Measuring Temperature Time Course using Membrane Capacitance

The ability of the pathogenic fungus Candida albicans to switch from a yeast to a hyphal morphology in response to external signals is implicated in its pathogenicity. We used glass DNA microarrays to investigate the transcription profiles of 6333 predicted ORFs in cells undergoing this transition and their responses to changes in temperature and culture medium. We have identified several genes whose transcriptional profiles are similar to those of known virulence factors that are modulated by the switch to hyphal growth caused by addition of serum and a 37°C growth temperature. Time course analysis of this transition identified transcripts that are induced before germ tube initiation and shut off later in the developmental process. A strain deleted for the Efg1p and Cph1p transcription factors is defective in hyphae formation, and its response to serum and increased temperature is almost identical to the response of a wild-type strain grown at 37°C in the absence of serum. Thus Efg1p and Cph1p are needed for the activation of the transcriptional program that is induced by the presence of serum.

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Two step-production of acylglycerols containing a high proportion of docosapentaenoic acid from marine omega-3 oil and their oxidative stability

Journal of Food Bioactives ◽

10.31665/jfb.2018.4168 ◽

2018 ◽

Vol 4 ◽

Author(s):

Zhongshui Yu ◽

Jiankang Wang ◽

Fereidoon Shahidi

Keyword(s):

Fatty Acid ◽

Oxidative Stability ◽

Polyunsaturated Fatty Acid ◽

Time Course ◽

Docosapentaenoic Acid ◽

Fatty Acid Esters ◽

Omega 3 ◽

Seal Blubber Oil ◽

Temperature Time ◽

Acid Esters

The objective of this study was to concentrate polyunsaturated fatty acid (PUFA) from seal blubber oil in an innovative manner to produce a high content of docosapentaenoic acid (DPA) in the resultant product. It also aimed at investigating the use of lipases as catalysts for synthesizing acylglycerols from glycerol and polyunsaturated fatty acid concentrates. Additionally, study of the oxidative stability of acylglycerols synthesized by lipases was intended. A two-stage urea complexation process was used to concentrate PUFA from seal blubber oil, giving rise to a DPA content of up to 24.0% in the product. Enzymatic synthesis of acyglycerols directly from glycerol and fatty acid concentrate was studied. Three lipases were used as biocatalysts for esterification. Lipase SP435 from Candida antarctica showed the highest activity for esterification. Effects of reaction parameters, namely temperature, time course and mole ratio of glycerol to fatty acid were followed with all three lipases. The optimal reaction time was 24 hr at 30 °C at a mole ratio of glycerol to fatty acid of 14:1. The maximum degree of acylglycerol synthesis was > 90%. The effect of time course and mole ratio of glycerol to fatty acid on acylglycerols distribution was also determined. The oxidative stability of different samples under Schaal-oven conditions at 60 °C showed that the oxidative stability of acylglycerols was better than that of the corresponding fatty acid esters.

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The time course of cortical vesicle fusion in sea urchin eggs observed as membrane capacitance changes

Developmental Biology ◽

10.1016/0012-1606(78)90314-7 ◽

1978 ◽

Vol 67 (1) ◽

pp. 243-248 ◽

Cited By ~ 66

Author(s):

Laurinda A. Jaffe ◽

Susumu Hagiwara ◽

Raymond T. Kado

Keyword(s):

Sea Urchin ◽

Time Course ◽

Vesicle Fusion ◽

Membrane Capacitance ◽

Sea Urchin Eggs

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Degradation of aflatoxin B1 by atoxigenic Aspergillus flavus biocontrol agents

Plant Disease ◽

10.1094/pdis-01-21-0066-re ◽

2021 ◽

Author(s):

Lourena A Maxwell ◽

Kenneth Callicott ◽

Ranajit Bandyopadhyay ◽

Hillary Laureen Mehl ◽

Marc Joel Orbach ◽

...

Keyword(s):

