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Cell kinetics during regeneration in the sponge Halisarca caerulea: how local is the response to tissue damage?

Alexander BE, Achlatis M, Osinga R, van der Geest HG, Cleutjens JP, Schutte B, de Goeij JM - PeerJ (2015)

Bottom Line: We demonstrate that during early regeneration, the growth fraction of the choanocytes (i.e., the percentage of proliferative cells) adjacent to the wound is reduced (7.0 ± 2.5%) compared to steady-state, undamaged tissue (46.6 ± 2.6%), while the length of the cell cycle remained short (5.6 ± 3.4 h).There was no difference in the number of proliferative mesohyl cells in regenerative sponges compared to steady-state sponges.The efficient allocation of limited resources to these life-history traits has enabled the ecological success and diversification of sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Aquatic Ecology and Ecotoxicology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam , Amsterdam , The Netherlands ; Porifarma B.V. , Ede , The Netherlands.

ABSTRACT
Sponges have a remarkable capacity to rapidly regenerate in response to wound infliction. In addition, sponges rapidly renew their filter systems (choanocytes) to maintain a healthy population of cells. This study describes the cell kinetics of choanocytes in the encrusting reef sponge Halisarca caerulea during early regeneration (0-8 h) following experimental wound infliction. Subsequently, we investigated the spatial relationship between regeneration and cell proliferation over a six-day period directly adjacent to the wound, 1 cm, and 3 cm from the wound. Cell proliferation was determined by the incorporation of 5-bromo-2'-deoxyuridine (BrdU). We demonstrate that during early regeneration, the growth fraction of the choanocytes (i.e., the percentage of proliferative cells) adjacent to the wound is reduced (7.0 ± 2.5%) compared to steady-state, undamaged tissue (46.6 ± 2.6%), while the length of the cell cycle remained short (5.6 ± 3.4 h). The percentage of proliferative choanocytes increased over time in all areas and after six days of regeneration choanocyte proliferation rates were comparable to steady-state tissue. Tissue areas farther from the wound had higher rates of choanocyte proliferation than areas closer to the wound, indicating that more resources are demanded from tissue in the immediate vicinity of the wound. There was no difference in the number of proliferative mesohyl cells in regenerative sponges compared to steady-state sponges. Our data suggest that the production of collagen-rich wound tissue is a key process in tissue regeneration for H. caerulea, and helps to rapidly occupy the bare substratum exposed by the wound. Regeneration and choanocyte renewal are competing and negatively correlated life-history traits, both essential to the survival of sponges. The efficient allocation of limited resources to these life-history traits has enabled the ecological success and diversification of sponges.

No MeSH data available.


Regeneration in H. caerulea (A) directly, (B) one day, (C) two days, and (D) six days after wound infliction.After six days, sponges had completely filled in the bare substrate exposed by the initial wound with a thin layer of regenerative wound tissue. Tissue samples were taken directly adjacent to the wound, 1 cm from the wound, and 3 cm from the wound (A). Tissue samples taken adjacent to the wound were marked with an arrow shape so that the orientation of the tissue could be recognized and histological sections could be made that included the wound area (A). Within each tissue sample, three histological sections were analyzed, each 100 µm apart, represented by the solid black lines (A). Photographs by Brittany Alexander.
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fig-1: Regeneration in H. caerulea (A) directly, (B) one day, (C) two days, and (D) six days after wound infliction.After six days, sponges had completely filled in the bare substrate exposed by the initial wound with a thin layer of regenerative wound tissue. Tissue samples were taken directly adjacent to the wound, 1 cm from the wound, and 3 cm from the wound (A). Tissue samples taken adjacent to the wound were marked with an arrow shape so that the orientation of the tissue could be recognized and histological sections could be made that included the wound area (A). Within each tissue sample, three histological sections were analyzed, each 100 µm apart, represented by the solid black lines (A). Photographs by Brittany Alexander.

Mentions: Tissue damage was induced by removing a small piece of tissue (∼1 cm2) from the center of the sponge using a scalpel, and exposing the bare substrate (Fig. 1A). Wounded sponges were placed in individual incubation chambers (3L) containing magnetic stirring devices. The incubation chambers were kept in the aquaria to maintain ambient seawater temperature (De Goeij et al., 2009; Alexander et al., 2014). In order to determine cell cycle parameters (e.g., length of the cell cycle, growth fraction) of choanocytes directly after wound infliction (herein referred to as ‘early regenerative tissue’), sponges were continuously labeled with 50 µmol L−1 5-bromo-2′-deoxyuridine (BrdU, Sigma) directly after wounding for t = 0, 0.5, 1.5, 2, 6, and 8 h (n = 3 for each time point). After BrdU-labeling, a tissue sample (∼0.5 cm2) directly adjacent to the wound was removed from each sponge (Fig. 1A).


