Parthenogenesis Research Papers - Academia.edu (original) (raw)

Obtaining karyotypes from human spermatozoa after microinjection into Syrian golden hamster oocytes is difficult and the hitherto reported results are unsatisfactory. This may be related to the injection and culture technique or to the... more

Obtaining karyotypes from human spermatozoa after microinjection into Syrian golden hamster oocytes is difficult and the hitherto reported results are unsatisfactory. This may be related to the injection and culture technique or to the high susceptibility of the hamster oocytes to undergo parthenogenetic activation or both. Therefore, we investigated the hamster oocyte-human sperm microinjection model using the following two approaches: (i) application of contemporary techniques for injection (touching the sperm tail) and culture (hamster embryo culture medium, HECM-3, 10% CO 2 ) and (ii) omission of Ca 2⍣ from the injection medium. Thus, in the first series of experiments, 252 hamster oocytes were injected with human spermatozoa. Among the 219 (87%) oocytes that survived the injection procedure, the mean percentages of male pronucleus formation [two pronuclei (2PN), two polar bodies (PB)], mitotic metaphase entry and sperm chromosome spreads were 41.4, 27.8 and 18.2% respectively. Analysis of the oocytes which failed to develop the male pronucleus following injection revealed that most of them had developed only the hamster female PN while the sperm nuclei were either intact or swollen (partially decondensed), indicating that failure of oocyte activation was not the likely reason for the failure of male PN formation in these oocytes. In the next series of experiments, sibling oocytes were alternately injected with spermatozoa suspended either in the regular (1.9 mM Ca 2⍣ ) or Ca 2⍣ -free injection medium (experiment set 2, n ⍧ 278). A significant improvement was noted in the mean percentages of oocytes with 2PN, 2PB, metaphase entry and sperm chromosome spreads in the Ca 2⍣ -free group versus the regular group (2PN, 2PB: 51 versus 36.6%, metaphase entry: 36.3 versus 26.9% and sperm chromosome spreads: 28 versus 20.4%; all P < 0.04). Thus, parthenogenetic activation appears to be one of the contributing factors for the failure of male PN formation after heterospecific hamster ICSI. From these experiments it can be concluded that application of the advanced injection and culture techniques and omission of Ca 2⍣ from the injection medium are promising for the routine application of the hamster oocyte microinjection for karyotyping of human spermatozoa with poor fertilizing capacity.

The expression of interferon-tau (IFN-t) is essential for bovine embryo survival in the uterus. An evaluation of IFN-t production from somatic cell nuclear transfer (NT)-embryo-derived primary trophectoderm cultures in comparison to... more

The expression of interferon-tau (IFN-t) is essential for bovine embryo survival in the uterus. An evaluation of IFN-t production from somatic cell nuclear transfer (NT)-embryo-derived primary trophectoderm cultures in comparison to trophectoderm cultured from parthenogenote (P) and in vitro matured, fertilized, and cultured (IVP) bovine embryos was performed. In Experiment 1, the success/ failure ratio for primary trophectoderm colony formation was similar for IVP and NT blastocysts [IVP ¼ 155/ 29 (84%); NT 104/25 (81%)], but was decreased (P ¼ .05) for P blastocysts [54/43 (56%)]. Most trophectoderm colonies reached diameters of at least 1 cm within 3-4 weeks, and at this time, 72 hr conditioned cell culture medium was measured for IFN-t concentration by antiviral activity assay. The amount of IFN-t produced by IVP-outgrowths [4311 IU/mL (n ¼ 155)] was greater (P < .05) than that from NT-[626 IU/mL (n ¼ 104)] and P -[1595 IU/ mL (n ¼ 54)] derived trophectoderm. Differential expression of IFN-t was confirmed by immunoblotting. In Experiment 2, colony formation was again similar for IVP and NT blastocysts [IVP ¼ 70/5 (93%); NT 67/ 1 (99%)] and less (P < .05) for P blastocysts [65/ 27 (70%)]. Analysis of trophectoderm colony size after 23 days in culture showed a similar relationship with P-derived colonies being significantly smaller in comparison to IVP and NT colonies. A differential expression of IFN-t was also observed again, but this time as measured over time in culture. Maximal IFN-t production was found at day-14 of primary culture and diminished to a minimum by the 23rd day. Mol.

Patterns of variation in chromosomes, mitochondrial DNA and allozymes were assessed for two parthenogenetic (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual (H. frenatus) species of house gecko that have colonized remote... more

Patterns of variation in chromosomes, mitochondrial DNA and allozymes were assessed for two parthenogenetic (Lepidodactylus lugubris and Hemidactylus garnotii) and one sexual (H. frenatus) species of house gecko that have colonized remote Pacific Ocean islands. The aims were to test the assumed recency of colonization and to provide information on the amount and distribution of genetic variation. Lepidodactylus lugubris was found to have diploid and triploid clones, high heterozygosity and moderate diversity for allozymes, and only two common types of mtDNA. The common clones distinguished by genetic analysis were geographically widespread. Together the genetic data suggest multiple origins of L. lugubris, with multiple recent invasions of the Pacific Ocean islands. Hemidactylus garnotii had low genetic diversity for chromosomes, mtDNA and allozymes. In contrast, its sexual congener, H. frenalus, had unusually high levels of mtDNA diversity, with some widespread variants. The low level of mtDNA diversity in the parthogenetic species provides strong support for the assumption that these are recent colonists of Pacific Islands.

