Activation of morphogenesis and proliferation by low specificity chemical effectors

Activation of highly specific biochemical processes by simple chemical agents is demonstrated for morphogenesis (anlage and development of female gametophyte in cereal) and mitosis (in cell cultures and animal and plant tissues). The effects of these agents are tissue-specific. Structure--activity relationship is analyzed in this group of compounds. Thus, the phenomenon reveals the exact pathways of the influence of allelopathic and anthropogenic chemical agents on evolution of plant biocenoses.     

Organization of fusicoccin receptor in higher plant plasma membrane: relationship between affinity and molecular mass

Higher plant plasma membranes carry receptors of different affinity for the phytotoxin fusicoccin. Reception of fusicoccin involves proteins belonging to the highly conserved 14-3-3 family, but the complete structure of the fusicoccin receptor (FCR) is unknown. Using radiation inactivation analysis, we estimated the molecular masses of low-affinity and high-affinity FCR at 63 +/- 7 and 130 +/- 15 kD, respectively. The dose dependences of receptor inactivation indicate that microsomal specimens contain "silent" FCRs of 420 +/- 90 kD in amounts commensurate with that of the active FCRs. Both low- and high-affinity FCRs are inactivated by hydrolytic enzymes from the outer surface of the plasma membrane, and impairment of protoplast integrity causes an irreversible transition of the low-affinity binding site into the high-affinity one. A scheme is proposed for the organization of different types of FCR in the plasma membrane, implying that the membrane affinity for fusicoccin reflects the interaction between proteins in the FCR complex.     

Romanowsky staining,the Romanowsky effect and thoughts on the question of scientific priority

I give an historical account and analysis of the scientific priority of the discovery of the polychrome staining of microscopic biological preparations provided by mixtures of eosin plus methylene blue and its derivatives, especially azure B. I maintain that both the formal priority for the discovery of the polychrome staining phenomenon and credit for initiating the development of a technique of polychrome staining properly belong to D. L. Romanowsky. His scientific work demonstrated the possibility of using a simple technique to stain hematological preparations selectively to give good contrast, high resolution and the ability to identify malaria parasites. Romanowsky’s approach constituted the starting point for the development of a family of polychrome stains for microscopic investigation of hematological preparations by a number of his contemporaries.     

P-glycoprotein effect on the properties of its natural lipid environment probed by Raman spectroscopy and Langmuir-Blodgett technique

Behavior of P-glycoprotein (Pgp) natural lipid environment within the membrane of CEM cells expressing Pgp in the quantities varying from 0% to 32% of the total amount of all membrane proteins is described for the first time. Observed cooperative effect of Pgp-induced increase of membrane stability, decrease of the temperature of gel-to-crystal lipids transition and predominance of the lipid liquid crystalline phase at physiological temperatures should have an impact in development of multidrug resistance phenotype of tumor cells by favoring the Pgp intercellular transfer and Pgp ATPase activity.     

Novel ultramicrobacteria,strains NF4 and NF5, of the genus <Emphasis Type="Italic">Chryseobacterium</Emphasis>: Facultative epibionts of <Emphasis Type="Italic">Bacillus subtilis</Emphasis>

Two strains, NF4 and NF5, of a yellow-colored gram-negative bacterium were isolated from sediments of Lake Baikal and from old oil sludge of the Nizhnekamsk oil-processing plant. The cells of the strains are ultrasmall coccoids or short rods, measuring 0.2–0.4 × 0.2–0.5 μm; the average cell volume ranges from 0.004 to 0.04 μm³. A considerable proportion (30–60%) of cells have nanometer dimensions (180–300 nm in diameter and 0.004–0.02 μm³ in volume). The new isolates are thus among the smallest representatives of presently known free-living ultramicrobacteria. The two studied isolates are gram-negative nonmotile cells possessing a pronounced outer membrane. The cells do not have flagella and are not capable of gliding motility. They divide by constriction, budding, and multiple septation. The multiplicity of reproduction mechanisms results in a high degree of cell polymorphism. The isolates are chemoorganotrophic, aerobic, psychrotolerant, oxidase- and catalase-positive. Their characteristic trait is the absence of extracellular hydrolytic enzymes, such as proteases, lipases, pectinases, and cellulases. Menaquinone MK-6 is the main respiratory quinone; the flexirubin pigment was not detected. The G + C contents of the DNA of strains NF4 and NF5 are 40.8 and 40.5 mol %, respectively. The DNA-DNA hybridization level of strains NF4 and NF5 was close to 100%. Analysis of the 16S rRNA gene sequences and the fatty acid compositions showed that the isolates are most closely related to certain representatives of the genus Chryseobacterium (C. solincola, C. antarcticum, and C. jeonii). However, the differences in the 16S rRNA gene sequences, as well as in the phenotypic properties, such as formation of ultrasmall cells, the absence of extracellular hydrolases, oligotrophy, and the capacity for epibiosis on bacterial cells, suggest that the studied strains belong to a new species of the genus Chryseobacterium. The capacity for epibiosis, i.e., the ability to exist in a tightly adhered state on the surfaces of host Bacillus subtilis cells, is a peculiar trait of the studied isolates. It is assumed that adhesion of the cells of strains NF4 and NF5 (members of the phylum Bacteroidetes) occurs via by the same unique mechanism as the mechanism that we previously described for representatives of Alphaproteobacteria (Kaistia sp., NF1, and NF3), which use polysaccharide chains equipped with sticky granules as trapping and constricting cords.     

