Efficient markerless gene deletions in Pseudomonas protegens Pf-5 using a upp-based counterselective system.

OBJECTIVES: Developing a counterselective system for efficient markerless gene deletions in biocontrol strain P. protegens Pf-5. RESULTS: We successfully implemented a markerless deletion of upp in Pf-5 to obtain the 5-FU resistant strain Pf5139. With this strain, we performed markerless gene deletions for each component of Gac/Rsm system and a 17 kb DNA fragment with the deletion ratio of 20 to 50%, and efficiently constructed a strain with triple deletions based on the suicide plasmid pJQ200UPP. In addition, there is no obvious connection between the deleted fragment length and the deletion ratio. CONCLUSION: The upp-based counterselective system in this study is efficient and valuable for markerless gene deletions in Pf-5, indicating that it has great potential in the study of gene function and in the application of genome reduction for Pseudomonas strains.

[Clinical diagnosis and treatment of superior tibial fracture complicating with crotch injury of distal popliteal artery].

OBJECTIVE: To investigate the clinical effects of treatment for superior tibial fracture complicating with crotch injury of distal popliteal artery by an alternative micro-surgical operation. METHODS: During Feb. 2002 to Oct. 2007, there were 19 patients with superior tibial fracture complicating with crotch injury of distal popliteal artery included 15 males and 4 females aged from 21 to 48 years (means 35 years). There were 6 cases complicating with fracture of tibial plateau, 3 cases complicating with nerve injury. The tibial fracture were fixed with external fixator and the anterior tibial artery and vein and posterior tibial artery and vein were treated by transplantable great saphenous vein (Y-shape) combined with windowing for interosseous membrane by the posterior and anterolateral incision. Evaluations of clinical effect were performed according to Rasmussen functional score system. RESULTS: All patients survived after operation. All fracture achieved bony union, the union time was from 3 to 14 months (means 5.5 months). All patients were followed-up for from 8 to 23 months (means 13 months). The mean Rasmussen functional score was (27.0 + 2.9). The results were excellent in 11 cases, good in 7, and fair in 1. CONCLUSION: The surgical exploration should be done as soon as possible when diagnosis of injuries of large arteries is definite or highly suspected. Simultaneous reconstruction of both posterior tibial artery and anterior tibial artery associated with vein can reduce the rate of disability and recover function of limb.