Milleville, R. | Search bioRxiv

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↗