scholarly journals Time course of embryonic midbrain and thalamic auditory connection development in mice as revealed by carbocyanine dye tracing

2004 ◽  
Vol 479 (3) ◽  
pp. 309-327 ◽  
Author(s):  
Bina Gurung ◽  
Bernd Fritzsch
Keyword(s):  
Time Course ◽  
Dye Tracing ◽  
Carbocyanine Dye

Segmental and neuronal architecture of the hindbrain of Krox-20 mouse mutants

Development ◽  
1997 ◽  
Vol 124 (6) ◽  
pp. 1215-1226 ◽  
Author(s):  
S. Schneider-Maunoury ◽  
T. Seitanidou ◽  
P. Charnay ◽  
A. Lumsden
Keyword(s):  
Branchial Arch ◽  
Motor Nucleus ◽  
Exit Point ◽  
Dye Tracing ◽  
Trigeminal Motor Nucleus ◽  
Zinc Finger Transcription Factor ◽  
Mouse Mutants ◽  
Neuron Populations ◽  
Carbocyanine Dye ◽  
Internal Architecture

The vertebrate hindbrain is transiently segmented during its early development with the formation of reiterated bulges, the rhombomeres (r). The Krox-20 gene, which encodes a zinc finger transcription factor, has been shown previously to be implicated in the maintenance of r3 and r5 (Schneider-Maunoury, S., Topilko, P., Seitanidou, T., Levi, G., Cohen-Tannoudji, M., Pournin, S., Babinet, C. and Charnay, P. (1993) Cell 75, 1199–1214; Swiatek, P. J. and Gridley, T. (1993) Genes Dev. 7, 2071–2084. However, it was not clear from these analyses how extensive the deletion of r3 and r5 was and whether the overall segmentation and internal architecture of the hindbrain was affected. We have now reinvestigated these issues by analysis of rhombomere boundaries, using both morphological and molecular markers, and of the fate of specific motor neuron populations, using retrograde and anterograde carbocyanine dye tracing. We conclude that r3 and r5 and their derivatives are completely eliminated in Krox-20(−/−) embryos while overall hindbrain segmentation is maintained. In addition, we show that the disappearance of these territories has important consequences for even-numbered rhombomeres as well, in particular on axonal navigation: (i) a population of r6 motoneurons, presumably normally fated to join the glossopharyngeal nerve, has its axons misrouted toward the facial exit point in r4; (ii) the trigeminal motor axons are also misrouted, presumably because of the proximity of the trigeminal and facial exit points. They fasciculate with facial axons outside the neural tube and enter the second branchial arch instead of the first arch. This navigational error could explain the disappearance, at around 17.5 dpc, of the trigeminal motor nucleus in Krox-20(−/−) embryos by inadequate supply of essential, possibly arch-specific survival factors.

scholarly journals Pax6 is required for the normal development of the forebrain axonal connections

Development ◽  
2002 ◽  
Vol 129 (21) ◽  
pp. 5041-5052 ◽  
Author(s):  
Lucy Jones ◽  
Guillermina López-Bendito ◽  
Peter Gruss ◽  
Anastassia Stoykova ◽  
Zoltán Molnár
Keyword(s):  
Knockout Mouse ◽  
Normal Development ◽  
Internal Capsule ◽  
Axonal Guidance ◽  
Pax6 Expression ◽  
Dye Tracing ◽  
Axonal Connections ◽  
Carbocyanine Dye ◽  
Ventral Thalamus ◽  
Guidance Molecule

The transcription factor PAX6 has been implicated in forebrain patterning,cerebral cortical arealization and in development of thalamocortical connections. Using a Pax6/lacZ knockout mouse, in which the endogenous Pax6 expression is reflected by β-galactosidase activity, we have studied the consequences of the loss of Pax6function on thalamocortical (TCA) and corticofugal axon (CFA) pathfinding during the period of embryonic day (E) 14.5 to E18.5. Carbocyanine dye tracing in Pax6 heterozygotes (Pax6+/-) and Pax6wild-type (Pax6+/+) brains revealed that CFAs and TCAs temporarily arrested their growth at E14.5 at the border of theβ-galactosidase-positive region at the pallial/subpallial boundary(PSPB), before they continued towards their targets. However, in Pax6homozygous (Pax6-/-) embryos, CFAs and TCAs were unable to encounter each other at the PSPB and reach their final targets. Instead of crossing the PSPB, they had the tendency to descend into the ventral pallium in large aberrant fascicles. In addition, cells with a presumptive guide-post function, which are normally situated in the ventral thalamus, internal capsule and hypothalamus, were more dispersed in the hypothalamus and ventral pallium. These pathfinding defects were confirmed by immunohistochemistry for L1 and TAG1, markers of the early axonal connections. The aberrant development of axonal connections in absence of Pax6 function appear to be related to ultrastructural defects of cells along the PSPB, as well as to a failure of axonal guidance molecule expression, including Sema3c and Sema5a.

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

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.

Destruction of Actin Filaments by Osmium Tetroxide

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.

Preplate neurons in embryonic mouse cortex: Ultrastructural observations using photoconversion of the fluorescent lipophilic dye dil

1992 ◽  
Vol 50 (1) ◽  
pp. 906-907
Author(s):  
Linda C. Hassinger ◽  
James E. Crandall
Keyword(s):  
Mouse Embryos ◽  
Embryonic Mouse ◽  
Cortical Afferents ◽  
Mouse Cortex ◽  
Carbocyanine Dye ◽  
Increased Sensitivity

We have begun to look directly at small numbers of afferent axons to early generated neurons that form the preplate in the developing mouse cortex. The carbocyanine dye Dil (1’1, dioctadecyl-3,3,3’3’-tetramethyl-indocarbocyanine) has proved especially useful for this goal. DiI labels axons and their terminals with greater sensitivity and without some of the disadvantages of axon filling with HRP. The increased sensitivity provided by labeling embryonic axons with DiI has given us new insights into the development of cortical afferents. For instance, we reported originally that afferents from the thalamus were present below the cortex as early as embryonic day 15 (E15) based on HRP injections into mouse embryos. By using DiI placements into the thalamus in aldehyde-fixed brains, we now know that thalamic fibers reach the cortex 24 hrs earlier.

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

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.

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

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.

Short-term volume and turgor regulation in yeast

2008 ◽  
Vol 45 ◽  
pp. 147-160 ◽  
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.

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

1989 ◽  
Vol 32 (3) ◽  
pp. 681-687 ◽  
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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