Triterpenes of toxic and non-toxic taxa of Lantana camara.

The taxa of Lantana camara toxic to animals contain lantadene A lantadene B, whereas in two non-toxic taxa other triterpenes predominate. Several new triterpenes have been characterized. Contrary to earlier claims, lantadene A and to a lesser extent lantadene B are toxic when administered intraruminally to sheep.     

Triterpènes XVI1. Fréquence et site d'oxygénation des triterpènes naturels

Summary Comparison of the known tetracyclic and-amyrenic triterpenes shows that natural oxygenation of the skeleton occurs preferentially at certain carbon atoms that are biogenetically equivalent in the 2 series.     

Isolation of the two paragonial substances deposited into the spermatophores ofAcanthoscelides obtectus (Coleoptera,Bruchidae)

Summary Aqueous extracts from spermatophores ofAcanthoscelides obtectus (Coleoptera, Bruchidae) have been chromatographed on Sephadex G 25 and G 15 columns, the active fractions being further purified by preparative SiO₂ TLC. The isolation and properties of 2 biologically active compounds are reported. The paragonial substance A has a favourable action upon oogenesis, is a low molecular weight molecule (500–1000) and gives 1 single amino acid on hydrolysis, corresponding to glycin on TLC. The paragonial substance B is toxic, or an inhibitor of oogenesis at lower concentration, thus showing an antagonistic effect.     

Systematics and evolution of holarctic Pierinae (Lepidoptera). An enzyme electrophoretic approach

Summary Enzyme electrophoretic data show a remarkably high degree of genetic similarity within the European group ofnapi s.l. whereas genetic differences exist at several loci between the European and the North American taxa ofnapi s.l. It is concluded that the European taxa did not differentiate to the species level and form a phylogenetically young group. The North American taxa included in this study are specifically distinct from Europeannapi and separated much earlier. Within these North American taxamarginalis, oleracea andvirginiensis did undergo speciation. The data show a splitting of the genusPieris into three species groups, each genetically differentiated to the same level. The splitting ofPieris into two genera, as suggested by earlier investigators, is not supported here.     

Essais de solubilisation et de détoxification de la Tyrothricine

Summary As Tyrothricin —Dubos's discovery of the antibiotic agent extracted from cultures ofB. brevis — does not give true aqueous solutions and retains, in the colloïdal state of the usually employed solutions, toxic properties for polymorphonuclear blood cells, we have attempted to effect the solubilization and detoxification of this compound. Treatment with formalin in given proportions results in making it water-soluble. The action of the formalin-treated compound on blood cells suspended in Ringer's solution seems to show a loss of toxicity. Subcutaneous and intramuscular injections in mice do not give visible general toxic effects, and the experiments incite to further investigations in this direction.     

Toxicity of Temik (aldicarb) for a fresh water teleost,Barbus conchonius Hamilton

Summary The toxic effects of Temik (aldicarb) on a fresh water Himalyan lake teleost,Barbus conchonius were investigated in hard and soft water. The 48-, 72- and 96-h TL_m-values in mg/l were 8.99, 2.39 and 2.42 respectively in the hard-water test and 3.30, 0.62 and 0.46 in the soft-water test. The toxicity of Temik toB. conchonius increases many fold in soft water.One of us (S. C. P.) is grateful to U. G. C., for the award of a senior research fellowship.     

Production de nidulotoxine par desAspergillus appartenant à différentes espèces

Summary Strains ofA. versicolor Tiraboshi andA. Sydowi Thorn and Church produce a toxic metabolite spectrographically identical with the nidulotoxin.     

Effect of the extracts fromAristolochia indica Linn. on interception in female mice

Summary The crude petroleum ether, chloroform and alcoholic extracts of the roots ofAristolochia indica (Linn.) showed 100% interceptive activity in mature female mice at the single dose of 100 mg/kg body wt. The follow-up studies with the chloroform extract showed the most significant effect in the basic part and two acidic fractions at the single dose levels of 50 mg/kg body wt. No toxic effect was observed at the dose levels used.The authors are thankful to Mr.P. P. Ghosh Dastidar, Medicinal Chemistry Division for the plant extracts. Thanks are also due to Indian Council of Medical Research and Council of Scientific and Industrial Research for granting scholarships to two of them (B.C. and A.D.) and to Prof.R. N. Chakravarti, Director of the Institute for encouragement.     

