A r t i c l e TRADE-OFF BETWEEN IMMUNE STIMULATION AND EXPRESSION OF STORAGE PROTEIN GENES Anete P. Lourenc - o Departamento de Gene´tica, Faculdade de Medicina de Ribeira˜o Preto, Universidade de Sa˜o Paulo, Ribeira˜o Preto, Sa˜o Paulo, Brazil; DepartamentodeCieˆnciasBiolo´gicas,FaculdadedeCieˆnciasBiolo´gicas e da Sau´de, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Diamantina, Minas Gerais, Brazil Juliana R. Martins Departamento de Gene´tica, Faculdade de Medicina de Ribeira˜o Preto, Universidade de Sa˜o Paulo, Ribeira˜o Preto, Sa˜o Paulo, Brazil Ma ´ rcia M.G. Bitondi and Zila ´ L.P. Simo ˜ es Departamento de Biologia, Faculdade de Filosofia, Cieˆncias e Letras de Ribeira˜o Preto, Universidade de Sa˜o Paulo, Ribeira˜o Preto, Sa˜o Paulo, Brazil Proteins stored in insect hemolymph may serve as a source of amino acids and energy for metabolism and development. The expression of the main storage proteins was assessed in bacterial-challenged honey bees using real-time (RT)-PCR and Western blot. After ensuring that the immune system had been activated by measuring the ensuing expression of the innate immune response genes, defensin-1 (def-1) and prophenoloxidase (proPO), we verified the expression of four genes encoding storage proteins. The levels of vitellogenin (vg) mRNA and of the respective protein were significantly lowered in bees injected with bacteria or water only (injury). An equivalent response was observed in orally-infected bees. The levels of apolipophorin II/I (apoLp-II/I) and hexamerin (hex 70a) mRNAs did not significantly change, but levels of Hex 70a protein subunit showed a substantial decay after bacterial challenge or injury. Grant sponsor: FAPESP/Brazil; Grant numbers: 03/07041-2; 05/03926-5. Correspondence to: Anete P. Lourenc - o, Departamento de Cieˆncias Biolo ´gicas, Faculdade de Cieˆncias Biolo ´gicas e da Sau ´de, Universidade Federal dos Vales do Jequitinhonha e Mucuri, Campus II, Rodovia MGT 367, Km 583, no 5000, Bairro Alto da Jacuba, 39100-000, Diamantina, Minas Gerais, Brazil. E-mail: anetelourenco@gmail.com ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY Published online in Wiley InterScience (www.interscience.wiley.com). & 2009 Wiley Periodicals, Inc. DOI: 10.1002/arch.20301