 In these deletion-mutant mice, loss of Paneth cells, impaired IEC function and alterations in intestinal composition of commensal bacteria were observed.These negative effects were not observed in germ-free mice, indicating that the effects of the deletion are only seen in the presence of intestinal microbial colonization.But the negative effects of HDAC3 deletion are not due to the presence of an altered microbiota because normal germ-free mice colonized with the altered microbiota did not show the negative effects seen in deletion mutants.