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1.
Analogues of DDT (ethoxymethyl and methoxymethio derivatives) compared with DDT for their inhibitory action on the ATPase system from tissues of the cockroach, Periplaneta americana show similar, but less inhibitory effects. The mitochondrial (oligomycin-sensitive) Mg2+ ATPase activity from coxal muscle preparations was more sensitive to DDT than the two analogues; whereas, the muscle and nerve cord homogenates showed about equal sensitivity to the biodegradable analogues. The mitochondrial Mg2+ ATPase from nerve cord preparation was more sensitive to the three compounds than the Na+K+ ATPase activity. The significance of these results in relation to recent reports on the effect of DDT on Na+K+ ATPase is discussed.  相似文献   

2.
Oligomycin-sensitive (O-S) Mg2+ ATPase from American cockroach muscle was more sensitive to DDT, TDE, methoxychlor, and DDE at cool temperatures than at warm temperature, thus showing a negative temperature effect. In contrast, inhibition by acaricides dicofol, chlorfenethol, and Plictran shows a positive temperature effect. Oxidative phosphorylation in a mitochondrial preparation from cockroach coxal muscle was reduced by DDT, but the reduction was greater at a higher temperature (32°C) than at a cooler temperature (22°C). In addition, Na+K+ ATPase from cockroach nerve cord showed a positive temperature effect with DDT. The inhibition by DDT was much less on Na+K+ ATPase than on O-S Mg2+ ATPase. The negative temperature effect by DDT and analogs on O-S Mg2+ ATPase parallels toxicity effects on insects and fish as reported by numerous researchers. The results provide further evidence for this energy-regulating enzyme being a critical component in the biological action of DDT.  相似文献   

3.
A Ca-ATPase highly sensitive to DDT has been found in peripheral nerves of lobster, Homarus americanus. The observed I50 for this Ca-ATPase toward DDT is on the order of 10?9M and has a low temperature quotien. The ATPase seems to work over a wide range of ATP concentrations. It is stimulated by Ca2+ (optimum 0.1 mM) and shows sensitivity to Na+ (optimum 20 mM) and K+ (optimum 20 mM) ions. The fact that it is highly sensitive to ruthenium red (I50 = 10 μM) suggests that the enzyme is a Ca-ATPase and not a Mg-ATPase. Furthermore the enzyme is not a CaMg-ATPase, since the presence of Mg2+ along with Ca2+ ion is not required for its activity. DDT is found to inhibit the process of Ca2+ binding in the axonic membrane only in the presence of ATP. The evidence suggests the important role of the Ca-ATPase in regulating Ca2+ concentrations in the membrane. The possible significance of DDT inhibition of the ATPase is discussed.  相似文献   

4.
American cockroaches injected with sublethal doses of DDT (0.75 μg/roach) at 5-day intervals showed a 40% reduction in oligomycin-sensitive Mg2+ATPase from muscle homogenates, and a 23% reduction of Na+-K+ATPase from nerve cords. Thus, the maximum effect measured occurred with the same enzyme and tissue as determined from in vitro studies. The metabolite, DDE, used at 15 μg per roach, gave no significant change in activity of the ATPase system following injection. In contrast, high single doses of DDT (7.5 μg/roach) and 100 μg DDE and dicofol per roach caused over 30% increase in oligomycin-sensitive Mg2+ATPase of muscle and a 10–15% increase in Na+-K+ATPase of nerve cords measured 24 and 48 hr later. While a similar response was observed for Mg2+ATPase activities in cockroaches that were immobilized, the increase in enzyme activities were much greater than that caused by the pesticides.  相似文献   

5.
The effects of DDT on the Na/Ca exchange system were studied by using an axolemma-rich nerve membrane preparation from walking legs of Homerus americanus, the American lobster. The Na/Ca exchange system was measured by using two criteria: Na+ stimulated 45Ca2+ uptake by the membrane vesicles and Na+Ca2+ protein kinase-phosphatase (formally called Ca-ATPase) as measured by the production of 32P-labeled inorganic phosphate from [γ-32P]ATP in the presence of Na+ and Ca2+. Activities of both systems were stimulated by the addition of exogenous calmodulin. DDT's inhibitory actions on both systems were reduced when an excess of calmodulin was added. Also addition of large amounts of ATP (or γ-thio-ATP) to the former system had an effect to reduce levels of DDT inhibition. DDT appears to act on the protein kinase proper as well as calmodulin itself in this system in a reversible manner.  相似文献   

