Molecular Polymorphism Analysis Of BMPR1B, IGFBP-3 And POU1F1 Genes In Nilagiri And Mecheri Sheep
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Date
2009
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Tamil Nadu Veterinary and Animal Sciences University
Abstract
Bone Morphogenetic Protein Receptor type 1 B (BMPR1B), Insulin like Growth Factor Binding Protein -3 (IGFBP-3) and Pituitary Transcription Factor 1 (POU1F1) are structural genes that have multiple physiological roles in reproduction and growth of animals. The present work was carried out on Nilagiri and Mecheri sheep maintained at Sheep Breeding Research Station, Sandynallah, The Nilgiris and Mecheri Sheep Research Station, Pottaneri, Salem district respectively. Polymorphisms of the genes were studied by PCR-RFLP technique.
AvaII PCR-RFLP of BMPR1B gene revealed the presence of FecB mutation in Nilagiri sheep. In Nilagiri sheep, the frequency of FecB allele was found to be 0.14. FecB mutation could not be identified in Mecheri sheep. PCR-RFLP of IGFBP-3 gene (316 bp region and 654 bp region) did not reveal polymorphism in both Nilagiri and Mecheri sheep. Polymorphism was not detected in POU1F1 gene by PCR-RFLP in the 508 bp and 450 bp regions analysed in both Nilagiri and Mecheri sheep.
Association analysis of genotypes at FecB locus with traits of economic importance was carried out in Nilagiri sheep only. The homozygous mutant (FecB^BB) genotype was not considered for association analysis as only one animal was identified with FecB^BB genotype. The least-squares mean for litter size at birth, litter size at weaning, cumulative litter size at birth, cumulative litter size at weaning, cumulative litter weight at birth and cumulative litter weight at weaning was 1.04 ± 0.04, 1.01 ± 0.05, 3.10 ± 0.10, 2.86 ± 0.13, 8.06 ± 0.22 kg and 27.98 ± 1.45 kg respectively among wild type (FecB^++) ewes and the same in heterozygous (FecB^B+) ewes was 1.44 ± 0.05, 1.40 ± 0.06, 4.13 ± 0.14, 4.13 ± 0.19, 9.05 ± 0.32 kg and 35.42 ± 2.19 kg. FecB^B allele significantly (P<0.05 / P<0.01) increased the litter size at birth, litter size at weaning, cumulative litter size at birth, cumulative litter size at weaning, cumulative litter weight at birth and cumulative litter weight at weaning. Hence, FecB mutation can be used as a marker for prolificacy in Nilagiri sheep.
The animals heterozygous at FecB locus (FecB^B+) had slightly higher body weight than the wild type (FecB^++) animals except for birth weight. But the differences were not significant. Thus, FecB^B allele did not have any significant effect on birth weight, weaning weight, body weight at six, nine and twelve months of age in Nilagiri sheep.
Nucleotide sequencing of the 190 bp region of BMPR1B confirmed the presence of FecB mutation in Nilagiri sheep. In Nilagiri sheep, five new SNPs were also identified in the 654 bp region of the IGFBP-3 gene. Nucleotide sequencing of both 508 bp and 450 bp regions of POU1F1 genes revealed an A to T mutation in the exon 6 of the 450 bp fragment in Nilagiri sheep. Phylogenetic analysis with deduced nucleotide sequences revealed that sheep was closely related to goats than to cattle and buffalo. Swine was most distantly related to sheep among the livestock species studied.
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Keywords
Sheep, Nilagiri, Mecheri, FecB mutation, IGFBP-3, POU1F1