Building Protocells -- 4pm, January 27th, room 397, MIT Stata Center-- given by Irene Chen

[Alexander (Sasha) Wait]

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The next talk is sponsored by Gerald J. Sussman of Project MAC at MIT.
It will be held at 4pm, Room 397, MIT, CSAIL, Building 32, The Stata
Center, 32 Vassar Street Cambridge, MA 02139. Abstract at:

* http://non.fiction.org/~await/alife/talks/20050127.chen.html

Irene Chen (Harvard Biophysics) will be talking about her work (in Jack
Szostak's lab, published in Science last fall) on "Building Protocells".

> We are exploring simple mechanisms by which cellular-level traits may
> arise in model protocells. The encapsulation of genetic material by a
> semipermeable membrane was presumably an important transition during
> the origin of cellular life. How might these two components, the
> membrane and the genome, combine to produce a unified cellular
> 'system'? Using vesicles composed of prebiotically plausible
> amphiphiles, we first demonstrated that membrane growth causes the
> generation of a transmembrane pH gradient, which can be sustained for
> several hours under certain conditions. The energy stored in such
> gradients would be available for use in cellular processes, such as
> genomic replication. This illustrates how the growth of one component,
> the membrane, might convey a fitness advantage to the protocell.
>
> Second, we observed the emergence of Darwinian selection between
> vesicles encapsulating RNA and empty vesicles. Vesicles containing
> high concentrations of RNA experienced substantial osmotic stress,
> which drove the uptake of membrane components from unstressed
> membranes. Therefore during protocellular evolution, vesicles
> encapsulating highly active genomic replicators might grow at the
> expense of other vesicles, effectively translating genomic fitness
> into protocellular fitness. These results highlight the prospect of
> building a protocell with apparently complex behaviors using simple
> components and physico-chemical processes.
>

Irene is a great speaker and this is fascinating, ground-breaking work.

Hope you can all make it!

--ASW