Dynamic readout of the Hh gradient in the Drosophila wing disc reveals pattern-specific tradeoffs between robustness and precision.

Understanding the principles underlying the design of robust, yet flexible patterning systems is a key problem in developmental biology. In the Drosophila wing, Hedgehog (Hh) signaling determines patterning outputs using dynamical properties of the Hh gradient. In particular, the pattern of collier (col) is established by the steady-state Hh gradient, whereas the pattern of decapentaplegic (dpp), is established by a transient gradient of Hh known as the Hh overshoot. Here, we use mathematical modeling to suggest that this dynamical interpretation of the Hh gradient results in specific robustness and precision properties. For instance, the location of the anterior border of col, which is subject to self-enhanced ligand degradation is more robustly specified than that of dpp to changes in morphogen dosage, and we provide experimental evidence of this prediction. However, the anterior border of dpp expression pattern, which is established by the overshoot gradient is much more precise to what would be expected by the steady-state gradient. Therefore, the dynamical interpretation of Hh signaling offers tradeoffs between robustness and precision to establish tunable patterning properties in a target-specific manner.

The exocyst complex controls multiple events in the pathway of regulated exocytosis.

Eukaryotic cells depend on exocytosis to direct intracellularly synthesized material toward the extracellular space or the plasma membrane, so exocytosis constitutes a basic function for cellular homeostasis and communication between cells. The secretory pathway includes biogenesis of secretory granules (SGs), their maturation and fusion with the plasma membrane (exocytosis), resulting in release of SG content to the extracellular space. The larval salivary gland of Drosophila melanogaster is an excellent model for studying exocytosis. This gland synthesizes mucins that are packaged in SGs that sprout from the trans-Golgi network and then undergo a maturation process that involves homotypic fusion, condensation, and acidification. Finally, mature SGs are directed to the apical domain of the plasma membrane with which they fuse, releasing their content into the gland lumen. The exocyst is a hetero-octameric complex that participates in tethering of vesicles to the plasma membrane during constitutive exocytosis. By precise temperature-dependent gradual activation of the Gal4-UAS expression system, we have induced different levels of silencing of exocyst complex subunits, and identified three temporarily distinctive steps of the regulated exocytic pathway where the exocyst is critically required: SG biogenesis, SG maturation, and SG exocytosis. Our results shed light on previously unidentified functions of the exocyst along the exocytic pathway. We propose that the exocyst acts as a general tethering factor in various steps of this cellular process.

Nicotine and Vape: Drugs of the Same Profile Flock Together.

Smoking, a major behavioral health burden, causes preventable and premature deaths globally. Nicotine, the addictive component present in tobacco products and Electronic cigarettes (E-cigarettes, vape), can bind to nicotinic acetylcholine receptors in the brain to trigger a dopamine release that reinforces smoking. Despite the widespread usage of nicotine, its mechanisms of toxicity, particularly in e-cigarettes, are poorly understood. Using Drosophila melanogaster as a model organism, this study aims to investigate the mechanism of the toxicity of nicotine and vape. Behavioral parameters, oxidative stress indicators, mRNA expression levels of Dopamine 1- receptor 1 (Dop1R1), Acetyl-coenzyme A synthetase (AcCoAs), and apoptotic proteins were assessed in the flies after a 5-day exposure to varying concentrations of nicotine (0.15, 0.25, and 0.35 mg/mL diet) and vape (0.06, 0.08, and 0.12 mg/mL diet). Furthermore, Gas Chromatography-Mass Spectrometry (GC/MS) and Gas Chromatography-Flame Ionization Detection (GC/FID) analyzes were conducted to gain more insight on the composition of the vape used in study. Findings indicate that both nicotine and vape exposure significantly reduced lifespan, impaired locomotor activity, and disrupted sleep patterns. Notably, nicotine exposure stimulated Dop1R1 transcription and altered Acetyl-CoA gene expression, impacting the viability and behavior of the flies. Elevated levels of reactive oxygen biomarkers were observed, contributing to cellular damage through oxidative stress and apoptotic mechanisms mediated by the Reaper and DIAP1 proteins. Additionally, the composition analysis of vape liquid revealed the presence of propylene glycol, nicotine, methyl esters, and an unidentified compound. This study highlights the complex interplay between nicotine, gene expression, and physiological responses in Drosophila.

