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Topic: Parthenogenetic

In the News (Tue 2 Dec 08)

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	Melissa Kramer
		Life-history analysis of the relative costs and benefits of parthenogenetic versus sexual reproduction revealed that the transition from sexual to parthenogenetic reproduction is associated with increased mortality, decreased egg viability, and a change in the apportionment of eggs across the life span.
		There are also important differences among parthenogenetic strains in the extent and the way these factors are affected, although when all changes are considered together in the context of population-level parameters, differences between sexual and parthenogenetic strains are greatly reduced, and differences among parthenogenetic strains largely disappear.
		The extremely high abortion rate of parthenogenetic eggs (as high as 95% of eggs that initiate development) is being investigated as a potential developmental constraint on the evolution of parthenogenesis.
	biology4.wustl.edu /templeton/people/melissa (395 words)

	jwz - I, for one, welcome our parthenogenetic hybrid masters
		In 1995, for instance, Bonthron described another boy who was partially parthenogenetic: cells from his blood and certain other tissues contained none of his father's chromosomes; instead, they featured a duplicated set of one half of his mother's.
		Although it is not unknown for an egg to start developing without being fertilized, fully parthenogenetic human embryos cannot develop to term.
		Bonthron believes that the partially parthenogenetic boy owed his unusual genetic constitution to an egg that spontaneously divided into two cells, one of which was fertilized.
	www.livejournal.com /users/jwz/260749.html (352 words)

	Blackwell Synergy - Heredity, Vol 81, Issue 1, pp. 38-47: Allozyme variability in sexual and parthenogenetic freshwater ...
		Purely parthenogenetic populations are found north of the Alps, whereas sexuals seem to have the centre of their distribution south of the Alps, in middle and northern Italy (Beukeboom et al., 1996).
		When geographically isolated parthenogenetic populations are genetically more closely related to coexisting sexuals than to each other, independent endemic origins of parthenogenetic clones is the most parsimonious explanation (Quattro et al., 1991, 1992) and, thus, genotypes of parthenogenetic clones should consist of alleles that are segregating in the sexual population (Dybdahl and Lively, 1995).
		Ecological implications of clonal diversity in parthenogenetic morphospecies.
	www.ice.mpg.de /clib/fulltext/pube/mio/MIO107.htm (3539 words)

	Parthenogenesis - Wikipedia, the free encyclopedia
		The mechanism by which the mixing of chromosomes from two or three species can lead to parthenogenetic reproduction is unknown.
		Because multiple hybridization events can occur, individual parthenogenetic whiptail species can consist of multiple, independent asexual lineages.
		Within lineages, there is very little genetic diversity, but different lineages may have quite different genotypes.
	en.wikipedia.org /wiki/Parthenogenetic (1173 words)

	ParthCategories.html (Site not responding. Last check: 2007-09-19)
		Differentiation of this parthenogenetic expression, from a post-fertilization incubation failure is difficult and may not be conclusive.The following five images identified as Ruptured Membranes illustrate this category of parthenogenetic expression that was observed between 7 and 21 days of incubation.
		Typically, parthenogenetic embryos die in ovo but those that are able to sustain a modem of normal development require an additional 2 to 3 days to hatch.
		Attempts to discriminate between parthenogenetic development and early embryonic failures prior to the formation of blood cells may result in mis-classifications.
	oregonstate.edu /dept/animal-sciences/poultry/ParthCateg.html (510 words)

	Sloan-Kettering - Projects: Therapeutic Cloning and Parthenogenetic Stem Cells
		Monkey parthenogenetic stem cells were differentiated into dividing neural precursor cells (A, B).
		Parthenogenetic stem cells could serve as an alternative source for autologous cell therapy.
		Parthenogenetic stem cells are also an interesting tool to elucidate the role of imprinting during development, as these cells lack paternal imprinting.
	www.mskcc.org /mskcc/html/12041.cfm (277 words)

	Ludmila A. Kutikova. Variability in obligatory parthenogenetic rotifers (Rotifera, Bdelloida).
		Variability and speciation in parthenogenetic organisms is a topical issue of general biological importance.
		Examples of variability are known in parthenogenetic insects (Suomalainen, 1961), lizards of the genus Chemidophorus (Parker and Selander, 1976), and in angiosperms (Kashin, 1998).
		Therefore it can be assumed that obligatory parthenogenetic bdelloid rotifers invaded terrestrial biotopes on the early stage of their evolution; they are characterized by slow evolution rates as compared to heterogonetic monogononts; the variability of bdelloids is of principally of different character and concerns morphological structures of a lower taxonomic rank.
	www.zin.ru /annrep/2000/13.html (1399 words)

