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Sample records for 79th anaheim ca

  1. 33 CFR 80.1114 - San Pedro Bay-Anaheim Bay, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Pedro Bay-Anaheim Bay, CA. 80.1114 Section 80.1114 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1114 San Pedro Bay—Anaheim Bay,...

  2. 33 CFR 80.1114 - San Pedro Bay-Anaheim Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Pedro Bay-Anaheim Bay, CA. 80.1114 Section 80.1114 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1114 San Pedro Bay—Anaheim Bay,...

  3. 75 FR 1362 - City of Anaheim, CA, California Independent System Operator Corporation; Notice of Filing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-11

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission City of Anaheim, CA, California Independent System Operator Corporation... the California Independent System Operator Corporation filed is seventh annual revision to...

  4. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Radio and Television Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Radio and Television section of the proceedings contains the following 13 papers: "Two Pacific Powers View the World: News on CBS and TBS Television" (Anne Cooper-Chen); "Nicholas Johnson: The Public's Defender on the Federal Communication Commission, 1966-1973" (Max V. Grubb); "News Tips, TV Viewers, and Computer Links: A Follow-Up Story"…

  5. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Qualitative Studies Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Qualitative Studies section of the proceedings contains the following 13 papers: "Writing as Theater: The Marketing of the Digital Word" (Sally McMillan); "Rethinking Ideology: Polysemy, Pleasure and Hegemony in Television Culture" (Luis Rivera-Perez); "Low Power FM: A Small History" (Gregory J. Adamo); "The Residue of Culture: An Ellulian…

  6. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). International Communications Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The international communications section of the Proceedings contains the following 14 papers: "Spinning Stories: Latin America and the World Wide Web" (Eliza Tanner); "Private-Enterprise Broadcasting and Accelerating Dependency: Case Studies from Nigeria and Uganda" (Folu Folarin Ogundimu); "The Transitional Media System of Post-Communist…

  7. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). History Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The history section of the Proceedings contains the following 17 papers: "A Bid for Legitimacy: The Women's Press Club Movement, 1881-1900" (Elizabeth V. Burt); "'Securing the Affections of Those People at This Critical Juncture': Newspaper Portrayal of Colonial-Native American Relations, 1754-1763" (David A. Copeland); "'The Unfortunate Conflict…

  8. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Miscellaneous Studies Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Miscellaneous Studies Division of these Proceedings contains the following 13 papers: "A Trend, Imagined or Real? A Comparative Study of Development Journalism and Public Journalism" (Jiafei Yin); "Investigative Reporting about Minorities in America" (Tim Gallimore and Lillian Dunlap); "A Defining Moment: Who Says What about Public Journalism"…

  9. 78 FR 78349 - Cities of Anaheim, Azusa, Banning, Colton, Pasadena, Riverside, CA v. Trans Bay Cable LLC; Notice...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-26

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Cities of Anaheim, Azusa, Banning, Colton, Pasadena, Riverside, CA v. Trans Bay Cable LLC; Notice of Complaint Take notice that on December 17, 2013, pursuant to sections 206 and 306 of the Federal Power Act (FPA);...

  10. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Advertising and Public Relations Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Advertising and Public Relations section of the proceedings contains the following 14 papers: "Toward an Understanding of Cultural Values Manifest in Advertising: A Content Analysis of Chinese Television Commercials from 1990 and 1995" (Hong Cheng); "The Impact of Advertising Distance on International Advertising: An Analysis of Creative…

  11. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Communication Theory and Methodology Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The communication theory and methodology section of the Proceedings contains the following 20 papers: "Political Adwatches and the Third-Person Effect" (Ekaterina Ognianova and others); "Understanding Adopters of Audio Information Services" (Kimberly A. Neuendorf and others); "A Principal-Agent Approach to the Study of Media Organizations: Toward…

  12. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Communication Technology and Policy Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The communication technology and policy section of the Proceedings contains the following 11 papers: "The Battle for the Net Frontier: Technology and Policy in an Age of Hype and Sensationalism" (Jan H. Samoriski); "Uses and Gratifications of the World Wide Web" (Barbara K. Kaye); "Comparing Consumer Feedback Channels: Newspapers versus…

  13. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Visual Communication and Science and Health Communication Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Visual Communication and Science and Health Communication section of the proceedings contains the following 12 papers: "The Designers' Toolbox: Newsroom Experience and Ideal Characteristics of Newspaper Designers" (Wayne Wanta and Lauren Danner); "Patterned Image of the Homeless: Discourse Analysis of Television News Narrative" (In-Sung Whang…

  14. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Mass Communication and Society Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The mass communication and society section of the Proceedings contains the following 17 papers: "Deviance in News Coverage of On-Line Communications: A Print Media Comparison" (Lisa M. Weidman); "Political Tolerance of Environmental Protest: The Roles of Generalized and Specialized Information" (Catherine A. Steele and Carol M. Liebler); "First…

  15. Proceedings of the Annual Meeting of the Association for Education in Journalism and Mass Communication (79th, Anaheim, CA, August 10-13, 1996). Status of Women and Minorities and Communication Division.

    ERIC Educational Resources Information Center

    Association for Education in Journalism and Mass Communication.

    The Status of Women and Minorities and Communication section of the proceedings contains the following 14 papers: "Who Harasses Women Journalists? A Qualitative Look at Sexual Harassment among U.S. Newswomen" (Kim Walsh-Childers and others); "Not There Yet--Coverage of Women in Foreign News: A 1995 Multi-National Study" (Anat First and Donald L.…

  16. 79th Street Rotunda, former fountain in foreground, now Boat Basin ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    79th Street Rotunda, former fountain in foreground, now Boat Basin Cafe, looking west. - Henry Hudson Parkway, Extending 11.2 miles from West 72nd Street to Bronx-Westchester border, New York County, NY

  17. Annual Proceedings of Selected Research and Development Papers Presented at the National Convention of the Association for Educational Communications and Technology (26th, Anaheim, California, 2003). Volume 1

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.; Crawford, Margaret, Ed.

    2003-01-01

    For the twenty-sixth year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the National AECT Convention in Anaheim, CA. The Proceedings of AECT's Convention are published in two volumes.…

  18. The O.C.: Our Guide to ALA in Anaheim

    ERIC Educational Resources Information Center

    Hardstark, Georgia

    2008-01-01

    For those who grew up in Orange County (O.C.), Disneyland is the metaphoric morsel of food that gets stuck between the teeth of someone one does not like. While D-land is a must-see for millions of visitors each year, there is much more to Anaheim. Although O.C. is portrayed on numerous reality TV shows as a mecca for rich white people with…

  19. Installation of 200 kW UTC PC-25 Natural Gas Fuel Cell At City of Anaheim Police Station

    SciTech Connect

    Dina Predisik

    2006-09-15

    The City of Anaheim Public Utilities Department (Anaheim) has been providing electric service to Anaheim residents and businesses for over a century. As a city in a high-growth region, identifying sources of reliable energy to meet demand is a constant requirement. Additionally, as more power generation is needed, locating generating stations locally is a difficult proposition and must consider environmental and community impacts. Anaheim believes benefits can be achieved by implementing new distributed generation technologies to supplement central plants, helping keep pace with growing demand for power. If the power is clean, then it can be delivered with minimal environmental impact. Anaheim started investigating fuel cell technology in 2000 and decided a field demonstration of a fuel cell power plant would help determine how the technology can best serve Anaheim. As a result, Anaheim completed the project under this grant as a way to gain installation and operating experience about fuel cells and fuel cell capabilities. Anaheim also hopes to help others learn more about fuel cells by providing information about this project to the public. Currently, Anaheim has hosted a number of requested tours at the project site, and information about the project can be found on Anaheim Public Utilities RD&D Project website. The Anaheim project was completed in four phases including: research and investigation, purchase, design, and construction. The initial investigative phase started in 2000 and the construction of the project was completed in February 2005. Since acceptance and startup of the fuel cell, the system has operated continuously at an availability of 98.4%. The unit provides an average of about 4,725 kilowatthours a day to the Utilities' generation resources. Anaheim is tracking the operation of the fuel cell system over the five-year life expectancy of the fuel stack and will use the information to determine how fuel cells can serve Anaheim as power generators.

  20. Overview of the 79th Annual Scientific Meeting of the Japanese Circulation Society – Late-Breaking Cardiovascular Medicine From Japan.

    PubMed

    Hokimoto, Seiji; Yasuda, Satoshi; Sueta, Daisuke; Tsujita, Kenichi; Sakamoto, Kenji; Yamamuro, Megumi; Izumiya, Yasuhiro; Arima, Yuichiro; Usuku, Hiroki; Sumida, Yoko; Kojima, Sunao; Kaikita, Koichi; Kanazawa, Hisanori; Yamabe, Hiroshige; Ogawa, Hisao

    2015-01-01

    The 79th Annual Scientific Meeting of the Japanese Circulation Society was held in Osaka on April 24-26, 2015. The main theme was "Late-breaking Cardiovascular Medicine from Japan". Recently, optimal medical treatment has been guided by evidence-based medicine. We aim to emphasize the research findings and advances in cardiology from Japan, in the hope that Japan will become one of the leaders in the field worldwide. Unlike previous meetings, this annual scientific meeting was held in late April. Approximately 18,000 people, including medical doctors, healthcare professionals, and management staff, attended. The meeting was successfully completed, and included discussions on state-of-the art medicine.

  1. "LJ" Report "Anaheim, ALA 2008": Amid the Fantasy, Doses of Reality

    ERIC Educational Resources Information Center

    Blumenstein, Lynn; Berry, John; Fialkoff, Francine; Fox, Bette-Lee; Hadro, Josh; Horrocks, Norman; Oder, Norman; Roncevic, Mirela

    2008-01-01

    If the resort city of Anaheim, California, home of Disneyland and its "imagineers," marked a departure from the urban reality of the typical American Library Association (ALA) annual conference, it was impossible, at this 2008 meeting, to avoid urgent library issues. How do libraries maintain their value and cultural presence as users turn to the…

  2. 33 CFR 334.930 - Anaheim Bay Harbor, Calif.; Naval Weapons Station, Seal Beach.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Weapons Station, Seal Beach. 334.930 Section 334.930 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay Harbor, Calif.; Naval Weapons Station, Seal Beach. (a) The restricted area. The water of Anaheim Bay Harbor between the east and west jetties at the United States Naval Weapons Station, Seal...

  3. 33 CFR 334.930 - Anaheim Bay Harbor, Calif.; Naval Weapons Station, Seal Beach.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Weapons Station, Seal Beach. 334.930 Section 334.930 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay Harbor, Calif.; Naval Weapons Station, Seal Beach. (a) The restricted area. The water of Anaheim Bay Harbor between the east and west jetties at the United States Naval Weapons Station, Seal...

  4. 33 CFR 334.930 - Anaheim Bay Harbor, Calif.; Naval Weapons Station, Seal Beach.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Weapons Station, Seal Beach. 334.930 Section 334.930 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay Harbor, Calif.; Naval Weapons Station, Seal Beach. (a) The restricted area. The water of Anaheim Bay Harbor between the east and west jetties at the United States Naval Weapons Station, Seal...

  5. 33 CFR 334.930 - Anaheim Bay Harbor, Calif.; Naval Weapons Station, Seal Beach.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Weapons Station, Seal Beach. 334.930 Section 334.930 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay Harbor, Calif.; Naval Weapons Station, Seal Beach. (a) The restricted area. The water of Anaheim Bay Harbor between the east and west jetties at the United States Naval Weapons Station, Seal...

  6. Sex Ed...And the Reds? Reconsidering the Anaheim Battle over Sex Education, 1962-1969

    ERIC Educational Resources Information Center

    Mehlman, Natalia

    2007-01-01

    By December 1968, the Anaheim Family Life and Sex Education (FLSE) program, celebrated since its formal introduction in 1965 as one of the most progressive in the nation, was being smeared as communistic and perverse. Local activists in this Orange County city had been congregating in hotel rooms and homes, screening cautionary films for the…

  7. 33 CFR 334.930 - Anaheim Bay Harbor, Calif.; Naval Weapons Station, Seal Beach.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Weapons Station, Seal Beach. 334.930 Section 334.930 Navigation and Navigable Waters CORPS OF ENGINEERS... Bay Harbor, Calif.; Naval Weapons Station, Seal Beach. (a) The restricted area. The water of Anaheim Bay Harbor between the east and west jetties at the United States Naval Weapons Station, Seal...

  8. Fluid mechanics phenomena in microgravity; ASME Winter Annual Meeting, Anaheim, CA, Nov. 8-13, 1992

    NASA Technical Reports Server (NTRS)

    Siginer, Dennis A. (Editor); Weislogel, Mark M. (Editor)

    1992-01-01

    This paper is the first in a series of symposia presenting research activity in microgravity fluid mechanics. General topics addressed include two-phase flow and transport phenomena, thermo-capillary flow, and interfacial stability. Papers present mathmatical models of fluid dynamics in the microgravity environment. Applications suggested include space manufacturing and storage of liquids in low gravity.

  9. 33 CFR 80.1114 - San Pedro Bay-Anaheim Bay, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Beach Breakwater East End Light 1. (b) A line drawn from Long Beach Channel Entrance Light 2 to Long Beach Light. (c) A line drawn from Los Angeles Main Entrance Channel Light 2 to Los Angeles Light....

  10. 33 CFR 80.1114 - San Pedro Bay-Anaheim Bay, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Beach Breakwater East End Light 1. (b) A line drawn from Long Beach Channel Entrance Light 2 to Long Beach Light. (c) A line drawn from Los Angeles Main Entrance Channel Light 2 to Los Angeles Light....

  11. 33 CFR 80.1114 - San Pedro Bay-Anaheim Bay, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Beach Breakwater East End Light 1. (b) A line drawn from Long Beach Channel Entrance Light 2 to Long Beach Light. (c) A line drawn from Los Angeles Main Entrance Channel Light 2 to Los Angeles Light....

  12. 1990 ACSM-ASPRS Fall Convention, Anaheim, CA, Nov. 5-10, 1990, Technical Papers

    SciTech Connect

    Not Available

    1990-01-01

    The present conference on surveying, mapping, photogrammetry, and remote sensing encompasses the U.S. Geological Survey (USGS), the North American Vertical Datum (NAVD), the Geographic Information System and geodetic control, developments in geodetic surveying, and applications for remote sensing and photogrammetric techniques. Specific issues addressed include federal coordination of mapping, a USGS data format, the use of NAVD for flood insurance assessment, geodetic reference upgrades, the Airborne Data Acquisition and Registration system, conducting inventories of wetlands with remote sensing, chronologically evaluating urban growth, and analyzing substrate type and water depth with SPOT imagery. Also addressed are vehicle crush measurements via photogrammetry, the role of remote sensing in comprehensive environmental planning, watershed characterization using the Landsat TM, hardwoods identification with Landsat TM data, image motion effects, and computer modeling of urban area detection.

  13. International SAMPE Symposium and Exhibition, 37th, Anaheim, CA, Mar. 9-12, 1992, Proceedings

    NASA Technical Reports Server (NTRS)

    Grimes, Glenn C. (Editor); Turpin, Russell (Editor); Forsberg, Gustaf (Editor); Rasmussen, Benjamin M. (Editor); Whitney, Jim (Editor)

    1992-01-01

    The present conference discusses the industrial and transportation markets for advanced composites, novel NASA and military applications of advanced materials, composite space structures, sandwich structures, composite tooling and processing, advanced epoxy compositions, composites repair, commercial applications of advanced resins, metal-matrix composites, adhesive compositions, ultrahigh-temperature composites, failure analyses, testing methods for composites, and bismaleimides and polyimides. Also discussed are composite structures design, innovations in composite reinforcement, nonautoclave-processed composites, molecular composites, design and manufacture processes with thermoplastics, automation in manufacturing, technologies for large component fabrication, damage-limitation design practices, thermoplastic-matrix composites, industrial applications of composites, and process controls in composites manufacturing.

  14. 33 CFR 110.215 - Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach, California; Naval...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ....S. Naval Weapons Station, Seal Beach, California; Naval Explosives Anchorage. 110.215 Section 110... REGULATIONS Anchorage Grounds § 110.215 Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach... permission from the Commanding Officer, Naval Weapons Station, Seal Beach, California. This officer...

  15. 33 CFR 110.215 - Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach, California; Naval...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ....S. Naval Weapons Station, Seal Beach, California; Naval Explosives Anchorage. 110.215 Section 110... REGULATIONS Anchorage Grounds § 110.215 Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach... permission from the Commanding Officer, Naval Weapons Station, Seal Beach, California. This officer...

  16. 33 CFR 110.215 - Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach, California; Naval...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ....S. Naval Weapons Station, Seal Beach, California; Naval Explosives Anchorage. 110.215 Section 110... REGULATIONS Anchorage Grounds § 110.215 Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach... permission from the Commanding Officer, Naval Weapons Station, Seal Beach, California. This officer...

  17. 33 CFR 110.215 - Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach, California; Naval...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ....S. Naval Weapons Station, Seal Beach, California; Naval Explosives Anchorage. 110.215 Section 110... REGULATIONS Anchorage Grounds § 110.215 Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach... permission from the Commanding Officer, Naval Weapons Station, Seal Beach, California. This officer...

  18. 33 CFR 110.215 - Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach, California; Naval...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ....S. Naval Weapons Station, Seal Beach, California; Naval Explosives Anchorage. 110.215 Section 110... REGULATIONS Anchorage Grounds § 110.215 Anaheim Bay Harbor, California; U.S. Naval Weapons Station, Seal Beach... permission from the Commanding Officer, Naval Weapons Station, Seal Beach, California. This officer...

  19. Annual Proceedings of Selected Research and Development Papers Presented at the Annual Convention of the Association for Educational Communications and Technology (36th, Anaheim, California, 2013). Volume 1

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.

    2013-01-01

    For the thirty-sixth year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the annual AECT Convention in Anaheim, California. The Proceedings of AECT's Convention are published in two…

  20. Annual Proceedings of Selected Research and Development Papers Presented at the Annual Convention of the Association for Educational Communications and Technology (36th, Anaheim, California, 2013). Volume 2

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.

    2013-01-01

    For the thirty-sixth year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the annual AECT Convention in Anaheim, California. The Proceedings of AECT's Convention are published in two…

  1. Annual Proceedings of Selected Research and Development Papers Presented at the National Convention of the Association for Educational Communications and Technology (30th, Anaheim, California, 2007). Volume 2

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.

    2007-01-01

    For the thirtieth year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the National AECT Convention in Anaheim, California. The Proceedings of AECT's Convention are published in two…

  2. Annual Proceedings of Selected Research and Development Papers Presented at the Annual Convention of the Association for Educational Communications and Technology (33rd, Anaheim, California, 2010). Volume 1

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.

    2010-01-01

    For the thirty-third year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the national AECT Convention in Anaheim, California. The Proceedings of AECT's Convention are published in two…

  3. Annual Proceedings of Selected Research and Development Papers Presented at the National Convention of the Association for Educational Communications and Technology (30th, Anaheim, California, 2007). Volume 1

    ERIC Educational Resources Information Center

    Simonson, Michael, Ed.

    2007-01-01

    For the thirtieth year, the Research and Theory Division of the Association for Educational Communications and Technology (AECT) is sponsoring the publication of these Proceedings. Papers published in this volume were presented at the National AECT Convention in Anaheim, California. The Proceedings of AECT's Convention are published in two…

  4. Abstracts of Presented Papers [at the] NARST Annual Meeting (67, Anaheim, CA, March 26-29, 1994).

    ERIC Educational Resources Information Center

    Izak, Dina, Ed.; Chia, Siu Yoon, Ed.

    Included in this publication are abstracts of papers presented at a meeting on science teaching. Also included are: an index of authors and the sessions in which they presented papers, a strand index listing sessions that pertain to that strand, and an address list of all the authors. Strands include alternative assessment; approaches to research;…

  5. Institute of Environmental Sciences, Annual Technical Meeting, 35th, Anaheim, CA, May 1-5, 1989, Proceedings

    SciTech Connect

    Not Available

    1989-01-01

    The present conference discusses the combination of thermal and high level acoustics, the correlation between vibration and computer operator response aboard a UH-1H helicopter, microcalorimetric methods for corrosion rate measurement, a building-block approach for life cycle environmental profile development, fatigue life assessment for a leaded electronic component, determination of product fragility for packaging optimization, and a decision-theoretic concept of thermal reliability growth acceleration. Also discussed are a practical method for the tailoring of environmental stress screens, product verification during stress screening, aircraft gunfire response predictions, simple fixture concepts for multiaxis vibration testing, a shock and vibration data base for military equipment, terpenes as environmentally safe halogenated solvent replacements, air toxic risk assessment, a new method of airflow visualization, particle generation during fiber abrasion, and particle transport in computer disk drives.

  6. Time to Take Inventory in Agricultural Education. Distinguished Lecture, American Vocational Association Convention, Anaheim, CA, December 4, 1979.

    ERIC Educational Resources Information Center

    Lee, Jasper S.

    1980-01-01

    The time has arrived to determine the essential, productive elements of the inventory of practices in vocational education in agriculture/agribusiness. We must determine those items in the inventory which benefit our program and those which do not. (LRA)

  7. A new virus-induced gene silencing vector based on Euphorbia mosaic virus-Yucatan peninsula for NPR1 silencing in Nicotiana benthamiana and Capsicum annuum var. Anaheim.

    PubMed

    Villanueva-Alonzo, Hernan J; Us-Camas, Rosa Y; López-Ochoa, Luisa A; Robertson, Dominique; Guerra-Peraza, Orlene; Minero-García, Yereni; Moreno-Valenzuela, Oscar A

    2013-05-01

    Virus-induced gene silencing is based on the sequence-specific degradation of RNA. Here, a gene silencing vector derived from EuMV-YP, named pEuMV-YP:ΔAV1, was used to silence ChlI and NPR1 genes in Nicotiana benthamiana. The silencing of the ChlI transcripts was efficient in the stems, petioles and leaves as reflected in tissue bleaching and reduced transcript levels. The silencing was stable, reaching the flowers and fruits, and was observed throughout the life cycle of the plants. Additionally, the silencing of the NPR1 gene was efficient in both N. benthamiana and Capsicum annuum. After silencing, the plants' viral symptoms increased to levels similar to those seen in wild-type plants. These results suggest that NPR1 plays a role in the compatible interactions of EuMV-YP N. benthamiana and EuMV-C. annum var. anaheim.

  8. Computational mechanics - Advances and trends; Proceedings of the Session - Future directions of Computational Mechanics of the ASME Winter Annual Meeting, Anaheim, CA, Dec. 7-12, 1986

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K. (Editor)

    1986-01-01

    The papers contained in this volume provide an overview of the advances made in a number of aspects of computational mechanics, identify some of the anticipated industry needs in this area, discuss the opportunities provided by new hardware and parallel algorithms, and outline some of the current government programs in computational mechanics. Papers are included on advances and trends in parallel algorithms, supercomputers for engineering analysis, material modeling in nonlinear finite-element analysis, the Navier-Stokes computer, and future finite-element software systems.

  9. Establishing an IEZ at the K-25 Site With Realism - ANS 2008 Annual Meeting - June 8-12, 2008 Anaheim, CA

    SciTech Connect

    Kimball, K.D.

    2008-06-08

    The requirement from ANSI/ANS-8.3 states: (1) a criticality alarm system meeting the requirements of this standard shall be installed in areas where personnel would be subject to an excessive radiation dose; and (2) excessive dose = any dose to personnel corresponding to an absorbed dose from neutrons and gamma rays equal to or greater than 0.12 Gy (12 rad) in free air. The requirement was misconstrued to imply that the Immediate Evaluation Zone (IEZ) had to cover out to 12 Rad of dose. This mis-interpretation prompted the following official clarification: The standard does not attempt to define the area that is to be evacuated, which is considered a management responsibility and outside the scope of this Standard. What we wanted was an IEZ that: (1) depended on the facility characteristics and hazards; (2) departed from the one 'Size' fits all mentality; (3) balanced the risk of a criticality with the risk of evacuating; and (4) was consistent with the emergency planning process. What they have is a facility that is a mile long; a facility that was falling down around them; a facility where workers are routinely in fall protection; and a facility where high noise is the normal condition. They ended up matching ANS-8.23 with their EPHA and DSA and eliminated 12 Rad as the criterion; integrated Emergency Planning into the process; established evacuation zones using DSA consequence levels; and introduced time dependence into the evacuation process.

  10. Advanced materials technology '87; Proceedings of the Thirty-second International SAMPE Symposium and Exhibition, Anaheim, CA, Apr. 6-9, 1987

    SciTech Connect

    Carson, R.; Burg, M.; Kjoller, K.J.; Riel, F.J.

    1987-01-01

    The present conference on advanced materials considers topics in the fields of novel bismaleimide resin systems, USAF Materials Laboratory technology-development forecasts, high performance thermoplastics, ceramic-matrix composites, high temperature thermosetting resins, pressure-sensitive adhesives, advanced filament-winding methods, metal-matrix composites, and impact damage tolerance and control in filament-wound structures. Also discussed are spacecraft materials applications, epoxy resin technology, automated materials processing equipment, asbestos-substitute fibers, thermally hardened electronic materials, carbon/carbon composites, and pultrusion technology.

  11. 46 CFR 7.120 - Mexican/United States border to Point Fermin, CA.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... drawn from Anaheim Bay East Jetty Light “6” to Anaheim Bay West Jetty Light “5”; thence to Long Beach Breakwater East End Light “1”. A line drawn from Long Beach Entrance Light “2” to Long Beach Light. A...

  12. 46 CFR 7.120 - Mexican/United States border to Point Fermin, CA.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... drawn from Anaheim Bay East Jetty Light “6” to Anaheim Bay West Jetty Light “5”; thence to Long Beach Breakwater East End Light “1”. A line drawn from Long Beach Entrance Light “2” to Long Beach Light. A...

  13. 46 CFR 7.120 - Mexican/United States border to Point Fermin, CA.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... drawn from Anaheim Bay East Jetty Light “6” to Anaheim Bay West Jetty Light “5”; thence to Long Beach Breakwater East End Light “1”. A line drawn from Long Beach Entrance Light “2” to Long Beach Light. A...

  14. 46 CFR 7.120 - Mexican/United States border to Point Fermin, CA.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... drawn from Anaheim Bay East Jetty Light “6” to Anaheim Bay West Jetty Light “5”; thence to Long Beach Breakwater East End Light “1”. A line drawn from Long Beach Entrance Light “2” to Long Beach Light. A...

  15. 46 CFR 7.120 - Mexican/United States border to Point Fermin, CA.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... drawn from Anaheim Bay East Jetty Light “6” to Anaheim Bay West Jetty Light “5”; thence to Long Beach Breakwater East End Light “1”. A line drawn from Long Beach Entrance Light “2” to Long Beach Light. A...

  16. Structure and Thermal Expansion of Calcium-Thorium Apatite, [Ca4]F[Ca2Th4]T[(SiO4)6]O2.

    PubMed

    Bulanov, Evgeny N; Wang, Jingxian; Knyazev, Alexander V; White, Tim; Manyakina, Marina E; Baikie, Tom; Lapshin, Alexander N; Dong, ZhiLi

    2015-12-01

    Thorium silicate apatite with the formula [Ca3.84Th0.16]F[Ca2.79Th3.21]T(SiO4)6O2 · x(H) was synthesized by solid-state reaction, and its structure refined in P63/m from powder X-ray diffraction (XRD) data using the Rietveld method (a = 9.50172(9) Å, c = 6.98302(8) Å, V = 545.98(1) Å(3); R-Bragg = 2.102%). It was found that thorium partitions strongly to the tunnel (T) 6h position rather than the framework (F) 4f site. Fourier transform infrared spectroscopy revealed only SiO4 tetrahedron, with SiO5 and SiO6 groups, sometimes observed in siliceous apatites absent, at least to the limit of detection of this technique. Thermal expansion of the thorium apatite determined by high-temperature XRD from 298-1173 K found Δa (0.87%) dilation to exceed Δc (0.73%) with increasing temperature consistent with other silicate apatites. PMID:26562353

  17. The Ca(2+)/Calmodulin/CaMKK2 Axis: Nature's Metabolic CaMshaft.

    PubMed

    Marcelo, Kathrina L; Means, Anthony R; York, Brian

    2016-10-01

    Calcium (Ca(2+)) is an essential ligand that binds its primary intracellular receptor calmodulin (CaM) to trigger a variety of downstream processes and pathways. Central to the actions of Ca(2+)/CaM is the activation of a highly conserved Ca(2+)/CaM kinase (CaMK) cascade that amplifies Ca(2+) signals through a series of subsequent phosphorylation events. Proper regulation of Ca(2+) flux is necessary for whole-body metabolism and disruption of Ca(2+) homeostasis has been linked to various metabolic diseases. Here we provide a synthesis of recent advances that highlight the roles of the Ca(2+)/CaMK axis in key metabolic tissues. An appreciation of this information is critical to understanding the mechanisms by which Ca(2+)/CaM-dependent signaling contributes to metabolic homeostasis and disease.

  18. Origin of 48Ca

    NASA Astrophysics Data System (ADS)

    Clayton, Donald D.; Krishnan, Tracy D.; Meyer, Bradley S.

    1997-02-01

    We stress conceptual understanding of why 48Ca survives low-entropy expansions but not high-entropy expansions. Type Ia supernovae are thereby demonstrated to be its source. The interdependence of the quasiequilibrium cluster (QSE) and the number of heavy nuclei is the key. By varying reaction rates, we show that nuclear cross sections are not a sensitive need for the problem of 48Ca nucleosynthesis.

