Silkie Research Articles

Characterization of the Coding Sequence of the MC1R (Melanocortin 1 Receptor) Gene of Ayam Cemani Black Chickens.

Plumage color is one of the most important traits characterizing chicken breeds. Black-boned chickens constitute a specific group of breeds with a unique phenotype. One of the representatives is the Indonesian Ayam Cemani. The extraordinary black phenotype results from a specific chromosomal rearrangement. We used complete CDS of crucial color-related gene MC1R, which plays a key role in melanin distribution but has not been previously studied in Ayam Cemani. It turned out that Ayam Cemani individuals possess a newly found non-synonymous mutation G355A resulting in amino acid substitution D119N. Together with the presence of G274A (E92K), the new missense variant enabled us to distinguish a new extended black allele at the E locus. All of the investigated birds were heterozygous in terms of the new mutation. Previous studies and our own results indicate a high level of genetic variation within the MC1R gene within and between chicken breeds. Besides the key mutations that make it possible to distinguish particular major alleles, there are also numerous substitutions that give haplotypes more characteristics for individual breeds.

Effect of High Dietary Iron on Fat Deposition and Gut Microbiota in Chickens.

To meet the demand of consumers for chicken products, poultry breeders have made improvements to chickens. However, this has led to a new problem in the modern poultry industry, namely excessive fat deposition. This study aims to understand the effects of dietary iron supplementation on fat deposition and gut microbiota in chickens. In this study, we investigated the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens. A total of 75 7-week-old silky fowl black-bone chickens were randomly divided into three groups (five replicates per group, five chickens per replicate) and fed them for 28 days using a growing diet (control group), a growing diet + 10% tallow (high-fat diet group, HFD group), and a growing diet + 10% tallow + 500 mg/kg iron (HFDFe500 group), respectively. We detected the effects of iron on the growth performance, fat deposition, and gut microbiota of silky fowl black-bone chickens using the growth performance index test, oil red O staining, and HE staining, and found that the high-fat diet significantly increased liver and serum fat deposition and liver injury, while the addition of iron to the diet could reduce the fat deposition caused by the high-fat diet and alleviate liver injury. In addition, 16S rDNA sequencing was used to compare the relative abundance of gut microbiota in the cecal contents in different feeding groups. The results showed that the high-fat diet could induce gut microbiota imbalance in chickens, while the high-iron diet reversed the gut microbiota imbalance. PICRUSt functional prediction analysis showed that dietary iron supplementation affected amino acid metabolism, energy metabolism, cofactors, and vitamin metabolism pathways. In addition, correlation analysis showed that TG was significantly associated with Firmicutes and Actinobacteriota (p < 0.05). Overall, these results revealed high dietary iron (500 mg/kg) could reduce fat deposition and affect the gut microbiota of silky fowl black-bone chickens, suggesting that iron may regulate fat deposition by influencing the gut microbiota of chickens and provides a potential avenue that prevents excessive fat deposition in chickens by adding iron to the diet.

Genetic diversity, demographic history, and selective signatures of Silkie chicken

BackgroundSilkie is a traditional Chinese chicken breed characterized by its unique combination of specialized morphological traits. While previous studies have focused on the genetic basis of these traits, the overall genomic characteristics of the Silkie breed remain largely unexplored. In this study, we employed whole genome resequencing data to examine the genetic diversity, selective signals and demographic history of the Silkie breed through comparative analyses with seven other Chinese indigenous breeds (IDGBs), a commercial breed, and the wild ancestor Red Jungle Fowl.ResultsIn total, 20.8 million high-quality single nucleotide polymorphisms and 86 large structural variations were obtained. We discovered that Silkie exhibits a relatively high level of inbreeding and is genetically distinct from other IDGBs. Furthermore, our analysis indicated that Silkie has experienced a stronger historical population bottleneck and has a smaller effective population size compared with other IDGBs. We identified 45 putatively selected genes that are enriched in the melanogenesis pathway, which probably is related to the feather color. Among these genes, LMBR1 and PDSS2 have been previously associated with the extra toe and the hookless feathers, respectively. Six of the selected genes (KITLG, GSK3B, SOBP, CTBP1, ELMO2, SNRPN) are known to be associated with neurodevelopment and mental diseases in human, and are possibly related to the distinct behavior of Silkie. We further identified structural variants in Silkie and found previously reported variants linked to hyperpigmentation (END3), muff and beard (HOXB8), and Rose-comb phenotype (MNR2). Additionally, we found a 0.61 Mb inversion overlapping with the GMDS gene, which was previously linked to neurodevelopmental defects in zebrafish and humans. This may also be related to the behavior distinctiveness of Silkie.ConclusionsOur study revealed that Silkie is genetically distinct and relatively highly inbred compared to other IDGB chicken populations, possibly attributed to more prolong population bottlenecks and selective breeding practice. These results enhance our understanding of how domestication and selective breeding have shaped the genome of Silkie. These findings contribute to the broader field of domestication and avian genomics, and have implications for the future conservation and breeding efforts.

