Thermal stress depletes energy reserves in Drosophila.

Understanding how environmental temperature affects metabolic and physiological functions is of crucial importance to assess the impacts of climate change on organisms. Here, we used different laboratory strains and a wild-caught population of the fruit fly Drosophila melanogaster to examine the effect of temperature on the body energy reserves of an ectothermic organism. We found that permanent ambient temperature elevation or transient thermal stress causes significant depletion of body fat stores. Surprisingly, transient thermal stress induces a lasting “memory effect” on body fat storage, which also reduces survivorship of the flies upon food deprivation later after stress exposure. Functional analyses revealed that an intact heat-shock response is essential to protect flies from temperature-dependent body fat decline. Moreover, we found that the temperature-dependent body fat reduction is caused at least in part by apoptosis of fat body cells, which might irreversibly compromise the fat storage capacity of the flies. Altogether, our results provide evidence that thermal stress has a significant negative impact on organismal energy reserves, which in turn might affect individual fitness

The obesity-related adipokinetic hormone controls feeding and expression of neuropeptide regulators of Drosophila metabolism.

Homeostasis of circulating and storage energy reserves in mammals is dependent on the antagonistically acting insulin and glucagon signaling. In the model organism Drosophila melanogaster, this function is executed by the insulin-like peptides and the glucagon-like Adipokinetic hormone (AKH). Loss of Drosophila AKH results in the adulthood-specific onset of obesity coupled with hypoglycemia. However, apart from the role of AKH in the lipid mobilization, the physiological and endocrine underpinnings of the AKH deficiency-triggered obesity are unknown. Here, we investigate the role of AKH in feeding and metabolic rate control, and address the interactions of this hormone with other endocrine regulators of fly metabolism. Via in vivo gain- and loss-of-function analyses, we show that despite its anti-obesity effects, AKH is an orexigenic peptide. Moreover, AKH also affects expression of orexigenic factors CCHamide-2 and neuropeptide F. In addition, AKH regulates metabolic genes like Corazonin, Limostatin, and Insulin-like peptides (Ilps) 2, 3, 5, and 6. Altogether, our work shows that the Drosophila AKH is a central regulator of energy homeostasis; next to its well-known role in the control of energy expenditure, this hormone controls also food intake, and expression of other endocrine regulators of fly metabolism. Practical applications: Basic research of the neuroendocrine regulation of metabolism in the fruit fly D. melanogaster has potential applications in both human medicine and insect pest control. The evolutionary conservation of the key metabolic pathways, together with the unprecedented choice of transgenic tools turned the fruit fly into a useful model to study human diseases, including obesity and diabetes. Based on the evolutionary conservation of AKH and glucagon functions, our investigations might provide useful hints regarding the physiological actions, and endocrine interactions of human glucagon, too. In addition, insect neuropeptides are emerging as important targets for the parasite and pest control; understanding of their regulatory networks has thus potential implications also in the development of novel insecticides

Reproductive and post-reproductive life history of wild-caught Drosophila melanogaster under laboratory conditions

The life history of the fruit fly (Drosophila melanogaster) is well understood, but fitness components are rarely measured by following single individuals over their lifetime, thereby limiting insights into lifetime reproductive success, reproductive senescence and post‐reproductive lifespan. Moreover, most studies have examined long‐ established laboratory strains rather than freshly caught individuals and may thus be confounded by adaptation to laboratory culture, inbreeding or mutation accumulation. Here, we have followed the life histories of individual females from three recently caught, non‐laboratory‐adapted wild populations of D. melanogaster. Populations varied in a number of life‐history traits, including ovariole number, fecundity, hatchability and lifespan. To describe individual patterns of age‐specific fecundity, we developed a new model that allowed us to distinguish four phases during a female's life: a phase of reproductive maturation, followed by a period of linear and then exponential decline in fecundity and, finally, a post‐ovipository period. Individual females exhibited clear‐cut fecundity peaks, which contrasts with previous analyses, and post‐peak levels of fecundity declined independently of how long females lived. Notably, females had a pronounced post‐reproductive lifespan, which on average made up 40% of total lifespan. Post‐reproductive lifespan did not differ among populations and was not correlated with reproductive fitness components, supporting the hypothesis that this period is a highly variable, random ‘add‐on’ at the end of reproductive life rather than a correlate of selection on reproductive fitness. Most life‐ history traits were positively correlated, a pattern that might be due to genotype by environment interactions when wild flies are brought into a novel laboratory environment but that is unlikely explained by inbreeding or positive mutational covariance caused by mutation accumulation

