Friday, January 14, 2005

ClockNews #6: Cyanobacteria, Post-lunch dip, Student Jet-Lag and Neccessary Randomness,

No Transcription-Translation Feedback in Circadian Rhythm of KaiC Phosphorylation

An autoregulatory transcription-translation feedback loop is
thought to be essential in generating circadian rhythms in any model organism.
In the cyanobacterium Synechococcus elongatus, the essential clock protein KaiC
is proposed to form this type of transcriptional negative feedback.
Nevertheless, we demonstrate here temperature-compensated, robust circadian
cycling of KaiC phosphorylation even without kaiBC messenger RNA accumulation
under continuous dark conditions. This rhythm persisted in the presence of a
transcription or translation inhibitor. Moreover, kinetic profiles in the ratio
of KaiC autophosphorylation-dephosphorylation were also temperature compensated
in vitro. Thus, the cyanobacterial clock can keep time independent of de novo
transcription and translation processes.

There's nothing swinish about afternoon slumbers

You shouldn't feel the least bit guilty taking a nap in the
afternoon. In fact, those 40 winks can make you more mentally alert and,
contrary to popular wisdom, a well-timed nap won't interfere with your nighttime

"People think you're lazy if you nap, or not using your time
wisely, but napping is an integral part of our circadian rhythm," Patricia
Murphy, a professor at Weill Cornell Medical College in White Plains, N.Y., said
in an interview.

Lack of sleep leads students down hazy path

"You can actually become psychotic if you're going long
periods of time without sleep," Douce told a group of students. "It's like
having an ocean on top of you - you're just dull and inattentive."

NYU researchers simulate molecular biological clock

Researchers at New York University have developed a model of
the intra-cellular mammalian biological clock that reveals how rapid interaction
of molecules with DNA is necessary for producing reliable 24-hour rhythms. They
also found that without the inherent randomness of molecular interactions within
a cell, biological rhythms may dampen over time.


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