Distribution des alcaloides dans le genre Lycopodium

The alkaloid content of Lycopodium saururus, L. carolinianum, L. cernuum, L. clavatum, L. issleri, L. sitchense, L. carolinum, L. contiguum and L. thyoïdes has been investigated. The results obtained and the distribution of the alkaloids in the genus are discussed from a chemotaxonomic point of view.     

Crassostrea gryphoides et C. gingensis (Schlotheim, 1813) deux expressions morphologiques d'une même espèce (Miocène, Bivalvia)

The assemblages of Crassostrea gryphoïdes of the Loupian's quarry is constitued of differents morphotypes which result of ecological effects (population density, locality and position in the assemblage). The selection of individuals with her life position shows two lots of Ostreidae the morphology of which is statistically different. The observations about Crassostrea of outcrops of Rhone's Valley and Touraine confirm the relations between position (liable to population's density) and morphology. The two types which are point out are often recognize as different species describe by E.F. von Schlotheim, 1813: Crassostrea gryphoïdes and Crassostrea gingensis. Therefore this two species must be consider as synonymous.     

Phenols bromes des algues rouges: Cyclotribromoveratrylene,nouveau derive obtenu au cours de l'extraction de Halopytis pinastroïdes

Cyclotribromoveratrylene has been isolated from an ethanolic extract of fresh Halopytis pinastroïdes, after treatment with diazomethane. This new     

Sterols of the amansieae (rhodomelaceae: Rhodophyta)

Osmundaria prolifera, kuetzingia natalensis, Halopythis pinastroïdes and Vidalia fimbriata contain C₂₇ sterols as the major sterols. Six other species of the Amansieae, belonging to the genera Amansia, Vidalia, Lenormandia and Rythiphlaea, contain C₂₈-sterols as the major sterols.     

Alcaloïdes de l' Isopyrum thalictroïdes—bases quaternaires des feuilles—isolement et identification de quatre pseudoprotoberberines

Besides the known magnoflorine, four new protoberberines were isolated from leaves of Isopyrum thalictroïdes. Their structures were deduced from spectral data. The names pseudoberberine, pseudocoptisine, pseudocolumbamine and dehydropseudocheilanthifoline are proposed for them.     

Alcaloïdes d'Alstonia vitiensis var. Novo ebudica monachino

Five alkaloids have been isolated from Alstonia vitiensis: pleïocarpamine, vincorine, cabucraline, alstovine (11-methoxycompactinervine) and quaternoxine; the latter two are new alkaloids.     

Value of the specific distinction between Ascaris lumbricoïdes linné 1758 and Ascaris suum Goeze 1782

Ansel M. and Thibaut M. 1973. Value of the specific distinction between Ascaris lumbricoïdes Linné 1758 and Ascaris suum Goeze 1782. International Journal for Parasitology3: 317–319. Study by scanning electron microscopy of heads of Ascaris lumbricoides Linné 1758 and Ascaris suum Goeze 1782 showed typical distinctive characteristics between these two species. There are differences in the appearance of the rows of denticules and the shapes of the lips.     

Alkaloids of Pterotaberna inconspicua

Sixteen alkaloids were isolated from the seeds and root-bark of Pterotaberna inconspicua, collected in Zaïre. They were voacangine 3-carbonitrile, voacangine, voacristine, 3,6-oxido-voacangine, vobasine, 10-hydroxycoronaridine, 10-hydroxyheyneanine, methuenine, apparicine, tubotaiwine, 16-epi-isositsirikine, 16-epimethuenine, 3,14-dihydroellipticine, an isomer of corynantheol, 16-epimethuenine N-oxide and tetra-hydroellipticine.     

