Hydrogen sulfide removal by immobilized Thiobacillus novellas on SiO2 in a fluidized bed reactor

The removal of hydrogen sulfide (H2S) from aqueous media was investigated using Thiobacillus novellas cells immobilized on a SiO2 carrier (biosand). The optimal growth conditions for the bacterial strain were 30 degrees C and initial pH of 7.0. The main product of hydrogen sulfide oxidation by T. novellus was identified as the sulfate ion. A removal efficiency of 98% was maintained in the three-phase fluidized-bed reactor, whereas the efficiency was reduced to 90% for the two-phase fluidized-bed reactor and 68% for the two-phase reactor without cells. The maximum gas removal capacity for the system was 254 g H2S/m3/h when the inlet H2S loading was 300 g/m3/h (1,500 ppm). Stable operation of the immobilized reactor was possible for 20 days with the inlet H2S concentration held to 1,100 ppm. The fluidized bed bioreactor appeared to be an effective means for controlling hydrogen sulfide emissions.     

Construction of dextrin and isomaltose-assimilating brewer’s yeasts for production of low-carbohydrate beer

Most Saccharomyces spp. cannot degrade or ferment dextrin, which is the second most abundant carbohydrate in wort for commercial beer production. Dextrin-degrading brewer’s bottom and top yeasts expressing the glucoamylase gene (GAM1) from Debaryomyces occidentalis were developed to produce low-carbohydrate (calorie) beers. GAM1 was constitutively expressed in brewer’s yeasts using a rDNA-integration system that contained yeast CUP1 gene coding for copper resistance as a selective marker. The recombinants secreted active glucoamylase, displaying both α-1,4- and α-1,6-debranching activities, that degraded dextrin and isomaltose and consequently grew using them as sole carbon source. One of the recombinant strains expressing GAM1 hydrolyzed 96 % of 2 % (w/v) dextrin and 98 % of 2 % (w/v) isomaltose within 5 days of growth. Growth, substrate assimilation, and enzyme activity of these strains were characterized.     

Expression of a bifunctional fusion of the Escherichia coli genes for trehalose-6-phosphate synthase and trehalose-6-phosphate phosphatase in transgenic rice plants increases trehalose accumulation and abiotic stress tolerance without stunting growth

Trehalose plays an important role in stress tolerance in plants. Trehalose-producing, transgenic rice (Oryza sativa) plants were generated by the introduction of a gene encoding a bifunctional fusion (TPSP) of the trehalose-6-phosphate (T-6-P) synthase (TPS) and T-6-P phosphatase (TPP) of Escherichia coli, under the control of the maize (Zea mays) ubiquitin promoter (Ubi1). The high catalytic efficiency (Seo et al., 2000) of the fusion enzyme and the single-gene engineering strategy make this an attractive candidate for high-level production of trehalose; it has the added advantage of reducing the accumulation of potentially deleterious T-6-P. The trehalose levels in leaf and seed extracts from Ubi1::TPSP plants were increased up to 1.076 mg g fresh weight(-1). This level was 200-fold higher than that of transgenic tobacco (Nicotiana tabacum) plants transformed independently with either TPS or TPP expression cassettes. The carbohydrate profiles were significantly altered in the seeds, but not in the leaves, of Ubi1::TPSP plants. It has been reported that transgenic plants with E. coli TPS and/or TPP were severely stunted and root morphology was altered. Interestingly, our Ubi1::TPSP plants showed no growth inhibition or visible phenotypic alterations despite the high-level production of trehalose. Moreover, trehalose accumulation in Ubi1::TPSP plants resulted in increased tolerance to drought, salt, and cold, as shown by chlorophyll fluorescence and growth inhibition analyses. Thus, our results suggest that trehalose acts as a global protectant against abiotic stress, and that rice is more tolerant to trehalose synthesis than dicots.     

云南伊蚊属奈蚊亚属一新种及二新记录种记述

报道了云南省伊蚊属奈蚊亚属Aedes subgen. Kenknightia Reinert,1990至今所发现的种类,其中包括1新种类异形伊蚊Ae.（Ken.） dissmilierodes sp. Nov.和2种中国新记录,讨论了新种与近缘种的鉴别特征,简述了2种新记录的形态特征。新种模式标本保存于云南省疟疾防治研究所。     

CHO工程细胞株低血清培养的初探

以DMEM: F12(1: 1)为基础培养基,对CHO细胞的低血清培养进行了初步探索,降低培养基中血清含量,观察了细胞在10%、5%和1%等不同浓度低血清培养条件下生长状态和外源蛋白表达活性的变化.试验结果表明:在含1%血清的F12: DMEM(1: 1)培养基中,细胞仍能保持良好的生长状态,且培养上清中的目的蛋白活性与常规血清浓度10% DMEM培养条件下的活性接近.从而达到了既可以降低生产成本,又可以降低纯化难度的目的.     

