Abundant Small Protein ICARUS Inside the Cell Wall of Stress-Resistant Ascospores of Talaromyces macrosporus Suggests a Novel Mechanism of Constitutive Dormancy

Ascospores of Talaromyces.macrosporus belong to the most stress resistant eukaryotic cells and show a constitutive dormancy, i.e., no germination occurs in the presence of rich growth medium. Only an extreme trigger as very high temperature or pressure is able to evoke synchronized germination. In this study, several changes within the thick cell wall of these cells are observed after a heat treatment: (i.) a change in its structure as shown with EPR and X-ray diffraction; (ii.) a release of an abundant protein into the supernatant, which is proportional to the extent of heat activation; (iii.) a change in the permeability of the cell wall as judged by fluorescence studies in which staining of the interior of the cell wall correlates with germination of individual ascospores. The gene encoding the protein, dubbed ICARUS, was studied in detail and was expressed under growth conditions that showed intense ascomata (fruit body) and ascospore formation. It encodes a small 7–14 kD protein. Blast search exhibits that different Talaromyces species show a similar sequence, indicating that the protein also occurs in other species of the genus. Deletion strains show delayed ascomata formation, release of pigments into the growth medium, higher permeability of the cell wall and a markedly shorter heat activation needed for activation. Further, wild type ascospores are more heat-resistant. All these observations suggest that the protein plays a role in dormancy and is related to the structure and permeability of the ascospore cell wall. However, more research on this topic is needed to study constitutive dormancy in other fungal species that form stress-resistant ascospores.

Download Full-text

Impact of Field and Laboratory Environmental Conditions on the Diversity of Wood-Decay Fungi in the Forests of Northwest Arkansas

Journal of Pure and Applied Microbiology ◽

10.22207/jpam.14.3.18 ◽

2020 ◽

Vol 14 (3) ◽

pp. 1801-1808

Author(s):

Nawaf I. Alshammari ◽

Vajid N. Veettil ◽

Abdel Moneim E. Sulieman ◽

S.L. Stephenson

Keyword(s):

Woody Debris ◽

Fruit Body ◽

Fungal Growth ◽

Wood Decay ◽

Its Region ◽

Growth Conditions ◽

Fungal Species ◽

Decay Fungi ◽

Northwest Arkansas ◽

Taxonomic Groups

Environmental factors such as temperature and humidity directly affect the growth and fruit bodies of fungi. We studied the diversity of wood decaying fungal species, which have grown on same substrate in forest as well as laboratory environment. Ten specimens of fruit body of wood-decaying fungi and 24 random pieces of coarse wooden debris were collected from the forest of northwest Arkansas. The samples of coarse woody debris were incubated in laboratory-growth chambers for two months to promote the fungal growth. Fourty-two different species of wood-decay fungal isolates were recovered and identified by internal transcribed spacer (ITS) region sequencing. The isolates from the forest belonged to twenty-two different taxa whereas twenty taxonomic groups were reported from the growth compartments. Remarkably, data observed from two sets did not shared any taxon. These results indicated that environmental growth conditions play crucial role on fungal diversity even if grown on same substrates.

Download Full-text

Defect morphology in thick relaxed layers of InGaAs on GaAs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176472 ◽

1990 ◽

Vol 48 (4) ◽

pp. 668-669

Author(s):

R H Dixon ◽

P Kidd ◽

P J Goodhew

Keyword(s):

Electron Microscopy ◽

Surface Morphology ◽

Growth Conditions ◽

X Ray Diffraction ◽

Double Crystal ◽

Strained Layers ◽

Good Surface ◽

Transmission Electron ◽

Device Structures ◽

Surface Morphologies

Thick relaxed InGaAs layers grown epitaxially on GaAs are potentially useful substrates for growing high indium percentage strained layers. It is important that these relaxed layers are defect free and have a good surface morphology for the subsequent growth of device structures.3μm relaxed layers of InxGa1-xAs were grown on semi - insulating GaAs substrates by Molecular Beam Epitaxy (MBE), where the indium composition ranged from x=0.1 to 1.0. The interface, bulk and surface of the layers have been examined in planar view and cross-section by Transmission Electron Microscopy (TEM). The surface morphologies have been characterised by Scanning Electron Microscopy (SEM), and the bulk lattice perfection of the layers assessed using Double Crystal X-ray Diffraction (DCXRD).The surface morphology has been found to correlate with the growth conditions, with the type of defects grown-in to the layer (e.g. stacking faults, microtwins), and with the nature and density of dislocations in the interface.

