Molecular characterization of growth hormone genes in Egyptian Tilapias

Document Type : Original Article

Authors

1 Department of Animal Production, Faculty of Agriculture, Al-Azhar University Cairo, Egypt.

2 Department of Genetics, Faculty of Agriculture, Ain Shams University, Shubra El- Khema, Cairo, Egypt.

Abstract

This study presented growth hormone (GH) gene of three fish species in Egypt namely; Oreochromis niloticus (KT387598 accession number), Sarotherodon galilaeus (KT387599 accession number) and Tilapia zillii (KT387600 accession
number) which belong to cichlids. The tilapiine species growth hormone (GH) genes were isolated and sequenced following amplification from genomic DNA by the polymerase chain reaction (PCR) technique. The sequences of GH gene were analyzed by GENEIOUS program ( V8.1) software. The gene lengths were variable among the three studied species which ranged from 1572bp to 1601bp and consisted of six exons and five introns. Was also described a novel polymorphism of the six exons and the five introns fragments. Exons showed 26 nucleotide polymorphisms
(NPs) while the total number of NPs in introns was 37. A comparison between the three studied species indicated that T. zillii species was totally different from the others. It had three insertions and nine substitutions which were not existed in the other species. The sequencing predicted a polypeptide of 204 amino acids. The GH amino acid sequence of tilapiine species exhibited the homology in all amino acids expect only four amino acids which were different [Isoleucine (I)> Threonine (T), Glycine (G)> Arginine (R), Leucine (L)> Lysine (K) and Leucine (L)> Valine (V)] in
78, 97, 132 and 133 sites, respectively; which all differences were only found in T. zillii species. In the phylogenetic tree the single outlier was T. zillii species.

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Egyptian Journal of Aquatic Biology and Fisheries
Volume 20, Issue 1
January and February 2016
Pages 35-46

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