A Novel Particle Contact Assay with the Yeast Saccharomyces cerevisiae (8 pp)

Goal, Scope and Background   Numerous xenobiotics released into surface waters are transferred to suspended particulate matter and finally attached to sediments. Aquatic organisms may be exposed to them by direct particle feeding, by physical contact with contaminated surfaces as an exposure route, and by the uptake of dissolved contaminants after equilibration via the free water phase. In order to assess potential sediment toxicity, each of these exposure routes has to be addressed. This paper presents a newly developed particle contact assay that uses the fermentation performance of a specific Saccharomyces cerevisiae strain for the assessment of toxic effects in sediments. The test procedure is based on the characteristic feature of growing yeast cells to attach to sediment particles, which are also relevant for the accumulation of contaminants. The physical contact with lipophilic contaminants mirrors an exposition pathway for the direct uptake into the cells. In order to quantitatively characterize the toxic effects of particle attached pollutants on the fermentation performance, unpolluted native reference sediment was spiked with representatives for widely distributed anthropogenic contaminants. Methods   Saccharomyces cerevisiae was established as sensitive eukaryotic microorganism for the ecotoxicological assessment of particle attached anthropogenic contaminants in freshwater sediments. For this purpose, yeast cells were cultivated in sediment samples and the resulting fermentation performance was continuously measured. Sediments artifically spiked with HCB, PCB, g-HCH, DDT, and benzo(a)pyrene and solutions of each contaminant were comparatively investigated by means of their adverse effects on yeast fermentation performance. Additionally, four native river sediments characterized by increasing levels of pollution were assessed by the yeast particle contact assay, and simultaneously by standard aquatic tests with algae, daphniae, and luminescent bacteria using pore water and elutriates. Results of the bioassays were related to specific sediment contamination with respect to metals and organic priority pollutants. Results and Discussion   In sediments spiked with PCB and benzo(a)pyrene fermentation, performance was affected extensively below concentrations inhibiting fermentation in contaminant solutions. This suggests a high efficiency of the exposure route by physical contact. The fermentation performance was only slightly affected by single lipophilic pollutants, whereas mixtures of individually spiked sediments caused critically reduced fermentation performance suggesting additive synergistic effects. Native river sediments modestly to critically polluted by hazardous organic compounds lead to a slightly to dangerously reduced fermentation performance in the yeast contact assay. These inhibitory effects were much less pronounced in the standard bioassays conducted with algae, daphniae and luminescent bacteria, applying pore waters and elutriates as sample matrices. Using pore water, inhibition was measured only in the most polluted sediment, elutriates lead to a slight inhibition of the algal growth in the undiluted sample only. These results indicate an improved sensitivity of the yeast particle contact assay compared to the standard assays, due to uptake and physical cell contact as additional routes of exposure. Conclusion   The yeast particle contact assay is a valuable tool for the assessment of ecotoxicological potential in freshwater sediments. Since the assay addresses physical contact as an exposure route, it indicates bioavailability of lipophilic compounds in sediments. Outlook   The sensitive indication of bioavailable contaminants associated to sediment particles by the newly developed yeast particle contact assay recommends it as a complementary microbial bioassay in a test battery for assessing major pathways of contaminants in whole sediments.     

Libri Novi

Ohne Zusammenfassung     

Numbers of gastrointestinal helminth eggs of Wyoming cattle in two surveys: 1957 to 1961 and 1973 to 1977

From 1973 to 1977, a survey of internal parasites in Wyoming cattle was conducted via fecal analyses of 1,490 beef cattle. Sugar flotation techniques were used, with a factor of 2 times the actual egg counts. The prevalence of internal parasites of beef cattle in this survey was compared with that in a previous survey conducted on Wyoming beef cattle from 1957 to 1961. Results of analyses indicated no true change in mean eggs per gram of feces (epg) as follows: calves, 14 epg in 1961 and 20 epg in 1977; yearlings, 29 epg in 1961 and 19 epg in 1977; and adults, 22 epg in 1961 and 21 epg in 1977.     

