Genotoxicity assessment of titanium dioxide nanoparticles using a standard battery of in vivo assays.

As one representative of nanometal oxides, titanium dioxide nanoparticles (TiO2-NPs) have been widely used, particularly in the food industry. The genotoxicity of TiO2-NPs has attracted great attention over the years. This study was undertaken to investigate the chromosome and DNA damage effects of TiO2-NPs (0, 50, 150, and 500 mg/kg BW) using rodent models. After a comprehensive characterization, we conducted a standard battery of in vivo genotoxicity tests, including the chromosomal aberration test (CA), micronucleus (MN) test, and the comet test. The results of all these tests were negative. There were no structural or numerical chromosomal abnormalities in mice bone marrow cells, no increase in the frequency of micronucleated polychromatic erythrocytes in mice bone marrow cells, and no elevation in % tail DNA in rat hepatocytes. This indicated that TiO2-NPs did not cause chromosomal damage or have a direct impact on DNA. These findings suggested that TiO2-NPs did not exhibit genotoxicity and provided valuable data for risk assessment purposes.

Safety assessment of phytase transgenic maize 11TPY050 in Sprague-Dawley rats by 90-day feeding study.

The present study aimed to evaluate the subchronic toxicity of feeding with phytase-transgenic maize line 11TPY050 in Sprague-Dawley (SD) rats. Rats (n = 10/sex/group) were fed with 12.5%, 25% or 50% (w/w) transgenic maize diet, 12.5%, 25% or 50% (w/w) non-transgenic isoline OSL940 maize diet, or 50% (w/w) commercially available Zhengdan958 maize diet for 90 days. Daily clinical observations and weekly measurements of body weights and food consumption were conducted. Blood samples were collected on day 46 and day 91 for hematology and clinical chemistry evaluations. At the end of the study, macroscopic and microscopic examinations were performed. No effects on body weight and food consumption were observed. The results of hematology, clinical chemistry, and absolute and relative organ weights in the transgenic maize group were comparable to those in the parental maize group. Several statistical differences were not dose-related and were not considered to be biologically significant. Furthermore, the terminal necropsy and histopathological examination showed no treatment-related changes among the groups. The results from the present 90-day feeding study of phytase-transgenic maize 11TPY050 indicated no unexpected adverse effects in SD rats. The phytase transgenic maize 11TPY050 has substantial equivalence with non-transgenic maize.

Safety assessment of phytase transgenic maize 11TPY001 by 90-day feeding study in rats.

11TPY001 is a transgenic maize that expresses the Aspergillus niger phyA2 gene which could significantly improve phosphorus bioavailability in monogastric animals. The present study was conducted to investigate the potential health effects of phytase transgenic maize 11TPY001 through a 90-day subchronic rodent feeding study. Maize grains from 11TPY001 or its parental counterpart maize OSL963 were incorporated into rodent diets at 12.5%, 25% and 50% concentrations by mass and administered to Sprague-Dawley rats (n = 10/sex/group) for 90 days. An additional control group of rats (n = 10/sex/group) were fed with common maize Zhengdan958 diets at 50% by mass. All formulated diets were nutritionally balanced. Body weights, food intake, hematology, serum chemistry, absolute and relative organ weights were measured, and gross as well as microscopic pathology were examined. Compared with rats fed OSL963 maize and the common maize diet groups, no adverse diet-related differences were observed in rats fed 11TPY001 maize diets with respect to clinical signs of toxicity, body weight/gain, food consumption/efficiency, hematology, clinical chemistry, organ weights, and gross and microscopic pathology. Under the conditions of this study, the results indicated that 11TPY001 did not cause any treatment related adverse effects in rats compared with its non-transgenic parental maize OSL963.

[Immunotoxicologic assessment of genetically modified drought-resistant wheat T349 with GmDREB1].

