Influence of tidal cycles on the endocrine control of reproductive activity in common snook (Centropomus undecimalis).
The aim of our study was to confirm the role of tidal pattern on the coordination of oocyte maturation and spawning in common snook Centropomus undecimalis. To do so, we studied oocyte maturation during the spawning season in relation to the tidal pattern in both males and females by means of histology and hormonal profiling along the pituitary-gonadal axis. Plasma LH levels, as well as transcript levels of gonadotropin genes (fshβ and lhβ) from the pituitaries of sexually mature male and female common snook were analyzed using a heterologous ELISA and quantitative RT-PCR, respectively. The fshβ and lhβ cDNAs were isolated and phylogenetic analysis of the deduced amino acid sequences revealed strong identity with other teleosts (75-90%). A strong link was found between tide and follicular development irrespective of the time of the day: female snook sampled on the rising tide were all found to have oocytes in the Secondary Growth Stage whereas females sampled at high tide or on the falling tide had oocytes in the later stages of maturation and ovulation. In addition, LH plasma and mRNA levels of fshβ and lhβ increased during the later stages of vitellogenesis peaking at ovulation in females. Plasma estradiol and testosterone significantly increased in late vitellogenesis (Secondary Growth Stage) and oocyte maturation (Eccentric Germinal Vesicle Step) respectively. Among male common snook sampled, no correlation was identified between tide and gonadal development. In addition, lhβ mRNA expression in males peaked at the mid germinal epithelium stage as for testosterone and 11-KT in the blood while fshβ expression and plasma LH levels peaked at late germinal epithelium stage. This study confirms the role played by tidal cycle on the entrainment of the later stages of oogenesis of common snook and provides a better understanding of the link between environmental and endocrine control of reproduction in this species.
Mote Marine Laboratory, Directorate of Fisheries and Aquaculture, 874 WR Mote Way, Sarasota, FL 34240, USA. Electronic address: nrhody@mote.org.
Nicole R
NR
Rhody
Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, UK.
Andrew
A
Davie
Department of Marine Biotechnology and Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E. Pratt Street, Baltimore, MD 21202, USA.
Nilli
N
Zmora
Department of Marine Biotechnology and Institute of Marine and Environmental Technology, University of Maryland Baltimore County, 701 E. Pratt Street, Baltimore, MD 21202, USA.
Yonathan
Y
Zohar
Mote Marine Laboratory, Directorate of Fisheries and Aquaculture, 874 WR Mote Way, Sarasota, FL 34240, USA.
Kevan L
KL
Main
Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, UK.
Hervé
H
Migaud
D000818:Animals; D015153:Blotting, Western; D018076:DNA, Complementary / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D037201:Follicle Stimulating Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism*; D037101:Luteinizing Hormone, beta Subunit / Q000235:genetics / Q000378:metabolism*; D008297:Male; D009866:Oogenesis / Q000502:physiology; D010060:Ovulation / Q000502:physiology*; D010473:Perciformes / Q000254:growth & development / Q000378:metabolism*; D010802:Phylogeny; D010902:Pituitary Gland / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D012098:Reproduction / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014818:Vitellogenesis / Q000235:genetics
D018076:DNA, Complementary; D037201:Follicle Stimulating Hormone, beta Subunit; D037101:Luteinizing Hormone, beta Subunit; D012333:RNA, Messenger
Common snook; FSH; Gametogenesis; Gene expression; LH; Tidal cycle