Genomic structural variation is associated with hypoxia adaptation in high-altitude zokors

Inference of functional differentiation of intestinal microbes between two wild zokor species based on metagenomics

BACKGROUND

Currently, there are fewer studies on the intestinal microbes of wild zokors, and it is unclear how zokors adapt to special underground environments by regulating their intestinal microbes. Here, we explored the function of intestinal microbes of Eospalax cansus and Eospalax rothschildi based on metagenomics.

RESULTS

Both zokor species have similar intestinal microbial composition, but E. cansus has a higher proportion of bacteria involved in carbohydrate degradation. Functional analysis based on KEGG and CAZy databases indicated that the intestinal microbes of E. cansus harboured stronger carbohydrate degradation ability, mainly in starch and sucrose metabolism, and further in cellulose degradation. Furthermore, the cellulase activity was significantly higher in E. cansus than that in E. rothschildi. Eospalax cansus has a stronger microbial fermentation ability due to an increase in fibre-degrading bacteria like unclassified_f_Lachnospiraceae, Ruminococcus, and Clostridium. In addition, the dominant bacteria isolated from zokor were Bacillus, some of which could degrade both cellulose and hemicellulose.

CONCLUSION

Metagenomic analysis and bacterial isolation experiments indicate that E. cansus has a stronger microbial cellulose-degrading capacity, possibly as an adaptation to its limited food resources underground. © 2024 Society of Chemical Industry.

A Novel 6-bp Repeat Unit (6-bp RU) of the 13th Intron Within the Conserved EPAS1 Gene in Plateau Pika Is Capable of Altering Enhancer Activity

The plateau pika (pl-pika), a resilient mammal of the Qinghai-Tibet Plateau, exhibits remarkable adaptations to extreme conditions. This study delves into mutations within the Endothelial PAS Domain Protein 1 (EPAS1) gene, crucial for high-altitude survival. Surprisingly, a novel 6-bp insertion/deletion (indel) mutation in EPAS1's Intron 13, along with an additional repeat unit downstream, was discovered during PCR amplification. Genetic analysis across altitude gradients revealed a correlation between this indel's frequency and altitude, hinting at its role in altitude adaptation. Fluorescence enzyme assays unveiled enhancer activity within Intron 13, where the deletion of repeat units led to increased activity, indicating potential transcription factor binding. Notably, GCM1 emerged as a candidate transcription factor binding to the indel site, suggesting its involvement in EPAS1 regulation. These findings enrich our comprehension of high-altitude adaptation in plateau pikas, shedding light on the intricate interplay between genetic mutations, transcriptional regulation, and environmental pressures in evolutionary biology.

EPAS1 Variations and Hematological Adaptations to High-Altitude Hypoxia in Indigenous Goats in Yunnan Province, China

The EPAS1 gene plays a central role in hypoxia adaptation in high-altitude animals. Using over 400 blood samples from goats across elevations in Yunnan (500-3500 m), this study examined hematological traits, genetic polymorphisms, and protein structure. Red blood cell (RBC) and hemoglobin (HGB) levels increased significantly with altitude (p < 0.05), reflecting improved oxygen transport. A non-synonymous SNP (g.86650 A>T, p.Gln556Leu) exhibited adaptive selection, with the T allele frequency rising at higher altitudes (p < 0.05). At 2500 m, TT genotype goats showed significantly higher RBC and HGB levels than AA genotypes (p < 0.05). Protein modeling revealed structural instability caused by the polymorphism, highlighting its role in enhancing hypoxia adaptation. These findings provide a foundation for improving high-altitude livestock genetics.

Identifying Suitable Regions for Fritillaria unibracteata Cultivation Without Damage from the Pest Eospalax baileyi

The plateau zokor, Eospalax baileyi Thomas, is a destructive mammal pest affecting the cultivation of the medicinal plant Fritillaria unibracteata Hsiao et K.C. Hsia. Identifying regions exclusively suitable for the plant is an effective way to mitigate zokor-induced damage. In this study, the optimal MaxEnt model and ArcGIS were employed to predict suitable habitats for both species and identify pest-free regions for plant cultivation. Our results indicate that elevation and annual mean temperature are the critical factors influencing the plant distribution, while the pest distribution is determined by the elevation and precipitation of t warmest quarter. Under current and future climates, suitable habitats for the plant and the pest are concentrated in the Qinghai-Tibet Plateau, reaching their maximum under SSP245 and SSP126 in the 2090s, respectively. Current regions exclusively suitable for the plant without the pest are primarily found in eastern and central Tibet, reaching a maximum under SSP245 in the 2090s. Under climate change, the plant's suitable habitats, free from the pest damage, are predicted to be concentrated in eastern Tibet and northwestern Yunnan. Our findings provide practical guidance for F. unibracteata cultivation, as well as the monitoring and prevention of E. baileyi.

