Biology subjects

Maniere, G.

Publications and source records attributed to Maniere, G..

7 recordsLinked to original sources

bioRxiv2025

Uracil-Driven ROS signals activate larval TrpA1-B neurons to prime the Drosophila adult gustatory response to bacterial signal

Animals perceive their environment through their sensory systems why rely on neuronal circuits and proteins, but can be modulated by internal physiological conditions or exogenous factors. We have shown that the presence of certain pathogenic bacteria in the larval gut can alter the specificity of bacterial peptidoglycan recognition in the adults that emerge from these larvae. However, the nature of the bacterial signal and the host cells and molecules involved in receiving and transducing this signal remained unknown. We identify here uracil as the bacterial metabolite responsible for this priming and demonstrate that the effect is mediated by Duox-dependent production of reactive oxygen species in the larval gut. We show that specific expression of TrpA1 isoforms in a Gr66a-expressing neuron of the larval terminal organ is required for the adult response. Together, these findings reveal uracil as the bacterial cue and the Duox/ROS and TrpA1/Gr66a modules as key mediators linking larval gut microbial signals and host integration to subsequent sensory system modulation in the adult. HighlightsO_LIBacterial uracil primes larvae to drive adult aversion to peptidoglycan C_LIO_LIDuox-dependent ROS in larval enterocytes are required for sensory priming C_LIO_LITrpA1 B/C/E isoforms in a larval Gr66a+ neuron mediate priming C_LIO_LIUracil induces Duox/ROS signals enabling inter-larval activation of TrpA1-B+ neurons C_LI

neuroscience↗

bioRxiv2025

An intercellular metabolic relay for brain sparingin Drosophila

Brain sparing protects growth of the central nervous system (CNS) at the expense of other developing organs during nutrient restriction. This survival strategy is conserved from Drosophila to mammals but little is known about its underlying metabolic mechanisms. Here, we show that CNS uptake and catabolism of circulating glutamine is essential for neural stem cell proliferation during brain sparing but not normal brain development. Glutamine is imported into perineurial glia of the blood-brain-barrier, which upregulate glutaminase (Gls) and vesicular glutamate transporter 1 (VGlut1) to promote glutaminolysis and glutamate secretion. Neural stem cells then import released glutamate via excitatory amino acid transporter 1 (Eaat1) and maintain it at homeostatic levels via glutamine synthetase 1 (Gs1). Glutamine nitrogen contributes surprisingly little to newly synthesized DNA or protein in neural stem cells but its carbon fuels the oxidative tricarboxylic acid cycle. These findings identify an intercellular metabolic relay specifically required to sustain the proliferation of neural stem cells during brain sparing.

developmental biology↗

bioRxiv2024

Drosophila's sensory responses to bacterial peptidoglycan integrates positive and negative signals

Interactions between animals, including humans, and surrounding microbes are governed by a delicate balance, crucial for survival. Animals must distinguish and respond adequately to beneficial and harmful microbes to maintain homeostasis. Recent research suggests that bacterial components such as lipopolysaccharide and peptidoglycan (PGN) influence host behavior by modulating neuronal activity. PGN detection by specific neurons can prompt infected female flies to reduce oviposition or trigger avoidance behaviors via gustatory neurons. Using behavioral assays and calcium imaging, we found that PGNs can also act as attractants, activating the sweet taste circuit in a concentration-dependent manner. Our findings demonstrate that flies integrate PGN-derived positive and negative signals to make ad hoc decisions. This dual response underlines the need for Drosophila to distinguish between different concentrations of compounds in their environment, integrating sensory data to navigate efficiently in microbe-co-inhabited environments. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=104 SRC="FIGDIR/small/626038v3_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@8aab21org.highwire.dtl.DTLVardef@1e90d09org.highwire.dtl.DTLVardef@156f1d4org.highwire.dtl.DTLVardef@11ed69c_HPS_FORMAT_FIGEXP M_FIG C_FIG Highlights- Bacterial PGN is attractive to flies - Gr5a sweet gustatory neurons are activated by PGN - Adult PER to PGN is not directly influenced by larval life - Fly gustatory response to PGN integrates both attractive and aversive signals

animal behavior and cognition↗

bioRxiv2024

Detection of bacteria through taste receptors primes the cellular immune response

