外消旋薄荷醇对映选择性酶促酯化中酸酐与羧酸的比较研究

利用脂肪酶在有机溶剂中催化对映选择性酯化反应对外消旋薄荷醇进行了有效的光学拆分。对分别使用酸酐和相应的游离羧酸作酰基给体时的反应性能进行了比较。发现酸酐的反应性远高于对应的游离羧酸,但在酶的催化作用下酸酐易水解成为游离羧酸;在微水系统中使用过高浓度的酸酐会导致酶缺水而失活,同时会促进手性醇的非选择性酯化,从而降低产物的光学纯度。然而,在连续流加丙酸酐的半批式反应系统中,所有这些缺点均可有效地克服。与使用游离丙酸的批式反应系统相比,ｄｌ-薄荷醇的反应时间缩短了一半,酶的稳定性大幅度提高,而产物ｌ薄荷醇酯的光学纯度不相上下（＞９８％ｅ）。     

干旱和湿润生境下辽东栎群体遗传结构及其适应意义的初步研究

应用同工酶分析方法,测定北京市东灵山区两个分别代表干旱和湿润生境的辽东栋（ＱｕｅｒｃｕｓｌｉａｏｔｕｎｇｅｎｓｉｓＫｏｉｚ．）群体的遗传结构。共分析统计了１３ 个酶系统３０ 个位点。结果表明：辽东栎群体内部存在丰富的遗传变异（多态位点百分率为８６．６％ ,等位基因平均数为２．２５）。两群体遗传结构的相似性程度很高（Ｄ＝ ０．０２９, ＧＳＴ＝ ０．０４８）;但在个别位点上仍存在较大差异,这些差异的产生可能与对小生境的适应有关。对不同年龄段的初步分析结果显示,基因频率的动态变化可能有其适应意义     

杨树新品种叶肉原生质体培养和植株再生

从１ 个月龄的ＮＬ－８０１０６ 杨（Ｐｏｐｕｌｕｓｄｅｌｔｏｉｄｅｓ×Ｐ． ｓｉｍ ｏｎｉｉ）无菌苗叶片分离得到大量原生质体,纯化后其原生质体产量为４×１０７／ｇ ｆｒ．ｗ ｔ． 纯化的原生质体在含２,４－Ｄ ２ ｍ ｇ／Ｌ、ＮＡＡ ０．５ ｍ ｇ／Ｌ和ＫＴ ０．５ ｍ ｇ／Ｌ的ＫＭ８ｐ 和ＭＳ培养基中进行高密度液体浅层培养,渗透势为０．４０ ｍ ｏｌ／Ｌ的ＫＭ８ｐ 培养基中原生质体分裂频率最高． 培养第５ 天观察到第一次细胞分裂,培养１０ ｄ 的分裂频率为４．５％ ,１２ 周内可形成大量的细胞团和小愈伤组织． ＮＬ－８０１０６杨叶肉原生质体在富含有机氮并以葡萄糖为碳源的培养基中具有较高的分裂频率和植板率．小愈伤组织在ｇｅｌｒｉｔｅ 固化的ＮＬＺ１ 培养基上增殖生长,３ 周后形成４—６ ｍ ｍ 结构紧密的鲜红色愈伤组织,转至ＮＬＦ分化培养基,分化成苗率为１００％ ． 待芽伸长到３ ｃｍ 时,从基部切下转至１／２ ＭＳ培养基上诱导生根,形成完整植株     

Ballistic transfection of avian primordial germ cellin ovo

In the fowl the primordial germ cells accumulate in the germinal crescent to the anterior of the two-day embryo. A simple ballistic device has been used to fire tungsten particles (mean diameter 1.5 m) into this region. By coating these projectiles with vector DNA it is possible to transfect these cells. Hatchlings produced by this technique were raised to sexual maturity and shown to contain the foreign DNA in their sperm. G₁ offspring containing this DNA were also produced in roughly 20% of these cockerels. In the majority of cases the vector DNA disappeared from the G₁ generation as they matured suggesting that in these cases it had been transmitted episomally.     

