Nitrate respiration protects hypoxic Mycobacterium tuberculosis against acid- and reactive nitrogen species stresses

There are strong evidences that Mycobacterium tuberculosis survives in a non-replicating state in the absence of oxygen in closed lesions and granuloma in vivo. In addition, M. tuberculosis is acid-resistant, allowing mycobacteria to survive in acidic, inflamed lesions. The ability of M. tuberculosis to resist to acid was recently shown to contribute to the bacillus virulence although the mechanisms involved have yet to be deciphered. In this study, we report that M. tuberculosis resistance to acid is oxygen-dependent; whereas aerobic mycobacteria were resistant to a mild acid challenge (pH 5.5) as previously reported, we found microaerophilic and hypoxic mycobacteria to be more sensitive to acid. In hypoxic conditions, mild-acidity promoted the dissipation of the protonmotive force, rapid ATP depletion and cell death. Exogenous nitrate, the most effective alternate terminal electron acceptor after molecular oxygen, protected hypoxic mycobacteria from acid stress. Nitrate-mediated resistance to acidity was not observed for a respiratory nitrate reductase NarGH knock-out mutant strain. Furthermore, we found that nitrate respiration was equally important in protecting hypoxic non-replicating mycobacteria from radical nitrogen species toxicity. Overall, these data shed light on a new role for nitrate respiration in protecting M. tuberculosis from acidity and reactive nitrogen species, two environmental stresses likely encountered by the pathogen during the course of infection.     

Genome wide gene expression studies in mood disorders

Microarrays offer the possibility of screening in parallel virtually all genes expressed in a given tissue or to study the molecular signature associated with available treatments. As such, this technology has been increasingly used to investigate multifactorial and polygenic complex traits such as psychiatric disorders, in particular, schizophrenia and mood disorders. This review focuses on microarray studies investigating mood disorders. Study designs, methodologic approaches and limitations, subsequent follow-up strategies, and confirmation of results are discussed. Despite the apparent disparate and not always concordant results, it appears evident that this technology is a powerful and inevitable approach for the study of mood disorders, especially when phenotype-specific confounders are properly accounted for. Thus, alterations of mitochondrial, oligodendrocyte, and myelin related genes in bipolar disorder, of signaling and olidendroglial related genes in depression, and of GABA-glutamate related genes in depression and suicide have been observed and have confirmed new avenues for the study and the treatment of these complex disorders.     

Evaluating legume species as alternative trap crops to chickpea for management of Helicoverpa spp. (Lepidoptera: Noctuidae) in central Queensland cotton cropping systems

Mounting levels of insecticide resistance within Australian Helicoverpa spp. populations have resulted in the adoption of non-chemical IPM control practices such as trap cropping with chickpea, Cicer arietinum (L.). However, a new leaf blight disease affecting chickpea in Australia has the potential to limit its use as a trap crop. Therefore this paper evaluates the potential of a variety of winter-active legume crops for use as an alternative spring trap crop to chickpea as part of an effort to improve the area-wide management strategy for Helicoverpa spp. in central Queensland's cotton production region. The densities of Helicoverpa eggs and larvae were compared over three seasons on replicated plantings of chickpea, Cicer arietinum (L.), field pea Pisum sativum (L), vetch, Vicia sativa (L.) and faba bean, Vicia faba (L.). Of these treatments, field pea was found to harbour the highest densities of eggs. A partial life table study of the fate of eggs oviposited on field pea and chickpea suggested that large proportions of the eggs laid on field pea suffered mortality due to dislodgment from the plants after oviposition. Plantings of field pea as a replacement trap crop for chickpea under commercial conditions confirmed the high level of attractiveness of this crop to ovipositing moths. The use of field pea as a trap crop as part of an area-wide management programme for Helicoverpa spp. is discussed.     

Database resources of the National Center for Biotechnology

In addition to maintaining the GenBank(R) nucleic acid sequence database, the National Center for Biotechnology Information (NCBI) provides data analysis and retrieval resources for the data in GenBank and other biological data made available through NCBI's Web site. NCBI resources include Entrez, PubMed, PubMed Central (PMC), LocusLink, the NCBITaxonomy Browser, BLAST, BLAST Link (BLink), Electronic PCR (e-PCR), Open Reading Frame (ORF) Finder, References Sequence (RefSeq), UniGene, HomoloGene, ProtEST, Database of Single Nucleotide Polymorphisms (dbSNP), Human/Mouse Homology Map, Cancer Chromosome Aberration Project (CCAP), Entrez Genomes and related tools, the Map Viewer, Model Maker (MM), Evidence Viewer (EV), Clusters of Orthologous Groups (COGs) database, Retroviral Genotyping Tools, SAGEmap, Gene Expression Omnibus (GEO), Online Mendelian Inheritance in Man (OMIM), the Molecular Modeling Database (MMDB), the Conserved Domain Database (CDD), and the Conserved Domain Architecture Retrieval Tool (CDART). Augmenting many of the Web applications are custom implementations of the BLAST program optimized to search specialized data sets. All of the resources can be accessed through the NCBI home page at: http://www.ncbi.nlm.nih.gov.     