Use of GC-IMS and Stoichiometry to Characterize Flavor Volatiles in Different Parts of Lueyang Black Chicken during Slaughtering and Cutting.

Chilled and cut chicken is preferred by consumers for its safeness and readiness to cook. To evaluate the quality characteristics of various chilled chicken products, differences in volatile organic components (VOCs) of six different cut parts (breast, back, leg, heart, liver, and gizzard) of Lueyang black chicken were characterized through gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. A total of 54 peaks in the signal of VOCs were detected by GC-IMS, and 43 VOCs were identified by qualitative analysis. There were 22 aldehydes (20.66-54.07%), 8 ketones (25.74-62.87%), 9 alcohols (4.17-14.69%), 1 ether (0.18-2.22%), 2 esters (0.43-1.54%), and 1 furan (0.13-0.52%), in which aldehydes, ketones, and alcohols were the main categories. Among the six cut parts, the relative content of aldehydes (54.07%) was the highest in the gizzard, and the relative content of ketones (62.87%) was the highest in the heart. Meanwhile, the relative content of alcohols (14.69%) was the highest in the liver. Based on a stable and reliable predictive model established by orthogonal partial least squares-discriminant analysis (OPLS-DA), 3-hydroxy-2-butanone (monomer and dimer), acetone, 2-butanone monomer, hexanal (monomer and dimer), isopentyl alcohol monomer, and n-hexanol monomer were picked out as characteristic VOCs based on variable importance in projection (VIP value > 1.0, p < 0.05). Principal component analysis (PCA) and the clustering heatmap indicated that the characteristic VOCs could effectively distinguish the six cut parts of Lueyang black chicken. The specific VOCs responsible for flavor differences among six different cut parts of Lueyang black chicken were hexanal (monomer and dimer) for the gizzard, 2-butanone monomer and hexanal dimer for the breast, hexanal monomer for the back, 3-hydroxy-2-butanone monomer for the leg, 3-hydroxy-2-butanone (monomer and dimer) for the heart, and acetone and isopentyl alcohol monomer for the liver. These findings could reveal references for quality assessment and development of chilled products related to different cut parts of Lueyang black chicken in the future.

Analysis of VOCs in Lueyang Black Chicken Breast Meat during the Steaming Process with GC-IMS and Stoichiometry

Steamed chicken breast meat attracts people for its unique flavor and nutritional benefits. In this study, the sensory evaluation of Lueyang black chicken breast meat during steaming was first performed, and their volatile organic compounds (VOCs) were further analyzed by gas chromatography-ion mobility spectroscopy (GC-IMS) combined with stoichiometry. The sensory results demonstrated that the Lueyang black chicken breast meat steamed for 15–30 min was more acceptable in taste, flavor, and chewiness. A total of 60 volatile flavor signal peaks were obtained, and 46 VOCs were recognized from qualitative analysis, containing 24 aldehydes (51.19–72.57%), 8 ketones (10.15–16.97%), 9 alcohols (7.98-13.16%), 2 furans (2.24–10.85%), 2 esters (0.54–1.56%), and 1 ether (0.05–2.47%). A stable and reliable prediction model was set up by orthogonal partial least squares-discriminant analysis (OPLS-DA), and 18 characteristic VOCs (including 10 aldehydes, 3 alcohols, 3 ketones, 1 furan, and 1 ether) were picked out through variable importance in the projection (VIP&gt;1.0 and p&lt;0.05). Principal component analysis (PCA) results indicated that the cumulative contribution ratio was 92% with PC1 68.7% and PC2 23.3%, respectively, indicating that these characteristic VOCs could well discriminate the steaming time of Lueyang black chicken breast meat. Heatmap clustering analysis also demonstrated a similar distinguishing effect. These results could provide references for the research, development, and quality control of ready-to-eat steamed products for Lueyang black chicken breast meat in the future.

