In somatic cells, the serine/threonine kinase Akt (or protein kinase B) was shown to contribute to processes linked to cellular growth, cell survival and cell cycle regulation. In contrast to these findings, the function of Akt during the meiosis of mammalian oocytes remains to be investigated. We analysed the phosphorylation pattern and the activity of Akt during meiotic maturation (transition from prophase I to metaphase II) of bovine oocytes. The oocytes were matured in vitro (IVM) for 0, 10 and 24 h to reach the germinal vesicle (GV), metaphase I (M I) and metaphase II (M II) stages respectively. The abundance and phosphorylation pattern of Akt was revealed by Western blotting using total Akt or phosphoso-Akt-specific antibodies. The activity of this particular kinase was determined by an in vitro kinase assay. Furthermore, functional properties were analysed by cultivating oocytes in the presence of the Akt inhibitor SH6. The results showed that the overall abundance of Akt did not change significantly during IVM. On the other hand, Akt became phosphorylated at Thr 308 and Ser 473, reaching its maximum at the M I phase. In the GV and M II stages, only low basal phosphorylation levels were observed on both sides. This phosphorylation profile corresponded strictly to the activity of the kinase. The cultivation of oocytes in the presence of the phosphatidylinositol analogue SH6 for 24 h showed that, with higher concentrations, up to 65% of the oocytes were arrested in the M I stage. This result indicated that Akt is involved in the M I/M II transition during the meiotic maturation of bovine oocytes. The physiological aspects of the Akt function will be discussed.
Regulation of gene expression at the translational level is particularly essential during developmental periods, when transcription is impaired. According to the closed-loop model of translational initiation, we have analyzed components of the 5 -mRNA cap-binding complex eIF4F (eIF4E, eIF4G, eIF4A), the eIF4E repressor 4E-BP1, and 3 -mRNA poly-(A) tail-associated proteins (PABP1 and 3, PAIP1 and 2, CPEB1, Maskin) during in vitro maturation of bovine oocytes and early embryonic development up to the 16-cell stage. Furthermore, we have elucidated the activity of distinct kinases which are potentially involved in their phosphorylation. Major phosphorylation of specific target sequences of PKA, PKB, PKC, CDKs, ATM/ATR, and MAPK were observed in M II stage oocytes. Furthermore, main changes in the abundance and/or phosphorylation of distinct mRNA-binding factors occur at the transition from M II stage oocytes to 2-cell embryos. In conclusion, the results indicate that, at the transition from oocyte to embryonic development, translational initiation is regulated by striking differences in the abundance and/or phosphorylation of 5 -end and 3 -end mRNA associated factors, mainly the poly-(A) bindings proteins PABP1 and 3, their repressor PAIP2 and a Maskin-like protein with distinct eIF4E-binding properties which prevents eIF4E/cap binding and eIF4F formation in vitro. Nevertheless, from the M II stage to 16-cell embryos a substantial amount of eIF4E and, to a lesser extent, of eIF4G was precipitated by (7)m-GTP-Separose indicating eIF4F complex formation. Therefore, it is likely that in general the reduction in PABP1 and 3 abundance represses overall translation during early embryonic development.
For а long time, in practice, and science, has been known that pH values of sperm and vagina are important for successful fertilization. In this investigation this fact was confirmed, and the goal was to investigate the role of pH values through whole reproductive tract of male and female individuals: testis, rete testis, epididymis, ductus deferens, Cowper's gland, vesicula seminalis, prostata, corpus cavernosus, corpus spongiosus, epitel tissue of penis tube, sperm, vagina, uterus, horn of uterus, oviduct, fimbrie ovarica, ovarium, follicular fluid. Measurement was performed in reproductive active males as well as before and after ovulation in females. Porcine reproductive tracts (per 15 female and male individuals) were collected from institute's slaughterhouse, immediately post mortem dissected, homogenised and pH values were measured (according to method Rede&Rahelić (1969)). Ovarium and follicular liquid have the highest pH values (7,4) in females, but a small peak in preovulatory oviduct is also present and corresponded to pH of sperm of reproductive fully active male individuals (pH=app.7,2). After fertilization pH in surrounding of zygot (through depolarisation of its membrane) in oviduct , and zygot which then has external decreased pH value moves to less pH values regions by the same principle, that means to uterus, (pH between 7,2 (horn) and 7,07(cervix)) in postovulatory female reproductive tract, where nidation of blastocyst occurs. This investigation could help to elucidate knowledge about reproductive physiology in vivo, giving importance to role of pH values along reproductive tract of male and female individuals.
Abstract:In this paper, results of the effect of direct and indirect selection of quantitative fertility traits of cattle end heritability level are presented. Study of the quantitative genetic parameters was carried out on three large farms of Black and White, Holstein-Friesian cattle. Investigation included 3900 first calving cows, daughters of 54 bull sires. The effect of genetic group of the head of cattle (genotype) and of the herd on fertility and milk traits of heifers and first calving cows of Black and White breed was investigated. Genetic group of the head of cattle (genotype) had no significant effect in variation of the fertility traits compared to general average (P<0.01). The effect of herd caused statistically significant and highly significant deviation from the general average, P < 0.05 and P < 0.01. Established heritability coefficients for fertility traits had low values for age at insemination (0,112), duration of pregnancy (0,045) and duration of service period (0,097). Results were obtained by applying mathematicalstatistical analysis of data -using mixed model (Harvey, 1990). Mathematical-statistical analysis of data was carried out using linear methods with fixed influence through model of Least Squares (LS method). Genotype of the head of cattle caused no significant deviation of fertility traits (P>0,05).
In the paper, lean meat and quality of meat from pigs of 5 different genotypes were investigated: pure Landrace breed (L), genotype A; two hybrid combinations (Large Yorkshire x Landrace) x Duroc (LY x L) x D, genotype B; (Large Yorkshire x Landrace) x Pietrain (LY x L) x P, genotype C; and tow recurrent mating combinations: (Large Yorkshire x Landrace) x Large Yorkshire (F1 x LY, genotype D) and (Large Yorkshire x Landrace) x Landrace (F1 x L, genotype E). Relevant indicators of lean meat were analyzed early post mortem and by method of partial dissection on cooled left carcass sides according to recommendation of EU. By analysis of obtained results it was established that the best indicator of lean meat of pig carcass sides mass of muscle tissue in four main parts. This conclusion derives from the fact that fatteners (genotype C) which had the greatest mass of muscle tissue in four main parts (15,33kg) also had the highest lean meat share in leg, shoulder, back-loin part (BLP) and belly-rib part (BRP) (69,67%, 57,71%, 54,42% and 44,99%) and highest share of muscle tissue in carcass sides when any of the mentioned investigation methods was applied (51,23 and 60,73%) compared to fatteners of other investigated genotypes. The quality of meat was investigated by determination of its technological quality and chemical composition of the MLD. Technological quality and chemical composition of MLD meat exhibited significant (*p<0,05) differences in WBC and pigment content between genotypes B and C, as well as B and E. Average values for content of ashes and share of pigments corresponds with average values characterizing muscles of normal properties. By analysis of obtained results we can conclude that fatteners of genotype E had the highest meat yield in carcass sides, but of slightly lower quality, which indicates the need for further work on improvement of meat quality.
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