Ultrastructure and hydrolase activity in tobacco leaves exposed to chitosan

The mesophyll ultrastructure and hydrolase activity in leaves of tobacco cv. Samsun exposed to chitosan were studied. It was shown that, in many cells, chitosan treatment stimulated the protein-synthesizing apparatus (nucleolus size and amount of both mitochondria and membranes of rough endoplasmic reticulum increased). At the same time, we observed activation of the lytic compartment displayed as stimulated production of dictyosomes, smooth ER elements, and cytoplasmic vacuoles, which are prominent constituents of this compartment. Biochemical experiments showed that, in the leaves, chitosan substantially enhanced activity of hydrolases (acid phosphatase, RNase, proteases) as compared to untreated leaves. In some cells, chitosan treatment caused considerable destructive changes (condensation of nuclear chromatin, collapse of cytoplasm, etc.) that can be classified as development of programmed cell death.     

Divergence of the seasonal races of chum salmon, <Emphasis Type="Italic">Oncorhynchus keta</Emphasis> Walbaum, 1792, in the Amur and Poronai rivers: Ecology,genetics, and morphology

The chum salmon of the Amur River (the mainland part of the Far East) and the Poronai River (Terpeniya Bay, Sakhalin Island) are historically related to one another, as the drainage basins of these rivers are the remnants of a formerly single river system, the Paleoamur, which existed when Sakhalin Island was a part of the continent. Both river populations of chum salmon consist of the early-run and late-run ecological forms (seasonal races), which are also referred to as the summer and autumn races. They are reproductively isolated from each other due to their spawning at different times and in different types of spawning grounds. To assess the direction, pattern, and degree of divergence between these chum salmon races in the both river fragments since the Paleoamur, it is necessary to compare them using two types of traits: selectively neutral DNA markers and morphological and physiological traits, variations in which may have an adaptive value. For this, we have studied chum salmon from both rivers in terms of microsatellite DNA markers, body counts and measurements, body weight, and fecundity. Both in the Amur River and in the Poronai River, the autumn race of chum salmon prevails over the summer race in body length and weight, fecundity, number of pyloric caeca, and several other meristic traits. The intra-basin differences between the races are much more pronounced in the Amur chum salmon. The inter-race differences in microsatellites are also greater in the Amur chum salmon compared to the Poronai chum salmon. Using microsatellites, three levels of differentiation have been revealed: (1) between the basins of the Amur and Poronai rivers, (2) between the races within each of the river basins, (3) and between population samples within each race of each basin. A hypothesis is proposed that the currently existing races of chum salmon in the Amur and Poronai rivers have evolved since the breakup of the Paleoamur, and the intra-basin divergence of the races started in the Amur River earlier than in the Poronai River. An analysis of our own data and the published data suggests that the adaptation of the seasonal races of chum salmon to the conditions of their spawning grounds is determined by a complex of morphological and physiological traits, including the number of pyloric caeca, which is an adaptive and highly heritable trait associated with the incubation temperature of the water.     

Large deletion on the Y-chromosome long arm (Yq) of C57BL/6JBomTac inbred mice

Mammalian Genome - The Y-chromosome of mice has a crucial role in sex determination, gender ratio equilibrium as well as male fertility, and is moreover involved in behavioral, immunological, and...     

Influence of κ/β-carrageenan from red alga <Emphasis Type="Italic">Tichocarpus crinitus</Emphasis> on development of local infection induced by tobacco mosaic virus in Xanthi-nc tobacco leaves

The influence of κ/β-carrageenan from red marine alga Tichocarpus crinitus on the development of tobacco mosaic virus (TMV) infection in Xanthi-nc tobacco leaves was studied. It was shown that the number of necrotic lesions on the leaves inoculated with the mixture of TMV (2 μg/ml) and carrageenan (1 mg/ml) was reduced by 87%, compared to the leaves inoculated with the virus only. The suppression of virus infection was also observed when leaves were treated with carrageenan 24 h before or 24 h after leaf inoculation with TMV; however, in these cases, suppression was less evident than after inoculation with the virus-polysaccharide mixture. It is supposed that the antiviral activity of carrageenan applied together with TMV may be explained by its action not only on the plant but also on the virus itself. The inhibitory effect of carrageenan pretreatment can be explained by its favorable effect on tissue resistance to infection. The suppression of this resistance by actinomycin D indicates that carrageenan functions via its action on the cell genome.     

Early Temporal Changes in Ecto-Nucleotidase Activity after Cortical Stab Injury in Rat

During a variety of insults to the brain adenine nucleotides are released in large quantities from damaged cells, triggering multiple cellular responses to injury. Here, we evaluated changes in extracellular ATP, ADP and AMP hydrolysis at different times (0–24 hours) after unilateral cortical stab injury (CSI) in adult rats. Results demonstrated that 24 hours following CSI, ATP and ADP hydrolyzing activities were not significantly altered in injured cortex. Based on calculated V _ATP/V _ADP ratio it was concluded that ATP/ADP hydrolysis was primarily catalyzed by NTPDase1 enzyme form. In contrast, AMP hydrolysis, catalyzed by 5’-nucleotidase, was significantly reduced at least 4 hours following CSI. Kinetic analysis and Lineweaver-Burk transformation of the enzyme velocities obtained over the range of AMP concentrations (0.05–1.50 mM) revealed that inhibition of 5’-nucleotidase activity after CSI was of the uncompetitive type. Taken together our data suggest that injured tissue has reduced potential for extracellular metabolism of adenine nucleotides in early stages after CSI.     