Structure and immunostimulating activity of polysaccharides derived from the roots and leaves of dandelion

Two polysaccharides were obtained from dandelion roots (DPR) and dandelion leaves (DPL) via water extraction and ethanol precipitation. Both DPR and DPL were an acid heteropolysaccharide, with a molecular weight of 5.89 × 104 and 28.2 × 104 Da, respectively. Monosaccharide composition results showed that both DPR and DPL contained Man, Glc, Rha, GalA, Glc, Gal, and Ara with a molar ratios of 2.98:1.00:3.67:6.41:2.98:16.70:2.48 and 1.23:1.00:1.06:5.74:2.88:8.59:1.84, respectively. Methylation and NMR analysis showed DPR and DPL, with triple-helix conformations, were mainly composed of 4-ɑ-Galp and 4-ɑ-GalAp, terminated with t-ɑ-Araf, t-ɑ-Rhap, t-ɑ-Glcp and t-ɑ-Manp. DPL showed an immunoprotective effect in cyclophosphamide (Cy)-induced black-bone silky chickens by improving chicken growth performance, increasing the spleen, thymus, and bursa of Fabricius indices, and promoting blood lymphocyte proliferation, the secretion of cytokines (IL-2, IL-6, and INF-γ) and serum immunoglobulin (IgA, IgG, and IgM) levels in a dose-dependent manner. Moreover, the oxidative stress damage in immunosuppressed chickens was significantly reformed after DPL treatment. These findings provide useful information on the potential for application of dandelion polysaccharides as natural nutrients to enhance chicken immune and antioxidant functions.Graphical

Genome-wide association studies of egg production traits by whole genome sequencing of Laiwu Black chicken

Compared to high-yield commercial laying hens, Chinese indigenous chicken breeds have poor egg laying capacity due to the lack of intensive selection. However, as these breeds have not undergone systematic selection, it is possible that there is a greater abundance of genetic variations related to egg laying traits. In this study, we assessed 5 egg number (EN) traits at different stages of the egg-laying period: EN1 (from the first egg to 23 wk), EN2 (from 23 to 35 wk), EN3 (from 35 to 48 wk), EN4 (from the first egg to 35 wk), and EN5 (from the first egg to 48 wk). To investigate the molecular mechanisms underlying egg number traits in a Chinese local chicken breed, we conducted a genome-wide association study (GWAS) using data from whole-genome sequencing (WGS) of 399 Laiwu Black chickens. We obtained a total of 3.01 Tb of raw data with an average depth of 7.07 × per individual. A total of 86 genome-wide suggestive or significant single-nucleotide polymorphisms (SNP) contained within a set of 45 corresponding candidate genes were identified and found to be associated with stages EN1-EN5. The genes vitellogenin 2 (VTG2), lipase maturation factor 1 (LMF1), calcium voltage-gated channel auxiliary subunit alpha2delta 3 (CACNA2D3), poly(A) binding protein cytoplasmic 1 (PABPC1), programmed cell death 11 (PDCD11) and family with sequence similarity 213 member A (FAM213A) can be considered as the candidate genes associated with egg number traits, due to their reported association with animal reproduction traits. Noteworthy, results suggests that VTG2 and PDCD11 are not only involved in the regulation of EN3, but also in the regulation of EN5, implies that VTG2 and PDCD11 have a significant influence on egg production traits. Our study offers valuable genomic insights into the molecular genetic mechanisms that govern egg number traits in a Chinese indigenous egg-laying chicken breed. These findings have the potential to enhance the egg-laying performance of chickens.

