Xiangtao Kang

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.

A novel single-nucleotide polymorphism of the visfatin gene and its associations with performance traits in the chicken

Visfatin is a peptide that is predominantly expressed in visceral adipose tissue and is hypothesized to be related to obesity and insulin resistance. In this study, a novel silent single-nucleotide polymorphism (SNP) was found in exon 7 of the chickenvisfatin gene (also known asPBEF1) by single-stranded conformation polymorphism (SSCP) and DNA sequencing. In total, 836 chickens forming an F2 resource population of Gushi chicken crossed with Anka broiler were genotyped by XbaI forced RFLP, and the associations of this polymorphism with chicken growth, carcass characteristics, and meat quality were analyzed. Significant associations were found between the polymorphism and 4-week body weight (BW4), 6-week body weight (BW6), 4-week body slanting length (BSL4), fat bandwidth (FBW), breast muscle water loss rate (BWLR) and breast muscle fiber density (BFD) (P < 0.05), as well as 4-week breastbone length (BBL4) (P < 0.01). These observations suggested that the polymorphism in exon7 of thevisfatin gene had significant effects on the early growth traits of chicken.

Transcriptome profile of liver at different physiological stages reveals potential mode for lipid metabolism in laying hens

BackgroundLiver is an important metabolic organ that plays a critical role in lipid synthesis, degradation, and transport; however, the molecular regulatory mechanisms of lipid metabolism remain unclear in chicken. In this study, RNA-Seq technology was used to investigate differences in expression profiles of hepatic lipid metabolism-related genes and associated pathways between juvenile and laying hens. The study aimed to broaden the understanding of liver lipid metabolism in chicken, and thereby to help improve laying performance in the poultry industry.ResultsRNA-Seq analysis was carried out on total RNA harvested from the liver of juvenile (n = 3) and laying (n = 3) hens. Compared with juvenile hens, 2567 differentially expressed genes (1082 up-regulated and 1485 down-regulated) with P ≤ 0.05 were obtained in laying hens, and 960 of these genes were significantly differentially expressed (SDE) at a false discovery rate (FDR) of ≤0.05 and fold-change ≥2 or ≤0.5. In addition, most of the 198 SDE novel genes (91 up-regulated and 107 down-regulated) were discovered highly expressed, and 332 SDE isoforms were identified. Gene ontology (GO) enrichment and KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis showed that the SDE genes were most enrichment in steroid biosynthesis, PPAR signaling pathway, biosynthesis of unsaturated fatty acids, glycerophospholipid metabolism, three amino acid pathways, and pyruvate metabolism (P ≤ 0.05). The top significantly enriched GO terms among the SDE genes included lipid biosynthesis, cholesterol and sterol metabolic, and oxidation reduction, indicating that principal lipogenesis occurred in the liver of laying hens.ConclusionsThis study suggests that the majority of changes at the transcriptome level in laying hen liver were closely related to fat metabolism. Some of the SDE uncharacterized novel genes and alternative splicing isoforms that were detected might also take part in lipid metabolism, although this needs further investigation. This study provides valuable information about the expression profiles of mRNAs from chicken liver, and in-depth functional investigations of these mRNAs could provide new insights into the molecular networks of lipid metabolism in chicken liver.

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.

Discovery and functional characterization of leptin and its receptors in Japanese quail (Coturnix japonica)

Leptin is an important endocrine regulation factor of food intake and energy homeostasis in mammals; however, the existence of a poultry leptin gene (LEP) is still debated. Here, for the first time, we report the cloning of a partial exon 3 sequence of LEP (qLEP) and four different leptin receptor splicing variants, including a long receptor (qLEPRl) and three soluble receptors (qLEPR-a, qLEPR-b and qLEPR-c) in Japanese quail (Coturnix japonica). The qLEP gene had high GC content (64%), which is similar to other reported avian leptin genes. The encoded qLEP protein possessed the conserved pair of cysteine residues that are required to form a lasso knot for full biological activity, but shared relatively low identities with LEPs of other vertebrates. The translated qLEPRl protein contained 1143 amino acids and shared high amino acid sequence identity with a chicken homolog (89% identity). qLEPRl also contained all the motifs, domains, and basic tyrosine residues that are conserved in the LEPRl proteins of other vertebrates. qRT-PCR analysis showed that LEP and the four LEPR variants were expressed extensively in all tissues examined; the expression levels of LEP were relatively high in hypothalamus, skeletal muscle, and pancreas, while the expression levels of the LEPRs were highest in the pituitary. Compared with the expression levels of juvenile qLEP and total qLEPR (including all LEPR variants), the expression levels of mature qLEP and total qLEPR were up-regulated in the hypothalamus and pituitary, and down-regulated in the ovary. The expressions of LEP/LEPR increased when fasting and decreased when refeeding in the brain and peripheral tissues of juvenile quail, which suggested that the LEP/LEPR system modulated food intake and energy expenditure, although, unlike in mammals, LEP may actually act to inhibit food intake during fasting, at least in juvenile quail. The results indicate that qLEP and qLEPR have unique expression patterns and that the encoded proteins play important roles in the regulation of reproduction and energy status in Japanese quail.

Identification of the transcript isoforms and expression characteristics for chicken Lpin1.

Lpin1 was a gene with important effects on controlling lipid/energy metabolism in humans and mice. However, little was known about chicken Lpin1 gene. In the present study, two transcript isoforms of chicken Lpin1 were identified. Lpin1-α was predicted encoding one 902 amino acid protein, whereas Lpin1-δ was predicted encoding one 918 amino acid protein with an insertion of 48-bp fragment from intron 12 of chicken Lpin1-α, and a conservative element was found to be located in intron 12 of chicken Lpin1-α genomic sequence. Ten variants were identified from chicken Lpin1-α coding sequence, and two missense mutations were predicted to affect the protein function of Lpin1. Reverse transcription PCR (RT-PCR) analysis revealed that chicken total Lpin1, Lpin1-α and Lpin1-δ were expressed in all analyzed tissues, and presented clear tissue expression differences. Real-time quantitative RT-PCR revealed that 30% energy restriction significantly elevated the total Lpin1 mRNA expression level in hepatic (P < 0.01) and adipose (P < 0.01) tissues of birds. Chicken total Lpin1 gene mRNA expression level presented a significantly inverse correlation with some traits including abdominal fat rate (P < 0.01), serum high-density lipoprotein (P < 0.05) and total cholesterol (P < 0.05), which would make a foundation for the further study on chicken Lpin1 gene function.