• Asian-Australasian Journal of Animal Sciences
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• v.22 no.3
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• pp.336-342
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• 2009

Avian embryos at high altitude are independent of maternal protection against hypoxia, which is contrary to mammals. It is well known that chronic hypoxic exposure at key points can significantly impact on avian development. Tibetan Chicken, a Chinese indigenous breed, living in Tibetan areas with an altitude of 2.2 to 4.1 thousand meters, has an adaptive mechanism to hypoxia. In the present study, fertilized eggs of Tibetan Chicken were incubated under 13% and 21% oxygen concentration. Two lowland chicken breeds, Shouguang Chicken, an indigenous chicken breed in Shandong Province of China, and Dwarf Recessive White Chicken, an imported breed in Beijing, were used as control groups. The embryo mass and some organs such as brain, heart, liver, stomach and eye weight in the three species were measured at Hamburger-Hamilton stage 39, 41, 43 and 45 under hypoxic and normal conditions. The results showed that in hypoxia Tibetan Chicken significantly differed from the two lowland chicken breeds in embryo mass at Hamburger-Hamilton stage 41, 43 and 45 (p<0.01). In particular, Dwarf Recessive White Chicken and Shouguang Chicken showed retarded growth in hypoxic incubation (p<0.01), whereas Tibetan Chicken showed no significant difference between hypoxic and normal conditions (p>0.05). In addition, heart and the other organs showed different susceptibility to hypoxia at the studied stages. In conclusion, chronic hypoxia induced a change in the embryo development of the three different species and Tibetan Chicken showed adaptation to hypoxia. Of note, the embryo developmental physiology of Tibetan Chicken in response to hypoxia will shed light on the process of physiological acclimation or evolutionary adaptation as well as the study of clinical disease.

• Animal Bioscience
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• v.37 no.1
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• pp.28-38
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• 2024

Objective: Tibetan chickens, which have unique adaptations to extreme high-altitude environments, exhibit phenotypic and physiological characteristics that are distinct from those of lowland chickens. However, the mechanisms underlying hypoxic adaptation in the liver of chickens remain unknown. Methods: RNA-sequencing (RNA-Seq) technology was used to assess the differentially expressed genes (DEGs) involved in hypoxia adaptation in highland chickens (native Tibetan chicken [HT]) and lowland chickens (Langshan chicken [LS], Beijing You chicken [BJ], Qingyuan Partridge chicken [QY], and Chahua chicken [CH]). Results: A total of 352 co-DEGs were specifically screened between HT and four native lowland chicken breeds. Gene ontology and Kyoto encyclopedia of genes and genomes enrichment analyses indicated that these co-DEGs were widely involved in lipid metabolism processes, such as the peroxisome proliferator-activated receptors (PPAR) signaling pathway, fatty acid degradation, fatty acid metabolism and fatty acid biosynthesis. To further determine the relationship from the 352 co-DEGs, protein-protein interaction network was carried out and identified eight genes (ACSL1, CPT1A, ACOX1, PPARC1A, SCD, ACSBG2, ACACA, and FASN) as the potential regulating genes that are responsible for the altitude difference between the HT and other four lowland chicken breeds. Conclusion: This study provides novel insights into the molecular mechanisms regulating hypoxia adaptation via lipid metabolism in Tibetan chickens and other highland animals.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.8
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• pp.1047-1052
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• 2004

The genomes of Chinese native chicken populations were screened using microsatellites as molecular markers. A total of, 528 individuals comprisede12 Chinese native chicken populations were typed for 7 microsatellite markers covering 5 linkage groups and genetic variations and genetic distances were also determined. In the 7 microsatellite loci, the number of alleles ranged from 2 to 7 per locus and the mean number of alleles was 4.6 per locus. By using fuzzy cluster, 12 Chinese native chicken populations were divided into three clusters. The first cluster comprised Taihe Silkies, Henan Game Chicken, Langshan Chicken, Dagu Chicken, Xiaoshan Chicken, Beijing Fatty Chicken and Luyuan Chicken. The second cluster included Chahua Chicken, Tibetan Chicken, Xianju Chicken and Baier Chicken. Gushi Chicken formed a separate cluster and demonstrated a long distance when comparing with other chicken populations.

