MS

Model organisms · Imaging

Why larval zebrafish?

They let me image activity across much of a vertebrate brain while controlling sensory feedback and measuring behavior.

© Marc Duque Ramírez
Larval zebrafish in the light-sheet microscope, viewed from the sideMS

Why I use them

Keep mechanism, activity, and behavior in the same experiment.

Larval zebrafish are small and optically accessible, but they still have a vertebrate nervous system and a broad range of measurable behaviors.

In one preparation I can alter a receptor or cell population, observe the resulting activity across the brain, and measure what the animal does next.

Light-sheet imaging

Follow distributed activity at cellular resolution.

Thin optical sections are collected rapidly through the transparent larval brain. I use the resulting volumes to compare activity across cells and regions during behavior and molecular perturbation.

A custom segmentation algorithm identifies individual cells in these datasets. Each colored segment in the videos below represents one cell.

Image volume · Custom cell segmentation

© Marc Duque Ramírez
Light-sheet z-stack through cellular planesLS.1
© Marc Duque Ramírez
Individual cells identified by the custom segmentation algorithmLS.2
© Marc Duque Ramírez
Cell segmentation overlaid on the light-sheet volumeLS.3

Future extension · Adult fish

Carry optical access into adulthood.

Small, paedomorphic fish may make mature behavior accessible without giving up the optical advantages of larvae. Danionella cerebrum is already an emerging model for imaging the adult brain; Paedocypris progenetica is a more exploratory possibility whose experimental toolkit would need to be developed.

This is a future direction rather than a current experimental program.

Live adult female Danionella cerebrum showing its transparent body and visible brain© Ralf Britz
Adult Danionella cerebrumA1

Image: Ralf Britz / Senckenberg Natural History Collections Dresden, via the Natural History Museum of Bern. Scientific context: Britz, Conway & Rüber (2021).

Two transparent adult Paedocypris progenetica resting among aquatic plantsSource: Titan · University of Oslo
Adult Paedocypris progeneticaA2

Image: Titan, University of Oslo. Scientific context: Kottelat et al. (2006).

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