Juvenilizing effect of ecdysone mimic RH 5849 inGalleria mellonella larvae

The response of the final instar larvae ofG. mellonella to topical application of the non-steroidal ecdysone mimic, RH 5849, was age-related as well as dose-dependent. In young final instar larvae, moderate doses of RH 5849 induced perfect supernumerary larval moults, but doses equal to and higher than 8.5 μg per larva caused premature formation of larval cuticle and were lethal. Application of RH 5849 significantly increased allatotropic activity of the brain, and also activated synthesis of juvenile hormone (JH) by the corpora cardiaca/corpora allata complex. Simultaneous application of RH 5849 and FMev, a potent inhibitor of JH synthesis, to young final instar larvae lowered the incidence of perfect supernumerary larval moults. We conclude that the effect of RH 5849 on the developmental programme inG. mellonella is mediated by the corpora allata.     

Association of DNA replication with nuclear membrane in larvae ofChironomus thummi

Summary In the larvae ofChironomus thummi, the newly replicating DNA has been found to be associated with the nuclear membrane, as evidenced by the isolation of DNA nuclear membrane complexes (M-band) of³H-thymidine labelled larvae.Acknowledgment. The authors thank Dr D. S. Pradhan for discussions and encouragement.     

Phosphoinositide content in the erythrocyte membrane of rats with spontaneous and renal hypertension

Summary The increase of the content of triphosphoinositide in the erythrocyte membrane in rats with spontaneous and renal hypertension and decrease of phosphatidylinositol at spontaneous hypertension were revealed.     

Octopamine,dopamine and noradrenaline content of the brain of the locust,Schistocerca gregaria

Summary The octopamine, dopamine and noradrenaline content of the brain of the locust,Schistocerca gregaria has been determined using sensitive radiochemical-enzymatic assays. Octopamine and dopamine are present in high concentration but the noradrenaline content is only 1/25 that of octopamine. Both reserpine and fusaric acid (a dopamine--hydroxylase inhibitor) produce a significant depletion of the octopamine stores.The author is a M.R.C. of Canada Fellow. Thanks are due to Drs.A. A. Boulton, A. V. Juorio, andP. H. Wu for helpful discussion.     

Octopamine levels during the moult cycle and adult development in the migratory locust,Locusta migratoria

Summary Octopamine content of the head of the locustLocusta migratoria has been determined during the last larval stage, moulting and adult life of 3 groups of insects: female and male gregarious, solitary and CO₂ solitarized. An important difference was found between these 3 groups. Octopamine contents increased in the middle of the larval life and during the adult life. The moulting time is characterized by a sharp decrease of the octopamine content which becomes identical in the 3 groups of insects. The relation between octopamine content, hormone cycles and motility is discussed.     

Octopamine levels during the moult cycle and adult development in the migratory locust, Locusta migratoria.

Octopamine content of the head of the locust Locusta migratoria has been determined during the last larval stage, moulting and adult life of 3 groups of insects: female and male gregarious, solitary and CO2 solitarized. An important difference was found between these 3 groups. Octopamine contents increased in the middle of the larval life and during the adult life. The moulting time is characterized by a sharp decrease of the octopamine content which becomes identical in the 3 groups of insects. The relation between octopamine content, hormone cycles and motility is discussed.     

The effect of proctolin on the adenylate and guanylate cyclases in theLocusta brain at various developmental stages

Summary Proctolin at concentrations 10^–8–10^–7 M elevated by 40% brain adenylate cyclase activity of adultLocusta migratoria migratorioides R.F. In moulting individuals, proctolin caused a decrease in brain adenylate cyclase activity, and it proved to be ineffective in the larvae. Proctolin caused only a slight decrease on guanylate cyclase activity of the brain at every developmental stage.     

The effect of proctolin on the adenylate and guanylate cyclases in the Locusta brain at various developmental stages.

Proctolin at concentrations 10(-8)-10(-7) M elevated by 40% brain adenylate cyclase activity of adult Locusta migratoria migratoriodes R.F. In moulting individuals, proctolin caused a decrease in brain adenylate cyclase activity, and it proved to be ineffective in the larvae. Proctolin caused only a slight decrease on guanylate cyclase activity of the brain at every developmental stage.     

