Biomonitoring of arylamines: haemoglobin adducts of aniline derivatives

Aromatic amines are important intermediates in industrial manufacturing. They are used in a large number of products, such as pesticides, dyes, plastics and pharmaceuticals. The parent arylamines can be metabolically released from these arylamine-based compounds and form DNA and protein adducts after N-oxidation to N-hydroxy arylamines. Aromatic amine derivatives, including the industrial intermediates acetoacetanilide, acetoacet-m-xylidide and N-ethylaniline, were examined for their ability to form Hb adducts in rats as potential biomarkers of exposure. The haemoglobin binding indices (HBI=binding [mmol mol^-1 Hb]/dose [mmol kg^-1 body weight]) of the arylamines were determined 24 h after oral administration to female Wistar rats. The precipitated haemoglobin was dissolved in 0.1 M sodium hydroxide in the presence of internal standards. After hexane extraction the released arylamines were analysed by gas chromatography-mass spectrometry (GC-MS). For aniline released from acetoacetanilide an HBI of 15 and for 2,4-dimethylaniline released from acetoacet-m-xylidide an HBI of 0.129 were determined. The HBIof aniline released from N-ethylaniline was 45.     

Transfer of reducing equivalents into mitochondria by the interconversions of proline and Δ1-pyrroline-5-carboxylate

Direct evidence is presented for a proline cycle using a cell-free experimental system which sequentially transfers ³H from [1-³H]glucose to NADP⁺ to Δ¹-pyrroline-5-carboxylate and yields [³H]proline. The formation of [³H]proline depends on the presence of NADP, Δ¹-pyrroline-5-carboxylate, and the enzymes glucose-6-phosphate dehydrogenase and Δ¹-pyrroline-5-carboxylate reductase. The production of [³H]proline from unlabeled proline in the presence of mitochondria provides direct evidence for one complete turn of a proline cycle which transfers reducing equivalents produced by glucose oxidation in the pentose pathway into mitochondria. In this cycle, proline is oxidized to Δ¹-pyrroline-5-carboxylate by mitochondrial proline oxidase. Δ¹-pyrroline-5-carboxylate is released from mitochondria and is recycled back to proline by Δ¹-pyrroline-5-carboxylate reductase with concomitant oxidation of NADPH. At the maximal rate observed, 60% of Δ¹-pyrroline-5-carboxylate produced is recycled back to proline. This cycle provides a mechanism for transferring reducing equivalents from NADPH into mitochondria and is linked to glucose oxidation in the pentose pathway by NADPH turnover.     

Vererbungsstudien

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Hermaphroditismus im Tierreich vom genetischen Standpunkt

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The membrane dialysis bioreactor with integrated radial-flow fixed bed —a new approach for continuous cultivation of animal cells

A hybridoma cell was cultivated continuously in a membrane dialysis bioreactor with an integrated radial-flow fixed bed consisting of porous Siran^® carriers over a period of 6 weeks. Antibodies accumulated to an average of 100 mg l^?1, approx. 10 times more than in fixed bed cultures without dialysis membrane. Serum costs could be reduced about 85% due to an appropriate feeding strategy. Siran^® carriers with 3–5 mm diameter showed an advantage compared to those with 1–2 mm diameter. For the 3–5 mm carrier the specific glucose uptake rate and the MAb production rate were constant, if the velocity was between 0.09 mm s^?1 and 0.75 mm s^?1. At higher velocities cells are washed out of the bed. Furthermore antibody consistency and cell stability were verified in long-term cultivations over a period of 96 days. From an estimation of the antibody concentration reachable with the reactor concept under optimal conditions a concentration 45 times higher compared to axial-flow fixed bed reactors and 11 times higher compared to stirred tank reactors can be expected.     

Experiences with reducing point sources of phosphorus to lakes

Experiences over the last 25 years have demonstrated that eutrophication can be reversed, and that phosphorus is most often the nutrient through which control should be exerted.The reduction of the external load of phosphorus to a eutrophic lake is a necessary condition for lake restoration, but may not in itself be sufficient. Three main response patterns to a reduction in external load are identified. These include reduction in lake phosphorus that leads to sufficient reduction in chlorophyll to change the trophic category, to make the lakes less eutrophic or have small or no effect. The factors that determine the actual response are discussed.It is clear that interventions to restore eutrophic lakes have not always given the results expected. Limnological studies are necessary for well-grounded predictions.     

Survival ofPseudomonas syringae pv.lachrymans with cucumber roots

Summary Survival ofPseudomonas syringae pv.lachrymans with seedling cucumber roots, root washings, rhizosphere soil, and nonrhizosphere soil was determined 7–8 days after the soil surface was watered with a cell suspension of the bacterium. Plants were in pots in the green-house and soil was not sterilized. Survival was best with roots and root washings, next best in rhizosphere soil, and poor in nonrhizosphere soil.     

Coprophagy in larval Culiseta bergrothi (Diptera: Culicidae)

Two experimental groups of Culiseta bergrothi Edw. larvae were kept under laboratory conditions, but in water from the breeding locality. The ‘donors’ were fed on a suspension of charcoal powder and baker's yeast; the ‘receivers’ had access to the faecal pellets of the donors. After 1.5 hours the gut of almost all receivers was more or less filled with charcoal particles. The possible consequences of the added yeast suspension to food choice and feeding behaviour are discussed.