Animals use their sensory system to detect cues in their external environment, then communicate, process, and integrate these cues through the nervous system in order to elicit a specific response. Taste is an important cue used by animals to explore their external environment and can modulate various aspects of animal behavior and physiology. A major ongoing challenge for animals is to detect and respond to the presence of a variety of microbes in their environment. However, to date, the links between the sensory system and the response to pathogenic threats remain poorly understood. Here we show that Drosophila melanogaster larvae use their taste system to detect bacterial peptidoglycans in their environment and respond by modulating the activity of their cellular immune system. We show that specific PeptidoGlycan Receptor Proteins (PGRPs) act in aversive taste neurons, via a non-canonical Immune Deficiency (Imd) pathway. These PGRPs mediate signaling in taste neurons and control immune cells production in the larval hematopoietic organ, the lymph gland. Taste-mediated sensing of bacteria in larvae primes the immune system, and improves survival after infection in adult flies. These results demonstrate that sensory inputs such as taste play an important role in protecting animals from bacterial infection by providing a powerful adaptive response to potential pathogens. Overall, our findings add to the growing list of examples of crosstalk between the nervous and immune systems and provide novel and important mechanisms for linking them. One Sentence SummaryNajera Mazariegos et al. demonstrate that organisms can use taste to monitor their environment for potential immune challenges and activate their immune system if they detect bacteria.

immunology↗

bioRxiv2023

Larval microbiota primes the Drosophila adult gustatory response

The survival of animals depends, among other things, on their ability to identify threats in their surrounding environment. Senses such as olfaction, vision and taste play an essential role in sampling their living environment, including microorganisms, some of which are potentially pathogenic. This study focuses on the mechanisms of detection of bacteria by the Drosophila gustatory system. We demonstrate that the peptidoglycan (PGN) that forms the cell wall of bacteria triggers an immediate feeding aversive response when detected by the gustatory system of adult flies. Although we identify ppk23+ and Gr66a+ gustatory neurons as necessary to transduce fly response to PGN, we demonstrate that they play very different roles in the process. Time-controlled functional inactivation and in vivo calcium imaging demonstrate that while ppk23+ neurons are required in the adult flies to directly transduce PGN signal, Gr66a+ neurons must be functional in larvae to allow future adults to become PGN sensitive. Furthermore, the ability of adult flies to respond to bacterial PGN is lost when they hatch from larvae reared under axenic conditions. Recolonization of axenic larvae, but not adults, with a single bacterial species, Lactobacillus brevis, is sufficient to restore the ability of adults to respond to PGN. Our data demonstrate that the genetic and environmental characteristics of the larvae are essential to make the future adults competent to respond to certain sensory stimuli such as PGN.

animal behavior and cognition↗

bioRxiv2022

Evolutionary divergence in sugar valuation shifts Drosophila suzukii oviposition choice towards ripe fruit

Behavior evolution can promote the emergence of agricultural pests via ecological niche changes. The underlying neuronal mechanisms are poorly understood. We investigate the chemosensory changes underlying the evolutionary shift of oviposition substrate of the pest Drosophila suzukii from rotten to ripe fruits. Using a model substrate for fermented fruits and genetic manipulations, we show that an increase in valuation of fruit sugars during oviposition decisions drives D. suzukii to oviposit on ripe fruits as opposed to the model D. melanogaster which prefers rotten fruits. Inter-species comparative in vivo calcium imaging of sugar Gustatory Receptor Neurons suggests that increased sugar valuation in D. suzukii is related to neuronal sensitivity changes at multiple levels of the oviposition circuitry. Our results show that the tuning of sugar valuation has contributed to the evolution of oviposition preference on ripe fruit of D. suzukii.

evolutionary biology↗

bioRxiv2021

Bacteria-derived peptidoglycan triggers an NF-kB dependent response in Drosophila gustatory neurons

Probing the external world is essential for eukaryotes to distinguish beneficial from pathogenic microorganisms. If it is clear that this task falls to the immune cells, recent work shows that neurons can also detect microbes, although the molecules and mechanisms involved are less characterized. In Drosophila, detection of bacteria-derived peptidoglycan by pattern recognition receptor (PRR) of the PGRP family expressed in immune cells, triggers NF-{kappa}B/IMD dependent signaling. We show here that one PGRP protein, called PGRP-LB, is expressed in some probosciss bitter taste neurons. In vivo calcium imaging reveals that the PGRP/IMD pathway is cell-autonomously required in these neurons to transduce the PGN signal. We finally show that NF-{kappa}B/IMD pathway activation in bitter neurons influences fly behavior. This demonstrates that flies use the same bacterial elicitor and signaling module to sense bacterial presence via the peripheral nervous system and trigger an anti-bacterial response in immune-competent cells.

neuroscience↗