A Comparison of the Effects of Ethanol and the Competitive Glycine Antagonist 7-Chlorokynurenic Acid on N-Methyl-d-Aspartic Acid-Induced Neurotransmitter Release from Rat Hippocampal Slices

Abstract: N -Methyl- d -aspartate (NMDA; 500 μ M ) stimulated the net release of preloaded tritiated norepinephrine from rat hippocampal slices. Both ethanol and the competitive glycine antagonist 7-chlorokynurenic acid (7-CK) dose-dependently inhibited NMDA-stimulated release without affecting basal, nonstimulated efflux. These inhibitory effects were readily reversed upon washout of the drugs. Over the concentration range tested (25–200 m M ), ethanol inhibited ∼65% of NMDA-stimulated release with an estimated IC₅₀ of ∼70 m M . In contrast, 7-CK fully inhibited release (>95%) at a concentration of 30 μ M with half-maximal inhibition occurring at ∼2 μ M . The combination of 7-CK (1–30 μ M ) and ethanol (25–100 m M ) had an additive inhibitory effect on NMDA-stimulated release but did not alter the inhibitory potency of 7-CK. Calculated IC₅₀values for 7-CK in the presence of 25, 50, or 100 m M ethanol were (mean × SEM; μ M ) 2.33 (0.11), 2.38 (0.23), and 1.99 (0.30), respectively. 7-CK (3 μ M ) inhibited NMDA-stimulated [³H]norepinephrine release by ∼50%. This inhibition was fully attenuated by the addition of the glycine agonistserine with complete reversal occurring at 30 μ M d -serine. Increasing the 7-CK concentration to 10 μ M shifted the d -serine dose-effect curve to the right in a parallel fashion as expected for a competitive antagonist. In contrast, the inhibitory effects of ethanol or the combination of 7-CK (3 μ M ) and ethanol (25 or 50 m M ) were not reversed by the addition of d -serine (0.1–1,000 μ M ). Together, these results suggest that ethanol's inhibition of NMDA-stimulated [³H]norepinephrine release from hippocampal slices is not due to a simple competitive interaction with the glycine site on the NMDA receptor.     

黄绿绿僵菌Mf82悬乳剂对褐飞虱作用的时间-剂量-死亡率模型分析

为了寻找褐飞虱Nilaparvata lugens生物防治的新途径,用新分离出的黄绿绿僵菌Metarhiziumflavoviride(Mf82)菌株与实验室保存的黄绿绿僵菌、金龟子绿僵菌和球孢白僵菌3种菌种9个菌株作对比,测定了它们对褐飞虱成虫的毒力。结果表明:Mf82菌株对褐飞虱成虫的毒力最高,以1.0×108个孢子/mL的孢子液喷雾接种到褐飞虱成虫体表上,累积死亡率高达81.7%,LT50为4.6d,致病效果显著高于其他受测菌株。在此基础上研制了黄绿绿僵菌悬乳剂,并研究了其对褐飞虱的致病力。结果表明:随着黄绿绿僵菌浓度的增加,褐飞虱的累计死亡率增加,在浓度为1,048个孢子/mm2时,累计死亡率达到85.0%。利用时间-剂量-死亡率模型对数据进行处理,所建模型均顺利通过Hosmer-Lemeshow拟合异质性检验,表明模型拟合良好,并由模型估计出了该剂型对褐飞虱的致死剂量与致死时间。在接种后第7天和第9天,LC50值分别为2.1×103、9.9×102个孢子/mm2,LC90分别为7.8×104、3.7×104个孢子/mm2。黄绿绿僵菌悬乳剂对褐飞虱的致死时间与对数剂量相关,供试菌剂LT50值随着对数剂量的增加而递减,对数剂量由7.0增加到8.0时,LT50由8.9d降为5.7d。可见该黄绿绿僵菌悬乳剂对褐飞虱具有较强的毒力,在褐飞虱生物防治中具有广阔的应用前景。     

The cAMP signal from Dictyostelium discoideum amoebae.

