Wirkungsuntersuchungen beim Brassen
Quack, Markus; Klein, Roland
Trier: Universität Trier, Fachbereich VI – Biogeographie, 2003. - 77
Investigations of effects on Bream - Vitellogenine as example for selection of suitable storable target compartments
Up to now, samples of the German Environmental Specimen Bank (ESB) are analysed on concentrations of chemical substances only. Therefore, statements about exposition and bioavailability are not possible, and questions on cause and effect or on the relevance of availability for organisms cannot be answered completely. For this reason we established methods for environmental effect monitoring on the basis of ESB samples, from the selection of suitable organic compartments, the description of methods, to an examplary analysis.
Because of the complexity of immunological, hormonal and genetic systems and the poor knowledge about suitable marker systems, retrospective analyses are here of special interest. Regarding the continous specification of methods, the delivery of high-quality samples stored under stable conditions is an important aim of the ESB.
In this context, we exemplarily tested methods for the sampling and storing of specific compartments of bream (Abramis brama). Blood plasma, the most important medium of transport, and spleen as a representative of body tissue were chosen. Both compartments were sampled during the ESB routine samplings in the Rivers Saar, Rhine, Elbe, Mulde, Saale and Danube in 2002.
For blood plasma sampling, a variety of methods for fish anaesthetisation, methods for taking blood samples, different additives to blood plasma, and methods of further sample preparation were tested. According to the results of these tests the samples were analysed for vitellogenin (vtg) by means of an ELISA-assay. The results of the vtg assay showed that only at 3 of 16 sampling sites estrogenic effects could be detected. In general, no adverse endocrine effects could be observed in the individuals studied. Nevertheless, because of the simple and fast sampling method and because of the high information level (e.g. for immunological effects), we suggest that blood plasma should be included in the concept of ESB for retrospective effect assessment of animals.
For body tissue or organs, suitable methods for sampling and sample preparation could be developed. The methods were evolved for spleen but can also be applied to any other organ without methodological changes necessary.
To obtain additional information on estrogenic effects, male gonads were analysed for pathological changes. Structural or pathological changes (e.g. occurrence of an ovotestis) can be discussed as indicators for endocrine disruptors, but only 1 of 145 individuals exhibited an ovotestis. Since effects of endocrine disruptors may be superposed by other pathological effects, these have also been analysed systematically. The frequent occurence of fibrocytes and necrotic cells at some sampling sites are hints on pollution. It can be assumed that these findings indicate reduced reproductive abilities of the animals studied.
In summary, the results of the vtg assay as well as the histological examinations confirm that there is no evidence for endocrine effects on the level of population. However, it is suggested that histological analyses should be repeated in specific intervals. Collecting, fixing and storing samples of male gonads could be easily included in the ESB routine. The very informative histo-pathological analyses could be carried out even retrospectively.