WP3 (metabolic chronobiology) includes a number of approaches focusing on metabolism, growth and survival in D. melanogaster, D suzukii, housefly and black soldier fly.
WP3 (DC9; UM) / Integration of sleep and feeding with the circadian clock and metabolism in Drosophila melanogaster
Objectives: To understand how fruitflies adjust metabolic rate and sleep/wake cycles with the environment and circadian clock. By definition, the metabolic rate is the amount of energy used per unit of time. Therefore, a ‘lethargic’, or sleep state, is associated with a low, and wakefulness with a high metabolic rate. Hence, feeding behaviours, which include hunger-driven locomotion, also lead to an increase of metabolic rate. Furthermore, the metabolic rate is positively correlated with temperature increase. Interestingly, the two daily periods of inactivity, the siesta, which is a postprandial lethargic state, and night sleep, respond in opposite manners to temperature. While warm temperatures disrupt night sleep as expected, siesta sleep improves, suggesting that higher temperatures do not always correlate with higher metabolic rate. Interestingly, we have observed that at warm temperatures flies are more active and eat more in the morning before taking their siesta, compared to colder temperatures. Hence, depending on time of day, flies either increase their metabolic rate via locomotion and feeding (early morning), or fall asleep and reduce their metabolic rate (siesta), indicating a role for the circadian clock. To understand how the circadian clock controls and integrates metabolism with the environment in insects, we will target two aspects of locomotor activity that are tightly linked to the metabolic state of the animal: 1) how hunger-driven locomotion/feeding is controlled (preliminary results indicate the involvement of the Target of Rapamicin Complex 1 pathway TORC1) and 2) once the insect has eaten, how can siesta sleep improve at warm temperatures. Our results will have important implications for the non-model insects also studied inthis consortium as we will be dissecting the relationship between the clock, hunger, metabolism and sleep, in particular for the two industrially relevant dipterans, the housefly and the soldier fly.
Supervisor(s):
Prof. Ralf Stanewsky
Dr. Angelique Lamaze
Planned secondment(s):
University of Würzburg, Germany, Prof. Christian Wegener, for calcium imaging and optogenetics
WP3 (DC11; CNR) / Mitochondrial and nuclear control of adaptive thermogenesis in insects: the role of UCPs and TNALPs from a circadian and seasonal perspective
Objectives: To characterise (at a genetic, molecular, physiological, and behavioural level in Drosophila) newly identified mechanisms controlling adaptive thermogenesis in insects. Thermogenesis contributes to the resistance of insects to unfavourable temperatures, and therefore has seasonal implications. Drosophila metabolism during larval stages is fuelled by
glycolysis and is uncoupled from ATP production due to the expression of the Uncoupling Protein 4C (UCP4C), which triggers heat generation at cold temperatures, thus favouring survival. We will study other genes and gene families whose products localize within mitochondria and are implicated in energy production and metabolism.
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Thermogenesis experiments will be performed (at larval, pupal and adult stages) in conditions allowing to simulate both circadian and seasonal influence. Temporal expression of all members of the Ucp (uncoupling proteins) gene family and members of the tissue-nonspecific (TN) Alp (alkaline phosphatase) gene family (TNAPs) will be studied. Some of the TNAPs encoding genes, which we have already been implicated in the adaptive phenotype of flies, have counterparts in mammals contributing tothermogenesis by hydrolysis of phosphocreatine, which initiates a futile cycle (FCC) of creatine dephosphorylation and phosphorylation. Thermogenesis will be assessed in mutants as well as in KO/KDs of these genes using temperature and photoperiod to mimic the course of the seasons. Functional characterization of their products will be undertaken, and the effects on body temperature will be monitored in vivo by thermography. Further, as ROS (reactive oxygenspecies) production in mammals activates P38 kinase which, in turn, increases UCP1 expression (the only bona fide uncoupling protein in mammals) andthermogenesis, the possibility that a similar pathway also exists in Drosophila will be explored. This is a reasonable possibility asthe P38 MAP kinase gene family has been identified in Drosophila and we have previously shown that elevated ROS production increases levels of UCP4B and UCP4C in Drosophila. A comprehensive mechanistic model of adaptive thermogenesis in insects will be formulated, encompassing and integrating the roles of both mitochondrial UCPs and ALPs, as well as that of ROS. The model will be tested also in pest species.
Supervisor(s):
Prof. Rodolfo Costa
Prof. Carlo Viscomi
Planned secondment(s):
University of Leicester, Prof. Charalambos Kyriacou and Prof. Ezio Rosato, for the experiments with pest species
WP3 (DC14; JU) / The impact of dopaminergic system metabolism on circadian clock neurons
Objectives: To study the connection between circadian clock and dopaminergic system. Parkinson’s disease (PD) is one of the most common neurodegenerative disorders, caused by both genetics and environmental factors. It is an age-dependent
neurodegenerative disorder characterized by a progressive loss of dopaminergic neurons. Among the most common manifestations of PD are sleep problems, which affect quality of life and daytime functioning. Several lines of evidence
suggest that one of the reasons for sleep problems in patients with PD is circadian dysfunction.
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Drosophila serves as a great model for studying the link between the clock and dopaminergic cells physiology in health and Parkinson’s disease model. It was previously shown that circadian clock disruption promotes neurodegeneration. On the other hand, our preliminary data showed that PD model flies have disrupted circadian plasticity of clock neuron terminals. The aim of this project is to clarify the effect of dopaminergic cells dysfunction on the proper working of clock machinery during PD progression. Using transgenic flies we will manipulate the expression level of selected genes to decrease the dopamine signaling and we will examine the circadian plasticity of clock neurons’ terminals. In parallel, the level and quality of sleep of these strains will be examined. In this way, we will be able to draw the pathways that are involved in the regulation of main clock physiology through dopaminergic cells. Among genes selected to silence in dopaminergic cells are those involved in synaptic connection (i.e. brp) and dopamine production (ple). Furthermore, we will silence dopamine receptors on clock neurons. Finally, we will induce PD progression using park gene silencing in dopaminergic cells, and we will check the effect on clock neuron functioning.
Supervisor(s):
Dr. Milena Damulewicz
Planned secondment(s):
University of Leicester, UK, Prof. Ezio Rosato, the network properties of the circadian clock