New ichnotaxon Megascolytinus zherikhini (Coleoptera: Curculionidae: Scolytinae) from upper cretaceous deposits of mongolia

Gallery systems of Scolytinae on a petrified Araucaria trunk fragment from the Late Cretaceous of Gobi, Mongolia, similar to those of extant members of the supertribe Hylesininae, but exceptionally large (estimated body length of the beetle about 20 mm), are described as a new ichnotaxon, Megascolytinus zheriknini.     

Minor shift in background substitutional patterns in the Drosophila saltans and willistoni lineages is insufficient to explain GC content of coding sequences

Background  

Several lines of evidence suggest that codon usage in the Drosophila saltans and D. willistoni lineages has shifted towards a less frequent use of GC-ending codons. Introns in these lineages show a parallel shift toward a lower GC content. These patterns have been alternatively ascribed to either a shift in mutational patterns or changes in the definition of preferred and unpreferred codons in these lineages.     

Studien über die Funktion der im Wasser gelösten Nährsubstanzen im Stoffwechsel der Wassertiere

Ohne Zusammenfassung     

Investigation of the helicon discharge plasma parameters in a hybrid RF plasma system

Results of an experimental study of the helicon discharge plasma parameters in a prototype of a hybrid RF plasma system equipped with a solenoidal antenna are described. It is shown that an increase in the external magnetic field leads to the formation of a plasma column and a shift of the maximum ion current along the discharge axis toward the bottom flange of the system. The shape of the plasma column can be controlled via varying the configuration of the magnetic field.     

EDTA reduces heavy metal impacts on Tribulus terrestris photosynthesis and antioxidants

The effects of EDTA application to heavy metal-polluted soil on phytoextraction of heavy metals, leaf anatomy, gas exchange parameters, enzyme activities of C₄ carbon cycle, antioxidant defense, and active compounds of Tribulus terrestris L. were evaluated. The addition of EDTA to the soil polluted with Cd and Pb markedly increased dry weight and Pb, Zn, and Cd contents in shoots. Plants responded to the action of EDTA by an increased stomatal conductance, photosynthetic and transpiration rates, water use efficiency, chlorophyll and carotenoid contents. The activities of C₄ carbon cycle enzymes simultaneously increased, thus concentrating CO₂ for enhanced CO₂ assimilation and providing NADPH for the antioxidant system. Antioxidants, such as ascorbate, reduced glutathione, and flavonoids, increased more in the shoots of T. terrestris after the addition of EDTA. The activities of guaiacol peroxidase, catalase, and the enzymes of the ascorbate-glutathione cycle enhanced significantly in the presence of EDTA. Increased activities of antioxidant enzymes suggest that they have some additive functions in the mechanism of metal tolerance. EDTA application lowered the activity of phenylalanine ammonia-lyase and the content of total phenols, MDA, hydrogen peroxide, dehydroascorbate, and lipid-soluble antioxidant capacity expressed as α-tocopherol. Increased levels of total radical-scavenging activity are in correspondence with the activity of water-soluble antioxidant compounds in T. terrestris tissues. The content of furostanol saponins protodioscin, prototribestin, and rutin increased as a result of EDTA addition. The results obtained allowed us to assume that applied EDTA reduced a negative heavy metal impact on puncture vine photosynthesis and antioxidant potential.     

Genomewide spatial correspondence between nonsynonymous divergence and neutral polymorphism reveals extensive adaptation in Drosophila

The effect of recurrent selective sweeps is a spatially heterogeneous reduction in neutral polymorphism throughout the genome. The pattern of reduction depends on the selective advantage and recurrence rate of the sweeps. Because many adaptive substitutions responsible for these sweeps also contribute to nonsynonymous divergence, the spatial distribution of nonsynonymous divergence also reflects the distribution of adaptive substitutions. Thus, the spatial correspondence between neutral polymorphism and nonsynonymous divergence may be especially informative about the process of adaptation. Here we study this correspondence using genomewide polymorphism data from Drosophila simulans and the divergence between D. simulans and D. melanogaster. Focusing on highly recombining portions of the autosomes, at a spatial scale appropriate to the study of selective sweeps, we find that neutral polymorphism is both lower and, as measured by a new statistic Q(S), less homogeneous where nonsynonymous divergence is higher and that the spatial structure of this correlation is best explained by the action of strong recurrent selective sweeps. We introduce a method to infer, from the spatial correspondence between polymorphism and divergence, the rate and selective strength of adaptation. Our results independently confirm a high rate of adaptive substitution (approximately 1/3000 generations) and newly suggest that many adaptations are of surprisingly great selective effect (approximately 1%), reducing the effective population size by approximately 15% even in highly recombining regions of the genome.     

