Detection of antibody and antigen in the milkweed bug,Oncopeltus fasciatus

Zusammenfassung Mit Hilfe der Fluoreszenzmarkierung von Proteinen und Ouchterlonys Methode wurde festgestellt, dass Insekten keine Immunität besitzen; Blutserum des Kaninchens blieb während 197 h im Hämolymph der Insekten.

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This research was supported in part by St. Louis University CRIC grants Nos. 64-03 and 65-03.     

Neurosecretion and metamorphosis in the milkweed bug,Oncopeltus fasciatus (Dallas)

Zusammenfassung Exstirpation der 10 neurosekretorischenA-Zellen der Pars intercerebralis führt beiOncopeltus nicht zum Ausfall der letzten Larvenhäutung. Es wird angenommen, dass das Neurosekret derA-Zellen, welches in der Aortenwand gespeichert wird, die Häutung ermöglicht.     

Changes in acid phosphatase activity in 6 tissues of the fifth instar milkweed bug,Oncopeltus fasciatus

Summary Acid phosphatase activity in the hemolymph and cuticle was higher during the early part of the fifth instar than at any other time. The enzyme activity in the fat body, testes, salivary glands, and midgut was statistically the same throughout the instar.Acknowledgment. This research was supported in part by NSF grant GB 26542-Al to D. F.     

Pseudomonas aeruginosa cause epidemic disease in the milkweed bug,Oncopeltus fasciatus dallas (Insecta,Heteroptera)

Summary Pseudomonas aeruginosa was recognized as the causative organism of an epidemic disease occurring in a laboratory breed ofOncopeltus fasciatus. The infection probably occurs peroral and is favoured by high temperature and humidity.Pseudomonas aeruginosa destroys the fat body of the bug.For her interest and discussion I thank Dr.G. Hausner, Miss I. vonGraevenitz and Miss.H. Schilling gave techincal support.     

Effect of precocene II on circadian rhythms of feeding and mating behavior in the milkweed bug,Oncopeltus fasciatus

Summary Oncopeltus fasciatus adults were treated with the antiallatotropin, precocene II and the circadian rhythms of feeding and mating behavior were monitored at 2-h intervals from lights on to lights off under 2 photoperiod regimes. Females ovariectomized as 5th instars were monitored for feeding and mating behavior at 2–3-h intervals from lights on to lights off as well. Neither precocene treatment nor ovariectomy was found to affect the mating or feeding behavioral rhythms under any photoperiod regime.Acknowledgment. This work was supported by a National Science Foundation Grant number PCM76-10560 to M.A.R.     

Effect of precocene II on acid phosphatase activity in the large milkweed bug,Oncopeltus fasciatus (Hemiptera: Lygaeidae)

Summary When precocene II was applied to the fourth instar milkweed bug, there was a significant decrease in acid phosphatase activity in the hemolymph at the 40%, 50%, 60%, and 70% time periods in the stadium.     

In vivo inactivation of denervated corpora allata by precocene II in the bug,Oncopeltus fasciatus

Summary Transection of the nervous connections between the brain and the corpus allatum (CA) inOncopeltus fasciatus does not alter the susceptibility of the CA to precocene II in vivo.The authors wish to thank Patricia Ferugia for rearing the insects; Dr D. Soderlund, Department of Entomology, New York State Agricultural Experiment Station for helpful discussions; and Dr A.O. Lea, Department of Entomology, University of Georgia for technical advice. To whom reprint requests should be addressed     

Exogenous makisterone A accelerates early embryonic development in the milkweed bugOncopeltus fasciatus

Summary Reproducing females ofOncopeltus fasciatus which were treated with exogenous makisterone A and 20-hydroxyecdysone laid eggs with considerably elevated ecdysteroid contents. The early embryonic development was markedly accelerated when the mother was treated with makisterone A, whereas 20-hydroxyecdysone had no influence.Supported by grants of the Deutsche Forschungsgemeinschaft (Do 163/7) to A. D.The technical assistance of Ms Heike Bender is acknowledged. We thank Dr K.-D. Spindler for providing us with antiserum for the RIA.     

