Description

Abstract: Almost all organisms have a day-night rhythm that makes certain activities, such as eating and sleeping, occur at fixed times of the day. This rhythm is dictated by a biological clock with a period of about 24 hours: the circadian clock (from the Latin words circa -unlike- and diem -day). One of the big questions is how this clock can keep 'ticking' stably in growing and dividing cells, in which components of the clock are also duplicated. In a growing organism, the cells go through a cell cycle in which all parts are copied, including the DNA and genes on it. This leads to a periodic doubling of the production rate of the proteins that make up the biological clock. In existing theories of how clocks work, this doubled production of clock proteins causes a disruption of the 24-hour rhythm. Just as physicist Huygens showed back in the 17th century with two pendulum clocks linked together, the biological clock is linked to the period of the cell cycle. Depending on circumstances, that cell cycle lasts from a few hours to a few days. So a biological clock linked to the growth rate cannot possibly maintain a fixed 24-hour period.

In this lecture, I first give an overview of how living cells process information and perform calculations and measurements using DNA, genes, and proteins. I then describe one of the best-characterised clocks in biology, that of a cyanobacterium (blue-green algae). I then present two mechanisms that may protect this organism's clock from disruption by cell division. A mathematical model shows that a clock with these two ingredients is indeed stable and ticks with a period of 24 hours, regardless of the cell's growth rate.


Piet Rein ten Wolde:
https://amolf.nl/people/pieter-rein-ten-wolde

The drinks will start at 18:00 and the meal will follow punctually at 19:00.

Sign up by 12 March 2017 before 12:00.

Speaker(s)

Piet Rein ten Wolde

Location

Bar Brasserie Engels

Stationsplein 45,3013 AK Rotterdam

Organiser

Rotterdam Circle