For many years it was thought eating a diet high in fiber could help prevent cancers of the rectum and colon. More recently, however, some studies have cast a certain amount of doubt on this long-held belief. For instance, a study carried out by the National Cancer Institute found that individuals who previously developed colorectal polyps, which can develop into cancerous tumors, were not any less likely to develop them again if they consumed a diet high in fiber over the course of several years. The work of another research group was unable to produce any evidence that wheat bran fiber supplementation can help prevent colorectal cancer. However, many scientists believe that additional research into the value of fiber is still warranted.

In order to localize a green fluorescent tag to F-actin in the sample of rat rectum tissue presented in the digital image above, the specimen was labeled with Alexa Fluor 488 conjugated to phalloidin, a cyclic peptide derived from the toxic death cap fungus (Amanita phalloides). Texas Red conjugated to the lectin wheat germ agglutinin, which selectively binds to N-acetylglucosamine and N-acetylneuraminic residues, was also applied to the tissue sample, as was the nuclear counterstain Hoechst 33342. Images were recorded in grayscale with a 12-bit digital camera coupled to a Nikon Eclipse 80i microscope equipped with bandpass emission fluorescence filter optical blocks. During the processing stage, individual image channels were pseudocolored with RGB values corresponding to each of the fluorophore emission spectral profiles.