Reproduction in the spider mite Oligonychus yothersi (Acari: Tetranychidae).

In this work we reported injuries caused by the spider mite Oligonychus yothersi on Vitis vinifera leaves and we also investigate the sex ratio of this species under laboratory conditions. To access the aspects regarding reproduction, females were placed individually in arenas made of V. vinifera leaves to oviposit and all progeny were mounted on slides when they reached adulthood to confirm the offspring sex. Our study showed that O. yothersi reproduces by thelytokous /arrhenotokous parthenogenesis, generating low number of males. Additionally, we found vine plants with leaf browning, particularly on the adaxial surface, where mites were usually found.

Asymmetry is defined during meiosis in the oocyte of the parthenogenetic nematode Diploscapter pachys.

Asymmetric cell division is an essential feature of normal development and certain pathologies. The process and its regulation have been studied extensively in the Caenorhabditis elegans embryo, particularly how symmetry of the actomyosin cortical cytoskeleton is broken by a sperm-derived signal at fertilization, upstream of polarity establishment. Diploscapter pachys is the closest parthenogenetic relative to C. elegans, and D. pachys one-cell embryos also divide asymmetrically. However how polarity is triggered in the absence of sperm remains unknown. In post-meiotic embryos, we find that the nucleus inhabits principally one embryo hemisphere, the future posterior pole. When forced to one pole by centrifugation, the nucleus returns to its preferred pole, although poles appear identical as concerns cortical ruffling and actin cytoskeleton. The location of the meiotic spindle also correlates with the future posterior pole and slight actin enrichment is observed at that pole in some early embryos along with microtubule structures emanating from the meiotic spindle. Polarized location of the nucleus is not observed in pre-meiotic D. pachys oocytes. All together our results are consistent with the idea that polarity of the D. pachys embryo is attained during meiosis, seemingly based on the location of the meiotic spindle, by a mechanism that may be present but suppressed in C. elegans.

Effect of nucleocytoplasmic ratio on the in vitro porcine embryo development after in vitro fertilization or parthenogenetic activation.

This study was conducted to examine whether the nuclear to cytoplasmic (N/C) ratio had any influence on the timing of embryo compaction and blastocoel formation, as well as formation rate and quality of blastocyst. First, we produced embryos with increased N/C ratio by removal of approximately one-third of the cytoplasm and with decreased N/C ratio by doubling the oocyte cytoplasm with an enucleated oocyte. The initiation of compaction and cavitation in reduced cytoplasm group was significantly earlier (P < 0.05) compared with the control and doubled cytoplasm groups. The rate of blastocysts in the reduced cytoplasm and doubled cytoplasm groups was significantly lower (P < 0.05) compared with the control group. Blastocyst quality in terms of total cell number in the reduced cytoplasm group was significantly lower (P < 0.05) compared with the doubled cytoplasm group, but not different from the control group. Next, we produced embryos with various N/C ratios by oocyte fusion combined with cytochalasin D treatment. The onset of compaction and cavitation in the 2N/2C group (decreased N/C ratio) was significantly delayed (P < 0.05) or had the tendency to be delayed (P = 0.064), respectively, compared with the control group (2N/1C). A significantly higher rate of blastocyst was observed in the 4N/2C group compared with the 1N/1C group (P < 0.05) but not different from the remaining groups. These results demonstrated that an increase in N/C ratio caused an earlier occurrence of morula compaction and blastocyst formation in both in vitro fertilization (IVF) and parthenogenetically activated pig embryos.

New techniques for creating parthenogenetic larvae of the sea urchin Lytechinus pictus for gene expression studies.

BACKGROUND: Sea urchins are model organisms for studying the spatial-temporal control of gene activity during development. The Southern California species, Lytechinus pictus, has a sequenced genome and can be raised in the laboratory from egg to egg in 4 to 5 months. RESULTS: Here, we present new techniques for generating parthenogenetic larvae of this species and include a gallery of photomicrographs of morphologically abnormal larvae that could be used for transcriptomic analysis. CONCLUSIONS: Comparison of gene expression in parthenogenotes to larvae produced by fertilization could provide novel insights into gene expression controls contributed by sperm in this important model organism. Knowledge gained from transcriptomics of sea urchin parthenogenotes could contribute to parthenogenetic studies of mammalian embryos.

