Environmental pollution by antibiotics poses a potential ecological risk to aquatic photosynthetic organisms. In the present study, toxic effects of erythromycin on PSI and PSII were investigated in cyanobacteria culture medium of Microcystis aeruginosa. The activity and electron transport of both photosystems were affected by erythromycin in a concentrationdependent manner. The quantum yield of PSII (YII) was reduced at 0.1 mg L-1 of erythromycin, while the quantum yield of PSI (YI) significantly decreased at concentration of 5-25 mg L-1. The decline of YII was accompanied by an increase of nonregulated energy dissipation (YNO). At 10 mg L-1 of erythromycin, YII decreased by 55%, while YNO increased by 18%. The decrease of YI induced by erythromycin was caused by donor-side limitation of PSI (YND). YND was markedly enhanced with elevated erythromycin concentration. At 10 mg L-1 of erythromycin, YI and YNA (PSI acceptor-side limitation) decreased by 8 and 82%, respectively, while YND rose by 314%. The quantum yield of cyclic electron flow increased significantly at 0.1-1 mg L-1 of erythromycin; it decreased but remained higher than that of the control at 5-25 mg L-1 of erythromycin. The contribution of cyclic electron flow to YI, and to linear electron flow rose significantly with the increasing erythromycin concentration. The maximum values of electron transport rates in PSII and PSI decreased by 71 and 24.3%, respectively, at 25 mg L-1 of erythromycin. Compared with the untreated control, the light saturation of PSII and PSI decreased significantly with increasing erythromycin concentration. We showed that concentrations of erythromycin >- 5 mg L-1 could exert acute toxicity to cyanobacteria, whereas the chronic toxicity caused by concentrations of ng or μg L-1 needs further research., C.-N. Deng, D.-Y. Zhang, X.-L. Pan., and Obsahuje bibliografii
The aim of this study was to determine the impact of increased copper contents on selected physiological processes in oneyear-old Pinus sylvestris L. needles from a former German timber storage area in Warcino Forest District, a subject to an environmental quality survey. Samples were collected from the area with the high copper content in the soil. The control area was a nearby pine tree stand showing unimpeded growth. The significant growth inhibition was found in dwarf shoots and whole needles, increased water content, and reduced dry mass were also observed. The chlorophyll content was lowered, while 20% higher electrolyte leakage was found. Chlorophyll a fluorescence indicated only higher values of the nonphotochemical quenching in P. sylvestris from the Cu-site. Significant differences were shown in the rate of gas exchange measured by changes in carbon dioxide or oxygen concentration. The intensity of photosynthesis in needles of P. sylvestris from the Cu-site measured by CO2 uptake was considerably higher than that of oxygen production. The rate of respiration in the needles from the Cu-site measured by the amount of released CO2 was higher only by 15%, while according to O2 consumed, the rate increased by 30% in relation to the control. Our results suggest that the copper accumulation in P. sylvestris needles affected the morphology and physiology of the studied organs., K. Możdżeń, T. Wanic, G. Rut, T. Łaciak, A. Rzepka., and Obsahuje bibliografii
We summarize the contemporary understanding of the effects of metal stress on various photosynthetic processes in photoautotrophic organisms and of the defence strategies employed by these organisms to avoid such stress. Cadmium is in the centre of interest of this review, as a non-essential element and important environmental pollutant, but Al, Pb, Hg, As, Cu, and Zn are also considered. Toxic metal ions pollute the environment through anthropogenic activities and affect the quality of plant crop. They represent one of the main abiotic stress factors influencing the health of plants and, as a secondary effect, of animals including man. The review summarizes the generally accepted answers to the questions: How do the toxic metal ions enter the photosynthetic organisms? How are they accumulated in plants? Which mechanisms do plants develop to tolerate metal stress and protect themselves? and T. Kučera, H. Horáková, A. Šonská.
The toxicity of cadmium and zinc at concentrations ranging from 0.1 to 100 µg/l was investigated against the activity of Diplostomum spathaceum (Rudolphi, 1819) cercariae. Over a 24 h exposure period a significant reduction in cercarial activity occurred in solutions of cadmium, zinc, and a mixture of cadmium and zinc at all concentrations. Reduced cercarial activity also occurred in all toxicant solutions compared with controls after only 6 h exposure indicating that cercariae were vulnerable during the period of maximum cercarial infectivity (0-5 h). The mechanisms of metal toxicity and their importance to parasite transmission are discussed.