Suppression of ceramide-induced cell death by hepatitis C virus core protein

The hepatitis C virus (HCV) core protein is believed to be one of viral proteins that are capable of preventing virus-infected cell death upon various stimuli. But, the effect of the HCV core protein on apoptosis that is induced by various stimuli is contradictory. We examined the possibility that the HCV core protein affects the ceramide-induced cell death in cells expressing the HCV core protein through the sphingomyelin pathway. Cell death that is induced by C(2)-ceramide and bacterial sphingomyelinase was analyzed in 293 cells that constitutively expressed the HCV core protein and compared with 293 cells that were stably transfected only with the expression vector. The HCV core protein inhibited the cell death that was induced by these reagents. The protective effects of the HCV core protein on ceramide-induced cell death were reflected by the reduced expression of p21(WAF1/Cip1/Sid1) and the sustained expression of the Bcl-2 protein in the HCV core-expressing cells with respect to the vector-transfected cells. These results suggest that the HCV core protein in 293 cells plays a role in the modulation of the apoptotic response that is induced by ceramide. Also, the ability of the HCV core protein to suppress apoptosis might have important implications in understanding the pathogenesis of the HCV infection.     

灰葡萄孢丝裂原活化蛋白激酶编码基因bmp1和bmp3的功能

【背景】植物病原真菌丝裂原活化蛋白激酶(Mitogen-activated protein kinase,MAPK)信号途径参与病菌有性生殖、细胞壁完整、菌丝侵染、致病力、胁迫响应等过程,灰葡萄孢MAPK信号途径参与病菌生长发育、致病力以及胁迫响应,但MAPK信号途径基因在灰葡萄孢中的功能尚未完全阐明,该信号途径对灰葡萄孢的生长发育和致病力的调控机制尚不明确。【目的】明确灰葡萄孢MAPK编码基因bmp1、bmp3在病菌生长发育、致病力以及氧化胁迫响应过程的功能,为进一步阐明MAPK信号途径调控灰葡萄孢生长发育和致病力的分子机制奠定基础。【方法】利用RNAi技术构建灰葡萄孢MAPK编码基因bmp1和bmp3的RNAi突变体,并以野生型BC22菌株为对照,对bmp1和bmp3基因的RNAi突变体的表型、致病力以及对氧化胁迫的敏感性进行分析。【结果】灰葡萄孢bmp1和bmp3基因的RNAi突变体其菌落形态、菌丝形态均与野生型BC22菌株没有明显差别;bmp1基因的RNAi突变体生长速率明显减慢,分生孢子产量明显降低;bmp3基因的RNAi突变体的生长速率与野生型BC22菌株没有明显差别,不能产生分生孢子。bmp1和bmp3基因的RNAi突变体在番茄果实的表面均不能产生明显的致病症状,而且不能穿透玻璃纸。bmp1基因的RNAi突变体在含有H_2O_2的培养基上受抑制的程度显著低于野生型,而在含甲萘醌的培养基上受抑制的程度显著高于野生型;bmp3基因的RNAi突变体在含有H_2O_2和甲萘醌的培养基受抑制的程度均显著高于野生型。【结论】灰葡萄孢bmp1基因正调控病菌生长、分生孢子形成、致病力和穿透能力,参与调控病菌对氧化胁迫的响应;灰葡萄孢bmp3基因正调控病菌分生孢子形成、致病力、穿透能力以及对氧化胁迫的响应。     

不同林龄桉树人工林林下物种多样性和生物量的动态变化

采用空间代替时间法和典型抽样法,以四川省威远县桉树(Eucalyptus robusta)人工林为研究对象,综合分析其林下植被物种组成及重要值、灌木层和草本层地上、地下和全株生物量以及物种多样性指数(Shannon-Wiener多样性指数H、Simpson优势度指数H′、丰富度指数D和Pielou均匀度指数JSW),探究林下植被的物种多样性和生物量在5个不同林龄(4,5,6,7,8年生)下的动态变化及二者之间的相关性。结果表明:调查到植物共有210种,隶属79科151属,草本层物种数多于灌木层。草本层的五节芒(Miscanthus floridulus)、芒萁(Dicranop?teris pedata)和灌木层的野牡丹(Melastoma malabathricum)、戟叶悬钩子(Rubus hastifolius)在不同林龄下都占据主要优势地位。随着林龄的增大,郁闭度加大,灌木层的D、H和H′值均表现为先增后减的规律;草本层D、H和H′值均呈先增后减再增再减的双峰趋势。草本层各生物量呈先增后减再增的变化趋势;灌木层各生物量呈先增后减的变化趋势。物种多样性与生物量呈显著正相关,草本层的D、H指数是影响生物量的直接因子。桉树人工林林下植被物种分布、组成、物种多样性和生物量对林龄变化的响应不同,表现为不同的动态特征规律,相关结果为我国西南地区桉树林管理提供了数据支撑。