Submitted on November 13, 2007
Accepted on February 11, 2008
Hyperthermic preconditioning of presynaptic calcium regulation in
Drosophila
Markus Kristian Klose1*, Harold L. Atwood2, and R M Robertson3
1 Biology, Queen's University, Kingston, Canada; Physiology, Univesity of Toronto, Toronto, Canada; Physiology, University of Toronto, Toronto, Canada; , Canada
2 Physiology, University of Toronto, Toronto, Canada
3 Biology, Queen's University, Kingston, Canada
* To whom correspondence should be addressed. E-mail: markus.klose{at}utoronto.ca.
We examined the thermosensitivity of calcium regulation in Drosophila larval neuromuscular junctions, testing effects of prior heat shock and Hsp70 expression. Motor neurons were loaded with either the ratiometric indicator Fura-dextran or the non-ratiometric indicator Oregon Green BAPTA to monitor parameters of calcium regulation as temperature increased. Nerve terminals treated to a prior heat shock, and those of transgenic flies expressing higher than normal levels of Hsp70, were better able to maintain near-normal resting calcium concentrations, calcium influx, and calcium clearance at higher temperatures. Synaptic transmission was also protected by prior heat shock and by higher than normal Hsp70 expression. Thus, the thermal limit of synaptic transmission may be directly linked to the stability of calcium regulation.
