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1.
The action of the molluscicide Frescon, which induces contractures in smooth and cross-striated muscles of the freshwater snail Lymnaea stagnalis, was compared with the action of caffeine. The results indicate that the latter agent promotes contractions in Lymnaea muscles by releasing Ca2+ from intracellular stores. Such a release could not be attributed to the action of Frescon. Furthermore, the molluscicide did not appear to alter muscle function at the level of the contractile apparatus as it did not affect the time course of caffeine-induced contractions. These results favor the hypothesis that Frescon increases sarcolemmal Ca2+ permeability. 相似文献
2.
The molluscicide Frescon (N-(triphenylmethyl)morpholine) induces prolonged, irreversible contractions (contractures) in the isolated heart ventricle, penis retractor, and foot muscles of the aquatic snail Lymnaea stagnalis. It also causes contracture of the penis retractor muscle, but not the heart ventricle, of the terrestrial snail Helix aspersa. Since Frescon-induced contracture is not accompanied by a depolarization of the sarcolemma of Lymnaea heart ventricle muscle cells, it is suggested that the action of this molluscicide is associated with a membrane potential-independent activation of the contractile machinery. The rapid response of Lymnaea musculature to Frescon suggests that the direct contracture-inducing action of this molluscicide could explain its toxicity to the whole animal. 相似文献
3.
Stephen O. Duke Kevin C. Vaughn R.Don Wauchope 《Pesticide biochemistry and physiology》1985,24(3):384-394
Root-fed or foliar-applied glyphosate [N-(phosphonomethyl) glycine] reduced uptake and translocation of Ca2+ and Mg2+, but not K+, by soybean [Glycine max (L.) Merr. “Hill”] seedlings as measured by atomic absorption spectrometry. Histochemical techniques revealed that cells of secondary roots that were formed after glyphosate treatment were deficient in Ca2+. The relative distribution of Ca2+ in control root and leaf cells was mitochondria > plastids > cytoplasm. Glyphosate severely reduced Ca2+ content and eliminated intracellular concentration of Ca2+ in the mitochondria of both root and leaf cells. Glyphosate had no effects on K+ distribution at the ultrastructural level. These results support the view that glyphosate effects on distribution of divalent metal cations may be related directly or indirectly to the phytotoxicity of the herbicide. 相似文献
4.
《Pesticide biochemistry and physiology》1987,29(3):187-196
A series of 25 pyrethroids were assessed for their effects on Na+-dependent norepinephrine release and on Ca2+ uptake in vitro using a crude rat brain synaptosomal preparation. The most effective pyrethroids required a concentration of 3–10 μM to promote norepinephrine release. Plotting release data versus lipophilicity (as log P) for each compound resulted in a parabolic curve with log Popt being 5.4 for maximal release. The release promoted by most of the compounds assessed at 30 μM could not be or was only partially reversed by either tetrodotoxin or substituting choline for Na+ conditions which readily reversed the release promoting effects of veratridine. Thus, many pyrethroids, particularly those without the α-cyano group, did not display their expected effects on the Na+ channel in rat brain. When assessed at 5 μM, pyrethroids inhibited, had no effect, or caused increases in the amount of Ca2+ incorporated in the presence of ATP. The effectiveness of the various pyrethroids to inhibit Ca2+ uptake again displayed a parabolic relationship with log Popt being 6.4. It was concluded that the variations in pyrethroid effects on norepinephrine release and Ca2+ uptake are not solely related to their particular chemical structures, but to lipophilicity. The effects of many pyrethroids on Ca2+ metabolism, particularly displacement of bound Ca2+, better explain the transmitter release promoting properties in vitro rather than a direct effect on the Na+ channel. No direct relationship between known toxicity to mammals and Ca2+ inhibition by pyrethroids was established. 相似文献
5.
