Research on development of gene markers associated with marbling and growth traits based on the gene expression profiling
助川, 慎Sukegawa, Shin
112 , 2015-09-24 , 新潟大学
学位の種類: 博士（農学）. 報告番号: 甲第4092号. 学位記番号: 新大院博（農）甲第155号. 学位授与年月日: 平成27年9月24日
The recent livestock breeding has improved target traits tremendously with the evaluation techniques of genetic capacity based on statistical genetic method. Especially the improvement of marbling trait in Japanese Black Cattle, which has great economic value in Japan, has been strenuously implemented. In chapter 1, the current status and problems of livestock breeding with the statistical genetic method were discussed. The classical method comprehensively evaluates a total sum of a lot of genes involved in quantitative traits, so that it cannot evaluate or select the effect of each gene. The identification of genes and their polymorphisms associated with target traits and the development of the various genetic markers which are available for livestock selection have been reported to overcome this problem. To develop the gene markers which can be used to improve beef marbling trait of Japanese Black cattle, we had the idea of utilization of the method based on gene expression profiling and achieved the identification of multiple gene polymorphisms associated with marbling. However there are several problems to be considered to establish these identified gene polymorphisms as gene markers. We therefore investigated in chapter 2 whether c-312A>G, an identified gene polymorphism, can be applied to the population of Japanese Black cattle with various genetic background and whether there is any influence on economic traits other than marbling or not. The results demonstrated that c-312A>G had significant association with marbling trait in the population of commercial Japanese Black cattle with various genetic background and clarified that there was no negative effect on other economic traits. That is, the usefulness of c-312A>G as a genetic marker for marker assist selection was revealed. In chapter 3, the influence of interactions among gene polymorphisms useful as selection marker on marbling trait was examined for the three gene polymorphisms (g.1471620G>T、c*188G>A、g.3129537C>T) which were identified in Japanese Black cattle. The result revealed the importance of detection and elucidation of significant interaction effects among the gene polymorphisms when plural gene markers were used in marker assist selection. Through chapter 2 and 3, we revealed the usefulness of the effective operation manner for target trait associated polymorphisms developed by the gene expression profiling method as genetic markers for marker assisted selection and verified the benefit of the development of marbling gene markers for Japanese Black Cattle with this method.
We discussed the effectivity of the gene expression profiling method using marbling trait of Japanese Black cattle as target trait so far, while at the same time, the effectivity of this method on other livestock or traits has not been verified sufficiently. In chapter 4, we adapted this method to daily gain traits of landrace pig and tried to ascertain that this method was effective in various livestock and traits. We also tried to develop a new gene marker useful for daily gain traits in pig. We applied subtraction cloning and differential screening, as gene expression profiling method, to two pig groups with high and low genetic capacity of daily gain and identified several genes with differential gene expression among the two pig groups. With function annotation information of these genes gained by in silico analysis as well as past QTL analysis information, we successfully screened 5 genes possessing strong association with daily gain. Furthermore, we performed sequence analysis focusing on promotor region which was expected to control the gene expression of 5genes and identified the gene polymorphism with different allele frequency between the two pig groups with different daily gain genetic capacity. Through the chapter 1 to 4, we revealed the usefulness of new method of gene expression profile for development of the gene markers required for efficient marker assist selection of livestock breeding and the effects, main and epistatic, of the developed gene markers on the target traits. These findings are expected to further enhance a variety of economical important genetic capacity of livestock and contribute to the corresponding efficient livestock breeding towards increase of economic value of livestock by utilizing the genetic marker developed with this method for livestock breeding as a practical matter.