Identification of Characteristic Bioactive Compounds in Silkie Chickens, Their Effects on Meat Quality, and Their Gene Regulatory Network.

Silkie chicken, an important chicken breed with high medicinal and nutritional value, has a long history of being used as a dietary supplement in China. However, the compounds with health-promoting effects in Silkie chickens remain unclear. In the present study, we conducted a comprehensive analysis of metabolic and lipidomic profiles to identify the characteristic bioactive compounds in Silkie chickens, using a common chicken breed as control. The results showed that the levels of 13 metabolites including estradiol, four lipid subclasses including cardiolipin (CL), eight lipid molecules, and three fatty acids including docosahexaenoic acid (C22:6) were significantly increased in Silkie chickens, which have physiological activities such as resisting chronic diseases and improving cognition. These characteristic bioactive compounds have effects on meat quality characteristics, including improving its water-holding capacity and umami taste and increasing the content of aromatic compounds and phenols. The differentially expressed genes (DEGs) between the two chicken breeds revealed the regulatory network for these characteristic bioactive compounds. Fifteen DEGs, including HSD17B1, are involved in the synthesis of characteristic metabolites. Eleven DEGs, including ELOVL2, were involved in the synthesis and transport of characteristic lipids and fatty acids. In summary, we identified characteristic bioactive compounds in Silkie chickens, and analyzed their effects on meat quality characteristics. This study provided important insight into Silkie chicken meat as a functional food.

Integrated transcriptome and proteome analysis reveals the unique molecular features and nutritional components on the muscles in Chinese Taihe black-bone silky fowl chicken.

The Taihe Black-Bone silky fowl chicken (BB-sfc) is a renowned dietary and medicinal chicken globally recognized for its high nutritional and medicinal value. Compared to the local Black-Bone black-feathered chicken (BB-bfc), the Taihe silky fowl chicken has higher levels of amino acids, trace elements, and unsaturated fatty acids in their muscles, which offer anti-aging, anti-cancer, and immune enhancing benefits. Despite this, the unique nutritional components, genes, and proteins in Taihe silky fowl chicken muscles are largely unknown. Therefore, we performed a comprehensive transcriptome and proteome analysis of muscle development between BB-sfc and BB-bfc chickens using RNA-Seq and TMT-based quantitative proteomics methods. RNA-Seq analysis identified 286 up-regulated genes and 190 down-regulated genes in BB-sfc chickens, with oxidoreductase activity and electron transfer activity enriched in up-regulated genes, and phospholipid homeostasis and cholesterol transporter activity enriched in down-regulated genes. Proteome analysis revealed 186 significantly increased and 287 significantly decreased proteins in Taihe BB-sfc chicken muscles, primarily affecting mitochondrial function and oxidative phosphorylation, crucial for enhancing muscle antioxidant capacity. Integrated transcriptome and proteome analysis identified 6 overlapped up-regulated genes and 8 overlapped down-regulated genes in Taihe silky fowl chicken, related to improved muscle antioxidant status. Taken together, this research provides a comprehensive database of gene expression and protein information in Taihe Black-Bone silky fowl chicken muscles, aiding in fully exploring their unique economic value in the future.

Differential responses to avian pathogenic E. coli and the regulatory role of splenic miRNAs in APEC infection in Silkie chickens.

Avian pathogenic Escherichia coli (APEC) is a bacterial disease that harms the poultry industry worldwide, but its effect on Chinese Silkie has not been reported. Studies on whether there are differences in Silkie individual resistance to APEC and the regulatory role of spleen miRNAs lay the foundation for strategies against APEC. Therefore, 270 Silkie chickens were infected with the median lethal dose of an E. coli O1, O2, and O78 mixture. These chickens were divided into a susceptible group (Group S) and a recovery group (Group R) according to whether they survived 15 days postinfection (dpi). Moreover, 90 uninfected APEC Silkie served as controls (Group C). The splenic miRNA expression profile was examined to evaluate the role of miRNAs in the APEC infection response. Of the 270 Silkies infected with APEC, 144 were alive at 15 dpi. Cluster analysis and principal component analysis (PCA) of splenic miRNAs revealed that the four Group R replicates were clustered with the three Group C replicates and were far from the three Group S replicates. Differentially expressed (DE) miRNAs, especially gga-miR-146b-5p, play essential roles in immune and inflammatory responses to APEC. Functional enrichment analyses of DEmiRNAs suggested that suppression of immune system processes (biological processes) might contribute to susceptibility to APEC and that FoxO signaling pathways might be closely associated with the APEC infection response and postinfection repair. This study paves the way for screening anti-APEC Silkies and provides novel insights into the regulatory role of miRNAs in APEC infection.

