Construction of a System for the Stable Expression of Foreign Genes in Dunaliella salina

A stable transformation system for the expression of foreign genes in the unicellular greenmarine alga (Dunaliella salina Teod.) was established. Using electroporation, the alga was transformed witha plasmid containing the hepatitis B surface antigen (HBsAg） gene and the chloramphenicol acetyltransferase(CAT) gene as a selectable gene. PCR and Southern blotting analysis indicated that the HBsAEgene wasintegrated into the D. salina genome. Northern dotting analysis showed that the HBsAg gene was expressedat the mRNA level. The stable expression of HBsAg protein in transformants was confirmed by HBsAgenzyme-linked immunosorbent assay (HBsAg EUSA) and Western blotting analysis. Also, PCR and Southernblotting analyses showed that the CA Tgene was integrated into the D, salina genome, and CAT EUSAindicated that CAT protein was stably expressed in the cells. The introduced HBsAg DNA and HBsAgprotein expression were stably maintained for at least 60 generations in media devoid of chloramphenicol.This is the first report of the stable expression of foreign genes in D. salina.

胆道梗阻合并胆道感染的病原学特征和危险因素及与肝脏损伤的关系研究

目的:探讨胆道梗阻合并胆道感染的病原学特征和危险因素,并分析胆道感染与肝脏损伤的关系。方法:回顾性分析250例胆道梗阻患者的临床资料,分析胆道梗阻合并胆道感染的病原菌分布和主要病原菌的耐药性,分析胆道梗阻合并胆道感染的危险因素,比较各组的肝功能指标[天冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、谷氨酰转移酶(GGT)、直接胆红素(DBIL)]和肝纤维化指标[层黏蛋白(LN)、透明质酸(HA)、Ⅲ型前胶原(PCⅢ)、Ⅳ型胶原(Ⅳ-C)]。结果:250例胆道梗阻中共有132例合并胆道感染,感染率为52.80%,共分离出病原菌150株,以革兰阴性菌和革兰阳性菌为主。粪肠球菌对红霉素的耐药率最高,屎肠球菌对林可霉素的耐药率最高,均对万古霉素的耐药率最低;大肠埃希菌和肺炎克雷伯菌均对氨苄西林的耐药率最高,对妥布霉素的耐药率最低。年龄≥60岁、有胆道手术史、肝功能Child-Pugh评分≥11分是胆道梗阻合并胆道感染的危险因素(P<0.05)。胆道感染组的AST、ALT、GGT、DBIL、LN、HA、PCⅢ、Ⅳ-C水平高于无胆道感染组和对照组,且无胆道感染组高于对照组(P<0.05)。结论:胆道梗阻患者胆道感染的发生率较高,并且胆道感染会进一步加重胆道梗阻患者的肝脏损伤,临床应根据其病原学特征和危险因素做好相应的防治工作。