A timeline of the key events in the history of molecular/genetic chronobiology.
Created by coturnix on Feb 9, 2011
Last updated: 03/18/11 at 01:00 AM
Tags: science circadian genetics chronobiology
CRY, known already as a photoreceptor in plants, a photoreceptor in insects, and a clock gene in mammals, was shown to also be a clock gene in Drosophila. This was the last element needed for the Transcritpion/Translation Feedback Loop model to be complete, and thus fully accepted by the field.
Transcription-translation feedback loop closed in Drosophila.
CYCLE - a core circadian clock gene in fruitflies discovered.
Discovery of Bmal/MOP/Arntl clock gene in mammals.
Takahashi lab discovered and cloned the Clock gene in the mouse, starting the explosion in research on mammalian clock genetics.
The wc ("white collar", or, behind the closed doors: "water closet") genes close the transcription/translation feedback loop in the Neurosopora crassa fungus.
Three papers in Science describing timeless in fruitflies, trigger an explosion in genetic research on clocks in flies and a large influx of geneticists from other fields into chronobiology.
Clock genes now found in another Kingdom - plants.
First clock genes - including KaiA, KaiB and KaiC - discovered in the cyanobacterium Synechococcus.
Until 1993, it was thought that Prokaryotes did not have clocks. This paper showed they do, and opened up a new avenue for a lot of productive research.
Neurospora crassa is the fungus of choice of circadian research and mutations have been discovered early on. The sequencing of a number of clock genes happened in the 1980s, starting with frequency (frq). This is also the discovery of the first clock-controlled genes, i.e., genes whose expression is directly controlled by clock genes.
In Mike Menaker's lab, Martin Ralph discovered a clock mutant in a shipment of hamsters. He bred her and established a strain of tau-mutants which has been used in research for decades since. This was the first known clock mutation in mammals which was much later shown to be the gene called Kaseine kinase A, which is the equivalent of fruitfly 'doubletime'.
Discovery of the first genetic mutation of circadian rhythms in the fungus Neurospora crassa - the "frequency" (frq) gene.
In 1971, Victor Bruce discovered the first circadian mutant in a protist Chlamydomonas
The history of clock genetics starts with the identification of the period mutant in Drosophila melanogaster by Konopka and Benzer in 1971. Discovery of this gene was an entry point for discovery of many canonical clock genese and clock-associated genes in the fly and in other organisms.
After decades of studying rhythmic phenomena in a variety of organisms, scientists got together at Cold Spring Harbor in 1960 for the foundational meeting of the field. Structure of DNA was new at the time, and comparatively little was known about the inner workings of a cell. But most researchers were eager to break into the 'black box' and start investigating how the circadian clock ticks inside of cells. A number of models were proposed, some focusing on cell membranes, others on DNA. Thus, experiments were started to test the role of nucleus and DNA in the clock mechanism. This timeline shows the successes in the study of clock genetics. The other timeline - History of challenges to the DNA-based circadian clock - chronicles experimental results that pose difficulties to the DNA-centered view. DNA is important, but not sufficient to explain the circadian clock. Compare and contrast the two timelines.