Sun Dongxiao

Analysis of DNA methylation in different chicken tissues with MSAP

With methylation sensitive amplified polymorphism (MSAP), the DNA methylation levels and patterns of CCGG sites in genomes was analyzed among four different tissues and between parents and offsprings from three groups of adult chicken, White Leghorn, White Plymouth Rock, and their F1 hybrids. The results indicated that the degree of methylation was approximate 29.7% in muscle, 27.5% in liver, 27.5% in heart, and 26.1% in kidney. There was significantly different in the level of methylation in the 3 different groups and in 4 different tissues (P<0.05). The fully-methylated sites were less than the hemi-methylated sites among the 4 tissues, which was different from that of plants. The two tissue-specific MSAP fragments were isolated, sequenced, and characterized, both of which were located in the coding regions. These results clearly demonstrated that there was difference in the methylation level among various tissues and different groups, which suggested that the genetic factor may have effect on the individual methylation level.

Identification of the complex vertebral malformation gene in Chinese Holstein and its association with dairy performance traits

Complex vertebral malformation is caused by a single base mutation from G to T at the nucleotide position 559 in the bovine solute carrier family 35 member 3 (SLC35A3) gene exon 4 on Bos Taurus autosome (BTA) 3. The presence of the disease gene in Holstein dairy cattle has been reported in many countries. In this study, we examined 38 top Chinese Holstein sires in Beijing, four of which were identified as CVM carriers. Furthermore, 555 daughters of the four CV sires were examined and 44.0% of them were identified as heterozygotes at the mutation site. The association analysis between estimated breeding values (EBV) of dairy performance traits and the polymorphism showed that there were extremely significant differences between the carriers and the non-carriers (P<0.01). The EBVs of the five milk production traits of CVM carriers were significantly higher than those of non-carriers, and the lactation persistency and somatic cell score (SCS) were also higher in CVM carriers. Therefore, CVM gene seems to link with a QTL or gene associated with milk production traits on BTA3. It is recommended to cull the CVM carriers gradually for economical and breeding reasons.

Whole cDNA sequence cloning and expression of chicken L-FABP gene and its relationship with lipid deposition of hybrid chickens

Liver fatty acid-binding protein (L-FABP) is closely related to intracellular transportation and deposition of lipids. A positive differential displayed fragment was found in the liver tissue among Silkie (CC), CAU-brown chicken (CD), and their reciprocal hybrids (CD and DC) at 8 weeks-old using differential display RT-PCR techniques (DDRT-PCR). Through recycling, sequencing, and alignment analysis, the fragment was identified as chicken liver fatty acid-binding protein gene (L-FABP, GenBank accession number AY321365). Reverse Northern dot blot and semi-quantitative RT-PCR revealed that the avian L-FABP gene was over-expressed in the liver tissue of the reciprocal hybrids (CD and DC) compared to their parental lines (CC and DD), which was consistent with the fact that higher abdomen fat weight and wider inter-muscular fat width observed in the reciprocal hybrids. Considering the higher expression of L-FABP may contribute to the increased lipid deposition in the hybrid chickens, the functional study of avian L-FABP is warranted in future.