An optically accessible adult vertebrate model is needed to study dynamic cellular processes in vivo. We aim to develop
and characterize Danionella cerebrum, a teleost related to zebrafish that remains transparent into adulthood, for studying
immune-related biological processes and their impact on disease progression in multiple organs. A transparent adult model
is particularly important for live imaging studies of immune related processes due to the dynamic and complex nature of
immune cell heterogeneity and plasticity, the involvement of infiltrating immune cells during disease progression, as well
as confounding factors related to aging. D. cerebrum, previously named as D. translucida, was first described by the
Judkewitz group in 2018 for brain-related studies. This genetically tractable model is small, adults reach a length of
approximately 12 mm in length, and is optical transparency even into adulthood. Established transgenesis and genome
editing methods used in zebrafish have showed to be effective in D. cerebrum. These characteristics make D. cerebrum an
attractive model for noninvasive in vivo visualization of dynamic and complex cellular events in a physiologically relevant
setting. This study aims to build the infrastructure required to use D. cerebrum as a systems biology model organism for
studying immune-related biological processes and their impact on disease progression. Our proof of principle experiments
have successfully generated transgenic lines with fluorescently labelled innate immune cells such as neutrophils and
macrophages, and the endothelial cells of the vasculature. We propose to expand our collection of transgenic D. cerebrum
lines by fluorescently labeling multiple organs such as the brain, heart, liver, and kidney. In combination, these transgenic
lines will allow us to visualize the complex interplay between immune cells and various organs throughout development,
injury and disease. We will also develop a macrophage/microglia fluorescent activity reporter line which will allow us to
observe and measure dynamic state changes displayed by immune cells in a physiologically relevant environment using
non-invasive in vivo imaging. To facilitate our studies, we will develop methods and equipment for longitudinal live
imaging of awake adult D. cerebrum. Immune cell functions play important roles in wound healing and regeneration.
Zebrafish are known to have great regeneration capacity in different organs, however, it is not known if D. cerebrum can
regenerate. Our preliminary work suggests that adult D. cerebrum can regenerate its tail fin but this regenerative capacity
decreased in aged animal. Our proposed study will investigate if D. cerebrum regenerates its central nervous system during
different developmental stages, its corresponding immune cell response and the transcriptomic changes that accompany
these events. We will also perform interspecies comparative analysis using available data from zebrafish regeneration
studies to explore key players in modulating regeneration capacity. This proposal describes strategies that will build the
infrastructure required to use D. cerebrum for immunology related studies in vivo. The tools, techniques and knowledge
built for the D. cerebrum immune model will provide an important springboard for carrying out future focused analyses on
immune-related processes that include, but by no means are limited to, inflammaging, wound healing/regeneration, cancer,
and neurodegenerative diseases.
