Raman microscopy as a tool to study changes in chemical composition upon structural differentiation of Ambystoma embryo.

Ambystoma mexicanum is often used in regeneration studies because it reaches sexual maturity as aquatic larvae within 360 hours, and it can regenerate its appendages. In developing a spectroscopic approach for regeneration studies, in this contribution, we show that Raman confocal microscopy can be used as a diagnostic tool to describe the chemical composition of axolotl embryonal tissues at different stages of development. Experimental observations, supported by quantum chemistry studies on molecules reported or considered to be present in the tissues of the living organism, show that in the early stages of development (Harrison stage 11), there is only limited spatial differentiation of phospholipid, carotenoids and proteins, though, in the later stages of development (Harrison stage 33), differentiation of chemical species is possible and can be related to the development of tissues and organs. In particular, we were able to assess the oxidation state of proteins, their packing and the role of pigments in protection of cellular tissues. We believe the results presented here will be helpful for those involved in planning experiments to combine biochemistry, emission and Raman microscopy to research axolotl tissue regeneration mechanisms.