Cry1Ac Protoxin from Bacillus thuringiensis sp. kurstaki HD73 Binds to Surface Proteins in the Mouse Small Intestine

Binding of Cry1Ab toxin, a Bacillus thuringiensis insecticidal toxin, to proteins of the bovine intestinal epithelial cell: An in vitro study

“…4A). This result agrees with a previous report that Cry1Ac protoxin binds to surface proteins in the mouse small intestine (Vázquez-Padrón et al, 2000). In addition, we found that the site of Cry1Ab toxin attachments corresponds to the b-actin site (Fig.…”

“…However, Vázquez-Padrón et al (2000) reported that one type of Cry1 protoxin (Cry1Ac) bound to the mucosal surface of the mouse small intestine and induced in situ temporal changes in the electrophysiological properties of the mouse jejunum without affecting the macroscopic physiological signals. Although Cry toxins are considered to be easily digested into non-toxic small fragments in the mammalian gastrointestinal tract, we recently detected trace amounts of intact Cry1Ab toxin in the gastrointestinal contents of calves that were fed GM corn containing the toxin (Chowdhury et al, 2003).…”

Humoral and cellular immune responses in mice after airway administration ofBacillus thuringiensisCry1Ab and MON810cry1Ab-transgenic maize

“…Although the mucous membranes of the respiratory and gastro-intestinal tracts may be the most important portals of exposure (Vazquez-Padron et al, 2000, Kitami et al, 2011 little information exist on the potential immune effects after airway exposure to the Cry1Ab proteins. Inhalation of pollen and plant debris may be a realistic exposure route for humans and domestic as well as wildlife animals in the fields, and also of workers during processing of food and feed.…”

Histopathological Investigation of the Stomach of Rats Fed a 60% Genetically Modified Corn Diet

“…While it has been suggested that these proteins cannot harm the gut of mammals because mammals lack the necessary gut environment and spe- [29], several studies indicate that this may not be the case. One in vitro study found Cry proteins binding to the apical surface of mouse small intestine epithelial cells, as well as hyperpolarisation of the intestine, which is consistent with the pore-forming action of the Cry proteins [30]. Another study found ultrastructural changes to enterocytes and hyperplasia in the ileum of mice fed for two weeks on a diet containing a Cry protein-producing GM potato or a non-GM potato diet which had the Cry protein added [31].…”

“…However, histopathological or immunotoxicological studies on the effects of the proteins on animal physiology are scarce [30], particularly of the Cry proteins produced by GM crops [13], which are encoded by cry genes that have been modified, enhanced or synthetically produced [2]. The species-specific mode of action of Cry proteins are believed to be based on three things: 1) the insects' mid-gut proteases which cleave the Cry proteins, consequently activating the proteins by exposing their binding site [28]; 2) the activated proteins binding to the insects' specific cadherin receptor [69]; and 3) the Cry proteins binding to the insects' specific cell membrane receptor(s) [70] [71].…”