group from the Oregon Health & Science University demonstrated SCNT procedures developed for primates successfully reprogrammed skin cells into stem cells . The key to their success was utilizing oocytes in metaphase II ( MII ) of the cell cycle . Egg cells in MII contain special factors in the cytoplasm that have a special ability in reprogramming implanted somatic cell nuclei into cells with pluripotent states . When the ovum 's nucleus is removed , the cell loses its genetic information . This has been blamed for why enucleated eggs are hampered in their reprogramming ability . It is theorized the critical embryonic genes are physically linked to oocyte chromosomes , enucleation negatively affects these factors . Another possibility is removing the egg nucleus or inserting the somatic nucleus causes damage to the cytoplast , affecting reprogramming ability . Taking this into account the research group applied their new technique in an attempt to produce human SCNT stem cells . In May 2013 , the Oregon group reported the successful derivation of human embryonic stem cell lines derived through SCNT , using fetal and infant donor cells . Using MII oocytes from volunteers and their improved SCNT procedure , human clone embryos were successfully produced . These embryos were of poor quality , lacking a substantial inner cell mass and poorly constructed trophectoderm . The imperfect embryos prevented the acquisition of human ESC . The addition of caffeine during the removal of the ovum 's nucleus and injection of the somatic nucleus improved blastocyst formation and ESC isolation . The ESC obtain were found to be capable of producing teratomas , expressed pluripotent transcription factors , and expressed a normal 46XX karyotype , indicating these SCNT were in fact ESC - like . This was the first instance of successfully using SCNT to reprogram human somatic cells . This study used fetal and infantile somatic cells to produce their ESC . In April 2014 , an international research team expanded on this break through . There remained the question of whether the same success could be accomplished using adult somatic cells . Epigenetic and age related changes were thought to possibly hinder an adult somatic cells ability to be reprogrammed . Implementing the procedure pioneered by the Oregon research group they indeed were able to grow stem cells generated by SCNT using adult cells from two donors , aged 35 and 75. Indicating age does not impede a cells ability to be reprogrammed Late April 2014 , the New York Stem Cell Foundation was successful in creating SCNT stem cells derived from adult somatic cells . One of these lines of stem cells was derived from the donor cells of a type 1 diabetic . The group was then able to successfully culture these stem cells and induce differentiation . When injected into mice , cells of all three of the germ layers successfully formed . The most significant of these cells , were those who expressed insulin and were capable of secreting the hormone . These insulin producing cells could be used for replacement therapy in diabetics , demonstrating real SCNT stem cell therapeutic potential . The impetus for SCNT - based stem cell research has been decreased by the development and improvement of alternative methods of generating stem cells . Methods to reprogram normal body cells into pluripotent stem cells were developed in humans in 2007 . The following year , this method achieved a key goal of SCNT - based stem cell research : the derivation of pluripotent stem cell lines that have all genes linked to various diseases . Some scientists working on SCNT - based stem cell research have recently moved to the new methods of induced pluripotent stem cells . Though recent studies have put in question how similar iPS cells are to embryonic stem cells . Epigenetic memory in iPS affects the cell lineage it can differentiate into . For instance , an iPS cell derived from a blood cell will be more efficient at differentiating into blood cells , while it will be less efficient at creating a neuron . This raises the question of how well iPS cells can mimic the gold standard ESC in experiments , as stem cells are defined as having the ability to differentiate into any cell type . SCNT stem cells do not pose such a problem and continue to remain relevant in stem cell studies . Reproductive cloning ( edit ) Main article : Cloning BTX ECM 2001 Electrofusion generator used for SCNT and Cloning applications This technique is currently the basis for cloning animals ( such as the famous Dolly the sheep ) , and has been theoretically proposed as a possible way to clone humans . Using SCNT in reproductive cloning has proven difficult with limited success . High fetal and neonatal death make the process very inefficient . Resulting cloned offspring are also plagued with development and imprinting disorders in non-human species . For these reasons , along with moral and ethical objections , reproductive cloning in humans is proscribed in more than 30 countries . Most researchers believe that in the foreseeable future it will not be possible to use the current cloning technique to produce a human clone that will develop to term . It remains a possibility , though critical adjustments will be required to overcome current limitations during early embryonic development in human SCNT . There is also the potential for treating diseases associated with mutations in mitochondrial DNA . Recent studies show SCNT of the nucleus of a body cell afflicted with one of these diseases into a healthy oocyte prevents the inheritance of the mitochondrial disease . This treatment does not involve cloning but would produce a child with three genetic parents . A father providing a sperm cell , one mother providing the egg nucleus and another mother providing the enucleated egg cell . Interspecies nuclear transfer ( edit ) Interspecies nuclear transfer ( iSCNT ) is a means of somatic cell nuclear transfer used to facilitate the rescue of endangered species , or even to restore species after their extinction . The technique is similar to SCNT cloning which typically is between domestic animals and rodents , or where there is a ready supply of oocytes and surrogate animals . However , the cloning of highly endangered or extinct species requires the use of an alternative method of cloning . Interspecies nuclear transfer utilizes a host and a donor of two different organisms that are closely related species and within the same genus . In 2000 , Robert Lanza was able to produce a cloned fetus of a gaur , Bos gaurus , combining it successfully with a domestic cow , Bos taurus . Interspecies nuclear transfer provides evidence of the universality of the triggering mechanism of the cell nucleus