Genome-wide identification evolution and expression of vestigial-like gene family in chicken.

Vestigial-like (Vgll) genes are widespread in vertebrates and play an important role in muscle development. In this study, we used bioinformatics methods to systematically identify the chicken VGLL family in the whole genome and investigated its evolutionary history and gene structure features. Tissue expression spectra combined with real-time PCR data were used to analyze the organizational expression pattern of the genes. Based on the maximum likelihood method, a phylogenetic tree of the VGLL family was constructed, and 94 VGLL genes were identified in 24 breeds, among which four VGLL family genes were identified in the chicken genome. Ten motifs were detected in the VGLL genes, and the analysis of introns combined with gene structure revealed that the family was conserved during evolution. Tissue expression analysis suggested that the expression profiles of the VGLL family genes in 16 tissues differed between LU Shi and AA broilers. In addition, a single gene (VGLL2) showed increased expression in chickens at embryonic days 10-16 and was involved in the growth and development of skeletal muscle in chickens in the embryonic stage. In summary, VGLL genes are involved in chicken muscle growth and development, which provides useful information for subsequent functional studies of VGLL genes.

A 104-bp Structural Variation of the ADPRHL1 Gene Is Associated With Growth Traits in Chickens.

Analyzing marker-assisted breeding is an important method utilized in modern molecular breeding. Recent studies have determined that a large number of molecular markers appear to explain the impact of "lost heritability" on human height. Therefore, it is necessary to locate molecular marker sites in poultry and investigate the possible molecular mechanisms governing their effects. In this study, we found a 104-bp insertion/deletion polymorphism in the 5'UTR of the ADPRHL1 gene through resequencing. In cross-designed F2 resource groups, the indel was significantly associated with weight at 0, 2, 4, 6, and 10 weeks and a number of other traits [carcass weight (CW), semi-evisceration weight (SEW), evisceration weight (EW), claw weight (CLW), wings weight (DWW), gizzard weight (GW), pancreas weight (PW), chest muscle weight (CMW), leg weight (LW), leg muscle weight (LMW), shedding Weight (SW), liver rate (LR), and leg muscle rate (LMR)] (P < 0.05). In brief, the insertion-insertion (II) genotype was significantly associated with the greatest growth traits and meat quality traits, whereas the values associated with the insertion-deletion (ID) genotype were the lowest in the F2 reciprocal cross chickens. The mutation sites were genotyped in 4,526 individuals from 12 different chicken breeds and cross-designed F2 resource groups. The II genotype is the most important genotype in commercial broilers, and the I allele frequency observed in these breeds is relatively high. Deletion mutations tend to be fixed in commercial broilers. However, there is still considerable great potential for breeding in dual-purpose chickens and commercial laying hens. A luciferase reporter assay showed that the II genotype of the ADPRHL1 gene possessed 2.49-fold higher promoter activity than the DD genotype (P < 0.05). We hypothesized that this indel might affect the transcriptional activity of ADPRHL1, thereby affecting the growth traits of chickens. These findings may help to elucidate the function of the ADPRHL1 gene and facilitate enhanced reproduction in the chicken industry.

Molecular characterization and a duplicated 31-bp indel within the LDB2 gene and its associations with production performance in chickens.

Many studies have shown that the LDB2 gene plays a regulatory role in retinal development and the cell cycle, but its biological role remains unclear. In this study, a 31-bp indel in the LDB2 gene was found for the first time on the basis of 2797 individuals from 10 different breeds, which led to different genotypes among individuals (II, ID and DD). Among these genotypes, DD was the most dominant. Association analysis of an F2 resource population crossed with the Gushi (GS) chicken and Anka chicken showed that the DD genotype conferred a significantly greater semi-evisceration weight (SEW, 1108.665 g ± 6.263), evisceration weight (EW, 927.455 g ± 5.424), carcass weight (CW, 1197.306 g ± 6.443), breast muscle weight (BMW, 71.05 g ± 0.574), and leg muscle weight (LMW, 100.303 g ± 0.677) than the ID genotype (SEW, 1059.079 g ± 16.86; EW, 879.459 g ± 14.446; CW, 1141.821 g ± 17.176; BMW, 67.164 g ± 1.523; and LMW, 96.163 g ± 1.823). In addition, LDB2 gene expression in different breeds was significantly higher in the breast muscles and leg muscles than in other tissues. The expression level in the breast muscle differed significantly among stages of GS chicken development, with the highest expression observed at 6 weeks. The expression levels in the pectoral muscles differed significantly among Ross 308 genotypes. In summary, we studied the relationships between a 31-bp indel in the LDB2 gene and economic traits in chickens. The indel was significantly correlated with multiple growth and carcass traits in the F2 resource population and affected the expression of the LDB2 gene in muscle tissue. In short, our study revealed that the LDB2 gene 31-bp indel can be used as a potential genetic marker for molecular breeding.