This article describes the first successful induction of meiotic gynogenesis in Wels catfish (Silurus glanis) using heterologous sperm of grass carp (Ctenopharyngodon idella) with DNA inactivated by means of UV-irradiation at 4800 J/m 2.... more

This article describes the first successful induction of meiotic gynogenesis in Wels catfish (Silurus glanis) using heterologous sperm of grass carp (Ctenopharyngodon idella) with DNA inactivated by means of UV-irradiation at 4800 J/m 2. The cold shock at 61C (duration of 20 min) started in the nineth minute after fertilization was found as efficient in retaining the second polar body and producing meiotic diploids. Successful induction of meiotic gynogenesis was confirmed by the microsatellite DNA analysis, which revealed only maternal inheritance in gynogenetic offspring. Ploidy of gynogenetic offspring was verified by the application of active nucleoli counting analysis.

Wolbachia are endocellular bacteria known for manipulating the reproductive systems of many of their invertebrate hosts. Wolbachia are transmitted vertically from mother to offspring. In addition, new infections result from horizontal... more

Wolbachia are endocellular bacteria known for manipulating the reproductive systems of many of their invertebrate hosts. Wolbachia are transmitted vertically from mother to offspring. In addition, new infections result from horizontal transmission between different host species. However, to what extent horizontal transmission plays a role in the spread of a new infection through the host population is unknown. Here, we investigate whether horizontal transmission of Wolbachia can explain clonal genetic variation in natural populations of Leptopilina clavipes, a parasitoid wasp infected with a parthenogenesis-inducing Wolbachia. We assessed variance of markers on the nuclear, mitochondrial and Wolbachia genomes. The nuclear and mitochondrial markers displayed significant and congruent variation among thelytokous wasp lineages, showing that multiple lineages have become infected with Wolbachia. The alternative hypothesis in which a single female became infected, the daughters of which mated with males (thus introducing nuclear genetic variance) cannot account for the presence of concordant variance in mtDNA. All Wolbachia markers, including the hypervariable wsp gene, were invariant, suggesting that only a single strain of Wolbachia is involved. These results show that Wolbachia has transferred horizontally to infect multiple female lineages during the early spread through L. clavipes. Remarkably, multiple thelytokous lineages have persisted side by side in the field for tens of thousands of generations.

The genus Brevipalpus includes most of the economically important species of Tenuipalpidae. Many Brevipalpus species reproduce by theletokous parthenogenesis while other species reproduce by male fertilization of female eggs. Previous... more

The genus Brevipalpus includes most of the economically important species of Tenuipalpidae. Many Brevipalpus species reproduce by theletokous parthenogenesis while other species reproduce by male fertilization of female eggs. Previous researchers have determined that Brevipalpus californicus (Banks), B. obovatus Donnadieu, and B. phoenicis (Geijskes) females were haploid with two chromosomes. The life cycle and developmental times for these three species are reviewed. Longevity of each Brevipalpus species is two to three times greater than corresponding longevities of various tetranychid mites. Brevipalpus mites inject toxic saliva into fruits, leaves, stems, twigs, and bud tissues of numerous plants including citrus. Feeding injury symptoms on selected plants include: chlorosis, blistering, bronzing, or necrotic areas on leaves by one or more Brevipalpus mites. Premature leaf drop occurred on ‘Robinson’ tangerine leaves in Florida (USA). Leaf drop was observed in several sweet orange and grapefruit orchards in Texas (USA) that were heavily infested with Brevipalpus mites feeding on the twigs, leaves, and fruit. Initial circular chlorotic areas appear on both sweet orange and grapefruit varieties in association with developing populations of Brevipalpus mites in Texas. These feeding sites become progressively necrotic, darker in color, and eventually develop into irregular scab-like lesions on affected fruit. Russeting and cracking of the fruits of other plant hosts are reported. Stunting of leaves and the development of Brevipalpus galls on terminal buds were recorded on sour orange, Citrus aurantium L., seedlings heavily infested with B. californicus in an insectary. The most significant threat posed by these mites is as vectors of a potentially invasive viral disease called citrus leprosis.

Whole-body human chimerism is the result of two zygotes giving rise to one individual, and is a rarely detected condition. We have studied the molecular background and discuss the likely mechanism for the chimerism in a patient with a... more

Whole-body human chimerism is the result of two zygotes giving rise to one individual, and is a rarely detected condition. We have studied the molecular background and discuss the likely mechanism for the chimerism in a patient with a 46,XX/47,XY,þ14 karyotype and ambiguous genitalia, cryptorchidism, pigment anomalies, and normal psychomotor development. We have used karyotyping, interphase-FISH and array-CGH analysis as well as molecular analysis of polymorphic markers from 48 loci in order to define the origin and percentage of 47,XY,þ14 cells in different tissues. Based on the findings of two paternal alleles and the detection of homozygous maternal alleles without evidence of crossing-over, and the fact that four alleles were never detected, our results indicate that the chimerism in our patient is the result of dispermic fertilization of a parthenogenetically activated oocyte. Our report underlines that cytogenetic findings suggesting mosaicism might actually indicate chimerism as an underlying mechanism in patients. It also highlights the difficulties in predicting the clinical outcome in patients with genetic aberrations in mosaic or chimeric form. Ó

Aphids exhibit divergent modes of embryogenesis during the sexual and asexual phases of the life cycle. To explore how a single genome can give rise to these alternative developmental modes, we have initiated embryological studies of the... more

Aphids exhibit divergent modes of embryogenesis during the sexual and asexual phases of the life cycle. To explore how a single genome can give rise to these alternative developmental modes, we have initiated embryological studies of the pea aphid, Acyrthosiphon pisum. Here we present a detailed description of parthenogenetic, viviparous embryonic development in the pea aphid. We compare and contrast development of the parthenogenetic embryo with that of the embryo resulting from sexual reproduction. The primary difference between the embryos is the scale on which development occurs: early parthenogenetic development occurs in a volume approximately three orders of magnitude smaller than the sexual egg, largely because of the apparent absence of yolk in the parthenogenetic egg. This results in a drastically different duration of syncytial energid cleavage and, presumably, patterning processes in the two embryos must act at scales that differ by orders of magnitude. The eggs also dev...