几种常用杀虫剂对蚜虫天敌——瓢虫的影响

作者等就11种常用杀虫剂对蚜虫的重要天敌——瓢虫进行了毒性测定,观察了它们对瓢虫的各个虫态的影响。 供试药剂 20％乐果乳剂、50％敌敌畏乳剂、50％对硫磷乳剂、50％内吸磷乳剂、25％三硫磷乳剂、50％杀螟硫磷乳剂、50％磷胺液剂、20％酚开普敦乳剂、6％丙体六六六乳剂、6％丙体六六六可湿性粉(W、P)、2.5％鱼籐精乳剂。 供试瓢虫 异色瓢虫Leis axyridis,室内饲养;龟纹瓢虫Propylaea japonica,田间采回。     

促甲状腺激素对甲状腺细胞胞内游离钙和钙调蛋白的影响

本文研究TSH和forskolin对原代培养的猪甲状腺细胞[Ca~(2+)]_i和钙调蛋白的影响。结果表明,TSH可引起甲状腺细胞[Ca~(2+)]_1急性升高。此反应是剂量依赖关系,而与细胞外钙的存在与否无关。其反应性在细胞单层高于细胞是液,近汇合细胞单层高于汇合细胞单层。TSH作用3天,可使甲状腺细胞的钙调蛋白含量增高,此作用与TSH对甲状腺细胞数的影响无关。Forskolin对甲状腺细胞的[Ca~(2+)]_i和钙调蛋白均无明显的影响。     

交联琼脂糖珠固定化蛋白酶在纯化牛肺Kunitz抑制剂中的应用

本文介绍了珠状交联琼脂糖及以此作为载体,经氯代环氧丙烷活化后与蛋白酶(胰蛋白酶或糜蛋白酶)结合,制成固定化蛋白酶亲和吸附剂,进而用以亲和层析牛肺提取液中的Kunitz抑制剂的方法。纯化出的抑制剂在SDS-聚丙烯酰胺凝胶电泳上呈现单一条带,与参照物Trasytol(商品Kunitz抑制剂)具有相对应的电泳迁移率,其分子量也相符。纯化产品每毫克蛋白的抑制活力相当于16 000胰蛋白酶BAEE单位。纯化效果为90倍,收率约85％。     

Membrane-microfilament interactions in ascites tumor cell microvilli. Identification and isolation of a large microfilament-associated membrane glycoprotein complex

[14C]Glucosamine metabolic labeling and concanavalin A blots were used to identify four major glycoprotein species associated with ascites tumor cell microvillar microfilament cores and with a transmembrane complex containing actin. Phalloidin shift analysis of glucosamine-labeled microvilli showed that glycoproteins of 110-120, 80, 65, and 55 kDa are stably associated with the microfilament cores. Analysis of large (greater than 10(6) kDa) transmembrane complexes from microvillar membranes made under microfilament-depolymerizing conditions (Carraway, C. A. C., Jung, G., and Carraway, K. L. (1983) Proc. Natl. Acad. Sci. U. S. A. 80, 430-434) revealed glycoproteins of the same Mr values, showing the same relative staining or labeling patterns as those observed with the microfilament cores. Gel filtration of high salt, high pH extracts of intact microvilli, microfilament cores, or transmembrane complexes showed that in all of these fractions the glycoproteins are associated in a very large, stable complex. The glycoprotein multimer was isolated essentially free of actin and other components by Sephacryl S-1000 chromatography of microvilli, microvillar membranes prepared at pH 11, microfilament cores, or transmembrane complex fractions in Triton X-100, 1 M KCl, glycine, pH 9.5. Purified glycoprotein complex bound actin when incubated under polymerizing conditions. The presence of the glycoprotein heteromultimer in both microfilament cores and transmembrane complex from isolated membranes and the association of the purified glycoprotein complex with actin are consistent with our hypothesis that the glycoprotein-containing transmembrane complex is an association site for microfilaments at the plasma membrane.     

Purification of cytochrome cd1 nitrite reductase from Pseudomonas stutzeri JM300 and reconstitution with native and synthetic heme d1.

Cytochrome cd1 nitrite reductase has been purified from Pseudomonas stutzeri strain JM 300. This enzyme appears to be a dimer with a subunit molecular mass of 54 kDa and its isoelectric point is determined to be 5.4. The N terminus of amino acid sequence has strong homology with that of nitrite reductase from P. aeruginosa. The apoprotein of this enzyme has been reconstituted with native and synthetic heme d1. The nitrite reductase activity measured by NO and N2O gas evolution can be restored to 82% of the activity of the original enzyme when the protein was reconstituted with the native heme d1 and to 77% of the activity when reconstituted with the synthetic heme d1. The absorption spectra of both reconstituted enzymes are essentially identical to that of the original nitrite reductase. These results further substantiate the novel dione structure of heme d1 as proposed. The loss of NO2- reducing activity in the absence of heme d1 and its restoration by addition of heme d1 provides further evidence that heme d1 plays a key role in the conversion of NO2- to NO and N2O.