Phytochelatin (PC) plays an important role in heavy metal detoxification in plants and other living organisms. Therefore, we overexpressed an Arabidopsis PC synthase (AtPCS1) in transgenic Arabidopsis with the goal of increasing PC synthesis, metal accumulation, and metal tolerance in these plants. Transgenic Arabidopsis plants were selected, designated pcs lines, and analyzed for tolerance to cadmium (Cd). Transgenic pcs lines showed 12-to 25-fold higher accumulation of AtPCS1 mRNA, and production of PCs increased by 1.3-to 2.1-fold under 85 m CdCl 2 stress for 3 d when compared with wild-type plants. Cd tolerance was assessed by measuring root length of plants grown on agar medium containing 50 or 85 m CdCl 2 . Pcs lines paradoxically showed hypersensitivity to Cd stress. This hypersensitivity was also observed for zinc (Zn) but not for copper (Cu). The overexpressed AtPCS1 protein itself was not responsible for Cd hypersensitivity as transgenic cad1-3 mutants overexpressing AtPCS1 to similar levels as those of pcs lines were not hypersensitive to Cd. Pcs lines were more sensitive to Cd than a PC-deficient Arabidopsis mutant, cad1-3, grown under low glutathione (GSH) levels. Cd hypersensitivity of pcs lines disappeared under increased GSH levels supplemented in the medium. Therefore, Cd hypersensitivity in pcs lines seems due to the toxicity of PCs as they existed at supraoptimal levels when compared with GSH levels.Contamination of soils and waters with toxic heavy metals contributes to serious worldwide environmental and human health problems. These heavy metal pollutants have been discharged mainly by mining and combustion of fossil fuels during the period of global industrialization.A promising new technology, referred to as phytoremediation, offers promise for clean up of polluted areas in a cost-effective and environmentfriendly manner (Salt et al., 1995(Salt et al., , 1998Raskin et al., 1997). This technology involves removal of toxic heavy metals from contaminated soils and waters, or rendering them harmless by accumulating, chelating, or transforming these contaminants into biologically inactive forms through green plants. One possible approach for phytoremediation is to use "hyperaccumulators," plant species that have evolved to accumulate high concentrations of heavy metals in their biomass. However, most known hyperaccumulators tend to grow slowly, and produce relatively low biomass (Cunningham et al., 1995). Due to these limitations, genetic and molecular investigations of plant defense mechanisms involved in heavy metal stress have been under way to improve the efficiency of phytoremediation.Plants can produce Cys-rich peptides such as glutathione (GSH), phytochelatins (PCs), or metallothioneins (MTs) for detoxification or homeostasis of heavy metals (Rauser, 1999; Cobbett, 2000a Cobbett, , 2000b. PCs are a family of small enzymatically synthesized peptides having a general structure of (␥-Glu-Cys) nGly where n equals 2 to 11 (Rauser, 1990). These peptides are rapidly synthesized in response to ...

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SUMMARY An 18 year old woman presented with fulminant pneumococcal bacteraemia and subsequently died with multisystem organ failure. A search for diseases predisposing to overwhelming encapsulated bacterial infections was negative except for previously undiagnosed systemic lupus erythematosus (SLE). This case emphasises the severity of immune system dysfunction in some patients with SLE, regardless of immunosuppressive treatment. The possible relation between Fc receptor dysfunction and pneumococcal bacteraemia in SLE is discussed.

A plasmid-mediated transformation system has been developed for the xylose-fermenting yeast Pichia stipitis. We found that plasmid vectors containing the Saccharomyces cerevisiae 2 mu replicon and the kanamycin resistance gene (KmR) could be introduced into the Pichia cells and maintained as extrachromosomal elements. Pichia transformants containing such vectors will be resistant to the antibiotic geneticin that can be inactivated by the protein product of KmR. Plasmids identical to those used for transformation can be recovered from the Pichia transformants. Protocols for transformation of P. stipitis by the CaCl2-polyethylene glycol-protoplast process or by direct electroporation of intact Pichia cells have both been developed.