Interactions between metals accumulated in the narrow-clawed crayfish Astacus leptodactylus (Eschscholtz, 1823) in Dikilitaş Lake,Turkey

The accumulations of Al, Cd, Cr, Cu, Fe, Ni, Pb and Zn in the exoskeleton, gills, hepatopancreas and abdominal muscles of crayfish Astacus leptodactylus (Eschscholtz, 1823) were determined. The strongest correlation observed was between Cr and Ni in the gills (r?=?0.904); moderate to strong correlations between Al, Cr, Fe, Ni and Cu were also observed in gill tissue. Disregarding the gills, the strongest correlation was found between Cu and Zn in the hepatopancreas (r?=?0.808); the correlation between these two metals might have been a result of metallothionein activity. The accumulation of Pb was found to correlate with that of Cd in the exoskeleton, Cd and Zn in the gills, Zn and Cu in the hepatopancreas and Cu in the abdominal muscle. None of these correlations were present in lakewater and sediment samples, suggesting that the crayfish metabolism may be responsible for the co-accumulation of metal–metal pairs. As all correlations in non-gill tissues are observed between divalent metals, a shared transporter such as divalent metal transporter 1 might be involved in the accumulation of these metals.     

Entwicklung eines Sedimentbiotests mit der ZwergdeckelschneckePotamopyrgus antipodarum (Gastropoda: Prosobranchia)

Currently, only few organismic biotest systems are available for the assessment of effects on reproduction, which consider an exposure toward whole sediments. A well-suited test organism is the parthenogenetic mudsnailPotamopyrgus antipodarum. This ovoviviparous prosobranch snail lives in the upper layers of freshwater and brackish sediments. The number of (unshelled) embryos turned out to be a very sensitive parameter for the indication of sediment components affecting reproduction. Additionally, this endpoint allows to signal possible estrogenic sediment compounds. With this 28-day bioassay, laboratory tests on the effects of various chemicals onP. antipodarum were performed, e.g. triphenyltin and bisphenol A, in relevant environmental concentration ranges. Furthermore, the suitability of our test system for the investigation of complex and multiple level ranged contaminations was examined by means of various natural sediments from the Neiße and Odra rivers.     

Genetic and evolutionary constraints for the symbiosis between animals and methanogenic bacteria

It has been assumed that the feeding habits of animals predispose the composition of the microbial biota living in their intestinal tracts. Here we show that in arthropods and vertebrates the presence of methanogenic bacteria requires a quality of the host that is under phylogenetic rather than dietary constraint: competence for intestinal methanogenic bacteria is a primitive-shared character among reptiles, birds, and mammals, and a shared-derived trait of millipedes, termites, cockroaches and scarab beetles. The presence of methanogenic bacteria seems to be a prerequisite for the evolution of anatomic specializations of the intestinal tract such as hindguts, caeca or rumina, and it is likely that it also has consequences for the reproductive strategies of the animals.Methanogenic animals contribute to atmospheric methane by their breath and faeces. Because the status as either methane-producer or non-producer is shared by most species belonging to a higher taxonomic unit, it is possible to calculate methane emissions that are characteristic for whole taxa. In combination with ecological field data on the biomass it is possible to arive at estimates concerning the global contributions by animals.The demonstration of a genetic basis for the symbiosis between methanogens and animals will allow new approaches for the reduction of methane emission by domestic animals.