Molecular characterization, expression analysis and association study with meat quality traits of porcine TTID gene.

Titin immunoglobulin domain protein (TTID) is localized to the Z-line and binds to alpha-actinin, gamma-filamin. It plays an indispensable role in stabilization and anchorage of thin filaments. In this study, the full-length cDNA sequence was isolated by the reverse transcription-polymerase chain reaction (RT-PCR) and the rapid amplification of cDNA ends (RACE). The TTID sequence was deposited into the Genbank under the accession no. DQ157551. The deduced protein of 499 amino acids showed 93 % identity to the corresponding human and rat sequence. Semi-quantitative RT-PCR revealed porcine TTID gene was expressed highest level in skeletal muscle, at second-highest level in the heart, but only low expression in the fat was detected. Bioinformatics analysis shows the molecular weight of the TTID protein is 55.747 kD with a PI of 9.26. It contains the protein function site of two potential Ig-like domain profiles, six N-myristoylation sites, six potential Casein kinase II phosphorylation sites, eight protein kinase C phosphorylation sites, three N-glycosylation sites, a tyrosine kinase phosphorylation site and a cell attachment sequence site. No putative base substitution was detected in the coding region by comparing sequences of Large White, Landrace and Meishan pig breeds. A T978C single nucleotide polymorphism in the intron 6 of porcine TTID gene was detected by a HinfI PCR-restriction fragment length polymorphism. Study showed allele frequency differences among four purebreds. Association of the genotypes with meat quality traits showed that different genotypes of porcine TTID gene were significantly associated with meat pH (m.Biceps Femoris) (P < 0.05), meat color value (m.longissimus Dorsi) (P < 0.05) and Water Moisture (m.longissimus Dorsi) (P < 0.05).

Imprinting analysis of porcine MAGEL2 gene in two fetal stages and association analysis with carcass traits.

Imprinted genes play an essential role in the regulation of fetal growth, development and function of the placenta, however only a limited number of imprinted genes have been studied in swine. In this study, we cloned and characterized porcine MAGEL2 (melanoma antigen-like gene 2), and also identified its imprinting status during porcine fetal development. The complete open reading frame (ORF) encoding 1,193 amino acids was isolated and two single nucleotide polymorphisms (SNPs) (g.2592A>C and g.3277T>C) in the coding region were identified. The reciprocal Yorkshire×Meishan F1 hybrid model and the RT-PCR/RFLP method were used to detect the imprinting status of porcine MAGEL2 gene at two developmental stages of day 30 and 65 of gestation. Imprinting analysis showed that porcine MAGEL2 was paternally expressed in day 65 fetal tissues, including heart, liver, spleen, lung, kidney, stomach, small intestine, skeletal muscle, brain and placenta. Interestingly, we observed an imprinting variance of MAGEL2 gene in 30 dpc fetuses produced by the cross of Yorkshire boar×Meishan sow, in which seven heterozygous fetuses were monoallelically expressed from the paternal allele but two were biallelically expressed from both the paternal and maternal alleles. Association analysis in a Yorkshire×Meishan F2 resource population showed that the mutation of g.2592A>C was significantly associated with dressed carcass percentage (P<0.05) and buttock fat thickness (P<0.05). Our results suggest that MAGEL2, as a novel imprinted gene in pig, might be a candidate gene affecting carcass traits and could provide important information for the functional study of imprinted genes during porcine development.

Molecular characterization and association analysis of porcine adipose triglyceride lipase (PNPLA2) gene.

The adipose triglyceride lipase (PNPLA2, also known as ATGL) is a novel triacylglycerol (TG) lipase which specifically removes the first fatty acid from the triglyceride molecule generating free fatty acid and diglyceride (DG) in mammalian cells. Here we describe the molecular characterization of the porcine ATGL gene. The full-length cDNA sequence contains a 1,461 bp open reading frame encoding a protein of 486 amino acids with a calculated molecular mass of 53.2 kDa and an isoelectric point of 7.90. The porcine ATGL protein shares high identity with other mammalian ATGL. The ATGL gene contains 9 coding exons, spans approximately 6 kb. The porcine ATGL mRNA was expressed predominantly in backfat, mildly in muscle, small intestine and heart, and almost absent in liver, spleen, lung, stomach, kidney and ovary. Statistical analysis showed the ATGL gene polymorphism (G/A(392)) was different between Chinese indigenous and introduced commercial western pig breeds, and was highly associated with almost all the fat deposition and carcass traits, including subcutaneous fat thickness, viscera adipose tissue, lean percentage, loin eye traits and even rib numbers.

