Adenosine triphosphatase. Sensitive to DDT in synapses of rat brain

The insecticide DDT selectively inhibits the action of a Na(+), K(+), Mg(2+)-adenosine triphosphatase found in the nerve ending fraction of the rat brain. As judged by the concentrations of inhibitors that give 50 percent of enzyme inhibition, DDT was approximately 1000 times more toxic than its non-insecticidal analog, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene. The degrees of inhibition of this enzyme system by various toxic and nontoxic DDT analogs were closely related to a general toxicity in vivo of these compounds. Moreover, the extents of inhibition of this enzyme system by DDT were much higher at low temperatures, an indication of a causal relation between poisoning in vivo by DDT and the inhibition in vitro of the Na(+), K(+), Mg(2+)-adenosine triphosphatase system.     

DDT: interaction with nerve membrane conductance changes

The falling phase of action potentials of lobster giant axons is prolonged by DDT; finally a plateau phase is produced like cardiac action potentials. In axons poisoned with DDT, peak transient (sodium) currents associated with step depolarizations are turned off very slowly, and steady-state (potassium) currents are markedly suppressed. These two changes would cause the prolongation of action potentials and are considered the major ionic mechanisms of DDT action.     

Induced photolysis of DDT

Photolysis of mixtures of certain alkyl halides and aromatic amines produces dehalogenation of the halide. These reactions involve a photoinduced charge transfer from the amine to the halide. Photolysis of tritolylamine and carbon tetrachloride produces tritolylaminium chloride. Photolysis of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and diethylaniline at 3100 angstroms yields 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (DDE), 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD), p,p'-dichlorobenzophenone (DDCO), and hydrogen chloride. Photolysis of DDT does not occur unless an inducer which has a low ionization potential, such as diethylaniline, is present. The DDT-diethylaniline mixture is stable in the dark, and the induced photolysis is not affected by triplet quenchers.     

Does DDT inhibit carbonic anhydrase?

At a concentration of 50 to 100 micrograms per milliliter, p,p'-DDT (and p,p'-DDE) did not inhibit the rate of hydration or dehydration of carbon dioxide by carbonic anhydrase. At concentrations greater than 500 micrograms per milliliter, partial inhibition of the rate of dehydration of carbonic acid was observed, but this involved precipitation of drug in the reaction vessel. This degree of inhibition suggests that DDT may not inhibit carbonic anhydrase effectively at the usual concentrations found in tissue after exposure of organisms to DDT in the environment.     

不同环境因素对表皮葡萄球菌生物膜形成的影响

采用微量板半定量法研究影响表皮葡萄球菌生物膜形成的因素,同时模拟奶牛体内环境因素,如乳糖、酪蛋白和Ca2+等,探索不同理化因素对表皮葡萄球菌生物膜形成的影响,结果表明,检测的3种培养基中,胰蛋白胨大豆肉汤(Typtic Soy Broth,TSB)培养基最有利于表皮葡萄球菌的生长及其生物膜的形成,且最适质量分数为3%左右;在pH中性条件下,NaCl对表皮葡萄球菌生物膜的形成有明显抑制作用;当pH大于7时,表皮葡萄球菌生物膜形成能力明显减弱。在模拟奶牛体内环境因素中,一定质量分数的Ca2+(0.2%及以上)与高质量分数的乳糖(8%及以上)对生物膜形成有明显抑制作用,而外源添加酪蛋白对表皮葡萄球菌生物膜形成没有明显影响。     

NaCl胁迫下Cl~-和Na~+对大豆幼苗胁迫作用的比较

 以栽培大豆 (Glycinemax.L .Merrill)的幼苗为材料 ,比较研究了等渗的NaCl、Cl-和Na+ 对苗期大豆根和叶细胞膜透性、鲜重、株高及根冠比等的影响。试验结果表明 ,NaCl对大豆幼苗的胁迫作用主要是由Cl-引起的。在等渗的Cl-和Na+ 胁迫下 ,Cl-盐对大豆植株的株高、鲜重以及根系和叶片的胁迫程度都高于Na+ 。大豆耐盐性主要与Cl-在根部的积累、减少叶片中Cl-含量有关 ;而与根部对Na+ 的截留作用相关性不显著     

