Metabolite Profiling Uncovers Plasmid-Induced Cobalt Limitation under Methylotrophic Growth Conditions

We have introduced into Hansenula polymorpha an extra copy of its alcohol oxidase gene. This gene which is under the control of the Saccharomyces cerevisiae phosphoglycerate kinase promoter is integrated in a chromosome different from the one containing the endogenous gene. Cells with the extra alcohol oxidase gene, grown on glucose or ethanol as the sole carbon source, express enzymatically active alcohol oxidase. However, other enzymes characteristic for methylotrophic growth conditions are absent or present at low levels. Most of the alcohol oxidase occurs in the octameric state and immuno- and cytochemical evidence shows that it is located in a single enlarged peroxisome per cell. Such peroxisomes show crystalloid inclusions which are lacking in the peroxisomes present in glucose grown control cells. Our results suggest that import into peroxisomes of H. polymorpha, assembly and activation of alcohol oxidase is not conditionally dependent on adaptation to methylotrophic growth conditions and that proliferation of peroxisomes is a well-programmed process that is not triggered solely by overproduction of a peroxisomal protein.

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Metabolic characterisation of Magnetospirillum gryphiswaldense MSR-1 using LC-MS-based metabolite profiling

RSC Advances ◽

10.1039/d0ra05326k ◽

2020 ◽

Vol 10 (54) ◽

pp. 32548-32560 ◽

Cited By ~ 1

Author(s):

Salah Abdelrazig ◽

Laudina Safo ◽

Graham A. Rance ◽

Michael W. Fay ◽

Eirini Theodosiou ◽

...

Keyword(s):

Metabolic Pathways ◽

Metabolite Profiling ◽

Growth Conditions ◽

Limited Growth ◽

Magnetospirillum Gryphiswaldense

Metabolic pathways in Magnetospirillum gryphiswaldense MSR-1 are significantly altered under microaerobic (O2-limited) growth conditions enabling magnetosome formation.

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Faculty Opinions recommendation of Combined transcript and metabolite profiling of Arabidopsis grown under widely variant growth conditions facilitates the identification of novel metabolite-mediated regulation of gene expression.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.3115956.2799054 ◽

2010 ◽

Author(s):

Sjef Smeekens ◽

Johannes Hanson

Keyword(s):

Gene Expression ◽

Metabolite Profiling ◽

Regulation Of Gene Expression ◽

Growth Conditions

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Influence of MBE Growth Conditions on Dislocation Densities of GaAs/Ge Epilayers Grown on Silicon Substrates

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118692 ◽

1985 ◽

Vol 43 ◽

pp. 364-365

Author(s):

K.M. Hones ◽

P. Sheldon ◽

B.G. Yacobi ◽

A. Mason

Keyword(s):

High Efficiency ◽

Lattice Mismatch ◽

Low Cost ◽

Growth Conditions ◽

Nonradiative Recombination ◽

Device Structure ◽

Si Substrates ◽

Transmission Electron ◽

Dislocation Densities ◽

Dislocation Type

There is increasing interest in growing epitaxial GaAs on Si substrates. Such a device structure would allow low-cost substrates to be used for high-efficiency cascade- junction solar cells. However, high-defect densities may result from the large lattice mismatch (∼4%) between the GaAs epilayer and the silicon substrate. These defects can act as nonradiative recombination centers that can degrade the optical and electrical properties of the epitaxially grown GaAs. For this reason, it is important to optimize epilayer growth conditions in order to minimize resulting dislocation densities. The purpose of this paper is to provide an indication of the quality of the epitaxially grown GaAs layers by using transmission electron microscopy (TEM) to examine dislocation type and density as a function of various growth conditions. In this study an intermediate Ge layer was used to avoid nucleation difficulties observed for GaAs growth directly on Si substrates. GaAs/Ge epilayers were grown by molecular beam epitaxy (MBE) on Si substrates in a manner similar to that described previously.

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Diffraction from arrays of antiphase boundaries in ordered III-V alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100126378 ◽

1987 ◽

Vol 45 ◽

pp. 312-313

Author(s):

T. S. Kuan

Keyword(s):

High Surface ◽

Growth Conditions ◽

Ternary Alloys ◽

Local Growth ◽

Antiphase Boundaries ◽

Surface Mobility ◽

Ordered Phases ◽

Diffraction Patterns ◽

Atomically Flat ◽

Degree Of Order

Recent electron diffraction studies have found ordered phases in AlxGa1-xAs, GaAsxSb1-x, and InxGa1-xAs alloy systems, and these ordered phases are likely to be found in many other III-V ternary alloys as well. The presence of ordered phases in these alloys was detected in the diffraction patterns through the appearance of superstructure reflections between the Bragg peaks (Fig. 1). The ordered phase observed in the AlxGa1-xAs and InxGa1-xAs systems is of the CuAu-I type, whereas in GaAsxSb1-x this phase and a chalcopyrite type ordered phase can be present simultaneously. The degree of order in these alloys is strongly dependent on the growth conditions, and during the growth of these alloys, high surface mobility of the depositing species is essential for the onset of ordering. Thus, the growth on atomically flat (110) surfaces usually produces much stronger ordering than the growth on (100) surfaces. The degree of order is also affected by the presence of antiphase boundaries (APBs) in the ordered phase. As shown in Fig. 2(a), a perfectly ordered In0.5Ga0.5As structure grown along the <110> direction consists of alternating InAs and GaAs monolayers, but due to local growth fluctuations, two types of APBs can occur: one involves two consecutive InAs monolayers and the other involves two consecutive GaAs monolayers.