Hera was indigenous and represents a matrilinear system; she reigned alone at Argos, at Samos, her temple at Olympia is distinct from and far earlier than that of Zeus. Her first husband, or rather consort, was Herakles [Heracles]. The... more

The emergence of dramatic morphological differences (disparity) and the ensuing bewildering increase in the number of species (diversity) documented in the fossil record at key stages of animal and plant evolution have defied, and still... more

The emergence of dramatic morphological differences (disparity) and the ensuing bewildering increase in the number of species (diversity) documented in the fossil record at key stages of animal and plant evolution have defied, and still defy, the explanatory powers of Darwin's theory of evolution by natural selection. Among the best examples that have captured the imagination of the layman and the interest of scores of scientists for  years are the origins of land plants from aquatic green plants, of flowering plants from seed plants, of chordates from non-chordates and of tetrapod vertebrates from non-tetrapods; and the conquest of the land by amphibians; the emergence of endotherms from ectotherm animals; the recurrent invention of flight (e.g. in arthropods, birds and mammals) from non-flying ancestors; and the origin of aquatic mammals from fourlegged terrestrial ancestors.

The emergence of dramatic morphological differences (disparity) and the ensuing bewildering increase in the number of species (diversity) documented in the fossil record at key stages of animal and plant evolution have defied, and still... more

The emergence of dramatic morphological differences (disparity) and the ensuing bewildering increase in the number of species (diversity) documented in the fossil record at key stages of animal and plant evolution have defied, and still defy, the explanatory powers of Darwin's theory of evolution by natural selection. Among the best examples that have captured the imagination of the layman and the interest of scores of scientists for  years are the origins of land plants from aquatic green plants, of flowering plants from seed plants, of chordates from non-chordates and of tetrapod vertebrates from non-tetrapods; and the conquest of the land by amphibians; the emergence of endotherms from ectotherm animals; the recurrent invention of flight (e.g. in arthropods, birds and mammals) from non-flying ancestors; and the origin of aquatic mammals from fourlegged terrestrial ancestors.

some reflections on science, myth and the female body

In many parts of the world, the tobacco specialist Myzus persicae nicotianae is isolated from the generalist Myzus persicae s.s. because either or both taxa reproduce parthenogenetically. Here we investigated how the genomic integrity of... more

In many parts of the world, the tobacco specialist Myzus persicae nicotianae is isolated from the generalist Myzus persicae s.s. because either or both taxa reproduce parthenogenetically. Here we investigated how the genomic integrity of the tobacco specialist is maintained in Greece, where both taxa have a bisexual generation on peach. Microsatellite DNA analysis revealed greatest genetic divergence between populations in tobacco-growing regions and those in a region where tobacco is not cultivated. This was irrespective of reproductive mode, which has an important effect on population structure. Bayesian clustering and admixture analyses split the aphid genotypes into three groups, corresponding with persicae, bisexual nicotianae and unisexual nicotianae, respectively. Genetic distance parameters showed strong regional differentiation but marked year-on-year stability, indicating low interpopulation migration. Assortative mating between taxa is promoted by differences in the daily rhythm of female signalling behaviour, with peak activity coinciding with periods of consubspecific male searching activity. Males showed greater attraction to the sex pheromone of their own subspecies. Thus, despite relatively low overall genetic differentiation, processes are in place facilitating further genomic divergence and eventual speciation. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 91, 687–702.

Asexual organisms that naturally coexist with sexual relatives may hold the key to understanding the maintenance of sex and recombination, a long-standing problem in evolutionary biology. This situation applies to the peach-potato aphid,... more

Asexual organisms that naturally coexist with sexual relatives may hold the key to understanding the maintenance of sex and recombination, a long-standing problem in evolutionary biology. This situation applies to the peach-potato aphid, Myzus persicae , in southeastern Australia where cyclical parthenogens form mixed populations with obligate parthenogens. We collected M. persicae from several areas across Victoria, genotyped them at seven microsatellite loci and experimentally determined their reproductive mode. The geographic distribution of reproductive modes was correlated with two environmental variables that differentially affect obligate and cyclical parthenogens; obligate parthenogens were less frequent in areas with cold winters because they cannot produce frost-resistant eggs while cyclical parthenogens were limited by the availability of their primary host, peach, on which sexual reproduction takes place. Clonal diversity increased with the proportion of cyclical parthenogens in a sample because they tended to have unique microsatellite genotypes, whereas many obligate parthenogens were copies of the same genotype. Two obligately asexual genotypes stood out as being very abundant and widespread, one constituting 24% and the other 17.4% of the entire collection. Both of these highly successful genotypes were present in the majority of all collection sites. Genetic population structure was weak, albeit significant, with a multilocus F ST of only 0.021 when samples were reduced to only one representative of each genotype. Interestingly, obligate parthenogens were, on average, more heterozygous and exhibited larger allele size differences between the two alleles at individual loci than cyclical parthenogens. This striking pattern could result from hybridization, for which we have no evidence, or may reflect the previously proposed model of biased mutational divergence of microsatellite alleles within asexual aphid lineages.

