Anchusa—Mosaic caused by TMV-infection in nature

Mosaic disease ofAnchusa officinalis found at a ruderal association in Prague-Hole?ovice in the close proximity of TMV infected cruciferous weedsCardaria draba andSisymbrium loeselii, was identified to be caused by the same agent—the necrotic TMV-strain.     

Natural infections ofSisymbrium loeselii Jusl. with cabbage black ringspot and tobacco mosaic viruses

Investigating weeds for viruses in ruderal localities of Greater Prague two forms of mosaic diseases inSisymbrium loeselii Jusl. were demonstrated (green and yellowish-green mosaic). Transmission tests carried out on differential host plants showed that the green mosaic is caused by cabbage black ringspot virus (CBRV) and the yellowish green by mixed infection of CBRV and tobacco mosaic virus (TMV). TMV—isolate is characterized as an unusual necrotic strain; its capability to reproduce in cruciferous plant in nature is unique. It was ascertained that green mosaic was commonly spread overSisymbrium plants in ruderal ***DIRECT SUPPORT *** A01GP029 00004 associations on Prague territory; epidemiological significance of this discovery is discussed.     

Aluminium cycling in the soil-plant-animal-human continuum

A critical review of the literature on Al toxicity in plants, animals and humans reveals a similar mode of Al action in all living organisms, namely interference with the secondary messenger system (phosphoinositide and cytosolic Ca²⁺ signalling pathways) and enhanced production of reactive oxygen species resulting in oxidative stress. Aluminium uptake by plants is relatively quick (across the intact plasma membrane in < 30 min and across the tonoplast in < 1 h), despite huge proportion of Al being bound in the cell wall. Aluminium absorption in the animal/human digestive system is low (only about 0.1% of daily Al intake stays in the human body), except when Al is complexed with organic ligands (eg. citrate, tartarate, glutamate). Aluminium accumulates in bones and brain, with Al-citrate and Al-transferrin complexes crossing the blood-brain barrier and accumulating in brain cells. Tea plant and other Al-accumulator plant species contain large amounts of Al in the form of non-toxic organic complexes.     

Combined effects of waterlogging and salinity on electrochemistry, water-soluble cations and water dispersible clay in soils with various salinity levels

The combination effects of waterlogging and salinity on redox potential (Eh), pH, electric conductivity (EC), water-soluble cations (NH₄ ⁺, K⁺, Na⁺, Ca²⁺, Mg²⁺, Fe²⁺, and Mn²⁺) and water-dispersible clay (WDC) were studied in six soils collected near salt lakes in western Australia. The soils with various salinity levels were incubated under a waterlogged condition at 30 °C for 12 weeks. The Eh, pH, EC, and cations of soil solutions were monitored over the waterlogged period. The Eh values generally dropped to the lowest point within 12 days of waterlogging, then increased slightly, and reached equilibrium after 4 weeks of waterlogging. Increasing salinity levels increased soil Eh. While waterlogging increased soil pH in the first 3–4 weeks, increasing salinity level decreased soil pH during the entire waterlogging period. Waterlogging increased the EC values in the first 2 weeks, partly due to dissolution of insoluble salts. The concentrations of water-soluble NH₄ ⁺ were significantly increased with salinity level and waterlogging, and reached maximum values at week 2, and then declined to the initial level. Waterlogging and salinity increased the concentrations of water-soluble K⁺, Ca²⁺, Mg²⁺, Fe²⁺, and Mn²⁺ ions, but the magnitudes of changes were greatly affected by soil properties. Increases in water-soluble K⁺, Ca²⁺ and Mg²⁺ were attributed to increased solubility of insoluble salts, and increased competition for the adsorption sites of the soil exchange complex due to elevated concentrations of Na⁺, Fe²⁺ and Mn²⁺. Increases in water-soluble Fe²⁺ and Mn²⁺ induced by waterlogging were attributed to the dissolution of Fe and Mn oxides under reduced conditions. Waterlogging increased, but salinity decreased, the amounts of water-dispersible clay in the soils of low EC value. The higher salinity level can counteract the adverse effect of waterlogging on clay flocculation.     

