Gamasid Mites (Acari: Parasitiformes: Gamasina) of Rodents of the Valley-Foothill Zone of the Issyk-Kul Basin (Northern Tian-Shan)

Entomological Review - The article presents the current species composition of gamasid mites (Gamasina) of rodents from the valley-foothill zone of Issyk-Kul depression, comprising 28 species...     

Influenza A virus M1 protein structure probed by in situ limited proteolysis with bromelain

Influenza A virus matrix M1 protein is membrane associated and plays a crucial role in virus assembly and budding. The N-terminal two thirds of M1 protein was resolved by X-ray crystallography. The overall 3D structure as well as arrangement of the molecule in relation to the viral membrane remains obscure. Now a proteolytic digestion of virions with bromelain was used as an instrument for the in situ assessment of the M1 protein structure. The lipid bilayer around the subviral particles lacking glycoprotein spikes was partially disrupted as was shown by transmission electron microscopy. A phenomenon of M1 protein fragmentation inside the subviral particles was revealed by SDS-PAGE analysis followed by in-gel trypsin hydrolysis and MALDI-TOF mass spectrometry analysis of the additional bands. Putative bromelain-digestion sites appeared to be located at the surface of the M1 protein globule and could be used as landmarks for 3D molecular modeling.     

Investigation of physicochemical properties of arabinogalactan of different larch species

Samples of arabinogalactan (AG) were isolated by aqueous extraction from wood of different larch species (Larix sibirica Ledeb., Larix gmelinii (Rupr.) Rupr., Larix cajanderi Mayr., and Larix olgensis var. Koreana) and studied by HPLC, IR spectroscopy, and quantitative ¹³C NMR spectroscopy. The wood of the studied larch species was shown to contain significant amount of arabinogalactan (10–17% of the a.d.w. mass) and could be a source of its industrial production. The studied AG samples had similar structural and molecular-mass characteristics. This fact could facilitate the product standardization during its industrial production both from the wood of a single larch species and from mixed raw materials.     

The Thermodynamic Basis for Viral RNA Detection by the RIG-I Innate Immune Sensor

RIG-I is a cytoplasmic surveillance protein that contributes to the earliest stages of the vertebrate innate immune response. The protein specifically recognizes 5′-triphosphorylated RNA structures that are released into the cell by viruses, such as influenza and hepatitis C. To understand the energetic basis for viral RNA recognition by RIG-I, we studied the binding of RIG-I domain variants to a family of dsRNA ligands. Thermodynamic analysis revealed that the isolated RIG-I domains each make important contributions to affinity and that they interact using different strategies. Covalent linkage between the domains enhances RNA ligand specificity while reducing overall binding affinity, thereby providing a mechanism for discriminating virus from host RNA.     

Detection of Borrelia burgdorferi Sensu Stricto ospC Alleles Associated with Human Lyme Borreliosis Worldwide in Non-Human-Biting Tick Ixodes affinis and Rodent Hosts in Southeastern United States

Comparative analysis of ospC genes from 127 Borrelia burgdorferi sensu stricto strains collected in European and North American regions where Lyme disease is endemic and where it is not endemic revealed a close relatedness of geographically distinct populations. ospC alleles A, B, and L were detected on both continents in vectors and hosts, including humans. Six ospC alleles, A, B, L, Q, R, and V, were prevalent in Europe; 4 of them were detected in samples of human origin. Ten ospC alleles, A, B, D, E3, F, G, H, H3, I3, and M, were identified in the far-western United States. Four ospC alleles, B, G, H, and L, were abundant in the southeastern United States. Here we present the first expanded analysis of ospC alleles of B. burgdorferi strains from the southeastern United States with respect to their relatedness to strains from other North American and European localities. We demonstrate that ospC genotypes commonly associated with human Lyme disease in European and North American regions where the disease is endemic were detected in B. burgdorferi strains isolated from the non-human-biting tick Ixodes affinis and rodent hosts in the southeastern United States. We discovered that some ospC alleles previously known only from Europe are widely distributed in the southeastern United States, a finding that confirms the hypothesis of transoceanic migration of Borrelia species.     

