TY - JOUR
T1 - Dimorphic sperm influence semen distribution in a non-copulatory sculpin Hemilepidotus gilberti
AU - Hayakawa, Youichi
AU - Akiyama, Ryo
AU - Munehara, Hiroyuki
AU - Komaru, Akira
N1 - Funding Information:
We thank K. Shimazaki, H. Ogi and Y. Sakurai, Faculty of Fisheries, Hokkaido University, for their advice and encouragement. We also thank T.R. Birkhead, Sheffield University for suggestions, and B.A. Afzelius, Stockholm University for important discussion. We appreciate J. Bower, Hokkaido University for critically reading the manuscript. This study was supported in part by Research Fellowships of Japan Society for Promotion of Science for young scientists. It is contribution number 149 from the Usujiri Fisheries Laboratory, Faculty of Fisheries, Hokkaido University.
Copyright:
Copyright 2008 Elsevier B.V., All rights reserved.
PY - 2002/11/1
Y1 - 2002/11/1
N2 - We used an artificial semen emission test to examine the semen transporting role of parasperm (unflagellated sperm), which are produced along with eusperm (normal sperm) by an incomplete meiosis in the marine sculpin Hemilepidotus gilberti. After separation of contents of semen (eusperm, parasperm, and seminal plasma) by centrifugation, the distance traveled by semen discharged vertically from a syringe into seawater was compared among various test semen; eusperm semen (eusperm re-mixed with seminal plasma), parasperm semen (parasperm re-mixed with seminal plasma), normal semen (eusperm and parasperm re-mixed with seminal plasma), and natural semen (unmodified semen). Parasperm semen traveled more than 1.5 times as far as the eusperm semen. The lateral dispersion width of normal semen after emission was significantly narrower than that of eusperm semen. These findings indicate that parasperm can reduce the lateral dispersion and prolong the distance semen travels. The eusperm ratio in the lower portion of the emitted semen did not differ from that in the upper portion, indicating that eusperm evenly distribute within the ejaculate and reach the lower portion of semen. Since males cannot closely approach eggs that are deposited in the narrow space between the female's belly and the spawning substrate, restraint of lateral dispersion and prolongation of the distance semen traveled would increase the number of eusperm arriving at eggs, despite reduction of eusperm in the ejaculate.
AB - We used an artificial semen emission test to examine the semen transporting role of parasperm (unflagellated sperm), which are produced along with eusperm (normal sperm) by an incomplete meiosis in the marine sculpin Hemilepidotus gilberti. After separation of contents of semen (eusperm, parasperm, and seminal plasma) by centrifugation, the distance traveled by semen discharged vertically from a syringe into seawater was compared among various test semen; eusperm semen (eusperm re-mixed with seminal plasma), parasperm semen (parasperm re-mixed with seminal plasma), normal semen (eusperm and parasperm re-mixed with seminal plasma), and natural semen (unmodified semen). Parasperm semen traveled more than 1.5 times as far as the eusperm semen. The lateral dispersion width of normal semen after emission was significantly narrower than that of eusperm semen. These findings indicate that parasperm can reduce the lateral dispersion and prolong the distance semen travels. The eusperm ratio in the lower portion of the emitted semen did not differ from that in the upper portion, indicating that eusperm evenly distribute within the ejaculate and reach the lower portion of semen. Since males cannot closely approach eggs that are deposited in the narrow space between the female's belly and the spawning substrate, restraint of lateral dispersion and prolongation of the distance semen traveled would increase the number of eusperm arriving at eggs, despite reduction of eusperm in the ejaculate.
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U2 - 10.1023/A:1020507120692
DO - 10.1023/A:1020507120692
M3 - Article
AN - SCOPUS:0036828551
SN - 0378-1909
VL - 65
SP - 311
EP - 317
JO - Environmental Biology of Fishes
JF - Environmental Biology of Fishes
IS - 3
ER -
