High-frequency switching of colony morphology in Candida albicans

The pathogenic yeast Candida albicans switches heritably and at high frequency between at least seven general phenotypes identified by colony morphology on agar. Spontaneous conversion from the original smooth to variant phenotypes (star, ring, irregular wrinkle, hat, stipple, and fuzzy) occurs at a combined frequency of 1.4 X 10(-4), but is increased 200 times by a low dose of ultraviolet light that kills less than 10 percent of the cells. After the initial conversion, cells switch spontaneously to other phenotypes at a combined frequency of 2 X 10(-2). Switching is therefore heritable, but also reversible at high frequency. The genetic basis of this newly discovered process and its possible role in Candida pathogenesis are considered.     

Influence of the lethal yellow (Ay) gene on estrous synchrony in mice

Introduction of an adult male induces partially synchronous estrus in female laboratory mice that have been caged in groups. In the inbred YS/ChWf strain, this effect was observed only when the male was nonyellow (aa), while males heterozygous for the lethal yellow allele (A(y)a) failed to induce synchrony.     

白念珠菌菌落PCR方法的建立和应用

白念珠菌(Candida albicans)是临床上引起系统真菌感染的主要病原真菌,在白念珠菌临床鉴定和基因组功能研究中,通常要提取其基因组DNA以进行PCR。以白念珠菌菌落为材料,通过蜗牛酶处理后直接进行PCR,从而建立一种简捷快速的PCR模板获取方法。结果表明,该方法避免了提取转化子基因组DNA的过程,可以大大提高工作效率。     

抗白色念珠菌的海洋微生物的分离与鉴定

本文旨在从海洋沉积物样品中分离筛选出具有抗白色念珠菌特性的细菌菌株。通过涂布平板法分离出112株菌株,通过初筛得到6株对白色念珠菌有拮抗作用的菌株,经琼脂扩散法培养复筛,最终得到1株拮抗效果最好的菌株,命名为NB04-N1,其抑菌圈直径为(30.13±0.45)mm。16S rDNA测序鉴定结果证明该菌株为绿脓杆菌(Pseudomonas)。     

白念珠菌临床分离株的基因分型及药物敏感性研究

采用PCR方法对241株临床白念珠菌分离株编码rRNA的25SrDNA的Ⅰ类内含子区进行分析．根据扩增条带大小进行基因分型及序列分析;药物敏感试验采用NCCLS M27-A微量稀释法方案;受试菌株为随机选择其中的80株白念珠菌临床分离株;试验药物为氟康唑、伊曲康唑、酮康唑、5-氟胞嘧啶以及两性霉素B。探讨白念珠菌基因分型与抗真菌药物敏感性之间的关系。基因分型表明：241株临床白念珠菌分离株中A型181株,B型34株．C型26株;B型含有Ⅰ类内含子的保守区域,C型含有部分保守区域．A型则缺乏Ⅰ类内含子的这些保守区域。白念珠菌A型为最常见的基因型。药物敏感试验提示：不同白念珠菌基因型对5-氟胞嘧啶敏感性存在显著差异,对其他4种抗真菌药物敏感性无显著差异。     

鸡白色念珠菌的分离鉴定及其防治措施

[目的]寻找鸡白色念珠菌的有效防治措施。[方法]近10年来,从湖北省100多个蛋鸡场收集鸡白色念珠菌病料,对病料进行白色念珠菌的分离和鉴定,探讨该病的初步诊断方法和防治措施。[结果]从832份鸡病料中分离到86株白色念珠菌。从2只鸡的嗉囊炎症部位涂片镜检结果发现,有卵形生芽的或不生芽的酵母状细胞和假菌丝。该病的诊断应以流行病学、症状及病理变化等资料为依据,并结合病原学检查。[结论]可通过向健康鸡群定期投喂"真菌通治"等生物制剂,也可在饲料中添加5.00%大蒜、维生素和0.05%龙胆紫水,改善鸡舍环境条件等措施来预防鸡白色念珠菌。发病鸡则应立即隔离消毒,喂服制霉菌素。     

