The sodium channel gene family is specifically expressed in hen uterus and associated with eggshell quality traits

Abstract

Background: Eggshell quality is important for the poultry industry. During eggshell formation a mass of inorganic minerals is deposited. The Sodium Channel (SCNN1) gene family plays an essential role in cation transportation. The objective of this study was to investigate the pattern of expression of members of the SCNN1 gene family, their variation and their effects on eggshell quality.

Result: The highest expression of SCNN1a, SCNN1b, and SCNN1g genes were in the active uterus during eggshell mineralization, while SCNN1d showed its highest expression level in the quiescent uterus (no egg present). Nineteen candidate SNPs from the four genes were genotyped in a population of 338 White Leghorn layers. Association analysis between SNPs (haplotypes/diplotypes) and eggshell traits was performed. Among seven significant SNPs, five SNPs were associated with eggshell strength, eggshell thickness, eggshell percentage or/and egg weight, while the other two SNPs within SCNN1d were only associated with eggshell percentage. These SNPs had a 0.25-6.99% contribution to phenotypic variance, depending on the trait. In haplotype analysis, SCNN1b and SCNN1d were associated with egg weight. The SCNN1b and SCNN1g were significantly associated with eggshell weight while only SCNN1g explained 2.04% of phenotypic variance. All the alleles of the members of SCNN1 gene family were associated with eggshell percentage and eggshell thickness, and others members had an association with eggshell strength except for SCNN1a. The contribution of different haplotypes of the SCNN1 gene family to eggshell phenotypic variance ranged from 0.09% to 5.74%.

Conclusions: Our study indicated that the SCNN1 gene family showed tissue expression specificity and was significantly associated with eggshell traits in chicken. This study provides evidence that genetic variation in members of the sodium channel can influence eggshell quality.

Figure 1

Comparison of relative expression of SCNN1 gene family members vs β-actin measured by qPCR in different tissues. The kidney was collected from four normal 49-Week-old White Leghorn layers while all others tissues, breast muscle, liver, jejunum, ovary, magnum, isthmus, active uterus (during eggshell deposition) and quiescent uterus (no egg present at time of tissue collection) were collected from four normal 55-week-old White Leghorn layers. The y-axis indicates the relative expression level of each SCNN1 family member. Different letters (A,B,C, D) represent significant difference (P < 0.05). Panel (a), Panel (b), Panel (c) and Panel (d) represents the expression of the SCNN1a, SCNN1b, SCNN1g and SCNN1d, respectively.

Figure 2

Fold change of the relative expression by qPCR of SCNN1 gene family members in active uterus (eggshell mineralizing) of 49-week-old hens compared to 16-week-old pullets. Expression in the 49-week-old adult hen active uterus was compared with expression in pullet uterus. * represents a significant difference (p < 0.05). The expressions of all four genes are significantly increased in 49-week-old adult hens compared to 16-week-old pullets.