Dictyostelium discoideum cells were allowed to differentiate on agar for 600 min at room temperature. All of the cells were then competent to relay or amplify a cAMP signal, but none to produce a cAMP signal autonomously. The cells were stimulated with cAMP concentrations ranging from 10^?9 to 3.5 × 10^?7M. Populations of 10⁶ cells could amplify an initial cAMP concentration of 2.5 × 10^?9M with a low probability, while an initial cAMP concentration of 5 × 10^?8M always induced a response. An initial cAMP concentration of 1.2 × 10^?7M induced the maximum cellular release of cAMP observed; this corresponded to 3 × 10⁷ molecules per cell. No cellular release of cAMP was detected for initial cAMP concentrations of 3 × 10^?7M or more. The amplification of a 10^?7M cAMP stimulus was complete within 8 sec, indicating the pulsatile nature of the cellular release of cAMP. The phosphodiesterase (PDE) activities of D. discoideum cells were measured over a wide range of cell densities. At densities above 7.5 × 10⁴ cells/cm², both cell-bound and extracellular (ePDE) activities declined, per cell, as cell density increased. These results are compared to ePDE activities derived from critical density measurements. We found that PDE activities were in the range of 10^?13–10^?14 moles of cAMP converted/cell/min under culture conditions consistent with normal aggregation.     

Yeast Cell Microcapsules as a Novel Carrier for Cholecalciferol Encapsulation: Development,Characterization and Release Properties

In this study Saccharomyces cerevisiae yeast cells was used as a novel vehicle for encapsulation of vitamin D₃. The effects of initial cholecalciferol concentration (100,000 and 500,000 IU/g yeast), yeast cell pretreatment (plasmolysis with NaCl) and drying method (spray or freeze drying) on microcapsules properties were investigated. It was found that the vitamin concentration and drying method had significant influence on encapsulation efficiency (EE) and size of yeast microcapsules. Furthermore, EE values were more increased by the plasmolysis treatment. The highest EE was obtained for plasmolysed and spray dried yeast cells prepared using initial cholecalciferol concentration of 2.5 mg per gram of yeast cells (76.10?±?6.92%). The values of mean particle size were 3.43–7.91 μm. The presence of cholecalciferol in yeast microcapsules was confirmed by X-ray diffraction (XRD) and Fourier transform-infrared (FT-IR) analyses. The in vitro cholecalciferol release from yeast microcapsules in phosphate buffer saline solution (PBS) followed a controlled release manner consistent with a Fickian diffusion mechanism. In addition, the release studies in simulated gastrointestinal tract showed sustained release of cholecalciferol in the stomach condition and significant release in intestinal medium.     

CHARACTERISTICS OF ACETYLCHOLINE RELEASE BY SUPERFUSED SLICES OF RAT BRAIN1

—A superfusion system has been used to examine the effects of choline and the utilization of [³H]choline during resting and potassium-stimulated release of ACh from rat cerebrum slices. The rate of ACh release from unstimulated tissue, 0·25 nmol/g per min, increased 8-fold when the concentration of KCl in the superfusing medium was increased from 5 to 50 mm . This rate was not maintained, however, but gradually declined to one-half the peak rate after approx. 30 min. After an initial washout period, choline was released at a rate of 2·5-5 nmol/g per min, which was equal to 1-2 × 10^?6m in the superfusate. The addition of 1 × 10^?5m -choline to the superfusing medium was required to maintain the stimulated ACh release at near peak rates for 90 min. When hemicholinium-3 was added to the 50 mm -KCl medium, the release of ACh reached a peak as usual but then declined to prestimulation rates. After introducing a pulse of radioactive choline in the superfusing medium, the specific radioactivity of choline and ACh in the superfusate was determined before and during stimulation with 50 mm -KCl. The specific radioactivity of released ACh was always greater than that of released choline; it decreased rapidly at the onset of stimulation, and then more gradually as stimulation proceeded. The specific radioactivity of ACh released in the initial minutes of stimulation was higher than that of ACh in the tissue before stimulation. In the last 10-20 min of stimulation the specific radioactivity of the released ACh was lower than that of the tissue ACh at the end of stimulation. The relative contributions of old and newly synthesized ACh to the releasable transmitter pool are discussed.     