Protein phosphatase 2A is essential to maintain meiotic arrest, and to prevent Ca2+ burst at spawning and eventual parthenogenesis in the larvacean Oikopleura dioica.

Unfertilized eggs of most animals are arrested at a certain point in the meiotic cell cycles. Reinitiation of meiosis and the start of embryogenesis are triggered by fertilization. This arrest is essential for preventing parthenogenetic activation and for promoting proper initiation of development by fertilization. In the larvacean Oikopleura dioica, which is a simple model organism for studies of chordate development, the unfertilized egg is arrested at metaphase of meiosis I. We show here that protein phosphatase 2A (PP2A) is essential for maintenance of meiotic arrest after spawning of oocytes. Knockdown (KD) of the maternal PP2A catalytic subunit, which was found in functional screening of maternal factors, caused unfertilized eggs to spontaneously release polar bodies after spawning, and then start pseudo-cleavages without fertilization, namely, parthenogenesis. Parthenogenetic embryos failed to undergo proper mitosis and cytokinesis because of lack of a centrosome, which is to be brought into the egg by a sperm. Activation of the KD oocytes was triggered by possible rise of ambient and intracellular pH upon their release from the gonad into seawater at spawning. Live recording of intracellular calcium level of the KD oocytes indicated that the pH rise caused an aberrant Ca2+ burst, which mimicked the Ca2+ burst that occurs at fertilization. Then, the aberrant Ca2+ burst triggered meiosis resumption through Calcium/calmodulin-dependent protein kinase (CaMK II). Therefore, PP2A is essential for maintenance of meiotic arrest and prevention of parthenogenesis by suppressing the aberrant Ca2+ burst at spawning.

Downstream of GA4, PbCYP78A6 participates in regulating cell cycle-related genes and parthenogenesis in pear (Pyrus bretshneideri Rehd.).

BACKGROUND: Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear (Pyrus bretshneider). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis. RESULTS: Here, in a transcriptional comparison between pollination-dependent fruit and GA4-induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlets development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression in pear calli revealed that the gene is an upstream regulator of specific fruit development-related genes in pear. CONCLUSIONS: Our findings indicate that PbCYP78A6 plays a critical role in fruit formation and provide insights into controlling parthenocarpy.

Life cycle of Ixodes schulzei (Acari: Ixodidae) in the laboratory, and demonstration of reproduction by parthenogenesis.

Ixodes schulzei is an ixodid tick that parasitizes Cricetidae rodents, chiefly the South American water rat, Nectomys squamipes, in Brazil and Argentina. In the present study, we evaluated the life cycle of I. schulzei by exposing larvae and nymphs to feed on two rodent species, N. squamipes and Calomys callosus (large vesper mouse),while adult ticks were exposed to feed on N. squamipes. Off-host developmental periods were observed in an incubator at 27 °C, 95% relative humidity, and 0:24 (light:dark) regimen. Larvae and nymphs successfully fed on either C. callosus or N. squamipes. Mean larval and nymphal feeding periods were 8.8 and 8.7 days on N. squamipes and 8.5 and 9.7 days on C. callosus. The majority of engorged larvae (79.0-80.8%) and nymphs (67.0-86.0%) successfully molted to nymphs and adults, respectively. Mean premolt periods were 11.5-11.7 days for engorged larvae and 22.5-23.7 days for engorged nymphs. Only adult females emerged from engorged nymphs, regardless of host species, i.e., none of 120 engorged nymphs molted to male. Around 18% of the unfed females presented teratologies compatible with the metagynander type of gynandromorphism. Ixodes schulzei adult females successfully fed (mean feeding period, 9.4 days), oviposited, and presented high reproductive performance (high engorged weight, egg mass weight, and % egg mass hatching), in the absence of male ticks. Our results showed that I. schulzei successfully reproduces by parthenogenesis, and corroborate field data that indicate N. squamipes as the most important host for this tick species. The male of I. schulzei remains unknown.

Derivation of Mouse Parthenogenetic Advanced Stem Cells.