	HETEROGONY
		Heterogony is a form of life cycle in which parthenogenetic and sexual reproduction alternate.
		As species of very diverse taxonomic groups have evolved the same type, it seems only reasonable to look for environmental clues which are analogous to the different forms exhibiting heterogony and which could therefore stand as an evolutive factor enfavouring heterogony to take place.
		Common to the first two groups of the cladocera and the rotatoria is that the parthenogenetic exploration and the sexual refinement and remixing of genes to start a new cycle.
	www.cladocera.de /heterogony/heterogony.html (1107 words)

	ARS \| Publication request: Isolation and Characterization of a Bovine Trophectoderm Cell Line derived from a ... (Site not responding. Last check: 2007-09-19)
		Parthenogenetic fetuses always have poor formation of the placenta and always abort.
		This may help in the efforts to improve the efficiency of animal cloning which is important because, via cloning, it may be possible to rapidly improve various traits of cattle.
		To initiate the cell line, 8-day parthenogenetic blastocysts were attached to a feeder layer of STO fibroblasts and primary outgrowths occurred that consisted of trophectoderm, endoderm, and very occasionally epiblast tissue.
	ars.usda.gov /research/publications/publications.htm?SEQ_NO_115=159192 (611 words)

	ParthIndex.html (Site not responding. Last check: 2007-09-19)
		Macroscopic differentiation between parthenogenetic and normal embryos can be achieved after 4 days of artificial incubation, but due to the variability in parthenogenetic expression, accuracy of detection is improved after 6 days of incubation.
		The phenomena of avian parthenogenesis is described as a process of cell division in an unfertilized egg that may result in the formation of embryonic tissues and in extreme situations a fully developed individual (Olsen,1975).
		The parthenogenetic tissues that develop in infertile eggs is diploid (Yao and Olsen, 1955; Sato and Kosin, 1960) which makes differentiation between normal and parthenogenetic embryos a difficult task.
	oregonstate.edu /Dept/animal-sciences/poultry (593 words)

	BioMed Central \| Full text \| Phylogeography of competing sexual and parthenogenetic forms of a freshwater flatworm: ...
		It is a simultaneous hermaphrodite with sexual and parthenogenetic biotypes and has been used for various studies on the costs and benefits of sex [21-24].
		Differences between parthenogenetic strains in the degree of divergence would then be a relative measure of the age of such lineages, and allow to distinguish relatively "young" from relatively "old" lineages.
		Inferring the age of a parthenogenetic lineage from genetic data is based on nucleotide divergence with its closest sexual relative (the hypothetical ancestor).
	www.biomedcentral.com /1471-2148/3/23 (5287 words)

	Sergey D. Grebelnyi. The mechanisms of unisexual reproduction and pure either maternal or paternal inheritance.
		In natural populations the parthenogenesis is always connected with deep disintegration of meiosis that leads to a complete stoppage of genetic recombination, so that the maternal characters are inherited by the offspring without any c the population an opportunity not to spend 50% of environmental resources hanges.
		When discussing the origination of parthenogenetic forms and inevitable competitive interactions of them with their closest bisexual relatives, one quite often pays attention to the 'double advantage' of parthenogenesis (Maynard Smith, 1971, 1978) that gives on males.
		According to another, may be more reasoned point of view, the advantages of parthenogenetic populations could be caused by their higher heterozygosity and uniformity much more than by higher rate of breeding without males (Suomalainen, 1969; Suomalainen et al., 1973, 1976; Grant, 1977; and many others).
	www.zin.ru /annrep/2000/11.html (2393 words)

	Maternal Primary Imprinting Is Established at a Specific Time for Each Gene throughout Oocyte Growth -- Obata and Kono ...
		The establishment of maternal primary imprinting was shown by the repression of paternally expressed genes and biallelic expression of maternally expressed genes in the constructed parthenogenetic embryos.
		Developmental ability of the parthenogenetic embryos constructed with one genome from a non-growing or growth-stage oocyte and one from an fg oocyte at (a) 12.5 dpc and (b) 9.5 dpc.
		The development of constructed parthenogenetic embryos was notably reduced with the oocyte growth compared with 1d-ng/fg PE (, p < 0.05; *, p < 0.001).
	www.jbc.org /cgi/content/full/277/7/5285 (3745 words)

