Dietary zinc absorption is influenced by zinc levels in the enterocyte but not the rest of the body. (A) Transcriptional responses of dZip1 and dZip2 to gut-specific zinc changes as revealed by reverse transcriptase (RT)-PCR analysis. (B) Transcription of dZip1 and dZip2 in the gut does not respond noticeably to body zinc changes achieved by modulating the zinc excretion process (ZnT35C knockdown or ZnT35C overexpression in the malpighian tubules). (C) As a control, ZnT35C knockdown in the malpighian tubules effectively induced the bodily transcription of MtnB and MtnC (reflecting zinc increase), whereas overexpression of ZnT35C repressed the transcription of MtnB and MtnC. (D) Western blotting analysis shows that dZnT1 expression in the enterocyte is not altered when zinc excretion is modulated. (E) Immunofluorescence staining shows that dZip1 is induced at the midgut constriction (arrows) when dZnT1 is specifically overexpressed in the gut, in the absence of dietary zinc change. Scale bars = 50 μm. Genotypes of flies are NP3084/+ (control fly) and NP3084/dZnT1-RNAi (dZnT1-RNAi fly), NP3084/+; UAS-dZnT1/+ (dZnT1 overexpression fly), NP1093/+ (control fly), NP1093/+; ZnT35C-RNAi/+ (ZnT35C RNAi fly), and NP1093/+; UAS-ZnT35C (ZnT35C overexpression fly). RNAi, RNA interference.