The released polysaccharide of the cyanobacterium Aphanothece halophytica inhibits flocculation of the alga with ferric chloride

The effect of the released polysaccharide (RPS) of the cyanobacterium Aphanothece halophytica GR02 on the recovery of the alga by flocculation with ferric chloride was studied. With increasing RPS concentration in algal cultures from 0 to 68 mg L⁻¹ the flocculation efficiency at the same dosage of ferric chloride decreased, and higher dosages of ferric chloride were required to attain the same flocculation efficiency. It is demonstrated that RPS could form complexes with ferrum during flocculation. In conclusion, RPS of A. halophytica GR02 had a significant inhibitory effect on flocculation of the alga with ferric chloride. The inhibitory mechanism of A. halophytica GR02 RPS allows the RPS to compete for ferrum by forming complexes with ferrum, thus leading to the consumption of ferrum in ferric chloride.     

Tetrathiafulvalene Radical Cation — A New Potent Inhibitor of Anion Transport in a Green Alga

An inhibitory effect of potassium ferricyanide on the light-dependent active uptake of chloride anions into the alga Hydrodictyon reticulatum has drawn attention to the possibility that chloride transport proceeds as an exchange for electrons and hence can be impaired by artificial electron acceptors. Tetrathiafulvalene radical cation present in solutions of the highly conductive TTF-C1 crystals is easily reduced to TTF⁰ and inhibits the chloride uptake more powerfully than does ferricyanide. A practically complete inhibition of Cl^? uptake is brought about by 3 × 10^?5 M TTF⁺. The presence of ferricyanide actually reduces the inhibitory effect of TTF⁺; the complex equilibria of a mixture of the two electron acceptors were examined by cyclic voltammetry and a competition between the two for the inhibitory function has been suggested as a possible explanation.     

Effects of Lanthanum Chloride Administration in Prenatal Stage on One-Trial Passive Avoidance Learning in Chicks

Lanthanum cations (La 3+) are well known for their inhibitory actions on calcium channels. Prenatal lanthanum exposure may affect the development of embryo and alter the capacity for learning and memory in adults, and the one-trial passive avoidance learning paradigm with day-old chicks is an excellent model to study several mechanisms of memory formation. In the present study, we examined the effects of prenatal lanthanum chloride exposure on memory consolidation using one-trial passive avoidance learning task in day-old chicks. The data suggest that chicks injected with lanthanum chloride (2 mg/kg) daily from E9 to E16 had significantly impaired long-term memory at 120 min after training (p < 0.05) but not the chicks injected with lanthanum chloride (0.1 mg/kg) daily from E9 to E16.     

Effects of lipids on thermophilic anaerobic digestion and reduction of lipid inhibition upon addition of bentonite

Summary The effect of bentonite-bound oil on thermophilic anaerobic digestion of cattle manure was investigated. In digestor experiments, addition of oil was found to be inhibitory during start-up and the inhibitory effect was less pronounced when the oil was added in the form of bentonite-bound oil compared to when the oil was added alone. After adaption of the digestors, very rapid degradation of oil was observed and more than 80% of the oil was degraded within a few hours after daily feeding. In batch experiments, glyceride trioleate was found to be inhibitory to thermophilic anaerobic digestion when the concentrations were higher than 2.0 g/l. However, addition of bentonite (a clay mineral) at concentrations of 0.15% and 0.45% was found to partly overcome this inhibition. Addition of calcium chloride in concentration of 3 mM (0.033% w/v) showed a similar positive effect on the utilization of oil, but the effect was lower than with bentonite. Offprint requests to: I. Angelidaki     

乙酰胆碱门控氯离子通道受体突变影响秀丽线虫运动学和运动状态转换

目的 乙酰胆碱作为一种高度保守的神经递质，在动物的运动行为调控中起着至关重要的作用。乙酰胆碱信号转导异常可导致多种运动功能障碍。然而，乙酰胆碱在运动行为中的抑制性调控机制尚未完全清楚。本文以秀丽隐杆线虫为研究对象，探究乙酰胆碱门控氯离子通道受体亚基（ACC-1、ACC-2、ACC-3、ACC-4）在运动行为中的调控作用。方法 通过将运动追踪、分子遗传学和光遗传学技术相结合，对乙酰胆碱门控氯离子通道受体亚基突变线虫的运动进行分析。结果 研究发现，这些亚基突变会影响线虫前进、后退和转向运动的运动学特征，并且前进过程中线虫身体弯曲幅度也发生了变化。在这些突变线虫的后退过程中光激活RIB中间神经元会导致后退运动延迟终止。结论 这些结果提示，乙酰胆碱门控氯离子通道亚基的调控作用对于维持和调节秀丽隐杆线虫运动状态是必需的。同时，这些亚基可能参与介导RIB中间神经元在秀丽隐杆线虫后退运动中的抑制性调控。本研究为理解乙酰胆碱门控抑制性受体在运动行为中的调控机制提供了新的思路。     