Molecular characterization and expression patterns of Lbx1 in porcine skeletal muscle.

Ladybird-like genes were recently identified in mammals. The first member characterized, Lbx1, is expressed in developing skeletal muscle and the nervous system. However, little is known about the porcine Lbx1 gene. In the present study, we cloned and characterized Lbx1 from porcine muscle. RT-PCR analyses showed that Lbx1 was highly expressed in porcine skeletal muscle tissues. And we provide the first evidence that Lbx1 has a certain regulated expression pattern during the postnatal period of the porcine skeletal muscle development. Lbx1 gene expressed at higher levels in biceps femoris muscles compared with masseter, semitendinosus and longissimus dorsi muscles in Meishan pigs. Phylogenetic tree was constructed by aligning the amino acid sequences of different species. Moreover, single nucleotide polymorphism (SNP) scanning in the Lbx1 genomic fragment identified two mutations, g.752A>G and g.-1559C>G. Association analysis in our experimental pig populations showed that the mutation of g.752A>G was significantly associated with loin muscle area (P<0.05) and internal fat rate (P<0.05). Our results suggest that the Lbx1 gene might be a candidate gene of carcass traits and provide useful information for further studies on its roles in porcine skeletal muscle.

[Association of porcine ATF4 gene polymorphism and production traits and analysis of gene expression].

In order to understand the function of gene ATF4 and identify new DNA markers involved in pig production traits, the cDNA fragment of porcine ATF4 was cloned and sequenced. Sequence comparison revealed an A159G substitution downstream of the initiation codon (ATG). We then carried out PCR-AluⅠ-RFLP analysis in Large white, Landrace, Tongcheng and Meishan pigs, followed by association analysis in F2 "Large white ×Meishan" resource family. In all the individuals tested, Large White and Landrace pigs possessed the AA genotype, while Meishan and Tongcheng pigs pos-sessed the GG genotype. Association analysis in F2 resource family showed that this site was highly associated with buttock fat thickness (BFT) (Pamp;0.01) and had significant effect on thorax-waist fat thickness (TFT), average backfat thickness (ABT), loin eye height (LEH), and loin eye area (LEA)(Pamp;0.05). Real-time PCR was used to analyze the expression patterns of porcine ATF4 gene in longissimus dorsi at different development stages of Large White and Meishan pigs. The results showed that the gene expression levels of ATF4 were low 65 days after conception and 3 days after birth, but no signifi-cant differences were observed in both breeds. Meanwhile, the expression levels of porcine ATF4 gene were up-regulated 60 days and 120 days after birth in both breeds and the expression level in Meishan pigs was obviously higher than that in Large White pigs. These data could lay the foundation for further study on the molecular mechanism of porcine ATF4 gene in lipid metabolism.

[Polymorphism in coding region of pig PRDX6 gene and its genetic effects analysis].

PRDX6, a member of antioxidant protein superfamily, plays an important role in oxidative stress, catabolism of lipids and phospholipid lipisomes. Therefore, we used PRDX6 as an important candidate gene for meat quality according to its physiological and biochemical function. Partial coding sequence of porcine PRDX6 was isolated and two potenial SNPs, one at 417 bp (C/T) and the other at 423 bp (A/G), were found in the fourth exon by comparison of the obtained sequence from different pig breeds. In order to explore the relationship between PRDX6 polymorphism and meat quality, genetic variation and trait association of these two SNPs were separately performed in 6 purebred pig population and 247 F2 "Large White x Meishan" resource population by pyrosequencing. The results showed that allele C was predominant in western pig breeds, while allele T was predominant in Chinese indigenous breeds at 417 bp (C/T). This SNP was significantly associated with the intramuscular fat and water moisture (P < 0.05). The A/G mutation at 423 bp was significantly associated with drip water rate, water holding capacity, intramuscular fat, and water moisture (P < 0.05). Allele A was predominant in western pig breeds, while allele G was predominant in Chinese indigenous breeds. These two SNPs were likely to be important markers affecting meat quality traits (especially the muscle tenderness).

Molecular characterization, expression profile and association analysis with carcass traits of porcine LCAT gene.

