Associations of the Novel Polymorphisms of Periostin and Platelet-Derived Growth Factor Receptor-Like Genes with Egg Production Traits in Local Chinese Dagu Hens.

The periostin (POSTN) and platelet-derived growth factor receptor-like (PDGFRL) genes are implicated in regulation of hen ovarian development. In the present study, these genes were explored as possible molecular markers associated with egg production, egg weight and body weight in Chinese Dagu hens. Samples were analyzed using the PCR-single strand conformation polymorphism (PCR-SSCP) method, followed by sequencing analysis, and three novel single nucleotide polymorphisms (SNPs) were identified within the candidate genes. Among them, an A/T transversion at base position 2727 in intron 2 of POSTN gene was found to be polymorphic and named SNP A2727T; and two transitions, G/A at position 6761 and A/G at base 6839 in exon 2 of PDGFRL gene were detected and named SNPs G6761A and A6839G, respectively. For the SNP A2727T, a total of 360 Dagu hens were classified as AA and AB genotypes, allele A was found present at a higher frequency. Moreover, the AA genotype was significantly correlated with higher hen-housed egg production (HHEP) at 43, 57, and 66 weeks (wks) of age and with a higher egg weight (EW) at 30 wks (P < 0.05). For the two linked SNPs (G6761A and A6839G) in the PDGFRL fragment, the hens were typed into TT, TC and CC genotypes, with the T allele shown to be dominant. The TT genotype was correlated with higher HHEP at 57 and 66 wks of age; genotype CC associated with the highest body weight and EW at 30 and 43 wks (P < 0.05), while it was correlated with the lowest HHEP at 57 and 66 wks of age (P < 0.05). Furthermore, five haplotypes were reconstructed based on these SNPs, with the AATT haplotype associated with the highest HHEP at 43 to 66 wks of age and higher EW at 30 wks (P < 0.05). Collectively, these SNPs identified in this study might be used as a potential molecular marker favorable to genetic improvement of egg productivity in chicken breeding.

Genetic effects of the transcription factors-sal-like 1 and spalt-like transcription factor 3 on egg production-related traits in Chinese Dagu hens.

Transcription factors (TFs) encoded by SALL1 and SALL3 genes play central roles in the regulation of ovarian development in hens. The present study aimed to examine polymorphisms of these two genes in Chinese Dagu chickens, and to identify the effects of TFs on the laying performance. Among the population, two novel single-nucleotide polymorphisms (SNPs) were identified by single-strand conformation polymorphism (SSCP) in the amplicons of the candidate genes. The effect of the SNP (729C > A) in exon 2 of SALL1 gene on egg production at 43, 57, and 66 weeks and EW at 30 and 43 weeks were the most significant in the 360 samples (P < 0.05). Moreover, for the SNP 1014T > A (in exon 2 of SALL3), the TT genotype was significantly correlated with higher egg production and EW (P < 0.05). Furthermore, four combined genotypes were reconstructed based on the two SNPs. The combined genotype TATT was correlated with the highest egg production at 43-66 weeks and with higher EW at 30, 43 weeks (P < 0.05). The polymorphisms of the two TFs studied are potential molecular genetic markers for chicken breeding, which might help in understanding the genetic structure of laying performance and improving these traits directly by marker-assisted selection (MAS).

Retraction Note: Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation.

This Article has been retracted.

Sequence variations in estrogen receptor 1 and 2 genes and their association with egg production traits in Chinese Dagu chickens.

