Doris Schäfer

Glucose regulates the promoter activity of aldolase A and pyruvate kinase M2 via dephosphorylation of Sp1

Proliferating cells and tumour cells maintain a high glycolytic rate even under aerobic conditions. FTO2B cells, a rat hepatoma cell line, show high activities of glycolytic enzymes. Within a culture period of 48 h the cell number increases 5‐fold. Replacement of glucose by pyruvate in the culture medium lowers glycolytic enzyme activity and prevents proliferation. Transfection assays revealed that glucose deprivation dramatically decreases the transcriptional activities of the Sp1‐dependent aldolase and pyruvate kinase promoters leading to reduced reporter gene expression. Sp1 binding activity is also inhibited by ocadaic acid, an inhibitor of protein phosphatase 1. Western blot analyses with nuclear extracts from FTO2B cells cultured in the presence or absence of glucose revealed differences in the phosphorylation state of Sp1. From these results we conclude that glucose increases the amount of the dephosphorylated form of Sp1 which has a higher DNA binding activity. As a consequence gene expression of the glycolytic enzymes is increased which is a prerequisite for cell proliferation.

Differences in DNA-binding efficiency of Sp1 to aldolase and pyruvate kinase promoter correlate with altered redox states in resting and proliferating rat thymocytes

Thymocytes induce their glycolytic enzymes as they undergo transition from the resting to the proliferating state. Corresponding increases in mRNA levels point to a transcriptional regulation. Electrophoretic mobility shift assays revealed that the DNA‐binding efficiency of Sp1 is increased when nuclear extracts from proliferating compared to resting rat thymocytes were used. Here we demonstrate that hydrogen peroxide, added to nuclear extract from proliferating cells, decreases the Spl DNA‐binding activity, whereas in nuclear extracts from resting cells dithioerythritol fully restores DNA‐binding efficiency. Moreover we show that in contrast to resting thymocytes, production of reactive peroxide anions upon priming with phorbol 12‐myristate 13‐acetate is nearly abolished in the proliferating cells. From these results we propose that reactive oxygen intermediates affect the interaction of the Sp1 transcription factor with its consensus sequence and subsequently regulate glycolytic gene expression.

Mellein, a Trail Pheromone Component of the Ant Lasius fuliginosus

Abstract3,4-Dihydro-8-hydroxy-3-methylisocoumarin (mellein) and 2,3-dihydro-3,5-dihydroxy-6-methyl-4H-pyran-4-one are among the volatile constituents identified from the hindgut of the formicine ant Lasius (Dendrolasius) fuliginosus Mellein induces trail-following behavior in worker ants of this species and evokes electrophysiological responses from their antennae. The trail-following activity released by (R)-(−)-mellein is significantly higher than that elicited by its (S)-(+) antipode, or the racemic mixture. The above-mentioned pyranone is found also in the honeydew of aphids, the customary diet of this ant species. The pyranone also evokes some trail-following behavior, but its activity is far less pronounced than that of mellein. Apparently, extra pheromone components are present in the hindgut, since the activity of these two constituents, either individually or as a mixture, does not completely account for the total activity released by a hindgut extract containing similar amounts of these two compounds.

Host Attractants for Red Weevil, Rhynchophorus ferrugineus: Identification, Electrophysiological Activity, and Laboratory Bioassay

A steam distillate from the freshly cut young bark of coconut palm Cocos nucifera was analyzed by gas chromatography, combined gas chromatography–electroantennographic detection (GC-EAD) and GC-MS to detect host attractants for the curculionid weevil Rhynchophorus ferrugineus, one of the major coconut pests in Sri Lanka. A twin FID peak consisting of a minor and a major component was shown to possess electrophysiological (EAG) activity. The minor peak was identified as γ-nonanoic lactone 1, while the major peak was identified as 4-hydroxy-3-methoxystyrene 2. In an EAG assay the synthetic racemic nonanoic lactone 1 did not elicit a considerable response in the antenna of R. ferrugineus, whereas the laboratory synthesized 2 showed activity. In a laboratory bioassay using a Y-type olfactometer, synthetic 1 and 2 elicited moderate attractant properties to R. ferrugineus, whereas a 1:1 mixture of the compounds showed increased attraction over that of the individual compounds.

Redox-regulated expression of glycolytic enzymes in resting and proliferating rat thymocytes

© 1997 Federation of European Biochemical Societies.

(11Z,13Z)-11,13-hexadecadienal, the sex pheromone of females ofNotodonta dromedarius

polymer. Most functional compounds investigated could be condensed with the polymers within 3 h, reaching average contents between 200 and 400 mg compound/g polymer material. In summary, the results reported here demonstrate that a variety of organic compounds can be conveniently introduced into polymers by this one-pot, three-component coupling process in good yields. We are continuing to investigate the scope and application potential of this convenient preparation method, leading easily and directly to functionalized polymeric materials.

Chemical structure and final steps of biosynthesis of the female sex pheromone of Gastropacha quercifolia (Lepidoptera: Lasiocampidae)☆

Abstract The major volatile constituents in the sex pheromone gland of females of Gastropacha quercifolia (Lepidoptera: Lasiocampidae) were identified as ( Z )-5-Dodecenal 1, ( Z )-5-dodecenol 2 and ( Z )-5-dodecenyl( Z )-5-dodecenoate 3. Synthetic samples of the first two compounds 1 and 2 were able to evoke strong electroantennographic responses from male antennae, however, no electrophysiological activity was found for the ester 3. The final steps involved in the biosynthesis of the three compounds were investigated using deuterated biosynthesis intermediates. ( Z )-5-Dodecenoic acid 14 was established as the immediate precursor of ( Z )-5-dodecenol 2 which is subsequently converted to the ( Z )-5-dodecenal 1. Since a direct desaturation of dodecanoic acid was not observed, the introduction of the double bond appears to take place at an earlier stage of biosynthesis. No evidence was found that the ester 3 might serve as a pheromone pool from which the components 1 and 2 can be derived; on the other hand, ( Z )-5-dodecenol and ( Z )-5-dodecenoic acid served as the bioprecursors of the ester 3.

Pheromone 97*. Der Sexualpheromonkomplex Des Weiblichen Blutbär Thyria Jacobaeae (Lepidoptera, Arctiidae) /Pheromones, 97*. The Sex Pheromone Complex of the Female Arctiid Moth Thyria jacobaeae (Lepidoptera, Arctiidae)

By means of gas chromatographic, mass spectrometric methods and combined GC-electroantennogramm techniques as well as activity comparison with pheromones of related species (3Z,6Z)-c/s-9,10-epoxyeicosadiene 1 and (3Z,6Z)-cis-9,10-epoxyheneicosadiene 2 were identified as the biological active components of the sex pheromone complex of the female arctiid moth Thyria jacobaeae