Morphological and anatomical characterization of ectomycorrhizas and ectendomycorrhizas on Pinus strobus seedlings in a southern Ontario nursery

1997 ◽  
Vol 75 (12) ◽  
pp. 2057-2072 ◽  
Author(s):  
Margot Ursic ◽  
R. Larry Peterson
Keyword(s):  
Key Words ◽  
Pinus Strobus ◽  
Anatomical Study ◽  
Culture Conditions ◽  
Thelephora Terrestris ◽  
Southern Ontario ◽  
Conifer Seedlings ◽  
The Given ◽  
Pot Culture

A morphological and anatomical study of the mycorrhizas on Pinus strobus L. was conducted on seedlings excavated from St.-Williams nursery in southern Ontario. Micro- and macro-scopic characters were used to classify the morphotypes into complexes and, when possible, genera and species. An E-strain fungus, fungi from the Mycelium radicis atrovirens (MRA) complex, and an unidentified ascomycetous "red-type" fungus formed ectendomycorrhizal (EECM) associations, while Tuber sp., Hebeloma sp., and Thelephora terrestris formed ectomycorrhizal (ECM) associations in the nursery. Cultures of Hebeloma sp., the E-strain fungus, Tuber sp., and two morphologically distinct MRA fungi (MRA1, later identified as Phialophora finlandia Wang & Wilcox, and MRA2, unidentified) were isolated from field-collected morphotypes and re-inoculated onto Pinus strobus seedlings grown in semisterile pot cultures for 4 months. In the resynthesis experiment, the E-strain fungus formed EECM with sparse intracellular colonization, and Tuber sp. formed ECM with characteristic cystidia and densely packed mantles, as they had in the field. However, unlike the MRA field specimens, Phialophora finlandia formed ECM in pot culture. Hebeloma sp., normally an ECM former with conifer seedlings, did not form mycorrhizal structures under the given culture conditions, and neither did the MRA2 isolate. Key words: ectomycorrhiza, ectendomycorrhiza, Pinus strobus, Tuber sp., Phialophora finlandia, E-strain.

scholarly journals Insights into the Functionality of the Putative Residues Involved in Enterocin AS-48 Maturation

2010 ◽  
Vol 76 (21) ◽  
pp. 7268-7276 ◽  
Author(s):  
Rubén Cebrián ◽  
Mercedes Maqueda ◽  
José Luis Neira ◽  
Eva Valdivia ◽  
Manuel Martínez-Bueno ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
High Efficiency ◽  
Specific Protein ◽  
Culture Conditions ◽  
Site Directed Mutagenesis ◽  
Circular Structure ◽  
Cleavage Enzyme ◽  
Site Recognition ◽  
Biosynthetic Machinery

ABSTRACT AS-48 is a 70-residue, α-helical, cationic bacteriocin produced by Enterococcus faecalis and is very singular in its circular structure and its broad antibacterial spectrum. The AS-48 preprotein consists of an N-terminal signal peptide (SP) (35 residues) followed by a proprotein moiety that undergoes posttranslational modifications to yield the mature and active circular protein. For the study of the specificity of the region of AS-48 that is responsible for maturation, three single mutants have been generated by site-directed mutagenesis in the as-48A structural gene. The substitutions were made just in the residues that are thought to constitute a recognition site for the SP cleavage enzyme (His-1, Met1) and in those involved in circularization (Met1, Trp70). Each derivative was expressed in the enterococcal JH2-2 strain containing the necessary native biosynthetic machinery for enterocin production. The importance of these derivatives in AS-48 processing has been evaluated on the basis of the production and structural characterization of the corresponding derivatives. Notably, only two of them (Trp70Ala and Met1Ala derivatives) could be purified in different forms and amounts and are characterized for their bactericidal activity and secondary structure. We could not detect any production of AS-48 in JH2-2(pAM401-81 His-1Ile ) by using the conventional chromatographic techniques, despite the high efficiency of the culture conditions applied to produce this enterocin. Our results underline the different important roles of the mutated residues in (i) the elimination of the SP, (ii) the production levels and antibacterial activity of the mature proteins, and (iii) protein circularization. Moreover, our findings suggest that His-1 is critically involved in cleavage site recognition, its substitution being responsible for the blockage of processing, thereby hampering the production of the specific protein in the cellular culture supernatant.

Kleinian characterization of asymptotic symmetries of real general relativity

1993 ◽  
Vol 441 (1913) ◽  
pp. 465-471 ◽  
Keyword(s):  
General Relativity ◽  
Automorphism Group ◽  
Group Action ◽  
Radon Transform ◽  
Symmetry Groups ◽  
Asymptotic Symmetry ◽  
The Real ◽  
The Given ◽  
Asymptotic Symmetries

According to Klein’s Erlanger programme, one may (indirectly) specify a geometry by giving a group action. Conversely, given a group action, one may ask for the corresponding geometry. Recently, I showed that the real asymptotic symmetry groups of general relativity (in any signature) have natural ‘projective’ classical actions on suitable ‘Radon transform’ spaces of affine 3-planes in flat 4-space. In this paper, I give concrete models for these groups and actions. Also, for the ‘atomic’ cases, I give geometric structures for the spaces of affine 3-planes for which the given actions are the automorphism group.

