Aurapex penicillata gen. sp. nov. from native Miconia theaezans and Tibouchina spp. in Colombia

Conidiomata of a fungus resembling Chrysoporthe cubensis, a serious canker pathogen of Eucalyptus spp. (Myrtaceae, Myrtales) in tropical and subtropical parts of the world, was found on Eucalyptus grandis in Colombia. Fruiting structures of the fungus could be distinguished from those of C. cubensis by their distinctly orange conidiomatal necks. This fungus also was found on several plant species native to Colombia including Tibouchina urvilleana, T. lepidota and Miconia theaezans (Melastomataceae, Myrtales). Morphological comparisons, as well as those based on sequences of the ITS1/ITS2 region of the ribosomal DNA repeat and the beta-tubulin gene, were used to characterize this fungus. Its pathogenicity was assessed on various plants from which it has been collected, either in field or greenhouse trials. Phylogenetic analyses showed that isolates reside in a clade distinct from the four clades accommodating Chrysoporthe, Cryphonectria, Endothia and Rostraureum. Members of this clade are distinguished by the presence of orange conidiomatal necks with black bases and a unique internal stromatal structure. No teleomorph has been found for this fungus, for which we have provided the name Aurapex penicillata gen. sp. nov. A. penicillata produced only small lesions after inoculation on young T. urvilleana, M. theaezans and E. grandis trees and appears not to be a serious pathogen.     

Radiofrequency and extremely low-frequency electromagnetic field effects on the blood-brain barrier

During the last century, mankind has introduced electricity and during the very last decades, the microwaves of the modern communication society have spread a totally new entity--the radiofrequency fields--around the world. How does this affect biology on Earth? The mammalian brain is protected by the blood-brain barrier, which prevents harmful substances from reaching the brain tissue. There is evidence that exposure to electromagnetic fields at non thermal levels disrupts this barrier. In this review, the scientific findings in this field are presented. The result is a complex picture, where some studies show effects on the blood-brain barrier, whereas others do not. Possible mechanisms for the interactions between electromagnetic fields and the living organisms are discussed. Demonstrated effects on the blood-brain barrier, as well as a series of other effects upon biology, have caused societal anxiety. Continued research is needed to come to an understanding of how these possible effects can be neutralized, or at least reduced. Furthermore, it should be kept in mind that proven effects on biology also should have positive potentials, e.g., for medical use.     

Synthesis and antibacterial activity of 5-methylphenanthridium derivatives as FtsZ inhibitors

5-Methylphenanthridium derivatives were designed, synthesized and evaluated for their in vitro antibacterial activity and cell division inhibitory activity against various Gram-positive and -negative bacteria. Among them, compounds 5A2, 5B1, 5B2, 5B3, 5C1 and 5C2 displayed the best on-target antibacterial activity with an MIC value of 4 µg/mL against B. subtilis ATCC9372 and S. pyogenes PS, showing over 2-fold better activity than sanguinarine. The SARs showed that the 5-methylphenanthridium derivatives with the alkyl side chains at the 2-postion, especially the straight alkyl side chains exerted better on-target antibacterial activity.     

Cross-reactivity between human and fish pituitary hormones as demonstrated by immunocytochemistry

Summary In this communication we describe the immunocytochemical cross-reactivity between antisera to various human pituitary hormones and specific hormone producing cell types in the pituitary gland of sexually mature male platyfish (Xiphophorus maculatus). Antisera to human pituitary hormones cross-reacted either with cells known to produce corresponding hormones (or hormone subunits) in the platyfish (e.g., ACTH, prolactin, TSH , LH , FSH , TSH ) or with no pituitary cells at all (e.g., LH , FSH ). The one exception was antiserum to human growth hormone which cross-reacted with MSH and ACTH producing cells. The platyfish pituitary is proposed as a test system for immunocytochemically screening antisera for purity and specificity in order to determine their applicability in particular studies.     

