Guirong Sun

Novel 9-bp indel in visfatin gene and its associations with chicken growth

1. The effects of polymorphisms of the visfatin gene on growth performance, carcase traits, meat quality and serum variables were investigated in an F2 resource population of Gushi chickens crossed with Anka broilers. 2. A 9-bp (‘TAACCTGTG’) insertion/deletion in intron10 of the visfatin gene was found and a total of 964 individuals were genotyped in the resource population. Genotypes (II, ID and DD) were identified based on the 9-bp insertion (allele I) or deletion (allele D). The insertion/deletion polymorphism was used for analysing associations of the gene with growth traits, carcase traits and meat quality traits in 414 F2 chickens. 3. The DD genotype was not detected in those 66 F1 chickens and the I allelic frequency (0·724–0·879) was obviously higher than the D allelic frequency (0·121–0·276) in the birds of three generations. 4. The 9-bp insertion/deletion was associated with the traits of 8-week shank length, 12-week shank length, 4-week pectoral angle and pancreas weight. The relationships with other traits: body weight, carcase traits, meat quality traits and serum variables, were not significant. 5. It was concluded that allele D (9-bp deletion) of the visfatin gene had a negative effect on skeletal growth.

Novel SNPs in the PRDM16 gene and their associations with performance traits in chickens

The PR domain containing 16 (PRDM16) is a member of the Prdm family, and is known to regulate cell differentiation. In the present study, DNA pool sequencing methods were employed to screen genetic variations in the chicken PRDM16 gene. The results revealed four novel single nucleotide polymorphisms (SNPs): NC_006108.2: g.92188G>A, XM_417551: c.1161C>T (Ala/Ala, 387aa), c.1233C>T (Ser/Ser, 411aa) and c.1433G>A (Ser/Asn, 478aa). The BglI polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) was used to detect c.1161C>T, while HhaI Forced PCR-RFLP methods were used to detect 1233C>T and c.1433G>A in 964 chickens. The chickens comprised 38 grandparents, 66 F1 parents and 860 F2 birds derived from an F2 resource population of Gushi chickens crossed with Anka broilers. The associations of the polymorphisms in the chicken PRDM16 gene with performance traits were analyzed in the 860 F2 chickens. The results indicated that the three SNPs were significantly associated with growth, fatness and meat quality traits in the chickens. In particular, the polymorphisms of the missense SNP (c.1433G>A) had positive effects on chicken body weight and body size at different stages. It affected also fatness traits significantly. Comparison of the different genotypes of c.1433G>A showed that the GG genotype favored chicken growth and fatness traits.

Association study of polymorphisms inside the miR-1657 seed region with chicken growth and meat traits.

1. Polymorphisms occurring in the seed region of microRNAs (miRNAs) could influence their target gene and lead to phenotypic variation. The purpose of the research was to explore the genetic effects of the rs14934924 (G > A) mutation resident in the conserved seed region of miR-1657 on growth and meat traits of the Gushi-Anka F2 resource population. 2. The NdeI polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and association analysis were used to analyse the polymorphism. 3. The mutation was associated with body weight at 8 weeks of age, shank girth at 12 weeks of age, breast bone length at 12 weeks of age, pelvis breadth at 4 weeks of age and subcutaneous fat thickness (P < 0·05) and was associated with body weight at 4, 6, 10 and 12 weeks of age (P < 0·01). 4. Our results will be a useful resource for a subsequent study in miRNA function, and provide a basis for molecular techniques in chicken breeding.

Effect of γ-aminobutyric acid on growth performance and immune function in chicks under beak trimming stress

This experiment was undertaken to examine the effect of beak trimming stress on the growth performance and immune system, and to consider possible roles of γ-aminobutyric acid (GABA) in this stress response. Results showed that body weight, feed intake and relative spleen weight were significantly increased by GABA at 80 mg/kg (P < 0.05) under beak trimming stress, whereas the relative organ weights of the bursa of fabricius and thymus were not significantly affected (P > 0.05). Adrenocorticotropic hormone concentration in serum was highest for chicks fed the GABA-deficient water and was significantly decreased by the supplement of GABA at days 1, 3 and 5 after beak trimming (P < 0.05). The supplement of GABA significantly increased the proportions of CD4(+) and CD8(+) lymphocytes, especially at the dose of 60 mg/kg (P < 0.05). The levels of interleukin (IL)-1β, lipopolysaccharide-induced tumor necrosis factor-α and IL-6 in serum were significantly decreased by GABA at 80 mg/kg (P < 0.05). All the three cytokines expressed in the spleen were significantly decreased by GABA at 80 mg/kg when birds were under beak trimming stress (P < 0.05). It is concluded that beak trimming suppressed the immune response of chicks, whereas the immune response of chicks could be improved by GABA supplementation.