为了明确钙离子与东莨菪内酯联合作用的杀螨效果,进而为东莨菪内酯的开发利用提供参考,采用玻片浸渍法测定了钙离子(Ca2+)与东莨菪内酯混用对朱砂叶螨Tetranychus cinnabarinus雌成螨的杀螨毒力,并测定了活体和离体条件下对螨体内Ca2+-ATP酶活性的影响,对Ca2+的增效作用机理进行了初步分析。结果表明:Ca2+与东莨菪内酯联合使用能显著增强东莨菪内酯的杀螨效果,其中联合作用24和48 h的LC50值分别比东莨菪内酯单独处理降低20%和45%;对朱砂叶螨Ca2+-ATP酶活性的测定结果表明,无论在活体还是离体条件下,Ca2+与东莨菪内酯联用均能显著增强对Ca2+-ATP酶的抑制作用,而相同浓度的Ca2+单独作用则对Ca2+-ATP酶活性无影响,这也在一定程度上证明了Ca2+-ATP酶是东莨菪内酯的重要作用靶标之一。 相似文献
6.
The effects of pesticides and their breakdown products on membrane fluxes is a subject of interest in assessing the potential ecological impact of these substances. As part of a continuing program we have examined the effects of 2,4-dichlorophenoxyacetic acid (2,4-D) and paranitrophenol (PNP) on divalent cation and primary amine losses from and glycine uptake by gills of the bivalve molluscs Anodonta californiensis (fresh water) and Mytilus californianus (marine). Both 2,4-D and PNP reduce glycine influx into gills of M. californianus. This observation is consistent with the view that glycine is bound to the gill surface as a Mg2+ complex prior to active transport.For gills of A. californiensis, Ca2+ and Mg2+ losses are increased by 10?3M 2,4-D relative to that into distilled water. Primary amine losses are increased for both A. californiensis and M. californianus gills at low 2,4-D concentrations.For A. californiensis and M. californianus gills the uptake of both 2,4-D and PNP are reduced by increasing concentrations of Ca2+ and Mg2+. In the case of A. californiensis, Ca2+ has a larger effect than Mg2+, which is consistent with the demonstrated stabilizing effect of Ca2+ on biological membranes. The uptake of PNP is larger than that of 2,4-D and glycine for gills of A. californiensis. The uptake of 2,4-D is reduced by the presence of an excess concentration of glycine but this is probably a physical effect. The uptake of 2,4-D, PNP, and glycine are all passive processes for A. californiensis gills. Glycine does not reduce 2,4-D uptake into M. californianus gills. For M. californianus the transport mechanism for glycine is not the same as that for 2,4-D; the former being active transport and the latter passive transport. However, 2,4-D does interfer with the active transport of glycine. 相似文献
7.
The molluscicide Frescon (N-(triphenylmethyl)morpholine) induces prolonged, irreversible contractions (contractures) in the isolated heart ventricle, penis retractor, and foot muscles of the aquatic snail Lymnaea stagnalis. It also causes contracture of the penis retractor muscle, but not the heart ventricle, of the terrestrial snail Helix aspersa. Since Frescon-induced contracture is not accompanied by a depolarization of the sarcolemma of Lymnaea heart ventricle muscle cells, it is suggested that the action of this molluscicide is associated with a membrane potential-independent activation of the contractile machinery. The rapid response of Lymnaea musculature to Frescon suggests that the direct contracture-inducing action of this molluscicide could explain its toxicity to the whole animal. 相似文献
8.
The calcium entry blockers sodium nitroprusside (10?2M) and sodium pentobarbital (5 × 10?3M) had different effects on high-potassium-induced and Frescon-induced contractures in a smooth and a cross-striated muscle of the snail Lymnaea stagnalis. This suggests that Frescon causes an increase in sarcolemmal calcium permeability by a mechanism which is different from that utilized by high extracellular potassium. 相似文献
9.
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 CaMg-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
10.