Combined analysis of the microbiome, metabolome and transcriptome of silkie chickens in response to avian pathogenic E. coli (APEC)

Avian colibacillosis is a bacterial disease caused by avian pathogenic Escherichia coli (APEC) that results in great losses in the poultry industry every year. Individual Silkie chickens of the same breed that are given the same feed in the same feeding conditions have different levels of resistance or susceptibility to APEC. Differences in gut microbes, gut metabolites, and gene expression in the spleen of APEC-resistant and APEC-susceptible chickens were compared, and multiple omics associations were analyzed to explore the mechanism of resistance to APEC in Silkie chickens. Compared with those in the APEC-susceptible group, the APEC-resistant group showed significantly increased abundances of many gut microorganisms, including Bacillus, Thermoactinomyces, Arthrobacter, and Ureibacillus, which were positively correlated with norvaline, l-arginine, and valyl-glycine levels. Intestinal tryptophan, indole, and indole derivative-related differentially abundant metabolites played an active role in combatting APEC infection. In the spleen, “response to stimulus” was the most significantly enriched GO term, and “cytokine‒cytokine receptor interaction” was the most significantly enriched KEGG pathway. The arginine biosynthesis and PPAR signaling pathways were the KEGG pathways that were significantly enriched with differentially abundant metabolites and differentially expressed genes. This study provides new insight into the prevention and treatment of APEC infection in Silkie chickens and lays a foundation to study the mechanism of APEC infection in poultry.

A chromosome-level genome assembly for the Silkie chicken resolves complete sequences for key chicken metabolic, reproductive, and immunity genes

A set of high-quality pan-genomes would help identify important genes that are still hidden/incomplete in bird reference genomes. In an attempt to address these issues, we have assembled a de novo chromosome-level reference genome of the Silkie (Gallus gallus domesticus), which is an important avian model for unique traits, like fibromelanosis, with unclear genetic foundation. This Silkie genome includes the complete genomic sequences of well-known, but unresolved, evolutionarily, endocrinologically, and immunologically important genes, including leptin, ovocleidin-17, and tumor-necrosis factor-α. The gap-less and manually annotated MHC (major histocompatibility complex) region possesses 38 recently identified genes, with differentially regulated genes recovered in response to pathogen challenges. We also provide whole-genome methylation and genetic variation maps, and resolve a complex genetic region that may contribute to fibromelanosis in these animals. Finally, we experimentally show leptin binding to the identified leptin receptor in chicken, confirming an active leptin ligand-receptor system. The Silkie genome assembly not only provides a rich data resource for avian genome studies, but also lays a foundation for further functional validation of resolved genes.

Clonally derived chicken primordial germ cell lines maintain biological characteristics and proliferative potential in long-term culture

Chicken primordial germ cells (PGCs) are important cells with significant implications in preserving genetic resources, chicken breeding and production, and basic research on genetics and development. Currently, chicken PGCs can be cultured long-term in vitro to produce single-cell clones. However, systematic exploration of the cellular characteristics of these single-cell clonal lines has yet to be conducted. In this study, single-cell clonal lines were established from male and female PGCs of Rugao Yellow Chicken and Shouguang Black Chicken, respectively, using a micropipette-based method for single-cell isolation and culture. Analysis of glycogen granule staining, mRNA expression of pluripotency marker genes (POUV, SOX2, NANOG), germ cell marker genes (DAZL, CVH), and SSEA-1, EMA-1, SOX2, C-KIT, and CVH protein expression showed positive results, indicating that PGCs maintain normal cellular properties after single-cell cloning. Furthermore, tests on proliferation ability and gene expression levels in PGC single-cell clonal lines showed high expression of the pluripotency-related genes and TERT compared to control PGCs, and PGC single-cell clonal lines demonstrated higher proliferation ability. Finally, green fluorescent protein (GFP)-PGC single-cell clonal lines were established, and it was found that these single-cell clonal lines could still migrate into the gonads of recipients, suggesting their potential for germ-line transmission. This study systematically validated the normal cellular characteristics of PGC single-cell clonal lines, indicating that they could be applied in genetic modification research on chickens.