Developmental and transplacental genotoxicology: fluconazole

Over the last 40 years mankind has been facing new types of radiochemical environmental settings with every decade. During the last decade, biomonitoring was additionally focused on assessing associations between environmental exposure(s) and both early and late biological effects in children. Despite efforts to control and avoid child exposure to genotoxic agents the incidence of childhood cancers is increasing. Some cancers in adulthood may be the consequence of a multi-step process which starts with intrauterine and childhood exposure. This highlights the importance of a comprehensive interpretation of multiple health effects, especially considering recent studies suggesting that most health disorders are related to DNA changes. When exposed to genotoxic agents, a developing organism (fetus or child) is constantly being forced to reorganize into new equilibriums in order to adjust to a xenobiotic environment. In addition, the influence of sex hormones on radiochemical sensitivity is still unknown. For this reason special attention should be paid to puberty. The results of recent studies on animal models and follow up studies on children after nuclear accidents show long-lasting cytogenetic damage even after low dose exposures and their transgenerational persistance. To evaluate age-related difference and transplacental genotoxic potency fluconazole (FC) was investigated by in vivo micronucleus (MN) assay in adult mice, young mice and in transplacentally exposed newborn pups. Compared to the baseline values, FC caused no detectable genome damage in adult animals, but there was a significant increase in MN frequency in young animals and in newborn pups. Our study thus exemplifies an age-related chemosensitivity, and argues that cancer-promoting disturbances of complex prenatal developmental mechanisms and maturation during childhood require a new approach using systems biology.     

The cyclic nucleotide-gated channel, AtCNGC10, influences salt tolerance in Arabidopsis

Cyclic nucleotide-gated channels (CNGCs) in the plasma membrane transport K+ and other cations; however, their roles in the response and adaptation of plants to environmental salinity are unclear. Growth, cation contents, salt tolerance and K+ fluxes were assessed in wild-type and two AtCNGC10 antisense lines (A2 and A3) of Arabidopsis thaliana (L.) Heynh. Compared with the wild-type, mature plants of both antisense lines had altered K+ and Na+ concentrations in shoots and were more sensitive to salt stress, as assessed by biomass and Chl fluorescence. The shoots of A2 and A3 plants contained higher Na+ concentrations and significantly higher Na+/K+ ratios compared with wild-type, whereas roots contained higher K+ concentrations and lower Na+/K+ ratios. Four-day-old seedlings of both antisense lines exposed to salt stress had smaller Na+/K+ ratios and longer roots than the wild-type. Under sudden salt treatment, the Na+ efflux was higher and the K+ efflux was smaller in the antisense lines, indicating that AtCNGC10 might function as a channel providing Na+ influx and K+ efflux at the root/soil interface. We conclude that the AtCNGC10 channel is involved in Na+ and K+ transport during cation uptake in roots and in long-distance transport, such as phloem loading and/or xylem retrieval. Mature A2 and A3 plants became more salt sensitive than wild-type plants because of impaired photosynthesis induced by a higher Na+ concentration in the leaves.     

Characteristics of hepatitis C infection in injecting drug users in Zadar County, Croatia

The aim of the study was to determine additional risk factors that could increase the prevalence of hepatitis C (HCV) infection among injecting drug users (IDU). The study included 327 heroin addicts registered in Zadar County, Croatia. The participants were divided into two groups according to their HCV status. HCV-positive and HCV-negative study participants were compared. HCV-positive group started injecting heroin at earlier age (median 18.5 years) than HCV-negative group (median 20.0 years) (p = 0.032) and had been injecting heroin for a significantly longer period (median 5 years vs. median 4 years, respectively; p < 0.001). IDUs in HCV-positive group shared their injecting equipment significantly more often than IDUs in HCV-negative group (p < 0.001; chi2 = 32.7). The main reasons for starting drugs were curiosity, psychological reasons (depression and/or neurosis), and peer or partner pressure in HCV-positive group, and fun, curiosity, and peer pressure in HCV-negative group (p = 0.051; chi2 = 23.6). Earlier onset of heroin use, longer heroin use, sharing injection equipment, curiosity, and psychological problems as reasons for starting drugs were associated with higher prevalence of HCV infection among injecting heroin users in Zadar County.     

