Persistent epigenetic reprogramming of sweet taste by diet

The impact of sugar diet on humidity preference, survival, and host landing in mosquitoes

Mosquito-borne diseases have caused more than one million deaths each year. There is an urgent need to develop an effective way to reduce mosquito-host interaction to mitigate disease transmission. Sugar diets have long been linked to abnormal physiology in animals, making them potential candidates for mosquito control. Here, we show the impact of sugar diets on humidity preference and survival in Aedes aegypti and Culex pipiens . With two-choice assays between 100% and 75% relative humidity (RH), we demonstrate that the effect of sugar diets on humidity preference is species-specific where Ae. aegypti showed significant differences and the reduced effects were noted in Cx. pipiens . Among the sugar diets, arabinose significantly reduced the survival rate of mosquitoes even at low concentrations. Moreover, we found that host landing was not impacted by feeding on different sugar types. Our study suggests that specific sugar treatments could be applied to mosquito control by dampening their humidity preference and reducing their lifespan, thus reducing mosquito-borne disease transmission.

EPOP Restricts PRC2.1 Targeting to Chromatin by Directly Modulating Enzyme Complex Dimerization

Polycomb repressive complex 2 (PRC2) mediates developmental gene repression as two classes of holocomplexes, PRC2.1 and PRC2.2. EPOP is an accessory subunit specific to PRC2.1, which also contains PCL proteins. Unlike other accessory subunits that collectively facilitate PRC2 targeting, EPOP was implicated in an enigmatic inhibitory role, together with its interactor Elongin BC. We report an unusual molecular mechanism whereby EPOP regulates PRC2.1 by directly modulating its oligomerization state. EPOP disrupts the PRC2.1 dimer and weakens its chromatin association, likely by disabling the avidity effect conferred by the dimeric complex. Congruently, an EPOP mutant specifically defective in PRC2 binding enhances genome-wide enrichments of MTF2 and H3K27me3 in mouse epiblast-like cells. Elongin BC is largely dispensable for the EPOP-mediated inhibition of PRC2.1. EPOP defines a distinct subclass of PRC2.1, which uniquely maintains an epigenetic program by preventing the over-repression of key gene regulators along the continuum of early differentiation.

Fat- and sugar-induced signals regulate sweet and fat taste perception in Drosophila

In this study, we investigate the interplay between taste perception and macronutrients. While sugar's and protein's self-regulation of taste perception is known, the role of fat remains unclear. We reveal that in Drosophila, fat overconsumption reduces fatty acid taste in favor of sweet perception. Conversely, sugar intake increases fatty acid perception and suppresses sweet taste. Genetic investigations show that the sugar signal, gut-secreted Hedgehog, suppresses sugar taste and enhances fatty acid perception. Fat overconsumption induces unpaired 2 (Upd2) secretion from adipose tissue to the hemolymph. We reveal taste neurons take up Upd2, which triggers Domeless suppression of fatty acid perception. We further show that the downstream JAK/STAT signaling enhances sweet perception and, via Socs36E, fine-tunes Domeless activity and the fatty acid taste perception. Together, our results show that sugar regulates Hedgehog signaling and fat induces Upd2 signaling to balance nutrient intake and to regulate sweet and fat taste perception.

Exposure to high-sugar diet induces transgenerational changes in sweet sensitivity and feeding behavior via H3K27me3 reprogramming