Effect of temperature and sources of carbon and nitrogen on the conidial germination and appresoria formation in Colletotrichum capsici

The effect of temperatures and exogenous supply of different carbon and nitrogen sources on the conidial germination and appresoria formation inC. capsici has been studied. 25 °C was observed to be the best temperature for conidial germination. At 18 °C, conidia germinated only in hanging drops and did not germinate on 2 % agar. Amongst carbon sources, 1-rhamnose supported maximum conidial germination and appresoria formation. Potassium nitrate supported very good conidial germination and appresoria formation. Ammonium nitrate, ammonium sulphate and ammonium chloride were found to be inhibitory. A few aminoacids stimulated conidial germination but dl-alanine, dl-methionine, tyrosine and l-glutamine were found to be inhibitory.     

Effect of water activity on the growth and the production of cAMP phosphodiesterase inhibitor with Bacillus subtilis

Summary Bacillus subtilis C-756, a producer of cyclic adenosine 3,5-monophosphate (cAMP) phosphodiesterase inhibitor, was cultured in media adjusted to various water activity (a_w) levels by addition of three different solutes, sodium chloride, ethylene glycol and polyethylene glycol 1540 (PEG). B. subtilis C-756 can grow, however weakly, at a_w levels of 0.94 and 0.93.The presence of all three solutes in the medium inhibited growth, cell mass as well as inhibitor production. PEG was found to be most inhibitory, but the effect can not be explained in terms of a decreased water activity in the medium. It is rather the increased viscosity of the medium, which results in a decreased oxygen transfer rate.Comparing ethylene glycol and sodium chloride, the presence of ethylene glycol appears to favour inhibitor production, whereas sodium chloride favours cell mass production.     

Osmoregulation in Rhizobium meliloti: inhibition of growth by salts

A defined medium of low osmolarity was developed permitting growth of Rhizobium meliloti with generation times of approximately 2.8 h doubling^-1. The effects of sodium, potassium, magnesium, ammonium, chloride, sulfate, phosphate, bicarbonate and acetate ions on the growth rate of R. meliloti were determined. Sodium, potassium and ammonium ions had little effect on growth at concentrations of 100 mEq or less; magnesium ion inhibited growth severely at concentrations of 50 mEq (25 mM). Of the anions, chloride and sulfate appeared to have little effect while phosphate, bicarbonate, and acetate inhibited growth at concentrations of as little as 25 mEq. The addition of proline, glutamate, or betaine to cells growing in inhibitory concentrations of NaCl did not relieve the inhibition. When grown in the presence of inhibitory levels of NaCl, the intracellular concentration of glutamate but not of proline or gamma amino butyric acid increased 5-fold.     

Calcium and calmodulin inhibitor effects on the growth of carrot (Daucus carota L.) and radish (Raphanus sativus L.) in nutrient culture

Growth of carrot and radish seedlings in nutrient culture was inhibited by pretreatment with three calmodulin inhibitors. There was little selective effect on specific organs, shoots, tap root and fibrous roots over a range of concentrations. Although pretreatment with CaCl₂ (0.5 mM) did not affect growth of untreated seedlings, it partially reduced the inhibitory effects of trifluoperazine over the concentration range 0.01–0.05 mM. Trifluoperazine reduced the growth of GA₃-treated seedlings but did not overcome the modifying effect of GA₃ in favouring shoot/root ratio; ABA exacerbated its inhibitory effect on overall seedling growth and particularly on tap root development.Abbreviations GA₃ gibberellic acid - ABA abscisic acid - CaCl₂ calcium chloride - GAs gibberellins - Tfp trifluoperazine     

Stilbene derivatives inhibit the activity of the inner mitochondrial membrane chloride channels

