Climate and land cover shape the fungal community structure in topsoil.

Globally, soils are subject to radical changes in their biogeochemistry as rampant deforestation and other forms of land use and climate change continue to transform planet Earth. To better understand soil ecosystem functioning, it is necessary to understand the responses of soil microbial diversity and community structure to changing climate, land cover, and associated environmental variables. With next-generation sequencing, we investigated changes in topsoil fungi community structure among different land cover types (from Forest to Cropland) and climate zones (from Hot to Cold zones) in the Western Pacific Region. We demonstrated that climate zones substantially (P = 0.001) altered the soil fungal beta-diversity (change in community composition), but not alpha-diversity (taxonomical diversity). In particular, precipitation, temperature, and also latitude were the best predictors of beta-diversity. Individual fungal classes displayed divergent but strong responses to climate variables and latitude, suggesting niche differentiation at lower taxonomic levels. We also demonstrated that fungal taxonomic diversity differentially responded to latitude across land covers: fungal diversity increased towards lower latitudes in the Forest and Cropland (R2 = 0.19) but increased towards both lower and higher latitudes in Fallow land (R2 = 0.45). Further, alpha-diversity was significantly influenced by soil pH in Forest (P = 0.02), and by diurnal temperature range in Fallow land and mean annual precipitation in Cropland. Collectively, various land cover types had differential influence on the latitude diversity gradient, while climate, and to some extent, edaphic variables, were crucial in shaping soil fungal community structure. Our results can also serve as a baseline for estimating global change impacts on fungal community structure in the Western Pacific Region.

Increased concentration of sialidases by HeLa cells might influence the cytotoxic ability of NK cells.

OBJECTIVE: Cancer cells reportedly have the ability to escape from the immune system, mainly from natural killer (NK) cells. Although the real mechanisms are complicated, some inhibitors that are secreted from the cancer cells might play an important role. This study's aim was to investigate the potential mediator released by cancer cells (HeLa) that contributes to the decreased cytotoxicity of NK cells. METHODS AND MATERIALS: An NK-HeLa coculture system was used to test the hypothesis that the presence of the potential mediator from cancer cells contributes to the decreased cytotoxicity of NK cells. RESULTS: After coculturing with HeLa cancer cells, the cytotoxicity of NK cells was decreased. When the coculture medium and culture medium containing commercialized sialidase were used to culture NK cells, the cytotoxicity of the NK cells was also inhibited. However, cytotoxicity was partially restored by a sialidase inhibitor (DANA). Western blot analysis of the HeLa cells after coculturing with NK cells demonstrated increased Neu2 and Neu3 expression in HeLa cells. CONCLUSIONS: The finding that Neu2 and Neu3 expression in cancer cells might be involved in the impaired function of NK cells, which could be restored by a sialidase inhibitor, provides a new concept that could be applied to the management of cancer.

Altered ganglioside GD3 in HeLa cells might influence the cytotoxic abilities of NK cells.

OBJECTIVE: Previously, we found that altered sialidases in HeLa cells in a natural killer-HeLa (NK-HeLa) coculture system contributed to the decreased cytotoxic ability of NK cells. However, changes that occur in the glycosylation of the HeLa cells in the NK-HeLa coculture system remain unknown. MATERIALS AND METHODS: An NK-HeLa coculture system was used to examine the changes that occur in the gangliosides of HeLa cells. RESULTS: GD3 expression in HeLa cells was significantly increased in the NK-HeLa coculture system. Exogenous ganglioside GD3 decreased the cytotoxic ability of the NK cells, which could be restored by the addition of the anti-GD3 antibody. Coadministration of GD3 and sialidase further decreased the cytotoxic ability of the NK cells, which could be partially restored by the addition of a sialidase inhibitor (DANA). GD3 expression in HeLa cells also decreased following DANA treatment. CONCLUSIONS: This study suggests that interactions between ganglioside GD3 and sialidases in HeLa cells influence the cytotoxic ability of NK cells.