Mutations of MC4R gene and its association with economic traits in Qinchuan cattle

A Critical Functional Missense Mutation (T117M) in Sheep MC4R Gene Significantly Leads to Gain-of-Function

The melanocortin 4 receptor (MC4R) gene plays a central role in regulating energy homeostasis and food intake in livestock, thereby affecting their economic worth and growth. In a previous study, the p.T117M mutation in the sheep MC4R gene, which leads to the transition of threonine to methionine, was found to affect the body weight at six months and the average daily gain in Hu sheep. However, there are still limited studies on the frequency of the sheep p.T117M missense mutation globally, and the underlying cellular mechanism remains elusive. Therefore, this study first used WGS to investigate the distribution of the MC4R gene p.T117M mutation in 652 individuals across 22 breeds worldwide. The results showed that the mutation frequency was higher in European breeds compared with Chinese sheep breeds, particularly in Poll Dorset sheep (mutation frequency > 0.5). The p.T117M mutation occurs in the first extracellular loop of MC4R. Mechanistically, the basal activity of the mutated receptor is significantly increased. Specifically, upon treatment with α-MSH and ACTH ligands, the cAMP and MAPK/ERK signaling activation of M117 MC4R is enhanced. These results indicate that the T117M mutation may change the function of the gene by increasing the constitutive activity and signaling activation of cAMP and MAPK/ERK, and, thus, may regulate the growth traits of sheep. In conclusion, this study delved into the global distribution and underlying cellular mechanisms of the T117M mutation of the MC4R gene, establishing a scientific foundation for breeding sheep with superior growth, thereby contributing to the advancement of the sheep industry.

Allelic and genotypic frequencies of SNP related to beef and carcass quality in Romosinuano cattle in Mexico

Romosinuano is a tropically adapted Bos taurus breed, and some Mexican breeders aim to improve it genetically. The aim was to estimate allelic and genotypic frequencies for SNPs associated with meat quality in a Mexican Romosinuano population. Four hundred ninety-six animals were genotyped using the Axiom©BovMDv3 array. Only SNPs related to meat quality in this array were studied in this analysis. The Calpain, Calpastatin, and Melanocortin-4 receptor alleles were considered. Allelic and genotypic frequencies and Hardy-Weinberg equilibrium were estimated with the PLINK software. Alleles associated with meat tenderness and higher marbling scores were found in the Romosinuano cattle population. CAPN1_4751 was not found in Hardy-Weinberg equilibrium. The rest of the markers could not be affected by selection and inbreeding. Romosinuano cattle in Mexico have similar genotypic frequencies in markers related to meat quality to Bos taurus breeds known for their meat tenderness. Breeders can choose a marker-assisted selection to improve meat quality characteristics.

Two co-inherited novel SNPs in the MC4R gene related to live body weight and hormonal assays in Awassi and Arabi sheep breeds of Iraq

Melanocortin‐4 receptor (MC4R) gene plays a key role in the regulation of body weight and energy homeostasis. This study aims to evaluate the association of single nucleotide polymorphisms (SNPs) of the MC4R gene with live body weight and hormonal assays in two breeds of sheep that differ in productive performance, Awassi and Arabi. All known coding sequences of the MC4R gene were covered in this study. DNA samples from 150 animals (Awassi and Arabi breed) were genotyped by PCR‐single‐strand conformation polymorphism (PCR‐SSCP) to assess their pattern of genetic variation. Concerning exon 1, clear heterogeneity was detected with three different SSCP‐banding patterns. The sequencing reactions confirmed these variations by detecting the presence of the two novel SNPs, 107G/C and 138A/C, and three genotypes, GC, AC and AA. The 107G/C SNP was detected in GC genotype, while the 138A/C was detected on both GC and AC genotypes. The other SSCP‐banding pattern (AA genotype) did not show any detectable unique variation. Both SNPs were closely and strongly linked in both breeds (D' and r² values were 1.00), which signifies that both loci were co‐inherited as one unit. Association analysis indicated that both breeds with GC/AC haplotype showed higher live body weight (37.250 ± 0.790) relative to the GG/AA (30.244 ± 0.968) and CC/CC (47.231 ± 1.230) haplotypes (p < .05). Concerning the genotyping of exon 2, only 362 bp showed heterogeneity with a missense mutation, with no significant association (p > .05) with the measured traits. In conclusion, the two novel SNPs (107G/C and 138 A/C) were highly associated with live body weight in both breeds. Haplotype analysis confirmed that these two novel SNPs were in strong linkage disequilibrium (LD) and could be used as genetic markers for sheep phenotypic trait improvement.

