BDSF对白念珠菌酵母相和菌丝相的不同作用

白假丝酵母（又称白念珠菌）是人体重要的条件致病真菌。在正常人体中,白假丝酵母是一种无害共生真菌;在免疫力低下人群中,白假丝酵母可引起假丝酵母病,轻者可导致黏膜感染,重者可发展为系统疾病,直至危及生命。白假丝酵母从酵母态至菌丝态的形态转变是极其重要的致病因素之一。BDSF是小分子短链脂肪酸,由Burkholderia cenocepacia分泌产生。酵母态白假丝酵母,在BDSF≥30 μmol/L时因菌丝生长受强烈抑制,无法由酵母相向菌丝相转变。而菌丝相白假丝酵母,当BDSF在30 μmol/L和60 μmol/L时,菌丝进一步生长并产生分支,但随菌丝分支生长,新生的分支菌丝不断转变为酵母态;当BDSF增加至120 μmol/L时,菌丝生长和分支状况几乎完全受抑制。由此可见,BDSF不仅强烈抑制菌丝生长,还可促使新生的菌丝态向酵母态转化。     

白假丝酵母二相性及其与致病性关系的研究进展

白假丝酵母是二相性真菌,本文主要综述了近年来有关该茵的形态发育、二相性转移的外界条件、二相性发生的分子生物学基础及二相性与致病性之间关系方面的研究进展。     

三颗针对白假丝酵母的抑制作用

目的 研究三颗针对白假丝酵母的抑制作用。方法 采用溴化噻唑蓝四唑法（MTT）和琼脂平板法测定三颗针对白假丝酵母的最低抑菌浓度（MIC）和最低杀菌浓度（MFC）;利用倒置荧光显微镜观察三颗针对白假丝酵母菌丝形成的影响;采用MTT法测定三颗针对白假丝酵母菌丝萌发不同时期的抑制率。结果 三颗针对白假丝酵母具有较强的抑制作用。其中,采用琼脂平板法测得三颗针抑制该菌的MIC为2 mg/mL,MFC为4 mg/mL。三颗针能减缓该菌的生长速度或使其停止生长,且浓度越高作用效果越明显。其中4 mg/mL的三颗针作用白假丝酵母6 h后,能够完全抑制菌丝形成。对于24 h后已经萌发为菌丝态的白假丝酵母,三颗针可抑制菌丝的继续生长,与对照组相比,4 mg/mL的三颗针对于萌发2 h后的白假丝酵母的菌丝抑制率为76.7%（P<0.01）。结论 三颗针能抑制白假丝酵母菌丝的生长和萌发。     

假丝酵母一新种——北京假丝酵母

本文研究了一株从水果表皮分离到的假丝酵母,它与至今已发表的所有已知假丝酵母均不相同,定名为北京假丝酵母(Candida beijingensis)。     

白假丝酵母形态转换相关基因及其调控途径的研究进展

白假丝酵母可在酵母相和菌丝相之间进行转换,这种形态转换对白假丝酵母的黏附、侵入和逃逸宿主免疫系统攻击的能力等都具有很大的影响。近年来,运用分子生物学方法克隆出了一系列与白假丝酵母形态转换相关的基因,并发现了两条调控其形态转换的信号传导途径。     

白假丝酵母菌突变株ORF19.2500的功能研究

目的筛选50株白假丝酵母菌基因缺失菌,寻找出对白假丝酵母菌生物被膜形成相关基因,进一步探究白假丝酵母菌生物膜的致病机制。方法利用培养生物被膜的方法筛选50株基因缺失菌;利用XTT法验证所筛选出的白假丝酵母菌突变株ORF19.2500生物被膜形成缺陷;进一步观察ORF19.2500基因缺失菌生长、菌丝形成。结果用XTT法证明白假丝酵母菌突变株orf19.2500生物膜形成缺陷,且生长曲线和滴琼脂平板的方法均提示其生长速率减慢。在spider培养基上白假丝酵母菌突变株orf19.2500不能诱导菌丝形成,但在YPD+10%小牛血清则菌丝形成正常。结论白假丝酵母菌突变株orf19.2500可利用spider培养基缺陷而影响其酵母、菌丝二态性的转化,及其生物被膜的形成。     

白假丝酵母检测的研究进展

白念菌病已成为艾滋病等免疫功能低下患者的严重并发症和直接致死原因,是医源性感染的常见病之一,其早期诊断与防治是目前重要的研究课题。本文综述了近年来该菌免疫学及分子生物学检测技术试验与应用的研究进展。     

白假丝酵母活性代谢物种类及分离技术的研究进展

白假丝酵母是常见的条件致病菌,研究其生物机制有重要意义.代谢物作为生物体基因表达的终产物,对其种类和含量的研究可作为基因组学和蛋白质组学的重要补充.本文综述了目前研究中所发现的与白假丝酵母形态学和应激相关的代谢物种类和作用以及其分离和分析方法,为进一步研究其致病机制和耐药性提供参考.     

