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Einzellige, mikroskopisch kleine, pflanzliche Organismen erweisen sich als ideale Bioindikatoren, um den Verunreinigungsgrad von Gewässern zu bestimmen: Diese Kieselalgen finden sich in den verschiedensten Gewässern - von reinsten Quellbächen bis zu Abwasserkanälen; die Artenzusammensetzung der Kieselalgen ist je nach Gewässerzustand sehr unterschiedlich. Auf jede Veränderung der Qualität folgt schnell ein charakteristischer Artenaustausch. Seit 1972 untersucht der Biologe Horst Lange-Bertalot mit dieser Methode die Wasserqualität des Mains, die sich wesentlich verbessert hat. Über Ergebnisse berichtet er gemeinsam mit Christine Schmidt.

Differential derepression of the genome of potato tuber cells causes the onset of a vigorous metabolic activity, which is initiated by rapid synthesis of different RNA species, various proteins and phospholipids. Consequently enhanced respiration and the build up of cell compartments such as ribosomes and mitochondria as well as the performance of cell divisions and suberization of new-formed cell walls occur. Although there is an activation of metabolism in general with a concomitant rise in concentration of most glycolytic metabolites — as was proved for fructose-1.6-diphosphate, dihydroxyacetone, glyceraldehade-3-phosphate, phosphoenolepyruvate and pyruvate — the activities of the corresponding enzymes do not reflect these uniform metabolic changes. Aldolase and in a pronounced manner enolase and glutamate — pyruvate — transaminase lower their activities suddenly after derepression. The activity of triosephosphateisomerase remains constant. In contrast phosphoglyceromutase, pyruvate kinase and to a lower extent malic enzyme enhance their action during the same time. Without doubt, differential lowering and enhancing the activity of glycolytic chain constituents at the same time is an important regulatory mechanism of the cell. The activation represents de novo synthesis of the protein concerned whereas the inactivation depends largely on protein synthesis. This is clearly shown by experiments with inhibitors of protein synthesis. It is proposed that this differential synthesis and degradation represent a “long-time-regulation” of enzymatic activity of the cell in contrast to the known “short-time-regulation” by feedback or competition.