reprogramming . For example , Gupta et al. , explored the possibility of producing transgenic cloned embryos by interspecies somatic cell nuclear transfer ( iSCNT ) of cattle , mice , and chicken donor cells into enucleated pig oocytes . Moreover , NCSU23 medium , which was designed for in vitro culture of pig embryos , was able to support the in vitro development of cattle , mice , and chicken iSCNT embryos up to the blastocyst stage . Furthermore , ovine oocyte cytoplast may be used for remodeling and reprogramming of human somatic cells back to the embryonic stage . Limitations ( edit ) This section needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . ( August 2016 ) ( Learn how and when to remove this template message ) SCNT can be inefficient . Stresses placed on both the egg cell and the introduced nucleus in early research were enormous , resulting in a low percentage of successfully reprogrammed cells . For example , in 1996 Dolly the sheep was born after 277 eggs were used for SCNT , which created 29 viable embryos . Only three of these embryos survived until birth , and only one survived to adulthood . As the procedure was not automated , but had to be performed manually under a microscope , SCNT was very resource intensive . The biochemistry involved in reprogramming the differentiated somatic cell nucleus and activating the recipient egg was also far from understood . However , by 2014 , researchers were reporting success rates of 70 - 80 % with cloning pigs and in 2016 a Korean company , Sooam Biotech , was reported to be producing 500 cloned embryos a day . In SCNT , not all of the donor cell 's genetic information is transferred , as the donor cell 's mitochondria that contain their own mitochondrial DNA are left behind . The resulting hybrid cells retain those mitochondrial structures which originally belonged to the egg . As a consequence , clones such as Dolly that are born from SCNT are not perfect copies of the donor of the nucleus . This fact may also hamper the potential benefits of SCNT derived tissues / organs for therapy , as there may be an immunoresponse to the non-self mtDNA after transplant . Controversy ( edit ) Further information : stem cell controversy Human Blastocyst , showing the inner cell mass ( top , right ) . Proposals to use nucleus transfer techniques in human stem cell research raise a set of concerns beyond the moral status of any created embryo . These have led to some individuals and organizations who are not opposed to human embryonic stem cell research to be concerned about , or opposed to , SCNT research . One concern is that blastula creation in SCNT - based human stem cell research will lead to the reproductive cloning of humans . Both processes use the same first step : the creation of a nuclear transferred embryo , most likely via SCNT . Those who hold this concern often advocate for strong regulation of SCNT to preclude implantation of any derived products for the intention of human reproduction , or its prohibition . A second important concern is the appropriate source of the eggs that are needed . SCNT requires human eggs , which can only be obtained from women . The most common source of these eggs today are eggs that are produced and in excess of the clinical need during IVF treatment . This is a minimally invasive procedure , but it does carry some health risks , such as ovarian hyperstimulation syndrome . One vision for successful stem cell therapies is to create custom stem cell lines for patients . Each custom stem cell line would consist of a collection of identical stem cells each carrying the patient 's own DNA , thus reducing or eliminating any problems with rejection when the stem cells were transplanted for treatment . For example , to treat a man with Parkinson 's disease , a cell nucleus from one of his cells would be transplanted by SCNT into an egg cell from an egg donor , creating a unique lineage of stem cells almost identical to the patient 's own cells . ( There would be differences . For example , the mitochondrial DNA would be the same as that of the egg donor . In comparison , his own cells would carry the mitochondrial DNA of his mother . ) Potentially millions of patients could benefit from stem cell therapy , and each patient would require a large number of donated eggs in order to successfully create a single custom therapeutic stem cell line . Such large numbers of donated eggs would exceed the number of eggs currently left over and available from couples trying to have children through assisted reproductive technology . Therefore , healthy young women would need to be induced to sell eggs to be used in the creation of custom stem cell lines that could then be purchased by the medical industry and sold to patients . It is so far unclear where all these eggs would come from . Stem cell experts consider it unlikely that such large numbers of human egg donations would occur in a developed country because of the unknown long - term public health effects of treating large numbers of healthy young women with heavy doses of hormones in order to induce hyperovulation ( ovulating several eggs at once ) . Although such treatments have been performed for several decades now , the long - term effects have not been studied or declared safe to use on a large scale on otherwise healthy women . Longer - term treatments with much lower doses of hormones are known to increase the rate of cancer decades later . Whether hormone treatments to induce hyperovulation could have similar effects is unknown . There are also ethical questions surrounding paying for eggs . In general , marketing body parts is considered unethical and is banned in most countries . Human eggs have been a notable exception to this rule for some time . To address the problem of creating a human egg market , some stem cell researchers are investigating the possibility of creating artificial eggs . If successful , human egg donations would not be needed to create custom stem cell lines . However , this technology may be a long way off . Policies regarding human SCNT ( edit ) SCNT involving human cells is currently legal for research purposes in the United Kingdom , having been incorporated into the Human Fertilisation and Embryology Act 1990 . Permission must be obtained from the Human Fertilisation and Embryology Authority in order to perform or attempt SCNT . In the United States , the practice remains legal , as it has not been addressed by federal law . However , in 2002 , a moratorium on United States federal funding for SCNT prohibits funding the practice for the purposes of research . Thus , though legal , SCNT can not be federally funded . American scholars have recently argued that because the product of SCNT is