Zhi-bin Ma Li-jing Sun Jun-xia Zhao Jing Liu Li-an Wang 《European journal of plant pathology / European Foundation for Plant Pathology》2010,127(4):545-556
Two types of Ca2+/calmodulin-dependent protein kinase (CaMK) were found in Magnaporthe oryzae. MgCaMK1 and MgCaMK2 were both cloned and sequenced. High similarities in amino acid sequence to other reported CaMKs in fungi suggested that CaMKs were relatively conserved. Both MgCaMK1 and MgCaMK2 have a serine/threonine protein kinase active site and a calmodulin (CaM)-binding domain. Southern blot analysis showed that MgCaMK1 or MgCaMK2 existed as a single copy in the M. oryzae genome. Subsequently, MgCaMK1 or MgCaMK2 was expressed in Escherichia coli BL21 via a pET-32a (+) plasmid. The purified proteins exhibited protein kinase activity. The autophosphorylation and substrate phosphorylation of MgCaMK1 exhibited a Ca2+/calmodulin-dependent manner, and suggested that it belonged to the group of Ca2+/calmodulin-dependent protein kinases. However, the autophosphorylation and substrate phosphorylation of MgCaMK2 exhibited a Ca2+-dependent manner and suggested that it belonged to the group of Ca2+-dependent protein kinases. 相似文献
11.
Although the molluscicide Frescon is a strong neurotoxin to the Lymnaea stagnalis central nervous system in vitro, it is probable that the exposure of the whole animal to this molluscicide fails to result in central nervous system abnormalities: Frescon does not appear to reach the brain in sufficient quantity to disrupt its normal activity. However, only those Frescon analogs found to be neurotoxic were molluscicidal, suggesting some related mode, if not site, of action. Frescon and its analogs may act by affecting excitable tissues other than the nervous system (e.g., the snail musculature) by altering certain functional and/or structural membrane properties. 相似文献
12.
Anthranilic and phthalic diamides exemplified by chlorantraniliprole (Chlo) or cyantraniliprole (Cyan) and flubendiamide (Flu), respectively, are the newest major chemotype of insecticides with outstanding potency, little or no cross resistance with other classes and low mammalian toxicity. They are activators of the ryanodine (Ry) receptor (RyR)-Ca2+ channel, based on Ca2+ flux and electrophysiology investigations. The goal of this study is to define species differences in the degree and mechanisms of diamide selective action by radioligand specific binding studies at the [3H]Ry, [3H]Chlo and [3H]Flu sites. The [3H]Ry site is observed in muscle of lobster, rabbit and four insect species (Musca domestica, Apis mellifera, Heliothis virescens and Agrotis ipsilon) whereas the [3H]Chlo site is evident in the four insects and the [3H]Flu site in only the two lepidoptera (Agrotis and Heliothis). [3H]Ry binding is significantly stimulated by Chlo, Cyan and Flu with the insects (except Flu with Musca) but not the lobster and rabbit. [3H]Chlo binding is stimulated by Ry and Flu in Musca and Apis but not in the lepidoptera, while Flu and Cyan are inhibitory. [3H]Flu binding is strongly inhibited by Chlo and Cyan in Agrotis and Heliothis. [3H]Chlo and [3H]Flu binding are not dependent on added Ca2+ or ATP in Heliothis and Agrotis whereas the other radioligand-receptor combinations are usually enhanced by Ca2+ and ATP. More generally, there are species differences in the Ry, Chlo and Flu binding sites of the RyR that may confer selective toxicity and determine target site cross resistance mechanisms. 相似文献
13.
研究了Cd2+（10 mg·L-1、30 mg·L-1）胁迫下不同浓度Ca2+（0、80、160、320 mg·L-1）对板蓝根种子萌发、幼苗抗氧化酶系统及蛋白质含量的影响。结果表明：低浓度Ca2+（80、160 mg·L-1）可缓解Cd2+毒害,显著提高板蓝根种子的发芽率、发芽势、发芽指数、活力指数,促进蛋白质含量的增加,提高SOD、POD、CAT活性,且160 mg·L-1 Ca2+缓解效果最好,缓解能力随Cd2+浓度的升高有所下降;高浓度Ca2+（320 mg·L-1）与Cd2+作用,反而抑制了板蓝根种子的萌发,幼苗的POD、SOD、CAT活性及蛋白质含量下降。低浓度Ca2+可以显著提高板蓝根的抗性,对Cd2+毒害起缓解作用,高浓度的Ca2+与Cd2+对板蓝根种子起协同毒害作用。 相似文献
14.
