过氧化氢酶在病原性真菌中的相关研究进展

过氧化氢酶普遍存在于原核和真核生物,具有抗氧化作用。这种作用有其有利的方面,即保护细胞免受氧自由基等氧化物的损害,抑制细胞受氧化因素刺激诱导的凋亡。同样,有其不利的方面,即保护病原微生物(包括真菌)不受宿主氧化系统的破坏。抗氧化作用作为病原性真菌的一种可能致病机制,国外已经有不少相关的报道,但是目前国内对这方面的研究较少,本文就过氧化氢酶在病原性真菌中的相关研究进展做一综述。     

Characterization of compensated mutations in terms of structural and physico-chemical properties

The study of the evolution of compensatory mechanisms among amino acids is paramount to our understanding of intramolecular epistatic interactions. It has been addressed from different points of view, for example much effort has been devoted to establish the number of compensatory mutations required per deleterious mutation. However, we still do not know how the nature of the compensated mutation determines the existence of compensatory mutations. Within this context, recent studies have produced several instances of an interesting phenomenon: human disease-associated residues may sometimes appear as wild-type residues in non-human proteins. This can be explained in terms of compensatory mutations, present in the non-human protein, which would neutralize the damage caused by the disease-associated residue. Therefore, comparison between these compensated mutations and non-compensated pathological mutations provides a simple approach to understand how the nature of the compensated deleterious mutation determines the existence of compensatory mutations. To address this issue, we have obtained a large set of compensated mutations and characterised them with a series of different properties. When comparing the resulting distributions with those from pathological mutations we find that in general compensated mutations are milder than pathological mutations. More precisely, we find that the probability that a compensatory mutation will evolve is directly related (i) to the location in the protein structure and (ii) to changes in physico-chemical properties (e.g. amino acid volume or hydrophobicity) of the compensated mutation.     

几丁质合酶在人类致病真菌中的研究进展

抑制真菌细胞壁的合成常作为防治真菌感染的安全有效手段。几丁质是真菌细胞壁及隔膜的重要结构成分,几丁质合酶是催化几丁质合成的关键酶。真菌细胞中几丁质合酶家族的不同成员在调控几丁质的合成中存在着差异,因此产生不同的生物学效应。本文通过综述几丁质合酶在人体三大条件致病真菌白色念珠菌、烟曲霉、新生隐球菌中的研究进展,分析了几丁质合酶对真菌致病性影响的机制,总结了几丁质合酶调控真菌细胞增殖、形态转换、病原菌与宿主的相互作用和细胞壁损伤诱导的补偿效应,展望了抗真菌感染的新策略及关于真菌几丁质合酶的未来研究方向。     

Susceptibility of clinical isolates of fungi to saperconazole

The in vitro activity of saperconazole against 228 strains of mycotic agents belonging to 48 species was investigated. Susceptibility testing was performed using a microtiter broth dilution method. Isolates of Candida albicans, C. tropicalis and Torulopsis glabrata showed distinct intra-species variation of susceptibility with MIC values ranging from 0.045 to 100 mg l^–1. The drug was inhibitory for the dermatophytes at a relatively narrow range of concentrations, most isolates being inhibited at MIC 0.78 mg l^–1. The strongest antifungal potency of saperconazole was exerted against clinical isolates of the genus Aspergillus (MIC 90% = 0.19 mg l^–1). Concentrations up to 100 mg l^–1 had no macroscopically recognizable effect on the growth of zygomycetous fungi (Mucor, Rhizopus, Syncephalastrum). Species of the genus Absidia with their good sensitivity are an exception. Justification of in vitro susceptibility testing of triazoles is discussed. In the author's opinion, MIC values can serve as an informative parameter showing the range of indications of these antifungals for treatment. It is concluded that saperconazole exhibits a very good activity against a broad spectrum of medically important fungi in vitro and can be considered a promising antifungal drug.     

