油菜素内酯促进绿豆上胚轴伸长与蛋白质和核酸合成的关系

用饲喂蛋白质和核酸合成的放射性前体［３ Ｈ］－Ｐｈｅ、［３ Ｈ］－尿嘧啶和［３ Ｈ］－胸腺嘧啶证实了油菜素内酯（ＢＲ）能促进绿豆上胚轴的生长和蛋白质、ＲＮＡ 及ＤＮＡ 的合成。用蛋白质和核酸合成抑制剂（ＣＨ、Ａｃｔ．Ｄ、５－Ｆｕ）进一步探讨它们对上胚轴伸长的抑制作用与蛋白质、ＲＮＡ、ＤＮＡ 和ｍ ＲＮＡ 合成之间的关系。证明了上胚轴的伸长依赖于蛋白质和核酸的合成,尤其是依赖于ｍ ＲＮＡ 的合成。说明ＢＲ是在转录水平上调节基因的表达,进而促进上胚轴的伸长     

陕西省腹菌纲真菌的聚类分析

对产于陕西省的腹菌纲真菌,共４２个ＯＴＵ＇Ｓ和３６个性状,进行了Ｑ模式聚类分析,结果表明：（１）４２个ＯＴＵ＇Ｓ明显的分为六大类群,与Ｄｒｉｎｇ（１９７３）系统的６个目相吻合。（２）栓皮马勃属与灰包科中包被具拟薄壁层的属相似性较小,支持Ｈａｗｋｓｗｏｒｔｈｅｔａｌ（１９８３）将其作为科级处理的观点。（３）作者认为鬼笔属和竹荪属作为两个独立属处理比较合适。     

鲑鱼生长激素基因分泌型表达质粒的构建

生长激素(GH)是动物垂体前叶分泌的一种多肽类激素.应用分子重组及PCR等技术,构建了一种鲑鱼生长激素基因分泌型表达质粒pOsGH153,使编码鲑鱼生长激素成熟肽的序列克隆在大肠杆菌分泌型表达载体PIN-Ⅲ-ompA内,直接位于编码大肠杆菌外膜蛋白A信号肽序列的下游,在Lpp-Lac杂合启动子控制下,经IPTG诱导,分子量约23 000的鲑鱼生长激素在大肠杆菌中获得高效表达,该产物具有天然鲑鱼生长激素的免疫活性,直接分泌到细胞周质,而信号肽被自动剪除.     

Inhibition of mugineic acid-ferric complex uptake in barley by copper, zinc and cobalt

The interfering effects of copper, zinc, and cobalt on the uptake of mugineic acid-ferric complex were studied in barley ( Hordeum vulgare , cv. Minorimugi) grown in nutrient solution. Short-term uptake experiments of 3 h were performed utilizing both ionic and mugineic acid-complex forms of each metal at two different concentrations. Copper was most effective in decreasing iron uptake when added in an ionic form at either concentration. The inhibition order at higher concentrations followed Cu(II) > Zn(II) ≥ Co(II), Co(III), which is consistent with the stability constants of these metal complexes with mugineic acid. The displacement of iron from its mugineic acid complex by these metals is suggested as a probable explanation for the decreased iron uptake. The inhibitory effect of metal complexes with mugineic acid on iron uptake was only found in cases with higher concentrations of Cu(II) and Zn(II) complexes. Deformation of the specific iron transport system in the plasma membrane due to their adsorption may be responsible for this effect.     

Kinase requirement for retinal growth cone motility

Since cytoplasmic Ca²⁺ levels are reported to regulate neurite elongation, we tested whether calcium-activated kinases might be necessary for growth cone motility and neurite elongation in explant cultures of goldfish retina. Kinase inhibitors and activators were locally applied by micropipette to retinal growth cones and the responses were observed via phase-contrast videomicroscopy. In some cases, growth rates were also quantifed over several hours after general application in the medium. The selective inhibitors of protein kinase C, calphostin C (0.1–1 μM) and chelerythrin (up to 50 μM), caused no obvious changes in growth cones or neurite elongation, and activators of PKC (phorbols, arachidonic acid, and diacylglycerol) also were generally without effects, although phorbols slowed the growth rate. Inhibitors of protein kinase A and tyrosine kinases also produced no obvious effects. The calmodulin antagonists, calmidazolium (0.1 μM), trifluoperazine (100 μM), and CGS9343B (50 μM), however, caused a reversible growth cone arrest with loss of filopodia and lamellipodia. The growth cone became a club-shaped swelling which sometimes moved a short distance back the shaft, leaving evacuated filaments at points of strong filopodial attachments. A similar reversible growth cone arrest occurred with the general kinase inhibitors: H7 at 200 but not at 100 μM, and staurosporine at 100 but not 10 nM, suggesting possible involvement of a calmodulin-dependent kinase (camK) rather than PKC. The selective inhibitor of camKII, KN-62 (tested up to 50 μM), produced no effects but the specific myosin light-chain kinase (MLCK) inhibitors ML-7 (3–5 μM) and ML-9 (5–10 μM) reversibly reproduced the effect, suggesting that MLCK rather than camKII is necessary for growth cone motility. The MLCK inhibitors' effects both on growth cone morphology and on F-actin filaments (rhodamine-phalloidin staining) were similar to those caused by cytochalasin D (5 μM), and are discussed in light of findings that inhibiting MLCK disrupts actin filaments in astrocytes and fibroblasts. 1994 John Wiley & Sons, Inc.     

