Nα-quinaldyl-L-arginine·HCl,a new defensive alkaloid fromSubcoccinella-24-punctata (Coleoptera,Coccinellidae)

The isolation of N-quinaldyl-L-arginine·HCl (1) from the CoccinellidaeSubcoccinella-24-punctata is reported. The structure, first established on the basis of the analysis of the spectral properties of1, has been confirmed by synthesis. The alkaloid is of endogenous origin and markedly deterrent to ants.     

Some citrus chitinases also possess chitosanase activities

Several acidic chitinase and chitosanase isoforms were found in 4-week-old nonembryogenic sweet orange (Valencia [Citrus sinensis (L.) Osbeck]) callus tissue. Two isoforms (designated A1-CF1 and A1-CF2) were purified to homogeneity using HPLC size exclusion, anion exchange, and chromatofocusing techniques. Both hydrolase isoforms exhibited activity with either colloidal chitin or solubilized shrimp shell chitosan. Specific activities for the purified isoforms could not be calculated because of the lack of protein and contamination of ampholytes. However, the specific activities for chitinase and chitosanase after anion exchange were respectively 404 nmol GlcNAc per min per mg protein and 2,475 nmol GlcN per min per mg protein. The M_r for both enzymes was 30,500. The homogeneous proteins cross-reacted in western blots with antiserum against a basic class I potato leaf chitinase.     

A 6,000-year sedimentary molecular record of chemocline excursions in the Black Sea

The Black Sea is the world's largest anoxic basin; it is also a contemporary analogue of the environment in which carbonaceous shales and petroleum source beds formed. Recently, Repeta et al. reported that anoxygenic photosynthesis may be an important component of carbon cycling in the present Black Sea, owing to a shoaling of the chemocline and consequent penetration of the photic zone by anaerobic waters in the past few decades. It has been suggested that this was due to an anthropogenic decrease in freshwater input to the Black Sea, although natural causes were not ruled out. Here we report the distributions of sequestered photosynthetic pigments in eight core samples of sediments from the Black Sea ranging in age from zero to 6,200 years before the present. Our results show that photosynthetic green sulphur bacteria (Chlorobiaceae [correction of Clorobiaceae]) have been active in the Black Sea for substantial periods of time in the past. This finding indicates that the penetration of the photic zone by anaerobic waters is not a recent phenomenon, and suggests that natural causes for shoaling of the chemocline are more likely than anthropogenic ones.     

Evaluation of monoaminergic receptors in the genetically epilepsy prone rat

Summary The intensity of sound-induced convulsions in the genetically epilepsy-prone rat (GEPR) was reduced in a dose related fashion by intracerebroventricular administration of dobutamine, (₁ agonist), terbutaline (₂ agonist) or phenylephrine (₁ agonist). BHT-920 (₂ agonist) did not cause a dose-related decrease in sound-induced convulsion intensity. Binding studies showed that whole brain and receptor densities (B_max) were normal while the K_d was increased for the ligand in GEPR brain.Acknowledgment. We are most grateful to Boehringer Ingelheim for generously supplying BHT 920. We are also indebted to Ciba-Geigy Corporation for the gift of terbutaline hydrochloride and phentolamine hydrochloride. The work was supported in part by NIH grant NS 16829.     

Physiological state of submitochondrial particles and their susceptibility to Triton X-100

Summary The solubilizing effect of Triton X-100 on beef heart submitochondrial particles (ETP_H) has been studied under various physiological conditions. Coupled, uncoupled and azide-inhibited ETP_H particles have been studied. Quantitative and qualitative differences are found in the proteins solubilized by the detergent from ETP_H particles under the various conditions tested.Acknowledgments: This work was supported in part by a grant from a Spanish Comisión Asesora para la Investigación Cientifica y Técnica. M.C. Barbero was recipient of a scholarship from the Basque Government.     

A new interstellar molecule: tricarbon monoxide

The cold dark interstellar Taurus Molecular Cloud One (TMC-1) is a rich source of acetylenic and polyacetylenic molecular species. As well as linear closed-shell molecules (H(C triple bond C)nCN) and symmetric rotors (CH3C triple bond CH, CH3C triple bond CCN), several radicals (C triple bond CH, C triple bond CCN, (C triple bond C2H) have also been identified, many of which had not been studied previously in the laboratory. Whether the observed abundances can be understood in terms of purely gas-phase ion-molecule chemical schemes, which produce reasonable agreement for the simplest polyatomic species, is unclear; alternative models involving the particulate interstellar grains as catalysts or sources have also been suggested. We now report the detection in TMC-1 of a new molecule, tricarbon monoxide (C3O), whose pure rotational spectrum has only very recently been studied in the laboratory. As C3O is the first known interstellar carbon chain molecule to contain oxygen, its existence places an important new constraint on chemical schemes for cold interstellar clouds. In fact, the observed abundance of tricarbon monoxide fits quite well into our model of galactochemistry.     

Increased susceptibility ofTrypanosoma lewisi infected,or decomplemented rats toSalmonella typhimurium

Summary Rats infected withTrypanosoma lewisi or decomplemented by injection of cobra venom factor or complement activating factor of trypanosomes were found to be more susceptible to infection withSalmonella typhimurium. Decomplemented rats subsequently infected withT. lewisi developed higher blood parasitemia than did normalT. lewisi infected rats.This project is supported by the National Research Council of Canada grant A 0068 and a grant from the International Development Research Center.     

Experimental immunity against trypanosomiasis

Summary 9 groups of 6 female rats were used in an experiment using fraction 3 ofTrypanosoma rhodesiense. 500 g gave 100% immunoprotection and 1000 and 1500 g gave 66% immunoprotection when challenged with 5×10² T. brucei. 2 groups of 10 female rats were tested for a short period inoculation immune response. In this, 750 g of fraction 3 ofT. rhodesiense gave 70% immunoprotection when challenged withT. brucei.I thank the University of Zambia for support; Dr M. A. Q. Awan, Mazabuka, Zambia, forT. rhodesiense andT. brucei; Prof. J. W. Kibukamusoke, Dr O. Okong'o and Dr W. W. Anokbonggo for advice; Mr L. Nyaliti for technical help.     

Structural differences of cone ‘oil-droplets’ in the light and dark adapted retina ofPoecilia reticulata P.

Summary The vast majority of oil-droplets in the dark and light-adapted retinal twin-cones ofPoecilia reticulata is of the matrix-type. In bright light (day light+overhead strip light) there occurs in some regions a very pronounced numerical change from matrix to cristate-type, whereas other regions remain unaffected. The functional significance of these differences is discussed.