a clone embryo , rather than a human embryo , these policies are morally wrong and should be revised . In 2003 , the United Nations adopted a proposal submitted by Costa Rica , calling on member states to `` prohibit all forms of human cloning in as much as they are incompatible with human dignity and the protection of human life . '' This phrase may include SCNT , depending on interpretation . The Council of Europe 's Convention on Human Rights and Biomedicine and its Additional Protocol to the Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine , on the Prohibition of Cloning Human Being appear to ban SCNT of human beings . Of the Council 's 45 member states , the Convention has been signed by 31 and ratified by 18 . The Additional Protocol has been signed by 29 member nations and ratified by 14 . See also ( edit ) Induced stem cells Stem cell research Stem cell controversy Embryogenesis In vitro fertilisation Cloning New Jersey legislation S1909 / A2840 Rejuvenation References ( edit ) Jump up ^ Li , J ; Liu , X ; Wang , H ; Zhang , S ; Liu , F ; Wang , X ; Wang , Y ( 2009 ) . `` Human embryos derived by somatic cell nuclear transfer using an alternative enucleation approach '' . Cloning and Stem Cells. 11 ( 1 ) : 39 -- 50 . PMID 19196043 . doi : 10.1089 / clo. 2008.0041 . Jump up ^ Pattinson , Shaun D. ; Kind , Vanessa ( 2017 - 09 - 12 ) . `` Using a moot to develop students ' understanding of human cloning and statutory interpretation '' . Medical Law International . doi : 10.1177 / 0968533217726350 . Jump up ^ Wilmut , I. ; Schnieke , A.E. ; McWhir , J. ; Kind , A.J. ; Campbell , K.H.S. ( 1997 ) . `` Viable offspring derived from fetal and adult mammalian cells '' . Nature . 385 ( 6619 ) : 810 -- 813 . PMID 9039911 . doi : 10.1038 / 385810a0 . Jump up ^ Lomax , G.P. ; Dewitt , N.D. ( 2013 ) . `` Somatic cell nuclear transfer in Oregon : Expanding the pluripotent space and informing research ethics '' . Stem Cells and Development . 22 Suppl 1 : 25 -- 8 . PMID 24304071 . doi : 10.1089 / scd. 2013.0402 . Jump up ^ Lo , B ; Parham , L ( 2009 ) . `` Ethical issues in stem cell research '' . Endocrine Reviews . 30 ( 3 ) : 204 -- 13 . PMC 2726839 . PMID 19366754 . doi : 10.1210 / er. 2008 - 0031 . ^ Jump up to : Semb H ( 2005 ) . `` Human embryonic stem cells : origin , properties and applications '' . APMIS. 113 ( 11 -- 12 ) : 743 -- 50 . PMID 16480446 . doi : 10.1111 / j. 1600 - 0463.2005. apm_312. x . ^ Jump up to : Pera , M ; Trounson , A ( 2013 ) . `` Cloning debate : Stem - cell researchers must stay engaged '' . Nature . 498 ( 7453 ) : 159 -- 61 . PMID 23765475 . doi : 10.1038 / 498159a . Jump up ^ Hadjantonakis AK , Papaioannou VE ( July 2002 ) . `` Can mammalian cloning combined with embryonic stem cell technologies be used to treat human diseases ? '' . Genome Biol. 3 ( 8 ) : REVIEWS1023 . PMC 139399 . PMID 12186652 . doi : 10.1186 / gb - 2002 - 3 - 8 - reviews1023 . ^ Jump up to : Tachibana M ( 2013 ) . `` Human Embryonic Stem Cells Derived by Somatic Cell Nuclear Transfer '' . Cell. 153 : 1228 -- 38 . PMC 3772789 . PMID 23683578 . doi : 10.1016 / j. cell. 2013.05. 006 . Jump up ^ Elizabeth Weise , `` Cloning race is on again '' , USA Today ( January 17 , 2006 , retrieved October 6 , 2006 ) Jump up ^ `` Dolly scientists ' human clone bid '' , BBC News ( September 28 , 2004 , retrieved October 6 , 2006 ) Jump up ^ Charles C. Mann , `` The First Cloning Superpower '' , Wired ( January 2003 , retrieved October 6 , 2006 ) Jump up ^ Hwang WS , Roh SI , Lee BC , et al. ( June 2005 ) . `` Patient - specific embryonic stem cells derived from human SCNT blastocysts '' . Science . 308 ( 5729 ) : 1777 -- 83 . PMID 15905366 . doi : 10.1126 / science. 1112286 . ( Retracted ) Jump up ^ Kennedy D ( January 2006 ) . `` Editorial retraction '' . Science . 311 ( 5759 ) : 335 . PMID 16410485 . doi : 10.1126 / science. 1124926 . Jump up ^ ( 1 ) , Nature Stem Cell Blog . Jump up ^ ( 2 ) , The Scientist 19 June 2007 Jump up ^ Human Somatic Cell Nuclear Transfer Using Adult Cells Cell Stem Cell . Retrieved 18 April 2014 Jump up ^ Ariana Eunjung Cha ( 18 April 2014 ) Cloning advance using stem cells from human adult reopens ethical questions Washington Post . Retrieved 18 April 2014 Jump up ^ Yamada , M ; Johannesson , B ; Sagi , I ; Burnett , L.C. ; Kort , D.H. ; Prosser , R.W. ; Paull , D ; Nestor , M.W. ; Freeby , M ; Greenberg , E ; Goland , R.S. ; Leibel , R.L. ; Solomon , S.L. ; Benvenisty , N ; Sauer , M.V. ; Egli , D ( 2014 ) . `` Human oocytes reprogram adult somatic nuclei of a type 1 diabetic to diploid pluripotent stem cells '' . Nature . 510 ( 7506 ) : 533 -- 6 . PMID 24776804 . doi : 10.1038 / nature13287 . Jump up ^ Gretchen Vogel ( December 2008 ) . `` Breakthrough of the year : Reprogramming Cells '' . Science . 322 ( 5909 ) : 1766 -- 1767 . PMID 19095902 . doi : 10.1126 / science. 322.5909. 1766 . Jump up ^ Kim , K. ; Doi , A. ; Wen , B. ; Ng , K. ; Zhao , R. ; Cahan , P. ; Kim , J. ; Aryee , M.J. ; Ji , H. ; Ehrlich , L.I.R. ; Yabuuchi , A. ; Takeuchi , A. ; Cunniff , K.C. ; Hongguang , H. ; McKinney - Freeman , S. ; Naveiras , O. ; Yoon , T.J. ; Irizarry , R.A. ; Jung , N. ; Seita , J. ; Hanna , J. ; Murakami , P. ; Jaenisch , R. ; Weissleder , R. ; Orkin , S.H. ; Weissman , I.L. ; Feinberg , A.P. ; Daley , G.Q. ( 2010 ) . `` Epigenetic memory in induced pluripotent stem cells '' . Nature . 467 ( 7313 ) : 285 -- 90 . PMC 3150836 . PMID 20644535 . doi : 10.1038 / nature09342 . ^ Jump up to : Campbell KH , McWhir J , Ritchie WA , Wilmut I ( March 1996 ) . `` Sheep cloned by nuclear transfer from a cultured cell line '' . Nature . 380 ( 6569 ) : 64 -- 6 . PMID 8598906 . doi : 10.1038 / 380064a0 . Jump up ^ Ethics Committee of the American Society for Reproductive Medicine ( 2012 ) . `` Human somatic cell nuclear transfer and cloning '' . Fertility and Sterility. 98 ( 4 ) : 804 -- 7 . PMID 22795681 . doi : 10.1016 / j. fertnstert. 2012.06. 045 . Jump up ^ Revel M ( 2000 ) . `` Research on animal cloning technologies and their implications in medical ethics : an update '' . Med Law . 19 ( 3 ) : 527 -- 43 . PMID 11143888 . Jump up ^ Rhind SM , Taylor JE , De Sousa PA , King TJ , McGarry M , Wilmut I ( November 2003 ) . `` Human cloning : can it be made safe ? '' . Nat. Rev. Genet. 4 ( 11 ) : 855 -- 64 . PMID 14634633 . doi : 10.1038 / nrg1205 . Jump up ^ Lanza , Robert P. ; Jose B. Cibelli ; Francisca A. Diaz ; Carlos T. Moraes ; Peter W. Farin ; Charlotte E. Farin ; Carolyn J. Hammer ; Michael D. West ; Philip Damiani ( 2000 ) . `` Cloning of an endangered species ( Bos gaurus ) using interspecies nuclear transfer '' ( PDF ) . Cloning. 