The objective of this study was to evaluate the effect of heat stress and methionine supplementation on the gene expression of insulin-like growth factor I (IGF-I), growth hormone receptor (GHR), phosphatidylinositol 3-kinase, and regulatory 1 (PI3KR1) in the liver, as well as the expression of the atrogin 1 and cathepsin L2 (CTSL2) genes in the breast muscle of broilers. Broilers from 1–21 and 22–42 days of age were divided into three treatments related to methionine supplementation as follows: without methionine supplementation (MD), recommended level of methionine (DL1), and excess supplementation of methionine (DL2). The animals were either maintained at a thermal comfort temperature or exposed to heat stress (HS) (38°C for 24 hours, starting on day 20 or day 41 for experiments 1 and 2, respectively). The heat stress increased the body temperature at both ages. Starter period: The HS animals presented increased plasma creatinine content (P<0.0001) and the highest CTSL2 gene expression (P<0.0001). The methionine supplementation increased the IGF-I (P = 0.0144) and GHR (P = 0.0011) gene expression and decreased the CTSL2 (P = 0.0004) and atrogin 1 (P = 0.0012) gene expression. Grower period: Significant effects for the interaction between supplementation and environment were observed for GHR (P = 0.0252) and CTSL2 (P = 0.0011) gene expression. The highest GHR expression was observed in animals that remained in thermal comfort on the DL2 diet, and the lowest expression occurred in the HS animals fed the MD diet. For CTSL2, the HS animals fed the MD diet presented the highest CTSL2 gene expression, and the lowest expression was observed in the animals maintained at thermal comfort on DL1 and DL2 diets. Only methionine supplementation had effect on atrogin-1 gene expression (P<0.0001), with higher methionine content in the diet lower atrogin-1 gene expression was observed. Our results suggest that heat stress induces greater protein degradation and that methionine supplementation could induce protein deposition because methionine increased the expression of genes related to protein synthesis and decreased the expression of genes related to protein breakdown.

The aim of the present study was to evaluate the effects of heat stress (HS) and methionine supplementation on the markers of stress and on the gene expression levels of uncoupling proteins (UCP), betaine -homocysteine methyltransferase (BHMT), cystathionine b-synthase (CBS), glutathione synthetase (GSS) and glutathione peroxidase 7 (GPx7). Broilers from 1 to 21 d and from 22 to 42 d of age were divided into three treatment groups related to methionine supplementation: without methionine supplementation (MD); recommended level of methionine supplementation (DL1); excess methionine supplementation (DL2). The broilers were either kept at a comfortable thermal temperature or exposed to HS (388C for 24 h). During the starter period, we observed the effects of the interaction between diet and environment on the gene expression levels of UCP, BHMT and GSS. Higher gene expression levels of UCP and BHMT were observed in broilers that were maintained at thermal comfort conditions and received the MD diet. HS broilers fed the DL1 and DL2 diets had the highest expression level of GSS. The expression levels of the CBS and GPx7 genes were influenced by both the environment and methionine supplementation. During the grower period, the gene expression levels of BHMT, CBS, GSS and GPx7 were affected by the diet £ environment interaction. A higher expression level of BHMT was observed in broilers maintained at thermal comfort conditions and on the MD diet. HS induced higher expression levels of CBS, GSS and GPx7 in broilers that received the DL1 and DL2 diets. The present results suggest that under HS conditions, methionine supplementation could mitigate the effects of stress, since methionine contributed to the increased expression levels of genes related to antioxidant activity.

The associations of leptin (LEP) gene polymorphisms C798T, T2411C, T3266G and T3469C with production traits were investigated in a F2 pig population produced by divergent crosses. The statistical model included genotype, sex, batch and genotype by sex interaction as fixed effects and sire as random effect. Polymorphism C798T was associated with variation in total teat number (p < 0.02) and left teat number (p < 0.03), and polymorphism T3469C was associated with weight at 21 days (p < 0.03), 42 days (p < 0.05), 63 days (p < 0.02) and 77 days of age (p < 0.04) as well as feed intake (p < 0.01), average daily gain (p < 0.01), feed conversion (p < 0.01), bacon depth (p < 0.03) and slaughter weight (p < 0.03). Phenotypic associations were also performed by combining T3469C and C798T genotypes. Interaction between C798T genotypes and sex was observed for some traits. LEP genotypes had significant influence on performance traits, and can be considered as potential genetic markers for selection. However, these results have to be validated in commercial herds.