The lecithin cholesterol acyltransferase gene (LCAT) plays an important role in lipoprotein metabolism, especially in the process termed 'reverse cholesterol transport'. In this study, we obtained the 1,434 bp mRNA sequence of porcine LCAT including the full coding region and encoding a protein of 472 amino acids. The sequence was deposited into the GenBank under the accession no. EU717835. The genomic sequence of this gene which contains six exons and five introns, is 3,712 bp in length (GQ379050). Bioinformatic analysis of the 5' regulatory region has revealed that some transcription factor Sp1, AP-1, AP-2 and NF-kappaB were represented in this region. Tissue expression analysis showed that the porcine LCAT gene is ubiquitously expressed in all examined tissues. Phylogenetic tree was constructed by aligning the amino acid sequences of different species. Moreover, we found a single nucleotide polymorphism (SNP, C/G266) in intron 1 of the LCAT gene and association analysis showed that it was significantly associated with ratio of lean to fat (P < 0.05), caul fat weight (P < 0.01), leaf fat weight (P < 0.05), carcass length (P < 0.05) and bone percentage (P < 0.05). Our study will lay the groundwork for the further investigations on the detailed physiological function of LCAT in pig models.

Molecular characterization, expression profile and association analysis with fat deposition traits of the porcine APOM gene.

Apolipoprotein M (APOM), a novel apolipoprotein presented mostly in high-density lipoprotein (HDL) in plasma, is involved in lipid and lipoprotein metabolism. Through comparative mapping, we have mapped this gene to SSC7 p1.1 in which many QTLs affecting fat deposition traits have been reported. As a candidate gene for fat deposition traits, in this study, we obtained the 742-bp mRNA sequence of porcine APOM including the full coding region and encoding a protein of 188 amino acids. The sequence was deposited into the GenBank under the accession no. DQ329240. Semi-quantitative RT-PCR results showed that the porcine APOM gene is expressed predominantly in liver and kidney tissue. The genomic sequence of this gene which contains six exons and five introns, is 3,621 bp in length (DQ272488). Bioinformatic analysis of the 5' regulatory region has revealed that classical TATA-box element and species conserved Hepatocyte nuclear factor-1a (HNF-1alpha) biding site were represented in this region. A G2289C single nucleotide polymorphism (SNP) in the intron 2 of porcine APOM gene detected as an Eco130I PCR-restriction fragment length polymorphism (PCR-RFLP) showed allele frequency differences among three purebreds. Association of the genotypes with fat deposition traits showed that different genotypes of porcine APOM gene were significantly associated with leaf fat weight (P < 0.05), backfat thickness at shoulder (P < 0.05), backfat thickness at thorax-waist (P < 0.05), backfat thickness at buttock (P < 0.01) and average backfat thickness over shoulder, thorax-waist and buttock (P < 0.01).

[Polymorphism in exon 2 of pig FIT1 gene and its association with fat-deposition-related traits].

In pig industry, fat deposition related traits such as back fat thickness and fat rate are of great economic importance. Thus, research on genes related with fat deposition can offer many useful values theoretically and practically. Gene FIT1 (Fat-inducing transcript 1) plays an important role in packaging lipid droplets. Here, we used FIT1 gene as the candidate gene for fat deposition. Sequence comparison revealed that an insertion/deletion mutation occurred at 590~595 bp of the second exon. We then carried out PCR-SSCP analysis followed by association analysis in F2 "Large white xMeishan" resource family. In all the individuals tested, all Meishan pigs possessed the insertion, which was designated allele A, while most Large white pigs possessed the deletion and was named as allele B. Association analysis in F2 resource family showed that this site was highly associated with fat percentage (FP), 6-7 rib fat thickness (RFT), buttock fat thickness (BFT), leaf fat weigh (LFW), total internal fat weigh (TFW), and internal fat rate (IFR) (Plt;0.01). These results indicated that FIT1 gene may have some important values for application. Further and deep research is necessary for revealing more information on this gene in order to provide a new marker for molecular marker-assisted selection breeding.

Characterization of the porcine differentially expressed PDK4 gene and association with meat quality.

