Antibody-induced formation of caps inToxoplasma gondii

Summary Trophozoites ofToxoplasma gondii from mouse peritoneal exudate move their surface membrane antigens towards one pole of the cell when incubated with antibodies. The phenomenon may be induced in up to 50% of incubated parasites. It is prvented by some metabolic inhibitors and low temperatures (0–4°C). These properties do not change in parasites subpassaged after repeated incubation with antibodies.We wish to thank Dr. J.lusarczyk of the National Institute of Hygiene for his help in preparation the photomicropgraphs.     

In vitro mutagenicity testing of a potent,new, benzoyl urea insect growth regulator

Summary Bacterial mutagenicity assay to detect potential chronic toxicity of a potent, new, benzoyl urea insect growth regulator (CGA-112913 or IKI-7899, formerly UC-62644) was conducted using 5 histidine auxotrophs ofSalmonella typhimurium. Tests within the concentration range of 0.9–500 g (saturating)/plate of the compound with and without the 5–9 mammalian metabolic activation system showed no mutagenic effects clearing the way for long-term chronic toxicology studies.The authors thank Professor Bruce N. Ames for supplying the tester strains together with all the relevant information for conducting the bioassays and Ms. Norma Charlebois for her meticulous technical assistance.     

Continuous light abolishes the maternal entrainment of the circadian activity rhythm of the pups in the field mouse

Summary 1212-h cycles of presence and absence of mother mouse act as a zeitgeber and entrain the circadian rhythm of locomotor activity in the pups ofMus booduga under continuous darkness or continuous dim light. Continuous higher illumination of 15–25 lx abolishes this impressive maternal entrainment.Acknowledgment. We are grateful to the DST, Government of India, for financial support under their IRHPA scheme. N.V. is the recipient of a Senior Research Fellowship of CSIR, New Delhi. We thank Dr. R. Subbaraj for discussions.     

Methyllycaconitine,a naturally occurring insecticide with a high affinity for the insect cholinergic receptor

Summary Studies of extracts ofDelphinium seeds, long known to be insecticidal, revealed that a principal insecticidal toxin was methyllycaconitine, which is shown to be a potent inhibitor of -bungarotoxin binding to housefly heads (K_inh=2.5×10^–10±0.5×10^–10M).Calgary for gifts of MLA, citrate and lycoctonine, and Dr W. Bowers of the University of Arizona for the original extract ofDelphinium seeds. We would also like to acknowledge the able technical support of Ms C. Dushin, Mr E.L. Bowman, Dr C. C. Gagne, Mr R. F. Borysewicz and Dr P. Mowery for his assistance in obtaining and interpreting the carbon-13 NMR spectra.     

Cocarcinogens of the diterpene ester type fromCroton flavens L. and esophageal cancer in Curaçao

Summary From the roots ofCroton flavens L., 3 highly irritant and tumor promoting Croton factorsF ₁–F ₃ and the corresponding 3 cryptic Croton factorsF₁–F₃ were isolated and characterized as novel esters of 16-hydroxy- and 4-deoxy-16-hydroxyphorbol, respectively. These findings suggest that tumor promoters of the phorbol ester type, ingested through the widespread and frequent use ofCroton flavens according to local habits, may be causally related to the well recognized high rate of esophageal cancer on Curaçao.Dedicated to Prof. Dr H. P. Rusch, Director Wisconsin Clinical Cancer Center, Madison, Wis. USA, on occasion of his 70th birthday. We wish to thank Dr J.F. Morton, Morton Collectanea, University of Miami, Florida, USA, for kindly supplying us with the plant material.     

Identification of an acyclic diterpene alcohol in the defense secretion of soldiers ofReticulitermes lucifugus

Summary The defense secretion of soldiers ofReticulitermes lucifugus has been shown to contain, predominantly, (R)-(–)-(E,E)-geranyllinalool together with germacrene A and -farnesene.This report covers part of a collaborative study with J.-L. Clément, Lab. d'Evolution, Université P. et M. Curie, Paris, to whom we are grateful for supplies of material and discussions. We also thank Dr O.T. Jones for collections ofReticulitermes lucifugus.     

