Sister chromatid exchanges in rotogravure printing plant workers.

OBJECTIVE: The individual burden of inhaled ambient-air toluene and its link to genotoxic phenomena in exposed printing workers. METHOD: The influence of toluene on sister chromatid exchange (SCE) was investigated by monitoring of the individual toluene burden of 42 exposed printing workers. Therefore, the urinary hippuric acid (HA) excretion was measured directly after the work shift. The results were compared with those recorded for a control group consisting of 45 blood donors. SCE frequencies were determined from peripheral lymphocytes for both groups. RESULTS: The median HA excretion of the exposed and nonexposed groups amounted to 1.94 and 0.45 g/g creatinine, respectively. For both groups, different SCE rates were detected: 10.13 and 6.84 counts/lymphocyte for exposed and nonexposed persons, respectively. The independence of the measured values proved to be significant at a high confidence level (P = 0.000) for both groups. The influences of smoking and alcohol consumption on SCE as well as on HA values could be clearly separated from those induced by toluene. CONCLUSIONS: The results of our study indicate a strong relationship between the individual toluene burden and the genotoxic risk of the exposed persons. Since toluene was used for dilution of the letter-press ink, the influence of ink mist on the genotoxic effects could not be completely excluded.

[Do soluble organic nitrogen compounds cause unusual algal blooms in seawater?]. / Verursachen gelöste organische Stickstoffverbindungen im Meerwasser aussergewöhnliche Algenblüten?

Up to now the nature and importance of the macromolecular forms of organic nitrogen in the marine environment is poorly understood. There is no doubt on the capacity of phytoplankton to utilize low molecule weight dissolved organic nitrogen compounds competitively with bacteria. In marine ecosystems the members of the plankton community show a complex close coupling with biological substances. In spite of trace concentrations the high dynamics in uptake and release processes cause strong fluxes of these compounds. In the case of inorganic nutrient deprivation or reduced photosynthesis under light deficiency algal utilization of organic nitrogen becomes noteworthy. Even under high nitrate supply an algal development occurred which was mainly triggered by amino acid uptake as was demonstrated during field experiments in the German Bight. The consumption of amino acids is controlled by several uptake systems, which are specified for transportation of different groups of amino acids through the cell wall. Since the uptake systems can also differ among species, the amino acid composition of the environment could preferentially enhance the growth of some selected species in comparison with other components of natural phytoplankton assembles. In the scope of increasing water pollution and the resulting shift in nutrient distribution one may expect the development of phytoplankton species, which had not been supported so far. In estuaries and costal zones photosynthesis is effected by light absorbance from particulate material. This phenomenon additionally will sustain algae, which are able to compensate a photosynthesis deficit by heterotrophic uptake. Though interrelationships are not clear up to now, it becomes evident that increasing impact of dissolved organic substances cause strong changes in species composition of marine ecosystems.

An automated fluorescence assay for subnanogram quantities of protein in the presence of interfering material.

An automated assay for measuring nanogram and subnanogram quantities of protein in microliter samples was developed with the fluorometric reagent omicron-phthaldialdehyde/mercaptoethanol. Low molecular weight interfering substances were separated within the analysis by gel filtration. The technique allowed measurement of biological fluids without any sample pretreatment. The method presented proved to be linear within the range 1.2 ng to 1.4 microgram with a standard deviation of +/- 4.2%. The minimum detectable protein concentration was 1 microgram/liter. Special care was taken to prevent any determination errors caused by losses of protein during adsorption to surfaces. The simple analytical apparatus constructed can be used for field studies and ran several weeks when continuously used for seawater analysis aboard ship.

[Primary oxidation mechanisms in degradation of aliphatic hydrocarbons by bacterial enzyme systems (author's transl)]. / Primäre Oxydationsmechanismen beim Abbau aliphatischer Kohlenwasserstoffe durch bakterielle Enzymsysteme

The bacterial dissimilation of aliphatic hydrocarbons is catalysed by a monooxygenase mechanism with incorporation of molecular oxygen. Numerous publications have shown the cytochrome P 450-dependent hydroxylation of hydrocarbons, but there is considerably less information of hemo-protein-independent hydroxylations by alkanhydroxylases. In a marine Pseudomonad we found a system sensitive to cyanide: The oxygenase could be divided into three protein fractions. A cytochrome P 450 type spectrum was not detected. The NADH-dependent hydroxylation of n-decane can be activated by Mg2+ and Fe2+ ions. A noncompetitive product inhibition occurs which deserves special attention. An alcohol-dehydrogenase is closely associated with the oxygenase system by a kind of multienzyme-complex. Studies on kinetics and substrate specificity of this enzyme show an inhibition by excess substrate increasing with the chain length of the alcohols. The whole complex (alkanhydroxylase, alcoholdehydrogenase and aldehyddehydrogenase) is induceable by bacterial growth on alkanes, primary alcohols and fatty acids as sole carbon source.