Parthenogenesis is a reproductive strategy typical of lower species where a female gives birth to offsprings without a paternal contribution. On the contrary, parthenogenesis is not a form of natural reproduction in mammals even if... more

Parthenogenesis is a reproductive strategy typical of lower species where a female gives birth to offsprings without a paternal contribution. On the contrary, parthenogenesis is not a form of natural reproduction in mammals even if mammalian oocytes, under appropriate stimuli, can undergo to parthenogenetic activation. This review describes the biological mechanisms regulating parthenogenetic activation in mammals and illustrates the fundamental differences between embryos and parthenotes. Ethical, legal and political concerns on the value of human embryos regulate and limit human embryological studies founded on the widespread belief that human embryos should not be created and studied for research purposes only. Based on the differences between parthenotes and embryos the use of parthenogenesis is proposed as an experimental tool to investigate embryo development which may solve many of the ethical concerns associated with the use of human embryos for experimental purposes. Examples of the possible uses of parthenotes in many field of research such as in vitro assays aimed to study some aspects of assisted reproductive technologies (ART), toxicology or stem cell are described and their validity is discussed.

Virgin birth is a common theme in religious myths, science fiction, lesbian and feminist imaginaries, and sensational news stories. Virgin birth enters a laboratory setting through biologists' use of the term parthenogenesis (Greek for... more

Virgin birth is a common theme in religious myths, science fiction, lesbian and feminist imaginaries, and sensational news stories. Virgin birth enters a laboratory setting through biologists' use of the term parthenogenesis (Greek for virgin birth) to describe various forms of development without sperm. Scientific consensus holds that viable mammalian parthenogenesis is impossible; that is, mammalian embryos require both a maternal and a paternal contribution to develop completely. This essay investigates the historical development of that consensus and the evolving scientific language of parthenogenesis after the birth of Kaguya, a mouse with two mothers and no father. I qualitatively analyze 202 peer-reviewed scientific publications that cite the Kaguya experiment, and find unconventional interpretations of sex and parenthood, even in publications that maintain the impossibility of mammalian parthenogenesis. Though many scientists insist that males are necessary, they also describe eggs as paternal, embryos as sperm-free, and bimaternal sexual reproduction as something distinct from parthenogenesis. I argue that the scientific language used to explain the Kaguya experiment both supports a heteronormative reproductive status quo and simultaneously challenges it, offering bimaternal sexual reproduction as a feasible alternative.

A 22-year-old captive Brazilian rainbow boa (Epicrates cenchria cenchria) gave birth to four offspring after being housed with a vasectomized male. Sexual reproduction as a result of failed prior vasectomy, recanalization of the vas... more

A 22-year-old captive Brazilian rainbow boa (Epicrates cenchria cenchria) gave birth to four offspring after being housed with a vasectomized male. Sexual reproduction as a result of failed prior vasectomy, recanalization of the vas deferens, or prolonged sperm storage was ruled out using the clinical history, histopathology, and gross necropsy. Short tandem repeat (STR) DNA markers were genotyped in the male, female, and four offspring. None of the offspring possessed a diagnostic STR allele present in the potential sire. In addition, all offspring were homozygous at each STR locus evaluated, supporting parthenogenetic reproduction. This is the first report of parthenogenesis in a Brazilian rainbow boa and has implications for the conservation of reptiles maintained in captive breeding programs.

Despite inferior results in the past compared with embryo freezing, oocyte cryopreservation has made great strides in recent years. In fact, it has become a necessity in assisted reproduction technology, providing alternatives to legal,... more

Despite inferior results in the past compared with embryo freezing, oocyte cryopreservation has made great strides in recent years. In fact, it has become a necessity in assisted reproduction technology, providing alternatives to legal, moral and religious problems originating from embryo freezing. Recent advances in freezing technology, modifi cations of conventional protocols used and continuing optimization of vitrifi cation have effi ciently improved the method. A historical description of the method's progression over time, and a comparison of principles, procedures and results as reported in the literature are presented in this review.

In many parts of the world, the tobacco specialist Myzus persicae nicotianae is isolated from the generalist Myzus persicae s . s . because either or both taxa reproduce parthenogenetically. Here we investigated how the genomic integrity... more

In many parts of the world, the tobacco specialist Myzus persicae nicotianae is isolated from the generalist Myzus persicae s . s . because either or both taxa reproduce parthenogenetically. Here we investigated how the genomic integrity of the tobacco specialist is maintained in Greece, where both taxa have a bisexual generation on peach. Microsatellite DNA analysis revealed greatest genetic divergence between populations in tobacco-growing regions and those in a region where tobacco is not cultivated. This was irrespective of reproductive mode, which has an important effect on population structure. Bayesian clustering and admixture analyses split the aphid genotypes into three groups, corresponding with persicae , bisexual nicotianae and unisexual nicotianae , respectively. Genetic distance parameters showed strong regional differentiation but marked year-on-year stability, indicating low interpopulation migration. Assortative mating between taxa is promoted by differences in the daily rhythm of female signalling behaviour, with peak activity coinciding with periods of consubspecific male searching activity. Males showed greater attraction to the sex pheromone of their own subspecies. Thus, despite relatively low overall genetic differentiation, processes are in place facilitating further genomic divergence and eventual speciation.

Abstract Thelytokous parthenogenesis, the production of female-only offspring from unfertilized eggs, has been described in all the insect orders, but is a rare phenomenon in the Odonata (dragonflies and damselflies). The only-known case... more

Abstract Thelytokous parthenogenesis, the production of female-only offspring from unfertilized eggs, has been described in all the insect orders, but is a rare phenomenon in the Odonata (dragonflies and damselflies). The only-known case of parthenogenesis in this group is the North American damselfly species Ischnura hastata, which has parthenogenetic populations in the Azores Islands. Here, we present for the first time the results of laboratory rearing, which showed parthenogenetic reproduction in the Azorean I.

