Cutin deficiency in the tomato fruit cuticle consistently affects resistance to microbial infection and biomechanical properties, but not transpirational water loss

Plant cuticles are broadly composed of two major components: polymeric cutin and a mixture of waxes, which infiltrate the cutin matrix and also accumulate on the surface, forming an epicuticular layer. Although cuticles are thought to play a number of important physiological roles, with the most important being to restrict water loss from aerial plant organs, the relative contributions of cutin and waxes to cuticle function are still not well understood. Tomato ( Solanum lycopersicum ) fruits provide an attractive experimental system to address this question as, unlike other model plants such as Arabidopsis, they have a relatively thick astomatous cuticle, providing a poreless uniform material that is easy to isolate and handle. We identified three tomato mutants, cutin deficient 1 ( cd1 ), cd2 and cd3 , the fruit cuticles of which have a dramatic (95–98%) reduction in cutin content and substantially altered, but distinctly different, architectures. This cutin deficiency resulted in an increase in cuticle surface stiffness, and in the proportions of both hydrophilic and multiply bonded polymeric constituents. Furthermore, our data suggested that there is no correlation between the amount of cutin and the permeability of the cuticle to water, but that cutin plays an important role in protecting tissues from microbial infection. The three cd mutations were mapped to different loci, and the cloning of CD2 revealed it to encode a homeodomain protein, which we propose acts as a key regulator of cutin biosynthesis in tomato fruit.     

贵州小型猪主要病原微生物与寄生虫的控制

封闭群实验用贵州小型猪Sus scrofa domestica var. mino guizhounensis Yu是目前国内最主要的实验用小型猪种群之一(甘世祥, 1994).开展实验动物微生物与寄生虫的控制与监测,对保证实验动物和动物实验的质量和维护人类健康具有重要意义(孙靖,2005).本研究探索了环境消毒、体内外驱虫、疫苗接种等措施对贵州小型猪病原生物的携带和免疫状况的影响.     

产纤溶酶海洋微生物B5815菌株的筛选及鉴定

采用酪素平板、纤维蛋白平板的初筛和摇瓶复筛的方法从205株海洋微生物中筛选得到4株纤溶酶活性较强的菌株,其中菌株B5815产纤溶酶活性最高,平均达258 IU/mL。通过对菌株B5815的形态特征、生理生化特性的测定及16S rDNA序列分析,综合鉴定其为短小芽胞杆菌（Bacillus pumilus）。     

浙贝母内生真菌Nectria sp. JZ6分泌抑菌活性代谢产物的初步研究

Nectria sp.JZ6是从浙贝母新鲜鳞茎中首次分离到的一株内生真菌,其发酵液具有抑菌活性。为建立该真菌稳定分泌抑菌活性成分的发酵体系,本研究利用单因素实验和正交实验确定了发酵培养基的配方并初步优化了发酵条件。结果表明,将活化后的菌种接种于改良查氏培养基(8%葡萄糖,0.5%蛋白胨,0.05%KCl,0.1%K2HPO4,0.15%MgSO4,pH6.5)中,28℃、150r/min振荡培养6d后获得的发酵液抑菌活性比优化前提高了26%。该发酵液经100℃水浴30min不失活,在pH1-5时抑菌活性相对稳定,其后逐渐减弱,并在pH9.0及以上时丧失。Nectriasp.JZ6发酵液的乙酸乙酯浸膏抑菌活性最强,对金黄色葡萄球菌、藤黄八叠球菌、枯草芽孢杆菌、绿脓杆菌和大肠杆菌的最低抑菌浓度(MIC)分别为0.625、0.625、1.25、1.25和1.25mg/mL。     

细菌的运动性及其在致病初期过程中的作用

主要叙述了细菌的运动性及其在致病(初期)过程中的作用原理。细菌的运动性主要是靠鞭毛的旋转驱动的,可分为游泳运动性和爬行运动性2种方式。编码运动性和趋化性的基因大部分位于染色体上,但也有少数位于Ti质粒上。细菌的运动性、趋化性具有重要的病理学意义,而且主要在侵染初期发挥作用。     

番茄褐斑病菌产毒培养条件及其毒素的致病范围

对番茄褐斑病菌(Helminthosporiurn carposaprum)产毒条件和毒素对不同番茄品种的毒性进行了研究,结果表明,不同的pH值、温度、光照条件、培养天数所制备的毒素毒力差异显著,病菌的最佳产毒条件是室温25℃,光照12 h、pH值为6、振荡培养15 d;不同植物对病菌毒素的敏感性不同。     

Pattern‐mapped multiple detection of 11 pathogenic bacteria using a 16s rDNA‐based oligonucleotide microarray

Pathogen detection is an important issue in human health due to the threats posed by severe communicable diseases. In the present study, to achieve efficient and accurate multiple detection of 11 selected pathogenic bacteria, we constructed a 16S rDNA oligonucleotide microarray containing doubly specific capture probes. Many target pathogens were specifically detected by the microarray with the aid of traditional perfect match‐based analysis using our previously proposed two‐dimensional visualization plot tool. However, some target species or subtypes were difficult to discriminate by perfect match analysis due to nonspecific binding of conserved 16S rDNA‐derived capture probes with high sequence similarity. We noticed that the patterns of specific spots for each strain were somewhat different in the two‐dimensional gradation plot. Therefore, to discriminate subtle differences between phylogenetically related pathogens, a pattern‐mapping statistical model was established using an artificial neural network algorithm trained by experimental repeats. The oligonucleotide microarray system harboring doubly specific capture probes combined with the pattern‐mapping analysis tool resulted in successful detection of all target pathogens including even subtypes of two closely related species showing strong nonspecific binding. Collectively, the results indicate that our novel combined system of a 16S rDNA‐based DNA microarray and a pattern‐mapping statistical analysis tool is a simple and effective method for detecting multiple pathogens. Biotechnol. Bioeng. 2010;106: 183–192. © 2010 Wiley Periodicals, Inc.     

Why bacteria matter in animal development and evolution

While largely studied because of their harmful effects on human health, there is growing appreciation that bacteria are important partners for invertebrates and vertebrates, including man. Epithelia in metazoans do not only select their microbiota; a coevolved consortium of microbes enables both invertebrates and vertebrates to expand the range of diet supply, to shape the complex immune system and to control pathogenic bacteria. Microbes in zebrafish and mice regulate gut epithelial homeostasis. In a squid, microbes control the development of the symbiotic light organ. These discoveries point to a key role for bacteria in any metazoan existence, and imply that beneficial bacteria‐host interactions should be considered an integral part of development and evolution.     

Direct modifications of Rho proteins: deconstructing GTPase regulation

Small GTPases of the Rho protein family are master regulators of the actin cytoskeleton and are targeted by potent virulence factors of several pathogenic bacteria. Their dysfunctional regulation can lead to severe human pathologies. Both host and bacterial factors can activate or inactivate Rho proteins by direct post‐translational modifications: such as deamidation and transglutamination for activation, or ADP‐ribosylation, glucosylation, adenylylation and phosphorylation for inactivation. We review and compare these unconventional ways in which both host cells and bacterial pathogens regulate Rho proteins.