Vanillin Resistance Induced by BssS Overexpression in <Emphasis Type="Italic">Escherichia coli</Emphasis>

Overexpression of the BssS gene, a biofilm formation regulator, in planktonic Escherichia coli cells has been shown to confer the vanillin-resistant phenotype Van^r to the bacteria. The MG1655P_L-tac-bssS strain started growing in liquid aerated LB medium with 2 g/L vanillin after a lag phase of 17 ± 2 h, whereas the original MG1655 strain did not grow under these conditions. The role of aldehyde reductase YqhD, a vanillin- degrading enzyme, in Van^r phenotype formation has been assessed. However, the Van^r trait in the MG1655P_L-tac-bssS strain primarily depended on autoinducer-2 (AI-2), which formed in E. coli cells with an intact luxS gene. We supposed that BssS acts together with autoinducer-2 (which presumably accumulated during the prolonged lag phase) to induce vanillin resistance determined by changes in the expression of a range of genes.     

Comparative Analysis of the Activity of the Polymorphic Variants of Human Uracil-DNA-Glycosylases SMUG1 and MBD4

Molecular Biology - The human N-glycosylases SMUG1 and MBD4 catalyze the removal of uracil residues from DNA resulting from cytosine deamination or replication errors. For polymorphic variants of...     

Basic aspects of ovarian development in Drosophila melanogaster

Modern views of the development and structural organization of the female reproductive system in Drosophila melanogaster are reviewed. Special emphasis is placed on the generation and development of follicles in the germarium and the interactions of germline and somatic cells in the egg chamber. Detailed consideration is given to the main events that ensure and regulate the transport of mRNA, proteins, and organelles from nurse cells to the oocyte in the germarium and at later stages of egg chamber development.     

Genes Controlling Development: Morphoses, Phenocopies, Dimorphs, and Other Visible Expressions of Mutant Genes

We studied facultative dominant lethal mutations obtained earlier inDrosophila melanogaster. In some genotypes, these mutations were expressed as lethals, but in other genotypes they lacked this expression. The mutations were maintained in the following cultures: (1) females Muller-5 heterozygous for the mutation; (2) males crossed to attached-Xfemales; and (3) females and males homozygous for the mutation. During culturing, many mutations were found to give rise to phenotypically abnormal progeny. Generally, these abnormalities were morphoses involving various body parts; they were mostly asymmetric and nonheritable. Maternal and paternal effects in the formation of morphoses were observed. In four cases, dimorphic mutations were recorded: a female homozygous for the mutation had mutant phenotype whereas its male counterpart was phenotypically normal. The mutations were recessive with regard to the norm. New phenotypes behaving as mutations with incomplete penetrance arose during culturing. In cultures of mutant homozygotes phenocopies would appear en masse; they would persist for one or two generations and disappear. One wave of phenocopies succeeded another. Visible phenotypes appeared, which further behaved as ordinary recessive mutations. We concluded that these visible manifestations are characteristic for regulatory mutations controlling ontogeny. Their appearance is explained by the activation of new regulatory scenarios caused by blocking standard regulatory pathways.     

Temporal dynamics of methyltransferase and restriction endonuclease accumulation in individual cells after introducing a restriction-modification system

Type II restriction-modification (R-M) systems encode a restriction endonuclease that cleaves DNA at specific sites, and a methyltransferase that modifies same sites protecting them from restriction endonuclease cleavage. Type II R-M systems benefit bacteria by protecting them from bacteriophages. Many type II R-M systems are plasmid-based and thus capable of horizontal transfer. Upon the entry of such plasmids into a naïve host with unmodified genomic recognition sites, methyltransferase should be synthesized first and given sufficient time to methylate recognition sites in the bacterial genome before the toxic restriction endonuclease activity appears. Here, we directly demonstrate a delay in restriction endonuclease synthesis after transformation of Escherichia coli cells with a plasmid carrying the Esp1396I type II R-M system, using single-cell microscopy. We further demonstrate that before the appearance of the Esp1396I restriction endonuclease the intracellular concentration of Esp1396I methyltransferase undergoes a sharp peak, which should allow rapid methylation of host genome recognition sites. A mathematical model that satisfactorily describes the observed dynamics of both Esp1396I enzymes is presented. The results reported here were obtained using a functional Esp1396I type II R-M system encoding both enzymes fused to fluorescent proteins. Similar approaches should be applicable to the studies of other R-M systems at single-cell level.