Biomedical subjects

Xiang-Long Li

Publications and source records attributed to Xiang-Long Li.

7 recordsLinked to original sources

PubMed2006

Evolution and differentiation of MSHR gene in different species.

Coat color offers some prospects for evolutionary studies due to its large amount of presumably adaptive coat color variation and conserved genetic mechanisms of generating different coat colors in different species. Melanocyte-stimulating hormone receptor (MSHR) gene is responsible for intraspecific and interspecific color variation in mammals and birds. A total number of 206 MSHR gene sequences belonging to 84 species, 58 genera, and 20 families were analyzed to investigate its evolution and differentiation in different species. Most of the species have 954 bp and stop codon TGA. Species in Callithrix and Callimico have a stop codon mutation from TGA to TGG and elongate 81 bp with TAG as stop codon. Species in Phasianidae, Fringillidae, and Lemuridae also use TAG as stop codon. The Sus scrofa had an insertion of AACCAGACC encoding Asn-Gln-Thr from 85 to 93 bp. In Bovidae, a brown strain of cow with 966 bp due to the 12-bp duplication of GGCATTGCCCGG from 670 to 681 bp encoding for Gly-Ile-Ala-Arg was found. Teiidae has the smallest number of total mutations (6), silent mutations (3), nonsynonymous mutations (3), average number of nucleotide differences (1.519), synonymous nucleotide diversity (pi(s) = 0.0030), and nonsynonymous nucleotide diversity (pi(a) = 0.0029), and Hominidae, Lemuridae, Canidae, and Teiidae have higher ratio of pi(a)/pi(s) (0.537-0.973). The reconstructed phylogenetic tree of MSHR gene of families is basically consistent with the taxonomy of National Center for Biotechnology Information.

Animals↗

PubMed2006

SNP identification and analysis in part of intron 2 of goat MSTN gene and variation within and among species.

Part of intron 2 of the myostatin (MSTN) gene of 140 goats from 24 populations and 38 sheep from 8 breeds were sequenced, and similar sequences of different species from Gene bank were also obtained to study MSTN diversity within and among species. The results indicated that there were seven polymorphic sites in the sequenced region of goat, which have not been separated by recombination (or recurrent mutation), presented complete linkage disequilibrium, and could be sorted into three haplotypes. There was no polymorphic site in the sequenced region of sheep. The haplotype diversity, nucleotide diversity, and average number of single nucleotide polymorphism (SNP) differences of goats from the South group are higher than those of North group, and the corresponding value of the Foreign group is also higher than that of Chinese. The genetic differentiation (0.7558) between the Foreign and Chinese group is significant. There are two main haplotypes of the MSTN intron 2 in the goat, which may represent two ancestral types, in support of the theory that domestic goats in the world mainly originated from two ancestors based on morphology, history, archaeology, and molecular markers. The sequence differences of the MSTN intron 2 among species are greater than those within species.

Animals↗

PubMed2006

Study on tandem repeat sequence variation in sheep mtDNA D-loop region.

The 75-nt-long tandem repeat sequence in the control region of mtDNA of 77 individuals, of which 69 were from different indigenous sheep breeds in China and 8 were from imported breeds, was sequenced and analyzed to investigate the origin and differentiation of Chinese indigenous sheep breeds and also the genetic diversities and relationships among them. A total of 28 variable sites were detected within 309 repeated sequences, among which 7 sites were singleton variable sites with two variants, 1 site was a singleton variable site with three variants, and 20 sites were parsimony informative sites with two variants. A total of 63 haplotypes were sorted from 28 polymorphic sites, among which two main and basic haplotypes, namely, Hap 1 and Hap 3 were present at a much higher proportion, at 12.94% and 30.42%, respectively. It could be inferred that Chinese indigenous sheep breeds originated from two maternal ancestors because of the maternal inheritance characteristics of the mtDNA. Altay sheep and Kazakstan sheep are closely related and do not differentiate significantly. Mongolian sheep and Ujumuqin sheep also share a close relationship. Tibetan sheep, Mongolian sheep, and Ujumuqin sheep have lower genetic diversity than Altay sheep and Kazakstan sheep.

