Phlomis fruticosa is one of the main species of post-fire Mediterranean communities, occupying areas with post-fire grazing or altered precipitation pattern and consequently water stress imposed on seedlings of co-occurring species. Seedlings of woody perennials often differ from their mature individuals regarding their resistance of photosynthetic performance to environmental stresses. Such differences have been reported for tree species but there is a lack of information regarding shrub species. In the present study, we tried to detect changes in (PSII) activity imposed by water stress in P. fruticosa seedlings as well as its capability for recovery after rehydration. Maximum PSII photochemical efficiency decreased only under severe water stress exactly as in mature plants in the field. However, leaf chlorophyll (Chl) content was almost stable regardless of leaf relative water content (RWC). We assume that the photoprotective chlorophyll loss process, reported for many mature Mediterranean species (including P. fruticosa), has not yet been developed at the seedling stage. On the other hand, photoprotection through an increase of the relative amount of non-QB-reducing centers was found during dehydration. Non-photochemical quenching (NPQ) contributed to protection from photodamage until moderate water stress but was significantly suppressed under severe water stress. Both processes were reversed after rehydration. The above characteristics enabled seedlings not only to survive during aggravating drought but also to maintain a considerable part of their effective quantum yield and perform significant electron transport even at extremely low relative water content (RWC). This was confirmed with measurements in a semi-natural environment (pots) and under real steady state conditions regarding adaptation of the photosynthetic machinery to prevailing light intensities. and A. Petsas, G. Grammatikopoulos.
Global warming will likely exacerbate the negative effects of limited water availability in the Mediterranean area. The Italian Aleppo pine (Pinus halepensis Mill.) provenances are distributed along the coasts except Otricoli provenance growing in an unusual location between 300 and 1,000 m a. s. l., in Umbria (central Italy). The aim of the present study was to investigate the photosynthetic response to a 28-day-long drought and to a subsequent reestablishment of water availability in Otricoli and North Euboea (Greece) provenances, representing different locations along a rainfall gradient in the natural range of this species. Six-month-old seedlings were used in this experiment since at this age Aleppo pine plants in Mediterranean climate face their first water stress potentially affecting plant survival. Water potential (ψw), net photosynthesis and stomatal conductance decreased during drought in both provenances and showed minimal values 28 days after beginning the treatment (DAT). Otricoli seedlings adjusted ψw gradually as the stress level increased and 21 DAT showed a lower ψw than North Euboea. In contrast, in North Euboea seedlings ψw that was not affected until 21 DAT rapidly dropped to a minimum of -3.81 MPa 28 DAT. At the onset of the stress the intercellular CO2 concentration (Ci) was reduced, and the "instrinsic" water-use efficiency (WUEi) was enhanced in both provenances, as stomatal conductance decreased more rapidly than photosynthesis. However, 28 DAT, Ci increased and WUEi decreased as stomatal conductance and photosynthesis declined to minimum levels, revealing nonstomatal limitations of photosynthesis. A rapid decrease in PSII maximal photochemical efficiency estimated by chlorophyll (Chl) fluorescence (Fv/Fm) was also observed when the stress became severe. At the final stage of water stress, North Euboea seedlings maintained significantly higher values of Fv/Fm than Otricoli seedlings. Upon rewatering, photosynthesis did not fully recover in Otricoli seedlings (41 DAT), while all other parameters recovered to control levels in both provenances. No drought-induced physiological differences were consistent with the regional climatic features of these two provenances. Our results suggest that phenotypic plasticity in drought response may help Otricoli provenance cope with global warming, but that recurrent drought episode may slow down the primary productivity of this provenance. and M. Michelozzi ... [et al.].
