Microfluidic Transportation Control of Larval Zebrafish through Optomotor Regulations under a Pressure-Driven Flow.

Bivas Panigrahi,Chia-Yuan Chen

doi:10.3390/mi10120880

Abstract

To perform zebrafish larvae-related experiments within a microfluidic environment, the larvae need to be anesthetized and subsequently transported into respective test sections through mechanical or manual means. However, anesthetization tends to affect larval sensory perceptions, hindering their natural behaviors. Taking into account that juvenile larvae move naturally within their environment by accessing visual as well as hydromechanical cues, this work proposes an experimental framework to transport nonanesthetized larvae within a microfluidic environment by harmonically tuning both of the aforementioned cues. To provide visual cues, computer-animated moving gratings were provided through an in-house-developed control interface that drove the larval optomotor response. In the meantime, to provide hydromechanical cues, the flow rate was tuned using a syringe pump that affected the zebrafish larvae’s lateral line movement. The results obtained (corresponding to different test conditions) suggest that the magnitude of both modalities plays a crucial role in larval transportation and orientation control. For instance, with a flow rate tuning of 0.1 mL/min along with grating parameters of 1 Hz temporal frequency, the average transportation time for larvae that were 5 days postfertilization was recorded at 1.29 ± 0.49 s, which was approximately three times faster than the transportation time required only in the presence of hydromechanical cues.

Highlights

Zebrafish (Danio rerio) are unarguably considered to be one of the most important animal models that have been used for studies on neurobiological development [1], cardiac development [2,3,4], pharmacological research [5], genetic modeling [6], and toxicological research [7,8]
As the objective of this work was to transport zebrafish larvae efficiently within the microfluidic environment by regulating only environmental cues, experiments were conducted by positioning the zebrafish larvae in the microchannel and introducing different flow stimuli (0.05–0.3 mL/min) in the presence and absence of optical cues
A similar trend was observed for other flow rates, including 0.1, 0.2, and 0.3 mL/min, which indicates the importance of both parameters in the microfluidic manipulation of zebrafish larvae

Summary

Introduction

Zebrafish (Danio rerio) are unarguably considered to be one of the most important animal models that have been used for studies on neurobiological development [1], cardiac development [2,3,4], pharmacological research [5], genetic modeling [6], and toxicological research [7,8]. The manual procedure of larvae manipulation requires an operator’s intervention to position the larvae with precision, which is time-consuming by nature and hinders high-throughput screening processes for new drug testing. At this point, it can be noted that juvenile zebrafish usually take their environmental cues through multisensory processes that can be affected by several stimulus modalities, such as vestibular inputs, heat, visual stimuli, and hydromechanical cues. This study hypothesizes that by regulating hydromechanical and visual modalities within the microfluidic platform, juvenile larvae can be manipulated with precision in a noninvasive manner

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Conclusion