RT Journal Article SR Electronic T1 Two Nimrod receptors, NimC1 and Eater, synergistically contribute to bacterial phagocytosis in Drosophila melanogaster JF bioRxiv FD Cold Spring Harbor Laboratory SP 479550 DO 10.1101/479550 A1 Claudia Melcarne A1 Elodie Ramond A1 Jan Dudzic A1 Andrew J Bretscher A1 Éva Kurucz A1 István Andó A1 Bruno Lemaitre YR 2018 UL http://biorxiv.org/content/early/2018/11/27/479550.abstract AB Eater and NimC1 are transmembrane receptors of the Drosophila Nimrod family, specifically expressed in hemocytes, the insect blood cells. Previous ex vivo and in vivo RNAi studies have pointed to their role in the phagocytosis of bacteria. Here, we have created a novel null mutant in NimC1 to re-evaluate the role of NimC1, alone or in combination with Eater, in the cellular immune response. We show that NimC1 functions as an adhesion molecule ex vivo, but in contrast to Eater is not required for hemocyte sessility in vivo. Ex vivo phagocytosis assays and electron microscopy experiments confirmed that Eater is the main phagocytic receptor for Gram-positive, but not Gram-negative bacteria, and contributes to microbe tethering to hemocytes. Surprisingly, the NimC1 deletion did not impair phagocytosis of bacteria, nor their adhesion to the hemocytes. However, phagocytosis of both types of bacteria was almost abolished in NimC11;eater1 hemocytes. This indicates that both receptors contribute synergistically to the phagocytosis of bacteria, but that Eater can bypass the requirement for NimC1. Finally, we uncovered that NimC1, but not Eater, is essential for uptake of latex beads and zymosan particles. We conclude that Eater and NimC1 are the two main receptors for phagocytosis of bacteria in Drosophila, and that each receptor likely plays distinct roles in microbial uptake.