大肠杆菌葡萄糖异构酶基因在变铅青链霉菌中的克隆与表达

本文用穿梭质粒载体pSE-3,进行了大肠杆菌葡萄糖异构酶基因在变铅青链霉菌中的克隆与表达。把含有1.6kb葡萄糖异构酶基因的pX1200(4.3kb)质粒与pGEM-3(2.9kb)质粒分别用EcoRI酶解,T4DNA连接酶连接,转化E.Coli HB101(Xy1~-,Neo(?)),得到的重组质粒被命名为pX1203(7.2kb);将pX1203与穿梭质粒载体pSE-3分别用HindⅢ酶解,T_4DNA连接酶连接,转化E.Coli HB101,在含有新霉素的木糖培养基上筛选到转化重组体,其重组质粒被命名为pSE×100(10.6kb);把pSE×100转化变铅青链霉菌TK54的原生质体,在硫链丝菌肽(50μg/ml)和新霉素(50μg/ml)的平皿上得到了重组体。经质粒提取,酶切分析,再转化和葡萄糖异构酶活性测定,结果表明,大肠杆菌的葡萄糖异构酶基因确实已在链霉菌中克隆和表达。     

圈卷产色链霉菌分化相关基因——saw1的结构和功能

用双脱氧链终止法进行了分化基因——saw1的双链测序.结果表明在1500bp的DNA片段中有一个完整的开读框架(ORF),其编码区是在419bp至1252bp处.其产物与已知的天蓝色链霉菌whiG的氨基酸序列有89%的同源性.当把1500bp的saw1DNA片段插入到链霉菌表达质粒载体pIJ702后,构建的重组质粒转化天蓝色链霉菌孢子形成缺陷突变株C71,可使C71形成孢子和灰色色素.用基因破坏的策略进一步研究了该基因的生物学功能,结果表明saw1在圈卷产色链霉菌气生菌丝到孢子形成的发育转变中有重要作用,是分化中控制孢子发育起始的一个重要基因.     

玉蜀黍丝核菌的鉴定特征

在研究四川省玉米纹枯病菌系时,获得23个RhizoctoniazeaeVoorhees菌株。该菌菌丝形态与R.solaniKuhn相似;菌丝细胞含3个以上椭圆形细胞核;隔膜具桶孔,桶孔周围的隔膜肿体（septalswelling）与隔膜板垂直,两端不再膨大外延;菌丝生长较快,在PDA平板26℃下培养,每24小时菌落直径增长33．2～39．1mm;菌丝与苯酚相互作用后,着色较深,呈深褐色。菌核初期为白色或奶油色,成熟后为红褐色;常散生于基质内,少数着生在基质表面和培养皿的内壁上;球形或近球形,直径0.25～1．0mm;结构致密,无菌环和菌髓分化,表面较光滑。223个R.zeae菌株均与Oniki等建立的WaiteacircinataWAG－Z标准菌株发生融合,但与R.solani的融合群标准菌株均无融合反应。R.zeae对玉米的致病性较强,稍弱于玉米纹枯病主菌系R.solaniAG－1－IA,其病斑多半不连续,颜色较深,也可0侵染果穗引致穗腐并在苞叶上产生大量红褐至黑褐色的小菌核。     

旬河流域灌丛植被垂直分异规律的研究

植被的生趣分异是植被生态学的重要规律之一,根据旬河流域灌丛植被分的特点,首次提出该流域灌丛垂直带的划分：（１）亚高山凉温性常绿、落叶阔叶典型灌从带（２０００－２６００ｍ）;（２）中山温性落叶阔叶典型灌丛、杂木灌丛带     

Determination of d-saccharic acid-1,4-lactone from brewed kombucha broth by high-performance capillary electrophoresis

Kombucha is a health tonic. d-Saccharic acid-1,4-lactone (DSL), a component of kombucha, inhibits the activity of glucuronidase, an enzyme indirectly related with cancers. To date, there is no efficient method to determine the content of DSL in kombucha samples. In this paper, we report a rapid and simple method for the separation and determination of DSL in kombucha samples, using the high-performance capillary electrophoresis (HPCE) method with diode array detection (DAD). With optimized conditions, DSL can be separated in a 50 cm length capillary at a separation voltage of 20 kV in 40 mmol/L borax buffer (pH 6.5) containing 30 mmol/L SDS and 15% methanol (v/v). Quantitative evaluation of DSL was determined by ultraviolet absorption at λ = 190 nm. The relationship between the peak areas and the DSL concentrations, in a specified working range with linear response, was determined by first-order polynomial regression over the range 50–1500 μg/mL with a detection limit of 17.5 μg/mL. Our method demonstrated excellent reproducibility and accuracy with relative standard deviations (RSD) of less than 5% DSL content (n = 5). This is the first report to determine DSL by HPCE. We have successfully applied this method to determine DSL in kombucha samples in various fermented conditions.