Cell kinetics during regeneration in the sponge Halisarca caerulea: how local is the response to tissue damage?

Alexander BE, Achlatis M, Osinga R, van der Geest HG, Cleutjens JP, Schutte B, de Goeij JM - PeerJ (2015)

Regeneration in H. caerulea (A) directly, (B) one day, (C) two days, and (D) six days after wound infliction.After six days, sponges had completely filled in the bare substrate exposed by the initial wound with a thin layer of regenerative wound tissue. Tissue samples were taken directly adjacent to the wound, 1 cm from the wound, and 3 cm from the wound (A). Tissue samples taken adjacent to the wound were marked with an arrow shape so that the orientation of the tissue could be recognized and histological sections could be made that included the wound area (A). Within each tissue sample, three histological sections were analyzed, each 100 µm apart, represented by the solid black lines (A). Photographs by Brittany Alexander.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4358696&req=5

fig-1: Regeneration in H. caerulea (A) directly, (B) one day, (C) two days, and (D) six days after wound infliction.After six days, sponges had completely filled in the bare substrate exposed by the initial wound with a thin layer of regenerative wound tissue. Tissue samples were taken directly adjacent to the wound, 1 cm from the wound, and 3 cm from the wound (A). Tissue samples taken adjacent to the wound were marked with an arrow shape so that the orientation of the tissue could be recognized and histological sections could be made that included the wound area (A). Within each tissue sample, three histological sections were analyzed, each 100 µm apart, represented by the solid black lines (A). Photographs by Brittany Alexander.
Mentions: Tissue damage was induced by removing a small piece of tissue (∼1 cm2) from the center of the sponge using a scalpel, and exposing the bare substrate (Fig. 1A). Wounded sponges were placed in individual incubation chambers (3L) containing magnetic stirring devices. The incubation chambers were kept in the aquaria to maintain ambient seawater temperature (De Goeij et al., 2009; Alexander et al., 2014). In order to determine cell cycle parameters (e.g., length of the cell cycle, growth fraction) of choanocytes directly after wound infliction (herein referred to as ‘early regenerative tissue’), sponges were continuously labeled with 50 µmol L−1 5-bromo-2′-deoxyuridine (BrdU, Sigma) directly after wounding for t = 0, 0.5, 1.5, 2, 6, and 8 h (n = 3 for each time point). After BrdU-labeling, a tissue sample (∼0.5 cm2) directly adjacent to the wound was removed from each sponge (Fig. 1A).

Bottom Line: We demonstrate that during early regeneration, the growth fraction of the choanocytes (i.e., the percentage of proliferative cells) adjacent to the wound is reduced (7.0 ± 2.5%) compared to steady-state, undamaged tissue (46.6 ± 2.6%), while the length of the cell cycle remained short (5.6 ± 3.4 h).There was no difference in the number of proliferative mesohyl cells in regenerative sponges compared to steady-state sponges.The efficient allocation of limited resources to these life-history traits has enabled the ecological success and diversification of sponges.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Aquatic Ecology and Ecotoxicology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam , Amsterdam , The Netherlands ; Porifarma B.V. , Ede , The Netherlands.

ABSTRACT
Sponges have a remarkable capacity to rapidly regenerate in response to wound infliction. In addition, sponges rapidly renew their filter systems (choanocytes) to maintain a healthy population of cells. This study describes the cell kinetics of choanocytes in the encrusting reef sponge Halisarca caerulea during early regeneration (0-8 h) following experimental wound infliction. Subsequently, we investigated the spatial relationship between regeneration and cell proliferation over a six-day period directly adjacent to the wound, 1 cm, and 3 cm from the wound. Cell proliferation was determined by the incorporation of 5-bromo-2'-deoxyuridine (BrdU). We demonstrate that during early regeneration, the growth fraction of the choanocytes (i.e., the percentage of proliferative cells) adjacent to the wound is reduced (7.0 ± 2.5%) compared to steady-state, undamaged tissue (46.6 ± 2.6%), while the length of the cell cycle remained short (5.6 ± 3.4 h). The percentage of proliferative choanocytes increased over time in all areas and after six days of regeneration choanocyte proliferation rates were comparable to steady-state tissue. Tissue areas farther from the wound had higher rates of choanocyte proliferation than areas closer to the wound, indicating that more resources are demanded from tissue in the immediate vicinity of the wound. There was no difference in the number of proliferative mesohyl cells in regenerative sponges compared to steady-state sponges. Our data suggest that the production of collagen-rich wound tissue is a key process in tissue regeneration for H. caerulea, and helps to rapidly occupy the bare substratum exposed by the wound. Regeneration and choanocyte renewal are competing and negatively correlated life-history traits, both essential to the survival of sponges. The efficient allocation of limited resources to these life-history traits has enabled the ecological success and diversification of sponges.

No MeSH data available.