海洋破囊壶菌Thraustochytrium sp. FJN-10 DHA生物合成 途径相关延长酶的克隆与表达

二十二碳六烯酸(Docosahexaenoic acid,DHA)是具有各种重要生理功能的高度不饱和脂肪酸.以海洋真菌Thraustochytrium sp.FJN-10为研究对象,利用RT-PCR结合RACE,获得了两个碳链延长酶(TFD6和TFD5)的完整基因,其中TFD6 cDNA全长816 bp,编码271个氨基酸;TFD5 cDNA全长831 bp,编码276个氨基酸.将TFD6、TFD5酶切后分别连接到HindⅢ/Xba Ⅰ处理过的pYES2载体,醋酸锂法转化酿酒酵母感受态细胞,成功构建了延长酶酵母表达系统.气相色谱分析表明TFD6可延长C18:3n-6至C20:3n-6,TFD5可延长C20:5n-3至C22:5n-3.     

我国部分地区自然发酵豆酱中的曲霉菌及其有性型

Twenty species of Aspergillus and their teleomorphs were isolated from naturally fermented soybean pastes collected in 42 regions of China. Of which A. tubingensis, A. flavus, A. niger, A. ochraceus, A. candidus and A. fumigatus were predominant. The high frequency of A. flavus from the samples indicates that the traditional making method of soybean paste might possibly be harmful to food safety. Some Aspergillus species or strains isolated from the traditional food samples may be hopeful of using in pure leaven making and industrial production of soybean paste with special flavor.     

Identification of a Putative Mexican Strain of Serratia entomophila Pathogenic against Root-Damaging Larvae of Scarabaeidae (Coleoptera)

The larvae of scarab beetles, known as “white grubs” and belonging to the genera Phyllophaga and Anomala (Coleoptera: Scarabaeidae), are regarded as soil-dwelling pests in Mexico. During a survey conducted to find pathogenic bacteria with the potential to control scarab larvae, a native Serratia sp. (strain Mor4.1) was isolated from a dead third-instar Phyllophaga blanchardi larva collected from a cornfield in Tres Marías, Morelos, Mexico. Oral bioassays using healthy P. blanchardi larvae fed with the Mor4.1 isolate showed that this strain was able to cause an antifeeding effect and a significant loss of weight. Mortality was observed for P. blanchardi, P. trichodes, and P. obsoleta in a multidose experiment. The Mor4.1 isolate also caused 100% mortality 24 h after intracoelomic inoculation of the larvae of P. blanchardi, P. ravida, Anomala donovani and the lepidopteran insect Manduca sexta. Oral and injection bioassays were performed with concentrated culture broths of the Mor4.1 isolate to search for disease symptoms and mortality caused by extracellular proteins. The results have shown that Mor4.1 broths produce significant antifeeding effects and mortality. Mor4.1 broths treated with proteinase K lost the ability to cause disease symptoms and mortality, in both the oral and the injection bioassays, suggesting the involvement of toxic proteins in the disease. The Mor4.1 isolate was identified as a putative Serratia entomophila Mor4.1 strain based on numerical taxonomy and phylogenetic analyses done with the 16S rRNA gene sequence. The potential of S. entomophila Mor4.1 and its toxins to be used in an integrated pest management program is discussed.     

Mild processing defect of porcine DeltaF508-CFTR suggests that DeltaF508 pigs may not develop cystic fibrosis disease

Recent efforts have made significant progress in generating transgenic pigs with the ΔF508-CFTR mutation to model the lung and pancreatic disease of human cystic fibrosis. However, species differences in the processing and function of human, pig and mouse ΔF508-CFTR reported recently raise concerns about the phenotypic consequence of the gene-targeted pig model. The purpose of the present study was to characterize the ΔF508 mutant of porcine CFTR to evaluate the severity of its processing defect. Biochemical and immunofluorescence analysis in transfected COS7 and FRT cells indicated that pig ΔF508-CFTR efficiently targets to the plasma membrane and is present mainly as the mature glycosylated protein. Functional characterization in stably transfected FRT cells by fluorometric and electrophysiological assays supported efficient plasma membrane targeting of pig ΔF508-CFTR. The mild cellular processing defect of pig ΔF508-CFTR suggests that its gene-targeted pig model may not develop the lung and pancreatic phenotypes seen in CF patients.     