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We examined the population structure of the introduced aphid, Myzus persicae collected mainly from its primary host, Prunus persica, in south-east Australia. Myzus persicae has been present in Australia since at least 1893. Samples were... more

We examined the population structure of the introduced aphid, Myzus persicae collected mainly from its primary host, Prunus persica, in south-east Australia. Myzus persicae has been present in Australia since at least 1893. Samples were collected in the spring of 1998 from two mainland and three Tasmanian localities and isofemale lines were established in the laboratory. The reproductive mode (life cycle), karyotype and 17-locus microsatellite genotype of each clone were determined. All populations showed significant population differentiation (F ST 0.058-0.202) even over small geographic distances (Ͻ50 km). All clones were karyotypically normal except for a subset of clones from one site that was exposed to the carbamate insecticide, Pirimor,

Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step... more

Polyploid genomes evolve and follow a series of dynamic transfigurations along with adaptation and speciation. The initial formation of a new polyploid individual within a diploid population usually involves a triploid bridge, a two-step mechanism of cell fusions between ubiquitous (reduced) and rare (unreduced) gametes. The primary fusion event creates an intermediate triploid individual with unbalanced genome sets, a situation of genomic-shock characterized by gene expression dysregulation, high dosage sensitivity, disturbed cell divisions, and physiological and reproductive attributes drastically altered. This near-sterile neotriploid must produce (even) eupolyploids through secondary fusion events to restore genome steadiness, meiotic balance, and fertility required for the demographic establishment of a nascent lineage. Natural conditions locate several difficulties to polyploid establishment, including the production of highly unbalanced and rarely unreduced (euploid) gametes, frequency-dependent disadvantages (minority cytotype exclusion), severe fitness loss, and ecological competition with diploid parents. Persistence and adaptation of neopolyploids depend upon genetic and phenotypic novelty coupled to joint selective forces that preserve shock-induced genomic changes (subgenome homeolog partitioning) and drive meiotic (reproductive) stabilization and ecological diversification. Thus, polyploid establishment through the triploid bridge is a feasible but not ubiquitous process that requires a number of low-probability events and singular circumstances. Yet, frequencies of polyploids suggest that polyploid establishment is a pervasive process. To explain this disparity, and supported in experimental evidence, I propose that situations like hybridization and ploidy-state transitions associated to genomic shock and substantial developmental alterations can transiently activate apomixis as a mechanism to halt genomic instability and cancel factors restraining neopolyploid's sexual fertility, particularly in triploids. Apomixis –as a temporal alternative to sex– skip meiosis and syngamy, and thus can freeze genomic attributes, avoid unbalanced chromosomal segregation and increase the formation of unreduced euploid gametes, elude frequency-dependent reproductive disadvantages by parthenogenetic development of the embryo and permissive development of endosperm during seed formation, and increase the effective population size of the neopolyploid lineage favoring the formation rate of eupolyploids compared to aneuploids. The subsequent action of genome resilience mechanisms that alleviate transcriptomic shock and selection upon gene interactions might restore a stable
meiosis and sexual fertility within few generations, as observed in synthetic polyploids. Alternatively, provided that resilience mechanisms fail, the neopolyploid might retain apomixis and hold genomically and transcriptionally altered states for many generations.

We used polymorphic microsatellite markers to look for recombination during parthenogenetic oogenesis between the X chromosomes of aphids of the tribe Macrosiphini. We examined the X chromosome because it comprises " 25 % of the genome... more

We used polymorphic microsatellite markers to look for recombination during parthenogenetic oogenesis between the X chromosomes of aphids of the tribe Macrosiphini. We examined the X chromosome because it comprises " 25 % of the genome and previous cytological observations of chromosome pairing and nucleolar organizer (NOR) heteromorphism suggest recombination, although the same is not true for autosomes. A total of 564 parthenogenetic females of Myzus clones with three distinct reproductive modes (cyclical parthenogenesis, obligate parthenogenesis and obligate parthenogenesis with male production) were genotyped at three informative X-linked loci. Also, parthenogenetically produced males from clones encompassing the full range of maleproducing reproductive strategies were genotyped. These included 391 Myzus persicae males that were genotyped at three X-linked loci and 538 males from Sitobion clones that were genotyped at five informative X-linked loci. Our results show no departure from clonality in parthenogenetic generations of aphids of the tribe Macrosiphini : no recombinant genotypes were observed in parthenogenetically produced males or females.

A total of 8 calves approximately 6 months old and 22 lambs of similar age were infected with metacercariae of Fasciola hepatica of various laboratory-maintained isolates including: Cullompton (sensitive to triclabendazole) and Sligo,... more

