Mutants with altered leaf morphology are useful as markers for the study of genetic systems and for probing the leaf differentiation process. One such mutant with deficient greening and altered development of the leaf mesophyll appeared in an inbred line of sunflower (Helianthus annuus L.). The objectives of the present study were to determine the inheritance of the mutant leaf trait and its morphological characterisation. The mutation, named mesophyll cell defective1 (mcd1), has pleiotropic effects and it is inherited as a monogenic recessive. The structure and tissue organization of mcd1 leaves are disrupted. In mcd1 leaves, the mesophyll has prominent intercellular spaces, and palisade and spongy tissues are not properly shaped. The mutant palisade cells also appear to be more vacuolated and with a reduced number of chloroplasts than the wild type leaves of equivalent developmental stage. The lamina thickness of mcd1 leaves is greatly variable and in some areas no mesophyll cells are present between the adaxial and abaxial epidermis. The leaf area of the mcd1 mutant is extremely reduced as well as the stem height. A deficient accumulation of photosynthetic pigments characterizes both cotyledons and leaves of the mutant. In mcd1 leaves, chlorophyll (Chl) fluorescence imaging evidences a spatial heterogeneity of leaf photosynthetic performance. Little black points, which correspond to photosystem II (PSII) maximum efficiency (Fv/Fm) values close to zero, characterize the mcd1 leaves. Similarly, the lightadapted quantum efficiency (ΦPSII) values show a homogeneous distribution over wild type leaf lamina, while the damaged areas in mcd1 leaves, represented by yellow zones, are prominent. In conclusion, the loss of function of the MCD1 gene in Helianthus annuus is correlated with a variegated leaf phenotype characterized by a localized destruction of mesophyll morphogenesis and defeat of PSII activity. and M. Fambrini ... [et al.].
Mesophyll conductance (gm) is essential to determine accurate physiological parameters used to model photosynthesis in forest ecosystems. This study aimed to determine the effects of time of day on photosynthetic parameters, and to assess the effect of using either intercellular CO2 concentration (Ci) or chloroplast CO2 concentration (Cc), on maximum carboxylation velocity of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), Vcmax. We used Amazonian saplings of Myrcia paivae and Minquartia guianensis. Photosynthetic parameters were measured using an infrared gas analyzer (IRGA); gm was determined using both gas exchange and chlorophyll (Chl) a fluorescence and gas-exchange data alone. Leaf thickness (LT) and specific leaf area (SLA) were also measured. Air temperature, relative humidity or understory light did not correlate with gm and on average daily IRGA-fluorometer-determined gm was 0.04 mol(CO2) m-2 s-1 for M. paivae and 0.05 mol(CO2) m-2 s-1 for M. guianensis. Stomatal conductance (gs), gm, electron transport rate (JF), and light-saturated net photosynthetic rate (PNmax) were lower in the afternoon than in the morning. However, no effect of time of day was observed on Vcmax. LT and SLA did not affect any of the examined parameters.
IRGA-determined g m was almost the double of the value obtained using the IRGA-fluorescence method. Vcmax values determined using Cc were about 25% higher than those obtained using Ci, which highlighted the importance of using Cc in Vcmax calculation. Decline in PNmax at the end of the afternoon reflected variations in gs and gm rather than changes in Vcmax. Diurnal variation in gm appeared to be associated more with endogenous than with atmospheric factors. and H. C. S. Nascimento, R. A. Marenco.
The aim of this paper is to show time-de pendent baseline variation between GPS stations situated in South-East Poland. This study was based on daily data analysis of selected GPS stations: WROC, GOPE, MOPI, KRAW and KATO. The start date o f the analysis is linked at every station with the beginning of its operation and the closing date of the operation is in 2006. The multiresolution signal decomposition method has been used to analyze the periodic terms of the time series of the above. The estimated trends enable further coordinate analysis as well as determination of site displacements at the study area., Mariusz Figurski, Krzysztof Kroszczyński, Paweł Kamiński and Marcin Gałuszkiewicz., and Obsahuje bibliografické odkazy
Some innovations are presented at international Engineering Fair BRNO 2009. MESING traditionally exposes together with AQUASTYL SLOVAKIA and Uvádíme některé novinky, které bude MESING m. j. prezentovat na MSV BRNO 2009. MESING má na MSV BRNO tradičně společnou expozici s AQUASTYL SLOVAKIA.