L species. In the majority of these studies no adverse effects have been detected. However, few studies found subtle histopathological changes and signs of hepatorenal toxicity in rats [3,4] and altered immune responses in mice [5], fish [6] and pigs [7]. Thus, there is an on-going debate on the risk of GM consumption and a demand for Title Loaded From File additional evidence of GM food and feed safety [8?1]. Although in vitro testing of GM food and feed compounds is considered to be helpful to complement safety assessment programmes and has been encouraged by international scientific committees [10], only few data are available from cell culture experiments. The application of an in vitro cell culture system especially for preliminary screening of GM food has many advantages, e. g. sufficient results at low costs, high speed and less animal use [12]. Because of minor complexity of such cellularsystems in comparison to the animal better conclusions can be drawn concerning specific mechanism of action. Moreover, mammalian cell cultures may allow scientists to reveal possible unintended side effects of novel proteins on non-target species. Thus, there is a growing interest in suitable in vitro screening systems possibly reflecting in vivo toxicity of food ingredients. Liver and kidney are considered as the two major target Title Loaded From File organs of detoxification. Therefore cell cultures derived from these organs are in the focus of risk assessment. For example, a slight but not statistically significant increase of LDH release after 48 h exposure to Cry1Ab was observed on bovine hepatocytes [13]. Moreover Bt toxins have been tested on human embryonic kidney cells [14]. Time- and dose dependent effects of relatively high concentrations of Cry1Ab on viability of HEK293 cells, respiration inhibition and plasma membrane alterations, were detected. In addition, cell cultures from the gastrointestinal tract (GIT) are of particular interest in comprehensive risk assessment. Cell cultures of the digestive system are clearly superior to the use of any other cell types, because the GIT represents the first barrier for exogenous food and the primary portal and absorption side. Notably, since very low amounts of full-size and fragmented Cry1Ab protein have been detected in the GIT digesta [15]) in the rumen [16,17] and in the GIT of pigs [18], such intestinal cell culture systems are also in the focus of GM safety research. From the results on brush-border membrane vesicles (BBMVs) it was concluded, that Cry1Ab may not impair the membrane integrity or permeability of mammalianImpact of Cry1Ab on Porcine Intestinal Cellsintestinal epithelial cells [19]. In contrast, our previous results on perfused rumen epithelial cells suggest that at sufficiently high concentrations spontaneous insertion of Cry1Ab into the membrane of these cells occurs [20]. Nevertheless, we found no adverse effects on viability of cultured rumen epithelial cells [21]. Consequently, there is a need for additional data in comprehensive risk assessment regarding Cry1Ab on suitable in vitro systems. The aim of this study was to identify possible effects of Cry1Ab on porcine intestinal cells. The 23977191 used IPEC-J2 cell line is well characterized [22] and represents a convenient intestinal functional cell model [23], that reflects the in vivo situation as faithfully as possible. A novel electronic cell sensor array technology, the real-time cell analysis (RTCA) system was used for dynamic monitoring of cellular events of Cry1A.L species. In the majority of these studies no adverse effects have been detected. However, few studies found subtle histopathological changes and signs of hepatorenal toxicity in rats [3,4] and altered immune responses in mice [5], fish [6] and pigs [7]. Thus, there is an on-going debate on the risk of GM consumption and a demand for additional evidence of GM food and feed safety [8?1]. Although in vitro testing of GM food and feed compounds is considered to be helpful to complement safety assessment programmes and has been encouraged by international scientific committees [10], only few data are available from cell culture experiments. The application of an in vitro cell culture system especially for preliminary screening of GM food has many advantages, e. g. sufficient results at low costs, high speed and less animal use [12]. Because of minor complexity of such cellularsystems in comparison to the animal better conclusions can be drawn concerning specific mechanism of action. Moreover, mammalian cell cultures may allow scientists to reveal possible unintended side effects of novel proteins on non-target species. Thus, there is a growing interest in suitable in vitro screening systems possibly reflecting in vivo toxicity of food ingredients. Liver and kidney are considered as the two major target organs of detoxification. Therefore cell cultures derived from these organs are in the focus of risk assessment. For example, a slight but not statistically significant increase of LDH release after 48 h exposure to Cry1Ab was observed on bovine hepatocytes [13]. Moreover Bt toxins have been tested on human embryonic kidney cells [14]. Time- and dose dependent effects of relatively high concentrations of Cry1Ab on viability of HEK293 cells, respiration inhibition and plasma membrane alterations, were detected. In addition, cell cultures from the gastrointestinal tract (GIT) are of particular interest in comprehensive risk assessment. Cell cultures of the digestive system are clearly superior to the use of any other cell types, because the GIT represents the first barrier for exogenous food and the primary portal and absorption side. Notably, since very low amounts of full-size and fragmented Cry1Ab protein have been detected in the GIT digesta [15]) in the rumen [16,17] and in the GIT of pigs [18], such intestinal cell culture systems are also in the focus of GM safety research. From the results on brush-border membrane vesicles (BBMVs) it was concluded, that Cry1Ab may not impair the membrane integrity or permeability of mammalianImpact of Cry1Ab on Porcine Intestinal Cellsintestinal epithelial cells [19]. In contrast, our previous results on perfused rumen epithelial cells suggest that at sufficiently high concentrations spontaneous insertion of Cry1Ab into the membrane of these cells occurs [20]. Nevertheless, we found no adverse effects on viability of cultured rumen epithelial cells [21]. Consequently, there is a need for additional data in comprehensive risk assessment regarding Cry1Ab on suitable in vitro systems. The aim of this study was to identify possible effects of Cry1Ab on porcine intestinal cells. The 23977191 used IPEC-J2 cell line is well characterized [22] and represents a convenient intestinal functional cell model [23], that reflects the in vivo situation as faithfully as possible. A novel electronic cell sensor array technology, the real-time cell analysis (RTCA) system was used for dynamic monitoring of cellular events of Cry1A.