The natural occurrence and altitudinal pattern of species with C4 photosynthesis were investigated on Qinghai Plateau, Qinghai province by using stable carbon isotopes in plant leaves and using additional data from references. A total of 58 species belonging to 10 families and 34 genera were identified using C4 photosynthetic pathway, which is only 1.66 % of total 3 500 plant species in Qinghai province. The leading two families, i.e. Gramineae (23 species) and Chenopodiaceae (22 species) contain 77.6 % of all C4 plants in the studied area. The number of C4 species increased from 1 600 to 2 400 m a.s.l. and then decreases quickly till 4 400 m a.s.l. with one half of C4 species distributing from 2 200 to 2 800 m a.s.l. (48 %). Eight plant species were found above 4 000 m a.s.l., but the distribution of these species is limited to the south of Qinghai province (low latitude area) where annual mean temperature is above 0 °C, suggesting that low temperature may generally limit the distribution of C4 plants. and M. C. Li, J. J. Zhu, L. X. Li
Cell membranes of the cyanobacterium Phormidium lamino.sum were separated into two fractions by centrifugation in a stepwise sucrose gradient. One fraction contained mature thylakoid membranes and the other one contained membranes morphologically similar to primary membranes of pea etiochloroplasts. The latter ones represented an electron-transparent base with numerous electron-dense inclusions. The predominant type of the inclusions was rod-like structures containing presumably ribosomes.
Manuscripts from the abandoned library of the Premonstratensian Abbey of St Peter at Weißenau near Ravensburg are currently held in many European and American libraries. After the abbey was secularised in 1802 the library the Counts of von Sternberg-Manderscheid tool possession of it and after 1830 it was incorporated into the Prague palace library of the House of Lobkowicz, with which it was transferred in 1928 to what i snow the National Library of the Czecgh Republic. The manuscript collection of Prague Lobkowicz Library (shelf mark XXIII) contains almost a half of the extant Weißenau collection numbering circa 90 codices. The study delivers the results of systematic research into ownership notes in this file that uncovered fragments of several interesting private libraries of the fifteenth and sixteenth century from the territory of the Constance Diocese.
Twentieth-century photosynthesis research had strong roots in Germany, with the cell physiologist Otto H. Warburg being among its most influential figures. He was also one of the few scientists of Jewish ancestry who kept his post as a director of a research institution throughout the Nazi period. Based on archival sources, the paper investigates Warburg’s fate during these years at selected episodes. He neither collaborated with the regime nor actively resisted; he was harrassed by bureaucracy and denunciated to the secret police, but saved by powerful figures in economy, politics, and science. Warburg reciprocated this favour with problematic testimonies of political integrity after 1945. Warburg’s case, thus, defies wellestablished notions of how scientists in Germany lived and worked during the Nazi regime, and, therefore, helps provide a more nuanced perspective on this theme., K. Nickelsen., and Obsahuje bibliografické odkazy
In this brief communication we provide an estimate of the part of the incident solar energy used for oxygen evolution as well as the time, in years, needed for the generation of the present amount of molecular oxygen in the biosphere by photosynthesis on land and in the ocean. We find this to be ~3,000 yr. We also find that the ocean produces 22% more oxygen than the land surface., A. Yu. Borisov, L. O. Björn., and Obsahuje bibliografické odkazy
The variable fluorescence at the maximum Fm of the fluorescence induction (Kautsky) curve is known to be substantially suppressed shortly after light adaption due to nonphotochemical qE quenching. The kinetic pattern of the dark decay at Fm consists of three components with rates ~20, ~1, and ~0.1 s-1, respectively. Light adaptation has no or little effect on these rate constants. It causes a decrease in the ratio between the amplitudes of the slow and fast one with negligible change in the small amplitude of the ultra-slow component. Results add to evidence for the hypothesis that the dark-reversible decrease in variable fluorescence accompanying light adaptation during the P-S phase of the fluorescence induction curve is due to an alteration in nonphotochemical qE quenching caused by changes in the trans-thylakoid proton motive force in response to changes in the proton conductance gH+ of the
CF0-channel of the CF0·CF1·ATPase., W. J. Vredenberg., and Obsahuje bibliografické odkazy
The review deals with objective reasons that limit the use of chlorophyll fluorescence induction kinetics (Chl FIK) method in plant ecology. Based on the ontogenetic approach (analysis and comparison of the dynamics of the Chl fluorescence ratio Fp/Fs and physiological characteristics of plant leaves in ontogeny) possible criteria for the estimation of general plant resistance of photosynthetic apparatus (PSA) to prolonged stress affects are proposed. One of these criteria is the presence or absence of a steady-state phase in the dynamics of Chl fluorescence ratio Fp/Fs (or Rfd) of plant leaves after they stop growing. We also propose to use the duration of the steady-state phase and variability of Chl fluorescence ratios Rfd and Fp/Fs in this period for quantitative assessment of plant PSA resistance to prolonged stress during plant leaf ontogeny. and T. V. Nesterenko, A. A. Tikhomirov, V. N. Shikhov.
Ontogenetic changes of rates of photon-saturated photosynthesis (Psat) and dark respiration (RD) of individual leaves were examined in relation to nitrogen content (Nc) in rice, winter wheat, maize, soybean, field bean, tomato, potato, and beet. Psat was positively correlated with Nc as follows: Psat = CfNc + Psat0, where Cf and Psat0 are coefficients. The value of Cf was high in maize, medium in rice and soybean, and low in field bean, potato, tomato, and beet, of which difference was not explained by ribulose-1,5-bisphoshate carboxylase/oxygenase (RuBPCO) content. RD was explained by Psat and/or Nc, however, two models must be applied according to plant species. RD related linearly with Psat and Nc in maize, field bean, and potato as follows: RD = a Psat + b, or RD = a'Nc + b', where a, a', b and b' are coefficients. In other species, the RD/Psat ratio increased exponentially with the decrease of Nc as follows: RD/Psat = a exp(b Nc), where a and b are coefficients. Therefore, RD in these crops was expressed as follows: In(RD) = ln(a Psat) + b Nc, indicating that RD in these crops was regulated by both Psat and Nc. and M. Osaki ... [et al.].