Genomic Variation, Population History, and Long-Term Genetic Adaptation to High Altitudes in Tibetan Partridge (Perdix hodgsoniae).

Species residing across elevational gradients display adaptations in response to environmental changes such as oxygen availability, ultraviolet radiation, and temperature. Here, we study genomic variation, gene expression, and long-term adaptation in Tibetan Partridge (Perdix hodgsoniae) populations residing across the elevational gradient of the Tibetan Plateau. We generated a high-quality draft genome and used it to carry out downstream population genomic and transcriptomic analysis. The P. hodgsoniae populations residing across various elevations were genetically distinct, and their phylogenetic clustering was consistent with their geographic distribution. We identified possible evidence of gene flow between populations residing in <3,000 and >4,200 m elevation that is consistent with known habitat expansion of high-altitude populations of P. hodgsoniae to a lower elevation. We identified a 60 kb haplotype encompassing the Estrogen Receptor 1 (ESR1) gene, showing strong genetic divergence between populations of P. hodgsoniae. We identified six single nucleotide polymorphisms within the ESR1 gene fixed for derived alleles in high-altitude populations that are strongly conserved across vertebrates. We also compared blood transcriptome profiles and identified differentially expressed genes (such as GAPDH, LDHA, and ALDOC) that correlated with differences in altitude among populations of P. hodgsoniae. These candidate genes from population genomics and transcriptomics analysis were enriched for neutrophil degranulation and glycolysis pathways, which are known to respond to hypoxia and hence may contribute to long-term adaptation to high altitudes in P. hodgsoniae. Our results highlight Tibetan Partridges as a useful model to study molecular mechanisms underlying long-term adaptation to high altitudes.

Association between H-type Hypertension and White Matter Hyperintensity in Patients with Acute Ischemic Stroke.

OBJECTIVE: White matter hyperintensity (WMH) is related to the increased risk of ischemic stroke. It is unclear if H-type hypertension (H-type HBP) is associated with periventricular WMH (PWMH) and deep WMH (DWMH) of acute ischemic stroke. This study investigated the correlation between H-type HBP and the severity of PWMH and DWMH in acute ischemic stroke. METHODS: Consecutive patients with acute ischemic stroke were included in this cross-sectional observational study. The patients were divided into the following groups: the normal group, the simple hypertension group (Simple HBP), the simple hyperhomocysteinemia group (Simple HHcy) and the H-type HBP group. MR imaging and relevant clinical variables were obtained from the medical records. PWMH and DWMH were rated by using the Fazekas scale (score 0-3). All patients were defined to have moderate-severe PWMH or DWMH (score 2-3) and no or mild group (score 0-1). Multivariate binary logistic regression analysis was performed to determine the relationship between H-type HBP and the severity of PWMH and DWMH. RESULTS: Among 542 patients, 227 had moderate-severe PWMH and 228 had moderate-severe DWMH. Compared to the no or mild group, patients with moderate-severe PWMH (median age: 73 vs. 63 years) and DWMH (median age: 70 vs. 65.5 years) were older. Compared to the no or mild group, moderate-severe PWMH and DWMH were associated with a history of ischemic stroke (moderate-severe PWMH vs. no or mild group 20.7% vs. 11.7%, p = 0.004；moderatesevere DWMH vs. no or mild group 20.2% vs. 12.1%, p = 0.010); We found that H-type HBP was an independent risk factor for PWMH (OR 2.64, 95% CI 1.34-5.21) and DWMH (OR 3.64, 95% CI 1.82-7.26) after adjusting for the effect of relevant risk factors. CONCLUSION: This study suggests that H-type HBP is associated with the severity of PWMH and DWMH in acute ischemic stroke patients, which deserves further prevention measures.

Linking bacterial community shifts with changes in the dissolved organic matter pool in a eutrophic lake.

Aquatic bacterial communities play crucial roles in the circulation of nutrients in watershed ecosystems. However, the interaction between bacterial communities and chromophoric dissolved organic matter (CDOM) in freshwater ecosystems has not been studied in depth. In our study, we examined the constitution and interactions of CDOM with the bacterial community in Lake Chaohu and its inflow rivers under the influence of different exogenous pollutants. The results revealed that the bacterial community diversity in the inflow rivers was significantly lower than that in the lake sites. Clustering of different types of polluted inflow rivers integrated with the most abundant genera observed in specific areas indicated that environmentally guided species selection had a large impact on the composition of aquatic bacterial communities. Moreover, our study suggests that communities in lake environments may be more susceptible to interference through a variety of physiologies or via functional redundancy, allowing them to preserve their community structure. Through linear discriminant analysis effect size (Lefse) methods, we revealed that some taxa (from phylum to genus) were consistently enriched in the lake sites. Based on correlation network analysis results, the supersession niches of bacterial community members related to different CDOM in the biogeochemical process was determined. This study provides an ecological basis for the control of external pollution and the protection of the water environment in watershed ecosystems.

Seasonal variability of groundwater level effects on the growth of Carex cinerascens in lake wetlands.

Groundwater level is crucial for wetland plant growth and reproduction, but the extent of its effect on plant growth can vary along with changed precipitation and temperature at different seasons. In this context, we investigated the effect of two groundwater levels (10 cm vs. 20 cm depth) on growth and reproductive parameters of Carex cinerascens, a dominant plant species in the Poyang Lake wetland, during three seasons (spring, summer, and autumn) and during two consecutive years (2015 and 2016). Carex cinerascens showed low stem number, height, and individual and population biomass in summer compared to spring and autumn. 10 cm groundwater level was overall more suitable for plant growth resulting in higher stem height and biomass. However, the interactive effect between groundwater level and season clearly demonstrated that the effect of groundwater level on plant growth occurred mainly in autumn. After the withering of the plant population in summer, we observed that C. cinerascens growth recovered in autumn to similar values observed in spring only with 10 cm groundwater level. Consequently, we could deduce that lowering groundwater level in the studied Poyang Lake wetland will negatively impact C. cinerascens regeneration and growth particularly during the second growth cycle occurring in autumn. Additionally, our results showed that, independently of the season and groundwater level, population biomass of C. cinerascens was lower during drier year. Altogether, our findings suggest that water limitation due to both reduction in precipitation and decreased groundwater level during the year can strongly impact plant communities.

Spatial-Temporal Variation of Bacterial Communities in Sediments in Lake Chaohu, a Large, Shallow Eutrophic Lake in China.

Sediment bacterial communities are critical for the circulation of nutrients in lake ecosystems. However, the bacterial community function and co-occurrence models of lakes have not been studied in depth. In this study, we observed significant seasonal changes and non-significant spatial changes in the beta diversity and community structure of sediment bacteria in Lake Chaohu. Through linear discriminant analysis effect size (LEfSe), we observed that certain taxa (from phylum to genus) have consistent enrichment between seasons. The sudden appearance of a Firmicutes population in spring samples from the Zhaohe River, an estuary of Lake Chaohu, and the dominance of Firmicutes populations in other regions suggested that exogenous pollution and environmental induction strongly impacted the assembly of bacterial communities in the sediments. Several taxa that serve as intermediate centers in Co-occurrence network analysis (i.e., Pedosphaeraceae, Phycisphaeraceae, Anaerolineaceae, and Geobacteraceae) may play an important role in sediments. Furthermore, compared with previous studies of plants and animals, the results of our study suggest that various organisms, including microorganisms, are resistant to environmental changes and/or exogenous invasions, allowing them to maintain their community structure.