Assessing the Effects of Palm Oil Consumption on Life Expectancy, Metabolic Markers, and Oxidative Stress in Drosophila melanogaster.

Palm oil is the world's second most consumed vegetable oil, sourced from the tropical palm tree Elaeis guineensis. Its consumption has been associated with a higher incidence of cardiovascular disease, largely due to its elevated palmitic acid content, however those studies are contradictory and inconclusive. Wishing to contribute to this issue, the present study aims to investigate the molecular and toxicological effects of this oil and the involvement of oxidative stress, given its role in metabolic dysfunctions using Drosophila melanogaster. This study examines survival rates, and locomotor performance, oxidative status by analysis of lipid peroxidation, ROS formation, thiol levels and antioxidant enzyme activity, and metabolic parameters such as cholesterol and triglycerides, glucose, trehalose and glycogen levels. Exposure to palm oil concentrations of 10% and 30% resulted in a shortened lifespan, reduced locomotor performance, and increased lipid peroxidation, with lower thiol levels and antioxidant enzyme modulation. Cholesterol levels was increased whereas energetic fuels as glucose and glycogen and trehalose were decreased mainly after 10 days of exposure. These findings underscore the detrimental effects of high-fat diets containing palm oil on lifespan, antioxidant defenses, and metabolism in Drosophila melanogaster. This data highlights the potential risk associated with the habitual consumption of palm oil in the daily diet by population, particularly concerning cardiovascular health and metabolic function.

EMC1 Is Required for the Sarcoplasmic Reticulum and Mitochondrial Functions in the Drosophila Muscle.

EMC1 is part of the endoplasmic reticulum (ER) membrane protein complex, whose functions include the insertion of transmembrane proteins into the ER membrane, ER-mitochondria contact, and lipid exchange. Here, we show that the Drosophila melanogaster EMC1 gene is expressed in the somatic musculature and the protein localizes to the sarcoplasmic reticulum (SR) network. Muscle-specific EMC1 RNAi led to severe motility defects and partial late pupae/early adulthood lethality, phenotypes that are rescued by co-expression with an EMC1 transgene. Motility impairment in EMC1-depleted flies was associated with aberrations in muscle morphology in embryos, larvae, and adults, including tortuous and misaligned fibers with reduced size and weakness. They were also associated with an altered SR network, cytosolic calcium overload, and mitochondrial dysfunction and dysmorphology that impaired membrane potential and oxidative phosphorylation capacity. Genes coding for ER stress sensors, mitochondrial biogenesis/dynamics, and other EMC components showed altered expression and were mostly rescued by the EMC1 transgene expression. In conclusion, EMC1 is required for the SR network's mitochondrial integrity and influences underlying programs involved in the regulation of muscle mass and shape. We believe our data can contribute to the biology of human diseases caused by EMC1 mutations.

Brazilian kefir fraction mitigates the Alzheimer-like phenotype in Drosophila melanogaster with ß-amyloid overexpression model.

Alzheimer's disease (AD) is a progressive neurodegenerative condition and the primary form of dementia among elderly people. The amyloidogenic hypothesis is the main theory that explains this phenomenon and describes the extracellular accumulation of amyloid beta (Aß) peptides. Model organisms such as Drosophila melanogaster have been utilized to improve the understanding of this disease and its treatment. This study evaluated the effects of peptide and metabolic fractions of Brazilian kefir on a strain of D. melanogaster that expresses human Aß peptide 1-42 in the eye. The parameters assessed included ommatidial organization, vacuole area, retinal thickness, and Aß peptide quantification. The present study revealed that the fractions, particularly the peptidic fraction, significantly reduced the vacuole area and increased the retina thickness in treated flies, indicating an improvement in neurodegeneration phenotype. The peptidic fraction was also found to alter Aß aggregation dynamics, inhibiting Aß fibril formation, as revealed by dynamic light scattering. This study demonstrated that kefir fractions, particularly the peptidic fraction < 10 kDa, have the potential to regulate Aß aggregation and alleviate neurodegeneration in a Drosophila melanogaster AD-like model. These findings suggest that kefir fractions could be viable for the bioprospection of novel drug prototypes for AD treatment, providing valuable insights into strategies targeting Aß aggregation and neurodegeneration in AD.

