CHEMICAL ECOLOGY - A NEW APPROACH TO THE STUDY OF LIVING BENTHIC EPIPHYTIC FORAMINIFERA

Interactions of living benthic epiphytic foraminifera, Pararotalia spi nigera (Le Calvez) and Rosalina macropora (Hofker), with unidentified natural organic compounds (UNOC) derived from decomposed seaweeds, hea vy metal ions and three tracer xenobiotics, acridine orange (AO), neut ral red (NR) and fluorescein (FLU), were investigated, Changes of redo x state of nicotinamide adenine dinucleotide (NAD) in foraminifera, in duced by UNOC, indicated that these compounds contained both metabolic substrates and toxic components (natural uncouplers), The presence of toxic components in UNOC was confirmed by results of a dye extrusion test,vith FLU with cadmium ions acting as an uncoupler. The following defense mechanisms against xenobiotics were discovered in foraminifera studied: (1) mucopolysaccharide coat that forms additive diffusion ba rriers and binds some cationic xenobiotics, (2) plasma membrane that f orms impermeable diffusion barrier against natural and anthropogenic a nionic xenobiotics, (3) membrane carrier-mediated transport system for elimination of anionic xenobiotics from the cell, (4) active intralys osomal accumulation and isolation of some cationic xenobiotics, (5) pe roxidases that protect foraminiferal cytoplasm against an excess of ox ygen and peroxides, (6) haloperoxidases that protect the cytoplasm aga inst Br-and I- penetration and produce brominated or iodinated xenobio tics, and (7) metallthioneine-like Cu2+-binding tryptophan-containing proteins protecting the foraminifera against some toxic metals. Presen ce of UNOC in seawater decreased acute toxicity of heavy metal ions fo r foraminifera, The state of the defense system against xenobiotics in benthic epiphytic foraminifera can serve as a very sensitive biomarke r for monitoring and prediction of ecological consequences of anthropo genic pollution.