BIOMINERALIZATION IN DISCOPYGE TSCHUDII ELECTRIC ORGANS

MARÍA PRADO FIGUEROA1; NORA N. CESARETTI

Montevideo, Uruguay

Congreso; 3er Hemispherical Conference of Medical Geology, Octubre 2009, Montevideo – Uruguay.; 2009

International Medical Geology Association (IMGA)

South American ray Discopyge tschudii (Torpediniforme) is an electric fish. Torpedinidae  have since constituted the choice system for studying the biochemistry, morphology, physiology, and cell biology of the cholinergic system in general (Prado Figueroa and Barrantes, 1989). In this study the electric tissue was analyzed by mineralogical microscope (DMLP Leica). The aim of this stage was to study some characteristics which are not detected by biological microscope. The obtained results are useful and applicable to other alive organism, due to the similarity with human nervous cholinergic system. Here is the link with medical geology. In electric organ was identified permineralization (Fernández López, 2000) by silica. This one shows two different stages of  crystallization.  One is constituted by a cryptocrystalline variety and the other is constituted by a microcrystalline one. The cryptocrystalline variety is placed at the end of the channels and into the nucleus. It shows an irregular continuous arrangements (salt and pepper). The other variety develops chalcedony as spheres with a exactly defined axial cross, reaching 15-20 mm in diameter. Probably the silica should be as a gel state which would be precipitated as a cryptocrystalline form at Eh between 0.0 to –0.2 and pH ranging 7 to 8. With the time, this one could be evolved to a more mature form constituted by a microcrystalline form defining  chalcedony spheres. The immature variety should place in the external area belonging to a extracellular matrix. The incoming flow cause the permineralization through the permeable membrane and into the cell the chalcedony is precipitated.   1. M. Prado Figueroa and F.J. Barrantes, Ultrastructure of Discopyge tschudii electric organ. Micr. Electr. Biol. Cel. 13: 9-38. (1989). 2. S. Fernández López, Temas de tafonomía. Departamento de Paleontología. Fac. Cs. Geol. Universidad Complutense de Madrid. 167 pp. (2000).