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Contribution of spermatozoal centrosomes to the microtubule-organizing centre in Antarctic minke whale (Balaenoptera bonaerensis)

Published online by Cambridge University Press:  24 March 2006

Toshihiro Kobayashi
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
Kazue Amemiya
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
Kana Takeuchi
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
Tomomi Tsujioka
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.
Keiichiro Tominaga
Affiliation:
Hyogo Prefectural Institute for Agriculture, Forestry and Fisheries, Kasai, Hyogo 679-0198, Japan.
Masumi Hirabayashi
Affiliation:
National Institute for Physiological Sciences, Okazaki, Aichi 444-8787, Japan.
Hajime Ishikawa
Affiliation:
The Institute of Cetacean Research, Chuo-ku, Tokyo 104-0055, Japan.
Yutaka Fukui
Affiliation:
Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
Shinichi Hochi
Affiliation:
Faculty of Textile Science and Technology, Shinshu University, Ueda, Nagano 386-8567, Japan.

Abstract

Using an interspecies microinsemination assay with bovine oocytes, it was examined whether centrosomes of Antarctic minke whale spermatozoa function as the microtubule-organizing centre (MTOC). Bull and rat spermatozoa were used as positive and negative controls, respectively. Vitrified-warmed bovine mature oocytes were subjected to immunostaining against α-tubulin 4–6 h after intracytoplasmic injection (ICSI) of 5 mM dithiothreitol-treated spermatozoa. Aster formation occurred from whale spermatozoa (33%) and bull spermatozoa (33%), but very little from rat spermatozoa (3%). Activation treatment for the microinseminated oocytes with 7% ethanol + 2 mM 6-dimethylaminopurine resulted in a similar proportion of oocytes forming a whale sperm aster (35% vs 27% in the non-treated group; 4 h after ICSI) but a significantly larger aster (ratio of aster diameter to oocyte diameter, 0.57 vs 0.30 in the non-treated group). These results indicate that the centrosome introduced into bovine oocytes by whale spermatozoa contributes to the MTOC and that assembly of the microtubule network is promoted by oocyte activation.

Type
Research Article
Copyright
Cambridge University Press 2006

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