Comprehensive analysis of miRNAs, lncRNAs, and mRNAs reveals potential players of sexually dimorphic and left-right asymmetry in chicken gonad during gonadal differentiation.

Despite thousands of sex-biased genes being found in chickens, the genetic control of sexually dimorphic and left-right asymmetry during gonadal differentiation is not yet completely understood. This study aimed to identify microRNAs (miRNAs), long noncoding RNAs (lncRNAs), messenger RNAs (mRNAs), and signaling pathways during gonadal differentiation in chick embryos (day 6/stage 29). The left and right gonads were collected for RNA sequencing. Sex-biased, side-biased miRNAs, lncRNAs, mRNAs, and shared differentially expressed miRNAs (DEmiRNA)-differentially expressed mRNAs (DEmRNA)-differentially expressed lncRNAs (DElncRNA) interaction networks were performed. A total of 8 DEmiRNAs, 183 DElncRNAs, and 123 DEmRNAs were identified for the sex-biased genes, and 7 DEmiRNAs, 189 DElncRNAs, and 183 DEmRNAs for the side-biased genes. The results of quantitative real-time PCR were generally consistent with the RNA-sequencing results. The study suggested that miRNAs and lncRNAs regulation were novel gene-specific dosage compensation mechanism and they could contribute to left-right asymmetry of chicken, but sex-biased and side-biased miRNAs, lncRNAs, and mRNAs were independent of each other. The competing endogenous RNA (ceRNA) networks showed that 17 target pairs including miR-7b (CYP19A1, FSHR, GREB1, STK31, CORIN, and TDRD9), miR-211 (FSHR, GREB1, STK31, CORIN, and TDRD9), miR-204 (FSHR, GREB1, CORIN, and TDRD9), and miR-302b-5p (CYP19A1 and TDRD9) may play crucial roles in ovarian development. These analyses provide new clues to uncover molecular mechanisms and signaling networks of ovarian development.

Association of host genetics with intestinal microbial relevant to body weight in a chicken F2 resource population.

Host-microbiota interactions describe a co-evolution and mutualistic symbiosis. Gut microbial communities are important for diverse host functions. However, in birds, the relationship between the composition of the intestinal microbiota and the genetic variation of the host is not clearly understood. To dissect these interactions, a Chinese yellow broiler line (genetically selected for a high growth rate) and Huiyang Beard chickens (low growth rate) were crossed, generating an F2 population. The population structures of the gut microbes in the phenotypically high and low 91-d body weight individuals of both sexes in the F2 population were studied. Interestingly, a non-metric multidimensional scaling analysis revealed that the microbiota of the high-weight and low-weight females was clearly separated into 2 clusters. A ß-diversity analysis showed that the locus rs16775833 within the doublesex and mab-3-related transcription factor (DMRT) gene cluster accounted for approximately 21% of the variation in the population structure of the gut microbiota. Furthermore, the 2 genetic loci rs15142709 and rs15142674 were significantly associated with specific species of Methanobacterium. These loci are located in the pleiomorphic adenoma gene 1 (PLAG1) and lck/yes-related novel tyrosine kinase (LYN) genes, which are involved in cell differentiation and growth. This finding suggests evidence for the influence of the host genetics on the composition of the gut microbiota in birds and the importance and utility of the host-microbe status to better understand its effect on the potential growth of birds.

Effects of sodium butyrate on intestinal health and gut microbiota composition during intestinal inflammation progression in broilers.

Butyric acid is a beneficial feed additive used in animal production, including poultry production. However, there are few reports on butyric acid as a prophylactic treatment against intestinal inflammation in broilers. The current study explored the effect of sodium butyrate (SB) as a prophylactic treatment on the intestinal health and gut microbiota of broilers with intestinal inflammation induced by dextran sulfate sodium (DSS) by monitoring changes in intestinal histopathology, gut leakiness indicators, inflammatory cytokines, and gut microbiota composition. Sodium butyrate supplementation prior to DSS administration significantly reduced the lesion scores of intestinal bleeding (P < 0.05) and increased villus height and the total mucosa of the ileum (P < 0.05). Regardless of intestinal inflammation, supplementation with SB at 300 mg/kg significantly decreased the levels of D (-)-lactate (P < 0.05), interleukin-6, and interleukin-1ß (P < 0.05) but increased the level of interleukin-10 (P < 0.05). The SB treatment did not affect the alpha diversity of intestinal microbiota during intestinal inflammation progression but altered their composition, and the microbial community structure of treated broilers was similar to that of control broilers. Taken together, our results reveal the importance of SB in improving intestinal development, inducing an anti-inflammatory effect during intestinal inflammation progression, and modulating the microbial community in broilers. Sodium butyrate seems to be optimized for anti-inflammatory effects at higher doses (300 mg/kg SB).

Dextran sulphate sodium (DSS) causes intestinal histopathology and inflammatory changes consistent with increased gut leakiness in chickens.

