Insecticidal effects of essential oils. A study of the effects of essential oils extracted from eleven Greek aromatic plants on Drosophila auraria.

Effects of the essential oils (EOs) extracted from eleven aromatic plants belonging to the Lamiaceae family (common in the Greek flora) were examined upon three different developmental stages of Drosophila auraria. All of the EOs examined exhibited insecticidal effects, either by preventing egg hatching, or by causing the death of larvae and adult flies. In several cases, malformation and/or prohibition of puparium formation was also observed.     

Histidine-induced injury to cultured liver cells,effects of histidine derivatives and of iron chelators

The amino acid histidine is an excellent buffer and is therefore included in several organ preservation solutions used in transplantation medicine. However, when used at concentrations as in these solutions, histidine has a marked injurious potential. Therefore, we here assessed the mechanism of histidine-induced cell injury and searched for ways to use the buffering power of histidine but avoid histidine toxicity. When cultured hepatocytes were incubated in HTK solution or in modified Krebs-Henseleit buffer containing 198 mM L-histidine at 37°C, most cells lost viability within 3 h (LDH release 86 ± 7% and 89 ± 5%, respectively). This injury was accompanied by marked lipid peroxidation, and was strongly inhibited by hypoxia, by the antioxidants trolox, butylated hydroxytoluene and N-acetylcysteine and by the membrane-permeable iron chelators 2,2′-dipyridyl, 1,10-phenanthroline, LK 614, LK 616 and deferoxamine. Thus, histidine-induced cell injury appears to be mediated by an iron-dependent formation of reactive oxygen species. D-Histidine, imidazol and L-histidine methyl ester also elicited marked injury, while the N-substituted derivatives Nα-acetyl-L-histidine and tert-butyl-oxycarbonylhistidine and histidine-containing dipeptides showed almost no toxicity. Histidine toxicity, its iron dependence and the superiority of Nα-acetyl-L-histidine were also evident during/after cold (4°C) incubations. Therefore, we suggest the addition of iron chelators to histidine-containing solutions, and/or replacing histidine with Nα-acetyl-L-histidine in organ preservation solutions. Received 23 October 2006; accepted 21 November 2006     

Cytogenetic studies of Hynobiidae (Urodela). IX. Karyological characteristics ofHynobius abei Sato by means of R-and C-banding

Summary Chromosomal characteristics of the salamander speciesHynobius abei, from Ohimya (Kyoto) were revealed by the techniques of R-and C-banding. The karyotype ofH. abei was characterized by the shortness of an R-negative (C-positive) band in the terminal region of the long arm of chromosome 2 and a band encompassing the whole short arm of chromosome 10. These two bands inH. abei were the shortest among those of the variousHynobius species that have been examined. Otherwise no differences could be detected betweenH. abei and seven other pond-type species ofHynobius (2n=56) in terms of the banding patterns of 18 specifically identifiable pairs of their chromosomes.     

Differential olfactory perception of enantiomeric compounds by blind subterranean mole rats (Spalax ehrenbergi)

The behavior of mole rats (Spalax ehrenbergi) near pairs of enantiomeric compounds was examined in 901 two-choice experimental tests. Positioning of the nest and food store and the preferred location of the tested animal were used to assess attraction or aversion to the tested odorants. The results indicated that mole rats respond differentially to odors of stereoisomers (enantiomers of carvone, citronellol, and fechone). They responded to one enantiomer of each tested pair but were indifferent to or did not smell the other. Both sexes were attracted to the odor of R-(–)-carvone and repelled by the odor of (+)-citronellol. Females were attracted to the odor of (–)-fenchone while males had no preference. By contrast, all animals were indifferent to or did not smell the odor of S-(+)-carvone, (–)-citronellol, and (+)-fenchone. Further research to distinguish between these alternatives (indifference vs hyposmia/anosmia) is suggested.     

Growth inhibitory,insecticidal and antifeedant effects of some antileukemic and cytotoxic quassinoids on two species of agricultural pests

Summary Several quassinoids, obtained by isolation and derivatization fromSimaba multiflora andSoulamea soulameoides, were evaluated for growth inhibitory and insecticidal effects against the tobacco budworm (Heliothis virescens) and for antifeedant effects againstH. virescens and the fall armyworm (Spodoptera frugiperda). The relative activity of the quassinoids as insect growth inhibitors generally paralleled their known relative potency as antileukemic and cytotoxic agents.Phytochemical aspects of this work were supported by Contract CM-97295 with the Division of Cancer Treatment, National Cancer Institute, National Institutes of Health, Bethesda, Md. Insects were kindly supplied by the agency of the United States Department of Agriculture at Brownsville, TX.     

