Beltrania sinensis sp. nov., an endophytic fungus from China and a key to species of the genus.

During a survey of endophytic fungi in plant roots in secondary forests in Yunnan, China, a novel ascomyceteous taxon, Beltrania sinensis, was isolated from Quercus cocciferoides Hand.-Mazz. and Fraxinus malacophylla Hemsl. This novel species is characterized by having oval or obovoid conidiogenous cells with several apical, flat-tipped denticles, and biconic, aseptate, smooth, pale brown conidia with a hyaline to subhyaline equatorial transverse band and apical tubular appendage. Phylogenetic analysis of the combined sequences of the internal transcribed spacer and the LSU rRNA gene confirmed its novel species status within the genus Beltrania. Here, the novel species is described and illustrated, and a taxonomic key to species in the genus Beltrania is provided.

Effects of heat stress on yeast heat shock factor-promoter binding in vivo.

Heat shock factor-DNA interaction is critical for understanding the regulatory mechanisms of stress-induced gene expression in eukaryotes. In this study, we analyzed the in vivo binding of yeast heat shock factor (HSF) to the promoters of target genes ScSSA1, ScSSA4, HSP30 and HSP104, using chromatin immunoprecipitation. Previous work suggested that yeast HSF is constitutively bound to DNA at all temperatures. Expression of HSF target genes is regulated at the post-transcriptional level. However, our results indicated that HSF does not bind to the promoters of ScSSA4 and HSP30 at normal temperature (23 degrees C). Binding to these promoters is rapidly induced by heat stress at 39 degrees C. HSF binds to ScSSA1 and HSP104 promoters under non-stress conditions, but at a low level. Heat stress rapidly leads to a notable increase in the binding of HSF to these two genes. The kinetics of the level of HSF-promoter binding correlate well with the expression of target genes, suggesting that the expression of HSF target genes is at least partially the result of HSF-promoter binding stability and subsequent transcription stimulation.