scholarly journals Internalization of styryl dye FM1-43 in the hair cells of lateral line organs in Xenopus larvae.

1996 ◽  
Vol 44 (7) ◽  
pp. 733-741 ◽  
Author(s):  
S Nishikawa ◽  
F Sasaki
Keyword(s):  
Endoplasmic Reticulum ◽  
Lateral Line ◽  
Hair Cells ◽  
Divalent Cations ◽  
Apical Part ◽  
Cation Channel ◽  
Monovalent Cations ◽  
Photo Oxidation ◽  
Styryl Dye ◽  
Endocytic Activity

We used a fluorescent dye, FM1-43 to investigate mechanotransduction mechanisms in the hair cells of lateral line organs of Xenopus larvae. FM1-43 specifically labeled the hair cells. The photo-oxidation technique was performed with election microscopy to examine the labeling sites and their mechanisms. The results showed that the labeling sites were mitochondria and rough endoplasmic reticulum throughout the cytoplasm. Endocytic activity of the hair cells was limited to endosomes and small granules located at the apical part of the cells. Blockers of the mechanosensitive cation channel (neomycin, gentamicin, streptomycin, and amiloride) effectively inhibited FM1-43 labeling. One of the blockers, amiloride, was found to bind to hair cells when its fluorescence was examined. Divalent cations such as Mg2+ and Ca2+, but not monovalent cations such as Na+ and K+, inhibited FM1-43 labeling when they were added in excess amounts. These results suggest that FM1-43 internalizes hair cells via the putative mechanosensitive cation channel in the plasma membrane.

scholarly journals Pregnancy associated plasma protein-aa regulates endoplasmic reticulum-mitochondria associations

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Mroj Alassaf ◽  
Mary C Halloran
Keyword(s):  
Endoplasmic Reticulum ◽  
Growth Factor ◽  
Plasma Protein ◽  
Lateral Line ◽  
Hair Cells ◽  
Mitochondrial Function ◽  
Mitochondrial Morphology ◽  
Sensory Hair Cells ◽  
Downstream Processes ◽  
Er Calcium

Endoplasmic reticulum (ER) and mitochondria form close physical associations to facilitate calcium transfer, thereby regulating mitochondrial function. Neurons with high metabolic demands, such as sensory hair cells, are especially dependent on precisely regulated ER-mitochondria associations. We previously showed that the secreted metalloprotease Pregnancy associated plasma protein-aa (Pappaa) regulates mitochondrial function in zebrafish lateral line hair cells (Alassaf et al., 2019). Here, we show that pappaa mutant hair cells exhibit excessive and abnormally close ER-mitochondria associations, suggesting increased ER-mitochondria calcium transfer. pappaa mutant hair cells are more vulnerable to pharmacological induction of ER-calcium transfer. Additionally, pappaa mutant hair cells display ER stress and dysfunctional downstream processes of the ER-mitochondria axis including altered mitochondrial morphology and reduced autophagy. We further show that Pappaa influences ER-calcium transfer and autophagy via its ability to stimulate insulin-like growth factor-1 bioavailability. Together our results identify Pappaa as a novel regulator of the ER-mitochondria axis.

scholarly journals Anion Exchanger 1b in Stereocilia Is Required for the Functioning of Mechanotransducer Channels in Lateral-Line Hair Cells of Zebrafish

PLoS ONE ◽  
2015 ◽  
Vol 10 (2) ◽  
pp. e0117041 ◽  
Author(s):  
Yuan-Hsiang Lin ◽  
Giun-Yi Hung ◽  
Liang-Chun Wu ◽  
Sheng-Wen Chen ◽  
Li-Yih Lin ◽  
...  
Keyword(s):  
Lateral Line ◽  
Hair Cells ◽  
Anion Exchanger

S-100 protein is a selective marker for sensory hair cells of the lateral line system in teleosts

2002 ◽  
Vol 329 (2) ◽  
pp. 133-136 ◽  
Author(s):  
F Abbate ◽  
S Catania ◽  
A Germanà ◽  
T González ◽  
B Diaz-Esnal ◽  
...  
Keyword(s):  
Lateral Line ◽  
Hair Cells ◽  
Lateral Line System ◽  
Selective Marker ◽  
Line System ◽  
Sensory Hair ◽  
Sensory Hair Cells ◽  
S 100

Extracellular Receptor Potentials from the Lateral-Line Organ of Xenopus Laevis

1980 ◽  
Vol 86 (1) ◽  
pp. 63-77
Author(s):  
ALFONS B. A. KROESE ◽  
JOHAN M. VAN DER ZALM ◽  
JOEP VAN DEN BERCKEN
Keyword(s):  
Xenopus Laevis ◽  
Lateral Line ◽  
Hair Cells ◽  
Water Displacement ◽  
Stimulus Amplitude ◽  
Nerve Fibres ◽  
Large Stimulus ◽  
Sensory Hair ◽  
Lateral Line Organ ◽  
Line Organ

1. The response of the epidermal lateral-line organ of Xenopus laevis to stimulation was studied by recording extracellular receptor potentials from the hair cells in single neuromasts in isolated preparations. One neuromast was stimulated by local, sinusoidal water movements induced by a glass sphere positioned at a short distance from the neuromast. 2. The amplitudes of the extracellular receptor potentials were proportional to the stimulus amplitude over a range of 20 dB. The phase of the extracellular receptor potentials with respect to water displacement was independent of the stimulus amplitude. 3. With large stimulus amplitude, and stimulus frequencies between 0.5 Hz and 2 Hz, the extracellular receptor potentials, and responses of single afferent nerve fibres, showed a phase lead of 1.2 π radians with respect to water displacement, i.e. they were almost in phase with water acceleration. 4. It is concluded that under conditions of stimulation with small-amplitude water movements, the hair cells respond to sensory hair displacement, whereas under conditions of stimulation with large-amplitude water movements they respond to sensory hair velocity.

