Animal genetics最新文献

The origin of domestic sheep (Ovis aries) can be traced back to the Asian mouflon (Ovis gmelini), in the Near East around 10 000 years ago. Genetic divergence within mouflon populations can occur due to factors such as geographical isolation, social structures, and environmental pressures, leading to different affinities with domestic sheep. However, few studies have reported the extent to which mouflon sheep contribute to domestic sheep in different regions. Here, we implemented the demographic analyses of sheep populations across the globe based on the whole genome resequencing data of 410 samples, Y chromosome genetic variation of 417 rams, and 396 complete mitogenomes of O. aries. This revealed genetic differentiation within Iranian mouflons and a close genetic affinity between northern Iranian mouflons and worldwide domestic populations. The result illustrates that domestic sheep in our study may have derived from the same mouflon populations. Furthermore, analyses of paternal and maternal genetic diversity showed that five Y chromosome haplogroups and seven mitochondrial haplogroups were identified, of which the lineages mtF and mtG were newly found and defined. A phylogeographic interpretation of our data reveals a cline of north to south Iranian mouflons, which may be largely explained by increasing urial introgression.

Red deer is a species of family Cervidae that is widely distributed in the world and is often raised to provide antlers, as a trophy or traditional medicine materials, and meat. Currently, the whole genomic data for red deer are very limited. Qingyuan Wapiti (QYW), China's first breed of red deer by artificial breeding, is well known for its high yield of antlers and large body size. The phylogenetic tree showed that QYW had a closer genetic relationship with Tarim red deer than European red deer. To explore the genetic diversity and selection signatures, the whole genome of 28 QYW individuals was sequenced, and 19 401 749 biallelic SNPs and 1 849 784 indels were obtained. The value of observed heterozygosity, expected heterozygosity, and nucleotide diversity were 0.258598, 0.268844, and 0.002193, respectively. Based on Tajima's D and integrated haplotype score analyses, the candidate regions containing 187 genes were detected, including PLD1, ANTXR1, PLCL1, CPE, and CTNNA3, which have been reported to be correlated with osteogenesis and mineralization, growth, and body size by previous studies. The results obtained in this study will contribute to elucidating the genetic mechanisms underlying the formation of excellent traits in QYW and provide the whole genome data for future exploration of genomic diversity and adaptation evolution of red deer worldwide.

In this study, I report an unexpected case of a Holstein calf that developed horns even though the sire was homozygous and the dam was heterozygous for polledness. After verifying and confirming the correct parentage, the parents and offspring were genotyped with the Illumina EuroG_MD BeadChip and the SNPs in the polled region on chromosome 1 were evaluated. In addition, the father was sequenced with next generation sequencing to identify possible, previously unknown variants. The deletion of two base pairs within the causative 80-kb duplication described for the Friesian polled variant was verified by melting curve analysis and the 80-kb duplication by droplet digital PCR. Analysis of all data showed that, as expected, the calf was heterozygous for all SNP positions flanking the 80-kb duplication but was homozygous wild type in the 80-kb duplication region and therefore carried horns. This is certainly a very rare case of a recombination within the highly conserved polled region, which on the one hand confirms that only the 80-kb duplication is responsible for the expression of the Friesian polled variant, but on the other hand also shows that caution is required when interpreting the usual routine genotyping of the horn status based on linked single nucleotide polymorphisms in the polled region on chromosome 1. Based on the present case, it is recommended that, in addition to the evaluation of the SNP data of the BeadChip, an extended diagnosis with direct detection of the 2-bp deletion (1:g.2629156_2629158delGT) should be carried out in any case when detecting the Friesian polled variant.

Body mass index (BMI) can serve as a reasonable indicator of overall body fat content in pigs. This study aimed to identify underlying variants and candidate genes associated with BMI in Yunong-black pigs. A single-step genome-wide association analysis (GWAS) was performed on 1405 BMI records and 924 Yunong-black pigs genotyped using a 50 K SNP Chip. De-regressed estimated breeding values were taken as the response variable in the GWAS. The estimated heritability for BMI was 0.157. Nine significant regions were associated with BMI, accounting for 12.828% of genetic variance, with the highest region explaining 1.969% of the genetic variance. Linkage disequilibrium analysis of the nine significant regions revealed that SNPs in six single-step GWAS-identified genomic regions were all located in the linkage disequilibrium blocks. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses of the 29 protein-coding genes annotated to these regions revealed that FABP2, a key gene associated with BMI in human, was enriched in the fatty acid binding term and the fat digestion and absorption pathway. This study provides a better insight into the genetic architecture of the BMI trait, and offers potential molecular markers for the breeding of Yunong-black pigs.