Investigation of Intestinal Microbes of Five Zokor Species Based on 16S rRNA Sequences

Zokor is a group of subterranean rodents that are adapted to underground life and feed on plant roots. Here, we investigated the intestinal microbes of five zokor species (Eospalax cansus, Eospalax rothschildi, Eospalax smithi, Myospalax aspalax, and Myospalax psilurus) using 16S amplicon technology combined with bioinformatics. Microbial composition analysis showed similar intestinal microbes but different proportions among five zokor species, and their dominant bacteria corresponded to those of herbivores. To visualize the relationships among samples, PCoA and PERMANOVA tests showed that the intestinal microbes of zokors are largely clustered by host species, but less so by genetics and geographical location. To find microbes that differ among species, LefSe analysis identified Lactobacillus, Muribaculaceae, Lachnospiraceae_NK4A136_group, unclassified_f_Christensenellaceae, and Desulfovibrio as biomarkers for E. cansus, E. rothschildi, E. smithi, M. aspalax, and M. psilurus, respectively. PICRUSt metagenome predictions revealed enriched microbial genes for carbohydrate and amino acid metabolism in E. cansus and E. smithi, and for cofactor and vitamin metabolism as well as glycan biosynthesis and metabolism in E. rothschildi, M. aspalax, and M. psilurus. Our results demonstrated differences in the microbial composition and functions among five zokor species, potentially related to host genetics, and host ecology including dietary habits and habitat environment. These works would provide new insight into understanding how subterranean zokors adapt to their habitats by regulating intestinal microbes.

Chromatin accessibility: biological functions, molecular mechanisms and therapeutic application

The dynamic regulation of chromatin accessibility is one of the prominent characteristics of eukaryotic genome. The inaccessible regions are mainly located in heterochromatin, which is multilevel compressed and access restricted. The remaining accessible loci are generally located in the euchromatin, which have less nucleosome occupancy and higher regulatory activity. The opening of chromatin is the most important prerequisite for DNA transcription, replication, and damage repair, which is regulated by genetic, epigenetic, environmental, and other factors, playing a vital role in multiple biological progresses. Currently, based on the susceptibility difference of occupied or free DNA to enzymatic cleavage, solubility, methylation, and transposition, there are many methods to detect chromatin accessibility both in bulk and single-cell level. Through combining with high-throughput sequencing, the genome-wide chromatin accessibility landscape of many tissues and cells types also have been constructed. The chromatin accessibility feature is distinct in different tissues and biological states. Research on the regulation network of chromatin accessibility is crucial for uncovering the secret of various biological processes. In this review, we comprehensively introduced the major functions and mechanisms of chromatin accessibility variation in different physiological and pathological processes, meanwhile, the targeted therapies based on chromatin dynamics regulation are also summarized.

Genomic structural variation contributes to evolved changes in gene expression in high-altitude Tibetan sheep

Tibetan sheep were introduced to the Qinghai Tibet plateau roughly 3,000 B.P., making this species a good model for investigating genetic mechanisms of high-altitude adaptation over a relatively short timescale. Here, we characterize genomic structural variants (SVs) that distinguish Tibetan sheep from closely related, low-altitude Hu sheep, and we examine associated changes in tissue-specific gene expression. We document differentiation between the two sheep breeds in frequencies of SVs associated with genes involved in cardiac function and circulation. In Tibetan sheep, we identified high-frequency SVs in a total of 462 genes, including EPAS1, PAPSS2, and PTPRD. Single-cell RNA-Seq data and luciferase reporter assays revealed that the SVs had cis-acting effects on the expression levels of these three genes in specific tissues and cell types. In Tibetan sheep, we identified a high-frequency chromosomal inversion that exhibited modified chromatin architectures relative to the noninverted allele that predominates in Hu sheep. The inversion harbors several genes with altered expression patterns related to heart protection, brown adipocyte proliferation, angiogenesis, and DNA repair. These findings indicate that SVs represent an important source of genetic variation in gene expression and may have contributed to high-altitude adaptation in Tibetan sheep.