To investigate the differential expression of genes in the skeletal muscle between Yorkshire and Chinese indigenous breed Meishan pigs, suppression subtractive hybridization was carried out and many genes were proved to be expressed significantly different in the two breeds. One gene highly expressed in Meishan but lowly expressed in Yorkshire specific library, shared strong homology with human pyruvate dehydrogenase kinase 4 (PDK4). Using semi-quantity and quantity PCR, We confirmed its differential expression between the two breeds. Temporal and spatial expression analysis indicated that porcine PDK4 gene is highly expressed in skeletal muscle and the highest in neonatal pigs. Complete cDNA cloning and sequence analysis revealed that porcine PDK4 gene contains an open reading frame of 1,221 bp. The deduced amino acid sequence showed conservation in evolution. A G/A mutation in intron 9 was identified and association analysis showed that it was significantly associated with intramuscular fat, muscle water content.

[Cloning and expression analysis of porcine ACTA2 gene and its association with production traits].

To identify new DNA markers which have significant impact on pig production traits, the full coding sequence and partial genomic sequence of porcine ACTA2(Actin alpha 2)gene were isolated using in silico cloning and PCR. PCR-Hinf-RFLP was developed to detect C1554T substitution in intron 2. The frequency of allele C is higher than that of allele T in all the seven detected pig populations except for Large White and MeishanxLarge White. Association analysis of markers and production traits showed that the relation between ACTA2 gene and shoulder fat thickness, buttock fat thickness, fat meat percentage, lean meat percentage, meat pH (m.Biceps Femoris, BF), and intramuscular fat were significant or highly significant. Compared with CC genotype, TT had a higher lean meat percentage, a lower fat meat percentage and backfat thickness. Real-time RT-PCR analysis showed that the expression level of ACTA2 gene in the skeletal muscle of Large White and Meishan pigs decreased with the increasing of days. And during each period, the expression level was higher in Meishan pigs than in Large White pigs.

Association of MYF5 and MYOD1 gene polymorphisms and meat quality traits in Large White x Meishan F2 pig populations.

MYF5 and MYOD1 belong to the myogenic regulatory factor (MRF) gene family. They code for the basic helix-loop-helix transcription factors that play key regulatory roles in the initiation and development of skeletal muscle and the maintenance of its phenotype. In this work three single nucleotide polymorphisms (SNPs) in porcine MYF5 and one in porcine MYOD1 were detected in three pig breeds (Large White, Landrace, and Meishan) by means of a PCR-RFLP protocol. Analysis of the association of meat quality traits with the four polymorphisms in a series of three Large White x Meishan F2 populations, totaling 399 pigs, found: (1) MYF5 exon 1 Hsp92II polymorphism causing a Met --> Leu substitution was associated with intramuscular fat content (P = 0.04) and water moisture content (P = 0.0001) in the longissimus dorsi; (2) MYF5 exon 2 MspI polymorphism and an intron 1 HaeIII polymorphism, which were completely linked, were significantly associated with longissimus dorsi pH (P < 0.05); (3) MYOD1 intron 1 DdeI polymorphism was not significantly associated with any meat quality traits tested. Among these genetic variants (a novel SNP and three identified SNPs), our data suggested that the novel SNP of the MYF5 gene within exon 1 is valuable for pig breeding.

Imprinting analyses of the porcine GATM and PEG10 genes in placentas on days 75 and 90 of gestation.

Imprinted genes are expressed monoallelically depending on their parental origin, and escape the Mendel's laws of heredity. They play important roles in the mammalian development, growth, and behavior. Placenta is a key tissue for the normal development and growth of fetus. It is also used to illuminate the evolution of genomic imprinting. In this study, we cloned the porcine GATM and PEG10 genes. Somatic cell hybrid panel (SCHP) and porcine radiation hybrid (IMpRH) panel were employed to locate GATM and PEG10 genes to SSC1q12-21 and SSC9p13-21, respectively. By sequencing PCR products, we detected several cSNPs in the two genes. The BseLI (GATM) and TaqI (PEG10) polymorphisms were used to investigate the allele frequencies in different pig breeds and the imprinting status in porcine placentas on days 75 and 90 of gestation. The results showed that for the GATM BseLI polymorphism, the Yorkshire and Duroc pigs had higher allele frequencies at the G allele, whereas the local pigs had higher allele frequencies at the A allele. Expression and sequencing analyses showed that both alleles were expressed for the GATM gene, indicating the GATM was not imprinted in the porcine placentas on days 75 and 90 of gestation. The allele frequencies of TaqI polymorphism for PEG10 gene were significantly different in native Chinese Erhualian breed comparing to Yorkshire. PEG10 was monoallelically expressed, showing the PEG10 gene may be imprinted in porcine placentas on days 75 and 90 of gestation.