Transcriptional regulation of adipogenic marker genes for the improvement of intramuscular fat in Qinchuan beef cattle

The intramuscular fat content plays a crucial role in meat quality traits. Increasing the degree of adipogenesis in beef cattle leads to an increase in the content of intramuscular fat. Adipogenesis a complex biochemical process which is under firm genetic control. Over the last three decades, the Qinchuan beef cattle have been extensively studied for the improvement of meat production and quality traits. In this study, we reviewed the literature regarding adipogenesis and intramuscular fat deposition. Then, we summarized the research conducted on the transcriptional regulation of key adipogenic marker genes, and also reviewed the roles of adipogenic marker genes in adipogenesis of Qinchuan beef cattle. This review will elaborate our understanding regarding transcriptional regulation which is a vital physiological process regulated by a cascade of transcription factors (TFs), key target marker genes, and regulatory proteins. This synergistic action of TFs and target genes ensures the accurate and diverse transmission of the genetic information for the accomplishment of central physiological processes. This information will provide an insight into the transcriptional regulation of the adipogenic marker genes and its role in bovine adipogenesis for the breed improvement programs especially for the trait of intramuscular fat deposition.

The genetic polymorphisms of melanocortin-4 receptor gene are associated with carcass quality traits in a Chinese indigenous beef cattle breed

Melanocortin-4 receptor (MC4R) was considered as an essential modifiers in feelings intake, the regulation of metabolism and body weight. This study aimed at identifying polymorphisms in MC4R gene that might associate with carcass quality traits in Chinese indigenous beef cattle breed. qPCR analysis showed that the MC4R gene was widely expressed in various tissues, with predominantly expression levels in heart. Three single-nucleotide polymorphisms (SNPs) were identified, including a mutation (g.85A > G) in 5'untranslated regions (UTR) and two mutations (g.927C > T and g.1069C > G) in exon 1. Based on the χ² test, both g.927C > T and g.1069C > G loci fitted with Hardy-Weinberg equilibrium (P > .05). Population genetic analysis showed that except for g.85A > G, the other detected SNPs strongly affected the bovine back fat thickness and intramuscular fat content (P < .05). The individuals with Hap1/4 diplotypes (ACC-ATG) were highly significantly associated with carcass quality traits than the other diplotypes (P < .01 or P < .05). Results indicated that the bovine MC4R gene polymorphisms were implicated as genetic markers of potential importance in marker-assisted selection (MAS) strategies to improve carcass quality in Chinese Qinchuan cattle.

Phenotypic characterization and genome-wide association studies of digital cushion thickness in Holstein cows

The bovine digital cushion is a compression pad between the distal phalanx and sole and has been associated with claw horn disruption lesions. Digital cushion thickness (DCT) is estimated to be moderately heritable. Therefore, the objectives of our study were to examine influences of management and environment on DCT and to identify genetic markers and candidate genes associated with DCT. In a cohort of 502 Holsteins from 5 farms in New York State, DCT and body condition score (BCS) were collected twice, at <137 d prepartum and from 86 to 127 d in milk, corresponding to periods when the digital cushion is thickest and thinnest, respectively, as determined by previous research. Cows underwent sonographic examination of the digital cushion evaluated at the typical sole ulcer site for the right front and hind foot. Linear mixed models were conducted on DCT with the fixed effects of time point, digit, wither height, sacral height, BCS group, and multiple farm system variables separately and included random effects to control for the random subset of cows per farm, repeated measures, and multiple measurements from each cow. The phenotypic results indicated that DCT varied by sample time point, sacral height, parity, digit, BCS group, and wither height. For the genotypic study, 447 DNA samples were genotyped on the Illumina BovineHD 777K BeadChip (Illumina Inc., San Diego, CA). Quality assessment of markers and samples provided a final data set of 431 samples and 579,449 markers. Genome-wide association studies were conducted for DCT testing inheritance models and genetic variation of digit, foot, time point, and average thickness. One marker passed the Bonferroni correction threshold and 26 passed false discovery rate from 4 genome-wide association studies with covariates of sequencing batch plate, parity group, BCS, wither height, and sacral height. Ten candidate genes were identified, with 2 genes on Bos taurus autosomes 24 and 29 involved in biological functions related to the digital cushion: MC4R and DLG2 were related to fat deposition and bone growth, respectively. The genetic markers discovered in this study have the opportunity to be used in breeding programs using genomic selection to select against claw horn disruption lesions and lameness due to associations between the markers and DCT. Further studies on the biologically plausible candidate genes may identify causative genetic variants and how they relate to DCT through gene regulation, expression, structure, or copy number variation.

