Attention modulates the time-course of talker-specificity effects in lexical retrieval

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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