Isolation of hydrophobic and hydrophilic variants of Candida albicans

We have previously demonstrated that most isolates of C. albicans are hydrophobic when grown at room temperature (RT, ca. 22-24 degrees C) and hydrophilic when grown at 37 degrees C. Variants of our standard strain LGH1095 were isolated that are hydrophobic at 37 degrees C and hydrophilic at RT. After repeated phase partitioning with cyclohexane-water cell populations that were 6-16% hydrophobic at RT and 66-80% hydrophobic at 37 degrees C were obtained. Subsequent limiting dilution experiments provided clones which were more hydrophobic at RT or hydrophilic at 37 degrees C. These were then recloned until the resultant populations were consistently under 5% cell surface hydrophobicity (CSH) at RT or over 95% at 37 degrees C. Treatment with several detergents as well as sugars did not decrease the CSH of these cells. Lipase and several proteases also had no effect. When treated with trypsin at a concentration twice that used to lower CSH of normal cells to less than 5%, the hydrophobic variant only decreased in CSH by 50%. Both variants were capable of germinating, although at different levels depending on prior growth temperature. Sensitivity to the germination inhibitor morphogenic autoregulatory substance (MARS) was similar to that of the parent strain.     

Degradation of some phenols and hydroxybenzoates by the imperfect ascomycetous yeastsCandida parapsilosis andArxula adeninivorans: evidence for an operative gentisate pathway

The imperfect ascomycetous yeastsCandida parapsilosis andArxula adeninivorans degraded 3-hydroxybenzoic acid via gentisate which was the cleavage substrate. 4-Hydroxybenzoic acid was metabolized via protocatechuate. No cleavage enzyme for the latter was detected. In stead of this NADH- and NADPH-dependent monooxygenases were present. In cells grown at the expense of hydroquinone and 4-hydroxygenzoic acid, enzymes of the hydroxyhydroquinone variant of the 3-oxoadipate pathway were demonstrated, which also took part in the degradation of 2,4-dihydroxybenzoic acid byC. parapsilosis.Abbreviations HHQ Hydroxyhydroquinone (1,2,4-trihydroxybenzene) - GSH reduced Glutathione     

Functional Expression of the Alkane-Inducible Monooxygenase System of the Yeast: Candida tropicalis IN Saccharomyces cerevisiae

The genes for the alkane-inducible monooxygenase system of the yeast Candida tropicalis, namely a cytochrome P450_alk (P450_alk) and a NADPH cytochrome P450 oxidoreductase (NCPR) gene, were transferred in Saccharomyces cerevisiae. The P450_alk gene was expressed in this host with the help of the yeast alcohol dehydrogenase I (ADHI) promoter and terminator, whereas the NCPR gene could be expressed with its own structural elements. The presence of P450_alk in S. cerevisiae microsomal fractions resulted in a new acquired lauric acid terminal hydroxylation activity. Moreover, the same activity, coupled with the appearance of 12-hydroxylauric acid derivatives, could be obtained by the addition of lauric acid to intact cells expressing P450_alk. The coordinate expression of the P450_alk and NCPR genes in S. cerevisiae elevated the turnover rate of the P450_alk monooxygenase activity about 2-fold.     

Candida albicans stress mannoproteins expression in superficial and systemic candidiasis

The presence of heat shock mannoproteins (HSMPs) reactive with sIgA was demonstrated in several C. albicans strains. The subculture of the C. albicans isolated from mucosal surfaces on Sabouraud's dextrose agar at 25 °C switched off the HSMP expression. A re-expression of the HSMPs was obtained in the same medium by shifting the temperature of incubation to 37 °C. However, expression of HSMPs in two strains isolated from deep infections was maintained during several subcultures on Sabouraud's dextrose agar at 25 °C. A glycoprotein of 200 kDa seemed to be the main HSMP reacting with vaginal sIgA. The data presented in this study suggest that factors other than temperature can influence the expression of C. albicans HSMPs and therefore these antigens should be referred as stress mannoproteins.Abbreviations HSMPs heat shock mannoproteins - MAb monoclonal antibody - sIgA secretory IgA     

