Lateral Line Ablation by Toxins Results in Distinct Rheotaxis Profiles in Fish

Zebrafish lateral line is an established model for hair cell organ damage, yet few studies link mechanistic disruptions to changes in biologically relevant behavior. We used larval zebrafish to determine how damage via ototoxic chemicals impact rheotaxis. Larvae were treated with CuSO4 or neomycin to disrupt lateral line function then exposed to water flow stimuli. Their swimming behavior was recorded, and DeepLabCut and SimBA software were used to track movements and classify rheotaxis behavior. Lateral line-disrupted fish performed rheotaxis, but they swam greater distances, for shorter durations, and with greater angular variance than controls. Further, spectral decomposition analyses demonstrated that lesioned fish exhibited toxin-specific behavioral profiles with distinct fluctuations in the magnitude, timing, and cross-correlation between changes in linear and angular movements. Our observations support that lateral-line input is needed for fish to perform rheotaxis efficiently in flow and reveals commonly used lesion methods have unique effects on behavior.

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Brain-wide mapping of water flow perception in zebrafish

10.1101/2020.01.07.896738 ◽

2020 ◽

Cited By ~ 1

Author(s):

Gilles Vanwalleghem ◽

Kevin Schuster ◽

Michael A. Taylor ◽

Itia A. Favre-Bulle ◽

Ethan K. Scott

Keyword(s):

Water Flow ◽

Lateral Line ◽

Reverse Flow ◽

Forward Direction ◽

Brain Regions ◽

Reverse Direction ◽

Departure Point ◽

Forward Flow ◽

Larval Zebrafish ◽

The Brain

AbstractInformation about water flow, detected by lateral line organs, is critical to the behavior and survival of fish and amphibians. While certain specific aspects of water flow processing have been revealed through electrophysiology, we lack a comprehensive description of the neurons that respond to water flow and the network that they form. Here, we use brain-wide calcium imaging in combination with microfluidic stimulation to map out, at cellular resolution, all neurons involved in perceiving and processing water flow information in larval zebrafish. We find a diverse array of neurons responding to forward flow, reverse flow, or both. Early in this pathway, in the lateral line ganglia, these are almost exclusively neurons responding to the simple presence of forward or reverse flow, but later processing includes neurons responding specifically to flow onset, representing the accumulated volume of flow during a stimulus, or encoding the speed of the flow. The neurons reporting on these more nuanced details are located across numerous brain regions, including some not previously implicated in water flow processing. A graph theory-based analysis of the brain-wide water flow network shows that a majority of this processing is dedicated to forward flow detection, and this is reinforced by our finding that details like flow velocity and the total volume of accumulated flow are only encoded for the simulated forward direction. The results represent the first brain-wide description of processing for this important modality, and provide a departure point for more detailed studies of the flow of information through this network.Significance statementIn aquatic animals, the lateral line is important for detecting water flow stimuli, but the brain networks that interpret this information remain mysterious. Here, we have imaged the activity of individual neurons across the entire brains of larval zebrafish, revealing all response types and their brain locations as water flow processing occurs. We find some neurons that respond to the simple presence of water flow, and others that are attuned to the flow’s direction, speed, duration, or the accumulated volume of water that has passed during the stimulus. With this information, we modeled the underlying network, describing a system that is nuanced in its processing of water flow simulating forward motion but rudimentary in processing flow in the reverse direction.

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Macrophages Respond Rapidly to Ototoxic Injury of Lateral Line Hair Cells but Are Not Required for Hair Cell Regeneration

Frontiers in Cellular Neuroscience ◽

10.3389/fncel.2020.613246 ◽

2021 ◽

Vol 14 ◽

Author(s):

Mark E. Warchol ◽

Angela Schrader ◽

Lavinia Sheets

Keyword(s):