Quantitative trait loci for carcass traits on pig chromosomes 4, 6, 7, 8 and 13.

For 22 carcass traits, we identified 16 QTLs (based on data for pig resource population no. 214, including 180 F2 hybrids of 3 Yorkshire boars and 8 Meishan sows) and mapped them with the use of 39 microsatellite marker loci on chromosomes 4, 6, 7, 8 and 13. Five QTLs were highly significant (P < or = 0.01 at chromosome level): for skin weight (on chromosome 7 at SW1856 and on chromosome 13 at SW1495), skin percentage (on chromosome 7 between SW2155 and SW1856 and on chromosome 13 between SW1495 and SW520), and ratio of leg and butt to carcass (on chromosome 4 at SW1996). The remaining 11 QTLs were significant (P < or = 0.05 at chromosome level): for backfat thickness at shoulder, loin eye width, loin eye height, fat meat weight, lean meat weight, skin weight, bone weight, skin percentage, fat meat percentage, and ratio of lean meat to fat meat. The proportion of phenotypic variance explained by these QTLs ranged from 0.06% (QTL for loin eye width on chromosome 8 between SW1037 and SW1953) to 18.04% (QTL for ratio of lean meat to fat meat on chromosome 7 between SW252 and SW581). Seven of the QTLs reported here are novel.

Transcription factor C/EBPß promotes the transcription of the porcine GPR120 gene.

G protein-coupled receptor 120 (GPR120), an adipogenic receptor critical for the differentiation and maturation of adipocytes, plays an important role in controlling obesity in both humans and rodents and, thus, is an attractive target of obesity treatment studies. However, the mechanisms that regulate the expression of porcine GPR120 remain unclear. In this study, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) techniques were used to analyze and identify the binding of C/EBPß (transcription factor CCAAT/enhancer binding protein beta) to the GPR120 promoter. C/EBPß overexpression and RNA interference studies showed that C/EBPß regulated GPR120 promoter activity and endogenous GPR120 expression. The binding site of C/EBPß in the GPR120 promoter region from -101 to -87 was identified by promoter deletion analysis and site-directed mutagenesis. Overexpression of C/EBPß increased endogenous GPR120 expression in pig kidney cells (PK). Furthermore, when endogenous C/EBPß was knocked down, GPR120 mRNA and protein levels were decreased. The stimulatory effect of C/EBPß on GPR120 transcription and its ability to bind the transcription factor-binding site were confirmed by luciferase, ChIP, and EMSA. Moreover, the mRNA and protein expression levels of C/EBPß were induced by high fat diet feeding. Taken together, it can be concluded that C/EBPß plays a vital role in regulating GPR120 transcription and suggests HFD-feeding induces GPR120 transcription by influencing C/EBPß expression.

[Sequence and polymorphism analysis of porcine hormone-sensitive lipase gene 5'-UTR and exon I].

Hormone-sensitive lipase (HSL) is the key enzyme responsible for the mobilization of free acids from adipose tissue, and it is also the most important enzyme that affect fat deposition. In this paper, the porcine hormone-sensitive lipase gene 5'-UTR and exon I were sequenced. The sequence number in GenBank are AY332499, AY332497, AY332504, AY332505. A GC-CG in the DNA sequence -13 - -12 bp of porcine HSL gene 5'-UTR was detected between Duroc, Meishan, Qingping pig, Largewhite and Landrace. A G-->A missense mutation was detected in HSL gene exon I of different pig breeds. The characterization of the BsaH I PCR-RFLP polymorphism in exon I of the porcine HSL gene of different breeds and "Largewhite x Meishan" F2 group was analyzed. By association analysis between BsaH I PCR-RFLP polymorphism and GG, GG, AA genotypes of HSL gene exon I, a significant difference of pig eye area was found between AG and GG genotypes (P<0.05) in F2 group.

[Effects of FUT1 gene on meat quality and carcass traits in swine].

A total of 139 hybrid finishing pigs from Large White x Meishan were slaughtered at about 88kg body weight. Fourteen meat quality traits and 8 carcass traits were assayed for each pig. FUT1 gene was scored by PCR-RFLP. The values of meat pH and meat color for AA genotype pig were higher than those of AG genotype pig (P<0.05). Water holding capacity (WHC) of AA genotype pig was higher than that of AG genotype pig(91.02% VS 86.70%, P<0.05). Backfat at 6-7 vertebra (BV) and backfat at vertebra-lumbar (BVL) of AA genotype pig were lower than those of AG genotype pig 4.26 mm and 3.96 mm respectively (P<0.05). Meat factor of AA genotype pig was higher than that of AG genotype pig 3.31% (53.46% VS 50.15%, P<0.05). These results indicated that FUT1 gene had good genetic effects on pig meat quality and carcass traits.