常见致病菌糖基转移酶的结构与功能

糖基转移酶(glycosyltransferases,GTs)将糖基从活化的供体转移到糖、脂、蛋白质和核酸等受体,其参与的蛋白质糖基化是最重要的翻译后修饰(post-translational modifications,PTMs)之一。近年来越来越多的研究证明,糖基转移酶与致病菌毒力密切相关,在致病菌的黏附、免疫逃逸和定殖等生物学过程中发挥关键作用。目前,已鉴定的糖基转移酶根据其蛋白质三维结构特征分为3种类型GT-A、GT-B和GT-C,其中常见的是GT-A和GT-B型。在致病菌中发挥黏附功能的糖基转移酶,在结构上属于GT-B或GT-C型,对致病菌表面蛋白质(黏附蛋白、自转运蛋白等)进行糖基化修饰,在致病菌黏附、生物被膜的形成和毒力机制发挥具有重要作用。糖基转移酶不仅参与致病菌黏附这一感染初始过程,其中属于GT-A型的一类致病菌糖基转移酶会进入宿主细胞,通过糖基化宿主蛋白质影响宿主信号传导、蛋白翻译和免疫应答等生物学功能。本文就常见致病菌糖基转移酶的结构及其糖基化在致病机制中的作用进行综述,着重介绍了特异性糖基化高分子量(high-molecular-weight,HMW)黏附蛋白的糖基转移酶、针对富丝氨酸重复蛋白(serine-rich repeat proteins,SRRP)糖基化修饰的糖基转移酶、细菌自转运蛋白庚糖基转移酶(bacterial autotransporter heptosyltransferase,BAHT)家族、N-糖基化蛋白质系统和进入宿主细胞发挥毒力作用的大型梭菌细胞毒素、军团菌(Legionella)葡萄糖基转移酶以及肠杆菌科的效应子NleB。为揭示致病菌中糖基转移酶致病机制的系统性研究提供参考,为未来致病菌的诊断、药物设计研发以及疫苗开发等提供科学依据和思路。     

基于微生物源的抗虫基因发掘

植物转基因抗虫技术在害虫控制方面取得了巨大成功。商业化运用的抗虫基因目前全部来源于苏云金杆菌（Bacillus thuringiensis,Bt）的杀虫晶体蛋白基因,存在抗虫谱较窄及害虫逐渐产生抗性等问题,表明新型抗虫基因的筛选尤为重要。已有的文献研究表明,除了继续发掘Bt来源的新型杀虫蛋白基因以外,非Bt杀虫细菌及杀虫真菌也具有重要的发掘价值。     

Inhibition of expression of virulence genes of Yersinia pestis in Escherichia coli by external guide sequences and RNase P

External guide sequences (EGSs) targeting virulence genes from Yersinia pestis were designed and tested in vitro and in vivo in Escherichia coli. Linear EGSs and M1 RNA-linked EGSs were designed for the yscN and yscS genes that are involved in type III secretion in Y. pestis. RNase P from E. coli cleaves the messages of yscN and yscS in vitro with the cognate EGSs, and the expression of the EGSs resulted in the reduction of the levels of these messages of the virulence genes when those genes were expressed in E. coli.     

应用PCR方法检测油菜菌核病菌对多菌灵的抗药性*

通过保守的寡核苷酸引物B1/B3扩增出油菜菌核病菌MBCHR和MBCS菌株的部分β-微管蛋白基因,结果发现编码的198位氨基酸由Glu(GAG)突变为Ala(GCG),表现高水平抗药性。根据MBCHR菌株的突变设计2个快速检测方法:第一种方法是根据MBCHR菌株197和198位密码子(GACGAG→GACGCG)形成ThaI酶切位点(3’CGCG 5’),将B1/B3的扩增产物874bp片段酶切成193bp和681bp片段,而MBCS菌株的PCR产物不被酶切;第二种方法用198位突变密码子作为3’末端碱基设计2个等位基因特异性寡核苷酸引物(ASO)用于“nested”PCR或直接从基因组DNA扩增。通过PCR扩增和ThaI酶切能直接检测油菜菌核病菌的MBCHR和MBCS菌株,所得结果与传统菌落直径法相吻合。     

致病真菌对甲侵袭性的体外初步研究

目的观察不同致病真菌在体外对甲板的侵袭能力。方法将分离自甲真菌病患者的致病真菌包括白念珠菌、红色毛癣菌和短帚霉,接种到沙堡培养基中,同时将灭菌甲板埋植入接种处。第28d时,取出甲板,进行病理切片,观察真菌对甲板的侵袭能力。结果病理显示接种于红色毛癣菌及短帚霉的甲板内可见菌丝生长,而接种于白念珠菌的甲板内无菌丝生长。结论皮肤癣菌和霉菌可以在甲板内侵袭生长,而白念珠菌对甲板无侵袭能力。     