Developmental temperature affects thermal dependence of locomotor activity in Drosophila

Data used in the publication: Developmental temperature affects thermal dependence of locomotor activity in DrosophilaAuthors: Peter Klepsatel, Martina GálikováJournal of Thermal BiologyTHIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Crowding of Drosophila larvae affects lifespan and other life-history traits via reduced availability of dietary yeast

Raw data used in the publication: Crowding of Drosophila larvae affects lifespan and other life-history traits via reduced availability of dietary yeast Authors: Peter Klepsatel, Emanuel Procházka, Martina Gáliková Experimental Gerontolog

Spastic paraplegia-linked phospholipase PAPLA1 is necessary for development, reproduction, and energy metabolism in Drosophila.

The human PAPLA1 phospholipase family is associated with hereditary spastic paraplegia (HSP), a neurodegenerative syndrome characterized by progressive spasticity and weakness of the lower limbs. Taking advantage of a new Drosophila PAPLA1 mutant, we describe here novel functions of this phospholipase family in fly development, reproduction, and energy metabolism. Loss of Drosophila PAPLA1 reduces egg hatchability, pre-adult viability, developmental speed, and impairs reproductive functions of both males and females. In addition, our work describes novel metabolic roles of PAPLA1, manifested as decreased food intake, lower energy expenditure, and reduced ATP levels of the mutants. Moreover, PAPLA1 has an important role in the glycogen metabolism, being required for expression of several regulators of carbohydrate metabolism and for glycogen storage. In contrast, global loss of PAPLA1 does not affect fat reserves in adult flies. Interestingly, several of the PAPLA1 phenotypes in fly are reminiscent of symptoms described in some HSP patients, suggesting evolutionary conserved functions of PAPLA1 family in the affected processes. Altogether, this work reveals novel physiological functions of PAPLA1, which are likely evolutionary conserved from flies to humans

Energy Homeostasis Control in Drosophila Adipokinetic Hormone Mutants

Maintenance of biological functions under negative energy balance depends on mobilization of storage lipids and carbohydrates in animals. In mammals, glucagon and glucocorticoid signaling mobilizes energy reserves, whereas adipokinetic hormones (AKHs) play a homologous role in insects. Numerous studies based on AKH injections and correlative studies in a broad range of insect species established the view that AKH acts as master regulator of energy mobilization during development, reproduction, and stress. In contrast to AKH, the second peptide, which is processed from the Akh encoded prohormone [termed adipokinetic hormone precursor-related peptide (APRP)] is functionally orphan. APRP is discussed as ecdysiotropic hormone or as scaffold peptide during AKH prohormone processing. However, as in the case of AKH, final evidence for APRP functions requires genetic mutant analysis. Here we employed CRISPR/Cas9-mediated genome engineering to create AKH and AKH plus APRP-specific mutants in the model insect Drosophila melanogaster. Lack of APRP did not affect any of the tested steroid-dependent processes. Similarly, Drosophila AKH signaling is dispensable for ontogenesis, locomotion, oogenesis, and homeostasis of lipid or carbohydrate storage until up to the end of metamorphosis. During adulthood, however, AKH regulates body fat content and the hemolymph sugar level as well as nutritional and oxidative stress responses. Finally, we provide evidence for a negative autoregulatory loop in Akh gene regulation