原子吸收分光光度法对果蔬型酸奶中Vc含量的测定

[目的]建立测定果蔬酸奶中还原型Vc与Vc总量的方法。[方法]用钨酸钠沉淀酸奶中的大分子,过滤得到Vc提取液。采用原子吸收法测定含铜量,间接测定Vc含量,即样液不经DDT还原直接测定还原型Vc;经DDT还原后测定Vc总量。[结果]还原型Vc的RSD为3.2%,平均回收率为96.8%;Vc总量的RSD为3.3%,平均回收率为96.5%。[结论]原子吸收分光光度法精密度高,准确度好,适合用于测定果蔬酸奶中Vc含量。     

NaCl和Na2SO4胁迫对蒲公英种子发芽及成苗的影响

以蒲公英种子为试材，在NaCl和Na2SO4盐溶液中发芽，幼苗在持续盐胁迫条件下成苗生长。结果表明，当浓度为3500mg／kg时，NaCl和Na2SO4分别严重抑制了蒲公英种子的发芽，达到极显著水平。NaCl对种子发芽率的抑制强于Na2SO4。蒲公英成苗胁迫试验中，NaCl，Na2SO4浓度分别为5000mg／kg时，严重影响蒲公英成苗率、幼苗根、茎的生长和鲜干重比值，对叶绿素含量影响不大。种子发芽期问适当浓度的NaCl和Na2SO4盐溶液胁迫有助于诱导蒲公英幼苗耐盐性的产生。     

聚乙烯醇和海藻酸钠联合固定化汉逊德巴利酵母产3-羟基丙酸的研究

采用微胶囊固定化技术,利用聚乙烯醇、海藻酸钠和氯化钙制备汉逊德巴利酵母微胶囊,探讨了聚乙烯醇、海藻酸钠、氯化钙的浓度对汉逊德巴利酵母微胶囊的制备工艺及其产3-羟基丙酸量的影响。结果表明,随着聚乙烯醇、海藻酸钠和氯化钙浓度的分别增加,3-羟基丙酸含量先增加后减少。聚乙烯醇最佳浓度为10.0%,此时3-羟基丙酸含量为(20.01±0.66)g/L;海藻酸钠为最佳浓度为1.0%,此时3-羟基丙酸含量为(18.71±0.54)g/L;氯化钙最佳浓度为2.1%,此时3-羟基丙酸含量为(18.37±0.45)g/L。聚乙烯醇和海藻酸钠联合固定汉逊德巴利酵母制备微胶囊最佳工艺为10.0%聚乙烯醇,1.0%海藻酸钠和2.1%氯化钙,在此条件下3-羟基丙酸含量为(21.53±1.12)g/L。     

氯化钠对分蘖葱头根尖细胞有丝分裂的影响及其致畸效应

以分蘖葱头根尖为试验材料,研究了氯化钠对分蘖葱头根尖的毒性效应。用不同浓度(0.05、0.1、0.2、0.3 mol/L)的氯化钠水溶液对分蘖葱头根尖细胞染毒12 h、24 h、48 h,观察分蘖葱头根尖细胞有丝分裂指数、微核率以及染色体畸变情况。结果表明:在试验剂量范围内,随着氯化钠水溶液浓度的升高,染毒时间增长,分蘖葱头根尖细胞的有丝分裂指数逐渐降低,染色体畸变率和微核率逐渐升高,并且均在氯化钠水溶液浓度为0.3 mol/L、染毒时间为48 h时达到最大值,说明氯化钠是一种胁迫因子。     

DDT: disrupted osmoregulatory events in the intestine of the eel Anguilla rostrata adapted to seawater

The drinking of seawater and absorption of water along with sodium across the intestinal epithelium are well-known osmoregulatory events in marine teleosts. The insecticide DDT impairs fluid absorption in intestinal sacs from eels adapted to seawater. Furthermore, this functional impairment has an enzymatic basis; DDT also inhibits the (Na(+) and K(+)) activated, Mg(2+)-dependent adenosine triphosphatase in homogenates of the intestinal mucosa. Thus, the extreme sensitivity of teleosts to organochlorine pollutants may involve the disruption of osmoregulatory transport mechanisms.     