2 ( 2 ) : 79 -- 90 . doi : 10.1089 / 152045500436104 . Retrieved 10 December 2013 . Jump up ^ Gupta , M.K. ; Das , Z.C. ; Heo , Y.T. ; Uhm , S.J. ( 2013 ) . `` Transgenic Chicken , Mice , Cattle , and Pig Embryos by Somatic Cell Nuclear Transfer into Pig Oocytes '' . Cellular Reprogramming. 15 ( 4 ) : 322 -- 328 . doi : 10.1089 / cell. 2012.0074 . Jump up ^ Hosseini , S. Morteza ; Hajian , Mehdi ; Forouzanfar , Mohsen ; Nasr - Esfahani , Mohammad H. ( April 2012 ) . `` Enucleated Ovine Oocyte Supports Human Somatic Cells Reprogramming Back to the Embryonic Stage '' . Cellular Reprogramming. 14 ( 2 ) : 155 -- 163 . PMID 22384929 . doi : 10.1089 / cell. 2011.0061 . Jump up ^ Shukman , David ( 14 January 2014 ) China cloning on an ' industrial scale ' BBC News Science and Environment , Retrieved 10 April 2014 Jump up ^ Zastrow , Mark ( 8 February 2016 ) . `` Inside the cloning factory that creates 500 new animals a day '' . New Scientist . Retrieved 23 February 2016 . ^ Jump up to : Jeremy Rifkin . ( February 18 , 2002 ) . `` Fusion Biopolitics '' . The Nation . Retrieved on August 7 , 2006 . Jump up ^ Sheryl Gay Stolberg , `` Some for Abortion Rights Lean Right in Cloning Fight '' , New York Times ( January 24 , 2002 ) Jump up ^ Lori B. Andrews , et al. , Open Letter to US Senate on Human Cloning , ( March 19 , 2002 ) Jump up ^ Lori B. Andrews et al. ( March 19 , 2002 ). `` Open Letter to US Senators on Human Cloning and Eugenic Engineering '' . Retrieved on August 7 , 2006 Jump up ^ Andy Coghlan , `` Cloning opponents fear loopholes in new UK law '' , New Scientist ( November 23 , 2001 , retrieved October 6 , 2006 ) Jump up ^ Pattinson , Shaun D. ; Kind , Vanessa ( 2017 - 09 - 12 ) . `` Using a moot to develop students ' understanding of human cloning and statutory interpretation '' . Medical Law International . doi : 10.1177 / 0968533217726350 . Jump up ^ `` Chapter 5 : Legal and Policy Considerations . Cloning Human Beings '' Report and Recommendations of the National Bioethics Advisory Commission , June 1997 . Accessed 21 Oct 06 Jump up ^ Robertson , John A ( 2010 ) . `` Embryo Stem Cell Research : Ten Years of Controversy '' . The Journal of Law , Medicine , & Ethics. 38 ( 2 ) : 191 -- 203 . doi : 10.1111 / j. 1748 - 720x. 2010.00479. x . Jump up ^ Cunningham , Thomas V ( 2013 ) . `` What justifies the United States ban on federal funding for nonreproductive cloning ? '' . Medicine , Health Care and Philosophy. 16 ( 4 ) : 825 -- 841 . doi : 10.1007 / s11019 - 013 - 9465 - 5 . Jump up ^ United Nations , `` General Assembly Adopts United Nations Declaration on Human Cloning By Vote of 84 - 34 - 37 '' , press release ( August 3 , 2005 , retrieved October 6 , 2006 ) Jump up ^ Council of Europe , Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine : Convention on Human Rights and Biomedicine ( April 4 , 1997 , retrieved October 6 , 2006 ) ; Council of Europe , Additional Protocol to the Convention for the Protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine , on the Prohibition of Cloning Human Being ( January 12 , 1998 , retrieved October 6 , 2006 ) Further reading ( edit ) Wilmut I , Beaujean N , de Sousa PA , et al. ( October 2002 ) . `` Somatic cell nuclear transfer '' . Nature . 419 ( 6907 ) : 583 -- 6 . PMID 12374931 . doi : 10.1038 / nature01079 . Kikyo N , Wolffe AP ( January 2000 ) . `` Reprogramming nuclei : insights from cloning , nuclear transfer and heterokaryons '' . J. Cell. Sci. 113 . ( Pt 1 ) : 11 -- 20 . PMID 10591621 . Tian XC , Kubota C , Enright B , Yang X ( November 2003 ) . `` Cloning animals by somatic cell nuclear transfer -- biological factors '' . Reprod. Biol. Endocrinol. 1 ( 1 ) : 98 . PMC 521203 . PMID 14614770 . doi : 10.1186 / 1477 - 7827 - 1 - 98 . Gurdon JB , Byrne JA , Simonsson S ( September 2003 ) . `` Nuclear reprogramming and stem cell creation '' . Proc. Natl. Acad. Sci. U.S.A. 100 . Suppl 1 ( 90001 ) : 11819 -- 22 . PMC 304092 . PMID 12920185 . doi : 10.1073 / pnas. 1834207100 . External links ( edit ) Research Cloning : Medical and scientific , legal and ethical aspects The Basics : Stem Cells and Public Policy The Century Foundation , June 2005 `` Research Cloning Basic Science '' , Center for Genetics and Society , ( Last modified October 4 , 2004 , retrieved October 6 , 2006 ) Cloning : present uses and promises National Institutes of Health , Paper giving background information on cloning in general and SCNT from The Office of Science Policy Analysis . Nuclear Transfer -- Stem Cells or Somatic Cell Nuclear Transfer ( SCNT ) The International Society for Stem Cell Research The Hinxton Group : An International Consortium on Stem Cells , Ethics & Law Retrieved from `` https://en.wikipedia.org/w/index.php?title=Somatic_cell_nuclear_transfer&oldid=806184232 '' Categories : Cloning Genetics Stem cell research Induced stem cells Life extension Hidden categories : Articles needing additional references from August 2016 All articles needing additional references Talk Contents About Wikipedia Dansk Deutsch Español Français 한국어 Italiano Nederlands Português Русский Українська Edit links This page was last edited on 20 October 2017 , at 08 : 01 . Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply . By using this site , you agree to the Terms of Use and Privacy Policy . Wikipedia ® is a registered trademark of the Wikimedia Foundation , Inc. , a non-profit organization . About Wikipedia

Question: to transplant a nucleus from one cell to another cell a scientist would use


Shark tooth - wikipedia Shark tooth Jump to : navigation , search Fossil shark teeth ( Cretaceous ) from southern Israel . Elementorum myologiae specimen , 1669 A shark tooth is one of the numerous teeth of a shark . A shark tooth contains resistant calcium phosphate materials . Sharks continually shed their teeth ; some Carcharhiniformes shed approximately 35,000 teeth in a lifetime , replacing those that fall out . There are four basic types of shark teeth : dense flattened , needle - like , pointed lower with triangular upper , and non-functional . The type of tooth that a shark has depends on its diet and feeding habits . In some formations , shark 's teeth are a common fossil . These fossils can be analyzed for information on shark evolution and biology ; they are often the only part of the shark to be fossilized . Fossil teeth comprise much of the fossil record of the Elasmobranchii , extending back to hundreds of millions of years . Shark teeth are also useful in conducting research about the structure of teeth , shark migration patterns , and identifying shark species . The most ancient types of sharks date back to 450 million years ago , during the Late Ordovician period , and are mostly known by their fossilised teeth . However , the most commonly found fossil shark teeth are from the Cenozoic era ( the last 66 million years ) . Contents ( hide ) 1 