title: Brefeldin A or monensin inhibits the 3D organizer in gastropod, polyplacophoran, and scaphopod molluscs.
abstract: In molluscs, the 3D vegetal blastomere acts as a developmental signaling center, or organizer, and is required to establish bilateral symmetry in the embryo. 3D is similar to organizing centers in other metazoans, but detailed comparisons are difficult, in part because its organizing function is poorly understood. To elucidate 3D function in a standardized fashion, we used monensin and brefeldin A (BFA) to rapidly and reversibly interfere with protein processing and secretion, thereby inhibiting the signaling interactions that underlie its specification and patterning. In the gastropods, Patella vulgata and Lymnaea stagnalis, the polyplacophoran, Mopalia muscosa, and the scaphopod, Antalis entalis, treatments initiated before the organizer-dependent onset of bilateral cleavage resulted in radialization of subsequent development. In radialized P. vulgata, L. stagnalis, and M. muscosa, organizer specification was blocked, and embryos failed to make the transition to bilateral cleavage. In all four species, the subsequent body plan was radially symmetric and was similarly organized about a novel aboral-oral axis. Our results demonstrate that brefeldin A (BFA) and monensin can be used to inhibit 3D's organizing function in a comparative fashion and that, at least in M. muscosa, the organizer-dependent developmental architecture of the embryo predicts subsequent patterns of morphogenetic movements in gastrulation and, ultimately, the layout of the adult body plan.
authors.affiliation: Department of Developmental Biology, University of Utrecht, Padualaan 8, 3584 CH, Utrecht, The Netherlands. eegonzales@berkeley.edu
authors.forename: Eric E
authors.initials: EE
authors.lastname: Gonzales
authors.forename: Maurijn
authors.initials: M
authors.lastname: van der Zee
authors.forename: Wim J A G
authors.initials: WJ
authors.lastname: Dictus
authors.forename: Jo
authors.initials: J
authors.lastname: van den Biggelaar
mesh_terms: D000818:Animals; D019521:Body Patterning / Q000187:drug effects; D020126:Brefeldin A / Q000494:pharmacology*; D049851:Gastropoda / Q000187:drug effects / Q000196:embryology; D008195:Lymnaea / Q000187:drug effects / Q000196:embryology; D008855:Microscopy, Electron, Scanning; D008974:Mollusca / Q000145:classification / Q000187:drug effects* / Q000196:embryology* / Q000502:physiology; D008985:Monensin / Q000494:pharmacology*; D020897:Organizers, Embryonic / Q000187:drug effects* / Q000196:embryology; D049916:Polyplacophora / Q000187:drug effects / Q000196:embryology; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D011500:Protein Synthesis Inhibitors; D020126:Brefeldin A; D008985:Monensin