OBJECTIVE: To assess the immunotoxicologic effects of genetically modified drought resistant wheat T349 with GmDREB1 gene. METHODS: A total of 250 female BALB/c mice (6-8 week-old, weight 18-22 g) were divided into five large groups (50 mice for each large group) by body weight randomly. In each large group, the mice were divided into five groups (10 mice for each group) by body weight randomly, which were set as negative control group, common wheat group, parental wheat group, genetically modified wheat group and cyclophosphamide positive control group, respectively. Mice in negative control and positive control group were fed with feedstuff AIN-93G, mice in common wheat group, non-genetically modified parental wheat group and genetically modified wheat group were fed with feedstuffs added corresponding wheat (proportion up to 76%) for 30 days, then body weight, organ coefficient of spleen and thymus, peripheral blood lymphocytes phenotyping, serum cytokine, serum immunoglobulin, antibody plaque-forming cell (PFC), serum 50% hemolytic value (HC50), mitogen-induced splenocyte proliferation, delayed-type hypersensitivity (DTH) reaction and phagocytic activities of phagocytes were detected respectively. RESULTS: After 30 days raise, among negative control group, common wheat group, non-genetically modified parental wheat group, genetically modified wheat group and cyclophosphamide positive control group, mice body weight were (21.0±0.3), (20.4±0.7), (21.1±1.0), (21.1±1.0), (19.4±1.0) g, respectively (F=7.47, P<0.01); organ coefficient of spleen were (0.407±0.047)%, (0.390±0.028)%, (0.402±0.042)%, (0.421±0.041)%, (0.304±0.048)%, respectively (F=12.41, P<0.01); organ coefficient of thymus were (0.234±0.032)%, (0.246±0.028)%, (0.249±0.040)%, (0.234±0.034)%, (0.185±0.039)%, respectively (F=5.58, P<0.01); the percentage of T cell in peripheral blood were (70.43±4.44)%, (68.33±5.37)%, (73.04±2.68)%, (74.42±2.86)%, (90.42±1.66)%, respectively (F=57.51, P<0.01); the percentage of B cell were (13.89±3.19)%, (15.34±4.84)%, (13.06±4.22)%, (12.93±2.36)%, (3.01±0.96)%, respectively (F=12.79, P<0.01); the percentage of Th cell were (55.87±3.80)%, (55.24±4.60)%, (57.92±3.70)%, (59.57±2.54)%, (77.37±2.31)%, respectively (F=68.58, P<0.01);the Th/Ts ratio were 4.16±0.29, 4.73±0.96, 4.19±0.78, 4.52±0.40, 6.34±0.73, respectively (F=17.57, P<0.01);the serum IgG were (1046.38±210.67), (1065.49±297.22), (1517.73±299.52), (1576.67±241.92), (1155.88±167.05) µg/ml, respectively (F=10.53, P<0.01); the serum IgM were (333.83±18.97), (327.73±27.72), (367.47±27.18), (363.42±46.14), (278.71±24.42) µg/ml, respectively (F=12.11, P<0.01); the serum IgA were (51.69±10.10), (42.40 ± 8.35), (32.11±4.22), (37.12±4.90), (41.45±8.89) µg/ml, respectively (F=8.25, P<0.01); the PFC were (29.2±14.6), (28.0±20.0), (34.8±30.9), (33.2±25.1), (4.8±5.3) per 10(6) splenocyte, respectively (F=3.33, P<0.05); the HC50 were 82.3±6.5, 79.7±4.6, 75.8±4.1, 74.9±3.6, 70.8±2.1, respectively (F=9.99, P<0.01);the LPS-induced splenocyte proliferation were 0.21±0.10, 0.21±0.14, 0.26±0.12, 0.25±0.14, 0.07±0.06, respectively (F=4.18, P<0.05). CONCLUSION: The genetically modified drought-resistant wheat T349 was substantially equivalent to parental wheat in the effects on immune organs and immunologic functions of mice, and it didn't show immunotoxicity.