Evidence of balancing selection in multiple indigenous chicken populations.

Microsatellite DNA markers, which are assumed to drift, have been widely used to assess genetic diversity in all major domestic animal species. These markers provide insight into the arrival and dispersion history of a species, with regard to their content or management history. However, no direct evidence supports current standard microsatellite markers falling under this assumption. Therefore, the objective of this study was to investigate the effect and divergence of microsatellites under different types of selection on genetic patterns and population diversity. A total of 192 birds (Gallus gallus) from eight different geographic locations were investigated using 20 microsatellites that are classified into different groups by their selective effect (neutral, positive selection, and balancing selection) by the FDIST2 outlier test. The results showed that most polymorphisms were in the balancing selection marker group, the expected heterozygosity was 0.70, the observed heterozygosity was 0.65, and the mean number of alleles was 6.91. AMOVA revealed that the balancing group contributed the lowest amount of variance among groups, which was -0.60%, the highest variance contributed within the population being 92.28% in comparison with that of other groups. A similar pattern of population genetics was revealed following Slatkin linearized FST, principal component factor analysis, and population structure by Bayesian clustering. In conclusion, balancing selective markers offer high polymorphism for estimating genetic diversity but reduced genetic divergence between populations.

Transcript analysis of a goat mesenteric lymph node by deep next-generation sequencing.

Deep RNA sequencing (RNA-seq) provides a practical and inexpensive alternative for exploring genomic data in non-model organisms. The functional annotation of non-model mammalian genomes, such as that of goats, is still poor compared to that of humans and mice. In the current study, we performed a whole transcriptome analysis of an intestinal mucous membrane lymph node to comprehensively characterize the transcript catalogue of this tissue in a goat. Using an Illumina HiSeq 4000 sequencing platform, 9.692 GB of raw reads were acquired. A total of 57,526 lymph transcripts were obtained, and the majority of these were mapped to known transcriptional units (42.67%). A comparison of the mRNA expression of the mesenteric lymph nodes during the juvenile and post-adolescent stages revealed 8949 transcripts that were differentially expressed, including 6174 known genes. In addition, we functionally classified these transcripts using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) terms. A total of 6174 known genes were assigned to 64 GO terms, and 3782 genes were assigned to 303 KEGG pathways, including some related to immunity. Our results reveal the complex transcriptome profile of the lymph node and suggest that the immune system is immature in the mesenteric lymph nodes of juvenile goats.

Differential expression of Toll-like receptors in goat dominant and nondominant follicles.

The mechanism of dominant follicle selection is unclear because of its physiological complexity. However, some studies have reported that the immune system plays an important role in reproductive physiology. The objective of the current study was to investigate the differential expression of Toll-like receptors (TLRs) in the dominant (DFs) and nondominant follicles (NFs), and to determine the correlation between the expression of TLRs and the related genes, such as WNT4 and FOXL2. In this comparative study, the expression levels of TLRs, WNT4, and FOXL2 genes of DFs and NFs were obtained from three Dazu black goats were estimated using the real-time PCR. Our results showed no significant difference in the expression of seven TLRs (excluding TLR2, TLR5, and TLR8), WNT4, and FOXL2 between the DFs and NFs. In addition, the mRNA expression levels of WNT4 significantly correlated with the relative expression of TLR6 (r = 0.949739, P < 0.01); however, no significant expression of the TLR genes was found to be associated with FOXL2 mRNA expression. Our results support the fact that TLRs are not involved in the process of dominant follicle selection; however, TLR6 might play a role in the development of follicles by interacting with WNT4.

Desmoglein 4 diversity and correlation analysis with coat color in goat.

Desmoglein 4 (DSG4) has an important role in the development of wool traits in domestic animals. The full-length DSG4 gene, which contains 3918 bp, a complete open-reading-frame, and encodes a 1040-amino acid protein, was amplified from Liaoning cashmere goat. The sequence was compared with that of DSG4 from other animals and the results show that the DSG4 coding region is consistent with interspecies conservation. Thirteen single-nucleotide polymorphisms (SNPs) were identified in a highly variable region of DSG4, and one SNP (M-1, G>T) was significantly correlated with white and black coat color in goat. Haplotype distribution of the highly variable region of DSG4 was assessed in 179 individuals from seven goat breeds to investigate its association with coat color and its differentiation among populations. However, the lack of a signature result indicates DGS4 haplotypes related with the color of goat coat.

Variability with altitude of major histocompatibility complex-related microsatellite loci in goats from Southwest China.