Clostridium scindens: a human gut microbe with a high potential to convert glucocorticoids into androgens

Clostridium scindens American Type Culture Collection 35704 is capable of converting primary bile acids to toxic secondary bile acids, as well as converting glucocorticoids to androgens by side-chain cleavage. The molecular structure of the side-chain cleavage product of cortisol produced by C. scindens was determined to be 11β-hydroxyandrost-4-ene-3,17-dione (11β-OHA) by high-resolution mass spectrometry, ¹H and ¹³C NMR spectroscopy, and X-ray crystallography. Using RNA-Seq technology, we identified a cortisol-inducible (∼1,000-fold) operon (desABCD) encoding at least one enzyme involved in anaerobic side-chain cleavage. The desC gene was cloned, overexpressed, purified, and found to encode a 20α-hydroxysteroid dehydrogenase (HSDH). This operon also encodes a putative “transketolase” (desAB) hypothesized to have steroid-17,20-desmolase/oxidase activity, and a possible corticosteroid transporter (desD). RNA-Seq data suggests that the two-carbon side chain of glucocorticords may feed into the pentose-phosphate pathway and are used as a carbon source. The 20α-HSDH is hypothesized to function as a metabolic “rheostat” controlling rates of side-chain cleavage. Phylogenetic analysis suggests this operon is rare in nature and the desC gene evolved from a gene encoding threonine dehydrogenase. The physiological effect of 11β-OHAD on the host or other gut microbes is currently unknown.     

Grantianine and grantaline,alkaloids of Crotalaria virgulata subsp. Grantiana

Characterization data are presented for grantianine and grantaline, alkaloids of Crotalaria virgulata subsp. grantiana. The plant growing in Australia also contains 1-hydroxymethyl-1β,2β-epoxy-8αH-pyrrolizidine.     

Loss of Gibberellin Production in Fusarium verticillioides (Gibberella fujikuroi MP-A) Is Due to a Deletion in the Gibberellic Acid Gene Cluster

Fusarium verticillioides (Gibberella fujikuroi mating population A [MP-A]) is a widespread pathogen on maize and is well-known for producing fumonisins, mycotoxins that cause severe disease in animals and humans. The species is a member of the Gibberella fujikuroi species complex, which consists of at least 11 different biological species, termed MP-A to -K. All members of this species complex are known to produce a variety of secondary metabolites. The production of gibberellins (GAs), a group of diterpenoid plant hormones, is mainly restricted to Fusarium fujikuroi (G. fujikuroi MP-C) and Fusarium konzum (MP-I), although most members of the G. fujikuroi species complex contain the GA biosynthesis gene cluster or parts of it. In this work, we show that the inability to produce GAs in F. verticillioides (MP-A) is due to the loss of a majority of the GA gene cluster as found in F. fujikuroi. The remaining part of the cluster consists of the full-length F. verticillioides des gene (Fvdes), encoding the GA₄ desaturase, and the coding region of FvP450-4, encoding the ent-kaurene oxidase. Both genes share a high degree of sequence identity with the corresponding genes of F. fujikuroi. The GA production capacity of F. verticillioides was restored by transforming a cosmid with the entire GA gene cluster from F. fujikuroi, indicating the existence of an active regulation system in F. verticillioides. Furthermore, the GA₄ desaturase gene des from F. verticillioides encodes an active enzyme which was able to restore the GA production in a corresponding des deletion mutant of F. fujikuroi.     

Impacts of water stress removal and disturbance regimes on Mediterranean dry grasslands diversity and succession

Our goal was to disentangle the effects of stress removal and disturbance on plant communities of a Mediterranean rangeland, La Crau (southeastern France). We compared undisturbed reference steppe vegetation with vegetation impacted by changes in land use such as earlier phases of cultivation (dating back 20 years) and/or current water infiltrations (revealed by the presence of Brachypodium ph?nicoïdes), since the establishment of adjacent hay meadows. We considered plots with and without brambles (Rubus ulmifolius), an indigenous shrub species that had colonized the area after the land-use changes. We monitored the composition and measured the taxonomic richness and richness of functional groups, evenness and similarities of plant communities. The species richness of the undisturbed community was significantly higher than that of all disturbed plant communities. Although cultivation led to the dominance of ruderal species, the removal of water stress had a stronger negative impact, enabling the establishment of herbaceous competitor species such as B. ph?nicoïdes. The dominance of this species resulted in a significant decline in species richness and evenness after water stress removal. The presence of brambles correlating with former cultivation and/or current water infiltration did not have a significant impact on plant species richness in the vicinity of bramble bushes, although it significantly modified the composition of the adjacent herbaceous vegetation. Our study highlights again the low resilience of Mediterranean dry grasslands after disturbance. While both the disturbance and the water stress removal resulted in changes within the plant community, our findings reveal a stronger impact of the water stress removal. Water infiltration led to decreased plant species richness and evenness because the greater availability of water favored competitor species over the stress-tolerant xeric species. Therefore, for restoring the original steppe species richness, the priority will be to control water infiltrations, even before any scrub-clearing is undertaken to control bramble colonization.     

