In Arabidopsis, the plastidial isoform of phosphoglucose isomerase, PGI1, mediates growth and photosynthesis, likely due to its involvement in the vascular production of cytokinins (CK). To examine this hypothesis, we characterized pgi1-2 knockout plants impaired in PGI1 and pgi1-2 plants specifically expressing PGI1 in root tips and vascular tissues. Moreover, to investigate whether the phenotype of pgi1-2 plants is due to impairments in the plastidial oxidative pentose phosphate pathway (OPPP) or the glycolytic pathway, we characterized pgl3-1 plants with reduced OPPP and pfk4pfk5 knockout plants impaired in plastidial glycolysis. Compared with wild-type (WT) leaves, pgi1-2 leaves exhibited weaker expression of photosynthesis- and 2-C-methyl-D-erythritol 4-P (MEP) pathway-related proteins, and stronger expression of oxidative stress protection-related enzymes. Consistently, pgi1-2 leaves accumulated lower levels of chlorophyll, and higher levels of tocopherols, flavonols and anthocyanins than the WT. Vascular- and root tip-specific PGI1 expression countered the reduced photosynthesis, low MEP pathway-derived CK content, dwarf phenotype and the metabolic characteristics of pgi1-2 plants, reverting them to WT-like levels. Moreover, pgl3-1, but not pfk4pfk5 plants phenocopied pgi1-2. Histochemical analyses of plants expressing GUS under the control of promoter regions of genes encoding plastidial OPPP enzymes exhibited strong GUS activity in root tips and vascular tissues. Overall, our findings show that root tip and vascular PGI1-mediated plastidial OPPP activity affects photosynthesis and growth through mechanisms involving long-distance modulation of the leaf proteome by MEP pathway-derived CKs.

• Klíčová slova
• Cytokinin, MEP pathway, Oxidative pentose phosphate pathway, Photosynthesis,
• MeSH
• anthokyaniny metabolismus   MeSH
• Arabidopsis * metabolismus   MeSH
• cytokininy metabolismus   MeSH
• fotosyntéza MeSH
• pentózofosfátový cyklus * MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• anthokyaniny MeSH
• cytokininy MeSH

• Klíčová slova
• PENTOSES/metabolism *,
• MeSH
• lidé MeSH
• pentosy metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• pentosy MeSH

BACKGROUND: Pentose phosphate pathway (PPP) represents a potentially 'protective' mechanism in hyperglycaemia due to shunting of glycolytic intermediates into PPP reactions. We hypothesized that thiamine status (plasma and erythrocyte levels of thiamine and its esters) together with genetic variability in key PPP enzymes-transketolase (TKT), transaldolase and TKT-like-might contribute to the progression of diabetic nephropathy (DN) and mortality of diabetics. METHODS: A total of 240 diabetic subjects with variable degree of kidney disease were included at baseline and were followed up for a median of 26 (IQR 21-50) months. Concentrations of thiamine in plasma and whole blood and TKT-catalysed reaction were determined by HPLC. Single-nucleotide polymorphisms (SNPs) (n = 14) were genotyped by means of PCR using TaqMan chemistry (Applied Biosystems, Foster City, CA, USA). RESULTS: Significant differences in pTh, pThDP, eryThDP and eryTKT between DN-stage groups were ascertained (P < 0.05) with advancing stage of DN being accompanied with increasing values of pTh, pThDP and eryTKT but not eryThDP. A highly significant negative correlation (r = - 0.41, P < 0.001) was found between pThDP and eryThDP, and the tertiles of the ratio of eryThDP/pThDP were significantly associated with all-cause mortality rates (P = 0.0072). We also identified significant differences in the rate of DN progression between different pTDP tertile groups (P = 0.0017). No significant genetic effects were found. CONCLUSIONS: The results support the role of 'functional' thiamine deficiency in the development of hyperglycaemia-related pathology. Limited intracellular availability of active TKT co-factor seems to be a dominant abnormality.