Identification of meat from yak and cattle using SNP markers with integrated allele-specific polymerase chain reaction-capillary electrophoresis method

Correct species identification is necessary for meat product quality assurance. Genetic markers are useful tools to accurately determine the animal source of meat products. To better protect yak meat and its products, ten single nucleotide polymorphism (SNP) loci from bovine meat-related genes and one positive control primer set were selected to discriminate meat sourced from yak or cattle. A multiplex allele-specific polymerase chain reaction and capillary electrophoresis method was employed for SNP genotyping. The samples were identified as from yak or cattle based on the number of amplicons. Yak samples generally produced one to three amplicon peaks, and the cattle samples yielded five or more peaks in the electropherogram. This method could be useful to distinguish yak meat from cattle beef, and would protect consumers and yak meat producers.

Agouti Signaling Protein and Its Receptors as Potential Molecular Markers for Intramuscular and Body Fat Deposition in Cattle

Transcriptome analyses of bovine muscle tissue differing in intramuscular fat (IMF) content identified agouti signaling protein (ASIP) as a promising candidate gene for fat deposition. The protein is secreted from adipocytes and may serve as a signaling molecule in cross-talk between adipocytes and muscle fibers or other cells. Known receptors for ASIP are the melanocortin receptors (e.g., MC4R) and attractin (ATRN). The present study was conducted to determine relationships between the expression of ASIP and its receptors in different bovine tissues with fat deposition. Adipose tissues, liver, and longissimus muscle tissue were collected from 246 F₂-generation bulls (Charolais × Holstein cross) and gene expression was measured with RT-qPCR. During analysis of subcutaneous fat (SCF) of all bulls, 17 animals were identified with a transposon-derived transcript (Exon2C) inserted in the ASIP gene and dramatically increased ASIP mRNA levels. Significant correlations between normalized mRNA values of SCF and phenotypic traits related to fat deposition were found in bulls without Exon2C. Three retrospectively assigned groups [Exon2C, n = 17; high carcass fat (HCF), n = 20; low carcass fat (LCF), n = 20] were further analyzed to verify expression differences and elucidate molecular reasons. Expression of ASIP could be detected in isolated muscle fibers and adipocytes of Exon2C bulls in contrast to HCF and LCF bulls, indicating ectopic ASIP expression if the transposon is present. Among adipose tissues, highest ASIP mRNA levels were measured in SCF with significantly higher values in HCF compared to LCF bulls (1.6-fold, P < 0.05). However, the protein abundance was below the detection limit in all bulls. Potential ASIP receptors were detected in most investigated tissues. The expression of MC4R was higher and of ATRN was lower in several tissues of LCF compared to HCF bulls, whereas MC1R was not differentially expressed. Bulls of the Exon2C group had lower ATRN mRNA values than HCF and LCF bulls in perirenal fat (PF), but higher (P < 0.05) values in muscle. Receptors were also expressed in tissues where ASIP mRNA was not detected. Consequently, those tissues could be targets for ASIP if it circulates.

Beef quality with different intramuscular fat content and proteomic analysis using isobaric tag for relative and absolute quantitation of differentially expressed proteins

Intramuscular fat (IMF) is an important trait for beef eating quality. The mechanism of how IMF is deposited in beef cattle muscle is not clear at the molecular level. The muscle (M. longissimus lumborum: LL) of a group of Xiangxi yellow×Angus cattle with high fat levels (HF), was compared to the muscle of a low fat group (LF). The meat quality and the expressed protein patterns were compared. It was shown that LL from the HF animals had a greater fat content (P<0.05) and lower moisture content (P<0.05) than LL from LF animals. Forty seven sarcoplasmic proteins were differentially expressed and identified between the two groups. These proteins are involved in 6 molecular functions and 16 biological processes, and affect the Mitogen-activated protein kinases pathway, insulin pathway and c-Jun N-terminal kinases leading to greater IMF deposition. Cattle in the HF group had greater oxidative capacity and lower glycolytic levels suggesting a greater energetic efficiency.