Types and Functions 1.1 Dense Flattened Teeth 1.2 Needle - like Teeth 1.3 Pointed Lower Teeth and Triangular Upper Teeth 1.4 Non-Functional Teeth 1.5 Transitional teeth 1.6 Special mention : Megalodon teeth 1.7 Deposits 2 Counting 3 Shark Teeth Research and Identification 4 History of discovery 5 Tool use by humans 6 See also 7 References 8 External links Types and functions ( edit ) Though sharks often are highly specialized , as a category they have ranged widely in their adaptations . Their teeth reflect this , ranging widely in form and function . There are a number of common types of shark teeth , that vary according to the diet of the shark . Examples include dense flattened teeth for crushing ; long needle - like teeth for gripping ; pointed lower teeth for gripping combined with serrated , triangular upper teeth cutting , and teeth that are tiny , greatly reduced , and non-functional . Eastman1901 - web Dense flattened teeth ( edit ) Dense flattened teeth are used to crush prey like bivalves and crustaceans . These Sharks include nurse sharks and angel sharks . They are typically found at the bottom of the ocean floor because this is the habitat in which their prey live . Their teeth are flat in order to easily crack open the shells their prey uses for protection . Needle - like teeth ( edit ) This was the first common style of shark tooth , present in the plentiful cladodont teeth of the devonian , four hundred million years ago . Sharks with needle - like teeth commonly feed on small to medium - sized fish , sometimes including small sharks . These teeth are especially effective for such prey because they can easily grip their slippery and narrow bodies . Modern examples include the blue shark and bull sharks . These sharks specifically use their teeth to feed on small prey like squid , flounder , stingrays , and even hammerhead sharks . Pointed lower teeth and triangular upper teeth ( edit ) This combination of pointed lower teeth with triangular upper teeth are especially useful for cutting prey that consist of large mammals and fish . The combination of teeth entails serrated edges to cut the larger prey into smaller portions in order to easily swallow the pieces . The most famously known shark with these teeth is the Great White shark , which feeds on animals such as sea lions , dolphins , other sharks , and even small whales . Non-functional teeth ( edit ) The teeth of plankton - feeders , such as the basking shark and whale shark , are greatly reduced and non-functional. ( 1 ) These sharks filter feed on prey by opening their mouths to let tiny organisms get sucked into their mouths to feed without using their teeth at all , instead filtering the food when passing water through their gills . Transitional teeth ( edit ) As one species evolves into another , its teeth may become difficult to classify , exhibiting characteristics of both species . For example , teeth from Carcharocles auriculatus as it evolved into C. angustidens , are difficult to definitively identify as coming from either species . A commonly referred to transition is the evolution of Isurus hastalis , the Extinct Giant Mako , into the Great White shark , Carcharodon carcharias . There exist teeth that are believed to represent the transition between the two species . These teeth , from Carcharodon sp . are characterised by the wider , flatter crowns of the Extinct Giant Mako . However , they also exhibit partial , fading serrations , which are more pronounced near the root , and disappear towards the tip of the tooth - serrations being found in Great Whites but not Extinct Giant Makos . Special mention : megalodon teeth ( edit ) A C. megalodon tooth excavated from Lee Creek Mine , Aurora , North Carolina , United States . C. megalodon teeth are the largest of any shark , extinct or living , and are among the most sought after types of shark teeth in the world . This shark lived during the late Oligocene epoch and Neogene period , about 28 to 1.5 million years ago , and ranged to a maximum length of 60 ft . The smallest teeth are only 1.2 cm ( 0.5 in ) in height , while the largest teeth are in excess of 17.7 cm ( 7.0 in ) . The smaller teeth ranging from 31⁄2 '' and 41⁄2 '' are more common finds , while teeth over 5 '' , 6 '' , and 7 '' are more rare . These teeth are in extremely high demand by collectors and private investors , and they can fetch steep prices according to their size and deterioration . The larger teeth can cost as much as 3,000 dollars . Deposits ( edit ) Shark teeth can not be collected from just any type of rock . Any fossils , including fossil shark teeth , are preserved in sedimentary rocks after falling from their mouth . The sediment that the teeth were found in is used to help determine the age of the shark tooth due to the fossilization process . Shark teeth are most commonly found between the Upper Cretaceous and Tertiary periods . Only after about 10,000 years will a shark tooth fossilize . The teeth commonly found are not white because they are covered with sediment from fossilization . The sediment prevents oxygen and bacteria from attacking and decaying the tooth . Fossilized shark teeth can often be found in or near river bed banks , sand pits , and beaches . These teeth are typically worn , because they were frequently moved and redeposited in different areas repeatedly before settling down . Other locations , however , yield perfect teeth that were hardly moved during the ages . These teeth are typically fragile , and great care should be taken while excavating them . Phosphate pits , containing mostly fossil bones and teeth , or kaolin pits , are ideal places to look for fossil shark teeth . One of the most notable phosphate mines is in Central Florida , Polk County , and is known as Bone Valley . Most of the teeth found here range from 3 to 10 million years old . Near New Caledonia , up until the practice was banned , fishermen and commercial vessels used to dredge the sea floor for megalodon teeth . In the state of Georgia , shark teeth are found so often that they decided to make shark teeth the official state fossil in 1976 . Counting ( edit ) Megalodon lower jaw with 4 tooth rows and 4 tooth series labeled . `` Series 1 '' contains the functional teeth at the front of the jaw . In taxonomy , shark teeth are counted as follows : rows of teeth are counted along the line of the jaw , while series of teeth are counted from the front of the jaw inward . A single tooth row includes one or more functional teeth at the front of the jaw , and multiple replacement teeth behind this . For example , the jaws of a bull shark can have 50 rows of teeth in 7 series , with the outermost series functional , but most sharks have five series with the average