Steven B. Symington Hilliary E. HodgdonRichard K. Frisbie J. Marshall Clark 《Pesticide biochemistry and physiology》2011,99(2):131-139
Isolated rat brain synaptosomes were used to evaluate the action of pyrethroid mixtures on Ca2+ influx and subsequent glutamate release under depolarizing conditions. In equipotent binary mixtures at their respective and/or estimated EC50s with deltamethrin always as one of the two components, cismethrin, λ-cyhalothrin, cypermethrin, esfenvalerate and permethrin were additive and S-bioallethrin, fenpropathrin and tefluthrin were less-than-additive on Ca2+ influx. In binary mixtures with deltamethrin always as one of the two components, esfenvalerate, permethrin and tefluthrin were additive and λ-cyhalothrin was less-than-additive on glutamate release. Binary mixture of S-bioallethrin and cismethrin was additive for both Ca2+ influx and glutamate release. Only a subset of pyrethroids (S-bioallethrin, cismethrin, cypermethrin, and fenpropathrin) in binary mixtures with deltamethrin caused a more-than-additive effect on glutamate release. These binary mixtures were, however, only additive (cismethrin and cypermethrin) or less-than-additive (S-bioallethrin and fenpropathrin) on Ca2+ influx. Therefore, increased glutamate release evoked by this subset of pyrethroids in binary mixture with deltamethrin is not entirely occurring by Ca2+-dependent mechanisms via their action at voltage-sensitive calcium channels. These results suggest that pyrethroids do not share a common mode of toxicity at presynaptic nerve terminals from rat brain and appear to affect multiple target sites, including voltage-sensitive calcium, chloride and sodium channels. 相似文献
15.
Frescon (N-triphenylmethyl morpholine) is a strong neurotoxic agent when applied to the in vitro brain of Lymnaea stagnalis. Ten Frescon analogs were tested in order to determine their degree of neurotoxicity. Nine of the ten analogs were found to be neurotoxic to a greater or lesser degree. Triphenylmethanol (a hydrolysis product of Frescon), however, did not exhibit neurotoxicity. These results form part of an investigation to determine the plausibility of the snail central nervous system being a target for Frescon action. 相似文献
16.
日光温室钾镁配施对土壤固相和液相钾、钙、镁分配及比例的影响 总被引：1，自引：0，他引：1
针对西北地区日光温室作物出现的缺镁问题,通过施用不同水平的硫酸镁肥及减少钾肥施用处理,探究钾、钙、镁离子在土壤固相和液相的分布及比例。得出以下结论:土壤液相镁浓度随着镁肥施用量的增加而显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理镁浓度相比不施用MgSO_4处理分别增加26.64%、74.78%;相比不施用MgSO_4处理,施用镁肥后土壤液相Mg~(2+)占K~+、Ca~(2+)、Mg~(2+)总量的比例显著增加,施用45 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理、施用90 kg·hm~(-2)MgSO_4(400 kg·hm~(-2)K_2O)处理和施用90 kg·hm~(-2)MgSO_4(200 kg·hm~(-2)K_2O)处理分别增加32.03%、31.62%、32.84%;施用镁肥促进钾由固相向液相转移;相比不施用MgSO_4处理,施用45、90 kg·hm~(-2)MgSO_4处理土壤固相交换性钾含量分别降低15.78%、27.74%,差异达到显著水平;交换性钾饱和度分别降低13.39%、27.21%;液相钾浓度显著增加,分别增加18.84%、73.91%;K+占K+、Ca~(2+)、Mg~(2+)总量的比例显著增加,增幅分别为23.91%、31.21%;土壤固相K+/Mg~(2+)比例分别降低14.52%、26.61%,;土壤液相Ca~(2+)/Mg~(2+)比例显著降低,降幅分别为31.51%、32.29%;施用MgSO_4肥量相同,钾肥施用量减半,土壤液相钾浓度降低69.88%,K+/Mg~(2+)比例降低20.88%;施用镁肥对番茄具有一定的增产作用,并能促进作物对镁的吸收。 相似文献
17.
