A prenylation inhibitor prevents production of infectious hepatitis delta virus particles

Hepatitis delta virus (HDV) causes both acute and chronic liver disease throughout the world. Effective medical therapy is lacking. Previous work has shown that the assembly of HDV virus-like particles (VLPs) could be abolished by BZA-5B, a compound with farnesyltransferase inhibitory activity. Here we show that FTI-277, another farnesyltransferase inhibitor, prevented the production of complete, infectious HDV virions of two different genotypes. Thus, in spite of the added complexity and assembly determinants of infectious HDV virions compared to VLPs, the former are also sensitive to pharmacological prenylation inhibition. Moreover, production of HDV genotype III virions, which is associated with particularly severe clinical disease, was as sensitive to prenylation inhibition as was that of HDV genotype I virions. Farnesyltransferase inhibitors thus represent an attractive potential class of novel antiviral agents for use against HDV, including the genotypes associated with most severe disease.     

Mutations in the N-terminal domains of nectin-1 and nectin-2 reveal differences in requirements for entry of various alphaherpesviruses and for nectin-nectin interactions

Nectin-1 and nectin-2 are related molecules that can function with different specificities as entry receptors for mammalian alphaherpesviruses through interaction with viral glycoprotein D (gD). The normal function of members of the nectin family is to mediate cell-cell adhesion through homotypic and heterotypic nectin-nectin interactions in cadherin-based adherens junctions. We examined mutations in three equivalent regions of the N-terminal V-like domains of nectin-1 and nectin-2 to test the effects on entry of various alphaherpesviruses, nectin-nectin interactions, and interactions of the mutant nectins with gD. Mutations in region I previously shown to severely impair herpes simplex virus (HSV) entry activity, but not pseudorabies virus (PRV) or bovine herpesvirus 1 (BHV-1) entry, did not reduce homotypic trans interactions for either nectin-1 or nectin-2 or binding of nectin-3 to nectin-1. Mutations in region II, patterned after a reported single-nucleotide polymorphism in nectin-2, enhanced intracellular accumulation of both nectin-1 and nectin-2 and had a deleterious effect on all of the activities under study. Mutations in region III previously shown to reduce homotypic trans interactions of nectin-2 impaired the entry of PRV and BHV-1 when introduced into either nectin-1 or nectin-2, but only the nectin-2 mutation reduced HSV entry activity. Binding of nectin-1 to nectin-3 was not affected. Effects of the nectin-1 and nectin-2 mutations on interactions with gD did not necessarily correlate with entry activity of the mutant receptors. We can conclude that structural requirements for HSV entry, PRV and BHV-1 entry, and homotypic and heterotypic trans interactions are all different despite the previously reported ability of HSV and HSV gD to inhibit trans interactions.     

Characterization and daily variation of nitrate reductase in Gracilaria tenuistipitata (Rhodophyta)

The chemosensory protein CSP-sg4 of the desert locust Schistocerca gregaria binds reversibly N-phenyl-1-naphthylamine in fluorescent-binding assays, with a dissociation constant of 4 microM. Upon binding to the protein, the emission peaks of the fluorescent probe undergo a marked blue shift, accompanied by an order of magnitude increase of the maximum intensity. The assay has also allowed the measurement of the affinity of CSP to other aromatic and aliphatic compounds. The binding capacity of this protein is unaffected by thermal treatments up to 100 degrees C for 20 min. The ligand-binding characteristics of chemosensory proteins may help in clarifying the role of this recently discovered class of soluble proteins in chemoreception.     

Morphologically complex plant macrofossils from the Late Silurian of Arctic Canada

In addition to vegetative remains, fertile remains from ten plants, representing seven distinct taxa whose size and complexity are much greater than most contemporaneous fossils, are reported from late Ludlow (Ludfordian) sediments of Bathurst Island in Nunavut, Canada. Evidence for the age of these beds is gathered from stratigraphic relationships and index fossils including conodonts, graptolites, and brachiopods. Zosterophylls dominate the collection, some of which constitute the earliest record of fertile structures arranged in dense clusters and longitudinal rows along axes. Representatives include a plant that resembles Bathurstia, one species of Zosterophyllum, and two specimens that bear affinity to this genus. Distichophytum is also represented, as is a new zosterophyll named Macivera gracilis. The prevalence of sporangial clustering and reduced sporangial stalks in this flora leads to a discussion of the origins and significance of these morphological features. Following a review of some of the other Silurian floras, particularly the Baragwanathia-bearing Lower Plant Assemblage of Victoria, Australia, which also shows morphological advancement over the rhyniophytoid-dominated floras common to Laurussia, it is concluded that the Bathurst Island flora presents the best evidence to date of substantial morphological diversity, complexity, and stature of vascular land plants in this period.     

Enhancer trap expression patterns provide a novel teaching resource

A collection of Arabidopsis enhancer trap transposants has been identified for use as a teaching tool. This collection serves to assist students in understanding the patterning and organization of plant tissues and cells, and will be useful in plant anatomy, morphology, and developmental biology courses. Each transposant exhibits reporter gene expression in a specific tissue, cell type, or domain, and these lines collectively offer a glimpse of compartments of gene expression. Some compartments correspond to classical definitions of botanical anatomy and can assist in anatomical identification. Other patterns of reporter gene expression are more complex and do not necessarily correspond to known anatomical features. The sensitivity of the beta-glucuronidase histochemical stain provides the student with a colorful and direct way to visualize difficult aspects of plant development and anatomy, and provides the teacher with an invaluable tool for a practical laboratory session.     