• MeSH
• diabetické nefropatie enzymologie   genetika   mortalita   MeSH
• dospělí MeSH
• erytrocyty enzymologie   MeSH
• genotyp MeSH
• glukosa metabolismus   MeSH
• jednonukleotidový polymorfismus genetika   MeSH
• lidé středního věku MeSH
• lidé MeSH
• míra přežití MeSH
• následné studie MeSH
• pentosafosfáty metabolismus   MeSH
• pentózofosfátový cyklus MeSH
• průřezové studie MeSH
• senioři MeSH
• thiamin metabolismus   MeSH
• transaldolasa genetika   MeSH
• transketolasa genetika   MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• glukosa MeSH
• pentosafosfáty MeSH
• thiamin MeSH
• TKTL1 protein, human MeSH Prohlížeč
• transaldolasa MeSH
• transketolasa MeSH

• Klíčová slova
• ACTH/effects *, ERYTHROCYTES/metabolism *, PENTOSES/in blood *,
• MeSH
• adrenokortikotropní hormon farmakologie   MeSH
• erytrocyty metabolismus   MeSH
• lidé MeSH
• pentosy krev   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adrenokortikotropní hormon MeSH
• pentosy MeSH

• MeSH
• experimentální radiační poranění metabolismus   MeSH
• myši MeSH
• pentosy metabolismus   MeSH
• radiobiologie MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• pentosy MeSH

The aim of the study was to verify the hypothesis that a potential cause of the phytotoxicity of diclofenac (DCF, a non-steroidal anti-inflammatory drug) is an effect of cell cycle progression. This research was conducted using synchronous cultures of a model organism, green alga Chlamydomonas reinhardtii. The project examined DCF effects on selected parameters that characterize cell cycle progression, such as cell size, attainment of commitment points, DNA replication, number of nuclei formed during cells division and morphology of cells in consecutive stages of the cell cycle, together with the physiological and biochemical parameters of algae cells at different stages. We demonstrated that individual cell growth remained unaffected, whereas cell division was delayed in the DCF-treated groups grown in continuous light conditions, and the number of daughter cells from a single cell decreased. Thus, the cell cycle progression is a target affected by DCF, which has a similar anti-proliferative effect on mammalian cells.

• Klíčová slova
• Chlamydomonas reinhardtii, cell cycle, diclofenac, non-steroidal anti-inflammatory drug,
• MeSH
• antiflogistika nesteroidní toxicita   MeSH
• buněčné dělení účinky léků   MeSH
• buněčný cyklus účinky léků   MeSH
• Chlamydomonas reinhardtii účinky léků   genetika   růst a vývoj   MeSH
• diklofenak toxicita   MeSH
• DNA rostlinná biosyntéza   genetika   MeSH
• fotosyntéza účinky léků   MeSH
• replikace DNA účinky léků   MeSH
• velikost buňky účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antiflogistika nesteroidní MeSH
• diklofenak MeSH
• DNA rostlinná MeSH

A microscope for imaging of chlorophyll fluorescence kinetics was equipped with a chamber that allows the growth of an immobilised population of algae and their study under well-defined conditions. Single cells of the chlorococcal alga Scenedesmus quadricauda were grown and recorded for periods of whole cell cycles (up to 48 h) displaying a normal course of cell development. Heterogeneity in fluorescence yield among individual coenobia in the population and among different cells in one coenobium were analysed. Differences were observed both in the shape of Kautsky transients and in the modulation of fluorescence parameter values during the progress of the cell cycle. The extent of heterogeneity in fluorescence parameters was cell cycle dependent - in some phases of the cycle, the population was almost homogeneous, while distinct heterogeneity was observed, in particular between the protoplast division and the release of the daughter coenobia. The heterogeneity was not random but reflected developmental processes.