Effects of the virulence plasmid ColV,I-K94 on the sensitivity ofEscherichia coli to putative environmental inhibitory agents

Summary Derivatives ofEscherichia coli carrying the virulence plasmid, ColV, I-K94 were more resistant than the ColV^– parents to phage Mel but were more sensitive to the hydrophobic inhibitors deoxycholate, erythromycin and lysozyme. The basis for these changes in sensitivity has been examined in ColV⁺ mutants with altered colicin or VmpA protein levels and in ColV⁺ strains with repressed transfer properties.The authors wish to thank the Fondacion Gran Marischal de Ayacucho and the Central Research Fund of the University of London for financial support.     

Chromatin circles in amphibian previtellogenic oocytes

Summary Previtellogenic oocytes ofOdontophrynus americanus display hundreds of chromatin circles. Electron microscopy of spread preparations of isolated nuclei shows that the circles originate from the chromatin. The circles change their morphology and form new copies. The length of the DNA packed in the nucleosomal circles is about 2.5–3.5 m or multiples of this value. Assuming that histones need not be removed from chromatin before DNA replication³ we suggest that the circles might belong to the process of rDNA amplification.This work was supported by grants from the Brazilian CNPq, FAPESP and FEDIB.We thank Dr A. Brunner Jr for the use of the electron microscope and Dr N. Leon for his valuable help.     

Insect tissues,not microorganisms,produce linoleic acid in the house cricket and the American cockroach

Summary Biosynthesis of linoleic acid, 182(n–6), was unambiguously demonstrated to occur in the cockroach,Periplaneta americana, and the cricket,Acheta domesticus. Axenic tissue from both of these insect species was demonstrated by radio-gas-liquid chromatography (radio-GLC) and radio-high-performance liquid chromatography (radio-HPLC) to incorporate [1-¹⁴C]acetate and [1-¹⁴C]oleate into this essential fatty acid.This work was supported by the National Science Foundation under grant DCB-8914417. We would like to thank Coby Schal for his generous gift of American cockroaches and Tania Kellermeyer for her excellent technical assistance.     

Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III throughout the life cycle of a hemimetabolous insect,the ovoviviparous cockroachNauphoeta cinerea

Summary Titers of ecdysone, 20-hydroxyecdysone and juvenile hormone III were measured in whole body extracts or hemolymph of embryos, first, penultimate and last stadium nymphs, and adult females ofNaupoheta cinerea. We used a gas-chromatography/mass spectrometry method for quantifying juvenile hormone and a radio-immunoassay for ecdysteroid determination. Juvenile hormone III is particularly abundant in the embryonic stage (up to 960 ng/g), at a low level in first and penultimate stadium nymphs (2–10 ng/ml) and almost absent in the last nymphal stadium; in the adult female the juvenile hormone titer rises to 180 ng/ml in hemolymph during rapid oocyte growth. The titers of ecdysone and 20-hydroxyecdysone undergo similar fluctuations in the embryonic and nymphal stages, being highest at the time of cuticle formation in the embryo and a few days before the nymphal and adult molts (around 100–200 ng/ml for exdysone and 2–4 g/ml for 20-hydroxyecdysone).Acknowledgments. We thank Mrs A. Tschan for rearing the cockroaches, Mr M. Kaltenrieder for drawing the graphs, Mr G.C. Jamieson and Mrs C. Reuter for GC/MS analyses. We are also grateful to the Swiss National Science Foundation (grant no. 3.291-0.82 to B. Lanzrein) and the United States National Science Foundation (grant no. PCM 82-08665 to D.A. Schooley) for their financial support.     