Drosophila in the study of hTBP protein interactions in the development and modeling of SCA17.

BACKGROUND: Protein interactions participate in many molecular mechanisms involved in cellular processes. The human TATA box binding protein (hTBP) interacts with Antennapedia (Antp) through its N-terminal region, specifically via its glutamine homopeptides. This PolyQ region acts as a binding site for other transcription factors under normal conditions, but when it expands, it generates spinocerebellar ataxia 17 (SCA17), whose protein aggregates in the brain prevent its correct functioning. OBJECTIVE: To determine whether the hTBP glutamine-rich region is involved in its interaction with homeoproteins and the role it plays in the formation of protein aggregates in SCA17. MATERIAL AND METHODS: We characterized hTBP interaction with other homeoproteins using BiFC, and modeled SCA17 in Drosophila melanogaster by targeting hTBPQ80 to the fly brain using UAS/GAL4. RESULTS: There was hTBP interaction with homeoproteins through its glutamine-rich region, and hTBP protein aggregates with expanded glutamines were found to affect the locomotor capacity of flies. CONCLUSIONS: The study of hTBP interactions opens the possibility for the search for new therapeutic strategies in neurodegenerative pathologies such as SCA17.

ANTECEDENTES: Las interacciones proteicas participan en una gran cantidad de mecanismos moleculares que rigen los procesos celulares. La proteína de unión a la caja TATA humana (hTBP) interacciona con Antennapedia (Antp) a través de su extremo N-terminal, específicamente a través de sus homopéptidos de glutaminas. Esta región PolyQ sirve como sitio de unión a factores de transcripción en condiciones normales, pero cuando se expande genera la ataxia espinal cerebelosa 17 (SCA17), cuyos agregados proteicos en el cerebro impiden su funcionamiento correcto. OBJETIVO: Determinar si la región rica en glutaminas de hTBP interviene en su interacción con homeoproteínas y el papel que tiene en la formación de agregados proteicos en SCA17. MATERIAL Y MÉTODOS: Se caracterizó la interacción de hTBP con otras homeoproteínas usando BiFC y se modeló SCA17 en Drosophila melanogaster dirigiendo hTBPQ80 al cerebro de las moscas usando UAS/GAL4. RESULTADOS: Existió interacción de hTBP con homeoproteínas a través de su región rica en glutaminas. Los agregados proteicos de hTBP con las glutaminas expandidas afectaron la capacidad locomotriz de las moscas. CONCLUSIONES: El estudio de las interacciones de hTBP abre la posibilidad para la búsqueda de nuevas estrategias terapéuticas en patologías neurodegenerativas como SCA17.

Developmental iron exposure induces locomotor alterations in Drosophila: Exploring potential association with oxidative stress.

Prenatal iron (Fe) exposure has been associated with learning and cognitive impairments, which may be linked to oxidative stress resulting from elevated Fe levels and harm to the vulnerable brain. Drosophila melanogaster has contributed to our understanding of molecular mechanisms involved in neurological conditions. This study aims to explore Fe toxicity during D. melanogaster development, assessing oxidative stress and investigating behaviors in flies that are related to neurological conditions in humans. To achieve this goal, flies were exposed to Fe during the developmental period, and biochemical and behavioral analyses were conducted. The results indicated that 20 mM Fe decreased fly hatching by 50 %. At 15 mM, Fe exposure increased lipid peroxidation, and GSH levels decreased starting from 5 mM of Fe. Superoxide Dismutase activity was enhanced at 15 mM, while Glutathione S-Transferase activity was inhibited from 5 mM. Although chronic Fe exposure did not alter acetylcholinesterase (AChE) activity, flies exhibited reduced locomotion, increased grooming, and antisocial behavior from 5 mM of Fe. This research highlights potential Fe toxicity risks during development and underscores the utility of D. melanogaster in unraveling neurological disorders, emphasizing its relevance for future research.

The Density of Regulatory Information Is a Major Determinant of Evolutionary Constraint on Noncoding DNA in Drosophila.

