Description: The northward flowing Antarctic Intermediate Water (AAIW) is a major contributor to the large-scale meridional circulation of water masses in the Atlantic. Together with bottom and thermocline water, AAIW replaces North Atlantic Deep Water that penetrates into the South Atlantic from the North. On the northbound propagation of AAIW from its formation area in the south-western region of the Argentine Basin, the AAIW progresses through a complex spreading pattern at the base of the main thermocline. This paper presents trajectories of 75 subsurface floats, seeded at AAIW depth. The floats were acoustically tracked, covering a period from December 1992 to October 1996, Discussions of selected trajectories focus on mesoscale kinematic elements that contribute to the spreading of AAIW. In the equatorial region, intermittent westward and eastward currents were observed, suggesting a seasonal cycle of the AAIW flow direction. At tropical latitudes, just offshore the intermediate western boundary current, the southward advection of an anticyclonic eddy was observed between 5 degrees S and 11 degrees S. Farther offshore, the flow lacks an advective pattern and is governed by eddy diffusion. The westward subtropical gyre return current at about 28 degrees S shows considerable stability, with the mean kinetic energy to eddy kinetic energy ratio being around one. Farther south, the eastward deeper South Atlantic Current is dominated by large-scale meanders with particle velocities in excess of 60 cm s(-1). At the Brazil-Falkland Current Confluence Zone, a cyclonic eddy near 40 degrees S 50 degrees W seems to act as injector of freshly mixed AAIW into the subtropical gyre. In general, much of the mixing of the various blends of AAIW is due to the activity of mesoscale eddies, which frequently reoccupy similar positions. (C) 1999 Elsevier Science Ltd. All rights reserved.

Description: Phospholipase C-η (PLCη) enzymes are a class of phosphatidylinositol 4,5-bisphosphate-hydrolyzing enzymes involved in intracellular signaling. PLCη2 can sense Ca 2+ (stimulated by ∼1 µM free Ca 2+ ) suggesting that it can amplify transient Ca 2+ signals. PLCη enzymes possess an EF-hand domain composed of two EF-loops; a canonical 12-residue loop (EF-loop 1) and a non-canonical 13-residue loop (EF-loop 2). Ca 2+ -binding to synthetic peptides corresponding to EF-loops 1 and 2 of PLCη2 and EF-loop 1 of calmodulin (as a control) was examined by 2D-[ 1 H, 1 H] TOCSY NMR. Both PLCη2 EF-loop peptides bound Ca 2+ in a similar manner to that of the canonical calmodulin EF-loop 1, particularly at their N-terminus. A molecular model of the PLCη2 EF-hand domain, constructed based upon the structure of calmodulin, suggested both EF-loops may participate in Ca 2+ -binding. To determine whether the EF-hand is responsible for Ca 2+ -sensing, inositol phosphate accumulation was measured in COS7 cells transiently expressing wild-type or mutant PLCη2 proteins. Addition of 70 µM monensin (a Na + /H + antiporter that increases intracellular Ca 2+ ) induced a 4 to 7-fold increase in wild-type PLCη2 activity. In permeabilized cells, PLCη2 exhibited a ∼4-fold increase in activity in the presence of 1 µM free Ca 2+ . The D256A (EF-loop1) mutant exhibited a ∼10-fold reduction in Ca 2+ -sensitivity and was not activated by monensin, highlighting the involvement of EF-loop 1 in Ca 2+ -sensing. Involvement of EF-loop 2 was examined using D292A, H296A, Q297A and E304A mutants. Interestingly, the monensin responses and Ca 2+ -sensitivities were largely unaffected by the mutations, indicating that the non-canonical EF-loop 2 is not involved in Ca 2+ -sensing. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.