  19. HB 2578--Relating to the School Meals Program. Testimony, 79th Texas State Legislature (April 26, 2005)

    ERIC Educational Resources Information Center

    Hagert, Celia

    2005-01-01

    The Center for Public Policy Priorities supports HB 2574. Why encourage school districts to offer free meals to all students? The link between adequate nutrition and improved academic performance creates a clear incentive for Texas to increase participation in the school breakfast and lunch programs, particularly among low-income children.…

  20. Association of Higher Education Facilities Officers: Proceedings of the Annual Meeting (79th, Indianapolis, Indiana, July 26-29, 1992).

    ERIC Educational Resources Information Center

    Association of Physical Plant Administrators, Alexandria, VA. Association of Higher Education Facilities Officers.

    This volume presents 24 conference papers: (1) "Total Quality Management, or Nirvana--Are We There Yet?" by Gary L. Reynolds; (2) "Managing by the Seat of Your Pants: Vision, Innovation, and Creativity" by Roy M. Dalebozik; (3) "Understanding Cross-Cultural Issues in the Workplace" by Ann M. Jenkins; (4) "Drugs in the Workplace: An Ounce of…

  1. Los Angeles, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This rare cloud and smog free view of Los Angeles, CA (34.0N, 118.5W) is a result of strong Santa Ana winds blowing from the east. Both cultural and natural features are well displayed and all of the major streets, highways and freeways can be traced in their entirety throughout the city as well as the major business and commercial sections. On the eastern edge of the scene, the San Andreas fault cuts across from southeast to northwest.

  2. Sulfide capacities of CaO-CaF2-CaCl2 melts

    NASA Astrophysics Data System (ADS)

    Simeonov, Simeon; Sakai, Toshihiko; Maeda, Masafumi

    1992-06-01

    The sulfide capacityC_{s^{2 - } } = ({text{pct S}}^{{text{2 - }}} )(p_{{text{O}}_{text{2}} } /p_{{text{S}}_{text{2}} } )^{1/2} ) of CaO-CaF2-CaCl2 slag was determined at temperatures from 1000 °C to 1300 °C by equilibrating molten slag, molten silver, and CO-CO2-Ar gas mixture. The sulfide capacity increases with replacing CaCl2 by CaF2 in slags of constant CaO contents. The sulfide capacity also increases with increasing temperature as well as with increasing CaO content at a constant ratio of CaF2/CaCl2 of unity. A linear relationship between the sulfide capacity and carbonate capacity in literature was observed on a logarithmic scale.

  3. Measurement of CA1P and CA in leaves

    SciTech Connect

    Moore, B.d.; Kobza, J.; Seemann, J.R. )

    1990-05-01

    Carboxyarabinitol-1-phosphate (CA1P) and carboxyarabinitol (CA) were assayed in leaves by isotope dilution. {sup 14}C-labeled standards were synthesized from (2-{sup 14}C) CABP using acid (CA1P) or alkaline (CA) phosphatase. Either was added to boiling 80% EtOH along with liquid N{sub 2}-killed leaves. Each was largely purified by anion exchange chromatography. CA1P samples were subjected to 2D-TLE/TLC. The specific activity of the {sup 14}C-containing spot was measured using alkaline phosphatase. CA samples were run on an HPLC and the specific activity was determined using a UV monitor and a flow-through radioisotope detector. In 3 of the tested species, light/dark amount of CA1P (nmol/mg Chl) were kidney bean, 0.7/67; sugar beet, 0.8/33; and Alocasia, 0/3.4. Light/dark CA levels (nmol/mg Chl) in these respective species were 897/653, 3.2/3.5, and 5.7/4.6. These results support the hypothesis that CA is a product of CA1P metabolism in vivo under high light, but also indicate that CA is not the only intermediate involved in CA1P synthesis under low light/dark conditions.

  4. Ca(2+) Binding and Transport Studied with Ca(2+)/EGTA Buffers and (45)Ca(2+).

    PubMed

    Sehgal, Pankaj; Olesen, Claus; Møller, Jesper V

    2016-01-01

    The chapter describes procedures useful for determination of Ca(2+) binding by membranous Ca(2+)-ATPase based on the correction for the removal of Ca(2+) present in a non-bound state in the suspension medium. This is done by a filtration procedure that retains the membranous material on the Millipore filters. With suitable sucking devices it is possible to gently remove without dehydration nearly all medium from the Ca(2+) containing membranes, except that required for wetting of the filters on which they are deposited. Correction for this effect can be done with a double-filter where the radioactive content of the lower (protein-free) filter is subtracted from that present in the upper filter for calculation of Ca(2+) binding. This methodology can be used to study the effect of inhibitors on Ca(2+) binding and -transport, and with Ca(2+)/EGTA buffers to explore the Ca(2+) binding affinities and cooperative aspects of the two transport sites.

  5. Coachella Valley, CA

    NASA Technical Reports Server (NTRS)

    2001-01-01

    These band composites, acquired on June 4, 2000, cover a 11 by 13.5 km sub-scene in the Coachella Valley, CA. The area is shown by the yellow box on the full scene in the LOWER RIGHT corner, northwest of the Salton Sea. This is a major agricultural region of California, growing fruit and produce throughout the year. Different combinations of ASTER bands help identify the different crop types. UPPER LEFT: bands 3, 2, 1 as red, green, and blue (RGB); UPPER RIGHT: bands 4, 2, 1 as RGB; LOWER LEFT: bands 4, 3, 2 as RGB. The image is centered at 33.6 degrees north latitude, 116.1 degrees west longitude.

    The U.S. science team is located at NASA's Jet Propulsion Laboratory, Pasadena, Calif. The Terra mission is part of NASA's Science Mission Directorate.

  6. Dynamic buffering of mitochondrial Ca2+ during Ca2+ uptake and Na+-induced Ca2+ release

    PubMed Central

    Blomeyer, Christoph A.; Bazil, Jason N.; Stowe, David F.; Pradhan, Ranjan K.; Dash, Ranjan K.; Camara, Amadou K. S.

    2014-01-01

    In cardiac mitochondria, matrix free Ca2+ ([Ca2+]m) is primarily regulated by Ca2+ uptake and release via the Ca2+ uniporter (CU) and Na+/Ca2+ exchanger (NCE) as well as by Ca2+ buffering. Although experimental and computational studies on the CU and NCE dynamics exist, it is not well understood how matrix Ca2+ buffering affects these dynamics under various Ca2+ uptake and release conditions, and whether this influences the stoichiometry of the NCE. To elucidate the role of matrix Ca2+ buffering on the uptake and release of Ca2+, we monitored Ca2+ dynamics in isolated mitochondria by measuring both the extra-matrix free [Ca2+] ([Ca2+]e) and [Ca2+]m. A detailed protocol was developed and freshly isolated mitochondria from guinea pig hearts were exposed to five different [CaCl2] followed by ruthenium red and six different [NaCl]. By using the fluorescent probe indo-1, [Ca2+] and [Ca2+e]m were spectrofluorometrically quantified, and the stoichiometry of the NCE was determined. In addition, we measured NADH, membrane potential, matrix volume and matrix pH to monitor Ca2+-induced changes in mitochondrial bioenergetics. Our [Ca2+]e and [Ca2+]m measurements demonstrate that Ca2+ uptake and release do not show reciprocal Ca2+ dynamics in the extra-matrix and matrix compartments. This salient finding is likely caused by a dynamic Ca2+ buffering system in the matrix compartment. The Na+ - induced Ca2+ release demonstrates an electrogenic exchange via the NCE by excluding an electroneutral exchange. Mitochondrial bioenergetics were only transiently affected by Ca2+ uptake in the presence of large amounts of CaCl2, but not by Na+- induced Ca2+ release. PMID:23225099

  7. CaPTC Biennial Meetings

    Cancer.gov

    CaPTC hosts the 'Biennial Science of Global Prostate Cancer Disparities in Black Men' conference to address the growing global public health problem of prostate cancer among Black men in industrialized and developing countries.

  8. CaMKII-dependent SR Ca leak contributes to doxorubicin-induced impaired Ca handling in isolated cardiac myocytes

    PubMed Central

    Sag, Can M.; Köhler, Anne C.; Anderson, Mark E.; Backs, Johannes; Maier, Lars S.

    2011-01-01

    Objective Doxorubicin (DOX) is one of the most effective chemotherapeutic agents, but cardiotoxicity limits DOX therapy. Although the mechanisms are not entirely understood, reactive oxygen species (ROS) appear to be involved in DOX cardiotoxicity. Ca/calmodulin dependent protein kinase II (CaMKII) can be activated by ROS through oxidation and is known to contribute to myocardial dysfunction through Ca leakage from the sarcoplasmic reticulum (SR). Rationale We hypothesized that CaMKII contributes to DOX-induced defects in intracellular Ca ([Ca]i) handling. Methods Cardiac myocytes were isolated from wild-type (WT) adult rat hearts and from mouse hearts lacking the predominant myocardial CaMKII isoform (CaMKIIδ−/−, KO) vs. WT. Isolated cardiomyocytes were investigated 30 min after DOX (10 µmol/L) superfusion, using epifluorescence and confocal microscopy. Intracellular ROS-generation ([ROS]i) and [Ca]i handling properties were assessed. In a subset of experiments, KN-93 or AIP (each 1 µmol/L) were used to inhibit CaMKII. Melatonin (Mel, 100 µmol/L) served as ROS-scavenger. Western blots were performed to determine the amount of CaMKII phosphorylation and oxidation. Results DOX increased [ROS]i and led to significant diastolic [Ca]i overload in rat myocytes. This was associated with reduced [Ca]i transients, a 5.8-fold increased diastolic SR Ca leak and diminished SR Ca content. ROS-scavenging partially rescued Ca handling. Western blots revealed increased CaMKII phosphorylation, but not CaMKII oxidation after DOX. Pharmacological CaMKII inhibition attenuated diastolic [Ca]i overload after DOX superfusion and led to partially restored [Ca]i transients and SR Ca content, presumably due to reduced Ca spark frequency. In line with this concept, isoform-specific CaMKIIδ-KO attenuated diastolic [Ca]i overload and Ca spark frequency. Conclusions DOX exposure induces CaMKII-dependent SR Ca leakage, which partially contributes to impaired cellular [Ca]i homeostasis

  9. [CA 125--a tumor marker?].

    PubMed

    Pabst, T; Ludwig, C

    1995-06-17

    Tumor markers are useful tools in monitoring malignancies postoperatively or under hormone-/chemotherapy. In contrast, they usually lack diagnostic relevance and uncritical use may result in confusing situations. We describe three cases of diagnostic determinations of the tumor marker CA 125 resulting in subsequent partially invasive procedures. Based on these three cases, serum CA 125 levels were examined in 49 patients with abdominal diseases. We found CA 125 to be less a tumor product than an unspecific expression of stimulated mesothelial cells of the peritoneum. CA 125 was a marker for ascites (16 of 16 patients) and an indicator of infra-diaphragmatic involvement in non-Hodgkin's lymphoma (11 of 12 patients). Furthermore, 5 of 6 patients with inflammatory abdominal diseases showed elevated CA 125 levels, as did 13 of 15 patients with solid abdominal tumors of different histology (all non-ovarian cancer, no ascites). In conclusion, CA 125 remains a good marker for follow-up of ovarian cancer, but should not be used for diagnosis of abdominal processes.

  10. Ca2+ scraps: local depletions of free [Ca2+] in cardiac sarcoplasmic reticulum during contractions leave substantial Ca2+ reserve.

    PubMed

    Shannon, Thomas R; Guo, Tao; Bers, Donald M

    2003-07-11

    Free [Ca2+] inside the sarcoplasmic reticulum ([Ca2+]SR) is difficult to measure yet critically important in controlling many cellular systems. In cardiac myocytes, [Ca2+]SR regulates cardiac contractility. We directly measure [Ca2+]SR in intact cardiac myocytes dynamically and quantitatively during beats, with high spatial resolution. Diastolic [Ca2+]SR (1 to 1.5 mmol/L) is only partially depleted (24% to 63%) during contraction. There is little temporal delay in the decline in [Ca2+]SR at release junctions and between junctions, indicating rapid internal diffusion. The incomplete local Ca2+ release shows that the inherently positive feedback of Ca2+-induced Ca2+ release terminates, despite a large residual driving force. These findings place stringent novel constraints on how excitation-contraction coupling works in heart and also reveal a Ca2+ store reserve that could in principle be a therapeutic target to enhance cardiac function in heart failure.

  11. The site of net absorption of Ca from the intestinal tract of growing pigs and effect of phytic acid, Ca level and Ca source on Ca digestibility.

    PubMed

    González-Vega, J Caroline; Walk, Carrie L; Liu, Yanhong; Stein, Hans H

    2014-01-01

    An experiment was conducted to test the hypothesis that the standardised digestibility of Ca in calcium carbonate and Lithothamnium calcareum Ca is not different regardless of the level of dietary Ca, and that phytic acid affects the digestibility of Ca in these two ingredients to the same degree. The objectives were to determine where in the intestinal tract Ca absorption takes place and if there are measurable quantities of basal endogenous Ca fluxes in the stomach, small intestine or large intestine. Diets contained calcium carbonate or L. calcareum Ca as the sole source of Ca, 0% or 1% phytic acid and 0.4% or 0.8% Ca. A Ca-free diet was also formulated and used to measure endogenous fluxes and losses of Ca. Nine growing pigs (initial body weight 23.8 ± 1.3 kg) were cannulated in the duodenum and in the distal ileum, and faecal, ileal and duodenal samples were collected. Duodenal endogenous fluxes of Ca were greater (p < 0.05) than ileal endogenous fluxes and total tract endogenous losses of Ca, but ileal endogenous fluxes were less (p < 0.05) than total tract endogenous losses. Standardised digestibility of Ca was not affected by the level of phytic acid, but decreased (p < 0.05) as Ca level increased in L. calcareum Ca diets, but that was not the case if calcium carbonate was the source of Ca (interaction, p < 0.05). The standardised duodenal digestibility (SDD), standardised ileal digestibility (SID) and standardised total tract digestibility (STTD) of Ca were not different if calcium carbonate was the source of dietary Ca. However, the STTD of Ca in L. calcareum Ca was greater (p < 0.05) than the SID and SDD of Ca. The SDD, SID and STTD of Ca in calcium carbonate were greater (p < 0.05) than those of L. calcareum Ca. In conclusion, under the conditions of this experiment, standardised digestibility of Ca is not affected by the level of phytic acid, but may be affected by dietary Ca level depending on the Ca source. Calcium from calcium carbonate is mostly

  12. Routes of Ca2+ Shuttling during Ca2+ Oscillations: FOCUS ON THE ROLE OF MITOCHONDRIAL Ca2+ HANDLING AND CYTOSOLIC Ca2+ BUFFERS.

    PubMed

    Pecze, László; Blum, Walter; Schwaller, Beat

    2015-11-20

    In some cell types, Ca(2+) oscillations are strictly dependent on Ca(2+) influx across the plasma membrane, whereas in others, oscillations also persist in the absence of Ca(2+) influx. We observed that, in primary mesothelial cells, the plasmalemmal Ca(2+) influx played a pivotal role. However, when the Ca(2+) transport across the plasma membrane by the "lanthanum insulation method" was blocked prior to the induction of the serum-induced Ca(2+) oscillations, mitochondrial Ca(2+) transport was found to be able to substitute for the plasmalemmal Ca(2+) exchange function, thus rendering the oscillations independent of extracellular Ca(2+). However, in a physiological situation, the Ca(2+)-buffering capacity of mitochondria was found not to be essential for Ca(2+) oscillations. Moreover, brief spontaneous Ca(2+) changes were observed in the mitochondrial Ca(2+) concentration without apparent changes in the cytosolic Ca(2+) concentration, indicating the presence of a mitochondrial autonomous Ca(2+) signaling mechanism. In the presence of calretinin, a Ca(2+)-buffering protein, the amplitude of cytosolic spikes during oscillations was decreased, and the amount of Ca(2+) ions taken up by mitochondria was reduced. Thus, the increased calretinin expression observed in mesothelioma cells and in certain colon cancer might be correlated to the increased resistance of these tumor cells to proapoptotic/pronecrotic signals. We identified and characterized (experimentally and by modeling) three Ca(2+) shuttling pathways in primary mesothelial cells during Ca(2+) oscillations: Ca(2+) shuttled between (i) the endoplasmic reticulum (ER) and mitochondria, (ii) the ER and the extracellular space, and (iii) the ER and cytoplasmic Ca(2+) buffers.

  13. Controls on Sr/Ca and Mg/Ca in scleractinian corals: The effects of Ca-ATPase and transcellular Ca channels on skeletal chemistry

    NASA Astrophysics Data System (ADS)

    Emif Allison, Nicola; Cohen, Itay; Finch, Adrian A.; Erez, Jonathan

    2011-11-01

    The Sr/Ca of aragonitic coral skeletons is a commonly used palaeothermometer. However skeletal Sr/Ca is typically dominated by weekly-monthly oscillations which do not reflect temperature or seawater composition and the origins of which are currently unknown. To test the impact of transcellular Ca2+ transport processes on skeletal Sr/Ca, colonies of the branching coral, Pocillopora damicornis, were cultured in the presence of inhibitors of Ca-ATPase (ruthenium red) and Ca channels (verapamil hydrochloride). The photosynthesis, respiration and calcification rates of the colonies were monitored throughout the experiment. The skeleton deposited in the presence of the inhibitors was identified (by 42Ca spike) and analysed for Sr/Ca and Mg/Ca by secondary ion mass spectrometry. The Sr/Ca of the aragonite deposited in the presence of either of the inhibitors was not significantly different from that of the solvent (dimethyl sulfoxide) control, although the coral calcification rate was reduced by up to 66% and 73% in the ruthenium red and verapamil treatments, respectively. The typical precision (95% confidence limits) of mean Sr/Ca determinations within any treatment was <±1% and differences in skeletal Sr/Ca between treatments were correspondingly small. Either Ca-ATPase and Ca channels transport Sr2+ and Ca2+ in virtually the same ratio in which they are present in seawater or transcellular processes contribute little Ca2+ to the skeleton and most Ca is derived from seawater transported directly to the calcification site. Variations in the activities of Ca-ATPase and Ca-channels are not responsible for the weekly-monthly Sr/Ca oscillations observed in skeletal chronologies, assuming that the specificities of Ca transcellular transport processes are similar between coral genera.

  14. Controls on Sr/Ca and Mg/Ca in scleractinian corals: The effects of Ca-ATPase and transcellular Ca channels on skeletal chemistry

    NASA Astrophysics Data System (ADS)

    Allison, Nicola; Cohen, Itay; Finch, Adrian A.; Erez, Jonathan; EMIF

    2011-11-01

    The Sr/Ca of aragonitic coral skeletons is a commonly used palaeothermometer. However skeletal Sr/Ca is typically dominated by weekly-monthly oscillations which do not reflect temperature or seawater composition and the origins of which are currently unknown. To test the impact of transcellular Ca 2+ transport processes on skeletal Sr/Ca, colonies of the branching coral, Pocillopora damicornis, were cultured in the presence of inhibitors of Ca-ATPase (ruthenium red) and Ca channels (verapamil hydrochloride). The photosynthesis, respiration and calcification rates of the colonies were monitored throughout the experiment. The skeleton deposited in the presence of the inhibitors was identified (by 42Ca spike) and analysed for Sr/Ca and Mg/Ca by secondary ion mass spectrometry. The Sr/Ca of the aragonite deposited in the presence of either of the inhibitors was not significantly different from that of the solvent (dimethyl sulfoxide) control, although the coral calcification rate was reduced by up to 66% and 73% in the ruthenium red and verapamil treatments, respectively. The typical precision (95% confidence limits) of mean Sr/Ca determinations within any treatment was <±1% and differences in skeletal Sr/Ca between treatments were correspondingly small. Either Ca-ATPase and Ca channels transport Sr 2+ and Ca 2+ in virtually the same ratio in which they are present in seawater or transcellular processes contribute little Ca 2+ to the skeleton and most Ca is derived from seawater transported directly to the calcification site. Variations in the activities of Ca-ATPase and Ca-channels are not responsible for the weekly-monthly Sr/Ca oscillations observed in skeletal chronologies, assuming that the specificities of Ca transcellular transport processes are similar between coral genera.

  15. Large Ca2+-dependent facilitation of CaV2.1 channels revealed by Ca2+ photo-uncaging

    PubMed Central

    Lee, Shin-Rong; Adams, Paul J; Yue, David T

    2015-01-01

    Key points CaV2.1 channels constitute a dominant Ca2+ entry pathway into brain neurons, triggering downstream Ca2+-dependent processes such as neurotransmitter release. CaV2.1 is itself modulated by Ca2+, resulting in activity-dependent enhancement of channel opening termed Ca2+-dependent facilitation (CDF). Real-time Ca2+ imaging and Ca2+ uncaging here reveal that CDF turns out to be strikingly faster, more Ca2+ sensitive, and larger than anticipated on previous grounds. Robust resolution of the quantitative profile of CDF enables deduction of a realistic biophysical model for this process. These results suggest that CaV2.1 CDF would figure most prominently in short-term synaptic plasticity and cerebellar Purkinje cell rhythmicity. Abstract CaV2.1 (P-type) voltage-gated Ca2+ channels constitute a major source of neuronal Ca2+ current, strongly influencing rhythmicity and triggering neurotransmitter release throughout the central nervous system. Fitting with such stature among Ca2+ entry pathways, CaV2.1 is itself feedback regulated by intracellular Ca2+, acting through calmodulin to facilitate channel opening. The precise neurophysiological role of this calcium-dependent facilitation (CDF) remains uncertain, however, in large measure because the very magnitude, Ca2+ dependence and kinetics of CDF have resisted quantification by conventional means. Here, we utilize the photo-uncaging of Ca2+ with CaV2.1 channels fluxing Li+ currents, so that voltage-dependent activation of channel gating is no longer conflated with Ca2+ entry, and CDF is then driven solely by light-induced increases in Ca2+. By using this strategy, we now find that CDF can be unexpectedly large, enhancing currents by as much as twofold at physiological voltages. CDF is steeply Ca2+ dependent, with a Hill coefficient of approximately two, a half-maximal effect reached by nearly 500 nm Ca2+, and Ca2+ on/off kinetics in the order of milliseconds to tens of milliseconds. These properties were

  16. How Does Stochastic Ryanodine Receptor-Mediated Ca Leak Fail to Initiate a Ca Spark?

    PubMed Central

    Sato, Daisuke; Bers, Donald M.

    2011-01-01

    Spontaneous calcium (Ca) sparks are initiated by single ryanodine receptor (RyR) opening. Once one RyR channel opens, it elevates local [Ca] in the cleft space ([Ca]Cleft), which opens other RyR channels in the same Ca release unit (CaRU) via Ca-induced Ca-release. Experiments by Zima et al. (J. Physiol. 588:4743–4757, 2010) demonstrate that spontaneous Ca sparks occur only when intrasarcoplasmic-reticulum (SR) [Ca] ([Ca]SR) is above a threshold level, but that RyR-mediated SR Ca leak exists without Ca sparks well below this threshold [Ca]SR. We examine here how single RyR opening at lower [Ca]SR can fail to recruit Ca sparks at a CaRU, while still contributing to SR Ca leak. We assess this using a physiologically detailed mathematical model of junctional SR Ca release in which RyR gating is regulated by [Ca]SR and [Ca]Cleft. We find that several factors contribute to the failure of Ca sparks as [Ca]SR declines: 1), lower [Ca]SR reduces driving force and thus limits local [Ca]Cleft achieved and the rate of rise during RyR opening; 2), low [Ca]SR limits RyR open time (τO), which further reduces local [Ca]Cleft attained; 3), low τO and fast [Ca]Cleft dissipation after RyR closure shorten the opportunity for neighboring RyR activation; 4), at low [Ca]SR, the RyR exhibits reduced [Ca]Cleft sensitivity. We conclude that all of these factors conspire to reduce the probability of Ca sparks as [Ca]SR declines, despite continued RyR-mediated Ca leak. In addition, these same factors explain the much lower efficacy of L-type Ca channel opening to trigger local SR Ca release at low [Ca]SR during excitation-contraction coupling. Conversely, all of these factors are fundamentally important for increasing the propensity for pro-arrhythmic Ca sparks and waves in cardiac myocytes at high [Ca]SR. PMID:22098735

  17. Solar Ca II K Observations

    NASA Astrophysics Data System (ADS)

    Bertello, Luca; Pevtsov, Alexei A.; Tlatov, Andrey; Singh, Jagdev

    2016-07-01

    Some of the most important archives of past and current long-term solar synoptic observations in the resonance line of Ca II K are described here. These observations are very important for understanding the state of the solar magnetism on time scales up to several decades. The first observations of this kind began in 1904 at the Kodaikanal Observatory (India), followed by similar programs at different other locations. Regular full-disk Ca II K monitoring programs started in 1915 at the Mount Wilson Observatory (USA) and in 1917 at the National Solar Observatory of Japan. Beginning in 1919 and in 1926 regular observations were taken also at the Paris-Meudon Observatory (France) and at the "Donati solar tower telescope of the Arcetri Astrophysical Observatory in Italy, respectively. In 1926 the the Astronomical Observatory of the Coimbra University in Portugal started its own program of Ca II K observations. Although some of these programs have been terminated over the years, their data archives constitute a unique resource for studies of solar variability. In the early 1970s, the National Solar Observatory (NSO) at Sacramento Peak (USA) started a new program of daily Sun-as-a-star observations in the Ca II K line. Today the NSO is continuing these observations through its Synoptic Optical Long-term Investigations of the Sun (SOLIS) facility.

  18. EMRE Is a Matrix Ca(2+) Sensor that Governs Gatekeeping of the Mitochondrial Ca(2+) Uniporter.

    PubMed

    Vais, Horia; Mallilankaraman, Karthik; Mak, Don-On Daniel; Hoff, Henry; Payne, Riley; Tanis, Jessica E; Foskett, J Kevin

    2016-01-26

    The mitochondrial uniporter (MCU) is an ion channel that mediates Ca(2+) uptake into the matrix to regulate metabolism, cell death, and cytoplasmic Ca(2+) signaling. Matrix Ca(2+) concentration is similar to that in cytoplasm, despite an enormous driving force for entry, but the mechanisms that prevent mitochondrial Ca(2+) overload are unclear. Here, we show that MCU channel activity is governed by matrix Ca(2+) concentration through EMRE. Deletion or charge neutralization of its matrix-localized acidic C terminus abolishes matrix Ca(2+) inhibition of MCU Ca(2+) currents, resulting in MCU channel activation, enhanced mitochondrial Ca(2+) uptake, and constitutively elevated matrix Ca(2+) concentration. EMRE-dependent regulation of MCU channel activity requires intermembrane space-localized MICU1, MICU2, and cytoplasmic Ca(2+). Thus, mitochondria are protected from Ca(2+) depletion and Ca(2+) overload by a unique molecular complex that involves Ca(2+) sensors on both sides of the inner mitochondrial membrane, coupled through EMRE.

  19. Ca isotopic fractionation patterns in forest ecosystems

    NASA Astrophysics Data System (ADS)

    Kurtz, A. C.; Takagi, K.

    2012-12-01

    Calcium stable isotope ratios are an emerging tracer of the biogeochemical cycle of Ca that are just beginning to see significant application to forest ecosystems. The primary source of isotopic fractionation in these systems is discrimination against light Ca during uptake by plant roots. Cycling of vegetation-fractionated Ca establishes isotopically distinct Ca pools within a forest ecosystem. In some systems, the shallow soil exchangeable Ca pool is isotopically heavy relative to Ca inputs. This has been explained by preferential removal of light Ca from the soil. In other systems, the soil exchange pool is isotopically light relative to inputs, which is explained by recycling of plant-fractionated light Ca back into soil. Thus vegetation uptake of light Ca has been called on to account for both isotopically heavy and light Ca in the shallow soil exchange pools. We interpret patterns in ecosystem δ44Ca with the aid of a simple box model of the forest Ca cycle. We suggest that the δ44Ca of exchangeable Ca in the shallow soil pool primarily reflects the relative magnitude of three key fluxes in a forest Ca cycle, 1) the flux of external Ca into the system via weathering or atmospheric deposition, 2) the uptake flux of Ca from soils into the vegetation pool, and 3) the return flux of Ca to shallow soils via remineralization of leaf litter. Two observations that emerge from our model may aid in the application of Ca isotopes to provide insight into the forest Ca cycle. First, regardless of the magnitude of both vegetation Ca uptake and isotopic fractionation, the δ44Ca of the soil exchange pool will equal the input δ44Ca unless the plant uptake and remineralization fluxes are out of balance. A second observation is that the degree to which the shallow soil exchange pool δ44Ca can differ from the input ratio is controlled by the relative rates of biological uptake and external Ca input. Significant differences between soil exchange and input δ44Ca are seen only

  20. Decoding Ca2+ signals in plants

    NASA Technical Reports Server (NTRS)

    Sathyanarayanan, P. V.; Poovaiah, B. W.

    2004-01-01

    Different input signals create their own characteristic Ca2+ fingerprints. These fingerprints are distinguished by frequency, amplitude, duration, and number of Ca2+ oscillations. Ca(2+)-binding proteins and protein kinases decode these complex Ca2+ fingerprints through conformational coupling and covalent modifications of proteins. This decoding of signals can lead to a physiological response with or without changes in gene expression. In plants, Ca(2+)-dependent protein kinases and Ca2+/calmodulin-dependent protein kinases are involved in decoding Ca2+ signals into phosphorylation signals. This review summarizes the elements of conformational coupling and molecular mechanisms of regulation of the two groups of protein kinases by Ca2+ and Ca2+/calmodulin in plants.