Hair Cell ◽

Inner Ear ◽

Lateral Line ◽

Hair Cells ◽

Control Fish ◽

Cell Regeneration ◽

Cellular Interactions ◽

Hair Cell Regeneration ◽

Genetic Ablation ◽

Larval Zebrafish

The sensory organs of the inner ear contain resident populations of macrophages, which are recruited to sites of cellular injury. Such macrophages are known to phagocytose the debris of dying cells but the full role of macrophages in otic pathology is not understood. Lateral line neuromasts of zebrafish contain hair cells that are nearly identical to those in the inner ear, and the optical clarity of larval zebrafish permits direct imaging of cellular interactions. In this study, we used larval zebrafish to characterize the response of macrophages to ototoxic injury of lateral line hair cells. Macrophages migrated into neuromasts within 20 min of exposure to the ototoxic antibiotic neomycin. The number of macrophages in the near vicinity of injured neuromasts was similar to that observed near uninjured neuromasts, suggesting that this early inflammatory response was mediated by “local” macrophages. Upon entering injured neuromasts, macrophages actively phagocytosed hair cell debris. The injury-evoked migration of macrophages was significantly reduced by inhibition of Src-family kinases. Using chemical-genetic ablation of macrophages before the ototoxic injury, we also examined whether macrophages were essential for the initiation of hair cell regeneration. Results revealed only minor differences in hair cell recovery in macrophage-depleted vs. control fish, suggesting that macrophages are not essential for the regeneration of lateral line hair cells.

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Macrophages respond rapidly to ototoxic injury of lateral line hair cells but are not required for hair cell regeneration

10.1101/2020.09.28.314922 ◽

2020 ◽

Cited By ~ 1

Author(s):

Mark E. Warchol ◽

Angela Schrader ◽

Lavinia Sheets

Keyword(s):

Hair Cell ◽

Inner Ear ◽

Lateral Line ◽

Hair Cells ◽

Control Fish ◽

Cell Regeneration ◽

Cellular Interactions ◽

Hair Cell Regeneration ◽

Genetic Ablation ◽

Larval Zebrafish

AbstractThe sensory organs of the inner ear contain resident populations of macrophages, which are recruited to sites of cellular injury. Such macrophages are known to phagocytose the debris of dying cells but the full role of macrophages in otic pathology is not understood. Lateral line neuromasts of zebrafish contain hair cells similar to those in the inner ear, and the optical clarity of larval zebrafish permits direct imaging of cellular interactions. In this study, we used larval zebrafish to characterize the response of macrophages to ototoxic injury of lateral line hair cells. Macrophages migrated into neuromasts within 20 min of exposure to the ototoxic antibiotic neomycin. The number of macrophages in close proximity of injured neuromasts was similar to that observed near uninjured neuromasts, suggesting that this early inflammatory response was mediated by ‘local’ macrophages. Upon entering injured neuromasts, macrophages actively phagocytosed hair cell debris. Such phagocytosis was significantly reduced by inhibiting Src-family kinases. Using chemical-genetic ablation of macrophages prior to ototoxic injury, we also examined whether macrophages were essential for the initiation of hair cell regeneration after neomycin exposure. Results revealed only minor differences in hair cell recovery in macrophage-depleted vs. control fish, suggesting that macrophages are not essential for the regeneration of lateral line hair cells.

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Mechanical overstimulation causes acute injury followed by fast recovery in lateral-line neuromasts of larval zebrafish

10.1101/2020.07.15.205492 ◽

2020 ◽

Cited By ~ 1

Author(s):

Melanie Holmgren ◽

Michael E. Ravicz ◽

Kenneth E. Hancock ◽

Olga Strelkova ◽

Artur A. Indzhykulian ◽

...

Keyword(s):

Hair Cell ◽

Lateral Line ◽

Hair Cells ◽

Cell Damage ◽

Acute Injury ◽

Water Current ◽

Functional Changes ◽

Larval Zebrafish ◽

Auditory Nerves ◽

Hair Cell Damage

AbstractNoise exposure damages sensory hair cells, resulting in loss of synaptic connections with auditory nerves and hair-cell death. The cellular mechanisms underlying noise-induced hair-cell damage and subsequent repair are not completely understood. Hair cells in neuromasts (NMs) of larval zebrafish are structurally and functionally comparable to mammalian hair cells but undergo robust regeneration following damage. We therefore developed a model for noise-induced hair-cell damage in this highly tractable system. Free swimming larvae exposed to strong water current for 2 hours displayed damage to NMs, including synapse loss, afferent neurite retraction, damaged hair bundles, and reduced mechanotransduction. Overstimulation also elicited an inflammatory response and macrophage recruitment. Remarkably, NM morphology and function appeared to fully recover within 2 days following exposure. Our results reveal morphological and functional changes in mechanically overstimulated lateral-line NMs that are analogous to changes observed in noise-exposed mammalian ear yet are rapidly and completely repaired.

