The Gac-rsm pathway is a global regulatory network that governs mayor lifestyle and metabolic changes in gamma-proteobacteria. In a previous study, we uncovered the role of CsrA proteins promoting growth and repressing motility, alginate production and virulence in the model phytopathogen Pseudomonas syringae pv. tomato (Pto) DC3000. Here, we focus on the expression and regulation of the rsm regulatory sRNAs, since Pto DC3000 exceptionally has seven variants (rsmX1-5, rsmY and rsmZ). The presented results offer further insights into the functioning of the complex Gac-rsm pathway and the interplay among its components. Overall, rsm expressions reach maximum levels at high cell densities, are unaffected by surface detection, and require GacA for full expression. The rsm levels of expression and GacA-dependence are determined by the sequences found in their −35/-10 promoter regions and GacA binding boxes, respectively. rsmX5 stands out for being the only rsm in Pto DC3000 whose high expression does not require GacA, constituting the main component of the total rsm pool in a gacA mutant. The deletion of rsmY and rsmZ had minor effects on Pto DC3000 motility and virulence phenotypes, indicating that rsmX1-5 can functionally replace them. On the other hand, rsmY or rsmZ overexpression in a gacA mutant did not revert its phenotype. Additionally, a negative feedback regulatory loop in which the CsrA3 protein promotes its own titration by increasing the levels of several rsm RNAs in a GacA-dependent manner has been disclosed as part of this work.
TX 75083-3836, U.S.A., fax 01-972-952-9435.
AbstractThe tanker Prestige, carrying 77,000 Tm of heavy fuel, sank in 3,850 m of water 153 nautical miles off the north coast of Spain in November 2002. The ship broke apart and, for several months afterward, large quantities of spilt fuel washed ashore in Galicia and elsewhere.Repsol YPF, although in no way connected to the vessel or its cargo, was appointed by the Spanish government to recover the fuel remaining in the wreck. Repsol YPF subsequently selected Sonsub as its main contractor.This paper describes the required operations performed during the final wreck fuel recovery project, mainly focus ing on deepwater (up to 4,000 meters) and offshore operations.A project overview and details of other aspects of the project are described in separate papers, see References.Innovative deepwater equipment and procedures were involved during these operations, both due to water depth and the atypical activities to be performed: several vessels required on the surface, simultaneous ROV operations in nearly 4,000 meters of water depth, the tapping onto the wreck's tanks, the transfer of extremely viscous fuel into specially designed shuttles, the recovery of these shuttles to surface and offloading them into a dynamically positioned FSO.The Repsol YPF Prestige Recovery Project has won the prestigious Energy Engineering Project of the Year at the Platts Global Energy Awards for 2004.
TX 75083-3836, U.S.A., fax 01-972-952-9435.
AbstractIn November 2002, the Prestige oil tanker sank in 3,850 meters of water depth offshore Spain carrying some 77,000 tons of heavy fuel. During the sinking, and for a period of several months, a large amount of fuel was spilt and ended up mainly in the shores of Galicia (Northwest Spain). The wreck continued to leak fuel at slowly decreasing rates.Repsol YPF, though in no way connected to the vessel or its cargo, was appointed by the Spanish government to recover the fuel remaining inside the wreck. Later Repsol YPF selected Sonsub as the main contractor.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.