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.
An exploratory methodology has been used to identify genes related to growth of the shrimp Farfantepenaeus paulensis (Pérez‐Farfante, 1967). Six hundred postlarvae, with an average (±SD) initial weight of 0.022 g (±0.008), were reared for 60 days in salinity 30 g L−1. In the end, the 15 heaviest (>1.2 g) and the 15 lightest (<0.6 g) animals were frozen in liquid nitrogen. A modified differential display reverse transcription‐polymerase chain reaction technique was used to generate expression profiles for all individuals. The resulting cDNA from reverse transcription were amplified by pairing 31 arbitrary primers with a reverse primer anchored to the cDNA tails. From the comparison between the expression profiles of the organisms in the two size classes, differences could be pinpointed. Bands of interest were collected, purified, cloned and sequenced. Despite the relatively small number of primers used, the methodology allowed the identification of three genes, not described previously for the investigated species and possibly related to growth. These partial sequences are likely to belong to genes that code for myosin heavy chain, cyclophilin and haemocyanin as revealed through an amino acid similarity search conducted using the blastp on‐line tool.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.