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•The KATP channel antagonist tolbutamide decreases honey bee heart rate.•The KATP channel agonist pinacidil has a biphasic effect on honey bee heart rate.•The cations barium and ...magnesium decrease honey bee heart.•Barium pretreatment alters the cardiac effects of pinacidil and tolbutamide.
ATP-sensitive inwardly rectifying potassium (KATP) channels couple cellular metabolism to the membrane potential of the cell and play an important role in a variety of tissue types, including the insect dorsal vessel, making them a subject of interest not only for understanding invertebrate physiology, but also as a potential target for novel insecticides. Most of what is known about these ion channels is the result of work performed in mammalian systems, with insect studies being limited to only a few species and physiological systems. The goal of this study was to investigate the role that KATP channels play in regulating cardiac function in a model social insect, the honey bee (Apis mellifera), by examining the effects that modulators of these ion channels have on heart rate. Heart rate decreased in a concentration-dependent manner, relative to controls, with the application of the KATP channel antagonist tolbutamide and KATP channel blockers barium and magnesium, whereas heart rate increased with the application of a low concentration of the KATP channel agonist pinacidil, but decreased at higher concentrations. Furthermore, pretreatment with barium magnified the effects of tolbutamide treatment and eliminated the effects of pinacidil treatment at select concentrations. The data presented here confirm a role for KATP channels in the regulation of honey bee dorsal vessel contractions and provide insight into the underlying physiology that governs the regulation of bee cardiac function.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Acetylcholinesterase (AChE) is a proven target for control of the malaria mosquito (Anopheles gambiae). Unfortunately, a single amino acid mutation (G119S) in An. gambiae AChE-1 (AgAChE) confers ...resistance to the AChE inhibitors currently approved by the World Health Organization for indoor residual spraying. In this report, we describe several carbamate inhibitors that potently inhibit G119S AgAChE and that are contact-toxic to carbamate-resistant An. gambiae. PCR-RFLP analysis was used to confirm that carbamate-susceptible G3 and carbamate-resistant Akron strains of An. gambiae carry wild-type (WT) and G119S AChE, respectively. G119S AgAChE was expressed and purified for the first time, and was shown to have only 3% of the turnover number (k(cat)) of the WT enzyme. Twelve carbamates were then assayed for inhibition of these enzymes. High resistance ratios (>2,500-fold) were observed for carbamates bearing a benzene ring core, consistent with the carbamate-resistant phenotype of the G119S enzyme. Interestingly, resistance ratios for two oxime methylcarbamates, and for five pyrazol-4-yl methylcarbamates were found to be much lower (4- to 65-fold). The toxicities of these carbamates to live G3 and Akron strain An. gambiae were determined. As expected from the enzyme resistance ratios, carbamates bearing a benzene ring core showed low toxicity to Akron strain An. gambiae (LC(50)>5,000 μg/mL). However, one oxime methylcarbamate (aldicarb) and five pyrazol-4-yl methylcarbamates (4a-e) showed good to excellent toxicity to the Akron strain (LC(50) = 32-650 μg/mL). These results suggest that appropriately functionalized "small-core" carbamates could function as a resistance-breaking anticholinesterase insecticides against the malaria mosquito.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The European honey bee, Apis mellifera L., is an economically and agriculturally important pollinator that generates billions of dollars annually. Honey bee colony numbers have been declining in the ...United States and many European countries since 1947. A number of factors play a role in this decline, including the unintentional exposure of honey bees to pesticides. The development of new methods and regulations are warranted to reduce pesticide exposures to these pollinators. One approach is the use of repellent chemistries that deter honey bees from a recently pesticide-treated crop. Here, we describe a protocol to discern the deterrence of honey bees exposed to select repellent chemistries. Honey bee foragers are collected and starved overnight in an incubator 15 h prior to testing. Individual honey bees are placed into Petri dishes that have either a sugar-agarose cube (control treatment) or sugar-agarose-compound cube (repellent treatment) placed into the middle of the dish. The Petri dish serves as the arena that is placed under a camera in a light box to record the honey bee locomotor activities using video tracking software. A total of 8 control and 8 repellent treatments were analyzed for a 10 min period with each treatment was duplicated with new honey bees. Here, we demonstrate that honey bees are deterred from the sugar-agarose cubes with a compound treatment whereas honey bees are attracted to the sugar-agarose cubes without an added compound.