Influence of phenolic acids on phosphorus mobilisation in acidic and calcareous soils

Phenolic acids and phenols are abundant in soils. However, little information is available on the role of these compounds in mobilisation of soil phosphorus (P). The present study examined the effects of three phenolics on P mobilisation in comparison with citric acid in three soils differing in chemical properties. The soils were incubated with organic compounds at concentrations of 0 to 100 mol g^–1 soil for 30 min. While the addition of phenolic acid anions and phenol decreased soil pH, citrate either increased or did not affect soil pH depending on the soil type. All the organic compounds increased the amounts of easily-mobilised P fractions in the order of catechol citric acid proto-catechuic acid caffeic acid for the acid soils and citric acid > catechol = proto-catechuic acid > caffeic acid for the calcareous soil. Phosphorus mobilisation did not correspond to the amounts of Ca, Fe or Al ions released from the soils. These results suggest that organic acids and phenols altered the P fractions from stable, sparingly-soluble forms to easily dissolvable forms, and that chelation or precipitation of cations with organic ligands occur before biodegradation of the ligands.     

Aluminium toxicity in rye (Secale cereale): root growth and dynamics of cytoplasmic Ca2+ in intact root tips

Aluminium (Al) toxicity in rye (Secale cereale L.), an Al-resistant crop, was examined by measuring root elongation and cytoplasmic free activity of calcium ([Ca2+]cyt) in intact root apical cells. Measurement of [Ca2+]cyt, was achieved by loading a Ca2+-sensitive fluorescent probe. Fluo-3/AM ester, into root apical cells followed by detection of intracellular fluorescence using a confocal laser scanning microscope. After 20 min of exposure to 50 microM Al (pH 4-2) a slight increase in [Ca2+]cyt of root apical cells was observed, while the response of [Ca2+]cyt to 100 microM Al (pH 4.2) was faster and larger ([Ca2+]cyt increased by 46% in 10 min). Increases in [Ca2+]cyt were correlated with inhibition of root growth, generally measurable after 2 h. Addition of 400 microM malic acid (pH 4.2) largely ameliorated the effect of 100 microM Al on [Ca2+]cyt in root apical cells and protected root growth from Al toxicity. These results suggest that an increase in [Ca2+]cyt in root apical cells in rye is an early effect of Al toxicity and is followed by the secondary effect on root elongation.     

Aluminium-induced growth inhibition is associated with impaired efflux and influx of H+ across the plasma membrane in root apices of squash (Cucurbita pepo)

It is generally understood that the inhibition of growth of root apices is the initial effect caused by aluminium (Al) toxicity. The correlation between impaired H+-fluxes across the plasma membrane (PM) and Al-induced growth inhibition, Al accumulation and callose formation in root apices of squash (Cucurbita pepo L. cv. Tetsukabuto) is reported here. The root inhibition was dependent on Al concentration, and the duration of exposure, with the damage occurring preferentially in regions with high Al accumulation and callose formation. Using the fluorescent Al indicator (Morin), Al was localized in the cell walls of the root-tip cells after 3 h and in the whole root-tip cells after 6 h of the Al treatment (50 micro M). The inhibition of H+-pumping rate in the highly purified PM vesicles obtained from the Al-treated apical root portions (1 cm) coincided with the inhibition of root growth under Al stress. Furthermore, H+-ATPase activity of PM vesicles prepared from the control root apices was strongly inhibited by Al in vitro in a dose-dependent manner. Approximately 50% inhibition was observed when PM vesicles were preincubated at Al concentration as low as 10 micro M followed by the enzyme assay in the medium without Al. Using the pH indicator (bromocresol purple), it is shown that surface pH of the control (0 Al) root apices was strongly alkalized from the starting pH of 4.5 in a time-dependent manner. By contrast, the surface pH changed only slightly in the Al-treated root apices. The changes in surface pH mediated by altered dynamics of H+ efflux and influx across the root tip PM play an important role in root growth as affected by Al.