Biomedical subjects

Xue-Wei Li

Publications and source records attributed to Xue-Wei Li.

10 recordsLinked to original sources

PubMed2006

Molecular cloning and tissue-specific expression of intestinal-type fatty acid binding protein in porcine.

The intestinal fatty acid-binding protein (I-FABP) shows binding specificity for long-chain fatty acids and is proposed to be involved in the uptake of dietary fatty acids and their intracellular transport. In this study, the full-length cDNA of I-FABP was cloned from pig intestine by homology cloning approach combined with 3' and 5' RACE. Sequence analysis and bioinformatics study showed that this cDNA contained 614 nucleotides, with a 399 bp open reading frame (ORF) flanked by a 43 bp 5' UTR and a 172 bp 3' UTR. The encoded 132 amino acids of pig I-FABP with a molecular weight of approximately 15 kDa shared a high sequence identity of 68%-85% with those of other species. In addition, the phylogenetical analysis also indicated that the pig I-FABP was in the same branch with those of other species. The tissue-specific expression of pig I-FABP was measured by Northern hybridization and semi-quantitative RT-PCR. The results demonstrated that pig I-FABP mRNA was extensively present in various tissues, but I-FABP transcript of approximately 620 bp was more abundant in intestine than in other tissues.

Amino Acid Sequence↗

PubMed2006

Optimal multiple trait selection for multiple linked quantitative trait loci.

A method was developed to optimize selection on multiple traits with multiple quantitative trait loci (QTLs) over multiple generations. The basis of the method was to replace in the objective function the genotypic value of a single trait with an aggregate genotypic value of multiple traits weighted by their corresponding economic weight, and to maximize the weighted sum of the selection response in the planning horizon. The optimization was formulated as a multiple stage optimal control problem and solved by a forward and backward iteration cycle. The practical utility of this method was illustrated in an example of pig breeding population, in which the number born alive (NBA) and days to 100 kg (D100) were used as parameters. The selection response of this method was compared with standard QTL selection and regular best linear unbiased prediction (BLUP) selection. Results showed that optimal selection achieved greater selection response than either standard QTL or regular BLUP selections. The influence of economic weight to optimal selection was significant, and the optimization was better as the economic weight of D100 increased. Optimal selection increased the total selection response by two ways: 1) it sacrificed some QTL responses during early generations and 2) it put more emphasis on D100. Optimal cumulative discounted selection gave more weight to D100 than optimal terminal selection in the longer generations.

Algorithms↗

PubMed2006

Optimizing selection on multiple identified quantitative trait loci in population with overlapping generations.

A method was developed to model and optimize selection on multiple identified quantitative trait loci (QTLs) and polygenic estimated breeding value, in order to maximize a weighted sum of cumulative response to selection over multiple years in a population with overlapping generations. The model allows for a population with multiple sex-age classes, different number of age class between sires and dams, and varied genetic contribution of the age class. The optimization problem was formulated as a multiple-stage optimal control problem and solved by a forward and backward iteration loop. The practical utility of this method was illustrated in an example of pig breeding population with overlapping generations. The selection response of this method was compared with standard QTL selection and conventional best linear unbiased prediction (BLUP) selection. Simulation results show that optimal selection achieved greater selection response than either standard QTL or conventional BLUP selections. The influence of population structure on optimal selection was significant. Optimal QTL selection and standard QTL selection were more favorable in a population with overlapping generations than discrete generations, and obtained more benefits relative to conventional BLUP selection in a population with overlapping generations. Optimal QTL selection relative to conventional BLUP selection is also more favorable following increase of genetic contribution of two-year-old boars and sows in a population with overlapping generations.

Algorithms↗

PubMed2006

Sequence characterization, tissue-specific expression and polymorphism of the porcine (Sus scrofa) liver-type fatty acid binding protein gene.

In this study, the full-length cDNA of porcine liver-type fatty acid binding protein gene (L-FABP) was obtained by the rapid amplification of cDNA ends (RACE). The nucleotide sequence and the predicted protein sequence share a high sequence identity with their mammalian counterparts. Semi-quantitative RT-PCR revealed that porcine L-FABP gene is expressed in all twelve tissues studied, but a transcript is more abundant in liver and small intestine than in other tissues. The part genomic DNA of the porcine L-FABP gene was amplified by PCR. The coding region of the pig L-FABP gene is organized in four exons and spans an approximate 2.62 kb genomic region. Comparative sequencing of four pig breeds revealed a C-->T single nucleotide polymorphism (SNP) within exon 2. The allele and genotype frequencies differed significantly between indigenous Chinese Zang, Dahe, and Yanan pigs with higher frequencies of allele C and genotype CC and Yorkshire pigs with higher frequencies of allele T and genotype TT (P < 0.01). The association analysis suggested that the C-->T polymorphism was associated with intramuscular fat content, indicating that the SNP is a potential molecular marker for intramuscular fat content.

Amino Acid Sequence↗

PubMed2006

[Latest advances on the nomenclature for factors of the SLA class-I system].

A new nomenclature system for the SLA class-I system based on DNA sequencing and phylogenetic analysis has been published recently. The naming conventions of SLA class-I loci, allele groups, alleles and haplotypes are particular represented, and the requirements for naming a new allele are also recapitulatively described in this paper. Considering the nomenclature system of SLA class-I, it will has important significance towards human transplantation immunology, swine immunogenetics and breeding for pig disease resistance in the future.

