Jürgen Berndt

l-Phenylalanine ammonia-lyase in suspension culture cells of spruce (Picea abies)

The activity of l-phenylalanine ammonia-lyase (PAL) (EC 4.3.1.5) was determined in seedlings, callus cells, cell suspension cultures and in young needles of spruce (Picea abies) (L.) (Karst). PAL activity increased up to 10 fold in response to transferring suspension cultured cells into new cultivation medium. PAL was also induced about 10 fold when callus cells were transferrd into liquid medium. The increase was transient and it required the presence of a carbohydrate.In cell suspension cultures, grown in the dark (white cells), but not in light-grown cultures (green cells), PAL activity was induced up to 30 fold by UV-light.With a cell wall preparation of Rhizosphaera kalkhoffii, a forest pathogenic fungus, used as elicitor, the activity of PAL could be induced more than 10 fold. The degree of induction depended on the elicitor concentration. Induction was prevented by cycloheximide but not by actinomycin D.

Ascorbic acid and chlorophyll content in cell cultures of spruce (Picea abies): changes by cell culture conditions and air pollutants.

Abstract Conifers contain ascorbic acid which is probably a protective against oxidative attacks. In yellow needles of damaged conifers the ascorbic acid content is increased, this suggests an induction by air pollutants and/or photooxidants of a protection mechanism in trees. To study this mechanism in more detail, a green cell suspension culture of spruce (Picea abies) has been established. These cells contain chlorophyll and have a photosynthetic capacity, but they need carbohydrates (sucrose) for growth and are thus photoheterotrophic. Their ascorbic acid content and its regulation depends on carbohydrates, the cells resemble healthy green needles in this respect; they appear to be qualified for studies on the induction of a defense mechanism. Treatment of these cells with SO2 (20 ppm, 4 days) ozone (1 ppm, 14 days) and vaporous H2O2 revealed a decrease of the ascorbic acid content and (to a lesser extent) also of chlorophyll. It is concluded that (photo-)oxidants obviously do not play such a dominant role in bleaching of needles as it is assumed. The increased ascorbic acid content found in needles of damaged conifers is probably not an induced protection mechanism against oxidants.

Modes of action and combination effects of polychlorinated biphenyls and γ-hexachlorocyclohexane on the regulation of rat liver 3-hydroxy-3-methylglutaryl coenzyme A reductase

The effect of polychlorinated biphenyls, gamma-hexachlorocyclohexane and the effect of a combination of these substances on the regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase were investigated. As known from previous investigations polychlorinated biphenyls interfere with the regulation of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in rat liver via enzyme-lipid interaction and at the pretranslational level. In contrast to polychlorinated biphenyls, gamma-hexachlorocyclohexane did not alter the lipid status of the microsomal membrane. Thus the location of the 3-hydroxy-3-methylglutaryl coenzyme A reductase, and consequently the catalytic activity of the enzyme was not changed. As with polychlorinated biphenyls, gamma-hexachlorocyclohexane interacted with enzyme regulation at the pretranslational level. Northern dot hybridization experiments showed a decrease in the level of m-RNA coding for 3-hydroxy-3-methylglutaryl coenzyme A reductase. The effect of combination of gamma-hexachlorocyclohexane and polychlorinated biphenyls was not additive. The gamma-hexachlorocyclohexane effect appeared to play a more important role than that of the polychlorinated biphenyls. The results indicate that the combination effects are as important as the effects of the single compounds when making risk assessments for xenobiotics.

Zur Störung des Kohlenhydratstoffwechsels Nach Bestrahlung: Einfluss Einer Ganzkörperbestrahlung auf den Gehalt an Intermediärprodukten der Glycolyse in der Mäuseleber