Ion channels selective for chloride ions are present in all biological membranes, where they regulate the cell volume or membrane potential. Various chloride channels from mitochondrial membranes have been described in recent years. The aim of our study was to characterize the effect of stilbene derivatives on single-chloride channel activity in the inner mitochondrial membrane. The measurements were performed after the reconstitution into a planar lipid bilayer of the inner mitochondrial membranes from rat skeletal muscle (SMM), rat brain (BM) and heart (HM) mitochondria. After incorporation in a symmetric 450/450 mM KCl solution (cis/trans), the chloride channels were recorded with a mean conductance of 155 ± 5 pS (rat skeletal muscle) and 120 ± 16 pS (rat brain). The conductances of the chloride channels from the rat heart mitochondria in 250/50 mM KCl (cis/trans) gradient solutions were within the 70–130 pS range. The chloride channels were inhibited by these two stilbene derivatives: 4,4′-diisothiocyanostilbene-2,2′-disulfonic acid (DIDS) and 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid (SITS). The skeletal muscle mitochondrial chloride channel was blocked after the addition of 1 mM DIDS or SITS, whereas the brain mitochondrial channel was blocked by 300 μM DIDS or SITS. The chloride channel from the rat heart mitochondria was inhibited by 50–100 μM DIDS. The inhibitory effect of DIDS was irreversible. Our results confirm the presence of chloride channels sensitive to stilbene derivatives in the inner mitochondrial membrane from rat skeletal muscle, brain and heart cells.     

Physiological and morphological properties of the metathoracic common inhibitory neuron of the locust

Summary Intracellular recordings were made from the soma of the metathoracic common inhibitory neuron of the locustsSchistocerca andChortoicetes. The soma is passively invaded by a spike of 2–5 mV in amplitude. The response of the common inhibitor to a variety of different inputs was studied. Tests for coupling between the common inhibitory and excitatory motoneurons to the same or antagonistic muscles were made by simultaneous recordings from pairs of neuron somata. No low resistance or synaptically mediated coupling was found. The somata of the two common inhibitory neurons which supply muscles on opposite sides of the body lie together on the ventral surface of the ganglion on the mid-line (Fig. 6). They are not coupled in any way. Cobalt chloride injected into the common inhibitor has shown it to have an extensive and complex dendritic tree confined to the ipsilateral half of the ganglion (Fig. 8). A single branch extends into the mesothoracic ganglion. There are differences in the branching patterns of the dendrites in different animals (Fig. 10).Beit Memorial Research Fellow.     

SPECTROPHOTOMETRICALLY ASSAYED INHIBITORY EFFECTS OF MERCURIC COMPOUNDS ON ANABAENA FLOS-AQUAE AND ANACYSTIS NIDULANS (CYANOPHYCEAE)1

The growth-related inhibitory effects of mercuric chloride (MC), methylmercuric chloride (MMC) and phenylmercuric acetate (PMA) (each at 1, 10, 10,² 10³ ppb) were measured in Anabaena flos-aquae (Lyng.) Bréb. and Anacystis nidulans (Richt.) Drouet & Daily. Optical density changes of control cultures compared against those of experimental cultures showed that MC was the least inhibitory of the compounds. MMC. was the most inhibitory, producing statistically significant inhibition at a concentration as low as I ppb in Anabaena. PMA was more inhibitory than MC but less than MMC. Effects caused by the mercury compounds included bleaching of individual cells, cell size changes and destruction of whole cells; the degree and extent of these effects depended on the compound and its concentration in the nutrient medium. The high sensitivities of the algae tested suggested the possibility of using them as test organisms in bioassays for mercury.     

Time-dependent inhibition of inositol-1,4,5-trisphosphate-5-phosphatase by calmidazolium chloride in rat GH3 cells

The calmodulin inhibitor calmidazolium chloride inhibited the activity of soluble and particulate Ins(1,4,5)P₃-5-phosphatase from GH₃ cells, with an IC₅₀ value of 100 μM following a 10-min preincubation with enzyme. The inhibition was time-dependent and could not be reversed by washing of the particulate fraction. It is concluded that although the inhibitory effect of calmidazolium chloride cannot be related per se to inhibition of calmodulin function, effects of this compound unrelated to actions upon calmodulin function may be found when concentrations that are only moderately supramaximal are used.     