  1. CaFe interstellar clouds

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Kozak, M.; Gnaciński, P.; Galazutdinov, G. A.; Beletsky, Y.; Krełowski, J.

    2007-07-01

    A new kind of interstellar cloud is proposed. These are rare (just a few examples among ~300 lines of sight) objects with the CaI 4227-Å, FeI 3720-Å and 3860-Å lines stronger than those of KI (near 7699 Å) and NaI (near 3302 Å). We propose the name `CaFe' for these clouds. Apparently they occupy different volumes from the well-known interstellar HI clouds where the KI and ultraviolet NaI lines are dominant features. In the CaFe clouds we have not found either detectable molecular features (CH, CN) or diffuse interstellar bands which, as commonly believed, are carried by some complex, organic molecules. We have found the CaFe clouds only along sightlines toward hot, luminous (and thus distant) objects with high rates of mass loss. In principle, the observed gas-phase interstellar abundances reflect the combined effects of the nucleosynthetic history of the material, the depletion of heavy elements into dust grains and the ionization state of these elements which may depend on irradiation by neighbouring stars. Based on data collected using the Maestro spectrograph at the Terskol 2-m telescope, Russia; and on data collected using the ESO Feros spectrograph; and on data obtained from the ESO Science Archive Facility acquired with the UVES spectrograph, Chile. E-mail: `arctur'@rambler.ru (AB); marizak@astri.uni.torun.pl (MK); pg@iftia.univ.gda.pl (PG); gala@boao.re.kr (GAG); ybialets@eso.org (YB); jacek@astri.uni.torun.pl (JK)

  2. Evolution of Seawater 44Ca/40Ca Through the Late Cretaceous and Cenozoic

    NASA Astrophysics Data System (ADS)

    Castillo, P. R.; Gopalan, K.; Norris, R. D.; MacIsaac, C.; Liu, X.; MacDougall, J. D.

    2009-12-01

    We analyzed the Ca concentrations and 44Ca/40Ca ratios of surface ocean planktonic (Morozovella, Acarinina, Dentoglobigerina) and benthic (Gavelinella) foraminifera of Late Cretaceous to Late Oligocene ages from DSDP and ODP sites in the Pacific, Atlantic and Indian oceans in order to fill a major gap in the Phanerozoic seawater 44Ca/40Ca curve (Farkass et al., Geochim. Cosmochim. Acta 71, 2007). Our new 44Ca/40Ca data indicate a general increase in foraminiferan-based seawater 44Ca/40Ca from ~-1.3 ‰ δ44Ca/40CaSW in Late Cretaceous to ~0.0 ‰ δ44Ca/40CaSW in Early Miocene (Heuser et al., Paleocean. 20, 2005; Sime et al., Geochim. Cosmochim. Acta 71, 2007). In detail, the 44Ca/40Ca ratio stepped abruptly from ~-1.3 ‰ δ44Ca/40CaSW to a slightly higher value of ~-1.1 ‰ δ44Ca/40CaSW across the Cretaceous-Tertiary (K/T) boundary. A slight positive excursion of ~0.2 ‰ above the background value occurred after the Paleocene Thermal Maximum (55 Ma) but otherwise, the Paleocene to Middle Eocene ratio is relatively stable at ~-1.0 ‰ δ44Ca/40CaSW. The most prominent increase in foraminiferan-based seawater 44Ca/40Ca occurred from Late Eocene to Late Oligocene, roughly coincident with the initial phase of the rapid and steady rise of marine carbonate 87Sr/86Sr ratio in the Tertiary (e.g., DePaolo and Ingram, Science 227, 1985).

  3. Fine tuning of cytosolic Ca 2+ oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed.

  4. [Effect of polycarbophil Ca on IBS].

    PubMed

    Mine, Tetsuya

    2006-08-01

    In this chapter, I mentioned the effect of polycarbophil Ca on IBS. IBS is classified into 3 types; diarrhea type, constipation type and combined type. Polycarbophil Ca is effective for all types of IBS.

  5. Fine tuning of cytosolic Ca (2+) oscillations.

    PubMed

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca (2+) oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca (2+) exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca (2+) changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca (2+) are controlled not only by the frequency of Ca (2+) oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca (2+) stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca (2+) oscillations. The main characteristics of the Ca (2+) exchange fluxes with these compartments are also reviewed. PMID:27630768

  6. Fine tuning of cytosolic Ca 2+ oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed. PMID:27630768

  7. Determinants in CaV1 Channels That Regulate the Ca2+ Sensitivity of Bound Calmodulin*

    PubMed Central

    Halling, D. Brent; Georgiou, Dimitra K.; Black, D. J.; Yang, Guojun; Fallon, Jennifer L.; Quiocho, Florante A.; Pedersen, Steen E.; Hamilton, Susan L.

    2009-01-01

    Calmodulin binds to IQ motifs in the α1 subunit of CaV1.1 and CaV1.2, but the affinities of calmodulin for the motif and for Ca2+ are higher when bound to CaV1.2 IQ. The CaV1.1 IQ and CaV1.2 IQ sequences differ by four amino acids. We determined the structure of calmodulin bound to CaV1.1 IQ and compared it with that of calmodulin bound to CaV1.2 IQ. Four methionines in Ca2+-calmodulin form a hydrophobic binding pocket for the peptide, but only one of the four nonconserved amino acids (His-1532 of CaV1.1 and Tyr-1675 of CaV1.2) contacts this calmodulin pocket. However, Tyr-1675 in CaV1.2 contributes only modestly to the higher affinity of this peptide for calmodulin; the other three amino acids in CaV1.2 contribute significantly to the difference in the Ca2+ affinity of the bound calmodulin despite having no direct contact with calmodulin. Those residues appear to allow an interaction with calmodulin with one lobe Ca2+-bound and one lobe Ca2+-free. Our data also provide evidence for lobe-lobe interactions in calmodulin bound to CaV1.2. PMID:19473981

  8. Autonomous CaMKII requires further stimulation by Ca2+/calmodulin for enhancing synaptic strength

    PubMed Central

    Barcomb, Kelsey; Buard, Isabelle; Coultrap, Steven J.; Kulbe, Jacqueline R.; O'Leary, Heather; Benke, Timothy A.; Bayer, K. Ulrich

    2014-01-01

    A hallmark feature of Ca2+/calmodulin (CaM)-dependent protein kinase II (CaMKII) is generation of autonomous (Ca2+-independent) activity by T286 autophosphorylation. Biochemical studies have shown that “autonomous” CaMKII is ∼5-fold further stimulated by Ca2+/CaM, but demonstration of a physiological function for such regulation within cells has remained elusive. In this study, CaMKII-induced enhancement of synaptic strength in rat hippocampal neurons required both autonomous activity and further stimulation. Synaptic strength was decreased by CaMKIIα knockdown and rescued by reexpression, but not by mutants impaired for autonomy (T286A) or binding to NMDA-type glutamate receptor subunit 2B (GluN2B; formerly NR2B; I205K). Full rescue was seen with constitutively autonomous mutants (T286D), but only if they could be further stimulated (additional T305/306A mutation), and not with two other mutations that additionally impair Ca2+/CaM binding. Compared to rescue with wild-type CaMKII, the CaM-binding-impaired mutants even had reduced synaptic strength. One of these mutants (T305/306D) mimicked an inhibitory autophosphorylation of CaMKII, whereas the other one (Δstim) abolished CaM binding without introducing charged residues. Inhibitory T305/306 autophosphorylation also reduced GluN2B binding, but this effect was independent of reduced Ca2+/CaM binding and was not mimicked by T305/306D mutation. Thus, even autonomous CaMKII activity must be further stimulated by Ca2+/CaM for enhancement of synaptic strength.—Barcomb, K., Buard, I., Coultrap, S. J., Kulbe, J. R., O'Leary, H., Benke, T. A., Bayer, K. U. Autonomous CaMKII requires further stimulation by Ca2+/calmodulin for enhancing synaptic strength. PMID:24843070

  9. A World of Magic: Conference Papers from the Selected Sessions of the AACRAO Annual Meeting (79th, Orlando, FL, April 18-23, 1993).

    ERIC Educational Resources Information Center

    Russell, Michele, Ed.

    Papers on aspects of college admission, records, and institutional research functions are: "How To Improve Office Morale" (Victor Swenson); "Staff Meetings: How To Save Hours per Month and Develop Your Staff" (LuAnn Harris, Shelley Olsen); "Selling SPEED/ExPRESS" (Laura Patterson, Thomas Scott); "Advisement and Registration: A Terminal Solution"…

  10. Controls on Sr/Ca in Scleractinian Corals: The Effects of Ca-ATPase and Ca channels on Skeletal Chemistry

    NASA Astrophysics Data System (ADS)

    Allison, N.; Cohen, I.; Finch, A. A.; Erez, J.

    2010-12-01

    Coral skeletal Sr/Ca is a commonly used palaeothermometer and has been used to estimate past sea surface temperatures. However the processes controlling Sr incorporation in coral aragonite are poorly understood. The Sr/Ca chemistry of the massive Porites spp. corals typically used for palaeoenvironmental reconstruction is dominated by short-term (weekly-monthly) oscillations of ~10% which do not reflect seawater temperature. This heterogeneity may reflect variations in the composition of the fluid used for calcification. Coral skeletons precipitate from an extracellular calcifying fluid enclosed in a semi-isolated space between the skeleton and the calicoblastic epithelium (the tissue layer at the base of the coral organism). Seawater diffuses directly to the calcification site and the calcification fluid has a composition derived from that of seawater but modified by other transport processes. In zooxanthellate corals, Ca2+ is transported transcellularly to the calcification site by both calcium channels and by the carrier protein Ca-ATPase. Sr2+ has a similar ionic radius to Ca2+, but it is not clear if Sr2+ can substitute for Ca2+ in these transport mechanisms. Variations in the relative contributions of each of the transport mechanisms to the calcification fluid and the efficiencies with which each process transports Sr2+ and Ca2+ could explain the Sr/Ca heterogeneity observed in coral skeletons. To test the impact of transcellular Ca transport processes on skeletal Sr/Ca and Mg/Ca we cultured Pocillopora damicornis corals in the presence of inhibitors of Ca-ATPase (ruthenium red) and Ca channels (verapamil). The photosynthesis, respiration and calcification rates of the colonies were monitored throughout the experiment. The skeleton subsequently deposited was identified (by 42Ca spike) and analysed by secondary ion mass spectrometry. The Sr/Ca and Mg/Ca of the aragonite deposited in the presence of either of the inhibitors was not significantly different from

  11. Mission CaMKIIγ: shuttle calmodulin from membrane to nucleus.

    PubMed

    Malik, Zulfiqar A; Stein, Ivar S; Navedo, Manuel F; Hell, Johannes W

    2014-10-01

    Neuronal plasticity depends on plasma membrane Ca(2+) influx, resulting in activity-dependent gene transcription. Calmodulin (CaM) activated by Ca(2+) initiates the nuclear events, but how CaM makes its way to the nucleus has remained elusive. Ma et al. now show that CaMKIIγ transports CaM from cell surface Ca(2+) channels to the nucleus.

  12. Ca2+ Cycling in Heart Failure

    PubMed Central

    Luo, Min; Anderson, Mark E.

    2013-01-01

    Ca2+ plays a crucial role in connecting membrane excitability with contraction in myocardium. The hallmark features of heart failure are mechanical dysfunction and arrhythmias; defective intracellular Ca2+ homeostasis is a central cause of contractile dysfunction and arrhythmias in failing myocardium. Defective Ca2+ homeostasis in heart failure can result from pathological alteration in the expression and activity of an increasingly understood collection of Ca2+ homeostatic binding proteins, ion channels and enzymes. This review focuses on the molecular mechanisms of defective Ca2+ cycling in heart failure and consider how fundamental understanding of these pathways may translate into novel and innovative therapies. PMID:23989713

  13. Distinct Roles for Dorsal CA3 and CA1 in Memory for Sequential Nonspatial Events

    ERIC Educational Resources Information Center

    Farovik, Anja; Dupont, Laura M.; Eichenbaum, Howard

    2010-01-01

    Previous studies have suggested that dorsal hippocampal areas CA3 and CA1 are both involved in representing sequences of events that compose unique episodes. However, it is uncertain whether the contribution of CA3 is restricted to spatial information, and it is unclear whether CA1 encodes order per se or contributes by an active maintenance of…

  14. Expression and Localization of CaBP Ca2+ Binding Proteins in the Mouse Cochlea.

    PubMed

    Yang, Tian; Scholl, Elizabeth S; Pan, Ning; Fritzsch, Bernd; Haeseleer, Françoise; Lee, Amy

    2016-01-01

    CaBPs are a family of EF-hand Ca2+ binding proteins that are structurally similar to calmodulin. CaBPs can interact with, and yet differentially modulate, effectors that are regulated by calmodulin, such as Cav1 voltage-gated Ca2+ channels. Immunolabeling studies suggest that multiple CaBP family members (CaBP1, 2, 4, and 5) are expressed in the cochlea. To gain insights into the respective auditory functions of these CaBPs, we characterized the expression and cellular localization of CaBPs in the mouse cochlea. By quantitative reverse transcription PCR, we show that CaBP1 and CaBP2 are the major CaBPs expressed in mouse cochlea both before and after hearing onset. Of the three alternatively spliced variants of CaBP1 (caldendrin, CaBP1-L, and CaBP1-S) and CaBP2 (CaBP2-alt, CaBP2-L, CaBP2-S), caldendrin and CaBP2-alt are the most abundant. By in situ hybridization, probes recognizing caldendrin strongly label the spiral ganglion, while probes designed to recognize all three isoforms of CaBP1 weakly label both the inner and outer hair cells as well as the spiral ganglion. Within the spiral ganglion, caldendrin/CaBP1 labeling is associated with cells resembling satellite glial cells. CaBP2-alt is strongly expressed in inner hair cells both before and after hearing onset. Probes designed to recognize all three variants of CaBP2 strongly label inner hair cells before hearing onset and outer hair cells after the onset of hearing. Thus, CaBP1 and CaBP2 may have overlapping roles in regulating Ca2+ signaling in the hair cells, and CaBP1 may have an additional function in the spiral ganglion. Our findings provide a framework for understanding the role of CaBP family members in the auditory periphery. PMID:26809054

  15. Non–Ca2+-conducting Ca2+ channels in fish skeletal muscle excitation-contraction coupling

    PubMed Central

    Schredelseker, Johann; Shrivastav, Manisha; Dayal, Anamika; Grabner, Manfred

    2010-01-01

    During skeletal muscle excitation-contraction (EC) coupling, membrane depolarizations activate the sarcolemmal voltage-gated L-type Ca2+ channel (CaV1.1). CaV1.1 in turn triggers opening of the sarcoplasmic Ca2+ release channel (RyR1) via interchannel protein–protein interaction to release Ca2+ for myofibril contraction. Simultaneously to this EC coupling process, a small and slowly activating Ca2+ inward current through CaV1.1 is found in mammalian skeletal myotubes. The role of this Ca2+ influx, which is not immediately required for EC coupling, is still enigmatic. Interestingly, whole-cell patch clamp experiments on freshly dissociated skeletal muscle myotubes from zebrafish larvae revealed the lack of such Ca2+ currents. We identified two distinct isoforms of the pore-forming CaV1.1α1S subunit in zebrafish that are differentially expressed in superficial slow and deep fast musculature. Both do not conduct Ca2+ but merely act as voltage sensors to trigger opening of two likewise tissue-specific isoforms of RyR1. We further show that non-Ca2+ conductivity of both CaV1.1α1S isoforms is a common trait of all higher teleosts. This non-Ca2+ conductivity of CaV1.1 positions teleosts at the most-derived position of an evolutionary trajectory. Though EC coupling in early chordate muscles is activated by the influx of extracellular Ca2+, it evolved toward CaV1.1-RyR1 protein–protein interaction with a relatively small and slow influx of external Ca2+ in tetrapods. Finally, the CaV1.1 Ca2+ influx was completely eliminated in higher teleost fishes. PMID:20212109

  16. Adenosine stimulates Ca2+ fluxes and increases cytosolic free Ca2+ in cultured rat mesangial cells.

    PubMed Central

    Olivera, A; López-Rivas, A; López-Novoa, J M

    1992-01-01

    Adenosine has been associated with cellular Ca2+ metabolism in some cell types. Since adenosine is able to contract glomerular mesangial cells in culture, and since Ca2+ is the main messenger mediating contractile responses, we studied the effect of adenosine on 45Ca2+ movements into and out of mesangial cells and on the cytosolic free Ca2+ concentration ([Ca2+]i). Adenosine at 0.1 mM increased 45Ca2+ uptake (basal, 9993 +/- 216; + adenosine, 14823 +/- 410 d.p.m./mg; P less than 0.01) through verapamil-sensitive Ca2+ channels. These channels seem to be of the A1-adenosine receptor subtype. Adenosine also stimulated 45Ca2+ efflux from 45Ca(2+)-loaded mesangial cells. This effect was accompanied by a net depletion of intracellular 45Ca2+ content under isotopic equilibrium conditions (basal, 24213 +/- 978; + adenosine, 18622 +/- 885 d.p.m./mg; P less than 0.05). The increase in 45Ca2+ efflux was inhibited by a Ca(2+)-free medium or in the presence of 10 microM-verapamil. However, the intracellular Ca(2+)-release blocker TMB-8 (10 microM) only partially inhibited the adenosine-stimulated 45Ca2+ efflux. In addition, adenosine induced an elevation in [Ca2+]i in mesangial cells with an initial transient peak within 15 s (basal, 113 +/- 7; adenosine, 345 +/- 46 nM), and a secondary increase which was slower (3-4 min) and of lower magnitude than the initial peak (250 +/- 21 nM). In summary, adenosine elevates [Ca2+]i and stimulates both Ca2+ uptake from the extracellular pool and Ca2+ efflux from intracellular pools in mesangial cells. The Ca2+ release from internal stores is produced by a combination of a TMB-8-inhibitable and a non-TMB-8-inhibitable mechanism, and seems to be dependent on Ca2+ influx. PMID:1554371

  17. Ca isotope cycling in a forested ecosystem

    NASA Astrophysics Data System (ADS)

    Holmden, Chris; Bélanger, Nicolas

    2010-02-01

    Reports of large Ca isotope fractionations between trees and soils prompted this study of a Boreal forest ecosystem near La Ronge, Saskatchewan, to improve understanding of this phenomenon. The results on five tree species (black spruce, trembling aspen, white spruce, jack pine, balsam poplar) confirm that nutrient Ca uptake by plants favors the light isotopes, thus driving residual Ca in plant available soil pools towards enrichment in the heavy isotopes. Substantial within-tree fraction occurs in tissues formed along the transpiration stream, with low δ 44Ca values in fine roots (2 mm), intermediate values in stemwood, and high values in foliage. Separation factors between different plant tissues are similar between species, but the initial fractionation step in the tips of the fine roots is species specific, and/or sensitive to the local soil environment. Soil water δ 44Ca values appear to increase with depth to at least 35 cm below the top of the forest floor, which is close to the deepest level of fine roots. The heavy plant fractionated signature of Ca in the finely rooted upper soils filters downward where it is retained on ion exchange sites, leached into groundwater, and discharged into surface waters. The relationship between Ca uptake by tree fine roots and the pattern of δ 44Ca enrichment with soil depth was modeled for two Ca pools: the forest floor (litter) and the underlying (upper B) mineral soil. Six study plots were investigated along two hillside toposequences trending upwards from a first order stream. We used allometric equations describing the Ca distribution in boreal tree species to calculate weighted average δ 44Ca values for the stands in each plot and estimate Ca uptake rates. The δ 44Ca value of precipitation was measured, and soil weathering signatures deduced, by acid leaching of lower B mineral soils. Steady state equations were used to derive a set of model Ca fluxes and fractionation factors for each plot. The model reproduces

  18. Drugs preventing Na+ and Ca2+ overload.

    PubMed

    Ravens, U; Himmel, H M

    1999-03-01

    Cardiac intracellular Na+and Ca2+homeostasis is regulated by the concerted action of ion channels, pumps and exchangers. The Na+, K+-ATPase produces the electrochemical concentration gradient for Na+, which is the driving force for Ca2+removal from the cytosol via the Na+/Ca2+exchange. Reduction of this gradient by increased intracellular Na+concentration leads to cellular Ca2+overload resulting in arrhythmias and contractile dysfunction. Na+and Ca2+overload-associated arrhythmias can be produced experimentally by inhibition of Na+efflux (digitalis-induced intoxication) and by abnormal Na+influx via modulated Na+channels (veratridine, DPI 201-106; hypoxia) or via the Na+, H+exchanger. Theoretically, blockers of Na+and Ca2+channels, inhibitors of abnormal oscillatory release of Ca2+from internal stores or modulators of the Na+, Ca2+and Na+, H+exchanger activities could protect against cellular Na+and Ca2+overload. Three exemplary drugs that prevent Na+and Ca2+overload, i.e. the benzothiazolamine R56865, the methylenephenoxydioxy-derivative CP-060S, and the benzoyl-guanidine Hoe 642, a Na+, H+exchange blocker, are briefly reviewed with respect to their efficacy on digitalis-, veratridine- and ischaemia/reperfusion-induced arrhythmias. PMID:10094840

  19. Neuronal Ca2+ disregulation in diabetes mellitus.

    PubMed

    Biessels, Geert Jan; ter Laak, Mariël P; Hamers, Frank P T; Gispen, Willem Hendrik

    2002-07-01

    The Ca(2+) hypothesis of brain ageing and dementia may account for part of the available data on the pathogenesis of dementia and certain neurodegenerative disorders. The hypothesis proposes that disturbances in the homeostasis of neuronal cytosolic free Ca(2+) are part of a final common pathway, ultimately leading to neuronal dysfunction and cell death. The hypothesis also proposes that a small change in cytosolic free Ca(2+) sustained over a long period of time will result in similar damage as a large change over a short period. Diabetes mellitus is associated with neurological complications in the peripheral and central nervous system, as reflected in peripheral neuropathy, modest cognitive impairments and an increased risk of dementia. In animal models of diabetes, learning impairments are associated with alterations in Ca(2+) -dependent forms of hippocampal synaptic plasticity. Disturbances in the homeostasis of cytosolic free Ca(2+) may present a final common pathway in the multifactorial pathogenesis of neurological complications of diabetes, which involves vascular changes, oxidative stress, and non-enzymatic protein glycation. In line with the Ca(2+) hypothesis of neurodegenerative disorders, a prolonged, small increase in basal cytosolic Ca(2+) levels indeed exists in sensory neurones of diabetic animals. In addition, Ca(2+) dynamics are affected. Ca(2+) channel blockers, such as nimodipine, have been shown to improve experimental peripheral neuropathy, through a vascular mechanism, possibly in combination with direct neuronal effects. Preliminary studies indicate that nimodipine may also improve Ca(2+)-dependent forms of synaptic plasticity in the hippocampus of diabetic rats.

  20. The influence of Ca²⁺ buffers on free [Ca²⁺] fluctuations and the effective volume of Ca²⁺ microdomains.

    PubMed

    Weinberg, Seth H; Smith, Gregory D

    2014-06-17

    Intracellular calcium (Ca(2+)) plays a significant role in many cell signaling pathways, some of which are localized to spatially restricted microdomains. Ca(2+) binding proteins (Ca(2+) buffers) play an important role in regulating Ca(2+) concentration ([Ca(2+)]). Buffers typically slow [Ca(2+)] temporal dynamics and increase the effective volume of Ca(2+) domains. Because fluctuations in [Ca(2+)] decrease in proportion to the square-root of a domain's physical volume, one might conjecture that buffers decrease [Ca(2+)] fluctuations and, consequently, mitigate the significance of small domain volume concerning Ca(2+) signaling. We test this hypothesis through mathematical and computational analysis of idealized buffer-containing domains and their stochastic dynamics during free Ca(2+) influx with passive exchange of both Ca(2+) and buffer with bulk concentrations. We derive Langevin equations for the fluctuating dynamics of Ca(2+) and buffer and use these stochastic differential equations to determine the magnitude of [Ca(2+)] fluctuations for different buffer parameters (e.g., dissociation constant and concentration). In marked contrast to expectations based on a naive application of the principle of effective volume as employed in deterministic models of Ca(2+) signaling, we find that mobile and rapid buffers typically increase the magnitude of domain [Ca(2+)] fluctuations during periods of Ca(2+) influx, whereas stationary (immobile) Ca(2+) buffers do not. Also contrary to expectations, we find that in the absence of Ca(2+) influx, buffers influence the temporal characteristics, but not the magnitude, of [Ca(2+)] fluctuations. We derive an analytical formula describing the influence of rapid Ca(2+) buffers on [Ca(2+)] fluctuations and, importantly, identify the stochastic analog of (deterministic) effective domain volume. Our results demonstrate that Ca(2+) buffers alter the dynamics of [Ca(2+)] fluctuations in a nonintuitive manner. The finding that Ca(2

  1. Topographic specificity of functional connections from hippocampal CA3 to CA1

    NASA Astrophysics Data System (ADS)

    Brivanlou, Iman H.; Dantzker, Jami L. M.; Stevens, Charles F.; Callaway, Edward M.

    2004-02-01

    The hippocampus is a cortical region thought to play an important role in learning and memory. Most of our knowledge about the detailed organization of hippocampal circuitry responsible for these functions is derived from anatomical studies. These studies present an incomplete picture, however, because the functional character and importance of connections are often not revealed by anatomy. Here, we used a physiological method (photostimulation with caged glutamate) to probe the fine pattern of functional connectivity between the CA3 and CA1 subfields in the mouse hippocampal slice preparation. We recorded intracellularly from CA1 and CA3 pyramidal neurons while scanning with photostimulation across the entire CA3 subfield with high spatial resolution. Our results show that, at a given septotemporal level, nearby CA1 neurons receive synaptic inputs from neighboring CA3 neurons. Thus, the CA3 to CA1 mapping preserves neighbor relations.

  2. Dietary calcium deficiency increases Ca2+ uptake and Ca2+ extrusion mechanisms in chick enterocytes.

    PubMed

    Centeno, Viviana A; Díaz de Barboza, Gabriela E; Marchionatti, Ana M; Alisio, Arturo E; Dallorso, Maria E; Nasif, Renée; Tolosa de Talamoni, Nori G

    2004-10-01

    Ca2+ uptake and Ca2+ extrusion mechanisms were studied in enterocytes with different degree of differentiation from chicks adapted to a low Ca2+ diet as compared to animals fed a normal diet. Chicks adapted to a low Ca2+ diet presented hypocalcemia, hypophosphatemia and increased serum 1,25(OH)2D3 and Ca2+ absorption. Low Ca2+ diet increased the alkaline phosphatase (AP) activity, independently of the cellular maturation, but it did not alter gamma-glutamyl-transpeptidase activity. Ca2+ uptake, Ca2+-ATPase and Na(+)/Ca2+ exchanger activities and expressions were increased by the mineral-deficient diet either in mature or immature enterocytes. Western blots analysis shows that vitamin D receptor (VDR) expression was much higher in crypt cells than in mature cells. Low Ca2+ diet decreased the number of vitamin D receptor units in both kinds of cells. In conclusion, changes in Ca2+ uptake and Ca2+ extrusion mechanisms in the enterocytes by a low Ca2+ diet appear to be a result of enhanced serum levels of 1,25(OH)2D3, which would promote cellular differentiation producing cells more efficient to express vitamin D dependent genes required for Ca2+ absorption. PMID:15528161

  3. TMCO1 Is an ER Ca(2+) Load-Activated Ca(2+) Channel.

    PubMed

    Wang, Qiao-Chu; Zheng, Qiaoxia; Tan, Haiyan; Zhang, Bing; Li, Xiaoling; Yang, Yuxiu; Yu, Jie; Liu, Yang; Chai, Hao; Wang, Xi; Sun, Zhongshuai; Wang, Jiu-Qiang; Zhu, Shu; Wang, Fengli; Yang, Maojun; Guo, Caixia; Wang, Heng; Zheng, Qingyin; Li, Yang; Chen, Quan; Zhou, Aimin; Tang, Tie-Shan

    2016-06-01

    Maintaining homeostasis of Ca(2+) stores in the endoplasmic reticulum (ER) is crucial for proper Ca(2+) signaling and key cellular functions. The Ca(2+)-release-activated Ca(2+) (CRAC) channel is responsible for Ca(2+) influx and refilling after store depletion, but how cells cope with excess Ca(2+) when ER stores are overloaded is unclear. We show that TMCO1 is an ER transmembrane protein that actively prevents Ca(2+) stores from overfilling, acting as what we term a "Ca(2+) load-activated Ca(2+) channel" or "CLAC" channel. TMCO1 undergoes reversible homotetramerization in response to ER Ca(2+) overloading and disassembly upon Ca(2+) depletion and forms a Ca(2+)-selective ion channel on giant liposomes. TMCO1 knockout mice reproduce the main clinical features of human cerebrofaciothoracic (CFT) dysplasia spectrum, a developmental disorder linked to TMCO1 dysfunction, and exhibit severe mishandling of ER Ca(2+) in cells. Our findings indicate that TMCO1 provides a protective mechanism to prevent overfilling of ER stores with Ca(2+) ions. PMID:27212239

  4. Ca2+ cycling in heart cells from ground squirrels: adaptive strategies for intracellular Ca2+ homeostasis.

    PubMed

    Li, Xiao-Chen; Wei, Ling; Zhang, Guang-Qin; Bai, Zai-Ling; Hu, Ying-Ying; Zhou, Peng; Bai, Shu-Hua; Chai, Zhen; Lakatta, Edward G; Hao, Xue-Mei; Wang, Shi-Qiang

    2011-01-01

    Heart tissues from hibernating mammals, such as ground squirrels, are able to endure hypothermia, hypoxia and other extreme insulting factors that are fatal for human and nonhibernating mammals. This study was designed to understand adaptive mechanisms involved in intracellular Ca(2+) homeostasis in cardiomyocytes from the mammalian hibernator, ground squirrel, compared to rat. Electrophysiological and confocal imaging experiments showed that the voltage-dependence of L-type Ca(2+) current (I(Ca)) was shifted to higher potentials in ventricular myocytes from ground squirrels vs. rats. The elevated threshold of I(Ca) did not compromise the Ca(2+)-induced Ca(2+) release, because a higher depolarization rate and a longer duration of action potential compensated the voltage shift of I(Ca). Both the caffeine-sensitive and caffeine-resistant components of cytosolic Ca(2+) removal were more rapid in ground squirrels. Ca(2+) sparks in ground squirrels exhibited larger amplitude/size and much lower frequency than in rats. Due to the high I(Ca) threshold, low SR Ca(2+) leak and rapid cytosolic Ca(2+) clearance, heart cells from ground squirrels exhibited better capability in maintaining intracellular Ca(2+) homeostasis than those from rats and other nonhibernating mammals. These findings not only reveal adaptive mechanisms of hibernation, but also provide novel strategies against Ca(2+) overload-related heart diseases. PMID:21935466

  5. Anodic reactions in the Ca/CaCrO/sub 4/ thermal battery

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.