Structure-Function-Immunogenicity Studies of PfEMP1 Domain DBL2βPF11_0521, a Malaria Parasite Ligand for ICAM-1

Plasmodium falciparum virulence has been ascribed to its ability to sequester in deep vascular beds, mediated by the variant surface antigen family PfEMP1 binding endothelial receptors like ICAM-1. We previously observed that naturally-acquired antibodies that block a PfEMP1 domain, DBL2β of PF11_0521 allele, from binding to the human ICAM1 receptor, reduce the risk of malaria hospitalization in children. Here, we find that DBL2β_{PF11_0521} binds ICAM-1 in the low nM range and relate the structure of this domain with its function and immunogenicity. We demonstrate that the interaction with ICAM-1 is not impaired by point mutations in the N-terminal subdomain or in the flexible Loop 4 of DBL2β_{PF11_0521}, although both substructures were previously implicated in binding ICAM-1. These data will help to refine the existing model of DBLβ::ICAM-1 interactions. Antibodies raised against full-length DBL2β_{PF11_0521}, but not truncated forms lacking the N terminal fragment, block its interaction with ICAM-1. Our data suggest that full length domain is optimal for displaying functional epitopes and has a broad surface of interaction with ICAM-1 that is not disrupted by individual amino acid substitutions at putative key residues. This information might be important for the future design of anti-malarial vaccines based on PfEMP1 antigens.     

DNA sequence-specific ligands: XIII. New dimeric Hoechst 33258 molecules,inhibitors of HIV-1 integrase in vitro

Dimeric Hoechst 33258 molecules [dimeric bisbenzimidazoles (DBBIs)] that, upon binding, occupy one turn of the B form of DNA in the narrow groove were constructed by computer simulation. Three fluorescent DBBIs were synthesized; they consist of two bisbenzimidazole units tail-to-tail linked to phenolic hydroxy groups via penta-or heptamethylene or tri(ethylene glycol) spacers and have terminal positively charged N,N-dimethylaminopropyl carboxamide groups in the molecule. The absorption spectra of the DBBIs in the presence of different DNA concentrations showed a hypochromic effect and a small shift of the absorption band to longer wavelengths, which indicated the formation of a complex with DNA. The presence of an isobestic point in the spectrum indicates the formation of one type of DBBI-DNA complexes. The interaction of DBBIs with DNA was studied by CD using a cholesteric liquid-crystalline dispersion (CLD) of DNA. The appearance of a positive band in the absorption region of ligand chromophores in the CD spectrum of the DNA CLD indicates the formation of a DBBI-DNA complex in which ligand chromophores are arranged at an angle close to 54° relative to the helix axis of DNA, which suggests the localization of the DBBI in the narrow groove of DNA. All the DBBIs were found to be in vitro inhibitors of HIV-1 DNA integrase in the 3′-processing reaction, and, of the three DBBIs, two dimers inhibit HIV-1 integrase even in submicromolar concentrations.     

Energetic aspects of CO oxidation in desulfovibrio desulfuricans

In cell suspension of Desulfovibrio desulfuricans B-1388, oxidation of CO as the only energy source is associated with reduction of SO42-. After a 2-h incubation of cells in 8% CO, 81% of the gas is converted. Oxidation of 1 mole CO results in formation of 0.23 mole H2S. Intracellular ATP content increases from 2.5 (control) to 8.3 nmoles/mg (during CO conversion). Dinitrophenol inhibits sulfate reduction and CO oxidation. CO dehydrogenase was detected in cytoplasmic and membrane cell fractions (59 and 34%, respectively).