Selection of reference genes for quantitative real-time PCR normalization in European quail tissues

Coturniculture has been standing out as an industrial poultry activity in several countries around the world because of the several adaptive advantages of quails. Research that considers the analysis of gene expression can enhance this activity. This study aimed to analyze the stability of reference genes (RGs) in different tissues of quails (both males and females) for the recommendation of use in gene expression studies by the quantitative reverse transcription-polymerase chain reaction (RT-qPCR). The expression stability of ten RGs (ACTA1, ACTB, B2M, GAPDH, HMBS, SDHA, HPRT1, MRPS27, MRPS30, and RPL5) was analyzed in four tissues (breast muscle, abdominal fat, liver, and intestine), and assessed using the statistical tools geNorm, NormFinder, comparative ΔC_q method, and BestKeeper. The HPRT1 gene was the most stable in all quail tissues tested, followed by MRPS27 and MRPS30 in breast muscle, B2M and RPL5 in abdominal fat, HMBS and B2M in the liver, and RPL5 and HMBS in the intestine. These results may help studies using RT-qPCR assays to assess quail tissues from both sexes because they provide data on the most stable genes, which should be tested as candidate RGs for other experimental conditions.

Heat stress induces expression of HSP genes in genetically divergent chickens

BACKGROUND

Chickens are animals that are sensitive to thermal stress, which may decrease their production level in terms that it affects feed intake and thus, decreasing body weight gain. The Heat Shock Factors (HSF) and Heat Shock Proteins (HSP) genes are involved in the key cellular defense mechanisms during exposure in hot environments. Aimed with this study to analyze the expression of HSF1, HSF3, HSP70 and HSP90 genes in two local breeds (Peloco and Caneluda) and a commercial broiler line (Cobb 500®) to verify differences in resistance of these chicken to Heat stress treatment. Chicken were submitted to heat stress under an average temperature of 39°C ± 1.

RESULTS

Under stress environment, the HSP70 and HSP90 genes were more expressed in backyard chickens than in broiler. There was a difference in HSP70 and HSP90 expression between Caneluda and Cobb and between Peloco and Cobb under stress and comfort environment respectively. HSP70 expression is higher in local breeds during heat stress than in a commercial broiler line. No significant differences were observed in the expression of HSF1 and HSF3 genes between breeds or environments.

CONCLUSIONS

HSP70 and HSP90 genes are highly expressed, HSF1 and HSF3 genes did not have high expression in all genetic groups. HSP70 and HSP90 are highly expressed in Peloco and Caneluda within heat stress, these breeds proved to be very resistant to high temperature.

Influence of heat stress, sex and genetic groups on reference genes stability in muscle tissue of chicken

Quantitative RT-PCR is an important technique for assessing gene expression. However, a proper normalization of reference genes prior to expression analyses of target genes is necessary. The best normalizer is that gene which remains stable in all samples from different treatments. The aim of this study was to identify stable reference genes for normalization of target genes in muscle tissue from three genetically divergent chickens groups (Peloco, Cobb 500^® and Caneluda) under environmental (heat stress and comfort) and sex influence. Expressions of ten reference genes were tested for stability in breast muscular tissue (Pectoralis major muscle). Samples were obtained from 36 males and females of two backyard breeds (Caneluda and Peloco) and one commercial line (Cobb 500^®) under two environments. The heat stress and comfort temperature were 39 and 23°C, respectively. Animals were housed in the Animal Science Department at Universidade Estadual do Sudoeste da Bahia. We analyzed the expression data by four statistical tools (SLqPCR, NormFinder, Bestkeeper and Comparative CT). According to these tools, genes stability varied according to sex, genetic group and environment, however, some genes remained stable in all analyzes. There was no difference between the most stable genes for sex effect, being MRPS27 more stable for both males and females. In general, MRPS27 was the most stable gene. Within the three genetic groups, the most stable genes were RPL5, HMBS and EEF1 to Cobb 500^®, Peloco and Caneluda, respectively. Within the environment, the most stable gene under comfort and heat stress conditions was HMBS and MRPS27, respectively. BestKeeper and Comparative Ct were less correlated (28%) and SLqPCR and NormFinder were the most correlated (98%). MRPS27, RPL5 and MRPS30 genes were considered stable according the overall ranking and can be used as normalizer of relative expression of target genes in muscle tissue of chickens under heat stress.