Composite images of whole milk stained with acridine orange (AO). Each image contains three channels: 1) a differential interference contrast image to view the fat globules, which look like gray bubbles; 2) a fluorescence channel for AO-RNA; and 3) another fluorescence channel for AO-DNA. When AO associates with RNA, the emission maximum is 650 nm (red). When AO associates with DNA, the emission maximum is 525 nm (green). Therefore, areas containing only RNA (e.g. crescents) look red, only DNA look green, and both RNA and DNA (e.g. nucleated cells) look yellow. (A) Close-up of human whole milk with a nucleated cell (yellow) and several crescents of various sizes. (B) Whole slide scanned image of human whole milk collected after a 4-hr milk accumulation. (C–D) Whole slide scanned images of macaque whole milk after (C) a 4-hr and (D) a 10-min milk accumulation.
Lemay et al. BMC Genomics 2013 14:872 doi:10.1186/1471-2164-14-872