[Effect study of white locus (I) on coat color inheritance in Chinese native pig breeds].

The classical White (I) locus is one of the important pig coat color hereditable loci,which is homologous to KIT gene. In this study,PCR-RFLP and PCR-SSCP analysis were commanded on the Intron 17 and 18 nucleotide sequences of KIT gene. The tested results showed that the substitution mutation (G-->A) of Intron 17 was found in white pigs, including Wuzhishan pigs (white), Landrace and Large White,and its genotype (AB) frequency was 1.1 and 0.8 respectively. The genotype frequency was uniformly 0 in the other native pig breeds. Similarly,the deleted mutation (AGTT) of Intron 18 was also found in the same white pigs,its genotype (,AA) frequency was 1.1 and 0.93 separately,while in the other native pig breeds was 0. Accordingly it was considered that KIT gene was an important factor regulating the white coat color genotype, and the classical I locus (KIT gene) was epistatic to the other genetic coat color loci. On the other hand,although the native pig breed Rongchang Pig is similar to Landrace and Large White in phenotype (white coat color), the mutation status found in them was absolutely distinct. So it is presumed that the coat color genetic system of Chinese native pig breeds was different from that of imported breeds.

Shi KR ，Wang AG ，Li N ，Deng XM ... -  《-》

Chinese white Rongchang pig does not have the dominant white allele of KIT but has the dominant black allele of MC1R.

The mast/stem cell growth factor receptor (KIT) and melanocortin receptor 1 (MC1R) mutations are responsible for coat color phenotypes in domestic pigs. Rongchang is a Chinese indigenous pig breed with a white coat color phenotype. To investigate the genetic variability of the KIT and MC1R genes and their possible association with the coat color phenotype in this breed, a gene duplication and splice mutation of KIT were diagnosed in a sample of 93 unrelated Rongchang animals. The results show that Rongchang pigs have a single copy of KIT without the splice mutation at the first nucleotide of intron 17, indicating that the dominant white I allele of KIT is not responsible for their white phenotype. The KIT mRNA and MC1R coding sequences were also determined in this breed. Three putative amino acid substitutions were found in the KIT gene between Rongchang and Western white pigs, their association with the Rongchang white phenotype remains unknown. For the MC1R gene, Rongchang pigs were demonstrated to have the same dominant black allele (E(D1)) as other Chinese breeds, supporting the previous conclusion that Chinese and Western pigs have independent domestication origin. We also clarified that the Rongchang white phenotype was recessive to nonwhite color phenotypes. Our results provide a good starting point for the identification of the mutations underlying the white coat color in Rongchang pigs.

Lai F ，Ren J ，Ai H ，Ding N ，Ma J ，Zeng D ，Chen C ，Guo Y ，Huang L ... -  《JOURNAL OF HEREDITY》

[Studies of the relationship of melanocortin receptor 1(MC1R) gene with coat color phenotype in pigs].

Although coat color in pigs has no direct relation with economic traits, it affects economic benefit significantly, coat color selection are widely used in pig breeding and production. PCR-Acc II-RFLP, PCR-BspH I-RFLP and PCR-SSCP were used in combination to analyze genotype at MC1R locus among individuals from 16 full-sib pedigrees and 6 Chinese native breeds including Jinhua, Jiaxing Black, Yushan Black, Leping Spotted, Shanggao Spotted and Shengxian Spotted pig. It was found that the Chinese native pig breeds carry a dominant black allele at MC1R at high frequency, this ED1 allele was suggested to be the major allele controlling black coat color in Chinese native pig breed. In addition, the evidence for a new allele was obtained in Shengxian Spotted pigs by PCR-SSCP analysis. It was reconfirmed from the result of pedigree analysis that ED1 was dominant over EP and e, while EP was incompletely dominant over e.

Deng SH ，Gao J ，Ren J ，Chen KF ，Ding NS ，Ai HS ，Lin WH ，Wang WJ ，Liu BS ，Lai FJ ，Huang LS ... -  《-》

A large duplication associated with dominant white color in pigs originated by homologous recombination between LINE elements flanking KIT.

The Dominant White (I/KIT) locus is one of the major coat color loci in the pig. Previous studies showed that the Dominant White (I) and Patch (IP) alleles are both associated with a duplication including the entire KIT coding sequence. We have now constructed a BAC contig spanning the three closely linked tyrosine kinase receptor genes PDGFRA-KIT-KDR. The size of the duplication was estimated at about 450 kb and includes KIT, but not PDGFRA and KDR. Sequence analysis revealed that the duplication arose by unequal homologous recombination between two LINE elements flanking KIT. The same unique duplication breakpoint was identified in animals carrying the I and IP alleles across breeds, implying that Dominant White and Patch alleles are descendants of a single duplication event. An unexpected finding was that Piétrain pigs carry the KIT duplication, since this breed was previously assumed to be wild type at this locus. Comparative sequence analysis indicated that the distinct phenotypic effect of the duplication occurs because the duplicated copy lacks some regulatory elements located more than 150 kb upstream of KIT exon 1 and necessary for normal KIT expression.

Giuffra E ，Törnsten A ，Marklund S ，Bongcam-Rudloff E ，Chardon P ，Kijas JM ，Anderson SI ，Archibald AL ，Andersson L ... -  《MAMMALIAN GENOME》

Relationship among H-FABP gene polymorphism, intramuscular fat content, and adipocyte lipid droplet content in main pig breeds with different genotypes in western China.

H-FABP(Heart fatty acid-binding protein), a member of FABP family, plays an essential role in long-chain fatty acid uptake and metabolic homeostasis. Its role in pig intramuscular fat content remains poorly understood, especially in local pig breeds in western China. In this study, the genetic variations of 5'-upstream region and the second intron in porcine H-FABP gene were investigated by PCR-RFLP in 256 pigs including Duroc, Large White, Landrace, Neijiang, Rongchang, Bamei pig, Hanjiang Black, Hanzhong White, and the wild ones. The effect of H-FABP gene on the IMF content was analyzed by the least square method. Lipid droplet morphology and content in adipocytes cultured from pigs with different H-FABP genotypes, were studied by oil red O staining and a triglyceride assay kit. Results showed a Hinf I -RFLP in these eight pig breeds and wild pigs, among which Large white, Bamei pig, Hanjiang Black, Hanzhong White, and wild pigs presented with low polymorphism while the other breeds had intermediate polymorphism. There was no Hae III or Msp I -RFLPs in the four Chinese local pig breeds tested, but Duroc, Landrace, Large White, Hanzhong White and wild pig had polymorphism. Landrace, Large White and wild pigs had low levels of Hae III- and Msp I -RFLP, whereas others had intermediate polymorphism. H-FABP genotypes significantly affected the IMF content (P<0.05). The IMF content ordered by H-FABP genotypes were HH>Hh>hh, DD<Dd<dd, and AA<Aa<aa. The genetic effect values were 3.89, 3.42, 3.17, 2.27, 2.49, 2.91, 2.28, 2.70, and 2.95, respectively. Fat deposition in adipocytes was stronger in the HH, dd and aa genotypes than in others. The results suggest that porcine meat quality may be improved by increasing the frequency of genotype aa-dd-HH in pig breeds.

Pang WJ ，Bai L ，Yang GS 《-》