scholarly journals Maintenance of neuronal size gradient in MNTB requires sound-evoked activity

2017 ◽  
Vol 117 (2) ◽  
pp. 756-766 ◽  
Author(s):  
Jessica H. Weatherstone ◽  
Conny Kopp-Scheinpflug ◽  
Nadia Pilati ◽  
Yuan Wang ◽  
Ian D. Forsythe ◽  
...  
Keyword(s):  
Cell Size ◽  
Calcium Atpase ◽  
Plasma Membrane Calcium Atpase ◽  
High Frequencies ◽  
Medial Nucleus ◽  
Soma Size ◽  
A Cell ◽  
Evoked Activity ◽  
Size Gradient ◽  
Trapezoid Body

The medial nucleus of the trapezoid body (MNTB) is an important source of inhibition during the computation of sound location. It transmits fast and precisely timed action potentials at high frequencies; this requires an efficient calcium clearance mechanism, in which plasma membrane calcium ATPase 2 (PMCA2) is a key component. Deafwaddler ( dfw 2J) mutant mice have a null mutation in PMCA2 causing deafness in homozygotes ( dfw 2J/ dfw 2J) and high-frequency hearing loss in heterozygotes (+/ dfw 2J). Despite the deafness phenotype, no significant differences in MNTB volume or cell number were observed in dfw 2J homozygous mutants, suggesting that PMCA2 is not required for MNTB neuron survival. The MNTB tonotopic axis encodes high to low sound frequencies across the medial to lateral dimension. We discovered a cell size gradient along this axis: lateral neuronal somata are significantly larger than medially located somata. This size gradient is decreased in +/ dfw 2J and absent in dfw 2J/ dfw 2J. The lack of acoustically driven input suggests that sound-evoked activity is required for maintenance of the cell size gradient. This hypothesis was corroborated by selective elimination of auditory hair cell activity with either hair cell elimination in Pou4f3 DTR mice or inner ear tetrodotoxin (TTX) treatment. The change in soma size was reversible and recovered within 7 days of TTX treatment, suggesting that regulation of the gradient is dependent on synaptic activity and that these changes are plastic rather than permanent. NEW & NOTEWORTHY Neurons of the medial nucleus of the trapezoid body (MNTB) act as fast-spiking inhibitory interneurons within the auditory brain stem. The MNTB is topographically organized, with low sound frequencies encoded laterally and high frequencies medially. We discovered a cell size gradient along this axis: lateral neurons are larger than medial neurons. The absence of this gradient in deaf mice lacking plasma membrane calcium ATPase 2 suggests an activity-dependent, calcium-mediated mechanism that controls neuronal soma size.

Spindle scaling mechanisms

2020 ◽  
Vol 64 (2) ◽  
pp. 383-396
Author(s):  
Lara K. Krüger ◽  
Phong T. Tran
Keyword(s):  
Cell Size ◽  
Spindle Assembly ◽  
Dependent Manner ◽  
Post Translational Modification ◽  
Size Dependent ◽  
A Cell ◽  
Chromosome Separation ◽  
Spindle Elongation ◽  
Protein Gradients ◽  
Spindle Structure

Abstract The mitotic spindle robustly scales with cell size in a plethora of different organisms. During development and throughout evolution, the spindle adjusts to cell size in metazoans and yeast in order to ensure faithful chromosome separation. Spindle adjustment to cell size occurs by the scaling of spindle length, spindle shape and the velocity of spindle assembly and elongation. Different mechanisms, depending on spindle structure and organism, account for these scaling relationships. The limited availability of critical spindle components, protein gradients, sequestration of spindle components, or post-translational modification and differential expression levels have been implicated in the regulation of spindle length and the spindle assembly/elongation velocity in a cell size-dependent manner. In this review, we will discuss the phenomenon and mechanisms of spindle length, spindle shape and spindle elongation velocity scaling with cell size.

Emulsion flow which preparation excludes a presence of mechanical impurities

2012 ◽  
Vol 9 (2) ◽  
pp. 118-122
Author(s):  
A.A. Rakhimov
Keyword(s):  
Cell Size ◽  
First Case ◽  
A Cell ◽  
Emulsion Flow ◽  
Blocking Mechanism

Experiments were carried out with waterhydrocarbon emulsions with various emulsifiers in capillaries with a length of 2 cm, diameters of 40 and 100 µm. To eliminate the influence of mechanical impurities comparable in size with the diameter of the capillary in first case emulsion components were filtered through fine-meshed filters. In second case obtained that way emulsion was additionally filtered through a system consisting of 3 filters with a cell size of 30-40 microns. In a capillary of 100 µm such emulsion came in a blocked state. Additional filtration of the emulsion through the mesh filters have led to an increase in viscosity but in 100 µm capillaries the time until the blocking 2-3 times more than the original. Rheology of used emulsions is well described by the model of Ostwald-de Waale. It was determined that emulsion blocking mechanism is due to the presence of inclusions not emulsion viscosity.

