A cyanobacterium containing phycobiliproteins with far-red acclimation was isolated from Pozas Rojas, Cuatro Ciénegas, México. It was named Leptolyngbya CCM 4 after phylogenetic analysis and a description of its morphological characteristics. Leptolyngbya was grown in far-red light. Sucrose-gradient analysis of the pigments revealed two different colored bands of phycobiliproteins. A band at 60% sucrose was a phycocyanin containing phycobilisome; at 35% sucrose, a new type of phycobiliprotein absorbed at 710 nm. SDS-PAGE revealed the presence of two types of core-membrane linkers. Analysis of the hydrophobic pigments extracted from the thylakoid membranes revealed Chl a, d, and f. The ratio of Chl f/a was reversibly changed from 1:12-16 under far-red light to an undetectable concentration of Chl f under white light. Cuatro Ciénegas, a place surrounded by the desert, is a new ecosystem where a cyanobacterium, which grows in farred light, was discovered., C. Gómez-Lojero, L. E. Leyva-Castillo, P. Herrera-Salgado,
J. Barrera-Rojas, E. Ríos-Castro, E. B. Gutiérrez-Cirlos., and Obsahuje bibliografické odkazy
The Southern Urals are an inspiring place for Czech naturalists. This paper provides basic information on this seldom visited region and describes the impressions of the two Czech biologists from their excursion to this place. The nature of the Southern Urals captivated them with its wildness, unrivalled in present-day Central Europe, its intrinsic order and the similarities with Central European nature. and Jan Roleček, Jan Losík.
Physiological responses to light availability and soil flooding on Lindera melissifolia (Walt.) Blume were studied. Shrubs were grown under 70, 37 or 5% of full sunlight with either 0, 45, or 90 d of soil flooding. We measured leaf photosynthetic rate (PN) to test the hypothesis that soil flooding reduces PN in L. melissifolia following shrub acclimation to low light availability. Results showed that light availability and soil flooding interacted to affect PN. In the 0 d and
45 d flooding regimes (flood water removed 36-39 d prior to measurement), PN was similar between shrubs receiving 70% or 37% light, and these shrubs had 147% greater PN than shrubs receiving 5% light. Shrubs receiving 90 d of soil flooding had similar low rates of area-based PN regardless of light level. Similar PN between 0 d and 45 d flooded shrubs indicated physiological recovery following removal of flood water., B. R. Lockhart, E. S. Gardiner, T. D. Leininger, M. S. Devall, A. D. Wilson, K. F. Connor, P. B. Hamel, N. M. Schiff., and Obsahuje bibliografii
C3 photosynthesis at high light is often modeled by assuming limitation by the maximum capacity of Rubisco carboxylation (VCmax) at low CO2 concentrations, by electron transport capacity (Jmax) at higher CO2 concentrations, and sometimes by
triose-phosphate utilization rate at the highest CO2 concentrations. Net photosynthetic rate (PN) at lower light is often modeled simply by assuming that it becomes limited by electron transport (J). However, it is known that Rubisco can become deactivated at less than saturating light, and it is possible that PN at low light could be limited by the rate of Rubisco carboxylation (VC) rather than J. This could have important consequences for responses of PN to CO2 and temperature at low light. In this work, PN responses to CO2 concentration of common bean, quinoa, and soybean leaves measured over a wide range of temperatures and PPFDs were compared with rates modeled assuming either VC or J limitation at limiting light. In all cases, observed rates of PN were better predicted by assuming limitation by VC rather than J at limiting light both below and above the current ambient CO2. One manifestation of this plant response was that the relative stimulation of PN with increasing the ambient CO2 concentration from 380 to 570 µmol mol-1 did not decrease at less than saturating PPFDs. The ratio of VC to VCmax at each lower PPFD varied linearly with the ratio of PN at low PPFD to PN at high PPFD measured at 380 µmol(CO2) mol-1 in all cases. This modification of the standard C3 biochemical model was much better at reproducing observed responses of light-limited PN to CO2 concentrations from
pre-industrial to projected future atmospheric concentrations., J. A. Bunce., and Obsahuje bibliografii
