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ABSTRACT: We examined the stomach contents of 26 Baird's beaked whales caught off the coast of Japan by small-type coastal whalers. The main prey for these whales was rat-tails and hakes in the western North Pacific. Pollock and squids were also important food in the whales collected from the southern Sea of Okhotsk. The prey species found in the stomachs of the whales were almost identical to those caught in bottom-trawl nets at depths greater than about 1000 m in the western North Pacific, which suggests that the Baird's beaked whale forages for prey at depths of about 1000 m or more. Baird's beaked whales in the western North Pacific migrate to waters of 1000–3000 m in depth, where demersal fish are abundant. This implies that Baird's beaked whales migrate to waters where demersal fish, especially rat-tails and hakes, are abundant. Although there is limited information on the feeding habits of ziphiid whales, they are generally thought to prefer squid. The present data suggest that demersal fish are also important prey for ziphiid whales. 相似文献
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ABSTRACT: Sequence variability of the control region of mitochondrial DNA in five Sebastes species ( S. thompsoni , S. joyneri , S. inermis , S. schlegeli and S. owstoni ) was investigated. Of 324 nucleotide sites in the control region of S. thompsoni , 56 sites (17.3%) varied, and all 20 individuals had different haplotypes. The other four species had between five and 17 sites (1.5–5.9%), which was fewer than that observed in S. thompsoni . The nucleotide diversity of S. thompsoni was highest (3.45%) among the five species, and that of S. schlegeli was the lowest (0.19%). The results demonstrated that sequence variability exists in the control region of the five Sebastes fishes investigated, and that sequence data in the control region may be suitable for stock structure analysis. Also, the extent of genetic variablitiy in the control region differed among these species. In particular, the mitochondrial DNA control region in S. thompsoni was characterized by high sequence variability, which may indicate a large effective population size. 相似文献
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Takako Yazaki Yuki Hiradate Yumi Hoshino Kentaro Tanemura Eimei Sato 《Animal Science Journal》2013,84(5):395-402
We investigated the effect of oxidative stress induced by hydrogen peroxide (H2O2) on lipid peroxide (LPO) level and nuclear maturation in porcine oocytes cultured with or without cumulus cells. After 22 h of pre‐culture, oocytes with attached cumulus cells (COC group) or denuded oocytes (DO group) were cultured with H2O2, and intra‐oocyte H2O2 and LPO levels were quantitatively analyzed using immunofluorescence. This is the first report evaluating LPO levels in porcine oocytes. After H2O2 supplementation, the DO group showed severe accumulation of H2O2 and LPO in the oocytes. Similarly, while inhibition of progression of nuclear maturation was observed in both groups, the effect was more severe in the DO group. These results demonstrate that cumulus cells reduce the accumulation of H2O2 stress in oocytes. Furthermore, we attempted to reduce the oxidative stress by H2O2 with L‐carnitine, a H2O2 scavenger. L‐carnitine decreased H2O2 and LPO levels in the oocytes in both groups, and improvement in the progression of impaired nuclear maturation was observed. These effects were different by the presence of cumulus cells. Our results provide that L‐carnitine is useful for alleviating H2O2‐induced oxidative stress by reducing LPO levels and improving the progression of nuclear maturation. 相似文献
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