Preparation of Ag+/TiO2 Composite Coating Film for Preservation of Nanfeng Citrus

Using tetrabutyl titanate as the precursor, silver nitrate as the load agent, silver-doped titanium dioxide coating film was prepared by sol-gel method. Three agent samples were characterized by X-ray diffraction （XRD） analysis to investigate the crystal structure, which confirmed a synergistic antibacterial effect. The antibacterial and preservative effects of silver-doped titanium dioxide coating film on Nanfeng citrus were investigated preliminarily. Nutritional indicators of ripe Nanfeng citrus before and after preservation were detected to investigate the preservative properties of silver-doped titanium dioxide coating film and compare the effects of different components of composite coating film. The results showed that Ag＋/TiO2 composite coating film exhibited high antibacterial and preservative effects on Nanfeng citrus under visible light illumination condition.

Human KIAA1018/FAN1 nuclease is a new mitotic substrate of APC/C^(Cdh1)

A recently identified protein, FAN1 (FANCD2-associated nuclease 1, previously known as KIAA1018), is a novel nuclease associated with monoubiquitinated FANCD2 that is required for cellular resistance against DNA interstrand crosslinking (ICL) agents. The mechanisms of FAN1 regulation have not yet been explored. Here, we provide evidence that FAN1 is degraded during mitotic exit, suggesting that FAN1 may be a mitotic substrate of the anaphase-promoting cyclosome complex (APC/C). Indeed, Cdh1, but not Cdc20, was capable of regulating the protein level of FAN1 through the KEN box and the D-box. Moreover, the up-and down-regulation of FAN1 affected the progression to mitotic exit. Collectively, these data suggest that FAN1 may be a new mitotic substrate of APC/C Cdh1 that plays a key role during mitotic exit.

酿酒酵母荧光定位报告菌株的开发

【目的】为了给外源蛋白在酿酒酵母细胞中的定位提供参考,构建酿酒酵母荧光定位报告菌株。【方法】运用染色体同源重组的方法,将突变的、已进行酵母表达优化的红色荧光蛋白RedStar分别整合到12个酵母细胞器标记蛋白的C端,与之进行融合表达,用特异性引物对每一个酵母荧光定位报告菌株进行PCR扩增和测序验证,用激光共聚焦显微镜进行荧光检测,对线粒体和细胞核进行特异性染料染色,用EGFP标记沙门氏菌已知定位蛋白SipA,与构建的相应荧光定位报告菌株进行共定位。【结果】构建的酿酒酵母荧光定位报告菌株可分别标示酵母细胞的肌动蛋白、晚期胞内体、细胞核、核周质、纺锤体、线粒体、过氧化物酶体、脂滴、初级内吞体、次级内吞体、高尔基体顺面及高尔基体反面。PCR扩增及测序验证、荧光检测、染料与相应报告菌株的共定位、已知定位蛋白SipA与相应报告菌株的共定位均提示报告菌株构建成功。【结论】这些报告菌株的构建,为日后在酵母中观察细胞器动态变化,以及未知蛋白在酵母中的定位提供了基础性工具。

Exploration of the key functional proteins from an efficient cellulolytic microbial consortium using dilution-to-extinction approach

In the present study, the cellulose binding proteins（CBPs） secreted by a putative cellulolytic microbial consortium were isolated and purified by affinity digestion. The purified CBPs were subsequently separated by sodium dodecyl sulfate–polyacrylamide gel electrophoresis（SDS-PAGE）. Using mass spectrometric analyses, eight CBPs were identified and annotated to be similar to known proteins secreted by Clostridium clariflavum DSM 19732 and Paenibacillus sp. W-61. In addition, in combination with dilution-to-extinction approach and zymogram analysis technique, CBPs 6（97 k Da） and 12（52 k Da） were confirmed to be the key functional proteins that influence cellulolytic activities. Moreover, structural domain analyses and enzymatic activity detection indicated that CBPs 6 and 12 contained glycoside hydrolase families（GH） 9 and 48 catalytic modules, which both revealed endoglucandase and xylanase activities. It was suggested that the coexistence of GH9 and GH48 catalytic domains present in these two proteins could synergistically promote the efficient degradation of cellulose.