	Heterogamy -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-09-19)
		Heterogamy is the alternation of differently organized generations, applied to the alternation between (Click link for more info and facts about parthenogenetic) parthenogenetic and a (Click link for more info and facts about sexual) sexual generation.
		Heterogamy is a synomym of anisogamy, the condition of having differently sized male and female (A mature sexual reproductive cell having a single set of unpaired chromosomes) gametes.
		A plant is heterogamous when (The male reproductive organ of a flower) stamens and (The female ovule-bearing part of a flower composed of ovary and style and stigma) pistils are not regularly present in each flower or floret.
	www.absoluteastronomy.com /encyclopedia/h/he/heterogamy.htm (102 words)

	D:\ASAWEB~1\PSCF\1983\JASA9-83Kessel.htm (Site not responding. Last check: 2007-09-19)
		ree-living flatworms of the genus Bothrioplana are parthenogenetic.
		As for the parthenogenetic species, even if I had a complete listing of them, it could not be published here as the number would run into hundreds of thousands.
		According to our biological interpretation of the Virgin Birth, Jesus' conception was parthenogenetic, and because human beings have the same X-Y kind of sex determination found in other mammals, with the female homozygous and possessing two X chromosomes, Jesus was conceived as a chromosomal female.
	www.asa3.org /ASA/PSCF/1983/JASA9-83Kessel.html (5510 words)

	Disruption of Imprinted Expression of U2afbp-rs/U2af1-rs1 Gene in Mouse Parthenogenetic Fetuses -- Sotomaru et al. 276 ...
		In parthenogenetic fetuses, which contained diploid genomes from both B6CBF1 and JF1 mice, gene expression was detected from both alleles.
		In contrast to the control fetuses, the sequences in both regions in the parthenogenetic fetuses were not digested by HpaII or HhaI and showed the status of hypermethylation regardless of the gene expression.
		expression of the U2afbp-rs gene in the parthenogenetic fetus
	www.jbc.org /cgi/content/full/276/28/26694 (3365 words)

	[No title]
		Biology of Artemia urmiana and some other populations of Artemia from Iran: During this study life cycle and reproductive characteristics of 6 Iranian populations of Artemia were studied at laboratory condition.
		It was found that except Artemia urmiana rest of the Artemia populations are parthenogenetic.
		Field observations indicate that all Artemia populations from Iran except the bisexual Artemia urmiana are parthenogenetic.
	www.aquaculture.ugent.be /rend/INCO/1annualrep/UU.doc (1073 words)

	ASCO - Abstracts - PubMed Abstract View (Site not responding. Last check: 2007-09-19)
		In vivo developed and in vitro produced embryos displayed allocation of nucleolar proteins to fibrillar and granular compartments of the developing nucleoli during the 4th cell cycle.
		The parthenogenetic embryos typically displayed formation of fibrillo- granular nucleoli during the 5th cell cycle and autoradiographic labeling was not observed until the morula stage.
		On the other hand, parthenogenetic embryos displayed allocation of nucleoar proteins to nuclear entities during the 4th cell cycle.
	www.asco.org /ac/1,1003,_12-002867-00_18-0012658636,00.asp?SearchNames= (463 words)

	Genetic dissection of susceptibility to murine ovarian teratomas that originate from parthenogenetic oocytes. (Site not responding. Last check: 2007-09-19)
		Genetic dissection of susceptibility to murine ovarian teratomas that originate from parthenogenetic oocytes.The LT/Sv mouse strain is characterized by its abnormally high incidence of spontaneous ovarian teratomas.
		These tumors have been shown to originate from parthenogenetic oocytes, which are spontaneously induced to divide.
		A locus on chromosome 6 designated Ots1 (ovarian teratoma susceptibility) was identified as the single major locus that increases the frequency of teratomas in a semidominant manner.
	www.pdg.cnb.uam.es /UniPub/iHOP/gp/887647.html (121 words)