Behavioural responses of sablefish, Anoplopoma fimbria, to bait odour

A behavioural bioassay was used to determine the response threshold to squid extract of sablefish, Anoplopoma fimbria, held at three different feeding regimens. Sablefish responded to the odour of bait by changing swimming activity and turning behaviour. The response threshold to bait odour was influenced by both the amount of food eaten and the duration of food deprivation. The total concentration of amino acids in the bait extract was assumed to determine the response threshold as chemical fractionation studies have shown that this class of compounds is essential for the stimulatory capacities of food extracts. When fed to satiation (9.4% wet body weight) and tested after one day of food deprivation, the mean response threshold to total dissolved free amino acids was 4.4 × 10^?8m (range=7.6 × 10^?8 to 3.6 × 10^?8m ). When fed at 1.6-2.3% wet body weight, the threshold sensitivity had increased to a mean value of 1.8 × 10^?10m (range=8.4 × 10^?10 to 7.0 × 10^?11m ) after one day of food deprivation; after four days of deprivation, the sensitivity had increased even further to a mean value of 1.4 × 10^?11m (range=1.6 × 10^?10 to 1.4 × 10^?12m ). It was also apparent that the intensity of behavioural responses to the bait odour increased with both stimulus concentration and duration of food deprivation. These results suggest that sablefish intensify their search for prey under increased feeding motivation. The active space of a bait source was estimated from the threshold values obtained. Depending on state of food deprivation, rate of chemical release from the bait and the current velocity, maximum lengths of active space within which sablefish would exhibit food searching responses vary from 10 m to several km. Stock assessment based on catch data from baited gear will need techniques that take into account those factors influencing active space for food searching.     

苏云金芽胞杆菌HA和HD对黄曲条跳甲成虫的毒力分析

黄曲条跳甲Phyllotreta striolata (Fabricius)是为害十字花科蔬菜的世界性害虫之一.为了探究苏云金芽胞杆菌HA和HD对黄曲条跳甲成虫的防治潜力,本研究测定了苏云金芽胞杆菌HA和HD菌株对黄曲条跳甲成虫的毒力,以及对其谷胱甘肽-S-转移酶(GST)活性和中肠组织形态的影响.结果 表明:Bt-HA和Bt-HD均对黄曲条跳甲成虫有杀虫活性,LC50分别为4.01×108 CFU/mL和1.17×108 CFU/mL.菌株Bt-HD处理组的GST酶活性高于对照组和菌株Bt-HA处理组.菌株Bt-HA处理黄曲条跳甲成虫14 d后,中肠微绒毛肿胀脱落;菌株Bt-HD处理黄曲条跳甲成虫4d后中肠微绒毛开始疏松脱落,14 d后中肠柱状细胞底膜变形脱落.综上所述,苏云金芽胞杆菌HD对黄曲条跳甲成虫的毒力更强,是防治黄曲条跳甲成虫的优势菌株,其杀虫机理值得深入研究.     

The effect of epostane (Win32739), an inhibitor of 3β-hydroxy steroid dehydrogenase,on luteal function and gonadotrophin secretion in cows

Six cows were injected i.m. with either 4 × 125 mg or 4 × 250 mg of the 3β-hydroxy steroid dehydrogenase inhibitor epostane (Win32729) at 12-h intervals during the luteal phase of the oestrous cycle. Four more cows received 1 × 1 g epostane i.m. In all cows there was a transient decrease in plasma progesterone concentrations beginning within 8 h of the first injection, the decrease being more rapid and greater in the group receiving 1 × 1 g epostane. However, progesterone concentrations did not reach basal values and no preovulatory LH or FSH surges occurred. Progesterone concentrations invariably returned to pre-injection values within a few days and the length of the oestrous cycle was not affected. During the treatment period there were significant negative correlations between mean plasma LH and progesterone concentrations.     

