It is with great sadness that I learned that Dr.Greg Cahill died a few days ago, at the Houston airport, waiting for his flight. I have met Greg at several meetings of the Society for Research on Biological Rhythms and while, those being fairly large meetings, we never had big one-on-one conversations, I remember him as a humble and friendly person, beloved by everyone.
He started his scientific career in Mike Menaker’s lab, studying the entrainment of the mammalian clock in the suprachiasmatic nucleus in vitro. Making preparations of SCN and optic tracts and doing electrophysiology on such preparations was not an easy technical feat back in 1986 or so when he started doing this. After getting a PhD with Menaker at the University of Oregon, Greg did some work on circadian clocks in the retina of the Xenopus frog with Dr. Joseph Besharse.
When he got his own lab at the University of Houston, he was one of the first two circadian researchers to start using the zebrafish. I remember the SRBR meeting when we all excitedly watched the two of them present their first data – both primarily focused on the methodological question: how to continuously monitor circadian rhythms in this animal.
The other researcher, Dr.Keith Barrett (MS with Terry Page on cockroaches, PhD with Herb Underwood on Japanese quail, postdoc with Joseph Takahashi on chicken pineal, then started on zebrafish, not doing science any more, I hear), designed a continuous-flow collection and melatonin assay of zebrafish larvae placed in a 96-well plate.
Greg Cahill used a different tactic – he also placed larvae in a 96-well plate, but instead, he trained a camera on them and came up with a computer program to translate the video of the movements into quantitative data of circadian locomotor activity.
Having this methodology as a starting point, Dr.Cahill then embarked on the study of zebrafish circadian rhythms, identifying genetic mutants and elucidating the molecular mechanisms underlying the rhythms. He later perfected an even better monitoring technique – constructing zebrafish with the luciferase gene which could be monitored in the dark during the early development of the circadian system in the fish larvae.
He will be sorely missed by his colleagues and the field.