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Presenting Author(s) Sumihare Noji
Abstract Title Involvement of Wnt and EGF signalling systems in regeneration of cricket legs.
Full author List Sumihare Noji, Taro Mito, Yoshihisa Tanaka, Katsuyuki Miyawaki, Yohei Shinmyou, and Hideyo Ohuchi
Text of abstract Regeneration is the ability to replace lost parts by the growth or remodelling of somatic tissue. The issue of regeneration raises two major questions: What are the pattern formation mechanisms in regenerating tissue and how are they related to the patterning processes that occur in embryonic development? To address these questions, we have been working on limb development and regeneration with the cricket, Gryllus bimaculatus. As observed in cockroaches, cricket legs develop during embryogenesis so that the nymph possesses functional legs and the ability to regenerate these legs. We observed expression patterns of Gryllus bimaculatus hedgehog (Gb'hh), wingless (Gb'wg), and decapentaplegic (Gb'dpp), key genes during leg development, during leg regeneration and postulated that the formation of the proximodistal axis of a regenerating leg is triggered at a site where ventral wg-expressing cells abut dorsal dpp-expressing cells in the anteroposterior (A/P) boundary (Mito et al., MOD, 114, 27-35 (2002)) . Since a cricket homologue of Epidermal Growth Factor Receptor (Gb'EGFR) gene was expressed in the regeneration blastema, we speculated that the wg-dpp signal may induce expression of EGF as a regeneration factor. We observed expression patterns of wg during the intercalary regeneration: When a distally amputated tibia with disparate positional values is placed next to proximally amputated host, intercalary growth occurs in order to regenerate the missing part. We found that when grafted, expression of Gb'wg was induced in the proximal amputated region, but not in the distal grafted donor. This directional induction occurs in cells having more proximal positional values than the amputated position even in the reversed intercalation. These results indicated that wingless signalling may be involved in determination of positional values during intercalary regeneration.
Which session is your work most relevant to: Limb regeneration