Surface plasmon resonance: An innovative method for studying water permeability of plant cuticles.

The cuticle forms an effective barrier protecting plants from water loss. Its permeability to water and other compounds significantly differs between species, types of cuticle (stomatous, astomatous), and can be affected by a wide variety of ambient conditions. Enzymatic isolation of the leaf cuticle allows obtaining intact cuticles for permeability measurements.

Modulating the activities of chloroplasts and mitochondria promotes adenosine triphosphate production and plant growth.

Efficient photosynthesis requires a balance of ATP and NADPH production/consumption in chloroplasts, and the exportation of reducing equivalents from chloroplasts is important for balancing stromal ATP/NADPH ratio. Here, we showed that the overexpression of purple acid phosphatase 2 on the outer membranes of chloroplasts and mitochondria can streamline the production and consumption of reducing equivalents in these two organelles, respectively. A higher capacity of consumption of reducing equivalents in mitochondria can indirectly help chloroplasts to balance the ATP/NADPH ratio in stroma and recycle NADP, the electron acceptors of the linear electron flow (LEF).

A modified method for enzymatic isolation of and subsequent wax extraction from leaf cuticle.

Background: The plant cuticle represents one of the major adaptations of vascular plants to terrestrial life. Cuticular permeability and chemical composition differ among species. is a widely used model for biochemical and molecular genetic studies in plants.

Seasonal variation of δO and δH in leaf water of Fagus sylvatica L. and related water compartments.

The study aims to assess variability in leaf water isotopic enrichment occurring in the field under natural conditions. We focused on seasonal variation and difference between sun-exposed and shaded leaves. Isotopic composition (δO, δH) of leaf water was monitored in a beech tree (Fagus sylvatica L.

Stomatal function, density and pattern, and CO assimilation in Arabidopsis thaliana tmm1 and sdd1-1 mutants.

Stomata modulate the exchange of water and CO between plant and atmosphere. Although stomatal density is known to affect CO diffusion into the leaf and thus photosynthetic rate, the effect of stomatal density and patterning on CO assimilation is not fully understood. We used wild types Col-0 and C24 and stomatal mutants sdd1-1 and tmm1 of Arabidopsis thaliana, differing in stomatal density and pattern, to study the effects of these variations on both stomatal and mesophyll conductance and CO assimilation rate.

Stimulation of ipt overexpression as a tool to elucidate the role of cytokinins in high temperature responses of Arabidopsis thaliana.

Cytokinins (CKs) are phytohormones regulating plant growth and development as well as response to the environment. In order to evaluate their function in heat stress (HS) responses, the effect of CK elevation was determined during three types of HS - targeted to shoots, targeted to roots and applied to the whole plant. The early (30min) and longer term (3h) responses were followed at the hormonal, transcriptomic and proteomic levels in Arabidopsis transformants with dexamethasone-inducible expression of the CK biosynthetic gene isopentenyltransferase (ipt) and the corresponding wild-type (Col-0).

Light-induced STOMAGEN-mediated stomatal development in Arabidopsis leaves.

The initiation of stomata, microscopic valves in the epidermis of higher plants that control of gas exchange, requires a co-ordinated sequence of asymmetric and symmetric divisions, which is under tight environmental and developmental control. Arabidopsis leaves grown under elevated photosynthetic photon flux density have a higher density of stomata. STOMAGEN encodes an epidermal patterning factor produced in the mesophyll, and our observations indicated that elevated photosynthetic irradiation stimulates STOMAGEN expression.

Stomatal and pavement cell density linked to leaf internal CO2 concentration.

Background And Aims: Stomatal density (SD) generally decreases with rising atmospheric CO2 concentration, Ca. However, SD is also affected by light, air humidity and drought, all under systemic signalling from older leaves. This makes our understanding of how Ca controls SD incomplete.

Enhanced drought and heat stress tolerance of tobacco plants with ectopically enhanced cytokinin oxidase/dehydrogenase gene expression.

Responses to drought, heat, and combined stress were compared in tobacco (Nicotiana tabacum L.) plants ectopically expressing the cytokinin oxidase/dehydrogenase CKX1 gene of Arabidopsis thaliana L. under the control of either the predominantly root-expressed WRKY6 promoter or the constitutive 35S promoter, and in the wild type.

Mesophyll conductance to CO(2) transport estimated by two independent methods: effect of variable CO(2) concentration and abscisic acid.

Mesophyll conductance (g(m)) and stomatal conductance (g(s)) are two crucial components of the diffusive limitation of photosynthesis. Variation of g(m) in response to CO(2) concentration was evaluated by using two independent methods based on measurements of variable electron transport rate (J) and instantaneous carbon isotope discrimination, respectively. Both methods of g(m) estimation showed a very similar shape of the g(m)/C(i) relationship, with an initial increase at low substomatal CO(2) concentrations (C(i)), a peak at 180-200 micromol mol(-1) C(i), and a subsequent decrease at higher C(i).

[Changes in the cardiovascular risk profile of the population of the Czech Republic--MONICA 1992].

Background: The cardiovascular risk profile of the population in the Czech Republic is unfavourable, the mortality of the population from cardiovascular diseases is among the highest in the world. The objective of the present work was to compare the prevalence of the most serious risk factors in 1988 and 1992 and to find out whether the change of the political and economic system in 1989 had an impact on the risk profile of the population. Within the framework of the international WHO project MONICA independent 1% random population samples, age bracket 25-64 years, were examined in six districts of the Czech Republic.