Hydration of macromolecules

Frozen protein and nucleic acid solutions at -35 degrees C show relatively narrow (100 milligauss) proton nuclear magnetic resonance signals which are assignable to water that is sufficiently mobile to reduce the dipolar broadening normally associated with solids. Hydration was found to be 0.3 to 0.5 gram of water per gram of protein. Nucleic acids are three to five times as hydrated as proteins. Conformational changes in solution produce detectable changes in linewidth or amount of "bound" water, or both. The very fact that the water signals can be observed by high resolution nuclear magnetic resonance suggests that it is not "ice-like" in any literal sense, although it is clearly less mobile than liquid water at the same temperature. A simple model is described which considers both surface hydration and trapped water.     

几种鸡新城疫油佐剂灭活疫苗免疫效果的比较

比较研究了鸡新城疫(ND)二价灭活苗、ND灭活苗、进口ND灭活苗、ND强毒(CNDV)灭活苗和ND克隆-30弱毒苗的免疫效果。结果表明,不同ND疫苗首次免疫鸡所产生的抗体有差异,ND二价灭活苗免疫鸡的抗体上升最快,免疫后20 d左右可达到最高峰。1日龄免疫,14日龄攻毒,ND二价灭活苗、ND灭活苗的保护率分别为5/5,4/5;10日龄和10日龄以上免疫,免疫后7 d或7 d以上攻毒,ND二价灭活苗、ND灭活苗、进口ND苗的保护率分别为4/5~5/5,2/5~5/5,0/5~2/5。攻毒后ND二价灭活苗、进口ND灭活苗免疫的与对照鸡的肛棉拭子NDV阳性数分别为0/5,5/5,5/5。结果表明,ND二价灭活苗免疫效果优于进口ND灭活苗、ND强毒灭活苗,稍优于ND灭活苗。     

Epinephrine: effect on uptake of iodine by dispersed cells of calf thyroid gland

In isolated thyroid cells I-epinephrine (0.1 and 10.0 micrograms per milliliter), norepinephrine and isoproterenol consistently stimulated the accumulation and organic binding of iodine. The effect was partially inhibited by phentolamine, but not propranolol, and hence may be mediated by alpha receptors. Theophylline did not mimic or enhance the epinephrine effect, suggesting that the latter may not result from activation of adenyl cyclase.     

Plasma membranes of rat liver: isolation of lipoprotein macromolecules

Three high-denisity lipoprotein classes and one protein were separated from rat-liver plasma in membranes that had been treated with mild sonic oscillation. The lipoproteinis were separated and identified by techniques in which ultracentrifugation was used. Enzyme markers and electron-microscopic examination revealed membrane preparations essentially free of contaminating cellular partictulates.     

Circular dichroism of biological macromolecules

Circular dichroism, the unequal absorption of right and left circularly polarized light, is a manifestation of optical activity in the vicinity of absorption bands. To the experimental scientist interested in the conformation of macromolecules and in the sensitive response of optical activity to conformational alteration, it offers a relatively new and powerful means of understanding the environment of chromophoric residues. As a tool in the elucidation of electronic spectra, it should be useful to the theoretical scientist in identifying weakly allowed absorption bands as well as in providing rotational parameters which can be compared with the developing theory of optical activity. I have stressed application of circular dichroism, to experimental aspects of protein and nucleic acid conformation in solution. Much is still uncertain in particular quantitative details. However, even these early results shed new light and yield new information on the conformation of these molecules.     

DNA: a model compound for solution studies of macromolecules

Well-defined, monodisperse, homologous series of oligonucleotides and DNA restriction fragments may now be produced and used as models of rigid and semirigid rodlike molecules in solution. Information from optical experiments on these model systems aids in the formulation and testing of theories of macromolecular dynamics in both dilute and concentrated solution.     

Dielectrophoresis of macromolecules: determination of the diffusion constant of poly- -benzyl-L-glutamate

The translational diffusion constant of poly-gamma-benzyl-L-glutamate in ethylene dichloride was measured by dielectrophoresis. The method is rapid, precise to about +/- 5 percent, and yields values in good agreement with those obtained by standard methods.     

海泡石施加深度对水稻吸收镉的影响

为探讨海泡石施加深度对镉（Cd）污染土壤钝化修复效果的影响,选取湖南湘潭酸性水稻土,采用根际箱培养的方式,研究海泡石施加深度对土壤中Cd生物有效性、植株Cd吸收和根际环境的影响特征。结果表明,与未添加海泡石的对照相比,海泡石在施加深度为20、10 cm和5 cm的处理下,根际与非根际各层土壤pH值分别提高了1.00～1.16、0.59～1.21个单位,根际与非根际各层土壤中Cd有效态含量分别降低了0.02%～3.40%和1.00%～7.80%,且海泡石施加深度为5 cm(T2)时根际与非根际层土壤Cd有效态含量降幅最大,分别为3.40%和7.80%;海泡石不同施加深度处理水稻各部位Cd含量均有下降,且在施加深度5 cm并隔离根系向未钝化土壤延伸处理（T4）降幅最大,与对照相比根部Cd含量下降显著（P<0.05）,同时,海泡石在不同施加深度处理下水稻株高和产量均有提高,且与对照相比海泡石在T2和T4耕层深度处理下株高和产量显著提高（P<0.05）。可见,浅耕（耕层5 cm处理）施用海泡石降低土壤Cd生物有效性效果最好,且降低了水稻中Cd含量,显著提高了水稻产量。     