白鲜碱体外抗白色念珠菌活性研究

白色念珠菌等真菌是能够引起人类及动物患病的重要致病菌。本实验测定了白鲜碱对临床22株临床分离氟康唑耐药白色念珠菌的最小抑菌浓度（MIC），采用棋盘式微量稀释实验测定了两药联合应药的分级抑制浓度指数（ractional inhibitory concentration index，FICI）值。结果表明，白鲜碱有较好的抗白色念珠菌活性且与氟康唑有协同作用。     

Adhesive and mammalian transglutaminase substrate properties of Candida albicans Hwp1

The pathogenesis of candidiasis involves invasion of host tissues by filamentous forms of the opportunistic yeast Candida albicans. Morphology-specific gene products may confer proinvasive properties. A hypha-specific surface protein, Hwp1, with similarities to mammalian small proline-rich proteins was shown to serve as a substrate for mammalian transglutaminases. Candida albicans strains lacking Hwp1 were unable to form stable attachments to human buccal epithelial cells and had a reduced capacity to cause systemic candidiasis in mice. This represents a paradigm for microbial adhesion that implicates essential host enzymes.     

环介导等温扩增技术快速检测血液中白色念珠菌

目的 探讨环介导等温扩增法(loop-mediated isothermal amplification,LAMP)检测血液中白色念珠菌的可行性.方法 采用通用基因组DNA提取试剂盒提取血液中白色念珠菌DNA,应用LAMP方法进行扩增,采用浊度仪进行检测.结果 该方法能够检测出血液中白色念珠菌,而其它临床常见血流感染的...     

Induction of mating in Candida albicans by construction of MTLa and MTLalpha strains

Although the diploid fungus Candida albicans, a human pathogen, has been thought to have no sexual cycle, it normally possesses mating-type-like orthologs (MTL) of both of the Saccharomyces cerevisiae mating-type genes (MAT) a and alpha. When strains containing only MTLa or MTLalpha were constructed by the loss of one homolog of chromosome 5, the site of the MTL loci, MTLa and MTLalpha strains mated, but like mating types did not. Evidence for mating included formation of stable prototrophs from strains with complementing auxotrophic markers; these contained both MTL alleles and molecular markers from both parents and were tetraploid in DNA content and mononucleate.     

抗鸡念珠菌卵黄抗体的研制及应用

本试验以龙岩某肉鸡场发病鸡嗉囔中分离得到的念珠菌作为免疫抗原,免疫25周龄产蛋鸡.经效力检验合格后,试制成抗鸡念珠菌卵黄抗体液.抑菌活性试验表明:效价为5 log2以上的高免卵黄表现出明显的抑菌活性,完全抑制了念珠菌的生长和繁殖.用抗鸡念珠菌卵黄抗体液分别喂服20日龄肉鸡和100日龄孔雀.结果表明:试验组鸡群嗉囔和咽喉念珠菌检出率较对照组显著降低(P<0.05);平均日采食量和日增重较对照组分别提高了80%和400%,死亡率则下降了7%.对孔雀的治疗效果与常规药物CuSO4相当.     

五倍子鞣质对生物被膜型白假丝酵母的干预作用

[目的]研究五倍子鞣质对生物被膜型白假丝酵母的抑制作用。[方法]在生物被膜形成的早期、中期和成熟期以不同浓度药物干预48 h,采用MTT法检测药物对膜型白假丝酵母的抑制率;以不同浓度药物干预成熟生物被膜24、48、72 h,再用MTT法检测抑制率;光镜直接观察生物被膜内白假丝酵母的形态结构变化;用吖啶橙/溴化乙锭染色,通过荧光显微镜观察生物被膜内白假丝酵母的死亡方式。[结果]五倍子鞣质对生物被膜的形成具有抑制作用,对成熟期生物被膜中白假丝酵母的抑制作用具时间和剂量依赖性;鞣质导致被膜内白假丝酵母细胞变形,形态结构改变,但未见确切细胞凋亡,同时抑制细胞芽管和假菌丝形成。[结论]五倍子鞣质对白假丝酵母生物被膜的形成及成熟期生物被膜中白假丝酵母均具较强的抑制作用;可能通过非凋亡途径导致被膜内白假丝酵母的死亡。     