Human health is facing a host of new threats linked to unbalanced diets, including high-sugar diet (HSD), which contributes to the development of both metabolic and behavioral disorders. Studies have shown that diet-induced metabolic dysfunctions can be transmitted to multiple generations of offspring and exert long-lasting health burden. Meanwhile, whether and how diet-induced behavioral abnormalities can be transmitted to the offspring remains largely unclear. Here, we showed that ancestral HSD exposure suppressed sweet sensitivity and feeding behavior in the offspring in Drosophila. These behavioral deficits were transmitted through the maternal germline and companied by the enhancement of H3K27me3 modifications. PCL-PRC2 complex, a major driver of H3K27 trimethylation, was upregulated by ancestral HSD exposure, and disrupting its activity eliminated the transgenerational inheritance of sweet sensitivity and feeding behavior deficits. Elevated H3K27me3 inhibited the expression of a transcriptional factor Cad and suppressed sweet sensitivity of the sweet-sensing gustatory neurons, reshaping the sweet perception and feeding behavior of the offspring. Taken together, we uncovered a novel molecular mechanism underlying behavioral abnormalities spanning multiple generations of offspring upon ancestral HSD exposure, which would contribute to the further understanding of long-term health risk of unbalanced diet.

N6-adenosine methylation controls the translation of insulin mRNA

Control of insulin mRNA translation is crucial for energy homeostasis, but the mechanisms remain largely unknown. We discovered that insulin mRNAs across invertebrates, vertebrates and mammals feature the modified base N6-methyladenosine (m6A). In flies, this RNA modification enhances insulin mRNA translation by promoting the association of the transcript with polysomes. Depleting m6A in Drosophila melanogaster insulin 2 mRNA (dilp2) directly through specific 3' untranslated region (UTR) mutations, or indirectly by mutating the m6A writer Mettl3, decreases dilp2 protein production, leading to aberrant energy homeostasis and diabetic-like phenotypes. Together, our findings reveal adenosine mRNA methylation as a key regulator of insulin protein synthesis with notable implications for energy balance and metabolic disease.

Polygenic adaptation to overnutrition reveals a role for cholinergic signaling in longevity

Overnutrition by high-sugar (HS) feeding reduces both the lifespan and healthspan across taxa. Pressuring organisms to adapt to overnutrition can highlight genes and pathways important for the healthspan in stressful environments. We used an experimental evolution approach to adapt four replicate, outbred population pairs of Drosophila melanogaster to a HS or control diet. Sexes were separated and aged on either diet until mid-life, then mated to produce the next generation, allowing enrichment for protective alleles over time. All HS-selected populations increased their lifespan and were therefore used as a platform to compare allele frequencies and gene expression. Pathways functioning in the nervous system were overrepresented in the genomic data and showed evidence for parallel evolution, although very few genes were the same across replicates. Acetylcholine-related genes, including the muscarinic receptor mAChR-A, showed significant changes in allele frequency in multiple selected populations and differential expression on a HS diet. Using genetic and pharmacological approaches, we show that cholinergic signaling affects Drosophila feeding in a sugar-specific fashion. Together, these results suggest that adaptation produces changes in allele frequencies that benefit animals under conditions of overnutrition and that it is repeatable at the pathway level.

Effects of hunger on neuronal histone modifications slow aging in Drosophila

Hunger is an ancient drive, yet the molecular nature of pressures of this sort and how they modulate physiology are unknown. We find that hunger modulates aging in Drosophila. Limitation of branched-chain amino acids (BCAAs) or activation of hunger-promoting neurons induced a hunger state that extended life span despite increased feeding. Alteration of the neuronal histone acetylome was associated with BCAA limitation, and preventing these alterations abrogated the effect of BCAA limitation to increase feeding and extend life span. Hunger acutely increased feeding through usage of the histone variant H3.3, whereas prolonged hunger seemed to decrease a hunger set point, resulting in beneficial consequences for aging. Demonstration of the sufficiency of hunger to extend life span reveals that motivational states alone can be deterministic drivers of aging.