SNPs of melanocortin 4 receptor (MC4R) associated with body weight in Beagle dogs

Melanocortin 4 receptor (MC4R), which is associated with inherited human obesity, is involoved in food intake and body weight of mammals. To study the relationships between MC4R gene polymorphism and body weight in Beagle dogs, we detected and compared the nucleotide sequence of the whole coding region and 3'- and 5'- flanking regions of the dog MC4R gene (1214 bp). In 120 Beagle dogs, two SNPs (A420C, C895T) were identified and their relation with body weight was analyzed with RFLP-PCR method. The results showed that the SNP at A420C was significantly associated with canine body weight trait when it changed amino acid 101 of the MC4R protein from asparagine to threonine, while canine body weight variations were significant in female dogs when MC4R nonsense mutation at C895T. It suggested that the two SNPs might affect the MC4R gene's function which was relative to body weight in Beagle dogs. Therefore, MC4R was a candidate gene for selecting different size dogs with the MC4R SNPs (A420C, C895T) being potentially valuable as a genetic marker.

Effect of polymorphisms in candidate genes on carcass and meat quality traits in double muscled Piemontese cattle

The aim of this study was to investigate the association between 10 candidate genes and carcass weight and conformation, carcass daily gain, and meat quality (pH, color, cooking loss, drip loss and shear force) in 990 double-muscled Piemontese young bulls. Animals were genotyped at each of the following genes: growth hormone, growth hormone receptor, pro-opiomelanocortin, pro-opiomelanocortin class 1 homeobox 1, melanocortin-4 receptor, corticotrophin-releasing hormone, diacylglycerol O-acyltransferase-1, thyroglobulin, carboxypeptidase E and gamma-3 regulatory subunit of the AMP-activated protein kinase. All the investigated SNPs had additive effects which were relevant for at least one of the traits. Relevant associations between the investigated SNPs and carcass weight, carcass daily gain and carcass conformation were detected, whereas associations of SNPs with meat quality were moderate. Results confirmed some of previously reported associations, but diverged for others. Validation in other cattle breeds is required to use these SNPs in gene-assisted selection programs for enhancement of carcass traits and meat quality.

Three novel SNPs in the coding region of the bovine MC3R gene and their associations with growth traits

The involvement of melanocortin-3 receptor (MC3R) is well recognized in the regulation of feeding efficiency, body weight, and energy homeostasis. The objective of this study was to investigate the associations between MC3R gene polymorphisms and growth traits. Three novel SNPs (c.24C→T, c.220T→A, c.734G→C) and five haplotypes were identified in 234 Xiangxi cattle. The associations between MC3R gene polymorphisms and growth traits indicated that the individuals with TT and AT genotypes maintained higher body weight than those with the AA genotype at the c.220T→A locus (P < 0.05). The animals with GG and CG genotypes had higher heart girth and body weight than those with the CC genotype at c.734G→C (P < 0.05). The animals with H3H3 and H2H3 haplotype combinations had higher body weight than those with other haplotype combinations (P < 0.05). The results suggest that these SNPs in the MC3R gene might be useful genetic markers for marker-assisted selection and cattle breeding.

Family of melanocortin receptor (MCR) genes in mammals-mutations, polymorphisms and phenotypic effects

The melanocortin receptor gene family consists of five single-exon members, which are located on autosomes. Three genes (MC2R, MC4R and MC5R) are syntenic in the human, mouse, cattle and dog genomes, while in the pig, the syntenic group comprises MC1R, MC2R and MC5R. Two genes (MC1R and MC4R) have been extensively studied due to their function in melanogenesis (MC1R) and energy control (MC4R). Conservative organisation of these genes in five mammalian species (human, mouse, cattle, pig and dog), in terms of the encoded amino acid sequence, is higher in the case of MC4R compared to MC1R. Polymorphisms of these two genes are responsible or associated with variation of pigmentation (MC1R) and adipose tissue deposition (MC4R). Polymorphic variants in MC1R, causing coat colour variation, were described in humans and domestic mammals (cattle, horse, pig, sheep, dog), as well as farm red and arctic foxes. The MC4R gene is very polymorphic in humans and it is well known that some variants cause monogenic obesity or significantly contribute to the development of polygenic obesity. Such relationships are not so evident in domestic mammals; however, at least one missense substitution (298Asp > Asn) in the porcine MC4R significantly contributes, at least in some breeds, to fat tissue accumulation, feed conversion ratio and daily weight gain. Knowledge on the phenotypic effects of polymorphisms of MC2R, MC3R and MC5R in domestic mammals is scarce, probably due to the small number of reports addressing these genes. Thus, further studies focused on these genes should be undertaken.