[Sequencing analysis on partial translated region of uncoupling protein-3 gene and single nucleotide polymorphism associations with the porcine carcass and meat quality traits].

Porcine uncoupling protein-3 gene was used to study its effect on carcass and meat quality traits. The UCP3 partial translated regions in skeletal muscle from four pig breeds were sequenced and the comparison of the fragment sequences among four pig breeds showed that there were three coding-region single nucleotide polymorphisms (cSNP), of which the mutation at 842 bp of the open reading frame can result in the amino acid chang between methionine and threonine, so we selected the mutation as polymorphic site. The detection of polymorphic fragment by the technique of single strand conformation polymorphism (SSCP) and chi2 analysis among three pig breeds indicated that the distribution of three genotypes(AA, AB and BB) was significantly different between Meishan and Large White or Meishan and Landrace( P < 0.01). In addition, association analysis of UCP3 polymorphism with carcass and meat quality traits was conducted in the F2 generation from the Large White x Meishan resource family, the results with GLM analysis showed that UCP3 polymorphism has significant effect on several carcass and meat quality traits and also additive effect on some carcass and meat quality traits predominated in the resource family. It implied that UCP3 gene could be a candidate gene locus or a linked marker to a major gene, which affects the porcine carcass traits and meat quality traits significantly.

[Studies of relationship between the melanocortin-3 receptor gene and body weight in chicken for high and low weight lines' intercross].

Genetic studies in mice have demonstrated a complementary role for the melanocortin-3 receptor (MC3R) and MC4R in the control of energy balance. Knockout of the MC3R in mice revealed an exclusively metabolic syndrome and increased fat mass. In the present study, we found a total of 5 novel single nucleotide polymorphisms (SNPs) of the MC3R gene in the chickens of high weight (HW) and low weight (LW) lines from divergently selected for high or low body weight at 8 weeks of age in White Plymouth Rock. Only one of the 5 SNPs led to amino acid substitution (Leu-->Arg) in HW and LW lines animals: a T/G substitution at nucleotide (nt) position 452 of coding sequence. Three of the 5 SNPs distinguished the birds from HW and LW lines: an A/G substitution at nt position 549 in LW line, an A/G substitution at nt position 882 in HW line, and a C/T substitution at nt position 894 in LW line, respectively. Another SNP was presented only in one of two HW line animals: a C/T substitution at nt position 564. Of the 5 SNPs, only A/G polymorphism at nt position 549 is located within a Dde I restriction enzyme recognition site. We designed a PCR-RFLP test based on the enzyme Dde I and screened the chickens for HW and LW lines' intercross. Analysis of variance revealed a significant influence of the MC3R genotype on body weight in the chickens for both sex and abdominal fat mass in male chickens. The result suggests that the MC3R as a candidate gene can explain significant difference for body weight in the intercross chickens.

[Molecular screening of MC4R gene and association with fat traits in pig resource family].

Melanocortin-4 Receptor (MC4R) plays an important role in the regulation of human obesity. It can cooperate with leptin, neuropeptide Y(NPY) and melanocyte-stimulating hormone (MSH) to regulate body weight and feeding. Inactivation of this receptor by gene targeting in mice results in a maturity onset obesity syndrome associated with hyperphagic, hyperinsulinemia, hyperglycemia, as well as decreased linear growth and adult obesity. Multiple alignments of the sequences from individuals of several pig lines identified a single nucleotide substitution(G-->A) at position 298 of the seventh transmembrane domain. In present study, polymorphism distribution of MC4R gene fragment in resource population was studied using PCR-RFLP method based on the enzyme Taq I. The genotype was analyzed with the phenotype of the slaughtered individuals. The results showed that the frequencies of MC4R genotype varied in different breeds. The correlation analysis demonstrated the genotype of MC4R was in significant relation with back-fat thickness on thorax-waist, buttock and the average back-fat thickness, as well as with the width and area of longissmus dorsi (LD), and the percentage of skin. MC4R gene plays a role mainly in the pattern of dominant effect, and all the additive effects were not significant.