Effects of uranium poisoning on cultured preimplantation embryos

The toxic effect of uranium in cultured preimplantation embryos of the mouse is presented. Embryos were obtained from hybrid females CBA×C57 BL following induction of superovulation and were incubated in M16 cultured medium. Two different experiments were performed. In one, embryos in a one-cell stage were placed in culture media with final concentrations of uranyl nitrate of 104 and 208 μg/mL during 120 h in the same dish. In the other experiment, embryos in a one-cell stage were placed in culture medium with uranyl nitrate with final U concentrations of 26, 52, 104, and 208 μg/mL. At 24 h, those embryos which had reached the two-cell stage were transferred to another culture dish to which fresh solutions with uranyl nitrate were added. The percentage of embryos in two-cell stage, morula, early blastocyst, expanded blastocyst, and hatched blastocyst were recorded at 24, 72, 96 and 120 h of culture. The results obtained showed that concentrations as from 26 μg U/mL induced the delay of embryo development and the impairment of blastomere proliferation. The toxic effect of uranium increased in those experiments in which the embryos were transferred to a new medium. This embryo-culture system appears to be appropriate to evaluate the toxic effect of uranium on embryos removed from maternal influences and represents a suitable test system for environmental pollutants.     

Effects of mating rate and delayed mating on the fecundity of Adoxophyes orana

Females of Adoxophyes orana F. v. R. (Lepidoptera: Tortricidae) could mate after one day, or after up to 7 days, after eclosion. It was recorded how many eggs per female were laid, had been fertilized and ultimately hatched. Mating rate was assessed by counting the spermatophores in a female.Egg production did not depend on mating rate, but proportion fertilization of eggs from females with three or more spermatophores was reduced. Delayed mating promoted longevity and changed the pattern of oviposition in time. No correlation was found between the proportion hatching of fertilized eggs and any of the other variables in the experiments.The data were introduced into a population model to compute the relation between fecundity and probability to mate.

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Effets du nombre d'accouplements et du retard de la date du premier accouplement sur la fécondité de Adoxophyes orana

Résumé Des femelles de A. orana F. v. R. (Lep., Tortricid.) ont eu la possibilité de s'accoupler le lendemain de leur émergence. Nous avons dénombré l'effectif d'oeufs pondus par chaque femelle, et calculé leur taux de fertilisation et d'éclosion. Les femelles ont été disséquées et les spermatophores comptés pour déterminer le nombre de copulations. La même procédure a été suivie avec d'autres femelles qui ont pu copuler librement jusquà leur mort, (leur longévité a été notée), mais avec une date du premier accouplement pouvant être retardée jusqu'à 6 jours après l'émergence.La production d'oeufs ne dépend pas du nombre de copulations, mais le taux de fertilisation des femelles avec 3 ou 4 spermatophores a été plus faible. Le retard de la date du premier accouplement augmente la longévité, mais réduit légérement le taux de fertilisation. La production d'oeufs était à peu près proportionnelle à la durée de la vie décomptée à partir du moment où la copulation était possible. Aucune corrélation n'a été mise en évidence entre la taux d'éclosion des oeufs fertilisés et les variables de l'habitat.Pour évaluer ces résultats et obtenir plus de connaissances sur les conséquences des copulations retardées, par exemple provenant de procédures d'interruption des copulations, les données ont été introduites successivement dans un modèle de populations pour établir la relations entre fécondité et probabilité d'accouplement.

     

Effects of non-24-hour days on reproductive efficacy and embryonic development in mice

ICR female mice were exposed to either 22 (L11, D11) or 26 hour day (L13, D13) light/dark cycles for at least 2 weeks before mating and/or during pregnancy. The mating rates of these animals decreased considerably. When pregnant females were examined at gestation days 12.0 or 17.5, resorption rates were increased, the embryos weighed less, and development was retarded in the experimental groups with preconceptional exposure to non-24-hour days. We speculate that in mice maternal and paternal pre- and periconceptional environment of daily light/dark cycles is important for normal reproductive efficacy and normal embryonic development during pregnancy.     