ABSTRACT. Calpastatin (CAST) is an endogenous calpain inhibitor and its main function is to modulate the proteolytic action of enzymes responsible for post-mortem myofibril deterioration. The myostatin gene (GDF-8) acts as a negative regulator of skeletal muscle growth. The expression of these two genes, as well as their interaction, affects the quality of the meat, especially the tenderness phenotype. We evaluated the genetic groups Santa Inês, ½ Dorper-Santa Inês and ½ White Dorper-Santa Inês, slaughtered with 2.0 mm, 2.5 mm and 3.0 mm of fat thickness, comparing the levels of expression of the CAST and GDF-8 genes with the weight performance and carcass traits, especially the shear force values. We found significantly higher expression of myostatin and calpastatin in the Santa Inês genetic group. The ½ Dorper-Santa Inês genetic group had the lowest expression of these genes when slaughtered with 2.0 and 2.5 mm of fat thickness. In conclusion, the Santa Inês breed had the lowest phenotype values for meat tenderness, and the ½ Dorper-Santa Inês breed had the best performance for this characteristic. We suggest that high levels of the 6169 ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 12 (4): 6168-6175 (2013) Gene expression associated with lamb meat quality expression of the CAST and GDF-8 genes are associated with lower values of lamb meat tenderness, and that tenderness is related to the stage of muscular growth and development.

ABSTRACT. Heat stress is one of the main problems in modern aviculture, since it affects birds especially in the final phase of rearing, causing bird mortality and economic losses to the aviculturist. The quail, as most birds, has difficulties in dissipating heat. However, little is known about the mechanism that controls the responses of the organism to stressor agents. Therefore, the study of heat shock proteins (HSPs) in these birds is important. A 960-bp portion of HSP70 was amplified using oligonucleotide primers specific for chickens. The fragment was sequenced, since it was the same protein, although some modifications have been observed. It showed 98% homology with HSP70 stress protein in Gallus gallus and 99% homology with Numida meleageris.

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-Three different regions of the alpha s1 -casein gene (CSN1S1) were investigated to determine the frequencies of major alleles for null, low, intermediate and high milk protein expression in a herd of dairy goats raised in the southeastern region of Brazil. Genomic DNA samples were obtained from leukocytes of 145 dairy goats and regions of interest in the gene were amplified through Polymerase Chain Reaction (PCR), then evaluated in both agarose (O and E allele) and polyacrylamide gels (F allele). For better characterization of the F allele, a PCR-RFLP (PCR-Restriction Fragment Length Polymorphism) study was performed employing the endonuclease XmnI. The allelic frequencies in the herd of 62 Saanen goats studied were: CSN1S1 E = 0.35; CSN1S1 F = 0.30; CSN1S1 O1 = 0.02; CSN1S1 A+B+C = 0.30, other alleles = 0.03. In another group of 83 Alpine animals, the frequencies were: CSN1S1 E = 0.48; CSN1S1 F = 0.28; CSN1S1 O1 = 0.01; CSN1S1 A+B+C = 0.20, other alleles = 0.03. In the region of exon 9 and intron downstream, where mutations that characterize the F allele occur, it was verified that different intragenic haplotypes may exist, involving the deletion of the 23rd nucleotide in the ninth exon in addition to the insertion of 11bp on intron. These haplotypes may be used to make direct association with other alleles.Although rare, a higher number of combinations were found in this work by evaluating in conjunction the region of the insertion of 3bp in the referred intron, which may allow a higher number of associations. A complete characterization of these combinations will allow elaborating simplified protocols to identify animals concerning the alleles of CSN1S1 gene in goats. CSN1S1 A+B+C = 0.20; outros alelos = 0.03. Na região do exon e intron 9, onde ocorrem as mutações que caracterizam o alelo F, podem existir diferentes haplótipos intragênicos, envolvendo a deleção do 23º nucleotídeo do exon 9, e a inserção de 11pb no intron subsequente. Esses haplótipos podem ser utilizados para associação direta a outros alelos.Embora raro, neste trabalho foi encontrado maior número de combinações ao se avaliar, juntamente com as outras duas mutações, a região da inserção de 3pb no mesmo intron, o que pode permitir maior número de associações. A completa caracterização dessas combinações permitirá elaborar protocolos mais simplificados para a identificação de animais quanto aos demais alelos do gene CSN1S1 em caprinos leiteiros.Palavras-chave: Alpina, Capra hircus, CSN1S1, genotipagem, proteínas do leite, Saanen R. Bras.