Circadian Rhythms

Lipids with Rhythm

Science's STKE  12 Sep 2000:
Vol. 2000, Issue 49, pp. tw4
DOI: 10.1126/stke.2000.49.tw4

The Neurospora crassa mutant chol-1 exhibits a lengthened period for spore formation. In chol-1 mutants, the period length can be controlled by the amount of choline that is added to the growth medium. Ramsdale and Lakin-Thomas show that the lengthened period correlates with an increase in diacylglycerol (DAG). The period can be artificially lengthened in chol-1 mutants by pharmacologic treatments that elevate DAG, suggesting that DAG levels contribute to the control of rhythmicity. In both aging portions and growing portions of cultures of wild-type Neurospora and chol-1 mutants supplemented with choline, DAG levels fluctuate with a bimodal periodicity in response to constant darkness with a shorter period in the first 40 hours of constant darkness and a longer period thereafter. The frq gene is also implicated in controlling the Neurospora clock. DAG levels fluctuated in frq mutants; however, the period was decreased, suggesting that DAG rhythmicity is independent of FRQ but that the length of the period is influenced by FRQ. These results imply the existence of dual interacting oscillators: one that directly involves FRQ, which could then influence the oscillator that controls the DAG rhythm.

Ramsdale, M., and Lakin-Thomas, P.L. (2000) sn-1,2-Diacylglycerol levels in the fungus Neurospora crassa display circadian rhythmicity. J. Biol. Chem. 275: 27541-27550. [Abstract] [Full Text]