The organophosphorus insecticides, parathion and azinphos (10?5-10?4M), significantly stimulate the Ca2+-pump activity of sarcoplasmic reticulum, while malathion has a limited effect. The rates of Ca2+ translocation and ATP hydrolysis are both stimulated and, apparently, the ratio is improved. Parathion and azinphos maximally increase this ratio by 26 and 14%, respectively. The organochlorine compounds, DDT and aldrin, also stimulate the Ca2+ pump, and lindane has a reduced effect. These effects are smaller than those observed for parathion and azinphos. The order of effectiveness is similar to the toxicity of the compounds to mammals and can be described as follows: parathion > azinphos > DDT ≈ aldrin > malathion ≈ lindane. 相似文献
18.
Ca2+ homeostasis is one of the major regulatory mechanisms operating in the nervous system, with calmodulin translating the Ca2+ message into cellular response. To check if hexachlorocyclohexane (HCH) acts as a calmodulin antagonist in the nervous system of rats, the in-vitro effect of HCH on calmodulin-dependent Ca2+-ATPase and cAMP-phosphodiesterase (PDE) in rat brain has been studied. In the membrane fraction from rat brain, a basal activity of Ca2+-ATPase was obtained in the absence of Ca2+. Inclusion of Ca2+ (1 mM) increased the enzyme activity by 70%. Further, addition of fluphenazine, a potent calmodulin antagonist, inhibited the Ca2+-dependent enzyme activity (IC50 = 85 μM), demonstrating the calmodulin dependence of the enzyme activity. The Ca2+- and calmodulin-dependent Ca2+-ATPase was inhibited by HCH in a dose-dependent manner (IC50 = 80–90 μM). Ca2+- and calmodulin-dependent cAMP-PDE from the cytosolic fraction of rat brain was inhibited by HCH (340 μM) by 79%. Addition of excess calmodulin reversed the inhibitory effects of HCH or fluphenazine on Ca2+-ATPase and cAMP-PDE, suggesting their direct interaction with calmodulin. By fluorescence interaction studies it has been shown that HCH interacts directly with calmodulin. These studies show that HCH may modulate the intracellular concentration of Ca2+ and cAMP, by decreasing the effectiveness of calmodulin towards its effector enzymes, resulting in an altered signal transduction in the nervous system. 相似文献
19.
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
20.
The mode of action of DDT and pyrethroids was investigated in the house fly, Musca domestica L, using drug:receptor binding techniques. Both in vivo and in vitro binding studies demonstrated the existence of membrane receptors which bind specifically to [14C]DDT and [14C]cis-permethrin. The receptors show properties to be expected of a critical target site of these insecticides. These include negative temperature correlation with binding, relatively nonsensitivity to DDE, and sensitivity to Ca2+. The receptor sites are readily saturated at 45–90 nM [14C]DDT and have an apparent disassociation constant (Kd) of 12.2 nM. The maximum number of binding sites was estimated to be 17 pmol DDT/mg membrane protein (0.34 pmol/house fly head). Competition studies showed DDT, cis-permethrin, and cypermethrin bind to the same receptor but not at precisely the same site. The addition of Ca2+ to the incubation buffer significantly inhibited the binding of both [14C]DDT and [14C]cis-permethrin, suggesting the receptor binding is Ca2+ sensitive and may have a role in ion conductance. 相似文献