Bacterial nonspecific acid phosphohydrolases: physiology, evolution and use as tools in microbial biotechnology

Bacterial nonspecific acid phosphohydrolases (NSAPs) are secreted enzymes, produced as soluble periplasmic proteins or as membrane-bound lipoproteins, that are usually able to dephosphorylate a broad array of structurally unrelated substrates and exhibit optimal catalytic activity at acidic to neutral pH values. Bacterial NSAPs are monomeric or oligomeric proteins containing polypeptide components with an M _r of 25 – 30 kDa. On the basis of amino acid sequence relatedness, three different molecular families of NSAPs can be distinguished, indicated as molecular class A, B and C, respectively. Members of each class share some common biophysical and functional features, but may also exhibit functional differences. NSAPs have been detected in several microbial taxa, and enzymes of different classes can be produced by the same bacterial species. Structural and phyletic relationships exist among the various bacterial NSAPs and some other bacterial and eucaryotic phosphohydrolases. Current knowledge on bacterial NSAPs is reviewed, together with analytical tools that may be useful for their characterization. An overview is also presented concerning the use of bacterial NSAPs in biotechnology. Received 21 November 1997; received after revision 10 March 1998; accepted 10 March 1998     

Ethanol metabolism inDrosophila melanogaster

Summary A quantitative study of the transformation of ethanol into acetaldehyde shows that, inDrosophila melanogaster, the mitochondrial ethanol oxidizing system is not very active but that the part played by catalase appears more important than expected. For a strain without alcoholdehydrogenase, ethanol is highly toxic. The presence of acetaldehyde in the culture medium is toxic for all the strains studied. But, since even a strain without any aldehydeoxidase lives normally, the metabolic production of acetaldehyde does not seem dangerous.     

Resistance to ethidium bromide inAspergillus nidulans

Summary A mutant ofAspergillus nidulans resistant to ethidium bromide was isolated and the semi-dominant gene responsible for this resistance was allocated on linkage group II at 17.42±3.05 units of recombination from thewA₃ gene. The gene also confers cross-resistance to acriflavin, malachite green and crystal violet. It was also shown that riboflavin is antagonistic to the toxic effect of ethidium bromide, at certain concentrations. The mechanisms which could be responsible for the toxic effect of this drug are discussed and compared with those of acriflavin. The use of theEtb ₁ gene in genetical analysis through the parasexual cycle is suggested.Acknowledgements. The authors are thankful to the National Council for the Development of Science and Technology (CNPq) for financial support through PIG-SIP 04/053 FAPESP.     

Flavonol glycosides and seed coat structure in certain species ofEpilobium — A correlation?

Summary In a survey of 239 populations ofEpilobium representing 17 taxa the following flavonol glycosides were found: myricetin 3-O-arabinoside; 3-O-glucoside; 3-O-rhamnoside; quercetin 3-O-arabinoside; 3-O-glucoside; 3-O-diglucoside; 3-O-rhamnoside; kaempferol 3-O-glucoside; and 3-O-rhamnoside. A correlation appears to exist between seed coat sculpturing as determined in a previous study using SEM techniques, and the flavonoid profiles.Acknowledgments. This study was supported in part by NSERC of Canada and The Boreal Institute for Northern Studies.     

Novel cytotoxic peptides from the tropical marine cyanobacteriumHormothamnion enteromorphoides 1. Discovery,isolation and initial chemical and biological characterization of the hormothamnins from wild and cultured material

A Caribbean cyanobacterium,Hormothamnion enteromorphoides, was found to produce a complex mixture of ichthyotoxic peptides, perhaps explaining the apparent absence of predation upon these potentially palatable life forms. Bioassay-guided fractionation was used to isolate these toxic and antimicrobial natural products, and a variety of techniques including HR FAB mass spectrometry, 2D-NMR, traditional hydrolysis-amino acid analysis, and several chemical reactions were used to define the basic structural features of the major peptide, hormothamnin A. Hormothamnin A is a cyclic undecapeptide containing six common and five uncommon or new amino acid residues. HPLC analyses indicate that the relative proportions of these peptide natural products remain relatively constant between different collection locations and years, however, they do vary seasonally. Clonal isolates of this cyanobacterium in culture produce the full spectrum of toxic peptides.     

