Origin of Neurogenic Electrocytes (ONE): genomic and regulatory bases of the origin of a novel cell type in vertebrates

All animals have specialized cells that can generate small electric currents, such as neurons or muscle cells. However, the ability to generate external electric fields is restricted to only few teleost and elasmobranch species.

This function evolved independently at least six times, generating different specialized electric organs composed of cells called electrocytes that generate these electric fields. In most species, electrocytes have convergently evolved from muscle cells.

Nonetheless, in Apteronoidae, a small tropical clade that shares a common ancestor with other fish with a myogenic electric organ, electrocytes have evolved de novo from spinal cord motor neuron precursors.

These neurogenic electrocytes create the electric organ by packing axons with unique morphological properties: no pre-synaptic terminal, U-shape with a 5-fold changing diameter and unique myelination pattern.

However, nothing is known about the molecular changes that underlie these striking evolutionary novelties, to a large extent due to the difficulty to access the somas of electrocytes, which are intermingled within other spinal cord cells.

The goal of ONE is to elucidate the genomic and regulatory bases of the origin of the neurogenic electrocytes in Apteronoidae.

This will be possible thanks to the use of cutting-edge single-cell multi-omics technologies, which will allow us to investigate this cell type at the transcriptomic and regulatory levels for the first time (Aim 1).

I will then use comparative approaches with close fish relatives and between neurogenic and myogenic electrocytes to identify unique and convergent evolutionary genomic patterns (Aim 2).

Altogether, ONE will positively impact neuroscience and evolutionary research, revealing new mechanisms of novel cell-type evolution.

Moreover, we will discover new genetic variants that might be applied to biotechnology and biomedicine and that will further help to raise awareness of the importance of conserving Biodiversity.