Absence of cholesterol synthesis as contrasted with the presence of fatty acid synthesis in some arthropods

1. 1. After administration of acetate-1-14C absence of cholesterol synthesis was demonstrated in the lobster Homarus gammarus (L.), the spider Avicularia avicularia (L.) and in the millepede Graphidostreptus tumuliporus (Karsch). 2. 2. However, the animals utilize acetate for the synthesis of fatty acids (except for polyunsaturated ones) and for some non-saponifiable lipids. 3. 3. Gas-liquid chromatography analyses demonstrated even- and odd-numbered fatty acids, saturated and unsaturated ones, iso, anteiso and probably neo-branched-chain fatty acids. 4. 4. The fatty-acid composition of the mixtures from the animals and the biosynthesis of the fatty acids are discussed

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

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 -lactate was found. There was some accumulation of -lactate. Alanine and succinate were formed in almost equimolar amounts and accounted for about 50 per cent of the degraded glycogen

Amino acid metabolism of Astacus leptodactylus Esch.—III. Studies on the biosynthesis of α- and β-alanine from aspartate

1. 1. Six hours after injection of 1- or 4-14C-aspartate into the crayfish Astacus leptodactylus almost all radioactivity incorporated was found in the amino acids. 2. 2. From both precursors only the amino acids α-alanine and glutamic acid were labelled. The biosynthesis of α-alanine from aspartate via decarboxylation of aspartate, oxaloacetate or malate is discussed. 3. 3. No synthesis of β-alanine via α-decarboxylation of aspartate had occurred during the incubation period. Its probable formation through the pyrimidine metabolism is discussed

Body distribution and seasonal changes in the glycogen content of the common sea mussel Mytilus 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

What about squalene in the earthworm Lumbricus terrestris?

1. 1. It is shown that Lumbricus terrestris does not utilize 14C-labelled squalene for the biosynthesis of sterols. 2. 2. The squalene administered was metabolized rapidly and radioactivity was recovered in several lipids, making it unlikely that accumulation of radioactivity in squalene might occur. 3. 3. The distribution of radioactivity in the hydrocarbons of L. terrestris after the administration of sodium acetate-1-14C was investigated. 4. 4. Both saturated and unsaturated straight-chain and branched hydrocarbons were radioactive. 5. 5. Squalene was present in a very small quantity and may be of exogenous origin

Occurrence of calcium concretions in various tissues of freshwater mussels, and their capacity for cadmium sequestration

The freshwater unionids Anodonta anatina, Anodonta cygnea and Unio pictorum were examined with respect to the distribution of calcium concretions among the various organs, and to a possible role of concretions in heavy metal detoxification. Gills of all three species contain large amounts of concretions, up to 55% of the tissue dry weight in A. cygnea. Smaller amounts are present in the mantle and the midgut gland, and also in granulocytes. The other organs, including the kidney, are practically devoid of concretion material. By electron-microprobe analysis, the concretions appear to be of the phosphatic type, and also contain manganese, iron and zinc. When animals were exposed to CdCl2, cadmium was bound to the concretion fraction of the various organs. But, in almost all cases, Cd concentrations in the concretion material were lower than those in the whole organ. Furthermore, the contribution of the concretion fractions in Cd accumulation decreased over the course of exposure. It is concluded that calcium (pyro)phosphate concretions do not function as preferential sequestration sites for cadmium

The influence of seasonal changes on energy metabolism in Mytilus edulise (L.).—III. Anaerobic energy metabolism

1. 1. Seasonal changes in the accumulation of end products after 48 hr of exposure to air and in the composition of the free amino acid pool were studied in Mytilus edulis. 2. 2. The accumulation levels of succinate and acetate showed only weak seasonal changes. 3. 3. Conversion of succinate to propionate was high in summer and virtually zero in winter 4. 4. Alanine and most other free amino acids were present in relatively high concentrations in summer and early autumn and reached minimal values in winter and early spring. 5. 5. Exceptions were glutamate, aspartate and taurine, which showed hardly an season related changes and glycine, which changed inversely to the majority of the free amino acids. 6. 6. The anaerobic formation of alanine was inversely proportional to the endogenous concentration. 7. 7. The only other free amino acids affected by anaerobiosis were glutamate and aspartate, which respectively increased and decreased under these conditions