We studied the photosynthetic performance of sterile and fertile sporophytes in a natural population of the fern Dryopteris affinis growing within a riparian forest (Central Italy) using chlorophyll (Chl) a fluorescence transients, the OJIP phase, where O is for the minimum fluorescence, P is for the peak (the maximum), and J and I are inflections. The “vitality” of the samples was assessed by the maximum quantum yield of primary photochemistry obtained indirectly from the fluorescence data (Fv/Fm); in the same way, the so-called performance index (PIABS) was obtained from fluorescence data. The photosynthetic performance (inferred from PIABS) of D. affinis changed significantly with the seasonal development of the fronds. The highest photosynthetic performance was recorded in the summer, corresponding to the period of spore release. The photosynthetic performance decreased in the winter, down to the minimal values of senescent fronds reached at the end of the seasonal cycle (May-June). On the whole, during the seasonal development, sterile and fertile fronds had a similar photosynthetic behaviour, as inferred from fluorescence data. At the end of spore maturation and dispersal (September-October), the fertile fronds showed somewhat lower photosynthetic performance than the sterile fronds, as revealed by PIABS. Being a long-lived fern, confined to humid and undisturbed sites in the Mediterranean, D. affinis deserves to be further investigated as a potential indicator of ecological continuity in Mediterranean riparian forests., L. Paoli, M. Landi., and Obsahuje bibliografii
The effects of a high temperature on leaf photosynthetic response of Lupinus albus, a species native from the Mediterranean zone, were studied under varying tissue water status and irradiance (/). At leaf temperatures optimal (25 °C) or near-optimal (15 ®C) for carbon assimilation in lupins, photosynthetic capacity (P^) was decreased at leď relative water content (RWC) around 60 %. The temperature above the optimum (e g. 35 oC) decreased at high RWC (80 %). Irrespective of the leaf water status the optimum leaf temperature for in lupins was around 25 "C. The inhibition of P^ by lupin leaf discs at 35 °C was greatly enhanced at high I. Leaf disc treatment at 35 in the dark did not change quantum yield or Pn. When in addition to 35 the leaves were subjected to high I (TS + IS) or to high I and dehydration (TS + IS + WS), then a substantial decrease was observed in the quantum yield (66 and 77 % of the values in Controls, respectively) and in (31 and 56 %, respectively).
Plants of Solanum curtilobum (from high altitude) and Solanum tuberosum (from low altitude) were grown in open-top chambers in a greenhouse at either ambient (AC, 360 µmol mol-1) or ca. twice ambient (EC, 720 µmol mol-1) CO2 concentrations for 30 d. CO2 treatments started at the reproductive stage of the plants. There were similar patterns in the physiological response to CO2 enrichment in the two species. Stomatal conductance was reduced by 59 % in S. tuberosum and by 55 % in S. curtilobum, but such a reduction did not limit the net photosynthetic rate (PN), which was increased by approximately 56 % in S. curtilobum and 53 % in S. tuberosum. The transpiration rate was reduced by 16 % in both potato species while instantaneous transpiration efficiency increased by 80 % in S. tuberosum and 90 % in S. curtilobum. Plants grown under EC showed 36 and 66 % increment in total dry biomass, whereas yields (dry mass of tubers) were increased by 40 and 85 % in S. tuberosum and S. curtilobum, respectively. EC promoted productivity by increasing PN. Thus S. tuberosum, cultivated around the world at low altitudes, and S. curtilobum, endemic of the highland Andes, respond positively to EC during the tuberisation stage. and N. Olivo, C. A. Martinez, M. A. Oliva.
The aim of the study was to investigate the genetic distances and their relationships among pepper species using photosynthetic features under different stresses and genetic variability. The photosynthetic features under drought, waterlogging and
low-temperature stresses, rDNA internal transcribed spacer (ITS) sequences of nuclear genome and trnH-psbA sequence of chloroplast genome of 25 varieties from 5 pepper species Capsicum annuum L. (CA), Capsicum baccatum L. (CB), Capsicum chinense Jacquin. (CC), Capsicum frutescens L. (CF) and Capsicum pubescens Ruiz & Pavon (CP) were analyzed and used to construct the dendrograms. The results showed the photosynthetic rate of different pepper species could be greatly but differentially decreased by stresses. For example, CB and CF had the smallest and the highest decrease to drought, CC had the highest decrease to waterlogging, and CP had the smallest decrease to low temperature. The ITS sequences of 25 pepper varieties are 591-619 bp in length and have GC% between 51.1% and 64.5%. Their trnH-psbA sequences are 537-558 bp in length and have GC% between 27.2% and 28.5%. The cluster analysis of the five pepper species based on the changes in PN under stresses is similar to that based on genetic variability, that is, CP clusters with CB, and CC clusters with CA after first clusters with CF. In addition, the clustering methods based on the photosynthetic stress responses and genetic variability are unable to completely distinguish pepper varieties within the same species. The results indicate that similarly to genetic variability, changes in PN under stresses (specifically the stress corresponding to the climate of plant’s original habitat) could be used to identify genetic distance of pepper species., L. J. Ou and X. X. Zou., and Obsahuje bibliografii
Ultrafast time resolved emission spectra were measured in whole cells of a PSI-deficient mutant of Synechocystis sp. PCC 6803 at room temperature and at 77K to study excitation energy transfer and trapping. By means of a target analysis it was estimated that the terminal emitter of the phycobilisome, termed allophycocyanin 680, transfers its energy with a rate of (20 ps)-1 to PSII. This is faster than the intraphycobilisome energy transfer rates between a rod and a core cylinder, or between the core cylinders., A. M. Acuña, P. Van Alphen, R. Van Grondelle, I. H. M. Van Stokkum., and Obsahuje bibliografické odkazy
The small subunit ribosomal RNA gene (SSU rDNA) of two freshwater and one marine species of the genus Chloromyxum Mingazzini, 1890 were sequenced. The SSU rDNA trees obtained show the phylogenetic position of the marine species Chloromyxum leydigi Mingazzini, 1890 to be at the base of the freshwater clade, being well supported by a high bootstrap value. Chloromyxum cyprini Fujita, 1927 is closely related to Chloromyxum truttae Léger, 1906 and they represent a sister branch to raabeia sp., Myxidium sp. and Myxidium truttae Léger, 1930. Chloromyxum legeri Tourraine, 1931 is in a position ancestral to Myxidium lieberkuehni Bütschli, 1882 and Sphaerospora oncorhynchi Kent, Whitaker et Margolis, 1993. Three newly sequenced species of the genus Chloromyxum represent three separate lineages within the myxosporean tree and do not support the monophyly of this genus.