Parthenogenetic embryos have been widely studied as an effective tool related to paternal and maternal imprinting genes and reproductive problems for a long time. In this study, we established a parthenogenetic epiblast-like stem cell line through culturing parthenogenetic diploid blastocysts in a chemically defined medium containing activin A and bFGF named paAFSCs. The paAFSCs expressed pluripotent marker genes and germ-layer-related genes, as well as being alkaline-phosphatase-positive, which is similar to epiblast stem cells (EpiSCs). We previously showed that advanced embryonic stem cells (ASCs) represent hypermethylated naive pluripotent embryonic stem cells (ESCs). Here, we converted paAFSCs to ASCs by replacing bFGF with bone morphogenetic protein 4 (BMP4), CHIR99021, and leukemia inhibitory factor (LIF) in a culture medium, and we obtained parthenogenetic advanced stem cells (paASCs). The paASCs showed similar morphology with ESCs and also displayed a stronger developmental potential than paAFSCs in vivo by producing chimaeras. Our study demonstrates that maternal genes could support parthenogenetic EpiSCs derived from blastocysts and also have the potential to convert primed state paAFSCs to naive state paASCs.

To have and not to have sex: When multiple evolutions of conditional use of sex elegantly solve the question in the ant genus Cataglyphis.

Organisms use an amazingly large diversity of mechanisms to pass on their genes to the next generation. Sex is ancestral in eukaryotes, where it remains the most widespread way of reproduction. By combining one's genes with those of a partner, sex entails a dilution of one's genes at each generation. Evolution has been particularly creative in devising mechanisms allowing females to avoid this dilution, from classical parthenogenesis to the elimination of male genes after fertilization (Bell, 1982). Moreover, the term parthenogenesis includes various forms. Parthenogenesis can be used for female (thelytoky) or male (arrhenotoky) production and it can be associated with different cytological mechanisms, from strict clonality to meiotic division with the fusion of two of the four products of meiosis to restore diploidy (Suomalainen, Saura, & Lokki, 1987). Understanding the evolution of these diverse reproductive systems remains one of the most exciting and longstanding questions in evolutionary biology. By characterizing the reproductive systems of 11 species from the thermophilic ant genus Cataglyphis, in this issue of Molecular Ecology, Kuhn, Darras, Paknia, and Aron (2020) show the high lability of parthenogenesis, with multiple independent evolution of facultative thelytoky from sexual ancestors. The diversity of life history traits and social characteristics of this genus (e.g., mode of colony foundation, female polyandry) provides a unique and exciting opportunity to investigate the social and environmental factors driving the evolution of reproductive systems in social Hymenoptera.

Intrafollicular spontaneous parthenogenetic development of dromedary camel oocytes.

Dromedary camel oocytes are unique in their capability for intrafollicular and in vitro spontaneous parthenogenetic activation (SPA) and development. This study was designed for (a) observing the incidence of SPA and development of dromedary camel oocytes retrieved from ovaries; (b) assessing intrafollicular development of dromedary camel oocytes using histological examination; (c) evaluating the abilities of dromedary camel oocytes to mature, SPA, and develop in vitro; and (d) identifying the transcript abundance of Cdx2 messenger RNA (mRNA) expression in different stages of SPA and developed camel embryos. The results revealed that 2.33% of oocytes retrieved from dromedary camel ovaries were SPA and developed to blastocyst stage. Serial sections of dromedary camel ovaries also demonstrated the presence of 1.4 SPA and parthenotes per ovary, which included from two-cell to the blastocysts with demarcated trophectoderm and inner cell mass layers. A total of 2.6% in vitro matured dromedary camel oocytes developed into morulae. The SPA and developed dromedary embryos expressed transcript abundance for Cdx2 mRNA with the highest (p < .05) at the blastocyst. The present work determines for the first time the intrafollicular oocytes from the dromedary camel display SPA, and the parthenotes can develop into blastocysts and expressing Cdx2 mRNA.

Induction of autophagy promotes porcine parthenogenetic embryo development under low oxygen conditions.

