Promising Loci and Genes for Yolk and Ovary Weight in Chickens Revealed by a Genome-Wide Association Study

Abstract

Because it serves as the cytoplasm of the oocyte and provides a large amount of reserves, the egg yolk has biological significance for developing embryos. The ovary and its hierarchy of follicles are the main reproductive organs responsible for yolk deposition in chickens. However, the genetic architecture underlying the yolk and ovarian follicle weights remains elusive. Here, we measured the yolk weight (YW) at 11 age points from onset of egg laying to 72 weeks of age and measured the follicle weight (FW) and ovary weight (OW) at 73 weeks as part of a comprehensive genome-wide association study (GWAS) in 1,534 F2 hens derived from reciprocal crosses between White Leghorn (WL) and Dongxiang chickens (DX). For all ages, YWs exhibited moderate single nucleotide polymorphism (SNP)-based heritability estimates (0.25–0.38), while the estimates for FW (0.16) and OW (0.20) were relatively low. Independent univariate genome-wide screens for each trait identified 12, 3, and 31 novel significant associations with YW, FW, and OW, respectively. A list of candidate genes such as ZAR1, STARD13, ACER1b, ACSBG2, and DHRS12 were identified for having a plausible function in yolk and follicle development. These genes are important to the initiation of embryogenesis, lipid transport, lipoprotein synthesis, lipid droplet promotion, and steroid hormone metabolism, respectively. Our study provides for the first time a genome-wide association (GWA) analysis for follicle and ovary weight. Identification of the promising loci as well as potential candidate genes will greatly advance our understanding of the genetic basis underlying dynamic yolk weight and ovarian follicle development and has practical significance in breeding programs for the alteration of yolk weight at different age points.

Transcriptome profiling of laser-captured germ cells and functional characterization of zbtb40 during 17alpha-methyltestosterone-induced spermatogenesis in orange-spotted grouper (Epinephelus coioides)

“…DHRS11 is a novel type of 17 β-hydroxysteroid dehydrogenase to tart part in the synthesis of estrogen and androgen in human [36]. In chicken, DHRS12 has been identified for its plausible function in yolk and follicle developments [37]. CYP3A40, a cytochrome P450 member, hydroxylates testosterone to regulate the metabolism of hormone in medaka [38].…”

Whole-Genome Resequencing of Holstein Bulls for Indel Discovery and Identification of Genes Associated with Milk Composition Traits in Dairy Cattle

“…Claire et al identified ACSBG2 as a candidate gene that was significantly related to abdominal fat deposition in chicken [48]. In addition, Sun et al demonstrated that one SNP located in an intron of ACSBG2 was also significantly associated with yolk development in chicken [49]. NFKB2 with one indel in upstream region encodes a protein subunit of the transcription factor complex nuclear factor-kappa-B (NFkB), which regulates the transcription of genes related to cell differentiation and proliferation.…”

Functional and whole regression-based genome-wide association analyses for weight measurements of chicken eggs

“…The results obtained from this study show that fGWAS can be useful for manipulating dynamic EW over the entire laying period (based on a moderate to major effect). The fGWAS SNPs that were associated with EW were located on chromosome 1, close to the gene DLEU7, which regulates ovary weight in chickens [14,33]. The SNPs were detected based on the absolute effect sizes using Bayes C(π) ( Table 5) and BL (Table 6) is likely useful for predicting the polygenic risk scores and/or genomic breeding values during genomic selection for longitudinal EW measurements.…”