The influence of drought stress (DS) upon whole-plant water content, water relations, photosynthesis, and water-use efficiency of Hibiscus rosa-sinensis cv. Leprechaun (Hibiscus) plants at three levels of potassium (K) nutritional status were determined after a 21-d gradually imposed DS treatment. Compared to K-deficient plants, adequate K supply improved the leaf water content (LWC) and leaf water relations of Hibiscus by decreasing the Ψ π, and generally sustained rates of net photosynthesis (PN) and transpiration (E), and stomatal conductance (gs), both in DS and non-DS plants. In K-deficient Hibiscus, LWC, turgor potential (Ψ P), and PN, E, and gs as well as instantaneous water-use efficiency, WUE (PN/E) were consistently lower, compared to K-sufficient plants. Carbon isotope discrimination (Δ) was lower (i.e. longterm WUE was greatest) in DS than non-DS plants, but K had no effect on Δ during the 21-d drought treatment period under glasshouse conditions. However, the trend in the Δ value of DS plants suggests that Δ could be a useful index of the response of Hibiscus to DS under glasshouse growing conditions. Thus the incorporation of a properly controlled fertilization regime involving sufficient levels of K can improve the acclimation of PN to low Ψleaf, increase PN/E of Hibiscus, and may have potential benefit for other woody plants species. and J. N. Egilla, F. T. Davies Jr., T. W. Boutton.
We investigated the strategies of four co-occurring evergreen woody species Quercus ilex, Quercus coccifera, Pinus halepensis, and Juniperus phoenicea to cope with Mediterranean field conditions. For that purpose, stem water potential, gas exchange, chlorophyll (Chl) fluorescence, and Chl and carotenoid (Car) contents were examined. We recognized two stress periods along the year, winter with low precipitation and low temperatures that led to chronic photoinhibition, and summer, when drought coincided with high radiation, leading to an increase of dynamic photoinhibition and a decrease of pigment content. Summer photoprotection was related to non-photochemical energy dissipation, electron flow to alternative sinks other than photosynthesis, decrease of Chl content, and proportional increase of Car content. Water potential of trees with deep vertical roots (Q. coccifera, Q. ilex, and P. halepensis) mainly depended on precipitation, whereas water potential of trees with shallow roots (J. phoenicea) depended not only on precipitation but also on ambient temperature. and F. J. Baquedano, F. J. Castillo.
In this review we summarize several synthetic approaches to the advanced synthesis of star-like polymer-based drug carriers. Moreover, their application as nanomedicines for therapy or the diagnosis of neoplastic diseases and their biodistribution are reviewed in detail. From a broad spectrum of star-like systems, we focus only on fully water-soluble systems, mainly based on poly(ethylene glycol) or N-(2-hydroxypropyl)methacrylamide polymer and copolymer arms and polyamidoamine dendrimers serving as the core of the star-like systems., L. Kotrchová, L. Kostka, T. Etrych., and Obsahuje bibliografii
Our previous studies have shown that the combined administration of drugs elevating extracellular adenosine, i.e. dipyridamole (DP) and adenosine monophosphate (AMP), enhances murine hematopoiesis and potentiates the action of granulocyte colony-stimulating factor (G-CSF). In this study, colony-stimulating activity (CSA) of blood serum of mice treated with DP+AMP, G-CSF or all these drugs in combination, i.e. the ability of the sera to stimulate the growth of GM-CFC colonies, was assayed in vitro. Furthermore, the concentration of GM-CSF and IL-6 in the sera was determined. Administration of DP+AMP was found to enhance significantly serum CSA at all time intervals of serum sampling including 24 h after the last injection of the tested drugs. Additive effects of DP+AMP and G-CSF on serum CSA were noted at early intervals after administration of the drugs. Furthermore, IL-6 levels were significantly elevated in the sera of mice which were administered DP+AMP either alone or in combination with G-CSF. Our results show that the effects of DP+AMP are indirect, mediated through the induction of some cytokine(s) and/or growth factor(s) and that extracellular adenosine can act in cooperation with G-CSF. These findings contribute to the further elucidation of the role of adenosine in hematopoiesis., L. Weiterová, M. Hofer, M. Pospíšil, V. Znojil, D. Štreitová., and Obsahuje bibliografii a bibliografické odkazy
