# Effect of Retinal on Dictyostelium Cells During Development

## TL;DR

Retinal affects Dictyostelium cells by altering their shape and signaling during development, even though they lack known retinal-binding proteins.

## Contribution

The study reveals a novel effect of retinal on Dictyostelium cells' cytoskeleton and signaling pathways.

## Key findings

- Adding all-trans-retinal caused Dictyostelium cells to retract pseudopodia and become rounded.
- Low concentrations of retinal increased cAMP signaling frequency during development.
- Retinal's effects suggest an unknown signaling pathway involving the cytoskeleton in Dictyostelium.

## Abstract

Retinal plays a key role in light absorption across prokaryotes and eukaryotes, both in rhodopsin and bacteriorhodopsin systems. The multicellular social amoeba Dictyostelium discoideum exhibits positive phototaxis. However, retinal binding proteins such as rhodopsin have not been found in the genome of Dictyostelium cells. Herein, we microscopically examined the effects of retinal on Dictyostelium cells. On adding all‐trans‐retinal to the medium, Dictyostelium cells retracted their pseudopodia and became rounded. This was unique to retinal among the tested vitamin A variants. Addition of all‐trans‐retinal at low concentrations did not cause cell rounding. However, it increased the frequency of cAMP signaling triggered during cell development. Results indicate that retinal acts on an unknown signaling pathway involving the cytoskeleton in Dictyostelium cells.

When all‐trans‐retinal was added to the medium, Dictyostelium cells retracted their pseudopodia and became rounded; however, this rounding was not observed at low concentrations. Instead, low concentrations of all‐trans‐retinal increased the frequency of cAMP signaling during cell development.