Lectin-induced blockage of developmental processes in preimplantation mouse embryos in vitro

This study attempts to assess the developmental importance of cell surface glycoconjugates of preimplantation mouse embryos. This was done by incubating early embryos in various lectins and analyzing subsequent development. If specific cell surface glycoconjugates (lectin receptors) are linked to specific developmental processes, such as cell division, compaction, and blastocyst formation, then different lectins should block these different developmental processes. The results show that wheat-germ agglutinin (WGA; N-acetyl-D-glucosamine-specific) at 50 μg/ml prevents the cell division of four-cell embryos. However, this effect of WGA occurs only in embryos with intact zonae pellucidae. Concanavalin A (Con A; α-D-glucose and α-D-mannose-specific) treatment, 20 μg/ml, of four-cell or early eight-cell embryos prevents compaction, the first major change in cell shape in early mouse embryogenesis. Divalent succinly Con A does not affect development, suggesting that the Con A effect is due to crosslinking of cell surface glycoconjugates. Exposure of four-cell or early eight-cell embryos to 10 μg/ml Lotus Tetragonolobus puprureas agglutinin (LTA; α-L-fucose-specific) or 25 μg/ml Limulus polyphemus agglutinin (LPA; sialic acid-specific) allows compaction or development to the morula stage, but blocks blastocyst formation. All lectins tested retard cell division to some extent. Late morulae and early blastocysts are more resistant than earlier stages to all of the lectins studied. This study demonstrates that very low concentrations of these lectins affect different developmental processes, presumably based upon their sugar specificities.     

Effects of heat shock on in vitro development and intracellular oxidative state of bovine preimplantation embryos

We investigated the effects of heat shock on developmental competence of bovine embryos and intracellular oxidative state. After in vitro fertilization, embryos were exposed to heat shock at 41 degrees C for 6 hr on days 0, 2, 4, and 6, respectively. On day 2, cleavage rate was not significantly different in all groups. However, the percentage of embryos developing to blastocyst stage after exposure to heat shock on day 0 (18.8 +/- 4.3%) and day 2 (23.6 +/- 3.7%) were significantly decreased compared with control (37.5 +/- 4.0%), day 4 (40.0 +/- 7.4%), and day 6 (38.1 +/- 2.0%). In addition, the total cell number of blastocysts was significantly decreased by heat shock on day 0 (107.5 +/- 6.6) and day 2 (112.8 +/- 5.7) compared with the control (143.2 +/- 9.4). To evaluate intracellular oxidative state by heat shock, embryos exposed to heat shock on days 0, 2, 4, and 6 were incubated with 2',7'-dichlorodihydrofluorescein diacetate (DCHFDA) and fluorescence of oxidized DCHFDA by reactive oxygen species (ROS) was detected under fluorescent microscope. The intensity of fluorescence was significantly increased when embryos were exposed to heat shock on days 0 and 2. However, heat shock on day 4 and day 6 did not increase the fluorescence intensity. These results indicate that (1) heat shock to earlier stage embryos causes a decrease in development to blastocysts and cell proliferation and (2) the decrease in development by heat shock could be involved in an increase of intracellular oxidative stress. Mol. Reprod. Dev. 67: 77-82, 2004.     

豆野螟延迟交尾和多次交尾对生殖的影响

豆野螟Maruca vitrata(Fabricius)是一种严重的泛热带豆类蔬菜害虫。本文研究了豆野螟延迟交尾和多次交尾对其生殖的影响。延迟交尾实验结果表明:豆野螟雌雄同时延迟交尾,雌雄虫的寿命、产卵量均表现为先上升后下降的趋势,但是对卵的孵化率没有显著影响;雌虫延迟交尾,随着延迟时间的增加,雌虫的寿命、产卵量、卵的孵化率表现为下降的趋势,而雄虫的寿命延迟交尾第3天达到最大值;雄虫延迟交尾,随着延迟交尾时间的增加,雌雄虫的寿命、产卵量均表现为先上升后下降的趋势,卵的孵化率随着延迟逐渐下降。多次交尾实验结果表明,随着雄虫交尾次数的增加,成功交尾率逐渐降低,用于交尾的时间延长,雌虫和相应雄虫的寿命逐渐缩短,雌虫的产卵量下降,但对卵的孵化率影响不大;豆野螟雌虫一生只交尾一次,未见到雌虫2次交尾。     

