Strong bacterial stochasticity and fast fungal turnover in Taihu Lake sediments, China.

Understanding the assembly and turnover of microbial communities is crucial for gaining insights into the diversity and functioning of lake ecosystems, a fundamental and central issue in microbial ecology. The ecosystem of Taihu Lake has been significantly jeopardized due to urbanization and industrialization. In this study, we examined the diversity, assembly, and turnover of bacterial and fungal communities in Taihu Lake sediment. The results revealed strong bacterial stochasticity and fast fungal turnover in the sediment. Significant heterogeneity was observed among all sediment samples in terms of environmental factors, especially ORP, TOC, and TN, as well as microbial community composition and alpha diversity. For instance, the fungal richness index exhibited an approximate 3-fold variation. Among the environmental factors, TOC, TN, and pH had a more pronounced influence on the bacterial community composition compared to the fungal community composition. Interestingly, species replacement played a dominant role in microbial beta diversity, with fungi exhibiting a stronger pattern. In contrast, stochastic processes governed the community assembly of both bacteria and fungi, but were more pronounced for bacteria (R2 = 0.7 vs. 0.5). These findings deepen the understanding of microbial assembly and turnover in sediments under environmental stress and provide essential insights for maintaining the multifunctionality of lake ecosystems.

[Distribution and Potential Ecological Risk Assessment of Heavy Metals in Sediments of Lake Qinghai].

Lake Qinghai is the largest closed saltwater lake in China. In recent years, because of the rapid development of industry, agriculture, and tourism, the lake has been increasingly affected by human activities, which has attracted the attention of many scholars. In order to understand the distribution of heavy metals in the surface sediments of Lake Qinghai, the contents of Zn, Cu, Pb, Co, Ni, As, Cd, and Cr were investigated, the metal fractions were extracted, and the sources, as well as potential ecological risks, were analyzed. The results showed that:① the ω(As) (13.21 mg·kg-1) and ω(Cd) (0.21 mg·kg-1) in the surface sediments of Lake Qinghai were 1.13 and 1.53 times higher than the environmental background values, respectively, and the other heavy metal contents were all lower than the environmental background values. There were similar spatial distribution characteristics of analyzed metals except for As, with higher values measured in the northwestern area of the lake and the 151 Terminal. ② Except for Cd, the analyzed heavy metals mainly existed in the form of the residual state; by contrast, Cd mainly existed in the form of the bioavailable state, which has high potential toxicity to aquatic organisms. ③ Combined with the results of the correlation and principal component analysis, the metals including Zn, Cu, Pb, Co, Ni, Cd, and Cr were thought to mainly come from the natural environment, whereas the source of As was related to human activities, such as agricultural production. ④ According to potential risk analyses, the average of the metal potential ecological risk factors was 76.57, which indicated a slight ecological hazard level. However, it should be noted that the potential ecological hazard level and release risk of Cd at each site were higher than those of the other metals, especially in the regions nearing the estuary of Heima River, Lake Gahai, and the sand island, which showed higher levels of enrichment and potential release risk. Therefore, further attention should be paid to the potential impacts of Cd in sediments of these regions on the water environment and ecosystem.

[Synergistic Inhibitory Effect of Arsenic Trioxide Combined with Itraconazole on Hedgehog Pathway of Multiple Myeloma NCI-H929 Cells].

OBJECTIVE: To investigate the antitumor effect of arsenic trioxide (ATO) combined with itraconazole (ITRA) on human multiple myeloma NCI-H929 cells by synergistically inhibiting Hedgehog (HH) signaling pathway. METHODS: The inhibitory rate of NCI-H929 cells was assayed by MTT method. Tumor weight, tumor weight inhibition rate, and tumor volume of mouse model with multiple myeloma were examined. The ELISA were appled to detect the M-protein, qPCR and Western blot were used respectively to detect the expression level of Ptch, SMO, Gli and downstream target genes, the survival rate of tumor-bearing mice was analyzed. RESULTS: ATO combined with ITRA significantly inhibited NCI-H929 cell proliferation as compared with a single administration. The combination of ATO and ITRA could synergistically inhibit tumor growth and obviously reduced tumor burden, survival time of tumor-bearing mice was significantly prolonged. qPCR and Western blot results confirmed that the ATO combined with ITRA could significantly down-regulated expression of Gli1, leading to significantly decrease of cyclinD1 and BCL-2 expression levels. CONCLUSION: ATO combined with ITRA can more strongly suppress the growth of multiple myeloma NCI-H929 cells, as compared with a single administration. The synergistic effect of ATO and ITRA significantly down-regulates expression of Gli1 in HH signaling pathway, moreover the inhibition of target gene overexpression may be one of two drug mechanisms.

