The objective of this study was to determine the genotype effects of the bovine insulin-like growth factor Ⅰ （IGF-Ⅰ） and its binding protein 3 （IGFBP3） genes on growth and development traits in beef cows, including 130 Chinese Simmental, 42 Nanyang, and 47 Luxi Yellow cattle. Sequence variations in the bovine IGF-Ⅰ and IGFBP3 genes were investigated by single strand conformation polymorphism （SSCP）. SSCPs were detected in 6 fragments, which is the 5＇-flanking region, the 2nd exon, the 5th exon, and the 5th intron of the IGF-1 gene, and the 2nd exon, the 3rd exon of the 1GFBP3 gene. Two polymorphisms, an A-to-G transition in the 2rid exon of the IGF-Ⅰ gene and a T-to-C transition in the 2rid exon of IGFBP3 gene were detected in 3 breeds. The allele frequencies of 2 polymorphisms were 0.0411 （A）, 0.9589 （B）, and 0.7237 （A）, 0.2763 （B）, respectively. These 2 loci were analyzed to associate with body weight, height at withers, body length, heart girth, rump width, and beef production index （BPI） at 0, 6, 12, 24, and 36-month old. The IGFBP3 locus was shown to be associated with rump width, heart girth at 24-month and 36-month. Animals with BB genotype had higher rump width （24.86 ± 0.47） cm at 24-month and （27.50 ± 0.63） em at 36-month. The heart girth was highest for the individuals with BB genotype （171.33 ± 1.84） cm and higher than those with AB genotype （166.68 ± 1.13） cm （P〈 0.05） at 36-month.
Interleukin-1 receptor-associated kinases （IRAKs） are important signaling elements of the toll-like receptors family, which play a role in innate immune responses by coordinating host defense mechanisms. Presently different isoforms of human and murine IRAK2 molecules are cloned, but there is no report on the sequences and structure of bovine IRAK2 gene. In this study, we cloned the bovine IRAK2 gene by RT-PCR and RACE and discovered that there exist two alternative splicing of bovine IRAK2 genes, IRAK2a and 1RAK2b （GenBank accession no. EU528620 and EU528621）. IRAK2a gene is 2 148 bp coding 622 aa, which contains a death domain （aa 14-94） and a kinase domain （aa 205-440）, but 1RAK2b lacks 147 bp of exon 3 corresponding to 1RAK2a, and codes 386 aa which contains only partly kinase domain.
WANG Xing-pingLUOREN Zhuo-maXU Shang-zhongGAO XueLI Jun-yaREN Hong-yanCHEN Jin-bao