Effects of delayed mating on reproductive output of female oriental beetle Anomala orientalis (Coleoptera: Scarabaeidae)

1 Although management of the oriental beetle Anomala orientalis (Waterhouse) by mating disruption shows promise across a range of agricultural systems, relatively little is known about aspects of the reproductive biology of this species relevant to its management. We studied the effects of delayed mating on several aspects of the oviposition behaviour and biology of the oriental beetle using females mated in the laboratory at 4–13 days posteclosion. 2 Females exhibited a gradual decline in fecundity with increased age at mating that was largely a function of a decline in duration of the oviposition period, as well as lower female fertility: females mated at 11 days were less likely to lay any fertile eggs. However, egg fertility did not vary with female age at mating. 3 Because mating delay did not affect longevity, females mated at older ages experienced decreased oviposition periods; however, females laid more eggs per day with increased age at mating, which partially offset shorter oviposition periods. 4 A mating delay of ≥ 6 days relative to females mated within the first day of reaching sexual maturity resulted in an approximately 35–50% lower mean fecundity. 5 These results suggest that, for mating disruption to be a successful management tool for the oriental beetle, mating must be prevented rather than delayed. We compare the findings of the present study with the published research on delayed mating in moths and discuss the importance of these results in relation to management of the oriental beetle using female sex pheromones.     

Lack of effect of 2.45-GHz microwave radiation on the development of preimplantation embryos of mice

The development of preimplantation embryos after exposure to microwave radiation was studied. Female CD-1 mice were induced to superovulate, mated, and exposed to 2.45-GHz microwave or sham radiation for 3 h at power densities of 9 mW/cm² and 19 mW/cm² on either day 2 or 3 of pregnancy (plug day was considered day 1). Another group of mice was exposed to heat stress by placing the dams in an environmental room at an ambient temperature of 38 °C and relative humidity at 62% for 3 h on day 2 of pregnancy. All groups were euthanized on day 4 of pregnancy and embryos were recovered by flushing excised uterine horns. Embryos were examined for abnormalities and classified by the developmental stages. They were then treated with hypotonic solution and dissociated for counting blastomeres. Heat stress caused stunted development of embryos, but no remarkable effect of microwave radiation could be found on the development of preimplantation embryos.     

生殖细胞及早期胚胎基因组印记的表观调控

基因组印记是一种区别父母等位基因的表观遗传过程,可导致父源和母源基因特异性表达。印记是在配子发生过程中全基因组表观重编程时获得的,且在早期胚胎发育过程中得以维持。因此,在全基因组重编程过程中,对印记的识别和维持十分重要。本文概述了原始生殖细胞的印记清除、双亲原始生殖细胞的印记获得以及早期胚胎发育过程中印记维持的相关过程,并对在印记区域内保护印记基因免受全基因组DNA去甲基化的表观遗传因子的相关作用机制进行了讨论。     

Effects of delayed mating and male mating history on the reproductive potential of Leucoptera coffeella (Lepidoptera: Lyonetiidae)

Abstract 1 Despite the importance of Leucoptera coffeella (Guérin‐Mèneville) in coffee production worldwide, there is a lack of information on its reproduction. This knowledge will help in mass rearing, and support the development of behavioural control techniques for this insect. The present study determined the effects of delayed mating and previous matings of male L. coffeella on fecundity, egg viability and frequency of female remating. 2 The highest levels of fecundity and egg viability were obtained from matings of 1–3‐day‐old females. When females mated at 5 days of age, there were reductions of 40% in oviposition and of 43% in egg viability. 3 Females mated with 2‐day‐old virgin males were more fecund than those mated with older males; egg viability was also low (18%) from females mated with older males. 4 Virgin females that mated with virgin males laid a greater number of eggs than those mated with previously copulated males. Egg viability decreased with the increase in the number of previous male matings. 5 Five‐day‐old females remated in greater proportion than 2–3‐day‐old females. Females that copulated with males that had previously mated three times had higher rates of remating than those that copulated with virgin males. 6 The results obtained indicate that 1–3 days after emergence is the optimum age for mating. The implications of these findings for the control of L. coffeella by synthetic sex pheromone are discussed.     

