Mitochondrial structure and dynamics as critical factors in honey bee (Apis mellifera L.) caste development

Author(s)

Santos, Douglas Elias ^[1] ; Alberici, Luciane Carla ^[2] ; Hartfelder, Klaus ^[1]

Affiliation

^[1] Univ Sao Paulo, Fac Med Ribeirao Preto, Dept Biol Celular & Mol, Av Bandeirantes 3900, BR-14049900 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Fac Ciencias Farmaceut Ribeirao Preto, Dept Quim & Fis, Av Cafe S-N, BR-14040903 Sao Paulo - Brazil

• Document type: Journal article
• Source: Insect Biochemistry and Molecular Biology; v. 73, p. 1-11, JUN 2016.
• Web of Science Citations: 4

Abstract

The relationship between nutrition and phenotype is an especially challenging question in cases of facultative polyphenism, like the castes of social insects. In the honey bee, Apis mellifera, unexpected modifications in conserved signaling pathways revealed the hypoxia response as a possible mechanism underlying the regulation of body size and organ growth. Hence, the current study was designed to investigate possible causes of why the three hypoxia core genes are overexpressed in worker larvae. Parting from the hypothesis that this has an endogenous cause and is not due to differences in external oxygen levels we investigated mitochondrial numbers and distribution, as well as mitochondrial oxygen consumption rates in fat body cells of queen and worker larvae during the caste fate-critical larval stages. By immunofluorescence and electron microscopy we found higher densities of mitochondria in queen larval fat body, a finding further confirmed by a citrate synthase assay quantifying mitochondrial functional units. Oxygen consumption measurements by high-resolution respirometry revealed that queen larvae have higher maximum capacities of ATP production at lower physiological demand. Finally, the expression analysis of mitogenesis-related factors showed that the honey bee TFB1 and TFB2 homologs, and a nutritional regulator, ERR, are overexpressed in queen larvae. These results are strong evidence that the differential nutrition of queen and worker larvae by nurse bees affects mitochondrial dynamics and functionality in the fat body of these larvae, hence explaining their differential hypoxia response. (C) 2016 Elsevier Ltd. All rights reserved. (AU)

• FAPESP's process: 10/17259-9 - Studies on mechanisms of mitochondrial uncoupling by non-esterified fatty acids as a strategy for prevention / treatment of obesity
• Grantee: Luciane Carla Alberici
• Support type: Research Grants - Young Investigators Grants
• FAPESP's process: 13/24733-7 - Oxidative metabolism in caste differentiation in honeybees: number and structure of gene expression and mitochondrial functional indicators
• Grantee: Douglas Elias Santos
• Support type: Scholarships in Brazil - Doctorate