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© Leo Otsuki

The axolotl brain. Credit: IMP

An atlas of the axolotl brain

Axolotls are experts when it comes down to regeneration. Even after brain injury they are able to regenerate damaged tissue. Nevertheless, until now the salamander brain was largely unexplored.

In a study published in Science, an international research team with scientists from the labs of Elly Tanaka at the IMP and Barbara Treutlein at ETH Zurich constructed in a tremendous effort a unique atlas of the axolotl forebrain. For the first time, the researchers characterised and analysed the different cell types of the salamander forebrain in a developmental and regenerative context using single-nucleus and single-cell genomic profiling.

Healing of broken bones - What can we learn from the axolotl?

The axolotl is known for its highly regenerative capacity. But how does the master of regeneration copes with bone fractions?

Anastasia Polikarpova, a Postdoc from Elly Tanaka’s lab, in collaboration with researchers from the labs of Katharina Schmidt-Bleek at Charité-Universitätsmedizin Berlin have developed a fracture model in the axolotl. The model allows the scientists to compare bone fracture healing to the process of bone regeneration after an amputation.

Read here what we can learn from the axolotl when it brakes a bone.

Micro-CT scans and tissue sections of the axolotl leg after amputation (left), after a fracture with a titanium plate (middle), and after a fracture without a plate (right), after three weeks (a-c) and three months (d-f). The titanium plate helps align the bones as they regrow
Blastema with Fgf8 stained in red, Axin2 in white, and cell nuclei in blue. Credit: Giacomo Glotzer

Unravelling the regeneration puzzle - one step closer

Giacomo Glotzer, an undergraduate student from Yale University and Pietro Tardivo, a PhD student from Elly’s lab, report new insights into the regulation of the Fibroblast Growth factor (Fgf) 8 during axolotl limb development and regeneration in their study recently published in eLife.

Giacomo spent a year in Elly’s lab, supervised by Pietro, to investigate the upstream regulators of Fgf8 with its unique mesenchymal expression in the axolotl. If you want to find out more about the project read the interview with Giacomo here.

 

Ready, set, go: stem cells synchronise to repair the axolotl spinal cord

Leo Otsuki in Elly Tanakas lab teamed up with Emanuel Cura Costa in Osvaldo Chara’s lab (Argentina’s National Scientific and Technical Research Council (CONICET)) to create a mathematical model recapitulating early axolotl spinal cord regeneration and to test its predictions using new transgenic and imaging technologies. Their findings, published in eLife, show that neural stem cells accelerate their cell cycles in a highly synchronised manner, with the activation spreading along the spinal cord.

Spinal cord regeneration visualized using new transgenic FUCCI axolotls. Magenta stem cells are activating synchronously in response to a spinal cord amputation four days prior towards the right of the image. Green cells are resting cells. Credit: Leo Otsuki
The African clawed frog (Xenopus laevis) and the axolotl (Ambystoma mexicanum). Credit: IMP

Limb regeneration - What do axolotls have that frogs don't?

An international team of scientists led by the labs of Elly Tanaka at the Research Institute of Molecular Pathology and Barbara Treutlein at ETH Zurich zoomed in on the regeneration abilities of axolotls. The study, published in Developmental Cell gives away the cellular and molecular bases that lead to the incomplete limb regeneration in African clawed frogs (Xenopus laevis). The researchers compared the regeneration process in frogs and axolotls (Ambystoma mexicanum) using genetic fate-mapping and state-of-the-art single cell RNA-seq technologies. Their findings show that frog cells have cell intrinsic barriers to become fully de-differentiated to a limb bud-like progenitor state, which correlates with the regeneration outcome. This work opens the door to further disentangling the (epi)genetic networks underlying the secret of limb regeneration. 

Giant lungfish genome reveals how vertebrates conquered land

For the first time, a team of international researchers with Elly Tanaka sequenced and fully assembled the genome of the Australian lungfish. This study uncovers the largest animal genome known to date and gives away some of the secrets on how vertebrates conquered land.

Australian Lungfish (Neoceratodus forsteri)

Introducing www.axolotl-omics.org – an integrated -omics data portal for the axolotl research community

Sergej Nowoshilow & Elly M.Tanaka, Experimental Cell Research, Volume 394, Issue 1, 1 September 2020

MERTK-Dependent Ensheathment of Photoreceptor Outer Segments by Human Pluripotent Stem Cell-Derived Retinal Pigment Epithelium

New study from Seba Almedawar published in Stem Cell Reports (March 2020).

Almedawar S, Vafia K, Schreiter S, Neumann K, Khattak S, Kurth T, Ader M, Karl MO, Tsang SH, Tanaka EM. MERTK-Dependent Ensheathment of Photoreceptor Outer Segments by Human Pluripotent Stem Cell-Derived Retinal Pigment Epithelium. Stem Cell Reports. 2020 Mar 10;14(3):374-389. doi: 10.1016/j.stemcr.2020.02.004.
Elly Tanaka

Elly Tanaka receives the FEBS | EMBO Women in Science Award 2020

Elly receives the award for her pioneering work developing a molecular understanding of limb and spinal cord regeneration. She developed new methods to study the phenomenon, which had previously been considered too complex to understand at a cellular level. Through her work inside and outside the lab, Elly has galvanized regeneration research worldwide.