What was used as the positive control tissue for Beclin-1?

• A. Canine hepatic tissue
• B. Canine cardiac muscle
• C. Canine brain
• D. Canine renal tubular epithelium

Answer: (D)

Beclin-1 is a key initiator of autophagy, so in immunohistochemistry the positive control should be a tissue that reliably expresses Beclin-1 to confirm the assay is working and the staining protocol is capable of detecting the target.

canine renal tubular epithelium fits this role well because proximal tubule cells have high basal autophagic activity, leading to robust Beclin-1 expression that can be consistently detected with the antibody. This provides a clear, reproducible positive signal that helps verify the staining procedure across samples.

Other tissues can show variable or weaker Beclin-1 expression under routine conditions, making them less dependable as universal positive controls. For example, hepatic tissue, cardiac muscle, or brain may not yield as consistent a positive signal in standard IHC settings, which is why renal tubular epithelium is preferred as the positive control.