Analysis of genetic variation of inducible nitric oxide synthase and natural resistance-associated macrophage protein 1 loci in Malaysian native chickens

The genetic diversity of 100 Malaysian native chickens was investigated using polymerase chain reaction-restriction fragment polymorphism (PCR-RFLP) for two candidate genes: inducible nitric oxide synthase (INOS) and natural resistance-associated macrophage protein 1 (NRAMP1). The two genes were selected because of their important role in chicken’s immune system. INOS and NRAMP1 PCR products were digested by AluI and SacI restriction enzymes, respectively. The restriction digests produced fragment sizes of 322 and 173 bp for INOS and 722 and 79 bp for NRAMP1 as one allele and an undigested PCR product as the other allele. Both loci were polymorph, however only INOS gene showed Hardy-Weinberg equilibrium. Average heterozygosity and the Shannon information index (I) was 0.43 and 0.62 for INOS and 0.48 and 0.68 for NRAMP1 genes, respectively. The observed polymorphism in this study shows the ability of these candidate genes in marker assisted selection and introgression programs to increase resistance to diseases in both Malaysian native and commercial chickens.Key words: Malaysian native chickens, polymorphism, inducible nitric oxide synthase (INOS), natural resistance-associated macrophage protein 1 (NRAMP1)

Demarcation of informative chromosomes in tropical sweet corn inbred lines using microsatellite DNA markers

A study of genetic variation among 10 pairs of chromosomes extracted from 13 tropical sweet corn inbred lines, using 99 microsatellite markers, revealed a wide range of genetic diversity. Allelic richness and the number of effective alleles per chromosome ranged from 2.78 to 4.33 and 1.96 to 3.47, respectively, with respective mean values of 3.62 and 2.73. According to the Shannon's information index (I) and Nei's gene diversity coefficient (Nei), Chromosome 10 was the most informative chromosome (I = 1.311 and Nei = 0.703), while Chromosome 2 possessed the least (I = 0.762 and Nei = 0.456). Based on linkage disequilibrium (LD) measurements for loci less than 50 cM apart on the same chromosome, all loci on Chromosomes 1, 6 and 7 were in equilibrium. Even so, there was a high proportion of genetic variation in Chromosomes 4, 5, 8, 9 and 10, thereby revealing their appropriateness for use in the genetic diversity investigations among tropical sweet corn lines. Chromosome 4, with the highest number of loci in linkage disequilibrium, was considered the best for marker-phenotype association and QTL mapping, followed by Chromosomes 5, 8, 9 and 10