Modulation of growth and immunity by dietary supplementation with resveratrol in young chickens receiving conventional vaccinations

OBJECTIVE To determine the effects of resveratrol (RES) on growth and immune status in chickens receiving conventional vaccinations. ANIMALS Two hundred forty 1-day-old layer chickens. PROCEDURES Chickens received conventional vaccinations throughout the study and were randomly assigned to 1 of 4 treatments in 6 replicate pens/treatment. Treatments included 1 control group (basal diet) and 3 experimental groups fed the basal diet plus 200, 400, and 800 mg of RES/kg of diet. At 40 days of age, 1 bird/pen was randomly selected to have blood and tissues collected to determine serum immunity indices; mRNA relative expression of proinflammatory cytokines in splenocytes; mRNA relative expression of nuclear transcription factor-κB, growth hormone receptor, and insulin-like growth factor-1 in hepatocytes; cell proliferation; and apoptosis. RESULTS Average daily gain, antibody titers against Newcastle disease virus and avian influenza viruses H5 and H9, and insulin-like growth factor-1 expression were quadratically increased with increasing RES concentration. In hepatocytes, growth hormone receptor gene mRNA relative expression was quadratically increased and nuclear transcription factor-κB gene mRNA relative expression was linearly decreased with increasing RES concentration. In splenocytes, nterleukin-1β and tumor necrosis factor-α mRNA relative expression was linearly decreased with increasing RES concentration. Resveratrol supplementation delayed cell proliferation and reduced apoptosis in immunocytes. With increasing RES concentration, proliferation index and relative weight of the thymus, ratio of CD4+ to CD8+ cells, and CD4+ cell count were quadratically increased, and IgM concentration was linearly increased. CONCLUSIONS AND CLINICAL RELEVANCE Dietary resveratrol supplementation improved growth, protected immunocytes against antigen-induced apoptosis, and upregulated immune response in chickens that received conventional vaccinations.

MicroRNAs-1614-3p gene seed region polymorphisms and association analysis with chicken production traits

In the present study, a total of 860 chickens from a Gushi–Anka F2 resource population were used to evaluate the genetic effect of the gga-miR-1614-3p gene. A novel, silent, single nucleotide polymorphism (SNP, +5 C>T) was detected in the gga-miR-1614-3p gene seed region through AvaII polymerase chain reaction–restriction fragment length polymorphism (PCR-RFLP) and PCR products sequencing methods. Associations between the SNP and chicken growth, meat quality and carcass traits were performed by association analysis. The results showed that the SNP was significantly associated with breast muscle shear force and leg muscle water loss rate, wing weight, liver weight and heart weight (p < 0.05), and highly significantly associated with the weight of the abdominal fat (p < 0.01). The secondary structure of gga-miR-1614 and the free energy were altered due to the variation predicted by the M-fold program.

A novel 31-bp indel in the paired box 7 (PAX7) gene is associated with chicken performance traits

Abstract 1. A novel 31-bp indel polymorphism in intron 3 of the chicken paired box 7 (PAX7) gene was identified and genotyped in an F2 resource population of Gushi chicken crossed with Anka broiler to analyse its associations with chicken growth, carcass and meat quality traits. 2. Results showed that the 31-bp indel was significantly associated with body weight at 4, 6, 8, 10, 12 weeks of age and body size indices including shank length, shank girth, body slanting length at 8 and 12 weeks of age. Significant associations were found for carcass weight, semi-evisceration weight, evisceration weight, breast muscle fibre diameter, leg muscle fibre diameter, breast muscle fibre density, while no significant association with leg muscle fibre density was observed. 3. It was concluded that the 31-bp indel in intron 3 of the PAX7 gene was associated with chicken growth, carcass and meat quality traits where the 31-bp deletion had a negative effect on chicken growth and carcass traits and positive effect on meat quality traits.