1. The clinical severity, histological changes, indicators of gut leakiness and inflammatory cytokine profiles were studied in chickens with dextran sulphate sodium (DSS)-induced intestinal inflammation. 2. The experimental groups (1.25%, 1.5% and 2.5% DSS) showed clinical signs, such as loose stools and weight loss, which increased with additional treatment days and, as expected, the effects of DSS-induced intestinal inflammation were time and dose-dependent. 3. After 10 d, histological manifestations were evident, including goblet cell depletion, mucus layer loss, significantly shorter villi and a thinner total ileal mucosa. 4. The d(-)-lactate value, which was used as a gut leakiness indicator, was significantly increased in the 2.5% DSS group. 5. Expression of the inflammatory cytokines interleukin-1Beta, tumour necrosis factor alpha and interleukin-10 in the serum significantly increased with DSS treatment. 6. This study indicates that the experimental intestinal inflammation induced by DSS is an ideal model to study the pathogenic mechanisms of intestinal inflammation in chickens and to test the efficacy of therapies.

Single nucleotide polymorphism variants within tva and tvb receptor genes in Chinese chickens.

Avian leukosis is an immunosuppressive neoplastic disease caused by avian leukosis viruses (ALV), which causes tremendous economic losses in the worldwide poultry industry. The susceptibility or resistance of chicken cells to subgroup A ALV and subgroup B, D, and E ALV are determined by the receptor genes tumor virus locus A (tva) and tumor virus locus B (tvb), respectively. Four genetic resistant loci (tva(r1), tva(r2), tva(r3), and tva(r4)) in tva receptor gene and a genetic resistant locus tvb(r) in the tvb receptor gene have been identified in inbred lines of White Leghorn. To evaluate the genetic resistance to subgroup A, B, D, and E ALV, genetic variations within resistant loci in tva and tvb genes were screened in Chinese local chicken breeds and commercial broiler lines. Here, the heterozygote tva(s1/r1) and the resistant genotype tva(r2/r2), tva(r3/r3), and tva(r4/r4) were detected in Chinese chickens by direct sequencing. The heterozygote tva(s1/r1) was detected in Huiyang Bearded chicken (HYBC), Rizhaoma chicken, and commercial broiler line 13 to 15 (CB13 to CB15), with the frequencies at 0.08, 0.18, 0.17, 0.25, and 0.15, respectively. The resistant genotype tva(r2/r2) was detected in Jiningbairi chicken (JNBRC), HYBC, and CB15, with the frequencies at 0.03, 0.08, and 0.06, respectively, whereas tva(r3/r3) and tva(r4/r4) were detected in 19 and 17 of the 25 Chinese chickens tested, with the average frequencies at 0.13 and 0.20, respectively. Furthermore, the resistant genotype tvb(r/r) was detected in JNBRC, CB07, CB12, CB14, and CB15 by pyrosequencing assay, with the frequencies at 0.03, 0.03, 0.11, 0.09, and 0.15, respectively. These results demonstrated that the potential for genetic improvement of resistance to subgroup A, B, D, and E ALV were great both in Chinese local chickens and commercial broilers. This study provides valuable insight into the selective breeding for chickens genetically resistant to ALV.

An association between genetic variation in the roundabout, axon guidance receptor, homolog 2 gene and immunity traits in chickens.

The roundabout, axon guidance receptor, homolog 2 (ROBO2) gene is one member of the roundabout (ROBO) family, which belongs to the immunoglobulin superfamily. The ROBO molecules are known to function in axon guidance and cell migration and are involved in SLIT/ROBO signaling. In this study, we obtained the full-length cDNA sequence of the chicken ROBO2 gene. Sequence analysis indicated that 3 SNP (1418G > A, 1421C > A and 2462T > C) exist in exons 5 and 12 of the ROBO2 gene. Genotyping results revealed that the allele frequency of SNP 1421C > A was similar in all tested breeds, but the allele frequencies of the other 2 SNP were different between White Leghorn and Chinese indigenous chickens. Allele G of 1418G > A and allele T of 2462T > C predominated in the Chinese indigenous breed, whereas alleles A and C predominated in the White Leghorn breed. Association analyses revealed that birds with the GG genotype of SNP 1418G > A or the TT genotype of SNP 2462T > C had significantly higher antibody responses to Newcastle disease virus (NDV_S/P; P < 0.01) than carriers of the A allele (GA and AA) or the C allele (TC), respectively. Real-time PCR further revealed that ROBO2 expression in the spleens of the birds with higher antibody responses (GG and TT genotypes at SNP 1418 and 2462, respectively) was significantly higher than in the spleens of birds with the AA and AG genotypes at SNP 1418 or the TC genotype at SNP 2462 (P < 0.01). The results demonstrated that genetic variation at the ROBO2 gene plays a key role in the immune response to Newcastle disease virus, and SNP 1418G > A and 2462T > C can be used as genetic markers for the selection of chickens with stronger immune responses to Newcastle disease virus.