Extraction of Auditory Information by Modulation of Neuronal Ion Channels

2018 ◽  
pp. 272-300
Author(s):  
Leonard K. Kaczmarek
Keyword(s):  
Ion Channels ◽  
Neuronal Firing ◽  
Auditory Information ◽  
Auditory Neurons ◽  
Complex Sound ◽  
Medial Nucleus ◽  
Rapid Changes ◽  
Genes Encoding ◽  
Kinetics Of ◽  
Trapezoid Body

All neurons express a subset of over seventy genes encoding potassium channel subunits. These channels have been studied in auditory neurons, particularly in the medial nucleus of the trapezoid body. The amplitude and kinetics of various channels in these neurons can be modified by the auditory environment. It has been suggested that such modulation is an adaptation of neuronal firing patterns to specific patterns of auditory inputs. Alternatively, such modulation may allow a group of neurons, all expressing the same set of channels, to represent a variety of responses to the same pattern of incoming stimuli. Such diversity would ensure that a small number of genetically identical neurons could capture and encode many aspects of complex sound, including rapid changes in timing and amplitude. This review covers the modulation of ion channels in the medial nucleus of the trapezoid body and how it may maximize the extraction of auditory information.All neurons express a subset of over seventy genes encoding potassium channel subunits. These channels have been studied in auditory neurons, particularly in the medial nucleus of the trapezoid body. The amplitude and kinetics of various channels in these neurons can be modified by the auditory environment. It has been suggested that such modulation is an adaptation of neuronal firing patterns to specific patterns of auditory inputs. Alternatively, such modulation may allow a group of neurons, all expressing the same set of channels, to represent a variety of responses to the same pattern of incoming stimuli. Such diversity would ensure that a small number of genetically identical neurons could capture and encode many aspects of complex sound, including rapid changes in timing and amplitude. This review covers the modulation of ion channels in the medial nucleus of the trapezoid body and how it may maximize the extraction of auditory information.

scholarly journals GABA is a modulator, rather than a classical transmitter, in the medial nucleus of the trapezoid body–lateral superior olive sound localization circuit

2019 ◽  
Vol 597 (8) ◽  
pp. 2269-2295 ◽  
Author(s):  
Alexander U. Fischer ◽  
Nicolas I. C. Müller ◽  
Thomas Deller ◽  
Domenico Del Turco ◽  
Jonas O. Fisch ◽  
...  
Keyword(s):  
Sound Localization ◽  
Lateral Superior Olive ◽  
Superior Olive ◽  
Medial Nucleus ◽  
Trapezoid Body

Effect of Blowing Agent on Cell Morphology and Acoustic Absorption of Natural Rubber Foam

2015 ◽  
Vol 804 ◽  
pp. 25-29 ◽  
Author(s):  
Wanlop Harnnarongchai ◽  
Kantima Chaochanchaikul
Keyword(s):  
Natural Rubber ◽  
Cell Size ◽  
Cell Morphology ◽  
Foam Cell ◽  
Adsorption Coefficient ◽  
Low Frequencies ◽  
Potassium Oleate ◽  
High Frequencies ◽  
Blowing Agent ◽  
Open Cell Foam

The sound absorbing efficiency of natural rubber (NR) foam is affected by the cell morphology of foam. Potassium oleate (K-oleate) and sodium bicarbonate (NaHCO3) were used as blowing agents to create open-cell foam. Amounts of the blowing agent were varied from 0.5 to 8.0 part per hundred of rubber (phr) to evaluate cell size and number of foam cell as well as sound adsorption coefficient of NR foam. The NR foam specimens were prepared using mould and air-circulating oven for vulcanizing and foaming processes. The results indicated that K-oleate at 2.0 phr and NaHCO3 at 0.5 phr led to form NR foam with the smallest cell size and the largest number of foam cell. At low frequencies, the optimum sound adsorption coefficient of NR foam was caused by filling K-oleate 2 phr. However, that of NR foam at high frequencies was provided by 0.5 phr-NaHCO3 addition.

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