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Identification and gene expression analysis of three GnRH genes in female Atlantic cod during puberty provides insight into GnRH variant gene loss in fish.
- Source :
-
General and comparative endocrinology [Gen Comp Endocrinol] 2011 Jul 01; Vol. 172 (3), pp. 458-67. Date of Electronic Publication: 2011 Apr 20. - Publication Year :
- 2011
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Abstract
- Gonadotropin releasing hormone (GnRH) is a key regulator of sexual development and reproduction in vertebrates. Fish have either two or three pre-pro-GnRH genes, encoding structurally distinct peptides. We identified three pre-pro-GnRH genes in Atlantic cod (Gadus morhua, gmGnRH) using RT-PCR, RACE-PCR and BAC DNA library clone sequencing based on synteny searching. Gene identity was confirmed by sequence alignment and subsequent phylogenetic analysis. The expression of these genes was measured by quantitative PCR in the brain and pituitary of female cod throughout their reproductive cycle and in peripheral tissues. All three gmGnRH genes have highly conserved deduced decapeptide sequences, but sequence and phylogenetic data for gmGnRH1 suggest that this is a pseudogene. gmGnRH1 shares low identity with all fish GnRH variants and grouped with the GnRH3 clade. Although gmGnRH1 is a putative pseudogene, it is transcribed in multiple tissues but at low levels in the brain, indicating the loss of conserved hypophysiotrophic function. Phylogenetic analysis reveals that gmGnRH2 and gmGnRH3 variants are located in variant-specific clades. Both gmGnRH2 and gmGnRH3 transcripts are most abundant in the brain, with lower expression in pituitaries and ovaries. Brain gmGnRH3 gene expression increases in spawning fish and is expressed in the pituitary during puberty. Brain gmGnRH2 transcripts are highly expressed relative to gmGnRH3 before and during spawning. Sequence and expression data suggest that gmGnRH1 is a pseudogene and that gmGnRH3 is likely the hypophysiotrophic form of GnRH in Atlantic cod.<br /> (Copyright © 2011 Elsevier Inc. All rights reserved.)
- Subjects :
- Amino Acid Sequence
Animals
Base Sequence
Brain metabolism
Cloning, Molecular
Conserved Sequence
Female
Fish Proteins metabolism
Gadus morhua growth & development
Gadus morhua metabolism
Gene Expression Profiling
Gene Library
Gonadotropin-Releasing Hormone metabolism
Molecular Sequence Data
Ovary metabolism
Phylogeny
Pituitary Gland metabolism
Pseudogenes
RNA, Messenger metabolism
Reverse Transcriptase Polymerase Chain Reaction
Sequence Alignment
Fish Proteins genetics
Gadus morhua genetics
Gene Deletion
Gonadotropin-Releasing Hormone genetics
Sexual Maturation
Subjects
Details
- Language :
- English
- ISSN :
- 1095-6840
- Volume :
- 172
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- General and comparative endocrinology
- Publication Type :
- Academic Journal
- Accession number :
- 21521645
- Full Text :
- https://doi.org/10.1016/j.ygcen.2011.04.010