Richard J. Weld

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 An Agrobacterium tumefaciens-mediated transformation method has been developed for onions (Allium cepa L.) using immature embryos as the explant source. Transgenic plants were recovered from the open-pollinated onion cultivar Canterbury Longkeeper at a maximum transformation frequency from immature embryos of 2.7%. The method takes between 3–5 months from(More)
Phage therapy is complicated by the self-replicating nature of phage. It is difficult to extrapolate from in vitro phage growth data to in vivo expectations, difficult to interpret in vivo data and difficult to generalize from one in vivo situation to another. Various generic models of phage growth have been used as the theoretical basis for understanding(More)
The study of gene function in filamentous fungi is a field of research that has made great advances in very recent years. A number of transformation and gene manipulation strategies have been developed and applied to a diverse and rapidly expanding list of economically important filamentous fungi and oomycetes. With the significant number of fungal genomes(More)
The transient nature of T-DNA expression was studied with a gfp reporter gene transferred to Nicotiana plumbaginifolia suspension cells fromAgrobacterium tumefaciens. Individual GFP-expressing protoplasts were isolated after 4 days' co-cultivation. The protoplasts were cultured without selection and 4 weeks later the surviving proto-calluses were again(More)
Trichoderma spp. have served as models for asexual reproduction in filamentous fungi for over 50 years. Physical stimuli, such as light exposure and mechanical injury to the mycelium, trigger conidiation; however, conidiogenesis itself is a holistic response determined by the cell's metabolic state, as influenced by the environment and endogenous biological(More)
Geobacter-dominated biofilms can be selected under stringent conditions that limit the growth of competing bacteria. However, in many practical applications, such stringent conditions cannot be maintained and the efficacy and stability of these artificial biofilms may be challenged. In this work, biofilms were selected on low-potential anodes (-0.36 V vs(More)
Direct toxicity assessment (DTA) techniques seek to measure the impact of toxic chemicals on biological materials resident in the environment. This study features the use of freeze-dried bacterial cells in combination with a rapid DTA analyser, SciTOX™. The effects of three factors—cryoprotectant type, bacterial strain, and storage temperature—were tested(More)
Ascospores from the phytopathogenic fungus Sclerotinia sclerotiorum were transformed to hygromycin B resistance by co-cultivation with Agrobacterium tumefaciens. Transformed spores germinated and grew on PDA supplemented with 100 ug/ml hygromycin B. The presence of mitotically stable hph gene integration at random sites in the genome was confirmed by PCR(More)
Through their ability to directly transfer electrons to electrodes, Geobacter sp. are key organisms for microbial fuel cell technology. This study presents a simple method to reproducibly select Geobacter-dominated anode biofilms from a mixed inoculum of bacteria using graphite electrodes initially poised at -0.25, -0.36 and -0.42 V vs. Ag/AgCl. The(More)
Three separate genetic strategies, based upon the induced expression of three different genes (lacZ, selA and nuoA) were tested to provide the SciTox assay with sensitive and specific detection of the antibiotic tetracycline (Tet). All three strategies relied on gene induction from the Tn10 tetA promoter. Both lacZ and nuoA biosensors responded specifically(More)