Labeling, characterization, and in vivo localization of a new 90Y-based phosphonate chelate 2,3-dicarboxypropane-1,1-diphosphonic acid for the treatment of bone metastases: Comparison with 99mTc-DPD complex

The goal of this investigation was to examine the possibilities for yttrium-90-labeling of the 2,3-dicarboxypropane-1,1-diphosphonic acid (DPD), which is currently labeled with technetium-99m and as a (99m)Tc-DPD clinically used as bone imaging agent. Analysis of the complex enclosed the radiochemical quality control methods, biodistribution studies, as well as the determination of pharmacokinetic parameters. The biological behavior of complexes (90)Y-DPD, (99m)Tc-DPD and (90)Y-labeled DPD-kit formulation [(90)Y-(Sn)-DPD] in animal model was compared. The labeling conditions were standardized to give the maximum yield, which ranged between 93% and 98%. The examined (90)Y complex could be easily prepared, with an outstanding yield and was also found to be very stable for at least 10h after (90)Y-labeling. Protein binding value was 4.6+/-0.7% for (90)Y-DPD complex and the complex possess a hydrophilic character. The satisfactory results of (90)Y-DPD biodistribution in healthy test animals were obtained; the uptake in the bone was 11-13%ID/g after 24h depending on the pH value during the preparation. With high skeletal uptake, a minimum uptake in soft tissues and rapid blood clearance the (90)Y-DPD complex proved to be an excellent candidate for targeting tumor therapy.     

Influence of cyclopentane beta,beta'-triketones on the ultrastructure of root cap meristematic cells of Cucumis sativus L. seedlings

The influence of cyclopentane beta,beta'-triketones on the ultrastructure of root cap meristematic cells of Cucumis sativus L. under inhibition of root growth by these compounds was studied. It was shown that treatment of the seedlings by these substances at the concentration of 100 microg/ml caused, on the one hand, stimulation of protein-synthesizing apparatus (increase in the nucleolus size and in the number of mitochondria and rough endoplasmic reticulum membranes) and, on the other hand, stimulation of lytic processes. The fact that the used compounds, causing inhibition of the seedling growth, do not suppress but stimulate protein-synthesizing activity of the cells, according to existing concept, testifies to the compound-mediated induction of the cell resistance to unfavourable factors. Consequently, these compounds, in contrast with growth inhibitors suppressing cell metabolism completely, possess properties peculiar to retardants, growth inhibitors valuable for crop production.     

The mammalian pannexin family is homologous to the invertebrate innexin gap junction proteins

We have cloned the genes PANX1, PANX2 and PANX3, encoding putative gap junction proteins homologous to invertebrate innexins, which constitute a new family of mammalian proteins called pannexins. Phylogenetic analysis revealed that pannexins are highly conserved in worms, mollusks, insects and mammals, pointing to their important function. Both innexins and pannexins are predicted to have four transmembrane regions, two extracellular loops, one intracellular loop and intracellular N and C termini. Both the human and mouse genomes contain three pannexin-encoding genes. Mammalian pannexins PANX1 and PANX3 are closely related, with PANX2 more distant. The human and mouse pannexin-1 mRNAs are ubiquitously, although disproportionately, expressed in normal tissues. Human PANX2 is a brain-specific gene; its mouse orthologue, Panx2, is also expressed in certain cell types in developing brain. In silico evaluation of Panx3 expression predicts gene expression in osteoblasts and synovial fibroblasts. The apparent conservation of pannexins between species merits further investigation.     

A novel mouse Chr5 locus <Emphasis Type="Italic">Diht</Emphasis> controls dopamine-induced hypothermia

Mice of the strain C3H.PRI-Flv^r, carrying genetically determined resistance to flaviviruses, have been shown to be more sensitive to the hypothermic effect of dopamine than congenic flavivirus-susceptible C3H/HeJARC mice. In the current study, the greater sensitivity to dopamine-induced hypothermia observed in flavivirus-resistant mice was shown to be dose-dependent, with strain differences being the most prominent at a moderate dose of apomorphine (1 mg/kg). In addition, hypothermic responses to apomorphine were shown to be under developmental regulation; aging increased the potency of apomorphine-induced hypothermia and abrogated strain and sex differences observed in young mice. Linkage analysis of mouse strain-dependent co-inheritance between flavivirus resistance and greater sensitivity to the hypothermic effect of dopamine was performed using two genetically unrelated flavivirus-susceptible and two highly congenic flavivirus-resistant mouse strains in parallel with C3H.PRI-Flv^r-and C3H/HeJARC reference strains. This study has revealed a clear segregation between flavivirus resistance conferred by the Flv locus and sensitivity to dopamine-controlled hypothermia conferred by a novel locus, Diht. Parallel studies in F1 and F2 heterozygote mice showed that the high sensitivity to hypothermic effect of dopamine (Diht^high) is inherited as the Chr5-linked dominant trait. The novel locus, Diht, has been mapped proximal to the Flv locus on a distal part of mouse Chr5 between microsatellite markers D5Mit41 and D5Mit158.