The age dependence of the photosynthetic performance, chlorophyll fluorescence and chloroplast ultrastructure of green form and Chl ft-deficient form (aurea) of tobacco Su/su mutant were compared. The most pronounced differences between the aurea and green tobacco found in young leaves diminished with leaf age. Slower accumulation of the photosynthetic pigments during the development of aurea leaves was accompanied by a slower accumulation of LHC antennae of both photosystems, particularly that of PS2, and by retention of an increase in the capacity of PS2 photochemistry, measured as Fy/FM The ratio Fv/Fm, however, increased rapidly during maturation of aurea leaves, and fmally the mature aurea leaves exhibited higher values of this ratio than the green ones. Rates of photosynthesis at saturating irradiance (Epiax) saturating CO2 concentration (/’sat) decreased with leaf age for both aurea and green tobacco, being always higher in aurea leaves than in leaves of green tobacco of comparable age. AU these characteristics indicated retarded development of aurea leaves. Also the chloroplast ultrastructure, particularly grana formation, exhibited slower development. The decrease in /Wx and with leaf age in both tobacco forms and retardation in the development of aurea leaves can explain higher value of usually found in aurea tobacco.
Cryptosporidium fragile sp. n. (Apicomplexa) is described from black-spined toads, Duttaphrynus melanostictus (Schneider) (Amphibia, Anura, Bufonidae) from the Malay Peninsula. The parasitized animals were directly imported from Malaysia and harboured C. fragile at the time of arrival. Oocysts were subspherical to elliptical with irregular contour in optical section, measuring 6.2 (5.5-7.0) × 5.5 (5.0-6.5) µm. Oocyst wall was smooth and colourless in light microscopy. The endogenous development of C. fragile in the stomach of black-spined toad was analysed in detail using light and electron microscopy. Cryptosporidian developmental stages were confined to the surface of gastric epithelial cells. In transmission experiments, C. fragile has not been infective for one fish species, four amphibian species, one species of reptile and SCID mice. Full length small subunit rRNA gene sequence was obtained. Phylogenetic reconstruction revealed distinct status of C. fragile within the clade of species with gastric localisation including Cryptosporidium muris Tyzzer, 1907, Cryptosporidium serpentis Levine, 1980 and Cryptosporidium andersoni Lindsay, Upton, Owens, Morgan, Mead et Blagburn, 2000. Described characteristics differentiate C. fragile from the currently recognized Cryptosporidium species. Our experience with the description of C. fragile has led us to revise the recommended criteria for an introduction of a new Cryptosporidium species name. C. fragile is the first species described and named from an amphibian host. Its prevalence of 83% (15/18) in black-spined toads within the 3 months after importation calls for strict quarantine measures and import regulation for lower vertebrates.
The article deals with the personality of Josef Scheiner as a Sokol official. It follows his activity in the Sokol organisation since the end of 1870s until the 1930s when Scheiner was a living Sokol legend. It perceives Scheiner's Sokol career crowned by the highest Sokol function - Mayor of Sokol in 1906. His career was topped off with the resistance during World War I and with the participation of the Sokol movement in the creation and consolidation of the Czechoslovak Republic during and after 1918. and Článek zahrnuje odkazy pod čarou