    1985-09-01

    The reaction of Ca with a CaCrO/sub 4/-(LiCl-KCl eutectic) solution at temperatures of 400/sup 0/C to 500/sup 0/C was studied to better understand the nature of the chemical reactions and electrochemical processes that occur in the Ca/CaCrO/sub 4/ thermal battery at the anode during activation and discharge. Limited tests also were conducted with a CaCrO/sub 4/-(CaCl/sub 2/-NaCl-KCl eutectic) solution at 550/sup 0/C. Ca/CaCrO/sub 4/ and CaLi/sub 2//CaCrO/sub 4/ single cells were tested to observe the relative performance differences of Ca and CaLi/sub 2/ anodes. The discharged cells were analyzed by optical microscopy, electron microprobe, Auger electron spectroscopy, and secondary-ion mass spectroscopy. These analytical data were used in conjunction with the results of chemical-reaction experiments to propose a discharge mechanism for the Ca/CaCrO/sub 4/ thermal battery, consistent with experimental observations.

  6. Anodic reactions in the Ca/CaCrO4 thermal battery

    NASA Astrophysics Data System (ADS)

    Guidotti, R. A.; Reinhardt, F. W.

    1985-09-01

    The reaction of Ca with a CaCrO4-(LiCl-KCl eutectic) solution at temperatures of 400(0)C to 500(0)C was studied to better understand the nature of the chemical reactions and electrochemical processes that occur in the Ca/CaCrO4 thermal battery at the anode during activation and discharge. Limited tests also were conducted with a CaCrO4-(CaCl2-NaCl-KCl eutectic) solution at 550(0)C. Ca/CaCrO4 and CaLi2/CaCrO4 single cells were tested to observe the relative performance differences of Ca and CaLi2 anodes. The discharged cells were analyzed by optical microscopy, electron microprobe, Auger electron spectroscopy, and secondary-ion mass spectroscopy. These analytical data were used in conjunction with the results of chemical-reaction experiments to propose a discharge mechanism for the Ca/CaCrO4 thermal battery, consistent with experimental observations.

  7. Serum CA549 in primary breast cancer: comparison with CA15.3 and MCA.

    PubMed

    Gion, M; Plebani, M; Mione, R; Penzo, C; Meo, S; Burlina, A

    1994-04-01

    We carried out a comparison of three commonly used mucin markers, CA549, CA15.3 and MCA. Serum samples from 184 healthy women and 237 patients with primary breast cancer were evaluated. The markers were measured using commercially available immunometric assays. Like CA15.3 and MCA, CA549 was significantly associated with tumour size and lymph node status, being an effective indicator of tumour bulk. CA549 was significantly correlated with both CA15.3 and MCA. Positive/negative concordance rate was very good (93.7%) between CA549 and MCA. Conversely, CA15.3 was positive and CA549 negative in 20.4% of cases. Axillary status was not significantly different in the latter group of patients and in cases in which CA15.3 and CA549 showed concordant results. From the present findings we draw the following major conclusions: 1. CA549 and MCA are highly correlated and their association should not provide additional information; however, they should not be considered interchangeable since they may behave differently in individual cases. 2. CA549 and CA15.3, although well correlated, are discordant in a significant number of cases. Longitudinal studies are needed to verify the usefulness of the association between the two markers. 3. The three evaluated mucin markers are not interchangeable in individual patients; if a patient is monitored with a marker, she should be followed up with the same marker.

  8. Dissection of local Ca(2+) signals inside cytosol by ER-targeted Ca(2+) indicator.

    PubMed

    Niwa, Fumihiro; Sakuragi, Shigeo; Kobayashi, Ayana; Takagi, Shin; Oda, Yoichi; Bannai, Hiroko; Mikoshiba, Katsuhiko

    2016-10-01

    Calcium (Ca(2+)) is a versatile intracellular second messenger that operates in various signaling pathways leading to multiple biological outputs. The diversity of spatiotemporal patterns of Ca(2+) signals, generated by the coordination of Ca(2+) influx from the extracellular space and Ca(2+) release from the intracellular Ca(2+) store the endoplasmic reticulum (ER), is considered to underlie the diversity of biological outputs caused by a single signaling molecule. However, such Ca(2+) signaling diversity has not been well described because of technical limitations. Here, we describe a new method to report Ca(2+) signals at subcellular resolution. We report that OER-GCaMP6f, a genetically encoded Ca(2+) indicator (GECI) targeted to the outer ER membrane, can monitor Ca(2+) release from the ER at higher spatiotemporal resolution than conventional GCaMP6f. OER-GCaMP6f was used for in vivo Ca(2+) imaging of C. elegans. We also found that the spontaneous Ca(2+) elevation in cultured astrocytes reported by OER-GCaMP6f showed a distinct spatiotemporal pattern from that monitored by plasma membrane-targeted GCaMP6f (Lck-GCaMP6f); less frequent Ca(2+) signal was detected by OER-GCaMP6f, in spite of the fact that Ca(2+) release from the ER plays important roles in astrocytes. These findings suggest that targeting of GECIs to the ER outer membrane enables sensitive detection of Ca(2+) release from the ER at subcellular resolution, avoiding the diffusion of GECI and Ca(2+). Our results indicate that Ca(2+) imaging with OER-GCaMP6f in combination with Lck-GCaMP6f can contribute to describing the diversity of Ca(2+) signals, by enabling dissection of Ca(2+) signals at subcellular resolution.

  9. Transcriptional Mechanisms Regulating Ca2+ Homeostasis

    PubMed Central

    Ritchie, Michael F.; Zhou, Yandong; Soboloff, Jonathan

    2011-01-01

    Ca2+ is a dynamic cellular secondary messenger which mediates a vast array of cellular responses. Control over these processes is achieved via an extensive combination of pumps and channels which regulate the concentration of Ca2+ within not only the cytosol but also all intracellular compartments. Precisely how these pumps and channels are regulated is only partially understood, however, recent investigations have identified members of the Early Growth Response (EGR) family of zinc finger transcription factors as critical players in this process. The roles of several other transcription factors in control of Ca2+ homeostasis have also been demonstrated, including Wilms Tumor Suppressor 1 (WT1), Nuclear Factor of Activated T cells (NFAT) and c-myc. In this review, we will discuss not only how these transcription factors regulate the expression of the major proteins involved in control of Ca2+ homeostasis, but also how this transcriptional remodeling of Ca2+ homeostasis affects Ca2+ dynamics and cellular responses. PMID:21074851

  10. Large Ca isotope effect in the CaC{sub 6} superconductor.

    SciTech Connect

    Hinks, D. G.; Rosenmann, D.; Claus, H.; Bailey, M. S.; Jorgensen, J. D.; Materials Science Division

    2007-01-01

    We have measured the Ca isotope effect coefficient, {alpha}(Ca), in the newly discovered superconductor CaC{sub 6} and find a value of 0.53(2). This result shows that the superconductivity is dominated by coupling of the electrons by Ca phonon modes. The C phonons contribute very little, assuming that this material is a conventional electron-phonon coupled superconductor. Thus, in contrast to another layered material MgB{sub 2}, where high-energy phonons in the B layers are responsible for the superconductivity, in layered CaC{sub 6} the phonons responsible for superconductivity are primarily low-energy modes of the intercalated Ca.

  11. Glutamate excitotoxicity and Ca2+-regulation of respiration: Role of the Ca2+ activated mitochondrial transporters (CaMCs).

    PubMed

    Rueda, Carlos B; Llorente-Folch, Irene; Traba, Javier; Amigo, Ignacio; Gonzalez-Sanchez, Paloma; Contreras, Laura; Juaristi, Inés; Martinez-Valero, Paula; Pardo, Beatriz; Del Arco, Araceli; Satrustegui, Jorgina

    2016-08-01

    Glutamate elicits Ca(2+) signals and workloads that regulate neuronal fate both in physiological and pathological circumstances. Oxidative phosphorylation is required in order to respond to the metabolic challenge caused by glutamate. In response to physiological glutamate signals, cytosolic Ca(2+) activates respiration by stimulation of the NADH malate-aspartate shuttle through Ca(2+)-binding to the mitochondrial aspartate/glutamate carrier (Aralar/AGC1/Slc25a12), and by stimulation of adenine nucleotide uptake through Ca(2+) binding to the mitochondrial ATP-Mg/Pi carrier (SCaMC-3/Slc25a23). In addition, after Ca(2+) entry into the matrix through the mitochondrial Ca(2+) uniporter (MCU), it activates mitochondrial dehydrogenases. In response to pathological glutamate stimulation during excitotoxicity, Ca(2+) overload, reactive oxygen species (ROS), mitochondrial dysfunction and delayed Ca(2+) deregulation (DCD) lead to neuronal death. Glutamate-induced respiratory stimulation is rapidly inactivated through a mechanism involving Poly (ADP-ribose) Polymerase-1 (PARP-1) activation, consumption of cytosolic NAD(+), a decrease in matrix ATP and restricted substrate supply. Glutamate-induced Ca(2+)-activation of SCaMC-3 imports adenine nucleotides into mitochondria, counteracting the depletion of matrix ATP and the impaired respiration, while Aralar-dependent lactate metabolism prevents substrate exhaustion. A second mechanism induced by excitotoxic glutamate is permeability transition pore (PTP) opening, which critically depends on ROS production and matrix Ca(2+) entry through the MCU. By increasing matrix content of adenine nucleotides, SCaMC-3 activity protects against glutamate-induced PTP opening and lowers matrix free Ca(2+), resulting in protracted appearance of DCD and protection against excitotoxicity in vitro and in vivo, while the lack of lactate protection during in vivo excitotoxicity explains increased vulnerability to kainite-induced toxicity in Aralar

  12. Ca2+ signaling differentiation during oocyte maturation.

    PubMed

    Machaca, Khaled

    2007-11-01

    Oocyte maturation is an essential cellular differentiation pathway that prepares the egg for activation at fertilization leading to the initiation of embryogenesis. An integral attribute of oocyte maturation is the remodeling of Ca2+ signaling pathways endowing the egg with the capacity to produce a specialized Ca2+ transient at fertilization that is necessary and sufficient for egg activation. Consequently, mechanistic elucidation of Ca2+ signaling differentiation during oocyte maturation is fundamental to our understanding of egg activation, and offers a glimpse into Ca2+ signaling regulation during the cell cycle.

  13. Genetically Encoded Green Fluorescent Ca2+ Indicators with Improved Detectability for Neuronal Ca2+ Signals

    PubMed Central

    Sadakari, Junko; Gengyo-Ando, Keiko; Kagawa-Nagamura, Yuko; Kobayashi, Chiaki; Ikegaya, Yuji; Nakai, Junichi

    2012-01-01

    Imaging the activities of individual neurons with genetically encoded Ca2+ indicators (GECIs) is a promising method for understanding neuronal network functions. Here, we report GECIs with improved neuronal Ca2+ signal detectability, termed G-CaMP6 and G-CaMP8. Compared to a series of existing G-CaMPs, G-CaMP6 showed fairly high sensitivity and rapid kinetics, both of which are suitable properties for detecting subtle and fast neuronal activities. G-CaMP8 showed a greater signal (Fmax/Fmin = 38) than G-CaMP6 and demonstrated kinetics similar to those of G-CaMP6. Both GECIs could detect individual spikes from pyramidal neurons of cultured hippocampal slices or acute cortical slices with 100% detection rates, demonstrating their superior performance to existing GECIs. Because G-CaMP6 showed a higher sensitivity and brighter baseline fluorescence than G-CaMP8 in a cellular environment, we applied G-CaMP6 for Ca2+ imaging of dendritic spines, the putative postsynaptic sites. By expressing a G-CaMP6-actin fusion protein for the spines in hippocampal CA3 pyramidal neurons and electrically stimulating the granule cells of the dentate gyrus, which innervate CA3 pyramidal neurons, we found that sub-threshold stimulation triggered small Ca2+ responses in a limited number of spines with a low response rate in active spines, whereas supra-threshold stimulation triggered large fluorescence responses in virtually all of the spines with a 100% activity rate. PMID:23240011

  14. Extrapolating microdomain Ca2+ dynamics using BK channels as a Ca2+ sensor

    PubMed Central

    Hou, Panpan; Xiao, Feng; Liu, Haowen; Yuchi, Ming; Zhang, Guohui; Wu, Ying; Wang, Wei; Zeng, Wenping; Ding, Mingyue; Cui, Jianming; Wu, Zhengxing; Wang, Lu-Yang; Ding, Jiuping

    2016-01-01

    Ca2+ ions play crucial roles in mediating physiological and pathophysiological processes, yet Ca2+ dynamics local to the Ca2+ source, either from influx via calcium permeable ion channels on plasmic membrane or release from internal Ca2+ stores, is difficult to delineate. Large-conductance calcium-activated K+ (BK-type) channels, abundantly distribute in excitable cells and often localize to the proximity of voltage-gated Ca2+ channels (VGCCs), spatially enabling the coupling of the intracellular Ca2+ signal to the channel gating to regulate membrane excitability and spike firing patterns. Here we utilized the sensitivity and dynamic range of BK to explore non-uniform Ca2+ local transients in the microdomain of VGCCs. Accordingly, we applied flash photolysis of caged Ca2+ to activate BK channels and determine their intrinsic sensitivity to Ca2+. We found that uncaging Ca2+ activated biphasic BK currents with fast and slow components (time constants being τf ≈ 0.2 ms and τs ≈ 10 ms), which can be accounted for by biphasic Ca2+ transients following light photolysis. We estimated the Ca2+-binding rate constant kb (≈1.8 × 108 M−1s−1) for mSlo1 and further developed a model in which BK channels act as a calcium sensor capable of quantitatively predicting local microdomain Ca2+ transients in the vicinity of VGCCs during action potentials. PMID:26776352

  15. Distinct roles for dorsal CA3 and CA1 in memory for sequential nonspatial events.

    PubMed

    Farovik, Anja; Dupont, Laura M; Eichenbaum, Howard

    2010-01-01

    Previous studies have suggested that dorsal hippocampal areas CA3 and CA1 are both involved in representing sequences of events that compose unique episodes. However, it is uncertain whether the contribution of CA3 is restricted to spatial information, and it is unclear whether CA1 encodes order per se or contributes by an active maintenance of memories of sequential events. Here, we developed a new behavioral task that examines memory for the order of sequential nonspatial events presented as trial-unique odor pairings. When the interval between odors within a studied pair was brief (3 sec), bilateral dorsal CA3 lesions severely disrupted memory for their order, whereas dorsal CA1 lesions did not affect performance. However, when the inter-item interval was extended to 10 sec, CA1 lesions, as well as CA3 lesions, severely disrupted performance. These findings suggest that the role of CA3 in sequence memory is not limited to spatial information, but rather appears to be a fundamental property of CA3 function. In contrast, CA1 becomes involved when memories for events must be held or sequenced over long intervals. Thus, CA3 and CA1 are both involved in memory for sequential nonspatial events that compose unique experiences, and these areas play different roles that are distinguished by the duration of time that must be bridged between key events.

  16. Conservation of Ca2+/Calmodulin Regulation across Na and Ca2+ channels

    PubMed Central

    Ben-Johny, Manu; Yang, Philemon S.; Niu, Jacqueline; Yang, Wanjun; Joshi-Mukherjee, Rosy; Yue, David T.

    2014-01-01

    SUMMARY Voltage-gated Na and Ca2+channels comprise distinct ion-channel superfamilies, yet the carboxy tails of these channels exhibit high homology hinting at a long-shared and purposeful module. For different Ca2+ channels, carboxyl-tail inter actions with calmodulin do elaborate robust and similar forms of Ca2+ regulation. However, Na channels have only shown subtler Ca2+modulation that differs among reports, challenging attempts at unified understanding. Here, by rapid Ca2+photoreleaseon to Na channels, we reset this view of Na channel regulation. For cardiac muscle channels (NaV1.5), reported effects from which most mechanistic proposals derive, we observe no Ca2+modulation. Conversely, for skeletal-muscle channels (NaV1.4), we uncover fast Ca2+ regulation eerily similar to that of Ca2+ channels. Channel opathic myotonia mutations halve NaV1.4 Ca2+ regulation, and transplanting the NaV1.4 carboxy tail onto Ca2+ channels recapitulates Ca2+ regulation. Thus we argue for the persistence and physiological relevance of an ancient Ca2+ regulatory module across Na and Ca2+ channels. PMID:24949975

  17. Biphasic decay of the Ca transient results from increased sarcoplasmic reticulum Ca leak

    PubMed Central

    Sankaranarayanan, Rajiv; Li, Yatong; Greensmith, David J.; Eisner, David A.

    2016-01-01

    Key points Ca leak from the sarcoplasmic reticulum through the ryanodine receptor (RyR) reduces the amplitude of the Ca transient and slows its rate of decay.In the presence of β‐adrenergic stimulation, RyR‐mediated Ca leak produces a biphasic decay of the Ca transient with a fast early phase and a slow late phase.Two forms of Ca leak have been studied, Ca‐sensitising (induced by caffeine) and non‐sensitising (induced by ryanodine) and both induce biphasic decay of the Ca transient.Only Ca‐sensitising leak can be reversed by traditional RyR inhibitors such as tetracaine.Ca leak can also induce Ca waves. At low levels of leak, waves occur. As leak is increased, first biphasic decay and then slowed monophasic decay is seen. The level of leak has major effects on the shape of the Ca transient. Abstract In heart failure, a reduction in Ca transient amplitude and contractile dysfunction can by caused by Ca leak through the sarcoplasmic reticulum (SR) Ca channel (ryanodine receptor, RyR) and/or decreased activity of the SR Ca ATPase (SERCA). We have characterised the effects of two forms of Ca leak (Ca‐sensitising and non‐sensitising) on calcium cycling and compared with those of SERCA inhibition. We measured [Ca2+]i with fluo‐3 in voltage‐clamped rat ventricular myocytes. Increasing SR leak with either caffeine (to sensitise the RyR to Ca activation) or ryanodine (non‐sensitising) had similar effects to SERCA inhibition: decreased systolic [Ca2+]i, increased diastolic [Ca2+]i and slowed decay. However, in the presence of isoproterenol, leak produced a biphasic decay of the Ca transient in the majority of cells while SERCA inhibition produced monophasic decay. Tetracaine reversed the effects of caffeine but not of ryanodine. When caffeine (1 mmol l−1) was added to a cell which displayed Ca waves, the wave frequency initially increased before waves disappeared and biphasic decay developed. Eventually (at higher caffeine concentrations), the

  18. HISTORIC IMAGE: VIEW OF CA. 1890SERA ROSTRUM, DEMOLISHED. PHOTOGRAPH CA. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    HISTORIC IMAGE: VIEW OF CA. 1890S-ERA ROSTRUM, DEMOLISHED. PHOTOGRAPH CA. 1930S. CEMETERY MAINTENANCE LEDGER, NCA HISTORY COLLECTION. - Alexandria National Cemetery, 1450 Wilkes Street, Alexandria, Independent City, VA

  19. Submicroscopic Ca2+ diffusion mediates inhibitory coupling between individual Ca2+ channels.

    PubMed

    Imredy, J P; Yue, D T

    1992-08-01

    Dihydropyridine-sensitive Ca2+ channels in heart demonstrate an important negative feedback property: they close, or inactivate, in response to prior Ca2+ entry. We now find that Ca2+ influx through one channel can selectively contribute to the inactivation of another adjacent channel, without a generalized elevation of bulk intracellular Ca2+ concentration. Intracellular application of the Ca2+ chelator BAPTA greatly diminishes such negative interactions within Ca2+ channel pairs. These findings demonstrate that Ca2+ currents are controlled not only by intrinsic channel properties, but also by local diffusive interactions among neighboring channels. Such inhibitory coupling among channels provides a concrete example of localized Ca2+ signaling, long proposed to exist on the basis of theoretical calculations. PMID:1323309

  20. By Regulating Mitochondrial Ca2+-Uptake UCP2 Modulates Intracellular Ca2+

    PubMed Central

    Gebing, Tina; Reda, Sara; Schwaiger, Astrid; Leitner, Johannes; Wolny, Martin; Eckardt, Lars; Hoppe, Uta C.

    2016-01-01

    Introduction The possible role of UCP2 in modulating mitochondrial Ca2+-uptake (mCa2+-uptake) via the mitochondrial calcium uniporter (MCU) is highly controversial. Methods Thus, we analyzed mCa2+-uptake in isolated cardiac mitochondria, MCU single-channel activity in cardiac mitoplasts, dual Ca2+-transients from mitochondrial ((Ca2+)m) and intracellular compartment ((Ca2+)c) in the whole-cell configuration in cardiomyocytes of wild-type (WT) and UCP2-/- mice. Results Isolated mitochondria showed a Ru360 sensitive mCa2+-uptake, which was significantly decreased in UCP2-/- (229.4±30.8 FU vs. 146.3±23.4 FU, P<0.05). Single-channel registrations confirmed a Ru360 sensitive voltage-gated Ca2+-channel in mitoplasts, i.e. mCa1, showing a reduced single-channel activity in UCP2-/- (Po,total: 0.34±0.05% vs. 0.07±0.01%, P<0.05). In UCP2-/- cardiomyocytes (Ca2+)m was decreased (0.050±0.009 FU vs. 0.021±0.005 FU, P<0.05) while (Ca2+)c was unchanged (0.032±0.002 FU vs. 0.028±0.004 FU, P>0.05) and transsarcolemmal Ca2+-influx was inhibited suggesting a possible compensatory mechanism. Additionally, we observed an inhibitory effect of ATP on mCa2+-uptake in WT mitoplasts and (Ca2+)m of cardiomyocytes leading to an increase of (Ca2+)c while no ATP dependent effect was observed in UCP2-/-. Conclusion Our results indicate regulatory effects of UCP2 on mCa2+-uptake. Furthermore, we propose, that previously described inhibitory effects on MCU by ATP may be mediated via UCP2 resulting in changes of excitation contraction coupling. PMID:26849136

  1. 46 CFR 7.130 - Point Conception, CA to Point Sur, CA.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Point Conception, CA to Point Sur, CA. 7.130 Section 7.130 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Pacific Coast § 7.130 Point Conception, CA to Point Sur, CA. (a) A line drawn from the southernmost extremity of Fossil Point at longitude...

  2. 46 CFR 7.125 - Point Vincente, CA to Point Conception, CA.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Point Vincente, CA to Point Conception, CA. 7.125 Section 7.125 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY PROCEDURES APPLICABLE TO THE PUBLIC BOUNDARY LINES Pacific Coast § 7.125 Point Vincente, CA to Point Conception, CA. (a) A line drawn from Redondo Beach East Jetty Light “2” to...

  3. Effect of Ca2+ efflux pathway distribution and exogenous Ca2+ buffers on intracellular Ca2+ dynamics in the rat ventricular myocyte: a simulation study.

    PubMed

    Pásek, Michal; Simurda, Jiří; Orchard, Clive H

    2014-01-01

    We have used a previously published computer model of the rat cardiac ventricular myocyte to investigate the effect of changing the distribution of Ca(2+) efflux pathways (SERCA, Na(+)/Ca(2+) exchange, and sarcolemmal Ca(2+) ATPase) between the dyad and bulk cytoplasm and the effect of adding exogenous Ca(2+) buffers (BAPTA or EGTA), which are used experimentally to differentially buffer Ca(2+) in the dyad and bulk cytoplasm, on cellular Ca(2+) cycling. Increasing the dyadic fraction of a particular Ca(2+) efflux pathway increases the amount of Ca(2+) removed by that pathway, with corresponding changes in Ca(2+) efflux from the bulk cytoplasm. The magnitude of these effects varies with the proportion of the total Ca(2+) removed from the cytoplasm by that pathway. Differences in the response to EGTA and BAPTA, including changes in Ca(2+)-dependent inactivation of the L-type Ca(2+) current, resulted from the buffers acting as slow and fast "shuttles," respectively, removing Ca(2+) from the dyadic space. The data suggest that complex changes in dyadic Ca(2+) and cellular Ca(2+) cycling occur as a result of changes in the location of Ca(2+) removal pathways or the presence of exogenous Ca(2+) buffers, although changing the distribution of Ca(2+) efflux pathways has relatively small effects on the systolic Ca(2+) transient.

  4. Literacy.CA. Issue #19, Winter 2006

    ERIC Educational Resources Information Center

    Murray, Fiona, Ed.

    2006-01-01

    The "literacy.ca" newsletter is a vehicle for literacy workers and supporters to share information, ideas, resources and research on emerging literacy issues. This issue of "literacy.ca" contains the following articles: (1) Riding The Wave: How will the federal election affect progress on a pan-Canadian literacy agenda?; (2) Point of View:…

  5. CA-MRSA. The new sports pathogen.

    PubMed

    Kurkowski, Christina

    2007-01-01

    Skin infections in athletes caused by community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA) have been observed within many cities throughout the United States and within many countries throughout the world (Centers for Disease Control and Prevention [CDC], 2003). As the incidence rises in the athletic population, clinicians must learn to identify risk factors for CA-MRSA, diagnosis and treat infections with judicious use of antimicrobial agents and facilitate strategies to limit transmission. Recently, a new consensus guideline for handling CA-MRSA outbreaks in sports has been released by the CDC (Gorwitz et al., 2006). This article includes a review of the evolution of MRSA; distinguishes between healthcare associated Methicillin-resistant Staphylococcus aureus (HA-MRSA) and CA-MRSA; and reviews the diagnosis, management, and prevention strategies to limit transmission of CA-MRSA.

  6. Ca-Dependent Folding of Human Calumenin.

    PubMed

    Mazzorana, Marco; Hussain, Rohanah; Sorensen, Thomas

    2016-01-01

    Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range. PMID:26991433

  7. Vasospastic angina and Ca channel blockers.

    PubMed

    Minatoguchi, Shinya

    2013-08-01

    Coronary artery spasm is one of the causes of angina pectoris,acute myocardial infarction and ventricular fibrillation-related sudden death. It has been established that Ca channel blockers are protective against vasospastic angina (VSA) and treatment with Ca channel blockers provides a better prognosis of VSA. However, it is not still clarified what kinds of Ca channel blockers shows the best prognosis of VSA. We performed a meta-analysis in which 4Ca channel blockers amlodipine, nifedipine, benidipine and diltiazem were used for the treatment of VSA patients and found that among 4 Ca channel blockers, benidipine showed a statistically significant better prognostic effect on MACE than amlodipine, nifedipine or diltiazem.

