Genetic effects of polymorphisms in candidate genes and the QTL region on chicken age at first egg

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.

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).…”

“…Enhancing and stabilizing breeding quality are one of the methods used to improve these indicators. Many candidate genes associated with poultry productivity have been identified (Abdi et al, 2014;Fatemi et al, 2012;Xu et al, 2011a;Xu et al, 2011b), as a result of the unprecedented improvements of genetic technology, especially molecular genetics.…”

“…Chaiseha et al (2003) cloned cDNA of the DRD2 gene in turkeys and pointed out the associations between DRD2 gene and production and hatching traits. Similarly, Xu et al (2011a;2011b) studied the g.5841629T>C polymorphism on DRD2 gene and found a significant association between first laying age and total egg production in chickens at 300 days of age. For IGF-1 gene, Li et al (2009) suggested that IGF-1 genetic polymorphism at position 5'UTR was related to egg production at 300 and 400 days of age and the number of continuous laying days.…”

Association of Dopamine D2 Receptor Gene Polymorphisms with Reproduction Traits in Domestic Pigeons (<i>Columba livia</i>)

“…In turkeys, two spliced isoforms were isolated and some studies suggested that the expression of the DRD2 mRNA was correlated with broodiness (Schnell et al, 1999). In chickens, studies indicated that the polymorphisms of DRD2 gene exhibited a significant association with chicken egg number at 300 days of age (Xu et al, 2011b), the age at first egg (Xu et al, 2011c), and broody frequency and duration of broodiness (Xu et al, 2010). Both of these studies suggested that DRD2 gene played a critical role on regulating the reproductive traits of avians.…”

Variancia intrapoblacional para caracteres de la madurez sexual en gallinas del cruzamiento Campero Casilda

“…Su trascendencia radica en que la puesta del primer huevo marca el inicio de la vida productiva o reproductiva, dependiendo del destino posterior que se le dé al huevo. En la gallina, al igual que en otras especies, la maduración sexual es consecuencia de una compleja cascada de eventos vinculados con el eje hipotálamohipófisis-gonadal (Xu et al, 2011), dependiente de la edad y el peso corporal (Brody et al, 1984) y de la composición corporal, incluyendo esta última tanto el contenido de grasa corporal (Bornstein et al, 1984) como el contenido del cuerpo libre de grasa o tejido magro (Soller et al, 1984). A su vez, la importancia del peso corporal y de la edad en relación con la madurez sexual cambia de acuerdo al régimen de alimentación.…”