应用PCR方法检测油菜菌核病菌对多菌灵的抗药性

通过保守的寡核苷酸引物B1/B3扩增出油菜菌核病菌MBCHR和MBCS菌株的部分β-微管蛋白基因,结果发现编码的198位氨基酸由Glu(GAG)突变为Ala(GCG),表现高水平抗药性。根据MBCHR菌株的突变设计2个快速检测方法:第一种方法是根据MBCHR菌株197和198位密码子(GACGAG→GACGCG)形成ThaI酶切位点(3’CGCG 5’),将B1/B3的扩增产物874bp片段酶切成193bp和681bp片段,而MBCS菌株的PCR产物不被酶切;第二种方法用198位突变密码子作为3’末端碱基设计2个等位基因特异性寡核苷酸引物(ASO)用于“nested”PCR或直接从基因组DNA扩增。通过PCR扩增和ThaI酶切能直接检测油菜菌核病菌的MBCHR和MBCS菌株,所得结果与传统菌落直径法相吻合。     

中国苹果病害病原菌物名录

苹果为我国主要栽培水果,苹果产业在我国农业生产中占有重要地位.病原菌物是苹果病害的主要病原物,对我国苹果产量和品质造成严重损害.国际上病原菌物为苹果主要病原类型,其数量占苹果病原物的93.4％.我国植物病理学家和菌物学家对苹果病害的病原学进行了长期研究,描述与记载了大量国外已报道的病原真菌和病原卵菌,也描述了一些国外尚...     

Design, synthesis and anti-microbial activity of 1H-pyrazole carboxylates

In a SAR study, we have synthesized a few 1H-pyrazole carboxylate related microbicides using Vilsmeier reagent. The anti-microbial screening results of 1H-pyrazole-3-carboxylate are reported here for the first time. The effect of 1H-pyrazole carboxylates on the mycelial growth of plant pathogenic fungi is revealed. The first X-ray structure in the family of microbicidal 1H-pyrazole-4-carboxylates is presented.     

The time--mortality response of mosquito larvae infected with the fungus Culicinomyces

In laboratory experiments with Culicinomyces, the time of death of infected Anopheles hilli larvae decreased as the concentration of conidia to which they were exposed increased. At a concentration of 10³ conidia/ml, most first instar and third instar larvae died later than 2 days after exposure and the majority of dead specimens developed external sporulation on the exterior cuticle. On the other hand, at a concentration of 10⁵ conidia/ml, more than 60% of first and third instar larvae died within 2 days of exposure. Very few of these larvae developed external sporulation and it appears that most of them died after penetration by the fungus through the gut cuticle but before the hemocoel was colonized by mycelium. The reason for this rapid death at high concentrations of inoculum is not known, but it is thought that it may be caused by toxic substances associated with the invading hyphae which only attain a lethal titer when massive invasion originates from large numbers of conidia.     

高致病性禽流感

作者就高致病性禽流感对人类产生的危害、流行病学、临床症状表现及预防与控制策略等方面进行综述。     

Suppression of anti-Candida activity of macrophages by a quorum-sensing molecule, farnesol, through induction of oxidative stress

Farnesol is well known as a quorum-sensing molecule of Candida albicans . To assess the pathological function of farnesol, its effects on macrophage viability and functions including growth inhibitory activities against C. albicans were examined in vitro . Murine macrophages, when cultured in the presence of 56–112 μM of farnesol for 1–2 hr, decreased their activity inhibiting the mycelial growth of C. albicans and lost their viability. This suppression of macrophage function by farnesol was neutralized by the coexistence of the anti-oxidants probucol and trolox. Macrophages cultured in the presence of farnesol for 2 hr displayed morphological change of nuclei and DNA fragmentation, which suggested apoptosis of the cells. Intracellular production of ROS in the farnesol-treated macrophages was shown by fluorescence of DCFH-DA and increase of peroxidized materials. These effects of farnesol were blocked by probucol or trolox. These results indicate that farnesol lowered viability of the murine macrophages and suppressed their anti- Candida activity, perhaps through induction of ROS.     

Keratinophilic fungi isolated from children's sandpits in the Nablus area,West Bank of Jordan

The keratinophilic fungi of 29 sandpits from kindergarten schools and public parks in the city of Nablus was analysed to evaluate their role in the epidemiology of diseases caused by these fungi. Seventy two species were recovered 28 of which were common to both kindergartens and public parks sandpits. High percentage (57.4%) of fungal isolates found had been identified as the causes of various types of mycoses. Eight species of dermatophytes and closely related fungi were recovered, of which the followings were the most commonly found species in sandpits: Chrysosporium keratinophilum (20.7%), Microsporum gypseum (17.2%), Trichophyton mentagrophytes (6.9%), and C. evolceanui (6.9%).