BACKGROUND AND AIMS: Gluconacetobacter diazotrophicus is a plant growth-promoting bacteria (PGPB) that colonizes several plant species. Here, we studied the internal colonization of Arabidopsis ...thaliana tissues by G. diazotrophicus and analyzed its effects on physiology, growth, and activation of plant immune system during such association. METHODS: A. thaliana seedlings were inoculated with G. diazotrophicus and grown in substrate for 50 days. Effects on plant growth were estimated by quantifying number of leaves, leaf area, and fresh and dry weight. Endophytic bacterial population was determined by colony-forming unit (CFU), and its location in plant tissues was assayed by epifluorescence microscopy of red fluorescent protein-labeled bacterium. Whole canopy gas exchange (photosynthesis and transpiration) was determined using a portable photosynthesis system. RESULTS: G. diazotrophicus efficiently promoted A. thaliana plant growth at 50 days after inoculation. Inoculated plants showed higher whole canopy photosynthesis, lower whole plant transpiration, and increased water-use efficiency. The bacterium colonized preferentially root xylem. The inoculation of plants defective in systemic acquired resistance (SAR)-associated defense revealed that plant immune system plays an important role during the early association stages. CONCLUSIONS: G. diazotrophicus endophytically colonizes A. thaliana roots, promotes plant growth, and increases whole canopy photosynthesis. Our results indicate that A. thaliana is useful for molecular studies of the mechanisms involved in the interaction between plants and PGPB, especially those involving G. diazotrophicus.
Bioactivities from marine algae of the genus Gracilaria de Almeida, Cynthia Layse F; Falcão, Heloina de S; Lima, Gedson R de M ...
International Journal of Molecular Sciences,
07/2011, Letnik:
12, Številka:
7
Journal Article, Book Review
Recenzirano
Odprti dostop
Seaweeds are an important source of bioactive metabolites for the pharmaceutical industry in drug development. Many of these compounds are used to treat diseases like cancer, acquired ...immune-deficiency syndrome (AIDS), inflammation, pain, arthritis, as well as viral, bacterial, and fungal infections. This paper offers a survey of the literature for Gracilaria algae extracts with biological activity, and identifies avenues for future research. Nineteen species of this genus that were tested for antibacterial, antiviral, antifungal, antihypertensive, cytotoxic, spermicidal, embriotoxic, and anti-inflammatory activities are cited from the 121 references consulted.
• Species distribution is strongly driven by local and global gradients in water availability but the underlying mechanisms are not clear. Vulnerability to xylem embolism (P50) is a key trait that ...indicates how species cope with drought and might explain plant distribution patterns across environmental gradients. Here we address its role on species sorting along a hydrotopographical gradient in a central Amazonian rainforest and examine its variance at the community scale.
• We measured P50 for 28 tree species, soil properties and estimated the hydrological niche of each species using an indicator of distance to the water table (HAND).
• We found a large hydraulic diversity, covering as much as 44% of the global angiosperm variation in P50. We show that P50: contributes to species segregation across a hydrotopographic gradient in the Amazon, and thus to species coexistence; is the result of repeated evolutionary adaptation within closely related taxa; is associated with species tolerance to P-poor soils, suggesting the evolution of a stress-tolerance syndrome to nutrients and drought; and is higher for trees in the valleys than uplands.
• The large observed hydraulic diversity and its association with topography has important implications for modelling and predicting forest and species resilience to climate change.
Precise control of cell death is essential for the survival of all organisms. Arabidopsis thaliana BRASSINOSTEROID INSENSITIVE 1-associated receptor kinase 1 (BAK1) and somatic embryogenesis receptor ...kinase 4 (SERK4) redundantly and negatively regulate cell death through elusive mechanisms. By deploying a genetic screen for suppressors of cell death triggered by virus-induced gene silencing of BAK1/SERK4 on Arabidopsis knockout collections, we identified STT3a, a protein involved in N-glycosylation modification, as an important regulator of bak1/serk4 cell death. Systematic investigation of glycosylation pathway and endoplasmic reticulum (ER) quality control (ERQC) components revealed distinct and overlapping mechanisms of cell death regulated by BAK1/SERK4 and their interacting protein BIR1. Genome-wide transcriptional analysis revealed the activation of members of cysteine-rich receptor-like kinase (CRK) genes in the bak1/serk4 mutant. Ectopic expression of CRK4 induced STT3a/N-glycosylation-dependent cell death in Arabidopsis and Nicotiana benthamiana. Therefore, N-glycosylation and specific ERQC components are essential to activate bak1/serk4 cell death, and CRK4 is likely to be among client proteins of protein glycosylation involved in BAK1/SERK4-regulated cell death.
The thickness and refractive index of 1,2-dipalmitoyl-
sn
-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-
sn
-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) ...deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5 ± 0.6 Å and 1.485 ± 0.007 for DPPE monolayers, and 23.9 ± 0.5 Å and 1.478 ± 0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection.
