[Characteristics and Sources of Microbial Aerosols in Urban and Mountainous Areas in Autumn and Winter in Xi'an, China].

To explore the bioaerosol composition characteristics and sources in urban areas and mountains, three sample sites were selected in urban (urban, suburban) and southern mountainous areas in Xi'an, and air, soil, and leaf samples were simultaneously collected. The fungi and bacteria community structures at different sampling sites were analyzed through a high-throughput sequencing method, and their spatio-temporal variations were also examined. Moreover, a source track technique was used to identify the source of microorganisms in the air. The results showed that the fungi and bacteria at different sampling sites were significantly different, indicating that the geographical location has a significant influence on the community structure of microorganisms in the air. In winter, more potential fungal pathogens and bacterial pathogens were detected in urban areas with high relative abundance and diversity. In addition, the results showed that the main local source of fungi and bacteria was the leaf surface, of which the contribution rate of bacteria in the air fine particles was up to (55±30)%. This study can provide a scientific basis for understanding the characteristics of microbial pollution in the atmosphere, and for air environment quality evaluation and disease prevention in China.

[The effects of calmodulin on the lipid-binding activity of CaM-binding protein-10 and maize non-specific lipid transfer protein].

Fluorescence-marked lipid binding experiment shows that CaMBP-10 has typical lipid binding feature of non-specific lipid transfer protein (nsLTP). We have compared the effects of calmodulin (CaM) on the lipid-binding activity of CaMBP-10 and maize nsLTP. Different influences were found in the presence of either Ca(2+) or EGTA. W-7 and TFP could abolish the influence of CaM. Therefore, it is suggested that CaM could interact specifically with both CaMBP-10 and maize nsLTP. Probably, there are different CaM regulatory mechanisms between CaMBP-10 and maize nsLTP.

[Cloning and expression of cDNA for maize nonspecific lipid transfer protein as well as calmodulin-binding activity analysis of the expression product].

Maize nonspecific lipid transfer protein (Zm-nsLTP) was cloned and expressed to investigate its CaM-binding activity. The cDNA of Zm-nsLTP was amplified using RT-PCR (Fig.1), and then inserted into the vector pET32a(+). The recombinant vector pET-Zm-nsLTP was expressed in E. coli BL21(DE3)trxB(-). Results of CaM-gel overlay assays (Fig.2) and CaM-sepharose pull-down experiments (Fig.3) indicated that recombinant Zm-nsLTP was bound to CaM in a Ca(2+)-independent manner, which is in accordance with the way that CaMBP-10 and Arabidopsis non-specific lipid transfer protein-1 (At-nsLTP1) are bound to CaM. The CaM-binding domain in Zm-nsLTP was mapped to the region of 47-60 amino acids (Fig.3), and online sequence analysis using Predict Protein program predicted that it has a BAA structure (Fig.4,5).