Patch clamp study and kinetic modeling on the most abundant chloride channel on distal fibers of crayfish opener muscle

Whereas the inhibitory innervation of the deep extensor abdominal muscle in crayfish is mediated by a weakly acting common inhibitor, the opener muscle exhibits a stronger inhibition. In the present study the most abundant γ-aminobutyric acid-activated chloride channel on distal fibers of crayfish opener muscle was characterized by measuring the current responses after applying pulses of γ-aminobutyric acid to outside-out patches. The results were compared to those obtained earlier with the chloride channel on the deep extensor abdominal muscle of the same species. The double logarithmic plot of the dose-response relationship had a slope of n _H = 2.2 in contrast to n _H = 5.3 for the channel on the deep extensor abdominal muscle. The rise time of the current response declined to 1 ms at a γ-aminobutyric acid concentration of 50 mmol · l⁻¹. With lower concentrations the rise time increased to a maximal value of 280 ms. No peak of the rise time at low γ-aminobutyric acid concentrations, as observed for the channel on the deep extensor abdominal muscle, was obvious. The open and closed times were similar to those of the channel of the deep extensor abdominal muscle. Different reaction schemes were discussed to describe the kinetics of the chloride channel of the opener muscle. Accepted: 12 August 1996     

Determination of the sensitivity of bacteria to barium ions,a taxonomic marker of the genus <Emphasis Type="Italic">Pseudomonas</Emphasis>

Comparative efficacy of the determination of the sensitivity of bacterial cells to barium ions was evaluated on a synthetic nutrient medium, FMH agar, Mueller-Hinton agar, and AGV agar. The synthetic nutrient medium developed for this study contained L-proline and L-glutamine as the sole nitrogen and carbon source, which promoted growth of all Pseudomonas strains and ensured the minimal level of barium binding. The sensitivity of 80 strains belonging to 11 Pseudomonas species, including the type strains, as well as of 80 strains of 22 other bacterial species, was studied. The sensitivity of bacteria to barium ions was determined by using serial dilutions of barium chloride in the nutrient medium. The highest level of analytical sensitivity of pseudomonads to barium ions was determined on the synthetic nutrient medium: the minimal inhibitory concentration (MIC) values of barium chloride ranged from 0.5 to 6 g/L, the MIC₉₀ value was 2 g/L. At the same time, 86.1% of all strains of fluorescent Pseudomonas species produced fluorescein on the control BaCl₂-free synthetic nutrient medium. For representatives of other genera grown on all the studied nutrient media, the MIC values of barium chloride ranged from 20 to 50 g/L. The proposed method for determination of the sensitivity of bacteria to barium ions using the synthetic nutrient medium with 6 g/L of barium chloride as a criterion for the classification of barium-sensitive strains to the genus Pseudomonas is suitable for standardization.     

Calcium inhibition of efrotomycin production byNocardia lactamdurans

Summary Efrotomycin is a modified polyketide antibiotic of the elfamycin family that has use in the area of pig husbandry. Optimization of the fermentation medium for production of efrotomycin byNocardia lactamdurans revealed that the fermentation is sensitive to hard water and certain lots of cottonseed flour used to prepare a complex fermentation medium. A limited metal ion analysis of the hard water indicated that calcium ions are present at concentrations found to be inhibitory by the addition of calcium chloride to medium prepared with distilled water. Similarly, a correlation between lots of cottonseed flour that poorly supported the fermentation and high calcium levels is presented. Further experimentation revealed that by altering the sterilization conditions of the cottonseed flour, the inhibitory effect of poor lots could be prevented.     

Inhibitory activity of sulphoglycolipid derivatives towards pancreatic trypsin

Amphipathic sulpholipids have been shown to inhibit pancreatic serine proteases due to their detergent-like properties. To evaluate the structural requirement for this inhibitory activity, we examined the effects of various derivatives of sulphoglycolipids, some of which were prepared by deacylation with sphingolipid ceramide N-deacylase, followed by acylation with acyl chloride, on the activity of pancreatic trypsin. Both deacylated sulphatides and seminolipids exhibited inhibitory activity towards trypsin without any requirement for solubilisation and preincubation. On the other hand, stronger inhibition was observed for acylated sulphatides than for deacylated ones, but increasing the chain length of the fatty acid moiety resulted in the need for a solubilisation agent and preincubation in order to achieve maximal inhibitory activity. The structural isomers of sulphoglycolipids, such as I⁶SO₃-GalCer, and phytosphingosine- and diglyceride-containing sulphoglycolipids, showed similar inhibitory activity, indicating the involvement of sulphate and hydrophobic groups, irrespective of the fine structure, in the inhibition. Among the sulphoglycolipids examined, II³SO₃-LacCer was found to exhibit the highest inhibitory activity.     