Estrogen receptors α (ESR1) and ß (ESR2) play central roles in folliculogenesis and therefore in reproductive biology. In the present study, two single nucleotide polymorphisms (SNPs) were identified in the ESR1 and ESR2 genes using PCR-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing. One of the identified SNPs, a T1101C transition located within exon 4 of the ESR1 gene, was significantly associated with hen-housed egg production (HHEP) at 30, 43, 57 and 66 weeks of age (P<0.05), and egg weight (EW) at 30 weeks (P<0.05). Another SNP, a G1755A transition leading to a non-synonymous substitution (valine 459-to-isoleucine) located within exon 8 of the ESR2 gene, was also markedly correlated with the HHEP at 30, 43, 57 and 66 weeks of age (P<0.05), and EW at 30 weeks (P<0.05). A greater proportion of the additive variance was explained by the SNPs for most of the associated egg production traits (>1%). Furthermore, the results of the combined genotype-based association analysis supported the finding that the two SNPs were associated with the traits under a study. Taken together, our findings suggest that the two sequence variations in the ESR1 and ESR2 genes may provide promising genetic markers for the early selection and prediction of advantageous phenotypes in chicken breeding.

The Hippo/MST Pathway Member SAV1 Plays a Suppressive Role in Development of the Prehierarchical Follicles in Hen Ovary.

The Hippo/MST signaling pathway is a critical player in controlling cell proliferation, self-renewal, differentiation, and apoptosis of most tissues and organs in diverse species. Previous studies have shown that Salvador homolog 1 (SAV1), a scaffolding protein which functions in the signaling system is expressed in mammalian ovaries and play a vital role in governing the follicle development. But the exact biological effects of chicken SAV1 in prehierarchical follicle development remain poorly understood. In the present study, we demonstrated that the SAV1 protein is predominantly expressed in the oocytes and undifferentiated granulosa cells in the various sized prehierarchical follicles of hen ovary, and the endogenous expression level of SAV1 mRNA appears down-regulated from the primordial follicles to the largest preovulatory follicles (F2-F1) by immunohistochemistry and real-time RT-PCR, respectively. Moreover, we found the intracellular SAV1 physically interacts with each of the pathway members, including STK4/MST1, STK3/MST2, LATS1 and MOB2 using western blotting. And SAV1 significantly promotes the phosphorylation of LATS1 induced by the kinase of STK4 or STK3 in vitro. Furthermore, SAV1 knockdown by small interfering RNA (siRNA) significantly increased proliferation of granulosa cells from the prehierarchical follicles (6-8 mm in diameter) by BrdU-incorporation assay, in which the expression levels of GDF9, StAR and FSHR mRNA was notably enhanced. Meanwhile, these findings were consolidated by the data of SAV1 overexpression. Taken together, the present results revealed that SAV1 can inhibit proliferation of the granulosa cells whereby the expression levels of GDF9, StAR and FSHR mRNA were negatively regulated. Accordingly, SAV1, as a member of the hippo/MST signaling pathway plays a suppressive role in ovarian follicle development by promoting phosphorylation and activity of the downstream LATS1, may consequently lead to prevention of the follicle selection during ovary development.

Oxidized Low-density Lipoprotein (ox-LDL) Cholesterol Induces the Expression of miRNA-223 and L-type Calcium Channel Protein in Atrial Fibrillation.

Atrial fibrillation (AF) is the most common sustained arrhythmia causing high morbidity and mortality. While changing of the cellular calcium homeostasis plays a critical role in AF, the L-type calcium channel α1c protein has suggested as an important regulator of reentrant spiral dynamics and is a major component of AF-related electrical remodeling. Our computational modeling predicted that miRNA-223 may regulate the CACNA1C gene which encodes the cardiac L-type calcium channel α1c subunit. We found that oxidized low-density lipoprotein (ox-LDL) cholesterol significantly up-regulates both the expression of miRNA-223 and L-type calcium channel protein. In contrast, knockdown of miRNA-223 reduced L-type calcium channel protein expression, while genetic knockdown of endogenous miRNA-223 dampened AF vulnerability. Transfection of miRNA-223 by adenovirus-mediated expression enhanced L-type calcium currents and promoted AF in mice while co-injection of a CACNA1C-specific miR-mimic counteracted the effect. Taken together, ox-LDL, as a known factor in AF-associated remodeling, positively regulates miRNA-223 transcription and L-type calcium channel protein expression. Our results implicate a new molecular mechanism for AF in which miRNA-223 can be used as an biomarker of AF rheumatic heart disease.