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In addition to highly productive breeds of pigs, Polish breeders keep local pigs subject to the conservation programme including Pulawska (P) pig. Analysis of records spanning 20 years showed that lean content of P carcass increased from 41.43% in 1983 to 45.68% in 2003, with a simultaneous decrease in fat content. Considering the relatively high rate of changes in these traits, it would be interesting to find out parameters that could serve as a criterion for evaluating the degree of heterozygosity in P pig. The aim of this study was, therefore, to determine the melanocortin receptor gene polymorphism in P pig and its effect on carcass quality. The study involved 66 P fatteners. After slaughter and 24-hour cooling at 4°C, linear measurements of carcasses were taken and dissection was made according to the Walstra and Merkus method. Genotype analysis showed the highest frequency of MC4RA/G and the lowest of MC4RA/A animals. Frequency of the allele MC4RA was only by 15.2 per cent units lower than that of the MC4RG allele. The MC4RA allele showed a significant effect on increasing backfat thickness, especially over the loin and was significantly correlated with a greater fat amount of neck. Animals with the A allele at the MC4R locus were also characterized by a significantly lower amount of lean in this cut. The results obtained for frequency of different genotypes in P pig could serve as reference values for selection-induced changes, thus reflecting the level of genetic variation in the breed.
Troponin is a regulatory proteins complex composed of subunits TnC, TnI, and TnT encoded by separate genes – TNNT1, TNNT2 and TNNT3. It is a component of thin filaments (along with actin and tropomyosin), to which calcium binds to accomplish this regulation. The TPM2 gene encodes beta-tropomyosin. An imprinted QTL for muscle mass deposition has been detected near the TNNT3 gene and several significant linkages between TPM2 and QTLs on chromosome 1 have been identified. However, no significant correlation was found between polymorphism in both genes and economically important pig traits. The study aimed at analysing the level of expression of TNNT3 and TPM2 in the developing muscle (day 60-210 of life) and determining the expression differences among Polish Large White, Polish Landrace, Pulawska, Duroc and Pietrain pigs. Within the mentioned period the expression level of both genes in question did not change significantly. No developmental pattern characteristic for all breeds was revealed. In PL gilts a highly significant correlation was found among the level of expression in both white muscles (longissimus dorsi and semimembranosus) and the animals’ maternal origin. The above results suggest that an unknown polymorphism, probably located in regulatory part of the gene has an effect on the level of TNNT3 expression. Expression of the TPM2 did not change during ontogenesis and was not correlated with maternal origin. However, significant differences among gilts of different breeds were identified.
The calpain family includes proteolytic enzymes, which have a high capacity to degrade cytoskeletal and muscle fibre proteins. Thus they play an important role in the fusion of myoblasts and in cell proliferation and growth. The CAPN1 gene has been selected as a ‘candidate gene’ for meat quality in many domestic animals, including chickens. Consequently, the aim of our study was to identify new polymorphisms in the promoter region of the CAPN1 gene in broilers and to investigate their impact on CAPN1 transcript abundance in breast muscles. The experiment used broilers of two genetic lines, fast- and slow-growing. Five new polymorphisms in the promoter region of the CAPN1 gene were identified, all of them in linkage disequilibrium (P<0.05). However, the results obtained for their association with expression level were doubtful. Therefore, we surmise that the newly discovered polymorphisms, although they alter the potential sequence binding of transcription factors, probably have just a weak effect on the level of CAPN1 expression in broiler chickens at the investigated stage of ontogenesis.
Using the GLM procedure an association was analysed between PIT1 and GHRH SNPS and economically important traits in pigs of three breeds reared in Poland. Significant effect of GHRH/AluI SNP was observed on several quality traits such as water-holding capacity and meat colour (A,B and L*) in Polish Large White pigs (P<0.05), with the differences between alternative homozygotes being 8.1%, and 5% (meat colour), and 16% and 3% (WHC), respectively. With respect to the PIT1 gene polymorphism, it was found that pigs carrying AA genotype presented lower values of growth traits such as feed:gain ratio, daily feed intake and number of days on test compared to BB animals (P<0.05) as well as lower pH24 in loin and ham. In turn, heterozygous pigs (AB) had the highest level of fat and the lowest values of meat traits when compared to both homozygotes. It was concluded that polymorphisms in GHRH and PIT1 genes were not directly associated with quality and carcass traits, and likely they are linked to genetic markers localized on chromosomes 17 and 13. Therefore,further investigations should aim at thorough testing of GHRH and PIT1 loci.
Growth and development traits are economically important in animal production, especially in pig breeding. Therefore, the porcine GHRL gene is considered as a candidate gene responsible for growth rate and body weight. The aim of our study was to identify new polymorphisms in the GHRL gene in pig. Ten novel single nucleotide polymorphisms (SNP’s) were detected: four substitutions in exons, four in introns and two mutations in promoter region. We evaluated the GHRL mRNA abundance in porcine stomachs (fundus ventriculis) and ghrelin protein concentration in plasma in three breeds: Polish Landrace, Polish Large White and Pietrain. The results showed that transcript abundance of GHRL gene was significantly higher in Polish Landrace than in other two breeds (P<0.05). The mutation c.-93A>G located in the promoter region affected expression of the GHRL gene. The AA genotype animals showed a significantly (P<0.05) higher expression level when compared to AG genotype animals.
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