Transgenes for tea?

Effects of genetically modified T2A-1 rice on the GI health of rats after 90-day supplement

Bacillus thuringiensis insecticidal toxin (Bt) rice will be commercialized as a main food source. Traditional safety assessments on genetically modified products pay little attention on gastrointestinal (GI) health. More data about GI health of Bt rice must be provided to dispel public' doubts about the potential effects on human health. We constructed an improved safety assessment animal model using a basic subchronic toxicity experiment, measuring a range of parameters including microflora composition, intestinal permeability, epithelial structure, fecal enzymes, bacterial activity, and intestinal immunity. Significant differences were found between rice-fed groups and AIN93G-fed control groups in several parameters, whereas no differences were observed between genetically modified and non-genetically modified groups. No adverse effects were found on GI health resulting from genetically modified T2A-1 rice. In conclusion, this study may offer a systematic safety assessment model for GM material with respect to the effects on GI health.

Gene transfer events and their occurrence in selected environments

Genes encoding virulence determinants are transferred between species in many different environments. In this review we describe gene transfer events to and from different species of bacteria, from bacteria to plants, and from plants to bacteria. Examples of the setting for these transfer events include: the GI tract, the rumen, the oral cavity, and in food matrixes. As a case study, the flux of virulence factors from E.coli O157:H7 is described as an example of gene flow in the environment.

Transgenic maize in the presence of ampicillin modifies the metabolic profile and microbial population structure of bovine rumen fluidin vitro

Recently, transgenic crops have been considered as possible donors of transgenes that could be taken up by micro-organisms under appropriate conditions. In anin vitrorumen simulation system, effects of ampicillin on microbial communities growing either on rumen contents with transgenic maize carrying a gene that confers resistance to ampicillin or its isogenic counterpart as substrates were examined continuously over 13 d. Rate of production of SCFA was measured to determine functional changes in the rumen model and single-strand conformational polymorphism was used to detect alterations in structure of the microbial community. Rumen contents treated with ampicillin displayed a marked decrease in the rate of production of SCFA and diversity of the microbial community was reduced severely. In the presence of transgenic maize, however, the patterns of change of rumen micro-organisms and their metabolic profiles were different from that of rumen fluid incorporating maize bred conventionally. Recovery of propionate production was observed both in the rumen fluid fed transgenic and conventional maize after a delay of several days but recovery occurred earlier in fermenters fed transgenic maize. Alterations in the microbial population structures resulting from the ampicillin challenge were not reversed during the experimental run although there was evidence of adaptation of the microbial communities over time in the presence of the antibiotic, showing that populations with different microbial structures could resume a pre-challenge metabolic profile following the introduction of ampicillin, irrespective of the source of the plant material in the growth medium.

Engineering plants with increased disease resistance: what are we going to express?

To engineer plants with increased and durable disease resistance using transgenic technologies we must address two questions. First, what gene or genes do we want to express to improve disease resistance, and second, how are we going to express these genes so that crop yields are actually increased? Emerging technologies are providing us with a plethora of candidate genes that might lead to enhanced crop protection through genetic engineering. These genes can come from plants, from pathogens or from other organisms and several strategies for their manipulation show promise. Here, we discuss recent advances and consider future perspectives for producing plants with durable disease resistance.