Characterization of growth hormone in yellow perch and myostatin in several teleost species

Animal growth is a dynamic process that is controlled by many factors including nutrition, environmental conditions and internal regulators. The objective of the research presented here was to look at two contrasting regulatory factors that influence growth in vertebrates and to obtain a better understanding of their roles in fish.; A growth hormone (GH) cDNA was isolated from yellow perch and used to produce a recombinant protein. The recombinant protein was used to generate a polyclonal antibody that recognized a 21 kDa protein in perch pituitaries. Levels of GH immunoreactive protein significantly increased in estradiol-17β treated perch. The antibody can be used to measure perch GH in experiments aimed at understanding the factors that affect perch growth so that they can be optimized for aquaculture production.; A negative regulator of muscle mass in vertebrates, myostatin, was also characterized in several teleost species. Two myostatin (MSTN) isoforms were isolated from brook trout. One isoform was isolated from muscle and brain (b/m MSTN) and the second from ovarian tissue (ov MSTN). Within the brain, MSTN transcripts were localized to the optic lobes, hindbrain, and hypothalamus. In the trout ovary, MSTN transcripts were upregulated at ovulation in several females. MSTN cDNA fragments were also isolated from several other fish species and differential expression of MSTN between red and white muscle was observed.; To better characterize MSTN expression in brook trout, quantitative real-time RT-PCR and Western analysis were used to characterize RNA expression of the two MSTN isoforms and levels of MSTN immunoreactive protein (MIP), respectively. Higher levels of b/m MSTN were observed compared to ov MSTN, and b/m MSTN appeared to be differentially regulated across muscle type. In general, Western analysis indicated an increase in MIP at spawning in both males and females in a tissue specific manner (males—red and white muscle/females—red muscle). Only the ov MSTN RNA and the MIP corresponding to the precursor form of MSTN were detected in brook trout eggs/embryos.