6.
A continuous steady-state assay procedure was used to investigate the effects of DDT and several analogs on the in vitro Mg2+-stimulated adenosinetriphosphatase of a trout brain mitochondrial fraction. Pharmacological dissection of the enzyme with oligomycin, dicyclohexyl-carbodiimide, and azide failed to yield a fraction specifically sensitive to the organochlorines. At 25°C, low doses of DDT (≤1.35 μmol/mg of protein) stimulated enzyme activity, while methoxychlor was stimulatory at all doses. Higher doses of DDT and of several analogs caused only 45.5% or less inhibition at 25°C, but inhibition increased at lower temperatures. The physiological significance of these effects is discussed.  相似文献   

7.
Isolated spinach (Spinacia oleracea L.) chloroplasts contain a Mg+2-dependent ATPase that is activated by light in the presence of dithiothreitol (DTT) and phenazine methosulfate (PMS). Effects of 11 herbicides, known to affect photophosphorylation in isolated chloroplasts, were measured on ATPase activity when added prior to illumination, on the postillumination dark activity of the ATPase, and on the light-induced synthesis of ATP mediated by DTT and PMS.When added prior to illumination, activity of the ATPase was stimulated by low, and inhibited by high, molar concentrations of chlorpropham, dicryl, dinoseb, ioxynil, oryzalin, perfluidone, propanil, and 4,6,7-trichloro-2-(trifluoromethyl)benzimidazole (TCTFB). The light activation of the ATPase was not affected by diuron, bromacil, or atrazine. Perfluidone, dinoseb, ioxynil, and TCTFB stimulated, whereas chlorpropham, dicryl, oryzalin, propanil, atrazine, bromacil, and diuron had no effect on postillumination hydrolytic activity. The light-induced synthesis of ATP mediated by DTT and PMS was inhibited strongly by chlorpropham, dicryl, dinoseb, ioxynil, oryzalin, perfluidone, propanil, and TCTFB.Because the ATPase reactions are considered to represent the reversal of the terminal reactions of photophosphorylation, inhibition of these reactions implies that the compounds tested, except for diuron, atrazine, and bromacil, have a site of action on the ATP-generating pathway that is separate from the site involved in the inhibition of the Hill reaction.  相似文献   

8.
A water-soluble Mg2+-dependent ATPase (coupling factor F1) was isolated from the mitochondria of housefly thorax. It comprised about 14% of the proteins from a crude preparation. The F1 preparation was nearly homogeneous as assessed by gel electrophoresis, isoelectric focusing, and electron microscopy. It was composed of five subunits with the following apparent molecular weights: α, 68,000; β, 61,000; γ, 38,000; δ, 27,000; and ?, 17,500. The isoelectric pH (pI) of this protein was 7.3. F1 had a pH optimum of 8.2 and a temperature optimum between 37 and 45°C. The enzyme was fairly stable at 25°C. Nearly complete loss of activity was noticed at 0°C, while at 0 or 25°C, glycerol (20%) partially stabilized the enzyme activity against such inactivation. The Km value of the enzyme with respect to ATP was 0.4 mM. The activity was stimulated by low concentrations of 2,4-dinitrophenol. The enzyme was inhibited by azide, p-hydroxymercuribenzoate, and guanidine hydrochloride. Oligomycin and the pesticides pyrethrin, cyhexatin, and DDT have no effect on the enzyme activity. However, all of these chemicals inhibited intact Mg2+- ATPase. The results are discussed in the light of differential responses of soluble and intact ATPase to these pesticides.  相似文献   

9.
为寻找防治枸杞蚜虫的适用药剂,采用玻璃管药膜法,测定了4种拟除虫菊酯类杀虫剂对枸杞蚜虫的毒力及对其三磷酸腺苷酶(ATPase)和谷胱甘肽S-转移酶(GSTs)活性的影响。结果表明:枸杞蚜虫对联苯菊酯最敏感,LC50值为4.34 mg/L;氯菊酯、高效氯氰菊酯和甲氰菊酯的LC50值分别为17.08、40.50和184.84 mg/L。4种杀虫剂对枸杞蚜虫两种ATPase活性均有抑制作用,药剂浓度为1×10-4mol/L时,4种药剂对Na+-K+-ATPase活性的抑制率均高于对Ca2+-M g2+-ATPase的抑制率,其中对Na+-K+-ATPase活性的抑制率从高到低依次为:联苯菊酯高效氯氰菊酯氯菊酯甲氰菊酯,而对Ca2+-M g2+-ATPase的抑制率则是联苯菊酯最高(46.41%),高效氯氰菊酯最低(33.04%)。4种药剂对枸杞蚜虫GSTs活性的影响差异较大:联苯菊酯在低浓度时对GSTs具有诱导作用,高浓度时则表现为一定的抑制作用;不同浓度高效氯氰菊酯和氯菊酯对GSTs活性均表现为抑制作用,抑制率最高达85.02%;而甲氰菊酯处理后GSTs的活性则升高了193.07%~249.96%。  相似文献   