  8. Ca-Dependent Folding of Human Calumenin

    PubMed Central

    Mazzorana, Marco; Hussain, Rohanah; Sorensen, Thomas

    2016-01-01

    Human calumenin (hCALU) is a six EF-hand protein belonging to the CREC family. As other members of the family, it is localized in the secretory pathway and regulates the activity of SERCA2a and of the ryanodine receptor in the endoplasmic reticulum (ER). We have studied the effects of Ca2+ binding to the protein and found it to attain a more compact structure upon ion binding. Circular Dichroism (CD) measurements suggest a major rearrangement of the protein secondary structure, which reversibly switches from disordered at low Ca2+ concentrations to predominantly alpha-helical when Ca2+ is added. SAXS experiments confirm the transition from an unfolded to a compact structure, which matches the structural prediction of a trilobal fold. Overall our experiments suggest that calumenin is a Ca2+ sensor, which folds into a compact structure, capable of interacting with its molecular partners, when Ca2+ concentration within the ER reaches the millimolar range. PMID:26991433

  9. The CaMKK2/CaMKIV Relay Is an Essential Regulator of Hepatic Cancer

    PubMed Central

    Lin, Fumin; Marcelo, Kathrina L.; Rajapakshe, Kimal; Coarfa, Cristian; Dean, Adam; Wilganowski, Nathaniel; Robinson, Holly; Sevick, Eva; Bissig, Karl-Dimiter; Goldie, Lauren C.; Means, Anthony R.; York, Brian

    2015-01-01

    Hepatic cancer is one of the most lethal cancers worldwide. Here, we report that the expression of Ca2+/calmodulin-dependent protein kinase kinase 2 (CaMKK2) is significantly up-regulated in hepatocellular carcinoma (HCC) and negatively correlated with HCC patient survival. The CaMKK2 protein is highly expressed in all eight hepatic cancer cell lines evaluated and is markedly up-regulated relative to normal primary hepatocytes. Loss of CaMKK2 function is sufficient to inhibit liver cancer cell growth, and the growth defect resulting from loss of CaMKK2 can be rescued by ectopic expression of wild-type CaMKK2 but not by kinase-inactive mutants. Cellular ablation of CaMKK2 using RNA interference yields a gene signature that correlates with improvement in HCC patient survival, and ablation or pharmacological inhibition of CaMKK2 with STO-609 impairs tumorigenicity of liver cancer cells in vivo. Moreover, CaMKK2 expression is up-regulated in a time-dependent manner in a carcinogen-induced HCC mouse model, and STO-609 treatment regresses hepatic tumor burden in this model. Mechanistically, CaMKK2 signals through Ca2+/calmodulin-dependent protein kinase 4 (CaMKIV) to control liver cancer cell growth. Further analysis revealed that CaMKK2 serves as a scaffold to assemble CaMKIV with key components of the mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway and thereby stimulate protein synthesis through protein phosphorylation. Conclusion The CaMKK2/CaMKIV relay is an upstream regulator of the oncogenic mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway, and the importance of this CaMKK2/CaM-KIV axis in HCC growth is confirmed by the potent growth inhibitory effects of genetically or pharmacologically decreasing CaMKK2 activity; collectively, these findings suggest that CaMKK2 and CaMKIV may represent potential targets for hepatic cancer. PMID:25847065

  10. Measurement of true calcium absorption in premature infants using intravenous 46Ca and oral 44Ca.

    PubMed

    Hillman, L S; Tack, E; Covell, D G; Vieira, N E; Yergey, A L

    1988-06-01

    We have developed a method for measuring true fractional calcium absorption (alpha) in premature infants using two stable isotopes of calcium and tested it in seven studies in seven infants (birth weight 1543 +/- 65 g, gestation 32.8 +/- 7 wk). A total of 7.5 micrograms/kg 46Ca was given as a single intravenous bolus. Immediately thereafter 1.25 mg/kg of 44Ca was given in a single gavage feeding of standard infant formula (Enfamil). A metabolic isolette was used to obtain 4-h collections of urine for 24 h total. 46Ca and 44Ca were measured in urine by thermal ionization mass spectroscopy and expressed as the ratio to naturally occurring 48Ca. The differences in the 46Ca/48Ca and 44Ca/48Ca ratios from natural levels (delta % excess 46Ca and delta % excess 44Ca) were calculated. Percent absorption (alpha) equals a constant times cumulative delta % excess 44Ca/delta % excess 46Ca. The calculation of alpha is independent of urine volume or concentration. The delta % excess 46Ca, showed the expected multiexponential decline as a function of time, and delta % excess 44Ca usually peaked during a 4- to 8-h urine collection. Calculations of alpha using increasingly long sampling times showed that a plateau had been reached by 12 h. alpha values calculated after 16-24 h in the seven infants at 2 wk of age were 41, 48, 45, 46, 25, 55, and 51%. Repeat studies at 3 wk of age were 46, 60, and 54%. These values are somewhat higher than net percent calcium absorption values reported for standard formula and thus appear very appropriate.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. A new method for 44Ca/40Ca determination using cool plasma MC-ICP-MS

    NASA Astrophysics Data System (ADS)

    Fietzke, J.; Eisenhauer, A.; Liebetrau, V.; Bock, B.; Gussone, N.; Nägler, T. F.; Dietzel, M.; Spero, H.; Bijma, J.; Dullo, C.

    2003-04-01

    Here we present a new technique for the direct measurement of 44Ca/40Ca isotope ratios on a MC-ICP-MS (Axiom) using the "cool plasma" technique. By reducing the plasma energy from about 1250 Watts to 400 Watts the isobaric effect resulting from 40Ar^+ can be significantly reduced enabling the simultaneous and precise measurement of 44Ca and 40Ca beam intensities in different Faraday cups. In contrast to the TIMS technique requiring a Ca double spike the isotope measurements on a MC-ICP-MS can be performed by bracketing standards. This reduces the effort for chemical preparations without loss of precision. Isobaric effects of MgO^+ and NaOH^+ interfering with 40Ca and MgOH_2 with 44Ca can be neglected by measuring Ca isotopes near the low mass edge of the peaks. No influences of Sr2+ were found monitoring on 43.5amu. Repeated measurements of two Johnson Matthey CaCO_3 standards (lot No. 4064 and lot No. 9912) revealed values of about -11.29 ppm and 0.57 ppm. These values are in accordance with previous values published by Russel et al. (1978) and Heuser et al. (2002). Repeated measurement of the NIST 915a CaCO_3 standard showed that the variance of a single δ44Ca measurement is about 0.28 ppm (2SD) being comparable with TIMS. MC-ICP-MS based δ44Ca values measured on inorganic precipitates are indistinguishable from earlier measurements of Gussone et al. (in press) based on TIMS δ44Ca measurements confirming that there is a positive δ44Ca-temperature gradient. Our study demonstrates the possibility to measure the whole dispersion of Ca isotopes with a MC-ICP-MS showing that 40Ca can be used for normalization of 44Ca. References Russel W. A. et al. (1978) Ca isotope fractionation on the Earth and other solar system materials. Geochim. Cosmochim. Acta 42, 1075--1090. Heuser A. et al. (2002) Measurement of Calcium Isotopes (δ44Ca) Using a Multicollector TIMS Technique. Int. J. Mass Spec. 220, 387--399. Gussone N. et al. (in press) Model for Kinetic Effects on

  12. Ca/sup 2 +/-CaM-ATPase activity after corticosterone binding to synaptosomal plasma membrane

    SciTech Connect

    Iqbal, Z.; Sze, P.Y.

    1986-03-01

    Studies conducted in the laboratory have demonstrated that corticosterone (CS) binds specifically to synaptosomal plasma membrane (SPM) and modify the cellular events in the synaptosomes. On an exposure of a rat brain synaptosomes to physiological concentrations (<1..mu..M) of CS, the uptake of /sup 45/Ca/sup 2 +/ into synaptosomes was increased by 40-50%. Similarly the binding of /sup 45/Ca/sup 2 +/ to isolated SPM was also enhanced by 50% in the presence of CS. However when intact synaptosomes were pre-incubated with CS, the capacity of membranes to bind /sup 45/Ca/sup 2 +/ was increased by 2-fold. After the incubation of intact synaptosomes with < ..mu..M CS, the activity of trifluoperazine sensitive and CaM dependent Ca/sup 2 +/-ATPase at 1..mu..M Ca/sup 2 +/ was found to be stimulated by 20-30% whereas the activity of Ca/sup 2 +/-ATPase at 1mM Ca/sup 2 +/ remained unaffected. Exposure of synaptosomes to CS was also effective in protecting the reduction of ouabain-sensitive ATPase (Na/sup +/-K/sup +/-ATPase) activity caused by 0.5% ethanol used as a solvent medium for CS. These findings suggest that one of the physiological actions of CS in synaptosomes, after binding to synaptosomal plasma membranes, is an enhancement of Ca/sup 2 +/ transport and an increase of Ca/sup 2 +/-CaM-ATPase activity.

  13. Store-Operated Ca2+ Entry Sustains the Fertilization Ca2+ Signal in Pig Eggs.

    PubMed

    Wang, Chunmin; Zhang, Lu; Jaeger, Laurie A; Machaty, Zoltan

    2015-07-01

    The role of store-operated Ca(2+) entry (SOCE) in the maintenance of sperm-induced Ca(2+) oscillations was investigated in porcine eggs. We found that 10 μM gadolinium (Gd(3+)), which is known to inhibit SOCE, blocked Ca(2+) entry that was triggered by thapsigargin-induced store depletion and also caused an abrupt cessation of the fertilization Ca(2+) signal. In a similar manner 3,5-bis(trifluoromethyl)pyrazole 2 (20 μM), and tetrapandin-2 (10 μM), potent SOCE inhibitors, also blocked thapsigargin-stimulated Ca(2+) entry and disrupted the Ca(2+) oscillations after sperm-egg fusion. The downregulation of Stim1 or Orai1 in the eggs did not alter the Ca(2+) content of the intracellular stores, whereas co-overexpression of these proteins led to the generation of irregular Ca(2+) transients after fertilization that stopped prematurely. We also found that thapsigargin completely emptied the endoplasmic reticulum, and that the series of Ca(2+) transients stopped abruptly after the addition of thapsigargin to the fertilized eggs, indicating that the proper reloading of the intracellular stores is a prerequisite for the maintenance of the Ca(2+) oscillations. These data strengthen our previous findings that in porcine eggs SOCE is a major signaling cascade that is responsible for sustaining the repetitive Ca(2+) signal at fertilization.

  14. Ca2+ microdomains near plasma membrane Ca2+ channels: impact on cell function.

    PubMed

    Parekh, Anant B

    2008-07-01

    In eukaryotic cells, a rise in cytoplasmic Ca(2+) can activate a plethora of responses that operate on time scales ranging from milliseconds to days. Inherent to the use of a promiscuous signal like Ca(2+) is the problem of specificity: how can Ca(2+) activate some responses but not others? We now know that the spatial profile of the Ca(2+) signal is important Ca(2+) does not simply rise uniformly throughout the cytoplasm upon stimulation but can reach very high levels locally, creating spatial gradients. The most fundamental local Ca(2+) signal is the Ca(2+) microdomain that develops rapidly near open plasmalemmal Ca(2+) channels like voltage-gated L-type (Cav1.2) and store-operated CRAC channels. Recent work has revealed that Ca(2+) microdomains arising from these channels are remarkably versatile in triggering a range of responses that differ enormously in both temporal and spatial profile. Here, I delineate basic features of Ca(2+) microdomains and then describe how these highly local signals are used by Ca(2+)-permeable channels to drive cellular responses. PMID:18467365

  15. Extracellular Ca2+-sensing receptors--an overview.

    PubMed

    Chang, Wenhan; Shoback, Dolores

    2004-03-01

    Extracellular Ca2+-sensing receptors (CaRs) are the molecular basis by which specialized cells detect and respond to changes in the extracellular [Ca2+] ([Ca2+]o). CaRs belong to the family C of G-protein coupled receptors (GPCRs). Activation of CaRs triggers signaling pathways that modify numerous cell functions. Multiple ligands regulate the activation of CaRs including multivalent cations, L-amino acids, and changes in ionic strength and pH. CaRs in parathyroid cells play a central role in systemic Ca2+ homeostasis in terrestrial tetrapods. Mutations of the CaR gene in humans cause diseases in which serum and urine [Ca2+] and parathyroid hormone (PTH) levels are altered. CaR homologues are also expressed in organs critical to Ca2+ transport in ancient and modern fish, suggesting that similar receptors may have long been involved in Ca2+ homeostasis in lower vertebrates before parathyroid glands developed in terrestrial vertebrates. CaR mRNA and protein are also expressed in tissues not directly involved in Ca2+ homeostasis. This implies that there may be other biological roles for CaRs. Studies of CaR-knockout mice confirm the importance of CaRs in the parathyroid gland and kidney. The functions of CaRs in tissues other than kidney and parathyroid gland, however, remain to be elucidated.

  16. Aging and CaMKII alter intracellular Ca2+ transients and heart rhythm in Drosophila melanogaster.

    PubMed

    Santalla, Manuela; Valverde, Carlos A; Harnichar, Ezequiel; Lacunza, Ezequiel; Aguilar-Fuentes, Javier; Mattiazzi, Alicia; Ferrero, Paola

    2014-01-01

    Aging is associated to disrupted contractility and rhythmicity, among other cardiovascular alterations. Drosophila melanogaster shows a pattern of aging similar to human beings and recapitulates the arrhythmogenic conditions found in the human heart. Moreover, the kinase CaMKII has been characterized as an important regulator of heart function and an arrhythmogenic molecule that participate in Ca2+ handling. Using a genetically engineered expressed Ca2+ indicator, we report changes in cardiac Ca2+ handling at two different ages. Aging prolonged relaxation, reduced spontaneous heart rate (HR) and increased the occurrence of arrhythmias, ectopic beats and asystoles. Alignment between Drosophila melanogaster and human CaMKII showed a high degree of conservation and indicates that relevant phosphorylation sites in humans are also present in the fruit fly. Inhibition of CaMKII by KN-93 (CaMKII-specific inhibitor), reduced HR without significant changes in other parameters. By contrast, overexpression of CaMKII increased HR and reduced arrhythmias. Moreover, it increased fluorescence amplitude, maximal rate of rise of fluorescence and reduced time to peak fluorescence. These results suggest that CaMKII in Drosophila melanogaster acts directly on heart function and that increasing CaMKII expression levels could be beneficial to improve contractility.

  17. Reduced endogenous Ca2+ buffering speeds active zone Ca2+ signaling.

    PubMed

    Delvendahl, Igor; Jablonski, Lukasz; Baade, Carolin; Matveev, Victor; Neher, Erwin; Hallermann, Stefan

    2015-06-01

    Fast synchronous neurotransmitter release at the presynaptic active zone is triggered by local Ca(2+) signals, which are confined in their spatiotemporal extent by endogenous Ca(2+) buffers. However, it remains elusive how rapid and reliable Ca(2+) signaling can be sustained during repetitive release. Here, we established quantitative two-photon Ca(2+) imaging in cerebellar mossy fiber boutons, which fire at exceptionally high rates. We show that endogenous fixed buffers have a surprisingly low Ca(2+)-binding ratio (∼ 15) and low affinity, whereas mobile buffers have high affinity. Experimentally constrained modeling revealed that the low endogenous buffering promotes fast clearance of Ca(2+) from the active zone during repetitive firing. Measuring Ca(2+) signals at different distances from active zones with ultra-high-resolution confirmed our model predictions. Our results lead to the concept that reduced Ca(2+) buffering enables fast active zone Ca(2+) signaling, suggesting that the strength of endogenous Ca(2+) buffering limits the rate of synchronous synaptic transmission. PMID:26015575

  18. Genetical and comparative genomics of Brassica under altered Ca supply identifies Arabidopsis Ca-transporter orthologs.

    PubMed

    Graham, Neil S; Hammond, John P; Lysenko, Artem; Mayes, Sean; O Lochlainn, Seosamh; Blasco, Bego; Bowen, Helen C; Rawlings, Chris J; Rios, Juan J; Welham, Susan; Carion, Pierre W C; Dupuy, Lionel X; King, Graham J; White, Philip J; Broadley, Martin R

    2014-07-01

    Although Ca transport in plants is highly complex, the overexpression of vacuolar Ca(2+) transporters in crops is a promising new technology to improve dietary Ca supplies through biofortification. Here, we sought to identify novel targets for increasing plant Ca accumulation using genetical and comparative genomics. Expression quantitative trait locus (eQTL) mapping to 1895 cis- and 8015 trans-loci were identified in shoots of an inbred mapping population of Brassica rapa (IMB211 × R500); 23 cis- and 948 trans-eQTLs responded specifically to altered Ca supply. eQTLs were screened for functional significance using a large database of shoot Ca concentration phenotypes of Arabidopsis thaliana. From 31 Arabidopsis gene identifiers tagged to robust shoot Ca concentration phenotypes, 21 mapped to 27 B. rapa eQTLs, including orthologs of the Ca(2+) transporters At-CAX1 and At-ACA8. Two of three independent missense mutants of BraA.cax1a, isolated previously by targeting induced local lesions in genomes, have allele-specific shoot Ca concentration phenotypes compared with their segregating wild types. BraA.CAX1a is a promising target for altering the Ca composition of Brassica, consistent with prior knowledge from Arabidopsis. We conclude that multiple-environment eQTL analysis of complex crop genomes combined with comparative genomics is a powerful technique for novel gene identification/prioritization.

  19. A Model-Independent Algorithm to Derive Ca2+ Fluxes Underlying Local Cytosolic Ca2+ Transients

    PubMed Central

    Ventura, Alejandra C.; Bruno, Luciana; Demuro, Angelo; Parker, Ian; Ponce Dawson, Silvina

    2005-01-01

    Local intracellular Ca2+ signals result from Ca2+ flux into the cytosol through individual channels or clusters of channels. To gain a mechanistic understanding of these events we need to know the magnitude and spatial distribution of the underlying Ca2+ flux. However, this is difficult to infer from fluorescence Ca2+ images because the distribution of Ca2+-bound dye is affected by poorly characterized processes including diffusion of Ca2+ ions, their binding to mobile and immobile buffers, and sequestration by Ca2+ pumps. Several methods have previously been proposed to derive Ca2+ flux from fluorescence images, but all require explicit knowledge or assumptions regarding these processes. We now present a novel algorithm that requires few assumptions and is largely model-independent. By testing the algorithm with both numerically generated image data and experimental images of sparklets resulting from Ca2+ flux through individual voltage-gated channels, we show that it satisfactorily reconstructs the magnitude and time course of the underlying Ca2+ currents. PMID:15681645

  20. Aging and CaMKII Alter Intracellular Ca2+ Transients and Heart Rhythm in Drosophila melanogaster

    PubMed Central

    Santalla, Manuela; Valverde, Carlos A.; Harnichar, Ezequiel; Lacunza, Ezequiel; Aguilar-Fuentes, Javier; Mattiazzi, Alicia; Ferrero, Paola

    2014-01-01

    Aging is associated to disrupted contractility and rhythmicity, among other cardiovascular alterations. Drosophila melanogaster shows a pattern of aging similar to human beings and recapitulates the arrhythmogenic conditions found in the human heart. Moreover, the kinase CaMKII has been characterized as an important regulator of heart function and an arrhythmogenic molecule that participate in Ca2+ handling. Using a genetically engineered expressed Ca2+ indicator, we report changes in cardiac Ca2+ handling at two different ages. Aging prolonged relaxation, reduced spontaneous heart rate (HR) and increased the occurrence of arrhythmias, ectopic beats and asystoles. Alignment between Drosophila melanogaster and human CaMKII showed a high degree of conservation and indicates that relevant phosphorylation sites in humans are also present in the fruit fly. Inhibition of CaMKII by KN-93 (CaMKII-specific inhibitor), reduced HR without significant changes in other parameters. By contrast, overexpression of CaMKII increased HR and reduced arrhythmias. Moreover, it increased fluorescence amplitude, maximal rate of rise of fluorescence and reduced time to peak fluorescence. These results suggest that CaMKII in Drosophila melanogaster acts directly on heart function and that increasing CaMKII expression levels could be beneficial to improve contractility. PMID:25003749

  1. Ca2+ signalling, voltage-gated Ca2+ channels and praziquantel in flatworm neuromusculature.

    PubMed

    Greenberg, R M

    2005-01-01

    Transient changes in calcium (Ca2+) levels regulate a wide variety of cellular processes, and cells employ both intracellular and extracellular sources of Ca2+ for signalling. Praziquantel, the drug of choice against schistosomiasis, disrupts Ca2+ homeostasis in adult worms. This review will focus on voltage-gated Ca2+ channels, which regulate levels of intracellular Ca2+ by coupling membrane depolarization to entry of extracellular Ca2+. Ca2+ channels are members of the ion channel superfamily and represent essential components of neurons, muscles and other excitable cells. Ca2+ channels are membrane protein complexes in which the pore-forming alpha1 subunit is modulated by auxiliary subunits such as beta and alpha2delta. Schistosomes express two Ca2+ channel beta subunit subtypes: a conventional subtype similar to beta subunits found in other vertebrates and invertebrates and a novel variant subtype with unusual structural and functional properties. The variant schistosome beta subunit confers praziquantel sensitivity to an otherwise praziquantel-insensitive mammalian Ca2+ channel, implicating it as a mediator of praziquantel action.

  2. Prognostic significance of preoperative serum CA125, CA19-9 and CEA in gastric carcinoma

    PubMed Central

    Wang, Wei; Chen, Xiao-Long; Zhao, Shen-Yu; Xu, Yu-Hui; Zhang, Wei-Han; Liu, Kai; Chen, Xin-Zu; Yang, Kun; Zhang, Bo; Chen, Zhi-Xin; Chen, Jia-Ping; Zhou, Zong-Guang; Hu, Jian-Kun

    2016-01-01

    The prognostic significance of preoperative serum CA125, CA19-9 and CEA in gastric carcinoma (GC) has been widely reported and is still under debate. Here, we evaluated the prognostic significance of preoperative serum CA125, CA19-9 and CEA in patients with GC. 1692 patients with GC who underwent gastrectomy were divided into the training (from January 2005 to December 2011, n = 1024) and the validation (from January 2012 to December 2013, n = 668) cohorts. Positive groups of CA125 (> 13.72 U/ml), CA19-9 (> 23.36 U/ml) and CEA (> 4.28 ng/ml) were significantly associated with more advanced clinicopathological traits and worse outcomes than that of negative groups (all P < 0.01). In Cox regression analysis, tumor size (P < 0.001, P = 0.005), pTNM stage (P < 0.001, P < 0.001) and CA125 (P = 0.026, P = 0.005) were independent prognostic factors both in two cohorts. Nomograms of these two cohorts based on the number of positive serum tumor markers (NPTM) were more accurate in prognostic prediction than TNM stage alone. Our findings suggested that elevated preoperative serum CA125, CA19-9 and CEA were associated with more advanced clinicopathological traits and less favorable outcomes. In addition, CA125 as an independent prognostic factor should be further investigated. Nomogram based on NPTM could accurately predict the prognosis of GC patients. PMID:27097114

  3. Effects of rapid buffers on Ca2+ diffusion and Ca2+ oscillations.

    PubMed Central

    Wagner, J; Keizer, J

    1994-01-01

    Based on realistic mechanisms of Ca2+ buffering that include both stationary and mobile buffers, we derive and investigate models of Ca2+ diffusion in the presence of rapid buffers. We obtain a single transport equation for Ca2+ that contains the effects caused by both stationary and mobile buffers. For stationary buffers alone, we obtain an expression for the effective diffusion constant of Ca2+ that depends on local Ca2+ concentrations. Mobile buffers, such as fura-2, BAPTA, or small endogenous proteins, give rise to a transport equation that is no longer strictly diffusive. Calculations are presented to show that these effects can modify greatly the manner and rate at which Ca2+ diffuses in cells, and we compare these results with recent measurements by Allbritton et al. (1992). As a prelude to work on Ca2+ waves, we use a simplified version of our model of the activation and inhibition of the IP3 receptor Ca2+ channel in the ER membrane to illustrate the way in which Ca2+ buffering can affect both the amplitude and existence of Ca2+ oscillations. PMID:7919018

  4. Regulated release of Ca2+ from respiring mitochondria by Ca2+/2H+ antiport.

    PubMed

    Fiskum, G; Lehninger, A L

    1979-07-25

    Simultaneous measurements of oxygen consumption and transmembrane transport of Ca2+, H+, and phosphate show that the efflux of Ca2+ from respiring tightly coupled rat liver mitochondria takes place by an electroneutral Ca2+/2H+ antiport process that is ruthenium red-insensitive and that is regulated by the oxidation-reduction state of the mitochondrial pyridine nucleotides. When mitochondrial pyridine nucleotides are kept in a reduced steady state, the efflux of Ca2+ is inhibited; when they are in an oxidized state, Ca2+ efflux is activated. These processes were demonstrated by allowing phosphate-depleted mitochondria respiring on succinate in the presence of rotenone to take up Ca2+ from the medium. Upon subsequent addition of ruthenium red to block Ca2+ transport via the electrophoretic influx pathway, and acetoacetate, to bring mitochondrial pyridine nucleotides into the oxidized state, Ca2+ efflux and H+ influx ensued. The observed H+ influx/Ca2+ efflux ratio was close to the value 2.0 predicted for the operation of an electrically neutral Ca2+/2H+ antiport process.

  5. Pericellular Ca2+ recycling potentiates thrombin-evoked Ca2+ signals in human platelets

    PubMed Central

    Sage, Stewart O; Pugh, Nicholas; Farndale, Richard W; Harper, Alan G S

    2013-01-01

    We have previously demonstrated that Na+/Ca2+ exchangers (NCXs) potentiate Ca2+ signaling evoked by thapsigargin in human platelets, via their ability to modulate the secretion of autocoids from dense granules. This link was confirmed in platelets stimulated with the physiological agonist, thrombin, and experiments were performed to examine how Ca2+ removal by the NCX modulates platelet dense granule secretion. In cells loaded with the near-membrane indicator FFP-18, thrombin stimulation was observed to elicit an NCX-dependent accumulation of Ca2+ in a pericellular region around the platelets. To test whether this pericellular Ca2+ accumulation might be responsible for the influence of NCXs over platelet function, platelets were exposed to fast Ca2+ chelators or had their glycocalyx removed. Both manipulations of the pericellular Ca2+ rise reduced thrombin-evoked Ca2+ signals and dense granule secretion. Blocking Ca2+-permeable ion channels had a similar effect, suggesting that Ca2+ exported into the pericellular region is able to recycle back into the platelet cytosol. Single cell imaging with extracellular Fluo-4 indicated that thrombin-evoked rises in extracellular [Ca2+] occurred within the boundary described by the cell surface, suggesting their presence within the open canalicular system (OCS). FFP-18 fluorescence was similarly distributed. These data suggest that upon thrombin stimulation, NCX activity creates a rise in [Ca2+] within the pericellular region of the platelet from where it recycles back into the platelet cytosol, acting to both accelerate dense granule secretion and maintain the initial rise in cytosolic [Ca2+]. PMID:24303163

  6. Calcium transport in bovine rumen epithelium as affected by luminal Ca concentrations and Ca sources

    PubMed Central

    Schröder, Bernd; Wilkens, Mirja R; Ricken, Gundula E; Leonhard-Marek, Sabine; Fraser, David R; Breves, Gerhard

    2015-01-01

    The quantitative role of different segments of the gastrointestinal tract for Ca absorption, the respective mechanisms, and their regulation are not fully identified for ruminants, that is, cattle. In different in vitro experiments the forestomach wall has been demonstrated to be a major site for active Ca absorption in sheep and goats. In order to further clarify the role of the bovine rumen for Ca transport with special attention to luminal Ca concentrations, its ionic form, and pH, electrophysiological and unidirectional flux rate measurements were performed with isolated bovine rumen epithelial tissues. For Ca flux studies (Jms, Jsm) in vitro Ussing chamber technique was applied. Standard RT-PCR method was used to characterize TRPV6 and PMCA1 as potential contributors to transepithelial active Ca transport. At Ca concentrations of 1.2 mmol L−1 on both sides of the tissues, Jms were higher than Jsm resulting under some conditions in significant Ca net flux rates (Jnet), indicating the presence of active Ca transport. In the absence of an electrical gradient, Jnet could significantly be stimulated in the presence of luminal short-chain fatty acids (SCFAs). Increasing the luminal Ca concentrations up to 11.2 mmol L−1 resulted in significant increases in Jms without influencing Jsm. Providing Ca in its form as respective chloride, formate, or propionate salts there was no significant effect on Jms. No transcripts specific for Ca channel TRPV6 could be demonstrated. Our results indicate different mechanisms for Ca absorption in bovine rumen as compared with those usually described for the small intestines. PMID:26564067

  7. Distribution of CA 125 in placental tissues.

    PubMed

    Fuith, L C; Müller-Holzner, E; Marth, C; Perkmann, E; Zeimet, A; Daxenbichler, G

    1989-01-01

    The presence of the tumor marker CA 125 was studied in different compartments of the human placenta. Levels of CA 125 in the cytosol of chorionic villi ranged from 27-17100 U/g (median 560 U/g). In the placental amnion and chorion concentrations ranged from 175-29000 U/g, median 1060 U/g and were not statistically different. In the umbilical cord values were significantly lower (range 44-7600 U/g; median 180 U/g). Maternal serum probes were above the upper limit of normal in all cases (range 48-500 U/ml; median 131 U/ml). Immunohistochemistry detected CA 125 exclusively within the amniotic cells of the placenta and the umbilical cord. This might be because CA 125 fixes more to insoluble structures in the amnion or because of contamination of chorionic villi with the underlying decidua.

  8. Departure gate of acidic Ca2+ confirmed

    PubMed Central

    Jentsch, Thomas J; Hoegg-Beiler, Maja B; Vogt, Janis

    2015-01-01

    More potent, but less known than IP3 that liberates Ca2+ from the ER, NAADP releases Ca2+ from acidic stores. The notion that TPC channels mediate this Ca2+ release was questioned recently by studies suggesting that TPCs are rather PI(3,5)P2-activated Na+ channels. Ruas et al (2015) now partially reconcile these views by showing that TPCs significantly conduct both cations and confirm their activation by both NAADP and PI(3,5)P2. They attribute the failure of others to observe TPC-dependent NAADP-induced Ca2+ release in vivo to inadequate mouse models that retain partial TPC function. PMID:26022292

  9. Role of Ca++ in Shoot Gravitropism. [avena

    NASA Technical Reports Server (NTRS)

    Rayle, D. L.

