In Memoriam: Charles Frederick Ehret, 1924-2007

This news just came in:

Charles F- Ehret died of natural causes on February 24th at his home in Grayslake, Illinois, a suburb of Chicago.

His Wikipedia entry is quote short:

Charles Frederick Ehret is a WWII veteran (Battle of the Bulge/Ardennes along the Siegfried Line) as well as a world renowned molecular biologist who worked at Argonne National Laboratory (ANL) in Lemont, Illinois, USA, for 40 years. Dr. Ehret researched the effects of electromagnetic radiation on bacillus megaterium with Dr. Edward Lawrence (Larry) Powers, as well as the effects of time shifts on paramecia, rats and humans. A graduate of City College of CCNY (College of the City of New York) and the University of Notre Dame, Dr. Ehret formulated the term “circadian dyschronism”, popularized the term “zeitgeber” = “time giver” in the 1980’s while appearing on morning TV news shows, and helped millions of travellers overcome Jet Lag with the Jet Lag Diet, and Overcoming Jet Lag book, both available online. Dr. Ehret once created the worlds largest spectrograph, a rainbow 100 feet long, that was large enough to bathe many petri dishes of tetrahymena in each angstrom of the color spectrum.

While his later interest in human clocks and his book Overcoming Jet Lag made him popular outside of chronobiological circles, within the field he is famous for some ingeniously creative pioneering experiments on circadian clocks in protists, mainly Paramecium and Tetrahymena. Here are the links to a couple of his more popular papers on the topic:
Light synchronization of an endogenous circadian rhythm of cell division in Tetrahymena
Circadian rhythm of pattern formation in populations of a free-swimming organism, Tetrahymena.
Testing the chronon theory of circadian timekeeping (DNA-RNA molecular hybridization testing of chronon theory of circadian timekeeping in protozoa cells)
That last link refers to “the chronon theory” of circadian rhythms, the first serious molecular model for a circadian rhythm generation within a cell, which Ehret proposed back in 1967 when he was only one of a handful of researchers who were actively trying to study the biological clock below the level of the cell. Thus, his longest lasting contribution to science will not be his jet-lag book (which is already a bit aged), but his original Chronon paper:
Ehret, C. F., and Trucco, E., (1967), Molecular models for the circadian clock. I. The chronon concept., J. theor. Biol., 15, 240-262 .
I have mentioned the Chronon Model earlier, when I wrote a quick review of the history of clock genetics and this is what I wrote:

In this model, a series of genes induce each other’s expression, i.e., protein A induces trasncription of gene B, protein B induces expression of gene C and so on until the last protein in the series, about 24 hours later, induces expression of gene A again. This model is, actually, not that far from the currently understood mechanism of interlocking trasncription/translation feedback loops


One response to “In Memoriam: Charles Frederick Ehret, 1924-2007

  1. Thanks for that brief bio and news. I wasn’t aware of who he was until just now. My grandfather was also at Battle of the Bulge, Ardennes & St. Lo and was never the same afterward according to my grandmother -he often had difficulty sleeping and awoke with nightmares through the night.
    PTSD, called “shell shock” back then was little understood. I wonder if any similar post-war experiences inspired Dr. Ehret’s work -the sleep disruption angle, I mean.