| Abstract: | 台灣土雞雖為國人喜愛之禽肉，但其繁殖力偏低，其中相關基因調控產蛋效率之路徑仍未可知。本研究旨在探討雞肌肉生長抑制素（myostatin）基因調節區單核?酸多型性（Single Nucleotide Polymorphism；SNP）與不同品系雞種產蛋性能之關係。將中興大學L2品系、B品系、紅羽土雞與來亨雞基因組DNA，分別藉由PCR方法擴增肌肉生長抑制素基因上游調節區片段約1.2-kb，DNA序列比對發現合計9組SNPs，包括：C-181A、C-290T、A-295G、A-410C、T-425A、A-426T、C-458T、C-693T和C-730A等；其中C-181A SNP見之於L2品系、B品系及來亨雞等三品系中，而C-693T SNP僅位於來亨雞品系，其餘7個SNPs皆位於L2品系與B品系。基因型試驗顯示A-295G與T-425A兩位點在24週期間之平均產蛋量分別為，AA/TT純合子為82顆顯著最高、AG/TA雜合子為66顆，而GG/AA純合子則為50顆。藉由9個SNPs所建構的3種基因型啟動子片段，分別標示為高產組HE（C C A A T A C C C）、低產組LE（C T G C A T T C A）、綜合組M（A C A A T A C T C），將三組帶有不同啟動子片段之報導基因載體轉染L8肌原母細胞與C6神經膠質瘤細胞，並檢測其報導基因之表現。結果顯示L8細胞株各處理組間報導基因表現量無顯著差異，C6細胞株各處理組間均有顯著差異；其中基因型LE（C T G C A T T C A）表現量於兩細胞株試驗中均為處理組中報導基因表現量最低組，且此基因型亦具有所有樣品之最低平均產蛋率。綜合上述，肌肉生長抑制素啟動子SNPs和雞產蛋性能可能有關，而此研究成果可做為具潛力之雞隻產蛋性能選拔方式。
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. |
