Investigating circadian clock proteins in the brain of a stingless bee (Melipona quadrifasciata)

• Grant number: 23/02449-7
• Support Opportunities: Scholarships abroad - Research Internship - Scientific Initiation
• Start date: May 01, 2023
• End date: August 31, 2023
• Field of knowledge: Biological Sciences - Genetics - Animal Genetics
• Principal Investigator: Klaus Hartmann Hartfelder
• Grantee: Arthur Roque Justino
• Supervisor: Ricarda Scheiner
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Institution abroad: Julius-Maximilians-Universität Würzburg (JMU), Germany
• Associated to the scholarship: 22/05723-0 - The configuration and regulation of circadian rhythms in workers of stingless bees (Melipona quadrifasciata), BP.IC

Abstract

The regulatory circuitry of the molecular clock that generates circadian activity rhythms shows a striking feature in the workers of the highly eusocial honey bees. While caring for the brood, the workers are arrhythmic in their behaviors, and the genes composing the core-loop module of the clock do not oscillate in their expression. They only become rhythmic once they become foragers. To understand whether this is an idiosyncracy related to the reproductive biology of Apis mellifera, or whether this is a more general characteristic associated with the highly eusocial lifestyle, we started to investigate this phenomenon in the stingless bee Melipona quadrifasciata. We found that the expression of only one of the four core-loop genes, period, shows a circadian rhythm in nurse bees, while two show oscillation in the older foragers, both sampled from within the colony context. Strikingly, this configuration appeared inversed when the workers were synchronized for two days outside of the colony context. We believe that the neuropeptide Pigment Dispersing Factor (PDF), which serves a role in both the input and output pathways of the molecular clock in insects, may be a key factor to explain this switch between rhythmicity and arrhythmicity. Hence, in the current project we propose to investigate the anatomical architecture of Period and the PDF-expressing neurons in M. quadrifasciata workers using Fluorescence in situ Hybridization and immunofluorescence methods. These methods are well established at the University of Würzburg, Germany, an internationally renowned center of excellence in chronobiology research on insects, and the candidate will perform these experiments there, during his 4-months stay in the laboratory of Prof. Dr. Ricarda Scheiner and Dr. Katharina Beer. (AU)