Androgen accumulation andbinding to macromolecules in seminal vesicles: inhibition cyproterone

Cyproterone reduces the accumulation of testosterone and dihydrotestosterone in seminal vesicles 30 minutes after intravenous administration of tritiated testosterone to castrated rats. Testosterone, added in vitro, binds to macromolecules from the supernatant fraction of the seminal vesicle homogenates; this interaction is antagonized competitively by cyproterone. Cyproterone may diminish androgenic effects by competition for binding molecules.     

Passive immunization against cachectin/tumor necrosis factor protects mice from lethal effect of endotoxin

A highly specific polyclonal rabbit antiserum directed against murine cachectin/tumor necrosis factor (TNF) was prepared. When BALB/c mice were passively immunized with the antiserum or with purified immune globulin, they were protected against the lethal effect of the endotoxin lipopolysaccharide produced by Escherichia coli. The prophylactic effect was dose-dependent and was most effective when the antiserum was administered prior to the injection of the endotoxin. Antiserum to cachectin/TNF did not mitigate the febrile response of endotoxin-treated animals, and very high doses of endotoxin could overcome the protective effect. The median lethal dose of endotoxin in mice pretreated with 50 microliters of the specific antiserum was approximately 2.5 times greater the median lethal dose for controls given nonimmune serum. The data suggest that cachectin/TNF is one of the principal mediators of the lethal effect of endotoxin.     

Recombinant vaccinia virus: immunization against multiple pathogens

The coding sequences for the hepatitis B virus surface antigen, the herpes simplex virus glycoprotein D, and the influenza virus hemagglutinin were inserted into a single vaccinia virus genome. Rabbits inoculated intravenously or intradermally with this polyvalent vaccinia virus recombinant produced antibodies reactive to all three authentic foreign antigens. In addition, the feasibility of multiple rounds of vaccination with recombinant vaccinia virus was demonstrated.     

吸烟对口腔鳞状上皮细胞膜表面结构的影响

应用原子力显微镜(AFM)对无吸烟史的健康人、中度吸烟组、重度吸烟组、口腔鳞状上皮不典型增生组、口腔鳞状细胞癌组的口腔鳞状上皮细胞膜超微结构进行观察,并应用图像软件分析细胞膜表面的平均粗糙度、峰值、表面积差值,以探讨吸烟对口腔鳞状上皮细胞膜超微结构的影响机制,寻找预测口腔癌发生的早期检测指标.结果表明:随着吸烟指数的增加,细胞外形逐渐不规则,癌细胞异型性较大;细胞膜表面平均粗糙度、峰值、表面积差值呈增大趋势.证明吸烟影响口腔鳞状上皮细胞膜超微结构.     

Intestinal calcium transport: the role of sodium

The role of sodium in intestinal calcium transport was investigated in everted rat intestine. Ethacrynic acid, but not ouabain, inhibited calcium transport. However, ouabain did inhibit net water transport and, therefore, sodium transport, establishing the dissociation of the two transport processes. In addition to a magnesium-dependent adenosine triphosphatase (activated by sodium and potassium), a phosphatase dependent on sodium and calcium was localized to the lateral and basal membrane fractions of the mucosal cell. Activity of the latter phosphatase, similar to calcium transport in intact tissue, was inhibited by ethacrynic acid and not by ouabain. Sodium, therefore, may participate in the calcium transport process by activating an enzyme complex, dependent on adenosine triphosphate, that mediates calcium transport.     

禽流感灭活抗原与佐剂配合饮水免疫对鸭消化道抗体分泌细胞的影响

为探讨鸭源禽流感灭活抗原与佐剂配合饮水免疫雏鸭的效果,应用鸭源禽流感灭活抗原与复合黏膜免疫佐剂(CpG和/或葡萄糖)饮水免疫雏鸭,检测消化道(主要是咽和小肠)抗体分泌细胞的变化。首先分别从鸭的胆汁和血清中粗提免疫球蛋白A(IgA)和IgG,经纯化后制备了兔抗鸭IgA和IgG,然后应用免疫组化技术显示鸭消化道IgA和IgG分泌细胞。试验结果表明:用禽流感灭活抗原配合CpG和/或葡萄糖饮水免疫后3、5和7周,消化道黏膜局部IgA分泌细胞面积均显著或极显著增加(P<0.05或P<0.01),IgG分泌细胞(除首免后第3和7周小肠外)极显著升高(P<0.01)。而单独用禽流感灭活抗原和用葡萄糖配合禽流感灭活抗原饮水免疫对消化道局部免疫水平影响不大。结论:鸭源禽流感灭活抗原配合免疫佐剂饮水免疫能够提高雏鸭消化道局部免疫水平。     

