S7-10 Wed Jan 6 17:00 – 17:30 Within-cell cycle of endolysosome-related pigment organelles in crab spiders leads to reversible color changes Figon, F*; Hurbain, I; Heiligenstein, X; Trépout, S; Medjoubi, K; Somogyi, A; Delevoye, C; Raposo, G; Casas, J; IRBI, UMR 7261, CNRS – Université de Tours, Tours, France; Institut Curie, UMR 144, CNRS – Université PSL, Paris, France; CryoCapCell, 80, rue du Général Leclerc, Kremlin-Bicêtre, France; Institut Curie, Inserm U1196, UMR 9187, CNRS – Université Paris-Saclay, Orsay, France ; Synchrotron SOLEIL, Saint-Aubin, Gif sur Yvette, France; Synchrotron SOLEIL, Saint-Aubin, Gif sur Yvette, France; Institut Curie, UMR 144, CNRS – Université PSL, Paris, France; Institut Curie, UMR 144, CNRS – Université PSL, Paris, France; IRBI, UMR 7261, CNRS – Université de Tours, Tours, France firstname.lastname@example.org https://florent-figon.cygale.net/
Reversible color change is a fascinating ability of animals. Pigment-based mechanisms enabling morphological color changes are widespread in vertebrates and invertebrates. Yet, how pigment cells accommodate both formation and degradation of pigments for reversibility is not understood. In this presentation, we show how crab spiders alternate between yellowing and bleaching phases through the intracellular processing of pigment organelles. By performing electron and Synchrotron-based microscopies, we obtained ultrastructural and chemical evidence that pigment organelles are endolysosome-related organelles (ELRO), a family of organelles comprising vertebrate melanosomes. Our results suggest that yellowing of crab spiders arises from the formation of intraluminal fibrils and the deposition of metals within pigment ELROs. In contrast, bleaching appears to proceed via lysosomal degradation of intraluminal content and metal removal. Some of these intracellular processes mirror the biogenesis of other pigment ELROs, identifying endolysosomal organelles as a universal pigmentation platform. Overall, crab spiders offer a striking example of how the endolysosomal system has been fully functionalized, from anabolism to catabolism and recycling, to allow reversible morphological color changes.