Molecular characterization of Blastocystis spp. in Hotan Black chickens in southern Xinjiang.

To determine the infection status and assess the zoonotic potential of Blastocystis spp. in Hotan Black chickens in southern Xinjiang, China, fecal samples were collected from 617 chickens on 18 large-scale farms. The presence of Blastocystis spp. was determined using polymerase chain reaction based on the small subunit rRNA (SSU rRNA) locus. The results revealed an overall infection rate of 26.3% (162/617). Samples from Farm 1 in Luopu County showed the highest infection rate (76.3%, 29/38). The highest and lowest infection rates were detected in the <30-day (34.4%, 43/125) and > 90-day age groups (12.4%, 11/89), respectively. The infection rate decreased with increasing age. Statistical analysis showed significant differences in the infection rates of Blastocystis spp. among the different sampling sites (p < 0.05) and age groups (p < 0.05). Four Blastocystis spp. subtypes (ST6, ST7, ST10, and ST23) were identified. The infection rates of the zoonotic subtypes, ST6 and ST7, were 3.2% (20/617) and 22.2% (137/617), respectively. The presence of Blastocystis spp. and zoonotic subtypes provided evidence for the potential transmission of this pathogen between Hotan Black chickens and humans, especially in animal handlers in this area.

Elucidation of the genetic determination of clutch traits in Chinese local chickens of the Laiwu Black breed

BackgroundEgg laying rate (LR) is associated with a clutch, which is defined as consecutive days of oviposition. The clutch trait can be used as a selection indicator to improve egg production in poultry breeding. However, little is known about the genetic basis of clutch traits. In this study, our aim was to estimate genetic parameters and identify quantitative trait single nucleotide polymorphisms for clutch traits in 399 purebred Laiwu Black chickens (a native Chinese breed) using a genome-wide association study (GWAS).MethodsIn this work, after estimating the genetic parameters of age at first egg, body weight at first egg, LR, longest clutch until 52 week of age, first week when the longest clutch starts, last week when the longest clutch ends, number of clutches, and longest number of days without egg-laying until 52 week of age, we identified single nucleotide polymorphisms (SNPs) and potential candidate genes associated with clutch traits in Laiwu Black chickens. The restricted maximum likelihood method was used to estimate genetic parameters of clutch pattern in 399 Laiwu Black hens, using the GCTA software.ResultsThe results showed that SNP-based heritability estimates of clutch traits ranged from 0.06 to 0.59. Genotyping data were obtained from whole genome re-sequencing data. After quality control, a total of 10,810,544 SNPs remained to be analyzed. The GWAS revealed that 421 significant SNPs responsible for clutch traits were scattered on chicken chromosomes 1–14, 17–19, 21–25, 28 and Z. Among the annotated genes, NELL2, SMYD9, SPTLC2, SMYD3 and PLCL1 were the most promising candidates for clutch traits in Laiwu Black chickens.ConclusionThe findings of this research provide critical insight into the genetic basis of clutch traits. These results contribute to the identification of candidate genes and variants. Genes and SNPs potentially provide new avenues for further research and would help to establish a framework for new methods of genomic prediction, and increase the accuracy of estimated genetic merit for egg production and clutch traits.

