Density, porosity and magnetic susceptibility of the Košice meteorite shower and homogeneity of its parent meteoroid

Bulk and grain density, porosity, and magnetic susceptibility of 67 individuals of Košice H chondrite fall were measured. The mean bulk and grain densities were determined to be 3.43 g/cm3 with standard deviation (s.d.) of 0.11 g/cm3 and 3.79 g/cm3 with s.d. 0.07 g/cm3, respectively. Porosity is in the range from 4.2 to 16.1%. The logarithm of the apparent magnetic susceptibility (in 10−9 m3/kg) shows narrow distribution from 5.17 to 5.49 with mean value at 5.35 with s.d. 0.08. These results indicate that all studied Košice meteorites are of the same composition down to ∼g scale without presence of foreign (non-H) clasts and are similar to other H chondrites. Košice is thus a homogeneous meteorite fall derived from a homogenous meteoroid.Peer reviewe

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 different Na₂S concentrations on meiosis resumption and transition to meiosis II in oocytes.

<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. ^a,b,cStatistically significant differences among experimental groups (P<0.05).</p

Effect of Na₂S on MPF and MAPK activities during oocyte cultivation.

<p>Representative autoradiograms and signal quantifications of phosphorylated histone H1 (A) and MBP (B) reflecting MPF and MAPK activity, respectively. Kinase activity was measured in oocytes cultivated with or without Na₂S over 2 h time scale. The kinase activity was related to oocytes cultivated for 24 hs. C: control; 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

Hydrogen Sulfide Donor Protects Porcine Oocytes against Aging and Improves the Developmental Potential of Aged Porcine Oocytes

<div><p>Porcine oocytes that have matured in in vitro conditions undergo the process of aging during prolonged cultivation, which is manifested by spontaneous parthenogenetic activation, lysis or fragmentation of aged oocytes. This study focused on the role of hydrogen sulfide (H₂S) in the process of porcine oocyte aging. H₂S is a gaseous signaling molecule and is produced endogenously by the enzymes cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (MPST). We demonstrated that H₂S-producing enzymes are active in porcine oocytes and that a statistically significant decline in endogenous H₂S production occurs during the first day of aging. Inhibition of these enzymes accelerates signs of aging in oocytes and significantly increases the ratio of fragmented oocytes. The presence of exogenous H₂S from a donor (Na₂S.9H₂O) significantly suppressed the manifestations of aging, reversed the effects of inhibitors and resulted in the complete suppression of oocyte fragmentation. Cultivation of aging oocytes in the presence of H₂S donor positively affected their subsequent embryonic development following parthenogenetic activation. Although no unambiguous effects of exogenous H₂S on MPF and MAPK activities were detected and the intracellular mechanism underlying H₂S activity remains unclear, our study clearly demonstrates the role of H₂S in the regulation of porcine oocyte aging.</p></div