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SUMMARY:“Formation of intracellular earth-alkaline carbonates by Cyanoba
 cteria”
DTSTART:20140327T140000
DTEND:20140327T150000
DTSTAMP:20260924T175352Z
UID:17bea673c116c7caf766fd9dceafe91465a57b84ecfcace0507ef482
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Karim Benzerara\, IMPMC Paris\nCyanobacteria have had a pi
 votal role on the global cycle of carbon throughout the Earth’s history 
 in particular by inducing the formation of carbonate deposits. Yet the mec
 hanisms involved in carbonate biomineralization by cyanobacteria remain po
 orly known. For example\, this process had so far been considered exclusiv
 ely as an induced and extracellular biomineralization process. However\, w
 e recently discovered deep-branching cyanobacteria that form intracellular
  amorphous Ca-Mg-Sr-Ba carbonates [1]. These intracellular carbonates are 
 quite different from usual carbonates: 1) They appear as nanospheres with 
 a diameter between 100 to 500 nm\; 2) They are poorly crystalline as infer
 red by electron diffraction\; 3) They contain high concentrations of stron
 tium and barium\, much higher than in the extracellular solution suggestin
 g a mechanism discriminating between earth alkaline elements (Ca vs. Sr vs
 . Ba). Several questions remain open: How significant is this process nowa
 days and in the past? To what extent do phases formed intracellularly by t
 hese cyanobacteria differ from abiotically formed carbonates?\n     
        In this talk\, I will illustrate the analytical issues that w
 e face when attempting to characterize these materials and their propertie
 s and will discuss in particular the use of high spatial and spectral reso
 lution spectro-microscoscopies. Moreover\, I will show some molecular biol
 ogy and microbiology approaches developed to better understand this biomin
 eralization process.\n(1) Couradeau\, Benzerara\, Gérard\, Moreira\, Bern
 ard\, Brown Jr..\, López-García (2012) Science 336\, 459-462.
LOCATION:GC D0 386 http://plan.epfl.ch/?lang=fr&room=gc+d0+386
STATUS:CONFIRMED
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