• Asian-Australasian Journal of Animal Sciences
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• v.17 no.7
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• pp.903-909
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• 2004

The variability of mtDNA hypervariable segment I (HVS I) sequences was investigated in a total of 48 birds belonging to 12 Chinese native chicken breeds. Sixteen haplotypes were identified from 35 polymorphic nucleotide sites which accounted for 6.4% of a sequenced 544 bp fragment. Diversity analysis of the haplotypes showed that Tibetan, Langshan and Henan cockfight chicken had only one haplotype, while ancient haplotypes existed in Taihe silky and Chahua chicken. Phylogenetic analysis of the haplotypes suggested that Chinese native chicken breeds shared 5 maternal lineages and some breeds would share the same maternal lineage, regardless of their external features and ecological types. Both divergent and phylogenetic analysis of the haplotypes indicated the close genetic relationships between the Chinese native chicken breeds and G. g. gallus and G. g. spadiceus from different areas, which implied that G. g. gallus and G. g. spadiceus were the original ancestors of the Chinese native chicken breeds.

• Asian-Australasian Journal of Animal Sciences
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• v.19 no.2
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• pp.153-159
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• 2006

A 2,656 bp fragment of chicken ghrelin gene was cloned and SNPs were detected by PCR-RFLP and Allele Specific PCR (ASP) in 12 Chinese indigenous chicken breeds and a commercial chicken population. The results showed that there were 23 base variations and an amino acid change ($Gln{\rightarrow}Arg$) in cloned chicken ghrelin gene. Three SNPs were confirmed in 13 populations and associations between this gene and growth traits of Tibetan chicken (TC) and Recessive White chicken (RW) were investigated. The results of haplotype analysis revealed that 26 haplotype genotypes were composed of eight haplotypes. The results of $x^2$ tests indicated that there were significant differences between genotypes or haplotype genotype frequencies in some of the breeds or sexes at 0.05 or 0.01 levels. The results of ANOVA revealed that there were significant differences between genotypes or haplotype genotypes on some growth traits of TC and RW chicken breeds at 0.05 or 0.01 levels. Multiple comparisons showed that there were significant associations between genotype CT at site 71 and some growth traits of two chicken breeds and between genotype AG at site 1,215 and body weight at 16 wk of two chicken breeds, and there was a significant association between haplotype genotype CAA/CAG and body weight and shank girth at 16 wk of two chicken breeds.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.7
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• pp.942-948
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• 2005

New polymorphism of major histocompatibility complex B-G genes was investigated by amplification and digestion of a 401bp fragment including intron 1 and exon 2 using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique with two restriction enzymes of Msp I and Tas I in eight breeds of Chinese indigenous chickens and one exotic breed. In the fragment region of the gene, three novel single nucleotide polymorphisms (SNPs) were detected at the two restriction sites. We found the transition of two nucleotides of A294G and T295C occurred at Tas I restriction site, and consequently led to a non-synonymous substitution of asparagine into serine at position 54 within the deduced amino acid sequence of immunoglobulin variable-region-like domain encoded by the exon 2 of B-G gene. It was observed at rare frequency that a single mutation of A294G occurring at the site, also caused an identical substitution of amino acid, asparagine 54-to-serine, to that we described previously. And the transversion of G319C at Msp I site led to a non-synonymous substitution, glutamine 62-to-histidine. The new alleles and allele frequencies identified by the PCR-RFLP method with the two enzymes were characterized, of which the allele A and B frequencies at Msp I and Tas I loci were given disequilibrium distribution either in the eight Chinese local breeds or in the exotic breed. By comparison, allele A at Msp I locus tended to be dominant, while, the allele B at Tas I locus tended to be dominant in all of the breeds analyzed. In Tibetan chickens, the preliminary association analysis revealed that no significant difference was observed between the different genotypes identified at the Msp I and Tas I loci and the laying performance traits, respectively.