Magnesium uptake of Arabidopsis transporters, AtMRS2-10 and AtMRS2-11, expressed in Escherichia coli mutants: Complementation and growth inhibition by aluminum.

Magnesium (Mg2+) plays a critical role in many physiological processes. Mg2+ transport systems in Salmonella have been well documented, but those in Escherichia coli have not been fully elucidated. We examined the effects of corA, mgtA, yhiD and corC gene deletion on Mg2+ transport in E. coli. We obtained every combination of double, triple and quadruple mutants. The corA and mgtA double mutant required addition of 10 mM Mg2+ to Luria-Bertani (LB) medium for growth, and the corA, mgtA and yhiD triple mutant TM2 required a higher Mg2+ concentration. The Mg2+ requirement of the quadruple mutant was similar to that of TM2. The results demonstrated that either CorA or MgtA is necessary for normal E. coli growth in LB medium and that YhiD plays a role in Mg2+ transport under high Mg2+ growth conditions in E. coli. The Arabidopsis Mg2+ transporters, AtMRS2-10 and AtMRS2-11, were heterologously expressed in TM2 cells. TM2 cells expressing AtMRS2-10 and AtMRS2-11 could grow in LB medium that had been supplemented with 1 mM Mg2+ and without Mg2+ supplementation, respectively, and cell growth was inhibited by 2 mM AlCl3. The results indicated that the growth of TM2 expressing AtMRS2-10 and AtMRS2-11 reflected these AtMRS2 function for Mg2+ and aluminum. The E. coli TM2 cells are useful for functional analysis of Arabidopsis MRS2 proteins.

[Usefulness and Problems of Intraoperative Monitoring for Unruptured Aneurysm Surgery with the Motor Evoked Potential].

It has been pointed out that the motor evoked potential(MEP)with a subdural electrode is useful in the intraoperative monitoring for unruptured aneurysm surgery. However, in some cases, we experienced postoperative ischemic complications despite evaluating the motor function via MEP monitoring. Herein, we have reported the usefulness and problems of intraoperative monitoring with MEP to evaluate brain dysfunction caused by insufficiency of cerebral blood flow. Out of 279 aneurysm surgery procedures, we performed MEP monitoring in 142 cases and successfully recorded in 126 cases. We compared the ischemic complication rate of the group for which MEP was monitored with that of the group for which MEP was not monitored. The whole ischemic complication rate was decreased in the group that underwent MEP monitoring. Thus, it was suggested that MEP monitoring was useful for avoiding ischemic complications. In internal carotid artery aneurysms, the amplitude of MEP changed and recovered in 2 cases and disappeared in one case. In anterior cerebral artery aneurysms, the amplitude of MEP changed and recovered in 2 cases. In middle cerebral artery aneurysms, the amplitude of MEP changed and recovered in 5 cases. We could avoid ischemic complications by intraoperative MEP monitoring in many cases. However, in some cases, we found ischemic complications that were not detected by MEP monitoring with a subdural electrode. In these cases, transcranial stimulation in combination with subdural electrode might be effective in avoiding ischemic complications that might occur after dural closure.