Zur Biogenese pentazyklischer Triterpene in einer höheren Pflanze

Summary The biosynthesis of pentacyclic triterpenes has been followed in germinating soja-beans with the aid of isotopic tracers.     

Chemical subdivisions within the genusArctostaphylos based on flavanoid profiles

Summary The flavonoid glycosides from 227 populations representing 20 species ofArctostaphylos have been identified. Certain glycosides are of values in subdividing the genus into discreet chemically related groups. A single linkage computer analysis shows the existance of subdivisions based both on oxidation levels of the flavonoids as well as glycoside variation. The ability to form 7-O-glycosides appears to be restricted and could be of future value in the identification of hybrids between those taxa capable of 7-O-glycoside synthesis and those unable to do so.Supported by the National Sciences and Engineering Research Council of Canada.     

Pharmacological studies on a plant lectin,Aloctin A. I. Growth inhibition of mouse methylcholanthrene-induced fibrosarcoma (Meth A) in ascites form by Aloctin A

Summary A glycoprotein isolated fromAloe arborescens Mill markedly inhibited the growth of a syngeneic transplantable fibrosarcoma of mice, Meth A, in ascites form. There is evidence that the inhibition mechanism is host-mediated and not a direct toxic effect on the tumor cell.Acknowledgment. We thank Miss M. Hayama for her technical help.To whom all correspondence should be addressed.     

Muscleblind participates in RNA toxicity of expanded CAG and CUG repeats in <Emphasis Type="Italic">Caenorhabditis elegans</Emphasis>

We have utilized Caenorhabditis elegans as a model to investigate the toxicity and underlying mechanism of untranslated CAG repeats in comparison to CUG repeats. Our results indicate that CAG repeats can be toxic at the RNA level in a length-dependent manner, similar to that of CUG repeats. Both CAG and CUG repeats of toxic length form nuclear foci and co-localize with C. elegans muscleblind (CeMBL), implying that CeMBL may play a role in repeat RNA toxicity. Consistently, the phenotypes of worms expressing toxic CAG and CUG repeats, including shortened life span and reduced motility rate, were partially reversed by CeMbl over-expression. These results provide the first experimental evidence to show that the RNA toxicity induced by expanded CAG and CUG repeats can be mediated, at least in part, through the functional alteration of muscleblind in worms.     

Antibiotika als pflanzliche Plasmagifte

Summary The toxic action oflycomarasmine (a wilting agent produced byFusarium lycopersici Sacc., the causal organism of tomato-wilting) and ofpatulin (clavacin, an antibiotic produced byPenicillium patulum and by some other fungi) on some test-objects is studied (anthocyanin-test with red turnips, plasma-streaming test withSpirogyra etc.). Both substances are able to destroy for instance the semipermeability of the plasma boundary layer; but patulin proves to be more toxic for these objects than lycomarasmine, the specific poison of the tomato wilting disease.     

A convenient thin layer chromatographic method for the detection of cyclochlorotine and simatoxin,toxins fromPenicillium islandicum Sopp

Summary A rapid, convenient TLC method is described for detection of cyclochlorotine, a carcinogen produced by the commonly found storage moldPenicillium islandicum Sopp. This method has also led to the isolation of a new toxic metabolite, simatoxin.Acknowledgment. This work was supported by Food and Drug Administration, Washington, D.C. (Contract No. FDA-223-74-2209).     

A pesticide-resistant mutant of the N2-fixing blue-green algaNostoc muscorum

Summary The fungicide dithane Z-78 (zinc ethylene bisdithiocarbamate) has been found to be an inhibitor of growth and heterocyst differentiation inNostoc muscorum. Its inhibitory effect has been reversed by exogenous glucose. A spontaneous mutant resitant to a toxic concentration of the fungicide grows in the presence of dithane at a dose normally applied in fields and does not require an exogenous carbon source for its growth.Thanks are due to Council of Scientific and Industrial Research, Govt. of India, New Delhi-110001, for providing financial assistance to A.V. in the form of a Post-Doctoral Research Fellowship.