The genetic effects of the dopamine D1 receptor gene on chicken egg production and broodiness traits

Abstract

BackgroundThe elevation of egg production and the inhibition of incubation behavior are the aims of modern poultry production. Prolactin (PRL) gene is confirmed to be critical for the onset and maintenance of these reproductive behaviors in birds. Through PRL, dopamine D1 receptor (DRD1) was also involved in the regulation of chicken reproductive behavior. However, the genetic effects of this gene on chicken egg production and broodiness have not been studied extensively. The objective of this research was to evaluate the genetic effects of the DRD1 gene on chicken egg production and broodiness traits.ResultsIn this study, the chicken DRD1 gene was screened for the polymorphisms by cloning and sequencing and 29 variations were identified in 3,342 bp length of this gene. Seven single nucleotide polymorphism (SNPs) among these variations, including a non-synonymous mutation (A+505G, Ser169Gly), were located in the coding region and were chosen to analyze their association with chicken egg production and broodiness traits in 644 Ningdu Sanhuang individuals. Two SNPs, G+123A and C+1107T, were significantly associated with chicken broody frequency (P < 0.05). Significant association was also found between the G+1065A - C+1107T haplotypes and chicken broody frequency (P < 0.05). In addition, the haplotypes of G+123A and T+198C were significantly associated with weight of first egg (EW) (P = 0.03). On the other hand, the distribution of the DRD1 mRNA was observed and the expression difference was compared between broodiness and non-broodiness chickens. The DRD1 mRNA was predominantly expressed in subcutaneous fat and abdominal fat of non-broodiness chicken, and then in heart, kidney, oviduct, glandular stomach, hypothalamus, and pituitary. In subcutaneous fat and abdominal fat, the level of non-broodiness was 26 to 28 times higher than that of broodiness. In pituitary, it was 5-fold higher. In heart, oviduct, and kidney, a 2-3 times decrease from non-broodiness to broodiness was displayed. In glandular stomach and hypothalamus, the level seen in non-broodiness and broodiness was almost the same.ConclusionThe polymorphisms of the DRD1 gene and their haplotypes were associated with chicken broody frequency and some egg production traits. The mRNA distribution was significant different between broodiness and non-broodiness chickens.

Polymorphisms associated with egg number at 300 days of age in chickens

“…The dopaminergic system has been shown to play an important role in the regulation of the avian reproductive system and these physiological effects are exerted by activating its receptors (Sartsoongnoen et al, 2008;Xu et al, 2010b). Although Xu et al (2010a) did not find any association between the polymorphisms in the coding region of DRD1 and EN300, variation of the DRD2 gene exhibited a significant association with chicken EN300 in this study. As indicated by the present study, C1704887T, which is located in intron 6 of the VIPR-1 gene, was demonstrated to have a highly significant effect on chicken EN300.…”

“…the identification of molecular markers for it has been well performed (Dunn et al, 2004;Xu et al, 2010a;Zhou et al, 2010). In a commercial broiler breeder hen population, Dunn et al (2004) detected polymorphisms of the GnRHR and NPY genes and discovered an SNP in the intron 1 of the GnRHR gene and a 4-bp indel located 700 bp upstream of the NPY transcription start site.…”

“…Although there have been increasing studies on the relationship of genes with egg production (Dunn et al, 2004;Xu et al, 2010a), few genetic markers applied in MAS have been obtained. The objective of this study was to identify variations associated with EN300 in the candidate genes and QTL region.…”

Effects of genetic polymorphisms on egg production in indigenous Noi chicken

“…In the 2 INDEL variants, genotypic frequencies of VIP/VspI mutation did not follow the Hardy-Weinberg law (P<0.05) and comparable results were also found in other chicken populations. For example, on Ningdu Shanghuang breed, the frequency of C allele was higher than T allele in DRD2/BSeGI mutation point (Xu et al, 2010;Xu et al, 2011a;Xu et al, 2011b). In addition, Kim et al (2004) showed that C allele frequency (0.31) was lower than T allele (0.69) at IGF-I/PstI polymorphic position in Ogol chicken, but on the same Madandaran chicken, the distribution of 2 alleles was relatively equal (0.51 and 0.49) (Abbasi & Kazemi, 2011).…”

Genetic effect of the prolactin receptor gene on egg production traits in chickens

“…The candidate gene approach is a cost-effective means of investigating associations of gene polymorphisms and quantitative trait loci responsible for variations in traits of interest (Rothschild and Soller, 1997;Linville et al, 2001). Many studies have been carried out to identify associations between candidate gene SNPs and egg production traits (Xu et al, 2010(Xu et al, , 2011Huang et al, 2011;Xiao et al, 2011). However, more candidates are needed for marker-assisted selection.…”