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(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

Vascular budding in Symplegma brakenhielmi and the evolution of coloniality in styelid ascidians

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Autor(es):
Gutierrez, Stefania ; Brown, Federico D.
Número total de Autores: 2
Tipo de documento: Artigo Científico
Fonte: Developmental Biology; v. 423, n. 2, p. 152-169, MAR 15 2017.
Citações Web of Science: 9
Resumo

Individuals of colonial animals (e.g. zooids) are in continuous turnover. In ascidians colonial or solitary species have evolved by convergence multiple times. Colonial Botryllus and Botrylloides are well-studied genera that exhibit colony-wide developmental mechanisms that regulate synchronous and orchestrated cycles of budding and turnover of zooids. The origins of modular developmental mechanisms that facilitated the evolution of coloniality in this group remain unclear. To reconstruct ancestral states of coloniality we studied Symplegma brakenhielmi, a sister taxon of the botryllids. S. brakenhielmi zooids are embedded in a common tunic and present a similar vascular system as the botrylloides, however development and turnover of zooids occurs asynchronously and in a more independent manner. We generated a table of common stages of budding in Symplegma and Botryllus for comparative studies of asexual development. We tested dependent processes of budding among individuals of the colony by systemic bud or zooid removals. Although our results showed a higher degree of independence in bud development in S. brakenhielmi, we found a subtle colony-wide regulatory mechanism of modular development, i.e. new buds expedited development after the removal of all buds in the colony. Next, we characterized external morphology, ultrastructure, and abundance of circulatory blood cells in the vascular system of S. brakenhielmi. Macrophage-like cells (MLCs) are involved in zooid resorption and turnover. Proportions of MLCs in the blood of S. brakenhielmi corresponded to the peak of occurrence of this cell type during the budding cycle of B. schlosseri. We found several new blood cell types in S. brakenhielmi, including two cell types that resemble circulatory progenitor stem cells of other botryllid colonial ascidians. These cells showed features of undifferentiated cells and expressed mitotic marker Phospho-histone H3. Comparative studies of S. brakenhielmi and B. schlosseri allow us to discuss possible changes in the regulation of modular development (i.e. regulation of life and death in the colony), and a possible contribution of circulatory blood cells in budding processes. We propose that the higher degree of developmental independence in S. brakenhielmi budding is a result of its ancestral solitary mode of development. (AU)

Processo FAPESP: 15/22650-2 - Evolução de modos do desenvolvimento em ascídias coloniais
Beneficiário:Arianna Stefania Gutierrez Osorio
Linha de fomento: Bolsas no Brasil - Doutorado Direto
Processo FAPESP: 15/50164-5 - Células-tronco, brotação e a evolução da colonialidade em ascídias
Beneficiário:Federico David Brown Almeida
Linha de fomento: Auxílio à Pesquisa - Apoio a Jovens Pesquisadores