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Vol. 40 No. 1, 2001
Synchronization of Plasma Sexual Steroid Concentrations and Gonadal Cycles in the Sleeper, Eleotris acanthopoma
Hurng-Yi Wang1,2,§, Ching-Feng Weng3,§, Ming-Chung Tu1 and Sin-Che Lee2,*
1Department of Biology, National Taiwan Normal University, Taipei, Taiwan 116
2Institute of Zoology, Academia Sinica, Nankang, Taipei, Taiwan 115
3Institute of Biotechnology, National Dong Hwa University, Hualien, Taiwan
Hurng-Yi Wang, Ching-Feng Weng, Ming-Chung Tu and Sin-Che Lee (2001) This paper describes the possible influences of environmental factors on the reproductive cycle of Eleotris acanthopoma
in the Kaoping River estuary. For over 1 yr, gonad gross morphologies
of the fish were examined by light microscopy, and plasma 17
beta-estradiol (E2) and testosterone (T) were analyzed by ELISA. In
male E. acanthopoma, plasma T
concentrations show a single seasonal cycle, with a peak in the summer
(June to August) following the profile of the gonadosomatic index
(GSI). In females, plasma E2 concentrations are significantly elevated
during summer in accordance with the GSI. Low temperatures and a short
photoperiod in the winter correlate well with the arrest of gonad
maturation. Annual patterns of plasma E2 and T levels are similar to
those of GSI changes existing in E. acanthopoma of either sex. These
findings indicate that both temperature and photoperiod dominantly
affect the reproductive cycle of E. acanthopoma.
Key words: Photoperiod, Temperature, Annual cycle, Eleotris acanthopoma, Estradiol (E2) and Testosterone (T).
*Correspondence: §The
first 2 authors contributed equally to this study. Tel: 886-2-27899520.
Fax: 886-2-27858059. E-mail: sclee@gate. sinica.edu.tw
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