Intracellular Reactions Controlling Environmental Anaerobiosis in the Marine Annelid Arenicola Marina, A Fresh Look at Old Pathways

Several aquatic species of various phyla are well adapted for surviving prolonged periods of hypoxia. Their anaerobic metabolism is characterized by a dramatic reduction of energy output and by pathways yielding excretable end products sometimes combined with an improved ATP/substrate ratio. These strategies have been demonstrated in many facultative anaerobes, but the regulatory mechanisms controlling these energetic pathways are still under discussion. This report summarizes results about the regulation of hypoxic energy metabolism as particularly obtained from the marine lugworm Arenicola marina . A cascade of intracellular reactions is proposed by which the degradation of the main energy source, glycogen, can be explained. P 1 and pH might be important effectors for stimulation and depression of glycogenolysis during hypoxia.