The effects of spore age and sterilization on spore germination and early gametophyte development were investigated in the fern, Platycerium bifurcatum. The highest germination percentage of sterilized spores was obtained with 2-3 month old spores. Further increase in spore age leads to a decline in germination and primary rhizoid initiation. In contrast, spore age had no effect on the germination of unsterilized spores, where maximum response was observed with spores of both storage periods tested, 2 and 14 months. Increasing spore age delays early gametophyte development. In cultures of sterilized spores, this was evident from both a decrease in the length of the primary rhizoid and the decreased number of rhizoids and eel Although longer primary rhizoids developed from unsterilized spores of both ages, after 1 other growth parameters of gametophytes were similar or even lower compared t " sterilized spores.
Cell lines of Taxus x media Rehd. were established via embryo and callus culture and grown on B5 medium containing 10 microM 2,4-D and 1 microM kinetin. Jasmonic acid (JA) was used to elicit taxane synthesis in a selected yew cell line. 100 microM JA was added 7 days after subculture. JA strongly increased taxane content in the cells and in the medium. At the time of the highest amount in elicited cultures, the enhancement of paclitaxel production was 19-fold and 4-fold in the cells and medium, respectively, compared to controls (non-elicited cultures). The time course of taxane accumulation in the cells and in the medium and the release of taxanes into the medium were not changed after JA elicitation.
Quality assurance is a prerequisite for accurate and reliable results in food and feed testing, ISO/IEC 17025 being recognized worldwide as the base standard. A flexible scope of accreditation enables testing laboratories to react quickly to customer demand and to cope with the large number of new methods, which have to be introduced in the laboratory. Precisely defined procedures for the validation of methods, together with performance and acceptance criteria, are the key points for flexible scope of accreditation. Testing for genetically modified organisms (GMO) is a challenging exercise, especially with more GMOs entering the world market. We describe here the organization and performance of validating quantitative detection methods for GMO testing in the context of the European Union legislation. Operational procedures for method validation organized by the Community Reference Laboratory for Genetically Modified Food and Feed, assisted by the European Network of GMO Laboratories, are described. A protocol for validating methods within an individual laboratory is proposed and discussed in terms of the requirements of flexible scope of accreditation. The system setup can be an example for other similar fields of analytical work.
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