Evaluation of the association of SLC11A1 gene polymorphism with incidence of paratuberculosis in goats.

Paratuberculosis is one of the chronic granulomatous enteritis that predominantly affects ruminants world wide, caused by Mycobacterium avium ssp. paratuberculosis (MAP). In ruminants, microsatellite polymorphisms of the 3' untranslated region (3'UTR) of the solute carrier family 11 member A1 (SLC11A1) gene were associated with resistance to intracellular pathogen infections. This research was carried out to detect the polymorphisms in A and B regions of the 3'UTR of SLC11A1 gene and to evaluate the potential association between these polymorphisms and MAP infection in goats. MAP-specific antibodies were detected by ELISA and MAP infection was confirmed by IS900 PCR in 150 adult goats from different regions of Kerala, India. The polymorphism of microsatellite regions A and B at 3'UTR of the SLC11A1 gene was analysed in goats by an automated technique, fragment analysis, using fluorescent-tagged forward primers. Eight alleles with sizes ranging from 221 to 239 bp were found in region A. Region B revealed two alleles, 117 bp (B7) and 119 bp (B8). Animals with B8 alleles were found to have higher incidence of paratuberculosis than animals with B7 alleles (P < 0.01). There was no statistically significant association found between region A genotypes and paratuberculosis incidence. These results suggest that caprine SLC11A1 gene has significant role in paratuberculosis resistance in goats and further studies might help in development of a PCR-based genotyping test for paratuberculosis resistance and selection of superior animals for future goat breeding programmes.

cDNA cloning, structural analysis, SNP detection and tissue expression profile of the IGF1 gene in Malabari and Attappady Black goats of India.

Insulin-like growth factor 1 (IGF1) plays an important role in growth, reproduction, foetal development and cell proliferation. The present study was conducted to clone and sequence the full-length coding sequence of the caprine IGF1 gene from Attappady Black and Malabari breeds, two indigenous goat breeds of south India, to analyse its structure, and to ascertain the relative abundance of IGF1 mRNA in different tissues. The caprine IGF1 cDNA (GenBank accession nos: KJ549851 and KJ549852) contained a 465-bp open reading frame encoding IGF1 protein with 154 amino acid residues. A novel SNP was detected in the 3'UTR region, g.931A>G. Genotyping was performed in 277 goats from the two genetic groups using the PCR-single strand conformational polymorphism (SSCP) and two genotypes, AA and AG were observed at this locus. IGF1 is a secretary pathway protein with 49 amino acid-long signal peptide with 19 phosphorylation sites. Caprine IGF1 amino acid sequence was 83-99% identical to other species with highest identity with the ruminants. Relative expression of IGF1 was highest in uterus and liver (P < 0.05), followed by oviduct and muscle. This work provided an important experimental basis for further research on the functions of IGF1 in goats.

Molecular cloning, SNP detection and association analysis of 5' flanking region of the goat IGF1 gene with prolificacy.

The insulin-like growth factor 1 has an important role in reproduction, foetal development and growth. It regulates the secretion of gonadotrophin releasing hormone, stimulates ovarian function and steroidogenesis. The present study was conducted to characterise the 5' flanking region of goat IGF 1 gene, ascertain ovarian expression of the IGF1 gene, detect SNPs and assess the association with prolificacy in the two indigenous goat breeds of South India viz., low prolific Attappady Black and high prolific Malabari. The 5' flanking region of IGF1 gene was PCR amplified, cloned and sequenced from both breeds. Genotyping was performed in 277 goats from the two genetic groups using the PCR-Single Strand Conformational Polymorphism (SSCP) and the expression of the IGF1 gene in the ovary was analysed by quantitative real time PCR. The 5' flanking region of the IGF1 gene was 601 bp long and located at 450 bp upstream of the start codon. Sequence exhibited 97-99% similarity with that of the sheep, cattle and sika deer IGF1 genes. Three genotypes, PP, PQ and QR were observed at this locus with the frequency of 0.62, 0.30 and 0.08, respectively. Sequencing of the representative PCR products from each genotype revealed two SNPs, g.224A>G and g.227C>T. The population was found to be in Hardy-Weinberg disequilibrium at both loci. Statistical results indicated that these loci were associated with litter size (P ≤ 0.05). However, no significant difference was found in the expression of the IGF1 gene in the ovaries of the two goat breeds. These results suggest the significant influence of the IGF1 gene on prolificacy in goats and identified SNPs would benefit the selection of prolific animals in future breeding programs.