Ready, steady, cooooooonga~

What is this?

The video depicts the formation of the so-called lateral line in a transgenic zebrafish that I took when I was a student in Tatjana Piotrowski’s lab at the Stowers Institute for Medical Research (Kansas City, MO, USA). Cells of the lateral line use collective cell migration —sort of a cellular ‘Conga’ formation— to move from the head of the animal into the trunk and deposit volcano-shaped structures called neuromasts.

Where can the lateral line be found?

Fishes (bony, such as the zebrafish; and cartilaginous, such as sharks and rays) and amphibians (such as frogs and salamanders).

How was this video taken?

This is a video of a transgenic zebrafish expressing a fluorescent protein in the lateral line Tg(clndb:lynGFP). The video was taken live using a Zeiss 780 confocal microscope.

What does the lateral line do?

The lateral line is a mechanosensory organ that aquatic animals use to orient themselves in the water using neuromasts that cover the entire body of the animal (like in the picture below). These neuromasts are the sensory unit of the lateral line due to the presence of specialized sensory cells called hair cells (that do indeed have little ‘hairs’, but we call them kinocilia and stereocilia) that respond to the water flow. This movement is translated into synaptic information and is sent to the brain, where it is used to convey positional information. The lateral line also allows fishes to display the so-called ‘schooling behavior’, a kind of collective animal behavior that is commonly seen in documentaries showing fishes moving together

Why should people care about this?

Due to the transparency, rapid development and gene conservation of zebrafish, the lateral line is an outstanding model to study two processes: collective cell migration, and hair cell regeneration.

The migrating primordia depicted in the video deploy the same molecular and cellular tools healthy and cancer cells use to migrate. Thus, studying migration of the lateral line primordia can help us understanding collective cell migration in health and disease.

One interesting property about hair cells is that they are also present in humans, but they are in the inner ear and they are used for hearing. When we age, or under some non-physiological conditions, we lose hair cells forever. Fishes, on the other hand, can regenerate their hair cells upon loss; therefore, studying how fish regenerate their hair cells may give us clues that can be used to restore hearing in humans that have lost hair cells.

How would you explain this to an 8-year-old?

During their development, fishes have little groups of cells that move all together all over the body. These cells then form garlic-bulb shaped structures that fishes use to swim, due to the presence of prickly cells called hair cells. People also have hair cells — but not all over their bodies, but inside your ears — that we use for hearing.

Where can people find more about it?

https://en.wikipedia.org/wiki/Lateral_line

“PCP and Wnt pathway components act in parallel during zebrafish mechanosensory hair cell orientation” Navajas Acedo et al. 2019

https://www.nature.com/articles/s41467-019-12005-y (in this open access publication you can find the first video of the post, plus some others related to the lateral line and its formation)

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