shark having about 15 rows of teeth in each jaw . The small teeth at the symphysis , where the two halves of the jaw meet , are usually counted separately from the main teeth on either side . Sharks are also known to lose at least one tooth per week . Due to their specific arrangement of rows and series however , lost teeth can be replaced within a day . Shark teeth research and identification ( edit ) Identification of most sharks are found through a combination of tooth counts and tooth shapes . Teeth can even lead to the identification of shark species like the requiem shark . The fossilized records of teeth helps illustrate evolutionary history , and isolated teeth are used to study and analyze specific linear measurements of the species . In order to identify teeth and specific information about the teeth , research can be done on a shark tooth . This research may uncover many different aspects about the tooth itself , and the shark species . This proves complicated , however , due to the fact that most fossilized teeth are found mixed and scattered . To collect information on basic - life history and get dispersal estimates of a shark tooth , molecular - based technology is very efficient . To further shark population studies , collection of mtDNA can be extracted from shark jaws and teeth . To study the caries - reducing effect in sharks , studies are done on the fluorine atoms that are bound covalently to calcium atoms in the teeth . Each tooth has a complex fluorapatite structure enameloid . In order to reduce effects of deterioration in the teeth , it is useful to sample only the surface of the enameloid of the tooth for this specific research . Studying and researching shark teeth betters our understandings of shark feeding behaviors , evolutionary changes , and mechanisms . This helps us to identify the teeth , and even the species . History of discovery ( edit ) Scapanorhynchus texanus , Menuha Formation ( Upper Cretaceous ) , southern Palestine . The oldest known records of fossilized shark teeth are by Pliny the Elder , who believed that these triangular objects fell from the sky during lunar eclipses . According to Renaissance accounts , large , triangular fossil teeth often found embedded in rocky formations were believed to be petrified tongues of dragons and snakes and so were referred to as `` tongue stones '' or `` glossopetrae '' . Glossopetrae were commonly thought to be a remedy or cure for various poisons and toxins ; they were used in the treatment of snake bites . Due to this ingrained belief , many noblemen and royalty wore these `` tongue stones '' as pendants or kept them in their pockets as good - luck charms . This interpretation was corrected in 1611 by the Italian naturalist Fabio Colonna , who recognized them as ancient shark teeth , and , in 1667 , by the Danish naturalist Nicolaus Steno , who discussed their composition and famously produced a depiction of a shark 's head bearing such teeth . He mentioned his findings in a book , The Head of a Shark Dissected , which also contained an illustration of a C. megalodon tooth , previously considered to be a tongue stone . Tool use by humans ( edit ) Gilbertese weapons edged with shark teeth . In Oceania and America , shark teeth were commonly used for tools , especially on weapons such as clubs and daggers , but also as blades to carve wood and as tools for food preparation . For example , various weapons edged with shark teeth were used by the Native Hawaiians ( see example here ) , who called them leiomano . Some types were reserved for royalty . The Guaitaca ( Weittaka ) of coastal Brazil tipped their arrows with shark teeth . The remains of shark tooth - edged weapons , as well as chert replicas of shark teeth , have been found in the Cahokia mounds of the upper Mississippi River valley , more than 1,000 km ( 620 mi ) from the ocean . It is reported that the rongorongo tablets of Easter Island were first shaped and then inscribed using a hafted shark tooth . See also ( edit ) Elasmobranch Fish jaw List of sharks References ( edit ) Jump up ^ `` Fossil folklore '' . Jump up ^ `` Shark teeth '' . Jump up ^ `` Shark Savers : : Shark Teeth '' . ^ Jump up to : `` What Do Sharks Eat -- The Shark Diet '' . Types of Sharks . ^ Jump up to : The Zen Cart ® Team ; et al . `` About Fossil Shark Teeth '' . Jump up ^ `` 6 plus inch Megalodon Sharks Teeth '' . ^ Jump up to : `` FLMNH Ichthyology Department : Fossil Sharks '' . ^ Jump up to : Hennemann RM . Sharks & Rays : El i love shark teethasmobranch Guide of the World . IKAN - Unterwasserarchiv , Frankfurt , Germany 2001 : 266 - 269 . ^ Jump up to : `` Sink your teeth into this : 20 facts about shark teeth '' . Beach Chair Scientist . Jump up ^ `` Georgia State Fossil - Shark Tooth '' . Jump up ^ Case , Gerard ( 1967 ) . `` Fossil Shark and Fish Remains of North American '' . p. 2 . Jump up ^ Heemstra , P.C. ; Heemstra , E. ( 2004 ) . Coastal fishes of Southern Africa . NISC / SAIAB . p. 47 . ISBN 1 - 920033 - 01 - 7 . Jump up ^ Naylor , G.J.P. ; Marcus , L.F. ( 1994 ) . `` Identifying isolated shark teeth of the genus carcharhinus to species ; relevance for tracking phyletic change through the fossil record '' . American Museum Novitates. 3109 : 53 . Jump up ^ Ahonen , H. ; Stow , A.J. ( 2008 ) . `` Shark jaws and teeth : An unexploited resource for population genetic studies '' . Journal of Fish Biology . 73 ( 2 ) : 450 -- 455 . doi : 10.1111 / j. 1095 - 8649.2008. 01896. x . Jump up ^ Chen , C. ; Wang , Z. ; Saito , M. ; Tohei , T. ; Takano , Y. ; Ikuhara , Y. ( 2014 ) . `` Fluorine in shark teeth : Its direct atomic - resolution imaging and strengthening function '' . Angewandte Chemie International Edition in English . 126 ( 6 ) : 1569 -- 1573 . doi : 10.1002 / ange. 201307689 . Jump up ^ Becker , M.A. ; Seidemann , D.E. ; Chamberlain , J.A. ; Buhl , D. ; Slattery , W. ( 2008 ) . `` Strontium isotopic signatures in the enameloid and dentine of upper cretaceous shark teeth from western alabama : Paleoecologic and geochronologic implications '' . Palaeogeography , Palaeoclimatology , Palaeoecology. 264 ( 1 -- 2 ) : 188 -- 194 . doi : 10.1016 / j. palaeo. 2008.04. 006 . Jump up ^ Whitenack , L.B. ( 2008 ) . The biomechanics and evolution of shark teeth . ( Order No. 3376233 , University of South Florida ) . http://search.proquest.com/docview/304460308 Jump up ^ `` Sharks ' teeth are falling ! - Dharma Beach Bum '' . Dharma Beach Bum . Jump up ^ Haven , Kendall ( 1997 ) . 