MICROSCOPIC FEATURES OF CEMENT PASTE MODIFIED BY FINE PERLITE

The use of waste material and replacement of binder element in cementitious composites is in focus of material development. Perlite in the construction industry is usually used in form of lightweight aggregate enhancing the insulating performance of concrete. This paper focuses on integration of fine perlite into the cement matrix and possible replacement of the cement binder in the composition of the material. The macromechanical performance of the modified paste is tested on specimens with 5, 10, 15 and 20% fine perlite substitution and pure cement sample. To distinguish the effect of the perlite on the microstructural level, pure cement material and specimen containing 10% of fine perlite are investigated by the electron microscopy. Furthermore, the mechanical properties of individual phases are examined and compared on same samples by instrumented indentation. The presented results enabled estimation of fine perlite impact on the macro and microscopic performance of the material

Identification of salicylic acid-independent responses in an Arabidopsis 3 phosphatidylinositol 4-kinase beta double mutant

International audienceBackground and AimsWe have recently shown that an Arabidopsis thaliana double mutant of type III phosphatidylinositol-4-kinases (PI4Ks), pi4kβ1β2, constitutively accumulated a high level of salicylic acid (SA). By crossing this pi4kβ1β2 double mutant with mutants impaired in SA synthesis (such as sid2 impaired in isochorismate synthase) or transduction, we demonstrated that the high SA level was responsible for the dwarfism phenotype of the double mutant. Here we aimed at distinguishing between the SA-dependent and -independent effects triggered by the deficiency in PI4Kβ1 and PI4Kβ2.MethodsTo achieve this, the sid2pi4kβ1β2 triple mutant was a tool of choice. High-throughput analyses of phytohormones were performed on this mutant together with pi4kβ1β2 and sid2 mutants and wild-type plants. Responses to pathogens, namely Hyaloperonospora arabidopsidis, Pseudomonas syringae and Botrytis cinerea, but as well to the non-host fungus Blumeria graminis, were also determined. Callose accumulation was monitored in response to flagellin. Key ResultsWe show here the prominent role of high SA levels in influencing the concentration of many other tested phytohormones, including abscisic acid and its derivatives, the Aspartate-conjugated form of indole-3-acetic acid and some cytokinins such as cis-zeatin. We show that the increased resistance of pi4kβ1β2 plants to the host pathogens Hyaloperonospora arabidopsidis, Pseudomonas syringae pv. tomato DC3000 and Bothrytis cinerea is dependent on accumulation of high SA level. In contrast, accumulation of callose in pi4kβ1β2 after flagellin treatment was independent of SA. Concerning the response to Blumeria graminis, both callose accumulation and fungal penetration were enhanced in the pi4kβ1β2 double mutant compared to wild-type plants. Both of these processes occurred in a SA-independent manner. ConclusionsOur data extensively illustrate the influence of SA on other phytohormone levels. The sid2pi4kβ1β2 triple mutant allowed to uncover the role of PI4Kβ1/β2 per se, thus showing the importance of these enzymes in plant defence responses

Inducers and elicitors of systemic acquired resistance of rapeseed to Leptosphaeria maculans

Systemic acquired resistance (SAR) is one of the sophisticated mechanisms used by plants to defend themselves against pathogen attacks and herbivorous insects. It is based on the activation of defense mechanisms in uninfected parts of the plant. As a result the entire plant is more resistant to a secondary infection. That is very advantageous for the plant because it is too costly to have defense responses switched on all the time. Although this phenomenon was described almost fifty years ago, it received no serious attention until past decade. To use SAR widespread in integrated pest management it is necessary to describe it on molecular level and show its differences in various host-pathogen interactions

Usage of modal synthesis method with condensation in rotor dynamics

The paper deals with mathematical modelling of vibration and modal analysis of rotors composed of a flexible shaft and several flexible disks. The shaft is modelled as a one dimensional continuum whereon flexible disks modelled as a three dimensional continuum are rigid mounted to shaft. The presented approach allows to introduce continuously distributed centrifugal and gyroscopic effects. The finite element method was used for shaft and disks discretization. The modelling of such flexible multi-body rotors with large DOF number is based on the system decomposition into subsystems and on the modal synthesis method with condensation. Lower vibration mode shapes of the mutually uncoupled and non-rotating subsystems are used for creation of the rotor condensed mathematical model. An influence of the different level of a rotor condensationmodel on the accuracy of calculated eigenfrequencies and eigenvectors is discussed

Characterization of low-molecular weight collagen hydrolysates prepared by combination of enzymatic and acid hydrolysis

Byla provedena hydrolýza komerčně dostupného hydrolyzátu postružin Hykol-E. Cílem práce bylo připravit nízkomolekulární produkt (Mw < 5000 g.mol-1), který by mohl být použit jako rostlinný biostimulátor. Průběh hydrolýzy byl sledován prostřednictvím změn molární hmotnosti (MW) a distribuce molárních hmotností (MWD) stanovených metodou gelové permeační chromatografie. Studie prokázala, že MW a MWD hydrolyzátu jsou ovlivněny volbou typu kyseliny použité k hydrolýze, její koncentrací a dobou působení. Kombinací enzymatické a kyselé hydrolýzy je možné připravit hydrolyzát s předem definovanými vlastnostmi, vyhovujícími určenému účelu použití.Formic, phosphoric and nitric acids were used for hydrolysis of the commercially available hydrolysis product of chrome shavings Hykol-E. The aim of the work was to prepare low-molecular weight product (Mw < 5000 g.mol-1) to be used as the plant biostimulator. Course of hydrolysis was monitored by following the changes of molecular weight (MW) and molecular weight distribution (MWD) determined by gel permeation chromatography (GPC). The study demonstrated that MW and MWD of hydrolysates are influenced by the choice of hydrolysing acid, its concentration as well as by the time of acid treatment. Using the combination of enzymatic and acid hydrolysis, it is possible to prepare products with the tailor-made, pre-defined molecular weight fitting the intended use.Research project of the Ministry of Agriculture [MZe: QH 72117]; Ministry of Education, Youth and Sports of the Czech Republic [MSM 7088352101

