Plan apochromat 40 1.3 oil dic

Confocal images were taken on a Zeiss LSM 710 confocal microscope equipped with 10× (Zeiss, Fluar 10×/0.5) and 40× (Zeiss, Plan-Apochromat 40×/1.3 Oil DIC) objectives. Zen 2012 software was used for image acquisition. For illustration purposes, Z-stack images were collapsed onto a single image by ImageJ using maximum-intensity projection and pseudocolored into different acquisition channels using an RGB plug-in.

Salmonella transformed with the eGFP-pBAD plasmid (a gift from Michael Davidson, Addgene plasmid #54762; http://n2t.net/addgene:54762; RRID:Addgene_54762) was used to confirm intracellular localization. Images of infected cells were acquired every hour using a Zeiss LSM 780 laser scanning confocal microscope equipped with a Plan-Apochromat 40×/1.3 Oil DIC or Plan-Apochromat 63×/1.4 Oil DIC objective (Zeiss, Jena, Germany). Single mages and time-lapse series were acquired using the ZEN 2012 Black software (Zeiss). Differential interference contrast was used for visualization of living cells on a TPMT detector. GFP fluorescence in Salmonella was quantitated by excitation at 488 nm with the argon laser and an emission at 490–569 nm in the Channel mode.