Autophagy plays an important role in embryo development; however, only limited information is available on how autophagy specifically regulates embryo development, especially under low oxygen culture conditions. In this study we used parthenogenetic activation (PA) of porcine embryos to test the hypothesis that a low oxygen concentration (5%) could promote porcine embryo development by activating autophagy. Immunofluorescence staining revealed that low oxygen tension activated autophagy and alleviated oxidative stress in porcine PA embryos. Development was significantly affected when autophagy was blocked by 3-methyladenine, even under low oxygen culture conditions, with increased reactive oxygen species levels and malondialdehyde content. Furthermore, the decreased expression of pluripotency-associated genes induced by autophagy inhibition could be recovered by treatment with the antioxidant vitamin C. Together, these results demonstrate that low oxygen-induced autophagy regulates embryo development through antioxidant mechanisms in the pig.

Steroid hormones, energetic state, and immunocompetence vary across reproductive contexts in a parthenogenetic lizard.

Reproduction is energetically expensive and investing in this life history trait is likely accompanied by significant changes in physiological activity. Investment strategy necessary for achieving reproductive success in reptiles can vary with reproductive form and pattern, potentiating different consequences for competing fitness-related traits such as those key to survival. The goal of this study was to assess if and how energetic state (i.e., energy metabolites) and self-maintenance (i.e., immunocompetence) are hormonally modulated across reproductive contexts in an oviparous, parthenogenetic lizard, the Colorado Checkered Whiptail Aspidoscelis neotesselata. Here blood plasma samples were collected from lizards within the US Army Fort Carson Military Installation near Colorado Springs, CO, USA, during seasons of reproductive activity (i.e., June) and inactivity (i.e., August). Measures of reproductive (i.e., estradiol) and energy-mobilizing (i.e., corticosterone) hormones, energy metabolites (i.e., glucose, triglycerides, and free glycerol), and innate immunity (i.e., bactericidal ability) were compared by season and reproductive stage. Levels of energy metabolites and bactericidal ability were compared to levels of E2 and CORT. Bactericidal ability was also compared to levels of energy metabolites. Corticosterone and glucose levels were lower during the reproductive season while triglyceride levels and bactericidal ability were higher, but both estradiol and free glycerol levels did not differ between seasons. Throughout vitellogenesis, corticosterone and glucose levels as well as bactericidal ability did not differ, but estradiol levels were higher during early and mid-stage and both triglyceride and free glycerol levels were lower during gravidity. Corticosterone levels were negatively associated with circulating triglycerides and bactericidal ability, but were not related to glucose nor free glycerol levels. Estradiol levels were positively associated with free glycerol levels and bactericidal ability, but were not related to glucose nor triglyceride levels. Finally, bactericidal ability was negatively associated with glucose, but positively associated with triglycerides. Differences in energetic state and immunocompetence are thus reflected by shifts in hormone secretion across reproductive investment. These findings provide partial support for the hypothesis that energetic state is differentially regulated by steroid hormones to afford reproduction, potentially at the cost of future survival.

Embryonic development of a parthenogenetic vertebrate, the mourning gecko (Lepidodactylus lugubris).

BACKGROUND: One goal of evolutionary developmental biology is to understand the role of development in the origin of phenotypic novelty and convergent evolution. Geckos are an ideal system to study this topic, as they are species-rich and exhibit a suite of diverse morphologies-many of which have independently evolved multiple times within geckos. RESULTS: We characterized and discretized the embryonic development of Lepidodactylus lugubris-an all-female, parthenogenetic gecko species. We also used soft-tissue µCT to characterize the development of the brain and central nervous system, which is difficult to visualize using traditional microscopy techniques. Additionally, we sequenced and assembled a de novo transcriptome for a late-stage embryo as a resource for generating future developmental tools. Herein, we describe the derived and conserved patterns of L. lugubris development in the context of squamate evolution and development. CONCLUSIONS: This embryonic staging series, µCT data, and transcriptome together serve as critical enabling resources to study morphological evolution and development, the evolution and development of parthenogenesis, and other questions concerning vertebrate evolution and development in an emerging gecko model.

Widespread failure to complete meiosis does not impair fecundity in parthenogenetic whiptail lizards.

