Turnover des flavonols dans les tuniques d'Allium cepa en survie

During ageing of isolated onion scales there is an accumulation of flavonols which increase continuously. This is not light-dependent but is associated with a high level of respiratory gaseous exchanges. Phenylalanine-[U-¹⁴C] is actively incorporated in these flavonols but experiments of pulse labelling show that they have either a very slow or no turnover. This suggests that enzymes able to destroy flavonols are lacking in this material.     

ATPase membranaire de vacuoles lysosomales: Les lutoides du latex d'Hevea brasiliensis

Membranes of the lutoids present in the latex of Hevea brasiliensis possess an ATPase which is separable from adsorbed residual acid phosphatase. The pH optimum of the ATPase is 7.75 in Tris—HCl and is displaced to 6.5 in K-phosphate buffer. A divalent cation is obligatory (Mg  Mn > Ca). ATP-Mg is the natural substrate of the enzyme. Monovalent cations have practically no action on the enzyme. It is, however, activated by anions, both inorganic (Cl^?, HCO₃^?) and organic (malate, aspartate, tartrate). The enzyme has a higher specificity for ATP than for GTP, CTP or UTP and is non-competitively inhibited by ADP. The enzyme is temperature sensitive and a break in the Arrhenius plot occurs at about 20°, characteristic of membrane-bound enzymes. SH-group poisons inhibit enzyme activity as do classical uncouplers at high concentrations (about 10^?3 M). A hypothesis is formulated whereby the membrane-bound lutoid ATPase functions as a proton pump in order to maintain the acid pH of a vacuolar and lysosomal compartment.     

Alcaloides d'Araliopsis soyauxii. Isolement d'un nouvel alcaloide,l'Araliopsine

Six alkaloids have been isolated from root bark of Araliopsis soyauxii. Five are known, maculine, flindersiamine, skimmianine, (?) ribalinine, (+) isoplatydesmine and the sixth, araliopsine is new; its structure has been established as hydroxyisopropyldihydrofuro-2-quinolone. From the trunk bark four alkaloids have been isolated: flindersiamine, kokusaginine (?) ribalinine, (+) isoplatydesmine.     

Alcaloïdes d'Alstonia quaternata

Eleven alkaloids have been isolated from Alstonia quaternata. Three of them, namely 11-methoxy-epi-3α-yohimbine, 10,11-dimethoxy-picrinine designated quaternine, and 19,20-epoxy-N_(a)-methyl, desacetyl, desformo, 2βH-dihydroakuammiline designated quaternoxine, are new alkaloids.     

Acide nor-19 anticopalique d'Agathis lanceolata

A new diterpenoid, 19-noranticopalic acid, has been isolated from Agathis lanceolata resin. Its structure has been established by spectroscopic methods and chemical correlations with anticopalic acid.     

Les sterols de l'Ascomycete Leptosphaeria typhae

A mixture of C₂₈ and C₂₉ sterols have been isolated from Leptosphaeria typhae grown in vitro on “oat water” and characterized by GLC and MS. Mono-, di- and tri-unsaturated sterols are present in the extracts of fungi cultivated both in the dark and in the light but the sterol composition is different. The influence of “oat water” on sterol structure has been determined by comparison with the sterols of the same fungus grown on synthetic medium in the dark.     

Incorporation de phenylalanine,de glucose et d'acide cinnamique dans les flavonols de l'oignon

In Allium cepa bulb scales, incorporation of ¹⁴C-phenylalanine, cinnamic acid and glucose were studied in relation to flavonol synthesis. The best incorporation into flavonols is obtained with either cinnamic acid or phenylalanine. ¹⁴C-glucose gives a slow incorporation into flavonol aglycone; this is because there is a big pool of free glucose in the scales in which the precursor is diluted. Under certain conditions, free cinnamic acid is quickly incorporated in a complex which may be a glycoside. After short labelling experiments with phenylalanine or cinnamic acid, some free precursor can be found in the scales a few days later but it is not available for flavonol synthesis. In these conditions, flavonol analysis shows in some cases, no turnover and in others, a turnover of 10% per day due to catabolism.     

Polyacetyleniques en C17 des racines d'Heracleum mantegazzianum

Heracleum mantegazzianum roots were examined for polyacetylenes. The structures of two compounds, n-cis-heptadecene-(9)-diyne-(4,6)-ol-(8) and n-trans-cis-heptadecadiene-(2,9)-diyne-(4,6)-ol-(8) are definitively established.     

Phenylpolyenes d'Aspergillus niger: structure et proprietes de l'asperrubrol

When grown on a synthetic medium containing Zn²⁺ and Cd²⁺ in toxic concentrations and a high concentration of Mg²⁺, the mycelium of Aspergillus niger ATCC 9029 is pigmented yellow. Four pigments have been chromatographically separated. Two are still unknown; the others are asperenone and asperrubrol. Asperrubrol is the methyl ester of a dimethyl 13-phenyl-3-ol-2,4,6,8,10,12-tridecahexaenoic acid. One of the methyl groups is on C₂ and the other is probably at C₈. Asperrubrol has been obtained as the enol of the all trans molecule; ketoe nolisation can be obtained by action of heat or alkalis. When grown on the same medium, 13 of 17 strains of A. niger produced asperrubrol and asperenone.     

