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The STATs are a family of transcription factors. STAT5A, previously known as MGF, transduces prolactin signals to the milk-protein genes. Here, we describe the detection of nucleotide sequence polymorphism in exon 16 of the bovine STAT5A gene, coding for the SH2 domain. SSCP was found in a 281-bp PCR amplified gene fragment, lying between positions 12,525 and 12,806, and encompassing parts of intron 15 and exon 16 of the bovine STAT5A gene (GenBank AJ 237937). Three SSCP patterns (genotypes) were identified in a group of 108 animals of different cattle breeds. The DNA sequencing showed that they differed by a CCT deletion at position from 12,549 in intron 15, and a T→C substitution at position 12,743 in exon 16. The latter mutation changes an amino acid sequence in the STAT5A protein - a Val/Ala substitution at position 686. Since T→C substitution creates a new Msl1 site, genetic variants in the bovine STAT5A gene can be distinguished with RFLP analysis. The frequency of alleles T and C varied between the different cattle breeds studied; the CC genotype was the least frequent and the frequency of alleles T and C was 0.842 and 0.158, respectively. Proteins were extracted from the cell nuclei of liver tissues derived from bulls of different STAT5A genotypes and subjected to EMSA in order to study if the amino acid substitution might change the DNA-binding capacity of STAT5A transcription factor. Statistically significant (p<0.05) differences in nuclear protein binding to DNA were observed between genotypes TT and CC; nuclear proteins derived from CC animals always showed less DNA protein complexing than those of TT animals. EMSA competition experiments confirmed that STAT5 transcription factors take part in the formation of the DNA-protein complexes.
The association was studied between the polymorphism at leptin (LEP), Pit1, and STAT5A loci and meat production traits in 145 Black-and-White growing/fattening bulls. Genotypes of LEP, Pit1 and STAT5A were determined with the PCR-RFLP technique. Over the 8th month of age the 28-day performance test was introduced to assess growth rate and feed conversion during which the fullconcentrate diet was offered ad libitum. At the age of 15 months the bulls were slaughtered, and their carcasses cut and dissected into lean, fat and bone.The allele frequencies were 0.85, 0.07, and 0.08 for A, B and C LEP variants, 0.25 and 0.75 for A and B Pit1 variants, and 0.90 and 0.10 for C and T STAT5A variants, respectively. Polymorphism of lepton significantly affected some carcass traits, and among them the weight of carcass-side that was highest in the AA homozygotes. The effect of Pit1 genotype was observed on carcass dimensions only. The AA homozygotes had higher chest circumference, chest depth, and circumference of round, but BB homozygotes had a higher round width. CT genotype of the STAT5A-encoding gene significantly affected four out of 36 carcass traits measured and was related to higher weight of bone of best + fore ribs (4.2 vs 3.8 kg) and of sirloin (1.6 vs 1.3 kg) as well as to oblique carcass length (140.5 vs 138.5 cm). The CC STAT5A genotype was associated with significantly higher live weight gain from 8 to 15 months (1.04 vs 0,97 kg daily).
STAT5 is a group of transcription factors that mediate signals from prolactin and growth hormone. Therefore, STAT5A gene is a candidate marker for quantitative traits in farm animals. In this study the new nucleotide sequence polymorphism was found in the coding region of the bovine STAT5A gene - substitution C→T at position 6853 within the exon 7. As this mutation creates new AvaI/DdeI restriction site it could be easily detected with PCR-RFLP analysis. The RFLP-AvaI polymorphism was studied in cattle (n = 146) belonging to eight breeds, including two considered as Polish native. The overall frequencies of alleles C and T were 0.82 and 0.18, respectively.The genotype TT was found exclusively in both native breeds (Polish Red and White-Back).Moreover, for the first time an association was reported between STAT5A gene polymorphism and beef production traits in cattle (n = 71). In the animals of the CC genotype the live body weight at the age of 9 and 15 months, live weight gain (0-15 months), dressing percentage and four carcass traits were found more favourable than in CT animals. Individuals CC used less feed for maintenance and meat production.
Myogenic factor 5 (myf-5) is the product of the MYF5 gene, belonging to the MyoD family. This transcription factor participates in the control of myogenesis. We identified 3 new mutations in the promoter region of the gene: A65C, C580T and C613T. The aim of this study was to evaluate the influence of the A65C transversion on gene expression. The analysis was conducted on 15 Polish Large White gilts. The relative content of MYF5 mRNA in m. longissimus dorsi did not differ significantly across MYF5 genotypes (AA, AC, CC). This result suggests that the A65C transversion may not play an important role in the expression of the MYF5 gene in analysed adult muscle but it abolishes a putative binding site for two transcription factors (CDP and HSF1) and creates such a site for Sp1.
Because of the antimicrobial role that defensins play in humans and animals, genes encoding these peptides may be considered as molecular markers of a genetically determined susceptibility (or resistance) of the mammary gland to mastitis. Records were gathered of daily milk yield, fat, protein, and lactose content of milk, and milk somatic cell count (SCC) of 217 lactating Black-and-White cows. To determine the defensin gene polymorphism, DNA was isolated from blood and the RFLP method with enzyme TaqI was used. Twenty different polymorphic systems were revealed, possibly representing variants of genes encoding different defensins. Statistical evaluation included cows with more than seven records, and showing the 2.5% frequency of combined defensin genotypes (CDGs). In this way 13 different CDGs of 204 cows appeared available for statistical evaluation. CDGs significantly affected all dairy performance traits studied, as well as SCC. The important message from these results is that the defensin(s) may probably be used as genetic marker(s) in the breeding programmes aiming at selecting highly productive dairy cattle with increased resistance to udder infections.
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.
In the present study we show FISH localization of 4 porcine BAC clones harbouring potential candidate genes for fatness traits: DGAT1 (SSC4p15), PPARA (SSC5pl5), ADIPOR1 (SSC10p13) and CREB (SSC15q24). Until now the CREB and ADIPOR1 genes are considered to be monomorphic, DGAT1 is highly polymorphic, while for the PPARA gene only 1 SNP was identified. Assignment of the studied genes in relation to QTL chromosome regions for meat quality in pig chromosomes SSC4, SSC5, SSC10 and SSC15 is discussed.
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