Drug-lipid A interactions on the Escherichia coli ABC transporter MsbA

MsbA is an essential ATP-binding cassette half-transporter in the cytoplasmic membrane of the gram-negative Escherichia coli and is required for the export of lipopolysaccharides (LPS) to the outer membrane, most likely by transporting the lipid A core moiety. Consistent with the homology of MsbA to the multidrug transporter LmrA in the gram-positive Lactococcus lactis, our recent work in E. coli suggested that MsbA might interact with multiple drugs. To enable a more detailed analysis of multidrug transport by MsbA in an environment deficient in LPS, we functionally expressed MsbA in L. lactis. MsbA expression conferred an 86-fold increase in resistance to the macrolide erythromycin. A kinetic characterization of MsbA-mediated ethidium and Hoechst 33342 transport revealed apparent single-site kinetics and competitive inhibition of these transport reactions by vinblastine with K(i) values of 16 and 11 microM, respectively. We also detected a simple noncompetitive inhibition of Hoechst 33342 transport by free lipid A with a K(i) of 57 microM, in a similar range as the K(i) for vinblastine, underscoring the relevance of our LPS-less lactococcal model for studies on MsbA-mediated drug transport. These observations demonstrate the ability of heterologously expressed MsbA to interact with free lipid A and multiple drugs in the absence of auxiliary E. coli proteins. Our transport data provide further functional support for direct LPS-MsbA interactions as observed in a recent crystal structure for MsbA from Salmonella enterica serovar Typhimurium (C. L. Reyes and G. Chang, Science 308:1028-1031, 2005).     

Distinct groups of multidrug resistance modulating agents are distinguished by competition of P-glycoprotein-specific antibodies

P-glycoprotein (Pgp) is one of the ABC transporters responsible for the multidrug resistance of cancer cells. The conformational changes of Pgp that occur in the presence of substrates/modulators or ATP depletion are accompanied by the up-shift of UIC2 monoclonal antibody (mAb) binding. In the case of cyclosporin A, vinblastine or valinomycin, this up-shift was found to be concomitant with the near-complete suppression of labeling with other mAbs specific for Pgp epitopes overlapping with UIC2, while pre-treatment with verapamil or Tween 80 brings about a modest suppression. Here we have extended these observations to 44 Pgp interacting agents, and found that only 8 fall into the cyclosporin-like category, inducing a conformational state characterized by the complete UIC2 dominance. The rest of the drugs either did not affect antibody competition or had a modest effect. Thus, Pgp substrates/modulators can be classified into distinct modalities based on the conformational change they elicit.     

Expression of PD‐1/LAG‐3 and cytokine production by CD4+ T cells during infection with Plasmodium parasites

CD4⁺ T cells play critical roles in protection against the blood stage of malarial infection; however, their uncontrolled activation can be harmful to the host. In this study, in which rodent models of Plasmodium parasites were used, the expression of inhibitory receptors on activated CD4⁺ T cells and their cytokine production was compared with their expression in a bacterial and another protozoan infection. CD4⁺ T cells from mice infected with P. yoelii 17XL, P yoelii 17XNL, P. chabaudi, P. vinckei and P. berghei expressed the inhibitory receptors, PD‐1 and LAG‐3, as early as 6 days after infection, whereas those from either Listeria monocytogenes‐ or Leishmania major‐infected mice did not. In response to T‐cell receptor stimulation, CD4⁺ T cells from mice infected with all the pathogens under study produced high concentrations of IFN‐γ. IL‐2 production was reduced in mice infected with Plasmodium species, but not in those infected with Listeria or Leishmania. In vitro blockade of the interaction between PD‐1 and its ligands resulted in increased IFN‐γ production in response to Plasmodium antigens, implying that PD‐1 expressed on activated CD4⁺ T cells actively inhibits T cell immune responses. Studies using Myd88^?/?, Trif^?/? and Irf3^?/? mice showed that induction of these CD4⁺ T cells and their ability to produce cytokines is largely independent of TLR signaling. These studies suggest that expression of the inhibitory receptors PD‐1 and LAG‐3 on CD4⁺ T cells and their reduced IL‐2 production are common characteristic features of Plasmodium infection.