Biomineralization in Coccolithophores

Abstract

processes which generate and maintain a medium supersaturated with respect to CaCO 3 at mineralizing foci throughout calcite nucleation and crystal growth; it includes temporally and spatially controlled mechanisms for amassing calcium and bicarbonate ions and removing hydrogen ions. Nucleation refers to all processes and factors other than ion accumulation that determine the rate and site of calcite nucleation, and the crystallographic orientation of the initial mineral phase. Growth includes all processes subsequent to nucleation that regulate crystal growth and morphology.The remainder of this chapter describes the molecular, cellular and structural aspects of coccolith formation in Pleurochrysis, Emiliania and Coccolithus as it is presFigure 12.1 Scanning electron micrographs of coccolithophores. (a) Pleurochrysis carterae (reproduced from Marsh [13]). The mineralized rims (arrow head) and organic base plates (Â) of the coccoliths are indicated. (b) Emiliania huxleyi. (c) Coccolithus pelagicus (image by S. Nishida). Bar ¼ 1.0 mm. Heterococcolith-bearing Morphotypes

Biomineralization Within Vesicles: The Calcite of Coccoliths

“…Coccolith biomineralization has been rather extensively researched; reviews include de Vrind-de Jong et al (1986, Westbroek et al (1989), Pienaar (1994), de Vrindde Jong and de Vrind (1997), Young et al (1999), and Marsh (2000). This interest reflects both the importance of coccolithophores and the fact that, as rapidly reproducing protists, they are amenable to laboratory culture and study.…”

“…The parallel approaches of biochemical and morphological research have been applied rather extensively to coccolithophore calcification and are arguably at a relatively mature state of knowledge, although new insights are emerging from atomic force microscopy (Henriksen et al in press a,b) and from study of polysaccharide effects in mutant strains (Marsh and Dickinson 1997;Marsh 2000). Probably the most promising approach for the future will be genomic research aimed at identifying the suite of genes responsible for biomineralization and their functions.…”

Biomimetic Model Systems for Investigating the Amorphous Precursor Pathway and Its Role in Biomineralization

“…84,288–290 Marsh has also shown that high-capacity calcium-binding proteins, such as those found in bivalve phosphoproteins and dentin phosphophoryn (with apparent M.W. of around 100,000Da), can self associate in the presence of calcium ions.…”

Cell Wall Evolution and Diversity

“…The distal portion of this vesicle consists of a distinct reticular body that is comprised of a continuously changing membranous mass containing organic material derived from the Golgi body and endoplasmic reticulum. The reticular body becomes closely associated with the CV from the time of crystal nucleation to secretion (Kayano et al 2010;Marsh 1999;Taylor et al 2007;Brownlee and Taylor 2004). It is thought that these features provide an important regulatory role of the reticular body in supplying the organic and inorganic materials required for calcification (Drescher et al 2012).…”

“…However, one of the most spectacular calcification processes in an ECM of a photosynthetic eukaryote occurs in haptophytes or prymnesiophytes (Graham et al 2009). The covering of many taxa within this algal group is characterized not by a cell wall but by a coccosphere that is comprised of multiple plate-like coccoliths (Marsh 1999). A coccolith consists of an organic base plate to which calcite is complexed Mackinder et al 2010).…”