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Subject: Animal Genetics and Breeding × Author: KAU × End date: 2009 × Start date: 2009 × Thesis Type: M.V.Sc. ×
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    ThesisItemOpen Access
    Cloning and sequence analysis of the growth hormone gene in Indian elephants
    (Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2009) Bhosale, R A; KAU; Aravindakshan, T V
    The study was undertaken with the objectives of cloning and sequence analysis of the growth hormone gene of the Indian elephants. The growth hormone is a peptide hormone produced in the anterior pituitory. It stimulates the growth of vertebates. It is a protein hormone of about 190 amino acids, synthesized and secreted by cells called somatotrophs. Growth hormone is a major participant in the control of several complex physiologic processes, including growth and metabolism and it is also of considerable interest as a drug used in both humans and animals. The genomic DNA was isolated from blood samples and a 1712 bp fragment of the entire transcriptional unit of the GH was amplified by PCR using synthetic oligonucleotide primer pair designed based on the 5′ and 3′ flanking sequences of goat growth hormone gene. The gel purified PCR product was ligated in to the pGEM®-T Easy cloning vector and was transformed by giving heat shock to competent E. coli cells prepared by CaCl2 treatment. The recombinant clones among the transformed cells were identified by Blue–White Screening and the recombinant plasmid carrying the insert gene was isolated from the white clones by a modified SDS-alkaline lysis method. The 1.712 kb GH gene insert in the vector was sequenced by the dideoxynucleotide sequencing method with primer walking using an automated DNA sequencer. The nucleotide sequence showed 75 to 96 per cent homology with pig and 77 to 95 per cent with that of Dolphin GH genes, respectively. The exon-intron boundaries in the porcine gene occur at the codons of the amino acid residues, Gly-4 (intron 1), Phe-57 (intron 2), Ser-96 (intron 3) and Arg-150 (intron 4). The all four residues are conserved in both species and also in African elephants. This strict homology in the sites of insertion of introns suggests that the exon-intron organization of these genes was established before the divergence of these species. The positions of the exon-intron boundaries are also conserved as evidenced from similar sizes of the exons. Evidence for some homology was also seen in intron 1, which showed maximum 84 per cent similarity with giraffe. In contrast, intron 2, 3 and 4 showed no significant similarity both in length and in sequence with other animal species. The Indian elephant GH gene has an open reading frame of 648 nucleotides encoding a signal peptide of 26 amino acid residues and a mature protein of 190 amino acid residues with both NH2- and COOH- terminal phenylalanine. Alignment of this sequence with African elephant counterpart showed that 189 amino acid residues are identical with only one variant while, with pig sequence it showed 186 identical residues with four variants. The predicted secondary structure showed that the larger α-helical lobe is formed by four sections of the polypeptide chain (residues 3-34, 47-80, 110-126 and 148-172) while the smaller lobe, which encompasses a small antiparallel beta-sheet and a small irregular structure formed the remaining structure of the polypeptide chain. The predicted tertiary structure of the Indian elephant GH showed high homology with the human GH structures. Overall, the structures of Indian elephant GH gene was found to be very similar to that of African elephant and porcine reflecting their high degree of amino acid sequence identity (99 – 97 per cent).
