Biology subjects

Jung, E. E.

Publications and source records attributed to Jung, E. E..

7 recordsLinked to original sources

bioRxiv2025

Agarose Stamped Device: A simple but effective fixation method for Zebrafish Larvae through Customizable 3D Printed Molds for Danio rerio (Zebrafish)

Precise immobilization of zebrafish larvae is critical for high-resolution neural imaging and behavioral studies, yet conventional methods are often labor-intensive, low-throughput, and can induce stress. To address these challenges, we introduce the Agarose Stamped Device (ASD), a novel platform enabling efficient and gentle immobilization of zebrafish larvae for high-resolution imaging and behavioral assays. By employing a stamping approach to mold an array of consistent agarose wells, the ASD enables rapid, parallel, and reproducible positioning of larvae in a standardized orientation while minimizing stress and preserving viability. We validated ASD performance by comparing larval survival, heart rate, and imaging stability to conventional agarose embedding, finding no adverse effects on larval physiology and significantly enhanced imaging throughput and data consistency. Demonstrations in neuroscience and behavioral experiments underscore the devices versatility for diverse in vivo studies. The ASD offers a simple, cost-effective, and powerful tool for advancing zebrafish-based neuroscience and behavioral research.

bioengineering↗

bioRxiv2024

Larva in the loop, a closed loop machine interface system for Danio rerio larvae

The optokinetic response (OKR) in Zebrafish (Danio Rerio) had been characterized for its robust response to visual stimuli. Expanding on these works, we developed a novel closed loop control schema to drive a robot utilizing the OKR of Zebrafish larvae. Our system keeps the body of a larva constrained via a novel agarose mold holder that allows for eye movement and vision. The larva is then put under a microscope camera and processed through computer vision to track its eyes via ellipse fitting. Relative eye angle data is then parsed through an algorithm and used to send movement signals to a robot on a lined track. Simultaneously, the robot returns its relative position with respect to the line and converts that information into an OKR stimulation animation which is displayed on an LCD screen in the ventral plane of the larva, thus closing the loop. Through this work we show the capability of larvae OKR to keep a robot on a linear track after an initial oblique entrance to the line. This work displays the potential of our system and how it can pave the way to a Zebrafish Brain-Machine Interface.

animal behavior and cognition↗

bioRxiv2024

Hypothalamic dopamine neuron activity is modulated by caloric states and amphetamine abuse in zebrafish larvae

Dopaminergic (DA) neuron activity is affected by reward and stress-inducing entities such as food and drugs of abuse, and different DA neuron populations can respond distinctly to these stimuli. Interaction between both stimuli significantly alters the dynamics of DA release in different DA populations. Additionally, these stimulating entities can affect the interconnections among different DA populations by impairing their correspondence with each other. However, limited studies have been performed that could point to the effect of interaction between AMPH and caloric states on DA neurons and their inter-correlation. This study explores the individual and interactive effect of two caloric states, ad-libitum fed (AL) and food deprived (FD), and acute exposure to a stimulant drug (amphetamine) in two different DA neurons in the hypothalamus of zebrafish larvae. We used a transgenic zebrafish line Tg(th2:GCaMP7s), which expresses a calcium indicator (GCaMP7s) in A11(Posterior Tuberculum) and a part of A14 (Caudal Hypothalamus and Intermediate Hypothalamus) DA populations located in the hypothalamus of the larval zebrafish. The larvae were subjected to acute FD and ad AL feeding followed by acute treatment with 0.7uM and 1.5uM doses of AMPH. We recorded calcium activity and quantified fluorescence change, activity duration, peak rise/fall time, and latency in the spikes of the DA neurons. Our results show that baseline DA neuron activity amplitude, spike duration, and correlation between inter- and intra-DA neurons were higher in the FD than in the AL state. Dose-dependent AMPH treatment further increased the activity intensity of the aforementioned parameters in the neuron spikes in the FD state. The DA activity correlation and spike latency were dose-dependently impaired in both DA populations. These results suggest that different DA populations in the brain exhibit a similar activity trend in response to caloric states and AMPH, where the AMPH-mediated intensity change in the activity was dose-dependent.

neuroscience↗

bioRxiv2024

Modulation of locomotion and motor neuron response by the cohesive effect of acute and chronic feeding states and acute d-amphetamine treatment in zebrafish larvae.