Parthenogenetic species of whiptail lizards in the genus Aspidoscelis constitute a striking example of speciation by hybridization, in which first-generation hybrids instantly attain reproductive isolation and procreate as clonal all-female lineages. Production of eggs containing a full complement of chromosomes in the absence of fertilization involves genome duplication prior to the meiotic divisions. In these pseudo-tetraploid oocytes, pairing and recombination occur exclusively between identical chromosomes instead of homologs; a deviation from the normal meiotic program that maintains heterozygosity. Whether pseudo-tetraploid cells arise early in germ cell development or just prior to meiosis has remained unclear. We now show that in the obligate parthenogenetic species A. neomexicana the vast majority of oocytes enter meiosis as diploid cells. Telomere bouquet formation is normal, but synapsis fails and oocytes accumulate in large numbers at the pairing stage. Pseudo-tetraploid cells are exceedingly rare in early meiotic prophase, but they are the only cells that progress into diplotene. Despite the widespread failure to increase ploidy prior to entering meiosis, the fecundity of parthenogenetic A. neomexicana is similar to that of A. inornata, one of its bisexual ancestors.

Mouse Parthenogenetic Embryonic Stem Cells with Biparental-Like Expression of Imprinted Genes Generate Cortical-Like Neurons That Integrate into the Injured Adult Cerebral Cortex.

One strategy for stem cell-based therapy of the cerebral cortex involves the generation and transplantation of functional, histocompatible cortical-like neurons from embryonic stem cells (ESCs). Diploid parthenogenetic Pg-ESCs have recently emerged as a promising source of histocompatible ESC derivatives for organ regeneration but their utility for cerebral cortex therapy is unknown. A major concern with Pg-ESCs is genomic imprinting. In contrast with biparental Bp-ESCs derived from fertilized oocytes, Pg-ESCs harbor two maternal genomes but no sperm-derived genome. Pg-ESCs are therefore expected to have aberrant expression levels of maternally expressed (MEGs) and paternally expressed (PEGs) imprinted genes. Given the roles of imprinted genes in brain development, tissue homeostasis and cancer, their deregulation in Pg-ESCs might be incompatible with therapy. Here, we report that, unexpectedly, only one gene out of 7 MEGs and 12 PEGs was differentially expressed between Pg-ESCs and Bp-ESCs while 13 were differentially expressed between androgenetic Ag-ESCs and Bp-ESCs, indicating that Pg-ESCs but not Ag-ESCs, have a Bp-like imprinting compatible with therapy. In vitro, Pg-ESCs generated cortical-like progenitors and electrophysiologically active glutamatergic neurons that maintained the Bp-like expression levels for most imprinted genes. In vivo, Pg-ESCs participated to the cortical lineage in fetal chimeras. Finally, transplanted Pg-ESC derivatives integrated into the injured adult cortex and sent axonal projections in the host brain. In conclusion, mouse Pg-ESCs generate functional cortical-like neurons with Bp-like imprinting and their derivatives properly integrate into both the embryonic cortex and the injured adult cortex. Collectively, our data support the utility of Pg-ESCs for cortical therapy. Stem Cells 2018;36:192-205.

Baicalin improves IVM of pig oocytes and subsequent preimplantation embryo development by inhibiting apoptosis.

Baicalin, a monomer of flavonoids extracted from dried roots of Scutellaria baicalensis, is used to treat female infertility. However, the effect of baicalin on oocyte maturation is unknown. In this study we investigated the effects of baicalin on the IVM of pig oocytes and subsequent embryo development following parthenogenetic activation (PA). We found that 0.1µgmL-1 baicalin significantly (P<0.05) increased the IVM rate of oocytes compared with the non-treatment (control) group by reducing levels of reactive oxygen species (ROS). In addition, the mRNA expression of genes related to nuclear maturation and cumulus cell expansion, mitochondrial membrane potential and ATP content was significantly (P<0.05) higher in baicalin-treated than control oocytes. To determine whether baicalin treatment during IVM of pig oocytes improves subsequent development of PA embryos, we measured the cleavage and blastocyst formation rates, as well as the number of cells per blastocyst. All these parameters were significantly (P<0.05) higher in the baicalin-treated than control group. In conclusion, this study demonstrates that baicalin improves pig oocyte maturation and subsequent embryo development invitro by inhibiting production of ROS and reducing apoptosis in oocytes.

