Rats fed on diets containing kidney bean showed increased intestinal permeability to intravenously injected 125I-labelled rat serum proteins after an intragastric challenge with bean proteins. The ...enhanced accumulation of radioactive serum proteins in the lumen and walls of the small intestine indicated increased vascular permeability. It is suggested that dietary lectins may, at least in part, be responsible for this loss of serum proteins and thus contribute towards the overall toxicity of kidney bean proteins.
The effects of infection by Salmonella enteritidis and S. typhimurium on the small and large intestines, liver, spleen and mesenteric nodules of rats were studied in vivo. Both Salmonella serotypes ...persisted and proliferated in the gastrointestinal tract and invaded sub‐epithelial tissues, mainly the ileum, leading to the systemic distribution of these pathogens. Coincidental with the infection, the rate of crypt cell proliferation increased resulting in substantial growth of the small intestine. The extent of this and the accompanying accumulation of polyamines was particularly dramatic in the ileum where there was also some disruption of the villus epithelium. It is possible that these effects of the infection on the metabolism and morphology of the small bowel, which strongly resembled the changes induced by some plant lectins, may facilitate the colonisation and invasion of the gut by Salmonellae.
Arpad Pusztai became a household name in 1998 when his GM potato research angered the biotechnology industry and lost him his job. Here he explains for the first time what happened and why he ...believes academic freedom in science is in danger of extinction. (Original abstract)
By a combination of solubility fractionation, affinity and molecular-sieve chromatography, a lectin preparation containing several closely related lectin components of different isoelectric point was ...isolated from the seeds of Dioclea grandiflora Mart. The lectins showed a carbohydrate specificty for D-mannose (D-glucose)-binding and had a requirement for the presence of Ca2+ and Mn2+. The results of preliminary characterization studies showed that the D. grandiflora lectins had similar properties to those of concanavalin A, the lectin from the seeds of Canavalia ensiformis, a plant also belonging to the tribe Diocleae. Thus the D. grandiflora lectins contained no covalently bound carbohydrate and had an amino-acid composition characterized by a low content of methionine and the virtual absence of cysteine. Above pH 4.8 they had molecular weight of about 100,000, while below pH 3.1 they were dissociated to half-molecules. Between these two pH values there was a fast association-dissociation equilibrium for the two species. In dissociating solvents, three subunits were obtained of the approximate size of 25—26,000, 13—14,000 and 8—9,000. The lectins from C. grandiflora similar to concanavalin A were more distantly related to the lectins obtained from the members of the tribe Vicieae although these were also specific for D-mannose (D-glucose)-binding.
Seven recently isolated lectins were tested for their ability to bind to tissue sections of rat gut. Binding sites for N-Acetylgalactosamine specific lectins were found in mucins, in the brush border ...membrane and in goblet cells. Non-reducing terminal mannose residues were absent from cell surface membranes but were detected in the supranuclear region of goblet cells and enterocytes. The results of lectin binding obtained in this study were generally similar to lectin-gut interactions observed in vivo.
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