A total of 8 calves approximately 6 months old and 22 lambs of similar age were infected with metacercariae of Fasciola hepatica of various laboratory-maintained isolates including: Cullompton (sensitive to triclabendazole) and Sligo, Oberon and Leon (reported as resistant to triclabendazole). Ten to 16 weeks after infection, flukes were harvested from these experimental animals and the histology of the testis tissue was examined in a representative sample of flukes from each population. Adult wild-type flukes were also collected from 5 chronically infected cattle and 7 chronically infected sheep identified at post-mortem inspection. The testis tissue of these flukes was compared with that of the various laboratory-maintained isolates. Whilst the testes of the wild-type, Oberon and Leon flukes displayed all the usual cell types associated with spermatogenesis in Fasciola hepatica (spermatogonia, spermatocytes, spermatids and mature sperm), the Cullompton flukes from both cattle and sheep showed arrested spermatogenesis, with no stages later than primary spermatocytes represented in the testis profiles. The presence of numerous eosinophilic apoptotic bodies and nuclear fragments suggested that meiotic division was anomalous and incomplete. In contrast to the wild-type flukes, no mature spermatozoa were present in the testes or amongst the shelled eggs in the uterus. A high proportion of the eggs collected from these flukes hatched to release normal-appearing miracidia after an appropriate incubation period, as indeed was the case with all isolates examined and the wild-type flukes. It is concluded that the eggs of Cullompton flukes are capable of development without fertilization, i.e. are parthenogenetic. The implications of this for rapid evolution of resistant clones following an anthelmintic selection event are discussed. Amongst the Sligo flukes examined, two subtypes were recognised, namely, those flukes with all stages of spermatogenesis and mature spermatozoa present in the testes (type 1), and those flukes with all stages of spermatogenesis up to spermatids present, but no maturing spermatozoa in the testes (type 2). Each sheep infected with the Sligo isolate had both type 1 (approximately 60%) and type 2 (approximately 40%) flukes present in the population. Spermatozoa were found amongst the eggs in the uterus in 64% of flukes and this did not necessarily reflect the occurrence of spermatozoa in the testis profiles of particular flukes, suggesting that cross-fertilization had occurred. The apparent disruption of meiosis in the spermatocytes of the Cullompton flukes is consistent with reports that Cullompton flukes are triploid (3n = 30), whereas the Sligo and wild-type flukes are diploid (2n = 20). In the Sligo flukes the populations are apparently genetically heterogenous, with a proportion of the flukes unable to produce fully formed spermatozoa perhaps because of a failure in spermiogenesis involving elongation of the nucleus during morphogenesis. #

According to a dominant view in the scholarly literature, Musschenbroek is to be considered a follower of Newton’s methodology, i.e. as a natural philosopher who, although he occasionally departed from Newton’s doctrines, aligned himself... more

According to a dominant view in the scholarly literature, Musschenbroek is to be considered a follower of Newton’s methodology, i.e. as a natural philosopher who, although he occasionally departed from Newton’s doctrines, aligned himself to Newton’s methodological views. Few scholars have, however, explained in full detail what it means to claim that Musschenbroek followed Newton’s method. The purpose of this essay is to get more grip on this matter.

Multivariate morphometric analysis (method of canonical variates) was used to compare 38 parthenogenetic lineages and three field collections of aphids of the Myzus persicae (Sulzer) group sampled on peach and tobacco in the Caserta... more

Multivariate morphometric analysis (method of canonical variates) was used to compare 38 parthenogenetic lineages and three field collections of aphids of the Myzus persicae (Sulzer) group sampled on peach and tobacco in the Caserta region of southern Italy. Comparisons were also made with the morphology of lineages collected on peach in Lehonia, in central eastern Greece away from tobaccogrowing regions, and on tobacco in Naphplion, in southern Greece. The lineages were measured after parthenogenetic rearing for one to three generations on the same host (potato) under constant conditions. As in previous work, the multivariate morphometric approach separated the aphids from peach from those feeding on tobacco. The life cycle category of the lineages was also examined. Almost all the lineages from peach in Caserta were holocyclic, yet the lineages from tobacco in the same region were unable to produce sexual morphs. The results suggest that tobacco-adapted and non-tobacco-adapted forms co-exist in the same region in southern Italy, not only because they colonize different host plants, but also because they have different life cycles. This is in complete contrast to the situation in peach-growing areas of northern Greece, and shows that the ecology and population structure of M. persicae is different in neighbouring counties of the Mediterranean area, even where climatic conditions and cultivated crops are similar.

Los defensores del método partenogénico afirman evitar el problema ético que supone la clonación para la obtención de embriones de los que se puedan derivar líneas celulares útiles en terapia regenerativa. En el caso de la clonación, así... more

Los defensores del método partenogénico afirman evitar el problema ético que supone la clonación para la obtención de embriones de los que se puedan derivar líneas celulares útiles en terapia regenerativa. En el caso de la clonación, así como en la
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utilización de embriones obtenidos por fecundación in vitro, estos deben ser destruidos para la obtención de las células troncales, lo que implica la destrucción de seres humanos.
No sería este el caso, según afirman los partidarios de la partenogénesis, de esta técnica, en la que el partenote no sería considerado como ser humano

A new nematode, Elaeolenchus parthenonema n. g., n. sp., is described from the palm-pollinating weevil Elaeidobius kamerunicus Faust. The new genus is placed in the Anandranematidae n. fam., which, together with the genus Anandranema... more

A new nematode, Elaeolenchus parthenonema n. g., n. sp., is described from the palm-pollinating weevil Elaeidobius kamerunicus Faust. The new genus is placed in the Anandranematidae n. fam., which, together with the genus Anandranema Poinar et al., 1993, is characterised by nematodes having only a single autotokous generation in the insect host. This is the first report of a member of this superfamily reproducing only parthenogenetically. The development of E. parthenonema and its effect on the weevil host is discussed, along with a phylogenetic synopsis of the families of the Sphaerularioidea Lubbock 1861. The Beddingiidae n. fam. is proposed for Beddingia Blinova & Korenchenko, 1986, comprising the original Deladenus parasites of Hymenoptera that possess both free-living and parasitic amphimictic generations in their life-cycles. This family is considered to have the most primitive type of development in the superfamily.

