Data/hora: 21/09/2024 20:43:13

Biblioteca(s): 	Embrapa Amazônia Ocidental.	
Data corrente: 	14/07/2011	
Data da última atualização: 	21/07/2011	
Autoria: 	ALMEIDA, F. F. L. de; ANDERSSON, E.; MITTELHOLZER, C.; KARLSENC, Ø.; TARANGER, G. L.; SCHULZA, R. W.	
Afiliação: 	FERNANDA FERREIRA LOUREIRO DE ALMEI, CPAA; EVA ANDERSSON, Institute of Marine Research, Reproduction and Growth in Fish; CHRISTIAN MITTELHOLZER, Institute of Marine Research, Reproduction and Growth in Fish; ØRJAN KARLSENC, Institute of Marine Research, Reproduction and Growth in Fish; GEIR LASSE TARANGER, Institute of Marine Research, Reproduction and Growth in Fish; RÜDIGER W. SCHULZA, Utrecht University, Faculty of Sciences, Department of Biology.	
Título: 	Pituitary gonadotropin and testicular gonadotropin receptor expression in Atlantic cod (Gadus morhua L.) during the first reproductive season: effects of photoperiod modulation.	
Ano de publicação: 	2011	
Fonte/Imprenta: 	General and Comparative Endocrinology, v. 173, n. 1, p. 111-119, Ago. 2011.	
DOI: 	10.1016/j.ygcen.2011.05.002	
Idioma: 	Inglês	
Conteúdo: 	Pituitary mRNA levels of gonadotropin &#946;-subunits and of their cognate receptors in the testis were studied during puberty in Atlantic cod under normal and experimental photoperiod conditions that suppressed, delayed or accelerated testis maturation. Results are discussed in context with changes in testicular histology and plasma androgen levels, considered as end points of gonadotropic regulation. Up-regulation of fshb was closely associated with the onset of puberty, decreased when spermatogenesis was completed and reached minimum levels after spawning. These results demonstrate, for the first time using an experimental approach, that activation of Fsh-dependent signaling is associated with spermatogonial proliferation and formation of spermatogenic cysts. Changes in fshr expression were less prominent and could be explained by changes in the cellular composition and RNA content of cod testis tissue. At more advanced stages of development (spermiogenesis, spermiation and spawning), lhb and, one month later, lhcgr transcript levels increased and reached peak values in spawning fish, in a positive feedback loop involving plasma androgens and Lh/Lhcgr-dependent signaling. This loop was broken by a loss of lhb expression at the end of the spawning season. Continuous light (LL) from summer solstice, not, vert, similar8 months prior to spawning, suppressed the start of testis maturation and the changes in gonadotropin and receptor mRNA levels, while LL from winter solstice initially up-regulated lhb and lhcgr expression, before resulting in a precocious termination of the spawning season and low expression of all four genes. Our studies provide experimental evidence for a clear functional discrimination of cod gonadotropins.	
Palavras-Chave: 	Espermatogenesis; Fotoperíodo; Hormônios; Puberdade; Telaósteos.	
Thesagro: 	Bacalhau; Hipófise; Peixe; Reprodução.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Amazônia Ocidental (CPAA)	
Exemplares: 	CPAA - (23851-1) - UPC - AP - PP - S7666 -  - S7666 - DIS