Decontamination studies: Battelle-Northwest Laboratories, December 1964-- August 1965

From ninth meeting of the USAEC reactor decontamination information exchange group; Washington, District of Columbia, USA (1 Sep 1965). The decontamination activity described includes: laboratory studies to evaluate reagents, and actual decontamination of 2 steam generators at New Production Reactor. ln laboratory tests, a proprietery oxalic acid solution appeared to be more effective th:dn sny other tried. No excessive corrosion was noted. Special reegents to dissolve high fired ceramic core materials (UO/sub 2/ and PuO/sub 2/) are being developed and evaluated. Phosphorous acid, sulfuric acid and a mixture of sulfuric and nitric acids were effective. Corrosion of 304 stainless steel was low. Two N Reactor steam generators were decontaminated to facilitate inspection and repair. The APSUL procedure was tried, but control of concentrations was inadequate and decontamination factors were low, ranging from 1.6 to 9.0. No excessive corrosion was noted. (auth

A Dynamin–Cortactin–Arp2/3 Complex Mediates Actin Reorganization in Growth Factor-stimulated Cells

The mechanisms by which mammalian cells remodel the actin cytoskeleton in response to motogenic stimuli are complex and a topic of intense study. Dynamin 2 (Dyn2) is a large GTPase that interacts directly with several actin binding proteins, including cortactin. In this study, we demonstrate that Dyn2 and cortactin function to mediate dynamic remodeling of the actin cytoskeleton in response to stimulation with the motogenic growth factor platelet-derived growth factor. On stimulation, Dyn2 and cortactin coassemble into large, circular structures on the dorsal cell surface. These “waves” promote an active reorganization of actin filaments in the anterior cytoplasm and function to disassemble actin stress fibers. Importantly, inhibition of Dyn2 and cortactin function potently blocked the formation of waves and subsequent actin reorganization. These findings demonstrate that cortactin and Dyn2 function together in a supramolecular complex that assembles in response to growth factor stimulation and mediates the remodeling of actin to facilitate lamellipodial protrusion at the leading edge of migrating cells

The Association of ASAP1, an ADP Ribosylation Factor-GTPase Activating Protein, with Focal Adhesion Kinase Contributes to the Process of Focal Adhesion Assembly

ASAP1 (ADP ribosylation factor [ARF]- GTPase-activating protein [GAP] containing SH3, ANK repeats, and PH domain) is a phospholipid-dependent ARF-GAP that binds to and is phosphorylated by pp60(Src). Using affinity chromatography and yeast two-hybrid interaction screens, we identified ASAP1 as a major binding partner of protein tyrosine kinase focal adhesion kinase (FAK). Glutathione S-transferase pull-down and coimmunoprecipitation assays showed the binding of ASAP1 to FAK is mediated by an interaction between the C-terminal SH3 domain of ASAP1 with the second proline-rich motif in the C-terminal region of FAK. Transient overexpression of wild-type ASAP1 significantly retarded the spreading of REF52 cells plated on fibronectin. In contrast, overexpression of a truncated variant of ASAP1 that failed to bind FAK or a catalytically inactive variant of ASAP1 lacking GAP activity resulted in a less pronounced inhibition of cell spreading. Transient overexpression of wild-type ASAP1 prevented the efficient organization of paxillin and FAK in focal adhesions during cell spreading, while failing to significantly alter vinculin localization and organization. We conclude from these studies that modulation of ARF activity by ASAP1 is important for the regulation of focal adhesion assembly and/or organization by influencing the mechanisms responsible for the recruitment and organization of selected focal adhesion proteins such as paxillin and FAK