Morphological descriptors of indigenous chickens: as a selection guide

ABSTRACT The visual morphologies in animals are associated positively or negatively with production, adaptation, and behavioral characteristics. For rural farmers with limited records, these features are considered reliable phenotypic markers. Thus, this study was intended to explore the unique morphological features of indigenous chickens as a farmer's selection guide. A total of 1,060 adult chickens from four rural districts were investigated for nine morphological traits. The single-comb type, supposed to be of good fertility, was the most prevalent. Yellow and white shanks were predominant, followed by gray, greenish-yellow, green, and black pigmentations. Crested and silky chickens were more frequent in highland areas, whereas naked-neck chickens were observed in lowlands. Chickens of the lowlands have brighter, more uniform plumage colors and yellow shank, beak, and earlobe colors. On the other hand, the highland and mid-altitude chickens are characterized by dark, colorful combinations of various feather colors: laced plumage, white shank, rose, and deformed rose combs. Moreover, multiple correspondence analyses revealed that morphological features have special associations with districts. Thus, the observed morphological heterogeneity of the indigenous chickens can be used as a good indicator of selective breeding. Therefore, the associations of these characteristics with productivity qualities could be confirmed by quantitative and molecular tools.

Distribution and developmental changes of IL-21 immunopositive cells in the bursa of Fabricius of Jinhu silky chicken.

Bursa of Fabricius (BOF) is a unique immune organ of birds. It is the place where lymphocytes develop, differentiate and mature. Young chicken BOF is susceptible to infection and damage, and even atrophy, causing immune suppression, and bringing huge economic losses to chicken production. Therefore, studying the regulatory mechanism of chicken bursa development is of great practical significance for disease prevention and diagnosis. Jinhu silky chicken (JSC) is a local excellent breed in the Fujian Province of China and with strong disease resistance. However, studies on the disease resistance of JSC are scarce. This study aimed to provide a theoretical basis for reproduction and disease control of JSC. Developmental features of the structure and the IL-21-positive cell (IL-21 PC) distribution on the BOF in JSC were measured from 7 to 300 days of age. Bursas of chicken (n = 36) were taken at 7, 35, 70, 150, 240, and 300 days of age for preparation of paraffin sections and stained with hematoxylin-eosin (HE) and immunohistochemistry. The microstructure of JSC's BOF was similar to that of other poultry. The cortical-medullary boundary of the bursa nodule was not obvious at 7 days of age, but it was evident after 35 days of age. Before 70 days of age, IL-21 positive cells (PC) were scattered on the BOF. At 150 days of age, the number of IL-21 PC in the bursa were the highest and the nuclei were clear. The level of IL-21 PC gradually decreased with age. The BOF degenerated and disappeared in 300-day-old JSC. The histological structure of the BOF was similar to that of other poultry. IL-21 PC were widespread in the BOF at different ages, but the numbers were different.

Substrate Specificity of Bacillus megaterium UСM B-5710 Keratinase

The specifics of the processing of livestock and poultry products is that in the process of obtaining the main marketable products, about half the feedstock at various stages of the technological process turns into waste that pollutes the environment. These by-products contain large amounts of the hard-to-digest keratin protein. The use of specific enzymes capable of degrading this protein helps not only to reduce the negative anthropogenic impact on nature but also to obtain valuable hydrolysates that can be used as a fertilizer for plants or a feed additive. The aim of this work was to study the ability of Bacillus megaterium UCM B-5710 to split various keratin-containing substrates: black and white chicken feathers, white turkey feathers, parrot feathers of various colors, sheep wool, pig bristles, and baby hair and nails. Methods. The culture was grown under conditions of submerged cultivation at 40 °C, with a nutrient medium stirring rate of 201 rpm for 6 days. For growth, a basic nutrient medium containing 0.5% defatted chicken feathers or other keratin-containing substrates as sole sources of carbon and nitrogen were used. Keratinase activity was assessed by UV absorption at 280 nm of hydrolysis products of keratin-containing raw materials. Protein was determined by the Lowry method, caseinolytic (total proteolytic) activity was determined by the Anson method modified by Petrova, and amino acid content was determined by the ninhydrin method. The degree of hydrolysis of the substrates was evaluated by the ratio of the initial and final weight of the substrate. Results. It was shown that the synthesis of keratinase by the culture of B. megaterium UCM B-5710 begins from the 6th hour of cultivation. The level of protein and proteolytic activity and the content of amino acids increased throughout the entire period of culture growth. The supernatant of the culture liquid of B. megaterium UCM B-5710 was most effective in splitting white chicken’s and turkey’s feathers, a little slower — feathers of black chicken and blue parrots, as well as wool of white sheep. According to the degree of splitting, the substrates used can be arranged in the following order: white turkey feathers &gt; white chicken feathers &gt; black chicken feathers &gt; blue parrot feathers &gt; white sheep wool &gt; baby nails &gt; pig bristle &gt; baby hair. The study of the effect of feather color on the resistance to decomposition showed that black, blue, and red feathers are more resistant, which coincides with the literature data. Conclusions. B. megaterium UCM B-5710 produces keratinase capable of splitting both α- and β-keratins, however, with different efficiencies and rates.