DNA polymorphisms of the Hu sheep melanocortin-4 receptor gene associated with birth weight and 45-day weaning weight

The melanocortin-4 receptor (MC4R) has important roles in regulating food intake, energy balance, and body weight in mammals. In pigs and cattle, MC4R mutations have been identified as genetic markers for growth and traits. Compared with abundant research conducted on other livestock species, little is known about mutations of the ovine MC4R gene. We investigated the effect of MC4R polymorphisms on birth weight and on 45-day weaning weight in 144 Hu sheep. Four single nucleotide polymorphisms (SNPs; g.1016 G/A, g.1240 T/C, g.1264 G/A, and g.1325 A/G) were identified in the 3ꞌ-untranslated region of Hu sheep MC4R by PCR-single-strand conformation polymorphism and DNA sequencing. A haplotype block, containing g.1240 T/C, g.1264 G/A, and g.1325 A/G, was constructed within the Hu sheep MC4R gene. Four SNPs were found to be significantly associated with 45-day weaning weight, while the haplotype block was significantly associated with birth weight. Hu sheep with the genotypes GG in g.1016 G/A or with the genotype CCAAGG in the haplotype block, had higher 45-day weaning weights. We conclude that these 4 SNPs of the MC4R gene have potential as genetic markers for early growth traits in Hu sheep.

BRCA1: a new candidate gene for bovine mastitis and its association analysis between single nucleotide polymorphisms and milk somatic cell score

Bovine mastitis is a very complex and common disease of dairy cattle and a major source of economic losses to the dairy industry worldwide. In this study, the bovine breast cancer 1, early onset gene (BRCA1) was taken as a candidate gene for mastitis resistance. The main object of this study was to investigate whether the BRCA1 gene was associated with mastitis in cattle. Through DNA sequencing, Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) and Created Restriction Site PCR (CRS-PCR) methods, three SNPs (G22231T, T25025A, and C28300A) were detected and twenty-four combinations of these SNPs were observed. The single SNP and their genetic effects on somatic cell score (SCS) were evaluated and a significant association with SCS was found in C28300A. The mean of genotype EE was significantly lower than those of genotypes EF and FF. The results of combined genotypes analysis of three SNPs showed that BBDDFF genotype with the highest SCS were easily for the mastitis susceptibility, whereas AACCEE genotype with the lowest SCS were favorable for the mastitis resistance. The information provided in the present study will be very useful for improving mastitis resistance in dairy cattle by marker-assisted selection.

A comparative analysis of MC4R gene sequence, polymorphism, and chromosomal localization in Chinese raccoon dog and Arctic fox

Numerous mutations of the human melanocortin receptor type 4 (MC4R) gene are responsible for monogenic obesity, and some of them appear to be associated with predisposition or resistance to polygenic obesity. Thus, this gene is considered a functional candidate for fat tissue accumulation and body weight in domestic mammals. The aim of the study was comparative analysis of chromosome localization, nucleotide sequence, and polymorphism of the MC4R gene in two farmed species of the Canidae family, namely the Chinese raccoon dog (Nycterutes procyonoides procyonoides) and the arctic fox (Alopex lagopus). The whole coding sequence, including fragments of 3'UTR and 5'UTR, shows 89% similarity between the arctic fox (1276 bp) and Chinese raccoon dog (1213 bp). Altogether, 30 farmed Chinese raccoon dogs and 30 farmed arctic foxes were searched for polymorphisms. In the Chinese raccoon dog, only one silent substitution in the coding sequence was identified; whereas in the arctic fox, four InDels and two single-nucleotide polymorphisms (SNPs) in the 5'UTR and six silent SNPs in the exon were found. The studied gene was mapped by FISH to the Chinese raccoon dog chromosome 9 (NPP9q1.2) and arctic fox chromosome 24 (ALA24q1.2-1.3). The obtained results are discussed in terms of genome evolution of species belonging to the family Canidae and their potential use in animal breeding.