Download Full-text

Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v2 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

The sodium-ion conducting family of Na3PnS4, with Pn = P, Sb, have gained interest for the use in solid-state batteries due to their high ionic conductivity. However, significant improvements to the conductivity have been hampered by the lack of aliovalent dopants that can introduce vacancies into the structure. Inspired by the need for vacancy introduction into Na3PnS4, the solid solutions with WS42- introduction are explored. The influence of the substitution with WS42- for PS43- and SbS43-, respectively, is monitored using a combination of X-ray diffraction, Raman and impedance spectroscopy. With increasing vacancy concentration improvements resulting in a very high ionic conductivity of 13 ± 3 mS·cm-1 for Na2.9P0.9W0.1S4 and 41 ± 8 mS·cm-1 for Na2.9Sb0.9W0.1S4 can be observed. This work acts as a stepping-stone towards further engineering of ionic conductors using vacancy-injection via aliovalent substituents.

Download Full-text

Defect-Mediated Conductivity Enhancements in Na3-xPn1-xWxS4 (Pn = P, Sb) using Aliovalent Substitutions

10.26434/chemrxiv.9943961.v1 ◽

2019 ◽

Author(s):

Till Fuchs ◽

Sean Culver ◽

Paul Till ◽

Wolfgang Zeier

Keyword(s):

Ionic Conductivity ◽

Vacancy Concentration ◽

Sodium Ion ◽

High Ionic Conductivity ◽

Ionic Conductors ◽

X Ray Diffraction ◽

X Ray ◽

Solid State Batteries ◽

Ion Conducting ◽

Very High

Download Full-text

A Metzincin and TIMP-Like Protein Pair of a Phage Origin Sensitize Listeria monocytogenes to Phage Lysins and Other Cell Wall Targeting Agents

Microorganisms ◽

10.3390/microorganisms9061323 ◽

2021 ◽

Vol 9 (6) ◽

pp. 1323

Author(s):

Etai Boichis ◽

Nadejda Sigal ◽

Ilya Borovok ◽

Anat A. Herskovits

Keyword(s):

Cell Wall ◽

Listeria Monocytogenes ◽

Mammalian Cells ◽

Protein Pair ◽

Growth Conditions ◽

Wall Structure ◽

Antibiotic Resistant ◽

Extracellular Milieu ◽

Virion Release ◽

Genes Encoding

Infection of mammalian cells by Listeria monocytogenes (Lm) was shown to be facilitated by its phage elements. In a search for additional phage remnants that play a role in Lm’s lifecycle, we identified a conserved locus containing two XRE regulators and a pair of genes encoding a secreted metzincin protease and a lipoprotein structurally similar to a TIMP-family metzincin inhibitor. We found that the XRE regulators act as a classic CI/Cro regulatory switch that regulates the expression of the metzincin and TIMP-like genes under intracellular growth conditions. We established that when these genes are expressed, their products alter Lm morphology and increase its sensitivity to phage mediated lysis, thereby enhancing virion release. Expression of these proteins also sensitized the bacteria to cell wall targeting compounds, implying that they modulate the cell wall structure. Our data indicate that these effects are mediated by the cleavage of the TIMP-like protein by the metzincin, and its subsequent release to the extracellular milieu. While the importance of this locus to Lm pathogenicity remains unclear, the observation that this phage-associated protein pair act upon the bacterial cell wall may hold promise in the field of antibiotic potentiation to combat antibiotic resistant bacterial pathogens.

Download Full-text

Influence of growth conditions onCandida albicansadhesion, hydrophobicity and cell wall ultrastructure

Medical Mycology ◽

10.1080/02681218880000121 ◽

1988 ◽

Vol 26 (2) ◽

pp. 79-92 ◽

Cited By ~ 45

Author(s):

M.J. Kennedy ◽

R.L. Sandin

Keyword(s):

Cell Wall ◽

Growth Conditions ◽

Cell Wall Ultrastructure ◽

Wall Ultrastructure

Download Full-text

Observations on the Growth of YBa2Cu3O7 Thin Films at Very High Laser Fluences

MRS Proceedings ◽

10.1557/proc-388-67 ◽

1995 ◽

Vol 388 ◽

Cited By ~ 2

Author(s):

Rand R. Biggers. ◽

M. Grant Norton ◽

I. Maartense ◽

T.L. Peterson ◽

E. K. Moser ◽

...

