Effect of the polymorphism in 5' UTR region of pig prolactin gene on prolactin gene expression and reproduction performance in the female pig.

OBJECTIVES: The recent genetics and molecular biology progress seems to be a fascinating challenge for the interdisciplinary studies on the effects of genetic changes in gene structure that causes the modification of physiological functions of many important proteins including hormones. Pig prolactin is one of the interesting hormones for this study. AIM OF THE STUDY: The aim of the study was to analyze the mutation in 5'UTR region of the pig prolactin (PRL) gene and to evaluate the effect of this polymorphism on changes in plasma prolactin concentration. RESULTS: It was found that only two individual groups of animals differed by the genotype in examined PRL gene locus - homozygote C/C and heterozygote C/T. PRL plasma concentration was 38.4 ng/ml (for C/T animals) or 42.7 ng/ml (for C/C animals). Animals with C/C genotyped exhibited a tendency to elevate PRL concentration as compared to the C/T group (p< 0.07). CONCLUSIONS: This research combines the genetic, molecular and, in vivo, physiological study which allows focus on the possible relationship between the gene polymorphism and physiological status of animal.

Polymorphisms in coding and regulatory regions of the porcine MYF6 and MYOG genes and expression of the MYF6 gene in m. longissimus dorsi versus productive traits in pigs.

MYOG and MYF6 belong to the MyoD gene family. They code for the bHLH transcription factors playing a key role in later stages of myogenesis: differentiation and maturation of myotubes. Three SNPs in porcine MYF6 and two in porcine MYOG were analysed in order to establish associations with chosen carcass quality and growth rate traits in Polish Landrace, Polish Large White and line 990 sows. No statistically significant effect of SNP in the promoter region of the MYF6 gene on its expression measured on mRNA level was found. Associations between the genotype at the MYF6 locus and carcass quality traits appeared to be breed-dependent. The C allele in the case of SNP in the promoter region and GC haplotype in exon 1 were advantageous for right carcass side weight in Polish Landrace sows and disadvantageous for this trait in Polish Large White sows. These gene variants were also the most advantageous for loin and ham weight in sows of line 990. The mutation in exon 1 of the MYOG gene had no statistically significant association with carcass quality traits and the mutation in the 3'-flanking region had the breed-dependent effect as well. These results suggest that SNPs analysed in this study are not causative mutations, but can be considered as markers of some other, still unrevealed genetic polymorphism that influences the physiological processes and phenotypic traits considered in this study.

A novel polymorphism of the porcine prolactin gene (PRL).

Prolactin is a protein hormone playing a role in the maintenance of pregnancy in the pig by action on corpora lutea cells and possibly initiating production of progesterone. The prolactin gene is 10 kb in size and is composed of 5 exons and 4 introns. The present work is a report of the swine PRL gene--comparative DNA sequence analysis and the SNP revealed in the promoter region. Based on the bovine prolactin gene, three primer pairs were designed using the Primer3 on-line software. The overlapping fragments covered about 400 nucleotides of the promoter and 78 nucleotides of exon 1. The fragments were amplified; two of them were sequenced and deposited in the GenBank database (AY341908 and AY905690). All fragments were analyzed using multitemperature SSCP (MSSCP) technique. Only one fragment appeared to show a different MSSCP pattern. The samples of differing MSSCP conformers were sequenced and the C499T transition was identified in the 5'UTR region of the gene. The HphI restriction enzyme appeared to recognize the novel SNP. The alignment for homology analysis was performed with porcine, bovine (X01452) and human (NM_000948) DNA sequences available in GenBank database, using BLAST software. The comparative homology analysis results varied in dependence on the species and functional region of the gene.

A novel polymorphism in exon 1 of the porcine myogenin gene.

Myogenin is a gene belonging to the MyoD family, which codes for the bHLH transcription factor playing a key role in myogenesis. It affects the processes of differentiation and maturation of myotubes during embryogenesis. Fragments of the porcine myogenin coding sequence and promoter region were amplified and subjected to MSSCP analysis. T-->C transition recognised by the MaeIII restriction enzyme in exon 1 was revealed, which appeared to be a silent mutation in the region of the transactivation domain. No other polymorphism was found either in the remaining coding sequence or the promoter region.

