60º CONGRESSO BRASILEIRO DE GENÉTICA
26 a 29 de agosto de 2014 Casa Grande Hotel Resort • Guarujá • SP • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
Morphological and molecular characterization of fin regeneration
in Lepidosiren paradoxa
Nogueira, AF1; Moreira, RN; Schneider, I1*
Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém, Brasil; 1Programa de Pós Graduação em Genética e
Biologia Molecular
*[email protected]
Keywords: Regeneration, Lungfish, Sarcopterygii, FGF-8, SHH
Adult teleost fish and urodele amphibians have the ability to regenerate appendages that are lost or injured through a proliferatedependent process called epimorphic regeneration, in which a blastema of cycling progenitor cells replaces the lost tissues. The
first step of appendage regeneration is the formation of the wound epidermis over the cut surface, which proliferate to form
a multilayered wound epithelium called apical epidermal cap (AEC). The wound epidermis/AEC is absolutely required for
blastema formation and limb regeneration. The blastema formation takes place through the histolysis, disorganization and
dedifferentiation of differentiated tissue beneath the wound epidermis. The blastema cells lose their phenotypic specialization
to become undifferentiated mesenchymal progenitor cells that re-enter the cell cycle and proliferate to keep the source of the
regeneration. Among the proteins secreted by regenerative epidermis are Sonic hedgehog (SHH) and Fibroblast growth factor
8 (FGF-8). The expression of FGF-8 in the distal AEC of amphibians suggests that its expression is critical for successful
limb regeneration. Studies showed that SHH signaling is required for limb regeneration, where SHH is able to restore the
anteroposterior patterning and improve redifferentiation of dedifferentiated cells. Most studies in fish cast light on the
dermal fin rays regeneration, the prevalent structure in teleost fish, while the tetrapod (amphibians) limbs comprising only
endoskeleton. Lungfishes, like the South American Lungfish Lepidosiren paradoxa are the sister group of tetrapods and have
a robust endoskeleton able to regenerate. To elucidate ancient and derived regenerative mechanisms in tetrapods, we are
evaluateing the fin regeneration of Lepidosiren paradoxa by histological techniques and examining the expression of FGF-8 and
SHH proteins by immunohistochemistry. Finally, we identify forward cell proliferation during fin regeneration by labeling
with anti-BrdU. We hope through this approach to elucidate cellular and molecular mechanisms that control endoskeleton
fin regeneration in Lepidosiren paradoxa, thus helping to formulate hypotheses about the origin of regenerative capacity in
tetrapods.
Financial support: CAPES and UFPA.
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