10.
DDT inhibits the ATPase activity of the intact eel electroplaque. At a concentration of 10?5M, DDT inhibited 46% of the total ATPase activity, and 10?4M DDT inhibited 62% of the total ATPase activity and 62% of the ouabain-sensitive ATPase activity. The latter concentration of DDT reduced the rate of Na efflux from intact electroplaques and slowed the rate of recovery of the membrane potential following a large depolarization produced by carbamylcholine application. Repetitive direct stimulation of the innervated membrane at 10 Hz during the application of 10?4M DDT produced a significant irreversible depolarization. Ouabain, 10?4M, produced similar effects. The possible role of the inhibition of active NaK transport in producing the symptoms of DDT poisoning is discussed.  相似文献   

11.
Intact mitochondria, isolated from red coxal muscle of the American cockroach (Periplaneta americana L.), were incubated in the presence of 1,1,1-trichloro-2,2-bis(4-chloro[14C]phenyl)ethane ([14C]DDT) to isolate a suspected binding site for DDT in the membrane sector of the mitochondrial ATPase. The requirements for the binding of DDT were compared with those for the binding of dicyclohexyl[14C]carbodi-imide([14C]DCCD), a potent inhibitory probe of mitochondrial ATPase activity. [14C]DDT appeared to bind to a proteolipid of the membrane sector, which also binds [14C]DCCD. Exchange experiments, with [14C]DCCD, [14C]DDT and unlabelled DDT at different concentrations, indicated that DDT and DCCD may be acting on a similar protein. This protein may act as the energy transducing protonophore required for the synthesis and hydrolysis of ATP in coupled mitochondria. Inhibition of mitochondrial ATPase activity may be a consequence of DDT and DCCD binding to this proteolipid protonophore, resulting in the disruption of energy transduction in muscle and nerve.  相似文献   

12.
A continuous in vitro steady-state assay procedure was used to investigate the dependence of trout brain mitochondrial Mg2+-stimulated adenosinetriphosphatase specific activity on temperature and substrate concentration. The inhibition of enzyme activity by DDT was independent of substrate concentration. DDT and several analogs caused increases in the experimental activation energy and frequency factor of the enzyme-catalyzed reaction, which gave rise to a negative temperature coefficient of inhibition. It is suggested that DDT and other highly lipophilic compounds have the potential to allosterically affect membrane-bound enzymes by simply becoming a major lipoid component of the membranes.  相似文献   

13.
Inhibition of ATPase from aphid plasma membrane, sarcoplasmic reticulum (SR), and brain synaptosomal plasma membrane of locust, by 1,5-diphenyl-2-penten-1-one (dp-B), was studied. Results demonstrated that dp-B exhibited the similar effects on ATPase found in the three membranes amongst which the plasma membrane Ca2+–Mg2+-ATPase is the primary target. The effects of dp-B on Ca2+–Mg2+-ATPase activity were bi-directional: the enzyme enhanced hydrolyzation when dp-B or Ca2+ concentrations were low but inhibited significantly when at high concentrations. The inhibition of Ca2+–Mg2+-ATPase by dp-B from brain synaptosomal plasma membrane of insect is higher than that from other organizational plasma membranes of the insect. Dp-B inhibiting Ca2+- and CaM-requiring ATPase activity may be an important mechanism by which the insect gets poisoned (for example aphid).  相似文献   

14.
Earlier communications from this laboratory have shown that DDT inhibited oligomycin-sensitive Mg2+-ATPase (EC 3.6.1.3) but that its active component, F1, was not affected. In the present investigation evidence has been obtained to determine the nature of the requirements for DDT sensitivity. The results showed that DDT sensitivity was conferred to F1 from pig heart mitochondrial preparations when it was bound to F0 from the same preparation. The F1 from house fly (Musca domestica L) thorax was able to bind to F0 from pig heart. This combination showed similar sensitivity to that of the original F1-F0 combination from pig heart mitochondria. However, when F1 from pig heart mitochondria was incorporated into F0 depleted in oligomycin sensitivity-conferring protein (OSCP) from the same source, the resulting ATPase activity was insensitive to DDT. Addition of crude (50–200 μg) or purified (5–20 μg) OSCP in the above preparation restored DDT sensitivity. Presence of dioleyl or dipalmitoyl phosphatidyl choline or Triton X-100 in the reaction medium antagonized the DDT inhibitions. Depletion of phospholipids from submitochondrial membrane preparations (SMP) decreased ATPase activity. Addition of dioleyl or soybean phosphatidyl choline to this lipid-depleted preparation restored DDT sensitivity. Evidence presented suggests that DDT acted on F1 in association with one or more membrane components and that OSCP and phospholipid were essential for DDT sensitivity.  相似文献   