[Distributions of Arsenic Species in Different Eutrophic Waters of Lake Taihu and Their Relations to Environmental Factors].

A detailed field survey of arsenic species and water quality parameters was conducted in different eutrophicated regions of Lake Taihu (Zhushan Bay, Meiliang Bay, Gonghu Bay and Southern Taihu) in summer and winter. Furthermore, spatial and seasonal distributions of arsenic species and their relations to water quality parameters were investigated with multivariate analysis techniques. Higher average contents of total arsenic (TAs), arsenate[As(Ⅴ)], arsenite[ As(Ⅲ)] and methylarsenicals [sum of monomethylarsenic acid (MMA) and dimethylarsenic acid (DMA)] were observed in northern regions (including Zhushan Bay, Meiliang Bay, and Gonghu Bay) (TAs:2.58-3.34 µg·L-1, As(Ⅴ):1.37-2.34 µg·L-1, As(Ⅲ):0.53-0.64 µg·L-1, methylarsenicals:0.16-0.36 µg·L-1), compared to those in Southern Taihu (1.73, 1.10, 0.31, 0.10 µg·L-1). The results exhibited obvious spatial characteristics of arsenic species in the surface water of Lake Taihu. Besides, average values of TAs, As(Ⅴ), As(Ⅲ) and methylarsenicals in summer were 3.40, 2.06, 0.73 and 0.25 µg·L-1, respectively, higher than those in winter (1.78, 1.10, 0.30, 0.17 µg·L-1), reflecting significant seasonal characteristics of arsenic distribution. Factor analysis revealed the significant relationships of TAs and As(Ⅴ) with several water quality parameters, which suggested that spatial and seasonal distributions of TAs and As(Ⅴ) in Lake Taihu were affected by external pollution and internal arsenic release from sediments. Redundancy analysis further indicated significant effects of total phosphorus (TP) and total iron (TFe) on the distributions of TAs and As(Ⅴ). At the mean time, the above statistical analyses exhibited that As(Ⅲ) and methylarsenicals were positively correlated with chlorophyll-a (Chl-a). A large amount of microalgae could accumulate As(Ⅴ) and transform it more strongly to As(Ⅲ) and methylarsenicals in eutrophic regions when compared to mesotrophic region,especially in summer, reflecting the regulation of microalgae on arsenic biotransformation.

[Schisandrin B prevents doxorubicin-induced cardiotoxicity in rabbits].

OBJECTIVE: To study the effect of dexrazoxane in preventing doxorubicin-induced cardiotoxicity in rabbit-models and its mechanism. METHODS: Thirty one New Zealand white rabbits were randomly divided into two groups, doxorubicin (DOX) group and doxorubicin + dexrazoxane group. The cardiotoxicity was assessed by measuring serum superoxide dismutase (SOD), malondialdehyde (MDA), cardiac troponin I (cTnI), brain natriuretic peptide (BNP), left ventricular ejection function (LVEF), and left ventricular fractional shortening (LVFS), before and 4 and 10 weeks after intervention. Pathological changes in cardiac tissues and the apoptosis of myocardial cells were examined at the end of the experiment. Results Doxorubicin increased serum MDA, cTnI and BNP and decreased SOD, LVEF and LVFS (P < 0.05). Dexrazoxane (DEX) inhibited the increase of MDA, cTnI and BNP, and the decrease of LVEF and LVFS (P < 0.05). The rabbits treated with doxorubicin + dexrazoxane had slighter pathological changes in myocardium and apoptotic myocardial cells than those treated with DOX. CONCLUSION: Dexrazoxane prevents doxorubicin-induced cardiotoxicity through decreasing oxygen free radical production, cutting down lipid peroxidation, and depressing cardiocyte apoptosis.