Cation exchange in cell walls of gram-positive bacteria

1976 ◽  
Vol 22 (7) ◽  
pp. 975-982 ◽  
Author(s):  
Robert E. Marquis ◽  
Kathleen Mayzel ◽  
Edwin L. Carstensen
Keyword(s):  
Cation Exchange ◽  
Cell Walls ◽  
Divalent Cations ◽  
Teichoic Acid ◽  
Dry Weight ◽  
High Ionic Strength ◽  
Monovalent Cations ◽  
Anionic Sites ◽  
Gram Positive Bacteria ◽  
Anionic Groups

The relative affinities of various cations for anionic sites in isolated, bacterial cell walls were assessed by means of a technique involving displacement of one cation by another. The affinity series determined was [Formula: see text]. High affinity was correlated with low mobility of the bound ions in an electric field. The net cation-exchange capacities of walls isolated from a variety of bacteria were estimated by preparing the magnesium forms of the walls, washing them well with deionized water to remove supernumerary ions, and then completely displacing the magnesium with Na+ or H+. Total amounts of magnesium displaced varied from 73 μmol per gram dry weight, for walls of the teichoic acid-deficient 52A5 strain of Staphylococcus aureus to about 520 μmol per gram for Bacillus megaterium KM walls. The amount of displacable magnesium was inversely related to the physical compactness of the walls, except for walls of Streptococcus mutans GS-5. It was found that magnesium or calcium ions can each neutralize, or pair with, two anionic groups in walls suspended in ion-deficient media. Previous work had indicated that these ions may pair with only one anionic group at high ionic strength. Therefore, it appeared that there is a great deal of flexibility in the arrangement of charged groups in the wall. It was concluded also that for cells growing in commonly used laboratory media, which generally contain large excesses of monovalent versus divalent cations, there is a mix of small, cationic counterions in the wall and that monovalent cations may predominate even though the wall has higher affinity for divalent ions.

scholarly journals Using the Zebrafish Lateral Line to Understand the Roles of Mitochondria in Sensorineural Hearing Loss

2021 ◽  
Vol 8 ◽  
Author(s):  
Melanie Holmgren ◽  
Lavinia Sheets
Keyword(s):  
Cell Death ◽  
Hearing Loss ◽  
Hair Cell ◽  
Sensorineural Hearing Loss ◽  
Lateral Line ◽  
Hair Cells ◽  
High Energy ◽  
Sensorineural Hearing ◽  
Mitochondrial Activity ◽  
Ototoxic Drugs

Hair cells are the mechanosensory receptors of the inner ear and can be damaged by noise, aging, and ototoxic drugs. This damage often results in permanent sensorineural hearing loss. Hair cells have high energy demands and rely on mitochondria to produce ATP as well as contribute to intracellular calcium homeostasis. In addition to generating ATP, mitochondria produce reactive oxygen species, which can lead to oxidative stress, and regulate cell death pathways. Zebrafish lateral-line hair cells are structurally and functionally analogous to cochlear hair cells but are optically and pharmacologically accessible within an intact specimen, making the zebrafish a good model in which to study hair-cell mitochondrial activity. Moreover, the ease of genetic manipulation of zebrafish embryos allows for the study of mutations implicated in human deafness, as well as the generation of transgenic models to visualize mitochondrial calcium transients and mitochondrial activity in live organisms. Studies of the zebrafish lateral line have shown that variations in mitochondrial activity can predict hair-cell susceptibility to damage by aminoglycosides or noise exposure. In addition, antioxidants have been shown to protect against noise trauma and ototoxic drug–induced hair-cell death. In this review, we discuss the tools and findings of recent investigations into zebrafish hair-cell mitochondria and their involvement in cellular processes, both under homeostatic conditions and in response to noise or ototoxic drugs. The zebrafish lateral line is a valuable model in which to study the roles of mitochondria in hair-cell pathologies and to develop therapeutic strategies to prevent sensorineural hearing loss in humans.

scholarly journals Connectomics of the zebrafish's lateral-line neuromast reveals wiring and miswiring in a simple microcircuit

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Eliot Dow ◽  
Adrian Jacobo ◽  
Sajjad Hossain ◽  
Kimberly Siletti ◽  
A J Hudspeth
Keyword(s):  
Hair Cell ◽  
Lateral Line ◽  
Hair Cells ◽  
Planar Cell Polarity ◽  
Developmental Stages ◽  
Notch Signaling Pathway ◽  
Nerve Fibers ◽  
Directional Sensitivity ◽  
Efferent Nerve ◽  
Polarity Gene

The lateral-line neuromast of the zebrafish displays a restricted, consistent pattern of innervation that facilitates the comparison of microcircuits across individuals, developmental stages, and genotypes. We used serial blockface scanning electron microscopy to determine from multiple specimens the neuromast connectome, a comprehensive set of connections between hair cells and afferent and efferent nerve fibers. This analysis delineated a complex but consistent wiring pattern with three striking characteristics: each nerve terminal is highly specific in receiving innervation from hair cells of a single directional sensitivity; the innervation is redundant; and the terminals manifest a hierarchy of dominance. Mutation of the canonical planar-cell-polarity gene vangl2, which decouples the asymmetric phenotypes of sibling hair-cell pairs, results in randomly positioned, randomly oriented sibling cells that nonetheless retain specific wiring. Because larvae that overexpress Notch exhibit uniformly oriented, uniformly innervating hair-cell siblings, wiring specificity is mediated by the Notch signaling pathway.

Sign in / Sign up

Export Citation Format

Share Document