** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** HUMAN AND COW'S MILK CONTAIN LARGE AMOUNTS OF NATURAL NANOPARTICLES (MILK EXOSOMES, MES), WHEREAS PLANT-BASED MILK AND INFANT FORMULA CONTAIN NO MES. PRIOR RESEARCH HAS SHOWN THAT A ME-DEFICIENT DIET IMPAIRS SPATIAL LEARNING AND MEMORY (SLM) AND INCREASES THE SEVERITY OF EPILEPSY-LIKE SEIZURES. THIS PROJECTS STUDIES WHETHER THE POSITIVE EFFECTS OF MES IN THE HOST ARE MEDIATED BY ME-DEPENDENT CHANGES IN NANOPARTICLES SECRETED BY THE GUT MICROBIOME. [GRAM-NEGATIVE BACTERIA SECRETE OUTER MEMBRANE VESICLES (OMVS), WHEREAS GRAM-POSITIVE BACTERIA SECRETE CYTOPLASMIC MEMBRANE VESICLES (CMVS).] THIS PROPOSAL TESTS THE HYPOTHESIS THAT DIETARY ME DEPLETION ALTERS THE QUANTITY (NUMBER) AND QUALITY (CONTENT OF PROTEINS AND RNA) OF OMVS AND CMVS, THEREBY IMPAIRING SLM IN THE HOST. THE RESEARCHERS WILL STUDY 1) EFFECTS OF MES ON OMV AND CMV QUANTITY AND QUALITY IN CULTURES OF GUT BACTERIA, 2) ABSORPTION AND TISSUE DISTRIBUTION OF OMVS, CMVS AND THEIR PROTEIN AND RNA CARGO IN THE HOST, 3) EFFECTS OF ME-DEPENDENT CHANGE IN OMVS AND VMVS ON GENE EXPRESSION IN THE HOST, AND 4) WHETHER ME-DEPENDENT CHANGES IN OMV AND CMV ARE RESPONSIBLE FOR THE EFFECTS OF MES ON SLM N THE HOST OBSERVED IN PRIOR RESEARCH.