Ultrastructural alterations in euglenoids species as a result of the excess of organic matter in the culture medium.

CONFORTI, V; NANNAVECCHIA P.; TOLIVIA, A.; L. RUIZ; LEONARDI, P,

Alcalá de Henares, Madrid.

Simposio; 8th Internacional Symposium Use of Algae for Monitoring Rivers; 2012

Ultrastructural alterations in euglenoids species as a result of the excess of organic matter in  the culture medium   Visitación Conforti1, Paula Nannavecchia1, Laura Ruiz1, Analia Tolivia1 y Patricia Leonardi2   1 Dpto. Biodiversidad y Biología Experimental, Facultad de Cs. Exactas y Naturales, UBA y      IBBEA, CONICET.  1428, Buenos Aires, Argentina. 2 Univ. Nacional del Sur y CONICET. 8000, Bahía Blanca, Argentina.   conforti@bg.fcen.uba.ar   Excessive enrichment of freshwater bodies with organic matter is mainly caused by industrial, domestic and agricultural processes.  Depending on the characteristics and concentration of the pollutants, microalgae of these affected environments may suffer changes in their number, morphology, and ecophysiology.  In this type of freshwater body, we commonly observe euglenoid specimens with marked deformations [1], which we assume to be related to the excess of organic matter. To test this hypothesis, Lepocinclis acus and Phacus brachykentron were isolated from the Matanza River, Buenos Aires, Argentina, which presents a high degree of organic contamination derived from waste waters of the local meat industry [2]. These cells were cultured in soil water medium [3]. When transferred to medium enriched with soil beef extract, marked cell alterations were observed. These changes were unexpected in non-metabolic species, a condition which was previously shown in studies of the pellicle fine structure. Optical, scanning, and transmission electron microscopy observations show in both species marked morphological and ultrastructural alterations as a result of the enriched medium. Among these we can enumerate changes in cell dimension, strip number and orientation, increased number and volume of paramylon grains and vacuoles, the presence of membrane whorls in vacuoles, and cell lysis. These responses were fast, observed within 48 hours of exposure to enriched medium. In this presentation we will compare the fine structure of organisms grown in medium with and without organic matter enrichment and discuss their systematic and ecological importance.   References [1] Conforti, V.  Nov. Hedw. 53 (1991) 73-98. [2] Conforti, V., Alberghina, J. & Gonzalez Urda, E.  J. Aquatic Ecosystem  4 (1995) 59-75. [3] Pringsheim, E. G.  J. Ecol. 33 (1946) 193-204.