Is Type 2 Diabetes Mellitus a Behavioural Disorder? An Evidence Review for Type 2 Diabetes Mellitus Prevention and Remission through Lifestyle Modification

The prevalence of type 2 diabetes mellitus (T2DM) is steadily rising worldwide due to an increasingly sedentary lifestyle combined with unhealthy food habits. Currently, the burden of diabetes on healthcare systems is unprecedented and rising daily. Several observational studies and randomized controlled trials provide clinical evidence that T2DM remission is possible by adopting dietary interventions and a strict exercise training protocol. Notably, these studies provide ample evidence for remission in patients with T2DM or for prevention in those with risk factors for the disease through various non-pharmacological behavioural interventions. In this article, we present two clinical cases of individuals who showed remission from T2DM/prediabetes via behavioural changes, especially through the adoption of a low-energy diet and exercise. We also discuss the recent advances in T2DM and obesity research, focusing on nutritional interventions and exercise and their benefits for weight loss, improved metabolic profile, enhanced glycaemic control and remission of diabetes.

Health relevance of lowering postprandial glycaemia in the paediatric population through diet': results from a multistakeholder workshop

To summarize current knowledge and gaps regarding the role of postprandial glycaemic response in the paediatric population, a workshop was organized in June 2021 by the European branch of the International Life Science Institute (ILSI). This virtual event comprised of talks given by experts followed by in-depth discussions in breakout sessions with workshop participants. The main pre-specified topics addressed by the workshop organizing committee to the invited speakers and the workshop participants were: (1) the role of glycaemic responses for paediatric health, based on mechanistic insights from animal and human data, and long-term evidence from observational and intervention studies in paediatric populations, and (2) changes in metabolism and changes in dietary needs from infancy to adolescence. Each talk as well as the discussions were summarised, including the main identified research gaps. The workshop led to the consensus on the crucial role on health of postprandial glycaemic response in paediatric population. However, a lack of scientific data has been identified regarding detailed glucose and insulin profiles in response to foods commonly consumed by paediatric populations, as well as a lack of long-term evidence including the need for suitable predictors during childhood and adolescence to anticipate health effects during adulthood.

Nutrigenomic regulation of sensory plasticity

Diet profoundly influences brain physiology, but how metabolic information is transmuted into neural activity and behavior changes remains elusive. Here, we show that the metabolic enzyme O-GlcNAc Transferase (OGT) moonlights on the chromatin of the D. melanogaster gustatory neurons to instruct changes in chromatin accessibility and transcription that underlie sensory adaptations to a high-sugar diet. OGT works synergistically with the Mitogen Activated Kinase/Extracellular signal Regulated Kinase (MAPK/ERK) rolled and its effector stripe (also known as EGR2 or Krox20) to integrate activity information. OGT also cooperates with the epigenetic silencer Polycomb Repressive Complex 2.1 (PRC2.1) to decrease chromatin accessibility and repress transcription in the high-sugar diet. This integration of nutritional and activity information changes the taste neurons' responses to sugar and the flies' ability to sense sweetness. Our findings reveal how nutrigenomic signaling generates neural activity and behavior in response to dietary changes in the sensory neurons.

High sucrose consumption decouples intrinsic and synaptic excitability of AgRP neurons without altering body weight

BACKGROUND/OBJECTIVE

As the obesity epidemic continues, the understanding of macronutrient influence on central nervous system function is critical for understanding diet-induced obesity and potential therapeutics, particularly in light of the increased sugar content in processed foods. Previous research showed mixed effects of sucrose feeding on body weight gain but has yet to reveal insight into the impact of sucrose on hypothalamic functioning. Here, we explore the impact of liquid sucrose feeding for 12 weeks on body weight, body composition, caloric intake, and hypothalamic AgRP neuronal function and synaptic plasticity.

METHODS

Patch-clamp electrophysiology of hypothalamic AgRP neurons, metabolic phenotyping and food intake were performed on C57BL/6J mice.

RESULTS

While mice given sugar-sweetened water do not gain significant weight, they do show subtle differences in body composition and caloric intake. When given sugar-sweetened water, mice show similar alterations to AgRP neuronal excitability as in high-fat diet obese models. Increased sugar consumption also primes mice for increased caloric intake and weight gain when given access to a HFD.