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Mechanical overstimulation causes acute injury and synapse loss followed by fast recovery in lateral-line neuromasts of larval zebrafish

eLife ◽

10.7554/elife.69264 ◽

2021 ◽

Vol 10 ◽

Author(s):

Melanie Holmgren ◽

Michael E Ravicz ◽

Kenneth E Hancock ◽

Olga Strelkova ◽

Dorina Kallogjeri ◽

...

Keyword(s):

Hair Cell ◽

Lateral Line ◽

Hair Cells ◽

Cell Damage ◽

Mechanical Damage ◽

Excess Noise ◽

Larval Zebrafish ◽

Synapse Loss ◽

Auditory Nerves ◽

Hair Cell Damage

Excess noise damages sensory hair cells, resulting in loss of synaptic connections with auditory nerves and, in some cases, hair-cell death. The cellular mechanisms underlying mechanically induced hair-cell damage and subsequent repair are not completely understood. Hair cells in neuromasts of larval zebrafish are structurally and functionally comparable to mammalian hair cells but undergo robust regeneration following ototoxic damage. We therefore developed a model for mechanically induced hair-cell damage in this highly tractable system. Free swimming larvae exposed to strong water wave stimulus for 2 hours displayed mechanical injury to neuromasts, including afferent neurite retraction, damaged hair bundles, and reduced mechanotransduction. Synapse loss was observed in apparently intact exposed neuromasts, and this loss was exacerbated by inhibiting glutamate uptake. Mechanical damage also elicited an inflammatory response and macrophage recruitment. Remarkably, neuromast hair-cell morphology and mechanotransduction recovered within hours following exposure, suggesting severely damaged neuromasts undergo repair. Our results indicate functional changes and synapse loss in mechanically damaged lateral-line neuromasts that share key features of damage observed in noise-exposed mammalian ear. Yet, unlike the mammalian ear, mechanical damage to neuromasts is rapidly reversible.

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Faculty Opinions recommendation of Identification of modulators of hair cell regeneration in the zebrafish lateral line.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.714447804.790002804 ◽

2012 ◽

Author(s):

Andy Groves

Keyword(s):

Hair Cell ◽

Lateral Line ◽

Cell Regeneration ◽

Hair Cell Regeneration

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Frequency response properties of primary afferent neurons in the posterior lateral line system of larval zebrafish

Journal of Neurophysiology ◽

10.1152/jn.00414.2014 ◽

2015 ◽

Vol 113 (2) ◽

pp. 657-668 ◽

Cited By ~ 9

Author(s):

Rafael Levi ◽

Otar Akanyeti ◽

Aleksander Ballo ◽

James C. Liao

Keyword(s):

Lateral Line ◽

Sine Wave ◽

Afferent Neuron ◽

Lateral Line System ◽

Afferent Neurons ◽

Primary Afferent Neurons ◽

Primary Afferent ◽

Line System ◽

Response Properties ◽

Larval Zebrafish

The ability of fishes to detect water flow with the neuromasts of their lateral line system depends on the physiology of afferent neurons as well as the hydrodynamic environment. Using larval zebrafish ( Danio rerio), we measured the basic response properties of primary afferent neurons to mechanical deflections of individual superficial neuromasts. We used two types of stimulation protocols. First, we used sine wave stimulation to characterize the response properties of the afferent neurons. The average frequency-response curve was flat across stimulation frequencies between 0 and 100 Hz, matching the filtering properties of a displacement detector. Spike rate increased asymptotically with frequency, and phase locking was maximal between 10 and 60 Hz. Second, we used pulse train stimulation to analyze the maximum spike rate capabilities. We found that afferent neurons could generate up to 80 spikes/s and could follow a pulse train stimulation rate of up to 40 pulses/s in a reliable and precise manner. Both sine wave and pulse stimulation protocols indicate that an afferent neuron can maintain their evoked activity for longer durations at low stimulation frequencies than at high frequencies. We found one type of afferent neuron based on spontaneous activity patterns and discovered a correlation between the level of spontaneous and evoked activity. Overall, our results establish the baseline response properties of lateral line primary afferent neurons in larval zebrafish, which is a crucial step in understanding how vertebrate mechanoreceptive systems sense and subsequently process information from the environment.

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