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A transcriptional time-course analysis of oral vs. aboral whole-body regeneration in the Sea anemone Nematostella vectensis

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ABSTRACT

Background: The ability of regeneration is essential for the homeostasis of all animals as it allows the repair and renewal of tissues and body parts upon normal turnover or injury. The extent of this ability varies greatly in different animals with the sea anemone Nematostella vectensis, a basal cnidarian model animal, displaying remarkable whole-body regeneration competence.

Results: In order to study this process in Nematostella we performed an RNA-Seq screen wherein we analyzed and compared the transcriptional response to bisection in the wound-proximal body parts undergoing oral (head) or aboral (tail) regeneration at several time points up to the initial restoration of the basic body shape. The transcriptional profiles of regeneration responsive genes were analyzed so as to define the temporal pattern of differential gene expression associated with the tissue-specific oral and aboral regeneration. The identified genes were characterized according to their GO (gene ontology) assignations revealing groups that were enriched in the regeneration process with particular attention to their affiliation to the major developmental signaling pathways. While some of the genes and gene groups thus analyzed were previously known to be active in regeneration, we have also revealed novel and surprising candidate genes such as cilia-associated genes that likely participate in this important developmental program.

Conclusions: This work highlighted the main groups of genes which showed polarization upon regeneration, notably the proteinases, multiple transcription factors and the Wnt pathway genes that were highly represented, all displaying an intricate temporal balance between the two sides. In addition, the evolutionary comparison performed between regeneration in different animal model systems may reveal the basic mechanisms playing a role in this fascinating process.

Electronic supplementary material: The online version of this article (doi:10.1186/s12864-016-3027-1) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus

Experimental design of a time-course analysis of regeneration in Nematostella vectensis. a. A schematic depiction of the experimental procedure. Aboral “tail or physa” regeneration appears in the top row and oral “head” regeneration appears in the bottom row. The dissection planes are denoted by dashed red lines and the wound proximal parts were used for RNA extraction and the RNA-Seq screen. b. Photographs of regeneration process corresponding to the time course of the experiment. Left panels show a polyp before and after bisection at a plane marked by the yellow dashed line. The right panel shows pictures of the oral and physal-regenerating parts of the bisected fragments along the time course
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Fig1: Experimental design of a time-course analysis of regeneration in Nematostella vectensis. a. A schematic depiction of the experimental procedure. Aboral “tail or physa” regeneration appears in the top row and oral “head” regeneration appears in the bottom row. The dissection planes are denoted by dashed red lines and the wound proximal parts were used for RNA extraction and the RNA-Seq screen. b. Photographs of regeneration process corresponding to the time course of the experiment. Left panels show a polyp before and after bisection at a plane marked by the yellow dashed line. The right panel shows pictures of the oral and physal-regenerating parts of the bisected fragments along the time course

Mentions: In order to study the transcriptional basis of oral versus aboral regeneration we performed a transcriptional profile screen in which we examined the time course of polarized regeneration. To this end, we dissected adult polyps (ca 3 months old) into two parts in their mid-body, which corresponds to mid-gastric dissection in the Hydra. The wound-proximal “blastema”–like regions from 20 oral (‘head’) or aboral (‘tail’ or physa) fragments were taken immediately upon amputation (hour 0) and at three later time points (8, 24, and 72 h post dissection) (see Fig. 1a). These time points represent early regeneration at the wound-healing stage (up to ~8 h), the active growth and cell proliferation stage (24 h), and the later stage of remodeling and morphogenesis at 72 h [42, 52, 53, 55, 57]. The morphological changes in the appearance of the bisected polyps were followed. We observed that at 8 h wound closure was complete due to wound healing processes, as reported by DuBuc et al. [57] for puncture and bisection assays performed on very young polyps [57] and by Amiel et al. [53] for adult and young polyps. At this time we did not find any visible signs of new tissue formation and the wounded mesenteries are seen to be in close proximity to the site of the cut, while at the first hours they seem to recede from the wound plane (Fig. 1b). At 24 h we observed that the mesenteries seemed to be attached to the center of the cut area in both the oral and aboral fragments as reported before for oral regeneration [53, 57]. At 72 h tentacle buds can begin to be detected in the regenerating oral side, and in the regenerating physa the mesenteries appeared disconnected from the previously wounded area and the physal end is more rounded and clear. We chose 72 h as our last time point since the general re-establishment of the body plan after dissection and the major morphogenesis processes seem to have been determined by this time. While the regenerating polyps still grow extensively for several more days until their body parts assume normal proportions, and several more weeks for returning to their original size, this is secondary to the reorganization of the body plan.Fig. 1