鉴别都柏林假丝酵母和白假丝酵母的一种新的烟草琼脂培养基

根据表型特征鉴别都柏林假丝酵母（都柏林念珠菌）和白假丝酵母（白念珠菌）的方法一般不完全可靠，最可信的选择是基于聚合酶链反应（PCR）的分子生物学方法，但因其要求条件较高，不适于推广使用。原本用于鉴定新生隐球菌的Staib琼脂和向日葵琼脂培养基在区分都柏林念珠菌和白念珠菌中的作用逐渐得到肯定,     

Cell surface shaving of Candida albicans biofilms, hyphae, and yeast form cells

We used a brief trypsin treatment followed by peptide separation and identification using nano-LC followed by off-line MS/MS to identify the surface proteins on live Candida albicans organisms growing in biofilms and planktonic yeast cells and hyphae. One hundred thirty-one proteins were present in at least two of the three replicates of one condition and distributed in various combinations of the three growth conditions. Both previously reported and new surface proteins were identified and these were distributed between covalently attached proteins and noncovalently attached proteins of the cell wall.     

Interactions of Candida albicans yeast cells, germ tubes and hyphae with human polymorphonuclear leucocytes in vitro

Suspensions of Candida albicans yeast cells, germ tubes and hyphae with biomass standardized by ATP measurement were compared for their relative susceptibilities to phagocytosis and intracellular killing by human polymorphonuclear leucocytes. All three forms were ingested to a similar extent, but significantly fewer yeast cells were killed intracellularly after ingestion than were filamentous forms of the fungus. Ketoconazole pretreatment significantly enhanced the susceptibility of hyphae, but not of germ tubes, to phagocytosis and intracellular killing. The opsonic requirements of the yeasts and filamentous forms for efficient phagocytosis and killing differed.     

Identification of salivary components that induce transition of hyphae to yeast in Candida albicans

Candida albicans , the major human fungal pathogen, undergoes a reversible morphological transition from single yeast cells to pseudohyphae and hyphae filaments. The hyphae form is considered the most invasive form of the fungus. The purpose of this study is to investigate the effect of saliva on hyphae growth of C. albicans. Candida albicans hyphae were inoculated in Roswell Park Memorial Institute medium with whole saliva, parotid saliva or buffer mimicking the saliva ion composition, and cultured for 18 h at 37 °C under aerobic conditions with 5% CO₂. Whole saliva and parotid saliva induced transition to yeast growth, whereas the culture with buffer remained in the hyphae form. Parotid saliva was fractionated on a reverse-phase C8 column and each fraction was tested for inducing transition to yeast growth. By immunoblotting, the salivary component in the active fraction was identified as statherin, a phosphoprotein of 43 amino acids that has been implicated in remineralization of the teeth. Synthetically made statherin induced transition of hyphae to yeast. By deletion of five amino acids at the negatively charged N-terminal site (DpSpSEE), yeast-inducing activity and binding to C. albicans were increased. In conclusion, statherin induces transition to yeast of C. albicans hyphae and may thus contribute to the oral defense against candidiasis.     

Proteomic analysis of cytoplasmic and surface proteins from yeast cells,hyphae, and biofilms of Candida albicans

Candida albicans is a human commensal and opportunistic pathogen that participates in biofilm formation on host surfaces and on medical devices. We used DIGE analysis to assess the cytoplasmic and non‐covalently attached cell‐surface proteins in biofilm formed on polymethylmethacrylate and planktonic yeast cells and hyphae. Of the 1490 proteins spots from cytoplasmic and 580 protein spots from the surface extracts analyzed, 265 and 108 were differentially abundant respectively (> 1.5‐fold, p <0.05). Differences of both greater and lesser abundance were found between biofilms and both planktonic conditions as well as between yeast cells and hyphae. The identity of 114 cytoplasmic and 80 surface protein spots determined represented 73 and 25 unique proteins, respectively. Analyses showed that yeast cells differed most in cytoplasmic profiling while biofilms differed most in surface profiling. Several processes and functions were significantly affected by the differentially abundant cytoplasmic proteins. Particularly noted were many of the enzymes of respiratory and fermentative pentose and glucose metabolism, folate interconversions and proteins associated with oxidative and stress response functions, host response, and multi‐organism interaction. The differential abundance of cytoplasmic and surface proteins demonstrated that sessile and planktonic organisms have a unique profile.