Re: Biomineralization

[To~nu Meidla <tmeidla@xxxxxxxxxx>]

On Mon, 4 Nov 1996, Mike Simmons wrote:

> I'm wondering if subscribers to PaleoNet or Micropal might be able to 
> help and advise me. 
> 
> Along with colleagues at University College London, the Natural 
> History Museum and Moscow State University, I'm looking at the 
> earliest planktonic foraminfera (Middle Jurassic - Early Cretaceous). 
> Taxonomic revision and synthesis is well in hand, but in the course 
> of our work, we've been analysing the composition of the tests of 
> these forms. Following on from observations from Russian workers, 
> we're able to confirm that (some) of these taxa had aragonitic tests. 
> Others are calcitic, but this may well we secondary (work is ongoing). 
> As far as I know (correct me if I'm wrong) all modern planktonic 
> foraminifera are primary calcite as are Late Cretaceous and Tertiary 
> forms. 
> 
> My major question here is what governs if an organism secretes a 
> calcitic or aragonitic shell? I've tried to investigate this topic but so 
> far all the references I've seen are vague. Perhaps this is an area in 
> which palaeontologists should be talking more with cell biologists? 
> Maybe someone out there is working on this problem or can point me 
> in the direction of someone who is. Is there an obvious reference I 
> have missed?

Dear Mike,

concerning calcite and aragonite, did you check Falini, Albeck,
Weiner&Addadi (Control of aragonite or calcite polymorphism by Mollusc
Shell Macromolecules) in Science, January 5th, 1996?

To~nu Meidla
University of Tartu
tmeidla@math.ut.ee