Der Nitratgehalt von Gemüsen in Abhängigkeit von Pflanzenart und einigen Umweltfaktoren

Zusammenfassung Zur Prüfung der für die menschliche Ernährung wichtigen Frage des in gesundheitlicher Beziehung nicht ganz unbedenklichen Nitratgehaltes von Gemüse wurden an der Bundesanstalt für Qualitätsforschung in Geisenheim/Rheingau umfangreiche Untersuchungen durchgeführt. Die Nitratbestimmungen ergaben verschieden hohe Gehalte je nach botanisch-systematischer Zugehörigkeit der einzelnen Gemüsearten. Typische Nitratspeicherer unter den häufiger genossenen Gemüsepflanzen sind der Spinat, die Rote Rübe und die Kohlarten. Die einzelnen Pflanzenorgane führten Nitrat in unter-schiedlicher Höhe.Einen entscheidenden Einfluß auf die Menge des gespeicherten Nitrats hat die Art und Höhe der Stickstoffdüngung. Verabfolgung von Jauche führte, ebenso wie Salpeterdüngung zu höheren Nitratgehalten als eine Düngung mit ammoniumhaltigen Mineraldüngern. Je höher die Stickstoffgaben waren, desto höher stieg im allgemeinen auch der Nitratgehalt des untersuchten Pflanzenmaterials. Auch die Lichtintensität erwies sich als mitbestimmender Faktor auf die Höhe des Nitratgehaltes, wie Klimakammerversuche bei abgestufter künstlicher Beleuchtung mit Spinat zeigten (hohe Licht-Intensität = niedriger, geringe L.I. = hoher Nitratgehalt). Standortversuche, ebenfalls mit Spinat, an klimatisch differenten Orten ergaben, daß die Nitratgehalte bei sonnigen warmen Witterungsbedingungen (Geisenheim/Rhein) niedrig, bei kühlen niederschlagsreichen, also lichtärmeren (Kiel), hoch waren.Mit diesem im Nitratgehalt unterschiedlichen Spinat wurden (nach Dosenkonservierung) Ernährungsversuche mit Säuglingen in der Universitätskinderklinik Kiel (Direktor: Prof. Dr. med.W. Catel) durch Dr. med.W. Kübler durchgeführt, die in seiner nachfolgenden Arbeit beschrieben werden (16).

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Summary Experiments have been carried out at the Bundesanstalt für Qualitätsforschung pflanzlicher Erzeugnisse in Geisenheim/Rhine on vegetables to determine the amount of nitrates, to be looked upon as somewhat detrimental for human health. Determinations of nitrate showed contents, different according to systematic relationships of vegetables. Those vegetables, as spinach, beet roots, cabbages and kale are typical plants storing nitrates. Plant organs differ in the amount of nitrates stored.Nitrogen-fertilizers influence the amount of accumulated nitrates depending on N-fertilizers and amount of Nitrogen. Liquid manure and nitrate supply gave rise to higher contents of nitrate as ammoniac fertilizers.The higher the amount of nitrogen, the higher raised the contents of nitrate in plant material investigated. Different light intensities, mesured in climate chambers, have been proved to be a determining factor regarding amount of nitrates in plants. High light intensity show low contents of nitrate, low one a high amount of NO₃. Environmental experiments with spinach on places, different in climatic conditions, resulted in contents of nitrates which were low when sunny warm weather conditions (Geisenheim/Rh.) prevailed and vice versa (Kiel).After canning, this spinach differing in nitrate-contents has been administered babies in nutritional trials by Dr. med.W. Kübler in the Univ. Klinik Kiel (Director Prof. Dr. med.W. Catel). The results are given in the following paper by Dr.Kübler (16).

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Mit 5 Tabellen und 2 Fig.

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Gemeinschaftsversuche der BAQ mit der Universitätskinderklinik Kiel (Direktor: Prof. Dr. med.W. Catel) vgl. auch S. 297.