| Summary: | 碩士 === 東海大學 === 畜產與生物科技學系 === 99 === Taiwan country chicken is one of the favorite poultry in Taiwan. However, the reproductive ability of Taiwan country chicken is low and the related genes associated with reproduction is not known. The objective of this study was to investigate the relationship between single nucleotide polymorphisms (SNPs) in myostatin 5′-regulatory region and the egg production in various chicken breeds. The genomic DNAs were extracted from White Leghorn chicken, and Red Feather, L2 and B lines of Taiwan country chicken. The PCR method was used to amplify the 1.2-kb fragment of chicken myostatin 5′-regulatory region. Sequence alignment revealed 9 SNPs (C-181A, C-290T, A-295G, A-410C, T-425A, A-426T, C-458T, C-693T, and C-730A) in this region. Among these 9 SNPs, C-181A polymorphism exists in all chicken breeds, 7 SNPs exist in L2 and B lines of Taiwan country chicken, and C-693T polymorphism exists only in White Leghorn chicken. Genotyping results for polymorphisms at A-295G and T-425A positions showed that chickens with AA/TT homozygote, AG/TA heterozygote and GG/AA homozygote had average production of 82, 66 and 50 eggs over 24 weeks, respectively; and the AA/TT homozygote average egg production were significantly the highest. The promoter regions from three genotypes were constructed based on these 9 SNPs and designated as HE (C C A A T A C C C), LE (C T G C A T T C A) and M (A C A A T A C T C), respectively. The results indicate that LE genotype had the lowest average egg production among the breeds. Promoters with different SNPs from three genotypes were constructed into pGL3-basic plasmids. The constructs and pGL3-basic plasmid alone were transfected separately into L8 and C6 cells. The results showed that there was no significant difference among all transfectants in L8 cells, but all transfectants were significantly different in C6 cells. The pGL3 myo-LE construct express the lowest reporter gene and the chickens with LE genotype had the lowest average egg production among the breeds. In conclusion, SNP in myostatin promoter region appears to be related to the egg production, and the results from this study suggest that the polymorphisms in myostatin 5′-regulatory region is a potential selection marker for high egg production in chickens.
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