Photosynthesis and water relations of almond tree cultivars grafted on two rootstocks

Five cultivars of Prunus amygdalus Batsch (Ferragnes, Ferrastar, Marcona, Garrigues, and Non Pareil) grafted on two different rootstocks (Garrigues and GF677), and two cultivars (Ferraduel and Casa Nova) grafted on GF677, were grown for three years under rainfed conditions in an orchard in northeast Portugal. Net photosynthetic rate (PN), leaf conductance for water vapour (gs), leaf water potential (Ψ), instantaneous water use efficiency (WUE), and internal CO2 concentration (Ci) were measured at three periods of the growing season: spring, summer (June or July) and late summer (September) over two years. Ferraduel, Ferrastar, and Marcona presented the best performance in the periods when environmental conditions were not very hard (May or September). Casa Nova and Non Pareil were well adapted to high air evaporative demand, preventing the increase of leaf temperature (T1). Ferrastar, although having a good performance in May and September, did well adapt to hard climatic conditions in June 1994. In the following year, although it presented the highest T1, the values were not limiting (30.6 ± 2.1 °C), and PN was only decreased from May to July. Marcona was highly dependent on T1, but prevented its increasing. Garrigues showed lower PN in most measurement periods. GF677 frequently induced the highest PN, WUE, and Ψ. PN was mainly dependent on T1, radiation, Ci, month, and year. WUE depended on the same factors. Ψ depended mainly on gs, air temperature, month, and year. This revised version was published online in June 2006 with corrections to the Cover Date.     

Biotechnological potential of plant growth-promoting bacteria from the roots and rhizospheres of endemic plants in ironstone vegetation in southeastern Brazil

Microorganisms associated with plants have a great biotechnological potential, but investigations of these microorganisms associated with native plants in peculiar environments has been incipient. The objective of this study was to analyze the plant growth-promoting bacteria potential of cultivable bacteria associated with rare plants from the ferruginous rocky fields of the Brazilian Iron Quadrangle. The roots and rhizospheres of nine endemic plants species and samples of a root found in a lateritiric duricrust (canga) cave were collected, the culturable bacteria isolated and prospected for distinct biotechnological and ecological potentials. Out of the 148 isolates obtained, 8 (5.4%) showed potential to promote plant growth, whereas 4 (2.7%) isolates acted as biocontrol agents against Xanthomonas citri pathotype A (Xac306), reducing the cancrotic lesions by more than 60% when co-inoculated with this phytopathogen in Citrus sinensis plants. Moreover, other 4 (2.7%) isolates were classified as potential bioremediation agents, being able to withstand high concentrations of arsenite (5 mM As³⁺) and arsenate (800 mM As⁵⁺), by removing up to 35% and 15% of this metalloid in solution, respectively. These same four isolates had a positive influence on the growth of both the roots and the aerial parts when inoculated with tomato seeds in the soil contaminated with arsenic. This is the first time that an investigation highlights the potentialities of bacteria associated with rare plants of ferruginous rocky fields as a reservoir of microbiota of biotechnological and ecological interest, highlighting the importance of conservation of this area that is undergoing intense anthropic activity.

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Dissemination of the ST-103 clonal complex serogroup C meningococci in Salvador,Brazil

Invasive meningococcal disease (IMD) is a major public health problem worldwide. An epidemic of serogroup C (NmC) IMD occurred in 2010 in the city of Salvador. In this study, we describe the antigenic and genetic characterization of meningococcal isolates collected from meningitis cases in Salvador from 2001 to 2012. Pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) were performed for the analysis of IMD isolates. A total of 733 cases were identified, and the serogroup was determined for 391 (53.0%) of these. Most cases were caused by NmC (53%) or B (47%). The most prevalent strains were B:4,7:P1.19,15 (32.9%; 129/391) and C:23:P1.14–6 (28.6%; 112/391). Based on PFGE/MLST analysis, 71.3% (77/108 PFGE-tested isolates) clustered as two clones of sequence type ST-3779 and ST-3780, both belonging to the ST-103 clonal complex. ST-3779 has been detected in Salvador since 1996 and together with ST-3780 became predominant after 2005. There was a predominance of C:23:P1.14–6, ST-3779/3780 in Salvador during the period of 2007–2012, establishing a major clonal lineage, which remained in the community for a long time; this has serious implications for public health, particularly in terms of prevention and control strategies of IMD.     