Acetylcholinesterase activity in anAedes aegypti cell line

Summary Considerable acetylcholinesterase (AChE) activity was detected in anAedes aegypti established cell line. The enzyme is blocked by 10^–6 M eserine sulfate, displays excess substrate inhibition and slowly hydrolyzes butyrylthiocholine. A 2-fold stimulation of AChE activity was shown after 2 days exposure to 3×10^–7 M -ecdysone. AChE activity found in the fresh medium is the contribution of the fetal calf serum portion. A direct relationship between levels of serum and the AChE activity in the cultured cells was demonstrated.Acknowledgment. I wish to thank Dr J. Peleg of the Israel Institute for Biological Research for providing the starting culture ofAedes aegypti cells.     

Gamma aminobutyric acid induced changes in the spontaneous firing rates of insect neurons

Zusammenfassung -Aminobuttersäure (GABA) vermindert die Impulsfrequenz der spontan-aktiven Nervenzellen beim Insekt. Wirksame Konzentrationen betragen 0,1–25 · 10^–4 M. Ein unerwartetes Ergebnis war die Beobachtung, dass nach Applikation von GABA eine Erhöhung der Impulsfrequenz vor der Verminderung stattfindet.

---

---

This investigation was supported in part by the NSF College Teacher Research Participation Program, Grant No. GY-682, and by NSF Undergraduate Research Participation Program, Grant No. GY-151. — We thank Mr.A. McAfee, our undergraduate participant, for his assistance in this investigation.     

Benzamide potentiation of behavioral apomorphine-induced effects; mechanism involved

Summary A new N-pyridinyl benzamide was found to potentiate strongly the effects of apomorphine on the motility of reserpinized mice and on circling behavior. Since dopaminergic agonist activity could not account for this potentiation, involvement of-adrenergic agonist activity provided the only consistent explanation.Acknowledgments. We wish to thank Mr A. Decoodt for his excellent technical assistance and the Laboratoire de Chimie Therapeutique (Prof. Le Baut), Université de Nantes, for providing samples of N-PCB.     

Crossing between nondiapausing and diapausing races of Sarcophaga peregrina

Summary The temperate race (D) ofS. peregrina undergoes pupal diapause in response to certain environmental conditions of photoperiod (13L:11D–11L:13D) and temperature (under 20°C). The tropical race (ND) does not do so under the same circumstances. The tendency toward diapause was suppressed in 30–40% of the hybrids of crossings D×ND and ND×D even under such short day and low temperature conditions as 11L:13D–9L:15D, 20°C. For entering diapause, the hybrids require a shorter day length (13L:11D) than that of (D) parents (15L:9D).We thank Dr R. Kano and Dr S. Shinonaga, Tokyo Medical and Dental University, for supplying the New Guinean material.     

Insect hormones in vertebrates: Anabolic effects of 20-hydroxyecdysone in Japanese quail

Ecdysteroids are hormones controlling cell proliferation, growth and the developmental cycles of insects and other invertebrates¹. They are occasionally present in various unrelated plants for no apparent reason; no phytohormonal function has yet been identified. In certain cases, ecdysteroids are accumulated to high levels in leaves, roots or seeds. Some ecdysteroid-containing plants have been known as medicinal plants for centuries. One of them,Leuzea carthamoides Iljin (Asteraceae), growing in Central Asia, contains 0.4% ecdysteroid in dry roots and 2% in seeds. A pharmacological preparation from this plant, Ecdisten, is already available as a commercial preparation for its anabolic, tonic and other effects, for medical use (review²). It remained problematic, however, whether ecdysteroids were truly responsible for these effects, becauseLeuzea contains a number of other biologically active compounds in addition to ecdysteroids. We extracted and purified ecdysteroids from the seeds ofLeuzea. With 6 g of 96% 20-hydroxyecdysone (20E), we made a large-scale feeding assay with Japanese quail to find out whether ecdysteroid alone could duplicate the anabolic effects of the seeds. We found that the 96% ecdysteroid increased the mass of the developing quails in a dose-dependent manner, with the rate of increase proportional to the ecdysteroid content in the seeds; there was a 115% increase in living mass with 100 mg kg^–1 of pure 20E compared with 109.5% increase with 100–180 mg kg^–1 20E equivalents in the seeds. We conclude that the plethora of growth-promoting, vitamin-like effects induced in vertebrates byLeuzea is mediated by ecdysteroids.     

