三相流化床L-乳酸发酵及与离子交换分离耦合

L—乳酸因其能被人体代谢而将在食品、医药工业中代替DL—乳酸。另外均聚和共聚L—乳酸在医学及生产可生物降解的包装材料、农膜等方面有巨大的潜在市场。L—乳酸一般采用米根霉     

人参培养细胞单细胞克隆的条件培养

来自细胞悬浮培养物的条件培养基能显著地促进人参培养细胞的单细胞在较低细胞植板密度培养时的克隆形成。每毫升含3×10³个细胞时,条件培养的植板率是普通平板培养的4倍。细胞悬浮培养12－16天时所制备的条件培养基活性最大,在一定浓度范围内随条件培养基浓度增加。细胞克隆植板率随之增加。条件培养基具有一定的生理作用专一性。看护培养和条件培养的比较,表明前者在细胞密度较低时能更有效地促进细胞克隆的形成和生长。条件培养基在4℃条件下贮存两周仍保持活性稳定,并且能耐受高温处理。当受到强酸或强碱处理其活性失去．但在弱酸或弱碱条件下稳定。     

Ethanol fermentation coupled with complete cell recycle pervaporation system: Dependence of glucose concentration

Summary A membrane bioreactor system comprised of a fermenter and a flat pervaporation module was developed for continuous ethanol fermentation by Saccharomyces cerevisiae. In order to obtain the guidelines for high sugar concentration fermentation, the dependence of glucose concentration on the coupled system was investigated. Fed by 158 and 290g glucose/l, the improvement in productivity was obtained with 1. 58 and 1. 86 times, and the ethanol yield was 0. 45 and 0. 395, respectively. With the fermentation proceeding, the permeate flux decreased but the selectivity kept unaltered.     

Colorado potato beetle resistant somatic hybrid potato plants produced via protoplast electrofusion

Leptines are natural glycoalkaloids found only in certain selections of the wild potato speciesSolanum chacoense. These rare glycoalkaloids have been identified to be phytochemical defensive agents against insect herbivores such as the Colorado potato beetle (CPB). In an attempt to introduce this CPB resistance into the cultivated potatoS. tuberosum, interspecific somatic hybrid plants were developed between a dihaploid ofS. tuberosum and a high leptine-producing germplasm selection ofS. chacoense. The somatic hybrid was fused using protoplast electrofusion and regeneration techniques. Selection of interspecies fusion cell lines was based on hybrid vigor in protoplast-callus (p-callus) growth, on shoot regeneration from p-calli, and on characteristic appearance of anthocyanin pigment. This selection system was highly efficient and 12 of 13 fully regenerated plants were identified as somatic interspecies hybrids, as determined by the analyses of morphologic biochemical, and isozyme markers. In vitro insect bioassays demonstrated that the hybrids averaged a threefold reduction in leaf consumption by the CPB when compared to cultivated potatoes.     

Rapid optimization of electroporation conditions for plant cells,protoplasts, and pollen

The optimization of electroporation conditions for maximal uptake of DNA during direct gene transfer experiments is critical to achieve high levels of gene expression in transformed plant cells. Two stains, trypan blue and fluorescein diacetate, have been applied to optimize electroporation conditions for three plant cell types, using different square wave and exponential wave electroporation devices. The different cell types included protoplasts from tobacco, a stable mixotrophic suspension cell culture from soybean with intact cell walls, and germinating pollen from alfalfa and tobacco. Successful electroporation of each of these cell types was obtained, even in the presence of an intact cell wall when conditions were optimized for the electroporation pulse. The optimal field strength for each of these cells differs, protoplasts having the lowest optimal pulse field strength, followed by suspension cells and finally germinating pollen requiring the strongest electroporation pulse. A rapid procedure is described for optimizing electroporation parameters using different types of cells from different plant sources.     

苏芸金杆菌广谱杀虫Tm13－14菌株晶体毒素及毒力特性

以新筛选的对鞘翅目、鳞翅目、双翅目均具毒性的Ｂ．ｔ．Ｔｍ１３－１４菌株为材料,用ＨＤ－１、３３７０－１为参考菌株,比较了伴孢晶体蛋白的多肽组成,以及经三种昆虫肠道酶降解产生的抗酶多肽组分。ＳＤＳ－ＰＡＧＥ分析表明：Ｔｍ１３－１４晶体蛋白含１３８ｋＤ、１３２ｋＤ主要成分和６５ｋＤ次要成分。其晶体分别由三种昆虫肠道酶消化产生绚毒性多肽,经生物测定,杀家蚕的毒性成分为６８．５ｋＤ、５９ｋＤ多肽;杀斜纹夜蛾毒性成分为７１ｋＤ,６７ｋＤ和５９．６ｋＤ多肽杀马铃薯瓢虫毒性成分为６９ｋＤ、６５ｋＤ多肽。它与ＨＤ－１、３３７０－１晶体均有明显差异。     