100 Greatest Science Discoveries of All Time . Libraries Unlimited . pp. 25 -- 26 . ISBN 1 - 59158 - 265 - 2 . Jump up ^ Bruner , John ( 1997 ) . `` The Megatooth shark '' . FLMNH . Archived from the original on 2007 - 12 - 28 . Retrieved 2008 - 01 - 16 . Jump up ^ `` Treasures of Hawai'i : Shark Tooth Weapon '' . Bishopmuseum.org . Archived from the original on 2008 - 12 - 04 . Retrieved 2008 - 11 - 27 . Jump up ^ Taylor , Leighton R. ( 1993 ) . Sharks of Hawaii : Their Biology and Cultural Significance . University of Hawaii Press . p. 28 . ISBN 978 - 0 - 8248 - 1562 - 2 . Jump up ^ Anthony Meyer ( 1995 ) Oceanic Art , v. 2 , p. 579 . Jump up ^ Métraux , Alfred ( 1946 ) Handbook of South American Indians , v. 1 , p. 522 , `` The Guaitaca '' Jump up ^ Greg Perino , c. 1950 , Cahokia Brought to Life , pp. 66 - 67 Jump up ^ Métraux , Alfred ( 1940 ) , `` Ethnology of Easter Island '' . Bernice P. Bishop Museum Bulletin ( Honolulu : Bernice P. Bishop Museum Press ) 160 : 404 Campbell , Sid ( 2006 ) . `` Shark - Tooth Weapons '' . Warrior Arts and Weapons of Ancient Hawaii . Berkeley , Calif : Blue Snake Books . ISBN 1 - 58394 - 160 - 6 . OCLC 65400291 . Castro , Jose ( 1983 ) . The Sharks of North American Waters . College Station : Texas A&M University Press . ISBN 0 - 89096 - 143 - 3 . Hennemann RM . Sharks & Rays : Elasmobranch Guide of the World . IKAN - Unterwasserarchiv , Frankfurt , Germany 2001 : 266 - 269 . Stevens , John D. ( 1987 ) . Sharks . New York : NY Facts on File Publications . ISBN 0 - 8160 - 1800 - 6 . External links ( edit ) A weapon of tiger - shark teeth on carved koa wood , at the Bishop Museum . www.shark-references.com : Database of bibliography of living / fossil sharks and rays ( Chondrichtyes : Selachii ) with more than 15.000 listed papers and a lot of downloadlinks Real Great White Shark Teeth for Sale Online in USA Sharks Topics Outline of sharks Shark anatomy Shark teeth Egg case ( Chondrichthyes ) Threat display Threatened sharks Taxonomy Carcharhiniformes ( Ground sharks ) Heterodontiformes ( Bullhead sharks ) Hexanchiformes Lamniformes ( Mackerel sharks ) Orectolobiformes ( Carpet sharks ) Pristiophoriformes ( Sawsharks ) Squaliformes Squatiniformes ( Angel sharks ) † Cladoselachiformes † Hybodontiformes † Symmoriida † Xenacanthida ( Xenacantiformes ) List of sharks Human interaction Shark attack Shark attack prevention Shark net Shark proof cage Shark tourism Drum lines Category Portal WikiProject Fish About fish Diversity Ethnoichthyology Evolution Diseases and parasites Fisheries Fishing Fish as food Fear of fish FishBase Fish kill Hypoxia in fish Ichthyology Anatomy and physiology Fish anatomy Fish physiology Estimating age Anguilliformity Bone dermal intramembranous ossification Cleithrum Chromatophore Fins dorsal fin Gill branchial arch gill raker gill slit pharyngeal arch pharyngeal slit pseudobranch Glossohyal Jaw hyomandibula pharyngeal jaw Leydig 's organ Mauthner cell Meristics Operculum papillare Papilla Photophore Root effect Shark cartilage Scales ganoine Spiral valve Suckermouth Swim bladder physoclisti physostome Teeth pharyngeal teeth shark teeth Teleost leptins Digital Library Sensory systems Sensory systems in fish Ampullae of Lorenzini Barbel Hydrodynamic reception Electrocommunication Electroreception Jamming avoidance response Lateral line Otolith Passive electrolocation Capacity for pain Schreckstoff Surface wave detection Vision Weberian apparatus Reproduction Fish reproduction Bubble nest Clasper Egg case Fish development Ichthyoplankton Juvenile fish Life history theory Milt Mouthbrooder Polyandry in fish Pregnancy Roe Sequential hermaphroditism Spawning triggers Locomotion Fish locomotion Fin and flipper locomotion Amphibious fish Walking fish Flying fish Undulatory locomotion Tradeoffs for locomotion in air and water RoboTuna Other behaviour Aquatic predation Aquatic respiration Bait ball Bottom feeders Cleaner fish Corallivory Diel vertical migration Electric fish Filter feeders Forage fish Migrating fish Paedophagy Predatory fish Salmon run Sardine run Scale eaters Schooling fish Sleep in fish Venomous fish Fish intelligence By habitat Cave Coastal Coldwater Coral reef Deep sea Demersal Euryhaline Freshwater Groundfish Pelagic Tropical Other types Bait Coarse Diversity Game Genetically modified Hallucinogenic Oily Poisonous Rough Whitefish Commercial Fish farming Carp Salmonids Tilapia Wild fisheries Predatory fish billfish mackerel salmon tuna Forage fish anchovy herring sardine sprats Demersal fish cod flatfish pollock Major groups Jawless fish hagfish lampreys Cartilaginous fish chimaeras sharks rays Bony fish spiny - finned fleshy - finned Lists Aquarium life Blind fish Fish common names Fish families Fish on stamps Glossary of ichthyology Large fish Threatened rays sharks Prehistoric fish more lists ... Category Portal WikiProject Retrieved from `` https://en.wikipedia.org/w/index.php?title=Shark_tooth&oldid=835754920 '' Categories : Sharks Fish anatomy Symbols of Georgia ( U.S. state ) Teeth Talk Contents About Wikipedia Deutsch Français Italiano Nederlands Edit links This page was last edited on 10 April 2018 , at 15 : 31 . Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply . By using this site , you agree to the Terms of Use and Privacy Policy . Wikipedia ® is a registered trademark of the Wikimedia Foundation , Inc. , a non-profit organization . About Wikipedia

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Staci Keanan - wikipedia Staci Keanan Jump to : navigation , search Staci Keanan Anastasia Love Sagorsky ( 1975 - 06 - 06 ) June 6 , 1975 ( age 42 ) Devon , Pennsylvania , US Other names Stacy Keanan Staci Love Alma mater UCLA Southwestern Law School Occupation Actress ( 1987 -- 2012 ) Attorney ( 2013 -- present ) Years active 1987 -- Spouse ( s ) Guy Birtwhistle ( m . 2017 ) Staci Keanan ( born Anastasia Love Sagorsky on June 6 , 1975 ) is a former American actress and attorney . Keanan is best known for her roles in the television series My Two Dads ( 1987 -- 1990 ) and Step by Step ( 1991 -- 1998 ) . She has also been credited as Stacy Keenan and Staci Love . Contents ( hide ) 1 Early life 2 Career 2.1 Acting 2.2 Law 3 Personal life 4 Filmography 5 Theatre 6 Awards 7 References 8 External links Early life ( edit ) Keanan was born in Devon , Pennsylvania ( near Philadelphia ) , the daughter of Jacqueline ( née Love ) and Irv Sagorsky , a car salesman . She has a sister , Pilar . Career ( edit ) Acting ( edit ) At age five , she began modeling and appeared in print , radio , and television advertisements , including the voice of My Little Pony and television commercials for Burger King and Hershey 's Kisses . As a youth , Keanan moved with her mother and sister to New York City , where she changed her name to `` Staci Love '' and began appearing in summer stock . She made her credited television debut in the 1987 miniseries I 'll Take Manhattan . At the age of 12 , shortly after she moved with her family to Los Angeles , California , she was cast as Nicole Bradford in the TV series My Two Dads . The series ran from 1987 to 1990 . During the 1990 - 91 season , she co-starred in the short - lived series Going Places with Alan Ruck , Heather Locklear , and Hallie Todd . The following year , Keanan was cast as Dana Foster in the TV series Step by Step which aired from 1991 to 1998 . By 1997 Keanan had changed her name from Staci to Stacy . Keanan had roles in the short Stolen Poem ( 2004 ) and the films Hidden Secrets ( 2006 ) , and Death and Cremation ( 2010 ) with Brad Dourif , Jeremy Sumpter , and Daniel Baldwin . In 2009 Keanan appeared in Holyman Undercover , starring David A.R. White , and in 2010 she appeared in a cameo in You Again with Step By Step castmates Christine Lakin and Patrick Duffy . She also co-starred in the film Sarah 's Choice . Law ( edit ) Keanan received her ungraduate degree from UCLA . She then attended Southwestern Law School and was admitted to the State Bar of California in 2013 . She currently practices law under her given name , Anastasia Sagorsky , in the Los Angeles area . Personal life ( edit ) On February 11 , 2017 , Keanan married actor / producer Guy Birtwhistle . Filmography ( edit ) Film roles Year Title Role Notes 1990 Lisa Lisa Alternative title : Candlelight Killer Skooled Short film 1995 Ski Hard Annie Meyers Alternative titles : Downhill Willie , Ski Nuts 1995 The Red Coat Mary Short film 1997 Nowhere Ever Credited as Stacy Keanan Stolen Poem Jamie Short film 2006 Hidden Secrets Rachel Wilson Credited as Stacy Keanan 2009 Sarah 's Choice Denise Credited as Stacy Keanan Holyman Undercover Carmen You Again Dana Credited as Stacy Keanan Death and Cremation Becky Weaver Television roles Year Title Role Notes 1985 How To Be A Man N / A Television special ; uncredited 1985 Many Happy Returns Uncredited Television short produced for PBS ; uncredited I 'll Take Manhattan Angelica Cipriani Television miniseries ; credited as Staci Love 1987 -- 1990 My Two Dads Nicole Bradford Lead role ; 60 episodes 1990 Casey 's Gift : For Love of a Child Kathy Stilwell Television movie 1990 -- 1991 Going Places Lindsay Bowen Main role ; 22 episodes 1991 -- 1998 Step by Step Dana Foster Main role ; 159 episodes ; credited as Stacy Keanan for Season 7 Boy Meets World Dana Episode : `` The Happiest Show on Earth '' 1997 Lois & Clark : The New Adventures of Superman Becky Samms Episode : `` I 've Got You Under My Skin '' ; credited as Stacy Keanan 1998 Cybill Lacy Episode : `` Fine Is Not a Feeling '' 1998 Diagnosis : Murder Cindy Garrett Episode : `` Till Death Do Us Part '' Theatre ( edit ) As a child musical theatre performer : Miss Lulu Bett , Berkshire Theater Festival , Stockbridge , Massachusetts Annie , Theatre at Stagedoor Manor , Loch Sheldrake , New York Georgia Avenue , Goodspeed Opera House , East Haddam , Connecticut The King and I , Norma Terris Theatre , Chester , Connecticut Gypsy , Norma Terris Theatre , Chester , Connecticut As an adult stage performer : Old Glories , two one - act plays by Elliot Shoenman , directed by Mark L. Taylor , Zephyr Theatre , Hollywood , California Above the Fold ( Diane ) , Zephyr Theatre , Hollywood , California Red Flags ( Janet ) , Zephyr Theatre , Hollywood , California Moment in the Sun ( Diane Bellini ) , by Elliot Shoenman , Matrix Theatre , Hollywood , California Last Call at Moby Dick 's ( Caroline ) , by Ed Marill , directed by Mark L. Taylor , McCadden Place Theatre , Hollywood , California Sunset Park ( Young Evelyn ) second run , by Marley Sims and Elliot Shoenman , directed by Mark L. Taylor , Zephyr Theatre , Hollywood , California Awards ( edit ) Year Award Work Result Refs Young Artist Award Best Young Actress Starring in a New Television Comedy Series My Two Dads Won References ( edit ) ^ Jump up to : `` Staci Keanan Biography ( 1975 - ) '' . Filmreference.com . Retrieved 2009 - 03 - 07 . ^ Jump up to : `` The State Bar of California : Attorney Search '' . calbar.ca.gov . The State Bar of California . Retrieved January 1 , 2018 . Jump up ^ Kim , Jae - Ha . `` Actress likes having ' 2 Dads ' '' , Chicago Sun - Times , November 17 , 1989 . ^ Jump up to : Obituary for Jacqueline Love Sagorsky , Philadelphia Inquirer , July 30 , 2009 . Jump up ^ Blessing , Angela ; Holmstrom , Rick ( November 23 , 1987 ) . `` For Staci Keanan of TV 's My Two Dads , Hollywood Can Be a Two - Faced Town '' . People . Retrieved 2016 - 09 - 03 . Jump up ^ Podcast : ' Keanan , Stacy . Interview with Brian Castro . ' from ( 4 : 24 `` ) , IMDB listing misspelled . WTF ? the Podcast . FX Show , Orlando . January 2008 . Retrieved on 2010 - 10 - 24 . Jump up ^ `` ' My Two Dads ' Star Staci Keanan : Where Is She Now ? '' . Extra . Extra ( TV program ) . Retrieved November 13 , 2017 . Jump up ^ Film clip : ' FILM `` NOWHERE '' CAST ( 1997 ) ' onscreen credits ( 1.43 `` - 1.47 '' ) as `` Stacy Keanan '' . Jump up ^ Nowhere ( 1997 ) Cast and Crew at FLF.com ( circa 1997 via Wayback Machine . ) Retrieved 2010 - 11 - 26 . Jump up ^ Sarah 's Choice DVD cover DVD cover image Wikipedia.org . Retrieved 2010 - 10 - 24 . Jump up ^ You Again production credits New York Times Retrieved 2010 - 10 - 22 . Archived November 3 , 2012 , at the Wayback Machine . External links ( edit ) Staci Keanan on IMDb Retrieved from `` https://en.wikipedia.org/w/index.php?title=Staci_Keanan&oldid=818059167 '' Categories : 1975 births 20th - century American actresses 21st - century American actresses 21st - century American lawyers Actresses from Pennsylvania American child actresses American child models American film actresses American musical theatre actresses American stage actresses American television actresses American women lawyers California lawyers Female models from Pennsylvania Living people People from Chester County , Pennsylvania Southwestern Law School alumni University of California , Los Angeles alumni Hidden categories : All articles with dead external links Articles with dead external links from December 2017 Articles with permanently dead external links Webarchive template wayback links Use mdy dates from January 2018 Articles with hCards All articles with unsourced statements Articles with unsourced statements from September 2016 Talk Contents About Wikipedia Български Čeština Deutsch Español فارسی Français Nederlands Norsk Português Edit links This page was last edited on 1 January 2018 , at 07 : 47 . Text is available under the Creative Commons Attribution - ShareAlike License ; additional terms may apply . By using this site , you agree to the Terms of Use and Privacy Policy . Wikipedia ® is a registered trademark of the Wikimedia Foundation , Inc. , a non-profit organization . About Wikipedia

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