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Recognition and degradation of insoluble crystalline cellulose by Polyporus arcularius
Tadanori Aimi,Yuka Ohnishi,Mitsutoshi Nagase,Tsuyoshi Ichiyanagi,Yutaka Kitamoto 한국버섯학회 2010 한국버섯학회지 Vol.8 No.4
The genes encoding cellulases, which belong to glycosyl hydrolase families have been cloned from the basidiomycetous mushrooms. The transcripts of cellulase genes are strongly induced when the mycelia are grown in medium containing crystalline cellulose, and they are not expressed in medium containing glucose, but how insoluble substrates such as microcrystalline cellulose are recognized by these fungal cells is not clear. The polypore mushroom Polyporus arcularius is a wood-decomposing basidiomycete that produces at least three types (I, II, and IIIa) of carboxymethyl cellulase (CMCase) when the medium contains crystalline cellulose as the sole carbon source and produced mainly cellobiose in the medium. The genomic and cDNA clones encoding the family 12 endoglucanase (CMCase IIIa) gene (cel3A) of P. arcularius have been sequenced, and Cel3A has been expressed as an active enzyme in Escherichia coli. To determine the role and function of each type of cellulase in the degradation of crystalline cellulose by basidiomycetous mushrooms, the structure of all of the cellulase genes should be investigated, but the nucleotide sequences of the other cellulase genes in P. arcularius have not yet been reported. In the current study, the genomic and cDNA clones encoding the endoglucanases (cel4), and the two cellobiohydrolases (cel1 and cel2) of P. arcularius sequenced and characterized. The predicted amino acid sequence of Cel1 Cel2, Cel3a and Cel4 are similar to glycosyl hydrolase family 7, 6 12 and 5 protein, respectively. The expressions of the all cellulase genes (cel1 cel2, cel3a and cel4) were induced by Avicel (microcrystalline cellulose) and cellopentaose but repressed by glucose, cellobiose, cellotriose, and cellotetraose. There was a low level of transcription of both genes regardless of the carbon source. These results suggest that P. arcularius cells constitutively express a very low level of cellulase that can degrade insoluble crystalline cellulose and that the transcription of celluases in the cells is induced by products produced by these endoglucanases such as cellooligosaccharides. From our findings, we propose a possible mechanism for the recognition and degradation of insoluble crystalline cellulose by fungal cells.
Nuclear behavior during basidiospore formation in Rhizopogon roseolus (=R. rubescens)
Kiyomi Sawada,Norihiro Shimomura,Tadanori Aimi 한국버섯학회 2010 한국버섯학회지 Vol.8 No.4
Rhizopogon roseolus (Corda) Th. M. Fr. (=R. rubescens Tul. & Tul.), known as “shoro” in Japan, is a hypogeous basidiomycete that is an important ectomycorrhizal symbiont of the Pinaceae. Rhizopogon roseolus produced a fruiting body with a basic globose to subglobose shape. Basidiospores were encompassed in a glebal chamber in the fruiting body. However, little is known about basidiosporogenesis and nuclear behavior after karyogamy. We treated R. roseolus glebar chambers with Gimsa acid and observed their hymenium microscopically to characterize nuclear behavior and basidiosporogenesis. Our observations revealed the following five characteristics: ⅰ) meiosis and postmeiotic mitosis took place in the basidium; ⅱ) meiosis occurred in the center of the basidium; ⅲ) the sterigma appeared when the first meiotic division occurred; ⅳ) the center of the basidium constricted slightly when the second meiotic division occurred; ⅴ) after postmeiotic mitosis, asynchronous nuclear migration from the basidium to the basidiospores took place, producing eight uninucleate basidiospores. However, unusual nuclear behavior was frequently observed, indicating that regulations of the timing and the way of nucleus entering to the spores were not exact in R. roseolus.
Koo, Jaseung,Koga, Tadanori,Li, Bingquan,Satija, Sushil K.,Rafailovich, Miriam H. American Chemical Society 2016 Macromolecules Vol.49 No.9
<P>We investigated the effect of density fluctuation of supercritical carbon dioxide (scCO(2)) on anomalous swelling of multilayer polymer thin films On the ridge in the pressure temperature phase diagram of CO2. In order to measure the swelling ratio along the film depth, we alternatively deposited hydrogenated poly(methyl Methacrylate) (PMMA) and deuterated polystyrene (dPS) thin films and performed the neutron reflectivity measurements as a function of CO2 pressure at 36 degrees C. The results showed that, in contrast to previous studies, CO2 was to penetrate deeply:throughout the, multilayer thin film where the magnitude of swelling along the density fluctuation ridge of CO2 was independent of film thickness. Block copolymer thin films of dPS-b-PMMA with a parallel lamellar orientation also showed similar swelling behavior in scCO(2). However, it is well-known that single-layer polymer thin films exhibit anomalous swelling behavior only the film surface. This difference is probably due to the fact that the multilayer thin films have the CO2-philic PMMA layer sandwiched between dPS layers, which can function, as a CO2 reservoir, thereby transferring the CO2 molecules from the PMMA layers to the adjacent dPS layers. Furthermore, we found that the interaction between polymers and substrates was not significant in scCO(2) from diffusion dynamics results using neutron reflectivity, thereby facilitating anomalous dilation of polymers near the substrates without a pinning effect.</P>