Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.1/3991
Título: Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus
Autor: Modesto, Teresa
Canario, Adelino V. M.
Palavras-chave: Muscle hypertrophy
Androgen
Castration
Male dimorphism
Data: 1-Out-2003
Editora: The Company of Biologists
Citação: Modesto, T.; Canario, A. V. M.Hormonal control of swimbladder sonic muscle dimorphism in the Lusitanian toadfish Halobatrachus didactylus, Journal of Experimental Biology, 206, 19, 3467-3477, 2003.
Resumo: The swimbladder and associated sonic muscle of the Lusitanian toadfish Halobatrachus didactylus increase in size throughout life and are, respectively, 25% and 30% larger in type I (nest-holder) males than females, which may generate sexual differences in sound production. Sexual dimorphism in swimbladder is also evident in the morphological features of sonic muscle fibers. During the breeding season, type I males have smaller myofibril contracting zones surrounded by larger sarcoplasm areas compared with females, possibly an adaptation to speed and fatigue resistance for the production of long mating calls. Type II (floater) males show characteristics that are intermediate, but statistically not significantly different, between type I males and females. Six weeks after castration and androgen (testosterone and 11-ketotestosterone) replacement in type I and type II males there were no alterations either in swimbladder mass or fiber morphology. However, 17beta-estradiol induced a significant decrease in swimbladder mass and sarcoplasm area/myofibril area ratio. Six months after castration there was a clear reduction in the seasonal swimbladder hypertrophy in males and induction of sonic fiber morphological characteristics that resemble those occurring in females (low sarcoplasm area/myofibril area ratio). These results suggest that testicular factors are required to initiate sonic muscle hypertrophy and type I sonic fiber phenotype in H. didactylus, but a specific involvement of androgens has not been completely clarified.
Peer review: yes
URI: http://hdl.handle.net/10400.1/3991
DOI: http://dx.doi.org/%2010.1242/jeb.00581
ISSN: 0022-0949
Versão do Editor: http://jeb.biologists.org/content/206/19/3467.full.pdf+html
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