Irradiance prior to and during desiccation improves the tolerance to excess irradiance in the desiccated state of the old forest lichen Lobaria pulmonaria

Hydrated thalli of the lichen Lobaria pulmonaria were either preconditioned to dim irradiance (DI, 5 μmol m⁻² s⁻¹) or medium irradiance (MI, 200 μmol m⁻² s⁻¹) for 6 h. After this 6 h period, the thalli were allowed to desiccate under the two respective irradiances. Thereafter, these dry lichens were exposed to high irradiance (HI, 1 000 μmol m⁻² s⁻¹) for 60 h. After this HI treatment, the maximal photochemical quantum yield (F_V/F_M) and the de-epoxidation state of xanthophyll cycle pigments (DEPS) were highest in thalli preconditioned to MI. Hence irradiance in the last hydrated period before sampling is significant for the physiological state of lichens. A standardized irradiance pre-treatment before start of experiments is recommended.     

Modelling the dynamics of the electron transport rate measured by PAM fluorimetry during Rapid Light Curve experiments

We propose a dynamic model specifically designed to simulate changes in the photosynthetic electron transport rate, which is calculated from fluorescence measurements when plants are exposed, for a short time, to a series of increasing photon flux densities. This model simulates the dynamics of the effective yield of photochemical energy conversion from the maximum and natural chlorophyll fluorescence yields, taking into account a cumulative effect of successive irradiations on photosystems. To estimate a characteristic time of this effect on photosystems, two series of experiments were performed on two benthic diatom culture concentrations. For each concentration, two different series of irradiations were applied. Simplified formulations of the model were established based on the observed fluorescence curves. The simplified versions of the model streamlined the parameters estimation procedure. For the most simplified version of the model (only 4 parameters) the order of magnitude of the characteristic time of the residual effect of irradiation was about 38 s (within a confidence interval between 20 and 252 s). The model and an appropriate calibration procedure may be used to assess the physiological condition of plants experiencing short time-scale irradiance changes in experimental or field conditions.     

Prenylated flavonoids and total extracts from Morus nigra L. root bark inhibit in vitro growth of plant pathogenic fungi

Total extracts and kuwanon G from Morus nigra root bark showed antifungal activity against several phytopathogenic fungi, with minimal inhibitory concentration (MIC₅₀) ranging from 32 to 128 μg/ml and from 16 to 64 μg/ml, respectively. Acetonic extracts inhibited 60% B. cinerea biofilm formation at concentration of 128 μg/ml.     

Lessons Learned from Reconstructing Interactions Between Local Ecological Knowledge, Fisheries Science, and Fisheries Management in the Commercial Fisheries of Newfoundland and Labrador, Canada

Questions centered on the development of local and traditional ecological knowledge and the relationship of that knowledge to the development of conservation and management practices have recently attracted critical attention. We examine these questions with respect to the dynamic commercial fisheries of the Canadian province of Newfoundland and Labrador. The knowledge of fish harvesters coevolves with fishing practices and is embedded in a dynamic socioecological network that extends into and beyond the fisher, fishery households, and communities to include management, technologies, markets, and marine ecological conditions. Changes in these networks have moved knowledge and practices related to fishing in directions defined by policy, science, economic rationality, and new ecological realities. We characterize this movement as a shift along a continuum from local ecological knowledge (LEK) towards globalized harvesting knowledge (GHK) as harvesters become increasingly disconnected from socioecological relationships associated with traditional species and stocks. We conclude with a discussion of how LEK/GHK have interacted over time and space with other knowledge systems (particularly science) to influence management, and suggest that contingent, empirical evaluations of these interactions will provide a fruitful avenue for future interdisciplinary research.

Prediction of early termination from the self-regulatory treatment of chronic headache

The ability of demographic, psychological testing and history information to predict which patients will terminate early from nonpharmacological treatment of headache (relaxation and biofeedback) was tested. Information from each of these areas was initially examined for differences between dropouts and treatment completers using univariate analyses. These analyses were followed by a canonical discriminate function analysis that predicted whether patients would complete treatment or drop out. Information from the three predictor sets combined resulted in 77.4% of the patients being correctly classified.This research was supported by a grant from the NINCDS, NS15235.     