Puromycin: effect on memory of mice when injected with various cations

Puromycin dihydrochloride neutralized with bases of potassium, lithium, calcium, or magnesium fails to block expression of memory of maze learning in mice, unlike puromycin neutralized with NaOH. This failure may be due to cationic binding at anionic membrane sites with a resultant exclusion of sufficient peptidyl-puromycin to make it ineffective in blocking memory.     

植物乳杆菌SD26的筛选及对白色念珠菌的抑菌作用

[目的]从泡菜中成功筛选分离出1株乳酸菌并对其抑制白色念珠菌进行初步研究.[方法]采用涂布平板法从四川大凉山农家泡菜中分离筛选出1株乳酸菌,经形态学观察、生理生化试验及16SRNA基因序列对其进行鉴定.测定该筛选菌株对白色念珠菌的抑菌活性大小、生长曲线影响、最小抑菌浓度和细胞形态作用,初步研究其抑菌机理.[结果]菌株SD26为植物乳杆菌(Lactobacillus plantarum),其对白色念珠菌的抑菌圈直径可达到26 mm,共培养能显著抑制白色念珠菌的生长.该植物乳杆菌SD26对活菌数为3.0 × 107 CFU/mL的白色念珠菌的最小抑菌活菌数为4.0×108 CFU/mL.电镜观察结果表明该植物乳杆菌SD26能破坏白色念珠菌细胞膜的完整性.[结论]从泡菜中筛选的乳酸菌为植物乳杆菌SD26,其对白色念珠菌的抑菌活性是通过破坏其细胞膜起作用.     

亚硒酸钠对小鼠的半数致死量测定

研究亚硒酸钠对小鼠的急性毒性作用和半数致死量(LD50)。给70只小鼠分别以2.77、4.3、6.67、10.3、16和24.8 mg.kg-1剂量的亚硒酸钠溶液一次性灌胃,对照组以相同剂量的蒸馏水灌胃,观察7d内小鼠的毒性反应和死亡情况,以改良寇氏法计算LD50,并观察毒性作用。结果表明,亚硒酸钠对小鼠的LD50为10.8 mg.kg-1,其95%可信限为9.0~13.0 mg.kg-1。进而说明,亚硒酸钠有一定的毒性,需要进行毒理学研究,临床应用时应考虑其安全用量。     

白假丝酵母脂肪酶CaLIP5在毕赤酵母X33中的优化重组表达

[目的]研究新的脂肪酶及优化脂肪酶发酵培养条件。[方法]在毕赤酵母X33系统中重组表达白假丝酵母脂肪酶CaLIP5。利用响应面分析法,构建了CaLIP5的酶活回归方程。[结果]由响应面分析可知,在温度25．71oC,pH8．33,酵母提取物浓度1．28％和葡萄糖浓度4．06％时,预测最大酶活为8．33U／ml。试验验证酶活为9．24U／ml。实际试验值与模型预测值基本一致。优化后的酶活提高了22．22％。[结论]在优化的培养条件下,可以获得毕赤酵母X33重组表达CaLIP5的最大酶活。     

广西红树林海洋微生物的分离及抗白色念珠菌的快速筛选

利用一种基于96孔板的快速筛选抗白色念珠菌活性的美蓝—酶标仪检测法对从广西山口、防城、北海三个地点红树林分离的498株细菌,299株真菌进行活性检测。结果表明,157株细菌具有抗白色念珠菌活性,占总分离细菌数的31.5%,88株真菌具有抗白色念珠菌活性,占总分离真菌数的29.4%。且抗白色念珠菌活性菌株的比例与样品来源密切相关。