“…However, to detect minor fluctuations of other amino acid levels, which may be manifested as a result of the expression of the E. coli TD, may require large sample sizes, due to high inherent variation. Therefore, if the E. coli TD gene can be optimized for use in a selection scheme, given the potential for negative developmental abnormalities being generated ( Figure 2) and/or alteration of intracellular amino acid profile as a consequence of constitutive perturbation of the aspartate family biosynthetic pathway, additional measures, such as recombination approaches (Dale and Ow 1991;Zuo et al 2001) or the simultaneous delivery of two T-DNA elements (Komari et al 1996;Xing et al 2000), would undoubtedly need to be taken for the subsequent removal of the TD transgene from the genome.…”