Gentamicin

Example 12

Plant transformation—The Arabidopsis thaliana var Columbia (To plants) were transformed according to the Floral Dip procedure [Clough S J, Bent A F. (1998) Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana. Plant J. 16(6): 735-43; and Desfeux C, Clough S J, Bent A F. (2000) Female reproductive tissues were the primary targets of Agrobacterium-mediated transformation by the Arabidopsis floral-dip method. Plant Physiol. 123(3): 895-904] with minor modifications. Briefly, Arabidopsis thaliana Columbia (C010) T₀ plants were sown in 250 ml pots filled with wet peat-based growth mix. The pots were covered with aluminum foil and a plastic dome, kept at 4° C. for 3-4 days, then uncovered and incubated in a growth chamber at 18-24° C. under 16/8 hours light/dark cycles. The T₀ plants were ready for transformation six days before anthesis.

Single colonies of Agrobacterium carrying the binary vectors harboring the genes of some embodiments of the invention were cultured in YEBS medium (Yeast extract 1 gr/L, Beef extract 5 gr/L, MgSO₄*7H₂O, Bacto peptone 5 gr/L) supplemented with kanamycin (50 mg/L) and gentamycin (50 mg/L). The cultures were incubated at 28° C. for 48 hours under vigorous shaking to desired optical density at 600 nm of 0.85 to 1.1. Before transformation into plants, 60 μl of Silwet L-77 was added into 300 ml of the Agrobacterium suspension.

Transformation of T₀ plants was performed by inverting each plant into an Agrobacterium suspension such that the above ground plant tissue was submerged for 1 minute. Each inoculated T₀ plant was immediately placed in a plastic tray, then covered with clear plastic dome to maintain humidity and was kept in the dark at room temperature for 18 hours to facilitate infection and transformation. Transformed (transgenic) plants were then uncovered and transferred to a greenhouse for recovery and maturation. The transgenic T₀ plants were grown in the greenhouse for 3-5 weeks until siliques were brown and dry, then seeds were harvested from plants and kept at room temperature until sowing.

For generating T₁ and T₂ transgenic plants harboring the genes of some embodiments of the invention, seeds collected from transgenic T₀ plants were surface-sterilized by exposing to chlorine fumes (6% sodium hypochlorite with 1.3% HCl) for 100 minutes. The surface-sterilized seeds were sown on culture plates containing half-strength Murashig-Skoog (Duchefa); 2% sucrose; 0.5% plant agar; 50 mg/L kanamycin; and 200 mg/L carbenicylin (Duchefa). The culture plates were incubated at 4° C. for 48 hours and then were transferred to a growth room at 25° C. for three weeks. Following incubation, the T₁ plants were removed from culture plates and planted in growth mix contained in 250 ml pots. The transgenic plants were allowed to grow in a greenhouse to maturity. Seeds harvested from T₁ plants were cultured and grown to maturity as T2 plants under the same conditions as used for culturing and growing the T₁ plants.

Example 4

Since no mortality was observed in mice injected with PGN5+mucE, it was determined whether cells of this strain might localize differently than VE2 cells within the mice post-injection. To test this, the luxCDABEG operon was used to tag each strain with bioluminescence. VE2 and PGN5+mucE both carry gentamicin resistance genes, while the plasmids used for labeling with bioluminescence required gentamicin sensitivity. Thus, the luxCDABEG operon was incorporated into the chromosome of PAO1 and PGN5, and then the pUCP20-pGm-mucE plasmid was introduced into each strain to induce alginate production and mucoidy. Intraperitoneal injection of C57BL/6 mice with bioluminescent PAO1+mucE showed either localization at the injection site or dissemination through the body, and lethality resulted in all mice injected (FIGS. 5A-5B). Conversely, localization at the injection site but no dissemination was observed with bioluminescent PGN5+mucE, and no mortality was observed in injected mice (FIGS. 5C-5D).