Generation of drug-resistant mutants of Helicobacter pylori in the presence of peroxynitrite, a derivative of nitric oxide, at pathophysiological concentration.

In the present study it has been shown that the reactive nitrogen species, peroxynitrite, can cause at least a 7.1-fold increase in the frequency of occurrence of drug-resistant mutants of Helicobacter pylori at a pathophysiological concentration (e.g.

CelTOS, a novel malarial protein that mediates transmission to mosquito and vertebrate hosts.

The malarial parasite has two hosts in its life cycle, a vertebrate and a mosquito. We report here that malarial invasion into these hosts is mediated by a protein, designated cell-traversal protein for ookinetes and sporozoites (CelTOS), which is localized to micronemes that are organelles for parasite invasive motility. Targeted disruption of the CelTOS gene in Plasmodium berghei reduced parasite infectivity in the mosquito host approximately 200-fold.

Leukocyte activation by malarial pigment.

Malarial pigment, a unique hemozoin crystal composed of unit cells of heme dimers, is present in large amounts in circulating monocytes and neutrophils and can persist unchanged in macrophages for several months. In the present study, we investigated the effect of hemozoin not only on macrophages, but also on neutrophils. We used beta-hematin (BH), a chemically synthetic crystal structurally identical to hemozoin, for these studies.

One-step concentration of malarial parasite-infected red blood cells and removal of contaminating white blood cells.

Background: Isolation of a concentrated, living preparation of malarial parasite-infected red blood cells (PRBCs) that have low contamination of white blood cells (WBCs) facilitates research on the molecular, biochemical and immunological aspects of malarial parasites. This is currently carried out by a two-step method, including the concentration of PRBCs using density gradient centrifugation through Percoll or Nycodenz, followed by the removal of host WBCs using a cellulose powder column or a commercially available filtration unit. These two-step methods can help isolate sufficient PRBCs, but they are laborious.

Genomic cloning of ribonucleases in Nicotiana glutinosa leaves, as induced in response to wounding or to TMV-infection, and characterization of their promoters.

We previously cloned two distinct cDNA clones, NGR1 and NGR3, encoding S-like ribonucleases (RNases) induced by wounding and tobacco mosaic virus (TMV) infection, respectively, in Nicotiana glutinosa leaves. To gain insight into the regulatory mechanism of the RNase genes, we analyzed nucleotide sequences of the genes ngr1 (4.1 kbp) and ngr3 (5.

MAEBL is essential for malarial sporozoite infection of the mosquito salivary gland.

Malarial sporozoites mature in the oocysts formed in the mosquito midgut wall and then selectively invade the salivary glands, where they wait to be transmitted to the vertebrate host via mosquito bite. Invasion into the salivary gland has been thought to be mediated by specific ligand-receptor interactions, but the molecules involved in these interactions remain unknown. MAEBL is a single transmembrane-like protein that is structurally related to merozoite adhesive proteins.

Molecular cloning of cDNAs encoding ribonuclease-related proteins in Nicotiana glutinosa leaves, as induced in response to wounding or to TMV-infection.

We earlier isolated a cDNA clone (NGR1) encoding a wound-inducible ribonuclease (RNase NW) from leaves of Nicotiana glutinosa [Kariu et al. Biosci. Biotechnol.