Incorporation of labelled CO2, 3-phosphoglycerate (PGA), phosphoenolpyruvate (PEP) and pyruvate into hexane extractable rabber ffactions in the cut shoots of guayule {Parthenium argentatum Gray) was determined in order to evaluate the role of photosynthesis in providing precursors for rubber biosynthesis. DCMU inhibited the incorporation of labelled CO2 and PGA into rubber. The incorporation of i'*C02 into rubber depended on irradiance. Enzymatic activities of phosphoglyceromutase, enolase, pyruvate kinase and pyruvate dehydrogenase complex found in purified chloroplasts from the leaves indicated the chloroplast autonomy for intraplastid acetyl coenzyme A formation. The enzymes related to the biosynthesis of isopentenyl pyrophosphate (IPP) were associated with both leaf and stem extracts. Rubber producing enzyme activities, námely IPP isomerase and rubber transferase, were abundantly localized in roots and stems of guayule while the leaves exhibited low activities of these enzymes. Hence the leaves of guayule play a major role in providing precursors for rubber formation in stems and roots.
Vnitrodruhová variabilita v chování zvířat, tj. personalita, výrazně ovlivňuje ekologické i evoluční procesy. V tomto článku se pojednává o tom, jak může personalita vzniknout u pavouků a její vliv na potravní sítě., Inter-individual behavioural differences, i.e. personalities, play a very important role in eco-evolutionary processes. Here, we describe how spiders’ personalities arise and how they influence the dynamics of food webs., and Radek Michalko.
Rodiče předčasně narozených dětí vykazují ve srovnání s rodiči, jimž se narodilo dítě v termínu, vyšší míru stresu, vyšší potřebu pomoci během prvního roku po porodu, nižší schopnost adaptace, vysokou potřebu informací a lze u nich identifikovat také projevy posttraumatické stresové poruchy. To, jak se rodiče vyrovnávají s traumatem předčasného porodu, může ovlivnit přechod k rodičovství, přebírání rodičovských kompetencí, prospívání dítěte a samotný vztah k dítěti. Studie se zaměřuje na faktory, které mohou mít na utváření vztahu k dítěti vliv, tedy i na hledání možných způsobů prevence případných rizik. Vedle matek předčasně narozených dětí se zaměřuje také na otce, kterým je věnována samostatná kapitola. Krom jiného se ukazuje, že důležitou roli v utváření vztahu k dítěti hraje zdravotnický personál. Lepší povědomí o prožívání rodičů v tomto stresujícím období by mohlo vést k citlivějšímu přístupu k rodičům, saturaci jejich potřeb, a tím i předcházení některých obtíží ústících v opožďování nástupu rodičovské identity a narušený vztah k dítěti., Parents of premature born children show - in comparison with parents whose child was born in time limit - the higher level of stress, higher need for help during the first year after the birth, lower adaptation ability, high need for information, and also manifestations of post-traumatic stress disease can be identified in them. The way the parents cope with the trauma of premature birth can influence the transition to parenthood, taking over the parent competencies, prospering of the child, and the relation to child itself. The study focuses on factors that can influence the formation of parental relation to the child and thus also the looking for the possible ways of prevention of potential risks. Except of mothers of premature born children it focuses also on fathers whom is devoted a separated part of the study. It shows besides other things that the medical personnel play an important role in forming the relation to the child. The better awareness of parents’ experiencing in this stressing period could lead to more sensitive approach to parents, saturation of their needs and thus also prevention of some difficulties resulting in the delay of commencement of parental identity and disturbed relation to the child., Michaela Chlebounová, Ivo Čermák., and Obsahuje seznam literatury
In the temperate haptophyceaen Pavlova luíheri (Droop) Green and Pavlova sp. (not yet estimated) the dominant pigments were chlorophyll (Chl) a (57 %), fucoxanthin (17 %) and diadinoxanthin (13 %); other estimated pigments were p-carotene, Chl c, cA-fucoxanthin and diatoxanthin. UV-A of 1.7 W m-2 had no effect on pigmentation of P. luíheri, but led to a reduction of the pigment contents of Pavlova sp. The damaging effect of a high UV-A dose (11.0 W m'^) was more pronounced than that of UV-B irradiance. The strongest reduction of pigment concentrations of both Pavlova species was observed after an exposure to UV-A (11.0 W m'^) plus UV-B (1.2 W m-2). Under this combined irradiation an increase of the diatoxanthin content and a decrease of the diadinoxanthin content was found.
The purpose of this study was to determine the production of metalloproteinases (MMP) 2 and 9 following UV-B irradiation in human corneal epithelial cells and fibroblasts. Epithelial cells and fibroblasts were separated from human donor corneas and exposed to UV-B lamp irradiation for 20, 40, 80 and 120 s. Media samples were collected at 8, 24, 48 and 72 h and gelatinase A and B production was assayed by the ELISA test. Statistical significance of production was assessed by the paired t-test. Increased production of MMP-2 was found in human corneal fibroblasts in response to UV-B irradiation. A statistically significant production of MMP-2 was not observed in human corneal epithelial cells following UV-B exposure. We did not detect any increase in MMP-9 after irradiation in either epithelial cells or fibroblasts. MMP-2 is produced by the corneal fibroblasts in the acute phase after UV-B irradiation. MMP-9 is not released in vitro following UV-B irradiation damage and therefore does not directly participate in the pathophysiology of acute photokeratitis., I. Kozák, D. Klisenbauer, T. Juhás., and Obsahuje bibliografii
The review deals with the comprehensive analysis of ultraviolet-B (UV-B) induced alterations in photosynthetic processes of higher plants and possible protection mechanisms. Between two photosystems, photosystem 2 (PS2) is main target for UV- B radiation stress. Depending on the mode of treatment, the oxidising side of PS2 and reaction centres are mainly affected by UV-B treatment. As response to UV-B stress plants develop some inherent adaptive mechanisms which decide the extent of the overall damage.