CONCLUSIONS

Our results show that elevated sucrose consumption increased activity of AgRP neurons and altered synaptic excitability. This may contribute to obesity in mice and humans with access to more palatable (HFD) diets.

Chemosensory Ability and Sensitivity in Health and Disease: Epigenetic Regulation and COVID-19

Throughout the animal kingdom, our two chemical senses, olfaction and gustation, are defined by two primary factors: genomic architecture of the organisms and their living environment. During the past three years of the global COVID-19 pandemic, these two sensory modalities have drawn much attention at the basic science and clinical levels because of the strong association of olfactory and gustatory dysfunction with viral infection. Loss of our sense of smell alone, or together with a loss of taste, has emerged as a reliable indicator of COVID-19 infection. Previously, similar dysfunctions have been detected in a large cohort of patients with chronic conditions. The research focus remains on understanding the persistence of olfactory and gustatory disturbances in the post-infection phase, especially in cases with long-term effect of infection (long COVID). Also, both sensory modalities show consistent age-related decline in studies aimed to understand the pathology of neurodegenerative conditions. Some studies using classical model organisms show an impact on neural structure and behavior in offspring as an outcome of parental olfactory experience. The methylation status of specific odorant receptors, activated in parents, is passed on to the offspring. Furthermore, experimental evidence indicates an inverse correlation of gustatory and olfactory abilities with obesity. Such diverse lines of evidence emerging from basic and clinical research studies indicate a complex interplay of genetic factors, evolutionary forces, and epigenetic alterations. Environmental factors that regulate gustation and olfaction could induce epigenetic modulation. However, in turn, such modulation leads to variable effects depending on genetic makeup and physiological status. Therefore, a layered regulatory hierarchy remains active and is passed on to multiple generations. In the present review, we attempt to understand the experimental evidence that indicates variable regulatory mechanisms through multilayered and cross-reacting pathways. Our analytical approach will add to enhancement of prevailing therapeutic interventions and bring to the forefront the significance of chemosensory modalities for the evaluation and maintenance of long-term health.

Nutritional geometry framework of sucrose taste in Drosophila

Dietary protein (P) and carbohydrate (C) have a major impact on sweet taste sensation. However, it remains unclear whether the balance of P and C influences sweet taste sensitivity. Here, we use the nutritional geometry framework (NGF) to address the interaction of protein and carbohydrates and on sweet taste using Drosophila as a model. Our results reveal that high-protein, low-carbohydrate (HPLC) diets sensitize to sweet taste and low-protein, high-carbohydrate (LPHC) diets desensitize sweet taste in both male and female flies. We further investigate the underlying mechanisms of these two diets' effect on sweet taste using RNA sequencing. When compared to the LPHC diet, the mRNA expression of genes involved in the metabolism of glycine, serine, and threonine is significantly upregulated in the HPLC diet, suggesting these amino acids may mediate sweet taste perception. We further find that sweet sensitization occurs in flies fed with the LPHC diet supplemented with serine and threonine. Our study demonstrates that sucrose taste sensitivity is affected by the balance of dietary protein and carbohydrates possibly through changes in serine and threonine.

Food memory circuits regulate eating and energy balance

In mammals, learning circuits play an essential role in energy balance by creating associations between sensory cues and the rewarding qualities of food. This process is altered by diet-induced obesity, but the causes and mechanisms are poorly understood. Here, we exploited the relative simplicity and wealth of knowledge about the D. melanogaster reinforcement learning network, the mushroom body, in order to study the relationship between the dietary environment, dopamine-induced plasticity, and food associations. We show flies that are fed a high-sugar diet cannot make associations between sensory cues and the rewarding properties of sugar. This deficit was caused by diet exposure, not fat accumulation, and specifically by lower dopamine-induced plasticity onto mushroom body output neurons (MBONs) during learning. Importantly, food memories dynamically tune the output of MBONs during eating, which instead remains fixed in sugar-diet animals. Interestingly, manipulating the activity of MBONs influenced eating and fat mass, depending on the diet. Altogether, this work advances our fundamental understanding of the mechanisms, causes, and consequences of the dietary environment on reinforcement learning and ingestive behavior.

