Současná diverzita tropické flóry a bioty Latinské Ameriky je výsledkem řady historických událostí, ke kterým došlo během jejího dlouhého vývoje. Výskyt stejných či příbuzných čeledí, rodů nebo druhů v oblastech a na kontinentech představujících součásti někdejšího prakontinentu Gondwana jsou výsledkem působení tří mechanismů: rozpadu souvislého areálu výskytu (vikariance) na území někdejší Gondwany, migrací rostlin přes kontinenty severní polokoule a disperzí přes oceány. Při mezikontinentálním rozšíření řady čeledí však často nehrál roli jen jeden z výše uvedených mechanismů, ale často šlo o jejich kombinace. Tím se stává studium historie různých taxonů komplikovanější. K jejímu odhalení je potřeba mít jasnou představu o stáří jejich jednotlivých vývojových linií, umožňující správnou interpretaci působení konkrétního mechanismu na jejich dnešní rozšíření a diverzitu., The tropical flora and biota of Latin America was influenced during its long history by several events that led to their current diversity and disjunct distribution. Three mechanisms have been proposed to explain the occurrence of the same or closely related families, genera and/or species among fragments of former Gondwana: vicariance, migration of plants across the continents and long distance dispersion. Recent intercontinental distribution of several taxa is commonly a result of their combination. Good knowledge of the age of principal lineages is needed for the correct interpretation of the effect of these mechanisms on the distribution and diversity of the investigated lineages., and Anna Potůčková, Daniel Stančík.
LED lamps with various combinations of red (R) and blue (B) wavelengths were used to supplement sunlight for the growth of a heat-resistant (HR) and heat-sensitive (HS) recombinant inbred lines (RIL) of lettuce. The RB-LED ratios were 100R:0B (0B), 92R:8B (8B), 84R:16B (16B), and 76R:24B (24B) with an equal PPFD of 100 μmol m-2 s-1. The greatest leaf expansion rates were observed at 8B for both genotypes. All HR-RILs had similar values of growth parameters and specific leaf area (SLA). However, higher values of growth parameters were observed in HS-RIL with 0B, 8B, and 16B than that under 24B and sunlight. Furthermore, HS-RIL had higher SLA under 0B compared to other conditions. Photosynthetic light-use efficiency and maximal oxygen evolution rate were the lowest under 8B for both genotypes. The quality of LED lighting, if provided, seemed to implicate genotype dependence, probably as a result of their different sensitivities to heat stress., T. W. Choong, J. He, L. Qin, S. K. Lee., and Obsahuje bibliografii
Quametopia gen. n. is established on the basis of recent phylogenetic analysis of taxa formerly assembled under the genus Mumetopia Melander, 1913 to include M. terminalis (Loew, 1863) and two new closely related Nearctic species of Anthomyzidae. The new genus is diagnosed and its phylogenetic relationships discussed. Quametopia terminalis (Loew, 1863) comb. n. is transferred from Mumetopia and redescribed based on revision of the type material (lectotypes of Anthophilina terminalis Loew, 1863 and its synonym Mumetopia nitens Melander, 1913 are designated) and other extensive material. Quametopia clintonia sp. n. and Q. amplistylus sp. n. (both from Canada, USA) are described and relationships of all three Quametopia species discussed. Immature stages of Q. terminalis and Q. clintonia sp. n. obtained by means of adult-to-adult rearing are described (1st- and 2nd-instar larvae for the first time in the family Anthomyzidae) and illustrated. Keys to adults, eggs, larvae and puparia of Quametopia species are presented. Biology (habitat and host-plant associations, life history) of Q. terminalis and Q. clintonia sp. n. are studied in detail and their ecological separation demonstrated. Distribution of all Quametopia species is reviewed. and Jindřich Roháček, Kevin N. Barber.
In this study, we presented a new approach for quantification of bicarbonate (HCO3-) molecules bound to PSII. Our method, which is based on a combination of membrane-inlet mass spectrometry (MIMS) and 18O-labelling, excludes the possibility of "non-accounted" HCO3- by avoiding (1) the employment of formate for removal of HCO3- from PSII, and (2) the extremely low concentrations of HCO3-/CO2 during online MIMS measurements. By equilibration of PSII sample to ambient CO2 concentration of dissolved CO2/HCO3-, the method ensures that all physiological binding sites are saturated before analysis. With this approach, we determined that in spinach PSII membrane fragments 1.1 ± 0.1 HCO3- are bound per PSII reaction center, while none was bound to isolated PsbO protein. Our present results confirmed that PSII binds one HCO3- molecule as ligand to the non-heme iron of PSII, while unbound HCO3- optimizes the water-splitting reactions by acting as a mobile proton shuttle., K. Tikhonov, D. Shevela, V. V. Klimov, J. Messinger., and Obsahuje bibliografické odkazy
A portable open gas-exchange system (Li-6400, Li-Cor, Inc., Lincoln, NE, USA) has been widely used for the measurement of net gas exchanges and calibration/parameterization of leaf models. Measurement errors due to diffusive leakage rates of water vapor (LW) and CO2 (LC) between inside and outside of the leaf chamber, and the inward dark transpiration rate (DW) and dark respiration rate (DC) released from the leaf under the gasket, can be significant. Rigorous model-based approaches were developed for estimating leakage coefficients of water vapor (KW) and CO2 (KC) and correcting for the combination of these errors. Models were based on mass balance equations and the Dusty Gas Model for a ternary gas mixture of water vapor, CO2, and dry air. Experiments were conducted using two Li-6400 systems with potato and soybean leaves. Results indicated that models were reliable for estimating KW and KC, and the values varied with instrument, chamber size, gasket condition, and leaf structure. A thermally killed leaf should be used for this determination. Measurement error effects on parameterization of the Farquhar et al. (1980) model as determined by PN/C i curves were substantial and each parameter had its own sensitivity to measurement errors. Results also indicated that all four error sources should be accounted for when correcting measurements., Q. Wang ... [et al.]., and Obsahuje bibliografii a dodatky