    1985-01-01

    A cornerstone in the argument that Ca(2+) levels may regulate growth is the finding the EGTA promotes straight growth. The usual explanation for these results is that Ca(2+) chelation from cell walls results in wall loosening and thus accelerated straight growth. The ability of frozen-thawed Avena coleoptile tissue (subjected to 15g tension) to extend in response to EGTA and Quin II was examined. The EGTA when applied in weakly buffered (i.e., 0.1mM) neutral solutions initiates rapid extension. When the buffer strength is increased, similar concentrations of EGTA produce no growth response. This implies when EGTA liberated protons are released upon Ca(2+) chelation they can either initiate acid growth (low buffer conditions) or if consumed (high buffer conditions) have no effect. Thus Ca(2+) chelation in itself apparently does not result in straight growth.

  10. Ca Isotope Fractionation in the Hawaiian Ecosystem

    NASA Astrophysics Data System (ADS)

    Wiegand, B. A.; Chadwick, O. A.; Vitousek, P. M.; Wooden, J. L.

    2003-12-01

    Investigations of the nutrient budgets in Hawaiian soils show the sources of major cations to be weathering of volcanic rock, marine aerosols, and Asian dust inputs. Especially at deeply weathered sites older than 150 ka, soils show strong depletion of the macronutrient calcium. Most of the calcium supply in these soils is of atmospheric origin (marine aerosols and continental dust). In contrast, younger soils are mainly supplied by calcium from weathering of volcanic bedrock. Based on the results of previous studies using strontium isotopic signatures and Sr/Ca ratios (e.g. Kennedy et al. 1998, Chadwick et al. 1999, Whipkey et al. 2000, Stewart et al. 2001) we have conducted research focusing on the isotope composition of calcium as a new tool for the investigation of sources of calcium and biogeochemical processes effecting Ca isotope fractionation in the plant-soil system. The study combines δ 44Ca with 87Sr/86Sr and Sr/Ca data of soils (bulk compositions and extractable Ca and Sr from soil exchange sites) and different plant species including native Ohia trees (Metrosideros polymorpha) from a soil chronosequence along the Hawaiian Island chain. The study sites differ in age of the underlying substrate from 0.3 ka to 4,100 ka, but show similar recent climate (mean annual temperature of 16 ° C) and amount of precipitation (about 2,500 mm/y). 44Ca/40Ca ratios were measured on a MAT262 at Stanford University, using a 42Ca-48Ca double spike, and are reported as δ 44Ca values relative to seawater (δ 44Ca = 0 ‰ ). Results of the extractable, plant available calcium from six soil sites show δ 44Ca values in the range of +1.2 ‰ to -1.3 ‰ with generally more negative values related to younger soil sites where calcium is mainly derived from weathering of volcanic rocks. Bulk soil samples, however, show δ 44Ca values between -0.1 ‰ and -2.5 ‰ , indicating differences in composition as a result of contributions from volcanic minerals, continental dust, and

  11. Ca channel gating during cardiac action potentials.

    PubMed

    Mazzanti, M; DeFelice, L J

    1990-10-01

    How do Ca channels conduct Ca ions during the cardiac action potential? We attempt to answer this question by applying a two-microelectrode technique, previously used for Na and K currents, in which we record the patch current and the action potential at the same time (Mazzanti, M., and L. J. DeFelice. 1987. Biophys. J. 12:95-100, and 1988. Biophys. J. 54:1139-1148; Wellis, D., L. J. DeFelice, and M. Mazzanti. 1990. Biophys. J. 57:41-48). In this paper, we also compare the action currents obtained by the technique with the step-protocol currents obtained during standard voltage-clamp experiments. Individual Ca channels were measured in 10 mM Ca/1 Ba and 10 mM Ba. To describe part of our results, we use the nomenclature introduced by Hess, P., J. B. Lansman, and R. W. Tsien (1984. Nature (Lond.). 311:538-544). With Ba as the charge carrier, Ca channel kinetics convert rapidly from long to short open times as the patch voltage changes from 20 to -20 mV. This voltage-dependent conversion occurs during action potentials and in step-protocol experiments. With Ca as the charge carrier, the currents are brief at all voltages, and it is difficult to define either the number of channels in the patch or the conductance of the individual channels. Occasionally, however, Ca-conducting channels spontaneously convert to long-open-time kinetics (in Hess et al., 1984, notation, mode 2). When this happens, which is about once in every 100beats, there usually appears to be only one channel in the patch. In this rare configuration, the channel is open long enough to measure its conductance in 10 Ca/ 1 Ba. The value is 8-10 pS, which is about half the conductance in Ba. Because the long openings occur so infrequently with Ca as the charge carrier, they contribute negligibly to the average Ca current at any particular time during an action potential. However, the total number of Ca ions entering during these long openings may be significant when compared to the number entering by the

  12. Ca channel gating during cardiac action potentials.

    PubMed

    Mazzanti, M; DeFelice, L J

    1990-10-01

    How do Ca channels conduct Ca ions during the cardiac action potential? We attempt to answer this question by applying a two-microelectrode technique, previously used for Na and K currents, in which we record the patch current and the action potential at the same time (Mazzanti, M., and L. J. DeFelice. 1987. Biophys. J. 12:95-100, and 1988. Biophys. J. 54:1139-1148; Wellis, D., L. J. DeFelice, and M. Mazzanti. 1990. Biophys. J. 57:41-48). In this paper, we also compare the action currents obtained by the technique with the step-protocol currents obtained during standard voltage-clamp experiments. Individual Ca channels were measured in 10 mM Ca/1 Ba and 10 mM Ba. To describe part of our results, we use the nomenclature introduced by Hess, P., J. B. Lansman, and R. W. Tsien (1984. Nature (Lond.). 311:538-544). With Ba as the charge carrier, Ca channel kinetics convert rapidly from long to short open times as the patch voltage changes from 20 to -20 mV. This voltage-dependent conversion occurs during action potentials and in step-protocol experiments. With Ca as the charge carrier, the currents are brief at all voltages, and it is difficult to define either the number of channels in the patch or the conductance of the individual channels. Occasionally, however, Ca-conducting channels spontaneously convert to long-open-time kinetics (in Hess et al., 1984, notation, mode 2). When this happens, which is about once in every 100beats, there usually appears to be only one channel in the patch. In this rare configuration, the channel is open long enough to measure its conductance in 10 Ca/ 1 Ba. The value is 8-10 pS, which is about half the conductance in Ba. Because the long openings occur so infrequently with Ca as the charge carrier, they contribute negligibly to the average Ca current at any particular time during an action potential. However, the total number of Ca ions entering during these long openings may be significant when compared to the number entering by the

  13. Efficient 41Ca measurements for biomedical applications

    NASA Astrophysics Data System (ADS)

    Vockenhuber, C.; Schulze-König, T.; Synal, H.-A.; Aeberli, I.; Zimmermann, M. B.

    2015-10-01

    We present the performance of 41Ca measurements using low-energy Accelerator Mass Spectrometry (AMS) at the 500 kV facility TANDY at ETH Zurich. We optimized the measurement procedure for biomedical applications where reliability and high sample throughput is required. The main challenge for AMS measurements of 41Ca is the interfering stable isobar 41K. We use a simplified sample preparation procedure to produce calcium fluoride (CaF2) and extract calcium tri-fluoride ions (CaF3-) ions to suppress the stable isobar 41K. Although 41K is not completely suppressed we reach 41Ca/40Ca background level in the 10-12 range which is adequate for biomedical studies. With helium as a stripper gas we can use charge state 2+ at high transmission (∼50%). The new measurement procedure with the approximately 10 × improved efficiency and the higher accuracy due to 41K correction allowed us to measure more than 600 samples for a large biomedical study within only a few weeks of measurement time.

  14. Intracellular Ca2+ signaling and preimplantation development.

    PubMed

    Armant, D Randall

    2015-01-01

    The key, versatile role of intracellular Ca2+ signaling during egg activation after fertilization has been appreciated for several decades. More recently, evidence has accumulated supporting the concept that cytoplasmic Ca2+ is also a major signaling nexus during subsequent development of the fertilized ovum. This chapter will review the molecular reactions that regulate intracellular Ca2+ levels and cell function, the role of Ca2+ signaling during egg activation and specific examples of repetitive Ca2+ signaling found throughout pre- and peri-implantation development. Many of the upstream and downstream pathways utilized during egg activation are also critical for specific processes that take place during embryonic development. Much remains to be done to elucidate the full complexity of Ca2+ signaling mechanisms in preimplantation embryos to the level of detail accomplished for egg activation. However, an emerging concept is that because this second messenger can be modulated downstream of numerous receptors and is able to bind and activate multiple cytoplasmic signaling proteins, it can help the coordination of development through up- and downstream pathways that change with each embryonic stage.

  15. Stellar neutron capture rates for /sup 46/Ca and /sup 48/Ca

    SciTech Connect

    Kaeppeller, F.; Walter, G.; Mathews, G.J.

    1985-04-01

    Stellar neutron capture rates for /sup 46/Ca and /sup 48/Ca have been measured by the activation technique. Both kT = 25 keV Maxwellian-like incident neutron spectra and non-Maxwellian higher energy spectra have been utilized to study the possible role of individual capture resonances. Maxwellian-averaged (kT = 30 keV) cross sections of 5.7 +- 0.5 and 0.95 +- 0.09 mb are derived for /sup 46/Ca and /sup 48/Ca, respectively. The possibility of a neutron capture origin for /sup 46/Ca and /sup 48/Ca is discussed in the light of these new cross sections, as well as a mechanism for the production of the observed isotopic anomalies in inclusion EK-1-4-1 from the Allende meteorite.

  16. Sarcolemmal Ca(2+)-entry through L-type Ca(2+) channels controls the profile of Ca(2+)-activated Cl(-) current in canine ventricular myocytes.

    PubMed

    Horváth, Balázs; Váczi, Krisztina; Hegyi, Bence; Gönczi, Mónika; Dienes, Beatrix; Kistamás, Kornél; Bányász, Tamás; Magyar, János; Baczkó, István; Varró, András; Seprényi, György; Csernoch, László; Nánási, Péter P; Szentandrássy, Norbert

    2016-08-01

    Ca(2+)-activated Cl(-) current (ICl(Ca)) mediated by TMEM16A and/or Bestrophin-3 may contribute to cardiac arrhythmias. The true profile of ICl(Ca) during an actual ventricular action potential (AP), however, is poorly understood. We aimed to study the profile of ICl(Ca) systematically under physiological conditions (normal Ca(2+) cycling and AP voltage-clamp) as well as in conditions designed to change [Ca(2+)]i. The expression of TMEM16A and/or Bestrophin-3 in canine and human left ventricular myocytes was examined. The possible spatial distribution of these proteins and their co-localization with Cav1.2 was also studied. The profile of ICl(Ca), identified as a 9-anthracene carboxylic acid-sensitive current under AP voltage-clamp conditions, contained an early fast outward and a late inward component, overlapping early and terminal repolarizations, respectively. Both components were moderately reduced by ryanodine, while fully abolished by BAPTA, but not EGTA. [Ca(2+)]i was monitored using Fura-2-AM. Setting [Ca(2+)]i to the systolic level measured in the bulk cytoplasm (1.1μM) decreased ICl(Ca), while application of Bay K8644, isoproterenol, and faster stimulation rates increased the amplitude of ICl(Ca). Ca(2+)-entry through L-type Ca(2+) channels was essential for activation of ICl(Ca). TMEM16A and Bestrophin-3 showed strong co-localization with one another and also with Cav1.2 channels, when assessed using immunolabeling and confocal microscopy in both canine myocytes and human ventricular myocardium. Activation of ICl(Ca) in canine ventricular cells requires Ca(2+)-entry through neighboring L-type Ca(2+) channels and is only augmented by SR Ca(2+)-release. Substantial activation of ICl(Ca) requires high Ca(2+) concentration in the dyadic clefts which can be effectively buffered by BAPTA, but not EGTA. PMID:27189885

  17. Interlaboratory study for coral Sr/Ca and other element/Ca ratio measurements

    NASA Astrophysics Data System (ADS)

    Hathorne, Ed C.; Gagnon, Alex; Felis, Thomas; Adkins, Jess; Asami, Ryuji; Boer, Wim; Caillon, Nicolas; Case, David; Cobb, Kim M.; Douville, Eric; deMenocal, Peter; Eisenhauer, Anton; Garbe-Schönberg, Dieter; Geibert, Walter; Goldstein, Steven; Hughen, Konrad; Inoue, Mayuri; Kawahata, Hodaka; Kölling, Martin; Cornec, Florence L.; Linsley, Braddock K.; McGregor, Helen V.; Montagna, Paolo; Nurhati, Intan S.; Quinn, Terrence M.; Raddatz, Jacek; Rebaubier, Hélène; Robinson, Laura; Sadekov, Aleksey; Sherrell, Rob; Sinclair, Dan; Tudhope, Alexander W.; Wei, Gangjian; Wong, Henri; Wu, Henry C.; You, Chen-Feng

    2013-09-01

    The Sr/Ca ratio of coral aragonite is used to reconstruct past sea surface temperature (SST). Twenty-one laboratories took part in an interlaboratory study of coral Sr/Ca measurements. Results show interlaboratory bias can be significant, and in the extreme case could result in a range in SST estimates of 7°C. However, most of the data fall within a narrower range and the Porites coral reference material JCp-1 is now characterized well enough to have a certified Sr/Ca value of 8.838 mmol/mol with an expanded uncertainty of 0.089 mmol/mol following International Association of Geoanalysts (IAG) guidelines. This uncertainty, at the 95% confidence level, equates to 1.5°C for SST estimates using Porites, so is approaching fitness for purpose. The comparable median within laboratory error is <0.5°C. This difference in uncertainties illustrates the interlaboratory bias component that should be reduced through the use of reference materials like the JCp-1. There are many potential sources contributing to biases in comparative methods but traces of Sr in Ca standards and uncertainties in reference solution composition can account for half of the combined uncertainty. Consensus values that fulfil the requirements to be certified values were also obtained for Mg/Ca in JCp-1 and for Sr/Ca and Mg/Ca ratios in the JCt-1 giant clam reference material. Reference values with variable fitness for purpose have also been obtained for Li/Ca, B/Ca, Ba/Ca, and U/Ca in both reference materials. In future, studies reporting coral element/Ca data should also report the average value obtained for a reference material such as the JCp-1.

  18. Mitochondrial calcium uniporter MCU supports cytoplasmic Ca2+ oscillations, store-operated Ca2+ entry and Ca2+-dependent gene expression in response to receptor stimulation.

    PubMed

    Samanta, Krishna; Douglas, Sophie; Parekh, Anant B

    2014-01-01

    Ca2+ flux into mitochondria is an important regulator of cytoplasmic Ca2+ signals, energy production and cell death pathways. Ca2+ uptake can occur through the recently discovered mitochondrial uniporter channel (MCU) but whether the MCU is involved in shaping Ca2+ signals and downstream responses to physiological levels of receptor stimulation is unknown. Here, we show that modest stimulation of leukotriene receptors with the pro-inflammatory signal LTC4 evokes a series of cytoplasmic Ca2+ oscillations that are rapidly and faithfully propagated into mitochondrial matrix. Knockdown of MCU or mitochondrial depolarisation, to reduce the driving force for Ca2+ entry into the matrix, prevents the mitochondrial Ca2+ rise and accelerates run down of the oscillations. The loss of cytoplasmic Ca2+ oscillations appeared to be a consequence of enhanced Ca2+-dependent inactivation of InsP3 receptors, which arose from the loss of mitochondrial Ca2+ buffering. Ca2+ dependent gene expression in response to leukotriene receptor activation was suppressed following knockdown of the MCU. In addition to buffering Ca2+ release, mitochondria also sequestrated Ca2+ entry through store-operated Ca2+ channels and this too was prevented following loss of MCU. MCU is therefore an important regulator of physiological pulses of cytoplasmic Ca2+.

  19. Regulation of RYR1 activity by Ca(2+) and calmodulin

    NASA Technical Reports Server (NTRS)

    Rodney, G. G.; Williams, B. Y.; Strasburg, G. M.; Beckingham, K.; Hamilton, S. L.

    2000-01-01

    The skeletal muscle calcium release channel (RYR1) is a Ca(2+)-binding protein that is regulated by another Ca(2+)-binding protein, calmodulin. The functional consequences of calmodulin's interaction with RYR1 are dependent on Ca(2+) concentration. At nanomolar Ca(2+) concentrations, calmodulin is an activator, but at micromolar Ca(2+) concentrations, calmodulin is an inhibitor of RYR1. This raises the question of whether the Ca(2+)-dependent effects of calmodulin on RYR1 function are due to Ca(2+) binding to calmodulin, RYR1, or both. To distinguish the effects of Ca(2+) binding to calmodulin from those of Ca(2+) binding to RYR1, a mutant calmodulin that cannot bind Ca(2+) was used to evaluate the effects of Ca(2+)-free calmodulin on Ca(2+)-bound RYR1. We demonstrate that Ca(2+)-free calmodulin enhances the affinity of RYR1 for Ca(2+) while Ca(2+) binding to calmodulin converts calmodulin from an activator to an inhibitor. Furthermore, Ca(2+) binding to RYR1 enhances its affinity for both Ca(2+)-free and Ca(2+)-bound calmodulin.

  20. The ryanodine receptor store-sensing gate controls Ca2+ waves and Ca2+-triggered arrhythmias.

    PubMed

    Chen, Wenqian; Wang, Ruiwu; Chen, Biyi; Zhong, Xiaowei; Kong, Huihui; Bai, Yunlong; Zhou, Qiang; Xie, Cuihong; Zhang, Jingqun; Guo, Ang; Tian, Xixi; Jones, Peter P; O'Mara, Megan L; Liu, Yingjie; Mi, Tao; Zhang, Lin; Bolstad, Jeff; Semeniuk, Lisa; Cheng, Hongqiang; Zhang, Jianlin; Chen, Ju; Tieleman, D Peter; Gillis, Anne M; Duff, Henry J; Fill, Michael; Song, Long-Sheng; Chen, S R Wayne

    2014-02-01

    Spontaneous Ca(2+) release from intracellular stores is important for various physiological and pathological processes. In cardiac muscle cells, spontaneous store overload-induced Ca(2+) release (SOICR) can result in Ca(2+) waves, a major cause of ventricular tachyarrhythmias (VTs) and sudden death. The molecular mechanism underlying SOICR has been a mystery for decades. Here we show that a point mutation, E4872A, in the helix bundle crossing region (the proposed gate) of the cardiac ryanodine receptor (RyR2) completely abolishes luminal, but not cytosolic, Ca(2+) activation of RyR2. The introduction of metal-binding histidines at this site converts RyR2 into a luminal Ni(2+)-gated channel. Mouse hearts harboring a heterozygous RyR2 mutation at this site (E4872Q) are resistant to SOICR and are completely protected against Ca(2+)-triggered VTs. These data show that the RyR2 gate directly senses luminal (store) Ca(2+), explaining the regulation of RyR2 by luminal Ca(2+), the initiation of Ca(2+) waves and Ca(2+)-triggered arrhythmias. This newly identified store-sensing gate structure is conserved in all RyR and inositol 1,4,5-trisphosphate receptor isoforms.

  1. Negative feedback from CaSR signaling to aquaporin-2 sensitizes vasopressin to extracellular Ca2.

    PubMed

    Ranieri, Marianna; Tamma, Grazia; Di Mise, Annarita; Russo, Annamaria; Centrone, Mariangela; Svelto, Maria; Calamita, Giuseppe; Valenti, Giovanna

    2015-07-01

    We previously described that high luminal Ca(2+) in the renal collecting duct attenuates short-term vasopressin-induced aquaporin-2 (AQP2) trafficking through activation of the Ca(2+)-sensing receptor (CaSR). Here, we evaluated AQP2 phosphorylation and permeability, in both renal HEK-293 cells and in the dissected inner medullary collecting duct, in response to specific activation of CaSR with NPS-R568. In CaSR-transfected cells, CaSR activation drastically reduced the basal levels of AQP2 phosphorylation at S256 (AQP2-pS256), thus having an opposite effect to vasopressin action. When forskolin stimulation was performed in the presence of NPS-R568, the increase in AQP2-pS256 and in the osmotic water permeability were prevented. In the freshly isolated inner mouse medullar collecting duct, stimulation with forskolin in the presence of NPS-R568 prevented the increase in AQP2-pS256 and osmotic water permeability. Our data demonstrate that the activation of CaSR in the collecting duct prevents the cAMP-dependent increase in AQP2-pS256 and water permeability, counteracting the short-term vasopressin response. By extension, our results suggest the attractive concept that CaSR expressed in distinct nephron segments exerts a negative feedback on hormones acting through cAMP, conferring high sensitivity of hormone to extracellular Ca(2+). PMID:25977473

  2. Radioisotope tracer studies of inorganic carbon and Ca in microbially derived CaCO3

    USGS Publications Warehouse

    Yates, Kimberly K.; Robbins, Lisa L.

    1999-01-01

    Microbial calcification significantly impacts the cycling and deposition of inorganic carbon. This research employs 45Ca and 14C techniques as radioisotopic tracers to examine the role of cellular cycling of Ca2+ and inorganic carbon in CaCO3 precipitation by the unicellular green alga Nannochloris atomus. Implications of the effects of these physiological aspects on CaCO3 precipitation and the effects of microbial calcification on CaCO3 δ13C ratios are discussed. Results from pulse/chase experiments indicate that intracellular Ca2+ is incorporated into extracellular CaCO3. Intracellular inorganic carbon leaks from cells within 10 to 12 s after injection of unlabelled NaHCO3, providing a source of inorganic carbon for extracellular CaCO3. Cellular expulsion of calcium plays a key role in increasing the CaCO3 saturation state at the site of calcification. The δ13C ratios of microbial carbonates may vary depending on the amount of photorespiratory CO2 incorporated.

  3. Pumping Ca2+ up H+ gradients: a Ca2+–H+ exchanger without a membrane

    PubMed Central

    Swietach, Pawel; Leem, Chae-Hun; Spitzer, Kenneth W; Vaughan-Jones, Richard D

    2014-01-01

    Cellular processes are exquisitely sensitive to H+ and Ca2+ ions because of powerful ionic interactions with proteins. By regulating the spatial and temporal distribution of intracellular [Ca2+] and [H+], cells such as cardiac myocytes can exercise control over their biological function. A well-established paradigm in cellular physiology is that ion concentrations are regulated by specialized, membrane-embedded transporter proteins. Many of these couple the movement of two or more ionic species per transport cycle, thereby linking ion concentrations among neighbouring compartments. Here, we compare and contrast canonical membrane transport with a novel type of Ca2+–H+ coupling within cytoplasm, which produces uphill Ca2+ transport energized by spatial H+ ion gradients, and can result in the cytoplasmic compartmentalization of Ca2+ without requiring a partitioning membrane. The mechanism, demonstrated in mammalian myocytes, relies on diffusible cytoplasmic buffers, such as carnosine, homocarnosine and ATP, to which Ca2+ and H+ ions bind in an apparently competitive manner. These buffer molecules can actively recruit Ca2+ to acidic microdomains, in exchange for the movement of H+ ions. The resulting Ca2+ microdomains thus have the potential to regulate function locally. Spatial cytoplasmic Ca2+–H+ exchange (cCHX) acts like a ‘pump’ without a membrane and may be operational in many cell types. PMID:24514908

  4. Mg/Ca of Continental Ostracode Shells

    NASA Astrophysics Data System (ADS)

    Ito, E.; Forester, R. M.; Marco-Barba, J.; Mezquita, F.

    2007-12-01

    Marine ionic chemistry is thought to remain constant. This, together with the belief that marine calcifiers partition Mg/Ca in a systematic manner as functions of temperature (and Mg/Ca) of water forms the basis of the Mg/Ca thermometer. In continental settings both of these assumptions are usually not true. Continental waters contain a wide variety of solutes in absolute and relative ion concentrations. Hence, waters with identical Mg/Ca may have very different concentrations of Mg and Ca and very different anions. Here we use two examples to focus on the effects of ion chemistry on Mg/Ca partitioning in continental ostracode shells and we ignore the complexities of solute evolution, which can change Mg/Ca over timescales of minutes to millennia. Palacios-Fest and Dettman (2001) conducted a monthly study of ,Cypridopsis vidua at El Yeso Lake in Sonora, Mexico. They established a relation between temperature and average shell Mg/Ca using regression analyses on averaged data. When their Mg/Ca-temperature relation is applied to monthly ,C. vidua data from Page Pond near Cleveland, Ohio, water temperatures of -8 to -1°C are obtained. The observed Mg/Ca ranges for El Yeso Lake (0.31 to 0.46) and Page Pond (0.33 to 0.46) are similar, as are their specific conductivities (700 to 850μS for El Yeso Lake; 400 to 600μS for Page Pond). However, [Ca] is 140-260 mg/L for El Yeso, but only 70-90 mg/L for Page Pond. Page Pond data, in fact, shows a good temperature shell Mg/Ca relation for .C. vidua, but the relation is different from that at El Yeso. Hence, shell Mg/Ca is a multi-valued, family of curves function of temperature and Mg/Ca of water that depends on the [Mg] and [Ca] values in water and perhaps other factors. Our second example comes from sites near Valencia, Spain and involves shell data for ,Cyprideis torosa, an estuarine ostracode that is tolerant of a wide range of salinity and can live in continental waters as long as the carbonate alkalinity to Ca ratio is

  5. Combined detection of CEA, CA 19-9, CA 242 and CA 50 in the diagnosis and prognosis of resectable gastric cancer.

    PubMed

    Tian, Shu-Bo; Yu, Jian-Chun; Kang, Wei-Ming; Ma, Zhi-Qiang; Ye, Xin; Cao, Zhan-Jiang; Yan, Chao

    2014-01-01

    Our aim was to investigate the value of combined detection of serum carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, CA 242 and CA 50 in diagnosis and assessment of prognosis in consecutive gastric cancer patients. Clinical data including preoperative serum CEA, CA 19-9, CA 242, and CA 50 values and information on clinical pathological factors were collected and analyzed retrospectively. Univariate and multivariate survival analyses were used to explore the relationship between tumor markers and survival. Positive rates of tumor markers CEA, CA 19-9, CA 242 and CA 50 in the diagnosis of gastric cancer were 17.7, 17.1, 20.4 and 13.8%, respectively, and the positive rate for all four markers combined was 36.6%. Patients with elevated preoperative serum concentrations of CEA, CA 19-9, CA 242 and CA 50, had late clinical tumor stage and significantly poorer overall survival. Five-year survival rates in patients with elevated CEA, CA 19-9, CA 242 and CA 50 were 28.1, 25.8, 27.0 and 24.1%, respectively, compared with 55.0, 55.4, 56.4 and 54.5% in patients with these markers at normal levels (p<0.01). In multivariate Cox proportional hazards analyses, an elevated CA 242 level was determined to be an independent prognostic marker in gastric cancer patients. Combined detection of four tumor markers increased the positive rate for gastric cancer diagnosis. CA 242 showed higher diagnostic value and CA 50 showed lower diagnostic value. In resectable gastric carcinoma, preoperative CA 242 level was associated with disease stage, and was found to be a significant independent prognostic marker in gastric cancer patients.

  6. The destiny of Ca(2+) released by mitochondria.

    PubMed

    Takeuchi, Ayako; Kim, Bongju; Matsuoka, Satoshi

    2015-01-01

    Mitochondrial Ca(2+) is known to regulate diverse cellular functions, for example energy production and cell death, by modulating mitochondrial dehydrogenases, inducing production of reactive oxygen species, and opening mitochondrial permeability transition pores. In addition to the action of Ca(2+) within mitochondria, Ca(2+) released from mitochondria is also important in a variety of cellular functions. In the last 5 years, the molecules responsible for mitochondrial Ca(2+) dynamics have been identified: a mitochondrial Ca(2+) uniporter (MCU), a mitochondrial Na(+)-Ca(2+) exchanger (NCLX), and a candidate for a mitochondrial H(+)-Ca(2+) exchanger (Letm1). In this review, we focus on the mitochondrial Ca(2+) release system, and discuss its physiological and pathophysiological significance. Accumulating evidence suggests that the mitochondrial Ca(2+) release system is not only crucial in maintaining mitochondrial Ca(2+) homeostasis but also participates in the Ca(2+) crosstalk between mitochondria and the plasma membrane and between mitochondria and the endoplasmic/sarcoplasmic reticulum.

  7. Ultrastructural and immunohistochemical localization of plasma membrane Ca2+-ATPase 4 in Ca2+-transporting epithelia.

    PubMed

    Alexander, R Todd; Beggs, Megan R; Zamani, Reza; Marcussen, Niels; Frische, Sebastian; Dimke, Henrik

    2015-10-01

    Plasma membrane Ca(2+)-ATPases (PMCAs) participate in epithelial Ca(2+) transport and intracellular Ca(2+) signaling. The Pmca4 isoform is enriched in distal nephron isolates and decreased in mice lacking the epithelial transient receptor potential vanilloid 5 Ca(2+) channel. We therefore hypothesized that Pmca4 plays a significant role in transcellular Ca(2+) flux and investigated the localization and regulation of Pmca4 in Ca(2+)-transporting epithelia. Using antibodies directed specifically against Pmca4, we found it expressed only in the smooth muscle layer of mouse and human intestines, whereas pan-specific Pmca antibodies detected Pmca1 in lateral membranes of enterocytes. In the kidney, Pmca4 showed broad localization to the distal nephron. In the mouse, expression was most abundant in segments coexpressing the epithelial ransient receptor potential vanilloid 5 Ca(2+) channel. Significant, albeit lower, expression was also evident in the region encompassing the cortical thick ascending limbs, macula densa, and early distal tubules as well as smooth muscle layers surrounding renal vessels. In the human kidney, a similar pattern of distribution was observed, with the highest PMCA4 expression in Na(+)-Cl(-) cotransporter-positive tubules. Electron microscopy demonstrated Pmca4 localization in distal nephron cells at both the basolateral membrane and intracellular perinuclear compartments but not submembranous vesicles, suggesting rapid trafficking to the plasma membrane is unlikely to occur in vivo. Pmca4 expression was not altered by perturbations in Ca(2+) balance, pointing to a housekeeping function of the pump in Ca(2+)-transporting epithelia. In conclusion, Pmca4 shows a divergent expression pattern in Ca(2+)-transporting epithelia, inferring diverse roles for this isoform not limited to transepithelial Ca(2+) transport. PMID:26180241

  8. Diffusion of Ca and Mg in Calcite

    SciTech Connect

    Cygan, R.T.; Fisler, D.K.