Evolutionary analyses have estimated that ∼60% of nucleotides in intergenic regions of the Drosophila melanogaster genome are functionally relevant, suggesting that regulatory information may be encoded more densely in intergenic regions than has been revealed by most functional dissections of regulatory DNA. Here, we approached this issue through a functional dissection of the regulatory region of the gene shavenbaby (svb). Most of the ∼90 kb of this large regulatory region is highly conserved in the genus Drosophila, though characterized enhancers occupy a small fraction of this region. By analyzing the regulation of svb in different contexts of Drosophila development, we found that the regulatory information that drives svb expression in the abdominal pupal epidermis is organized in a different way than the elements that drive svb expression in the embryonic epidermis. While in the embryonic epidermis svb is activated by compact enhancers separated by large inactive DNA regions, svb expression in the pupal epidermis is driven by regulatory information distributed over broader regions of svb cis-regulatory DNA. In the same vein, we observed that other developmental genes also display a dense distribution of putative regulatory elements in their regulatory regions. Furthermore, we found that a large percentage of conserved noncoding DNA of the Drosophila genome is contained within regions of open chromatin. These results suggest that part of the evolutionary constraint on noncoding DNA of Drosophila is explained by the density of regulatory information, which may be greater than previously appreciated.

Screening for Differentially Expressed Memory Genes on a Diabetes Model Induced by High-Sugar Diet in Drosophila melanogaster: Potential Markers for Memory Deficits.

Type 2 diabetes mellitus (T2DM) has been shown to affect a series of cognitive processes including memory, increasing the risk for dementia, particularly Alzheimer's disease (AD). Although increasing evidence has supported that both diseases share common features, the pathophysiological mechanisms connecting these two disorders remain to be fully elucidated. Herein, we used Drosophila melanogaster fed on a high-sugar diet (HSD) to mimic T2DM, and investigate its effects on memory as well as identify potential molecular players associated with the memory deficits induced by HSD. Flies hatched from and reared on HSD for 7 days had a substantial decrease in short-term memory (STM). The screening for memory-related genes using transcriptome data revealed that HSD altered the expression of 33% of memory genes in relation to the control. Among the differentially expressed genes (DEGs) with a fold change (FC) higher than two, we found five genes, related to synapse and memory trace formation, that could be considered strong candidates to underlie the STM deficits in HSD flies: Abl tyrosine kinase (Abl), bruchpilot (Brp), minibrain (Mnb), shaker (Sh), and gilgamesh (Gish). We also analyzed genes from the dopamine system, one of the most relevant signaling pathways for olfactory memory. Interestingly, the flies fed on HSD presented a decreased expression of the Tyrosine hydroxylase (Ple) and Dopa decarboxylase (Ddc) genes, signals of a possible dopamine deficiency. In this work, we present promising biomarkers to investigate molecular networks shared between T2DM and AD.

The autophagy protein Def8 is altered in Alzheimer's disease and Aß42-expressing Drosophila brains.

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized by protein accumulation in the brain as a main neuropathological hallmark. Among them, Aß42 peptides tend to aggregate and create oligomers and plaques. Macroautophagy, a form of autophagy characterized by a double-membrane vesicle, plays a crucial role in maintaining neuronal homeostasis by degrading protein aggregates and dysfunctional organelles as a quality control process. Recently, DEF8, a relatively uncharacterized protein, has been proposed as a participant in vesicular traffic and autophagy pathways. We have reported increased DEF8 levels in lymphocytes from mild cognitive impairment (MCI) and early-stage AD patients and a neuronal profile in a murine transgenic AD model. Here, we analyzed DEF8 localization and levels in the postmortem frontal cortex of AD patients, finding increased levels compared to healthy controls. To evaluate the potential function of DEF8 in the nervous system, we performed an in silico assessment of its expression and network profiles, followed by an in vivo evaluation of a neuronal Def8 deficient model using a Drosophila melanogaster model of AD based on Aß42 expression. Our findings show that DEF8 is an essential protein for maintaining cellular homeostasis in the nervous system, and it is upregulated under stress conditions generated by Aß42 aggregation. This study suggests DEF8 as a novel actor in the physiopathology of AD, and its exploration may lead to new treatment avenues.

