Extracellular organic matrix

Hauschka, P.V., Wians, F.H. (1989) Osteocalcin-hydroxyapatite interaction in the extracellular organic matrix of bone. Anatomical Record, 224,180-188. 

Biofilms are abundant in a multitude of aquatic environments in which they cover all kinds of inorganic and organic solid surfaces. Biofilms can be defined as microorganisms attached to a surface and embedded in an extracellular gellike matrix of polymeric substances. This matrix is excreted by the microorganisms themselves and may be enriched by molecules adsorbed from the surrounding water. 

The mineralized matrix of bone tissue is strained when loaded. Macro-molecular mechanical connections between the extracellular matrix and the osteocytic cell membrane exist and these connections may be capable of transmitting information from the strained extracellular matrix to the bone cell nuclear membrane. The basis of this mechanism is the physical continuity of the transmembrane integrin molecule, which is connected extracellularly with the macromolecular collagen of the organic matrix and intracellularly with the... 

Most MAAs are intracellular, although MAAs can be translocated to external surfaces of cells and organisms because MAAs are found in significant concentrations in the extracellular sheath matrix of some cyanobacteria and in coral mucus.134 163 176 Scytonemin is not found intracellularly. It is located extracellularly in association with the glycan sheath but is not a structural component of the sheath layer.194 197 Scytonemin concentrations are not uniform within the sheath layer, and variations are related to the age of the sheath. In Scytonema myochrous, higher concentrations of scytonemin occur near the base of filaments where the sheath is older and thicker, while at newly formed apical cells, the sheath is usually absent or devoid of pigment.198... 

Anatomical aspects. The skeletons of corals are formed of crystals of aragonite in an organic matrix. Calcification begins when the free-swimming larva attaches to the substratum. The larva then metamorphoses into a polyp which continues to deposit extracellularly CaCOs and organic matrix through the secretory activity of the calicoblastic epithelium. The epithelium is a layer of cells at the base of the polyp adjoining the skeletal area at which deposition takes place. 

Bone is composed primarily of an extracellular mineralized matrix with a smaller cellular fraction. The organic matrix is primarily type I collagen (90%) with lesser... 

Stages in the formation of bone are (1) synthesis and extracellular assembly of the organic matrix framework, (2) mineralization of the framework, and (3) secondary mineralization as the bone constantly forms and reforms. 

Direct interactions between the biofilm extracellular polymeric matrix constituents and antimicrobials, affecting diffusion and availability. The extracellular polymeric substances (EPS) consist of various organic substances such as polysaccharides, proteins, nucleic acids and lipids (Sutherland 2001). The EPS matrix delays or prevents antimicrobial products from reaching target microorganisms... 

Kielty, C.M., Hopkinson, 1., Grant, M.E. Collagen structure, assembly and organization in the extracellular matrix. In Connective Tissue and its Heritable Disorders Wiley-Liss, Chichester, pp. 103-147, 1993. 

It is of interest that proteins termed motility factors (55-70 kD) are secreted by fetal cells and some tumor cells. These proteins act as autocrine factors and stimulate rapid movement by these cells. Motility factors induce the formation of cell processes that are packed with actin filaments and have an increased number of receptors for the matrix proteins laminin and fibronectin. The latter enhance the ability of the cells to bind to the extracellular matrix. Thus, it is likely that motility factors influence the organization of the cytoskeleton through changes taking place at the cell surface (reviewed by Warn and Dowrick, 1989). 

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