Cultured mosquito cells <i>Aedes albopictus</i> C6/36 (Dip., Culicidae) responsive to 20‐hydroxyecdysone and non‐steroidal ecdysone agonist

Smagghe, Guy; Braeckman, Bart P.; Huys, Nele; Raes, Hilda

doi:10.1046/j.1439-0418.2003.00727.x

Cited by 19 publications

(10 citation statements)

References 32 publications

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“…5.3d). The appearance of long slender neurite-like extensions may reflect a general stress response, rather than a specific effect of the heavy metals as this particular morphology was also obtained when cells were treated with 20-OH ecydosone (Smagghe et al 2003) and the F-actin poison cytochalasin B (Fig. 5.3e).…”

Section: Generalcellmorphology(lightmicroscopy)mentioning

confidence: 83%

Heavy Metal Toxicity in an Insect Cell Line (Methyl-HgCl, HgCl2, CdCl2 and CuSO4)

Braeckman

2011

Cellular Effects of Heavy Metals

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We have analyzed the toxicity, uptake and intracellular effects of CdCl 2 , HgCl 2 , MeHgCl and CuSO 4 in a cell line of the Asian tiger mosquito Aedes albopictus. Cell proliferation was drastically inhibited by CdCl 2 and MeHgCl while HgCl 2 showed only a moderate effect. Acute toxicity tests showed that membrane integrity was severely affected in cells treated with low doses of HgCl 2 and MeHgCl. Uptake of both mercury species occurred via simple diffusion while cadmium entered the cells through mediated transport. CdCl 2 , HgCl 2 and CuSO 4 , but not MeHgCl induced microtubulesupported neurite-like extensions in the Aedes cells. The metals induced some general intracellular pathologies such as mitochondrial alterations, nuclear deformation and increased lysosomal profiles. Mitochondrial swelling and severe RER dilatation by proteinaceous material was most pronounced in cadmium-treated cells. These morphological features were accompanied by lactate production and induction of a 78-kDa protein (possibly Grp78/BiP). The latter may represent a stress defense system that leads to a positive shift of the cell viability curve. Unlike other treatments, CuSO 4 -treated cells showed massive apoptosis characterized by nuclear chromatin condensation and DNA laddering. IntroductionMany insect species accumulate heavy metals from the environment in their body. Therefore, their role in food webs as well as their potential to serve as bioindicators have been widely studied (McGeoch 1998). However, less is known about the fate of the heavy metals at the cellular level in insects. A major advantage of using insect cell cultures for this purpose is that this method allows for controlled exposure of cells to precise metal concentrations for a specific amount of time. In this chapter, we will describe the general toxicity, uptake kinetics, subcellular distribution and physiological effects of several heavy metals in a cell line of the Asian tiger mosquito Aedes albopictus.In a series of dye exclusion tests and cell proliferation assays on mercury-, methylmercury-, and cadmium-treated cells, we found that they showed widely different toxicity patterns. Sublethal doses of the tested heavy metals showed a profound effect on general cell morphology: long, neurite-like, microtubule-supported extensions were induced (except for MeHgCl-treated cells). At the subcellular level, many general, stress-related pathologies were found, such as nuclear chromatin clumping, indentation and dilatation of the perinuclear cisternae, increase of ribosomal density, and lysosomal and RER volume. Cd-treated cells specifically showed clear mitochondrial condensation and swelling, suggesting impairment of aerobic function which was confirmed by increased lactic acid levels in the culture medium. Proteinaceous substance that we found in the dilated RER cisternae may represent the ER stress protein Grp78/BiP. Cells exposed to MeHgCl showed particular cytoplasmic tube-like structures of unknown function and the appearance of blebs suggested microtubul...