Alleles↗

PubMed2005

Genetic diversity and origin of Chinese cattle revealed by mtDNA D-loop sequence variation.

To determine the origin and genetic diversity of Chinese cattle, we analyzed the complete mtDNA D-loop sequences of 84 cattle from 14 breeds/populations from southwest and west China, together with the available cattle sequences in GenBank. Our results showed that the Chinese cattle samples converged into two main groups, which correspond to the two species Bos taurus and Bos indicus. Although a dominant lineage was clearly discerned in both B. taurus and B. indicus mtDNAs, network analysis of the lineages in each of the two species further revealed multiple clades that presented regional difference. The B. taurus samples in China could be grouped into clades T2, T3, and T4, whereas B. indicus harbored two clades I1 and I2. Age estimation of these discerned clades showed a time range of 14,100-44,500 years before present (YBP). The phylogenetic pattern of Chinese cattle was consistent with the recently described cattle matrilineal pool from northeast Asia, but suggested that B. indicus contributed more to the cattle from south and southwest China. The genetic diversity of Chinese cattle varied among the breeds studied.

Animals↗

PubMed2005

[Growth differentiation factor 9 gene and its role in reproduction.].

Growth differentiation factor 9 (GDF9) secreted by oocyte is essential for follicular growth and differentiation. This review introduced the structure, function and regulation of GDF9, as well as the cloning and structure, developmental expression, mapping and polymorphism of GDF9 gene. The relationship between GDF9 gene and reproductive performance was also discussed in mammals.

Animals↗

PubMed2005

[Study on mitochondrial DNA genetic polymorphism of some yak breeds in China].

This study determined yak's complete sequence of mitochondrial DNA control region (D-loop) of 35 individuals in 5 yak breeds at the first time. The result showed that the length of D-loop in yak was 891 -895 bp. Content of nucleotide T, C, A, G were 28.5%, 25.3%, 32.5% and 13.7% respectively. There were 55 polymorphic sites (6.16% in total analyzed sites). The transition,transversion and insertion/deletion were found in this region.24 haplotypes was defined in this study, in which haplotype H4 and H6 were major haplotypes of Chinese yak. The distribution of all the haplotypes among the breeds was disequilibrium. The average diversity of haplotypes were 0.9697 +/-0.0180, indicating the abundance of haplotypes of yak's D-loop. The average nucleotide difference and the nucleotide diversity in Chinese yak breeds were 10.936% and 1.231% respectively. Nucleotide divergence and Kimura 2-parameter distance between yak breeds were 0.760% -2.155%, and 0.000-0.029 respectively. The results indicated that the genetic diversity of Chinese yak was very abundant. Analysis of molecular variance and network construction results indicated that there was significant divergence among Chinese yak breeds. The network construction indicated that Chinese yak had been divided into 2 types and had probably 2 maternal origins or 2 domesticated places.

Animals↗

PubMed2005

[The genetic effects of MyoG gene].

The PCR-RFLP technique was applied in this study to analyze the MspI polymorphism in the 3-UTR of MyoG gene. The relationship between different genotypes and corresponding traits and the genetic effects of different allele were analyzed. The results indicated that the N allele has highly significant genetic effects in improving carcass lean percent and the loin eye area, and decreasing the fat content (P<0.01). But no significant influence was found to the FOM carcass traits (P>0.05). As meat quality traits being considered, the N allele highly significantly decreased the pH value, meat color, intramuscular fat content, increased the drip loss (P<0.01) and caused the worse of meat quality. When considering genetic values of different traits, it was found that the N allele had additive effects of 3.929% to carcass lean percent, 2.0985 cm2 to loin eye area, -3.0245% to the fat content, -0.167 to the pH1 value, 0.558% to the drip loss and -0.963% to intramuscular fat content. But no effect was observed to the carcass grading traits.

Alleles↗

PubMed2005

[The genetic diversity and genetic effects of Myf-6 gene in different pig breeds].

As a member of MRFs, Myf-6 gene plays an important role in the progress of myogenesis. The PCR-RFLP technique was applied in this study to analyze the distribution of Myf-6 gene in 12 different pig breeds and hybrid breeds. The genetic effects of Myf-6 gene on muscle fiber, carcass quality, carcass grading traits and meat quality traits were analyzed. The results indicated that: The polymorphisms of Myf-6/Ava I genotypes (intron1) were not abundant. Most of Chinese native pigs were AA homozygotes. B allele can be found only in foreign pig breeds and hybrid pigs originated from foreign pig breeds. Although no BB individuals were found in the experiment, the carcass lean percent of AB individuals (50.344 %) was significantly higher than that of AA individuals (45.875 %)(P<0.01), the loin eye area of AB individuals (27.097 cm2) was significantly larger than that of AA individuals (22.572 cm2)(P<0.01), and the carcass fat content of AB individuals (39.889 %) was significantly lower than that of AA individuals (44.503 %)(P<0.01). That means that the B allele can increase carcass lean percent and loin eye area, and decrease the carcass fat content, thus cause better carcass quality. No significant effects of the genotypes were found on the muscle fiber, FOM carcass grading traits and meat quality traits (P>0.05).

Alleles↗