啤酒酵母对杀假丝菌素抗性的遗传分析

杀假丝菌素(Candicidin)在0．8μ／ml的YEPG平板上能完全抑制呻酒酵母(Saechar-mycescerevisiae) H802-1B (a,lys2)及H802-5D(a,ade,ural)的生长。将H802-1B涂布在含有5—70μg／ml的抗生素平板上分离得到抗性突变体。第一次突变体的最高抗性水平是50μg／ml,从5—50μg／ml 抗生素平板上共获得39株自发突变株,第二次抗性突变株是将第一次突变体涂布在更高浓度(70—90μg／ml)的抗生素平板上分离到的。部分抗性突变株(70μg／ml和90μg／ml)与亲株H802-5D交配,测其分离子的抗性,所有杂合二倍体表现：抗性：敏感性为2：2分离现象。H1121-1A(a,lys2,CADR9)XH113-8A(a, ural,CADR30)的杂种抗性分离行为：PD(17个子囊),NPD(2个子囊)T(4个子囊)口遗传分析证明,实验用的抗性突变体有两个显性抗性基因CADHr30和CADR90．     

乳杆菌发酵上清对耐药白假丝酵母生物膜的作用

目的研究德氏乳杆菌(Lactobacillus delbrueckii,L.delbrueckii)和发酵乳杆菌(Lactobacillus fermentum,L.fermentum)发酵上清液对3株耐氟康唑白假丝酵母临床分离株CA3、CA6、CA8生物膜形成和分散的作用。方法通过MIC试验,确认3株白假丝酵母临床分离株对氟康唑耐药;用96孔板构建体外白假丝酵母生物膜;用棋盘法分别检测L.delbrueckii、L.fermentum发酵上清液与氟康唑联用对3株白假丝酵母的作用;用XTT法对生物膜形成量进行定量分析;检测L.delbrueckii、L.fermentum发酵上清液与氟康唑联用对白假丝酵母时间-生长曲线的影响;显微镜拍照检测L.delbrueckii、L.fermentum发酵上清液单独和氟康唑联用对白假丝酵母生物膜形态的影响;平板培养法检测L.fermentum发酵上清液对白假丝酵母黏附作用的影响。结果 CA3、CA6、CA8三株临床分离菌株对氟康唑耐药,MIC浓度均为8μg/mL。L.delbrueckii与L.fermentum发酵上清液与氟康唑联用对3株耐药型白假丝酵母的生物膜形成与分散均未表现出协同作用,且发酵上清液与氟康唑联用效果不如发酵上清液单独处理效果好,L.fermentum发酵上清液对生物膜的分散作用较L.delbrueckii发酵上清液强。L.fermentum发酵上清液抑制白假丝酵母的初始黏附。结论 L.delbrueckii、L.fermentum发酵上清液单独应用时均对耐氟康唑白假丝酵母生物膜的形成与分散有干预作用,与氟康唑联用时未表现出协同作用,抑制耐药白假丝酵母生物膜的作用可能与抑制菌丝形成和起始黏附有关。     

对多烯类药物耐药的1株黄曲霉临床株耐药性的初步研究

目的对1株分离自疑似侵袭性肺曲霉病患者肺泡灌洗液的黄曲霉进行常用抗真菌药物敏感性的测定,判断其药物敏感性。方法以形态学方法对该菌株进行菌种鉴定;然后按照美国临床和实验室标准研究所(CLSI)的丝状真菌抗真菌药物敏感性试验方案M38-A,测定常用抗真菌药物对该菌株的最低抑菌浓度、最低杀菌浓度;同时以E-test法测定该菌对两性霉素B和伊曲康唑的敏感性。结果微量液基稀释法显示,两性霉素B或制霉菌素对该菌的MIC值均为4μg/ml,MFC值均为16μg/ml;伊曲康唑的MIC值为0.5μg/ml,MFC值为2μg/ml;特比萘芬的MIC为0.03μg/ml,MFC为0.03μg/ml。E-test法结果显示,该菌对伊曲康唑敏感,对两性霉素B耐药。结论临床上可以分离到对多烯类抗真菌药物耐药的黄曲霉株,应该引起重视。     

十二碳二元酸的发酵研究

热带假丝酵母(Candidatropicalis)UH248菌株在单因子实验的基础上经过正交实验后,以正十二烷发酵生成十二碳二元酸的产酸量从817g/L提高到1082g/L。而其二元酸产品的纯度(>97%)满足工业生产的需要。吐温60010%、尿素012%、维生素B2150μg/L、青霉素150μ/mL、丙氨酸050%的浓度时也对十二碳二元酸产量有促进作用。用一株以UH248为母株诱变筛选的新的优良突变株HP12菌株,在最佳条件下,20m³罐中发酵151h,十二碳二元酸的平均产量达2021g/L。     