Contrasting effects of heat shock during in vitro maturation on development of in vitro-fertilized and parthenogenetic bovine embryos.

This study investigated the influence of heat shock during in vitro maturation on embryo development following in vitro fertilization (IVF) or parthenogenesis (Part). Immature bovine cumulus-oocyte complexes were exposed to heat shock (41.0°C) during the first 12 hr of in vitro maturation (IVM), followed by 12 hr at 38.5°C. Control group consisted of in vitro maturation for 24 hr at 38.5°C. Oocytes were in vitro-fertilized or activated with ionomycin and cultured in vitro for 192 hr post-in vitro insemination or parthenogenetic activation (hpia). There was an interaction (p < .01) between temperature of IVM and method of oocyte activation (IVF or Part) for cleavage at 48 hpia. Heat shock had a negative impact (p < .01) on cleavage of IVF embryos, whereas no (p > .05) effect was found in the Part embryos. Embryo development towards blastocyst stage at 168 and 192 hpia decreased in both IVF and Part embryos derived from heat-shocked oocytes. Heat shock increased (p < .05) the apoptotic index in Part blastocysts, but no effect (p > .05) was found in IVF counterparts. Heat shock also down-regulated the expression of AQP3 (p < .01) and up-regulated the expression of HSP70.1 (p < .01) in Part blastocysts, whereas it down-regulated the expression of ATP1A1 (p < .05) in IVF blastocysts. In conclusion, the effects of heat shock during IVM on early embryo cleavage and blastocyst apoptosis are influenced by the method of oocyte activation and expression of some genes can be disturbed in embryos derived from heat-shocked oocytes.

Distribution and reproductive plasticity of Gyrinicola batrachiensis (Oxyuroidea: Pharyngodonidae) in tadpoles of five anuran species.

Previous studies on Gyrinicola batrachiensis indicate that these pinworms have distinct reproductive strategies dependent on the development time to metamorphosis of their anuran tadpole hosts. In tadpoles of amphibian species with short developmental periods (a few weeks), female nematodes reproduce parthenogenetically, and only produce thick-shelled eggs used as transmission agents from tadpole to tadpole. In contrast, nematodes in tadpoles with longer larval developmental periods (months to years) reproduce by haplodiploidy, and females produce thick-shelled as well as autoinfective thin-shelled eggs. However, recent investigations on the haplodiploidy strain of G. batrachiensis indicate that plasticity exists in the ability of these nematodes to produce thin-shelled autoinfective eggs when these nematodes infect tadpoles of co-occurring amphibian species. Yet, little information is available on the potential mechanism for this reproductive plasticity because few co-occurring amphibian species have been examined for the reproductive strategies of these nematodes. Therefore, our goals were to document field host specificity and reproductive strategies of nematode populations in tadpoles of five co-occurring amphibian species that varied in their larval developmental periods. Additionally, we evaluated adult worm morphology from each infected amphibian species to assess any differences in worm development and reproductive strategy of pinworm populations in different amphibian species. Of the five amphibian species examined, four were infected with the haplodiploid strain of G. batrachiensis. Prevalence of G. batrachiensis ranged from a high of 83% in Acris blandchardi to a low of 15% in Pseudacris clarkii; whereas mean intensity was highest for Rana sphenocephala (10 ± 10.36) and lowest for Hyla chrysoscelis (3.23 ± 3.35). Prevalence appeared to be controlled by tadpole ecology and life history, while mean intensity appeared to be controlled by tadpole physiology and worm reproductive strategy, but not necessarily the developmental period of each anuran species. G. batrachiensis observed in long developing tadpoles of R. sphenocephala had high mean intensities and conformed to the haplodiploidy reproductive strategy with both male and female worms being present, and females produced thick-shelled and thin-shelled eggs. In contrast, tadpoles of A. blanchardi, H. chrysoscelis, and P. clarkii, which varied in their developmental times from long to short, had relatively low mean intensities and contained both male and female G. batrachiensis. However, female worms only produced thick-shelled eggs in these hosts. Importantly, morphological differences existed among female worms recovered from R. sphenocephala and female worms recovered from A. blanchardi tadpoles with long developmental periods. These data strongly suggest that when the haplodiploidy strain of G. batrachiensis is shared by tadpoles of different amphibian species, species-specific differences in interactions between these nematodes and their development in different amphibian host species have a strong influence on the reproductive plasticity of these nematodes.