Mating system of Helianthemum squamatum (Cistaceae), a gypsophile specialist of semi-arid Mediterranean environments

Aragán C. F. and Escudero A. 2008. Mating system of Helianthemum squamatum (Cistaceae), a gypsophile specialist of semi-arid Mediterranean environments. Bot. Helv. 118: 129–137 Plants living on gypsum have received remarkably little study, despite being one of the most important groups of endemic and rare plants in arid and semi-arid regions. This work is among the first to study the mating system of a gypsophyte, Helianthemum squamatum (Cistaceae), which is a short-lived perennial endemic to gypsum habitats of the Iberian Peninsula. We carried out a hand-pollination experiment, considering the following pollination treatments: autogamy, geitonogamy, xenogamy and control (open-pollination). Generalized linear mixed models were fitted to evaluate the effect of the treatment on the fruit set and the number of viable seeds yielded per fruit. Both response variables were significantly higher in the xenogamy treatment than in the autogamy and geitonogamy treatments. No significant differences were detected between the xenogamy treatment and the control group, indicating that H. squamatum is mainly an outcrosser although partially self-compatible. Our results also suggest that pollen limitation may only slightly affect the reproductive success of H. squamatum. In contrast with the general tendency towards self-compatibility previously described in short-lived species of the Cistaceae, this outcrossing mating system resembles the one of long-lived perennials Submitted 10 April 2008; Accepted 25 August 2008 Subject editor: Christian Parisod     

A provisional model to predict blood pressure response to biofeedback-assisted relaxation

Blood pressure (BP) response to biofeedback-assisted relaxation is not uniform among hypertensive individuals. The purpose of this exploratory study was to determine if selected psychophysiological variables could be used to identify individuals able to lower blood pressure using biofeedback-assisted relaxation. Responders were defined using a preset criterion of 5 mm Hg or greater decrease in mean arterial pressure. A logistic regression model derived from five variables (heart rate, finger temperature, forehead muscle tension, plasma renin response to furosemide, and mean arterial pressure response to furosemide) provided significant predictive power for BP response, exhibiting a sensitivity of 84.6% and a specificity of 80.0%. With future validation, the proposed model may provide useful information to identify patients likely to benefit from biofeedback-assisted relaxation.     

Elevated CO2 concentration enhances the role of the ear to the flag leaf in determining grain yield of wheat

Net photosynthetic rate (P _N) of ear and flag leaf during grain filling stage and grain yield of plants with non-darkened or darkened flag leaf or darkened ear were examined in two different CO₂ concentrations: ambient (AC) and AC+200 μmol mol⁻¹ (EC). Ear showed much higher enhancement (56 %) of P _N than flag leaf (23 %) under EC. Moreover, CO₂ enrichment shortened the photosynthetic duration of flag leaf relative to ear. In this way the ratio of ear to flag leaf contribution to grain yield increased from 1.18 (AC) to 1.39 (EC).     

A fluorescence microscopy method for quantifying the detection of prostaglandin endoperoxide H synthase-1 and CD-41 in MEG-01 cells

In platelets, PGHS-1-dependant formation of thromboxane A₂ is an important modulator of platelet function and a target for pharmacological inhibition of platelet function by aspirin. Since platelets are anucleated cells, we have used the immortalized human megakaryoblastic cell line MEG-01, which can be induced to differentiate into platelet-like structures upon addition of TPA as a model system to study PGHS-1 gene expression. Using a specific antibody to PGHS-1 we have developed a technique using immunofluorescence microscopy and analysis of multiple digital images to monitor PGHS-1 protein expression as MEG-01 cells were induced to differentiate by a single addition of TPA (1.6 × 10⁻⁸ M) over a period of 8 days. The method represents a rapid and economical alternative to flow cytometry. Using this technique we observed that TPA induced adherence of MEG-01 cells, and only the non-adherent TPA-stimulated cells demonstrated compromised viability. The differentiation of MEG-01 cells was evaluated by the expression of the platelet-specific cell surface antigen, CD-41. The latter was expressed in MEG-01 cells at the later stages of differentiation. We demonstrated a good correlation between PGHS-1 expression and the overall level of cellular differentiation of MEG-01 cells. Furthermore, PGHS-1 protein expression, which shows a consistent increase over the entire course of differentiation can be used as an additional and better index by which to monitor megakaryocyte differentiation. Published: December 12, 2001     

Protein composition analysis of oil bodies from maize embryos during germination

Seed oil bodies (OBs) are intracellular particles that store lipids. In maize embryos, the oil bodies are accumulated mainly in the scutellum. Oil bodies were purified from the scutellum of germinating maize seeds and the associated proteins were extracted and subjected to 2-DE analysis followed by LC-MS/MS for protein identification. In addition to the previously known oil body proteins oleosin, caleosin and steroleosin, new proteins were identified.     

Nitrate reduction in ramets of a clonal plant Eichhornia crassipes responding to nitrate availability during clonal growth stage

Effect of nitrate availability on nitrate reduction was examined in inter-connected ramets of invasive clonal plant Eichhornia crassipes grown with two nitrate supply regimes during different clonal growth stage. Increase of nitrate availability accelerated nitrate reductase activity (NRA) in parent and offspring ramets of E. crassipes, and there was greatly different pattern in inter-connected ramets during clonal growth stage. Leaf NRA was lower in offspring than that in parent ramets in phase 1, while significantly higher leaf NRA in offspring ramets was detected during phase 2. The results indicated NRA in inter-connected ramets of E. crassipes was highly dependent on nitrate availability and growth stage.     