The implications of exercise in Drosophila melanogaster: insights into Akt/p38 MAPK/Nrf2 pathway associated with Hsp70 regulation in redox balance maintenance.

This study investigated the potential effects of exercise on the responses of energy metabolism, redox balance maintenance, and apoptosis regulation in Drosophila melanogaster to shed more light on the mechanisms underlying the increased performance that this emerging exercise model provides. Three groups were evaluated for seven days: the control (no exercise or locomotor limitations), movement-limited flies (MLF) (no exercise, with locomotor limitations), and EXE (with exercise, no locomotor limitations). The EXE flies demonstrated greater endurance-like tolerance in the swimming test, associated with increased citrate synthase activity, lactate dehydrogenase activity and lactate levels, and metabolic markers in exercise. Notably, the EXE protocol regulated the Akt/p38 MAPK/Nrf2 pathway, which was associated with decreased Hsp70 activation, culminating in glutathione turnover regulation. Moreover, reducing the locomotion environment in the MLF group decreased endurance-like tolerance and did not alter citrate synthase activity, lactate dehydrogenase activity, or lactate levels. The MLF treatment promoted a pro-oxidant effect, altering the Akt/p38 MAPK/Nrf2 pathway and increasing Hsp70 levels, leading to a poorly-regulated glutathione system. Lastly, we demonstrated that exercise could modulate major metabolic responses in Drosophila melanogaster aerobic and anaerobic metabolism, associated with apoptosis and cellular redox balance maintenance in an emergent exercise model.

Increased Iron Levels and Oxidative Stress Mediate Age-Related Impairments in Male and Female Drosophila melanogaster.

Aging is characterized by a functional decline in the physiological functions and organic systems, causing frailty, illness, and death. Ferroptosis is an iron- (Fe-) dependent regulated cell death, which has been implicated in the pathogenesis of several disorders, such as cardiovascular and neurological diseases. The present study investigated behavioral and oxidative stress parameters over the aging of Drosophila melanogaster that, together with augmented Fe levels, indicate the occurrence of ferroptosis. Our work demonstrated that older flies (30-day-old) of both sexes presented impaired locomotion and balance when compared with younger flies (5-day-old). Older flies also produced higher reactive oxygen species (ROS) levels, decreased glutathione levels (GSH), and increased lipid peroxidation. In parallel, Fe levels were augmented in the fly's hemolymph. The GSH depletion with diethyl maleate potentiated the behavioral damage associated with age. Our data demonstrated biochemical effects that characterize the occurrence of ferroptosis over the age of D. melanogaster and reports the involvement of GSH in the age-associated damages, which could be in part attributed to the augmented levels of Fe.

Effects of Fructose and Palmitic Acid on Gene Expression in Drosophila melanogaster Larvae: Implications for Neurodegenerative Diseases.

One of the largest health problems worldwide is the development of chronic noncommunicable diseases due to the consumption of hypercaloric diets. Among the most common alterations are cardiovascular diseases, and a high correlation between overnutrition and neurodegenerative diseases has also been found. The urgency in the study of specific damage to tissues such as the brain and intestine led us to use Drosophila melanogaster to study the metabolic effects caused by the consumption of fructose and palmitic acid in specific tissues. Thus, third instar larvae (96 ± 4 h) of the wild Canton-S strain of D. melanogaster were used to perform transcriptomic profiling in brain and midgut tissues to test for the potential metabolic effects of a diet supplemented with fructose and palmitic acid. Our data infer that this diet can alter the biosynthesis of proteins at the mRNA level that participate in the synthesis of amino acids, as well as fundamental enzymes for the dopaminergic and GABAergic systems in the midgut and brain. These also demonstrated alterations in the tissues of flies that may help explain the development of various reported human diseases associated with the consumption of fructose and palmitic acid in humans. These studies will not only help to better understand the mechanisms by which the consumption of these alimentary products is related to the development of neuronal diseases but may also contribute to the prevention of these conditions.

Zearalenone Does Not Show Genotoxic Effects in the Drosophila melanogaster Wing Spot Test, but It Induces Oxidative Imbalance, Development, and Fecundity Alterations.

