On the spatial distribution, feeding and reproduction of the vermetid gastropod Dendropoma maximum

D. maximum is a dominant species of outer reef flats in the Red Sea, reaching densities of about 22/m² and biomass of 15.8 g dry tissue/m². A few individuals attached to loose rocks are found inside the breaker zone but they may have been dislodged by heavy seas from the outer reef flat. D. maximum feeds from a mucus net which is spread by wave action over the substratum. Hauling the net occurs at approximately 13 minute intervals throughout the 24 hours and lasts about two minutes. Neighbours with overlapping nets stimulate each other to haul and reduce feeding efficiency. The net is grasped by a pair of lateral jaws, tugged free of the substratum by rotation of the body and ingested by a zipper-like action of the lateral and marginal radula teeth. The robust, central and lateral teeth become worn, possibly while channelling out the substratum to accommodate new shell. Defaecation occurs about 2.4 times an hour, amounting to 10450 kcal/m²/y. Females may brood simultaneously at least 11 egg capsules at various stages of development, which are suspended by stalks from the roof of the shell and pass through a dorsal slit in the mantle. Each capsule contains–500 embryos which develop into larvae with simple, coiled shells 0.33 mm in diameter. There is no planktonic phase. Adult shells amount to 2.5 kg/m² on the outer reef flat, while dead shells are often occupied by blennies. Although D. maximum is not a specialized filter feeder, the highly developed ciliary mechanisms suggest that filtering may be an auxiliary feeding method.     

Aldehyde dehydrogenase isozymes in rat hepatoma-mouse fibroblast hybrids

A study of aldehyde dehydrogenase in rat hepatoma cells and rat hepatoma-mouse fibroblast hybrids revealed that the hepatoma cells had activity comparable to that found in whole rat liver and that the enzyme activity was suppressed in early hybrids and reappeared following chromosome loss. Starch gel electrophoresis and heat inactivation studies showed that a new form of enzyme was produced in the hybrids, possibly a heteropolymorphic combination between the HTC enzyme and a previously repressed mouse form. Staining methods for starch gel electrophoresis and histochemical detection of aldehyde dehydrogenase are described.This work was supported by grants from the Damon Runyon Foundation (DRG 1088s) and the Public Health Service (1-R01-Ca 12310-02).     

Correlation Between Degradation of Bacteriophage T2 Deoxyribonucleic Acid and the Resistance of Escherichia coli to Infection

The ability of certain strains of Escherichia coli to degrade T2 deoxyribonucleic acid to acid-soluble fragments is correlated with their high capacity to survive T2 infection.     

Androgen sulphate formation in male and female mice

1. After the administration of large doses of androsterone, epiandrosterone, dehydroepiandrosterone and testosterone to mice, females excreted more of the dose conjugated with sulphuric acid than did males. 2. Liver slices from female mice conjugated androgens with sulphuric acid to a greater extent than did slices from males. 3. Sulphotransferase preparations from livers of female rats and mice catalysed the formation of dehydroepiandrosterone sulphate at a faster rate than preparations from livers of the male animals. 4. A possible explanation for the observed sex differences is discussed.     

Androgen sulphate formation in male and female rats

1. After large doses of androsterone, epiandrosterone, dehydroepiandrosterone and testosterone, female rats excreted more of the dose conjugated with sulphuric acid than did the males. 2. Androgens were also incubated with liver slices from male and female rats. Slices from females conjugated androgens with sulphuric acid to a greater extent than did slices from males. 3. The amount of unchanged androgen present in the faeces of orally dosed animals was 4-35% of the dose.     

Inhibitory Effects of Dichlorophenoxyacetones on Auxin-induced Growth of Avena Coleoptile Sections

Six dichlorophenoxyacetones were synthesized and examined as potential metabolic antagonists utilizing Avena coleoptile sections and the straight growth assay procedure. Supplements of indoleacetic acid promoted growth of the sections which were inhibited by the analogs; the most inhibitory derivatives were 2,3-; 2,4-; 2,5-; and 3,4-dichlorophenoxyacetone which produced half-maximal growth responses (relative to the unaug-mented control growth) at concentrations of 106, 86, 80, and 62 μg/ml, respectively. A Lineweaver-Burk plot of the data for the inhibition by 2,4-dichlorophenoxyacetone and its reversal by indoleacetic acid appeared to represent an uncompetitive-like inhibition.