SummaryIn der Mauseleber wurde nach einer Ganzkorperbestrahlung mit 690 R der Gehalt an Glycogen, Glukose, Fructose-1, 6-Diphosphat, Dihydroxyacetonphosphat, Phosphoenolpyruvat, Pyruvat und Laktat gleichzeitig bestimmt.Bei gefutterten Tieren treten nach der Bestrahlung starke Schwankungen dieser Metabolite auf, die z.T. auf die strahlenbedingte Appetitlosigkeit zuruckzufuhren sind. Bei 24 Stunden hungernden Mausen tritt 18 Standen p.r. sowie vom 5.–10. Tag p.r. ein starker Anstieg des Leberglycogens auf, Fructose-1, 6-Diphosphat und Dihydroxyacetonphosphat sind 12 Stunden p.r. bis 10 Tage p.r. erhoht, wahrend Pyruvat, Laktat und Phosphoenolpyruvat nur wenig verandert sind. Zur Zeit des hochsten Glycogengehaltes ist von keinem der Metabolite die Konzentration besonders stark erhoht oder erniedrigt.SummaryIn der Mauseleber wurde nach einer Ganzkorperbestrahlung mit 690 R der Gehalt an Glycogen, Glukose, Fructose-1, 6-Diphosphat, Dihydroxyacetonphosphat, Phosphoenolpyruvat, Pyruvat und Laktat gleichzeitig bestimmt.Bei gefutterten Tieren treten nach der Bestrahlung starke Schwankungen dieser Metabolite auf, die z.T. auf die strahlenbedingte Appetitlosigkeit zuruckzufuhren sind. Bei 24 Stunden hungernden Mausen tritt 18 Standen p.r. sowie vom 5.–10. Tag p.r. ein starker Anstieg des Leberglycogens auf, Fructose-1, 6-Diphosphat und Dihydroxyacetonphosphat sind 12 Stunden p.r. bis 10 Tage p.r. erhoht, wahrend Pyruvat, Laktat und Phosphoenolpyruvat nur wenig verandert sind. Zur Zeit des hochsten Glycogengehaltes ist von keinem der Metabolite die Konzentration besonders stark erhoht oder erniedrigt.

Die Aktivität der Phosphofruktokinase und der Fruktose-1, 6-diphosphatase im Lebergewebe der Maus Nach Ganzkörperbestrahlung

SummaryIn der Mauseleber wurde nach einer Ganzkorperbestrahlung mit 690 R die Aktivitat der Phosphofruktokinase (PFK) und der Fruktose-1, 6-Diphosphatase (FDPase) uber einen Zeitraum von 17 Tagen nach der Bestrahlung gemessen. Die Aktivitat der PFK ist bei gefutterten Mausen vom 8. Tag p.r. bis zum 14. Tag p.r. erhoht, bei 24 h hungernden Mausen erfolgt ein gleichmasiger Anstieg der Aktivitat bereits vom 4. Tag p.r. an und erreicht am 12. Tag p.r. Werte, die um 150% uber der Aktivitat unbestrahlter Hungermause liegen. Derselbe Aktivitatsverlauf tritt auch nach Bestrahlung mit 810 R auf. Die Ergebnisse deuten auf eine erhohte Enzymsynthese nach der Bestrahlung hin.Dagegen ist die Aktivitat der FDPase bei gefutterten Mausen nur am 11. Tag p.r., bei 24 h hungernden Mausen vom 11.–17. Tag p.r. geringfugig erhoht. Der Aktivitatsverlauf dieser beiden Enzyme nach der Bestrahlung stutzt die Annahme, das nach einer Ganzkorperbestrahlung die Glycolyse nicht erniedrigt ist.

Inhibitory effect of cyclic adenosine-3′,5′-monophosphate on the induction of aryl hydrocarbon hydroxylase in the liver of female rats

Abstract The effect of dibutyryl cyclic adenosine-3′,5′-monophosphate (DBcAMP) on the activity of aryl hydrocarbon hydroxylase (AHH) was studied under in vivo conditions in the liver of female rats. To maintain an elevated level of DBcAMP for a longer period of time, the nucleotide was given by a continuous infusion up to 26 hr without disturbing the animals. Under these conditions the basal activity of AHH was not significantly changed, indicating that cAMP is not an inducer or inhibitor of AHH. On the other hand, 3-methylcholanthrene-and phenobarbital-mediated induction of AHH was reduced in the presence of DBcAMP by about 50 and 35%, respectively. A reduced induction rate of AHH has also been seen after the application of the herbicide atrazine, which increases the endogenous level of cAMP. The results suggest that cAMP is not involved in the induction of AHH caused by xenobiotics. The inhibitory effect of DBcAMP on the induction of AHH may be due to an inhibition of enzyme synthesis which, in turn, may be the consequence of a direct effect of DBcAMP or an indirect effect caused by changes in the level of steroid hormones.