Aflatoxin B1 ◽

Time Course ◽

Competitive Ability ◽

Defined Medium ◽

Aflatoxin Contamination ◽

Active Ingredients ◽

Time Course Experiment ◽

Food And Feed ◽

Temperature Time ◽

Selection Of

Aflatoxins are potent Aspergillus mycotoxins that contaminate food and feed, thereby impacting health and trade. Biopesticides with atoxigenic A. flavus as active ingredients are used to reduce aflatoxin contamination in crops. The mechanism of aflatoxin biocontrol is primarily attributed to competitive exclusion but sometimes aflatoxin is reduced by greater amounts than can be explained by displacement of aflatoxin-producing fungi on the crop. Objectives of this study were to 1) evaluate the ability of atoxigenic A. flavus genotypes to degrade aflatoxin B1 (AFB1) and 2) characterize impacts of temperature, time, and nutrient availability on AFB1 degradation by atoxigenic A. flavus. Aflatoxin-contaminated maize was inoculated with atoxigenic isolates in three separate experiments that included different atoxigenic genotypes, temperature, and time as variables. Atoxigenic genotypes varied in aflatoxin degradation, but all degraded AFB1 > 44% after seven days at 30°C. The optimum temperature for AFB1 degradation was 25-30°C which is similar to the optimum range for AFB1 production. In a time-course experiment, atoxigenics degraded 40% of AFB1 within three days, and 80% of aflatoxin was degraded by day 21. Atoxigenic isolates were able to degrade and utilize AFB1 as a sole carbon source in a chemically defined medium, but quantities of AFB1 degraded declined as glucose concentrations increased. Degradation may be an additional mechanism through which atoxigenic A. flavus biocontrol products reduce aflatoxin contamination pre- and/or post-harvest. Thus, selection of optimal atoxigenic active ingredients can include assessment of both competitive ability in agricultural fields and their ability to degrade aflatoxins.

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Ultrastructural Changes of the Symbiotic Chlorella-Like Alga Isolated from Hydra Viridis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100054212 ◽

1982 ◽

Vol 40 ◽

pp. 320-321

Author(s):

K.W. Lee ◽

R.H. Meints ◽

D. Kuczmarski ◽

J.L. Van Etten

Keyword(s):

Time Course ◽

Reciprocal Cross ◽

Ultrastructural Level ◽

Ultrastructural Changes ◽

Symbiotic Relationship ◽

Cell Recognition ◽

Green Hydra ◽

Different Strains ◽

Hydra Viridis

The physiological, biochemical, and ultrastructural aspects of the symbiotic relationship between the Chlorella-like algae and the hydra have been intensively investigated. Reciprocal cross-transfer of the Chlorellalike algae between different strains of green hydra provide a system for the study of cell recognition. However, our attempts to culture the algae free of the host hydra of the Florida strain, Hydra viridis, have been consistently unsuccessful. We were, therefore, prompted to examine the isolated algae at the ultrastructural level on a time course.

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Destruction of Actin Filaments by Osmium Tetroxide

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079772 ◽

1977 ◽

Vol 35 ◽

pp. 466-467

Author(s):

P. Maupin-Szamier ◽

T. D. Pollard

Keyword(s):

Actin Filaments ◽

Time Course ◽

Osmium Tetroxide ◽

Rabbit Muscle ◽

Muscle Actin ◽

Sodium Phosphate Buffer ◽

Transmission Electron ◽

The Difference ◽

Rates Of Decay ◽

Short Time

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.

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The time course of calcium deposition in shells of the barnacle (Balanus amphititre amphititre) during cyprid-juvenile metamorphosis

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100168621 ◽

1994 ◽

Vol 52 ◽

pp. 178-179

Author(s):

Nancy R. Wallace ◽

Craig C. Freudenrich ◽

Karl Wilbur ◽

Peter Ingram ◽

Ann LeFurgey

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Time Course ◽

Vertical Plane ◽

Mantle Cavity ◽

Qualitative Assessment ◽

Calcium Deposition ◽

Free Swimming ◽

Freeze Dried ◽

Scanning Electron

The morphology of balanomorph barnacles during metamorphosis from the cyprid larval stage to the juvenile has been examined by light microscopy and scanning electron microscopy (SEM). The free-swimming cyprid attaches to a substrate, rotates 90° in the vertical plane, molts, and assumes the adult shape. The resulting metamorph is clad in soft cuticle and has an adult-like appearance with a mantle cavity, thorax with cirri, and incipient shell plates. At some time during the development from cyprid to juvenile, the barnacle begins to mineralize its shell, but it is not known whether calcification occurs before, during, or after ecdysis. To examine this issue, electron probe x-ray microanalysis (EPXMA) was used to detect calcium in cyprids and juveniles at various times during metamorphosis.Laboratory-raised, free-swimming cyprid larvae were allowed to settle on plastic coverslips in culture dishes of seawater. The cyprids were observed with a dissecting microscope, cryopreserved in liquid nitrogen-cooled liquid propane at various times (0-24 h) during metamorphosis, freeze dried, rotary carbon-coated, and examined with scanning electron microscopy (SEM). EPXMA dot maps were obtained in parallel for qualitative assessment of calcium and other elements in the carapace, wall, and opercular plates.

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Arabidopsis 4-COUMAROYL-COA LIGASE 8 contributes to the biosynthesis of the benzenoid ring of coenzyme Q in peroxisomes

Biochemical Journal ◽

10.1042/bcj20190688 ◽

2019 ◽

Vol 476 (22) ◽

pp. 3521-3532

Author(s):

Eric Soubeyrand ◽

Megan Kelly ◽

Shea A. Keene ◽

Ann C. Bernert ◽

Scott Latimer ◽

...

