Identification of a Sorbicillinoid-Producing <Emphasis Type="Italic">Aspergillus</Emphasis> Strain with Antimicrobial Activity Against <Emphasis Type="Italic">Staphylococcus aureus</Emphasis>: a New Polyextremophilic Marine Fungus from Barents Sea

The exploration of poorly studied areas of Earth can highly increase the possibility to discover novel bioactive compounds. In this study, the cultivable fraction of fungi and bacteria from Barents Sea sediments has been studied to mine new bioactive molecules with antibacterial activity against a panel of human pathogens. We isolated diverse strains of psychrophilic and halophilic bacteria and fungi from a collection of nine samples from sea sediment. Following a full bioassay-guided approach, we isolated a new promising polyextremophilic marine fungus strain 8Na, identified as Aspergillus protuberus MUT 3638, possessing the potential to produce antimicrobial agents. This fungus, isolated from cold seawater, was able to grow in a wide range of salinity, pH and temperatures. The growth conditions were optimised and scaled to fermentation, and its produced extract was subjected to chemical analysis. The active component was identified as bisvertinolone, a member of sorbicillonoid family that was found to display significant activity against Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 30 μg/mL.     

Functional Activities of Antibodies Directed against Surface Lipoproteins of Borrelia hermsii

Enriched preparations for mouse polyclonal immunoglobulin G (IgG) antibodies reactive with surface-exposed epitopes (Ab-SEE) of the 22-kDa and 24-kDa membrane lipoproteins of living Borrelia hermsii (HS 1 strain) cells were obtained by an antibody absorption technique using living spirochetes. In vitro, the antibody preparations both inhibited spirochetal growth and were borreliacidal in the presence of complement. The monovalent Fab antibody fragments, prepared from antibody-enriched preparations, did not inhibit the growth of the bacteria, whereas they killed the bacteria in the presence of complement. The two-dimension gel electrophoresis of B. hermsii cells showed that ³H-labeled fatty acids incorporated into the 22-kDa and 24-kDa lipoproteins were resolved into one and three compact spots, respectively. The spots were recognized by the Ab-SEE preparations reactive with the 22-kDa and 24-kDa proteins, by Western blotting.     

An essential step of kinetochore formation controlled by the SNARE protein Snap29

The kinetochore is an essential structure that mediates accurate chromosome segregation in mitosis and meiosis. While many of the kinetochore components have been identified, the mechanisms of kinetochore assembly remain elusive. Here, we identify a novel role for Snap29, an unconventional SNARE, in promoting kinetochore assembly during mitosis in Drosophila and human cells. Snap29 localizes to the outer kinetochore and prevents chromosome mis‐segregation and the formation of cells with fragmented nuclei. Snap29 promotes accurate chromosome segregation by mediating the recruitment of Knl1 at the kinetochore and ensuring stable microtubule attachments. Correct Knl1 localization to kinetochore requires human or Drosophila Snap29, and is prevented by a Snap29 point mutant that blocks Snap29 release from SNARE fusion complexes. Such mutant causes ectopic Knl1 recruitment to trafficking compartments. We propose that part of the outer kinetochore is functionally similar to membrane fusion interfaces.     

Immunochemical characterization of human liver and heart ferritins with monoclonal antibodies

A library of 27 murine monoclonal antibodies was obtained by using human liver and heart ferritins as immunogens. The specificity of the antibodies for the two ferritins and their subunits was studied with five different methods. The antibodies elicited by the liver ferritin bound preferentially the immunogen and were specific for the L subunit. Some antibodies elicited by the heart ferritin had characteristics similar to the anti-liver antibodies, other ones bound preferentially the heart over the liver ferritin and were specific for the H subunit. Only two antibodies were able to bind both ferritins and subunits. Some anti-H and anti-L chain antibodies were used to develop and compare four types of immunoassay to quantitate isoferritins. The results indicate that heart ferritin is immunologically more heterogeneous than liver, the H and L subunits having large immunological differences with few, if any, identical epitopes; and that that the architecture of the immunoassays have a strong influence on the crossreactivity of the antibodies with the two isoferritins, probably because H and L chains are not arranged randomly in the assembled protein.     

