The negative effect of magnetic nanoparticles with ascorbic acid on peritoneal macrophages

Neurochemical Research - Superparamagnetic iron oxide nanoparticles (SPIOn) are widely used as a contrast agent for cell labeling. Macrophages are the first line of defense of organisms in contact...     

Genetic mapping of thet-complex region on mouse chromosome 17 including theHybrid sterility-1 gene

t-haplotypes occupy a region on chromosome (Chr) 17 which slightly overlaps the ends of theT-H-2 interval. The wild-type form of this 14 centi-Morgan (cM) region was mapped in a multilocus backcross (C57BL/10-T×C3H)F₁×C57BL/10 using 15 DNA probes on Southern blots of the DNA extracted from 53 animals which were recombinants in theT-H-2 interval. Each recombinant was also progenytested to ascertain itsHybrid sterility-1 (Hst-1) genotype by crossing to PWB/Ph, aMus musculus-derived inbred strain. The limit of resolution of the cross was 0.27 cM. The map distances have been determined for the DNA loci in theT-H-2 interval and theHst-1 gene was mapped in close vicinity to theD17Rp17 locus.     

Hexokinases of tobacco leaves: Subcellular localization and characterization

Subeellular localization of the enzymes which phosphorylate hexoses was studied in photosynthesizing tobacco leaves by means of differential centrifugation and centrifugation in sucrose gradient. More than 80 % of the total hexokinase activity of leaf tissues were found to be associated with the particulate fraction of mitochondria; however, the ratio of the particulate hexokinase fraction to the soluble fraction was influenced by the extraction medium applied. The particulate hexokinases showed a high affinity to glucose (Km = 26.8 μM) and a relatively low affinity to fructose (Km = 17.6 mM). They had a broad pH optimum, because 81 % of the phosphorylating activity obtained for glucose and 75 % of the activity obtained for fructose occurred in pH range from 7.9 to 9.1 (Tris-HCl buffer). The hexokinases were Mg2+ dependent with the highest activity occurring at equimolar Mg2+ and ATP concentrations. Their activity was enhanced by KC1, NaCl, and (NH4)2SO4 at 30 to 120 mM concentrations.     

Caterpillar (Lepidoptera) communities on European Turkey oak (Quercus cerris) in Malé Karpaty Mts (SW Slovakia)

Between 2000–2002, the structure of communities of lepidopteran larvae was studied in leaf bearing crowns of Quercus cerris in the central and northern part of the Malé Karpaty Mts (SW Slovakia). Caterpillars were collected using the beating method in four study plots. In total, 58 species were found. The families Geometridae, Noctuidae and Tortricidae comprised the highest number of species found. The family Geometridae comprised the highest number of pests. The most abundant species for individual plots were Lymantria dispar, Operophtera brumata, Ypsolopha alpella and Cyclophora ruficiliaria. Most of the recorded species belonged to the trophic group of generalists (39 species). Shannon-Wiener’s diversity index and Pielou’s equitability (evenness) value indicated there were marked differences between the Horny háj study plot (an insular forest with ants as the predators of caterpillars) and other plots. The main ecological gradient along DCA-1 related to the host specificity of caterpillars and consisted of three groups: (a) polyphagous species; (b) specialist species feeding chiefly on oaks or exclusively on oaks and (c) species preferring some oak species, mainly Q. cerris. The fragmentation of growth was identified along DCA-2.     

Auxin transport at cellular level: new insights supported by mathematical modelling

The molecular basis of cellular auxin transport is still not fully understood. Although a number of carriers have been identified and proved to be involved in auxin transport, their regulation and possible activity of as yet unknown transporters remain unclear. Nevertheless, using single-cell-based systems it is possible to track the course of auxin accumulation inside cells and to specify and quantify some auxin transport parameters. The synthetic auxins 2,4-dichlorophenoxyacetic acid (2,4-D) and naphthalene-1-acetic acid (NAA) are generally considered to be suitable tools for auxin transport studies because they are transported specifically via either auxin influx or efflux carriers, respectively. Our results indicate that NAA can be metabolized rapidly in tobacco BY-2 cells. The predominant metabolite has been identified as NAA glucosyl ester and it is shown that all NAA metabolites were retained inside the cells. This implies that the transport efficiency of auxin efflux transporters is higher than previously assumed. By contrast, the metabolism of 2,4-D remained fairly weak. Moreover, using data on the accumulation of 2,4-D measured in the presence of auxin transport inhibitors, it is shown that 2,4-D is also transported by efflux carriers. These results suggest that 2,4-D is a promising tool for determining both auxin influx and efflux activities. Based on the accumulation data, a mathematical model of 2,4-D transport at a single-cell level is proposed. Optimization of the model provides estimates of crucial transport parameters and, together with its validation by successfully predicting the course of 2,4-D accumulation, it confirms the consistency of the present concept of cellular auxin transport.     

