Project description:Exposure to indoor air pollution generated from the combustion of solid fuels is a major risk factor for a spectrum of cardiovascular and respiratory diseases, including lung cancer. In Chinaâs rural counties of Xuanwei and Fuyuan, lung cancer rates are among the highest in the country. While the elevated disease risk in this population has been linked to the widespread usage of bituminous (smoky) coal as compared to anthracite (smokeless) coal, the underlying physiologic mechanism that smoky coal induces in comparison to other fuel types is unclear. As we have previously used airway gene-expression profiling to gain molecular insights into the physiologic effects of cigarette smoke, here we profiled the buccal epithelium of residents exposed to the burning of smoky and smokeless coal in order to understand the physiologic effects of solid fuels. Buccal mucosa scrapings were collected from healthy, non-smoking female residents of Xuanwei and Fuyuan counties who burn coal indoors. RNA was isolated and hybridized onto Affymetrix Human gene 1.0 ST GeneChips, capturing the gene-expression response of (n=26) smoky coal users and (n=9) smokeless coal users. 24-hour indoor personal exposure levels (PM2.5, Polycyclic Aromatic Hydrocarbons) were also captured during this sampling period.
Project description:Anthropogenic nitrogen (N) deposition may affect soil organic carbon (SOC) decomposition, thus affecting the global terrestrial carbon (C) cycle. However, it remains unclear how the level of N deposition affects SOC decomposition by regulating microbial community composition and function, especially C-cycling functional genes structure. We investigated the effects of short-term N addition on soil microbial C-cycling functional gene composition, SOC-degrading enzyme activities, and CO2 emission in a 5-year field experiment established in an artificial Pinus tabulaeformis forest on the Loess Plateau, China.
Project description:Evidence shows that bacteria contribute actively to the decomposition of cellulose and hemicellulose in forest soil; however, their role in this process is still unclear. Here we performed the screening and identification of bacteria showing potential cellulolytic activity from litter and organic soil of a temperate oak forest. The genomes of three cellulolytic isolates previously described as abundant in this ecosystem were sequenced and their proteomes were characterized during the growth on plant biomass and on microcrystalline cellulose. Pedobacter and Mucilaginibacter showed complex enzymatic systems containing highly diverse carbohydrate-active enzymes for the degradation of cellulose and hemicellulose, which were functionally redundant for endoglucanases, -glucosidases, endoxylanases, -xylosidases, mannosidases and carbohydrate-binding modules. Luteibacter did not express any glycosyl hydrolases traditionally recognized as cellulases. Instead, cellulose decomposition was likely performed by an expressed GH23 family protein containing a cellulose-binding domain. Interestingly, the presence of plant lignocellulose as well as crystalline cellulose both trigger the production of a wide set of hydrolytic proteins including cellulases, hemicellulases and other glycosyl hydrolases. Our findings highlight the extensive and unexplored structural diversity of enzymatic systems in cellulolytic soil bacteria and indicate the roles of multiple abundant bacterial taxa in the decomposition of cellulose and other plant polysaccharides.