Amphetamine (AMPH) increases locomotor activities in animals, and the locomotor response to AMPH is further modulated by caloric deficits such as food deprivation and restriction. The increment in locomotor activity regulated by AMPH-caloric deficit concomitance can be further modulated by varying feeding schedules (e.g. acute and chronic food deprivation and acute feeding after chronic food deprivation). However, the effects of different feeding schedules on AMPH-induced locomotor activity are yet to be explicated. Here, we have explored the stimulatory responses of acutely administered d-amphetamine in locomotion under systematically varying feeding states (fed/sated and food deprivation) and schedules (chronic and acute) in zebrafish larvae. We used wild-type and transgenic[Tg(mnx1:GCaMP5)] zebrafish larvae and measured swimming activity and spinal motor neuron activity in vivo in real-time in time-elapsed and cumulative manner pre- and post-AMPH treatment. Our results showed that locomotion and motor neuron activity increased in both chronic and acute food deprivation post-AMPH treatment cumulatively. A steady increase in locomotion was observed in acute food-deprivation compared to an immediate abrupt increase in chronic food-deprivation state. The ad libitum-fed larvae exhibited a moderate increase both in locomotion and motor neuron activity. Conversely to all other caloric states, food-sated (acute feeding after chronic food deprivation) larvae moved moderately less and exhibited a mild decrease in motor neuron activity after AMPH treatment. These results point to the importance of the feeding schedule in modulating amphetamines characteristic stimulatory response on behavior and motor neurons.

neuroscience↗

bioRxiv2022

Food deprivation modulates heart rate, motor neuron, and locomotion responses to acute administration of d-amphetamine in zebrafish larvae

Psychostimulant drugs are so named because they alter the cardiac, brain and behavioral responses in humans and other animals. Acute food deprivation or chronic food restriction potentiates the stimulatory effects of abused drugs and increases the propensity for relapse to drug seeking in drug-experienced animals. The mechanisms by which hunger affects cardiac and behavioral activities are only beginning to be elucidated. Moreover, changes in motor neuron activities at the single neuron level induced by the stimulants, and their modulation by hunger, remain unknown. Here we investigated how the state of hunger affects responses to d-amphetamine by measuring locomotion, cardiac output, and individual motor neuron activity in zebrafish larvae. We used wild-type larval zebrafish to record behavioral and cardiac responses and the larvae of mnx1:GCaMP transgenic zebrafish to record motor neuron responses. Acute administration of d-amphetamine in sated larvae did not induce a significant change in the motor responses (swimming distances, tail activity), heart rate, or motor neuron firing frequency to the stimulant. However, food deprivation enhanced amphetamine-evoked responses significantly. The results extend the finding that signals arising from food deprivation are a key potentiator of the drug responses induced by d-amphetamine to the zebrafish model. The larval zebrafish is an ideal model to further elucidate this interaction and identify key neuronal substrates that may increase vulnerability to drug reinforcement, drug-seeking and relapse.

animal behavior and cognition↗

bioRxiv2021

Whole-ExM: Expansion microscopy imaging of all anatomical structures of whole larval zebrafish

Nanoscale resolution imaging of whole vertebrates is required for a systematic understanding of human diseases, but this has yet to be realized. Expansion microscopy (ExM) is an attractive option for achieving this goal, but the expansion of whole vertebrates has not been demonstrated due to the difficulty of expanding hard body components. Here, we demonstrate whole-body ExM, which enables nanoscale resolution imaging of anatomical structures, proteins, and endogenous fluorescent proteins (FPs) of whole zebrafish larvae and mouse embryos by expanding them fourfold. We first show that post-digestion decalcification and digestion kinetics matching are critical steps in the expansion of whole vertebrates. Then, whole-body ExM is combined with the improved pan-protein labeling approach to demonstrate the three-dimensional super-resolution imaging of antibody- or FP-labeled structures and all major anatomical structures surrounding them. We also show that whole-body ExM enables visualization of the nanoscale details of neuronal structures across the entire body.

developmental biology↗

bioRxiv2019

Population imaging of neural activity in awake behaving mice in multiple brain regions

A longstanding goal in neuroscience has been to image membrane voltage, with high temporal precision and sensitivity, in awake behaving mammals. Here, we report a genetically encoded voltage indicator, SomArchon, which exhibits millisecond response times and compatibility with optogenetic control, and which increases the sensitivity, signal-to-noise ratio, and number of neurons observable, by manyfold over previous reagents. SomArchon only requires conventional one-photon microscopy to achieve these high performance characteristics. These improvements enable population analysis of neural activity, both at the subthreshold and spiking levels, in multiple brain regions - cortex, hippocampus, and striatum - of awake behaving mice. Using SomArchon, we detect both positive and negative responses of striatal neurons during movement, highlighting the power of voltage imaging to reveal bidirectional modulation. We also examine how the intracellular subthreshold theta oscillations of hippocampal neurons govern spike output, finding that nearby cells can exhibit highly correlated subthreshold activities, even as they generate highly divergent spiking patterns.

neuroscience↗