Animal genetics最新文献

Pterin pigments are responsible for many of the bright colors observed across the animal kingdom. However, unlike melanin, the genetics of pterin-based pigmentation has received relatively little attention in animal coloration studies. Here, we investigate a lineage of axanthic ball pythons (Python regius) found in captivity as a model system to study pterin pigmentation in vertebrates. By crowdsourcing shed skin samples from commercial breeders and applying a case–control study design, we used whole-genome pool sequencing (pool-seq) and variant annotation. We identified a premature stop codon in the gene GTP cyclohydrolase II (gch2), which is associated with the axanthic phenotype. GCH2 catalyzes the first rate-limiting step in riboflavin biosynthesis. This study provides the first identification of an axanthism-associated gene in vertebrates and highlights the utility of ball pythons as a model to study pterin-based pigmentation.

The giant panda is a vulnerable species endemic to China and serves as a flagship species for biodiversity conservation. Accurately assessing population size in small populations has always been the foundation of conservation efforts. Owing to higher dropout rate and instability, the microsatellite marker has always caused the overestimation of the population size. The microhaplotype genetic marker, which is made from several adjacent SNPs, is as stable as the SNP marker and as polymorphic as the microsatellite marker. This study screened a panel of 32 candidate microhaplotype markers with an average polymorphic information content of 0.628 from a whole-genome sequencing dataset of 195 giant pandas. Afterwards, we successfully demonstrated the feasibility and reliability of the microhaplotype markers by genotyping half of them via the Illumina paired-end sequencing, with the markers amplified in four quadruplex PCR reactions, ranging from 142 and 234 bp in length. The cumulative non-exclusion probabilities for the full and half panel of markers are 6.477 × 10⁻²⁷ and 1.444 × 10⁻¹³, respectively. These markers offer a potential tool for individual identification, sex determination, the management and conservation of giant pandas.

A chromosomal rearrangement such as a reciprocal translocation (RT) in a breeding boar can produce unbalanced gametes during meiosis, leading to a decreased litter size with detrimental economic implications for breeders. FISH and standard karyotyping are currently used to detect RTs, but a fresh sample is required, limiting the shipping conditions. Here, we investigated Hi-C as an alternative technique to diagnose chromosome rearrangements. We show that Hi-C can be used to detect such RTs from either a fresh or a frozen blood sample and therefore this technique represents an alternative to FISH for RT detection.

Feather color is an important morphological trait of poultry. At present, the reports on the inheritance of plumage color of mule ducks at the molecular level are few, and the regulatory mechanism in white plumage rates of different mule ducks remains unclear. This study aimed to broaden the understanding of the white plumage rates in mule ducks to improve their production value. We used RNA sequencing to analyze and compare the mRNA expression profiles in hair follicle tissues from 10-week-old mule ducks with black and white plumages, thereby revealing the temporal gene expression patterns and pathways associated with plumage color regulation. In total, 1672 annotated differentially expressed genes (DEGs) were identified in black and white plumages from different databases between mule ducks with the 2 plumage colors. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment in hair follicle tissues indicated that the aforementioned DEGs were mainly involved in the melanin signaling pathway. Concurrently, we use weighted gene co-expression network analysis to detect core modules and hub genes associated with melanin biosynthesis in feathers. The green module exhibited the strongest correlation with the phenotypic traits, encompassing a total of 1049 genes. Subsequent Kyoto Encyclopedia of Genes and Genomes enrichment analysis identified 11 genes as pivotal in the melanin biosynthetic pathway, including EDRNB2, TYR, KIT, EDNRB, and MC1R. The differential expression of eight selected DEGs was verified using quantitative reverse transcription–PCR, and the results were consistent with RNA-seq data. This study provides a basis for understanding the differences in plumage color development in mule ducks.

Rabbits display a wide range of coat colors, with yellow being a particular phenotype that aids in exploring the molecular mechanisms of coat pigmentation. The Fujian yellow (FJY) rabbit, as China's only indigenous breed with a yellow coat, serves as a valuable genetic resource. Fujian yellow rabbits have predominantly yellow fur, with a diluted white hue on the distal limbs and tail. However, the genetic mechanism underlying yellow coat color remains unclear. To address this, we conducted selection signature analysis to identify candidate genes and potential casual mutations underlying the yellow phenotype in rabbits. Utilizing whole-genome resequencing, a total of 22 486 177 high-quality SNPs were identified from 30 individuals belonging to three Chinese indigenous rabbit breeds featured with yellow or non-yellow phenotype. The results revealed that the ASIP gene on chromosome 4 and the SNAI2 gene on chromosome 3 were under strong selection pressure, both of which play pivotal roles in determining coat color phenotypes. The ASIP gene is involved in melanogenesis across various livestock species, while the SNAI2 gene is linked to hypopigmentation in the distal regions such as the limbs and tail. We further identified two SNP variants, g.23870943C>T in the fourth intron of the ASIP gene, which is closely associated with the yellow phenotype, and g.73725380A>G downstream of the SNAI2 gene, probably contributing to the white shading in Fujian yellow rabbits’ limb and tail regions. These variants are key determinants in the development of the yellow coat color in rabbits. These findings advance the understanding of coat color pigmentation in domestic animals.

A 2-week-old litter of three Old English Sheepdog puppies presented with episodic generalised muscle hypertonia and cyanosis triggered by touch and noise. Owing to poor response to therapy and progression of symptoms, the puppies were euthanised. Post-mortem histology revealed perineuronal incrustations in the spinal cord, suggestive of ischemia or neuronal necrosis. Clinical symptoms, combined with necropsy and histopathology findings, led to a suspicion of startle disease, prompting a referral to a specialised clinical genetics centre. Whole exome sequencing (WES) of the nuclear family identified a homozygous truncating variant in the SLC6A5 gene in affected individuals, with both unaffected parents being heterozygous. Additional population screening found three phenotypically unaffected carriers, indicating that the variant segregates within the Old English Sheepdog breed. This raises concerns about the management of carriers and their breeding contributions if not properly guided by DNA testing. This study addresses a frameshift variant SLC6A5:c.1322del found in Old English Sheepdogs. Next to this, the value of genetic counselling and clinical genetics services in breeding programmes is highlighted to identify carriers and guide informed breeding decisions. Finally, the findings demonstrate the utility of WES in veterinary diagnostics and provide practical insights for breeders, veterinarians and geneticists to improve the health and welfare of Old English Sheepdogs.

For genetic data to be used in forensic casework, it has to be produced within a controlled environment that follows strict quality standards. However, recent reviews have suggested that wildlife forensic laboratories are behind in the development and adherence to appropriate standards for casework. This paper will address these concerns by documenting the standards that have been produced, highlighting the systems of assessment and competency testing available, and reviewing the status of validated reference genetic databases. Networks of dedicated wildlife forensic scientists across the globe, represented in part by the author list for this paper, illustrate the strides taken to build capacity in this field, and an ongoing commitment to present quality wildlife forensic evidence in court.

Stem cells are undifferentiated cells that exhibit a bivalent chromatin state that determines their fate. These cells have potential applications in human and animal health and livestock production. Somatic cell nuclear transfer or cloning is currently being used to produce genetically edited animals. A highly differentiated genome is the main obstacle to correcting epigenetic reprogramming by enucleated oocytes during cloning. Activation of pluripotency genes in the somatic genome is a promising strategy to contribute to more efficient epigenetic reprogramming, improving this technique. Recently, epigenome editing has emerged as a new generation of clustered regularly interspaced short palindromic repeats–clustered regularly interspaced short palindromic repeats-associated protein 9 technology with the aim of modifying the cellular epigenome to turn genes on or off without modifying DNA. Here, we characterize the DNA methylation profile of the CpG island spanning the 5′ untranslated region to intron 1 of the bovine octamer-binding transcription factor (Oct4) gene in gametes, embryos, and fibroblasts. DNA methylation patterns were categorized into three levels: low (0%–20%), moderate (21%–50%), and high (51%–100%). Sperm and embryos showed a hypomethylation pattern, whereas oocytes exhibited a hypo- to moderate methylation pattern. Fetal and adult skin fibroblasts were hypomethylated and moderately methylated, respectively. These results are essential for future studies aimed at manipulating the expression of Oct4. Thus, epigenome editing can be used to turn on the Oct4 in somatic cells to generate induced pluripotent stem cells. This strategy could potentially convert a fully differentiated cell into a cell with certain degree of pluripotency, facilitating nuclear reprogramming by the enucleated oocyte and improving cloning success rates.

Anhidrosis is defined as a decreased or absent ability to sweat in response to heat and exercise. In horses, this condition can increase the risk of life-threatening hyperthermia. A prior study has suggested that equine anhidrosis is associated with a missense variant (rs68643109) in the Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 4 (KCNE4) gene. This project aimed to validate this association in a population of well-phenotyped horses and to determine the allele frequency of this variant in publicly available whole-genome sequence data. Fifty horses within the University of California Davis Center for Equine Health herd were evaluated for anhidrosis using a series of intradermal terbutaline injections. From existing whole-genome sequence data, the rs68643109 genotype of each horse was identified. When stimulated with terbutaline, all 50 horses produced sweat. All three genotypes at rs68643109 were present in this population of horses; the allele previously associated with anhidrosis (G) was present at a frequency of 0.72. No statistical difference in total sweat score was found (p = 0.31). In whole-genome sequences from 820 other horses reported across three prior studies, the alternative (candidate) allele frequency was similarly high, ranging from 0.52 to 0.68. Since all 50 horses tested in our population produced sweat regardless of genotype, and the previously associated allele is present at a high frequency across datasets, these data fail to validate the missense variant within the KCNE4 gene as causative of or contributing to equine anhidrosis.

The size of the reference population and sufficient phenotypic records are crucial for the accuracy of genomic selection. However, for small-to-medium-sized pig farms or breeds with limited population sizes, conducting genomic breeding programs presents significant challenges. In this study, 2295 Yorkshire pigs were selected from three distinct regions, including 1500 from an American line, 500 from a Canadian line, and 295 from a Danish line. All populations were genotyped using the GeneSeek 50K GGP Porcine HD chip. To enhance genomic selection accuracy, we proposed strategies that combined multiple populations and leveraged multi-omics prior information. Cis-QTL from the PigGTEx database and QTL identified through genome-wide association studies were incorporated into the genomic feature best linear unbiased prediction (GFBLUP) model to predict the ADG100 and the BF100 traits. Results demonstrated that combining multiple populations effectively improved prediction accuracy for small population, accuracy for ADG100 increased by an average of 0.29 and accuracy for BF100 by 0.05. The GFBLUP model, which integrates biological priors, showed some improvements in prediction accuracy for the BF100 trait. Specifically, for the small population, accuracy increased by 0.09 in Scheme 1, where each population size was predicted independently. In Scheme 3, where the large population was used as a reference group to predict the small population, accuracy increased by 0.03. However, the GFBLUP model did not provide additional benefits in predicting the ADG100 trait. These findings offer effective strategies for genetic improvement in developing regions and highlight the potential of multi-omics integration to enhance prediction models.