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| Author(s): |
Tiago Falcón Lopes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Ribeirão Preto. |
| Institution: | Universidade de São Paulo (USP). Faculdade de Medicina de Ribeirão Preto (PCARP/BC) |
| Defense date: | 2016-11-01 |
| Examining board members: |
Marcia Maria Gentile Bitondi;
Maria Juliana Ferreira Caliman;
Nicolas Gerard Chaline;
Celso Teixeira Mendes Junior;
Zila Luz Paulino Simoes
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| Advisor: | Marcia Maria Gentile Bitondi |
| Abstract | |
Differences in the timing of exoskeleton melanization and sclerotization processes are evident when comparing the external morphology of social and solitary bee species. Such differences may constitute a relevant example of cuticular maturation heterochrony, this term referring to a genetic change in timing of an ontogenetic process relative to an ancestor or between taxons. We proposed that social bees, which remain protected inside the colony for many days before initiating outside nest activities, would reach the maturity of some organic systems, such as the integument (epidermis and cuticle), later than solitary bees, which start such activities immediately after ecdysis. We tested this hypothesis in a comparative study of the developing integument of eusocial bees, Apis mellifera and Frieseomelitta varia, and the solitary bee Centris analis. Using RNA-seq, we verified that the expression profiles of genes involved in cuticular melanization and sclerotization (ebony and tan), chitin deposition and organization (Cda5, Idgf4, chitooligosacchariodolytic-domain-like), and cuticle formation (CPR14, CPR17, CPR18, CPR25, CPR23, CPE26, Apd-3, Apd-like) were positively, correlated between the two eusocial species, but not between the eusocial and the solitary species. Some of the genes with roles in regulating exoskeleton maturation (FTZ-F1, E74, Hr46, Hr4) were co-expressed only in the eusocial species. The expression profiles of these genes (except Hr46) and other regulatory genes (Ethr, Hr38, Rickets, Ptx-1) were also positively correlated exclusively in the eusocial bees. We also highlighted the expression of genes involved in non-melanin pigment production and the expression of circadian rhythm genes that could be related to chitin layers deposition. Transmission electron microscopy analysis of the integument of the two eusocial and the solitary bee species, in addition to other three bee species (the primitively eusocial Bombus brasilienses; the facultatively social Euglossa cordata; the solitary bee Tetrapedia diversipes), showed differences in cuticle ultrastructure and thickness, thus supporting the RNA-seq data. In agreement with our hypothesis, CHC quantifications were consistent with the expression levels of genes involved in CHC biosynthesis, thus differentiating the superficial cuticle layer of the eusocial and solitary species. Together, the integument transcriptomes, ultrastructure, and CHC quantification allowed us to characterize differences in the timing of cuticle maturation in social and solitary bees (AU) | |
| FAPESP's process: | 12/24284-5 - Comparative approach of cuticular maturation heterochrony in social and solitary bees using RNA-Seq, hydrocarbons quantification and electron microscopy |
| Grantee: | Tiago Falcon Lopes |
| Support Opportunities: | Scholarships in Brazil - Doctorate |