Seasonal variation in the secondary chemistry of foliar and reproductive tissues of Delphinium nuttallianum

Plant secondary compounds are critical in affecting interactions between plants and their herbivores. The norditerpene alkaloids are secondary compounds in Delphinium (larkspur) species which are divided into two classes: the N-(methylsuccinimido) anthranoyllycoctonine (MSAL-type) and non MSAL-type, and are known to be toxic to herbivorous insects and livestock. Alkaloid concentrations were measured in a whole plant context in vegetative and reproductive tissues in Delphinium nuttallianum at different stages of plant maturity at two locations to explore how plant maturity affected alkaloid concentrations within a growing season. Alkaloid concentrations differed between vegetative and reproductive tissues, with vegetative tissues having significantly lower alkaloid concentrations than reproductive tissues. However, no systematic differences in alkaloid concentrations were observed at different plant maturity stages across the growing season. Based on the data we suggest that alkaloid allocation in different plant parts of D. nuttallianum is influenced by life history of the plant, consistent with plant defense theory. At one location, as pods mature the qualitative alkaloid composition changed through structural diversification of the alkaloids present. The ecological significance of this structural diversification awaits further exploration.     

Determinants of growth rate on chemically heterogeneous host plants by specialist insects

Nine Passiflora species growing sympatrically in a Costa Rican rain forest were screened for the presence of alkaloids, tannins, cyanogenic compounds, saponins and cardenolides. The first three chemical classes were found to be present and the Passiflora species could be classified into five groups according to the presence/absence of each chemical class. In order to assess the effects of this chemical variability on specialist herbivores, larvae of Heliconius ismenius and H. melpomane were experimentally introduced to seven species of Passiflora host plants growing naturally in the rain forest. Survival and growth rates were subsequently monitored at 2 day intervals and were found to be independent of each other. Larval growth rate and larval survivorship were not significantly affected by cyanogenesis in the host plants, nor by the presence of alkaloids, tannins and non-tanning phenolic compounds. Larval growth rate was found to be correlated to percentage nitrogen in the host plants, but was independent of host water content and non-structural carbohydrate content. Although these insects would be classified as host-specific by most authors, the results indicate the presence of a sufficiently general detoxication apparatus to consume many different classes of potential toxins with no apparent ill effects. We conclude that Passiflora natural product diversity does not cause major deleterious effects in Heliconius growth characteristics and that these effects are not the major component maintaining the current pattern of larval feeding specialization in this plant-herbivore system.     

Identification of Highly Attenuated Mutants of Simian Immunodeficiency Virus

Deletion mutants of the pathogenic clone of simian immunodeficiency virus isolate 239 (SIVmac239) were derived that are missing nef, vpr, and upstream sequences (US) in the U3 region of the LTR (SIVmac239Δ3), nef, vpx, and US (SIVmac239Δ3x), and nef, vpr, vpx, and US (SIVmac239Δ4). These multiply deleted derivatives replicated well in the continuously growing CEMx174 cell line and were infectious for rhesus monkeys. However, on the basis of virus load measurements, strength of antibody responses, and lack of disease progression, these mutants were highly attenuated. Measurements of cell-associated viral load agreed well with assays of plasma viral RNA load and with the strengths of the antibody responses; thus, these measurements likely reflected the extent of viral replication in vivo. A derivative of SIVmac239 lacking vif sequences (SIVmac239Δvif) could be consistently grown only in a vif-complementing cell line. This Δvif virus appeared to be very weakly infectious for rhesus monkeys on the basis of sensitive antibody tests only. The weak antibody responses elicited by SIVmac239Δvif were apparently in response to low levels of replicating virus since they were not elicited by heat-inactivated virus and the anti-SIV antibody responses persisted for greater than 1 year. These results, and the results of previous studies, allow a rank ordering of the relative virulence of nine mutant strains of SIVmac according to the following order: Δvpr > Δvpx > ΔvprΔvpx Δnef > Δ3 > Δ3x ≥ Δ4 > Δvif > Δ5. The results also demonstrate that almost any desired level of attenuation can be achieved, ranging from still pathogenic in a significant proportion of animals (Δvpr and Δvpx) to not detectably infectious (Δ5), simply by varying the number and location of deletions in these five loci.     