Pharmacokinetics and pharmacodynamics of ch14.18/CHO in relapsed/refractory high-risk neuroblastoma patients treated by long-term infusion in combination with IL-2

Ch14.18 manufactured in Chinese hamster ovary (CHO) cells is currently being evaluated in clinical trials. Short-term infusion (STI) (8–20 h/day; 4–5 days) of 100 mg/m2 ch14.18/CHO (dinutiximab β) per cycle in combination with cytokines is standard treatment of neuroblastoma (NB) patients. As pain is a limiting factor, we investigated a novel delivery method by continuous long-term infusion (LTI) of 100 mg/m2 over 10 days. 53 NB patients were treated with 5–6 cycles of 6 × 106 IU/m2 subcutaneous interleukin-2 (d 1-5, 8-12), LTI of 100 mg/m2 ch14.18/CHO (d 8-18) and 160 mg/m2 oral 13-cis-retinoic acid (d 22-35). Human anti-chimeric antibody (HACA), antibody-dependent cell-mediated cytotoxicity and complement-dependent cytotoxicity were determined. With LTI, we observed a maximum concentration of ch14.18/CHO (Cmax) of 12.56 ± 0.68 µg/ml and a terminal half-life time (t1/2 β) of 32.7 ± 16.2 d. The clearance values for LTI and STI of 0.54 ± 0.13 and 0.41 ± 0.29 L/d m2 and area under the serum concentration-time curve (AUC) values of 189.6 ± 41.4 and 284.8 ± 156.8 µg×d/ml, respectively, were not significantly different. Importantly, we detected ch14.18/CHO trough concentration of ≥ 1 µg/ml at time points preceding subsequent antibody infusions after cycle 1, allowing a persistent activation of antibody effector mechanisms over the entire treatment period of 6 months. HACA responses were observed in 10/53 (19%) patients, similar to STI (21%), indicating LTI had no effect on the immunogenicity of ch14.18/CHO. In conclusion, LTI of ch14.18/CHO induced effector mechanisms over the entire treatment period, and may therefore emerge as the preferred delivery method of anti-GD2 immunotherapy to NB patients.     

GABA Autoreceptors Are Not Coupled to Benzodiazepine Receptors in Rat Cerebral Cortex

Abstract: Depolarization-induced release of [³H] γ -aminobutyric acid ([³H]-GABA) from preloaded slices of rat cerebral cortex was inhibited by muscimol and THIP in a dose-dependent fashion. This inhibition of release was prevented by the GABA antagonists bicuculline and picrotoxin. These results confirm previous reports postulating the existence of GABA autoreceptors on GABAergic terminals. Since benzodiazapines are known to facilitate postsynaptic GABA actions, the effect of flunitrazepam on the inhibition of GABA release mediated through the autoreceptors has been examined. At a concentration of 1 μ m or 10 μ m , flunitrazepam had no effect on the IC₅₀ values for muscimol or THIP in inhibiting stimulated GABA release. It thus seems that GABA autoreceptors are not functionally coupled to benzodiazepine receptors in rat cerebral cortex.     

Human cochlear hydrodynamics: A high-resolution μCT-based finite element study

Measurements of perilymph hydrodynamics in the human cochlea are scarce, being mostly limited to the fluid pressure at the basal or apical turn of the scalae vestibuli and tympani. Indeed, measurements of fluid pressure or volumetric flow rate have only been reported in animal models. In this study we imaged the human ear at 6.7 and 3-µm resolution using µCT scanning to produce highly accurate 3D models of the entire ear and particularly the cochlea scalae. We used a contrast agent to better distinguish soft from hard tissues, including the auditory canal, tympanic membrane, malleus, incus, stapes, ligaments, oval and round window, scalae vestibule and tympani. Using a Computational Fluid Dynamics (CFD) approach and this anatomically correct 3D model of the human cochlea, we examined the pressure and perilymph flow velocity as a function of location, time and frequency within the auditory range. Perimeter, surface, hydraulic diameter, Womersley and Reynolds numbers were computed every 45° of rotation around the central axis of the cochlear spiral. CFD results showed both spatial and temporal pressure gradients along the cochlea. Small Reynolds number and large Womersley values indicate that the perilymph fluid flow at auditory frequencies is laminar and its velocity profile is plug-like. The pressure was found 102–106° out of phase with the fluid flow velocity at the scalae vestibule and tympani, respectively. The average flow velocity was found in the sub-µm/s to nm/s range at 20–100 Hz, and below the nm/s range at 1–20 kHz.     

