Sex-specific mediation of foraging in the shore crab, Carcinus maenas

Experiments were conducted to investigate the sex-specific differences to feeding responses of the shore crab Carcinus maenas throughout the year. Results demonstrate that female shore crabs exhibit stronger feeding responses than males throughout the year with a significantly reduced feeding response in males during the summer months' reproductive season. We also studied the possible function(s) of the moulting hormone, 20-hydroxyecdysone (Crustecdysone) that has been described as a potential female-produced sex pheromone to initiate male reproductive behaviour in a number of crustaceans. We recently presented evidence that for shore crabs this is not the case and now show that the steroid is instead functioning as a sex-specific feeding deterrent protecting the moulting 'soft' female crabs. Whilst male shore crabs were deterred from prey (Mytilus edulis) and synthetic feeding stimulants glycine and taurine when these feeding stimulants were spiked with crustecdysone, intermoult female crabs were significantly less affected and rarely deterred from feeding. This sex specificity of the moulting hormone, in combination with the female sex pheromone, which has no anti-feeding properties, ensures that male crabs mate with soft-shelled, moulted females rather than engage in cannibalism, such as found frequently in cases when soft-shelled females are exposed to intermoult females.     

To signal or not to signal? Chemical communication by urine-borne signals mirrors sexual conflict in crayfish

Background  

Sexual selection theory predicts that females, being the limiting sex, invest less in courtship signals than males. However, when chemical signals are involved it is often the female that initiates mating by producing stimuli that inform about sex and/or receptivity. This apparent contradiction has been discussed in the literature as 'the female pheromone fallacy'. Because the release of chemical stimuli may not have evolved to elicit the male's courtship response, whether these female stimuli represent signals remains an open question. Using techniques to visualise and block release of urine, we studied the role of urine signals during fighting and mating interactions of crayfish (Pacifastacus leniusculus). Test individuals were blindfolded to exclude visual disturbance from dye release and artificial urine introduction.     

Rapid high-pressure liquid chromatographic determination of methotrexate and its metabolites 7-hydroxymethotrexate and 2,4-diamino-N10-methylpteroic acid in biological fluids

A rapid and sensitive high-pressure liquid chromatographic method for determination of methotrexate and its metabolites 7-hydroxymethotrexate and 2,4-diamino-N¹⁰-methylpteroic acid has been developed. The assay is based on isocratic reversed-phase chromatography with siliceous microparticulate Spherisorb (5 μm, ODS, 15 × 0.4 cm i.d.) as stationary phase and a ternary solvent mixture of citrate-phosphate (0.05 m, pH 3.2)/methanol/tetrahydrofurane (80:16:4, v/v) as eluant. A precolumn of Perisorb (RP2, 30–40 μm, 3 × 0.4 cm i.d.) reasonably protects the analytical column against deterioration by the components of plasma or other biological fluids. Since the samples of plasma, urine, or cerebrospinal fluid are directly injected into the chromatographic system, the method is very rapid. Within 8 min as little as 50 ng of methotrexate and its metabolites per milliliter (10^?7m) can be measured with a precision better than 7%. Structural analogs of methotrexate do not interfere with the determination. There is a good correlation with the results of other methods, e.g., enzyme immunoassay or radioimmunoassay. The applicability for clinical monitoring in patient's plasma and urine is demonstrated.     

High dosage desferrioxamine therapy in a female patient with acquired aplastic anaemia and transfusion siderosis

A 32 year old woman with severe aplastic anaemia required frequent transfusions and consequently developed hyperferrioxaemia (54 microMol/l) and hyperferritinaemia (1,700 ng/ml). For the treatment of transfusion siderosis she was given 18 high dose courses each comprising 35 g of desferrioxamine. Because of pre-existing thrombocytopenia (platelet count 5 X 10(9)/l) the iron chelating agent was given by continuous intravenous infusion over 3 1/2 days. High dose desferrioxamine had to be abandoned because of severe bone pain. The desferrioxamine infusions achieved a negative iron balance, iron loss after each infusion being 100 to 200 mg in the urine and 400 mg in the faeces. Serum iron and ferritin concentrations fell almost to normal. This report shows that faecal iron excretion must be taken into account in assessing the balance of iron input and output during desferrioxamine treatment.     

An adenosine 3':5'-monophosphate-dependent protein kinase from the human erythrocyte membrane. Purification and characterization.

An adenosine 3':5'-monophosphate-dependent protein kinase (ATP:protein phosphotransferase, EC 2.7.1.37) has been isolated from the human erythrocyte memebrane and the phosphotransferase activity exhibited by this enzyme has been purified 800-fold. In concentrated solutions, the membrane-derived protein kinase undergoes aggregation with a concomitant loss in observed phosphotransferase activity. This loss of activity can be restored by means of inducing deaggregation. The phosphotransferase activity of the protein kinase is virtually obliterated in the presence of high (300 mM) concentrations of sodium chloride. This effect is also reversible. The pH optimum for the phosphotransferase reaction that is catalyzed by the membrane-derived protein kinase is approximately 8. Micromolar concentrations of cAMP are optimal with respect to promoting the phosphotransferase reaction. Initial velocity and product inhibition studies were conducted on the cAMP-independent protein kinase derived from the cAMP-dependent enzyme. These studies indicate that the phosphotransferase reaction proceeds by a sequential kinetic mechanism.     

The oldest record of serpent aggregation

Three virtually complete skeletons in east-central Wyoming of the Oligocene erycinine boid snakes Ogmophis and Calamagras represent the oldest known record of serpent aggregation. The skeletons are articulated and coiled loosely together in life-like positions in a horizontal plane within sediments of the White River Formation. The fossils represent an autochthonous, fluvial burial of snakes some 32 million years ago. Taphonomic considerations suggest the preservation of an aggregative event that occurred just prior to death. We suggest that serpent aggregation is a conservative, relatively unchanged form of behaviour, with a minimum age of 32 million years before present.