Isolation and identification of a marine killer yeast strain YF07b and cloning of the gene encoding killer toxin from the yeast

It was found that the marine yeast strain YF07b could secrete a large amount of killer toxin against a pathogenic yeast strain WCY which could cause milky disease in Portunus trituberculcttus. The marine yeast strain YF07b was identified to be Pichia anomala according to the results of routine yeast identification and 18S rDNA and ITS sequences. The gene encoding killer toxin in the marine yeast strain YF07b was amplified by PCR technology. After sequencing, the results show that an open reading frame, consisting of 1 281 bp, encoded a presumed protein of 427 amino acids. The sequence of the cloned gene was found to have 99% match with that of the gene encoding killer toxin in Pichia anomalas strain K. A signal peptide including 17 amino acids appeared in the N-terminal domain of the killer toxin. Therefore, the mature protein consisted of 410 amino acids, its molecular mass was estimated to be 47.4 ku and its isoelctronic point was 4.5.

酵母质粒Killer系统的研究

从酿酒酵母中筛选出两个具有线状双链RNA质粒的酵母菌株,提取并纯化了它的质粒RNA.用RNase和DNase处理,发现它们能被RNase消化,证明它们是质粒RNA.用电镜观察到它们呈线状,凝胶电泳图谱表明,这些质粒RNA都含有两条带;其分子量分别为3.0×10~6d和1.5×10~6d。

Occurrence and Diversity of Marine Yeasts in Antarctica Environments

A total of 28 yeast strains were obtained from the sea sediment of Antarctica.According to the results of routine identi-fication and molecular characterization,the strains belonged to species of Yarrowia lipolytica,Debaryomyces hansenii,Rhodotorula slooffiae,Rhodotorula mucilaginosa,Sporidiobolus salmonicolor,Aureobasidium pullulans,Mrakia frigida and Guehomyces pullu-lans,respectively.The Antarctica yeasts have wide potential applications in biotechnology,for some of them can produce b-galactosidase and killer toxins.

酵母菌杀菌系统的杀菌活性

探讨酵母菌杀菌系统（即３０株杀菌酵母菌）对３８株真菌或细菌的杀菌活性。结果显示杀菌酵母菌不仅对念珠菌、新型隐球菌和烟曲霉菌等真菌有杀菌活性，而且对其不相关的葡萄球菌、肠杆菌科、绿脓杆菌、不动杆菌和副溶血性弧菌也有杀菌活性，提示该系统具有广泛的杀菌活性，特别是Ｋ３６。

酵母菌杀菌系统用于白念珠菌分型

本文报道在国内首先建立了酵母菌杀菌系统用于白念珠菌(白念)的分型方法。对175株临床分离的白念分型,型别由3个数字组成的编码表示,175株被分为62个型,以编码511为最常见(占19.4％),分辨指数0.934。初步探讨了杀菌活性的机理,认为杀菌活性是杀菌哮母菌分泌的代谢产物的作用。该法具有简便、快速、结果易判定、重复性好和分辨率高等优点,易在医院实验室推广,且可与形态学分型法联合应用。

以酵母病毒杀伤系统为基础的抗病毒药物筛选模型

许多病毒利用程序性-1核糖体移码作为翻译调节机制进行繁殖。程序性酵母的病毒杀伤系统由L-A病毒和M1卫星病毒组成。M1病毒编码一种分泌型毒素K1,能杀死不含病毒的酵母细胞,但有自身免疫功能。L-A通过一定频率-1移码事件进行繁殖,-1移码效率的改变影响L-A病毒的存活,使M1数量快速下降。因此以程序性-1核糖体移码为靶位,建立以酵母病毒杀伤系统为基础的筛选模型,在抗病毒药物的高通量筛选方面有良好的应用前景。

BIK和SOCS3相互作用的筛选和鉴定

目的利用酵母双杂交技术筛选促凋亡因子BIK的相互作用蛋白。方法利用PCR在成人肝cDNA文库中扩增BIK全长ORF，构建pDBLeu—BIK载体。转化MaV203，检测细胞毒性和自激活作用，确定His基础表达的3AT浓度，依次转化成人肝cDNA文库。在营养缺陷型培养基上挑去三阳性克隆，进行回转验证，以及利用GST—pull down、CO—IP在体内外进行验证。结果成功构建pDBLeu—BIK载体，转化酵母细胞MaV203，无细胞毒性、无自激活作用，3AT浓度为25mmol／L。经回转实验、GST—pulldown、CO—IP证实了BIK和细胞因子信号通路抑制因子3（SOCS3）之间具有相互作用。结论BIK和SOCS3之间的相互作用可能是凋亡调控的新机制。