Simultaneous chiral analysis of amphetamine‐type stimulants and ephedrine by capillary electrophoresis coupled to time‐of‐flight mass spectrometry

This study focused on the chiral characteristics of methamphetamine seizures in Shanghai for inferring the synthetic pathways of drugs. Capillary electrophoresis coupled to time‐of‐flight mass spectrometry was used for simultaneous chiral separation of amphetamine‐type stimulants and ephedrine, including S(+)‐amphetamine/R(?)‐amphetamine, S(+)‐methamphetamine/R(?)‐methamphetamine, (±)‐MDA (3,4‐methylenedioxyamphetamine), (±)‐MDMA (3,4‐methylenedioxymethamphetamine), (±)‐MDEA (3,4‐methylenedioxy‐N‐ethylamphetamine), d,l‐N‐ethylamphetamine, methylephedrine/methylpseudoephedrine, and 1S,2R(+)‐ephedrine/(?)‐ephedrine. The running buffer was 50‐mM ammonium formate (pH 2.2 was adjusted by 1‐M formic acid) containing 0.26% highly sulfated γ‐cyclodextrin as the chiral selector. All enantiomers were well resolved within 40 minutes by capillary electrophoresis at 20 kV in an uncoated fused‐silica capillary (50‐μm I.D. × 375‐μm O.D. × 90‐cm length) and detected by micro time‐of‐flight mass spectrometry. Twenty seized methamphetamine samples were determined by the established method. They were classified into two groups through their chiral characteristics.     

Effect of Drug Loading Method on Drug Content and Drug Release from Calcium Pectinate Gel Beads

Drug-loaded calcium pectinate gel (CaPG) beads were prepared by either mixing, absorption, or swelling method. The effects of drug loading method as well as the drug loading factors (i.e., drug concentration, soaking time in drug solution, type of solvent) on drug content and drug release were investigated. The amount of drug uptake (i.e., drug content) into CaPG beads increased as the initial drug concentration increased and varied depending on the loading method. The in vitro release studies in 0.1 N hydrochloric acid (HCl) and pH 6.8 buffer indicated that the drug loading method affected drug release and release parameter, time for 50% of drug release (T ₅₀). The mixing method provided a faster drug release and lower T ₅₀ than the absorption method and swelling method, respectively. This is probably due to higher drug content in CaPG beads. The increased concentration of drug in soaking solution and soaking time resulted in higher drug content and thus faster drug release (lower in T ₅₀ values). When using 0.1 N HCl as solvent for soaking instead of water, the drug release was slower owing to the increase in molecular tortuosity of CaPG beads. The drug release was also affected by pH of the release medium in which drug release in 0.1 N HCl was faster than in pH 6.8 buffer.     

Latent and active forms of collagenase in rat uterine explant cultures: regulation of conversion by progestational steroids

A latent collagenase, activatable by trypsin, has been identified in the culture media of postpartum rat uterus explants. Progesterone at a concentration of 25 × 10^?6m reduced the level of active collagenase by approximately 50%, whereas, total enzyme levels (active + latent) remained essentially constant during the first 3 days of culture. In addition, medroxyprogesterone acetate at a concentration of 1 × 10^?6m reduced active enzyme by approximately 75% while only small decreases in total enzyme were observed. After the third day of culture, total enzyme levels were also significantly decreased. These data suggest that during the first 3 days in culture the progestins prevent the conversion of latent collagenase to its active form. A fraction capable of promoting the activation of explant collagenase was detected in the culture medium and was partially separated from the collagenase. Progesterone (25 × 10^?6m) or medroxyprogesterone acetate (1 × 10^?6m) caused a 50 or 71% decrease, respectively, in the levels of the activator.     