Molecular characterization of CART, AgRP, and MC4R genes and their expression with fasting and re-feeding in common carp (Cyprinus carpio)

Cocaine and amphetamine-regulated transcript (CART), agouti-related proteins (AgRP) and Melanocortin 4 Receptor (MC4R) involves in the control of appetite. The genes were cloned and characterized, and their regulation was studied in common carp. The CARTI and CARTII genes encode 117- and 120-amino acids, respectively. The AgRP-1 and AgRP-2 genes encode 128- and 136-amino acids, respectively. CARTI was principally expressed in the brain, eye and ovary, while CARTII was highly expressed in the brain. AgRP-1 was strongly expressed in the brain, intestine, testis and eye, while AgRP-2 was highly expressed only in the gill and eye. The MC4R gene, encoding 326-amino acids, was mainly expressed in the brain testis, pituitary and eye. Phylogenetic analysis had been conducted which implied that both CARTI/CARTII and AgRP-1/AgRP-2 might derived from gene duplication events during genome evolution of common carp. CART, AgRP and MC4R gene expression in brain were decreased after fasting treatment and increased sharply after refeeding comparing with normal fed controls, which suggested that CART, AgRP and MC4R are involved in appetite regulation in common carp.

Single nucleotide polymorphism of CACNA2D1 gene and its association with milk somatic cell score in cattle

The objective of the present study was to identify polymorphisms of the CACNA2D1 gene, and to analyze associations between these polymorphisms and mastitis in several cattle breeds. Through PCR-RFLP methods and DNA sequencing, an allelic variant corresponding to the A→G mutations and Aspartic (Asp) to Glycine (Gly) amino acid replacement at positions 526745 in the exon 25 of bovine CACNA2D1 gene could be detected. Two alleles, A and G, and three genotypes, AA, AG and GG were defined. Genetic character in the studied populations indicated that the A526745G loci of CACNA2D1 gene was moderate polymorphism and fitted with Hardy-Weinberg equilibrium (P > 0.05). The effects of CACNA2D1 polymorphisms on somatic cell score (SCS) were analyzed and significant association was found between A526745G and SCS. The mean of genotype GG was significantly lower than those of genotype AG and AA (P = 0.0469). Information provided in this research could be useful in further studies to determine the role of CACNA2D1 gene in the mastitis resistance.

Cloning and characterization of the 5'-flanking region of the pig AgRP gene

Agouti-related peptide (AgRP), a brain neuropeptide generated by AgRP/neuropeptide Y (NPY) neurons, plays a vital role in the hypothalamic regulation of energy homeostasis. RT-PCR and real-time PCR were carried out in various tissues to detect the AgRP expression pattern in pigs. Our RT-PCR results showed that the pig AgRP gene was ubiquitously expressed in all examined tissues including heart, liver, spleen, lung, kidney, stomach, bladder, m. longissimus, belly fat, brain, large intestine, lymph, back fat, skin, and hypothalamus. Real-time quantitative PCR experiments revealed that it is in the hypothalamus with the highest expression of AgRP both in adult Lantang and Landrace pigs compared to the back fat and m.longissimus muscle and the cDNA level of AgRP in the hypothalamus of adult Chinese indigenous Lantang pig (fat-type) is significantly higher than that of Landrace pig (lean-type). To understand the regulation of the pig AgRP gene, the 5'-flanking region was isolated from a pig bacterial artificial chromosome library and used in a luciferase reporter assay. A positive cis-acting element for efficient AgRP expression was identified at nucleotides -501 to -479, by 5'-serial deletion of the promoter. Electrophoretic mobility-shift assays (EMSA) with competing oligonucleotides revealed that the critical region contained a cis-acting element for Neurogenic Differentiation (NeuroD), which is a member of the NeuroD family of basic-helix-loop-helix transcription factors. This element has not been reported in human or mouse AgRP genes. Our results indicated that NeuroD might be an essential regulatory factor for transcription of pig AgRP, providing an important clue about energy homeostasis regulation in the porcine and human brain.

