A little help from a friend
The Hawaiian sea slug
Elysia rufescens
grazes on an alga called
Bryopsis
sp. The alga defends itself from predators using peptide toxins decorated with fatty acids, called kahalalides. Zan
et al.
wondered if a third party was involved in toxin production (see the Perspective by Mascuch and Kubanek). Within the alga, a species of bacterium with a very reduced genome was discovered to be a factory for the nonribosomal assembly of a family of kahalalides. The authors elucidated the pathways for generating this chemical diversity. It seems that the sea slug not only tolerates the toxins but, to protect itself from being eaten by fish, grazes on the alga to accumulate kahalalide.
Science
, this issue p.
eaaw6732
; see also p.
1034