Keyword(s):

Oxidative Metabolism ◽

Time Course ◽

Reverse Genetics ◽

De Novo ◽

Coenzyme Q ◽

Control Level ◽

Wild Type ◽

Fluorescent Reporters ◽

Coa Ligase ◽

Peroxisomal Targeting

Plants have evolved the ability to derive the benzenoid moiety of the respiratory cofactor and antioxidant, ubiquinone (coenzyme Q), either from the β-oxidative metabolism of p-coumarate or from the peroxidative cleavage of kaempferol. Here, isotopic feeding assays, gene co-expression analysis and reverse genetics identified Arabidopsis 4-COUMARATE-COA LIGASE 8 (4-CL8; At5g38120) as a contributor to the β-oxidation of p-coumarate for ubiquinone biosynthesis. The enzyme is part of the same clade (V) of acyl-activating enzymes than At4g19010, a p-coumarate CoA ligase known to play a central role in the conversion of p-coumarate into 4-hydroxybenzoate. A 4-cl8 T-DNA knockout displayed a 20% decrease in ubiquinone content compared with wild-type plants, while 4-CL8 overexpression boosted ubiquinone content up to 150% of the control level. Similarly, the isotopic enrichment of ubiquinone's ring was decreased by 28% in the 4-cl8 knockout as compared with wild-type controls when Phe-[Ring-13C6] was fed to the plants. This metabolic blockage could be bypassed via the exogenous supply of 4-hydroxybenzoate, the product of p-coumarate β-oxidation. Arabidopsis 4-CL8 displays a canonical peroxisomal targeting sequence type 1, and confocal microscopy experiments using fused fluorescent reporters demonstrated that this enzyme is imported into peroxisomes. Time course feeding assays using Phe-[Ring-13C6] in a series of Arabidopsis single and double knockouts blocked in the β-oxidative metabolism of p-coumarate (4-cl8; at4g19010; at4g19010 × 4-cl8), flavonol biosynthesis (flavanone-3-hydroxylase), or both (at4g19010 × flavanone-3-hydroxylase) indicated that continuous high light treatments (500 µE m−2 s−1; 24 h) markedly stimulated the de novo biosynthesis of ubiquinone independently of kaempferol catabolism.

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Short-term volume and turgor regulation in yeast

Essays in Biochemistry ◽

10.1042/bse0450147 ◽

2008 ◽

Vol 45 ◽

pp. 147-160 ◽

Cited By ~ 12

Author(s):

Jörg Schaber ◽

Edda Klipp

Keyword(s):

Dynamic Model ◽

Volume Change ◽

Volume Regulation ◽

Time Course ◽

Osmotic Shock ◽

Intracellular Concentration ◽

Short Term ◽

Hydrodynamic Property ◽

Turgor Regulation ◽

Thermodynamic Framework

Volume is a highly regulated property of cells, because it critically affects intracellular concentration. In the present chapter, we focus on the short-term volume regulation in yeast as a consequence of a shift in extracellular osmotic conditions. We review a basic thermodynamic framework to model volume and solute flows. In addition, we try to select a model for turgor, which is an important hydrodynamic property, especially in walled cells. Finally, we demonstrate the validity of the presented approach by fitting the dynamic model to a time course of volume change upon osmotic shock in yeast.

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Preliminary Evaluation of a Weibull Function for Fitting Slow-Component Eye Velocity over the Time Course of Caloric-Induced Nystagmus

Journal of Speech Language and Hearing Research ◽

10.1044/jshr.3203.681 ◽

1989 ◽

Vol 32 (3) ◽

pp. 681-687 ◽

Cited By ~ 1

Author(s):

C. Formby ◽

B. Albritton ◽

I. M. Rivera

Keyword(s):

Time Course ◽

Slow Component ◽

Weibull Function ◽

Preliminary Evaluation ◽

Mathematical Function ◽

Before And After ◽

Best Fitting ◽

Eye Velocity ◽

Fitting Parameters ◽

Weibull Equation

We describe preliminary attempts to fit a mathematical function to the slow-component eye velocity (SCV) over the time course of caloric-induced nystagmus. Initially, we consider a Weibull equation with three parameters. These parameters are estimated by a least-squares procedure to fit digitized SCV data. We present examples of SCV data and fitted curves to show how adjustments in the parameters of the model affect the fitted curve. The best fitting parameters are presented for curves fit to 120 warm caloric responses. The fitting parameters and the efficacy of the fitted curves are compared before and after the SCV data were smoothed to reduce response variability. We also consider a more flexible four-parameter Weibull equation that, for 98% of the smoothed caloric responses, yields fits that describe the data more precisely than a line through the mean. Finally, we consider advantages and problems in fitting the Weibull function to caloric data.

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