冬眠哺乳动物心血管机能特点

冬眠动物心血管系统适应于冬眠和激醒过程的特殊生理条件形成了其显著的机能稳定性。我们在总结已有研究的基础提出了冬眠动物心血管系统具有耐低体温,抗主律失常,耐缺氧三大机能特点。这些特点不仅是冬眠动物五非冬眠动物的区别,也是冬眠动物在冬眠季机能强化的方面。     

甲基单胞菌Methylomonas sp.GYJ3中甲烷单加氧酶还原酶组分的纯化和性质

Ｍｅｔｙｌｏｍｏｎａｓｓｐ．ＧＹＪ３菌的甲烷单加氧酶（ＭＭＯ）粗酶提取液经ＤＥＡＥ－ＳｅｐｈａｒｏｓｅＣＬ－６Ｂ阴离子交换层析、ＳｅｐｈａｄｅｘＧ－１００凝胶过滤层析和ＤＥＡＥ－ＴＳＫｇｅｌＨＰＬＣ分离纯化出ＭＭＯ还原酶组分．经ＨＰＬＣ分析,纯度大于９５％,纯化倍数为４．４,加入至ＭＭＯ羟基化酶和调节蛋白Ｂ的体系中表现比活为２２８ｎｍｏｌ环氧丙烷每分钟毫克蛋白．ＳＤＳ－ＰＡＧＥ电泳表明还原酶由一种亚基组成,分子量４２ｋＤ．ＩＣＰ－ＡＥＳ测定还原酶的Ｆｅ含量为１．８３ｍｏｌＦｅ每ｍｏｌ蛋白．ＵＶ－Ｖｉｓ光谱表明还原酶除２８０ｎｍ蛋白质特征峰外在４６０ｎｍ有最大吸收峰,且Ａ２８０ｎｍ／Ａ４６０ｎｍ为２．５０,与其它黄素一铁硫蛋白相似,推测还原酶可能含一个ＦＡＤ辅基和Ｆｅ２Ｓ２中心．在厌氧条件下,还原酶能够和ＮＡＤＨ作用,ＵＶ－Ｖｉｓ光谱分析表明还原酶４６０ｎｍ处特征吸收峰消失,说明在ＭＭＯ催化过程中还原酶接受ＮＡＤＨ的电子．ＤＥＡＥ－ＳｅｐｈａｒｏｓｅＣＬ－６Ｂ阴离子交换层析分离出调节蛋白Ｂ,部分纯化的调节蛋白Ｂ的分子量大约在２０ｋＤ,它能够提高ＭＭＯ比活性４０倍,ＭＭＯ还原酶和调节蛋白Ｂ单独存在时不具有ＭＭＯ     

筛选转基因动物的新方法——PCR及其产物测序法

用特异性引物对肌球蛋白轻链2启动子(myosin light chain-2,MLC₂)-糜酶融合基因的转基因新生鼠鼠尾DNA进行PCR筛选, 低熔点琼脂糖凝胶电泳回收阳性样品PCR所扩出的DNA条带,纯化后用同一对引物中的一个进行单引物PCR测序,与所转外源基因序列比较,进一步确定整合有外源基因的阳性鼠.PCR及PCR 产物测序法检测转基因动物具有操作方便,灵敏度高及特异性强等优点.     

播种密度和基肥条件对晚籼稻旱育秧苗某些生理特性的影响

研究了1995年晚季不同播种密度和不同基肥对华南稻区晚籼稻旱育秧苗某些生理特性的影响。结果表明,在2种播种密度和5种基肥构成的10个处理中,秧苗叶龄、苗高和假茎宽等均无明显差异。在播种量为125g m-2条件下,虽然秧苗的总生长量较低,但其干/鲜重比值仍较播种密度为65gm-2略高;不同处理间的功能叶叶绿素含量(a b)、白根数/株和根活力呈显著差异,其中以沤熟有机肥和高无机肥用量作基肥的处理效果明显优于低无机肥用量作基肥的处理。因此,在进行旱育秧苗床培肥中,应注意以施用有机肥为主,适当补充无机肥,才能获得根系发达、活力强的健壮旱秧,为移栽后的叶蘖早发打基础。