biostudies-literatureLiu YChina Agriculture Research System of MOF and MARANational Key R&D Program of ChinaHuazhong Agricultural UniversityHubei Hongshan Laboratorywrae221https://www.ebi.ac.uk/biostudies/studies/S-EPMC11697180biostudies-literatureUnknown18(1)Host-gut microbiota interactions are more complex than good or bad. Both gut symbiotic bacteria and pathobionts can provide essential functions to their host in one scenario and yet be detrimental to host health in another. So, these gut-dwelling bacteria must be tightly controlled to avoid harmful effects on the host. However, how pathobionts and other symbiotic bacteria coordinate to establish a host immune defense system remains unclear. Here, using a Tephritidae fruit fly Bactrocera dorsalis, we report that both pathobionts and other gut symbiotic bacteria release tyramine, which is recognized by the host insects. These tyramines induce the formation of insect-conserved Malpighian tubules-gut countercurrent flow upon bacterial infection, which requires tyramine receptors and aquaporinsThe ISME journalPathobiont and symbiont contribute to microbiota homeostasis through Malpighian tubules-gut countercurrent flow in Bactrocera dorsalis.PMC11697180CARS-262021YFC2600400Liu YLi XBai SLemaitre BZhang HLuo RfalsePathobiont and symbiont contribute to microbiota homeostasis through Malpighian tubules-gut countercurrent flow in Bactrocera dorsalis.Host-gut microbiota interactions are more complex than good or bad. Both gut symbiotic bacteria and pathobionts can provide essential functions to their host in one scenario and yet be detrimental to host health in another. So, these gut-dwelling bacteria must be tightly controlled to avoid harmful effects on the host. However, how pathobionts and other symbiotic bacteria coordinate to establish a host immune defense system remains unclear. Here, using a Tephritidae fruit fly Bactrocera dorsalis, we report that both pathobionts and other gut symbiotic bacteria release tyramine, which is recognized by the host insects. These tyramines induce the formation of insect-conserved Malpighian tubules-gut countercurrent flow upon bacterial infection, which requires tyramine receptors and aquaporins2024-01-01T00:00:00Z2024 Jan2025-04-22T09:06:26.797Z2025-04-05T22:52:15.777ZS-EPMC116971803953035610.1093/ismejo/wrae221