Keyword(s):

Thin Films ◽

Substrate Surface ◽

Chemical Vapor ◽

Growth Conditions ◽

Organic Chemical ◽

High Fluences ◽

Laser Fluences ◽

High Laser ◽

High Laser Fluences ◽

Very High

AbstractThe pulsed-laser deposition (PLD) technique utilizes one of the most energetic beams available to form thin films of the superconducting oxide YBa2Cu3O7 (YBCO). IN this study we examine the growth of YBCO at very high laser fluences (25 to 40 J/cm2); a more typical fluence for PLD would be nearer to 3 J/cm2. the use of high fluences leads to unique film microstructures which, in some cases, appear to be related to the correspondingly higher moveabilities of the adatoms. Films grown on vicinal substrates, using high laser fluences, exhibited well-defined elongated granular morphologies (with excellent transition temperature, Tc, and critical current density, Jc). Films grown on vicinal substrates using off-axis magnetron sputtering, plasma-enhanced metal organic chemical vapor deposition (PE-MOCVD), or PLD at more typical laser fluences showed some similar morphologies, but less well-defined. Under certain growth conditions, using high laser fluences with (001) oriented substrates, the YBCO films can exhibit a mixture of a- and c-axis growth where both crystallographic orientations nucleate on the substrate surface at the same time, and grow in concert. the ratio of a-axis oriented to c-axis oriented grains is strongly affected by the pulse repetition rate of the laser.

Download Full-text

Photocatalytic Performance of ZnO: Al Films under Different Light Sources

International Journal of Photoenergy ◽

10.1155/2012/780462 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 13

Author(s):

Prashant Pradhan ◽

Juan Carlos Alonso ◽

Monserrat Bizarro

Keyword(s):

White Light ◽

Irradiation Time ◽

Zno Films ◽

Light Sources ◽

X Ray Diffraction ◽

Treatment Processes ◽

Vis Spectroscopy ◽

Doped Zno ◽

Very High ◽

High Degradation Rate

ZnO and Al doped ZnO films were produced by spray pyrolysis. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy, and photoluminescence. Their photocatalytic activity was evaluated by the decomposition of the methyl orange dye using different light sources: ultraviolet light, artificial white light, and direct sunlight. The films were also tested under darkness for comparison. The ZnO films were able to degrade the test pollutant under UV and sunlight in more than a 60% after 180 min of irradiation and a scarce degradation was obtained using white light. However, the Al doped ZnO films presented a very high degradation rate not only under UV and sunlight (100% degradation), but also under white light (90% degradation after the same irradiation time). An unexpected high degradation was also obtained in the dark, which indicates that a nonphotonic process is taking place parallel to the photocatalytic process. This can be due to the extra electrons—provided by the aluminum atoms—that migrate to the surface and produce radicals favoring the decomposition process even in the dark. The high activity achieved by the ZnO: Al films under natural conditions can be potentially applied to water treatment processes.

Download Full-text

Cell-wall abnormalities of a Chlamydomonas reinhardtii mutant strain under suboptimal growth conditions

Planta ◽

10.1007/bf00197568 ◽

1991 ◽

Vol 183 (1) ◽

Author(s):

J�rgen Voigt ◽

Dieter Mergenhagen ◽

Irmhild Wachholz ◽

Elsbeth Manshard ◽

Marianne Mix

Keyword(s):

Cell Wall ◽

Chlamydomonas Reinhardtii ◽

Mutant Strain ◽

Growth Conditions

Download Full-text

Synchrotron white beam x-ray topography (SWBXT) and high resolution triple axis diffraction studies on AlN layers grown on 4H- and 6H-SiC seeds

MRS Proceedings ◽

10.1557/proc-831-e8.24 ◽

2004 ◽

Vol 831 ◽

Author(s):

Balaji Raghothamachar ◽

Michael Dudley ◽

Rafael Dalmau ◽

Raoul Schlesser ◽

Zlatko Sitar

Keyword(s):

High Resolution ◽

Single Crystal ◽

Large Diameter ◽

Laser Diodes ◽

Growth Conditions ◽

X Ray Diffraction ◽

X Ray ◽

White Beam ◽

Strain Data ◽

Growth Experiments

ABSTRACTFor nitride based devices such as LEDs, high power FETs and laser diodes, single crystal substrates of AlN are highly desirable. While the sublimation technique is suitable for growing bulk AlN crystals, appropriate seeds are also necessary for growing large diameter oriented boules. 4H- and 6H-SiC substrates which are readily available commercially can potentially be implemented as seeds for bulk AlN growth. However, issues regarding SiC decomposition at high temperatures, thermal expansion mismatch, single crystal growth, etc. need to be addressed. Towards this end, a series of growth experiments have been carried out in a resistively heated reactor using on and off-axis 4H- and 6H-SiC substrates as seeds for AlN growth from the vapor phase. Several hundred microns thick AlN layers have been grown under different growth conditions. Synchrotron white beam x-ray topography (SWBXT) has been used to map the defect distribution in the grown layers and high resolution triple axis x-ray diffraction (HRTXD) experiments were carried out to record reciprocal space maps from which tilt, mismatch and strain data can be obtained. These results are analyzed with respect to the growth conditions in order to gain a better understanding of this growth process.

Download Full-text