T cell integrin overexpression as a model of murine autoimmunity

Integrin adhesion molecules have important adhesion and signaling functions. They also play a central role in the pathogenesis of many autoimmune diseases. Over the past few years we have described a T cell adoptive transfer model to investigate the role of T cell integrin adhesion molecules in the development of autoimmunity. This report summarizes the methods we used in establishing this murine model. By treating murine CD4+ T cells with DNA hypomethylating agents and by transfection we were able to test thein vitro effects of integrin overexpression on T cell autoreactive proliferation, cytotoxicity, adhesion and trafficking. Furthermore, we showed that the ability to inducein vivo autoimmunity may be unique to the integrin lymphocyte function associated antigen-1 (LFA-1). Published: October 24, 2003     

Preliminary results from the self-regulatory treatment of high-medication-consumption headache

Data are presented from a prospective clinical replication series of ten consecutive high-medication headache patients who presented for nondrug treatment of their headaches. For the first eight, an attempt was made to withdraw the patients from medication, with the assistance of relaxation training, prior to entering a comprehensive self-regulatory treatment program. For the last two, drug withdrawal accompanied the treatment. Six of the ten patients showed clinically significant reductions in headache activity, which held up over follow-ups of up to 12 months. Psychological tests provide some discrimination between success and failures.This research was supported in part by a grant from NINDS, No. NS-23340. Appreciation is expressed to Dr. Kenneth A. Appelbaum and Ms. Denise Michultka for their roles in this study.     

A highly specific glyoxylate reductase derived from a formate dehydrogenase

A Glu141Asn mutant Paracoccus sp. 12-A formate dehydrogenase catalyzes marked glyoxylate reduction. Additional replacement of the His332-Gln313 pair with His-Glu, which is a consensus acid/base catalyst in D-hydroxyacid dehydrogenases, further improved the catalytic activity of the enzyme as to glyoxylate reduction through enhancement of the hydrogen transfer step in the catalytic process, slightly shifting the optimal pH for the reaction. On the other hand, the replacement induced no marked activity toward other 2-ketoacid substrates, and diminished the enzyme activity as to formate oxidation. Consequently, the formate dehydrogenase was converted to a highly specific and active glyoxylate reductase through only the two amino acid replacements.     

Photosynthetic behaviour of Arabidopsis plants with a Cap Binding Protein 20 mutation under water stress

Under non-stressed conditions the net photosynthetic rate (P _N) of the mutant plants cbp20 of Arabidopsis was similar to that of the wild type (WT). In response to water deprivation, however, P _N started to decrease later in the mutants and remained substantially higher. Thermoluminescence measurements showed that the lipid peroxidation induced by severe water stress was also less pronounced in the mutant than in the WT. Both soil gravimetric and plant water potential data showed that cbp20 mutants lose water more slowly than the WT plants. The drought-induced decline in F_v/F_m, the quantum efficiency of photosystem 2, and photochemical quenching parameters also started later in the cbp20 mutants than in the WT plants. Thus the restricted gas exchange in the cbp20 mutants does not impair the photosynthetic performance of the plant; however, under drought improved water retention provides significant protection for the photosynthetic apparatus.     

Studies on lavandin callus cultures: Ethylene production in relation to the growth

Ethylene production and growth of callus cultures of lavandin (Lavandula offidnalis Cham x Lavandula latifolia Villars) cv. Grosso were examined. Callus lines, derived from various kinds of primary expiants (shoot tip, leaf and calyx), exhibited differences in ethylene production patterns independent of callus growth. Moreover these differences could not be ascribed to the expiant source. Within a line, ethylene pattern paralleled callus growth curve. Variations in ethylene evolution were induced in shoot tip callus by means of ACC, AVG and varied amounts of 2,4-D in the culture medium. Following all these treatments callus growth was not altered. Hie decrease in 2,4-D concentration caused changes in Chl a and water content of the tissues.     

Cadmium effects on the organization of microtubular cytoskeleton in interphase and mitotic cells of Allium sativum

We have investigated the effects of cadmium on the microtubular (MT) cytoskeleton in the root tip cells of Allium sativum L. using indirect immunofluorescence microscopy. Cd affected the mechanisms controlling the organization of MT cytoskeleton, as well as tubulin assembly/disassembly processes. Cd induced the formation of abnormal MT arrays, consisting of discontinuous wavy MTs or short MT fragments at the cell periphery. Cadmium caused irregular nuclear disorder in cells where the MT organization and function was disturbed. Furthermore, with increased Cd concentration and duration of treatment the MTs depolymerized more severely, the frequency of abnormal cell increased and the mitotic index decreased progressively. The above findings showed that MT cytoskeleton is one of target sites of Cd toxicity in root tip cells.