Science 16 January 2015:
Vol. 347 no. 6219 pp. 220-221
In Depth

All in the (bigger) family

Elizabeth Pennisi | 1 Comments

Revised arthropod tree marries crustacean and insect fields.

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The 2015 Society for Integrative and Comparative Biology (SICB) presenters may not recognize how much progress has been made since the 2013 ecological epigenetics symposium. For example, since then authors claimed "...ctenophore neural systems, and possibly muscle specification, evolved independently from those in other animals."

Six months later, other authors traced signaling factors found in vertebrates to the origin of nerve cell centralization via the diffuse nerve net of animals like the sea anemone. That fact suggests ecological variation is linked to ecological adaptations in morphological and behavioral phenotypes via signaling protein concentrations that differentiate various cell types in body axes and the central nervous system.

Links across species from the epigenetic landscape to the physical landscape of DNA in organized genomes appear to have their origins in the conserved molecular mechanisms of RNA-directed DNA methylation and RNA-mediated protein folding. Two weeks after the publication that refuted ideas about independently evolved neural systems or muscle specification -- and perhaps refuted the independent evolution of anything else, SICB presenters linked crustaceans to insects.

Apparently, they've learned that the same set of microRNAs controls expression of the genes for rate-limiting enzymes that control the hormone production of different hormones in insects and crustaceans.

Why were they left with any questions about how crustaceans and insects could all be part of one big family? They linked RNA-mediated cell type differentiation to what we described in our section on molecular epigenetics in our 1996 Hormones and Behavior review. From Fertilization to Adult Sexual Behavior

Submitted on Mon, 01/19/2015 - 11:51