A transcriptional time-course analysis of oral vs. aboral whole-body regeneration in the Sea anemone Nematostella vectensis
Experimental design of a time-course analysis of regeneration in Nematostella vectensis. a. A schematic depiction of the experimental procedure. Aboral “tail or physa” regeneration appears in the top row and oral “head” regeneration appears in the bottom row. The dissection planes are denoted by dashed red lines and the wound proximal parts were used for RNA extraction and the RNA-Seq screen. b. Photographs of regeneration process corresponding to the time course of the experiment. Left panels show a polyp before and after bisection at a plane marked by the yellow dashed line. The right panel shows pictures of the oral and physal-regenerating parts of the bisected fragments along the time course
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5015328&req=5

Fig1: Experimental design of a time-course analysis of regeneration in Nematostella vectensis. a. A schematic depiction of the experimental procedure. Aboral “tail or physa” regeneration appears in the top row and oral “head” regeneration appears in the bottom row. The dissection planes are denoted by dashed red lines and the wound proximal parts were used for RNA extraction and the RNA-Seq screen. b. Photographs of regeneration process corresponding to the time course of the experiment. Left panels show a polyp before and after bisection at a plane marked by the yellow dashed line. The right panel shows pictures of the oral and physal-regenerating parts of the bisected fragments along the time course
Mentions: In order to study the transcriptional basis of oral versus aboral regeneration we performed a transcriptional profile screen in which we examined the time course of polarized regeneration. To this end, we dissected adult polyps (ca 3 months old) into two parts in their mid-body, which corresponds to mid-gastric dissection in the Hydra. The wound-proximal “blastema”–like regions from 20 oral (‘head’) or aboral (‘tail’ or physa) fragments were taken immediately upon amputation (hour 0) and at three later time points (8, 24, and 72 h post dissection) (see Fig. 1a). These time points represent early regeneration at the wound-healing stage (up to ~8 h), the active growth and cell proliferation stage (24 h), and the later stage of remodeling and morphogenesis at 72 h [42, 52, 53, 55, 57]. The morphological changes in the appearance of the bisected polyps were followed. We observed that at 8 h wound closure was complete due to wound healing processes, as reported by DuBuc et al. [57] for puncture and bisection assays performed on very young polyps [57] and by Amiel et al. [53] for adult and young polyps. At this time we did not find any visible signs of new tissue formation and the wounded mesenteries are seen to be in close proximity to the site of the cut, while at the first hours they seem to recede from the wound plane (Fig. 1b). At 24 h we observed that the mesenteries seemed to be attached to the center of the cut area in both the oral and aboral fragments as reported before for oral regeneration [53, 57]. At 72 h tentacle buds can begin to be detected in the regenerating oral side, and in the regenerating physa the mesenteries appeared disconnected from the previously wounded area and the physal end is more rounded and clear. We chose 72 h as our last time point since the general re-establishment of the body plan after dissection and the major morphogenesis processes seem to have been determined by this time. While the regenerating polyps still grow extensively for several more days until their body parts assume normal proportions, and several more weeks for returning to their original size, this is secondary to the reorganization of the body plan.Fig. 1

View Article: PubMed Central - PubMed

ABSTRACT

Background: The ability of regeneration is essential for the homeostasis of all animals as it allows the repair and renewal of tissues and body parts upon normal turnover or injury. The extent of this ability varies greatly in different animals with the sea anemone Nematostella vectensis, a basal cnidarian model animal, displaying remarkable whole-body regeneration competence.

Results: In order to study this process in Nematostella we performed an RNA-Seq screen wherein we analyzed and compared the transcriptional response to bisection in the wound-proximal body parts undergoing oral (head) or aboral (tail) regeneration at several time points up to the initial restoration of the basic body shape. The transcriptional profiles of regeneration responsive genes were analyzed so as to define the temporal pattern of differential gene expression associated with the tissue-specific oral and aboral regeneration. The identified genes were characterized according to their GO (gene ontology) assignations revealing groups that were enriched in the regeneration process with particular attention to their affiliation to the major developmental signaling pathways. While some of the genes and gene groups thus analyzed were previously known to be active in regeneration, we have also revealed novel and surprising candidate genes such as cilia-associated genes that likely participate in this important developmental program.

Conclusions: This work highlighted the main groups of genes which showed polarization upon regeneration, notably the proteinases, multiple transcription factors and the Wnt pathway genes that were highly represented, all displaying an intricate temporal balance between the two sides. In addition, the evolutionary comparison performed between regeneration in different animal model systems may reveal the basic mechanisms playing a role in this fascinating process.

Electronic supplementary material: The online version of this article (doi:10.1186/s12864-016-3027-1) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus