Resveratrol-Inspired Bridged Bicyclic Compounds: A New Compound Class for the Protection of Synaptic Function from Acute Oxidative Stress.

While resveratrol protects organisms from the deleterious effects of oxidative stress, its multifarious mechanism of action limits its potential as a selective medicinal agent. To address this shortcoming, we have designed a molecular scaffold that we have termed a resveramorph. The structure of this compound class possesses much of the functional group characteristics of resveratrol but in a nonplanar molecular arrangement, and, in the present work, we probe the neuroprotective activities of two resveramorph analogues. These novel compounds were found to protect neurotransmission from hydrogen peroxide-induced oxidative stress. Our findings demonstrate that, at a subnanomolar level, one analogue, resveramorph 1, protects synaptic transmission from acute oxidative stress at the Drosophila neuromuscular junction. These results position resveramorphs as potential lead compounds in the development of new drugs for neurodegenerative diseases.

BK channels and a cGMP-dependent protein kinase (PKG) function through independent mechanisms to regulate the tolerance of synaptic transmission to acute oxidative stress at the Drosophila larval neuromuscular junction.

A cGMP-dependent protein kinase (PKG) has previously been shown to regulate synaptic transmission at the Drosophila neuromuscular junction (NMJ) during acute oxidative stress, potentially through modulation of downstream K+ channel kinetics; however, the specific K+ channels through which PKG functions remains unclear. In this study, we hypothesized that PKG may be acting on calcium-activated large-conductance Slo K+ channels, or BK channels. We found that genetic elimination and pharmacological inhibition of BK channel conductance increases synaptic transmission tolerance to acute H2O2-induced oxidative stress. Furthermore, we discovered that activation of PKG in BK channel loss-of-function (Slo4) mutants significantly decreases time to stimulus-induced synaptic failure, providing the first evidence of PKG and BK channels functioning independently to control synaptic transmission tolerance to acute oxidative stress.

translin Is Required for Metabolic Regulation of Sleep.

Dysregulation of sleep or feeding has enormous health consequences. In humans, acute sleep loss is associated with increased appetite and insulin insensitivity, while chronically sleep-deprived individuals are more likely to develop obesity, metabolic syndrome, type II diabetes, and cardiovascular disease. Conversely, metabolic state potently modulates sleep and circadian behavior; yet, the molecular basis for sleep-metabolism interactions remains poorly understood. Here, we describe the identification of translin (trsn), a highly conserved RNA/DNA binding protein, as essential for starvation-induced sleep suppression. Strikingly, trsn does not appear to regulate energy stores, free glucose levels, or feeding behavior suggesting the sleep phenotype of trsn mutant flies is not a consequence of general metabolic dysfunction or blunted response to starvation. While broadly expressed in all neurons, trsn is transcriptionally upregulated in the heads of flies in response to starvation. Spatially restricted rescue or targeted knockdown localizes trsn function to neurons that produce the tachykinin family neuropeptide Leucokinin. Manipulation of neural activity in Leucokinin neurons revealed these neurons to be required for starvation-induced sleep suppression. Taken together, these findings establish trsn as an essential integrator of sleep and metabolic state, with implications for understanding the neural mechanism underlying sleep disruption in response to environmental perturbation.

Context-specific comparison of sleep acquisition systems in Drosophila.

Sleep is conserved across phyla and can be measured through electrophysiological or behavioral characteristics. The fruit fly, Drosophila melanogaster, provides an excellent model for investigating the genetic and neural mechanisms that regulate sleep. Multiple systems exist for measuring fly activity, including video analysis and single-beam (SB) or multi-beam (MB) infrared (IR)-based monitoring. In this study, we compare multiple sleep parameters of individual flies using a custom-built video-based acquisition system, and commercially available SB- or MB-IR acquisition systems. We report that all three monitoring systems appear sufficiently sensitive to detect changes in sleep duration associated with diet, age, and mating status. Our data also demonstrate that MB-IR detection appeared more sensitive than the SB-IR for detecting baseline nuances in sleep architecture, while architectural changes associated with varying life-history and environment were generally detected across all acquisition types. Finally, video recording of flies in an arena allowed us to measure the effect of ambient environment on sleep. These experiments demonstrate a robust effect of arena shape and size as well as light levels on sleep duration and architecture, and highlighting the versatility of tracking-based sleep acquisition. These findings provide insight into the context-specific basis for choosing between Drosophila sleep acquisition systems, describe a novel cost-effective system for video tracking, and characterize sleep analysis using the MB-IR sleep analysis. Further, we describe a modified dark-place preference sleep assay using video tracking, confirming that flies prefer to sleep in dark locations.

Altered regulation of sleep and feeding contributes to starvation resistance in Drosophila melanogaster.

Animals respond to changes in food availability by adjusting sleep and foraging strategies to optimize their fitness. Wild populations of the fruit fly, Drosophila melanogaster, display highly variable levels of starvation resistance that are dependent on geographic location, food availability and evolutionary history. How behaviors that include sleep and feeding vary in Drosophila with increased starvation resistance is unclear. We have generated starvation-resistant flies through experimental evolution to investigate the relationship between foraging behaviors and starvation resistance. Outbred populations of D. melanogaster were selected for starvation resistance over 60 generations. This selection process resulted in flies with a threefold increase in total lipids that survive up to 18 days without food. We tested starvation-selected (S) flies for sleep and feeding behaviors to determine the effect that selection for starvation resistance has had on foraging behavior. Flies from three replicated starvation-selected populations displayed a dramatic reduction in feeding and prolonged sleep duration compared to fed control (F) populations, suggesting that modified sleep and feeding may contribute to starvation resistance. A prolonged larval developmental period contributes to the elevated energy stores present in starvation-selected flies. By preventing S larvae from feeding longer than F larvae, we were able to reduce energy stores in adult S flies to the levels seen in adult F flies, thus allowing us to control for energy storage levels. However, the reduction of energy stores in S flies fails to generate normal sleep and feeding behavior seen in F flies with similar energy stores. These findings suggest that the behavioral changes observed in S flies are due to genetic regulation of behavior rather than elevated lipid levels. Testing S-F hybrid individuals for both feeding and sleep revealed a lack of correlation between food consumption and sleep duration, indicating further independence in genetic factors underlying the sleep and feeding changes observed in S flies. Taken together, these findings provide evidence that starvation selection results in prolonged sleep and reduced feeding through a mechanism that is independent of elevated energy stores. These findings suggest that changes in both metabolic function and behavior contribute to the increase in starvation resistance seen in flies selected for starvation resistance.