Effects of the Cooling Rate on the Acoustic Properties of Pb-10Sn Solder

2012 ◽  
Vol 729 ◽  
pp. 356-360
Author(s):  
Endre Harkai ◽  
Tamás Hurtony ◽  
Péter Gordon
Keyword(s):  
Sound Velocity ◽  
Cooling Rate ◽  
Acoustic Microscopy ◽  
Acoustic Properties ◽  
Scanning Acoustic Microscopy ◽  
Cooling Rates ◽  
Reliability Parameters ◽  
Microscopy Characterization ◽  
The Given

Microhardness and sound velocity were measured in case of differently prepared solder samples. The used Pb-10Sn solder samples were melted then cooled down applying different cooling rates. These procedures caused variant microstructure thus different microhardness and sound velocity values. The sound velocity was measured by means of scanning acoustic microscopy. Characterization of solder materials by acoustic microscopy gives the possibility to non-destructively estimate mechanical and reliability parameters of the given material.

Characterization of a novel Aspergillus niger beta-glucosidase tolerant to saccharification of lignocellulosic biomass products and fermentation inhibitors

2015 ◽  
Vol 69 (8) ◽  
Author(s):  
Alesandra Oriente ◽  
Robson Tramontina ◽  
Diandra de Andrades ◽  
Caroline Henn ◽  
Jose L. C. Silva ◽  
...  
Keyword(s):  
Aspergillus Niger ◽  
Lignocellulosic Biomass ◽  
Culture Conditions ◽  
Industrial Wastes ◽  
Fermentation Inhibitors ◽  
State Culture ◽  
Solid State Culture ◽  
Atlantic Rainforest Biome ◽  
Beta Glucosidase

AbstractProperties of beta-glucosidase produced by Aspergillus niger URM 6642 recently isolated from the Atlantic rainforest biome and its potential tolerance to saccharification of lignocellulosic biomass products and fermentation inhibitors was evaluated. The fungus was cultivated under solid state culture conditions at 37°C with different agro-industrial wastes. High levels of beta-glucosidase (3778.9 U g

Synthesis and characterization of the binuclear diamido titanium chalcogenides [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, Te)

2002 ◽  
Vol 80 (11) ◽  
pp. 1524-1529 ◽  
Author(s):  
Tianle Zhang ◽  
Warren E Piers ◽  
Masood Parvez
Keyword(s):  
Solid State ◽  
Key Words ◽  
Synthesis And Characterization ◽  
Catalyst Precursor ◽  
Tellurium Atom ◽  
Titanium Complex ◽  
X Ray ◽  
X Ray Crystallography ◽  
Atom Source

Reaction of McConville's chelating amido titanium complex [(Ar)NCH2CH2CH2N(Ar)]Ti(CH3)2 (Ar = 2,6-i-Pr2C6H3) with either elemental Se or the tellurium atom source Te=PBu3 resulted in the formation of bis-µ-chalcogenido dimers [(Ar)NCH2CH2CH2N(Ar)]2Ti(µ-E)2 (E = Se, 2; Te, 3) with concommitant loss of EMe2. The dimers 2 and 3 were characterized spectroscopically and via X-ray crystallography. The two compounds are isostructural in the solid state. The tellurido dimer 3 may also be synthesized by reduction of the diamido dichloride [(Ar)NCH2CH2CH2N(Ar)]2TiCl2 with Na–Hg amalgam followed by treatment with Te=PBu3. This dimer is unreactive toward further Te=PBu3 or stannanes such as HSnBu3. Unlike decamethyltitanocene derivatives, the diamido complex is not an effective catalyst precursor for the heterohydrodecoupling of Te=PBu3 and HSnBu3.Key words: diamido titanium complexes, selenides, tellurides.

scholarly journals Formations of Silicon Carbide and Epoxy Matrix Radiator: An Experimental Design, Dimension and Formulations

2019 ◽  
Vol 9 (1) ◽  
pp. 1793-1796
Keyword(s):  
Heat Transfer ◽  
Silicon Carbide ◽  
Experimental Design ◽  
Epoxy Resin ◽  
Epoxy Matrix ◽  
Research Work ◽  
Heat Transfer Analysis ◽  
The Given ◽  
Design Dimension