Apomixis, the asexual reproduction via seed, often occurs in huge plant polyploid complexes with large geographical distributions. However, the long-term evolutionary fate of asexuals traditionally was regarded as doomed by extinction. A... more

Apomixis, the asexual reproduction via seed, often occurs in huge plant polyploid complexes with large geographical distributions. However, the long-term evolutionary fate of asexuals traditionally was regarded as doomed by extinction. A seven-step evolutionary model is presented to explain the role of sex → apomixis shifts on geographical cytotype distributions, and the potential consequences of reversals apomixis → sex on plant diversity. Accordingly, apomictic polyploid genotypes act as facilitators for range expansions of asexual taxa in agamic complexes by functioning as pioneer explorers of new niches. High intragenomic (allelic) diversity and epigenetic variability may help for rapid adaptation. Therefore, they could rapidly expand the distribution areas of their progenitor sexual populations by occupying new ecological niches and geographical areas. Hence, apomixis would result in divergent patterns of geographic distribution between sexual and asexuals, a pattern described as “geographical parthenogenesis,” in which apomicts occupy extensive geographical areas and higher latitudinal zones while sexual relatives are restricted to small refugees. Later on, reversals to complete sexuality would allow for the establishment of new sexual populations in different habitats without the long-term disadvantages of asexuality. The new sexual recombinants will be genetically isolated from the original sexual populations and consequently predisposed to a divergent evolution, and potentially enabled to evolve into new sexual species. The present model stresses a previously unidentified evolutionary significance of the geographical parthenogenesis as a motor for plant diversification.

Fertilisation occurs when sperm and egg recognise each other and fuse to form a new, genetically distinct organism. The molecular basis of sperm-egg recognition is unknown, but is likely to require interactions between receptor proteins... more

Fertilisation occurs when sperm and egg recognise each other and fuse to form a new, genetically distinct organism. The molecular basis of sperm-egg recognition is unknown, but is likely to require interactions between receptor proteins displayed on their surface. Izumo1 is an essential sperm cell surface protein, but its egg receptor has remained a mystery. Here, we identify Juno as the receptor for Izumo1 on mouse eggs, and show this interaction is conserved within mammals. Female mice lacking Juno are infertile and Juno-deficient eggs do not fuse with normal sperm. Rapid shedding of Juno from the oolemma after fertilisation suggests a mechanism for the membrane block to polyspermy, ensuring eggs normally fuse with just a single sperm. Our discovery of an essential receptor pair at the nexus of conception provides opportunities for the rational development of new fertility treatments and contraceptives.

Host-associated differentiation (HAD) is the formation of genetically divergent host-associated sub-populations. Evidence of HAD has been reported for multiple insect herbivores to date, but published studies testing more than one... more

Host-associated differentiation (HAD) is the formation of genetically divergent host-associated sub-populations. Evidence of HAD has been reported for multiple insect herbivores to date, but published studies testing more than one herbivore for any given host-plant species pair is limited to herbivores on goldenrods. This limits the number of pair-wise comparisons that can be made about insect life-history traits that might facilitate or inhibit host-race development in general. Two traits previously proposed to facilitate HAD include endophagy and parthenogenesis. We tested for HAD in two herbivores, a quasi-endophagous caterpillar and a parthenogenetic aphid, feeding on two closely related species of hickories. We found that the quasiendophage is panmictic, whereas the parthenogen exhibits HAD on their sympatric host plants, pecan and water hickory, at a geographic mesoscale. This is an important first step in the characterization of HAD in multiple insect herbivores using North American hickories, a host-plant system with many shared parthenogens.

Embryonic stem cells have a pluripotency and a potential to differentiate to all type of cells. In our previous study, we have shown that embryonic stem cells (ESCs) lines can be generated from murine parthenogenetic embryos. This... more

Embryonic stem cells have a pluripotency and a potential to differentiate to all type of cells. In our previous study, we have shown that embryonic stem cells (ESCs) lines can be generated from murine parthenogenetic embryos. This parthenogenetic ESCs line can be a useful stem cell source for tissue repair and regeneration. The defect in full-term development of parthenogenetic ESCs line enables researchers to avoid the ethical concerns related with ESCs research. In this study, we presented the results demonstrating that parthenogenetic ESCs can be induced into osteogenic cells by supplementing culture media with ascorbic acid and ß-glycerophosphate. These cells showed morphologies of osteogenic cells and it was proven by Von Kossa staining and Alizarin Red staining. Expression of marker genes for osteogenic cells (osteopontin, osteonectin, alkaline phosphatase, osteocalcin, bone-sialoprotein, collagen type1, and Cbfa1) also confirmed osteogenic potential of these cells. These results demonstrate that osteogenic cells can be generated from parthenogenetic ESCs in vitro.

Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of... more

Orconectes limosus, a North American crayfish species, is one of the most important aquatic invaders in European inland waters. Despite more than 120 years occurrence in Europe and intense research, there are still gaps in knowledge of its life history and ecology. Investigation into O. limosus invasive success requires identifying the mechanisms that enabled them to establish dense and widespread populations from small initial numbers without observable limitation by an introduction bottleneck. In part, O. limosus success may lie in its ability to reproduce by facultative parthenogenesis. Moreover, there are possible other mating scenarios, because of two mating seasons (autumn and spring) in O. limosus. This work investigated the effect of four reproductive scenarios (autumn mating only, spring mating only, autumn and spring mating, and without mating) on the reproductive success of O. limosus. Females successfully reproduced in all tested mating regimes using parthenogenesis as w...