Experience-dependent plasticity of gustatory insular cortex circuits and taste preferences

Early experience with food influences taste preference in adulthood. How gustatory experience influences development of taste preferences and refinement of cortical circuits has not been investigated. Here, we exposed weanling mice to an array of taste solutions and determined the effects on the preference for sweet in adulthood. We demonstrate an experience-dependent shift in sucrose preference persisting several weeks following the termination of exposure. A shift in sucrose palatability, altered neural responsiveness to sucrose, and inhibitory synaptic plasticity in the gustatory portion of the insular cortex (GC) were also induced. The modulation of sweet preference occurred within a restricted developmental window, but restoration of the capacity for inhibitory plasticity in adult GC reactivated the sensitivity of sucrose preference to taste experience. Our results establish a fundamental link between gustatory experience, sweet preference, inhibitory plasticity, and cortical circuit function and highlight the importance of early life nutrition in setting taste preferences.

Hedgehog-mediated gut-taste neuron axis controls sweet perception in Drosophila

Dietary composition affects food preference in animals. High sugar intake suppresses sweet sensation from insects to humans, but the molecular basis of this suppression is largely unknown. Here, we reveal that sugar intake in Drosophila induces the gut to express and secrete Hedgehog (Hh) into the circulation. We show that the midgut secreted Hh localize to taste sensilla and suppresses sweet sensation, perception, and preference. We further find that the midgut Hh inhibits Hh signalling in the sweet taste neurons. Our electrophysiology studies demonstrate that the midgut Hh signal also suppresses bitter taste and some odour responses, affecting overall food perception and preference. We further show that the level of sugar intake during a critical window early in life, sets the adult gut Hh expression and sugar perception. Our results together reveal a bottom-up feedback mechanism involving a "gut-taste neuron axis" that regulates food sensation and preference.

John JC, Melvin RG, Turner N, Morris MJ, Ballard JWO. Ancestral dietary change alters the development of Drosophila larvae through MAPK signalling

Studies in a broad range of animal species have revealed phenotypes that are caused by ancestral life experiences, including stress and diet. Ancestral dietary macronutrient composition and quantity (over- and under-nutrition) have been shown to alter descendent growth, metabolism and behaviour. Molecules have been identified in gametes that are changed by ancestral diet and are required for transgenerational effects. However, there is less understanding of the developmental pathways altered by inherited molecules during the period between fertilization and adulthood. To investigate this non-genetic inheritance, we exposed great grand-parental and grand-parental generations to defined protein to carbohydrate (P:C) dietary ratios. Descendent developmental timing was consistently faster in the period between the embryonic and pupal stages when ancestors had a higher P:C ratio diet. Transcriptional analysis revealed extensive and long-lasting changes to the MAPK signalling pathway, which controls growth rate through the regulation of ribosomal RNA transcription. Pharmacological inhibition of both MAPK and rRNA pathways recapitulated the ancestral diet-induced developmental changes. This work provides insight into non-genetic inheritance between fertilization and adulthood.

High-sucrose diet exposure is associated with selective and reversible alterations in the rat peripheral taste system

