Genomic analyses of wild argali, domestic sheep, and their hybrids provide insights into chromosome evolution, phenotypic variation, and germplasm innovation.

Understanding the genetic mechanisms of phenotypic variation in hybrids between domestic animals and their wild relatives may aid germplasm innovation. Here, we report the high-quality genome assemblies of a male Pamir argali (O ammon polii, 2n = 56), a female Tibetan sheep (O aries, 2n = 54), and a male hybrid of Pamir argali and domestic sheep, and the high-throughput sequencing of 425 ovine animals, including the hybrids of argali and domestic sheep. We detected genomic synteny between Chromosome 2 of sheep and two acrocentric chromosomes of argali. We revealed consistent satellite repeats around the chromosome breakpoints, which could have resulted in chromosome fusion. We observed many more hybrids with karyotype 2n = 54 than with 2n = 55, which could be explained by the selfish centromeres, the possible decreased rate of normal/balanced sperm, and the increased incidence of early pregnancy loss in the aneuploid ewes or rams. We identified genes and variants associated with important morphological and production traits (e.g., body weight, cannon circumference, hip height, and tail length) that show significant variations. We revealed a strong selective signature at the mutation (c.334C > A, p.G112W) in TBXT and confirmed its association with tail length among sheep populations of wide geographic and genetic origins. We produced an intercross population of 110 F2 offspring with varied number of vertebrae and validated the causal mutation by whole-genome association analysis. We verified its function using CRISPR-Cas9 genome editing. Our results provide insights into chromosomal speciation and phenotypic evolution and a foundation of genetic variants for the breeding of sheep and other animals.

Ectopic expression of FGF5s induces wool growth in Chinese merino sheep.

Fibroblast growth factor 5 (FGF5) has been recognized as an inhibitor to cease animal hair growth, while in contrary, FGF5 short alternative transcript (FGF5s) can induce hair growth by antagonizing FGF5 function. To investigate the role of FGF5s in wool growth in Chinese Merino sheep, we generated transgenic sheep of ectopic expression of FGF5s by injection of recombinant lentivirus into zygote. Totally 20 transgenic sheep were obtained and 12 were alive after birth. Characterization of the transgene revealed that the transgenic sheep showed variety of integrant, ranged from 2 to 11 copies of transgene. The ectopic expression of FGF5s was observed in all transgenic sheep. Further study on the effect of ectopic expression of FGF5s revealed that the wool length of transgenic sheep were significantly longer than that of non-transgenic control, with 9.17cm of transgenic lambs versus 7.58cm of control animals. Notably, besides the increase of wool length, the yearling greasy fleece weight was also concordantly greater than that of wild-type (p<0.01), with 3.22kg of transgenic sheep versus 2.17kg of control lambs (p<0.01) in average. Our results suggested that overexpression of FGF5s could stimulate wool growth and resulted in increase of wool length and greasy wool weight.

CRISPR/Cas9-mediated loss of FGF5 function increases wool staple length in sheep.

Fibroblast growth factor 5 (FGF5) regulates hair length in humans and a variety of other animals. To investigate whether FGF5 has similar effects in sheep, we used clustered regularly interspaced short palindromic repeat (CRISPR)/CRISPR-associated 9 (Cas9) to generate loss-of-function mutations with the FGF5 gene in Chinese Merino sheep. A total of 16 lambs were identified with genetic mutations within the targeting locus: 13 lambs had biallelic modifications and three lambs had monoallelic modifications. Characterization of the modifications revealed that 13 were frameshift mutations that led to premature termination, whereas the other three were in-frame deletions. Thus, CRISPR/Cas9 efficiently generated loss-of-function mutations in the sheep FGF5 gene. We then investigated the effect of loss of FGF5 function on wool traits in 12 lambs and found that wool staple length and stretched length of genetically modified (GM) yearling sheep were significantly longer compared with that of wild-type (WT) control animals. The greasy fleece weight of GM yearling sheep was also significantly greater compared with that of WT sheep. Moreover, the mean fiber diameter in GM sheep showed no significant difference compared with WT sheep, suggesting that the increase in greasy fleece weight was likely attributed to the increase in wool length. The results of this study suggest that CRISPR/Cas9-mediated loss of FGF5 activity could promote wool growth and, consequently, increase wool length and yield.

