O código transcricional gerado pelo cérebro sob influência de diferenciais dietários durante o desenvolvimento do sistema nervoso de Apis mellifera

Abstract

The morphophysiological differentiation observed among Apis mellifera females is due to the different diets experienced during the larval period, which trigger complex cascades of endocrine reactions, leading to the establishment of different gene expression networks, thus giving rise to two very different morphs, queens and workers, from seemingly identical genotypes. The brain area/body size ratio represents a major phenotypic difference between queens and workers. Adult workers have proportionally more developed brains than queens. However, the opposite is observed during the larval period, in which queens have larger brains, probably in response to differential nutrition. Thus, our objective was to identify molecular mediators responding to the larval differential feeding, leading to the more developed brain of queens. Larval brains were dissected, and their total RNAs were used for cDNA synthesis, from which was synthesized aRNA marked with different fluorophores. These labeled RNAs were hybridized to oligonucleotide microarray slides corresponding to all known genes of the A. mellifera genome. After obtaining images and quantification of hybridization, the differentially represented transcripts (DRT) were selected through normalization and statistical analyzes, and studied in silico. There were found 16 DRT in the brain of A. mellifera queens and workers at L4, 12 up-regulated in queens and 4 in workers. Considering predicted functions, or demonstrated in other biological systems, the up-regulated transcript products in queens are associated with cell proliferation, fasciculation and interneuronal connections processes. In workers, the over-represented gene products act mainly on the eye cells and GABAergic neurons development, thus allowing adult activities like navigation, foraging, and nestmate recognition. qPCR of the gene GlcAT-P (a DRT) showed that its transcription levels are higher in queens’ brain during the whole larval period (L3-L5), thus confirming microarray results. The products encoded by the DRTs found in this work, acting together, may be responsible for mediating the nutritional influence on brain morphogenesis in A. mellifera castes.