Honeybees show adaptive reactions to ethanol exposure

AbstractThe honeybee is being developed as a simple invertebrate model for alcohol-related studies. To date, several effects of ethanol consumption have been demonstrated in honeybees, but the tolerance effect, one of the hallmarks of alcohol overuse, has never been shown. Here, we confirm our hypothesis that the response to ethanol (in terms of motor impairment) is lower in bees that have previously experienced intoxication than in bees encountering ethanol for the first time, indicating that the chronic tolerance effect occurs in honeybees. Furthermore, we investigated the basis of this effect and found that it likely results from conditioned compensatory responses to cues associated with ethanol delivery. Our findings significantly improve our understanding of the suitability of honeybees as models for alcoholism-related research and underline the first and foremost function of all conditioned reactions – their adaptive value.</jats:p

Oxygen and temperature affect cell sizes differently among tissues and between sexes of Drosophila melanogaster

Spatio-temporal gradients in thermal and oxygen conditions trigger evolutionary and developmental responses in ectotherms’ body size and cell size, which are commonly interpreted as adaptive. However, the evidence for cell-size responses is fragmentary, as cell size is typically assessed in single tissues. In a laboratory experiment, we raised genotypes of Drosophila melanogaster at all combinations of two temperatures (16 $^{\circ}C$ or 25 $^{\circ}C$) and two oxygen levels (10% or 22%) and measured body size and the sizes of cells in different tissues. For each sex, we measured epidermal cells in a wing and a leg and ommatidial cells of an eye. For males, we also measured epithelial cells of a Malpighian tubule and muscle cells of a flight muscle. On average, females emerged at a larger body size than did males, having larger cells in all tissues. Flies of either sex emerged at a smaller body size when raised under warm or hypoxic conditions. Development at 25 $^{\circ}C$ resulted in smaller cells in most tissues. Development under hypoxia resulted in smaller cells in some tissues, especially among females. Altogether, our results show thermal and oxygen conditions trigger shifts in adult size, coupled with the systemic orchestration of cell sizes throughout the body of a fly. The nature of these patterns supports a model in which an ectotherm adjusts its life-history traits and cellular composition to prevent severe hypoxia at the cellular level. However, our results revealed some inconsistencies linked to sex, cell type, and environmental parameters, which suggest caution in translating information obtained for single type of cells to the organism as a whole

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not availableHoney bees willingly consume ethanol as it is available in their natural environment, e.g. fermented floral nectar or fruits. Several behavioural effects of ethanol intoxication are known in honey bees, including changes in motor function, disorientation and immobility. This study examined whether honey bees develop tolerance during chronic exposures to ethanol. The experiment was performed on four colonies of honeybees. Workers of each colony were exposed to four treatments, and in each treatment, a bee was exposed for five consecutive days to vapours of either water of ethanol. After the exposition, the motor performance of bees was measured. In treatment 1, bees received water vapour on each day; in treatment 2, bees were exposed to water vapour for four days, and then to ethanol vapour on the 5th day; in treatment 3, bees experienced ethanol vapour on each day; and in treatment 4, bees received ethanol vapour for four days, and then water vapour on the 5th day. A comparison of the motor performance of bees on the last day of the experiment showed that individuals which were repeatedly exposed to ethanol (treatment 3) developed through time an ability to cope with intoxication. Bees with past ethanol experience (treatment 4) showed no motor impairment when exposed to water vapours, compared to individuals that have never experienced ethanol (treatment 1). Overall, these findings indicate that honey bees develop chronic ethanol tolerance, which indicates that honeybee can be an important study system in the field of alcohol-effects research, especially in addressing questions about the evolution of ethanol tolerance and the potential effects of ethanol consumptions on social interactions

Systemic changes in cell size throughout the body of Drosophila melanogaster associated with mutations in molecular cell cycle regulators

Abstract Along with different life strategies, organisms have evolved dramatic cellular composition differences. Understanding the molecular basis and fitness effects of these differences is key to elucidating the fundamental characteristics of life. TOR/insulin pathways are key regulators of cell size, but whether their activity determines cell size in a systemic or tissue-specific manner awaits exploration. To that end, we measured cells in four tissues in genetically modified Drosophila melanogaster (rictor Δ2 and Mnt 1 ) and corresponding controls. While rictor Δ2 flies lacked the Rictor protein in TOR complex 2, downregulating the functions of this element in TOR/insulin pathways, Mnt 1 flies lacked the transcriptional regulator protein Mnt, weakening the suppression of downstream signalling from TOR/insulin pathways. rictor Δ2 flies had smaller epidermal (leg and wing) and ommatidial cells and Mnt 1 flies had larger cells in these tissues than the controls. Females had consistently larger cells than males in the three tissue types. In contrast, dorsal longitudinal flight muscle cells (measured only in males) were not altered by mutations. We suggest that mutations in cell cycle control pathways drive the evolution of systemic changes in cell size throughout the body, but additional mechanisms shape the cellular composition of some tissues independent of these mutations

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