Multiple aster formation is frequently observed in bovine oocytes retrieved from 1 day-stored ovaries

We have recently reported that multiple aster formation after IVF was one of the factors negatively affecting to developmental competence of vitrified-warmed bovine matured oocytes, and that a short-term culture of the post-warm oocytes with an inhibitor of Rho-associated coiled-coil kinase (ROCK) suppressed the multiple aster formation and improved the blastocyst yield. The present study was conducted to investigate whether increased multiple aster formation following IVF can be involved in impaired developmental competence of stored ovary-derived bovine oocytes. Oocytes retrieved from 1-day stored ovaries had lower developmental potential to Day 8 blastocysts when compared with those from fresh ovaries (37 vs 63%). Immunostaining against -tubulin 10 h post-IVF revealed that the higher incidence of multiple aster formation occurred in oocytes retrieved from stored ovaries than fresh ovaries (31 vs 15%). Treatment of post-IVM oocytes with ROCK inhibitor for 2 h significantly suppressed the incidence of multiple aster formation (10 vs 32% in control group). However, the suppressing effect of ROCK inhibitor on multiple aster formation in IVM/IVF oocytes did not improve blastocyst yield from stored ovary-derived oocytes (41 vs 37% in control group). These results suggest that higher incidence of multiple aster formation by bovine ovary storage was not responsible for decreased developmental competence of IVF oocytes.ArticleZYGOTE.24(1):115-120(2015)journal articl

The Nevados de Payachata volcanic region (18°S/69°W, N. Chile)

Subduction-related volcanism in the Nevados de Payachata region of the Central Andes at 18°S comprises two temporally and geochemically distinct phases. An older period of magmatism is represented by glaciated stratocones and ignimbrite sheets of late Miocene age. The Pleistocene to Recent phase (≤0.3 Ma) includes the twin stratovolcanoes Volcan Pomerape and Volcan Parinacota (the Nevados de Payachata volcanic group) and two small centers to the west (i. e., Caquena and Vilacollo). Both stratovolcanoes consist of an older dome-and-flow series capped by an andesitic cone. The younger cone, i. e., V. Parinacota, suffered a postglacial cone collapse producing a widespread debris-avalanche deposit. Subsequently, the cone reformed during a brief, second volcanic episode. A number of small, relatively mafic, satellitic cinder cones and associated flows were produced during the most recent activity at V. Parinacota. At the older cone, i. e., V. Pomerape, an early dome sequence with an overlying isolated mafic spatter cone and the cone-forming andesitic-dacitic phase (mostly flows) have been recognized. The two Nevados de Payachata stratovolcanoes display continuous major- and trace-element trends from high-K 2 O basaltic andesites through rhyolites (53%–76% SiO 2 ) that are well defined and distinct from those of the older volcanic centers. Petrography, chemical composition, and eruptive styles at V. Parinacota differ between pre- and post-debris-avalanche lavas. Precollapse flows have abundant amphibole (at SiO 2 > 59 wt%) and lower Mg numbers than postcollapse lavas, which are generally less silicic and more restricted in composition. Compositional variations indicate that the magmas of the Nevados de Payachata volcanic group evolved through a combination of fractional crystallization, crustal assimilation, and intratrend magma mixing. Isotope compositions exhibit only minor variations. Pb-isotope ratios are relatively low ( 206 Pb/ 204 Pb = 17.95–18.20 and 208 Pb/ 204 Pb = 38.2–38.5); 87 Sr/ 86 Sr ratios range 0.70612–0.70707, 143 Nd/ 144 Nd ratios range 0.51238–0.51230, and γ 18 O SMOW values range from + 6.8% o to + 7.6% o SMOW. A comparison with other Central Volcanic Zone centers shows that the Nevados de Payachata magmas are unusually rich in Ba (up to 1800 ppm) and Sr (up to 1700 ppm) and thus represent an unusual chemical signature in the Andean arc. These chemical and isotope variations suggest a complex petrogenetic evolution involving at least three distinct components. Primary mantle-derived melts, which are similar to those generated by subduction processes throughout the Andean arc, are modified by deep crustal interactions to produce magmas that are parental to those erupted at the surface. These magmas subsequently evolve at shallower levels through assimilation-crystallization processes involving upper crust and intratrend magma mixing which in both cases were restricted to end members of low isotopic contrast.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47805/1/445_2005_Article_BF01073587.pd