Systematic analysis of the regulatory functions of microRNAs in chicken hepatic lipid metabolism.

Laying performance is an important economic trait in hens, and this physiological process is largely influenced by the liver function. The livers of hens at 20- and 30-week-old stages were investigated using the next generation sequencing to identify the differences of microRNA expression profiles. Compared with the 20-week-old hens, 67 down- and 13 up-regulated microRNAs were verified to be significant differentially expressed (false discovery rate, FDR ≤ 0.05) (SDE) in the 30-week-old. We also identified 13 down- and 6 up-regulated novel differentially expressed (DE) microRNAs. miR-22-3p and miR-146b-5p, which exhibit critical roles in mammalian lipid metabolism, showed the most abundant expression and the highest fold-change, respectively. A total of 648 potential target genes of the SDE microRNAs were identified through an integrated analysis of microRNAs and the DE genes obtained in previous RNA-sequencing, including FADS1, FADS2, ELOVL6 and ACSL5, which are critical lipid metabolism-related regulators. Bioinformatic analyses revealed that target genes were mainly enriched in lipid-related metabolism processes. This work provides the first study of the expression patterns of hepatic microRNAs between 20- and 30-week old hens. The findings may serve as a fundamental resource for understanding the detailed functions of microRNAs in the molecular regulatory systems of lipid metabolism.

Genome-wide DNA methylation profiles reveal novel candidate genes associated with meat quality at different age stages in hens

Poultry meat quality is associated with breed, age, tissue and other factors. Many previous studies have focused on distinct breeds; however, little is known regarding the epigenetic regulatory mechanisms in different age stages, such as DNA methylation. Here, we compared the global DNA methylation profiles between juvenile (20 weeks old) and later laying-period (55 weeks old) hens and identified candidate genes related to the development and meat quality of breast muscle using whole-genome bisulfite sequencing. The results showed that the later laying-period hens, which had a higher intramuscular fat (IMF) deposition capacity and water holding capacity (WHC) and less tenderness, exhibited higher global DNA methylation levels than the juvenile hens. A total of 2,714 differentially methylated regions were identified in the present study, which corresponded to 378 differentially methylated genes, mainly affecting muscle development, lipid metabolism, and the ageing process. Hypermethylation of the promoters of the genes ABCA1, COL6A1 and GSTT1L and the resulting transcriptional down-regulation in the later laying-period hens may be the reason for the significant difference in the meat quality between the juvenile and later laying-period hens. These findings contribute to a better understanding of epigenetic regulation in the skeletal muscle development and meat quality of chicken.

Effect of polymorphism within miRNA-1606 gene on growth and carcass traits in chicken.

Genetic variations in microRNAs (miRNAs) including primary miRNAs, precursor miRNAs and mature miRNAs can lead to phenotypic variation by altering the biogenesis of miRNAs and/or their binding to target mRNAs. Increasing functional studies suggest that polymorphisms occurring in miRNAs can lead to phenotypic variation in farm animal. Here, we identified a single nucleotide polymorphism (SNP) located in the precursor of chicken miRNA-1606 gene. The association study on body indexes, body weight at different growth stages, and carcass traits was performed in a Gushi-Anka F2 population resource. The SNP was not only significantly associated with body weight at 10 and 12 weeks, respectively, but also with chicken shank length, chest depth and body slanting length at 8 weeks; shank length, pectoral angle, body slanting length and pelvis breadth at 12 weeks, respectively. And the polymorphism was also significantly associated with carcass traits including semi-evisceration weight, evisceration weight, breast muscle weight, leg weight and carcass weight as well. The observed values of individuals with CA genotype were significantly higher than CC genotype both in body weight at different stages and carcass traits. This SNP altered the predicted second structure of pre-mir-1606, with the altering of the free energy values. And the relative expression level of mature miRNA between CA and AA was significantly changed in leg muscle. Our data suggested that miRNA-1606 may be a candidate gene associated with chicken growth traits.