In vitro metabolism of the trichothecene 4-monoacetoxyscirpenol by fungus- and non-fungus-feeding insects

Summary The metabolism of the trichothecene 4-monoacetoxyscirpenol by intact gut tissue was determined in the fungus-feeding Nitidulid,Carpophilus hemipterus (L.) and the non-fungus-feeding caterpillars, the fall armyworm,Spodoptera frugiperda (J. E. Smith) and the corn earworm,Heliothis zea (Boddie). The primary metabolite was the hydrolysis product scirpentriol. The amount of metabolism by theC. hemipterus larvae was ca 10 times that of the caterpillars on a per mg protein basis, suggesting metabolic adaptation for feeding on fungi that may contain mycotoxins.Acknowledgment. The authors wish to thank S. Taylor for technical assistance.The mention of firm names or trade products does not imply that they are endorsed or recommended by the U.S. Department of Agriculture over other firms or similar products not mentioned.     

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.     

Biological activity of flucycloxuron,a novel benzoylphenylurea derivative,onTenebrio molitor: comparison with diflubenzuron and triflumuron

Flucycloxuron, a novel benzoylphenylurea (BPU) derivative, exhibited insecticidal activity when injected into newly ecdysed pupae ofTenebrio molitor. Mortality occurs because of defective adult ecdysis. Treatment caused a reduction in both cuticle thickness and incorporation of¹⁴C-labelled precursor into chitin, although it had no significant effect on the protein synthesis. The potencies of other BPU compounds as inhibitors of chitin biosynthesis have been examined and results showed that diflubenzuron was less effective than either flucycloxuron or triflumuron.     

Inhibition of invasion and intraerythrocytic development ofPlasmodium falciparum by kinase inhibitors

We have examined the effects of seven protein kinase inhibitors (staurosporine, genistein, methyl 2,5-dihydroxycinnamate, tyrphostins B44 and B46, lavendustin A and R03) on the erythrocytic cycle of the malaria parasite,Plasmodium falciparum. One (staurosporine) strongly inhibits serine/threonine kinases, but the remainder all exhibit a strong preference for tyrosine kinases. We have been able to discriminate between effects on invasion and on intraerythrocytic development. All reagents impeded development of intraerythrocytic parasites, though at widely differing concentrations, from the sub-micromolar to the millimolar. Several inhibitors, including staurosporine, also reduced invasion. The phosphatase inhibitor, okadaic acid, had a strong inhibitory effect both on invasion and development. The regulation of malaria development by phosphorylation or dephosphorylation reactions at several points in the blood-stage cycle is implied.     

Rapid effects of insulin on cyclic GMP location in an intact protozoan

We studied rapid changes in location of cyclic GMP inTetrahymena pyriformis. Insulin caused cGMP localization in cilia and near the plasma membrane (0.5–1 min). Later (1–5 min) cGMP localization was diffuse in cytoplasm with perinuclear accentuation. Inactive insulin analogs did not elicit these changes.     

Septation and fragmentation inOedogonium mitochondria as different and independent effects of dimethyl sulfoxide (DMSO) treatment

Summary Oedogonium cardiacum Wittrock, a filamentous green alga, was treated with DMSO. The substance induced active swelling and fragmentation of mitochondria at both 5 and 7.5%. Septa were observed at 7.5% only and were not identical with the fragmentation sites. Thus it is concluded that internal partition by septa is not a prerequisite for mitochondrial fragmentation or division.Acknowledgment. This work was supported by the Österreichische Nationalbank, Jubiläumsfondsprojekt No. 1927.     

Regulation of cross-bridge detachment by Ca ions at high ionic strength in molluscan catch muscle

Summary Changes in the profile of equatorial intensities of X-ray diffraction from an intact, anterior byssal retractor muscle (ABRM) ofMytilus were examined at rest, during contracture brought about by acetylcholine (ACh) and a subsequent rigor-like contraction caused by raising the tonicity of the external solution, and after returning the tonicity to normal. The results suggest that the cross-bridges formed between thick and thin actin filaments during the ACh-contracture were maintained in the hypertonic solution and broken on decreasing the tonicity before the recovery of spacing of the actin filament lattice. A similar rigor-like contraction was induced in glycerinated ABRM by increasing salt concentration during active contraction. The rigor-like force declined rapidly when Ca⁺⁺ concentration decreased. The results suggest that the detachment of the cross-bridge from the actin filament is regulated by Ca⁺⁺ at high ionic strength in the ABRM.     

Criteria for permissible browse impact on sycamore maple (Acer pseudoplatanus) in mountain forests

Summary A naturally regenerated young-growth in the Buchser Hochwald area in the Canton of St. Gallen, Switzerland, was used to determine the silviculturally permissible browsing limit for sycamore maple (Acer pseudoplatanus). The investigated area is situated at an altitude ranging from 1280 to 1310 m a.s.l. on anAbieti-Fagetum typicum site. Browsing was done by red deer (Cervus elaphus) and roe deer (Capreolus capreolus). A total of 57 sycamore maples, 1.30 m high, were examined. The actual browse impact on these plants was assessed by determining the frequency of browsing marks on the stem axis. To this end, the plants were cut into sections of 5 cm each and then split radially. On this basis it was possible to calculate permissible shares of browsed plants for four different size categories between 0.10 and 1.30 m. The permissible share of plants with two or more visible browsing marks on the stem axis amounted to 37.8% as an average value for the total risk period. This corresponds to a quota of 26.9% browsed terminal shoots per annum.     

