Meeting Abstract
For decades brief pre-treatment with moderate low temperature has been used to induce a rapid cold hardening (RCH) response that protects against a) cold shock injury otherwise incurred during brief treatment with more severe low temperature and b) interruption of various behaviors ranging from the simple (e.g., clinging) through the complex (e.g., courtship and mating). If RCH provides protection at a cost to a particular organism, those costs may be subtle. Rapid cold hardening causes little, if any, effect on early fecundity, lifespan or the behavioral repertoire of Drosophila melanogaster. Here we describe a subtle effect of a commonly used RCH treatment (1 h at 2 °C) on the phototaxis response of D. melanogaster. Adult (48 h post-eclosion) flies were maintained at 23°C or cooled to 2 °C for 1 h (2 °C flies), then maintained at 23 °C for an additional 1 – 2 h before transfer to a phototaxis testing chamber. Each chamber consisted of a pair of 13 X 100 mm glass culture tubes connected at their openings, with one tube covered in aluminum foil and a fiber optic light source positioned at the far end of the uncovered tube. In tests initiated with flies placed on the dark side of the chamber control flies almost always moved to the lighted end of the testing chamber. By contrast 2 °C flies remained in the darkened side of the chambers. In tests initiated with flies in the lighted side, nearly all control flies remained within 10 mm of the lighted end but all 2 °C flies moved away from the light, positioning themselves 5.4 ± 0.3 cm from the lighted end. These data provide an example of a subtle effect associated with an RCH treatment that itself may be diminished by RCH during treatment with even less severe low temperature.
