Increased growth hormone (GH), growth hormone receptor (GHR), and insulin-like growth factor I (IGF-I) gene transcription after hyperosmotic stress in the Brazilian flounder Paralichthys orbignyanus

Abstract

Growth hormone (GH) action is the result of an intracellular cascade initiated just after its interaction with the growth hormone receptor (GHR) located on the surface of target cells. This cascade culminates with the transcription of target genes, such as the insulin-like growth factors (IGFs), which are responsible for most GH biological effects. In addition to its central role in growth, fish GH is also involved with osmoregulatory control. Within this context, the objective of the present work was to isolate GH, GHR, and IGF-I cDNAs from the Brazilian flounder Paralichthys orbignyanus and evaluate whether these genes are induced by hyperosmotic stress. The obtained results indicated that GH mRNA had a significant peak only 24 h after hyperosmotic stress. In gills, GHR mRNA was significantly increased after 7 days. In liver, GHR and IGF-I mRNAs were significantly increased in 72 h and both reached even higher levels after 7 days. These results indicate that hyperosmotic stress can increase GH sensitivity in the gills and liver of P. orbignyanus and, consequently, improve IGF-I production. The management of this parameter could be useful in achieving better growth performance for this and other commercially important species in which GH has a direct correlation with osmoregulatory mechanisms.

Salinity and photoperiod modulate pubertal development in Atlantic salmon (Salmo salar)

“…Two observations are interesting to note in this context. First, hyperosmotic stress increased growth hormone-mediated, hepatic insulin-like growth factor 1 production (Meier et al 2009), which may have increased pituitary gnrhr mRNA levels (Luckenbach et al 2010). Secondly, hyperosmotic stress following SW exposure might also have stimulated vasopressin release (Balment et al 2006), which in turn can directly stimulate testicular androgen release (Rodríguez & Specker 1991).…”

Life history traits influence in gonad composition of two sympatric species of flatfish

“…The isosmotic point estimate for P. orbignyanus is 10.9‰ (SAMPAIO; BIANCHINI, 2002), the salinity likely to be found in a brackish coastal lagoon such as "Laguna de Rocha" (CONDE et al, 2000). However, it is also known that in P. orbignyanus, as in other species, growth hormone levels increase after suffering hyperosmotic stress, whereby the highest growth rates in P. orbignyanus would be obtained in seawater (MEIER et al, 2009). Despite this, SAMPAIO et al, 2001 observed no significant variations in the growth rates of P. orbignyanus cultured at salinities such as 30ppt and 11ppt.…”

Clonagem e avaliação da expressão gênica do sbGnRH em machos juvenis e adultos de linguado, Paralichthys orbignyanus

“…Estudos recentes relacionados à larvicultura (Sampaio et al, 2007), reprodução (Lanes et al, 2008;Sampaio et al, 2008), potencial para transgênese (Lanes et al, 2009) e expressão de genes ligados ao crescimento e ao controle da fome (Meier et al, 2009;Campos et al, 2010) demonstram a viabilidade do cultivo desta espécie. No entanto, ainda não há estudos sobre os mecanismos moleculares e fisiológicos sobre o controle da puberdade nesta espécie.…”

“…Para densidade óptica das bandas, usou-se o software TotalLab TL 100 (Nonlinar Dynamics, Inglaterra). A taxa de densidade óptica sbGnRH/β-actina foi utilizada para o cálculo de expressão gênica, segundo Meier et al (2009).…”