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All major retinoids (vitamin A) stored in the liver of lake sturgeon from two Québec lakes were analysed by high-performance liquid chromatography (HPLC). Four HPLC peaks represented approximately 90% of all liver retinoids. Their relative proportion was remarkably consistent in the two sturgeon populations with dehydroretinyl palmitate/oleate accounting for the largest proportion (50-60%). Most retinoids demonstrated significant positive correlations with age, but only in the Lake Berthelot sturgeon. The concentrations of all major retinoids were significantly (P<0·0001) lower, as much as 40 times lower, in the Lake Saint-Louis population. Possible explanations for the extremely low liver stores in the Lake Saint-Louis sturgeon are discussed.1998 The Fisheries Society of the British Isles

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The distribution of nucleases of the microsomal fraction of rat liver between ribosomes and endoplasmic membranes was studied. The results show that the ribosomes contained a ribonuclease (RNase) inhibited by Mg++ ions but activated by ethylenediaminetetraacetic acid (EDTA). Furthermore the degradation products of this enzyme were found to possess a 3′-phosphomonoester end group. The endoplasmic membranes contained a 5′-RNase that could degrade the purine—purine linkage of polyadenylic acid, and a 5′-phosphodiesterase.