Iridophore development in wild-type and periodic albinoXenopus larvae

Summary Light microscopic studies of iridophore preparations from a^p mutantXenopus larvae revealed abnormalities in the morphology and size distribution of reflecting platelets; purine synthesis is normal. A pleiotropic effect of the a^p gene on melanoblasts and iridoblasts is proposed.     

Water exchange between mother and larvae in scorpions

Summary Scorpion larvae spend their first larval stage settled on their mother's back. Isolated larvae can also survive, but their survival probability is lower than it is if they remain on the back of the mother. Experiments with tritiated water suggest that a water exchange must take place between mother and larvae.     

Pronephric system in haploid and diploid larvae ofXenopus laevis

Zusammenfassung Eine morphologische Untersuchung des Vornierensystems in haploiden und diploiden Xenopuslarven weist darauf hin, dass das haploide Oedem nicht durch eine Funktionsstörung des Vornierensystems verursacht ist.     

The prey consumption and prey preference of the larvae of the mosquitoCulex (Lutzia) raptor on the larvae ofCulex quinquefasciatus

The maximum consumption of the larvae of the pest and vector mosquitoCulex quinquefasciatus by the predatory mosquitoCulex (Lutzia) raptor was studied at various instars of both the predator and the prey. The prey preferences of the predator when given lavae of different instars were also investigated. The IVth instar of the predator consumed the maximum number of Ist instar and the maximum biomass of IVth instar larvae of the prey. Instars I and II of the predator preferred the Ist of the prey; instars III and IV of the predator preferred instars II and III of the prey respectively.The predator consumed an average of 157.1 larvae during its whole larval period, when each instar of the predator was given its preferred instar of the prey.     

Depression of spontaneous and ionophore-induced neurotransmitter release bySalmonella

Summary Exposure of frog neuromuscular junctions to heat-killed, lyophilizedSalmonella typhimurium (SR 11) produces an early increase in spontaneous transmitter release followed by depression of release and blockade of the obligatory release usually induced by ionophore X537A.This study was supported by the Office of Naval Research, Biophysics Section, NR 202-160, N00014-77-C-0630. X537A was a gift of Hoffman-LaRoche. I am greatly indebted to Dr R. McCallum for preparing the Salmonella material. J.A. Kuhn provided the technical assistance.     

Diuretic and antifeedant actions byManduca sexta diuretic hormone in lepidopteran larvae

Neuroendocrine disruption of water balance in insect larvae was evaluated as the basis for a new approach to pest insect control. Effects on water balance and food consumption were measured for larvae ofHeliothis virescens (cotton budworm) treated with syntheticManduca sexta diuretic neurohormone (MasDH). Synthetic MasDH (50–250 nM) caused dose-dependent increases in fluid secretion by larval Malpighian tubules in vitro; higher concentrations resulted in lower fluid secretion. Last instar larvae injected with 20–100 pmol MasDH exhibited increasing weight loss. Larvae injected with 500 pmol MasDH dramatically reduced both water excretion and food consumption by 70%. These latter results indicate that high titers of diuretic hormone can suppress feeding damage by larval insects by depressing water excretion and food consumption.     

Nuclear membrane and chromatin network

Résumé Il existen un certain rapport entre la chromatine et des petites invaginations de la membrane nucléaire. Nous estimons que la charge positive de la membrane et la charge négative des chromosomes peut être la cause inductrice.     

The temporary inactivation of newt larvae by benzimidazole and its alkyl derivatives

Zusammenfassung Benzimidazol und einige von seinen Alkylderivaten inaktivieren Molch-Larven schon in kleinen Konzentrationen. In verdünnte Holtfreter-Lösung zurückgebrachte Tiere gewinnen ihre normale Aktivität schnell wieder. Der zeitweilige Beweglichkeitsverlust scheint analog dem bei Säugetieren durch Benzimidazol erzeugten.