Animals↗

PubMed2006

[Study on mtDNA D-loop of Chinese main indigenous sheep breeds using PCR-RFLP].

The polymorphism of mtDNA D-loop of 83 individuals from 9 Chinese indigenous sheep breeds and 2 imported sheep breeds were studied with 5 endonucleases, Hinf I, Msp I, Sau3A I, Xsp I and Taq I, using PCR-RFLP. The results indicated that there existed two basic haplotypes in the region of mtDNA D-loop. It could be inferred that Chinese indigenous sheep breeds originated from two maternal ancestors. The averaged polymorphic degree (Pi value=0.0421%) of mtDNA D-loop showed that the genetic diversity of mtDNA of Chinese indigenous sheep breeds was very poor.

Animals↗

PubMed2004

Study on SNP of melanocyte stimulating hormone receptor gene in several Chinese indigenous sheep breeds using DHPLC.

Single nucleotide polymorphism (SNP) of melanocyte stimulating hormone receptor (MSHR) gene was studied by sequencing and denaturing high performance liquid chromatography (DHPLC) in Mongolian sheep, Kazakstan sheep, Tan sheep and Tibetan sheep. The results showed that there is a mutation at position 317 (T317C) within the length of 415bp and the DHPLC is a high-throughput and simple method for screening this mutation. The heterozygote (TC) with shoulder peak could be detected quickly at the first time of DHPLC, and two homozygotes (TT or CC) could be discriminated easily through two times of DHPLC when each homozygous DNA was mixed with a known homozygous reference sample at the second time of DHPLC. All of the populations for this site are in Hardy-Weinberg equilibrium. The results also indicated that Mongolian sheep and Kazakstan sheep had close relationship, Tibetan sheep and Tan sheep had close relationship. The relationship among breeds was consistent with that of microsatellite DNA.

Animals↗

PubMed2004

Study on polymorphisms of microsatellites DNA of six Chinese indigenous sheep breeds.

The polymorphisms of 17 microsatellites loci of six indigenous sheep breeds, including Mongolian sheep, Ujumuqin sheep, Kazakstan sheep, Aletai sheep and Tibetan sheep, were studied using polypropylene gel electrophoresis in order to investigate their genetic diversity,origin, differentiation and relationships. The results indicated that there was a significant difference in genetic diversity between different loci (P < 0.01). There was no significant difference in PIC, Fis and observed heterozygosity (Obs. Het) among populations (P > 0.05), but a significant difference in gene diversity and expected heterozygosity (Exp. Het) (P < 0.05). Chinese indigenous sheep breeds had similar genetic diversity as those from Europe,but with higher inbreeding coefficient. It could be inferred from the cluster of individuals and populations that Chinese indigenous sheep breeds might originate from two ancestors. The cluster of populations showed that Mongolian sheep and Ujumuqin sheep had close relationship and did not differentiate obviously. Mongolian sheep and Tibetan sheep had far relationship and differentiated significantly. Aletai sheep differentiated from Kazakstan sheep but not significantly. Tan sheep,Aletai sheep and Tibetan sheep also had close relationships. The Fst of Chinese indigenous sheep breeds was close to some Spanish sheep breeds,but much smaller than that of other European sheep breeds. More loci and samples should be studied in the future in order to obtain more accurate results.

Animals↗

PubMed2003

[Studies of genetic structure of genetic relationship of Boer goat and its upgrading offspring to Tangshan Diary goat].

The gentic structure and relationship of Boer goat and its upgrading offspring to Tangshan Dairy goat were studied using the RAPD maker and some statistical program, such as POPGENE, PHYLIP and SPSS. The results indicated that there were the similar percentage of polymorphic loci, observed and effective number of alleles, gene diversity between Boer goat and its upgrading offspring, especially higher upgrading offspring. With the increasing of upgrading, the difference of population structure decreased as well as the genetic distance and differentiation among higher upgrading offspring and their improving parental, but gene flow and genetic identity increased. There was a close genetic relationship between higher upgrading offspring and Boer goat.

English Abstract↗