Cell proliferation dynamics and morphological differentiation during regeneration in Dorvillea bermudensis (Polychaeta, Dorvilleidae)

Abstract

Although some species of Annelida have an enormous capacity to regenerate, it is not yet known whether reestablishment of lost body parts is performed by stem cells, depends on preceding dedifferentiation of somatic cells, or is a combination of both. In order to clarify how, in the case of epimorphic regeneration, the blastemas are formed, we applied the thymidine analog 5'-bromo-2'-deoxyuridine (BrdU) in the dorvilleid polychaete Dorvillea bermudensis to identify cells in the S-phase of the cell cycle. Regeneration pulse-chase experiments were carried out to determine onset and dynamics of the proliferation process, and BrdU pulse-chase experiments were undertaken to follow cell fate. We found irregularly distributed S-phase cells throughout the body of adult specimens. Subsequent to amputation, these cells do not migrate from the amputee towards the wound site, where proliferation activity was documented no earlier than 16 h after fragmentation. In the initial phase, the proliferation rate at the anterior end exceeds the rate at the posterior end. Observance of identity could be demonstrated for the ectoderm and can be assumed for the two other germ layers. The anterior blastema transforms into the head, while the posterior forms the pygidium and persists as a proliferation zone; four or numerous segments are formed by intercalation between the former anterior or posterior blastema and the amputee.

Proliferative response of the stem cell system during regeneration of the rostrum in Macrostomum lignano (Platyhelminthes)

“…Besides contraction of the musculature at the level of the wound, already 1 hour p-a, the wound was almost completely covered by a thin layer of flattened epidermal cells. The same mechanism was observed earlier for tail plate regeneration in M. lignano (Salvenmoser et al 2001;Nimeth et al 2007;Egger et al 2009) and regeneration in triclads, so-called planarians (Baguñà et al 1994;Sánchez Alvarado and Newmark 1998) and polychaetes (Paulus and Muller 2006).…”

To Be or Not to Be a Flatworm: The Acoel Controversy

“…3), triclads [18], rhabdocoels [19] and parasitic platyhelminths [20]. In contrast, proliferating cells in the epidermis occur in all other lophotrochozoans investigated, including annelids [21] (Fig. 4A–C), nemertines (Fig.…”

General characterization of regeneration in Aeolosoma viride (Annelida, Aeolosomatidae)

“…Complete regeneration from two segments is known in the oligochaete Enchytraeus japonensis and in the polychaete D. bermudensis , and our study showed a similar capacity in A. viride . Most individuals of A. viride could survive and regenerate from three segments, with the percentage of successful regenerates increasing with the number of regenerating segments (Paulus & Müller, ; Takeo, Yoshida‐Noro, & Tochinai, ). Comparative study of the regeneration of annelids might contribute to a better understanding of the evolutionary loss or gain of regenerative abilities.…”