Axolotls can regenerate their brains

The Absolutel (Ambystoma mexicanum) is an salamander famous for its ability to Regenerates the spinal cord, heart and limbs. These amphibians too Easily make new neurons during their lives. In 1964, researchers noticed that adult sea urchins can regenerate parts of their brains, even if a large partition is removed completely. But one study found that Absolutl brain regeneration It has a limited ability to rebuild the original tissue structure.

So, how well is Absolutil able to regenerate their brains after an injury?

K A researcher studies regeneration at the cellular levelMe and my colleagues at Treutlein . Laboratory In ETH Zurich and tanaka lab At the Institute of Molecular Pathology in Vienna, he wondered if sea urchins were able to regenerate all the different types of cells in their brain, including the connections that connect one brain region to another. in our area A recently published studywe created an atlas of cells that are part of the absolutial brain, highlighting the way the brain regenerates and develops across species.

Why do we look at cells?

Different cell types It has different functions. They are able to specialize in certain roles because they each express different genes. Understanding the types of cells in the brain and what they do helps clarify the overall picture of how the brain works. It also allows researchers to make comparisons across evolution and try to find biological trends across species.

One way to understand which cells express genes is to use a technique called single-cell RNA sequencing (sgRNA sequencing). This tool allows researchers to count the number of active genes within each cell in a given sample. This provides a “snapshot” of the activities each cell was doing when it was collected.

This tool has been useful in understanding the types of cells found in the brains of animals. Scientists used scRNA-seq in fishAnd the reptilesAnd the mice even Humans. But one key piece of the brain evolution puzzle is missing: amphibians.

Mapping the Absolut Brain

Our team decided to focus on the brain from Epsolute. In humans, the diencephalon is the largest division of the brain and contains a region called the neocortex, which plays a major role in animal behavior and cognition. During the last development, the neocortex was Widely grown in size Compared to other brain regions. Likewise, the types of cells that make up the total brain have very diverse And it grew in complexity over time, making this area an interesting area to study.

Subscribe to get unexpected, surprising and touching stories delivered to your inbox every Thursday

We used scRNA-seq to identify the different types of cells that make up the axolotl telencephalon, including different types of nervous cells And the progenitor cells, or cells that can divide more of themselves or transform into other cell types. We determined which genes are active and when Progenitor cells become neuronsThey found that many of them pass through a type of intermediate cell called neurons — previously not known to exist in sea urchins — before becoming mature neurons.

We then put the regeneration of the absolutil to the test by removing a single section of the focal brain. using a Specialized method of sequencing our sugar, we were able to capture and sequence all new cells at different stages of regeneration, from 1 to 12 weeks after infection. In the end, we found that all types of cells removed were fully restored.

We observed that brain regeneration occurs in three main stages. The first stage begins with a rapid increase in the number of progenitor cells, and a small part of these cells activates the wound healing process. In the second stage, the progenitor cells begin to differentiate into neuroblasts. Finally, in the third stage, neuroblasts differentiate into the same types of neurons that were originally lost.

Surprisingly enough, we also noticed that the lump neural connections Between the area removed and other areas of the brain have been reconnected. This regeneration indicates that the regenerated area has also regained its original function.

Amphibians and human brains

Adding amphibians to the evolutionary puzzle allows researchers to infer how the brain and its cell types have changed over time, as well as the mechanisms behind regeneration.

When we compared our Absolutl data with other species, we found that cells in their diencephalon show strong similarities to mammals. hippocampusthe area of ​​the brain involved in memory formation, and olfactory cortexAn area of ​​the brain involved in the sense of smell. We even found some similarities in one type of absolutial cell with the neocortex, an area of ​​the brain known for cognition, thought and spatial reasoning in humans. These similarities suggest that these brain regions may be evolutionarily conserved, or remain comparable over the course of evolution, and that the neocortex of mammals may have a distant brain progenitor cell type of amphibians.

While our study sheds light on the brain regeneration process, including the genes involved and how cells eventually become neurons, we still don’t know what. external signals start this process. Furthermore, we don’t know if the processes we identified are still available to later evolved animals, such as mice or humans.

But we don’t solve the puzzle of brain evolution alone. The Touches Lab at Columbia University to explore the diversity of cell types in Another type of salamander, Pleurodeles Waltzwhile Fei’s laboratory at the Guangdong Academy of Medical Sciences in China and life sciences company collaborators BGI Find out what types of cells are spatially arranged in the forebrain absolut.

Identification of all cell types in the Absolut brain also helps pave the way for innovative research in regenerative medicine. They have the brains of mice and humans She has greatly lost her ability To repair or renew itself. Medical Interventions For severe brain injuries, he is currently focused on drug and stem cell therapies to promote or enhance repair. Examining the genes and cell types that allow sea urchins to achieve near-perfect regeneration may be the key to improving treatments for severe injuries and unleashing their regeneration potential in humans.

This article has been republished from Conversation Under a Creative Commons License. Read the original article.