Zearalenone (ZEN) is a non-steroidal mycoestrogen produced by the Fusarium genus. ZEN and its metabolites compete with 17-beta estradiol for cytosolic estrogen receptors, causing reproductive alterations in vertebrates. ZEN has also been associated with toxic and genotoxic effects, as well as an increased risk for endometrial adenocarcinomas or hyperplasia, breast cancer, and oxidative damage, although the underlying mechanisms remain unclear. Previous studies have monitored cellular processes through levels of transcripts associated with Phase I Xenobiotic Metabolism (Cyp6g1 and Cyp6a2), oxidative stress (hsp60 and hsp70), apoptosis (hid, grim, and reaper), and DNA damage genes (Dmp53). In this study, we evaluated the survival and genotoxicity of ZEN, as well as its effects on emergence rate and fecundity in Drosophila melanogaster. Additionally, we determined levels of reactive oxygen species (ROS) using the D. melanogaster flare and Oregon R(R)-flare strains, which differ in levels of Cyp450 gene expression. Our results showed that ZEN toxicity did not increase mortality by more than 30%. We tested three ZEN concentrations (100, 200, and 400 µM) and found that none of the concentrations were genotoxic but were cytotoxic. Taking into account that it has previously been demonstrated that ZEN administration increased hsp60 expression levels and apoptosis gene transcripts in both strains, the data agree with an increase in ROS and development and fecundity alterations. Since Drosophila lacks homologous genes for mammalian estrogen receptors alpha and beta, the effects of this mycotoxin can be explained by a mechanism different from estrogenic activity.

Drosophila DAxud1 Has a Repressive Transcription Activity on Hsp70 and Other Heat Shock Genes.

Drosophila melanogaster DAxud1 is a transcription factor that belongs to the Cysteine Serine Rich Nuclear Protein (CSRNP) family, conserved in metazoans, with a transcriptional transactivation activity. According to previous studies, this protein promotes apoptosis and Wnt signaling-mediated neural crest differentiation in vertebrates. However, no analysis has been conducted to determine what other genes it might control, especially in connection with cell survival and apoptosis. To partly answer this question, this work analyzes the role of Drosophila DAxud1 using Targeted-DamID-seq (TaDa-seq), which allows whole genome screening to determine in which regions it is most frequently found. This analysis confirmed the presence of DAxud1 in groups of pro-apoptotic and Wnt pathway genes, as previously described; furthermore, stress resistance genes that coding heat shock protein (HSP) family genes were found as hsp70, hsp67, and hsp26. The enrichment of DAxud1 also identified a DNA-binding motif (AYATACATAYATA) that is frequently found in the promoters of these genes. Surprisingly, the following analyses demonstrated that DAxud1 exerts a repressive role on these genes, which are necessary for cell survival. This is coupled with the pro-apoptotic and cell cycle arrest roles of DAxud1, in which repression of hsp70 complements the maintenance of tissue homeostasis through cell survival modulation.

A cis-regulatory sequence of the selector gene vestigial drives the evolution of wing scaling in Drosophila species.

Scaling between specific organs and overall body size has long fascinated biologists, being a primary mechanism by which organ shapes evolve. Yet, the genetic mechanisms that underlie the evolution of scaling relationships remain elusive. Here, we compared wing and fore tibia lengths (the latter as a proxy of body size) in Drosophila melanogaster, Drosophila simulans, Drosophila ananassae and Drosophila virilis, and show that the first three of these species have roughly a similar wing-to-tibia scaling behavior. In contrast, D. virilis exhibits much smaller wings relative to their body size compared with the other species and this is reflected in the intercept of the wing-to-tibia allometry. We then asked whether the evolution of this relationship could be explained by changes in a specific cis-regulatory region or enhancer that drives expression of the wing selector gene, vestigial (vg), whose function is broadly conserved in insects and contributes to wing size. To test this hypothesis directly, we used CRISPR/Cas9 to replace the DNA sequence of the predicted Quadrant Enhancer (vgQE) from D. virilis for the corresponding vgQE sequence in the genome of D. melanogaster. Strikingly, we discovered that D. melanogaster flies carrying the D. virilis vgQE sequence have wings that are significantly smaller with respect to controls, partially shifting the intercept of the wing-to-tibia scaling relationship towards that observed in D. virilis. We conclude that a single cis-regulatory element in D. virilis contributes to constraining wing size in this species, supporting the hypothesis that scaling could evolve through genetic variations in cis-regulatory elements.