The greatest dealon the article have to approach the experimental design, dimensions and formulations in Silicon Carbide and Epoxy Matrix Radiator. The experiment prepared as per the fabrication chart behind that known about the characterization of material and proposal layout of fabrication work. Among the research work, concentrated the formation of silicon carbide epoxy matrix radiator in the given configuration and composition prepared as a high thermal conductive Epoxy resin is mixed at the ratio of 20wt% of epoxy resin 80% of Silicon Carbide. As silicon carbide has higher thermal conductivity and lowerthermal expansion than Aluminium and then the experimented result determined by the rate of heat transfer analysis such as the mode of heat transfer like Conduction, Convection and Radiation of the materials (Aluminium 6061 and Sic + Epoxy Resin). The following heat transfer characteristics formulated and calculated as per the given design, dimension and configuration of the materials.

scholarly journals On Cauchy’s Interlacing Theorem and the Stability of a Class of Linear Discrete Aggregation Models Under Eventual Linear Output Feedback Controls

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 712 ◽  
Author(s):  
Manuel De la Sen
Keyword(s):  
Dynamic System ◽  
Output Feedback ◽  
Iteration Step ◽  
Stability And Convergence ◽  
Feedback Controls ◽  
Time Aggregation ◽  
The Stability ◽  
The Given ◽  
Stability Results

This paper links the celebrated Cauchy’s interlacing theorem of eigenvalues for partitioned updated sequences of Hermitian matrices with stability and convergence problems and results of related sequences of matrices. The results are also applied to sequences of factorizations of semidefinite matrices with their complex conjugates ones to obtain sufficiency-type stability results for the factors in those factorizations. Some extensions are given for parallel characterizations of convergent sequences of matrices. In both cases, the updated information has a Hermitian structure, in particular, a symmetric structure occurs if the involved vector and matrices are complex. These results rely on the relation of stable matrices and convergent matrices (those ones being intuitively stable in a discrete context). An epidemic model involving a clustering structure is discussed in light of the given results. Finally, an application is given for a discrete-time aggregation dynamic system where an aggregated subsystem is incorporated into the whole system at each iteration step. The whole aggregation system and the sequence of aggregated subsystems are assumed to be controlled via linear-output feedback. The characterization of the aggregation dynamic system linked to the updating dynamics through the iteration procedure implies that such a system is, generally, time-varying.

scholarly journals Characterization of a Bipartite Medial Cuneiform: Micro-CT and Anatomical Study

2018 ◽  
Vol 36 (4) ◽  
pp. 1372-1377
Author(s):  
Miki Dalmau-Pastor ◽  
Jordi Vega ◽  
Alicia Baltasar-Sánchez ◽  
Lotfi Slimani ◽  
Jorge Belinha ◽  
...  
Keyword(s):  
Anatomical Study ◽  
Micro Ct ◽  
Medial Cuneiform

scholarly journals Optimization of Saccharomyces cerevisiae α-galactosidase production and application in the degradation of raffinose family oligosaccharides

2019 ◽  
Vol 18 (1) ◽  
Author(s):  
María-Efigenia Álvarez-Cao ◽  
María-Esperanza Cerdán ◽  
María-Isabel González-Siso ◽  
Manuel Becerra
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Food Industry ◽  
Culture Conditions ◽  
Raffinose Family Oligosaccharides ◽  
Recombinant Production ◽  
Gene Coding ◽  
Productive Process ◽  
Hydrolysis Of ◽  
Degree Of Purification

Abstract Background α-Galactosidases are enzymes that act on galactosides present in many vegetables, mainly legumes and cereals, have growing importance with respect to our diet. For this reason, the use of their catalytic activity is of great interest in numerous biotechnological applications, especially those in the food industry directed to the degradation of oligosaccharides derived from raffinose. The aim of this work has been to optimize the recombinant production and further characterization of α-galactosidase of Saccharomyces cerevisiae. Results The MEL1 gene coding for the α-galactosidase of S. cerevisiae (ScAGal) was cloned and expressed in the S. cerevisiae strain BJ3505. Different constructions were designed to obtain the degree of purification necessary for enzymatic characterization and to improve the productive process of the enzyme. ScAGal has greater specificity for the synthetic substrate p-nitrophenyl-α-d-galactopyranoside than for natural substrates, followed by the natural glycosides, melibiose, raffinose and stachyose; it only acts on locust bean gum after prior treatment with β-mannosidase. Furthermore, this enzyme strongly resists proteases, and shows remarkable activation in their presence. Hydrolysis of galactose bonds linked to terminal non-reducing mannose residues of synthetic galactomannan-oligosaccharides confirms that ScAGal belongs to the first group of α-galactosidases, according to substrate specificity. Optimization of culture conditions by the statistical model of Response Surface helped to improve the productivity by up to tenfold when the concentration of the carbon source and the aeration of the culture medium was increased, and up to 20 times to extend the cultivation time to 216 h. Conclusions ScAGal characteristics and improvement in productivity that have been achieved contribute in making ScAGal a good candidate for application in the elimination of raffinose family oligosaccharides found in many products of the food industry.

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