Comparative analysis of diffusive and stress induced nutrient transport efficiency in the lacunar-canalicular system of osteons

Marker migration experiments suggest that cyclic mechanical loading of cortical bone in vivo increases marker penetration into bone. Is this a result of stress induced fluid flow or of stress stimulation of active transport processes? Active lacunar-canalicular transport of nutrients was suggested by Ham in 1979 on the basis of the presence of actin filaments in osteocyte processes and their suspected role in cell motility. In addition, Tanaka in 1984 observed active transport of microperoxidase in bone and Tanaka-Kamioka et al. in 1998 observed experimentally that osteocyte processes are able to actively change their form. In this study we performed parametric and comparative analyses of the transport efficiencies of diffusion and stress generated fluid flow of (glucose) nutrients in lacunar-canalicular systems in cortical bone. The result obtained is that neither diffusion nor stress induced fluid flow is capable of sustaining osteocyte viability. It is possible that cyclic stress stimulates an active nutrient transport mechanism to supplement stress flows.     

Individual variability in the karytype of Chironomus plumosus: atypical puffs in larva from a natural population from the Chita region

Atypical puffing of polytene chromosomes of Chironomus plumosus (1 larvae, IV stage) from the Ivan lake in Chita region, southern part of Siberia, has been described. At the sites of ordinary localization of interdisks and puff-patterns typical of Ch. plumosus the puffs in our material displayed different levels of activity: from a light vacuolous spot to puffs of class 5. Most of these puffs were revealed in Ch. plumosus for the first time, namely, puffs IA10a-r, IB12v-y + 13a-d, IIC14p-z + 15a-z + 16a-e, IIC14p-z + 15a-h, IID14a-m + 13s-w, IID11-2a-d, IID1p-x + 2a-d, IIIE3g-a and IIIF13h-p + 14a-e. Some other puffs, such as IB16a-k, IB15m-r + 16a-m, IB21a-o, IIC20, IVG6 and IVG7, were described earlier (Maksimova, 1979, 1983). The majority of observed puffs turned out to be heterozygous. Only one puff-knob, IIIE3g-a of class 5 activity, was found in all cells of the studied salivary glands. Its origin may be due to the appearance of heterozygoous inversion pluE1.2. All other puffs were observed in some part of cells. It is supposed that the appearance of larvae with unusually high functional activity of chromosomes may be presumably induced by stress influence of certain environmental factors.     

DNA-protein cross-links as a possible reason for genomic damage during its protonation]

The change in survival of bacteriophages with DNA of different GC-contents after their incubation in media of different acidities with subsequent neutralization was studied. It was shown that the higher the GC-content, the more sensitive is the phage to the action of H(+)-ions. Evidence is presented that the acidic inactivation of virions is not connected with the helix-coil transition of the intraphage DNA due to its protonation. The extractability of DNA from phages subjected to different concentrations of H(+)-ions with subsequent neutralization of the medium to pH 8 was determined. The changes in: transfection ability, UV-spectra, the quantity of the residual proteins, and the contents of glutamic and lysine amino acid residues in these proteins were investigated. The effect of glutamic acid on the parameters of DNA melting curves was followed for different pH values. Proceeding from the data obtained, we concluded that acidification of the medium from neutral tp pH congruent to 4 leads to formation of non-covalent DNA-protein cross-links due to interaction of the GC base pairs of DNA with glutamic and aspartic amino acid residues, whereas acidification of the medium to pH less than 4 with subsequent neutralization to pH 8 results in the formation of covalent DNA-protein cross-links of Schiff base type. The influence of non-covalent DNA-protein cross-links on the properties of DNA and their regulatory role in genome functioning are discussed.     

Regulatory functions of bacterial exometabolites

This review deals with the issue of growth autoregulation and survival in bacterial cultures under starvation conditions. Based on our results and on published data, the conclusion has been drawn that low-molecular products of metabolism (carboxylic acids, amino acids, and other metabolites) perform regulatory functions. The same compounds also control the ecological relationship between microorganisms at the interspecific level, and affect their antagonistic activity. It is suggested that complexes of bacterial metabolites can be used for controlling the composition of various microbiocenosis, including those of humans.