	[No title]
		Populations designated "parthenogenetic" in this work were those which were either verified to reproduce asexually in cultures or of having genotypes assignable to parthenogenetic forms observable in enzyme electrophoresis assays (Abreu-Grobois, 1983).
		The much broader geographic range of parthenogenetic populations in the Old World observed in the material studied probably reflects a greater capacity for colonizing newly opened environments that asexual Artemiaforms have, compared to their sexual relatives, at least, in that region of the world.
		Furthermore, being able to distinguish the range of the parthenogenetic forms by ploidy levels permits a similar obervation regarding the diploid asexualArtemiawhich are much more widely dispersed than their polyploid conterparts, suggesting that polyploidy per sedoes not confer this organism any additional capacity for colonizatíon and population spread.
	biblioweb.dgsca.unam.mx /cienciasdelmar/instituto/1989-2/articulo342.html (2601 words)

	Michael Heethoff (Site not responding. Last check: 2007-09-19)
		Therefore, parthenogenetic lineages are thought to be short-lived and doomed to extinction.
		But there is a third and little studied group of animals, the oribatid mites, which contain multiple speciose parthenogenetic and ancient taxa.
		Tritonymph of Archegozetes longisetosus, a parthenogenetic oribatid mite
	www.uni-tuebingen.de /agbetz/heethoff/research.html (283 words)

	Homoptera
		Aphids are characterized by having a complex system of alternating generations including wingless, winged, parthenogenetic and sexual forms in a single life cycle (Slide).
		The typical aphid overwinters as an egg on the primary host; wingless, parthenogenetic females hatch in the spring and in a short time produce a similar generation (Slide).
		Several wingless parthenogenetic generations may follow, until a winged parthenogenetic generation gives rise to the sexual forms that produce the overwintering eggs.
	classes.entom.wsu.edu /348/Homoptera.htm (837 words)

	New Scientist Breaking News - Zapped human eggs divide without sperm
		These blastocysts should in theory yield stem cells, but because they are parthenogenetic — produced from the egg only — they cannot be viewed as a potential human life, says Karl Swann of the University of Wales College of Medicine in Cardiff, UK.
		Swann and his team used a standard chemical treatment to prevent this, so both sets in the parthenogenetic embryos come from the mother.
		Swann hopes to be the first to harvest embryonic stem cells from human parthenogenetic blastocysts, but other scientists are trying different approaches.
	www.newscientist.com /article.ns?id=dn6733 (589 words)

	Virgin birth method could found stem cells
		A lot of work still has to be done to ensure any tissues made from parthenogenetic stem cells are absolutely normal, says Jerry Hall of the Institute for Reproductive Medicine and Genetics in Los Angeles.
		Since eggs are needed to make parthenogenetic stem cells, one potential problem is that the technique could not be used to make matching stem cells for men or for women after menopause.
		However, because cells made by parthenogenesis have two identical sets of chromosomes, rather than one set each from the father and the mother, they have less variation in the surface proteins on cells that can trigger immune reactions.
	www.eurekalert.org /pub_releases/2003-04/ns-vbm042303.php (676 words)

	IngentaConnect Mouse Parthenogenetic Embryos with Monoallelic H19 Expression Can... (Site not responding. Last check: 2007-09-19)
		Parthenogenetic mouse embryos that contain genomes from nongrowing (ng) and fully grown (fg) oocytes can develop into 13.5-day-old fetuses, in which paternally and maternally expressed imprinted genes are expressed and repressed, respectively, from the ng oocyte allele.
		parthenogenetic embryos carrying the ng-oocyte genome that had been deleted by the H19 transcription unit successfully developed as live fetuses for 17.5 gestation days.
		parthenogenetic fetuses expressed Igf2 and H19 genes at <2 and 82% of the levels in the controls.
	api.ingentaconnect.com /content/ap/db/2002/00000243/00000002/art00561 (353 words)

	TechRef-238 - EFFECTS OF MITOCHONDRIAL UNCOUPLING ON ADIPOCYTE INTRACELLULAR CA2+ AND LIPID METABOLISM.
		We employed a haploid model in the mouse to study the effects of aneuploidy on apoptosis in preimplantation embryos.
		Mouse metaphase II oocytes that were activated with strontium formed haploid parthenogenetic embryos with 1 pronucleus, whereas activation of oocytes with strontium plus cytochalasin D produced diploid parthenogenetic embryo controls with 2 pronuclei.
		Rates of development and apoptosis were compared between haploid and diploid parthenogenetic embryos (parthenotes) and control embryos derived from in vitro fertilization (IVF).
	www.glass-bottom-dishes.com /technical/technical-264.html (279 words)

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