Structures from anomalous diffraction of native biological macromolecules

Crystal structure analyses for biological macromolecules without known structural relatives entail solving the crystallographic phase problem. Typical de novo phase evaluations depend on incorporating heavier atoms than those found natively; most commonly, multi- or single-wavelength anomalous diffraction (MAD or SAD) experiments exploit selenomethionyl proteins. Here, we realize routine structure determination using intrinsic anomalous scattering from native macromolecules. We devised robust procedures for enhancing the signal-to-noise ratio in the slight anomalous scattering from generic native structures by combining data measured from multiple crystals at lower-than-usual x-ray energy. Using this multicrystal SAD method (5 to 13 equivalent crystals), we determined structures at modest resolution (2.8 to 2.3 angstroms) for native proteins varying in size (127 to 1148 unique residues) and number of sulfur sites (3 to 28). With no requirement for heavy-atom incorporation, such experiments provide an attractive alternative to selenomethionyl SAD experiments.     

Electrophoresis of flexible macromolecules: evidence for a new mode of transport in gels

Movement of macromolecules through low concentration agarose gels was investigated with linear poly(styrenesulfonate), linear DNA, star-shaped poly(styrenesulfonate), and circular DNA. Mobilities of weakly entangled flexible macromolecules were independent of molecular radius; within a homologous chemical sequence, electrophoretic separation at low field strengths depended solely on the degree of polymerization. These observations cannot be explained either by sieving or by reptation mechanisms; transport was apparently controlled by spatial variations of chain configurational entropy. Only when the chain was highly entangled did chain topology affect mobility. Evidence for entropically regulated transport clarifies how gel electrophoresis separates flexible macromolecules.     

五皮口服液对鸡痛风的防治效果

【目的】研究五皮口服液对鸡痛风的防治效果。【方法】将200只40日龄海兰蛋鸡随机分成A～H共8组,A组为健康对照组,B组为五皮口服液预防组（在饲喂高钙高蛋白饲料的同时在饮水中添加4 mL/L五皮口服液）,C～H组饲喂高钙高蛋白饲料制作鸡痛风模型,其中C组为模型对照组,D、E、F组分别为五皮口服液低、中、高剂量治疗组（在造模第36天时分别在饮水中添加2,4,8 mL/L五皮口服液）,G、H组分别为八正合剂、乌洛托品治疗组,分别在饮水中添加1 mL/L八正合剂和0.4 g/L乌洛托品。在试验过程中,每天进行临床检查,对死亡鸡只进行剖检,治疗组用药前1 d（记作第0天）和用药后第3,7天时,采血检测血清黄嘌呤氧化酶（XOD）、天门冬氨酸氨基转移酶（AST）、丙氨酸氨基转移酶（ALT）活性及尿酸（UA）、尿素（Ur）、肌酐（Cr）含量的变化。【结果】B组鸡在试验过程中未出现明显临床症状及病理变化,第35天时XOD、ALT活性及UA、Cr含量极显著低于C组（P＜0.01）,Ur含量显著低于C组（P＜0.05）,与A组相当（P＞0.05）。C～H组在造模1周后鸡只出现痛风临床症状,2周后临床症状及脏器尿酸盐沉积明显,第35天时血清UA含量达480 μmol/L以上的鸡有135只,痛风发病率93.1%。在鸡痛风造模成功后,五皮口服液治疗组用药第3天时鸡痛风症状明显减轻,D、E、F组UA含量极显著低于C组（P＜0.01）;D、F组Cr含量极显著低于C组（P＜0.01）,与A组相当（P＞0.05）;F组AST及E、F组ALT极显著低于C组（P＜0.01）,D组ALT显著低于C组（P＜0.05）,与A组相当（P＞0.05）。治疗第7天时,E组XOD显著低于C组（P＜0.05）,与A组相当（P＞0.05）;D、E、F组UA含量极显著低于C组（P＜0.01）;F组Cr、Ur极显著低于C组（P＜0.01）,D、E、F组与A组相当（P＞0.05）;D、F组ALT及AST显著低于C组（P＜0.05）,D、E、F组与A组相当（P＞0.05）。【结论】五皮口服液对鸡痛风有较好的防治效果。     

水培条件下Cd与乙酰甲胺磷在番茄植株体内迁移的互作影响

作为高毒杀虫剂甲胺磷的替代产品,乙酰甲胺磷的大量使用对农产品安全造成的影响一直备受关注。本研究以番茄植株为研究对象,在水培条件下,用含0.5 mg·L-1 Cd2+和1.0 mg·L-1乙酰甲胺磷的混合营养液直接作用于番茄植株的根部,通过测定营养液和番茄木质部液中Cd2+与乙酰甲胺磷随时间的浓度变化,研究Cd2+与乙酰甲胺磷在番茄植株中迁移的互作影响。研究发现,营养液中的Cd2+和乙酰甲胺磷均能被番茄根部吸收,经木质部向上迁移。Cd2+的存在抑制了番茄根系对营养液中乙酰甲胺磷的吸收与向上运输,而营养液中的乙酰甲胺磷能促进番茄根系对营养液中Cd2+的吸收转运。