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Comparative analysis of Wnt expression identifies a highly conserved developmental transition in flatworms

Please always quote using this URN: urn:nbn:de:bvb:20-opus-146566
  • Background Early developmental patterns of flatworms are extremely diverse and difficult to compare between distant groups. In parasitic flatworms, such as tapeworms, this is confounded by highly derived life cycles involving indirect development, and even the true orientation of the tapeworm antero-posterior (AP) axis has been a matter of controversy. In planarians, and metazoans generally, the AP axis is specified by the canonical Wnt pathway, and we hypothesized that it could also underpin axial formation during larval metamorphosis inBackground Early developmental patterns of flatworms are extremely diverse and difficult to compare between distant groups. In parasitic flatworms, such as tapeworms, this is confounded by highly derived life cycles involving indirect development, and even the true orientation of the tapeworm antero-posterior (AP) axis has been a matter of controversy. In planarians, and metazoans generally, the AP axis is specified by the canonical Wnt pathway, and we hypothesized that it could also underpin axial formation during larval metamorphosis in tapeworms. Results By comparative gene expression analysis of Wnt components and conserved AP markers in the tapeworms Echinococcus multilocularis and Hymenolepis microstoma, we found remarkable similarities between the early stages of larval metamorphosis in tapeworms and late embryonic and adult development in planarians. We demonstrate posterior expression of specific Wnt factors during larval metamorphosis and show that scolex formation is preceded by localized expression of Wnt inhibitors. In the highly derived larval form of E. multilocularis, which proliferates asexually within the mammalian host, we found ubiquitous expression of posterior Wnt factors combined with localized expression of Wnt inhibitors that correlates with the asexual budding of scoleces. As in planarians, muscle cells are shown to be a source of secreted Wnt ligands, providing an explanation for the retention of a muscle layer in the immotile E. multilocularis larva. Conclusions The strong conservation of gene expression between larval metamorphosis in tapeworms and late embryonic development in planarians suggests, for the first time, a homologous developmental period across this diverse phylum. We postulate these to represent the phylotypic stages of these flatworm groups. Our results support the classical notion that the scolex is the true anterior end of tapeworms. Furthermore, the up-regulation of Wnt inhibitors during the specification of multiple anterior poles suggests a mechanism for the unique asexual reproduction of E. multilocularis larvae.show moreshow less

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Metadaten
Author: Uriel Koziol, Francesca Jarero, Peter D. Olson, Klaus Brehm
URN:urn:nbn:de:bvb:20-opus-146566
Document Type:Journal article
Faculties:Medizinische Fakultät / Institut für Hygiene und Mikrobiologie
Language:English
Parent Title (English):BMC Biology
Year of Completion:2016
Volume:14
Issue:10
Source:BMC Biology (2016) 14:10 DOI 10.1186/s12915-016-0233-x
DOI:https://doi.org/10.1186/s12915-016-0233-x
Dewey Decimal Classification:6 Technik, Medizin, angewandte Wissenschaften / 61 Medizin und Gesundheit / 610 Medizin und Gesundheit
Tag:FoxQ2; SFRP; Six3/6 Wnt; antero-posterior axis; cestodes; metamorphosis; myocyte; phylotypic; planarian; platyhelminthes
Release Date:2017/04/04
Collections:Open-Access-Publikationsfonds / Förderzeitraum 2016
Licence (German):License LogoCC BY: Creative-Commons-Lizenz: Namensnennung