Enzymatic processing of pheromones and pheromone analogs

Summary Pheromone perception requires rapid enzymatic degradation of the active chemical signal in the sensory hairs. Three insects are used to illustrate chemical approaches to studying the degradation of pheromones by antennal enzymes. First, hydrolysis of acetate and haloacetate esters is examined in the diamondback moth,Plutella xylostella. Second, aldehyde oxidation and the selective inhibition of the oxidase and dehydrogenase activities are described for the tobacco budworm moth,Heliothis virescens. Finally, a stereochemical analysis of the epoxide-hydrase catalyzed addition of a water molecule to the oxirane ring of disparlure is described for the gypsy moth,Lymantria dispar.     

Toxic effects of boric acid on the German cockroach

Boric acid is a slow-acting, inorganic insecticide whose mode of action has not been satisfactorily elucidated. Reported here is evidence which shows that ingested boric acid destroys the cellular lining of the foregut of German cockroaches,Blattella germanica (L.). This effect appears to be sufficient to bring about the death of the insects, perhaps ultimately by starvation. This finding is important because resistance to conventional insectivides may re-establish boric acid as a prominent cockroach control chemical.     

New phytotoxic butenolides produced bySeiridium cardinale,the pathogen of cypress canker disease

Summary Two new butenolides, seiridin andiso-seiridin, were isolated from culture filtrates ofSeiridium cardinale, the pathogen of cypress canker, a destructive disease ofCupressus and relatedConiferae These metabolites were characterized as 3-methyl-4-(2-hydroxyheptyl)-2(5H)-furanone and its 4-(3-hydroxyheptyl) isomer, respectively. Chlorotic, and necrotic symptoms were produced on leaves of either host or non-host test plants by absorption of 0.3 mg/ml solutions of either compound. These also showed antibacterial activity.This study was supported in part by the National Research Council, Rome (special ad hoc project Chimica fine e secondaria) and in part by the Ministry of Education, Rome.     

Comparative aspects of structure and action of molluscan neuropeptides

A number of neuropeptides were isolated from the ganglia and muscles of molluscs, and their actions were examined. Diverse neuropeptides, in addition to several classical neurotransmitters, were suggested to be involved in the regulation of the anterior byssus retractor muscle ofMytilus. A wide structural variety of members of theMytilus inhibitory peptide family was observed in each of the generaMytilus, Achatina andHelix. Gly-Trp-NH₂, the C-terminal dipeptide fragment of the neuropeptide AGPWamide, showed a more potent action than the parent peptide in all of the muscles examined. Peptides related to some molluscan neuropeptides were found to be distributed interphyletically. Some neuropeptides containing ad-amino acid residue were found inAchatina andMytilus. These aspects of molluscan neuropeptides are thought not to be exceptional.     

Double cone mosaic pattern in the retina of larval and adult piranha,Serrasalmus spilopleura

The mosaic pattern of double cones of retinas in larval and adult piranha,Serrasalmus spilopleura, was examined. Samples from two habitats in the same reservoir, characterized by different light conditions, were examined. The same square pattern was found in all sampled retinas indicating that, for this species, there is no apparent relation between the patterns of double cone arrangement and environmental luminosity.     

The effects of diltiazem onPeriplaneta americana

Summary The effects of the calcium antagonist diltiazem on nerve and muscle in the cockroachPeriplaneta americana were examined. Diltiazem was observed to inhibit myogenic and glutamate-induced contractions of the visceral muscle while having either a potentiating, an inhibiting or a biphasic effect against proctolin-induced contractions. Against the isolated nervous system, diltiazem induced an increase in spontaneous discharge activity, followed by nerve block. Injection of diltiazem into cockroaches produced behavioral and toxic effects.Acknowledgments. The expert technical assistance of Miss Susan Auffarth is gratefully acknowledged. Bioresmethrin was provided by Dr. G.J.P. Singh. We would like to thank Nordic Laboratories for the gift of diltiazem.     

Torus shaped bands at the 2R telomere region and at the region 68 of the salivary gland chromosomes ofDrosophila auraria

Summary The telomere of the 2R arm of the salivary gland chromosomes ofD. auraria exhibits a definite toroidal structure in routine squashed preparations, stained either by propionic orcein-carmine or by fluorescent dyes. There is evidence that a band (or bands) of region 68 (possibly homologous to that ofD. melanogaster) of the 3L chromosome arm also exhibits a toroidal structure. These toroids are associated with heterochromatin, but it is not certain that they are themselves heterochromatic.Acknowledgments. This work was supported by a grant from Volkswagenwerk-Stiftung to C.D.K. The outstanding technical assistance of Ms G. Karamanlidis is acknowledged.