Identification and analysis of a prepro-chicken gonadotropin releasing hormone II (preprocGnRH-II) precursor in the Asian seabass, Lates calcarifer, based on an EST-based assessment of its brain transcriptome.
Using a novel library of 5637 expressed sequence tags (ESTs) from the brain tissue of the Asian seabass (Lates calcarifer), we first characterized the brain transcriptome for this economically important species. The ESTs generated from the brain of L. calcarifer yielded 2410 unique transcripts (UTs) which comprise of 982 consensi and 1428 singletons. Based on database similarity, 1005 UTs (41.7%) can be assigned putative functions and were grouped into 12 functional categories related to the brain function. Amongst others, we have identified genes that are putatively involved in energy metabolism, ion pumps and channels, synapse related genes, neurotransmitter and its receptors, stress induced genes and hormone related genes. Subsequently we selected a putative preprocGnRH-II precursor for further characterization. The complete cDNA sequence of the gene obtained was found to code for an 85-amino acid polypeptide that significantly matched preprocGnRH-II precursor sequences from other vertebrates, and possesses structural characteristics that are similar to that of other species, consisting of a signal peptide (23 residues), a GnRH decapeptide (10 residues), an amidation/proteolytic-processing signal (glycine-lysine-argine) and a GnRH associated peptide (GAP) (49 residues). Phylogenetic analysis showed that this putative L. calcarifer preprocGnRH-II sequence is a member of the subcohort Euteleostei and divergent from the sequences of the subcohort Otocephalan. These findings provide compelling evidence that the putative L. calcarifer preprocGnRH-II precursor obtained in this study is orthologous to that of other vertebrates. The functional prediction of this preprocGnRH-II precursor sequence through in silico analyses emphasizes the effectiveness of the EST approach in gene identification in L. calcarifer.
Tan
Sik-Loo
SL
Malaysia Genome Institute, Heliks Emas Block, UKM-MTDC Smart Technology Centre, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Selangor DE, Malaysia.
Mohd-Adnan
Adura
A
Mohd-Yusof
Nurul Yuziana
NY
Forstner
Michael R J
MR
Wan
Kiew-Lian
KL
D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D002645:Chickens; D020224:Expressed Sequence Tags; D015870:Gene Expression; D020869:Gene Expression Profiling; D007987:Gonadotropin-Releasing Hormone / Q000235:genetics*; D008969:Molecular Sequence Data; D010473:Perciformes / Q000235:genetics*; D010802:Phylogeny; D020033:Protein Isoforms; D011498:Protein Precursors / Q000235:genetics*; D012322:RNA Precursors; D016415:Sequence Alignment
D020033:Protein Isoforms; D011498:Protein Precursors; D012322:RNA Precursors; D007987:Gonadotropin-Releasing Hormone