ИСТИНА

Despite overall simple body organization sponges possess unique features in their organization not found in other multicellular animals. The plasticity of sponge body both at anatomical and cellular levels is one of such features. Virtually all cells in sponge body constantly moving and the majority of them have ability for transdifferentiation. Continuous tissue reorganization allows adjusting the aquiferous system to certain hydrodynamic conditions, reconstructing somatic tissue after degradation during sexual reproduction, asexual reproduction and movement. Plasticity of sponge tissues and cells is the most evident during the process of sponge cell reaggregation after tissue dissociation. In the course of reaggregation multicellular aggregates differing in structure form, ending in certain cases in the reconstruction of intact sponge. We studied cell reaggregation of three demosponge (Halisarca dujardinii, Halichondria panicea, Haliclona aquaeductus) and one calcarean (Leucosolenia complicata) species. Cell reaggregation of H. dujardinii and H. panicea was studied at the different stages of sexual reproduction cycles of these species. In general the cell reaggregation of all studied species have the same common pattern. During this process multicellular aggregates pass the same developmental stages: 1) primary multicellular aggregates, 2) early primmorphs, 3) primmorphs, 4) progressively developing primmorphs, 5) reconstructed sponge. Nevertheless, each species shows some species-specific features of cell reaggregation which appear as differences in rate and final stage of the process. Halisarca dujardinii cell reaggregation proceeds much quicker comparing to other species and always ends with the reconstruction of intact sponge. Cell reaggregation of other species ends at early primmorph or primmorph stages. Studies of H. dujardinii and H. panicea cell reaggregation at the different stages of sexual reproduction cycles shows intraspecific variations of the process. In both species, cell reaggregation is most successful in cultures obtained from non-reproducing individuals. After beginning of sexual reproduction and appearance of gametes and/or embryos in the sponge tissues the rate of cell reaggregation decrease and the development of multicellular aggregates stops at earlier stages. The probable reason is an alteration of the physiological condition of somatic tissue of sponge at the different stages of sexual reproduction cycle. Collected data allow to propose the upgraded general scheme of sponge cell reaggregation considering both inter- and intraspecific variation of this process. The study was supported by the Russian Foundation of Basic Research (project no. 16-34-00145). How to cite: Lavrov AI and Kosevich IA. Sponge cell reaggregation: inter- and intraspecific variations [version 1; not peer reviewed]. F1000Research 2017, 6:1035 (slides) (doi: 10.7490/f1000research.1114338.1)