丝孢酵母高甲硫氨酸突变株的选育及营养调控

以丝孢酵母(Trichosporon Behr)ST851为原始菌株,经紫外线诱变,在含乙硫氨酸的双层平板上筛选到多株抗乙硫氨酸突变株。其中ST851-10株抗乙硫氨酸浓度达到350μg/ml,其菌体蛋白质含量由40.5％提高到44.3％,菌体甲硫氨酸含量由20.45mg/g-DCW增加到29.32mg/g-DCW。在以苹果渣为碳源、尿素为氮源、硫酸镁作硫源的最适培养条件下,固态发酵24h后,蛋白质和甲硫氨酸含量较原始菌株分别提高了15.8％和44.9％。培养基中C/N值低有利于甲硫氨酸的合成,C/N值高则适合于菌体生长。在苹果渣固态发酵过程中,适当补加氮源既有利于菌体生长和甲硫氨酸的合成,又可起到调节培养基pH值的作用。     

发酵生产十六烷二羧酸的研究

以热带假丝酵母(Candida tropicalis)T_25-14为出发菌株,经紫外线多次诱变,获得生产十六烷二羧酸(DC₁₆)能力比原株提高25％以上的4株突变株。其中UH-3-9突变株经多次复筛,产DC16能力都比T25-14,菌株提高50％以上。经摇瓶条件试验,不加其他生长碳源。只加15％(v／v)正十六烷(nCl6),发酵96h,DC16为48．2g/L,转化率41％,产品纯度95．9％。     

香叶挥发油成分分析及其对 小鼠白色假丝酵母菌阴道病的影响

目的 研究香叶挥发油对白色假丝酵母生物膜形成的影响。方法 水蒸气蒸馏法提取香叶挥发油,GC-MS分析其成分,测定其对白色假丝酵母的MIC、MBC,激光共聚焦显微镜下观察白色假丝酵母生物膜的形成,制备小鼠白色假丝酵母菌阴道病模型,观察香叶油治疗效果。结果 香叶挥发油提取率为1.83%,分析出22个成分,主要成分为5-甲基-2-异丙烯基环己酮、3,7-二甲基-2-辛烯-1-醇、(顺)香叶醇、异香叶醇、香叶醇和甲酸香茅酯,MIC值为0.3625%,MBC值为0.6250%,激光共聚焦结果显示不同浓度香叶油均可显著抑制白色假丝酵母生物膜形成,动物实验结果显示香叶油可抑制小鼠阴道炎症改变。结论 香叶油用于治疗白色假丝酵母引起的阴道炎机制可能与其影响细菌生物膜形成有关。     

棘白菌素对氟康唑耐药的念珠菌体外药物敏感性的研究

目的评价3种棘白菌素类药物（卡泊芬净、米卡芬净、阿尼多芬净）体外对氟康唑耐药念珠菌的药物敏感性。方法采用微量液体稀释法和琼脂稀释法测定最小抑制浓度（MIC）。结果微量液体稀释法：59株耐药白念珠菌3种药物MIC50均为0.06μg/mL,米卡芬净、阿尼多芬净的MIC范围均为0.015～0.125μg/mL,卡泊芬净为0.015～0.25μg/mL;8株耐药光滑念珠菌MIC值均为0.063μg/mL。琼脂稀释法：59株耐药白念珠菌和8株耐药光滑念珠菌3种药物MIC值均为0.063μg/mL。结论3种棘白菌素类药物可能具有治疗氟康唑耐药的念珠菌感染的临床价值。     

克鲁斯假丝酵母及其近似种的脉冲电泳核型分析

用钳位均匀电场脉冲电泳(CHEF)系统分析了克鲁斯假丝酵母(Candida krusei),郎比可假丝酵母(C. lambica)和粗状假丝酵母(C. valiad)的模式菌株的电泳核型,发现这三种表型相似的假丝酵母却具有互不相同的染色体DNA分子带型,为其分类学研究提供了可靠的鉴别依据。在常规分类学研究的基础上,测定了AS 2.75(原定种名为(C. incospicua),AS2.1182(原定种名为 C. lambica)和AS 2.1772(未定种)等三株假丝酵母的G+C含量和脉冲电泳核型。通过对已报道的C. inconspicu的G+C含量及上述三种假丝酵母模式菌株的脉冲电泳核型的比较分析证明,AS 2.75和AS 2.1772为粗状假丝酵母(C. valida),AS 2.1182为克鲁斯假丝酵母(C. krusei)。     

