Evaluation and Validation of the Six Housekeeping Genes for Normalizing Mrna Expression in the Ovarian Follicles and Several Tissues in Chicken

ABSTRACT Expression of housekeeping genes is relatively constant in different tissues and cells by RT-qPCR analysis. Housekeeping genes (HGs) are usually utilized as the reference to evaluate and compare mRNA expression abundances of target genes in different cells or tissues sampled. However, the expression stabilities of different HGs in diverse samples may appear divergence. Currently, there is no exact reference data of HGs in hen ovarian follicular tissues during egg-laying period available yet. In this study, we detected the expression of 18SrRNA, ACTB, HOXC8, GAPDH, alpha-A, and alpha-D mRNA in the varied-size ovarian follicles (1-8 mm in diameter and F5), hearts, livers, spleens, lungs, and breast muscles of the laying hens by RT-qPCR, to analyze the results via Ct value, geNorm, Normfinder, and Bestkeeper. The data showed that the expression levels of 18SrRNA, alpha-A, and alpha-D transcripts were more significantly stable than the other three genes for normalizing mRNA expression in the hen ovarian follicles examination. Moreover, alpha-D, 18SrRNA, and alpha-A were also most suitable for the expression normalization in the tissues of the heart, liver, spleen, lung and breast muscle. In contrast, 18SrRNA has the most stable mRNA expression levels in all tissues sampled, so it can serve as an excellent inner control for the evaluation of the transcription levels in chickens. It is a remarkable fact that HOXC8 as a candidate reference should be avoided. Our study establishes a set of stably expressed candidate inner references in the hen ovarian follicles and several tissues, it firstly provided an exact data for validation of the inner references in normalizing transcription levels of a target gene in chickens.