Elevated sugar consumption is associated with an increased risk for metabolic diseases. Whereas evidence from humans, rodents, and insects suggests that dietary sucrose modifies sweet taste sensation, understanding of peripheral nerve or taste bud alterations is sparse. To address this, male rats were given access to 30% liquid sucrose for 4 weeks (sucrose rats). Neurophysiological responses of the chorda tympani (CT) nerve to lingual stimulation with sugars, other taste qualities, touch, and cold were then compared with controls (access to water only). Morphological and immunohistochemical analyses of fungiform papillae and taste buds were also conducted. Sucrose rats had substantially decreased CT responses to 0.15-2.0 M sucrose compared with controls. In contrast, effects were not observed for glucose, fructose, maltose, Na saccharin, NaCl, organic acid, or umami, touch, or cold stimuli. Whereas taste bud number, size, and innervation volume were unaffected, the number of PLCβ2+ taste bud cells in the fungiform papilla was reduced in sucrose rats. Notably, the replacement of sucrose with water resulted in a complete recovery of all phenotypes over 4 weeks. The work reveals the selective and modality-specific effects of sucrose consumption on peripheral taste nerve responses and taste bud cells, with implications for nutrition and metabolic disease risk. VIDEO ABSTRACT.

Brain regulation of hunger and motivation: The case for integrating homeostatic and hedonic concepts and its implications for obesity and addiction

Obesity and other eating disorders are marked by dysregulations to brain metabolic, hedonic, motivational, and sensory systems that control food intake. Classic approaches in hunger research have distinguished between hedonic and homeostatic processes, and have mostly treated these systems as independent. Hindbrain structures and a complex network of interconnected hypothalamic nuclei control metabolic processes, energy expenditure, and food intake while mesocorticolimbic structures are though to control hedonic and motivational processes associated with food reward. However, it is becoming increasingly clear that hedonic and homeostatic brain systems do not function in isolation, but rather interact as part of a larger network that regulates food intake. Incentive theories of motivation provide a useful route to explore these interactions. Adapting incentive theories of motivation can enable researchers to better how motivational systems dysfunction during disease. Obesity and addiction are associated with profound alterations to both hedonic and homeostatic brain systems that result in maladaptive patterns of consumption. A subset of individuals with obesity may experience pathological cravings for food due to incentive sensitization of brain systems that generate excessive 'wanting' to eat. Further progress in understanding how the brain regulates hunger and appetite may depend on merging traditional hedonic and homeostatic concepts of food reward and motivation.

Sex Differences at Early Old Stage in Glycolipid Metabolism and Fatty Liver in Offspring Prenatally Exposed to Chinese Great Famine

Background

About 50 years ago, Chinese Great Famine (CGF) affected the entire population in China, and its long-term influence on the offspring has attracted significant attention for research. However, information on possible metabolic differences between sexes is limited. This study explored whether there might be sex differences in the risks of development of glucolipid metabolic dysfunction and fatty liver following prenatal exposure to CGF.

Materials and Methods

There were 11,417 subjects around 55 years of age (6,661 women and 4,756 men). They were divided as the exposed group in which the fetal stage was in CGF, and the unexposed group included those born after CGF. Analysis focused on comparisons between sexes.

Results

Compared to the unexposed group, the BMI and triglyceride (P < 0.05) in men were higher in exposed group, while waist circumference and blood sugar (P < 0.05) in the exposed women were significantly higher. With the ages being properly balanced, the risks of glycolipid metabolic dysfunction were significantly higher in both men and women in the exposed than in the unexposed group (P < 0.001). Prenatal exposure to CGF significantly increased risks of abnormal BMI (P < 0.001, 95% CI: 2.305–2.93), blood sugar (P < 0.05, 95% CI: 1.050–1.401), triglycerides (P < 0.05, 95% CI: 1.006–1.245), and fatty liver (P < 0.001, 95% CI: 1.121–1.390) in men, and increased risks of abnormal blood sugar (P < 0.05, 95% CI: 1.024–1.689) and positive urine sugar (P < 0.05, 95% CI: 1.062–6.211) in women. Height and body weight were either the same or higher in the exposed subjects compared with the unexposed ones, regardless of sexes.

Conclusion

This study is the first to identify sex differences in the long-term effects of CGF on metabolism and fatty liver. Importance of the findings include the benefits of prescribing medicine for the early prevention of certain diseases for each sex before aging based on the differences revealed. This study also shows “catch-up growth” in the offspring prenatally exposed to CGF as possible mechanisms underlying the long-term effects.