米卡芬净对分离自中国的念珠菌和曲霉临床株体外抑菌活性的研究

目的了解新型抗真菌药物米卡芬净(micafungin,MFG)对分离自中国的念珠菌和曲霉临床株的体外抑菌活性。方法参照CLSI(Clinical and Laboratory Standards Institute,以前为NCCLS)制定的M27-A2和M38-A方案测定86株念珠菌和35株曲霉的最低抑菌浓度(MIC)或最低有效浓度(MEC)。结果MFG对大多数念珠菌属和曲霉属均有较好的抑菌作用。对念珠菌属的MIC90从高到低依次为:氟康唑(FLC)敏感的白念珠菌、热带念珠菌、光滑念珠菌为0.125μg/ml,FLC耐药和剂量依赖敏感株为0.25μg/ml,克柔念珠菌为0.5μg/ml,近平滑念珠菌8μg/ml,季也蒙念珠菌>16μg/ml。MFG对烟曲霉的MEC90为≤0.03μg/ml,对非烟曲霉的曲霉属MEC90为0.06μg/ml。MFG与唑类药物、两性霉素B(AMB)不存在交叉耐药,对FLC耐药的念珠菌、伊曲康唑耐药的曲霉、AMB不敏感的曲霉均有好的抑菌活性。结论MFG对多数念珠菌属和曲霉属(包括对唑类耐药和AMB不敏感的菌株)有较好的体外抑菌作用。     

A Unique Protease Cleavage Site Predicted in the Spike Protein of the Novel Pneumonia Coronavirus (2019-nCoV) Potentially Related to Viral Transmissibility

正Dear Editor,In December 2019, a novel human coronavirus caused an epidemic of severe pneumonia(Coronavirus Disease 2019,COVID-19) in Wuhan, Hubei, China(Wu et al. 2020; Zhu et al. 2020). So far, this virus has spread to all areas of China and even to other countries. The epidemic has caused 67,102 confirmed infections with 1526 fatal cases     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

The structure, reproduction and taxonomy of Vidalia and Osmundaria (Rhodophyta, Rhodomelaceae)

Comprises species occurring mostly in subtidal habitats in tropical, subtropical and warm-temperate areas of the world. An analysis of the type species, V. spiralis (Sonder) Lamouroux ex J. Agardh, a species from Australia, establishes basic characters for distinguishing species in the genus. These characters are (1) branching patterns of thalli, (2) flat blades that may be spiralled on their axis, (3) width of the blade, (4) primary or secondary derivation of sterile and fertile branchlets and (5) position of sterile and fertile branchlets on the thalli. Application of the latter two characters provides an important basic method for separation of species into three major groups. Osmundaria , a genus known only in southern Australia, was studied in relation to Vidalia , and its separation from the Vidalia assemblage is not accepted. Species of Vidalia therefore are transferred to the older genus name, Osmundaria. Two new species, Osmundaria papenfussii and Osmundaria oliveae are described from Natal. Confusion in the usage of the epithet, Vidalia fimbriala Brown ex Turner has been clarified, and Vidalia gregaria Falkenberg, described as an epiphyte on Osmundaria pro/ifera Lamouroux, is revealed to be young branches of the host, Osmundaria prolifera.     

New or rare chromosome counts in Artemisia L. (Asteraceae, Anthemideae) and related genera from Kazakhstan

Fifteen chromosome counts of six Artemisia taxa and one species of each of the genera Brachanthemum, Hippolytia, Kaschgaria, Lepidolopsis and Turaniphytum are reported from Kazakhstan. Three of them are new reports, two are not consistent with previous counts and the remainder are confirmations of very scarce (one to four) earlier records. All the populations studied have the same basic chromosome number, x = 9, with ploidy levels ranging from 2x to 6x. Some correlations between ploidy level, morphological characters and distribution are noted.     

肝癌中HBV和HCV基因和抗原的分布及意义

采用原位分子杂交方法检测HCV RNA及HBV X基因;采用免疫组织化学方法研究HCV核心抗原,非结构区C33c抗原及HBxAg在肝细胞肝癌中的定位及分布.结果表明(1)HCV RNA、HBV X基因在肝细胞肝癌组织检出率分别为40%(55/136)和82%(112/136).HCV RNA定位于癌细胞的胞浆内,阳性细胞呈散在、灶状及弥漫分布三种形式;HBV X基因在肝癌细胞中的分布呈胞浆型、核型及核浆型,阳性细胞也呈上述三种分布形式;(2)HCV C33c抗原、核心抗原在肝细胞肝癌中的阳性率为81%(133/164)及86%(141/164).C33c抗原定位于癌细胞及肝细胞的胞浆内;核心抗原既定位于癌细胞核中,又可定位于胞浆中.C33c抗原阳性细胞以灶状分布为主;而核心抗原阳性细