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Rainbow trout has two genes for growth hormone
L B Agellon1, S L Davies, C M Lin
1Department of Biology, Johns Hopkins University, Baltimore, Maryland.
Molecular Reproduction and Development
|January 1, 1988
Summary
Researchers identified two distinct rainbow trout growth hormone (GH) mRNA types, GH1 and GH2. These likely originated from separate gene loci duplicated during ancient salmonid genome evolution.
Area of Science:
- Molecular Biology
- Genomics
- Evolutionary Biology
Background:
- Growth hormone (GH) plays a crucial role in fish growth and development.
- Understanding GH gene structure and expression is vital for aquaculture and evolutionary studies.
- Rainbow trout (Salmo gairdneri) possess complex genomes due to past polyploidization events.
Purpose of the Study:
- To determine the primary structures of two distinct growth hormone (GH) mRNA species in rainbow trout.
- To investigate the genetic basis and evolutionary origins of these GH mRNA variants.
- To confirm the expression of the identified GH genes in trout pituitary tissue.
Main Methods:
- Cloning and sequencing of cDNA and genomic DNA encoding rainbow trout GH.
- Bioinformatic analysis to predict mRNA structures and identify variant amino acid residues.
- RNA blot analysis using specific oligonucleotide probes to detect GH mRNA expression.
Main Results:
- Two mRNA species, GH1 and GH2, were identified, each encoding 210 amino acids with 11 variants.
- Both mRNAs share a conserved 5'-untranslated region but have divergent 3'-untranslated sequences, suggesting different genetic loci.
- RNA blot analysis confirmed the expression of GH2 mRNA in trout pituitary RNA.
Conclusions:
- The GH1 and GH2 mRNA species likely originate from two distinct loci in the rainbow trout genome.
- These loci are proposed to be the result of gene duplication events during salmonid tetraploidization.
- The findings provide insights into the evolution of growth hormone genes in salmonid fish.