Abstract
BackgroundThe age at first egg (AFE), an important indicator for sexual maturation in female chickens, is controlled by polygenes. Based on our knowledge of reproductive physiology, 6 genes including gonadotrophin releasing hormone-I (GnRH-I), neuropeptide Y (NPY), dopamine D2 receptor (DRD2), vasoactive intestinal polypeptide (VIP), VIP receptor-1 (VIPR-1), and prolactin (PRL), were selected as candidates for influencing AFE. Additionally, the region between ADL0201 and MCW0241 of chromosome Z was chosen as the candidate QTL region according to some QTL databases. The objective of the present study was to investigate the effects of mutations in candidate genes and the QTL region on chicken AFE.ResultsMarker-trait association analysis of 8 mutations in those 6 genes in a Chinese native population found a highly significant association (P < 0.01) between G840327C of the GnRH-I gene with AFE, and it remained significant even with Bonferroni correction. Based on the results of the 2-tailed χ2 test, mutations T32742394C, T32742468C, G32742603A, and C33379782T in the candidate QTL region of chromosome Z were selected for marker-trait association analysis. The haplotypes of T32742394C and T32742468C were significantly associated (P < 0.05) with AFE. Bioinformatics analysis indicated that T32742394C and T32742468C were located in the intron region of the SH3-domain GRB2-like 2 (SH3GL2) gene, which appeared to be associated in the endocytosis and development of the oocyte.ConclusionThis study found that G840327C of the GnRH-I gene and the haplotypes of T32742394C-T32742468C of the SH3GL2 gene were associated with the chicken AFE.
Highlights
The age at first egg (AFE), an important indicator for sexual maturation in female chickens, is controlled by polygenes
gonadotrophin releasing hormone-I (GnRH-I), neuropeptide Y (NPY), DRD2, vasoactive intestinal polypeptide (VIP), VIP receptor-1 (VIPR-1) and PRL were selected to undertake association analysis in an Ningdu Sanhuang (NDH) population and 3 significant effects (P < 0.05) on chicken AFE were observed in single analysis: for C31394761T of the NPY gene, T5841629C of the DRD2 gene, and A1661691G of the VIPR-1 gene
A different mutation site was analyzed in this study, the NPY gene was proved to be important for chicken AFE
Summary
The age at first egg (AFE), an important indicator for sexual maturation in female chickens, is controlled by polygenes. Based on our knowledge of reproductive physiology, 6 genes including gonadotrophin releasing hormone-I (GnRH-I), neuropeptide Y (NPY), dopamine D2 receptor (DRD2), vasoactive intestinal polypeptide (VIP), VIP receptor-1 (VIPR-1), and prolactin (PRL), were selected as candidates for influencing AFE. The age at first egg (AFE) is one of the direct indicators for sexual maturation in female chickens. Kadarmideen found that prolactin (PRL) was one of the major regulators of GnRH and GnRH receptors and validated its important role in mammalian reproduction and sexual maturity [22]. VIP and VIP receptor-1 (VIPR-1), as well as PRL were chosen as candidates to analyze the genetic effects on chicken AFE
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