Age-related perseveration of the precopulatory behaviour in maleDrosophila melanogaster

Summary In response to an interruption of their courtship, males ofD. melanogaster exhibit a lasting sexual arousal (up to 30–60 min), expressed behaviourally by characteristic wing displays. A study of this effect centered on two memory mutants of different ages suggests that it can be related to an ageing-dependent perseveration, rather than to modifications in memory processing.Acknowledgments. This research was supported by an exchange grant of the Royal Society. We are grateful to Dr Linda Partridge for advice and loan of apparatus.     

Oxidative stress in the moderately halophilic bacteriumDeleya halophila: Effect of NaCl concentration

The sensitivity ofDeleya halophila to oxidative stress caused by hydrogen peroxide (H₂O₂) was found to vary, depending on the NaCl concentration of the growth medium. Pretreatment of the bacteria at a low concentration of H₂O₂ (50 M) protected the cells against the lethal effects of higher levels (1–2 mM) of H₂O₂. Exposure ofD. halophila cells to 50 M H₂O₂ resulted in the induction of several proteins (hydrogen peroxide-inducible proteins, hips). However, the kinetics of induction, the extent of induction and the number of hips appear to be influenced by the salt concentration of the growth medium. Five of the hips exhibited apparent molecular masses identical to those of five heat shock proteins (hsps).     

ZNS-aktive Phenylpropylamine vonCatha edulis FORSK. (Celastraceae) kenyanischer Herkunft

Summary The phenylpropylamine fraction ofCatha edulis FORSK. grown in Kenya has been investigated. The major components have been found to be (S)-(–)--aminopropiophenone (1), (+)-norpseudoephedrine (2) and(–)-norephedrine (3). Quantitative ratios of1, 2, 3 in tissues of different age are discussed.

---

ZNS-aktive Phenylpropylamine vonCatha edulis FORSK. (Celastraceae) kenyanischer Herkunft

     

Hyposmotic shock-induced discharge in acontia ofCalliactis parasitica is blocked by gadolinium

On acontia ofCalliactis parasitica it was observed that mechanical stimuli applied by a gelatin probe, a method effective in tentacles of Anthozoa, do not induce the discharge of nematocytes. Hyposmotic shock, performed by treatment with NaCl solution 35% hyposmotic with respect to sea water, induces, in the presence of Ca²⁺, the discharge that spreads along the acontial filament, as previously observed following treatment with SCN^–. The hyposmotic shock-induced discharge is blocked by Gd³⁺ at a concentration of 1 M. 10 M Gd³⁺ prevents also the SCN^–-induced discharge. These results suggest the presence of stretch activated cation channels either in nematocytes and/or in supporting cells as well as a possible effect of SCN^– on this class of ion channels.     

AnAnolis skin melanophore assay suitable for photoaffinity labeling studies with α-MSH

Summary Visual determination of MSH-induced pigment migration in melanophores of small pieces ofAnolis carolinensis skin is standardized by first measuring photoelectrometrically the change in reflection/transmission of the whole dorsal skin in response to different hormone concentrations. This method allows the rapid and precise recording of time-response curves after photoaffinity labeling of MSH receptors or of dose-response curves of large series of synthetic compounds.Acknowledgments. We wish to thank Ms V. Jäggin, Ms C. Schulthess and Ms G. van Hees for excellent technical assistance, Dr. R. Andreatta, Ciba-Geigy AG, Basel, for his generous gift of -MSH and Prof. A Pletscher for his continuous interest. This work was supported by the Swiss National Science Foundation.