Co-option of hedgehog and wingless pathways in the formation of evolutionary no...

• Author(s): Marialva, Marta Sofia Pires
• Date: 2009
• Persistent ID: http://hdl.handle.net/10451/1469
• Origin: Repositório da Universidade de Lisboa
• Subject(s): Evolução; Biologia do desenvolvimento; Hibridação in situ; Teses de mestrado
• Document Type: Master Thesis
• Advisor(s): Sucena, Élio; Beldade, Patrícia

Description

Tese de mestrado, Biologia (Biologia Evolutiva e do Desenvolvimento), 2009, Universidade de Lisboa, Faculdade de Ciências Resumo alargado em português disponível no documento The world is like a biological diversity accumulator and understanding the mechanisms responsible for the generation of this diversity is a fascinating theme in biology. The diversification of patterns and shapes can be accomplished by the origin of novelties lineage specific traits of new adaptive value. Much recent data suggest that novelties can arise from co-option: recycling of shared genetic circuitry. One of the most beautiful examples of this is found in butterfly wing patterns. Some wings have conspicuous circular paintings called eyespots development of which is divided in four main stages: prepattern, focus determination, focal signaling and cellular differentiation. There are some gaps in our knowledge about genes involved in this pattern design. Experiments with Junonia coenia revealed the expression of hedgehog around the foci in larvae, and, in Bicyclus anynana pupae, imunohistochemistry analysis showed the expression of Wingless, also a morphogen. Here, we studied the co-option of those two signaling pathways in formation of novelties using in situ hybridization to detect spatial patterns of gene expression. hedgehog was found only in the posterior area of larval wings with no higher expression around the foci as observed for J. coenia. On the other hand, it was detected that both sense and anti-sense transcripts for wingless were being expressed in eyespot foci at the same time. A model was designed to explain this finding that requires that different cells should be expressing wingless mRNA and anti-transcript. To have a better comprehension about Hedgehog and Wingless pathways involvement in eyespot formation we also analyzed expression of other genes: patched (hedgehog receptor), frizzled (wingless receptor) and groucho (a negative regulator of wingless signal transduction). However, there is still a lot to be done and the necessity of functional tests is clear.