Features of Sperm Motility and Circadian Rhythm in Japanese Anchovy (Engraulis japonicus)Dipak Pandey1,2, Yong-Woon Ryu2 and Takahiro Matsubara2*
- *Corresponding Author:
- Dr. Takahiro Matsubara
South Ehime Fisheries Research Center, Faculty of Agriculture
Ehime University, 25-1 Uchidomari, Minamiuwa-gun
Ainan, Ehime 7984206, Japan
Tel: (+81) 895-737112
Fax: (+81) 895-737113
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Received date: May 03, 2017; Accepted date: May 24, 2017; Published date: May 28, 2017
Citation: Pandey D, Ryu YH, Matsubara T (2017) Features of Sperm Motility and Circadian Rhythm in Japanese Anchovy (Engraulis japonicus). Fish Aqua J 8:203. doi: 10.4172/2150-3508.1000203
Copyright: © 2017 Pandey D, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Japanese anchovy (Engraulis japonicus) is a commercially and ecologically important fish that exhibits group synchronous and multiple spawning. However, the reproductive characteristics of the male in this species, especially sperm features and activation, are still largely unknown. In this study, we confirmed that features of the sperm and characteristics of the activations, regarding sperm motility and moving velocity. The average size of the sperm was 51 Â± 1.3 Î¼m in total length and possessed a normal structure with clockwise, anticlockwise, and linear motion. The initial motility at one minute after activation in seawater was 75 Â± 12% during spawning time in this species (21:00âÂÂ 22:00), and the initial moving velocity (196 Â± 26 Î¼m/sec) remained constant for fifteen minutes post activation. While, comparatively low motility (30 Â± 10%) was found until 17:00, and the sperm was almost immotile in the morning (08:00âÂÂ09:00). Swimming ability was also confirmed with sperm that swam for more than one hour in seawater without an exogenous energy supply derived from the ovary in females, suggesting the trigger for sperm activation in multiple spawning fish is possibly species dependent. This report is the first to demonstrate time specific activation, that is, circadian rhythm, in teleost males.