Yo Suzuki

Obihiro University of Agriculture and Veterinary Medicine, Obibiro, Hokkaido, Japan

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Publications (4)6.06 Total impact

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    ABSTRACT: The aim of this study was to investigate whether seasonal changes affected in vitro developmental competence of porcine oocytes. The relationship between atmospheric temperature and embryonic development of in vitro matured porcine oocytes following intracytoplasmic sperm injection was examined throughout the year. The blastocyst rate (31.1%) in winter (mean atmospheric temperature during December to February: -3.8 C) was significantly higher (P<0.05) than those of other seasons in 2008/2009 (19.7-23.5%; 6.3-17.5 C). The monthly mean blastocyst rates were negatively correlated with the temperatures (r=-0.5944, P<0.05). The results of the present study suggest that porcine embryos could be produced throughout the year, but the in vitro production efficiency was significantly affected by season, i.e., atmospheric temperatures. Furthermore, the results showed that winter is a favorable season for blastocyst production in the region of Obihiro, Hokkaido, Japan.
    Full-text · Article · Aug 2010 · Journal of Reproduction and Development

  • No preview · Article · Jan 2010 · Journal of Reproduction and Development
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    ABSTRACT: The objectives of this study were to choose an effective embryo reconstruction method and an effective post-activation agent for in vitro production of sei whale (Balaenoptera borealis) interspecies somatic cell nuclear transfer (iSCNT) embryos. Moreover, trichostatin A (TSA) treatment of whale iSCNT embryos was performed to improve the in vitro embryo development. In Experiment 1, the fusion rate was significantly higher (88.1%) in embryos reconstructed using the intracytoplasmic cell injection method (ICI) than that (48.7%) in the subzonal cell insertion (SUZI) counterpart. The rates of pseudopronucleus (PPN) formation (77.4 vs. 77.2%) and cleavage (24.5 vs. 37.0%) did not vary between ICI and SUZI. However, the PPN formation and cleavage rates were significantly (P<0.05) lower in the iSCNT embryos than in the parthenogenetic control (95.7% and 64.4%, respectively). Although 21.5% of the bovine parthenogenetic embryos developed to the blastocyst stage, no iSCNT embryo developed beyond the 6-cell stage. In Experiment 2, the cleavage rate did not vary between the TSA (50 nM)-treated and non-treated whale iSCNT embryos (30.5 vs. 32.3%, respectively). Moreover, it did not vary between the TSA-treated iSCNT and SCNT embryos (30.5 vs. 32.0%, respectively). Only one TSA non-treated iSCNT embryo developed to a compacted morula with 20 nuclei. One TSA-treated whale SCNT embryo developed to the 8-cell stage, and out of five whale iSCNT embryos, a 6-cell stage embryo was positive for whale DNA. In conclusion, bovine oocytes have the ability to support development of sei whale nuclei up to the 6-cell stage.
    Full-text · Article · Nov 2009 · Journal of Reproduction and Development
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    ABSTRACT: The present study investigated effects of three semen extenders and storage temperatures on post-thaw characteristics of Bryde's whale spermatozoa. Spermatozoa were collected from the vasa deferens of three mature Bryde's whales captured during the Japanese whale research in the north-west Pacific (May to August 2007) after death. The three semen extenders used for freezing were 1) a commercialized synthetic extender (AndroMed: AM), 2) Tris-based + 10% bovine serum albumin (BSA) and 3) Tris-based + egg yolk (EY). The sperm samples from the three whales were frozen with the three extenders, and the post-thaw spermatozoa were stored at three different temperatures (35 C; 20-25 C, room temperature; and 5 C) for 0, 6, 12, 24, 48 and 96 h. At each time-point, total and progressive motility (PM), viability (live or dead), the hypo-osmotic test, defective acrosomes and malformation were examined. Immediately after thawing, AM resulted in similar recovery rates (60.4 and 83.3%) in 2 of the 3 whales examined and had comparable post-thaw recovery rates to those obtained using the EY and BSA extenders. Immediately after thawing, the proportion of PM in EY (17.6%) was higher (P<0.05) than that in BSA (15.0%). In the hypo-osmotic test, the proportions of AM (26.0%) and BSA (25.2%) were higher (P<0.05) than that of EY (17.3 %). The three extenders had similar viabilities (36.7, 37.9 and 32.1%, respectively), but the viability of BSA was higher (P<0.05) than that of EY. The present study showed that a synthetic semen extender, AndroMed, could be used for cryopreservation of whale spermatozoa in addition to Tris-based extenders containing bovine serum albumin or egg yolk. Storage of the post-thaw Bryde's whale spermatozoa was better at 5 C than at room temperature or 35 C. The frozen-thawed Bryde's whale spermatozoa maintained their motility and viability for at least two days at room temperature and for four days at 5 C.
    No preview · Article · Sep 2009 · Journal of Reproduction and Development