Selected Grantee Publications
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- R43/R44 [SBIR]
The Effect of Common Paralytic Agents Used for Fluorescence Imaging on Redox Tone and ATP Levels in Caenorhabditis elegans
Morton et al., PLOS One. 2024.
https://pubmed.ncbi.nlm.nih.gov/38669260
Caenorhabditis elegans is a highly valuable model organism in biological research. However, these worms must be paralyzed for most imaging applications, and the effect that common chemical anesthetics may have on the parameters measured—especially biochemical measurements such as cellular energetics and redox tone—is poorly understood. In this study, the authors used two reporters—QUEEN-2m for relative ATP levels and reduction-oxidation–sensitive green fluorescent protein for redox tone—to assess the impact of commonly used chemical paralytics. The results show that all chemical anesthetics at doses required for full paralysis alter redox tone and/or ATP levels, and anesthetic use alters the detected outcome of rotenone exposure on relative ATP levels and redox tone. Therefore, it is important to tailor the use of anesthetics to different endpoints and experimental questions and to develop less disruptive paralytic methods for optimal imaging of dynamic in vivo reporters. Supported by ORIP (P40OD010440, R44OD024963) and NIEHS.
Gigapixel Imaging With a Novel Multi-Camera Array Microscope
Thomson et al., eLife. 2022.
https://www.doi.org/10.7554/eLife.74988
The dynamics of living organisms are organized across many spatial scales. The investigators created assembled a scalable multi-camera array microscope (MCAM) that enables comprehensive high-resolution, large field-of-view recording from multiple spatial scales simultaneously, ranging from structures that approach the cellular scale to large-group behavioral dynamics. By collecting data from up to 96 cameras, they computationally generated gigapixel-scale images and movies with a field of view over hundreds of square centimeters at an optical resolution of 18 µm. This system allows the team to observe the behavior and fine anatomical features of numerous freely moving model organisms on multiple spatial scales (e.g., larval zebrafish, fruit flies, slime mold). Overall, by removing the bottlenecks imposed by single-camera image acquisition systems, the MCAM provides a powerful platform for investigating detailed biological features and behavioral processes of small model organisms. Supported by ORIP (R44OD024879), NIEHS, NCI, and NIBIB.
Functional and Ultrastructural Analysis of Reafferent Mechanosensation in Larval Zebrafish
Odstrcil et al., Current Biology. 2022.
https://www.sciencedirect.com/science/article/pii/S096098222101530X
All animals need to differentiate between exafferent stimuli (caused by the environment) and reafferent stimuli (caused by their own movement). Researchers characterized how hair cells in zebrafish larvae discriminate between reafferent and exafferent signals. Dye labeling of the lateral line nerve and functional imaging was combined with ultra-structural electron microscopy circuit reconstruction to show that cholinergic signals originating from the hindbrain transmit efference copies, and dopaminergic signals from the hypothalamus may affect threshold modulation. Findings suggest that this circuit is the core implementation of mechanosensory reafferent suppression in these young animals. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Precise Visuomotor Transformations Underlying Collective Behavior in Larval Zebrafish
Harpaz et al., Nature Communications. 2021.
https://www.nature.com/articles/s41467-021-26748-0
Sensory signals from neighbors, analyzed in the visuomotor stream of animals, is poorly understood. The authors studied aggregation behavior in larval zebrafish and found that over development larvae transition from over dispersed groups to tight shoals. Young larvae turn away from virtual neighbors by integrating and averaging retina-wide visual occupancy within each eye, and by using a winner-take-all strategy for binocular integration. Observed algorithms accurately predict group structure over development. These findings allow testable predictions regarding the neuronal circuits underlying collective behavior in zebrafish. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Collective Behavior Emerges from Genetically Controlled Simple Behavioral Motifs in Zebrafish
Harpaz et al., Science Advances. 2021.
https://www.science.org/doi/10.1126/sciadv.abi7460
Harpaz et al. report that zebrafish regulate their proximity and alignment with each other at early larval stages. Two visual responses (one measuring relative visual field occupancy and one accounting for global visual motion), account for emerging group behavior. Mutations in genes known to affect social behavior in humans perturb these reflexes in individual larval zebrafish and change their emergent collective behaviors. Model simulations show that changes in these two responses in individual mutant animals predict well the distinctive collective patterns that emerge in a group. Hence, group behaviors reflect in part genetically defined primitive sensorimotor “motifs” evident in young larvae. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Algorithms Underlying Flexible Phototaxis in Larval Zebrafish
Chen et al., Journal of Experimental Biology. 2021.
https://pubmed.ncbi.nlm.nih.gov/34027982/
Given that physiological and environmental variables undergo constant fluctuations over time, how do biological control systems maintain control over these values? The authors demonstrate that larval zebrafish use phototaxis to maintain environmental luminance at a set point, that the value of this set point fluctuates on a time scale of seconds when environmental luminance changes, and it is determined by calculating the mean input across both sides of the visual field. Feedback from the surroundings drives allostatic changes to the luminance set point. The authors describe a novel behavioral algorithm with which larval zebrafish exert control over a sensory variable. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Larval Zebrafish Use Olfactory Detection of Sodium and Chloride to Avoid Salt Water
Herrera et al., Current Biology. 2021.
https://pubmed.ncbi.nlm.nih.gov/33338431/
Zebrafish are freshwater fish unable to tolerate high-salt environments and would benefit from neural mechanisms that enable the navigation of salt gradients to avoid high salinity. Yet zebrafish lack epithelial sodium channels, the primary conduit land animals use to taste sodium. This suggests fish may possess novel, undescribed mechanisms for salt detection. In the present study, the authors show that zebrafish indeed respond to small temporal increases in salt by reorienting more frequently. In summary, this study establishes that zebrafish larvae can navigate and thus detect salinity gradients and that this is achieved through previously undescribed sensory mechanisms for salt detection. Supported by ORIP (R43OD024879, R44OD024879) and NINDS.
Fluorescence-Based Sorting of Caenorhabditis elegans via Acoustofluidics
Zhang et al., Lab on a Chip. 2020.
The authors present an integrated acoustofluidic chip capable of identifying worms of interest based on expression of a fluorescent protein in a continuous flow and then separate them in a high-throughput manner. Utilizing planar fiber optics, their acoustofluidic device requires no temporary immobilization of worms for interrogation/detection, thereby improving the throughput. The device can sort worms of different developmental stages (L3 and L4 stage worms) at high throughput and accuracy. In their acoustofluidic chip, the time to complete the detection and sorting of one worm is only 50 ms, which outperforms nearly all existing microfluidics-based worm sorting devices. Supported by ORIP (R43OD024963), NIEHS, and NIDDK.