On the function of warning coloration: a black and yellow pattern inhibits prey-attack by naive domestic chicks

Summary Young chicks were offered a choice of warningly coloured black and yellow and non-warningly coloured green (or olive) prey. Unfed chicks were given palatable painted mealworms on their first day. They directed their first peck at both colour types at the same probability; however, they ate the warningly coloured ones at a much lower rate. This is due to an inhibition of attack which becomes effective after pecking. Chicks which were a few days old showed the same behaviour. Since the control prey was in this case painted with an olive mixture containing the same colours as the warningly coloured mealworms, it can be concluded that the inhibition is caused by the black and yellow coloration. With accumulating positive experience of the chicks, the inhibition decreased. For permanent avoidance it must therefore be supplemented by unpleasant experience. Accordingly, chicks handled the unpalatable black and yellow ringed caterpillars of Tyria jacobaeae only a few times and always for a short period when offered repeatedly. The inhibition caused by the black and yellow pattern is attributed to a genetically fixed predisposition to avoid warningly coloured black and yellow prey which is the result of evolutionary adaptation.     

Minerals and the Common Fund for Commodities

This paper reviews the role of minerals in the Integrated Programme for Commodities and the objectives and problems of the Second Account of the Common Fund for Commodities (CFC). It focuses on the least developed countries in Africa, providing specific suggestions for R&D to improve mineral exploration techniques in rain forest and savanna regions; to reduce mine exploration costs; to design equipment suitable for mining narrow veins; to improve concentrating methods for certain ores and to optimize byproduct recovery; to reduce environmental impacts; and to use the waste products of mining. It also discusses demand oriented CFC projects and their policy implications.     

Dynamics of skeleton formation in the Lake Baikal sponge Lubomirskia baicalensis. Part II. Molecular biological studies

In a preceding study it has been reported that the freshwater sponge Lubomirskia baicalensis, living in Lake Baikal (East Siberia), is composed of spicules forming a characteristic pattern which follows radiate accretive growth. Here we report that the spicules are synthesized by the enzyme silicatein, a protein which is related to cathepsin L. The cDNAs for silicatein and the related cathepsin L were isolated and used as probes to show that the mRNA levels of silicatein in the bases of the spicule skeleton of the animals are low, while the mRNA level of cathepsin L in this region exceeds that of the growing zone. This is the first comprehensive study on the importance of the axial filament/silicatein as an essential structural and functional component determining the growth and stability of demosponge spicules.Note: Sequences from Lubomirskia baicalensis have been deposited in the EMBL/GenBank; cDNAs for the putative silicatein (LBSILICA) are deposited under the accession no. AJ786771 and for cathepsin L (LBCATL) under the accession no. AJ786770.     

Geochemistry and bioavailability of metals in sediments from northern San Francisco Bay

In this study, metals (Be, Cr, Mn, Fe, Ni, Cu, Zn, Ag, Cd, Pb and Hg) in the fine-grained fraction (<63 microm) from 12 sites at different locations in northern San Francisco Bay over a year period from March 2000 to March 2001 were analyzed after acid extraction. The results showed that metal concentrations in the sediments varied from site to site, whereas some of them were found elevated with respect to the sediment of Tomales Bay, CA, which has little contamination history, indicating an enrichment of the metals in the sediment samples analyzed. Sediment toxicity and bioaccumulation evaluation by a clam species, Macoma nasuta, exposed to the sediment samples collected from the six sampling sites was carried out. The results showed that the sediment samples tested significantly reduced clam survival. Toxicity of the sediments to the clam was, in part, related to elevated metal concentrations in the sediments. In order to examine geochemistry of the metals and to understand potential correlations between metal concentrations and geochemical matrix elements of the sediments, bioavailability and toxicity of the metals, detailed analysis of metal concentrations associated with total organic carbon and the Fe-oxy-hydroxides in the sediment samples was performed. The analysis showed that sediment geochemistry appeared to influence metal bioavailability and may have important impacts on the toxicity of these metals to the clam.