Lichens of soil crust communities in the Intermountain Area of the western United States

Lichens are common components of microbiotic soil crusts. A total of 34 species from 17 genera are reported from soil crust communities throughout the Intermountain Area. Distribution of terricolous lichens is determined by various physical and biological factors: physical and chemical characteristics of the soil, moisture regimes, temperature, insolation, and development and composition of the vascular plant community. Some species demonstrate a broad ecological amplitude while others have a more restricted distribution. All growth forms are represented; however, the vast majority of soil crust lichens are squamulose (minutely foliose). Fruticose species are least abundant. In exposed, middle-elevation sites vagrant (detached) species are common. This paper describes and discusses terricolous lichen communities of desert habitats of the intermountain western United States. Effects of various human-related activities including grazing, wildfire, air pollution, and recreation vehicles on soil crust lichens are discussed. Gypsoplaca macrophylla (Zahlbr.) Timdal, a rare squamulose lichen which occurs on gypsifersous soils, was recently collected in Emery County, Utah, and is reported as new to the state.     

An in vitro system for studying mucus secretion and other physiological activities in human intestinal mucosa

Zusammenfassung Bei der zystischen Pankreasfibrose ist eine abnorme Schleimabsonderung vorhanden. Bei der einfachen Rektummucosabiopsie sind keine sicheren Befunde zu erheben. Wichtige Veränderungen wurden jedoch an der Duodenalmucosa mit Hilfe einer Organzüchtungsmethode festgestellt.     

Photochemistry of riboflavin

Résumé Le spectre d'absorption, les caractéristiques luminescentes et photochimiques de la riboflavine sont présentés. L'interprétation des données expérimentales d'autres auteurs sur la décomposition photochimique de l'eau sensibilisée par la riboflavine est critiquée. Il faut distinguer deux cas: dans les réactions photochimiques qui ont lieu en l'absence de donneurs d'électrons ajoutés, la portion ribosique de la riboflavine se comporte en donneuse d'électrons et elle est détruité. Par contre, en présence de donneurs d'électrons adjoutés, la riboflavine agit comme véritable photosensibilisateur et n'est pas consumée dans l'ensemble de la réaction photochimique.     

Sur la biosynthèse des constituants amers des Simarubacées

Summary The biosynthesis of glaucarubinone (IXa) and glaucarubolone (IXb), the bitter constituents ofSimarouba glauca (Simaroubaceae), has been investigated with the help of [2-¹⁴C] mevalonic acid lactone. The results so far obtained are consistent with the scheme involving a tetracyclic triterpene of the apoeuphol type as a precursor of these bitter substances.

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Avec la collaboration technique de Mlle A.Merrien.     

Mechanisms of drug inhibition of signalling molecules

The emergence of tumour-specific, molecularly targeted agents signifies a paradigm shift in cancer therapy, with less reliance on drugs that non-discriminately kill tumour and host cells. Although the diversity of targets giving rise to this new generation of anticancer drugs has expanded, many challenges persist in the design of effective treatment regimens. The complex interplay of signal-transduction pathways further complicates the customization of cancer treatments to target single mechanisms. However, despite uncertainty over precise or dominant mechanisms of action, especially for compounds targeting multiple gene products, emerging agents are producing significant therapeutic advances against a broad range of human cancers.     

A novel self-promoted Morita-Baylis-Hillman-like dimerization

While stable in CH₂Cl₂, hexane or THF, in the presence of MeOH, self-promoted dimerization of the triarylphosphine-alkene 1, a ligand for Pd-catalyzed reactions, produced an unusual racemic bis(phosphine) 2 in high yield. The reaction of 2 with Pd(dba)₂, followed by oxidative addition of p-IC₆H₄NO₂, yielded a trans-chelated Pd(II) aryl iodide complex.     

Association scan of 14,500 nonsynonymous SNPs in four diseases identifies autoimmunity variants

We have genotyped 14,436 nonsynonymous SNPs (nsSNPs) and 897 major histocompatibility complex (MHC) tag SNPs from 1,000 independent cases of ankylosing spondylitis (AS), autoimmune thyroid disease (AITD), multiple sclerosis (MS) and breast cancer (BC). Comparing these data against a common control dataset derived from 1,500 randomly selected healthy British individuals, we report initial association and independent replication in a North American sample of two new loci related to ankylosing spondylitis, ARTS1 and IL23R, and confirmation of the previously reported association of AITD with TSHR and FCRL3. These findings, enabled in part by increased statistical power resulting from the expansion of the control reference group to include individuals from the other disease groups, highlight notable new possibilities for autoimmune regulation and suggest that IL23R may be a common susceptibility factor for the major 'seronegative' diseases.