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age-2 in the BHI assay due to insufficient ATP. We also noticed that at all time points up to 6 hours after head bisection, ATP levels were significantly increased with light-exposure. This light-induced rise in ATP is also a likely indicator of photoreceptor viability. Thus, we have developed an ex vivo preparation of fly eyes in which the first stage of light-induced TRPL translocation can be studied on a time-course similar to that observed from living flies. Unfortunately, photoreceptor degeneration was observed at the longer incubation times required to examine the second stage of TRPL translocation. For subsequent studies described here, we therefore focus on mechanisms underlying stage-1 TRPL translocation. Perturbation of the Actin Cytoskeleton Does Not Affect Stage-1 TRPL Translocation Subcellular transport of proteins can occur via active and/or passive mechanisms. Active transport in Drosophila photoreceptors would likely involve the major cytoskeletal element, actin, which composes the microvilli of the rhabdomeres. We therefore set out to disrupt the actin cytoskeleton and examine whether TRPL translocation would be affected. Assembly and maintenance of the actin cytoskeleton is regulated by continuous cycles of actin polymerization and depolymerization. We used cytochalasin D February 2012 | Volume 7 | Issue 2 | e31622 Mechanisms of TRPL Channel Translocation , a membrane permeable mycotoxin known to inhibit actin polymerization. Using the BHI preparation, we were able to treat photoreceptors with CytD. Although phalloidin staining can be used to monitor the actin cytoskeleton, especially after drug treatment, severe disruption has been difficult to attain in insect retinas due to the dense packing of microvilli that make up rhabdoms and rhabdomeres of photoreceptor cells. With this in mind, we increased CytD and DMSO concentrations as much as possible while avoiding significant cell degeneration. We found that one hour CytD treatment at 10 mg/ml in 1% DMSO resulted in bright phalloidin-labeled actin aggregates directly at the base of the rhabdomeres, which were not present in control retinas; similar results were seen with up to 20 mg/ml cytD in 4% DMSO. Previous studies in both honeybee retinas and cultured vertebrate cells have demonstrated that phalloidin-staining following CytD treatment results in the appearance of these punctate, actin aggregates or “asters”, composed of densely packed, short actin filaments. We tested for the light-dependent translocation of TRPL with CytD treatment, and observed normal redistribution of TRPL from the rhabdomere to the apical plasma membrane. These results suggest that the actin cytoskeleton is not likely to play a major role in stage-1 TRPL translocation. TRPL Channel Localization in the Dark is ATP-Dependent, and Stage-1 Translocation is ATP-Independent To determine whether the light-regulated redistribution of TRPL 1443460-91-0 customer reviews channels ” requires energy, we planned to use the BHI preparation to deplete ATP from “ 23977191 photoreceptor cells, and then examine whether TRPL channels would translocate to stage-1. To deplete ATP, wild-type eyes were incubated in a glucose-free bath solution supplemented with 2-D-deoxyglucose and potassium cyanide. DOG, a glucose analogue, prevents glycolysis, while KCN inhibits mitochondrial cytochrome oxidase, thereby blocking oxidative phosphorylation. Together, these inhibitors have been used to deplete ATP in other cells. First, wild-type eyes were incubated in the dar

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