CARLSON, ALBERT/D; SUNY STONY BROOK: Is the Firefly Flash Controlled By Calcium Channels?
“Voltage-gated Ca(calcium) channels are found in every excitable cell. Indeed, I feel they define excitable cells.” (Hille, B.,) Ion Channels of Excitable Membranes, 3rd Edition, Sinauer Associates Inc., Sunderland, MA, 2001. Is something missing in our study of the control of the firefly flash? Are calcium channels in the photocyte membranes of the lantern involved in the activation of the photogenic reaction? An examination of the effect of high potassium saline on the lantern of male Photuris versicolor fireflies implicates calcium channels. High potassim saline induces massive scintillation in which individual photocytes twinkle rapidly on and off for hours. This response fails when calcium is replaced with magnesium. It is possible the depolarization of the photocyte membrane in high potassium saline opens voltage-sensitive Ca2+-permeable channels. Calcium ions act as intracellular second messengers that activate many cell functions. In the flickering male firefly, P. versicolor, direct electrical stimulation of the lantern with a one-second burst of pulses at 100 Hz induces only a rapid three-pulsed flicker. In P. lucicrescens, the male lantern, which produces a long crescendo flash during courtship, the same stimulus induces a one-second glow. The lantern of this latter firefly does not scintillate in response to high potassium saline. Is it possible that the calcium-permeable channels in these two fireflies differ?
