Manipulation of zebrafish's orientation using artificial cilia in a microchannel with actively adaptive wall design

Karthick Mani, Tsung-Chun Chang Chien, Bivas Panigrahi, Chia-Yuan Chen
2016 Scientific Reports  
The zebrafish is a powerful genetic model organism especially in the biomedical chapter for new drug discovery and development. The genetic toolbox which this vertebrate possesses opens a new window to investigate the etiology of human diseases with a high degree genetic similarity. Still, the requirements of laborious and time-consuming of contemporary zebrafish processing assays limit the procedure in carrying out such genetic screen at high throughput. Here, a zebrafish control scheme was
more » ... tiated which includes the design and validation of a microfluidic platform to significantly increase the throughput and performance of zebrafish larvae manipulation using the concept of artificial cilia actuation. A moving wall design was integrated into this microfluidic platform first time in literature to accommodate zebrafish inside the microchannel from 1 day post-fertilization (dpf) to 6 dpf and can be further extended to 9 dpf for axial orientation control in a rotational range between 0 to 25 degrees at the minimum step of 2-degree increment in a stepwise manner. This moving wall feature was performed through the deflection of shape memory alloy wire embedded inside the microchannel controlled by the electrical waveforms with high accuracy. The zebrafish made its first splash as an ideal model for genetic studies in vertebrate development due to its favorable biological characteristics such as high fecundity, transparency, short generation interval, and external fertilization 1 . Zebrafish genetics entered the picture and gained prominence with the large-scale mutagenesis screens performed for great potentials in genetic saturation screen 2 . From the time in the 1990 s and in the following years, zebrafish genetics was nearly exclusively confined to forward genetic studies, exploiting the huge number of available mutant strains, many of which proofed to be relevant to the understanding of pathogenesis of a number of human diseases 3, 4 . In addition, compare to the human reference genome it shows that over 70% of human genes have at least one obvious zebrafish orthologue which evidences that zebrafish bears significantly genetic similarity to human 5 . Genetic studies of human disorders also benefit from the investigation of specific target genes of interest. Aside from that, National of Health has recognized zebrafish as the third animal model, and large numbers of zebrafish are available to facilitate studies related to gene functions and the identification of cellular targets of new compounds 6 . The trend in conducting zebrafish for human subjects is expected to be prospering for the decades to come. Still, the lack of a trustworthy tool to manipulate zebrafish orientation during genetic screening hinders the practical realization of the full potential in modeling human diseases with zebrafish. To-date most of the zebrafish screening and imaging or related experiments rely heavily on experienced researchers with tediously and roughly manual operation for zebrafish orientation control to visualize the region of interest. This poses a significant barrier to batch-process large quantities of zebrafish which are highly required during the drug and gene processes. On top of that, zebrafish larvae are extremely fragile and vulnerable under the subjection of external forces such as the force applied from forceps during the manual processing of zebrafish, and it may cause detrimental impact to this animal model. As a remedy, microfluidic based manipulation platforms have sparked the interest through automated zebrafish processing. Several microfluidic platforms have been demonstrated to successfully facilitate zebrafish manipulation in more automatic and robust fashions. For example, an entrapment device that is agarose-free was reported to position zebrafish in a predictable array using pipettes. Addition access
doi:10.1038/srep36385 pmid:27821862 pmcid:PMC5099576 fatcat:nez4kcj6evhovbabtq6p6qtmcm