FOXO-mediated repression of Dicer1 regulates metabolism, stress resistance, and longevity in Drosophila.

The adipose tissue plays a crucial role in metabolism and physiology, affecting animal lifespan and susceptibility to disease. In this study, we present evidence that adipose Dicer1 (Dcr-1), a conserved type III endoribonuclease involved in miRNA processing, plays a crucial role in the regulation of metabolism, stress resistance, and longevity. Our results indicate that the expression of Dcr-1 in murine 3T3L1 adipocytes is responsive to changes in nutrient levels and is subject to tight regulation in the Drosophila fat body, analogous to human adipose and hepatic tissues, under various stress and physiological conditions such as starvation, oxidative stress, and aging. The specific depletion of Dcr-1 in the Drosophila fat body leads to changes in lipid metabolism, enhanced resistance to oxidative and nutritional stress, and is associated with a significant increase in lifespan. Moreover, we provide mechanistic evidence showing that the JNK-activated transcription factor FOXO binds to conserved DNA-binding sites in the dcr-1 promoter, directly repressing its expression in response to nutrient deprivation. Our findings emphasize the importance of FOXO in controlling nutrient responses in the fat body by suppressing Dcr-1 expression. This mechanism coupling nutrient status with miRNA biogenesis represents a novel and previously unappreciated function of the JNK-FOXO axis in physiological responses at the organismal level.

Navigating Like a Fly: Drosophila melanogaster as a Model to Explore the Contribution of Serotonergic Neurotransmission to Spatial Navigation.

Serotonin is a monoamine that acts in vertebrates and invertebrates as a modulator promoting changes in the structure and activity of brain areas relevant to animal behavior, ranging from sensory perception to learning and memory. Whether serotonin contributes in Drosophila to human-like cognitive abilities, including spatial navigation, is an issue little studied. Like in vertebrates, the serotonergic system in Drosophila is heterogeneous, meaning that distinct serotonergic neurons/circuits innervate specific fly brain regions to modulate precise behaviors. Here we review the literature that supports that serotonergic pathways modify different aspects underlying the formation of navigational memories in Drosophila.

Downregulation of Plasma Membrane Ca2+ ATPase driven by tyrosine hydroxylase-Gal4 reduces Drosophila lifespan independently of effects in neurons.

In Drosophila melanogaster, several Gal4 drivers are used to direct gene/RNAi expression to different dopaminergic neuronal clusters. We previously developed a fly model of Parkinson's disease, in which dopaminergic neurons had elevated cytosolic Ca2+ due to the expression of a Plasma Membrane Ca2+ ATPase (PMCA) RNAi under the thyroxine hydroxylase (TH)-Gal4 driver. Surprisingly, TH-Gal4>PMCARNAi flies died earlier compared to controls and showed swelling in the abdominal area. Flies expressing the PMCARNAi under other TH drivers also showed such swelling and shorter lifespan. Considering that TH-Gal4 is also expressed in the gut, we proposed to suppress the expression specifically in the nervous system, while maintaining the activation in the gut. Therefore, we expressed Gal80 under the direction of the panneuronal synaptobrevin (nSyb) promoter in the context of TH-Gal4. nSyb-Gal80; TH-Gal4>PMCARNAi flies showed the same reduction of survival as TH-Gal4>PMCARNAi flies, meaning that the phenotype of abdomen swelling and reduced survival could be due to the expression of the PMCARNAi in the gut. In perimortem stages TH-Gal4>PMCARNAi guts had alteration in the proventriculi and crops. The proventriculi appeared to lose cells and collapse on itself, and the crop increased its size several times with the appearance of cellular accumulations at its entrance. No altered expression or phenotype was observed in flies expressing PMCARNAi in the dopaminergic PAM cluster (PAM-Gal4>PMCARNAi). In this work we show the importance of checking the global expression of each promoter and the relevance of the inhibition of PMCA expression in the gut.