钠和氯对生长蛋鸭生产性能和血液生化指标的影响

试验采用单因素随机区组设计的方法,选择28日龄蛋鸭150只,平均体重为(0.50±0.01)kg,随机均分成6个处理组,在玉米-豆粕型日粮中添加氯化钠分别为0.0%、0.16%、0.24%、0.32%、0.48%、0.96%组成6种试验日粮。每个处理5个重复,每个重复5只鸭,3层笼养。旨在通过钠和氯对生长蛋鸭生产性能和血液生化指标的影响来确定生长蛋鸭对钠和氯的需要量。结果表明,玉米-豆粕型日粮中不添加氯化钠会对蛋鸭的终重、日增重和饲料转变化率产生极显著影响(P<0.01),而氯化钠添加量过高,尤其是氯化钠添加量为0.96%时,生长蛋鸭的生产性能下降,其终重、日采食量和日增重与中间4个处理组有显著差异(P<0.05)。当饲粮中氯化钠含量为0.24%～0.32%时,蛋鸭的各项生产性能指标最佳,最有利于鸭的生长。各处理间T3、T4、皮质醇和总抗氧化能力均有先升高后降低的趋势,处理Ⅰ(添加0%氯化钠)T4、皮质醇和总抗氧化能力水平极显著低于其他处理(P<0.01)。各处理间血清总蛋白、白蛋白和肌酐无显著性差异(P>0.05),处理Ⅰ组的血清尿素氮和尿酸含量极显著高于其他处理组(P<0.01)。结论表明,在本试验笼养条件下,采用玉米豆粕型日粮(含钠0.037%、氯0.047%、钾0.71%),添加氯化钠0.24%,使其日粮钠和氯的含量分别为0.131%和0.193%,可满足5～11周龄生长鸭的需要。     

微孔草耐盐碱性的研究

微孔草种子萌发期和土培出苗期的耐盐碱性试验结果表明：微孔草种子对ＣＬ ／ＳＯ２ ４＝１（当量比）的混合盐、ＮａＣｌ单盐和Ｎａ２ＣＯ３单盐萌发的耐盐临界值分别为０８１％、０７８％和０２１％。３种类型的盐对种子萌发的抑制顺序为Ｎａ２ＣＯ３＞ＮａＣｌ＞ＣＬ ／ＳＯ２ ４＝１。种子出苗期对ＣＬ ／ＳＯ２ ４＝１混合盐适宜的盐渍度为０８２％，临界盐渍度为１４３％。     

褐藻酸钠提高番茄幼苗耐盐适应性研究

[目的]探索提高番茄耐盐适应性的条件。[方法]设置3种浓度氯化钠溶液培养番茄,同时配制0、0.5、1.0、2.0 g/L几种浓度的褐藻酸钠溶液,研究褐藻酸钠对番茄遭受氯化钠胁迫的缓解作用。[结果]不同浓度的氯化钠中添加0.5～2.0 g/L的褐藻酸钠均能明显缓解氯化钠对番茄的胁迫,并以浓度2.0 g/L的褐藻酸钠缓解效果较好。可增强番茄超氧化物歧化酶（SOD）活性,提高番茄种子的萌发率和幼苗的叶绿素含量,促进番茄根系和苗高的生长,使番茄对氯化钠胁迫的可适应性从3 g/L提高至10 g/L。[结论]褐藻酸钠可提高番茄幼苗耐盐适应性。     