Epidermis is a pivotal site of at least four secondary metabolic pathways in Catharanthus roseus aerial organs

Catharanthus roseus produces a wide range of secondary metabolites, some of which present high therapeutic values such as antitumoral monoterpenoid indole alkaloids (MIAs), vinblastine and vincristine, and the hypotensive MIA, ajmalicine. We have recently shown that a complex multicellular organisation of the MIA biosynthetic pathway occurred in C. roseus aerial organs. In particular, the final steps of both the secoiridoid–monoterpene and indole pathways specifically occurred in the epidermis of leaves and petals. Chorismate is the common precursor of indole and phenylpropanoid pathways. In an attempt to better map the spatio-temporal organisation of diverse secondary metabolisms in Catharanthus roseus aerial organs, we studied the expression pattern of genes encoding enzymes of the phenylpropanoid pathway (phenylalanine ammonia-lyase [PAL, E.C. 4.3.1.5], cinnamate 4-hydroxylase [C4H, E.C. 1.14.13.11] and chalcone synthase [CHS, E.C. 2.3.1.74]). In situ hybridisation experiments revealed that CrPAL and CrC4H were specifically localised to lignifying xylem, whereas CrPAL, CrC4H and CrCHS were specifically expressed in the flavonoid-rich upper epidermis. Interestingly, these three genes were co-expressed in the epidermis (at least the upper, adaxial one) together with three MIA-related genes, indicating that single epidermis cells were capable of concomitantly producing a wide range of diverse secondary metabolites (e.g. flavonoïds, indoles, secoiridoid–monoterpenes and MIAs). These results, and data showing co-accumulation of flavonoids and alkaloids in single cells of C. roseus cell lines, indicated the spatio-temporal feasibility of putative common regulation mechanisms for the expression of these genes involved in at least four distinct secondary metabolisms.     

Composition and stereochemistry of ephedrine alkaloids accumulation in Ephedra sinica Stapf

Ephedra sinica Stapf (Ephedraceae) is a widely used Chinese medicinal plant (Chinese name: Ma Huang). The main active constituents of E. sinica are the unique and taxonomically restricted adrenergic agonists phenylpropylamino alkaloids, also known as ephedrine alkaloids: (1R,2S)-norephedrine (1S,2S)-norpseudoephedrine, (1R,2S)-ephedrine, (1S,2S)-pseudoephedrine, (1R,2S)-N-methylephedrine and (1S,2S)-N-methylpseudoephedrine. GC–MS analysis of freshly picked young E. sinica stems enabled the detection of 1-phenylpropane-1,2-dione and (S)-cathinone, the first two putative committed biosynthetic precursors to the ephedrine alkaloids. These metabolites are only present in young E. sinica stems and not in mature stems or roots. The related Ephedra foemina and Ephedra foliata also lack ephedrine alkaloids and their metabolic precursors in their aerial parts. A marked diversity in the ephedrine alkaloids content and stereochemical composition in 16 different E. sinica accessions growing under the same environmental conditions was revealed, indicating genetic control of these traits. The accessions can be classified into two groups according to the stereochemistry of the products accumulated: a group that displayed only 1R stereoisomers, and a group that displayed both 1S and 1R stereoisomers. (S)-cathinone reductase activities were detected in E. sinica stems capable of reducing (S)-cathinone to (1R,2S)-norephedrine and (1S,2S)-norpseudoephedrine in the presence of NADH. The proportion of the diastereoisomers formed varied according to the accession tested. A (1R,2S)-norephedrine N-methyltransferase capable of converting (1R,2S)-norephedrine to (1R,2S)-ephedrine in the presence of S-adenosylmethionine (SAM) was also detected in E. sinica stems. Our studies further support the notion that 1-phenylpropane-1,2-dione and (S)-cathinone are biosynthetic precursors of the ephedrine alkaloids in E. sinica stems and that the activity of (S)-cathinone reductases directs and determines the stereochemical branching of the pathway. Further methylations are likely due to N-methyltransferase activities.