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Section: Generalcellmorphology(lightmicroscopy)mentioning

confidence: 83%

Heavy Metal Toxicity in an Insect Cell Line (Methyl-HgCl, HgCl2, CdCl2 and CuSO4)

Braeckman

2011

Cellular Effects of Heavy Metals

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“…They reported an LC 50 for methoxyfenozide of 0.22 mg/kg, 10 times more toxic to mosquito larvae than RH-5849, tebufenozide, or halofenozide. In more physiological than toxicological reports, both Smagghe et al (2003) and Palli et al (2005) suggested ecdysone agonists could have promise as mosquitocides. Palli et al (2005) reported an EC 50 of 0.67 and 0.45 ppm (length of observation time was not Þxed) for methoxyfenozide (RH-2485) and (1-aroyl-4-(arylamino)-1,2,3,4-tetrahydro-quinoline against Ae.…”

Section: Discussionmentioning

confidence: 99%

Influence of Fluctuating Salinity on Insecticide Tolerance of Two Euryhaline Arthropods

Song

Brown

2006

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Among many other abiotic variations in an estuarine ecosystem, osmotic stress is an inescapable part of life. Organisms living in such environments must cope with changing osmotic conditions by either behavioral or physiological adaptations. Pollutants may increase the physiological stresses that an osmoregulating animal may encounter. We have developed a flow-through system that exposes test species to insecticides and continuously changing salinity conditions. This system has provided an insight into how susceptibility of a species to an insecticide can be affected by changing concentrations of salinity. Toxicity tests using this system were conducted with two arthropod species that are found in saline habitats: mosquito Aedes taeniorhynchus (Wiedemann) and brine shrimp (Artemia sp.). Four insecticides-aldicarb, dimethoate, imidacloprid, and tebufenozide-were studied. Both species were exposed for 48 h to a concentration of various insecticides that would cause 50% of the population to die in hyperosmotic artificial sea water (ASW). The mortality rate for both species was more acute in increasing salinity (10-200% ASW) than in decreasing salinity (200-10% ASW) conditions. A. taeniorhynchus was more susceptible than Artemia when exposed to its hyperosmotic LC50 concentration of toxicant while experiencing a change in salinity, e.g., adjusting to a changing salinity decreased the LT50. Our results indicated a change in salinity; more importantly, the direction of change altered the susceptibility of these organisms.

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“…Based on these observations, it can also be speculated that the cellular long filamentous cytoplasmic extensions of the Se4 cell line as seen in Figure 2B were due to changes in actin content. It has been proven that the cytoplasmatic actin content of responsive cells was doubled during 20E-induced cell elongation (Berger et al, 1981;Couderc et al, 1982;Smagghe et al, 2003a). The commitment to mitotic arrest was very rapid and this mitotic arrest was accompanied by changes in cell shape.…”

Section: Discussionmentioning

confidence: 99%

Action of 24-epibrassinolide on a cell line of the beet armyworm,Spodoptera exigua

Decombel

Tirry

Smagghe

2005

Arch. Insect Biochem. Physiol.

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The Spodoptera exigua cell line Se4 is sensitive for ecdysteroid activity stimulated by the insect molting hormone, 20-hydroxyecdysone (20E), showing a cease in cell proliferation (with 50% inhibition around 1 microM) and characteristic cell morphology changes with aggregation and formation of long filamentous cytoplasmic extensions. The bisacylhydrazine tebufenozide also triggered such typical cellular effects in Se4, and in addition, it showed an affinity for binding in competition with 3H-ponasterone A (PoA) that was similar to 20E (with 50% competition around 1 microM), confirming that such non-ecdysteroids display an ecdysteroid agonist activity. In contrast, when Se4 cells were incubated with the native plant hormone 24-epibrassinolide (24BR), none of the effects triggered by 20E were observed. Hence, a competition binding experiment with 3H-PoA demonstrated no affinity of 24BR for binding to the ecdysteroid receptor in the Se4 cell line. In another series of experiments, the Se4 cell line was tested in sensitivity response to increased acetylcholinesterase (AchE) activity after treatment with ecdysteroid active compounds. The AchE activity measured in the cell line is discussed in relation to inhibition by eserine. The obtained results suggest that 24BR exerted no ecdysteroid activity.

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Cultured mosquito cells Aedes albopictus C6/36 (Dip., Culicidae) responsive to 20‐hydroxyecdysone and non‐steroidal ecdysone agonist

Cited by 19 publications

References 32 publications

Heavy Metal Toxicity in an Insect Cell Line (Methyl-HgCl, HgCl2, CdCl2 and CuSO4)

Heavy Metal Toxicity in an Insect Cell Line (Methyl-HgCl, HgCl2, CdCl2 and CuSO4)

Influence of Fluctuating Salinity on Insecticide Tolerance of Two Euryhaline Arthropods

Action of 24-epibrassinolide on a cell line of the beet armyworm,Spodoptera exigua

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