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    ThesisItemOpen Access
    Construction and comparison of the efficiency of different selection indices for malabari goats
    (Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2009) Rani, Alex; KAU; Raghavan, K C
    The study was conducted with the objective of optimizing the genetic improvement of Malabari goat population in North Kerala by adopting an index method of selection incorporating various growth traits and peak yield of dam. Present study was undertaken on 1055 records of animals born from August 2005 to August 2008 from the farmers’ flocks of AICRP on goats for Malabari goats. Effect of non-genetic factors on body weight and body measurements at below one, three and six months of age was analyzed. Effect of centre and sex had significant influence on body weight and body measurements of all the ages studied. Type of birth had significant effect on body weight and measurements at below one and three months of age, but the same was non significant at six months of age except for body length. Year of birth had significant effect on body weights at third and sixth month, where as the effect of season was significant for body weight at below one and three months of age. But the effects of these factors on body measurements were significant at all the ages studied. Milk production in Malabari goats was recorded as peak yield and the mean peak yield recorded was 1237.62± 75.44 ml. The effects of centre, year and season of kidding had significant influence on peak yield. A high percentage of multiple births (75.71%) was recorded in the in the total population under study during the period for Malabari goats. The percentage of multiple births was higher in Tanur (79.29%) than in other centres. Heritability estimates were high for body weight and measurements at below one and six months of age and for peak yield also, whereas for three months of age they were low to moderate. Correlations between the traits were positive in almost all cases. The relative economic values of various traits were derived. Taking into consideration the heritability, genetic and phenotypic correlations as well as relative economic value, selection indices were constructed. Selection indices were developed by incorporating body weight and body measurements at below one, three and six months of age. Index with all the traits under study (I11) was expected to achieve more genetic gain in body weight at six months of age in all the groups. By taking into consideration, the rIH and aggregate economic genetic gain also, the same index was found to be the best in each group. Among the groups, the index with pooled data was considered to be most reliable and expected to achieve more gain in body weight at six months (1.490 kg) of age. Restricted selection indices by imposing restriction on body weight at below one month were also constructed. Effective restriction was possible in all the cases. The genetic advancement in all other characters due to selection of goats based on this index was comparatively less to that obtained with the index without restriction. To increase milk production along with body weight, a selection index was constructed with dam’s peak yield as a trait along with the growth traits of progeny.
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    ThesisItemOpen Access
    Leptin gene polymorphism in vechure and crossbred cattle of Kerala
    (Department of Animal Breeding, Genetics and Biostatistics, College of Veterinary and Animal Sciences, Mannuthy, 2009) Lali F, Anand; KAU; Bindu, K A
    Representative population comprising 74 heads of Vechur and 108 numbers of crossbred cattle of Kerala were investigated for leptin gene polymorphisms and their associations with milk production traits. LEP/BspE1 and BM1500 are the polymorphic markers used for PCR-RFLP and microsatellite analysis, respectively. For PCR-RFLP analysis, the amplified PCR product was digested with restriction enzyme BspE1 which revealed three genotypes in Vechur (CC, CT and TT) and two in crossbred cattle (CC and CT) indicating the presence of C (75 bp and 19 bp fragments) and T (94 bp fragment) alleles. The C/T allele frequencies were 0.82/0.18 and 0.89/0.11, respectively in Vechur and crossbred cattle. The genotypes of LEP/BspE1 polymorphism were distributed according to Hardy-Weinberg equilibrium with frequencies 0.71 (CC), 0.24 (CT) and 0.05 (TT) in Vechur and 0.79 (CC) and 0.21 (CT) with the absence of TT genotype in crossbred cattle under study. The microsatellite polymorphism at BM1500 locus was analyzed in Vechur and crossbred cattle and two novel alleles of size 126 and 132 bp were detected. Allele frequency was highest for 132 bp and in Vechur (0.40) as well as crossbred cattle (0.46) under study. The polymorphic information content of BM1500 marker in Vechur was 0.6595 while 0.656 in crossbred cattle. In the present study, the significant influence of LEP/BspE1 polymorphism on milk production traits. The T allele bearing Vechur and crossbred cattle showed 13.08% (89.77 kg) and 10.7% (466.63 kg) increase for 305 day milk yield, respectively whereas 9.96% (0.31 kg) and 8.38% (1.22 kg), respectively for average daily milk yield. A nonsignificant reduction for milk fat percentage was also observed associated with T allele in both populations. Increased body fat reserves, adipose tissue reserves, feed intake and favorable change in partitioning of nutrients in T allele possessing animals might have contributed to increased milk yield in cattle. For BM1500 marker, highest averages of 305 day milk yield and daily milk yield were observed for Vechur and crossbred cattle possessing 136 bp allele. The highest milk fat percentages were recorded in 136 bp allele bearing Vechur animals and crossbreds possessing 138 bp allele. The association of BM1500 marker with milk production traits can be established only by expanding the research to an extensive cattle population. The selection of Vechur and crossbred cattle, heterozygous for C and T alleles for LEP/BspE1 polymorphism can significantly improve milk yield. The use of molecular techniques provides new opportunities and challenges for building and using more accurately predictive and efficient selection procedures for livestock improvement.