We aimed to find out relations among nonphotochemical quenching (NPQ), gross photosynthetic rate (PG), and photoinhibition during photosynthetic light induction in three woody species (one pioneer tree and two understory shrubs) and four ferns adapted to different light regimes. Pot-grown plants received 100% and/or 10% sunlight according to their light-adaptation capabilities. After at least four months of light acclimation, CO2 exchange and chlorophyll fluorescence were measured simultaneously in the laboratory. We found that during light induction the formation and relaxation of the transient NPQ was closely related to light intensity, light-adaption capability of species, and PG. NPQ with all treatments increased rapidly within the first 1-2 min of the light induction. Thereafter, only species with high PG and electron transport rate (ETR), i.e., one pioneer tree and one mild shade-adapted fern, showed NPQ relaxing rapidly to a low steady-state level within 6-8 min under PPFD of 100 μmol(photon) m-2 s-1 and ambient CO2 concentration. Leaves with low PG and ETR, regardless of species characteristics or inhibition by low CO2 concentration, showed slow or none NPQ relaxation up to 20 min after the start of low light induction. In contrast, NPQ increased slowly to a steady state (one pioneer tree) or it did not reach the steady state (the others) from 2 to 30 min under PPFD of 2,000 μmol m-2 s-1. Under high excess of light energy, species adapted to or plants acclimated to high light exhibited high NPQ at the initial 1 or 2 min, and showed low photoinhibition after 30 min of light induction. The value of fastest-developing NPQ can be quickly and easily obtained and might be useful for physiological studies., S.-L. Wong, M.-Y. Huang, C.-W. Chen, J.-H. Weng., and Obsahuje bibliografii
Although maize (Zea mays L.) plants utilize light efficiently, the expression of high light-efficient genes and stomatal factors is regulated by light conditions and affects photosynthesis of plants. In this study, we investigated the effects of different light qualities on the expression of the photosynthetic genes, such as pep1, pdk1, ZmSTOMAGEN, and psad1, and on stomatal function in maize seedlings. For both maize genotypes, Zhengdan 958 and Xianyu 335, light with wavelengths shorter than 490 nm enhanced the expression of pdk1 and ZmSTOMAGEN, whereas the expression of pdk1 positively correlated with ZmSTOMAGEN. Light with wavelengths longer than 630 nm or shorter than 490 nm (band pass filter) increased the expression of pep1 and psad1. Although the expression of four genes in Zhengdan 958 was significantly higher than that of Xianyu 335, changes in the expression of ZmSTOMAGEN, pdk1, or pep1 exerted no significant influence on stomatal function and photosynthetic rate. Our results suggest that light with wavelengths shorter than 490 nm promoted the expression of stomatal proteins and pdk1, facilitated the absorption of inorganic elements, and contributed to stomatal function in photosynthesis. Meanwhile, light with wavelengths longer than 630 nm inhibited the expression of pep1 and pdk1. Light with wavelengths longer than 630 nm or shorter than 490 nm promoted the expression of pep1, pdk1, and psad1., T. D. Liu, X. W. Zhang, Y. Xu, S. Q. Liu, X. W. Chen., and Obsahuje bibliografii
a1_The emergence of cryptosporidiosis, a zoonotic disease of the gastrointestinal and respiratory tract caused by Cryptosporidium Tyzzer, 1907, triggered numerous screening studies of various compounds for potential anti-cryptosporidial activity, the majority of which proved ineffective. Extracts of Indonesian plants, Piper betle and Diospyros sumatrana, were tested for potential anti-cryptosporidial activity using Mastomys coucha (Smith), experimentally inoculated with Cryptosporidium proliferans Kváč, Havrdová, Hlásková, Daňková, Kanděra, Ježková, Vítovec, Sak, Ortega, Xiao, Modrý, Chelladurai, Prantlová et McEvoy, 2016. None of the plant extracts tested showed significant activity against cryptosporidia; however, the results indicate that the following issues should be addressed in similar experimental studies. The monitoring of oocyst shedding during the entire experimental trial, supplemented with histological examination of affected gastric tissue at the time of treatment termination, revealed that similar studies are generally unreliable if evaluations of drug