Associations of polymorphisms in prolactin and dopamine receptor D2 genes with reproductive traits on Silkie chicken

The Silkie chicken (Gallus gallus domesticus Brisson) is one of domestic chicken breeds with commercial rearing and breeding potentials for egg production. Prolactin (PRL) and dopamine D2 receptor (DRD2) are potential genes associated with reproductive traits in chickens. This study was conducted to analyze the association of PRL and DRD2 insertion/deletion (Indel) polymorphisms with chicken reproductive traits in Silkie chickens. A total of 380 hens from 16-40 weeks of age were used, with each one being placed in a separate cage. DNA isolation was performed using feather samples, and genotypes were detected using the Indel technique. Two polymorphisms consisting of 24 base pair (bp) Indel in the promoter region of the PRL gene and 22 bp Indel in the promoter region of the DRD2 gene were identified. At both sites, the Indel polymorphisms did not follow the Hardy-Weinberg equilibrium. In addition, with the exception of total eggs over 23 weeks of laying in the PRL gene, the analysis revealed no association between these polymorphic loci and any traits collected. In conclusion, birds with the DD genotype produced the maximum egg yield (73.6 eggs/hen), whereas those with the II genotype produced approximately 9 fewer eggs (64.1 eggs/hen), resulting in laying rates of 45.7% and 40.1%, respectively. For enhancing the egg-laying capacity of Silkie chickens via selective breeding, opting for DD birds with DD genotype of PRL Indel is highly recommended.

Analysis of the Selection Signal of the Tibetan Black Chicken Genome Based on Whole-Genome Sequencing.

The Tibetan chicken has adapted well to high altitudes genetically after its long-term habitation in the plateau. In this study, we analyzed the selection signal of Tibetan black chickens (TBCs) and discovered genes associated with the characteristics of germplasm. Whole-genome sequencing (WGS) was used to identify the single-nucleotide polymorphism (SNP) markers and genetic structures in the genome of Tibetan black chickens. Further, we performed a comparative population genomics analysis between the genomic data obtained in this present study and the genomic data for five wild red jungle fowls (RJFs) accessed from the NCBI database (GenBank accession number PRJNA241474). Thereafter, the Fst and Pi selections were used to identify genes under positive selection in the Tibetan black chicken genome. A total of 9,490,690 SNPs were identified in the Tibetan black chickens. In addition, the results from the gene ontology (GO) analysis showed that 732 genes of TBCs were enriched in a total of 210 GO terms with specific molecular functions such as regulation of cellular catabolic process, the MAPK signaling pathway, regulation of ion transport, growth, morphogenesis and lung alveolus development which may provide a better mechanism to facilitate oxygen transport and utilization in TBCs. Moreover, the results from the KEGG analysis showed that 732 genes of the TBCs were significantly enriched in the calcium signaling pathway, circadian entrainment (ADCY1, GNG7 and PER3), oxytocin signaling pathway and pathways of multiple neurodegeneration diseases. In addition, the CD86 antigen (CD86) was identified as a gene associated with the immune response in chickens. It was also revealed that genes such as TRIT1, HPCAL4, NT5C1A and HEYL were discovered under selection in Tibetan black chickens on chromosome 23. These genes may be related to the local adaptive characteristics of Tibetan black chickens, for instance, NT5C1A and HEYL may be involved in the high-altitude adaption of oxygen delivery in Tibetan black chickens. In summary, we found that selection mainly affects the disease resistance and cold acclimatization of Tibetan black chickens. Hence, these results may provide important genetic information for the evolution and breeding of Tibetan black chickens.