Dispositional Optimism and Marital Adjustment

This project examined dispositional optimism and its influence on the three subscales of marital adjustment (consensus, satisfaction, and cohesion) by gender. Data for this study came from Wave 2 and 3 of the National Survey of Families and Households. The Actor Partner Interdependence Model (APIM) was used to examine both actor and partner effects of dispositional optimism on the marital adjustment subscales using the program AMOS. Results indicate that wives’ optimism seem to influence their own later marital satisfaction as well as their husbands’ later marital satisfaction. However, husbands’ optimism appeared to influence neither their own nor their wives’ later satisfaction. These results imply that wives’ optimism matters for marital satisfaction, whereas husbands’ does not

STIM1 is required for Ca2+ signaling during mammalian fertilization

AbstractDuring fertilization in mammals, a series of oscillations in the oocyte's intracellular free Ca2+ concentration is responsible for oocyte activation and stimulation of embryonic development. The oscillations are associated with influx of Ca2+ across the plasma membrane that is probably triggered by the depletion of the intracellular stores, a mechanism known as store-operated Ca2+ entry. Recently, STIM1 has been identified in oocytes as a key component of the machinery that generates the Ca2+ influx after store depletion. In this study, the involvement of STIM1 in the sperm-induced Ca2+ oscillations and its significance in supporting subsequent embryo development were investigated. Downregulation of STIM1 levels in pig oocytes by siRNA completely inhibited the repetitive Ca2+ signal triggered by the fertilizing sperm. In addition, a significantly lower percentage of oocytes cleaved or formed blastocysts when STIM1 was downregulated prior to fertilization compared to the control groups. Restoring STIM1 levels after fertilization in such oocytes by means of mRNA injection could not rescue embryonic development that in most cases was arrested at the 2-cell stage. On the other hand, STIM1 overexpression prior to fertilization did not alter the pattern of sperm-induced Ca2+ oscillations and development of these fertilized oocytes up to the blastocyst stage was also similar to that registered in the control group. Finally, downregulation of STIM1 had no effect on oocyte activation when activation was stimulated artificially by inducing a single large elevation in the oocyte's intracellular free Ca2+ concentration. These findings suggest that STIM1 is essential for normal fertilization as it is involved in the maintenance of the long-lasting repetitive Ca2+ signal

Analysis of cat oocyte activation methods for the generation of feline disease models by nuclear transfer

Background Somatic cell nuclear transfer in cats offers a useful tool for the generation of valuable research models. However, low birth rates after nuclear transfer hamper exploitation of the full potential of the technology. Poor embryo development after activation of the reconstructed oocytes seems to be responsible, at least in part, for the low efficiency. The objective of this study was to characterize the response of cat oocytes to various stimuli in order to fine-tune existing and possibly develop new activation methods for the generation of cat disease models by somatic cell nuclear transfer. Methods First, changes in the intracellular free calcium concentration [Ca2+]i in the oocytes induced by a number of artificial stimuli were characterized. The stimuli included electroporation, ethanol, ionomycin, thimerosal, strontium-chloride and sodium (Na+)-free medium. The potential of the most promising treatments (with or without subsequent incubation in the presence of cycloheximide and cytochalasin B) to stimulate oocyte activation and support development of the resultant parthenogenetic embryos was then evaluated. Finally, the most effective methods were selected to activate oocytes reconstructed during nuclear transfer with fibroblasts from mucopolysaccharidosis I- and alpha-mannosidosis-affected cats. Results All treatments were able to elicit a [Ca2+]i elevation in the ooplasm with various characteristics. Pronuclear formation and development up to the blastocyst stage was most efficiently triggered by electroporation (60.5 +/- 2.9 and 11.5 +/- 1.7%) and the combined thimerosal/DTT treatment (67.7 +/- 1.8 and 10.6 +/- 1.9%); incubation of the stimulated oocytes with cycloheximide and cytochalasin B had a positive effect on embryo development. When these two methods were used to activate oocytes reconstructed during nuclear transfer, up to 84.9% of the reconstructed oocytes cleaved. When the 2 to 4-cell embryos (a total of 220) were transferred into 19 recipient females, 4 animals became pregnant. All of the fetuses developed from oocytes activated by electroporation followed by cycloheximide and cytochalasin B incubation; no fetal development was detected as a result of thimerosal/DTT activation. Although heartbeats were detected in two of the cloned fetuses, no term development occurred. Conclusion Electroporation proved to be the most effective method for the activation of cat oocytes reconstructed by nuclear transfer. The combined thimerosal/DTT treatment followed by cycloheximide and cytochalasin B incubation triggered development effectively to the blastocyst stage; whether it is a viable option to stimulate term development of cloned cat embryos needs further investigations

The dynamics of MAPK inactivation at fertilization in mouse eggs

Egg activation at fertilization in mammals is initiated by prolonged Ca2+ oscillations that trigger the completion of meiosis and formation of pronuclei. A fall in mitogen-activated protein kinase (MAPK) activity is essential for pronuclear formation, but the precise timing and mechanism of decline are unknown. Here, we have measured the dynamics of MAPK pathway inactivation during fertilization of mouse eggs using novel chemiluminescent MAPK activity reporters. This reveals that the MAPK activity decrease begins during the Ca2+ oscillations, but MAPK does not completely inactivate until after pronuclear formation. The MAPKs present in eggs are Mos, MAP2K1 and MAP2K2 (MEK1 and MEK2, respectively) and MAPK3 and MAPK1 (ERK1 and ERK2, respectively). Notably, the MAPK activity decline at fertilization is not explained by upstream destruction of Mos, because a decrease in the signal from a Mos–luciferase reporter is not associated with egg activation. Furthermore, Mos overexpression does not affect the timing of MAPK inactivation or pronuclear formation. However, the late decrease in MAPK could be rapidly reversed by the protein phosphatase inhibitor, okadaic acid. These data suggest that the completion of meiosis in mouse zygotes is driven by an increased phosphatase activity and not by a decline in Mos levels or MEK activity

Transmission of mitochondrial DNA following assisted reproduction and nuclear transfer

Review of the articleMitochondria are the organelles responsible for producing the majority of a cell's ATP and also play an essential role in gamete maturation and embryo development. ATP production within the mitochondria is dependent on proteins encoded by both the nuclear and the mitochondrial genomes, therefore co-ordination between the two genomes is vital for cell survival. To assist with this co-ordination, cells normally contain only one type of mitochondrial DNA (mtDNA) termed homoplasmy. Occasionally, however, two or more types of mtDNA are present termed heteroplasmy. This can result from a combination of mutant and wild-type mtDNA molecules or from a combination of wild-type mtDNA variants. As heteroplasmy can result in mitochondrial disease, various mechanisms exist in the natural fertilization process to ensure the maternal-only transmission of mtDNA and the maintenance of homoplasmy in future generations. However, there is now an increasing use of invasive oocyte reconstruction protocols, which tend to bypass mechanisms for the maintenance of homoplasmy, potentially resulting in the transmission of either form of mtDNA heteroplasmy. Indeed, heteroplasmy caused by combinations of wild-type variants has been reported following cytoplasmic transfer (CT) in the human and following nuclear transfer (NT) in various animal species. Other techniques, such as germinal vesicle transfer and pronuclei transfer, have been proposed as methods of preventing transmission of mitochondrial diseases to future generations. However, resulting embryos and offspring may contain mtDNA heteroplasmy, which itself could result in mitochondrial disease. It is therefore essential that uniparental transmission of mtDNA is ensured before these techniques are used therapeutically

Production and manipulation of bovine embryos : techniques and terminology

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