Effects of delayed mating and male mating history on longevity and reproductive performance of the rice stem borer, Chilo suppressalis (Walker) (Lep., Pyralidae)

Abstract:  The mating potential, effects of delayed mating and male mating history on longevity and reproductive performance of female rice stem borer (RSB), Chilo suppressalis , were investigated under laboratory conditions. Given the opportunity, RSB males copulated an average of 2.7 times, while females generally mated only once. Females were more severely affected by mating delay than males in terms of female longevity and reproductive performance. With increasing age at mating, females' longevity increased, while oviposition period, fecundity and egg fertility decreased. Mean fecundity and egg fertility of females mated 1 and 7 days after emergence were 251.3% and 99.2%, and 96.2% and 75.5% respectively. Both were reduced significantly when female mating was delayed beyond 4 days after emergence. However, irrespective of the first mating age and different mating history of the males, the results indicated that both did not result in a significant difference in the quality of their contributions to female longevity and reproductive performance. The results obtained in this study are discussed in relation to the potential effect on pheromone control of RSB.     

Identification of genes showing altered expression in preimplantation and early postimplantation parthenogenetic embryos

Uniparental embryos have been instrumental in studying imprinting because contributions from the parental genomes can be determined unambiguously. In this study, we set out to identify imprinted genes showing differential expression between parthenogenetic and fertilized embryos during preimplantation and early postimplantation stages of development. We identified three genes-apolipoprotein E, pyruvate kinase-3, and protein phosphatase 1 gamma-that represent excellent candidates for imprinted genes, based on the results of the differential screen, their function in differentiation and the cell cycle, and their location within imprinted chromosomal regions. In addition, two novel genes expressed in trophoblast were identified, 1661 and RA81. These genes, together with four known imprinted genes, H19, Igf2r, Igf2, and Snrpn, showed evidence of expression from both parental alleles in early stage embryos, indicating a role for postfertilization processes in regulating imprinted gene function. © 1995 Wiley-Liss, Inc.     

Increased survival of preimplantation mouse embryos in medium with recombinant cytokine LIF

We studied the effects of cytokine LIF on in vitro development of 2-cell mouse embryos to the late blastocyst stage. LIF at 10 ng/ml enhanced the blastocyst formation and hatching from zona pellucida. When blastocysts were cultivated in a medium with LIF for a longer time, the trophoblast adhesive properties and proliferative activity were enhanced. In the presence of this cytokine, the trophoblast cells were attached to the substrate surface and fulfill the function of a sublayer for growth of the inner cell mass colonies with a high activity of endogenous alkaline phosphatase. Expression of LIF was detected in the oviduct and uterus epithelial tissues from day 1 until day 4 of pregnancy, thus suggesting its involvement in early development. According to the data of cultivation, cytokine LIF enhanced the adhesive properties and functional activity of the trophoblast cells, which is essential for implantation of blastocysts in the uterus.     

延迟交配对昆虫生殖行为的影响以及与性信息素防治害虫的关系

对鳞翅目昆虫延迟交配对昆虫生殖力、卵孵化率、交配成功率、成虫寿命等进行了总结。雌虫延迟交配降低雌虫的生殖力、卵的孵化率及与雄虫成功交配率,但可以延长雌虫寿命。雄虫延迟交配降低雌虫的生殖力、卵的孵化率、产卵时间,雄虫的精子质量下降但寿命有所增加。已发现延迟交配在迷向法中控制害虫起着重要的作用,对进一步认识迷向法中不同作用机理以及延迟交配在迷向法防治害虫中的潜力进行了探讨。