Figure
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The isotopic ratio of nitrogen measured in primitive Solar System bodies shows a broad range of values, the origin of which remains unknown. One key question is whether these isotopic reservoirs of ...nitrogen predate the comet formation stage or are posterior to it. Another central question is elucidating the processes that can produce the observed variations in the 14N/15N isotopic ratio. Disks that orbit pre-main-sequence (T Tauri) stars provide unique opportunities for observing the chemical content of analogs of the protosolar nebula and therefore for building a comprehensive scenario that can explain the origin of nitrogen in the Solar System and in planet-forming disks. With ALMA, it has become possible to measure isotopic ratios of nitrogen-bearing species in such environments. We present spectrally and spatially resolved observations of the hyperfine structure of the 4−3 rotational transition of HCN and its main isotopologs H13CN and HC15N in the disk orbiting the 8 Myr old T Tauri star TW Hya. The sensitivity allows directly measuring the HCN/H13CN and HCN/HC15N abundance ratios with minimal assumptions. Averaged spatially over the disks, the ratios are 86 ± 4 and 223 ± 21, respectively. The latter value is significantly lower than the CN/C15N ratio of 323 ± 30 in this disk and thus provides the first evidence that two isotopic reservoirs of nitrogen are present in a disk at the stage of giant planet and comet formation. Furthermore, we find clear evidence for an increase in the ratio of HCN to HC15N with radius. The ratio in the outer disk, at 45 au, is 339 ± 28, in excellent agreement with direct measurements in the local interstellar medium, and with the bulk nitrogen isotopic ratio predicted from galactic evolution calculations. In the comet formation region at r = 20 au, the ratio is a factor ≈3 lower, 121 ± 11. This radial increase qualitatively agrees with the scenario in which selective photodissociation of N2 is the dominant fractionation process. However, our isotopic ratios and kinetic temperature of the HCN-emitting layers quantitatively disagree with models of nitrogen chemistry in disks.
In this study, we evaluated the physical, nutritional, and bioactive properties of mandacaru cladode flour (
DC.). The granulometric profile revealed particles with non-uniform geometry, flakiness, a ...rectangular tendency, and a non-homogeneous surface, with particle sizes ranging from 20 to 60 µm. The flour presented low water activity (0.423), a moisture content of 8.24 g/100 g, high ash (2.82 g/100 g), protein (5.18 g/100 g), and total carbohydrate contents (74.48 g/100 g), and low lipid contents (1.88 g/100 g). Mandacaru flour is an excellent source of insoluble dietary fiber (48.08 g/100 g), calcium (76.33%), magnesium (15.21%), and potassium (5.94%). Notably,
H NMR analysis revealed the presence of N-methyltyramine. Using HPLC chromatography, glucose was identified as the predominant sugar (1.33 g/100 g), followed by four organic acids, especially malic acid (9.41 g/100 g) and citric acid (3.96 g/100 g). Eighteen phenolic compounds were detected, with relevant amounts of kaempferol (99.40 mg/100 g), myricetin (72.30 mg/100 g), and resveratrol (17.84 mg/100 g). The total phenolic compounds and flavonoids were 1285.47 mg GAE/100 g and 15.19 mg CE/100 g, respectively. The mean in vitro antioxidant activity values were higher using the FRAP method (249.45 µmol Trolox TEAC/100 g) compared to the ABTS
method (0.39 µmol Trolox TEAC/g). Finally, the ascorbic acid had a content of 35.22 mg/100 g. The results demonstrate the value of mandacaru as a little-explored species and an excellent matrix for the development of flours presenting good nutritional value and bioactive constituents with excellent antioxidant potential.
Thoracostomopsidae is a family of free-living marine nematodes that has three subfamilies (Thoracostomopsinae, Trileptiinae and Enoplolaiminae). Most species descriptions within this family are very ...old and lack indication of important morphological details, so this article aims to fill this gap in the literature. This taxonomic review provides a list of all valid species, as well as species inquirenda, nomina nuda and synonyms, for each genus. Our review recognizes 16 valid genera, 193 valid species, 47 species inquirendae and three species as nomen nudum. Additionally, taxonomic dichotomous keys were constructed, modified or updated for each genus, as well to the subfamilies, using the most important diagnostic characters.
Abstract Learning to anticipate events based on the predictive relationship between an action and an outcome (operant conditioning) is a form of associative learning shared by humans and most of ...other living beings, including invertebrates. Several behavioral studies on the mechanisms of operant conditioning have included Melipona quadrifasciata, a honey bee that is easily manipulated due to lack of sting. In this work, brain proteomes of Melipona bees trained using operant conditioning and untrained (control) bees were compared by two-dimensional gel electrophoresis analysis within pI range of 3-10 and 4–7; in order to find proteins specifically related to this type of associative learning.One protein was detected with differential protein abundance in the brains of trained bees, when compared to not trained ones, through computational gel imaging and statistical analysis. This protein was identified by peptide mass fingerprinting and MS/MS peptide fragmentation using a MALDI-TOF/TOF mass spectrometer as one isoform of arginine kinase monomer, apparently dephosphorylated. Brain protein maps were obtained by 2-DE (Two-dimensional gel electrophoresis) from a total proteins and phosphoproteins extract of the bee Melipona quadrifasciata. One isoform of arginine kinase, probably a dephosphorylated isoform, was significantly more abundant in the brain of trained bees using operant conditioning. Arginine kinase has been reported as an important enzyme of the energy releasing process in the visual system of the bee, but it may carry out additional and unexpected functions in the bee brain for learning process.
Abstract
Despite their very close structural similarity, CxxC/S-type (class I) glutaredoxins (Grxs) act as oxidoreductases, while CGFS-type (class II) Grxs act as FeS cluster transferases. Here we ...show that the key determinant of Grx function is a distinct loop structure adjacent to the active site. Engineering of a CxxC/S-type Grx with a CGFS-type loop switched its function from oxidoreductase to FeS transferase. Engineering of a CGFS-type Grx with a CxxC/S-type loop abolished FeS transferase activity and activated the oxidative half reaction of the oxidoreductase. The reductive half-reaction, requiring the interaction with a second GSH molecule, was enabled by switching additional residues in the active site. We explain how subtle structural differences, mostly depending on the structure of one particular loop, act in concert to determine Grx function.
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