Analysis of four complete linkage sequence variants within a novel lncRNA located in a growth QTL on chromosome 1 related to growth traits in chickens.

An increasing number of studies have shown that quantitative trait loci (QTLs) at the end of chromosome 1 identified in different chicken breeds and populations exert significant effects on growth traits in chickens. Nevertheless, the causal genes underlying the QTL effect remain poorly understood. Using an updated gene database, a novel lncRNA (named LncFAM) was found at the end of chromosome 1 and located in a growth and digestion QTL. This study showed that the expression level of LncFAM in pancreas tissues with a high weight was significantly higher than that in pancreas tissues with a low weight, which indicates that the expression level of LncFAM was positively correlated with various growth phenotype indexes, such as growth speed and body weight. A polymorphism screening identified four polymorphisms with strong linkage disequilibrium in LncFAM: a 5-bp indel in the second exon, an A/G base mutation, and 7-bp and 97-bp indels in the second intron. A study of a 97-bp insertion in the second intron using an F2 chicken resource population produced by Anka and Gushi chickens showed that the mutant individuals with genotype II had the highest values for body weight (BW) at 0 days and 2, 4, 6, 8, 10 and 12 weeks, shank girth (SG) at 4, 8 and 12 weeks, chest width (CW) at 4, 8 and 12 weeks, body slant length (BSL) at 8 and 12 weeks, and pelvic width (PW) at 4, 8 and 12 weeks, followed by ID and DD genotypes. The amplification and typing of 2,716 chickens from ten different breeds, namely, the F2 chicken resource population, dual-type chickens, including Xichuan black-bone chickens, Lushi green-shell layers, Dongxiang green-shell layers, Changshun green-shell layers, and Gushi chickens, and commercial broilers, including Ross 308, AA, Cobb and Hubbard broilers, revealed that II was the dominant genotype. Interestingly, only genotype II existed among the tested populations of commercial broilers. Moreover, the expression level in the pancreas tissue of Ross 308 chickens was significantly higher than that in the pancreas tissue of Gushi chickens (P < 0.001), which might be related to the conversion rates among different chickens. The prediction and verification of the target gene of LncFAM showed that LncFAM might regulate the expression of its target gene FAM48A through cis-expression. Our results provide useful information on the mutation of LncFAM, which can be used as a potential molecular breeding marker.

Detection of CNV in the SH3RF2 gene and its effects on growth and carcass traits in chickens.

BACKGROUND: The SH3RF2 gene is a protein-coding gene located in a quantitative trait locus associated with body weight, and its deletion has been shown to be positively associated with body weight in chickens. RESULTS: In the present study, CNV in the SH3RF2 gene was detected in 4079 individuals from 17 populations, including the "Gushi ×Anka" F2 resource population and populations of Chinese native chickens, commercial layers, and commercial broilers. The F2 resource population was then used to investigate the genetic effects of the chicken SH3RF2 gene. The results showed that the local chickens and commercial layers were all homozygous for the wild-type allele. Deletion mutation individuals were detected in all of the commercial broiler breeds except Hubbard broiler. A total of, 798 individuals in the F2 resource group were used to analyze the effects of genotype (DD/ID/II) on chicken production traits. The results showed that CNV was associated with 2-, 6-, 10-, and 12-week body weight (P = 0.026, 0.042, 0.021 and 0.039 respectively) and significantly associated with 8-week breast bone length (P = 0.045). The mutation was significantly associated with 8-week body weight (P = 0.007) and 4-week breast bone length (P = 0.010). CNV was significantly associated with evisceration weight, leg muscle weight, carcass weight, breast muscle weight and gizzard weight (P = 0.032, 0.033, 0.045, 0.004 and 0.000, respectively). CONCLUSIONS: CNV of the SH3RF2 gene contributed to variation in the growth and weight gain of chickens.

Molecular characterization and an 80-bp indel polymorphism within the prolactin receptor (PRLR) gene and its associations with chicken growth and carcass traits.

The prolactin receptor (PRLR), a type I cytokine receptor, must bind prolactin (PRL) to act on target cells to mediate various physiological functions, including reproduction and lactation. This study identified an 80-bp insertion/deletion (indel) polymorphism in the 3'-untranslated region (3'-UTR) of the chicken PRLR gene in 3736 individuals from 15 breeds and analyzed its associations with growth and carcass traits in an F2 resource population. The results of the association analysis indicated that the 80-bp indel polymorphism was significantly (P < 0.05) or very significantly (P < 0.01) associated with multiple growth and carcass traits, such as body weight, leg weight, and shank length. In addition, we found that during the breeding process of commercial laying hens and commercial broilers, the 80-bp indel locus was artificially selected for the II genotype. Together, our findings reveal that this 80-bp indel polymorphism has potential as a new molecular marker for marker-assisted selection of chicken growth and carcass traits.