Organizer regions in marine colonial hydrozoans.
Organizers are specific tissue regions of developing organisms that provide accuracy and robustness to the body plan formation. Hydrozoan cnidarians (both solitary and colonial) require organizer regions for maintaining the regular body patterning during continuous tissue dynamics during asexual reproduction and growth. While the hypostomal organizer of the solitary Hydra has been studied relatively well, our knowledge of organizers in colonial hydrozoans remains fragmentary and incomplete. As colonial hydrozoans demonstrate an amazing diversity of morphological and life history traits, it is of special interest to investigate the organizers specific for particular ontogenetic stages and particular types of colonies. In the present study we aimed to assess the inductive capacities of several candidate organizer regions in hydroids with different colony organization. We carried out grafting experiments on colonial hydrozoans belonging to Leptothecata and Anthoathecata. We confirmed that the hypostome tip is an organizer in the colonial Anthoathecata as it is in the solitary polyp Hydra. We also found that the posterior tip of the larva is an organizer in hydroids regardless of the peculiarities of their metamorphosis mode and colony structure. We show for the first time that the shoot growing tip, which can be considered a key evolutionary novelty of Leptothecata, is an organizer region. Taken together, our data demonstrate that organizers function throughout the larval and polypoid stages in colonial hydroids.
Koltzov Institute of Developmental Biology, Russian Academy of Sciences, ul. Vavilova 26, 119334 Moscow, Russia.
Tatiana
T
Mayorova
Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory 1/12, 119234 Moscow, Russia.
Igor
I
Kosevich
Cancer Research Center, The University of Chicago, 929 East 57th Street, Chicago, IL 60637, USA.
Nickolai
N
Dulin
Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory 1/12, 119234 Moscow, Russia.
Elizaveta
E
Savina
Faculty of Biology, Lomonosov Moscow State University, Leninskie Gory 1/12, 119234 Moscow, Russia. Electronic address: yulia_kraus@hydrozoa.org.
Yulia
Y
Kraus
D000818:Animals; D059001:Aquatic Organisms / Q000166:cytology / Q000254:growth & development*; D019521:Body Patterning / Q000502:physiology*; D037402:Hydrozoa / Q000166:cytology / Q000254:growth & development*; D007814:Larva
Cnidaria; Colonial hydrozoans; Inductive capacity; Organizer regions; Transplantation experiments