The rice cold-responsive calcium-dependent protein kinase OsCPK17 is regulated by alternative splicing and post-translational modifications

Plant calcium-dependent protein kinases (CDPKs) are key proteins implicated in calcium-mediated signaling pathways of a wide range of biological events in the organism. The action of each particular CDPK is strictly regulated by many mechanisms in order to ensure an accurate signal translation and the activation of the adequate response processes. In this work, we investigated the regulation of a CDPK involved in rice cold stress response, OsCPK17, to better understand its mode of action. We identified two new alternative splicing (AS) mRNA forms of OsCPK17 encoding truncated versions of the protein, missing the CDPK activation domain. We analyzed the expression patterns of all AS variants in rice tissues and examined their subcellular localization in onion epidermal cells. The results indicate that the AS of OsCPK17 putatively originates truncated forms of the protein with distinct functions, and different subcellular and tissue distributions. Additionally, we addressed the regulation of OsCPK17 by post-translational modifications in several in vitro experiments. Our analysis indicated that OsCPK17 activity depends on its structural rearrangement induced by calcium binding, and that the protein can be autophosphorylated. The identified phosphorylation sites mostly populate the OsCPK17 N-terminal domain. Exceptions are phosphosites T107 and S136 in the kinase domain and S558 in the C-terminal domain. These phosphosites seem conserved in CDPKs and may reflect a common regulatory mechanism for this protein family.     

Biochemical response between insects and plants: an investigation of enzyme activity in the digestive system of Leucoptera coffeella (Lepidoptera: Lyonetiidae) and leaves of Coffea arabica (Rubiaceae) after herbivory

Plant defence mechanisms can reduce the digestive enzyme activity of insect pests. The aim of this study was to determine the relationship between the production of proteinase inhibitors, lipoxygenase and polyphenol oxidase activity in Coffea arabica (Catuai IAC 15) plants, and the digestive enzyme activity in the pest Leucoptera coffeella (Lepidoptera: Lyonetiidae) after feeding on the plant. The production of proteinase inhibitors was evaluated with L‐BApNA as a substrate. We studied lipoxygenase activity with linoleic acid and polyphenol oxidase activity with catechol substrates, in coffee plants damaged (T1) and not damaged (T2) by L. coffeella. L. coffeella digestive enzyme activity was verified by trypsin‐like (substrate l ‐BApNA and l ‐TAME), chymotrypsin‐like (BTpNA and ATEE), cysteine proteases (l ‐BApNA) and total protease (azocasein). Proteinase inhibitor production and lipoxygenase and polyphenol oxidase activity in C. arabica increases (P ≤ 0.05) with L. coffeella damage. Our results provide important information that these enzymatic activities may play a role in plant defence processes in C. arabica. Trypsin‐like activity increases, whereas chymotrypsin‐like and cysteine protease activity decrease in the midgut of L. coffeella, which acts as a defence mechanism.     

Microstachys crassifolia sp. nov. (Euphorbiaceae) from Chapada dos Veadeiros,Goiás,Brazil

Microstachys crassifolia, a new species from Chapada dos Veadeiros region in the State of Goias, central Brazil, is here described and illustrated. Its habit and general morphology resembles that of M. nana Silva & Esser, an endemic species from the State of Paraná, southern Brazil. Both species are hemicryptophytes from grasslands, with a well‐developed underground system, glabrous leaves and reddish inflorescences and fruits, but M. crassifolia has fleshy leaves without glands while M. nana has membranaceous leaves with pateliform, submarginal glands.     

The timing and nature of neovascularization of jejunal free flaps: an experimental study in a large animal model.