Toxoplasma gondii reportedly manipulates rodent behaviour to increase transmission to its definitive feline host. We compared the effects of mouse infection by two Type II strains of T. gondii, Prugniaud (PRU) and ME49, on attraction to cat odour, locomotor activity, anxiety, sensorimotor gating, and spatial working and recognition memory 2 months post-infection (mpi). Attraction to cat odour was reassessed 7 mpi. At 2 mpi, mice infected with either strain exhibited significantly more attraction to cat odour than uninfected animals did, but only PRU-infected mice exhibited this behaviour 7 mpi. PRU-infected mice had significantly greater body weights and hyperactivity, while ME49-infected mice exhibited impaired spatial working memory. No differences in parasite antibody titres were seen between PRU- and ME49-infected mice. The present data suggest the effect of T. gondii infection on mouse behaviour is parasite strain-dependent.
A convincing body of evidence now exists, from both human and animal studies, and encompassing epidemiological to experimental, to indicate that the common protozoan Toxoplasma gondii can cause specific behavioural changes in its host. Such behavioural alterations are likely to be the product of strong selective pressures for the parasite to enhance transmission from its intermediate host reservoir, primarily rodent, to its feline definitive host, wherein sexual reproduction can occur and the parasite's life cycle completed. Here we consider what the available data to date may reveal about the potential mechanisms involved, the future research that needs to be performed, and the subsequent implications for animal and human health.
Background - There is growing interest in the role of microbial agents in the causation of psychiatric disorders. The neurotropic protozoan parasite Toxoplasma gondii is one of the main candidates and has been associated with various psychiatric conditions, including schizophrenia. Methods - A narrative review of the literature from the main medical databases (Medline, PubMed, PsycINFO), Google Scholar and Google using combinations of applicable terms. Results - T. gondii affects the brain in both the acute and the latent stages of infection causing apparent brain pathologies in infected rodents and both immuno-compromised and immuno-competent humans. In immuno-competent individuals, behavioural disorders are primarily related to the latent stages of the illness. Behavioural/mental disorders that include schizophrenia, mood disorders, personality changes and cognitive impairments may be related to infection with T. gondii. Evidence for a behavioural effect of T. gondii comes from observational reports in animal models and controlled behavioural analysis in humans. Indirect clues of infection also come from raised seroprevalence or serotitres of antitoxoplasma antibodies among those with mental disorders. The pathophysiologic mechanism through which T. gondii may exert its effect is not clear, but direct impact on the brain and changes in neuroimmunomodulation, neurotransmission and some gene-environment interactions are postulated. Conclusion - There is evidence supporting a potential role of T. gondii infection in the onset of some behavioural disorders. Confirmation of such a role would prove a significant breakthrough in the search for the aetiology, treatment and prevention of behavioural disorders, such as schizophrenia. However, the associations remain preliminary.