Genetic diversity of the melanocortin 4 receptor (MC4R) gene and its association with slaughter traits in the Landes goose

Melanocortin 4 receptor (MC4R) plays a crucial part in regulating feeding behavior in humans and rodents. We detected two single nucleotide polymorphisms (SNPs; c.108G → A and c.627C → T) in the goose MC4R gene and genotyped 94 Landes geese for association analysis with several carcass traits. Significant associations (P < 0.05) were obtained for c.108G → A with carcass weight, breast muscle percentage, and leg muscle percentage, and for c.627C → T with body weight, carcass weight, semi-eviscerated weight, and eviscerated weight. We re-constructed haplotypes based on the two SNPs and analyzed diplotypes in association with carcass traits, obtaining significant associations with several of the traits. These results suggest that polymorphisms in the MC4R gene could have effects on carcass traits in Landes geese. More study is required to confirm these results.

Polymorphism of DLK1 and CLPG gene and their association with phenotypic traits in Chinese cattle

DLK1 and CLPG were located in DLK1-GTL2 imprinted cluster. They all affected muscle growth and meat tenderness. The functional importance of DLK1 and CLPG imply that the variation of the genes could affect the growth traits of animal. PCR-SSCP and sequencing were used to analyze the four loci of DLK1 gene and CLPG gene in 1109 individuals, which belong to eight breeds/species of bovidae, including cattle, buffalo and yak. A synonymous mutation (C451T) was detected in exon 5 of DLK1 in Qinchuan cattle, but didn't change significantly with phenotypic traits. Three genotypes AA, AB and AC of CLPG were identified in Jiaxian cattle. The associations analyst of different genotypes showed that the individuals with genotypes AA and AC had a greater body weight and longer body length than those with genotype AB (P<0.05 and P<0.01, respectively); the AA individuals were different from those AB (P<0.05) in the circumference of cannon bone. No polymorphism was observed in the other populations at other loci. These results were in agreement with the homology analysis: DLK1 and CLPG genes were in a highly conserved.

Polymorphism of bovine Y-STR UMN0929 and its correlation with carcass traits in five Chinese beef cattle populations

The correlations between Y chromosome polymorphisms and the carcass traits were studied in five Chinese beef cattle populations by PCR, single strand conformation polymorphism and Y-STR sequence analysis. Nine alleles and their frequencies were identified on Y-STR UMN0929 region in Qinchuan (n=116), Luxi (n=112), Jinnan (n=104) pure breeds, Simmental×Qinchuan crossbred (n=80) and Angus×Qinchuan crossbred (n=96). The most popular A-176 and B-178 alleles were presented in all 5 cattle populations in the range of 12% (Jinnan) to 66% (Simmental×Qinchuan). The allele I-194 presented Luxi and Angus×Qinchuan. In Qinchun cattle, G-190 and E-186 alleles had bigger effect on BPI (4.23±0.32 and 4.22±0.48 kg/cm, P<0.01) and CW (325.40±49.42 and 316.73±45.29 kg, P<0.01), respectively. In Luxi cattle, I-194 allele affected higher BPI (4.08±0.35 kg/cm, P<0.01) and CW (302.07±17.55 kg, P<0.01), respectively. In Jinnan cattle breed, H-192 had higher BPI (4.32±0.50 kg/cm, P<0.05) and CW (327.87±59.37 kg, P<0.05), respectively. In Simmental×Qinchuan cross breed, C-180 allele affected largely on BPI (5.16±0.25 kg/cm, P<0.05) and CW (393.16±25.92 kg, P<0.05). In Angus×Qinchuan cross breed, I-194 had higher BPI (4.43±0.33 kg, P<0.05) and CW (346.63±29.77 kg, P<0.05). Correlations between alleles and other carcass traits (net meat weight, top grade weight, slaughter rate, net meat rate, loin-eye muscle area, carcass length, meet tenderness and shear force) were also analyzed using mixed-effect model. Cattle Y-STR UMN0929 loci alleles and its correlation with carcass traits in beef cattle populations could be implemented into the cattle breeding program for choosing beef cattle with better carcass traits.