The present study was designed (1) to determine whether a free jejunal transfer in a large animal model can develop collateral circulation that is adequate to maintain viability after division of the pedicle and (2) to determine the earliest time pedicle ligation is safe after transplantation. A 15-cm jejunal segment was transferred to the necks of 18 dogs weighing 25 to 35 kg. The bowel segment was inset longitudinally under the skin on one side of the neck, partially covered by the neck muscles, and the mesenteric vessels were anastomosed to recipient vessels in the neck. The proximal and distal bowel stomas were exteriorized through skin openings 12 cm apart and matured. The dogs were subjected to ligation of the vascular pedicle at different intervals: postoperative day 7 (group I, n = 3), day 14 (group II, n = 5), day 21 (group III, n = 5), and day 28 (group IV, n = 5). Blood perfusion was measured in the proximal and distal bowel stomas before pedicle division (control) and 24 hours later using hydrogen gas clearance and fluorescein dye. Bowel necrosis was analyzed using planimetry. The bowel was also stained with hematoxylin and eosin and factor VIII, and new blood vessels were counted. Mean values (+/- standard deviation) were compared with control values for each test and with normal values in the intact bowel using analysis of variance with Neumann-Keuls post-hoc test for multiple comparisons. No jejunal free flaps survived when the vascular pedicle was divided 1 week postoperatively. Bowel survival was 60 percent at 2 weeks, 83 percent at 3 weeks, and 100 percent at 4 weeks. Hydrogen gas clearance values (ml/min/100 g) were 49.6 +/- 8.7 in the mucosa of the intraabdominal jejunum and 37.9 +/- 9.4 in the jejunum that was transferred to the neck before division of the pedicle. Twenty-four hours after pedicle division, hydrogen gas clearance values were 2.8 +/- 6.4 in group I (p < 0.05), 22.4 +/- 12.4 in group II, 23.9 +/- 9.3 in group III, and 34.2 +/- 7.5 in group IV. FluoroScan readings in the transferred jejunum were 201 +/- 7.2 in the control group, 9.3 +/- 2.8 in group I (p < 0.05), 79.1 +/- 10.6 in group II, 66.2 +/- 7.3 in group III, and 164 +/- 11.9 in group IV. New vessel formation as identified by factor VIII staining correlated with increasing bowel perfusion and flap survival rate. Bowel neovascularization, perfusion, and survival increased progressively 1 week after transfer. Significant portions of the transferred bowel will neovascularize and survive as early as 2 weeks postoperatively. However, a minimum of 4 weeks before ligation of the pedicle is necessary to maximize flap perfusion and guarantee survival.     

Glyoxalase II in Saccharomyces cerevisiae: in situ kinetics using the 5,5'-dithiobis(2-nitrobenzoic acid) assay.

The determination of glyoxalase II (S-(2-hydroxyacyl)glutathione hydrolase, EC 3.1.2.6) activity is usually accomplished by monitoring the decrease of absorbance at 240 nm due to the hydrolysis of S-d-lactoylglutathione. However, it was not possible, using this assay, to detect any enzyme activity in situ, in Saccharomyces cerevisiae permeabilized cells. Glyoxalase II activity was then determined by following the formation of GSH at 412 nm using 5,5'-dithiobis(2-nitrobenzoic acid). Using this method we characterized the kinetics of glyoxalase II in situ using S-d-lactoylglutathione as substrate and compared the results with those obtained for cell-free extracts. The specific activity was found to be (4.08 +/- 0.12) x 10(-2) micromol min-1 mg-1 in permeabilized cells and (3.90 +/- 0.04) x 10(-2) micromol min1 mg-1 in cell-free extracts. Kinetic parameters were Km 0.36 +/- 0.09 mM and V (7.65 +/- 0.59) x 10(-4) mM min-1 for permeabilized cells and Km 0.15 +/- 0.10 mM and V (7.23 +/- 1.04) x 10(-4) mM min-1 for cell-free extracts. d-Lactate concentration was also determined and increased in a linear way with permeabilized cell concentration. gamma-Glutamyl transferase (EC 2.3.2.2), which also accepts S-d-lactoylglutathione as substrate and hence could interfere with glyoxalase II assays, was found to be absent in Saccharomyces cerevisiae permeabilized cells.     

Study of Liquid Dimethyl Sulfoxide by Computer Simulation

The paper reports Monte Carlo and molecular dynamicsresults for pure liquid dimethyl sulfoxide (DMSO) at298 K and 1 atm. The classical 6–12 Lennard–Jones plusCoulomb pairwise potential was used to calculateintermolecular interaction energy. Potentialparameters for the liquid were optimized in this work.Some thermodynamic and dynamical properties obtained,such as heat of vaporization, density and diffusioncoefficient, are in good agreement with theexperimental values. The present model is comparedwith other models for DMSO reported previously. It isshown to be an improvement over earlier potentials.The structure factors and the radial distributionfunctions (rdf), are compared with experimentalresults for the liquid. The analysis shows that thestructure of DMSO is not completely understood yet anddeserves deeper investigation. The geometry of thedimer that corresponds to the rdf plots obtained, isreported. The results suggest that the dipole momentof this dimer plays an important role in the structureof the liquid.