Grandifloroside et methylgrandifloroside,glucosides iridoides nouveaux d'Anthocleista grandiflora

From the bark of Anthocleista grandiflora, two new iridoïd glucosides were isolated, and their structures established.     

Caractéristiques de l'incorporation d'acides aminés par les polysomes isolés du latex d'Hevea brasiliensis

Amino acid incorporation by latex polysomes needs the presence of cofactors (K⁺, Mg²⁺), cytoplasmic serum and GTP. It is abolished by RNase but not by chloramphenicol. Poly U increases the incorporation rate.     

Les métapodes d'Equus sensu lato (Mammalia,Périssodactyla)

Biometrical study of the metapodials of modern wild species (E. grevyi, E. burchelli boehmi, E. zebra hartmannae, E. africanus, E. hemionus and E. przewalskii) and some fossil forms (E. stenonis vireti and cf. vireti from the Villafranchian of France and Spain; E. tabeti and E. mauritanicus from the Lower and Middle Pleistocene of Northern Africa; E. mosbachensis from the Middle Pleistocene of Germany). Classical functional and evolutive interpretations of some characters are discussed: development of the distal keel, of the distal supra-articular and articular widths, of the proximal widths and antero-posterior diameters.     

Les flavonoides du Dryas octopetala

Two proanthocyanidins and seven flavonoids are present in the leaves of Dryas octopetala. They have been identified as procyanidin, propelargonidin, quercetin, kaempferol, isorhamnetin, corniculatusin, sexangularetin, limocitrin and gossypetin. Plant samples from both French and Norwegian sites were identical in their flavonoid composition.     

Cinetique d'action de l'acide 2-chloro ethylphosphonique sur les polyribosomes du latex d'Hevea brasiliensis

Effects of 2-chloroethylphosphonic acid on the latex of Hevea brasiliensis were studied during 7 days after its application on the tapping panel of the tree. Ribosome polymerisation shows a dramatic rise within 12 hr after treatment. This shift is overcome at first without rRNA synthesis. Increase of latex production and latex pH exhibit similar features and start 24 hr after application of the, stimulant. After 4 days, rRNA concentration and the stability of the lutoïds (microvacuoles with lysosomal characteristics) change significantly.     

Origine et caracteres de la sécrétion d'aglycones flavonoliques par les bourgeons d'Aesculus hippocastanum

Flavonol aglycones are present in the oil excreted by buds of Aesculus hippocastanuml. and are probably synthesized in glandular hairs situated on the inner side of bud scales. Flavonols are most abundant in the hairs, being much less concentrated in all other scale tissues. Flavonol accumulation in the buds reaches a maximum both in the Spring and the Autumn and this is related to the accumulation of leaf flavonols and leucoanthocyanes and of scale and bark coumarins.     

Les flavonoides des tiges principales de Periploca graeca cultive en conditions uniformes

The level of flavonoids does not change significantly when the main stem of plants cultivated in a controlled environment change from the short upright type to the twining type, but the quantity of cafeic acids derivatives is greater. The flavonoid content changes with temperature and light, with no correlation between the variation in elongation rate and stem type. Nevertheless, stems maintained in the short upright stage at a temperature of 15° are richer in derivatives of esculetin, ferulic acid and p-coumaric acid. The flavonoid content of these short upright main stems resemble that of short upright lateral stems grown under natural conditions. In the controlled environment, the axillary buds of the main stem give rise to short upright lateral stems and twining lateral stems which possess the same flavonoids as lateral stems under natural conditions. There is no evidence of any relationship between the stem type and the flavonol content and this group of compounds are not responsible for circumnutation in Periploca graeca.     

Action in vivo d'ecdysones sur la morphogénèse imaginale d'Aeshna cyanea (Odonata)

Single amounts of α or β ecdysone were injected during the last larval instar of Aeshna cyanea at various times after ecdysis. In these experimental conditions, α and β ecdysone had similar effects. Very large amounts of brown or black cuticle appeared on the tarsal claws soon after hormone injection, so that the cuticular synthesis of the larvae which were injected at the beginning of the last stage appears about two or three times more quickly than in controls. Nearly all the larval characters were exhibited by animals injected on the day of or the day after the last larval ecdysis. If the hormonal injection was further delayed, only adultoid forms were obtained. No perfect adults appeared. The effects evoked by α or β ecdysone may be different from one organ to another.On the other hand, some results were different according to the type of ecdysone. Darkening of the tarsal claws (and perhaps sclerotization) appears sooner when β ecdysone is supplied. The morphology of the external organs which degenerate during metamorphosis is not always the same after injection of equal amounts of α or β ecdysone at the same time. The regression of the larval organs seems to be more explicit and appears sooner when β ecdysone was administrated. The morphogenesis of the organs which grow during metamorphosis was either weaker or non-existent with β ecdysone.These results are discussed with regard to previous work.     

Biosynthese des ramifications en C-24 des phytosterols de Physarum polycephalum et d'Ochromonas danica

The side chain C-24 alkylation mechanism of phytosterols of Physarum polycephalum and Ochromonas danica, cultured in a nutrient medium containing methionine-CD₃, has been studied. Depending on species, five or four deuterium atoms were incorporated respectively in C-24 ethyl phytosterols. No relation could be established between the stereochemistry of C-24 and the alkylation mechanism at this position.