A novel SNP of the ATP1A1 gene is associated with heat tolerance traits in dairy cows

PCR low ionic strength single-strand conformation polymorphism (PCR-LIS-SSCP) and DNA sequencing methods were used to analyze the polymorphisms within the coding region of bovine ATP1A1 gene. A novel C/A mutation was identified at the nucleotide position 2789 of the ATP1A1 mRNA, but it was silent with respect to the amino acid sequence of the protein. The LIS-SSCP banding pattern could be divided into three kinds of genotypes, named CC, CA, and AA. Also, the association of the novel SNP of ATP1A1 gene with heat tolerance traits was studied, we found that the individuals with genotype CC showed significantly higher heat resistance than those of genotype CA (P<0.05). Further, the mRNA levels of ATP1A1 gene in lymphocytes of peripheral blood in dairy cows among various temperature groups and genotypes were analyzed by using real-time RT-PCR. Results showed that the expression of ATP1A1 mRNA was highest in heat-stressed cows with CC genotype among the three genotypes (P<0.01), and the ATP1A1 mRNA level at temperature 32.5°C was higher than that at optimal temperature 12.5°C in dairy cows (P<0.01). Simultaneity, the plasma potassium (K+, mmol/l) and sodium (Na+, mmol/l) declined when the temperature dropped (P<0.05). Our findings implied that the novel SNP here could be a potential genetic marker for anti-heat stress trait in dairy cow breeding.

Three novel SNPs in the coding region of PPARγ gene and their associations with meat quality traits in cattle

The peroxisome proliferator-activated receptor γ (PPARγ) is a nuclear hormone receptor that regulates adipogenesis and many other biological processes. In the present study, we carried out PCR-SSCP and DNA sequencing analyses to examine SNPs in coding region of the PPARγ gene. A total of 660 individuals from five Chinese cattle breeds were genotyped. We identified three SNPs and their associations with meat quality traits were analyzed in 108 Qinchuan cattle. Two missense mutations and one synonymous mutation were found: 200 A>G (genotypes AA, AB and BB) resulting in D7G change, the silent substitution 42895 C>T (genotypes JJ and JI) and 72472 G>T (genotypes CC, DC and DD) producing Q448H change, respectively. The frequencies of PPARγ-A allele were 0.86, 0.83, 0.80, 0.72 and 0.87 for Qinchuan, Nanyang, Jiaxian, Luxi and Xianan populations, respectively. The frequencies of PPARγ-J allele varied from 0.87 to 0.96 in the five populations. In the 72472 G>T locus, the frequencies of PPARγ-C allele were higher than PPARγ-D allele in the five populations, and ranged from 0.58 to 0.82. Least squares analysis revealed that in 42895 C>T locus, there was a significant effect on tenderness in 18-20 months Qinchuan cattle (P<0.01), and in the 72472 G>T locus, animals with the genotype DC had lower mean values than these with genotype CC (P<0.01) for back fat thickness in 18-20 months, and animals with the genotype DD had lower mean values than these with genotypes CC and DC (P<0.01) for water holding capacity in 21-24 months (P<0.01). The SNPs we have identified may contribute to establishing a more efficient selection program for improving of genetic characteristics in indigenous Chinese cattle.

Molecular characterization, polymorphism of bovine ZBTB38 gene and association with body measurement traits in native Chinese cattle breeds

Zinc finger and BTB domain containing 38 (ZBTB38), binding to and repressing methylated DNA, is an important candidate gene for selection of body measurement traits through marker-assisted selection (MAS). The expression of ZBTB38 is regulated in human and animal height as well as other stature indexes. Genomic structural analysis shows that bovine ZBTB38 shares much similarity with human ZBTB38. We discovered and evaluated the potential association of the single nucleotide polymorphism (SNP) of the bovine ZBTB38 gene with body measurement traits in 722 individuals. The latest findings demonstrate that the A841G SNP in exon 1 is significantly associated with Body Length (BL), Hip Height (HH) and Heart Girth (HG). Furthermore, the analysis of A841G SNP marker shows that there are significant effects on the BL (P = 0.0389) in 722 individuals, significant effects on the HH (P = 0.0173) and HG (P = 0.0147) in Qinchuan improvement steers (QI) population, as well as significant effects on the WH (P = 0.0094) in Xuelong (XL) population. These results clearly suggest that the ZBTB38 gene is among of target genes for body measurement traits in bovine reproduction and breeding, and thus provide data for establishment of an animal model using cattle to study big animal body type.