The feralization of domestic chicken makes the conservation and management of red jungle fowl (Gallus gallus) more complicated and challenging. We collected two Sulawesi feral chickens, located east of the Wallace Line, for whole-genome sequencing and de novo genome assembly. Phylogenetic and f4-statistics analyses indicated that the Sulawesi feralized domestic chickens (G. g. domesticus) received gene flow from G. g. gallus. We integrated ~45× ultra-long Oxford Nanopore Technology reads and ~28× PacBio HiFi reads to generate a de novo genome assembly of a female Sulawesi feral chicken (GGsula) with a contig N50 of 19.88 Mbp. We characterized structural variations in GGsula, and found some were related to nervous system. Our study provides the first genome assembly of feral chickens, which is a unique genomic resource to explore the process of chicken domestication and feralization.

Short tandem repeats (STRs) are abundant and have high mutation rates across cattle genomes; however, comprehensive exploration of cattle STRs is needed. Here, we constructed a comprehensive map of 467 553 polymorphic STRs (pSTRs) constructed from 423 cattle genomes representing 59 breeds worldwide. We observed that pSTRs in coding sequences and 5′UTRs (Untranslated Regions) were under strong selective constraints and exhibited a relatively low level of diversity. Furthermore, we found that these pSTRs underwent more contraction than expansion. Population analysis showed a strong positive correlation (R = 1) between pSTR diversity and single nucleotide polymorphic heterozygosity. We also investigated STR differences between taurine and indicine cattle and detected 2301 highly divergent STRs, which might relate to immune, endocrine and neurodevelopmental pathways. In summary, our large-scale study characterizes the spectrum of STRs in cattle, expands the scale of known cattle STR variation and provides novel insights into differences among various cattle subspecies.

Sheep have naturally pigmented wool which interferes with dyeing. Selection has been carried out over many years to remove pigment, with substantial success, but most wool still contains some pigment. As an alternative to selection, it has been proposed to take a naturally occurring mutation found in black Suffolk sheep, that blocks wool pigmentation, and introgress it into other breeds. However, the nature of the mutation has not been identified, prompting us to characterise it. The Suffolk white-fleece phenotype is associated with a novel 3-bp deletion in the gene SLC45A2, which encodes a membrane bound transporter that mediates melanin synthesis. The deletion results in the removal of one amino acid from the protein. The assignment of this deletion as the likely causative mutation is supported by it: being homozygous in the genome of nine animals with a white fleece and not homozygous in the genomes of eight animals with a black fleece; having a high level of conservation of the encoded amino acid sequence in the region surrounding the deleted amino acid across Mammalia; and the same deletion (but in a compound heterozygous state) being found in human SLC45A2 in a person with albinism.

The intramuscular oleic-to-stearic fatty acid ratio (C18:1n-9/C18:0) is an important indicator of the biosynthesis and desaturation of fatty acids in muscle. By using an RNA-Seq approach in muscle samples from 32 BC1_DU (25% Iberian and 75% Duroc) pigs with divergent values (high: H and low: L) of C18:1n-9/C18:0 fatty acids ratio, a total of 81 differentially expressed genes (DEGs) were identified. Functional analyses of DEGs indicate that mainly peroxisome proliferator-activated receptor signaling pathway (associated genes: PPARG, SCD, PLIN1, and FABP3) was overrepresented. Notably, SCD is directly involved in the conversion of C18:0 to C18:1n-9, and PPARG is a transcription factor regulating lipid metabolism genes, including SCD. However, other DEGs (e.g., ACADVL, FADS3, EPHB2, HGFAC, NGFR, NR0B2, MDH1, MMAA, PPP1R1B, SFRP5, RAB30, and TRARG1) are plausible candidate genes to explain the phenotypic differences of the C18:1n-9/C18:0 ratio. Interestingly, seven genetic variants within the SCD (including the well-known AY487830:g.2228T>C SNP and other novel genotyped polymorphisms) are associated with two haplotypes. Although the haplotypes are segregating at different frequencies in the H and L groups, they do not fully explain the desaturation ratios or the SCD expression levels. A more complex model, including polyunsaturated fatty acids such as C18:2n-6, C20:4n-6, and C18:3n-3, is suggested to explain the regulation of the C18:1n-9/C18:0 desaturation ratio in porcine muscle.