Interplay between metabolic energy regulation and memory pathways in Drosophila

Regulating energy metabolism is critical to maintain homeostasis of cellular and systemic functions. In the brain, specialised centres for energy storage regulation finely communicate with the periphery and integrate signals about internal states. As a result, the behavioural responses can be directly adjusted accordingly to the energetic demands. In the fruit fly Drosophila melanogaster, one of these regulatory centres is the mushroom bodies (MBs), a brain region involved in olfactory memory. The integration of metabolic cues by the MBs has a crucial impact on learned behaviour. In this review, we explore recent advances supporting the interplay between energy metabolism and memory establishment, as well as the instructive role of energy during the switch between memory phases.

Crème de la Créature: Dietary Influences on Behavior in Animal Models

In humans, alterations in cognitive, motivated, and affective behaviors have been described with consumption of processed diets high in refined sugars and saturated fats and with high body mass index, but the causes, mechanisms, and consequences of these changes remain poorly understood. Animal models have provided an opportunity to answer these questions and illuminate the ways in which diet composition, especially high-levels of added sugar and saturated fats, contribute to brain physiology, plasticity, and behavior. Here we review findings from invertebrate (flies) and vertebrate models (rodents, zebrafish) that implicate these diets with changes in multiple behaviors, including eating, learning and memory, and motivation, and discuss limitations, open questions, and future opportunities.

Brain on food: The neuroepigenetics of nutrition

Humans have known for millennia that nutrition has a profound influence on health and disease, but it is only recently that we have begun mapping the mechanisms via which the dietary environment impacts brain physiology and behavior. Here we review recent evidence on the effects of energy-dense and methionine diets on neural epigenetic marks, gene expression, and behavior in invertebrate and vertebrate model organisms. We also discuss limitations, open questions, and future directions in the emerging field of the neuroepigenetics of nutrition.

The Panopticon-Assessing the Effect of Starvation on Prolonged Fly Activity and Place Preference

Animal behaviours are demonstrably governed by sensory stimulation, previous experience and internal states like hunger. With increasing hunger, priorities shift towards foraging and feeding. During foraging, flies are known to employ efficient path integration strategies. However, general long-term activity patterns for both hungry and satiated flies in conditions of foraging remain to be better understood. Similarly, little is known about how permanent contact chemosensory stimulation affects locomotion. To address these questions, we have developed a novel, simplistic fly activity tracking setup—the Panopticon. Using a 3D-printed Petri dish inset, our assay allows recording of walking behaviour, of several flies in parallel, with all arena surfaces covered by a uniform substrate layer. We tested two constellations of providing food: (i) in single patches and (ii) omnipresent within the substrate layer. Fly tracking is done with FIJI, further assessment, analysis and presentation is done with a custom-built MATLAB analysis framework. We find that starvation history leads to a long-lasting reduction in locomotion, as well as a delayed place preference for food patches which seems to be not driven by immediate hunger motivation.

Confection Confusion: Interplay Between Diet, Taste, and Nutrition

Although genetics shapes our sense of taste to prefer some foods over others, taste sensation is plastic and changes with age, disease state, and nutrition. We have known for decades that diet composition can influence the way we perceive foods, but many questions remain unanswered, particularly regarding the effects of chemosensory plasticity on feeding behavior. Here, we review recent evidence on the effects of high-nutrient diets, especially high dietary sugar, on sweet taste in vinegar flies, rodents, and humans, and discuss open questions about molecular and neural mechanisms and research priorities. We also consider ways in which diet-dependent chemosensory plasticity may influence food intake and play a role in the etiology of obesity and metabolic disease. Understanding the interplay between nutrition, taste sensation, and feeding will help us define the role of the food environment in mediating chronic disease and design better public health strategies to combat it.