    1999-02-10

    The self-diffusion of Ca and the tracer diffusion of Mg in calcite have been experimentally measured using isotopic tracers of {sup 25}Mg and {sup 44}Ca. Natural single crystals of calcite were coated with a thermally-sputtered oxide thin film and then annealed in a CO{sub 2} gas at one atmosphere total pressure and temperatures from 550 to 800 C. Diffusion coefficient values were derived from the depth profiles obtained by ion microprobe analysis. The resultant activation energies for Mg tracer diffusion and Ca self-diffusion are respectively: E{sub a}(Mg) = 284 {+-} 74 kJ/mol and E{sub a}(Ca) = 271 {+-} 80 kJ/mol. For the temperature ranges in these experiments, the diffusion of Mg is faster than Ca. The results are generally consistent in magnitude with divalent cation diffusion rates obtained in previous studies and provide a means of interpreting the thermal histories of carbonate minerals, the mechanism of dolomitization, and other diffusion-controlled processes. The results indicate that cation diffusion in calcite is relatively slow and cations are the rate-limiting diffusing species for the deformation of calcite and carbonate rocks. Application of the calcite-dolomite geothermometer to metamorphic assemblages will be constrained by cation diffusion and cooling rates. The direct measurement of Mg tracer diffusion in calcite indicates that dolomitization is unlikely to be accomplished by Mg diffusion in the solid state but by a recrystallization process.

  9. CaF2:Yb laser ceramics

    NASA Astrophysics Data System (ADS)

    Akchurin, M. Sh.; Basiev, T. T.; Demidenko, A. A.; Doroshenko, M. E.; Fedorov, P. P.; Garibin, E. A.; Gusev, P. E.; Kuznetsov, S. V.; Krutov, M. A.; Mironov, I. A.; Osiko, V. V.; Popov, P. A.

    2013-01-01

    CaF2:Yb fluoride laser ceramics, prepared by hot-forming, exhibit the same optical properties as starting single crystals. Slope efficiency of the Сa0.95Yb0.05F2.05 is equal to 35% in the pulsed mode of laser operation. Decrease of ytterbium concentration in CaF2:Yb samples down to 3 mol.% resulted in the essential improvement of Сa0.97Yb0.03F2.03 thermal conductivity from 3.5 to 4.5 W/m K, but slightly decreased (down to 30%) slope efficiency of the samples under both pulsed and CW mode of operation. Alternative hot-pressing synthesis of CaF2:Yb fluoride laser ceramics provided materials with superior mechanical properties (microhardness Н = 3.2 GPa and fracture toughness К1С = 0.65 МPа m1/2) in comparison with hot-formed and/or single crystal CaF2:Yb specimens. For the first time, lasing has been observed for the novel aforementioned hot-pressed CaF2:Yb ceramics.

  10. Ca2+ signaling during vertebrate somitogenesis.

    PubMed

    Webb, Sarah E; Miller, Andrew L

    2006-07-01

    A variety of Ca2+ signals, in the form of intercellular pulses and waves, have been reported to be associated with the various sequential stages of somitogenesis: from convergent extension and the formation of the paraxial mesoderm; during the patterning of the paraxial mesoderm to establish segmental units; throughout the formation of the morphological boundaries that delineate the segmental units, and finally from within the maturing somites as they undergo subsequent development and differentiation. Due to both the technical challenges presented in imaging intact, developing embryos, and the subtle nature of the Ca2+ transients generated, they have proved to be difficult to visualize. However, a combination of cultured cell preparations and improvements in explant and whole embryo imaging techniques has begun to reveal a new and exciting class of developmental Ca2+ signals. In this chapter, we review the small, but expanding, number of reports in the literature and attempt to identify common characteristics of the somitogenic Ca2+ transients, such as their mode of generation, as well as their spatial and temporal features. This may help to elucidate the significance and function of these intriguing Ca2+ transients and thus integrate them into the complex signaling networks that orchestrate early developmental events. PMID:16787560

  11. Control of ciliary motility by Ca sup 2+ : Integration of Ca sup 2+ -dependent functions and targets for Ca sup 2+ action

    SciTech Connect

    Evans, T.C.

    1988-01-01

    To identify functions that regulate Ca{sup 2+}-induced ciliary reversal in Paramecium, mutants defective in terminating depolarization-induced backward swimming were selected. Six independent recessive mutations (k-shy) comprising two complementation groups, k-shyA and k-shyB, were identified. All mutants exhibited prolonged backward swimming in depolarizing solutions. Voltage clamp studies revealed that mutant Ca{sup 2+} current amplitudes were reduced, but could be restored to wild type levels by EGTA injection. The recovery of the mutant Ca{sup 2+} current from Ca{sup 2+}-dependent inactivation, and the decay of the Ca{sup 2+}-dependent K{sup +} and Ca{sup 2+}-dependent Na{sup +} currents after depolarization were slow in k-shy compared to wild type. To identify protein targets of Ca{sup 2+} action, ciliary proteins that interact with calmodulin (CaM) were characterized. With a {sup 125}I-CaM blot assay, several CaM-binding proteins were identified including axonemal, soluble, and membrane-bound polypeptides. Competitive displacement studies with unlabeled Paramecium CaM, bovine CaM, and troponinC suggested that both protein types bind CaM with high affinity and specificity. To examine the presence of CaM-binding sites in intact axonemes, a filtration binding assay was developed.

  12. Stability relations in the system CaSiO3-CaMnSi2O6-CaFeSi2O6

    NASA Astrophysics Data System (ADS)

    Abrecht, Jürgen

    1980-10-01

    In the system CaSiO3-CaMnSi2O6-CaFeSi2O6 extensive miscibility gaps between pyroxenoids and clinopyroxenes are observed. The miscibility gap between Mn-bustamite and Mn-wollastonite has been determined experimentally by a hydrothermal technique between 400° and 1200° C at P f= 2 kbar. Further experiments have been performed at P f=9 kbar, which revealed a shifting of the miscibility gap towards more Ca-rich compositions. The bustamite phase is stabilized by high pressures and the wollastonite structure is the stable phase at high temperatures. Similar phase relations as along the join CaSiO3-CaMnSi2O6 exist along the join CaSiO3-CaFeSi2O6 but with a more extensive two-phase field of bustamite-clinopyroxene. Possible phase relations along the joins CaSiO3-CaMnSi2O6, CaSiO3-CaFeSi2O6 and CaFeSi2O6-CaMnSi2O6 are given in temperature-composition diagrams for low pressures, based on natural and experimental data.

  13. Modeling the contributions of Ca2+ flows to spontaneous Ca2+ oscillations and cortical spreading depression-triggered Ca2+ waves in astrocyte networks.

    PubMed

    Li, Bing; Chen, Shangbin; Zeng, Shaoqun; Luo, Qingming; Li, Pengcheng

    2012-01-01

    Astrocytes participate in brain functions through Ca(2+) signals, including Ca(2+) waves and Ca(2+) oscillations. Currently the mechanisms of Ca(2+) signals in astrocytes are not fully clear. Here, we present a computational model to specify the relative contributions of different Ca(2+) flows between the extracellular space, the cytoplasm and the endoplasmic reticulum of astrocytes to the generation of spontaneous Ca(2+) oscillations (CASs) and cortical spreading depression (CSD)-triggered Ca(2+) waves (CSDCWs) in a one-dimensional astrocyte network. This model shows that CASs depend primarily on Ca(2+) released from internal stores of astrocytes, and CSDCWs depend mainly on voltage-gated Ca(2+) influx. It predicts that voltage-gated Ca(2+) influx is able to generate Ca(2+) waves during the process of CSD even after depleting internal Ca(2+) stores. Furthermore, the model investigates the interactions between CASs and CSDCWs and shows that the pass of CSDCWs suppresses CASs, whereas CASs do not prevent the generation of CSDCWs. This work quantitatively analyzes the generation of astrocytic Ca(2+) signals and indicates different mechanisms underlying CSDCWs and non-CSDCWs. Research on the different types of Ca(2+) signals might help to understand the ways by which astrocytes participate in information processing in brain functions.

  14. Method comparison for CA 15-3, CA 19-9, and CA 125 determination using the new LOCI technique of Dimension Vista 1500 and Immulite 2000 XPI.

    PubMed

    Zur, Berndt; Holdenrieder, Stefan; Albers, Eike; Walgenbach-Brünagel, Gisela; Stoffel-Wagner, Birgit

    2012-01-01

    We performed method comparison for the tumor markers CA 15-3, CA 19-9, and CA 125 measured by luminescent oxygen channeling immunoassay technology on the Dimension Vista 1500 and by classic luminescence technology on the Immulite 2000 XPI. Within-day and total imprecision were determined according to Clinical and Laboratory Standards Institute (CLSI) guidelines using three serum pools at different clinically relevant levels. In addition, parallel measurements on both systems were performed in a total of 738 routine serum samples (133 CA 15-3, 395 CA 19-9, and 210 CA 125). Total imprecision of serum pools for CA 15-3 ranged between 4.6% and 5.9%, for CA 19-9 between 4.4% and 7.8%, and for CA 125 between 3.3% and 4.3%. Marker values determined within the measurement range of both systems correlated well with each other (R = 0.88 for CA 15-3, R = 0.93 for CA 19-9, and R = 0.96 for CA 125). Slopes between the Vista and the Immulite method were 0.96 for CA 125, 0.72 for CA 15-3, and 0.87 for CA 19-9, indicating lower values for CA 15-3 and CA 19-9 when measured by the Vista method. This was particularly obvious for CA 19-9 levels in the lower measuring range of <100 U/mL (R = 0.85; slope 0.73).

  15. Sulfide capacity of CaO-CaF2-SiO2 slags

    NASA Astrophysics Data System (ADS)

    Susaki, Katsujiro; Maeda, Masafumi; Sano, Nobuo

    1990-02-01

    The sulfide capacity C S 2- = (pct S2-) · ( P O 2/ P S 2)1/2) of CaO-CaF2-SiO2 slags saturated with CaO, 3CaO · SiO2 or 2CaOSiO2 was determined at 1200 °C, 1250 °C, 1300 °C, and 1350 °C by equilibrating molten slag, molten silver, and CO-CO2 gas mixtures. Higher sulfide capacities were obtained for CaO-saturated slags. A drastic decrease was observed in those values when the ratio pct CaO/pct SiO2 is less than 2. The sulfur partition between carbon-saturated iron melts and presently investigated slags was calculated by using the sulfide capacities obtained and the activity coefficient of sulfur in carbon-saturated iron, which was also experimentally determined. For slags saturated with CaO, partitions of sulfur as high as 10,000 were obtained at 1300 °C and 1350 °C. Correlations between the sulfide capacity and other basicity indexes such as carbonate capacity and theoretical optical basicity were also discussed.

  16. Multifaceted plasma membrane Ca(2+) pumps: From structure to intracellular Ca(2+) handling and cancer.

    PubMed

    Padányi, Rita; Pászty, Katalin; Hegedűs, Luca; Varga, Karolina; Papp, Béla; Penniston, John T; Enyedi, Ágnes

    2016-06-01

    Plasma membrane Ca(2+) ATPases (PMCAs) are intimately involved in the control of intracellular Ca(2+) concentration. They reduce Ca(2+) in the cytosol not only by direct ejection, but also by controlling the formation of inositol-1,4,5-trisphosphate and decreasing Ca(2+) release from the endoplasmic reticulum Ca(2+) pool. In mammals four genes (PMCA1-4) are expressed, and alternative RNA splicing generates more than twenty variants. The variants differ in their regulatory characteristics. They localize into highly specialized membrane compartments and respond to the incoming Ca(2+) with distinct temporal resolution. The expression pattern of variants depends on cell type; a change in this pattern can result in perturbed Ca(2+) homeostasis and thus altered cell function. Indeed, PMCAs undergo remarkable changes in their expression pattern during tumorigenesis that might significantly contribute to the unbalanced Ca(2+) homeostasis of cancer cells. This article is part of a Special Issue entitled: Calcium and Cell Fate. Guest Editors: Jacques Haiech, Claus Heizmann, Joachim Krebs, Thierry Capiod and Olivier Mignen. PMID:26707182

  17. Intercellular Ca2+ Waves: Mechanisms and Function

    PubMed Central

    Sanderson, Michael J.

    2012-01-01

    Intercellular calcium (Ca2+) waves (ICWs) represent the propagation of increases in intracellular Ca2+ through a syncytium of cells and appear to be a fundamental mechanism for coordinating multicellular responses. ICWs occur in a wide diversity of cells and have been extensively studied in vitro. More recent studies focus on ICWs in vivo. ICWs are triggered by a variety of stimuli and involve the release of Ca2+ from internal stores. The propagation of ICWs predominately involves cell communication with internal messengers moving via gap junctions or extracellular messengers mediating paracrine signaling. ICWs appear to be important in both normal physiology as well as pathophysiological processes in a variety of organs and tissues including brain, liver, retina, cochlea, and vascular tissue. We review here the mechanisms of initiation and propagation of ICWs, the key intra- and extracellular messengers (inositol 1,4,5-trisphosphate and ATP) mediating ICWs, and the proposed physiological functions of ICWs. PMID:22811430

  18. Ca3Mn2O7.

    PubMed

    Guiblin, Nicolas; Grebille, Dominique; Leligny, Henri; Martin, Christine

    2002-01-01

    The tricalcium dimanganese heptaoxide (Ca3Mn2O7) member of the Ruddlesden-Popper series Ca(n+1)Mn(n)O(3n+1), i.e. with n = 2, was previously reported with an I-centred tetragonal lattice [a(t) = 3.68 and c(t) = 19.57 A] by Fawcett, Sunstrom, Greenblatt, Croft & Ramanujachary [Chem. Mater. (1998), 10, 3643-3651]. It is now found to be orthorhombic, with an A-centred lattice [a = 5.2347 (6), b = 5.2421 (2) and c = 19.4177 (19) A]. The structure has been refined in space group A2(1)am using X-ray single-crystal diffraction data and assuming the existence of twin domains related by the (1-10) plane. A comparison with the basic perovskite structure CaMnO3 (n = infinity) is proposed.

  19. Characterizing CA{sub 2} and CA{sub 6} using ELNES

    SciTech Connect

    Altay, A.; Carter, C.B.; Rulis, P.; Ching, W.-Y.; Arslan, I.; Guelguen, M.A.

    2010-08-15

    Calcium aluminates, compounds in the CaO-Al{sub 2}O{sub 3} phase system, are used in high-temperature cements and refractory oxides and have wide range of potential technological applications due to their interesting optical, electrical, thermal, and mechanical properties. They are used in both crystalline and glassy form; the glass is an isotropic material while the crystalline materials may be highly anisotropic. This paper will consider two particular crystalline materials, CA{sub 2} and CA{sub 6}, but the results should be applicable to all calcium aluminates. Although CA{sub 2} and CA{sub 6} crystals contain the same chemical species, Ca, Al, and O, the coordination and local environments of these species are different in the two structures and hence they show very different energy-loss near-edge structures (ELNES) when examined by electron energy-loss spectroscopy (EELS) in the TEM. The data obtained using ELNES can effectively provide a fingerprint for each compound and a map for their electronic structure. Once such fingerprints are obtained, they can be used to identify nano-sized particles/grains or material at interfaces and grain boundaries. In the present study, the local symmetry fingerprints for CA{sub 2} and CA{sub 6} structures are reported combining experimental spectra with electronic-structure calculations that allow the different features in the spectra to be interpreted. Al-L{sub 2,3} and O-K edge core-loss spectra from CA{sub 2} and CA{sub 6} were measured experimentally using electron energy-loss spectroscopy in a monochromated scanning transmission electron microscope. The near-edge structures were calculated for the different phases using the orthogonalized linear combination of atomic-orbitals method, and took account of core-hole interactions. It is shown that CA{sub 2} and CA{sub 6} structures exhibit distinctive experimental ELNES fingerprints so that these two phases can be separately identified even when present in small volumes

  20. IP3R, store-operated Ca2+ entry and neuronal Ca2+ homoeostasis in Drosophila.

    PubMed

    Chakraborty, Sumita; Hasan, Gaiti

    2012-02-01

    The IP3R (inositol 1,4,5-trisphosphate receptor) releases Ca2+ from the ER (endoplasmic reticulum) store upon binding to its ligand InsP3, which is thought to be generated by activation of certain membrane-bound G-protein-coupled receptors in Drosophila. Depletion of Ca2+ in the ER store also activates SOCE (store-operated Ca2+ entry) from the extracellular milieu across the plasma membrane, leading to a second rise in cytosolic Ca2+, which is then pumped back into the ER. The role of the IP3R and SOCE in mediating Ca2+ homoeostasis in neurons, their requirement in neuronal function and effect on neuronal physiology and as a consequence behaviour, are reviewed in the present article.

  1. Characterization of materials for Ca/CaCrO4 thermal batteries

    NASA Astrophysics Data System (ADS)

    Guidotti, R. A.; Reinhardt, F. W.; Poole, R. L.

    The performance of pelletized Ca/CaCrO4 thermal batteries is known to be sensitive to processing of the catholyte or DEB mix, which consists of CaCrO4 depolarized(D), KCl-LiCl eutectic electrolyte(E), and SiO2 binder(B). The chemical composition of the DEB mix affects the electrochemical behavior. Little work has been reported, however, for the characterization of DEB mixes in relation to their performance in Ca/CaCrO4 thermal batteries. Considerable variability of battery performance has also been observed when different lots of sheet calcium are used with the same DEB. The causes for this behavior remain elusive. In an effort to resolve these discrepancies in materials behavior, a study was carried out to characterize DEB powders and pellets and, to a lesser extent, sheet calcium with the primary objective of correlating observed battery performance to easily measured physical and chemical properties.

  2. Characterization of cathodic corrosion products in the Ca/CaCrO/sub 4/ thermal battery

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.; Venturini, E.L.; Rogers, J.W. Jr.; Cathey, W.N.

    1985-05-01

    Using thermal analysis techniques, we investigated the corrosion process resulting from the reaction of iron, nickel, and stainless steel (used as current collectors in Ca/CaCrO/sub 4/ thermal batteries) with CaCrO/sub 4/ dissolved in LiCl-KCl eutectic. The reaction product for iron was synthesized in bulk external to the battery and was characterized by chemical analysis, X-ray diffraction, Moessbauer spectroscopy, X-ray photoelectron spectroscopy, static magnetization, and electrical conductivity. This characterization provides a better understanding of the cathodic corrosion processes that occur in the Ca/CaCrO/sub 4/ thermal battery, and how the properties of the reaction layer at the catholyte-current collector interface influence battery performance.

  3. Characterization of cathodic corrosion products in the Ca/CaCrO4 thermal battery

    NASA Astrophysics Data System (ADS)

    Guidotti, R. A.; Reinhardt, F. W.; Venturini, E. L.; Rogers, J. W., Jr.; Cathey, W. N.

    1985-05-01

    Using thermal analysis techniques, the corrosion process resulting from the reaction of iron, nickel, and stainless steel (used as current collectors in Ca/CaCrO4 thermal batteries) with CaCrO4 dissolved in LiCl-KCl eutectic was investigated. The reaction product for iron was synthesized in bulk external to the battery and was characterized by chemical analysis, X-ray diffraction, Moessbauer spectroscopy, X-ray photoelectron spectroscopy, static magnetization, and electrical conductivity. This characterization provides a better understanding of the cathodic corrosion processes that occur in the Ca/CaCrO4 thermal battery, and how the properties of the reaction layer at the catholyte-current collector interface influence battery performance.

  4. Ca2+-induced Ca2+ Release in Chromaffin Cells Seen from inside the ER with Targeted Aequorin

    PubMed Central

    Alonso, Maria Teresa; Barrero, Maria José; Michelena, Pedro; Carnicero, Estela; Cuchillo, Inmaculada; García, Antonio G.; García-Sancho, Javier; Montero, Mayte; Alvarez, Javier

    1999-01-01

    The presence and physiological role of Ca2+-induced Ca2+ release (CICR) in nonmuscle excitable cells has been investigated only indirectly through measurements of cytosolic [Ca2+] ([Ca2+]c). Using targeted aequorin, we have directly monitored [Ca2+] changes inside the ER ([Ca2+]ER) in bovine adrenal chromaffin cells. Ca2+ entry induced by cell depolarization triggered a transient Ca2+ release from the ER that was highly dependent on [Ca2+]ER and sensitized by low concentrations of caffeine. Caffeine-induced Ca2+ release was quantal in nature due to modulation by [Ca2+]ER. Whereas caffeine released essentially all the Ca2+ from the ER, inositol 1,4,5-trisphosphate (InsP3)- producing agonists released only 60–80%. Both InsP3 and caffeine emptied completely the ER in digitonin-permeabilized cells whereas cyclic ADP-ribose had no effect. Ryanodine induced permanent emptying of the Ca2+ stores in a use-dependent manner after activation by caffeine. Fast confocal [Ca2+]c measurements showed that the wave of [Ca2+]c induced by 100-ms depolarizing pulses in voltage-clamped cells was delayed and reduced in intensity in ryanodine-treated cells. Our results indicate that the ER of chromaffin cells behaves mostly as a single homogeneous thapsigargin-sensitive Ca2+ pool that can release Ca2+ both via InsP3 receptors or CICR. PMID:9922451

  5. Kinetic studies of Ca2+ binding and Ca2+ clearance in the cytosol of adrenal chromaffin cells.

    PubMed Central

    Xu, T; Naraghi, M; Kang, H; Neher, E

    1997-01-01

    The Ca2+ binding kinetics of fura-2, DM-nitrophen, and the endogenous Ca2+ buffer, which determine the time course of Ca2+ changes after photolysis of DM-nitrophen, were studied in bovine chromaffin cells. The in vivo Ca2+ association rate constants of fura-2, DM-nitrophen, and the endogenous Ca2+ buffer were measured to be 5.17 x 10(8) M-1 s-1, 3.5 x 10(7) M-1 s-1, and 1.07 x 10(8) M-1 s-1, respectively. The endogenous Ca2+ buffer appeared to have a low affinity for Ca2+ with a dissociation constant around 100 microM. A fast Ca2+ uptake mechanism was also found to play a dominant role in the clearance of Ca2+ after flashes at high intracellular free Ca2+ concentrations ([Ca2+]), causing a fast [Ca2+]i decay within seconds. This Ca2+ clearance was identified as mitochondrial Ca2+ uptake. Its uptake kinetics were studied by analyzing the Ca2+ decay at high [Ca2+]i after flash photolysis of DM-nitrophen. The capacity of the mitochondrial uptake corresponds to a total cytosolic Ca2+ load of approximately 1 mM. Images FIGURE 2 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 8 PMID:9199815

  6. Anoxia-induced elevation of cytosolic Ca2+ concentration depends on different Ca2+ sources in rice and wheat protoplasts.

    PubMed

    Yemelyanov, Vladislav V; Shishova, Maria F; Chirkova, Tamara V; Lindberg, Sylvia M

    2011-08-01

    The anoxia-dependent elevation of cytosolic Ca(2+) concentration, [Ca(2+)](cyt), was investigated in plants differing in tolerance to hypoxia. The [Ca(2+)](cyt) was measured by fluorescence microscopy in single protoplasts loaded with the calcium-fluoroprobe Fura 2-AM. Imposition of anoxia led to a fast (within 3 min) significant elevation of [Ca(2+)](cyt) in rice leaf protoplasts. A tenfold drop in the external Ca(2+) concentration (to 0.1 mM) resulted in considerable decrease of the [Ca(2+)](cyt) shift. Rice root protoplasts reacted upon anoxia with higher amplitude. Addition of plasma membrane (verapamil, La(3+) and EGTA) and intracellular membrane Ca(2+)-channel antagonists (Li(+), ruthenium red and cyclosporine A) reduced the anoxic Ca(2+)-accumulation in rice. Wheat protoplasts responded to anoxia by smaller changes of [Ca(2+)](cyt). In wheat leaf protoplasts, the amplitude of the Ca(2+)-shift little depended on the external level of Ca(2+). Wheat root protoplasts were characterized by a small shift of [Ca(2+)](cyt) under anoxia. Plasmalemma Ca(2+)-channel blockers had little effect on the elevation of cytosolic Ca(2+) in wheat protoplasts. Intact rice seedlings absorbed Ca(2+) from the external medium under anoxic treatment. On the contrary, wheat seedlings were characterized by leakage of Ca(2+). Verapamil abolished the Ca(2+) influx in rice roots and Ca(2+) efflux from wheat roots. Anoxia-induced [Ca(2+)](cyt) elevation was high particularly in rice, a hypoxia-tolerant species. In conclusion, both external and internal Ca(2+) stores are important for anoxic [Ca(2+)](cyt) elevation in rice, whereas the hypoxia-intolerant wheat does not require external sources for [Ca(2+)](cyt) rise. Leaf and root protoplasts similarly responded to anoxia, independent of their organ origin.

  7. Materials compatibility during the chlorination of molten CaCl/sub 2/. CaO salts. [CaCl/sub 2/. CaO salt

    SciTech Connect

    Rense, C.E.C.; Fife, K.W.; Bowersox, D.F.; Ferran, M.D.

    1987-01-01

    As part of our effort to develop a semicontinuous PuO/sub 2/ reduction process, we are investigating promising materials for containing a 900/sup 0/C molten CaCl/sub 2/ . CaO chlorination reaction. We want the material to contain this reaction and to be reusable. We tested candidate materials in a simulated salt (no plutonium) using anhydrous HCl as the chlorinating agent. Data are presented on the performance of 36 metals and alloys, 9 ceramics, and 3 coatings.

  8. Novel antimigraineur dotarizine releases Ca2+ from caffeine-sensitive Ca2+ stores of chromaffin cells

    PubMed Central

    Novalbos, Jesús; Abad-Santos, Francisco; Zapater, Pedro; Alvarez, Javier; Alonso, María Teresa; Montero, Mayte; García, Antonio G

    1999-01-01

    The novel antimigraineur, dotarizine (30 μM), increased cytosolic Ca2+ concentration, [Ca2+]c, in fura-2-loaded bovine adrenal chromaffin cells. This increase was transient, reached a peak in about 2–5 min (0.53±0.07 μM; n=19) and then declined to basal levels over a further 5 min period.This transient rise of [Ca2+]c was mimicked by 1 μM thapsigargin and by 30 μM cyclopiazonic acid (CPA), but not by 30 μM flunarizine. Both thapsigargin and CPA occluded the effects of dotarizine and vice versa.All three compounds suppressed the transient [Ca2+]c rises induced by caffeine (10 mM, 10 s); blockade induced by thapsigargin was irreversible and that induced by CPA and dotarizine was reversible.Of the three compounds, only dotarizine blocked reversibly the [Ca2+]c spikes induced by short pulses of high K+ (70 mM, 5 s), suggesting that dotarizine blocks voltage-dependent Ca2+ channels but CPA and thapsigargin do not.Dotarizine caused a gradual and reversible depletion of endoplasmic reticulum (ER) Ca2+ in chromaffin cells transfected with ER-targeted aequorin. CPA had a similar effect.These data show that dotarizine shares with thapsigargin and CPA the ability to deplete Ca2+ in the ER; this novel action of dotarizine could be relevant to its prophylactic effects in migraine. Unlike thapsigargin and CPA, however, dotarizine additionally and reversibly blocks Ca2+ entry through voltage-dependent Ca2+ channels. PMID:10516641

  9. Growth rate effects on Mg/Ca and Sr/Ca ratios constrained by belemnite calcite

    NASA Astrophysics Data System (ADS)

    Vinzenz Ullmann, Clemens

    2016-04-01

    Multiple temperature proxies from single species are important to achieve robust palaeotemperature estimates. Besides the commonly employed oxygen isotope thermometer, also Mg/Ca and Sr/Ca ratios perform well as proxies for calcification temperature in the shells of some species. While salinity changes affect the ratios of earth alkaline elements much less than the δ18O thermometer, metabolic effects may exert a strong control on the expression of element ratios. Such effects are hard to study because biomineralization experiments have to overcome large intraspecific variability and can hardly ever isolate the controls of a single parameter on shell geochemistry. The unique geometry of the belemnite rostrum constitutes an exception to this rule. Its shape, large size, and the visibility of growth increments as bands enable the analysis of multiple, correlatable, high resolution geochemical profiles in a single fossil. The effects of the growth rate variability amongst these profiles on Mg/Ca and Sr/Ca ratios has been tested here. Within a specimen of Passaloteuthis bisulcata (Early Toarcian, Cleveland Basin, UK), Mg/Ca and Sr/Ca data were obtained from four profiles. With respect to growth rate in the first profile, which was taken as a reference, the relative growth rates in the remaining three profiles varied by a factor of 0.9 to 2.7. Results suggest that relative growth rate is linearly correlated with Mg/Ca and Sr/Ca, with a decrease of Mg/Ca by 8 % and increase of Sr/Ca by 6 % per 100 % increase in relative growth rate. The observed trends are consistent with abiogenic precipitation experiments and suggest that crystal precipitation rate exerts a significant, predictable control on the element distribution in biogenic calcite.