钙钠离子对高粱和小麦乙烯释放的影响

本文阐述了钙、钠离子对小麦、高粱抗旱性不同的品种叶片与根乙烯释放的影响。钙和钠离子对小麦和高架根的乙烯释放有明显的抑制效应。钠离子胁迫下,小麦根乙烯释放量多于高粱根;钙离子胁迫下则以高粱根乙烯释放量为多。钙或钠离子胁迫下,高粱或小麦不抗旱品种根乙烯释放量多于抗早品种。就叶片乙烯释放而言,高粱乙烯释放量少于小麦。两离子对高粱抗旱品种叶片乙烯释有促进作用,对不抗旱品种影响甚微。小麦不抗旱品种叶片乙烯释放为钙钠处理所抑制。胁迫下两种作物抗旱品种叶片的乙烯释放量高于其不抗旱品种的。这些结果表明,植物的乙烯释放对盐分胁迫的反应随组织器官和基因型而异。     

Phosphate uptake in an obligately marine fungus: a specific requirement for sodium

Phosphate uptake in the obligately marine fungus Thraustochytrium roseum is maximally stimulated by sodium chloride in a range of concentrations (0.2 to 0.4 molar) similar to those commonly encountered in littoral habitats. The effectiveness of sodium chloride for phosphate transport extends beyond its osmotic function and can be attributed specifically to sodium. Increases in respiration in the presence of the salt can be ascribed primarily to an osmotic effect.     

白鲢腌制过程中鱼肉与盐卤成分的变化

以白鲢为材料,研究了不同腌制条件下鱼肉与盐卤成分的变化及其动力学特性。结果表明,腌制条件对鱼肉中氯化钠含量及盐卤中可溶性蛋白和氨基态氮含量变化有明显影响。随着盐水浓度的提高,鱼肉中氯化钠含量显著上升,盐卤中可溶蛋白和氨基态氮含量明显降低。降低腌制温度、缩短腌制时间、提高盐水浓度可降低鱼肉中氯化钠含量,控制肌肉中营养成分的析出。试验建立的扩散动力学方程可较好地描述腌制过程中氯化钠、可溶蛋白和氨基态氮含量的变化。     

青霉酸的化学脱毒效果试验

为探讨青霉酸最有效的化学脱毒方法,采用碳酸氢钠、次氯酸钠、氢氧化钠和氯化钠等化学脱毒睦青霉酸进行了去毒试验。结果表明,碳酸氢钠对青霉酸脱毒效果最好,次氯酸钠和氢氧化钠次之,而氯化钠对青霉酸的去毒效果不佳,用３．００％的碳酸氢钠处理青霉酸只需１ｄ,就能达到理想的去毒效果。     

4-己基间苯二酚复合防褐剂对马铃薯多酚氧化酶活力的影响

[目的]为4-己基间苯二酚(4-HR)在食品贮藏与加工中的应用提供理论性依据。[方法]应用二次正交旋转组合设计方法,分析了4-HR与氯化钠、柠檬酸、抗坏血酸的交互防褐作用。[结果]4-HR对抑制马铃薯PPO活性有极显著作用,其次为抗坏血酸、柠檬酸和氯化钠,氯化钠抑制作用不明显。各因子对马铃薯PPO活力抑制效果最佳的用量分别为:4-HR 0.019%、柠檬酸0.57%、抗坏血酸0.027%,而氯化钠的水平变化对多酚氧化酶活力几乎没有影响。[结论]4-HR对马铃薯多酚氧化酶活性具有显著的抑制作用,且柠檬酸和抗坏血酸与4-HR的交互作用明显。     

THE SPECIFICITY OF THE XANTHYDROLPYRIDINE REACTION FOR 2, 2 BIS (p-CHLOROPHENYL) 1,1,1 TRICHLOROETHANE (DDT)

The Stiff and Castillo colorimetric test for DDT was extended to eighteen analogues and derivatives of DDT. The absorption maxima and extinction coefficients of the colored reactions were also obtained. The test is not specific for DDT. Of the compounds tested, the reaction was given by those having the structure > CHCX(3) or > C=CX(2.).