Sponge cell reaggregation: Cellular structure and morphogenetic potencies of multicellular aggregates

Area of Science:

• Marine Biology
• Developmental Biology
• Evolutionary Biology

Background:

• Sponges (phylum Porifera) are ancient multicellular animals offering insights into Metazoan evolution.
• Sponges exhibit high plasticity in cell differentiation and structure.
• Cell reaggregation after dissociation is a key example of sponge plasticity.

Purpose of the Study:

• To investigate the dynamics and structure of cell reaggregation in three demosponge species.
• To compare the reaggregation capabilities of Halichondria panicea, Haliclona aquaeductus, and Halisarca dujardinii.
• To understand the factors influencing successful sponge reconstruction from dissociated cells.

Main Methods:

• Mechanical dissociation of sponge tissues into cell suspensions.
• Culture of cell suspensions at 8-10°C for at least 5 days.
• Microscopic analysis (light, transmission, scanning electron microscopy) of multicellular aggregates.

Main Results:

• All three studied species exhibit common reaggregation stages: primary aggregates, early primmorphs, and primmorphs.
• Reaggregation rates vary significantly among the species.
• Only Halisarca dujardinii cells successfully reconstructed viable sponges via active cell locomotion; other species' development arrested.

Conclusions:

• Sponge species differ in their capacity for complete reconstruction from reaggregated cells.
• Cell immobility appears to be a limiting factor in the arrested development of some species.
• The inability to reconstruct may depend on life cycle stage and experimental conditions, not solely species-specific traits.