O-Heterocyclic Embeurekols from Embellisia eureka,an Endophyte of Cladanthus arabicus

Three new polyketides (-)-1 , (+)-1 , and 2 ) were isolated from the EtOAc extract of the fungus Embellisia eureka, an endophyte of the Moroccan plant Cladanthus arabicus (Asteraceae). The structures of these new compounds were determined on the basis of one- and two-dimensional NMR spectroscopy as well as by high-resolution mass spectrometry. The absolute configurations of (-)-1 , (+)-1 , and 2 were determined by TDDFT ECD calculations of solution conformers, online HPLC-ECD analysis, and the modified Mosher method. Chirality 25:250–256, 2013. © 2013 Wiley Periodicals, Inc.     

Jewish children under the camera: An ethnographic study of Jewish children in Britain

This article seeks to explore the use of photography as a tool for ethnographic research, having regard to the nature of participant observation as the primary method involved. A study of Jewish children in the center of England highlights a range of creative possibilities for the use of photography. An examination of the Jewish tradition reinforces the need for depth of understanding if one is to forge a truly empathetic relationship that links subject and object in photographic exploration.     

Understanding the genetic basis of invasiveness

Invasive species provide excellent study systems to evaluate the ecological and evolutionary processes that contribute to the colonization of novel environments. While the ecological processes that contribute to the successful establishment of invasive plants have been studied in detail, investigation of the evolutionary processes involved in successful invasions has only recently received attention. In particular, studies investigating the genomic and gene expression differences between native and introduced populations of invasive species are just beginning and are required if we are to understand how plants become invasive. In the current issue of Molecular Ecology, Hodgins et al. ( 2013 ) tackle this unresolved question, by examining gene expression differences between native and introduced populations of annual ragweed, Ambrosia artemisiifolia. The study identifies a number of potential candidate genes based on gene expression differences that may be responsible for the success of annual ragweed in its introduced range. Furthermore, genes involved in stress response are over‐represented in the differentially expressed gene set. Future experiments could use functional studies to test whether changes in gene expression at these candidate genes do in fact underlie changes in growth characteristics and reproductive output observed in this and other invasive species.     

Compartmentalized Calcium Signaling in Cilia Regulates Intraflagellar Transport

1. Download : Download high-res image (204KB)
2. Download : Download full-size image

     

Phylogenetic implications and diagenetic stability of macromolecules from pleistocene and recent shells of Mercenaria mercenaria (mollusca,bivalvia)

The phylogeny and diagenesis of Pleistocene and Recent bivalves were studied immunologically by use of a conventional antiserum elicited against an EDTA‐soluble macromolecular extract from shells of the modern bivalve mollusc Mercenaria mercenaria. ELISA tests of the antiserum with shell fragments of a wide range of modern bivalves gave taxonomically significant results. The antiserum reacted with palaeoheterodonts and heterodonts but not with representatives of other bivalve subclasses. This phylogenetic reactivity was also apparent in tests with fossil shells, although the specificity and overall strength of the reaction were both reduced. Absorption of the antiserum with etched shell powders of various (palaeo)heterodonts yielded more specific antibody preparations.

Investigations of shell matrix diagenesis, using the anti‐Mercenaria serum, demonstrated that small amounts of original determinants could be detected even in fossils over one million years old. The reactivity of the serum with extracts of fossil Mercenaria decreased with sample age. The relationship between serum reactivity and the degree of amino acid racemization was almost linear. Clearly, the various determinants to which antibodies were elicited were being destroyed at different rates.     

The global nitrogen cycle in the twenty-first century

Global nitrogen fixation contributes 413 Tg of reactive nitrogen (N_r) to terrestrial and marine ecosystems annually of which anthropogenic activities are responsible for half, 210 Tg N. The majority of the transformations of anthropogenic N_r are on land (240 Tg N yr⁻¹) within soils and vegetation where reduced N_r contributes most of the input through the use of fertilizer nitrogen in agriculture. Leakages from the use of fertilizer N_r contribute to nitrate (NO₃⁻) in drainage waters from agricultural land and emissions of trace N_r compounds to the atmosphere. Emissions, mainly of ammonia (NH₃) from land together with combustion related emissions of nitrogen oxides (NO_x), contribute 100 Tg N yr⁻¹ to the atmosphere, which are transported between countries and processed within the atmosphere, generating secondary pollutants, including ozone and other photochemical oxidants and aerosols, especially ammonium nitrate (NH₄NO₃) and ammonium sulfate (NH₄)₂SO₄. Leaching and riverine transport of NO₃ contribute 40–70 Tg N yr⁻¹ to coastal waters and the open ocean, which together with the 30 Tg input to oceans from atmospheric deposition combine with marine biological nitrogen fixation (140 Tg N yr⁻¹) to double the ocean processing of N_r. Some of the marine N_r is buried in sediments, the remainder being denitrified back to the atmosphere as N₂ or N₂O. The marine processing is of a similar magnitude to that in terrestrial soils and vegetation, but has a larger fraction of natural origin. The lifetime of N_r in the atmosphere, with the exception of N₂O, is only a few weeks, while in terrestrial ecosystems, with the exception of peatlands (where it can be 10²–10³ years), the lifetime is a few decades. In the ocean, the lifetime of N_r is less well known but seems to be longer than in terrestrial ecosystems and may represent an important long-term source of N₂O that will respond very slowly to control measures on the sources of N_r from which it is produced.     

Acyclic phosph(on)ate inhibitors of Plasmodium falciparum hypoxanthine-guanine-xanthine phosphoribosyltransferase

The pathogenic protozoa responsible for malaria lack enzymes for the de novo synthesis of purines and rely on purine salvage from the host. In Plasmodium falciparum (Pf), hypoxanthine-guanine-xanthine phosphoribosyltransferase (HGXPRT) converts hypoxanthine to inosine monophosphate and is essential for purine salvage making the enzyme an anti-malarial drug target. We have synthesized a number of simple acyclic aza-C-nucleosides and shown that some are potent inhibitors of Pf HGXPRT while showing excellent selectivity for the Pf versus the human enzyme.