Does the setup of Monte Carlo simulations influence the calculated properties and effect of gold nanoparticles in radiation therapy?

PurposeTo investigate whether the dose-scoring process of Monte Carlo (MC) simulations of Gold nanoparticles (GNPs) in radiation therapy affects the results.MethodsThe GATE MC toolkit was used to simulate the irradiation of a water phantom containing a single solid or hollow GNP with 250 kVp and 6 MV photons. The dose was scored in 20 nm × 20 nm × 50 μm, 100 nm × 100 nm × 50 μm and 200 nm × 200 nm × 50 μm volumes using dose-scoring voxels of size 1 nm × 1 nm × 50 μm, 10 nm × 10 nm × 50 μm, 50 nm × 50 nm × 50 μm and 100 nm × 100 nm × 50 μm Εxcess dose depth-dose (EDDD) curves and lateral beam profiles were used to compare the dose-scoring voxels.ResultsIn a given volume, neither the EDDD curves nor the lateral beam profiles are affected by the size of the dose-scoring voxels, subject to noise and uncertainty. Certain features of the EDDD curves are clearly seen in larger volumes, but hidden within the uncertainty and noise levels in smaller volumes. For the lateral beam profiles, it is the larger volumes that result in misleading results and the smaller ones that give the expected results. However, the limited statistics result in asymmetries and skewness in the profiles.ConclusionFor a given volume, the dose curves are not affected by the size of the dose-scoring voxels. However, the voxel size may hide or reveal the finer structure of the dose curves and/or may result in misleading curves.     

In vivo release kinetics of octreotide acetate from experimental polymeric microsphere formulations using oil/water and oil/oil processes

The purpose of the present study was to characterize the in vivo release kinetics of octreotide acetate from microsphere formulations designed to minimize peptide acylation and improve drug stability. Microspheres were prepared by a conventional oil/wate (o/w) method or an experimental oil/oil (o/o) dispersion technique. The dosage forms were administered subcutaneously to a rat animal model, and serum samples were analyzed by radioimmunoassay over a 2-month period. An averaged kinetic profile from each treatment group, as a result, was treated with fractional differential equations. The results indicated that poly(l-lactide) microspheres prepared by the o/o dispersion technique provided lower area under the curve (AUC) values during the initial diffusion-controlled release phase, 7.79 ng×d/mL, versus 75.8 ng/sxd/mL for the o/w batch. During the subsequent erosion-controlled release phase, on the other hand, the o/o technique yielded higher AUC values, 123 ng×d/mL, versus 42.2 ng×d/mL for the o/w batch. The differences observed between the 2 techniques were attributed to the site of drug incorporation during the manufacturing process, given that microspheres contain both porous hydrophilic channels and dense hydrophobic matrix regions. An o/o dispersion technique was therefore expected to produce microspheres with lower incorporation in the aqueous channels, which are responsible for diffusion-mediated drug release.     

L-Oxothiazolidine 4-carboxylate pretreatment of isolated human peripheral blood lymphocytes reduces sulfur mustard cytotoxicity

Sulfur mustard (HD, mustard gas) is a vesicant chemical warfare agent for which there is no specific medical countermeasure. A potential approach to combating the debilitating effects of this agent is the use of compounds that can react with this material before it interacts with critical macro-molecules. Glutathione (GSH), a tripeptide that exists in high concentrations in cells, reacts with HD and is involved in HD detoxification. Pretreatment of human peripheral blood lymphocytes (PBL) with 10 mmol/L L-oxothiazolidine-4-carboxylate (OTC), a "masked" cysteine precursor, increased intracellular glutathione levels 25-50% over control values. Pretreated PBL were harvested, washed, and exposed to 10, 50, or 100 µmol/L HD. Flow cytometry was used to measure cytotoxicity by propidium iodide uptake. Pretreatment of PBL with OTC led to small decreases in cytotoxicity after HD exposure. However, treatment of cells with OTC after HD exposure was not beneficial. Compounds that can modulate GSH levels within the cell may help to reduce the cytotoxicity of HD when used as a pretreatment.     