RGDS肽对大鼠主动脉球囊内膜剥脱后血管壁增殖的影响

在大鼠主动脉球囊内膜剥脱术后血管壁细胞过度增殖模型上,用合成的血小板膜纤维蛋白原受体（ｇｌｙｃｏｐｒｏｔｅｉｎⅡｂ／Ⅲａｃｏｍｐｌｅｘ,ＧＰⅡｂ／Ⅲａ）拮抗剂ＲＧＤＳ（Ａｒｇ－Ｇｌｙ－Ａｓｐ－Ｓｅｒ,５０μｍｏｌ·ｋｇ－１·ｄ－１）治疗可有效地抑制损伤血管壁的细胞计数增加和内膜增厚以及血管平滑肌细胞增殖,显著降低其血管组织３Ｈ－ＴｄＲ和３Ｈ－Ｌｅｕ的参入增加程度。实验结果提示ＲＧＤＳ肽作为血管成型术的辅佐剂,对于防治血管再狭窄可能具有潜在的临床应用前景。     

黑曲霉S4生淀粉糖化酶纯化组分的性质及其动力学常数

生淀粉糖化酶是可以水解生淀粉的葡萄糖糖化酶(Ec3.2.1.3,α-1.4-糖苷酶),它是近代工业中极为重要的酶类之一。虽然对生淀粉糖化酶可水解淀粉中所有的D-糖苷键已经清楚,由单糖逆合成寡糖的动力学研究也比较深入,但有关它对各种常用生淀粉材料的水解动力学以及各生淀粉糖化酶组分之间的相互关系的研究却很少。本研究通过在不同温度和pH下,生淀粉糖化酶的三个组分对寡糖和各种生淀粉作用的动力学常数,以及在不同pH值下它们对各生淀粉     

大熊猫消化道消化吸收区段游离面的扫描电镜观察

对大熊猫消化道的消化、吸收区段作扫描电镜观察后表明：（１）胃粘膜上皮细胞排列疏松,细胞表面具微绒毛,（２）十二指肠绒毛呈指状,表面凸凹不乎;绒毛表面具丰富的微绒毛,微绒毛表面粗糙,末端膨大。（３）直肠段具丰富的绒毛结构,表面不平滑,具颗粒状物质,但无微绒毛存在：直肠腺丰富。     

双裂解法提取血清HBV DNA技术的建立

为进行ＰＣＲ实验建立了一种两步裂解血清ＨＢＶ提取其ＤＮＡ的方法。该法首先用ＳＤＳ及蛋白酶消化裂解病毒,随后再进行碱裂解,操作较酚提取法大为简化,而ＰＣＲ实验进行的两法的灵敏性比较,说明双裂解法至少不低于酚法。     

岩豆凝集素的圆二色性与生物学活性关系的研究

岩豆凝集素（ＭＤＬ）的远紫外圆二色性谱（ＣＤ谱）显示２１６－２１７ｎｍ处的单一负峰。此时ＭＤＬ分子含有１６．２％的α螺旋,４６．３％的β折叠和３７．５％的无规卷曲。ｐＨ９．０时负峰红移至２２０ｎｍ,且在２１７－２２２ｎｍ处的峰值几乎相同;在２０－４０℃范围内,ＣＤ谱的变化甚微;６０℃时谱峰蓝移;在８０℃或１００℃时,２１２ｎｍ处出现一大负峰。１ｍｏｌ／Ｌ或２ｍｏｌ／Ｌ脲时,ＭＤＬ的ＣＤ谱已发生明显变化,二级结构单元也有变化,凝集兔红细胞的活性也随之减弱;随脲浓度的增加,ＭＤＬ的谱峰蓝移,最终在２１２ｎｍ处出现大负峰。当胍浓度为０．７５ｍｏｌ／Ｌ时,ＭＤＬ的ＣＤ谱即有明显变化和活性丧失;胍浓度继续增加,ＣＤ谱逐渐成为特征的无规卷曲的谱形。在ｐＨ９．０、温度超过８０℃、脲或胍浓度分别高于２ｍｏｌ／Ｌ和０．７５ｍｏｌ／Ｌ时,ＭＤＬ的ＣＤ谱发生显著变化的同时,其凝集兔红细胞的生物学活性全部丧失,分子的二级结构单元也发生很大改变。