Tři obrazy z pozdního období Toyen - V určitou chvíli (1963), Tajný pokoj bez zámku (1966) a Na zámku Silling (1969) - se vyznačují nápadným společným rysem: do každého z nich je vlepena černobílá reprodukce barokního nebo antického sochařského díla s mytologickým námětem. Článek zkoumá postupy, jimiž si Toyen přisvojovala příklady ze starého umění, zabývá se jejím výběrem mytických ženských hrdinek a zamýšlí se nad významem znázornění sochy v malbě. Nejradikálněji zacházela Toyen se zvolenou předlohou v obraze V určitou chvíli, neboť přerušila původní mytologický příběh, obsažený v Berniniho sousoší Apollon a Dafne, osamostatnila přízrak zděšeně prchající ženy a přetočila svůj výstřižek o devadesát stupňů. Navázala na podněty, na které upozornil Salvador Dalí v koláži Fenomén extáze (1933), do níž zapojil snímek "hysterické sochy" z Gaudího architektury. V následujících dvou obrazech Toyen ponechala reprodukovaná díla v původní podobě a pouze je zasadila do souvislostí spjatých s vlastními naléhavými tématy, ať šlo o představu erotizace světa v případě sousoší Amora a Psyche z vykopávek v Ostii (viz Tajný pokoj bez zámku), nebo o těsné sepětí ženy s nebezpečnými přírodními silami, jak je znázornil mélský reliéf Peleus a Thetis (viz Na zámku Silling). Otázka, jakou funkci mají převzaté motivy v obrazivosti Toyen a proč se rozhodla zpřítomnit je prostřednictvím černobílých reprodukcí soch z minulých staletí, odkazuje k Warburgovým formulím patosu. Předstupeň k pracím Toyen lze spatřovat v jeho výkladu, že užití grisaillové techniky pro ztvárnění antických námětů v renesanční malbě mělo udržet antiku v psychické, metaforické a typologické distanci. Zároveň však Warburga zaujal utopický rozměr grisaille, přenášející silné prvotní vášně do arkadického duševního prostoru. Zdá se, že podobné cíle, ovšem za použití moderní techniky koláže, sledovala intuitivně i Toyen. and Three paintings from Toyen's late period - At a Given Moment (1963), A Secret Room without a Lock (1966) and At Silling Castle (1969) - stand out due to a conspicuous trait they share: pasted into each is a black-and-white reproduction of a Baroque or ancient statue with a mythological motif. This article explores the methods Toyen used to appropriate instances from the art of old; it deals with her selection of mythical female figures and contemplates the significance of depicting sculpture in paintings. Toyen was most radical with the original she selected for the painting At a Given Moment, in which she intervened in the primordial mythological story embodied in Bernini's Apollo and Daphne, appropriating the spectre of the fleeing woman and rotating the cut-out ninety degrees. She was thus alluding to subjects which Salvador Dalí had drawn attention to in The Phenomenon of Ecstasy (1933), a collage in which he included a photograph of a 'hysterical or ecstatic statue'. In the other two paintings, Toyen left the reproduced image in its original form and simply inserted it into a set of relationships intertwined with her own pressing themes, whether that meant her desire to eroticize the world in case of Amor and Psyche, excavated at Ostia (see A Secret Room without a Lock), or the tightly interwoven relationship between woman and dangerous natural forces, as portrayed in the Melian relief of Peleus and Thetis (see At Silling Castle). The question regarding the function of the borrowed motifs in Toyen's imaginary world and why she decided to bring them into the present using black-and-white reproductions of sculptures from bygone centuries recalls Warburg's Pathosformen (pathos formulas). Certain precedents relating to Toyen's approach may be seen in the interpretation that the use of the grisaille technique to shape the antique subjects in Renaissance painting was meant to maintain antiquity at a typological distance. At the same time, however, Warburg was captivated by the Utopian dimension of grisaille. It seems that Toyen had similar aims, although she pursued them intuitively, using modern collage techniques.
Seedling recruitment is a critical developmental stage in regeneration of plant populations under Mediterranean conditions that strongly depends on water availability. Seed mass and relative growth rate (RGR) may affect the early establishment of seedlings through different physiological processes. Here, we examined the effects of the seed mass and carbon balance on seedling growth under two water regimes in Rhamnus alaternus L. and Rhamnus ludovici-salvatoris, two Mediterranean shrubs, showing a different ability to recruit seedlings. Plant water consumption and biomass accumulation (ΔB) were measured during three periods of the growth in order to estimate water use efficiency (WUE), RGR, and its components. Additionally, net photosynthesis and leaf, stem, and root respiration were measured in plants grown in pots well watered and under progressive drought. Rhamnus alaternus showed the higher seed mass, ΔB, and plant WUE than that of R. ludovici-salvatoris in all periods and water regimes. The higher RGR of R. alaternus was observed during the first and the second period, but the reverse trend was registered during the third period as a consequence of the higher initial biomass of R. alaternus. Also, R. alaternus showed a higher specific leaf area and estimated carbon balance than that of R. ludovicisalvatoris. The observed differences in ΔB, estimated carbon balance, seed mass, and WUE between both species could explain their different distribution and ability to recruit seedlings under natural conditions., H. El Aou-Ouad, I. Florez-Sarasa, M. Ribas-Carbó, J. Flexas, H. Medrano, J. Gulías., and Obsahuje seznam literatury