Survey of factors determining the circularly polarised luminescence of macrocyclic lanthanide complexes in solution

The development of emissive lanthanide complexes as structural or reactive probes to signal changes in their local chiral or ionic environment has been inhibited by the lack of understanding of correlating structural and electronic spectral information. The definition of relatively rigid enantiopure macrocyclic lanthanide complexes, whose inter- and intramolecular exchange dynamics have been defined, offers scope for remedying this situation. Chiral axially symmetric lanthanide complexes in solution give rise to large emission dissymmetry values (g(em)) in CPL spectra. The sign and magnitude of g(em) are determined by the degree of twist about the principal axis, which is predicted to be a maximum at +/-22.5 degrees, and by the site symmetry and local ligand field. In particular, the polarisability of the ligand donor atoms, especially for any axial donor, is very important. Examples of each case are discussed for structurally related cationic Eu(III) complexes.     

Skeletal defects in VEGF(120/120) mice reveal multiple roles for VEGF in skeletogenesis

Angiogenesis is an essential component of skeletal development and VEGF signaling plays an important if not pivotal role in this process. Previous attempts to examine the roles of VEGF in vivo have been largely unsuccessful because deletion of even one VEGF allele leads to embryonic lethality before skeletal development is initiated. The availability of mice expressing only the VEGF120 isoform (which do survive to term) has offered an opportunity to explore the function of VEGF during embryonic skeletal development. Our study of these mice provides new in vivo evidence for multiple important roles of VEGF in both endochondral and intramembranous bone formation, as well as some insights into isoform-specific functions. There are two key differences in vascularization of developing bones between wild-type and VEGF(120/120) mice. VEGF(120/120) mice have not only a delayed recruitment of blood vessels into the perichondrium but also show delayed invasion of vessels into the primary ossification center, demonstrating a significant role of VEGF at both an early and late stage of cartilage vascularization. These findings are the basis for a two-step model of VEGF-controlled vascularization of the developing skeleton, a hypothesis that is supported by the new finding that VEGF is expressed robustly in the perichondrium and surrounding tissue of cartilage templates of future bones well before blood vessels appear in these regions. We also describe new in vivo evidence for a possible role of VEGF in chondrocyte maturation, and document that VEGF has a direct role in regulating osteoblastic activity based on in vivo evidence and organ culture experiments.     

A collagen-like surface glycoprotein is a structural component of the Bacillus anthracis exosporium

Bacillus anthracis, the aetiological agent of anthrax, is a Gram-positive spore-forming bacterium. The exosporium is the outermost integument surrounding the mature spore. Here, we describe the purification and the characterization of an immunodominant protein of the spore surface. This protein was abundant, glycosylated and part of the exosporium. The amino-terminal sequence was determined and the corresponding gene was identified. It encodes a protein of 382 amino acid residues, the central part of which contains a region of GXX motifs presenting similarity to mammalian collagen proteins. Thus, this collagen-like surface protein was named BclA (for Bacillus collagen-like protein of anthracis). BclA was absent from vegetative cells; it was detected only in spores and sporulating cells. A potential promoter, dependent on the sigma factor sigma(K), which is required for a variety of events late in sporulation, was found upstream from the bclA gene. A bclA deletion mutant was constructed and analysed. Electron microscopy studies showed that BclA is a structural component of the filaments covering the outer layer of the exosporium.     

CCR3 antagonists: a potential new therapy for the treatment of asthma. Discovery and structure-activity relationships

CCR3 antagonist leads with IC(50) values in the microM range were converted into low nM binding compounds that displayed in vitro inhibition of human eosinophil chemotaxis induced by human eotaxin. In particular, 4-benzylpiperidin-1-yl-n-propylureas and erythro-3-(4-benzyl-2-(alpha-hydroxyalkyl)piperidin-1-yl)-n-propylureas (obtained via Beak reaction of N-BOC-4-benzylpiperidine) exhibited single digit nanomolar IC(50) values for CCR3.     

Cellular localization of D-lactate dehydrogenase and NADH oxidase from Archaeoglobus fulgidus

Members of the genus Archaeoglobus are hyperthermophilic sulfate reducers with an optimal growth temperature of 83 degrees C. Archaeoglobus fulgidus can utilize simple compounds including D-lactate, L-lactate and pyruvate as the sole substrate for carbon and electrons for dissimilatory sulfate reduction. Previously we showed that this organism makes a D-lactate dehydrogenase (Dld) that requires FAD and Zn2+ for activity. To determine the cellular location and topology of Dld and to identify proteins that interact with Dld, an antibody directed against Dld was prepared. Immunocytochemical studies using gold particle-coated secondary antibodies show that more than 85% of Dld is associated with the membrane. A truncated form of Dld was detected in immunoblots of whole cells treated with protease, showing that Dld is an integral membrane protein and that a significant portion of Dld, including part of the FAD-binding pocket, is outside the membrane facing the S-layer. The gene encoding Dld is part of an operon that includes noxA2, which encodes one of several NADH oxidases in A. fulgidus. Previous studies have shown that NoxA2 remains bound to Dld during purification. Thin sections of A. fulgidus probed simultaneously with antibodies against Dld and NoxA2 show that both proteins co-localized to the same sites in the membrane. Although these data show a tight interaction between NoxA2 and Dld, the role of NoxA2 in electron transport reactions is unknown. Rather, NoxA2 may protect proteins involved in electron transfer by reducing O2 to H2O2 or H2O.