15.
选取2个玉米品种(金玉819和金单999),探讨了3种盐胁迫(NaCl、Na_2SO_4和NaNO_3)对玉米幼苗生长、抗氧化酶活性以及叶片中K~+、Na~+、Ca~(2+)累积的影响。结果表明:3种不同类型的盐胁迫均会导致玉米幼苗鲜重下降,地上部鲜重金玉819下降超过28.6%,金单999下降超过18%;盐胁迫下金玉819叶片SOD酶活上升2.1倍以上, POD酶活性最高上升4.5倍,APX最高上升2.1倍,CAT最高上升2.2倍;金单999叶片SOD酶活最高上升2.1倍,APX最高上升1.6倍,CAT最高上升1.9倍。2个基因型玉米胁迫下叶片内Na~+含量上升4.5～6.3倍;NaCl和NaNO_3处理下,K~+/Na~+比对照降低90%～93%,而Na_2SO_4处理下K~+/Na~+下降78%～82%,金玉819和金单999的Ca~(2+)/Na~+比对照分别降低了85%～90%和92%～94%。综合分析表明NO~-_3引起的次生盐害对玉米生产危害较大。与金单999相比,金玉819对盐胁迫更加敏感,相同Na~+浓度处理下,金玉819的鲜重和SOD酶活性下降显著且拥有较低的K~+/Na~+和Ca~(2+)/Na~+值。  相似文献   

16.
塔里木河流域水化学组成分布特征   总被引：4，自引：0，他引：4  
于2010年6月对塔里木河干流及主要支流地表水进行水化学采样,共设25个点采集50个样品。分析表明：塔里木河干流水体中阳离子Na++K+＞Ca2+＞Mg2+,与南北侧支流Na++K+＞Mg2+＞Ca2+存在显著差异,但均以Na++K+为主,阳离子浓度分别占干流、南北侧支流的68.6%、62.6%和62.5%。与1965年对应采样点同月份水化学成分相比,塔里木河流域主要可溶性离子浓度增幅较大,整体平均增加8.0倍,尤其是Cl-达21.7倍,这可能是近年来塔里木河流域气温上升降水增加等自然因素,间接促进降水过程中水化学侵蚀地表可溶性物质所致。同时,流域内工农业快速发展,生活污水、工农业废水大量排放到塔里木河,这可能是影响塔里木河水质变化的重要因素之一。  相似文献   

17.
为探讨不同阳离子组成微咸水灌溉对膜下土壤孔隙结构的影响,开展2a田间定位试验,设置当地地下水灌溉（CK）、NaCl微咸水灌溉（T1）、KCl微咸水灌溉（T2）、CaCl2微咸水灌溉（T3）、MgCl2微咸水灌溉（T4）5个处理,利用CT扫描技术研究不同阳离子组成微咸水对土壤孔隙结构的影响。结果表明：与CK处理相比,随灌水次数增多,添加Na+处理的土壤大孔隙度显著降低,添加K+、Ca2+、Mg2+处理的土壤大孔隙度显著增加,2022年添加Na+处理的大孔隙度平均降低了44.49%,添加K+、Ca2+、Mg2+处理的土壤大孔隙度平均分别增加了5.73%、80.73%、25.75%;在2021—2022年期间,与CK相比,4种不同阳离子处理土壤孔隙成圆率均呈增加趋势,其中添加Ca2+、Mg2+处理增加显著,土壤孔隙成圆率平均增加区间分别为25.52%~30.94%、17.46%~23.19%;连续灌溉2a之后,添加Na+和K+处理的土壤开裂程度加重,土壤稳定性变差,而添加Ca2+和Mg2+对改善土壤结构、提高土壤入渗性能作用明显。  相似文献   