Associations between muscle gene expression pattern and technological and sensory meat traits highlight new biomarkers for pork quality assessment.

Meat quality (MQ) results from complex phenomenon and despite improved knowledge on MQ development, its variability remains high. The identification of biomarkers and the further development of rapid tests would thus be helpful to evaluate MQ in pork industries. Using transcriptomics, the present study aimed at identifying biomarkers of eight pork quality traits: ultimate pH, drip loss, lightness, redness, hue angle, intramuscular fat, shear force and tenderness, based on an experimental design inducing a high variability in MQ. Associations between microarray gene expression and pork traits (n=50 pigs) highlighted numerous potential biomarkers of MQ. Using quantitative RT-PCR, 113 transcript-trait correlations including 40 of these genes were confirmed (P<0.05, |r|≤0.73), out of which 60 were validated (P<0.05, |r|≤0.68) on complementary experimental data (n=50). Multiple regression models including 3 to 5 genes explained up to 59% of MQ trait variability. Moreover, functional analysis of correlated-trait genes provided information on the biological phenomena underlying MQ.

Comparison of muscle transcriptome between pigs with divergent meat quality phenotypes identifies genes related to muscle metabolism and structure.

BACKGROUND: Meat quality depends on physiological processes taking place in muscle tissue, which could involve a large pattern of genes associated with both muscle structural and metabolic features. Understanding the biological phenomena underlying muscle phenotype at slaughter is necessary to uncover meat quality development. Therefore, a muscle transcriptome analysis was undertaken to compare gene expression profiles between two highly contrasted pig breeds, Large White (LW) and Basque (B), reared in two different housing systems themselves influencing meat quality. LW is the most predominant breed used in pig industry, which exhibits standard meat quality attributes. B is an indigenous breed with low lean meat and high fat contents, high meat quality characteristics, and is genetically distant from other European pig breeds. METHODOLOGY/PRINCIPAL FINDINGS: Transcriptome analysis undertaken using a custom 15 K microarray, highlighted 1233 genes differentially expressed between breeds (multiple-test adjusted P-value<0.05), out of which 635 were highly expressed in the B and 598 highly expressed in the LW pigs. No difference in gene expression was found between housing systems. Besides, expression level of 12 differentially expressed genes quantified by real-time RT-PCR validated microarray data. Functional annotation clustering emphasized four main clusters associated to transcriptome breed differences: metabolic processes, skeletal muscle structure and organization, extracellular matrix, lysosome, and proteolysis, thereby highlighting many genes involved in muscle physiology and meat quality development. CONCLUSIONS/SIGNIFICANCE: Altogether, these results will contribute to a better understanding of muscle physiology and of the biological and molecular processes underlying meat quality. Besides, this study is a first step towards the identification of molecular markers of pork quality and the subsequent development of control tools.

A novel polymorphisms in intron 12 of the bovine calpastatin gene.

Calpastatin (CAST) is a specific inhibitor of the ubiquitous calcium-dependent proteases-mu-calpain and m-calpain, found in mammalian tissues. This proteolytic system plays a key role in the tenderization process that occurs during post-mortem storage of meat under refrigerated conditioning. Fragments of the bovine CAST gene including intron 12 were amplified and subjected to SSCP analysis. Four new SNPs were found within intron 12 of the CAST gene: a transition T/C at position 3893+155* A/G at position 3893+163, a transversion T/A at position 3893+223 and a substitution A/G at position 3893+428 (consensus sequence--GenBank AY834771). The genetic variants in the bovine CAST gene can be analyzed with RFLP method and was studied in 375 bulls of six breeds, including Hereford, Aberdeen-angus, Simmental, Charolaise, Limousine and Polish Black-and-White (BW; Fresian) breeds.