Identification and characterization of Escherichia coli thioesterase III that functions in fatty acid beta-oxidation

When Escherichia coli is grown on oleic acid as the sole carbon source, most of this fatty acid is completely degraded by beta-oxidation. However, approximately 10% of the oleic acid is only partially degraded to 3,5- cis-tetradecadienoyl-CoA, which is hydrolyzed to 3,5- cis-tetradecadienoic acid and released into the growth medium. An investigation of thioesterases involved in this novel pathway of beta-oxidation led to the identification of a new thioesterase (thioesterase III) that is induced by growth of E. coli on oleic acid. This enzyme was partially purified and identified as the ybaW gene product by mass spectrometric analysis of tryptic peptides. The ybaW gene, which has a putative consensus sequence for binding the fatty acid degradation repressor, was cloned and expressed in E. coli. Thioesterase III was shown to be a long-chain acyl-CoA thioesterase that is most active with 3,5-tetradecadienoyl-CoA, a minor metabolite of oleate beta-oxidation. Its substrate specificity and induction by fatty acids agree with its proposed function in the thioesterase-dependent pathway of beta-oxidation. Thioesterase III is proposed to hydrolyze metabolites of beta-oxidation that are resistant to further degradation and that would inhibit the flux through the pathway if they were allowed to accumulate.     

中华眼镜蛇伤致局部组织损伤治疗的实验研究

目的 探讨中华眼镜蛇伤致局部组织损伤的最佳治疗方法。方法 用中华眼镜蛇毒作家兔局部组织损伤模型,分别采用抗蛇素血清局部注射、糜蛋白酶局部注射、蛇伤药酒外敷、坏死组织早期切除、局部烧灼法、局部组织切开冲洗,共6种处理方法进行局部治疗,观察其疗效。结果 6种治疗方法从优到劣依次是：抗蛇毒血清局部注射、糜蛋白酶局部注射、蛇伤药酒外敷、坏死组织早期切除、局部烧灼法、局部组织切开冲洗。结论 中华眼镜蛇伤致局部组织损伤的治疗方法应首选抗蛇毒血清局部注射和糜蛋白酶局部注射,其次选用蛇伤药酒外敷。     

一种新的肉苁蓉甙类化合物的分离方法

简单介绍了一种从肉苁蓉中提取得到肉苁蓉甙类化合物的方法,避免了乙酸乙酯和正丁醇的萃取,便于工业化应用,同时还可获得纯度较高有甜菜碱。     

人正常腺上皮组织中MUC6基因的表达

应用免疫组织化学和原位杂交方法检测人正常腺上皮中MUC6基因的表达,揭示MUC6基因在正常人腺上皮组织中的分布异质性及其特点.结果显示MUC6基因编码的核心蛋白及其mRNA主要分布于正常胃粘膜胃腺的基底部,上皮细胞无MUC6基因表达,呈细颗粒状,位于细胞核周,胃底、胃窦的表达无区别;十二指肠绒毛上皮内的表达呈弥漫性,均质状,杯状和柱状细胞的表达类似,杯状细胞的粘液滴内未测得MUC6基因产物;空肠、结肠组织中无MUC6基因的表达;胆囊上皮组织内有强阳性MUC6核心蛋白的表达,而宫颈上皮中表达较弱.实验提示MUC6基因的表达存在异质性及器官特异性.     

Bcl-2在去甲二氢愈创木酸诱导恶性胶质瘤细胞凋亡中的变化

观察bcl-2在去甲二氢愈创木酸（NDGA）诱导恶性胶质瘤细胞系SHG-44细胞凋亡中的变化。利用光镜和电镜观察及TUNEL法检测培养细胞凋亡的情况。用免疫组织化学,原位杂交和图像分析等方法检测bcl-2基因mRNA和蛋白的表达水平。结果显示：（1）一定浓度的NDGA处理SHG-44细胞12-96h,均可诱导SHG-44细胞发生凋亡,且随着作用时间的延长,凋亡细胞数增加越明显;（2）免疫组织化学方法结果显示,NDGA处理细胞后,出现SHG-44细胞bcl-2蛋白表达水平降低,且随着作用时间的延长,这种趋势更加明显,与细胞凋亡的发生密切相关;（3）原位杂交结果显示,NDGA处理细胞不同时间后,出现SHG-44细胞bcl-2基因mRNA的表达水平降低,结果与免疫组织化学方法检测结果一致,上述结果表明,NDGA诱导SHG-44细胞凋亡过程中,bcl-2基因的表达降低,但其确切机制有待进一步深入研究。