Effect of calcium on the performance and morphology ofZymomonas mobilis ATCC 29191 in continuous ethanol fermentations

Summary The effect of calcium chloride, over a concentration range of 0–40mM (equivalent to 0–5.88g/L), on various steady-state parameters associated with the chemostat culture ofZ. mobilis ATCC 29191, in a defined salts medium containing 100g/L glucose, was examined. In contradiction of reports by other authors that calcium chloride (>2g/L) inhibits both the growth rate and ethanol yield while at the same time increasing the biomass yield, it was observed in the present study that 25mM (3.7g/L) CaCl₂ did not appreciably affect any of these fermentation parameters. The D_max (dilution rate for 95% substrate utilization) of 0.22/hr was not affected until the concentration of calcium chloride exceeded 30mM (4.41g/L). The apparent increase in biomass yield produced by calcium can be attributed to the formation of insoluble calcium carbonate. Calcium induced morphological changes of the biomass with filamentous growth were seen at concentrations >30 mM. Sparging with nitrogen gas reduces the dissolved carbon, dioxide, lessens the apparent inhibitory effect of calcium on the ethanol productivity and decreases the degree of filament formation.     

Inhibition of Acetylcholinesterase by three New Pyridinium Compounds and their Effect on Phosphonylation of the Enzyme

Abstract

Three new mono-pyridinium compounds were prepared: 1-phenacyl-2-methylpyridinium chloride (1), 1-benzoylethylpyridinium chloride (2) and 1-benzoylethylpyridinium-4-aldoxime chloride (3) and assayed in vitro for their inhibitory effect on human blood acetylcholinesterase (EC 3.1.1.7, AChE). All the three compounds inhibited AChE reversibly; their binding affinity for the enzyme was compared with their protective effect (PI) on AChE phosphonylation by soman and VX. Compound 1 was found to bind to both the catalytic and the allosteric (substrate inhibition) sites of the enzyme with estimated dissociation constants of 6.9 μM (K_cat) and 27 μM (K_all), respectively. Compound 2 bound to the catalytic site with K_cat= 59 μM and compound 3 only to the allosteric site with K_all = 328 μM. PI was evaluated from phosphonylation measured in the absence and in presence of the compounds applied in a concentration corresponding to their K_cat or K_all value, and was also calculated from theoretical equations deduced from the reversible inhibition of the enzyme. Compounds 1 and 3 protected the enzyme from phosphonylation by soman and VX, whereas no protection was observed in the presence of compound 2 under the same conditions. Irrespective of the binding sites to AChE, PI for compounds 1 and 3 evaluated from phosphonylation agreed with PI calculated from reversible inhibition. Compound 3 was found to be a weak reactivator of methylphosphonylated AChE with k_r = 1.1 × 10²Lmol^-1 min^-1.     

The Effect of Some Inhibitory Sugars upon the Content of Adenosine Triphosphate in Wheat Roots

The content of adenosine triphosphate (ATP) in roots of -wheat (Triticum aestivum L.) was determined with the fire-fly-luciferase method. The content is decreased by D-mannose, which inhibits root growth, respiration and chloride uptake. In intact seedlings the inhibition of root growth is relieved by other sugars and also by the flavanone naringenin and by 2,4-dinitrophenol. This reversal is combined with an increased content of ATP. The inhibition of chloride uptake by mannose in excised roots is reversed by some other sugars (including D-galactose which is in itself inhibitory to root growth), and also in this case the ATP content is increased. Naringenin and dinitrophenol do not relieve the inhibition of chloride uptake caused by mannose. Nor do they increase the content of ATP in this case. The primary effect of mannose seems to be inhibition of glycolysis whereas the effect upon root growth is secondary. Galactose, which also inhibits root growth, does not inhibit respiration or reduce the ATP content and the primary effect of galactose (and also of 2-deoxy-D-glucose and 2-deoxy-D-galactose) seems to be on the synthesis of cell wall substances.