The modes of action of juvenile hormones: some questions we ought to ask

This paper argues that the current dogma that juvenile hormones are structu rally unique and constitute a family of derivatives of farnesoic acid which are produced by the corpus allatum (CA), secreted into the hemolymph, freq uently transported by binding proteins, enter cells by diffusion across the cell membrane and there the products of the CA interact in some way with t he genome, probably via nuclear receptors of the steroid superfamily, may n ot be tenable. It does so by examining the following questions. How many JH s are there? Are there other sources of JH in insects? Are there non-farnes oids with JH activity in insects? How does JH get into cells? Is the produc t of the CA the effective hormone? How many modes of action are there? How many receptors are there? (C) 2000 Elsevier Science Ltd. All rights reserve d.