Multiple interacting stressors negatively affect the survival and productivity of managed honey bee colonies. Pesticides remain a primary concern for beekeepers, as even sublethal exposures can ...reduce bee immunocompetence, impair navigation, and reduce social communication. Pollinator protection focuses on pesticide application guidelines; however, a more active protection strategy is needed. One possible approach is the use of feeding deterrents that can be delivered as an additive during pesticide application. The goal of this study was to validate a laboratory assay designed to rapidly screen compounds for behavioral changes related to feeding or feeding deterrence. The results of this investigation demonstrated that the synthetic Nasonov pheromone and its terpenoid constituents citral, nerol, and geraniol could alter feeding behavior in a laboratory assay. Additionally, electroantennogram assays revealed that these terpenoids elicited some response in the antennae; however, only a synthetic Nasonov pheromone, citral, and geraniol elicited responses that differed significantly from control and vehicle detections.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Guidelines for grading diastolic dysfunction poorly categorize septic patients. We compared how well the American Society of Echocardiography (ASE) 2009 and 2016 definitions and a simplified ...definition categorized septic patients.
We studied septic patients who received a transthoracic echocardiogram within 24 h of admission to an ICU. We categorized patients according to ASE 2009 and 2016 definitions and a definition using
/
', a surrogate for left ventricular filling pressure. We assessed 28-day all-cause mortality and the presence of pre-existing diabetes, hypertension, or myocardial infarction. We tested for associations among diastolic grade, comorbidities, and outcomes using logistic regression.
We studied 398 patients. Mortality was 23%. The simplified definition categorized more patients than ASE 2016 (78% vs. 71%,
= 0.035); both definitions categorized more patients than ASE 2009 (34%,
< 0.001 for both comparisons). Higher grades of diastolic dysfunction were associated with hypertension (ASE 2016, simplified), myocardial infarction (ASE 2009, simplified), and diabetes (simplified). Grade of diastolic dysfunction was not associated with mortality by any definition. Of 199 patients categorized as normal by ASE 2016, 40% had an abnormal
/
' > 9 and 7% had a severely abnormal
/e' > 13.
The ASE 2016 definition categorizes more septic patients than the ASE 2009 definition, but it does not categorize the diastolic function of a third of septic patients. ASE 2016 designates many patients with elevated
/
' as normal. A simplified definition categorized patients with less ambiguity and is associated with relevant comorbidities.
The European honey bee, Apis mellifera L., is a valuable agricultural and commercial resource noted for producing honey and providing crop pollination services, as well as an important model social ...insect used to study memory and learning, aging, and more. Here we describe a detailed protocol for the dissection of the dorsal abdominal wall of a bee in order to visualize its dorsal vessel, which serves the role of the heart in the insect. A successful dissection will expose a functional heart that, under the proper conditions, can maintain a steady heartbeat for an extended period of time. This allows the investigator to manipulate heart rate through the application of cardiomodulatory compounds to the dorsal vessel. By using either a digital microscope or a microscope equipped with a digital camera, the investigator can make video recordings of the dorsal vessel before and after treatment with test compounds. The videos can then be scored at a time convenient to the user in order to determine changes in heart rate, as well as changes in the pattern of heartbeats, following treatment. The advantages of this protocol are that it is relatively inexpensive to set up, easy to learn, requires little space or equipment, and takes very little time to conduct.
Latin America and the Caribbean continue to be adversely affected by dengue with the disease being endemic in several countries in this region. As a result, the social and economic impacts of the ...disease have risen significantly. Currently, there are very few solutions available to limit the spread of the virus, with vector control being the most commonly used. However, due to increased insecticidal resistance, scientists in the region have actively been seeking new ways to limit the spread of the virus. This quest has led researchers to investigate the antiviral properties of natural products. While antiviral screening activities focused on preventing or treating infection of the human host remains a significant area of study, some scientists have now focused their attention on preventing infection or transmission in the mosquito vector. This review therefore aims to highlight the use of natural products in Latin America and the Caribbean for blocking viral transmission of dengue virus in mosquito cells. This novel approach is promising and could ultimately be used in conjunction with other methods to help significantly reduce dengue incidence in the region.
