氨对脑细胞胞浆游离钙含量的影响

目的与方法：采用Ｆｕｒａ－２／ＡＭ探针技术观察ＮＨ４Ｃｌ对离体急性分离之Ｗｉｓｔａｒ乳鼠大脑细胞胞头游离钙「Ｃａ＾２＋」ｉ含量的影响。结果：ＮＨ４＾＋浓度为２．５ｍｍｏｌ／Ｌ时脑细胞内「Ｃａ＾２＋」ｉ含量升高。在一定范围内,随着ＮＨ４＾＋浓度的加大,细胞内Ｃａ＾２＋持续升高。ＮＨ４＾＋的升钙作用主要被Ｎｉｃａｒｄｉｐｉｎｅ所阴断,其变化特征类以ＫＣｌ。结论：ＮＨ４＾＋主要通过影响电压依赖性钙离子通     

A COMPARATIVE STUDY OF SUPPORTS FOR THE SYNTHESIS OF OLIGONUCLEOTIDES WITHOUT USING AMMONIA

Abstract

A comparative study of the cleavage efficiency of succinyl, phthaloyl, oxalyl, 2-(2-nitrophenyl)ethyl, 9-fluorenylmethyl, and 2-nitrobenzyl supports in 0.5M DBU solutions is described. A decrease in cleavage efficiency is observed when small oligonucleotides containing thymidine are linked to the supports. In these conditions oxalyl supports gave the best yields followed by 2-(2-nitrophenyl)ethyl and 9-fluorenylmethyl supports.     

氨氮对软体动物生长的影响:以铜锈环棱螺为例

为探究氨氮对底栖动物的毒性效应,在位于湖北保安湖的近自然生态系统(单个水域面积约600 m²,水深约1.5 m)中开展了为期1年的模拟实验,分析了6个不同氨氮浓度[N25>N20>N15>N10>N5>N0(对照);0.2—33.7 mg/L]条件下,大型底栖动物(软体动物)群落特征的差异。结果表明:(1)实验系统中采集的软体动物主要为铜锈环棱螺(Bellamya aeruginosa);(2)从B. aeruginosa密度来看, N0、N5、N10和N15处理相差不大[28(0—85) ind./m²],均显著高于N20和N25处理[5(0—29) ind./m²](P<0.05);(3)从B. aeruginosa生物量来看,N0、N5、N10、N15和N20处理相差不大[40.0(0—85.5) g/m²],均显著高于N25处理[0.8(0—4.0) g/m²](P<0.05);(4)从B. aeruginosa壳长、壳宽和带壳...     

罗汉果果实维生素C含量变化研究

本文报道罗汉果不同品种、类型、产区、果实不同发育时期及不同成熟度等果实中维生素C含量测定结果,为提高罗汉果产品质量提供有效措施。     

西双版纳地区降雨和橡胶林内雨养分含量的初步研究

雨水于1981到1982年在3个地区收集,2种橡胶林内雨于1982年1月到1983年4月在景洪收集。分析结果表明:雨水中N、P、K、S、Ca、Mg的含量分别为17.3～19.9、0.22—0.50、11.0—15.2、9.2—27.6、3.0—18.9、6.7—12.3公斤/公顷·年;橡胶林内雨上述元素的含量分别为15.2—18.1、1.23—1.44、16.6—24.9、11.0—17.4、16.6—18.6、14.0—15.8公斤/公顷·年。降雨和橡胶林内雨的养分含量随一年中降雨量的变化而呈现明显的季节变化,一般雨季初最高,雨季次之,冬、早季最低,与本区橡胶树的生长节奏相一致。     

流域生态学研究内容的整体表述

流域,作为一个在自然地理方面有着频繁的物质、能量交换,普遍存在因果关系的特殊区域,其经济开发日益受到人们的重视。长江流域最大的特点是丰富的水资源。但水体常作为水透明的、异质的嵌块在景观地图上被描绘,而水体科学家不常借用景观生态学的工具和概念解释它们。因为淡水生态系统格局很难被看到（多一个水的介质、可视的格局也很短暂）,而且淡水是陆地海洋的“生境岛屿”（空间上断裂、功能上隔离）。也由于水生态系统的脆     

