Monoclonal antibody of IgG isotype against a cross-reactive lipopolysaccharide epitope of Chlamydia and Salmonella Re chemotype enhances infectivity in L-929 fibroblast cells

A murine monoclonal antibody (MAb) 202D7 of IgG3 isotype recognizes a lipopolysaccharide (LPS) epitope of Chlamydia spp. and cross-reacts with the Re chemotype LPS of Salmonella and Escherichia coli. The antibody exhibits strong complement activating properties and stimulates phagocytosis of Salmonella enterica serovar Minnesota Re mutant by murine macrophages. Salmonella Re mutants are non-invasive for cell monolayers but still can enter and replicate in L-929 murine fibroblast cells. The entry of bacteria within the cells increases five-fold in the presence of MAb 202D7. The antibody mediates attachment and enhances five-fold the infectivity of Chlamydia pneumoniae into L-929 cells, which suggests a possible IgG-mediated mechanism of entry and survival of the pathogen in fibroblast cells.     

Removal of heavy metals from aqueous solution using Rhizopus delemar mycelia in free and polyurethane-bound form

This study assesses the ability of mycelia of Rhizopus delemar (both free and immobilized on polyurethane foam) to remove heavy metals from single-ion solutions as well as from a mixture of them. All experiments were conducted using 0.5-5 mm solutions of CuSO4 x 5H2O, CoCl2-6H2O and FeSO4 7H2O. Mycelia immobilized on polyurethane foam cells showed some times increase in uptake compared with that of free cells. Metal ions accumulation from a mixed solution was decreased slightly for cobalt and iron and considerable for copper ions. Heavy metal uptake was examined in the immobilized column experiments and more than 92% heavy metal removal (mg heavy metals removed/mg heavy metals added) from a mixed solution was achieved during the 5 cycles. During these experiments, the dry weight of the immobilized cells was decreased by only 2%. These results showed that immobilized mycelia of Rhizopus delemar can be used repeatedly for removal of heavy metals from aqueous solutions.     

Ion temperature profiles along a hydrogen diagnostic beam in a TORE SUPRA tokamak plasma

The active particle diagnostic technique is used to study the ion temperature at five spatial points along the path of a hydrogen diagnostic beam. The temperature of the main ion plasma component (deuterium ions) measured by this diagnostic technique along the beam path is compared with the temperature of carbon ions (C⁺⁵). A study is made of the following characteristic features of the behavior of the ion temperature profiles T_i in various TORE SUPRA operating modes: the formation of flat and even hollow T_i profiles in ohmic discharges with q ～3 at the plasma edge, the change in T_i profiles in ergodic divertor discharges, and the difference between the temperature of the bulk ions measured by the active particle diagnostic technique and the temperature of C⁺⁵ ions in the plasma region r/a>0.5. The features revealed are explained at a qualitative level.     

Size matters: non-LTR retrotransposable elements and ectopic recombination in Drosophila

The Drosophila melanogaster genome contains approximately 100 distinct families of transposable elements (TEs). In the euchromatic part of the genome, each family is present in a small number of copies (5-150 copies), with individual copies of TEs often present at very low frequencies in populations. This pattern is likely to reflect a balance between the inflow of TEs by transposition and the removal of TEs by natural selection. The nature of natural selection acting against TEs remains controversial. We provide evidence that selection against chromosome abnormalities caused by ectopic recombination limits the spread of some TEs. We also demonstrate for the first time that some TE families in the Drosophila euchromatin appear to be only marginally affected by purifying selection and contain many copies at high population frequencies. We argue that TEs in these families attain high population frequencies and even reach fixation as a result of low family-wide transposition rates leading to low TE copy numbers and consequently reduced strength of selection acting on individual TE copies. Fixation of TEs in these families should provide an upward pressure on the size of intergenic sequences counterbalancing rapid DNA loss through small deletions. Copy-number-dependent selection on TE families caused by ectopic recombination may also promote diversity among TEs in the Drosophila genome.     

Evolution of genome size: new approaches to an old problem

Eukaryotic genomes come in a wide variety of sizes. Haploid DNA contents (C values) range > 80,000-fold without an apparent correlation with either the complexity of the organism or the number of genes. This puzzling observation, the C-value paradox, has remained a mystery for almost half a century, despite much progress in the elucidation of the structure and function of genomes. Here I argue that new approaches focussing on the genetic mechanisms that generate genome-size differences could shed much light on the evolution of genome size.     