• MeSH
• buněčný cyklus fyziologie   MeSH
• chlorofyl metabolismus   MeSH
• Chlorophyta cytologie   metabolismus   MeSH
• fluorescenční mikroskopie MeSH
• fotosyntéza fyziologie   MeSH
• kinetika MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH

Light-dependent conversion of violaxanthin to zeaxanthin, the so-called xanthophyll cycle, was shown to serve as a major, short-term light acclimation mechanism in higher plants. The role of xanthophylls in thermal dissipation of surplus excitation energy was deduced from the linear relationship between zeaxanthin formation and the magnitude of non-photochemical quenching. Unlike in higher plants, the role of the xanthophyll cycle in green algae (Chlorophyta) is ambiguous, since its contribution to energy dissipation can significantly vary among species. Here, we have studied the role of the xanthophyll cycle in the adaptation of several species of green algae (Chlorella, Scenedesmus, Haematococcus, Chlorococcum, Spongiochloris) to high irradiance. The xanthophyll cycle has been found functional in all tested organisms; however its contribution to non-photochemical quenching is not as significant as in higher plants. This conclusion is supported by three facts: (i) in green algae the content of zeaxanthin normalized per chlorophyll was significantly lower than that reported from higher plants, (ii) antheraxanthin + zeaxanthin content displayed different diel kinetics from NPQ and (iii) in green algae there was no such linear relationship between NPQ and Ax + Zx, as found in higher plants. We assume that microalgae rely on other dissipation mechanism(s), which operate along with xanthophyll cycle-dependent quenching.

• MeSH
• aklimatizace účinky záření   MeSH
• beta-karoten analogy a deriváty   metabolismus   MeSH
• chlorofyl metabolismus   MeSH
• Chlorophyta fyziologie   účinky záření   MeSH
• fotosyntetické reakční centrum - proteinové komplexy fyziologie   účinky záření   MeSH
• fotosyntéza fyziologie   účinky záření   MeSH
• světlo MeSH
• teplota MeSH
• xanthofyly metabolismus   MeSH
• zeaxanthiny MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• antheraxanthin MeSH Prohlížeč
• beta-karoten MeSH
• chlorofyl MeSH
• fotosyntetické reakční centrum - proteinové komplexy MeSH
• xanthofyly MeSH
• zeaxanthiny MeSH

• MeSH
• dehydroepiandrosteron metabolismus   MeSH
• gynekologie MeSH
• lidé MeSH
• NADP metabolismus   MeSH
• pentosy metabolismus   MeSH
• Check Tag
• lidé MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• dehydroepiandrosteron MeSH
• NADP MeSH
• pentosy MeSH

A dedicated field experiment was conducted to investigate the response of a green reflectance continuum removal-based optical index, called area under the curve normalized to maximal band depth between 511 nm and 557 nm (ANMB511-557), to light-induced transformations in xanthophyll cycle pigments of Norway spruce [Picea abies (L.) Karst] needles. The performance of ANMB511-557 was compared with the photochemical reflectance index (PRI) computed from the same leaf reflectance measurements. Needles of four crown whorls (fifth, eighth, 10th, and 15th counted from the top) were sampled from a 27-year-old spruce tree throughout a cloudy and a sunny day. Needle optical properties were measured together with the composition of the photosynthetic pigments to investigate their influence on both optical indices. Analyses of pigments showed that the needles of the examined whorls varied significantly in chlorophyll content and also in related pigment characteristics, such as the chlorophyll/carotenoid ratio. The investigation of the ANMB511-557 diurnal behaviour revealed that the index is able to follow the dynamic changes in the xanthophyll cycle independently of the actual content of foliar pigments. Nevertheless, ANMB511-557 lost the ability to predict the xanthophyll cycle behaviour during noon on the sunny day, when the needles were exposed to irradiance exceeding 1000 µmol m(-2) s(-1). Despite this, ANMB511-557 rendered a better performance for tracking xanthophyll cycle reactions than PRI. Although declining PRI values generally responded to excessive solar irradiance, they were not able to predict the actual de-epoxidation state in the needles examined.

• MeSH
• chlorofyl metabolismus   MeSH
• fotosyntéza fyziologie   MeSH
• karotenoidy metabolismus   MeSH
• listy rostlin metabolismus   fyziologie   MeSH
• smrk metabolismus   fyziologie   MeSH
• xanthofyly metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• chlorofyl MeSH
• karotenoidy MeSH
• xanthofyly MeSH