Pyruvate oxidoreductases involved in glycolytic anaerobic metabolism of polychaetes from the continental shelf off central-south Chile

The presence of low oxygen conditions in extensive areas of the continental shelf off central-south Chile has important effects on the biochemical ada ptations of the organisms living in this ecosystem. Polychaetes assemblages cohabit on the shelf with an extensively distributed prokaryotic community made up of giant filamentous sulfur bacteria (mainly Thioploca sp.). The a im of this research was to characterize the pyruvate oxidoreductases enzyme s involved in the biochemical adaptation of these benthic polychaetes. Nine polychaete species (Paraprionospio pinnata, Nephtys ferruginea, Glycera am ericana, Haploscoloplos sp., Lumbrineris composita, Sigambra bassi, Aricide a pigmentata, Cossura chilensis, and Pectinaria chilensis) were assayed for lactic dehydrogenase (LDH), octopine dehydrogenase (OPDH), strombine dehyd rogenase (STRDH) and alanopine dehydrogenase (ALPDH). Each species had a ch aracteristic number of the pyruvate oxidoreductases assayed ranging from 4 in Paraprionospio pinnata to I in Pectinaria chilensis. The pyruvate satura tion curves obtained for the enzymes from all species analysed, except L. c omposita, suggest that NADH can be oxidized at different rates depending on the amino acid used in the reaction with pyruvate. Our results indicate th at organisms having more that one pyruvate oxidoreductase present a greater metabolic capacity to cope with functional and environmental hypoxia becau se these enzymes would better regulate the pyruvate consumption rate during the transition period. Thus, the dominance of Paraprionospio pinnata in th e study area and its worldwide distribution is consistent with its higher n umber of pyruvate oxidoreductases with different pyruvate consumption rates involved in anaerobic metabolism. Finally, a positive allometric relations hip was found between body size and the specific activity of ALPDH, STRDH, and maximum pyruvate oxidoreductase specific activity. This latter result s uggests a positive scaling of the (C) 2000 Academic Press.