THE PENETRATION OF AMMONIA INTO FROG MUSCLE

1. A study was made of the electrolyte changes which occur when frog muscles are immersed in a Ringer solution with 1/5 of the Na replaced by NH₄Cl. Analyses were made in the solution and in the muscles for K and NH₃, and the muscles were also analyzed for Cl, HCO₃, and Na. Control muscles were immersed in normal Ringer''s solution and similarly analyzed. 2. The amount of ammonia taken up was about equal to the K and Na lost. There was also a small increase in chloride content. The bicarbonate content was the same in both experimental and control muscles, indicating no change in the muscle pH due to the NH₃ which penetrated. An increased loss of K due to the penetration of NH₃ was also demonstrated by the use of radioactive K. 3. After 5 hours, the concentration of ammonia per gram of muscle is about the same as the concentration in the solution. After 4 or 5 days, the concentration in the muscle is about 1.5 times that in the solution. The inside to outside NH₃ ratio is about equal to the corresponding H ion ratio, but is much less than the K ratio. 4. The rate of penetration of the NH₃ is increased by a rise of temperature, by stirring the solution, and by decrease in the concentration of Na, K, Ca, or Mg in the solution; it is decreased by increasing the size of the muscles or by killing them with chloroform or boiling. 5. Liver, smooth muscle, skin, and kidney, in a few experiments, behaved much like muscle except that there was a formation of urea in the case of liver. 6. The injection of NH₄Cl into anesthetized cats causes an increase in the level of K in the blood plasma.     

氨对脑星状胶质细胞形态结构的影响

本文就氨(氯化铵)对体外培养之星状胶质细胞形态结构的影响进行了初步探讨。结果表明,高氨环境下,胶质细胞首先出现空泡变性,之后胞浆内出现细小的嗜碱性颗粒,细胞之间的间隙随着氨浓度的增大及氨作用时间的延长不断增加,细胞的分支状或星状突起显得粗大、清晰。当氨浓度达10mmol/L、氨作用时间延长至72小时时,可见胶质细胞出现核浓缩及崩解坏死现象。观察结果提示:高氨环境下胶质细胞的损伤与修复同时或相继出现,由此其功能代谢也将发生相应变化,这些变化有可能与中枢神经系统在氨中毒时所出现的种种异常有关,其确切作用有待于今后深入研究。     

酸奶中乳酸菌含量的检测

目的检测酸奶发酵前后以及贮藏期间的乳酸菌活菌数及酸度变化,以对酸奶的质量进行控制.方法应用高层半固体琼脂试管法. 结果酸奶中乳酸菌含量极高,达2.65×1010个/ml以上,并随贮藏时间的延长而发生变化. 糖对酸奶的含菌量无明显影响.双菌酸奶比单菌酸奶含菌量高,常可达到倍增,pH值随发酵和贮藏进程而下降.结论高层半固体琼脂试管法操作简便、快速、准确、活菌检出率高.     

氨氮胁迫下凡纳滨对虾抗病力和副溶血弧菌噬菌体防病效果研究

在水体不同氨氮条件下,对对虾抗病力指标和副溶血弧菌噬菌体生物防治效果进行了研究。实验设置0．05mg／L（对照）、0．15mg／L低浓度组、0．75mg／L低浓度组、1．50mg／L中浓度组、3．00mg／L高浓度组5个氨氮的质量浓度作为胁迫组,计在此基础上加入副溶血弧菌设置感染组,加入副溶血弧菌和噬菌体设置噬菌体防治组。在胁迫组,低浓度氨氮使凡纳滨对虾Litopenaeus vannamei血清P0、ACP和SOD活力增强,但是在第14天时所有实验组对虾的THC、虮清PO、CAT、ACP、SOD活力均远低于对照组,差异显著（P〈0．05）。感染组对虾THC、血清PO、CAT、ACP、SOD活力受到显著影响,各实验组的对虾抗病力指标均低于相对应的胁迫组,差异显著（P〈0．05）。低浓度氨氮的噬菌体防治组各项指标与感染组比较差异显著（P〈0．05）,肝胰脏的副溶血弧菌计数的差异显著（P〈0．05）。在第14天时,低浓度氨氮防治组指标和感染组差异显著（P〈0．05）,和胁迫组相近。以上结果说明噬菌体防治弧菌病在水体低浓度氨氮条件下,有更好的效果。