The toxicities of two herbicides (alachlor and metolachlor) and an organophosphate insecticide (chlorpyrifos) were evaluated individually and with either herbicide in binary mixture with chlorpyrifos ...in fourth-instar larvae of the aquatic midge (Chironomus tentans). Alachlor alone up to 1,000 micrograms per liter of water (μg/L) did not exhibit significant toxicity, whereas metolachlor at 1,000 μg/L affected 58% of midges in 72-h bioassays. However, alachlor at 1,000 μg/L and metolachlor at 10, 100, and 1,000 μg/L enhanced the toxicity of chlorpyrifos to the midges. Furthermore, alachlor and metolachlor at 1,000 μg/L reduced acetylcholinesterase (AChE) activity by 34.3% and 27.6%, respectively, in the treated midges. Although alachlor at 1,000 μg/L did not significantly affect protein production in the treated midges, it reduced glutathione S-transferases (GST) total activities by 1.9- to 2.1-fold. In contrast, metolachlor at 1,000 μg/L reduced protein production by 3.2-fold, which was associated with a 2.8-fold reduction of cytochrome P450 O-deethylation total activity and 1.4- to 1.7-fold reductions of GST total activities in the treated midges. Such reduced total activities of the major detoxification enzymes in herbicide-treated midges might impede the metabolic detoxification of chlorpyrifos and, therefore, increase the susceptibility of the midges to chlorpyrifos. Thus, it is likely that coexistence of chlorpyrifos and these herbicides, particularly metolachlor, in surface waters may pose increased risks to midges in aquatic environments.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The aim of this study was to investigate the utility of cultured Anopheles gambiae Sua1B cells for insecticide screening applications without genetic engineering or other treatments. Sua1B cells were ...exposed to the known insecticidal compounds lindane and DIDS, which inhibited cell growth at micromolar concentrations. In patch clamp studies, DIDS produced partial inhibition (69%) of chloride current amplitudes, and an IC50 of 5.1μM was determined for Sua1B cells. A sub-set of chloride currents showed no response to DIDS; however, inhibition (64%) of these currents was achieved using a low chloride saline solution, confirming their identity as chloride channels. In contrast, lindane increased chloride current amplitude (EC50=116nM), which was reversed when cells were bathed in calcium-free extracellular solution. Voltage-sensitive chloride channels were also inhibited by the presence of fenvalerate, a type 2 pyrethroid, but not significantly blocked by type 1 allethrin, an effect not previously shown in insects. Although no evidence of fast inward currents typical of sodium channels was observed, studies with fenvalerate in combination with veratridine, a sodium channel activator, revealed complete inhibition of cell growth that was best fit by a two-site binding model. The high potency effect was completely inhibited in the presence of tetrodotoxin, a specific sodium channel blocker, suggesting the presence of some type of sodium channel. Thus, Sua1B cells express native insect ion channels with potential utility for insecticide screening.
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•Sua1B cell growth was inhibited by insecticides.•Cl− currents were enhanced in the presence of lindane in a Ca++ dependent manner.•DIDS blocked Cl− currents in most cells, but some were insensitive.•Type 2, but not type 1 pyrethroids also significantly reduced Cl− currents.•A type of “electrically silent” Na+ channels may exist in Sua1B cells.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The acute toxicities of two organophosphorodithioate (dimethoate and disulfoton) and two organophosphorothioate (omethoate and demeton-
S-methyl) insecticides were evaluated individually and in ...binary combination with the herbicide atrazine using fourth-instar larvae of the aquatic midge,
Chironomus tentans. Atrazine alone up to 1000
μg/L did not show significant toxicity to the midges in a 48-h bioassay. However, atrazine concentrations as low as 1
μg/L in combination with dimethoate at EC
25 (concentration to affect 25% of tested midges), 100
μg/L in combination with disulfoton (EC
25), and 10
μg/L in combination with demeton-
S-methyl (EC
25) significantly enhanced the toxicity of each organophosphate insecticide. In contrast, atrazine concentrations of 10
μg/L and above in combination with omethoate (EC
25) significantly decreased the toxicity of the insecticide. Biochemical analysis indicated that increased toxicity of dimethoate, disulfoton, and demeton-
S-methyl in binary combination with atrazine correlated to the increased inhibition of acetylcholinesterase. Furthermore, cytochrome P450-dependent O-deethylation activity in the midges exposed to atrazine at 1000
μg/L was 1.5-fold higher than that in the control midges. Thus, atrazine appeared to induce cytochrome P450 monooxygenases in the midges. Elevated cytochrome P450 monooxygenase activity may increase the toxicities of dimethoate, disulfoton, and demeton-
S-methyl by enhancing the oxidative activation of dimethoate into omethoate, and disulfoton and demeton-
S-methyl into their sulfoxide analogs with increased anticholinesterase activity. In contrast, atrazine reduced the toxicity of omethoate possibly by enhancing the oxidative metabolic detoxification since omethoate does not require oxidative activation.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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