The phylogenetic position of <Emphasis Type="Italic">Obolarina dryophila</Emphasis> (Xylariales)

The inconspicuous inner-bark parasite Obolarina dryophila is reported from wood of Quercus petraea and as an endophyte of Salix alba. In addition, viable ascospores of O. dryophila have been found in the gut of the oak bark weevil Gasterocercus depressirostris, suggesting a possible dissemination mechanism for the fungus. A phylogenetic analysis based on three genes (nrDNA, actin, β-tubulin) placed Obolarina inside the genus Biscogniauxia as a close relative of the oak pathogens B. atropunctata and B. mediterranea.     

Correlation of viral RNA biosynthesis with glucose-6-phosphate dehydrogenase activity and host resistance

Changes in glucose-6-phosphate dehydrogenase (G6P DH; EC 1.1.1.49) activity caused by infection of tobacco ( Nicotiana tabacum L.) leaves with potato virus Y (PVY), cucumber mosaic virus, potato virus X, tobacco rattle virus and turnip mosaic virus, the subcellular localisation of G6P DH isozymes in mesophyll protoplasts derived from healthy and PVY-infected tobacco leaves, as well as G6P DH control and the relationship of its isozymes with the degree of tobacco resistance to PVY multiplication, were studied. The activities of G6P DH were markedly increased in locally and systemically infected leaves and the time courses of the activity linearly correlated with those of virus multiplication. In leaves infected with PVY, the activity time courses of the crude and the partially purified G6P DH were coincident. This probably indicates the involvement of coarse regulation of the enzyme. PVY content linearly correlated with enhanced G6P DH activity in leaf discs derived from susceptible, tolerant and resistant cultivars of tobacco. The increased activity of the enzyme in infected protoplasts and plant tissues was predominantly caused by the increased activity of chloroplastic isozymes. This was confirmed by the specific staining of isozymes after electrophoretic separation of chloroplastic proteins of tobacco leaves. These findings enable the degree of resistance to virus multiplication to be quantified for the use of gene manipulation and breeding.     

Chromosome numbers,C-banding patterns and sperm of some ladybird species from Central Europe (Coleoptera,Coccinellidae)

C-banded karyotypes were studied in the males of seven ladybird species from the subfamily Coccinellinae, viz. Adonia variegata (Goeze), Tythaspis sedecimpunctata (L.), Coccinella septempunctata (L.), Calvia decemguttata (L.), Calvia quatuordecimguttata (L.), Propylea quatuordecimpunctata (L.), Phyllobora vigintiduopunctata (L.). All the species, with the exception of Tythaspis sedecimpunctata (L.), possess 2n = 20, n(male) = 9 + Xy(p). Tythaspis sedecimpunctata (L.), however, has 2n = 24, n(male) = 11+Xy. The examined karyotypes show only a paracentromeric position of constitutive heterochromatin in all autosomes and the sex chromosome X, while the y heterochromosome is dot-like and wholly euchromatic. Successive stages of spermiogenesis were analysed.     

The role of growth factors in the activity of pharmacological differentiation agents.

Bryostatin-1 inhibits acute myeloid leukemia (AML) in vitroat doses that stimulate the growth of normal hematopoietic progenitors.Although bryostatin-1 has a number of distinct biological activities, those specifically responsible for its antileukemic activity are unclear. We found that bryostatin-1 (10(-8) M) inhibited cell cycling at G(1), induced phenotypic evidence of differentiation, and limited the clonogenic growth of both AML cell lines and patient specimens. This activity was markedly enhanced by granulocyte/macrophage-colony stimulating factor, whereas growth factor-neutralizing antibodies completely inhibited both the differentiating and antileukemic activities of bryostatin-1. Cell cycle inhibition and growth factors were also required for the differentiating activities of two unrelated agents, hydroxyurea and phenylbutyrate. These data suggest that many pharmacological differentiating agents require both cell cycle arrest and lineage-specific growth factors for full activity and may explain why these agents have demonstrated only limited clinical efficacy.