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Effects of Bacillus thuringiensis Cry1Ab toxin on mammalian cells
Nobuaki Shimada1, Yong Soon Kim, Kazuhisa Miyamoto
1Department of Safety Research, National Institute of Animal Health, Tsukuba, Japan.
Abstract:
The Cry proteins produced by Bacillus thuringiensis are considered to be highly specific insecticidal proteins. Judged to be safe for humans and farm animals due to their insect-oriented selective toxicity, the proteins have been utilized as a biological pesticide and introduced into genetically modified plants. However, some critical fundamental characters of the Cry proteins remain unclear, and the direct effects of activated Cry proteins on mammalian cells have not yet been fully confirmed. Therefore, in this study we employed primary cultured bovine hapatocytes as a model system to determine if Cry1Ab, a Cry protein, affects mammalian cells. There were no significant changes in the secretion of albumin or the morphology of the Cry1Ab-treated cells. The LDH release showed a tendency to increase after the administration of Cry1Ab, but not significantly. Taking these results on bovine hepatocytes into consideration, Cry1Ab has little acute toxicity on mammalian cells.
Insights
Bacillus thuringiensis Cry1Ab proteins, used in biopesticides and GMOs, showed minimal acute toxicity in bovine liver cells. This study indicates Cry1Ab has little direct impact on mammalian cells.
Area of Science:
- Biochemistry
- Toxicology
- Molecular Biology
Background:
- Bacillus thuringiensis (Bt) produces Cry proteins, widely used as selective insecticidal biological pesticides and in genetically modified (GM) crops.
- While generally considered safe for mammals due to target specificity, the direct effects of activated Cry proteins on mammalian cells require further confirmation.
- Understanding the safety profile of Cry proteins is crucial for assessing the risks associated with their environmental and agricultural applications.
Purpose of the Study:
- To investigate the direct effects of activated Cry1Ab protein on mammalian cells using a primary cultured bovine hepatocyte model.
- To assess potential cytotoxic impacts, including changes in cell morphology and albumin secretion.
- To evaluate the release of lactate dehydrogenase (LDH) as an indicator of cell membrane damage.
Main Methods:
- Primary bovine hepatocytes were cultured and treated with activated Cry1Ab protein.
- Cell morphology and albumin secretion were monitored to assess general cell health.
- Lactate dehydrogenase (LDH) release assay was performed to detect cytotoxicity and cell membrane integrity.
Main Results:
- Cry1Ab treatment did not induce significant alterations in the morphology of bovine hepatocytes.
- No significant changes were observed in the secretion of albumin by the treated cells.
- A slight, non-significant tendency for increased LDH release was noted post-Cry1Ab administration.
Conclusions:
- Cry1Ab protein exhibits minimal acute toxicity towards primary cultured bovine hepatocytes.
- The findings suggest that Cry1Ab has a low direct impact on mammalian cells under the tested conditions.
- This study contributes to the safety assessment of Cry proteins used in agricultural biotechnology.