Gut instinct: How fruit flies beat cold temperatures

Research conducted by York University scientists revealed that to survive at low temperatures, fruit flies dramatically modify the function of a rather unexpected organ—the gut.

photo of a fruit fly

Drosophila melanogaster is a species of fly (the taxonomic order Diptera) in the family Drosophilidae). The species is known generally as the common fruit fly or vinegar fly. Image: Wikipedia

From the elegant lady bug to the annoying mosquito, insects represent the most diverse group of animals on earth. One key to their success is a complex set of responses that allow insects to modify their physiology to overcome environmental pressures such as changes in water availability, salt levels and temperature.

Unlike mammals and birds, insects are ectotherms, meaning that their body temperature is dependent on the temperature of their surroundings. Temperature strongly impacts a variety of biological processes from enzymatic activity to the liquid state of bodily fluids. As a result, the geographical distribution of insects is tightly linked to environmental temperatures that are suitable for their survival.

Particularly in the context of climate change, an understanding of the cold physiology of insects is crucial to insect distribution forecasting and control. To date, work has revealed that low temperatures cause many insects to lose the ability to regulate water and salt balance within their bodies. If, however, insects are first exposed to a mild cold stress, they can drastically alter their physiology and prevent these issues, but we don’t know how.

Researchers from York’s Faculty of Science led by MSc student Gil Yerushalmi have now answered this question in a paper published in The Journal of Experimental Biology.

In the current study, researchers raised common fruit flies, at 25°C. As the fruit flies emerged from their larval form, the researchers separated the flies into two different conditions: 10°C and 25°C. Using real time measurements of ion transport, they showed that guts of flies held at 10°C were drastically altered in a manner that helps to minimize potential water and salt-imbalances.

Yerushalmi led this project as a part of his Master’s thesis under the mentorship of postdoctoral fellow Heath MacMIllan (now an assistant professor at Carleton University) and Biology Professor Andrew Donini. Yerushalmi collaborated with a fellow Master’s student, Lidiya Misyura, whose expertise was crucial to conducting the complex ion-measurements of the present study.

This research was supported by the Natural Sciences & Engineering Research Council of Canada.

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