ON THE ABSENCE OF LIPOPOLYSACCHARIDES IN THE ENDOCELLULAR SYMBIONTS OF COCKROACHES AND ITS EVOLUTIONARY IMPLICATIONS

The endocellular symbionts of cockroaches, closely related to the flav obacteria-bacterioides, are essential to their survival. Attempts to i solate and to characterize the lipopolysaccharides in the symbionts of Periplaneta americana - and quantitatively less reliable ones for Bla ttella germanica - failed to detect any of their characteristic compon ents, as well as any of the endotoxicity usually associated with this macromolecule. Together with analogous results on other flavobacteria- bacteroids, and very different ones in other Gram-negative symbioses, this finding may help to address more precisely problems on the coevol ution of animals and Gram-negatives.