Transfer factor in chronic mucocutaneous candidiasis

Fifteen patients suffering from chronic mucocutaneous candidiasis were treated with an in vitro produced TF specific for Candida albicans antigens and/or with TF extracted from pooled buffy coats of blood donors. CMI of the patients was assessed using the LMT and the LST in presence of candidine. The aim of the study was the clinical evaluation of TF treatment and the incidence of positive tests before, during, and after therapy. Immunological data were matched using the Chi square test. 87 LMT were performed for each antigen dose and at the dilution of 1/50, 58.9% (33/56) tests were positive during non-treatment or non-specific TF treatment. On the contrary 83.9% (26/31) were positive during specific TF treatment (P<0.05). In the LST, a significant decrease of thymidine uptake in the control cultures in presence of autologous or AB serum was observed when patients were matched according to non-treatment, and both non specific (P<0.05) and specific TF treatment (P<0.01). Only during specific TF treatment was a significant increase of reactivity against the Candida antigen at the highest concentration noticed, when compared with the period of non specific treatment (P<0.01). Clinical observations were encouraging: all but one patient experienced significant improvement during treatment with specific TF. These data confirm that orally administered specific TF, extracted from induced lymphoblastoid cell-lines, increases the incidence of reactivity against Candida antigens in the LMT. LST reactivity appeared not significantly increased with respect to the periods of non treatment, but was significantly increased when it was compared to the non-specific TF treatment periods. At the same time, a clinical improvement was noticed.     

Interactions ofCandida albicans with bacteria and salivary molecules in oral biofilms

The yeastCandida albicans coaggregates with a variety of streptococcal species, an interaction that may promote oral colonization by yeast cells.C. albicans andCandida tropicalis are the yeasts most frequently isolated from the human oral cavity and our data demonstrate that both these species bind toStreptococcus gordonii NCTC 7869 while two otherCandida species (Candida krusei andCandida kefyr) do not. Adherence ofC. albicans was greatest when the yeast had been grown at 30° C to mid-exponential growth phase. For 21 strains ofC. albicans there was a positive correlation between the ability to adhere toS. gordonii and adherence to experimental salivary pellicle. Whole saliva either stimulated or slightly inhibited adherence ofC. albicans toS. gordonii depending on the streptococcal growth conditions. The results suggest that the major salivary adhesins and coaggregation adhesins ofC. albicans are co-expressed.     

葱兰黄化病病原类菌原体的研究

葱兰为石蒜科(Amaryllidaceae)草本植物,是一种在我国各地普遍栽培的多年生观赏花卉.葱兰黄化病是1992年在杭州发现的一种新病害,该病对葱兰的生长和观赏价值有严重影响.罹病株(丛)最初表现为深红色斑点,逐渐扩大为鲜红色条斑或斑块并转为亮黄色,最后整株叶片大部分转为鲜艳的黄色,呈现典型的系统侵染.发病1—2月后整株(丛)地上部分枯死.发病一般始于早春(3月上旬),春末夏初有一个发病高峰期;秋末有另一个发病期,但病状较轻;感染株有恢复现象,即在下一个生长季能从地下部分重新生长出叶片,但病株叶片明显细小,有丛簇现象,病株开花少且花期短.作者从1992年春起,对该病害进行了病原分离、生物学测定和病组织超薄切片电镜检查,发现该病害可能与类菌原体有关,现将研究结果报告如下.1 材料和方法1.1 样品感病植株分别于1992年4月采自浙江农业大学校园和1992年6月采自杭州花圃,用盆栽保存于防虫温室中,同时采取健株作为对照.1.2 用病株分离病原和接种     

Detection of microbial surface antigens that bind Lewisa antigen

Abstract There is evidence that the Lewis^a blood group antigen is one of the receptors for a number of potentially pathogenic microorganisms. To determine how widely distributed the microbial adhesins are that bind this antigen, anti-idiotypic antibodies produced against monoclonal anti-Lewis^a were used in coagglutination assays to screen a variety of species. The following were agglutinated: 7/7 strains of Staphylococcus aureus ; 10/19 (53%) strains of Neisseria meningitidis ; 8/13 (62%) strains of Haemophilus influenzae ; 1/3 strains of Helicobacter pylori ; 1/2 strains of Neisseria gonorrhoeae ; 1/2 strains of Candida albicans . The application of the anti-idiotypic antibodies to studies of host cell receptors, isolation of adhesins and development of new epidemiological typing reagents is discussed.