Effects of Transgenic cry1Ca Rice on the Development of Xenopus laevis

The Ecotoxicology of Microbial Insecticides and Their Toxins in Genetically Modified Crops: An Overview

The use of microbial insecticides and their toxins in biological control and transgenic plants has increased their presence in the environment. Although they are natural products, the main concerns are related to the potential impacts on the environment and human health. Several assays have been performed worldwide to investigate the toxicity or adverse effects of these microbial products or their individual toxins. This overview examines the published data concerning the knowledge obtained about the ecotoxicity and environmental risks of these natural pesticides. The data presented show that many results are difficult to compare due to the diversity of measurement units used in the different research data. Even so, the products and toxins tested present low toxicity and low risk when compared to the concentrations used for pesticide purposes. Complementary studies should be carried out to assess possible effects on human health.

Effects of straw leachates from Cry1C-expressing transgenic rice on the development and reproduction of Daphnia magna

The transgenic rice line T1C-19 provides high resistance to lepidopteran pests because of the synthesis of the Bacillus thuringiensis (Bt) insecticidal protein Cry1C. It thus shows good prospect for commercial planting in China. Species of Cladocera, an order of aquatic arthropods commonly found in aquatic ecosystems such as rice paddies, might be exposed to the insecticidal protein released from Bt-transgenic rice-straw residues. For the study reported herein, we used Daphnia magna (water flea) as a representative of Cladocera to evaluate whether aquatic arthropods are adversely affected when exposed to Bt rice-straw leachates. We exposed D. magna to M4 medium containing various volume percentages of medium that had been incubated with T1C-19 rice straw or rice straw from its non-transformed near-isoline Minghui 63 (MH63) for 21 days. Compared with pure M4 medium (control), the fitness and developmental and reproduction parameters of D. magna decreased significantly when exposed to rice-straw leachates; conversely, no significant differences between the T1C-19 and MH63 rice-straw leachate treatments were observed, indicating that the Bt rice straw leachate did not adversely affect this non-target species.

Safety Assessment of Bacillus thuringiensis Insecticidal Proteins Cry1C and Cry2A with a Zebrafish Embryotoxicity Test

As a result of the large-scale planting of transgenic Bacillus thuringiensis (Bt) crops, fish would be exposed to freely soluble Bt insecticidal protein(s) that are released from Bt crop tissues into adjacent bodies of water or by way of direct feeding on deposited plant material. To assess the safety of two Bt proteins Cry1C and Cry2A to fish, we used zebrafish as a representative species and exposed their embryos to 0.1, 1, and 10 mg/L of the two Cry proteins until 132 h post-fertilization and then several developmental, biochemical, and molecular parameters were evaluated. Chlorpyrifos (CPF), a known toxicant to aquatic organisms, was used as a positive control. Although CPF exposure resulted in significant developmental, biochemical, and molecular changes in the zebrafish embryos, there were almost no significant differences after Cry1C or Cry2A exposure. Thus, we conclude that zebrafish embryos are not sensitive to Cry1C and Cry2A insecticidal proteins at test concentrations.

Effects of 60-Week Feeding Diet Containing Bt Rice Expressing the Cry1Ab Protein on the Offspring of Inbred Wuzhishan Pigs Fed the Same Diet

We evaluated the chronic effects of Bt rice carrying the Cry1Ab protein (1.64 mg/kg) on offspring of highly inbred WZSP, fed with Bt rice for 360 days, in a 60-week feeding study. The WZSP offspring (n = 27) were assigned to two groups (Minghui86 group, female n = 6, male n = 5; Bt group, female n = 11, male n = 5). The average obtained Cry1Ab protein dosage for female and male pigs was 1.003 and 1.234 mg/kg body weight after 10 weeks of feeding, respectively. The experimental feed in the study was nutritionally matched in both groups. The average daily gain and feed conversion ratio of the females in week 3 and males from weeks 1 to 10 were different between the Bt and Minghui86 groups (P < 0.05), and the body weight of the male pigs in week 2 was greater in the Minghui86 group than that of the Bt group (P < 0.05). No other differences were observed, and there were no significant differences in the serum sex steroid level, hematology parameters, relative organ weights, or histopathology. Although differences in some serum chemistry parameters (alanine aminotransferase of female pigs and alkaline phosphatase of male pigs) were observed, they were not considered treatment-related. On the basis of these results, long-term intake of transgenic rice carrying Cry1Ab protein exerts no unintended adverse effects on WZSP offspring.

Impact on environment, ecosystem, diversity and health from culturing and using GMOs as feed and food

Modern agriculture provides the potential for sustainable feeding of the world's increasing population. Up to the present moment, genetically modified (GM) products have enabled increased yields and reduced pesticide usage. Nevertheless, GM products are controversial amongst policy makers, scientists and the consumers, regarding their possible environmental, ecological, and health risks. Scientific-and-political debates can even influence legislation and prospective risk assessment procedure. Currently, the scientifically-assessed direct hazardous impacts of GM food and feed on fauna and flora are conflicting; indeed, a review of literature available data provides some evidence of GM environmental and health risks. Although the consequences of gene flow and risks to biodiversity are debatable. Risks to the environment and ecosystems can exist, such as the evolution of weed herbicide resistance during GM cultivation. A matter of high importance is to provide precise knowledge and adequate current information to regulatory agencies, governments, policy makers, researchers, and commercial GMO-releasing companies to enable them to thoroughly investigate the possible risks.

Safety assessment of GM plants: An updated review of the scientific literature

In a wide revision of the literature conducted in 2000, I noted that the information in scientific journals on the safety of genetically modified (GM) foods in general, and GM plants in particular, was scarce. Of course, it was not sufficient to guarantee that the consumption of these products should not mean risks for the health of the consumers. Because of the scientific interest in GM organisms (GMOs), as well as the great concern that the consumption of GM foods/plants has raised in a number of countries, I conducted two subsequent revisions (2007 and 2011) on the adverse/toxic effects of GM plants. In the present review, I have updated the information on the potential adverse health effects of GM plants consumed as food and/or feed. With only a few exceptions, the reported studies in the last six years show rather similar conclusions; that is to say, the assessed GM soybeans, rice, corn/maize and wheat would be as safe as the parental species of these plants. However, in spite of the notable increase in the available information, studies on the long-term health effects of GM plants, including tests of mutagenicity, teratogenicity and carcinogenicity seem to be still clearly necessary.