18.
盐基离子对土壤持水及收缩特性的影响   总被引：1，自引：0，他引：1  
不同盐离子对土壤持水能力具有不同程度影响,且在土壤水分特征曲线测定过程中,土体随失水发生收缩和开裂。在已获取研究成果基础上进行扩展,进一步探索8种低浓度盐离子(K~+、Na~+、Ca~(2+)、Mg~(2+)、Cl~-、HCO_3~-、CO_3~(2-)、SO_4~(2-))对土壤持水能力和收缩特征的影响。选取陕西粉黏壤土并分别采用含有此8种离子的盐溶液(浓度均约为1 g·L~(-1))对土样进行饱和处理,以无盐离子处理作为对照(CK);采用离心机法获取土壤水分特征曲线,使用游标卡尺测定离心过程中的土体轴向沉降高度,编写MATLAB程序对裂缝图像提取裂隙度量指标,据此对各处理土壤持水能力和收缩特征进行对比分析及评价。结果发现,在此浓度条件下:(1)K~+、Na~+及4种阴性盐离子在一定程度上均可提高土壤持水能力,且阴阳盐离子中CO_3~(2-)和K~+效果最显著,分别较CK提高35.81%和3.68%;(2)Mg~(2+)、SO_4~(2-)和CO_3~(2-)有利于减小土体轴向收缩度,且阴阳盐离子的作用效果分别表现为HCO_3~-Cl~-SO_4~(2-)CO_3~(2-)和Na~+K~+Ca~(2+)Mg~(2+);(3)Na~+、Mg~(2+)及4种阴性盐离子在一定程度上均有利于减轻土壤开裂程度,可同时减小土壤裂隙总长度、总面积以及长度密度和面积密度,且阴阳盐离子中CO_3~(2-)和Na~+效果最显著。研究可为不同类型盐碱土壤持水能力评价及其干缩开裂机理认知提供理论指导。  相似文献   

19.
Salinity is a common issue of semi-arid and arid lands rendering them unfit for agriculture. Saline wastelands can be converted into productive ecosystems by rehabilitating them with salt tolerant native tree species. The objective of this work was to study the effect of NaCl salinity on tissue nutrient contents of the four dryland tree species. Saplings were grown in pots under nonsaline and high salinity conditions. After eighteen weeks the plants were harvested and their tissue nutrient contents were analyzed. Results revealed that all species accumulated high amounts of Na+ under saline conditions, while concentrations of N, P and Mg2+ decreased in their tissues. Concentrations of K+ and Ca2+ showed more variable trend in various tissues in response to increase in soil salinity. Na+: K+ ratios of roots (1.57), stems (1.27), and leaves (1.66) of salinized Salvadora oleoides plants were lowest among all the four species. Root Na+: K+ ratio of salinized plants was significantly higher for Prosopis cineraria (7.10), while these ratios for stem (1.85) and leaf (3.42) were highest for Tamarix aphylla. Plants of P. cineraria showed lowest Stem-Na+/root-Na+ ratio (0.30) when subjected to salinity. Results showed that salinity induces nutrient deficiency in all species. Salinity tolerance of these species can be attributed to their ability to (i) restrict translocation of Na+ from roots to stem; (ii) keeping low tissue Na+: K+ ratios; and (iii) selectivity of K+ and Ca2+ over Na+, and can be used for the screening of salt-tolerant ecotypes for the rehabilitation of saline wastelands.  相似文献   

20.
Antibody molecules were produced by injection of BSA-Kelevan into chickens and rabbits. Pure antibody was obtained by a single pass of blood serum through an affinity column. The affinity gel was prepared by covalently binding BGG-Kelevan to activated Sepharose 4B-CN. Purity of the antibody was determined by ultracentrifugation and gel electrophoresis. Properties of the antibody included: sedimentation coefficient = 6.2, pI = 7.0, calculated MW = 150,000, and precipitin band formation using the microouchterlony test. The antibodies in free or immobilized form were able to prevent or reverse Kepone inhibition of ATPase activity from a variety of tissues from different sources. About 70 μg (approx 0.4 μM) of purified antibody was sufficient to restore the activity of mitochondrial (oligomycin-sensitive) Mg2+ ATPase activity which had been inhibited (in vitro) by 1 μM Kepone. The antibody was effective in preventing enzyme inhibition by other organochlorine pesticides with widely differing molecular structures. However, nonchlorinated inhibitors of mitochondrial oligomycin-sensitive Mg2+ ATPase activity were much less affected by the antibody. The available evidence suggests that the antibody binding site for the hapten may be specific for secondary or induced bonding forces due to the carbon-chlorine bonds rather than for a specific molecular structure.  相似文献   

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