Isoflavones are a subgroup of phytoestrogens, natural plant substances with structure similar to 17-β-estradiol and capable of binding to estrogen receptors (ERs). Isoflavones possess higher affinity to ERβ than to ERα and may have a potency to activate both genomic and non-genomic estrogen signaling pathways. In addition, isoflavones interact with the metabolism of steroid hormones. Therefore, the actions of isoflavones are rather complex and may be related to large number of factors, which are not satisfactorily identified yet. Recently, isoflavones have come into focus of interest due to several reports about their positive effect on human health, in particular prevention of hormone-dependent cancers, cardiovascular diseases, osteoporosis, adverse menopausal manifestations and agerelated cognitive decline. Isoflavones may bring new insights into the mechanisms of physiological regulations and increase the possibilities of medical interventions., L. Pilšáková, I. Riečanský, F. Jagla., and Obsahuje bibliografii a bibliografické odkazy
Tropical savanna ecosystems are extremely diverse and important for global carbon storage. In the state of Mato Grosso, tropical savanna (locally known as the Cerrado), turns from well-drained, upland areas into seasonally flooded areas within the Pantanal; however, the Cerrado and the Pantanal share many common tree species, such as Vochysia divergens, a flood-adapted tree native to the Amazon Basin, and Curatella americana, a tree, adapted native to the welldrained the Cerrado. We measured the photosynthetic light response of these species in the the Cerrado and the Pantanal over a 1-year period to determine how these species physiologically adjust to these hydrologically distinct habitats. We hypothesized that neither species would experience a significant decline in maximum, light-saturated photosynthetic rate (Pmax) in their naturalized habitat. Physiological performance of each species was generally higher in the habitat that they were adapted to; however, our data indicated that both species have broad tolerance for seasonal variations in hydrology, allowing them to tolerate seasonal drought during the dry season in the Cerrado, and seasonal flooding during the wet season in the Pantanal. In V. divergens, flexible water-use efficiency, higher specific leaf area (SLA), and a greater ability to adjust mass-based Pmax (Pmax,m) to variations in leaf N and P concentration appeared to be key traits for withstanding prolonged drought in the Cerrado. In C. americana, increases in SLA and higher nutrient-use efficiency appeared to be important in maintaining high rates of Pmax,m in the seasonally flooded Pantanal. Flexibility in physiology and resource-use efficiency may allow these species to survive and persist in habitats with broadly differing hydrology., H. J. Dalmagro, F. de A. Lobo, G. L. Vourlitis, Â. C. Dalmolin, M. Z. Antunes Jr., C. E. R. Ortíz, J. de S. Nogueira., and Obsahuje bibliografii
The plasmonic properties of heavy doped semiconductors at a terahertz and far infrared frequencies are discussed in this article. Special attention is devoted to the semiconductors due to their tunability, extremely low effective masses and exceptionally high carrier mobility. Mathematical model is based on Drude-Lorentz oscillators that bring the properties of free electron gas and heteropolar lattice vibrations. The experimental values for indium antimonide n-doped at the 1017 cm-3 are used for calculations. The resonant quality, electric field amplification and dipolar moment are presented for five nanoantennas with different shapes. and V článku sú diskutované plazmonické vlastnosti ťažko dopovaných polovodičov v terahertzovej a ďalekej infračervenej oblasti. Špeciálna pozornosť je venovaná polovodičom z dôvodu ľaditeľnosť ich vlastností, veľmi nízkej efektívnej hmotnosti a výnimočne vysokej pohyblivosti elektrónov. Permitivita materialu je počítaná na základe Drudeho-Lorentzovho modelu, ktorý zahŕňa vlastnosti voľných elektrónov, aj vibrácie heteropolárnej mriežky materiala. Pri výpočtoch sú použité experimentálne hodnoty odmerané na polovodiči n-dopovanom polovodiči indium antimód s koncentráciou vodivostných elektrónov 1017 cm-3. Prezentované výsledky rezonančnej kvality, zosilnenia elektrického poľa a radiačného dipólového momentu sú vypočítané pre päť nanoantén rôzneho tvaru.
The cells of purple photosynthetic bacterium Rhodobacter sphaeroides embedded in stretched polymer films were irradiated by strong polarized "white light" with an electric vector parallel to the direction of film stretching. The polarized absorption and photoacoustic spectra before and after strong irradiation were measured. Measurements of absorbance showed no confident anisotropy before and after strong irradiation. In contradiction, the photoacoustic method showed after strong irradiation some changes in anisotropy of thermal deactivation due to the perturbation of the fate of excitations. The increase in yield of thermal deactivation, higher in a region of light-harvesting complex 2, can be explained by the irreversible changes in the conformation of the complexes due to strong irradiance reported up to now predominantly for thylakoid antenna complexes. and J. Goc, K. Klecha.