Tool-use by a rook (Corvus frugilegus), and its causation

A young captive rook, Corvus frugilegus, inserted a plug into a plug-hole in its aviary floor so that a pool of water formed, which was used by all four rooks in the aviary for drinking and bathing. The bird was selective about which, of six holes, it chose for insertion of the tool, choosing the appropriate one with respect to the water source. Days on which attempted or successful tool-use occurred were drier than other days, and days of successful tool-uses were also warmer. Availability of fresh water to the birds did not influence the occurrence of tool-use.     

A study of sugar beet growers' pest control decisions

The results of a survey of sugar beet growers are reported which provide subjective information on farmer perceptions of the hazard from pests and diseases on sugar beet, the control methods available and used, farmers' estimates of the costs and effect of controls, their objectives for pest control, and their attitudes to advice. In addition, objective information from research and field observations on losses and control methods is provided. The basis of pest control decisions and implications from comparisons of subjective and objective perceptions of the various problems and solutions are discussed.     

Preparation of eumelanin-related metabolites 5,6-dihydroxyindole, 5,6-dihydroxyindole-2-carboxylic acid, and their O-methyl derivatives

5,6-Dihydroxyindole (5,6DHI) and 5,6-dihydroxyindole-2-carboxylic acid (5,6DHI2C) are ultimate precursors of the black melanin, eumelanin. These indolic metabolites and their O-methyl derivatives are excreted in urine of melanoma patients at high levels and of healthy persons at low levels. We describe here a simplified procedure for preparing milligram to subgram quantities of 5,6DHI and 5,6DHI2C and their O-methyl derivatives. Dopachrome generated in situ by ferricyanide oxidation of dopa at pH 6.5 underwent spontaneous decarboxylation to give 5,6DHI in 40% isolation yield, while treatment of dopachrome with alkali at pH 13 afforded 5,6DHI2C in 38% isolation yield. Two isomeric O-methyl derivatives of 5,6DHI were prepared by treatment with diazomethane, while those of 5,6DHI2C were prepared by treatment with diazomethane followed by alkaline hydrolysis of the methyl esters. 5,6DHI and 6-hydroxy-5-methoxyindole were also obtained by heating the corresponding carboxylic acids in decalin. 5-Hydroxy-6-methoxyindole and 6-hydroxy-5-methoxyindole-2-carboxylic acid could also be prepared by debenzylation of the commercially available O-benzyl derivatives.     

Clinical adaptation of a high-performance liquid chromatographic method for the assay of pyridoxal 5′-phosphate in human plasma

Vitamin B6, measured as pyridoxal 5′-phosphate (PLP), is a co-enzyme in the transsulfuration pathway of homocysteine metabolism. Since depletion of PLP has been suggested as an independent risk factor for coronary artery disease, PLP is frequently measured to guide patient care. By a change and utilization of an Aquasil C18 column and the addition of an acetonitrile clean-up gradient to the potassium phosphate, with sodium perchlorate and bisulfite buffer between samples we report the modification of a previously described method for analysis of PLP. The result is a more practical, efficient, reliable and robust method for daily clinical use. We also determined and report that it is critical to protect freshly prepared standard PLP samples from light exposure during assay preparation.