Studie představuje složitý poválečný vývoj pražské egyptologie 1946-1951 prostřednictvím korespondence dvou důležitých aktérů. Korespondence významných českých egyptologů je jednak otiskem Černého osobnosti v dějinách pražského egyptologického pracoviště, ale také odrazem osobnosti Zbyňka Žáby, který byl pro institucionální vývoj a zajištění existence ústavu osobou klíčovou, ač rozporuplnou, což je patrné již od počátků jeho odborného působení. Studie tak prostřednictvím dvou rozdílných osudů vědců zachycuje období od poválečné obnovy výuky egyptologie na FF UK v Praze, po etablování Jaroslava Černého ve Velké Británii a Zbyňka Žáby v Praze., This study presents the complex post-war development of Prague Egyptology in 1946-1951 through the correspondence of two of its important practitioners, Jaroslav Černý and Zbyněk Žába. The correspondence of prominent Czech Egyptologists is marked both by Černý’s personality and its impact within the history of the Prague Egyptology department and by Zbyněk Žába’s, who was of key importance to ensuring the existence and the institutional development of the discipline, although he was a contradictory character, as was evident from the start of his professional activities. The character of the department-to-be was mainly philological in its beginnings in the late 1940s and early 1950s. The specialisation corresponded to the interests of the two protagonists, yet they both considered further developments, which eventually led to the establishment of a primarily archaeological institute. Hence this study uses the various fortunes of these two scholars to portray the period from the resumption of Egyptology tuition at the Charles University Faculty of Arts in Prague to the time Jaroslav Černý settled in Britain and Zbyněk Žába settled in Prague. It also includes Černý’s invisible college links in international Egyptology, and Překlad resumé: Melvyn Clarke
Obnovení pořádku v Československé akademii věd patřilo mezi prvořadé úkoly československé normalizace. Některé instituce byly ''očištěny'' dříve, jiné později, každopádně propuštění Ivana Svitáka z Filosofického ústavu v létě 1969 představovalo precedens, podle něhož bylo o nedlouho později postupováno vůči vědcům ocitnuvším se v kapitalistické cizině. Hlavně se ale jednalo o symbolický akt likvidace nepohodlného exponenta ''pravice a kontrarevoluce''. Svitákova institucionální exkomunikace vypovídá mnohé o samotných normalizačních mechanismech i tehdejších aktérech. Publikovaná korespondence odhaluje myšlenkový svět hlavního aktéra, jeho odpor vůči technokracii, byrokracii i zdeformovanému socialismu, přibližuje jeho pracovní plány a do jisté míry i představy o fungování společnosti demokratického socialismu. Úřední strohost Richtových listů oproti tomu nese jisté stopy cynismu expertně orientovaného vědce, který nepřipouští výraznější projevy odstředivých tendencí a vyžaduje ''klid na práci''. Edice je chápána jako příspěvek k intelektuálním dějinám, stejně jako k dějinám vědní politiky a rané normalizace., The restoration of order in the Czechoslovak Academy of Sciences was among the chief tasks of the so-called ''normalization'' process in Czechoslovakia after the end of the Prague Spring. Some institutions were ''cleansed'' sooner, some later, but the expulsion of Ivan Sviták from the Philosophy Institute in the summer of 1969 set a precedent that would later be used in dealing with other scholars who went to capitalist countries after the military invasion of Czechoslovakia in August 1968. Above all, Sviták’s expulsion was a symbolic act that represented the elimination of ''rightwing and counterrevolutionary'' elements. Sviták’s institutional excommunication sheds light both on the mechanisms of normalization, on Sviták as an individual, and on then-director of the Philosophy Institute Radovan Richta. The correspondence presented here reveals Sviták’s intellectual world: his distaste for technocracy, bureaucracy and deformed socialism; his work projects; and to some extent his vision of democratic socialist society. In contrast to Sviták, Richta’s administrative curtness shows the cynicism of expert-minded scientists, who were prepared to fight any disruptive tendencies and who required normalized ''peace for work.'' The publication of these documents is understood as a contribution to intellectual history as well as to the history of science policy and to the history of the early period of Czechoslovak normalization. (Translated by Jan Mervart), and Překlad resumé: Jan Mervart
Na jedinečnou vzdělávací akci, která se konala od 3. do 10. července 2017 v prostorách Matematicko-fyzikální fakulty v Troji, přijely čtyři desítky nejlepších řešitelů astronomických olympiád z České republiky, Estonska, Maďarska, Polska a Slovenska. Na programu byly vedle výpočetníích seminářů také zvané přednášky přístupné široké veřejnosti, večerní pozorování, výjezd do planetária v Hradci Králové, exkurze na odřejovskou observatoř a komentovaná procházka po pražských astronomických památkách. Účastnící si rovzněž vyzkoušeli atmosféru mezinárodní olympiády při simulované souteži. and Jakub Vošmera, Jan Kožuško, Václav Pavlík.