Transformation of individual contractile responses during tetanus in rat fast and slow skeletal muscles

Using a computer graphics approach, the last contractile responses (LCR_N, where N is a number of elementary contractile responses in tetanus) were separated from integral tetanic responses of rat fast muscles, m. Eхtensor digitorum longus (m. EDL), and slow muscles, m. Soleus, evoked by trains of 5, 10 and 50 stimuli. In m. Soleus, at a stimulation frequency of 20 Hz, the LCR₅ average amplitude decreased to 64 ± 9% compared to the single contraction amplitude. As N increased, LCR_N recovered and then rose to the values exceeding almost twofold initial elementary contractile responses (up to 211 ± 10% for LCR₅₀). Simultaneously, against the background of rising elementary contractile responses, a significant shortening of their half-decay time (～by 50%) and the formation of a stationary plateau within LCR_N was observed. In m. EDL, at a stimulation frequency of 50 Hz, there was only a single-phase LCR_N rise (up to 165 ± 18% for LCR₅₀) without changes in half-decay time and plateau formation. In skeletal muscles of both types, the prolonged (up to 30 s) ‘hyper-relaxation effect’ was found to develop after the end of tetanic responses manifested as a reduction of muscle tension followed by its recovery to the initial level. Possible mechanisms of these events are discussed. It is hypothesized that transformation of elementary contractile responses in skeletal muscles can be fulfilled due to the existence of specialized microdomains in muscle fibers which regulate accumulation and extrusion of Ca²⁺ ions during tetanic activity. The possibility that the basic, depolarization-induced, Ca²⁺ release (DICR) is complemented by an additional, Ca²⁺-induced, Ca²⁺release (CIRC) is analyzed.     

Pathogenicity of entomopathogenic fungus,Metarhizium anisopliae MET-GRA4 isolate on dengue vectors,Aedes albopictus and Aedes aegypti mosquito larvae (Diptera: Culicidae)

Considering the rapid transmission of the dengue virus, substantial efforts need to be conducted to ward-off the epidemics of dengue viruses. The control effort is depending on chemical insecticides and had aroused undesirable conflicts of insecticide resistance. Here, we study the entomopathogenic fungus, Metarhizium anisopliae as a promising new biological control agent for vector control. The pathogenicity effects of Metarhizium anisopliae against field and laboratory strains of Aedes albopictus and Aedes aegypti larvae were tested using the larvicidal bioassay technique. The results demonstrate that the treatments using M. anisopliae isolate MET-GRA4 were highly effective and able to kill 100% of both Ae. albopictus and Ae. aegypti mosquito larvae at a conidia concentration of 1 × 10?/ml within 7 days of the treatment period. The fungus displayed high larvicidal activity against laboratory and field strain of Ae. aegypti larvae with LC₅₀ values (9.6 × 10³/ml, 1.3 × 10³/ml) and LC₉₅ values (1.2 × 10?/ml, 5.5 × 10⁵/ml) respectively. For Ae. albopictus, LC₅₀ values for laboratory and field strains were (1.7 × 10⁴/ml, 2.7 × 10⁴/ml) and the LC₉₅ values were (2.1 × 10?/ml, 7.0 × 10⁵/ml) respectively. Interestingly, the susceptibility of field strain towards M. anisopliae was higher as compared to the laboratory strain Aedes larvae. In which, the causative agents of all the dead larvae were verified by the virulence of M. anisopliae and caused morphological deformities on larval body. The findings from this study identify this isolate could be an effective potential biocontrol agent for vector mosquitoes in Malaysia.