We aimed to use microsatellite BM1258 loci of the major histocompatibility complex (MHC) as an indicator of the influence of genetic diversity of immunity in goats (Dazu Black, Hechuan White, Meigu, and Tibetan goat). In total, 132 animals comprising 50 Dazu Black goats, 24 Hechuan White goats, 34 Meigu goats, and 24 Tibetan goats were examined. Collectively, 18 different alleles and 42 genotypes were found. The overall observed levels of heterozygosity showed large divergence from the expected levels in the four breeds, and an increase in the mean number of alleles of BM1258 accompanied decreasing altitude of the livestock's habitat. Our results indicate that low-altitude regions or plains were more conducive to genetic material exchange and gene flow between different populations. In addition, it seems that the breeds from low-altitude regions were less susceptible to problems introduced by commercial animals.

Brief Note :Variability in the cathelicidin 6 (CATHL-6) gene in Tianzhu white yak from Tibetan area in China.

Cathelicidins are a major family of antimicrobial peptides (AMPs), an important component of innate immune system, playing a critical role in host defense and disease resistance in virtually all living species. Polymorphism and functional studies on cathelicidin of Tianzhu white yak contribute to understanding the specific innate immune mechanism in animals living at high altitudes in comparison to cattle and domesticated white yak. Thirty-six individuals of Tianzhu white yak, originating from the area of three ecotypes (Gansu in China), were investigated. The total length of the aligned Yak cathelicidin 6 (CATHL-6) sequences was 1923 bp, including six single nucleotide polymorphisms and one indel. Ten haplotypes were identified, and phylogenetic analyses resolved those 10 haplotypes in two clusters. The results indicate that the white yak originated from two domestication sites. In addition, lack of significant pairwise difference between sequences (Tajima's D = 0.92865, P > 0.10) in the CATHL-6 region indicates absence of population size expansion in current white yak population.

Short Communication: Diversity of TNF-α region in Chinese domestic goats.

Tumor necrosis factor-α is a cytokine with a wide range of effects on both lymphoid and non-lymphoid cells. In this study, we identified polymorphisms in major histocompatibility complex class III gene in the 4th exon and the 3' untranslated region of tumor necrosis factor-α to evaluate the immunogenetic diversity of Chinese south indigenous goat. Three single-nucleotide polymorphisms were identified and showed similar frequencies in different except MI loci. These data suggest that the high immunodiversity of the tumor necrosis factor-α region within these breeds can be used for strengthening variety improvement and promoting animal husbandry development in Chinese indigenous goats.

Dynamic comparison of genetic diversity in a Small Tail Han sheep population using meta-analysis.

The aim of this research was to identify the dynamic diversity of Small Tail Han sheep in its main producing areas between different years, and provide a basis for a breeding and genetic resources conservation strategy. For this purpose, 15 microsatellites were genotyped for Small Tail Han Sheep sampled in 2014 from Heze, China, and a comparative analysis of these data with those from a previous study was undertaken using meta-analysis. The results reveal that inbreeding has caused a reduction in diversity of Small Tail Han Sheep from 2008 to 2014. Overall, our results are helpful in understanding the dynamic change in diversity, as well as providing information for a conservation strategy for this population.

Expressional analysis of immune-related miRNAs in breast milk.

Immune-related miRNAs in breast milk are extracellular miRNAs that are related to immune organ development and regulation of the immune function in infants and young animals. The goal of this study was to compare the expression levels of five immune-related miRNAs in breast milk in black goats, humans, and dairy cattle. The miRNAs from milk were extracted and the expression levels were assessed using quantitive RT-PCR methods. MiR-146, miR-155, miR-181a, miR-223, and miR-150 were all detected in Dazu black goat milk, and these miRNAs were significantly more highly expressed in colostrum than in mature milk of goats (P < 0.01), except for miR-150. Further, all five miRNAs were expressed in human colostrum, but patterns differed from those in goats: miR-146 and miR-155 were highly expressed (P < 0.01) in human colostrum, whereas miR-223 was abundant in goat colostrum (P < 0.01). In addition, five miRNAs were significantly higher in bovine mature milk than in goat milk (P < 0.01). Taken together, these results confirm that immune-related miRNAs are rich in breast milk with different expression levels depending on the lactation phase and species.

Brief Note Low diversity of the major histocompatibility complex class II DRA gene in domestic goats (Capra hircus) in Southern China.

DRA encodes the alpha chain of the DR heterodimer, is closely linked to DRB and is considered almost monomorphic in major histocompatibility complex region. In this study, we identified the exon 2 of DRA to evaluate the immunogenetic diversity of Chinese south indigenous goat. Two single nucleotide polymorphisms in an untranslated region and one synonymous substitution in coding region were identified. These data suggest that high immunodiversity in native Chinese population.