Regeneration and Growth as Modes of Adult Development: The Platyhelminthes as a Case Study

Cebrià, Francesc; Saló, Emili; Adell, Teresa

doi:10.1007/978-3-7091-1871-9_4

Cited by 2 publications

(2 citation statements)

References 235 publications

(234 reference statements)

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“…Bilaterian animals are not only characterized by a distinct anterior-posterior axis but also by defined dorsal and ventral body regions. The underlying regulatory network that commonly determines dorso-ventral polarity is the Dpp/BMP signalling pathway (De Robertis & Sasai, 1996;Ferguson, 1996;De Robertis & Kuroda, 2004;Ashe & Briscoe, 2006;Lowe et al, 2006;Cebria, Salo, & Adell, 2015). Briefly, the morphogen-encoding gene Dpp (the invertebrate homolog of the vertebrate Bmp2/4) is largely expressed dorsally in protostome animals, while its antagonists such as Chordin or Noggin have a predominantly ventral expression domain (Tan, Huan & Liu, 2017).…”

Section: (B) the Dpp/bmp Pathway And Dorso-ventral Patterningmentioning

confidence: 99%

The evolution of molluscs

2018

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Molluscs are extremely diverse invertebrate animals with a rich fossil record, highly divergent life cycles, and considerable economical and ecological importance. Key representatives include worm-like aplacophorans, armoured groups (e.g. polyplacophorans, gastropods, bivalves) and the highly complex cephalopods. Molluscan origins and evolution of their different phenotypes have largely remained unresolved, but significant progress has been made over recent years. Phylogenomic studies revealed a dichotomy of the phylum, resulting in Aculifera (shell-less aplacophorans and multi-shelled polyplacophorans) and Conchifera (all other, primarily uni-shelled groups). This challenged traditional hypotheses that proposed that molluscs gradually evolved complex phenotypes from simple, worm-like animals, a view that is corroborated by developmental studies that showed that aplacophorans are secondarily simplified. Gene expression data indicate that key regulators involved in anterior-posterior patterning (the homeobox-containing Hox genes) lost this function and were co-opted into the evolution of taxon-specific novelties in conchiferans. While the bone morphogenetic protein (BMP)/decapentaplegic (Dpp) signalling pathway, that mediates dorso-ventral axis formation, and molecular components that establish chirality appear to be more conserved between molluscs and other metazoans, variations from the common scheme occur within molluscan sublineages. The deviation of various molluscs from developmental pathways that otherwise appear widely conserved among metazoans provides novel hypotheses on molluscan evolution that can be tested with genome editing tools such as the CRISPR/Cas9 (clustered regularly interspaced short palindromic repeats/clustered regularly interspaced short palindromic repeats-associated protein9) system.

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Section: (B) the Dpp/bmp Pathway And Dorso-ventral Patterningmentioning

confidence: 99%

The evolution of molluscs

2018

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“…Varying abilities of posterior regeneration is a widespread feature in flatworms [55] as all members of the group rely on the maintenance of pluripotent somatic stem cells for all cellular turnover [56]. The transition from larval to adult form in tapeworms can be compared most directly to planarian development by considering the case of posterior regeneration, as in both organisms this involves the loss and replacement of former posterior tissues.…”

Section: Discussionmentioning

confidence: 99%

Segmentation in tapeworms as a modified form of flatworm posterior regeneration involving Wnt and Hedgehog signalling

Jarero,

Baillie,

Riddiford

et al. 2023

Preprint

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Tapeworms are parasitic flatworms that lack key features conventionally used to define the head-tail axis in free-living organisms, resulting in long standing questions regarding the true orientation of their main body axis. As adults, most tapeworms also exhibit a segmented body which has been considered an adaptation unique to the group. Anteroposterior (AP) patterning in free-living flatworms is controlled by β-catenin-dependent Wnt signalling and positional control genes are expressed by their musculature in highly regionalised domains. Here we investigate the expression of Wnt and Hedgehog components during the strobilar phase of the tapeworm life cycle during which larval tissues are lost and replaced through the continuous production of new tissues. Results reveal previously unidentified centres of signalling associated with their neuromuscular system and show that segments are marked by secondary, AP axes in agreement with the polarity of the primary body axis. Neuromuscular expression and communication between Wnt and Hedgehog signalling is consistent with embryonic and regenerative growth in planarians and is a common mechanism for establishing AP-polarised boundaries in a diverse range of segmented animals. Taken together our results suggest that segmentation in tapeworms represents a modified form of posterior regeneration, a common feature among flatworms.

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Regeneration and Growth as Modes of Adult Development: The Platyhelminthes as a Case Study

Cited by 2 publications

References 235 publications

The evolution of molluscs

The evolution of molluscs

Segmentation in tapeworms as a modified form of flatworm posterior regeneration involving Wnt and Hedgehog signalling

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