Removal of a large number of foreign bodies in the maxillofacial region with navigation system.

The removal of a large number of foreign bodies in the maxillofacial region can be complicated and challenging. In this case report, a specific strategy for removal of multiple foreign bodies in the maxillofacial region is presented. A girl diagnosed with 24 foreign bodies in her left lower face and neck underwent the surgery using a computer-assisted navigation system. A specific strategy was used in this case, which included from one sub-region to the next and from the easiest to the most difficult. This strategy is recommended for the removal of a large number of foreign bodies in the maxillofacial region with a navigation system.

Whole-Genome Sequencing of Native Sheep Provides Insights into Rapid Adaptations to Extreme Environments.

Global climate change has a significant effect on extreme environments and a profound influence on species survival. However, little is known of the genome-wide pattern of livestock adaptations to extreme environments over a short time frame following domestication. Sheep (Ovis aries) have become well adapted to a diverse range of agroecological zones, including certain extreme environments (e.g., plateaus and deserts), during their post-domestication (approximately 8-9 kya) migration and differentiation. Here, we generated whole-genome sequences from 77 native sheep, with an average effective sequencing depth of ∼5× for 75 samples and ∼42× for 2 samples. Comparative genomic analyses among sheep in contrasting environments, that is, plateau (>4,000 m above sea level) versus lowland (<100 m), high-altitude region (>1500 m) versus low-altitude region (<1300 m), desert (<10 mm average annual precipitation) versus highly humid region (>600 mm), and arid zone (<400 mm) versus humid zone (>400 mm), detected a novel set of candidate genes as well as pathways and GO categories that are putatively associated with hypoxia responses at high altitudes and water reabsorption in arid environments. In addition, candidate genes and GO terms functionally related to energy metabolism and body size variations were identified. This study offers novel insights into rapid genomic adaptations to extreme environments in sheep and other animals, and provides a valuable resource for future research on livestock breeding in response to climate change.

[Polymorphism at codons 136, 141 and 154 in the ovine prion protein gene in the state of Xinjiang].

Scrapie is a fatal and infectious neurodegenerating disease. The polymorphism in the prion protein (PRNP) gene is linked to the development of clinical signs of scrapie. The most important polymorphism appears to be at codons at 136(V/A), 154(H/R), and 171(H/Q/R). In this study, we investigated the polymorphisms at these codons in 746 individuals among ten sheep breeds (i.e., ALeTai, BaShiBai, BaYinBuLuKe, Celehei, DuoLang, He Tian, Chinese Merino, German Merino, Texel, and Suffolk sheep) in Xinjiang in order to evaluate the relative susceptibility of sheep to scrapie. A total of 8 alleles (i.e., ARQ, ARR, ARH, ARK, VRQ, AHR, AHQ and AHH) were observed. The alleles ARQ and ARR were found in all of the breeds with the highest frequency for allele ARQ. Allele ARH was found in eight breeds except for Suffolk and German Merino, while the ARK was only identified in ALeTai, BaShiBai, BaYinBuLuKe, and DuoLang native sheeps. The alleles VRQ, AHR, AHQ and AHH were detected exclusively in Chinese Merino with extremely low frequencies. Moreover, the genotypes contained by the eight alleles were also determined subsequently. A total of thirteen genotypes, such as ARQ/ARQ, ARQ/ARK, ARR/ARR, ARH/ARH, ARQ/ARR, ARH/ARQ, ARH/ARR, ARK/ARK, ARH/ARK, ARQ/VRQ, ARQ/AHQ, ARQ/AHR and ARH/AHH were detected. The genotype ARQ/ARQ with moderate susceptibility was found with the highest frequency among the ten breeds, whereas the genotype ARR/ARR with highest resistance to scrapie was merely identified in BaYinBuLuKe, Celehei, Chinese Merino, Texel and German Merino sheep, which had very low frequencies. In addition, the genotype VRQ/ARQ with high susceptibility was first variant reported in Chinese Merino sheep. Our data, therefore, indicate that the general genetic resistance of dominating sheep breeds in Xinjiang to scrapie was considerably low.