Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí sinh học thế giới đề tài: Genes influencing milk production traits predominantly affect one of four biological pathways | Genet. Sel. Evol. 40 2008 79-89 Available online at INRA EDP Sciences 2008 DOI gse 2007038 Original article Genes influencing milk production traits predominantly affect one of four biological pathways Amanda Jane Chamberlain Helen Clare McPartlan Michael Edward Goddard Animal Genetics and Genomics Platform Department of Primary Industries Victoria Australia Received 14 December 2006 accepted 24 July 2007 Abstract - In this study we introduce a method that accounts for false positive and false negative results in attempting to estimate the true proportion of quantitative trait loci that affect two different traits. This method was applied to data from a genome scan that was used to detect QTL for three independent milk production traits Australian Selection Index ASI protein percentage p and fat percentage corrected for protein percentage F - p . These four different scenarios are attributed to four biological pathways QTL that 1 increase or decrease total mammary gland production affecting ASI only 2 increase or decrease lactose synthesis resulting in the volume of milk being changed but without a change in protein or fat yield affecting p only 3 increase or decrease protein synthesis while milk volume remains relatively constant affecting ASI and p in the same direction 4 increase or decrease fat synthesis while the volume of milk remains relatively constant affecting F - p only . The results indicate that of the positions that detected a gene most affected one trait and not the others though a small proportion affected ASI and p in the same direction. bivariate analysis independent traits pleiotropy genome scan false discovery rate 1. INTRODUCTION As a result of complex biochemical developmental and regulatory pathways a polymorphism in a single gene will almost always influence multiple traits a phenomenon known as pleiotropy 6 8 . In classical quantitative genetics pleiotropy is recognised by genetic correlations. The existence
