A. De Zwaan

Anaerobic metabolism in bivalvia (Mollusca) Characteristics of anaerobic metabolism

Abstract 1. 1. The role of carbohydrates (glycogen, trehalose, glucose), lipids and proteins as forms of energy storage during aerobiosis and anaerobiosis is discussed. 2. 2. Fatty acid and amino acid conversions cannot be ruled out during anaerobiosis, but this is accompanied by a simultaneous mobilization of carbohydrates. 3. 3. Carbohydrates are therefore the main energy reserve stores under this condition. A Pasteur effect has been shown only in a few studies. The consumed carbohydrates form only a fraction of the pool size. This may be the result of a reduction of the metabolic rate during anaerobiosis. 4. 4. Calculations of ATP production and consumption reveal that the lowest possible energy demand is far below that of the standard rate. 5. 5. Anaerobiosis may lead to the accumulation of pyruvate, lactate, octopine, succinate, alanine, acetate, propionate and CO 2 . The ratio in which these compounds accumulate alters with time. Alanine and lactate are probably initial end products. 6. 6. Stoichiometric studies between consumed fuel substrates and accumulated compounds are discussed. 7. 7. There is a relationship between pH changes and shell movements. During shell closure there is a gradual decrease in pH. 8. 8. ATP levels decrease during anaerobiosis.

Body distribution and seasonal changes in the glycogen content of the common sea musselMytilus edulis

1. Glycogen content was measured in the sea musselMytilus edulis, and found to be present in amounts ranging from 10 to 35 per cent dry weight of the soft parts. 2. The annual glycogen cycle was followed for five different fractions: the digestive gland, muscles (including those of the foot), gills, mantle and residue. Seasonal changes in gills and muscles were much smaller than in the other tissues. 3. The annual glycogen cycle for the total animal consisted of a rapid increase in spring and early summer, followed by small fluctuations in the late summer. In autumn and early winter there was a gradual decline reaching a minimum of about 10 per cent in February and March. 4. There was an interrelation between seasonal changes in dry weight and the percentage of glycogen.

The utilization of glycogen and accumulation of some intermediates during anaerobiosis in Mytilus edulis L.

Abstract 1. 1. Glycogen degradation in the mussel under anaerobic conditions was measured at two temperatures. Glycogen decrease at 6·6°C was about 3 mg and at 20°C about 6 mg/24 hr per mussel. A Pasteur effect was observed. 2. 2. The decrease of glycogen was almost entirely restricted to muscles, including the foot and hepatopancreas. 3. 3. During anaerobiosis there was a significant increase in succinate and alanine, whereas almost no increase in l -lactate was found. There was some accumulation of d -lactate. Alanine and succinate were formed in almost equimolar amounts and accounted for about 50 per cent of the degraded glycogen.

Physiological and biochemical aspects of the valve snap and valve closure responses in the giant scallopPlacopecten magellanicus

Summary1.The giant scallopPlacopecten magellanicus responds to stimulation with starfish extract by snapping the valves in a series of rapid adductions. After approximately 25–35 adductions, the scallop does not respond to further stimulation, and usually closes the valves.2.Snapping of the valves results in an accelerated heart rate, increased stroke volume and enhanced cardiac output. The supply of oxygen to the adductor muscle will be increased but must be insufficient, as blood

Activity And Metabolism In The Mussel Mytilus-Edulis-L During Intertidal Hypoxia And Aerobic Recovery

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Aerobic Metabolism Octopine Production And Phosphoarginine As Sources Of Energy In The Phasic And Catch Adductor Muscles Of The Giant Scallop Placopecten-Magellanicus During Swimming And The Subsequent Recovery Period

decreases to 15 mm Hg and energy-producing anaerobic pathways are invoked (de Zwaan et al., 1980). There is an increase in the total carbon dioxide content of the blood and a fall in blood pH. When the scallop reopens, there is a transient increase in oxygen uptake.3.The restoration of physiological functions to normal values takes several hours.4.During valve closure, the

The role of phosphoenolpyruvate carboxykinase in the anaerobic metabolism of the sea musselMytilus edulis L.

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