Amlac 2 and integument differentiation in castes and sex of Apis mellifera: buildi...
| Grant number: | 14/13136-0 |
| Support type: | Regular Research Grants |
| Duration: | October 01, 2014 - September 30, 2016 |
| Field of knowledge: | Biological Sciences - Genetics - Animal Genetics |
| Principal Investigator: | Marcia Maria Gentile Bitondi |
| Grantee: | Marcia Maria Gentile Bitondi |
| Home Institution: | Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil |
Abstract
The exoskeleton of insects is primarily made of proteins, the polysaccharide chitin, and lipids. From the morphological point of view, the exoskeleton is arranged as a complex, multilayered structure formed by an inner procuticle comprising the endocuticle and exocuticle, the epicuticle and an outermost envelope. The rigid exoskeleton is periodically renewed through molting episodes, which are essential for insect growth. Larvae of holometabolous insects (complete metamorphosis) undergo a series of molts without, or with little, change in form before they stop feeding in preparation for the metamorphic molt, i.e., the larval-to-pupal transition. The last molting, or imaginal molt, transforms the pupa in an adult insect having a dark and sclerotized exoskeleton. Two points in this developmental table have deserved attention in our studies with holometabolous models, the bees. One of them refers to the morphogenesis of the pupal thoracic exoskeleton from imaginal discs precursors. What changes in gene expression are needed for the construction of this piece of exoskeleton? The other point refers to the maturation of the exoskeleton that makes the bee able to fly and face the environmental challenges. We have observed that species of social and solitary bees strikingly differ in the time of morphological exoskeleton maturation. The solitary bees emerge from the nest with a heavily pigmented and sclerotized exoskeleton, and immediately they start foraging for collection of nectar and pollen. In contrast, at the emergence, the social bees show a lower degree of exoskeleton pigmentation and sclerotization, and they remain for several days inside the hive before undertaken foraging activities. This is consistent with a temporal shift of exoskeleton maturation during bee evolution, or heterochrony. Here we are proposing to face these two important issues through the use of RNA-Seq (Next-Generation Sequencing). By sequencing the transcriptome of imaginal discs as they are transformed into the thoracic dorsum, and by sequencing the transcriptome of the integument of social and solitary bee species during specific times of pigmentation and sclerotization, we can add new information on the metamorphosis and maturation of this complex biological system, the exoskeleton, which shapes the insects, allows movement and locomotion, prevents desiccation, and is a rich source of semiochemicals and pheromones for insect survival. (AU)