Biostimulators formed by hydrolyzed collagenous waste

Technické řešení se týká biostimulátorů, vyznačující se tím, že jsou tvořeny kolagenními odpady a keratinem, zhydrolyzováním kolagenních odpadů a keratinu, odpady koželužského, obuvnického, masného a potravinářského průmyslu a že jsou ztekuceny alkalickou nebo kyselou hydrolýzou za případného použití enzymů

Plant biostimulator

Biostimulátor rostlin na bázi bílkovinných odpadů, jehož podstata spočívá v tom, že je tvořen hydrolyzovanou kolagenní a/nebo keratinovou surovinou nebo směsí těchto surovin, která je vybraná ze skupiny zahrnující odpady kožedělného, koželužského, masného, potravinářského, obuvnického nebo zemědělského průmyslu.Biostimulator based on proteinaceous waste. The ground of the invention lies in the fact that the biostimulator is made of hydrolyzed collagenous or/and keratin feedstock or a mixture of these feedstocks which belongs to a group comprising wastes generated by tanning, leather, meat, food-processing and shoe-manufacturing industries and agriculture

Leptosphaeria maculans effector AvrLm4-7 affects SA- and ET-signalling and H2O2 accumulation in Brassica napus

To achieve host colonization, successful pathogens need to overcome plant basal defences. For this, (hemi) biotrophic pathogens secrete effectors that interfere with a range of physiological processes of the host plant. AvrLm4-7 is one of the cloned effectors from the hemibiotrophic fungus Leptosphaeria maculans ‘brassicaceae’ infecting mainly oilseed rape (Brassica napus). Although its mode of action is still unknown, AvrLm4-7 is strongly involved in L. maculans virulence. Here, we investigated the effect of AvrLm4-7 on plant defence responses in a susceptible cultivar of B. napus. Using two isogenic L. maculans isolates differing in the presence of a functional AvrLm4-7 allele [absence (‘a4a7’) and presence (‘A4A7’) of the allele], the plant hormone concentrations, defence-related gene transcription and reactive oxygen species (ROS) accumulation were analysed in infected B. napus cotyledons. Various components of the plant immune system were affected. Infection with the ‘A4A7’ isolate caused suppression of salicylic acid- and ethylene-dependent signalling, the pathways regulating an effective defence against L. maculans infection. Furthermore, ROS accumulation was decreased in cotyledons infected with the ‘A4A7’ isolate. Treatment with an antioxidant agent, ascorbic acid, increased the aggressiveness of the ‘a4a7’ L. maculans isolate, but not that of the ‘A4A7’ isolate. Together, our results suggest that the increased aggressiveness of the ‘A4A7’ L. maculans isolate could be caused by defects in ROSdependent defence and/or linked to suppressed SA and ET signalling. This is the first study to provide insights into the manipulation of B. napus defence responses by an effector of L. maculans

Cytokinin Metabolism of Pathogenic Fungus Leptosphaeria maculans Involves Isopentenyltransferase, Adenosine Kinase and Cytokinin Oxidase/Dehydrogenase

Among phytohormones, cytokinins (CKs) play an important role in controlling crucial aspects of plant development. Not only plants but also diverse microorganisms are able to produce phytohormones, including CKs, though knowledge concerning their biosynthesis and metabolism is still limited. In this work we demonstrate that the fungus Leptosphaeria maculans, a hemi-biotrophic pathogen of oilseed rape (Brassica napus), causing one of the most damaging diseases of this crop, is able to modify the CK profile in infected B. napus tissues, as well as produce a wide range of CKs in vitro, with the cis-zeatin derivatives predominating. The endogenous CK spectrum of L. maculans in vitro consists mainly of free CK bases, as opposed to plants, where other CK forms are mostly more abundant. Using functional genomics, enzymatic and feeding assays with CK bases supplied to culture media, we show that L. maculans contains a functional: (i) isopentenyltransferase (IPT) involved in cZ production; (ii) adenosine kinase (AK) involved in phosphorylation of CK ribosides to nucleotides; and (iii) CK-degradation enzyme cytokinin oxidase/dehydrogenase (CKX). Our data further indicate the presence of cis–trans isomerase, zeatin O-glucosyltransferase(s) and N6-(Δ2-isopentenyl)adenine hydroxylating enzyme. Besides, we report on a crucial role of LmAK for L. maculans fitness and virulence. Altogether, in this study we characterize in detail the CK metabolism of the filamentous fungi L. maculans and report its two novel components, the CKX and CK-related AK activities, according to our knowledge for the first time in the fungal kingdom. Based on these findings, we propose a model illustrating CK metabolism pathways in L. maculans