Analysis of the associations between polymorphisms in GNAS complex locus and growth, carcass and meat quality traits in pigs

Imprinted genes are interesting candidates for marker assisted selection in farm animals. One of them—GNAS complex locus is engaged in obesity pathogenesis in humans and mice. In our study, we identified new polymorphism in porcine GNAS gene (variable number of CT repeats, accession number: rs196952953) and found that this polymorphism is in linkage disequilibrum with GNAS AM490165:g.324C>T. Statistical analysis (GLM procedure), performed on 552 animals (Large White n = 258 and Landrace n = 269), revealed that deduced haplotypes and GNAS AM490165:g.324C>T are associated with growth performance and a few carcass traits, but not with feed intake. We observed significant additive effects of GNAS AM490165:g.324C>T genotype and haplotype 2 (C/278 bp) on test daily gain (TDG), average daily gain (ADG), number of days on test, age of the slaughter (P < 0.01) and FCR ratio (P < 0.05). Animals with two copies of C/278 haplotype had significantly higher: TDG, ADG, lower feed:gain ratio and faster reached the weight of 100 kg. When carcass traits were considered, significant associations between GNAS AM490165:g.324C>T polymorphism, haplotype 2 (C/278) and weight of ham with and without backfat and skin (WH) (WH2), length of the carcass, height and the width of the loin, meat percentage, weight of the main cuts were identified. The significant dominance effects of GNAS AM490165:g.324C>T polymorphism and haplotype 2 on WH and WH2 were observed (P < 0.05). When the two breeds were analyzed separately significant associations were observed for most of the traits in Landrace while in Large White the same trends were present but the differences were mostly not significant. Among meat quality traits we found significant association between haplotype and IMF content in Landrace (P < 0.03). Our results show for the first time that GNAS complex locus may modulate economically important traits in pigs.     

ACTN3 genotype distribution across horses representing different utility types and breeds

Molecular Biology Reports - In horses, the identification of the genetic background of phenotypic variation, especially with regard to performance characteristics and predisposition to effort, has...     

A genome-wide detection of selection signatures in conserved and commercial pig breeds maintained in Poland

Background

Identification of selection signatures can provide a direct insight into the mechanism of artificial selection and allow further disclosure of the candidate genes related to the animals’ phenotypic variation. Domestication and subsequent long-time selection have resulted in extensive phenotypic changes in domestic pigs, involving a number of traits, like behavior, body composition, disease resistance, reproduction and coat color. In this study, based on genotypes obtained from PorcineSNP60 Illumina assay we attempt to detect both diversifying and within-breed selection signatures in 530 pigs belonging to four breeds: Polish Landrace, Pu?awska, Z?otnicka White and Z?otnicka Spotted, of which the last three are a subject of conservative breeding and substantially represent the native populations.

Results

A two largely complementary statistical methods were used for signatures detection, including: pairwise F_ST and relative extended haplotype homozygosity (REHH) test. Breed-specific diversifying selection signals included several genes involved in processes connected with fertility, growth and metabolism which are potentially responsible for different phenotypes of the studied breeds. The diversifying selection signals also comprised PPARD gene that was previously found to have a large effect on the shape of the external ear in pigs or two genes encoding neuropeptide Y receptors (Y2 and Y5) involved in fat deposition and stress response which are important features differentiating the studied breeds. REHH statistics allowed detecting several within-breed selection signatures overlapping with genes connected with a range of functions including, among others: metabolic pathways, immune system response or implantation and development of the embryo.

Conclusions

The study provides many potential candidate genes with implication for traits selected in the individual breeds and gives strong basis for further studies aiming at identification of sources of variation among the studied pig breeds.

     

Association between LEPR and MC4R genes polymorphisms and composition of milk from sows of dam line

The polymorphisms of LEPR and MC4R genes are involved in appetite control mechanisms and indirectly associated with level of fat content in pig carcasses. Therefore, the aim of our study was to determine if both polymorphisms have an effect on components of colostrum and milk of sows. In our study we used gilts of two Polish breeds: Polish Landrace and Polish Large White, which belong to dam-line in Polish breeding. Colostrum and milk of sows were collected in 7, 14 and 21 day of lactation to assay solids, total protein, fat and lactose. The obtained results showed, that the observed mutation (G/A 1426 MC4R) had a significant effect mainly on the fat and solids content of colostrum. Animals with the MC4R ^AA genotype had 2.13 and 1.91 % (P ≤ 0.01) lower fat content of colostrum compared to sows with the MC4R ^GG genotype and heterozygous MC4R ^AG. The presence of the MC4R ^A allele in the animals’ genotype contributed to a decrease in fat and solids content of colostrum. The LEPR/HpaII mutation was found to have a considerable effect on the level of most colostrum components (fat, protein and solids) in both pig breeds. Significant decrease in the value of the colostrum components (except lactose) was observed only for animals with the allele LEPR ^B. The results obtained suggest that these genes might be used in selection of dam-line pigs as genetic markers of milk quality.