efficacy are based exclusively on oocyst shedding. Moreover, the reduction of oocyst shedding did not guarantee the eradication of cryptosporidia in treated individuals. For treatment trials performed on experimentally inoculated laboratory rodents, only animals in the advanced phase of cryptosporidiosis should be used for the correct interpretation of pathological alterations observed in affected tissue. All the solvents used (methanol, methanol-tetrahydrofuran and dimethylsulfoxid) were shown to be suitable for these studies, i.e. they did not exhibit negative effects on the subjects. The halofuginone lactate, routinely administered in intestinal cryptosporidiosis in calves, was shown to be ineffective against gastric cryptosporidiosis in mice caused by C. proliferans., a2_In contrast, the control application of extract Arabidopsis thaliana, from which we had expected a neutral effect, turned out to have some positive impact on affected gastric tissue., Andrea Valigurová, Radka Pecková, Karel Doležal, Bohumil Sak, Dana Květoňová, Martin Kváč, Wisnu Nurcahyo, Ivona Foitová., and Obsahuje bibliografii
The apolipoprotein A-V (apo A-V) plays an important role in regulation of triglyceride (TG) concentration in serum. To better understand how apo A-V affects triglyceridemia and glucoregulation, the lipoprotein lipase (LPL) activity was determined using intravenous fat tolerance test (IVFTT) and oral glucose tolerance test (oGTT) was performed in carriers of apolipoprotein A-V gene ( APOAV) variants known to be associated with increased triglyceridemia. Twelve carriers of 19W variant, 16 carriers of -1131C variant, 1 combined heterozygote and 16 control subjects homozygous for wild type variants (19S/-1131T) were selected from a population sample and matched with respect to body mass index and age. The APOAV variants carriers had increased TG, very low density lipoprotein-TG, and apo B concentrations (p < 0.05). The LPL activity evaluated as k2 rate constant for clearance of Intralipid® was 14 % lower in APOAV variants carriers. The depression of nonesterified fatty acids (NEFA) concentration after glucose load was delayed in APOAV variants carriers in spite of the same insulinemia and glycemia. Our results suggest that variants of APOAV combined with increased triglyceridemia are associated with lower LPL activity in vivo and with disturbances of regulation of NEFA concentration after glucose load., J. Kovář, V. Adámková., and Obsahuje bibliografii a bibliografické odkazy
Zachovalé pralesovité porosty patří v České republice k ojedinělým úkazům. Přestože lesních rezervací u nás nalezneme celou řadu, ty skutečně málo dotčené nebo dlouhodobě se vyvíjející bez výrazných zásahů člověka představují pouhý zlomek. Zřejmě nejvýznamnějšími pralesům blízkými lesy jsou Boubínský prales nebo Hraničník na Šumavě a Žofínský prales v Novohradských horách. V minulosti byly málo ovlivněny činností člověka a dosti dlouhou dobu se v nich lesnicky nehospodaří. Příznivé podmínky pro přežívání vzácných druhů lišejníků a dalších organismů na těchto lokalitách jsou však omezeny jejich malou rozlohou. S větší plochou pralesa vzrůstají předpoklady pro dlouhodobou koexistenci různých fází vývoje přírodního lesa s dostatečnou variabilitou mikrostanovišť a tím se zároveň zvyšuje šance na přežití úzce specializovaných druhů. Žofínský prales patří k nejstarším chráněným územím v Evropě, je chráněn již od r. 1838. Národní přírodní rezervace Žofínský prales zaujímá v současné době 102 ha; jádrové území s pralesovitými porosty však tvoří jen 74,5 ha. Převažující dřevinou je buk, početně jsou zastoupeny také smrk a jedle. Z lichenologického hlediska jde o zcela unikátní lokalitu. Na území rezervace bylo zaznamenáno 247 druhů lišejníků, což představuje přibližně 16 % všech známých druhů z České republiky. Z hlediska epifytických a zejména epixylických (rostoucích na dřevě v různém stupni rozkladu) lišejníků je Žofínský prales zřejmě místem s největší rozmanitostí lišejníků na našem území., Žofín virgin forest forms a unique landscape, which probably predominated in mountain areas before the arrival of humans. Because of the huge diversity of lichens, the reserve is one of the most valuable lichenological localities in the Czech Republic. Many lichen taxa were recorded here for the first time in this country., and Jiří Malíček, Zdeněk Palice.