Changes in Microbial Composition During the Succession of Biological Soil Crusts in Alpine Hulun Buir Sandy Land, China.

Biological soil crusts (biocrusts) are considered "desert ecosystem engineers" because they play a vital role in the restoration and stability maintenance of deserts, including those cold sandy land ecosystems at high latitudes, which are especially understudied. Microorganisms participate in the formation and succession of biocrusts, contributing to soil properties' improvement and the stability of soil aggregates, and thus vegetation development. Accordingly, understanding the composition and successional characteristics of microorganisms is a prerequisite for analyzing the ecological functions of biocrusts and related applications. Here, the Hulun Buir Sandy Land region in northeastern China-lying at the highest latitude of any sandy land in the country-was selected for study. Through a field investigation and next-generation sequencing (Illumina MiSeq PE300 Platform), our goal was to assess the shifts in diversity and community composition of soil bacteria and fungi across different stages during the succession of biocrusts in this region, and to uncover the main factors involved in shaping their soil microbial community. The results revealed that the nutrient enrichment capacity of biocrusts for available nitrogen, total nitrogen, total phosphorus, total content of water-soluble salt, available potassium, soil organic matter, and available phosphorus was progressively enhanced by the succession of cyanobacterial crusts to lichen crusts and then to moss crusts. In tandem, soil bacterial diversity increased as biocrust succession proceeded but fungal diversity decreased. A total of 32 bacterial phyla and 11 fungal phyla were identified, these also known to occur in other desert ecosystems. Among those taxa, the relative abundance of Proteobacteria and Cyanobacteria significantly increased and decreased, respectively, along the cyanobacterial crust-lichen-moss crust successional gradient. However, for Actinobacteria, Chloroflexi, and Acidobacteria their changed relative abundance was significantly hump-shaped, increasing in the shift from cyanobacterial crust to lichen crust, and then decreasing as lichen crust shifted to moss crust. In this process, the improved soil properties effectively enhanced soil bacterial and fungal community composition. Altogether, these findings broaden our understanding about how soil microbial properties can change during the succession of biocrusts in high-latitude, cold sandy land ecosystems.

Soil extracellular enzyme stoichiometry reflects microbial metabolic limitations in different desert types of northwestern China.

Soil extracellular enzyme activity (EEA) stoichiometry reflects the dynamic balance between microorganism metabolic demands for resources and nutrient availability. However, variations in metabolic limitations and their driving factors in arid desert areas with oligotrophic environments remain poorly understood. In this study, we investigated sites in different desert types in western China and measured the activities of two C-acquiring enzymes (ß-1,4-glucosidase and ß-D-cellobiohydrolase), two N-acquiring enzymes (ß-1,4-N-acetylglucosaminidase and L-leucine aminopeptidase), and one organic-P-acquiring enzyme (alkaline phosphatase) to quantify and compare the metabolic limitations of soil microorganisms based on their EEA stoichiometry. The ratios of log-transformed C-, N-, and P-acquiring enzyme activities for all deserts combined were 1:1.1:0.9, which is close to the hypothetical global mean EEA stoichiometry (1:1:1). We quantified the microbial nutrient limitation by means of vector analysis using the proportional EEAs, and found that microbial metabolism was co-limited by soil C and N. For different desert types, the microbial N limitation increased in the following order: gravel desert < sand desert < mud desert < salt desert. Overall, the study area's climate explained the largest proportion of the variation in the microbial limitation (17.9 %), followed by soil abiotic factors (6.6 %) and biological factors (5.1 %). Our results confirmed that the EEA stoichiometry method can be used in microbial resource ecology research in a range of desert types, and that the soil microorganisms maintained community-level nutrient element homeostasis by adjusting enzyme production to increase uptake of scarce nutrients even in extremely oligotrophic environments such as deserts.

[Anticancer activity of Crocodylus siamensis blood in vitro and in vivo].

OBJECTIVE: To study the anticancer effects of the blood of Crocodylus siamensis in vitro and in vivo. METHODS: The inhibitory effects of serum and plasma of Crocodylus siamensis on proliferation of HepG2, BGC823, HeLa and SKOV3 cell were measured by MTT assay. The mouse S180 tumor model was used to evaluate the anti-tumor effect in vivo. RESULTS: High dosage serum and plasma of Crocodylus siamensis could inhibit the proliferation of HepG2, BGC823, HeLa and SKOV3 cell. The tumor inhibitory rate of high dosage blood of Crocodylus siamensis on S180 tumor was up to 57.55%. CONCLUSION: The blood of breeding Crocodylus siamensis has anticancer activity.

[Effects of centipede extract on life span of drosophila].

OBJECTIVE: To evaluate effects of centipede on life span of drosophila and on the appearance of the filial generation. METHODS: Drosophila melanogaster (male and female) were cultured in tubes with centipede extraction at concentrations of 0, 0.2%, 1%, 2.5%, or 5% until all drosophila died. The appearance of the filial generation were observed. RESULTS: The life span, including average, longest and shortest life span was shortened in exposed groups of both sexes and significantly dose-dependent. The appearance of the filial generation showed normal. CONCLUSION: Centipede extracts accelerates the aging of drosophila and shortens their life span. The appearance of the filial generation is not affected. Clinic using centipede for a long period should be carefully.