[Vertical Differences in Grassland Bacterial Community Structure During Non- Growing Season in Eastern Ulansuhai Basin].

Grassland is an important part of the regional ecosystem, and its micro ecological structures play key roles in the process of element migration and the evolution of ecological diversity systems. To discover the spatial difference of the grassland soil bacterial community, we collected five total soil samples at 30 cm depth and 60 cm depth in Eastern Ulansuhai Basin in early May (before the beginning of the new growing season, with a minimum influence of human activities and other factors). Based on 16S rRNA gene-based high-throughput sequencing technology, the vertical characteristic of the bacterial community was analyzed in detail. First, Actinobacteriota, Proteobacteria, Chloroflexi, Acidobacteriota, Gemmatimonadota, Planctomycetota, Methylomirabilota, and Crenarchacota all appeared in the 30 cm and 60 cm samples, with the relative contents all being higher than 1%. In addition, there were a total of six phyla, five genera, and eight OTUs in the 60 cm sample with relative contents higher than those in the 30 cm sample. As a result, the relative abundance changes in dominant bacterial phyla, genera, and even OTUs at different sample depths did not correspond to their contribution to the bacterial community structure. Second, because of the unique contribution to the bacterial community structure in 30 cm and 60 cm samples, the norank_f__norank_o__norank_c__norank_p__Armatimonadota and Candidatus_Xiphinematobacter could be utilized as key bacterial genera during ecological system analysis, belonging to the Armatimonadota and Verrucomicrobiota, respectively. Finally, the relative abundances of ko00190, ko00910, and ko01200 were all higher in 60 cm samples than those in 30 cm samples, which showed that through the increase in metabolic function abundance, the relative contents of C, N, and P elements in grassland soil had been reduced with the increase in depth. These results will provide references for further study on the spatial change of bacterial communities in typical grassland.

[Characteristics of Bacterial Community Structure in Wuliangsu Lake During an Irrigation Interval in Hetao Plain].

In order to study the bacterial community composition and corresponding function in Wuliangsu Lake at the end of the Hetao Plain during the irrigation gap period, lake samples were collected in September 2020, and the pH, TN, TP, DIP, DTP, NH4+-N, Chla, EC, SAL, and other indicators were analyzed. The 16S rRNA high-throughput sequencing method was used to explore the attached bacteria and bacterioplankton in 15 samples of the surface water in Wuliangsu Lake. The experimental results showed that:① the alpha diversity Chao and Shannon indices of attached bacteria were greater than that of bacterioplankton, but the median of Shannoneven index was the same. ② In each sampling point, the bacterioplankton of Proteobacteria and Actinobacteria in the top five dominant bacteria phyla were higher than that of attached bacteria, and the abundance of attached bacteria and bacterioplankton of Bacteroidota were staggered. On the contrary, the contents of attached bacteria of Verrucomicrobiota and Cyanobacteria were all higher than that of bacterioplankton. ③ Redundant analysis showed that pH had the most significant effect on dominant attached bacteria, and the effect of conductivity and salinity in dominant bacterioplankton was the most significant. ④ PICRUSt2 function prediction analysis showed that attached bacteria and planktonic bacteria had the strongest metabolic functions, showing abundant metabolic functions. There were 29 nitrogen-related effective KOs and 88 phosphorus-related effective KOs, with the greatest nitrogen-fixing function and strong inorganic phosphorus-dissolving function, and bacterioplankton played a greater role in the two functions.

Twist-related protein 1 negatively regulated osteoblastic transdifferentiation of human aortic valve interstitial cells by directly inhibiting runt-related transcription factor 2.

OBJECTIVE: Valve calcification involves transdifferentiation of valve interstitial cells (VICs) into osteoblasts. Twist-related protein 1 (TWIST1) has been established as a negative regulator of osteoblast differentiation in both mouse and human mesenchymal stem cells, but its function in human aortic VICs is unknown. In our study, we determined the mechanism of TWIST1 action in regulating osteoblastic transdifferentiation of human aortic VICs. METHODS: Human calcified and noncalcified aortic valves were examined for TWIST1 expression. Human aortic VICs were isolated and cultured. RESULTS: The data showed that calcified aortic valves express lower levels of TWIST1. In vitro experiments showed that TWIST1 overexpression inhibited the transdifferentiation of VICs into osteoblasts by decreasing the expression of runt-related transcription factor 2 (RUNX2) and its downstream osteoblastic markers. Through chromatin immunoprecipitation and dual luciferase assays, we found that TWIST1 repressed the expression of RUNX2 by directly binding to an E-box located at -820 bp of the RUNX2 P2 promoter region and inhibiting its activity. CONCLUSIONS: Our study results suggest that TWIST1 could play an important role in preventing human aortic valve calcification by negatively regulating osteoblastic transdifferentiation of human aortic VICs through direct inhibition of RUNX2.