Ecdysteroid-dependent larval-adult oviduct transformation in the milkweed bugOncopeltus fasciatus requires absence of juvenile hormone

Summary It has been tested whether juvenile hormone plays a role in the larval-adult transformation of lateral oviducts in the milkweed bug. The transformation is ecdysteroid-dependent, as was reported previously². Application of precocene or juvenile hormone III proved that the absence of juvenile hormone is required.Acknowledgments. This work was supported by a grant (Do 163/91) of the DFG. We thank Ms C. Friederichs for excellent technical support.     

Chemical expression of a sexual dimorphism in the tubular scent glands of the milkweed bugOncopeltus fasciatus (Dallas) (Heteroptera; Lygaeidae)

Zusammenfassung Die Metathorakalduftdrüsen der LandwanzeOncopeltus fasciatus erzeugen als Hauptkomponenten ungesättigte aliphatische Acetate und Aldehyde. Die röhrenförmigen Duftdrüsen, die Acetate erzeugen, und das Vorkommen dieser Acetate im Duftsekret sind für die Männchen spezifisch.     

Comparative effects of ouabain, natriuretic factor and ammonium chloride in the toad urinary bladder

Electrical changes and direct effects on Na-K ATPase activity induced by an endogenous digitalis-like natriuretic factor (NF), NH4Cl and ouabain were studied in toad bladders. NF inhibited the SCC and the Na-K ATPase activity in a similar manner to ouabain, but induced a greater increase in calculated direct current resistance (R) (p less than 0.05). NH4Cl was a weak inhibitor of Na-K ATPase activity, although it produced steeper SCC inhibition slopes than those observed with ouabain or NF (p less than 0.01). The data suggested the same mechanism of action of NF and ouabain on the sodium pump, with an additional effect of the former on apical sodium permeability of the cells and/or closure of paracellular routes leading to an increased tissue resistance. In contrast, the effects of NH4Cl were mostly compatible with intracellular inhibition of apical sodium entry into the cell.     

Properties of a calcium-dependent apyrase in the saliva of the blood-feeding bug,Rhodnius prolixus

Summary The saliva of the blood-feeding bugRhodnius prolixus contains at least 11 proteins, and has Ca²⁺-dependent apyrase activity. The activity has a broad pH optimum between pH 7 and 9, and is inhibited by Mg²⁺. Polyacrylamide gel electrophoresis and gel filtration suggest the possibility of at least 2 enzymes responsible for the activity.This work was supported by the National Science and Engineering Research Council of Canada. We are grateful to D. F. Mettrick for use of equipment, and to R. Hewson for invaluable assistance.     

Chromosome structure and meiosis in a pentatomid bug

Résumé Bagrada picta F. mâle possède 14 chromosomes dont une paire X-Y. Tous les chromosomes sont monocentriques à l'exception de l'Y chez lequel il est impossible de trouver un centromère localisé. Les autres éléments peuvent être, selon leurs dimensions et la position du centromère, rattachés à six types différents.     

The action of ouabain in promoting the release of catecholamines

Summary It is suggested that ouabain promotes catecholamine release by causing a rise in intracellular Na⁺ which, in turn, causes an elevated steady-state level of intracellular Ca²⁺. It is suggested that the Na⁺–K⁺-ATPase is not directly involved in exocytosis at either adrenergic or cholinergic synapses.     

Digoxin and ouabain increase the synthesis of cholesterol in human liver cells

Digoxin and ouabain are steroid drugs that inhibit the Na⁺/K⁺-ATPase, and are widely used in the treatment of heart diseases. They may also have additional effects, such as on metabolism of steroid hormones, although until now no evidence has been provided about the effects of these cardioactive glycosides on the synthesis of cholesterol. Here we report that digoxin and ouabain increased the synthesis of cholesterol in human liver HepG2 cells, enhancing the activity and the expression of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), the rate-limiting enzyme of the cholesterol synthesis. This effect was mediated by the binding of the sterol regulatory element binding protein-2 (SREBP-2) to the HMGCR promoter, and was lost in cells silenced for SREBP-2 or loaded with increasing amounts of cholesterol. Digoxin and ouabain competed with cholesterol for binding to the SREBP-cleavage-activating protein, and are critical regulators of cholesterol synthesis in human liver cells. Received 10 January 2009; received after revision 11 February 2009; accepted 6 March 2009