RESUMO
BACKGROUND: In honeybees, differential feeding of female larvae promotes the occurrence of two different phenotypes, a queen and a worker, from identical genotypes, through incremental alterations, which affect general growth, and character state alterations that result in the presence or absence of specific structures. Although previous studies revealed a link between incremental alterations and differential expression of physiometabolic genes, the molecular changes accompanying character state alterations remain unknown. RESULTS: By using cDNA microarray analyses of >6,000 Apis mellifera ESTs, we found 240 differentially expressed genes (DEGs) between developing queens and workers. Many genes recorded as up-regulated in prospective workers appear to be unique to A. mellifera, suggesting that the workers' developmental pathway involves the participation of novel genes. Workers up-regulate more developmental genes than queens, whereas queens up-regulate a greater proportion of physiometabolic genes, including genes coding for metabolic enzymes and genes whose products are known to regulate the rate of mass-transforming processes and the general growth of the organism (e.g., tor). Many DEGs are likely to be involved in processes favoring the development of caste-biased structures, like brain, legs and ovaries, as well as genes that code for cytoskeleton constituents. Treatment of developing worker larvae with juvenile hormone (JH) revealed 52 JH responsive genes, specifically during the critical period of caste development. Using Gibbs sampling and Expectation Maximization algorithms, we discovered eight overrepresented cis-elements from four gene groups. Graph theory and complex networks concepts were adopted to attain powerful graphical representations of the interrelation between cis-elements and genes and objectively quantify the degree of relationship between these entities. CONCLUSION: We suggest that clusters of functionally related DEGs are co-regulated during caste development in honeybees. This network of interactions is activated by nutrition-driven stimuli in early larval stages. Our data are consistent with the hypothesis that JH is a key component of the developmental determination of queen-like characters. Finally, we propose a conceptual model of caste differentiation in A. mellifera based on gene-regulatory networks.
Assuntos
Abelhas , Comportamento Animal/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Genes de Insetos , Hierarquia Social , Animais , Abelhas/anatomia & histologia , Abelhas/genética , Abelhas/fisiologia , Etiquetas de Sequências Expressas , Feminino , Perfilação da Expressão Gênica , Redes Reguladoras de Genes , Hormônios Juvenis/metabolismo , Larva/anatomia & histologia , Larva/fisiologia , Análise de Sequência com Séries de OligonucleotídeosRESUMO
Drosophila serido e D. antonietae são espécies crípticas pertencentes ao ''cluster'' Drosophila buzzatii. Morfologicamente, elas podem ser discriminadas apenas por diferenças quantitativas. Neste trabalho, nós analisamos o comprimento e a média da curvatura equalizada de quatro regiões do edeago de indivíduos de D. antonietae e D. serido. Os espécimes de D. serido e D. antonietae foram discriminados com 96,74% de eficiência. Apenas com base na variável que mais contribuiu para discriminação dos grupos (média da curvatura equalizada do arco IV do edeago), nós observamos significativa divergência morfológica intraespecífica em D. serido em relação a D. antonietae, o que está em concordância com outros marcadores. A alta divergência morfológica apenas na média da curvatura equalizada do arco IV do edeago mostra que essa região do edeago evoluiu mais rápido que as demais desde a divergência entre as duas espécies. A importância do presente estudo para o entendimento das bases genética que controlam a formação do edeago, nas espécies do ''cluster'' Drosophila buzzatii, é discutida.
Assuntos
Animais , Masculino , Drosophila/anatomia & histologia , Drosophila/classificação , Brasil , Análise por Conglomerados , Drosophila/genética , Evolução MolecularRESUMO
Drosophila serido and D. antonietae are sibling species belonging to the Drosophila buzzatii cluster. Morphologically, they can only be discriminated by quantitative traits. In this paper we analyze the length and equalized average curvature of four regions of the aedeagus of D. antonietae and D. serido. Specimens of D. serido and D. antonietae were classified correctly 96.74% of the time. Based only on the variable that most contributed to the discrimination of the groups (equalized average curvature of the arch IV of the aedeagus), we observed significant intraspecific morphological divergence in D. serido in relation to the D. antonietae, in agreement with other markers. The high morphological divergence in equalized average curvature of the arch IV of the aedeagus shows that this region evolved faster than others, since the divergence of the two species. The importance of the present study to the understanding of the genetic basis that controls the formation of the aedeagus, in the species of the Drosophila buzzatii cluster, is discussed.