Limits...
Transdifferentiation is a driving force of regeneration in Halisarca dujardini (Demospongiae, Porifera).

Borisenko IE, Adamska M, Tokina DB, Ereskovsky AV - PeerJ (2015)

Bottom Line: Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl.After the blastema is formed, MET becomes the principal mechanism of regeneration.Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Embryology, Faculty of Biology, Saint-Petersburg State University , Saint-Petersburg , Russia.

ABSTRACT
The ability to regenerate is widespread in the animal kingdom, but the regenerative capacities and mechanisms vary widely. To understand the evolutionary history of the diverse regeneration mechanisms, the regeneration processes must be studied in early-evolved metazoans in addition to the traditional bilaterian and cnidarian models. For this purpose, we have combined several microscopy techniques to study mechanisms of regeneration in the demosponge Halisarca dujardini. The objectives of this work are to detect the cells and morphogenetic processes involved in Halisarca regeneration. We show that in Halisarca there are three main sources of the new exopinacoderm during regeneration: choanocytes, archaeocytes and (rarely) endopinacocytes. Here we show that epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) occur during Halisarca regeneration. EMT is the principal mechanism during the first stages of regeneration, soon after the injury. Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl. Together with archaeocytes, these cells form an undifferentiated cell mass beneath of wound, which we refer to as a blastema. After the blastema is formed, MET becomes the principal mechanism of regeneration. Altogether, we demonstrate that regeneration in demosponges involves a variety of processes utilized during regeneration in other animals (e.g., cell migration, dedifferentiation, blastema formation) and points to the particular importance of transdifferentiation in this process. Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

No MeSH data available.


Related in: MedlinePlus

Simplified diagrams of histological organization of Halisarca dujardini: sponge structure and cell composition before injury (A) Dotted line shows the area of excision.1—ectosome; 2—choanosome.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4556153&req=5

fig-2: Simplified diagrams of histological organization of Halisarca dujardini: sponge structure and cell composition before injury (A) Dotted line shows the area of excision.1—ectosome; 2—choanosome.

Mentions: Halisarca dujardini is a predominantly shallow water, encrusting sponge growing up to 0.5–4 cm in diameter with thickness of 0.5–12 mm (Fig. 1A). Inorganic and organic skeletons are absent, and the surface is smooth. The body is composed of the peripheral ectosome and the internal choanosome (Figs. 1B and 1C; see also cartoon representation on Fig. 2). The ectosomal region is up to 27 µm thick and consists of three layers: (1) external parts of T-shaped exopinacocytes (Fig. 1D) which are covered an acellular mucous cuticle; (2) layer containing collagen fibrils and rare spherulous cells; and (3) the inner layer, consisting of condensed collagen fibrils and the cell bodies of exopinacocytes. The choanosome (Fig. 1B) makes up the greatest volume of the sponge body and is composed of choanocyte chambers (built of choanocytes the only cell type which is flagellated, Fig. 1C), aquiferous canals (built of endopinacocytes, Fig. 1E) and the mesohyl. Populations of free cells in the mesohyl of H. dujardini include: archaeocytes, lophocytes, spherulous cells, granular cells, microgranular cells, and vacuolar cells (Ereskovsky et al., 2011) (Figs. 1E–1H). Neither specialized cell junctions, nor basement membranes could be identified in association with any of the cell types.


Transdifferentiation is a driving force of regeneration in Halisarca dujardini (Demospongiae, Porifera).

Borisenko IE, Adamska M, Tokina DB, Ereskovsky AV - PeerJ (2015)

Simplified diagrams of histological organization of Halisarca dujardini: sponge structure and cell composition before injury (A) Dotted line shows the area of excision.1—ectosome; 2—choanosome.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4556153&req=5

fig-2: Simplified diagrams of histological organization of Halisarca dujardini: sponge structure and cell composition before injury (A) Dotted line shows the area of excision.1—ectosome; 2—choanosome.
Mentions: Halisarca dujardini is a predominantly shallow water, encrusting sponge growing up to 0.5–4 cm in diameter with thickness of 0.5–12 mm (Fig. 1A). Inorganic and organic skeletons are absent, and the surface is smooth. The body is composed of the peripheral ectosome and the internal choanosome (Figs. 1B and 1C; see also cartoon representation on Fig. 2). The ectosomal region is up to 27 µm thick and consists of three layers: (1) external parts of T-shaped exopinacocytes (Fig. 1D) which are covered an acellular mucous cuticle; (2) layer containing collagen fibrils and rare spherulous cells; and (3) the inner layer, consisting of condensed collagen fibrils and the cell bodies of exopinacocytes. The choanosome (Fig. 1B) makes up the greatest volume of the sponge body and is composed of choanocyte chambers (built of choanocytes the only cell type which is flagellated, Fig. 1C), aquiferous canals (built of endopinacocytes, Fig. 1E) and the mesohyl. Populations of free cells in the mesohyl of H. dujardini include: archaeocytes, lophocytes, spherulous cells, granular cells, microgranular cells, and vacuolar cells (Ereskovsky et al., 2011) (Figs. 1E–1H). Neither specialized cell junctions, nor basement membranes could be identified in association with any of the cell types.

Bottom Line: Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl.After the blastema is formed, MET becomes the principal mechanism of regeneration.Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Embryology, Faculty of Biology, Saint-Petersburg State University , Saint-Petersburg , Russia.

ABSTRACT
The ability to regenerate is widespread in the animal kingdom, but the regenerative capacities and mechanisms vary widely. To understand the evolutionary history of the diverse regeneration mechanisms, the regeneration processes must be studied in early-evolved metazoans in addition to the traditional bilaterian and cnidarian models. For this purpose, we have combined several microscopy techniques to study mechanisms of regeneration in the demosponge Halisarca dujardini. The objectives of this work are to detect the cells and morphogenetic processes involved in Halisarca regeneration. We show that in Halisarca there are three main sources of the new exopinacoderm during regeneration: choanocytes, archaeocytes and (rarely) endopinacocytes. Here we show that epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) occur during Halisarca regeneration. EMT is the principal mechanism during the first stages of regeneration, soon after the injury. Epithelial cells from damaged and adjacent intact choanocyte chambers and aquiferous canals assume mesenchymal phenotype and migrate into the mesohyl. Together with archaeocytes, these cells form an undifferentiated cell mass beneath of wound, which we refer to as a blastema. After the blastema is formed, MET becomes the principal mechanism of regeneration. Altogether, we demonstrate that regeneration in demosponges involves a variety of processes utilized during regeneration in other animals (e.g., cell migration, dedifferentiation, blastema formation) and points to the particular importance of transdifferentiation in this process. Further studies will be needed to uncover the molecular mechanisms governing regeneration in sponges.

No MeSH data available.


Related in: MedlinePlus