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The value of Electron Microscope studies of imperfect natural diamonds

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174102 ◽

1990 ◽

Vol 48 (4) ◽

pp. 194-195

Author(s):

J C Walmsley ◽

A R Lang

Keyword(s):

Electron Microscope ◽

Classification Scheme ◽

Natural Diamond ◽

Sudden Change ◽

Growth Conditions ◽

Diamond Growth ◽

Major Constituent ◽

Natural Diamonds ◽

Type Ia ◽

Platelet Defects

Interest in the defects and impurities in natural diamond, which are found in even the most perfect stone, is driven by the fact that diamond growth occurs at a depth of over 120Km. They display characteristics associated with their origin and their journey through the mantle to the surface of the Earth. An optical classification scheme for diamond exists based largely on the presence and segregation of nitrogen. For example type Ia, which includes 98% of all natural diamonds, contain nitrogen aggregated into small non-paramagnetic clusters and usually contain sub-micrometre platelet defects on {100} planes. Numerous transmission electron microscope (TEM) studies of these platelets and associated features have been made e.g. . Some diamonds, however, contain imperfections and impurities that place them outside this main classification scheme. Two such types are described.First, coated-diamonds which possess gem quality cores enclosed by a rind that is rich in submicrometre sized mineral inclusions. The transition from core to coat is quite sharp indicating a sudden change in growth conditions, Figure 1. As part of a TEM study of the inclusions apatite has been identified as a major constituent of the impurity present in many inclusion cavities, Figure 2.

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Role of the exosporial membrane in attachment and germination of C. sporogenes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146035 ◽

1993 ◽

Vol 51 ◽

pp. 38-39

Author(s):

B.J. Panessa-Warren ◽

G.T. Tortora ◽

J.B. Warren

Keyword(s):

Enzymatic Degradation ◽

Light Transmission ◽

Extended Period ◽

Growth Conditions ◽

Clostridium Sporogenes ◽

Radiation Chemical ◽

Physical Trauma ◽

Extended Contact ◽

Cold Pressure

Some bacteria are capable of forming highly resistant spores when environmental conditions are not adequate for growth. Depending on the genus and species of the bacterium, these endospores are resistant in varying degrees to heat, cold, pressure, enzymatic degradation, ionizing radiation, chemical sterilants,physical trauma and organic solvents. The genus Clostridium, responsible for botulism poisoning, tetanus, gas gangrene and diarrhea in man, produces endospores which are highly resistant. Although some sporocides can kill Clostridial spores, the spores require extended contact with a sporocidal agent to achieve spore death. In most clinical situations, this extended period of treatment is not possible nor practical. This investigation examines Clostridium sporogenes endospores by light, transmission and scanning electron microscopy under various dormant and growth conditions, cataloging each stage in the germination and outgrowth process, and analyzing the role played by the exosporial membrane in the attachment and germination of the spore.

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TEM study of very thin InGaAsP layers grown by liquid-phase epitaxy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100176496 ◽

1990 ◽

Vol 48 (4) ◽

pp. 672-673

Author(s):

N.A. Bert ◽

A.O. Kosogov

Keyword(s):

Liquid Phase ◽

Liquid Phase Epitaxy ◽

Chemical Vapor ◽

Growth Conditions ◽

Dark Field ◽

Organic Chemical ◽

Simple Liquid ◽

Cross Sectional ◽

Conventional Procedure ◽

Double Heterostructures

The very thin (<100 Å) InGaAsP layers were grown not only by molecular beam epitaxy and metal-organic chemical vapor deposition but recently also by simple liquid phase epitaxy (LPE) technique. Characterization of their thickness, interfase abruptness and lattice defects is important and requires TEM methods to be used.The samples were InGaAsP/InGaP double heterostructures grown on (111)A GaAs substrate. The exact growth conditions are described in Ref.1. The salient points are that the quarternary layers were being grown at 750°C during a fast movement of substrate and a convection caused in the melt by that movement was eliminated. TEM cross-section specimens were prepared by means of conventional procedure. The studies were conducted in EM 420T and JEM 4000EX instruments.The (200) dark-field cross-sectional imaging is the most appropriate TEM technique to distinguish between individual layers in 111-v semiconductor heterostructures.

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