The embryo makes red blood cell progenitors in every tissue simultaneously with blood vessel morphogenesis

During embryonic life, hematopoiesis occurs first in the yolk sac, followed by the aorto-gonado-mesonephric region, the fetal liver, and the bone marrow. The possibility of hematopoiesis in other embryonic sites has been suspected for a long time. With the use of different methodologies (transgenic mice, electron microscopy, laser capture microdissection, organ culture, and cross-transplant experiments), we show that multiple regions within the embryo are capable of forming blood before and during organogenesis. This widespread phenomenon occurs by hemo-vasculogenesis, the formation of blood vessels accompanied by the simultaneous generation of red blood cells. Erythroblasts develop within aggregates of endothelial cell precursors. When the lumen forms, the erythroblasts "bud" from endothelial cells into the forming vessel. The extensive hematopoietic capacity found in the embryo helps explain why, under pathological circumstances such as severe anemia, extramedullary hematopoiesis can occur in any adult tissue. Understanding the intrinsic ability of tissues to manufacture their own blood cells and vessels has the potential to advance the fields of organogenesis, regeneration, and tissue engineering.     

S-nitrosylation of NSF controls membrane trafficking

Nitric oxide is a diffusible molecule with profound effects on regulated exocytosis in several biological systems-however, the molecular targets remain elusive. In this issue of Cell, Matsushita et al. report that in aortic endothelial cells, S-nitrosylation of NSF, an ATPase essential for the activation of the membranefusion machinery, inhibits the exocytosis of Weibel-Palade bodies, secretory granules containing a cocktail of mediators essential to the regulation of vascular vessel tone.     

Crystallographic identification of Ca2+ and Sr2+ coordination sites in synaptotagmin I C2B domain

Synaptotagmin I has two tandem Ca(2+)-binding C(2) domains, which are essential for fast synchronous synaptic transmission in the central nervous system. We have solved four crystal structures of the C(2)B domain, one of them in the cation-free form at 1.50 A resolution, two in the Ca(2+)-bound form at 1.04 A (two bound Ca(2+) ions) and 1.65 A (three bound Ca(2+) ions) resolution and one in the Sr(2+)-bound form at 1.18 A (one bound Sr(2+) ion) resolution. The side chains of four highly conserved aspartic acids (D303, D309, D363, and D365) and two main chain oxygens (M302:O and Y364:O), together with water molecules, are in direct contact with two bound Ca(2+) ions (sites 1 and 2). At higher Ca(2+) concentrations, the side chain of N333 rotates and cooperates with D309 to generate a third Ca(2+) coordination site (site 3). Divalent cation binding sites 1 and 2 in the C(2)B domain were previously identified from NMR NOE patterns and titration studies, supplemented by site-directed mutation analysis. One difference between the crystal and NMR studies involves D371, which is not involved in coordination with any of the identified Ca(2+) sites in the crystal structures, while it is coordinated to Ca(2+) in site 2 in the NMR structure. In the presence of Sr(2+), which is also capable of triggering exocytosis, but with lower efficiency, only one cation binding site (site 1) was occupied in the crystallographic structure.     

Triosephosphates are toxic to superoxide dismutase-deficient Escherichia coli

Increase in the production of triosephosphates has been considered an important factor leading to diabetic complications. It might be expected that like the other short chain monosaccharides, triosephosphates autoxidize producing superoxide radical and alpha,beta-diketones. Since superoxide can also initiate the oxidation of short chain sugars, free radical chain reactions are possible. If such reactions occur in vivo, triosephosphates would be more deleterious to cells lacking superoxide dismutase (SOD) than to normal cells. Here we demonstrate that triosephosphates kill a SOD-deficient Escherichia coli mutant much more than the parental, SOD-proficient strain. The effect is oxygen-dependent and is partially suppressed by aminoguanidine. Increased production of superoxide and diketones appeared to be the cause of triosephosphates toxicity.     

Jatrophane and lathyrane diterpenoids from Euphorbia hyberna L

A new diterpene tetraester, from the jatrophane family, and two new diterpene triesters, with a lathyrane skeleton, have been isolated from the chloroform extract of the roots of Euphorbia hyberna L. The structures of these compounds have been established by spectroscopic methods, including 2D NMR experiments.     

High-performance liquid chromatography and studies of neurophysin—neurohypophysial hormone pathways

High-performance liquid chromatography (HPLC) is being used extensively to characterize active polypeptides, precursor processing mechanisms, and cooperative peptide—protein noncovalent complexes in neuroendocrine pathways for neurohypophysial peptide hormones, oxytocin and vasopressin, and the hormone-associated proteins, neurophysins. Reversed-phase and ion-exchange HPLC polypeptide mapping have been used to detect the hormones, associated proteins, and other molecular forms containing these. This mapping but also ultimately to identify anatomical sites which contain the neurophysin/ hormone molecular pathways and to define the relatedness of polypeptide forms contained in different pathways. Reversed-phase HPLC also has provided a means to study proteolytic precursor processing, both to isolate synthetic and semisynthetic polypeptides and intermediates produced by these reactions. Finally, bioaffinity HPLC is being evaluated as a separatory and analytical tool. The latter includes its use to characterize the noncovalent peptide—protein and protein—protein interactions which occur among the molecular forms of the neurophysin/hormone pathways. These experiments typify the impact of HPLC for both analytical and preparative separations in studies of biologically active peptides and proteins.