The effect of poly(ADP-ribosyl)ation inhibition on the porcine cumulus-oocyte complex during in vitro maturation.

Poly(ADP-ribosyl)ation (PARylation) plays important roles in DNA repair, apoptosis, transcriptional regulation, and cell death, and occurs via the activity of poly(ADP-ribose) polymerases (PARPs). Previous studies have shown that PARylation affects mouse and porcine pre-implantation development and participates in mechanisms of autophagy. However, there have not yet been reported the role of PARylation during in vitro maturation (IVM) of porcine oocytes. Thus, we investigated the effect of PARylation inhibition on this process; cumulus-oocyte complexes (COCs) were cultured with 3-aminobenzamide (3-ABA, PARP inhibitor) during porcine IVM. Full cumulus expansion was significantly reduced (10.34 ± 1.23 [3-ABA] vs. 48.17 ± 2.03% [control]), but nuclear maturation rates were not changed in the 3-ABA treatment group. Especially, we observed that cumulus cells were little expanded after 22 h in 3-ABA treated COCs. The mRNA expression levels of oocyte maturation- and cumulus expansion-related genes were evaluated at 22 and 44 h. GDF9, BMP15, COX-2, and PTX3 expression were upregulated at 44 h, whereas the levels of HAS2 and TNFAIP6 were downregulated in the 3-ABA treated group. Furthermore, 3-ABA treatment significantly decreased the developmental rate (28.24 ± 1.06 vs. 40.24 ± 3.03%) and total cell number (41.12 ± 2.10 vs. 50.38 ± 2.27), but increased the total apoptotic index (6.44 ± 0.81 vs. 3.08 ± 0.51) in parthenogenetically activated embryos. In conclusion, these results showed that PARylation regulates cumulus expansion through the regulation of gene expression and affects developmental competence and quality in parthenogenetic embryos.

Natriuretic peptides improve the developmental competence of in vitro cultured porcine oocytes.

BACKGROUND: Natriuretic peptides (NPs), brain and C type NPs (BNP and CNP), were involved in the maintenance of porcine oocyte meiotic arrest. The present study investigated the effects of NPs on developmental competence of immature porcine oocytes with follicles of different sizes. METHODS: Follicular fluid NP levels were examined by radioimmunoassay. The developmental competence of porcine oocytes was evaluated by cleavage and blastocyst developmental rates after in vitro fertilization (IVF) or parthenogenetic activation (PA) of cumulus oocyte complexes (COCs), which were recovered from follicle with different sizes. NP levels were examined and classified according to the cleavage potential after IVF with COCs released from these follicles. RESULTS: The BNP and CNP concentrations were increased with follicular size in follicular fluid and sustained at the set ranges of 3.0 - 6.0 mm follicles compared to 6.1 - 8.0 mm follicles. The oocytes developed from 3.0 to 6.0 mm follicles demonstrated increased embryo cleavage and blastocyst ratios after IVF, with an increased follicle size (P < 0.05). Moreover, BNP and CNP significantly promoted the blastocyst developmental rates of 3.0 - 6.0 mm follicles, but could not improve the developmental competence of oocytes from 6.1 to 8.0 mm follicles due to low NP levels. The COCs from 3.0 to 4.0 mm follicles were pre-incubated in 100 ng/ml of BNP and CNP media for 20 h before regular in vitro maturation, which demonstrated 2 to 3 folds higher developmental competencies in both PA and IVF groups compared to respective controls (P < 0.01). CONCLUSIONS: The effects of BNP and CNP supplementation in the pre-maturation culture media (PMC) on porcine developmental competence from COCs in follicles of different sizes were different and improved the developmental competence of porcine oocytes from small antral follicle in vitro.