Inactivation of Polykaryocytogenic and Hemolytic Activities of Sendai Virus by Phospholipase B (Lysolecithinase)

Evidence is presented that lysolecithin is involved in the fusing and hemolytic activities of Sendai virus. Treatment of the virus with phospholipase B (lysolecithinase) specifically inactivates the hemolytic and fusing abilities, without affecting the infectivity and the capability of the virus to hemagglutinate and adsorb to cells. The possible identity of lysolecithin with the "cell fusion factor" of paramyxoviruses and the mechanism of cell fusion are discussed.     

Analysis of HIV-1 drug resistant mutations by line probe assay and direct sequencing in a cohort of therapy naive HIV-1 infected Italian patients

Background  

Recent studies of viral entry proteins from influenza, measles, human immunodeficiency virus, type 1 (HIV-1), and Ebola virus have shown, first with molecular modeling, and then X-ray crystallographic or other biophysical studies, that these disparate viruses share a coiled-coil type of entry protein.     

Novel tetrapeptide inhibitors of bacterial protein synthesis produced by a Streptomyces sp

In the course of a microbial product screening aimed at the discovery of novel antibiotics acting on bacterial protein synthesis, a complex of three structurally related tetrapeptides, namely, GE81112 factors A, B, and B1, was isolated from a Streptomyces sp. The screening was based on a cell-free assay of bacterial protein synthesis driven by a model mRNA containing natural initiation signals. In this study we report the production, isolation, and structure determination of these novel, potent and selective inhibitors of cell-free bacterial protein synthesis, which stably bind the 30S ribosomal subunit and inhibit the formation of fMet-puromycin. They did not inhibit translation by yeast ribosomes in vitro. Spectroscopic analyses revealed that they are tetrapeptides constituted by uncommon amino acids. While GE81112 factors A, B, and B1 were effective in inhibiting bacterial protein synthesis in vitro, they were less active against Gram-positive and Gram-negative bacterial cells. Cells grown in minimal medium were more susceptible to the compounds than those grown in rich medium, and this is most likely due to competition or regulation by medium components during peptide uptake. The novelty of the chemical structure and of the specific mode of action on the initiation phase of bacterial protein synthesis makes GE81112 a unique scaffold for designing new drugs.     

Contactless magnetocardiographic mapping in anesthetized Wistar rats: evidence of age-related changes of cardiac electrical activity

Magnetocardiography (MCG) is the recording of the magnetic field (MF) generated by cardiac electrophysiological activity. Because it is a contactless method, MCG is ideal for noninvasive cardiac mapping of small experimental animals. The aim of this study was to assess age-related changes of cardiac intervals and ventricular repolarization (VR) maps in intact rats by means of MCG mapping. Twenty-four adult Wistar rats (12 male and 12 female) were studied, under anesthesia, with the same unshielded 36-channel MCG instrumentation used for clinical recordings. Two sets of measurements were obtained from each animal: 1) at 5 mo of age (297.5 +/- 21 g body wt) and 2) at 14 mo of age (516.8 +/- 180 g body wt). RR and PR intervals, QRS segment, and QTpeak, QTend, JTpeak, JTend, and Tpeak-end were measured from MCG waveforms. MCG imaging was automatically obtained as MF maps and as inverse localization of cardiac sources with equivalent current dipole and effective magnetic dipole models. After 300 s of continuous recording were averaged, the signal-to-noise ratio was adequate for study of atrial and ventricular MF maps and for three-dimensional localization of the underlying cardiac sources. Clear-cut age-related differences in VR duration were demonstrated by significantly longer QTend, JTend, and Tpeak-end in older Wistar rats. Reproducible multisite noninvasive cardiac mapping of anesthetized rats is simpler with MCG methodology than with ECG recording. In addition, MCG mapping provides new information based on quantitative analysis of MF and equivalent sources. In this study, statistically significant age-dependent variations in VR intervals were found.