Pseudogene evolution and natural selection for a compact genome

Pseudogenes are nonfunctional copies of protein-coding genes that are presumed to evolve without selective constraints on their coding function. They are of considerable utility in evolutionary genetics because, in the absence of selection, different types of mutations in pseudogenes should have equal probabilities of fixation. This theoretical inference justifies the estimation of patterns of spontaneous mutation from the analysis of patterns of substitutions in pseudogenes. Although it is possible to test whether pseudogene sequences evolve without constraints for their protein-coding function, it is much more difficult to ascertain whether pseudogenes may affect fitness in ways unrelated to their nucleotide sequence. Consider the possibility that a pseudogene affects fitness merely by increasing genome size. If a larger genome is deleterious--for example, because of increased energetic costs associated with genome replication and maintenance--then deletions, which decrease the length of a pseudogene, should be selectively advantageous relative to insertions or nucleotide substitutions. In this article we examine the implications of selection for genome size relative to small (1-400 bp) deletions, in light of empirical evidence pertaining to the size distribution of deletions observed in Drosophila and mammalian pseudogenes. There is a large difference in the deletion spectra between these organisms. We argue that this difference cannot easily be attributed to selection for overall genome size, since the magnitude of selection is unlikely to be strong enough to significantly affect the probability of fixation of small deletions in Drosophila.     

The action of a preparation of Escherichia coli M-17 growth autostimulants (Actoflor) on the growth of pure and mixed bacterial cultures

The effect of the preparation of E. coli M-17 low-molecular exometabolites (Actoflor), containing growth autostimulators, on the growth of pure cultures of E. coli M-17 E. coli K-12, Salmonella enteritidis, Serratia marcescens and Bifidobacterium adolescentis MC-42 was studied. This preparation was shown to stimulate the growth of all above-mentioned bacteria. The addition of Actoflor also led to the acceleration of growth in the cultivation of mixed cultures of E. coli M-17 with E. coli K-12 (or S. enteritidis), the producer strain (E. coli M-17) showing the highest degree of acceleration. Moreover, the action of Actoflor led to the elimination of competitor strains and to the increase of the antagonistic activity of E. coli M-17. Actoflor may be supposedly used as a therapeutic or prophylactic remedy.     

Mathematical modeling the kinetics of cell distribution in the process of ligand-receptor binding

A statistical approach is presented to model the kinetics of cell distribution in the process of ligand-receptor binding on cell surfaces. The approach takes into account the variation of the amount of receptors on cells assuming the homogeneity of monovalent binding sites and ligand molecules. The analytical expressions for the kinetics of cell distribution have been derived in the reaction-limited approximation. In order to demonstrate the applicability of the mathematical model, the kinetics of binding the rabbit, anti-mouse IgG with Ig-receptors of the murine hybridoma cells has been measured. Anti-mouse IgG was labeled with fluorescein isothiocyanate (FITC). The kinetics of cell distribution on ligand-receptor complexes was observed during the reaction process by real-time measuring of the fluorescence and light-scattering traces of individual cells with the scanning flow cytometer. The experimental data were fitted by the mathematical model in order to obtain the binding rate constant and the initial cell distribution on the amount of receptors.     

High rate of DNA loss in the Drosophila melanogaster and Drosophila virilis species groups

We recently proposed that patterns of evolution of non-LTR retrotransposable elements can be used to study patterns of spontaneous mutation. Transposition of non-LTR retrotransposable elements commonly results in creation of 5' truncated, "dead-on-arrival" copies. These inactive copies are effectively pseudogenes and, according to the neutral theory, their molecular evolution ought to reflect rates and patterns of spontaneous mutation. Maximum parsimony can be used to separate the evolution of active lineages of a non-LTR element from the fate of the "dead-on-arrival" insertions and to directly assess the relative frequencies of different types of spontaneous mutations. We applied this approach using a non-LTR element, Helena, in the Drosophila virilis group and have demonstrated a surprisingly high incidence of large deletions and the virtual absence of insertions. Based on these results, we suggested that Drosophila in general may exhibit a high rate of spontaneous large deletions and have hypothesized that such a high rate of DNA loss may help to explain the puzzling dearth of bona fide pseudogenes in Drosophila. We also speculated that variation in the rate of spontaneous deletion may contribute to the divergence of genome size in different taxa by affecting the amount of superfluous "junk" DNA such as, for example, pseudogenes or long introns. In this paper, we extend our analysis to the D. melanogaster subgroup, which last shared a common ancestor with the D. virilis group approximately 40 MYA. In a different region of the same transposable element, Helena, we demonstrate that inactive copies accumulate deletions in species of the D. melanogaster subgroup at a rate very similar to that of the D. virilis group. These results strongly suggest that the high rate of DNA loss is a general feature of Drosophila and not a peculiar property of a particular stretch of DNA in a particular species group.      

MACROSCOPIC OBSERVATIONS OF THE FACIAL MUSCLES IN THE BAIKAL SEAL (PHOCA SIBIRICA)

This study was performed to determine if, as expected, the enlarged eye of the Baikal seal ( Phoca sibirica ) has an influence on the form and function of the skull and facial muscles. Macroscopic observation of these muscles demonstrated that the M. orbicularis oculi expands around the palpebral fissure and that some facial muscles attach and insert in the M. orbicularis oculi , possibly supporting M. orbicularis oculi function. We suggest that these muscles move the eye and palpebral area and constitute a morphological and synergistic facial muscle complex system. Further, the development of the M. rectus lateralis around the sclera of the eye indicates that this muscle is also involved in eye movement.