In sharp contrast to their southeast Asian and European counterparts, Sitobion miscanthi and S. near fragariae aphids in Australia exhibit a complete absence of sexual reproduction. This demands an explanation within the context of the... more

In sharp contrast to their southeast Asian and European counterparts, Sitobion miscanthi and S. near fragariae aphids in Australia exhibit a complete absence of sexual reproduction. This demands an explanation within the context of the evolution and maintenance of sex and parthenogenesis. Accordingly, we executed a genetic analysis of the two species in neighbouring New Zealand. Microsatellites and single-stranded conformation polymorphism/sequence analysis of the nuclear gene elongation factor 1 α were used to identify aphid clones and confirm species identification, respectively. Karyotypic variation was also investigated. The New Zealand fauna showed few (nonrecombining) genotypes and appears to have received migrants from both Australia and Asia. Other genotypes have apparently arisen in situ in New Zealand, exhibiting stepwise mutation of microsatellite alleles and also karyotypic change. Thus, these data represent rare evidence of evolution within wild-living parthenogenetic lineages. Karyotypic changes appear to occur at a rate even greater than that of microsatellite evolution. Strong geographical partitioning of genotypes/karyotypes was found, with certain ones predominating over large areas. These data suggest that clonal selection could be important in the distribution and patterning of genetic variation. We present a model to explain the genetic patterns, with particular reference to the absence of sexual reproduction in Sitobion aphids in New Zealand and Australia.

Plant-parasitic nematodes are the most destructive group of plant pathogens worldwide and are extremely challenging to control. The recent completion of two root-knot nematode genomes opens the way for a comparative genomics approach to... more

Plant-parasitic nematodes are the most destructive group of plant pathogens worldwide and are extremely challenging to control. The recent completion of two root-knot nematode genomes opens the way for a comparative genomics approach to elucidate the success of these parasites. Sequencing revealed that Meloidogyne hapla, a diploid that reproduces by facultative, meiotic parthenogenesis, encodes approximately 14,200 genes in a compact, 54 Mpb genome. Indeed, this is the smallest metazoan genome completed to date. By contrast, the 86 Mbp Meloidogyne incognita genome encodes approximately 19,200 genes. This species reproduces by obligate mitotic parthenogenesis and exhibits a complex pattern of aneuploidy. The genome includes triplicated regions and contains allelic pairs with exceptionally high degrees of sequence divergence, presumably reflecting adaptations to the strictly asexual reproductive mode. Both root-knot nematode genomes have compacted gene families compared with the free-living nematode Caenorhabditis elegans, and both encode large suites of enzymes that uniquely target the host plant. Acquisition of these genes, apparently via horizontal gene transfer, and their subsequent expansion and diversification point to the evolutionary history of these parasites. It also suggests new routes to their control. 333 Annu. Rev. Phytopathol. 2009.47:333-351. Downloaded from arjournals.annualreviews.org by INRA Institut National de la Recherche Agronomique on 09/11/09. For personal use only. Click here for quick links to Annual Reviews content online, including: • Other articles in this volume • Top cited articles • Top downloaded articles • Our comprehensive search Further ANNUAL REVIEWS RKN: root-knot nematode RNAi: RNA interference PPN: plant-parasitic nematode CAZyme: carbohydrate-active enzyme

The ability of an oocyte to support early embryonic development requires both nuclear and cytoplasmic maturation. We have investigated the effects of brain-derived neurotrophic factor (BDNF) on maturation of the bovine oocyte and embryo... more

The ability of an oocyte to support early embryonic development requires both nuclear and cytoplasmic maturation. We have investigated the effects of brain-derived neurotrophic factor (BDNF) on maturation of the bovine oocyte and embryo development after parthenogenetic activation. By RT-PCR and immunohistochemistry, cumulus and oocytes were shown to express mRNA and protein for BDNF and the p75 common neurotrophin receptor. However, mRNA for the BDNF-specific full length and truncated isoforms of the TrkB receptor are only detected in cumulus, suggesting that oocytes and cumulus differ in their capacity to respond to neurotrophin signalling. In in vitro maturation experiments, the proportion of cumulus oocyte complexes maturing to metaphase II was not altered by BDNF in groups lacking fetal calf serum (FCS), but was significantly lower than the positive control containing 10% FCS (P < 0.01). However, after maturation, the proportion of parthenogenetically activated oocytes forming blastocysts was highest for 10 ng/ml BDNF (24%, n 5 95) followed by 100 ng/ml BDNF (18%, n 5 91) and 10% FCS (15%, n 5 103), which in turn were greater than no serum (10%, n 5 83; P < 0.01). Maturation in the presence of a BDNF blocking antibody resulted in a blastocyst yield that was comparable to the absence of serum, and lower than in the presence of BDNF (P < 0.01). Similar effects on progression to metaphase II and blastocyst formation were observed using oocytes matured without cumulus. Together, these results provide the first evidence for a role for neurotrophins in promoting oocyte cytoplasmic competence to support embryonic development, despite being insufficient in the absence of serum to enhance nuclear maturation. Reproduction (2005) 129 423-434 q 2005 Society for Reproduction and Fertility

Purpose To develop an experimental model to assess the feasibility of polar body preimplantation genetic diagnosis without requiring oocyte fertilization. Methods First polar body was removed from donated oocytes and second polar body was... more

Purpose To develop an experimental model to assess the feasibility of polar body preimplantation genetic diagnosis without requiring oocyte fertilization. Methods First polar body was removed from donated oocytes and second polar body was biopsied after parthenogenetic activation. Molecular analysis on both polar bodies involved a fluorescent multiplex polymerase chain reaction of shorttandem repeat markers, closely linked to genes of interest. Main outcome measures were: allele segregation through polar bodies and haploid nucleus, recombination rates between alleles and frequency of Allele Drop Out.