Young plants of Calamagrostis epigejos (L.) Roth were grown in controlled environments with two regimes of CO2 in the air: normál (350 cm^ m'^) and elevated (700 cm^ m‘3). The relative growth rate of plants grown at elevated CO2 was increased by about 20 % in comparison with control plants cultivated at ambient CO2 concentration. Partitioning of assimilates into roots (+ rhizomes) and shoots was the same in both treatments. Slightly lower values of specifíc leaf area, leaf mass ratio and leaf area ratio were found in the plants grown at elevated CO2. The net photosynthetic rate (P^) was measured gasometrically in plants from both treatments at 350 and 700 cm^ m"^ CO2 in the leaf chamber. There were no signifícant differences between plants grown at either CO2 concentration in their responses to radiation and CO2 conditions during measurements, i.e., no regulation of photosynthetic processes in response to elevated CO2 was detectable. at saturating irradiance and maximum apparent quantum yield of photosynthesis were always considerably higher at doubled CO2 concentration during measurements.
Net photosynthetic rate (PN) was studied in field-grown peanut cv. GG 2 in relation to leaf position, time of day, reproductive-sink, and phenophase. In general, PN remained higher in the upper leaves (first from top to the fourth) than in the lower leaves (fifth to eighth). The mean PN of the leaves situated upper and the leaves lower in the canopy increased from the morning, reached a maximum during noon hours, and decreased thereafter. Between 09:00 to 10:00 h, PN, stomatal conductance (gs), and transpiration rate (E) in the upper leaves were higher than in the lower leaves, but between 12:00 and 13:00 h, these activities increased significantly in the lower leaves. Highest PN was found during pod-development phase. Removal of flowers, and hence of active reproductive-sink, decreased plant height and number of leaves, and initiated accumulation of photosynthates in the leaves. The PN per unit leaf area in plants with reproductive-sink (WRS) was similar to those without reproductive-sink (WORS). However, leaf area of WORS plants decreased significantly, mainly due to the reduction in number of leaves. No feed-back inhibition of PN (per unit leaf area) was found despite accumulation of photosynthates in the leaves as a result of removal of the active reproductive-sink. and P. C. Nautiyal, V. Ravindra, Y. C. Joshi.
We investigated net photosynthetic rate and antioxidative enzyme activities in Erythrina orientalis grown in three different sites: Makati and Quezon (cities with high levels of air pollution, HP) and La Mesa (a non-polluted area, NP). Photosynthetic activity of E. orientalis was significantly reduced in the HP cities. In contrast, activities of the antioxidative enzymes ascorbate peroxidase and glutathione reductase were significantly higher in HP cities than in the NP area. and S. Y. Woo, D. K. Lee, Y. K. Lee.
Teprve v roce 2001 byl v Evropě popsán jako nový druh netopýr Myotis alcathoe. Byl rozlišen jako kryptický druh z komplexu netopýra vousatého (M. mystacinus). Následné studie ale ukázaly, že skupina evropských druhů M. mystacinus, M. brandtii a M. alcathoe nezahrnuje druhy příbuzné, ale jen velmi podobné. V roce 2005 byl M. alcathoe nalezen i v České republice. V současnosti probíhá výzkum jeho ekologie, která se v mnohém ukazuje jiná než u ostatních podobných druhů. and Only in 2001 was the Alcathoe Bat (Myotis alcathoe) described as a new species in Europe. It was distinguished as a separate, cryptic species from the Whiskered Bat (M. mystacinus) complex. Moreover, further studies revealed that the group consisting of the Alcathoe Bat, Whiskered Bat and Brandt’s Bat (M. brandtii), includes an unrelated, but very similar species. In 2005, the Alcathoe Bat was also recorded in the Czech Republic and its ecology is currently being studied: it seems to be quite different in comparison with similar species.
Lom, ohyb a odraz světla jsou jevy, s nimiž se potkáváme denně. Pochopit je však nemusí být zejména pro laiky jednoduché, přestože se jedná o téma, které je součástí školní výuky. Zákonitosti šíření světla ovšem plynou velmi jednoduše z několika základních principů optiky a dají se také velice názorně demonstrovat. V tomto příspěvku se jim věnujeme poněkud netradičním způsobem, od výkladu velmi jednoduchého a pochopitelného až po nečekanou aplikaci doládající, že zakřivení trajektorie tělesa v gravitačním poli má vlastně stejný původ jako lom či ohyb světla. and Tomáš Tyc, Jana Musilová.
Intriguing power of weak bonds (Noncovalent interactions in biodisciplines). The role of weak noncovalent interactions in nature, especially in biodisciplines, is demonstrated. First, it is emphasized how strongly properties of the most common solvent and biomedium, water, are influence by noncovalent interactions. Also structure and properties of typical biomolecules, nucleic acids and proteins result from noncovalent interactions, and the important role of dispersion forces in these systems is stressed. The physical origin of the noncovalent interactions is explained. The very important manifestation of the noncovalent interactions in biology, hydrogen bond, is extended to the newly discovered type of hydrogen bond, called improper (blue-shifted) hydrogen bond. Finally, the role of noncovalent interactions in silico drug design is briefly discussed.
U evolučně původnější skupin žab drží samec při páření samici v oblasti beder (inguiální amplexus). Zdokumentováno bylo pozorování netypického chování páru kuňky žlutobřiché (Bombina variegata) při amplexu axilárním (úchop za předními končetinami). and In the evolutionarily more original frog groups, during mating the male frogs keep the female frog just in front of the hind legs. However, atypical behaviour in a Yellow-Bellied Toad (Bombina variegata) pair, when the male kept just behind the female’s front legs, has been documented by the author.