[Eksliibris A. Kolenskile]

1 tõmmis : lito, trükitud mustaga j. 4,9 x 4,7 cm l. 5,5 x 5,3 cmNelinurkses raamistuses sarvik raamatut lugemas. Joonises all paremal signeering: АЗ all paremal: А.КОЛЕНСКіЙ keskel: E / X / L / I / B / R / I /

Involvement of K+ ATP and Ca2+ channels in hydrogen sulfide-suppressed ageing of porcine oocytes

Abstract Background Hydrogen sulfide has been shown to improve the quality of oocytes destined for in vitro fertilization. Although hydrogen sulfide is capable of modulating ion channel activity in somatic cells, the role of hydrogen sulfide in gametes and embryos remains unknown. Our observations confirmed the hypothesis that the KATP and L-type Ca2+ ion channels play roles in porcine oocyte ageing and revealed a plausible contribution of hydrogen sulfide to the modulation of ion channel activity. Results We confirmed the benefits of the activation and suppression of the KATP and L-type Ca2+ ion channels, respectively, for the preservation of oocyte quality. Conclusions Our experiments identified hydrogen sulfide as promoting the desired ion channel activity, with the capacity to protect porcine oocytes against cell death. Further experiments are needed to determine the exact mechanism of hydrogen sulfide in gametes and embryos

SIRT1-dependent modulation of methylation and acetylation of histone H3 on lysine 9 (H3K9) in the zygotic pronuclei improves porcine embryo development

Abstract Background The histone code is an established epigenetic regulator of early embryonic development in mammals. The lysine residue K9 of histone H3 (H3K9) is a prime target of SIRT1, a member of NAD+-dependent histone deacetylase family of enzymes targeting both histone and non-histone substrates. At present, little is known about SIRT1-modulation of H3K9 in zygotic pronuclei and its association with the success of preimplantation embryo development. Therefore, we evaluated the effect of SIRT1 activity on H3K9 methylation and acetylation in porcine zygotes and the significance of H3K9 modifications for early embryonic development. Results Our results show that SIRT1 activators resveratrol and BML-278 increased H3K9 methylation and suppressed H3K9 acetylation in both the paternal and maternal pronucleus. Inversely, SIRT1 inhibitors nicotinamide and sirtinol suppressed methylation and increased acetylation of pronuclear H3K9. Evaluation of early embryonic development confirmed positive effect of selective SIRT1 activation on blastocyst formation rate (5.2 ± 2.9% versus 32.9 ± 8.1% in vehicle control and BML-278 group, respectively; P ≤ 0.05). Stimulation of SIRT1 activity coincided with fluorometric signal intensity of ooplasmic ubiquitin ligase MDM2, a known substrate of SIRT1 and known limiting factor of epigenome remodeling. Conclusions We conclude that SIRT1 modulates zygotic histone code, obviously through direct deacetylation and via non-histone targets resulting in increased H3K9me3. These changes in zygotes lead to more successful pre-implantation embryonic development and, indeed, the specific SIRT1 activation due to BML-278 is beneficial for in vitro embryo production and blastocyst achievement

Dual Effects of Hydrogen Sulfide Donor on Meiosis and Cumulus Expansion of Porcine Cumulus-Oocyte Complexes

<div><p>Hydrogen sulfide (H₂S) has been revealed to be a signal molecule with second messenger action in the somatic cells of many tissues, including the reproductive tract. The aim of this study was to address how exogenous H₂S acts on the meiotic maturation of porcine oocytes, including key maturation factors such as MPF and MAPK, and cumulus expansion intensity of cumulus-oocyte complexes. We observed that the H₂S donor, Na₂S, accelerated oocyte <i>in vitro</i> maturation in a dose-dependent manner, following an increase of MPF activity around germinal vesicle breakdown. Concurrently, the H₂S donor affected cumulus expansion, monitored by hyaluronic acid production. Our results suggest that the H₂S donor influences oocyte maturation and thus also participates in the regulation of cumulus expansion. The exogenous H₂S donor apparently affects key signal pathways of oocyte maturation and cumulus expansion, resulting in faster oocyte maturation with little need of cumulus expansion.</p></div

Effect of Na₂S on meiosis resumption and transition to meiosis II in DOs.

<p>Proportion of GVBD (A) and meiosis I to II transition (B) during <i>in vitro</i> cultivation after 20 and 30 h <i>in vitro</i> cultivation, respectively. H₂S: 300 µM Na₂S. ^a,b,cStatistically significant differences among experimental groups (P<0.05).</p

Effect of Na₂S on meiotic resumption and transition to meiosis II during oocyte cultivation.

<p>Proportion of GVBD (A) and meiosis I to II transition (B) in oocytes during <i>in vitro</i> cultivation over 2 h time scale. H₂S: 300 µM Na₂S. *Statistically significant differences between control and H₂S groups (P<0.05).</p

Effect of Na₂S on HA content in expanded cumulus.

<p>(A) Total and retained HA content in COCs cultivated with 150–900 µM Na₂S for 48 hs, total HA is related to the control group. (B) Total and retained HA content in COCs during <i>in vitro</i> cultivation with 300 µM Na₂S over 12 h time scale, total HA is related to the control group after 48 h cultivation. (C) Total and retained HA content in COCs and OOXs cultivated with or without H₂S donor, total HA is related to the control group of COCs. H₂S: 300 µM Na₂S. ^a,b,cStatistically significant differences among experimental groups in total HA, ^1,2statistically significant differences among experimental groups in retained HA, *statistically significant differences in total HA between control and H₂S groups (P<0.05).</p

Effect of Na₂S on partenogenetic development of porcine oocytes.

<p>Oocytes were matured with or without Na₂S and partenogenetically activated using calcium ionophore. Pronucleus formation after 24 h zygote culture, cleavage rate after 2 days and blastocyst achievement after 7 days presumptive embryos culture were evaluated (%±SE).</p><p>H₂S: 300 µM Na₂S during oocyte maturation.</p><p>*Statistically significant differences between control and H₂S group – in column (P<0.05).</p