  10. Cardiac microvascular endothelial cells express a functional Ca+ -sensing receptor.

    PubMed

    Berra Romani, Roberto; Raqeeb, Abdul; Laforenza, Umberto; Scaffino, Manuela Federica; Moccia, Francesco; Avelino-Cruz, Josè Everardo; Oldani, Amanda; Coltrini, Daniela; Milesi, Veronica; Taglietti, Vanni; Tanzi, Franco

    2009-01-01

    The mechanism whereby extracellular Ca(2+) exerts the endothelium-dependent control of vascular tone is still unclear. In this study, we assessed whether cardiac microvascular endothelial cells (CMEC) express a functional extracellular Ca(2+)-sensing receptor (CaSR) using a variety of techniques. CaSR mRNA was detected using RT-PCR, and CaSR protein was identified by immunocytochemical analysis. In order to assess the functionality of the receptor, CMEC were loaded with the Ca(2+)-sensitive fluorochrome, Fura-2/AM. A number of CaSR agonists, such as spermine, Gd(3+), La(3+) and neomycin, elicited a heterogeneous intracellular Ca(2+) signal, which was abolished by disruption of inositol 1,4,5-trisphosphate (InsP(3)) signaling and by depletion of intracellular stores with cyclopiazonic acid. The inhibition of the Na(+)/Ca(2+) exchanger upon substitution of extracellular Na(+) unmasked the Ca(2+) signal triggered by an increase in extracellular Ca(2+) levels. Finally, aromatic amino acids, which function as allosteric activators of CaSR, potentiated the Ca(2+) response to the CaSR agonist La(3+). These data provide evidence that CMEC express CaSR, which is able to respond to physiological agonists by mobilizing Ca(2+) from intracellular InsP(3)-sensitive stores.

  11. Mitochondrial Ca(2+) uptake in skeletal muscle health and disease.

    PubMed

    Zhou, Jingsong; Dhakal, Kamal; Yi, Jianxun

    2016-08-01

    Muscle uses Ca(2+) as a messenger to control contraction and relies on ATP to maintain the intracellular Ca(2+) homeostasis. Mitochondria are the major sub-cellular organelle of ATP production. With a negative inner membrane potential, mitochondria take up Ca(2+) from their surroundings, a process called mitochondrial Ca(2+) uptake. Under physiological conditions, Ca(2+) uptake into mitochondria promotes ATP production. Excessive uptake causes mitochondrial Ca(2+) overload, which activates downstream adverse responses leading to cell dysfunction. Moreover, mitochondrial Ca(2+) uptake could shape spatio-temporal patterns of intracellular Ca(2+) signaling. Malfunction of mitochondrial Ca(2+) uptake is implicated in muscle degeneration. Unlike non-excitable cells, mitochondria in muscle cells experience dramatic changes of intracellular Ca(2+) levels. Besides the sudden elevation of Ca(2+) level induced by action potentials, Ca(2+) transients in muscle cells can be as short as a few milliseconds during a single twitch or as long as minutes during tetanic contraction, which raises the question whether mitochondrial Ca(2+) uptake is fast and big enough to shape intracellular Ca(2+) signaling during excitation-contraction coupling and creates technical challenges for quantification of the dynamic changes of Ca(2+) inside mitochondria. This review focuses on characterization of mitochondrial Ca(2+) uptake in skeletal muscle and its role in muscle physiology and diseases. PMID:27430885

  12. Gonadotropin-releasing hormone-induced Ca2+ transients in single identified gonadotropes require both intracellular Ca2+ mobilization and Ca2+ influx.

    PubMed Central

    Shangold, G A; Murphy, S N; Miller, R J

    1988-01-01

    We examined the effects of gonadotropin-releasing hormone (GnRH) on the intracellular free Ca2+ concentration ([Ca2+]i) in single rat anterior pituitary gonadotropes identified by a reverse hemolytic plaque assay. Concentrations of GnRH greater than 10 pM elicited increases in [Ca2+]i in identified cells but not in others. In contrast, depolarization induced by 50 mM K+ increased [Ca2+]i in all cells. Ca2+ transients induced by GnRH exhibited a complex time course. After an initial rapid rise, the [Ca2+]i fell to near basal levels only to be followed by a secondary extended rise and fall. Analysis of the Ca2+ transients on a rapid time base revealed that responses frequently consisted of several rapid oscillations in [Ca2+]i. Removal of extracellular Ca2+ or addition of the dihydropyridine Ca2+-channel blocker nitrendipine completely blocked the secondary rise in [Ca2+]i but had no effect whatsoever on the initial spike. Nitrendipine also blocked 50 mM K+-induced increases in [Ca2+]i in identified gonadotropes. The secondary rise induced by GnRH could be enhanced by a phorbol ester in a nitrendipine-sensitive fashion. Multiple spike responses to GnRH stimulation of the same cell could only be obtained if subsequent Ca2+ influx was permitted either by allowing a secondary rise to occur or by producing a Ca2+ transient by depolarizing the cells with 50 mM K+. It therefore appears that the response to GnRH consists of an initial phase of Ca2+ mobilization, probably mediated by inositol trisphosphate, and a subsequent phase of Ca2+ influx through nitrendipine-sensitive Ca2+ channels that may be activated by protein kinase C. The relative roles of these phases in the control of gonadotropin secretion are discussed. Images PMID:3045819

  13. Inhibitors of the Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase family (CaMKP and CaMKP-N)

    SciTech Connect

    Sueyoshi, Noriyuki; Takao, Toshihiko; Nimura, Takaki; Sugiyama, Yasunori; Numano, Takamasa; Shigeri, Yasushi; Taniguchi, Takanobu; Kameshita, Isamu Ishida, Atsuhiko

    2007-11-23

    Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP) and its nuclear isoform CaMKP-N are unique Ser/Thr protein phosphatases that negatively regulate the Ca{sup 2+}/calmodulin-dependent protein kinase (CaMK) cascade by dephosphorylating multifunctional CaMKI, II, and IV. However, the lack of specific inhibitors of these phosphatases has hampered studies on these enzymes in vivo. In an attempt to obtain specific inhibitors, we searched inhibitory compounds and found that Evans Blue and Chicago Sky Blue 6B served as effective inhibitors for CaMKP. These compounds also inhibited CaMKP-N, but inhibited neither protein phosphatase 2C, another member of PPM family phosphatase, nor calcineurin, a typical PPP family phosphatase. The minimum structure required for the inhibition was 1-amino-8-naphthol-4-sulfonic acid. When Neuro2a cells cotransfected with CaMKIV and CaMKP-N were treated with these compounds, the dephosphorylation of CaMKIV was strongly suppressed, suggesting that these compounds could be used as potent inhibitors of CaMKP and CaMKP-N in vivo as well as in vitro.

  14. Effects of glucagon and vasopressin on hepatic Ca2+ release.

    PubMed Central

    Kraus-Friedmann, N

    1986-01-01

    The effects of physiological levels of glucagon on Ca2+ efflux were examined in the perfused rat liver. Two methods were used to estimate Ca2+ efflux: prior labeling of the calcium pools with 45Ca2+ and measurement of perfusate Ca2+ with atomic absorption. According to both methods, glucagon administration at the physiological level evoked Ca2+ release. The released Ca2+ originated mostly from a carbonylcyanide p-trifluoromethoxyphenylhydrazone (FCCP)-depletable pool and also from an FCCP-insensitive pool from which Ca2+ could be released with A23187. Maximally effective doses of glucagon and vasopressin had no additive effect on Ca2+ release. Prior administration of vasopressin resulted in markedly reduced Ca2+ release by glucagon. These results indicate that glucagon releases Ca2+ from the same pool that vasopressin does. PMID:3466169

  15. L-type Ca2+ channels serve as a sensor of the SR Ca2+ for tuning the efficacy of Ca2+-induced Ca2+ release in rat ventricular myocytes

    PubMed Central

    Takamatsu, Hajime; Nagao, Taku; Ichijo, Hidenori; Adachi-Akahane, Satomi

    2003-01-01

    In cardiac excitation-contraction coupling, Ca2+-induced Ca2+ release (CICR) from ryanodine receptors (RyRs), triggered by Ca2+ entry through the nearby L-type Ca2+ channel, induces Ca2+-dependent inactivation (CDI) of the Ca2+ channel. Aiming at elucidating the physiological role of CDI produced by CICR (CICR-dependent CDI), we investigated the contribution of the CICR-dependent CDI to action potential (AP) waveform and the amount of Ca2+-influx through Ca2+ channels during AP in rat ventricular myocytes. The elimination of the CICR-dependent CDI, by depletion of the SR Ca2+ with thapsigargin, significantly prolonged AP duration (APD). APD changed in parallel with the magnitude of CICR during the recovery of the SR Ca2+ content after transient depletion by caffeine. Such CICR-dependent change of APD persisted under the highly Ca2+ buffered condition where the Ca2+ signalling was restricted to nanoscale domains. Blockers of the Ca2+-dependent Cl− channel or the BK channel did not affect AP waveform. The amount of Ca2+-influx through Ca2+ channels during the SR-depleted type AP waveform, measured in the SR-depleted myocyte, was increased by 40% over that during the SR-intact type AP waveform measured in the SR-intact myocyte. The protein kinase A stimulation further enhanced the Ca2+-influx during AP under the SR-depleted condition to 70% of that under the SR-intact condition. These results indicate that the CICR-dependent CDI of L-type Ca2+ channels, under control of the privileged cross-signalling between L-type Ca2+ channels and RyRs, play important roles for monitoring and tuning the SR Ca2+ content via changes of AP waveform and the amount of Ca2+-influx during AP in ventricular myocytes. PMID:14561825

  16. Detection of Ca(2+)-binding proteins by electrophoretic migration in the presence of Ca2+ combined with 45Ca2+ overlay of protein blots

    SciTech Connect

    Garrigos, M.; Deschamps, S.; Viel, A.; Lund, S.; Champeil, P.; Moller, J.V.; le Maire, M. , Gif-sur-Yvette )

    1991-04-01

    When high affinity Ca(2+)-binding proteins like calmodulin, or proteins with a high Ca(2+)-binding capacity like calsequestrin, underwent sodium dodecyl sulfate-gel electrophoresis in Laemmli systems, their electrophoretic migration rates were much higher in gels containing 1 mM Ca2+ than in gels containing ethylene glycol bis(beta-aminoethyl ether) N,N{prime}-tetraacetic acid (EGTA). Replacement of EGTA by Ca2+ in the gel, combined with the blotting of electrophoretically separated proteins on polyvinylidene difluoride membranes and subsequent 45Ca2+ overlay, proved a very effective means of detecting Ca(2+)-binding proteins. This combined approach is important since artifacts occur in both techniques when used separately. We found that the usual procedure of adding Ca2+ to the sample before electrophoresis without including it in the gel itself permitted the detection of only very high affinity Ca(2+)-binding proteins.

  17. 78 FR 60366 - California Disaster #CA-00212

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-10-01

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION California Disaster CA-00212 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY...: 06/24/2014. ADDRESSES: Submit completed loan applications to: U.S. Small Business...

  18. 77 FR 58901 - California Disaster #CA-00190

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... From the Federal Register Online via the Government Publishing Office SMALL BUSINESS ADMINISTRATION California Disaster CA-00190 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY... Application Deadline Date: 06/14/2013. ADDRESSES: Submit completed loan applications to: U.S. Small...

  19. SNL/CA Cultural Resources Management Plan.

    SciTech Connect

    Larsen, Barbara L.

    2005-11-01

    The SNL/CA Cultural Resources Management Plan satisfies the site's Environmental Management System requirement to promote long-term stewardship of cultural resources. The plan summarizes the cultural and historical setting of the site, identifies existing procedures and processes that support protection and preservation of resources, and outlines actions that would be initiated if cultural resources were discovered onsite in the future.3

  20. 78 FR 39821 - California Disaster #CA-00202

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-02

    ... ADMINISTRATION California Disaster CA-00202 AGENCY: U.S. Small Business Administration. ACTION: Notice. SUMMARY: This is a notice of an Administrative declaration of a disaster for the State of California dated 06/25... INFORMATION CONTACT: A. Escobar, Office of Disaster Assistance, U.S. Small Business Administration, 409...

  1. Hippocampal CA1 Ripples as Inhibitory Transients

    PubMed Central

    Krishnan, Giri P; Fellous, Jean-Marc; Bazhenov, Maxim

    2016-01-01

    Memories are stored and consolidated as a result of a dialogue between the hippocampus and cortex during sleep. Neurons active during behavior reactivate in both structures during sleep, in conjunction with characteristic brain oscillations that may form the neural substrate of memory consolidation. In the hippocampus, replay occurs within sharp wave-ripples: short bouts of high-frequency activity in area CA1 caused by excitatory activation from area CA3. In this work, we develop a computational model of ripple generation, motivated by in vivo rat data showing that ripples have a broad frequency distribution, exponential inter-arrival times and yet highly non-variable durations. Our study predicts that ripples are not persistent oscillations but result from a transient network behavior, induced by input from CA3, in which the high frequency synchronous firing of perisomatic interneurons does not depend on the time scale of synaptic inhibition. We found that noise-induced loss of synchrony among CA1 interneurons dynamically constrains individual ripple duration. Our study proposes a novel mechanism of hippocampal ripple generation consistent with a broad range of experimental data, and highlights the role of noise in regulating the duration of input-driven oscillatory spiking in an inhibitory network. PMID:27093059

  2. literacy.ca EXPRESS. October 2009

    ERIC Educational Resources Information Center

    Movement for Canadian Literacy, 2009

    2009-01-01

    This issue of "literacy.ca EXPRESS" focuses on the topic of promising practice. Promising or good practice and lessons learned are used to describe useful practices, approaches or ideas. Articles included in this issue: (1) Practitioner Profile: Meet Connie Jones; (2) Highlights from the LAN (Learner Advisory Network); (3) In the Works... Projects…

  3. literacy.ca EXPRESS. April 2010

    ERIC Educational Resources Information Center

    Movement for Canadian Literacy, 2010

    2010-01-01

    This issue of "literacy.ca EXPRESS" focuses on poverty. The articles included in this issue are: (1) Poverty Overview; (2) Tony's Story; (3) LAN (Learner Advisory Network) Member's Story (Dianne Smith); (4) Linking Adult Literacy to Poverty Reduction; (5) MCL (Movement for Canadian Literacy) Update; (6) Highlights from the LAN; (7) Good to Know...…

  4. literacy.ca EXPRESS. December 2010

    ERIC Educational Resources Information Center

    Canadian Literacy and Learning Network, 2010

    2010-01-01

    This issue of "literacy.ca EXPRESS" features new and exciting developments, updates and exciting new resources. Articles included in this issue are: (1) Introducing CLLN (Canadian Literacy and Learning Network)!; (2) Supporting Learner Leadership; (3) Involving Learners by Patricia Ashie; (4) Catching Confidence; (5) CALL (Committee of Adult…

  5. The study of skeletal calcium metabolism with 41Ca and 45Ca

    NASA Astrophysics Data System (ADS)

    Freeman, Stewart P. H. T.; Beck, Belinda; Bierman, June M.; Caffee, Marc W.; Heaney, Robert P.; Holloway, Leah; Marcus, Robert; Southon, John R.; Vogel, John S.

    2000-10-01

    The living skeleton can be labeled for life by the administration of radiologically trivial amounts of 41Ca tracer. After initial elimination of tracer from the readily exchangeable calcium pools subsequent skeletal calcium turnover maintains and modulates the urine 41Ca content. Uniquely, bone calcium metabolism may then be studied with tracer in near equilibrium with the body's calcium and resorbing calcium directly measured by accelerator mass spectrometry (AMS) of excreta. Our experiments with 25 41Ca labeled subjects demonstrate excellent diurnal stability and remarkable response to intervention of the urine signal. Thus the tracer method may prove a competitive means of measuring the effects of antiresorptive osteoporosis treatments, for therapy development or even clinical monitoring. Novel studies of long-term skeletal evolution are also possible. We realize that routinely administered short-lived calcium radiotracers contain 41Ca impurities and that thousands of experimental participants have been historically inadvertently 41Ca labeled. The 41Ca urine index might now rapidly further be characterized by contemporary measurements of these one-time subjects, and with their by now thoroughly skeleton-equilibrated tracer they might be ideal participants in other new experiments. We are also investigating 45Ca AMS. It may prove preferable to label the skeleton with this radiotracer already familiar to bioscientists, but new to AMS.

  6. Ca(2+)-activated chloride channel activity during Ca(2+) alternans in ventricular myocytes.

    PubMed

    Kanaporis, Giedrius; Blatter, Lothar A

    2016-11-01

    Cardiac alternans, defined beat-to-beat alternations in contraction, action potential (AP) morphology or cytosolic Ca transient (CaT) amplitude, is a high risk indicator for cardiac arrhythmias. We investigated mechanisms of cardiac alternans in single rabbit ventricular myocytes. CaTs were monitored simultaneously with membrane currents or APs recorded with the patch clamp technique. A strong correlation between beat-to-beat alternations of AP morphology and CaT alternans was observed. During CaT alternans application of voltage clamp protocols in form of pre-recorded APs revealed a prominent Ca(2+)-dependent membrane current consisting of a large outward component coinciding with AP phases 1 and 2, followed by an inward current during AP repolarization. Approximately 85% of the initial outward current was blocked by Cl(-) channel blocker DIDS or lowering external Cl(-) concentration identifying it as a Ca(2+)-activated Cl(-) current (ICaCC). The data suggest that ICaCC plays a critical role in shaping beat-to-beat alternations in AP morphology during alternans.

  7. DA-6034 Induces [Ca(2+)]i Increase in Epithelial Cells.

    PubMed

    Yang, Yu-Mi; Park, Soonhong; Ji, Hyewon; Kim, Tae-Im; Kim, Eung Kweon; Kang, Kyung Koo; Shin, Dong Min

    2014-04-01

    DA-6034, a eupatilin derivative of flavonoid, has shown potent effects on the protection of gastric mucosa and induced the increases in fluid and glycoprotein secretion in human and rat corneal and conjunctival cells, suggesting that it might be considered as a drug for the treatment of dry eye. However, whether DA-6034 induces Ca(2+) signaling and its underlying mechanism in epithelial cells are not known. In the present study, we investigated the mechanism for actions of DA-6034 in Ca(2+) signaling pathways of the epithelial cells (conjunctival and corneal cells) from human donor eyes and mouse salivary gland epithelial cells. DA-6034 activated Ca(2+)-activated Cl(-) channels (CaCCs) and increased intracellular calcium concentrations ([Ca(2+)]i) in primary cultured human conjunctival cells. DA-6034 also increased [Ca(2+)]i in mouse salivary gland cells and human corneal epithelial cells. [Ca(2+)]i increase of DA-6034 was dependent on the Ca(2+) entry from extracellular and Ca(2+) release from internal Ca(2+) stores. Interestingly, these effects of DA-6034 were related to ryanodine receptors (RyRs) but not phospholipase C/inositol 1,4,5-triphosphate (IP3) pathway and lysosomal Ca(2+) stores. These results suggest that DA-6034 induces Ca(2+) signaling via extracellular Ca(2+) entry and RyRs-sensitive Ca(2+) release from internal Ca(2+) stores in epithelial cells.

  8. Calculated and measured [Ca(2+)] in buffers used to calibrate Ca(2+) macroelectrodes.

    PubMed

    McGuigan, John A S; Stumpff, Friederike

    2013-05-01

    The ionized concentration of calcium in physiological buffers ([Ca(2+)]) is normally calculated using either tabulated constants or software programs. To investigate the accuracy of such calculations, the [Ca(2+)] in EGTA [ethylene glycol-bis(β-aminoethylether)-N,N,N|,N|-tetraacetic acid], BAPTA [1,2-bis(o-aminophenoxy) ethane-N,N,N|,N|-tetraacetic acid], HEDTA [N-(2-hydroxyethyl)-ethylenediamine-N,N|,N|-triacetic acid], and NTA [N,N-bis(carboxymethyl)glycine] buffers was estimated using the ligand optimization method, and these measured values were compared with calculated values. All measurements overlapped in the pCa range of 3.51 (NTA) to 8.12 (EGTA). In all four buffer solutions, there was no correlation between measured and calculated values; the calculated values differed among themselves by factors varying from 1.3 (NTA) to 6.9 (EGTA). Independent measurements of EGTA purity and the apparent dissociation constants for HEDTA and NTA were not significantly different from the values estimated by the ligand optimization method, further substantiating the method. Using two calibration solutions of pCa 2.0 and 3.01 and seven buffers in the pCa range of 4.0-7.5, calibration of a Ca(2+) electrode over the pCa range of 2.0-7.5 became a routine procedure. It is proposed that such Ca(2+) calibration/buffer solutions be internationally defined and made commercially available to allow the precise measurement of [Ca(2+)] in biology.

  9. Voltage-gated Ca2+ influx and mitochondrial Ca2+ initiate secretion from Aplysia neuroendocrine cells.

    PubMed

    Hickey, C M; Groten, C J; Sham, L; Carter, C J; Magoski, N S

    2013-10-10

    Neuroendocrine secretion often requires prolonged voltage-gated Ca(2+) entry; however, the ability of Ca(2+) from intracellular stores, such as endoplasmic reticulum or mitochondria, to elicit secretion is less clear. We examined this using the bag cell neurons, which trigger ovulation in Aplysia by releasing egg-laying hormone (ELH) peptide. Secretion from cultured bag cell neurons was observed as an increase in plasma membrane capacitance following Ca(2+) influx evoked by a 5-Hz, 1-min train of depolarizing steps under voltage-clamp. The response was similar for step durations of ≥ 50 ms, but fell off sharply with shorter stimuli. The capacitance change was attenuated by replacing external Ca(2+) with Ba(2+), blocking Ca(2+) channels, buffering intracellular Ca(2+) with EGTA, disrupting synaptic protein recycling, or genetic knock-down of ELH. Regarding intracellular stores, liberating mitochondrial Ca(2+) with the protonophore, carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP), brought about an EGTA-sensitive elevation of capacitance. Conversely, no change was observed to Ca(2+) released from the endoplasmic reticulum or acidic stores. Prior exposure to FCCP lessened the train-induced capacitance increase, suggesting overlap in the pool of releasable vesicles. Employing GTP-γ-S to interfere with endocytosis delayed recovery (presumed membrane retrieval) of the capacitance change following FCCP, but not the train. Finally, secretion was correlated with reproductive behavior, in that neurons isolated from animals engaged in egg-laying presented a greater train-induced capacitance elevation vs quiescent animals. The bag cell neuron capacitance increase is consistent with peptide secretion requiring high Ca(2+), either from influx or stores, and may reflect the all-or-none nature of reproduction.

  10. Voltage-gated Ca2+ influx and mitochondrial Ca2+ initiate secretion from Aplysia neuroendocrine cells.

    PubMed

    Hickey, C M; Groten, C J; Sham, L; Carter, C J; Magoski, N S

    2013-10-10

    Neuroendocrine secretion often requires prolonged voltage-gated Ca(2+) entry; however, the ability of Ca(2+) from intracellular stores, such as endoplasmic reticulum or mitochondria, to elicit secretion is less clear. We examined this using the bag cell neurons, which trigger ovulation in Aplysia by releasing egg-laying hormone (ELH) peptide. Secretion from cultured bag cell neurons was observed as an increase in plasma membrane capacitance following Ca(2+) influx evoked by a 5-Hz, 1-min train of depolarizing steps under voltage-clamp. The response was similar for step durations of ≥ 50 ms, but fell off sharply with shorter stimuli. The capacitance change was attenuated by replacing external Ca(2+) with Ba(2+), blocking Ca(2+) channels, buffering intracellular Ca(2+) with EGTA, disrupting synaptic protein recycling, or genetic knock-down of ELH. Regarding intracellular stores, liberating mitochondrial Ca(2+) with the protonophore, carbonyl cyanide-p-trifluoromethoxyphenyl-hydrazone (FCCP), brought about an EGTA-sensitive elevation of capacitance. Conversely, no change was observed to Ca(2+) released from the endoplasmic reticulum or acidic stores. Prior exposure to FCCP lessened the train-induced capacitance increase, suggesting overlap in the pool of releasable vesicles. Employing GTP-γ-S to interfere with endocytosis delayed recovery (presumed membrane retrieval) of the capacitance change following FCCP, but not the train. Finally, secretion was correlated with reproductive behavior, in that neurons isolated from animals engaged in egg-laying presented a greater train-induced capacitance elevation vs quiescent animals. The bag cell neuron capacitance increase is consistent with peptide secretion requiring high Ca(2+), either from influx or stores, and may reflect the all-or-none nature of reproduction. PMID:23876326

  11. Cenozoic seawater Sr/Ca evolution

    NASA Astrophysics Data System (ADS)

    Sosdian, Sindia M.; Lear, Caroline H.; Tao, Kai; Grossman, Ethan L.; O'Dea, Aaron; Rosenthal, Yair

    2012-10-01

    Records of seawater chemistry help constrain temporal variations in geochemical processes that impact the global carbon cycle and climate through Earth's history. Here we reconstruct Cenozoic seawater Sr/Ca (Sr/Casw) using fossil Conus and turritellid gastropod Sr/Ca. Combined with an oxygen isotope paleotemperature record from the same samples, the gastropod record suggests that Sr/Caswwas slightly higher in the Eocene (˜11.4 ± 3 mmol/mol) than today (˜8.54 mmol/mol) and remained relatively stable from the mid- to late Cenozoic. We compare our gastropod Cenozoic Sr/Casw record with a published turritellid gastropod Sr/Casw record and other published biogenic (benthic foraminifera, fossil fish teeth) and inorganic precipitate (calcite veins) Sr/Caswrecords. Once the uncertainties with our gastropod-derived Sr/Casw are taken into account the Sr/Casw record agrees reasonably well with biogenic Sr/Caswrecords. Assuming a seawater [Ca] history derived from marine evaporite inclusions, all biogenic-based Sr/Casw reconstructions imply decreasing seawater [Sr] through the Cenozoic, whereas the calcite vein Sr/Casw reconstruction implies increasing [Sr] through the Cenozoic. We apply a simple geochemical model to examine the implications of divergence among these seawater [Sr] reconstructions and suggest that the interpretation and uncertainties associated with the gastropod and calcite vein proxies need to be revisited. Used in conjunction with records of carbonate depositional fluxes, our favored seawater Sr/Ca scenarios point to a significant increase in the proportion of aragonite versus calcite deposition in shelf sediments from the Middle Miocene, coincident with the proliferation of coral reefs. We propose that this occurred at least 10 million years after the seawater Mg/Ca threshold was passed, and was instead aided by declining levels of atmospheric carbon dioxide.

  12. ASteCA: Automated Stellar Cluster Analysis

    NASA Astrophysics Data System (ADS)

    Perren, G. I.; Vázquez, R. A.; Piatti, A. E.

    2015-04-01

    We present the Automated Stellar Cluster Analysis package (ASteCA), a suit of tools designed to fully automate the standard tests applied on stellar clusters to determine their basic parameters. The set of functions included in the code make use of positional and photometric data to obtain precise and objective values for a given cluster's center coordinates, radius, luminosity function and integrated color magnitude, as well as characterizing through a statistical estimator its probability of being a true physical cluster rather than a random overdensity of field stars. ASteCA incorporates a Bayesian field star decontamination algorithm capable of assigning membership probabilities using photometric data alone. An isochrone fitting process based on the generation of synthetic clusters from theoretical isochrones and selection of the best fit through a genetic algorithm is also present, which allows ASteCA to provide accurate estimates for a cluster's metallicity, age, extinction and distance values along with its uncertainties. To validate the code we applied it on a large set of over 400 synthetic MASSCLEAN clusters with varying degrees of field star contamination as well as a smaller set of 20 observed Milky Way open clusters (Berkeley 7, Bochum 11, Czernik 26, Czernik 30, Haffner 11, Haffner 19, NGC 133, NGC 2236, NGC 2264, NGC 2324, NGC 2421, NGC 2627, NGC 6231, NGC 6383, NGC 6705, Ruprecht 1, Tombaugh 1, Trumpler 1, Trumpler 5 and Trumpler 14) studied in the literature. The results show that ASteCA is able to recover cluster parameters with an acceptable precision even for those clusters affected by substantial field star contamination. ASteCA is written in Python and is made available as an open source code which can be downloaded ready to be used from its official site.

  13. The Electronic Spectra of CaN2(+) and Ca(N2)2(+)

    NASA Technical Reports Server (NTRS)

    Rodriguez-Santiago, Luis; Bauschlicher, Charles W., Jr.; Arnold, James (Technical Monitor)

    1998-01-01

    The ground and low-lying electronic states of CaN2(+) are studied at several levels of theory. The results for the X(sup 2)Sigma(+) state and the excited (2)(sup 2)Pi state, arising from occupying the Ca 4p orbital, are in good agreement with experiment. The analogous states of Ca(N2)2(+) are studied using the same theoretical approaches, and predictions are made as to the changes caused by the addition of the second N2 ligand.

  14. A study of the low-lying states of CaAr + and CaKr +

    NASA Astrophysics Data System (ADS)

    Heinemann, Christoph; Koch, Wolfram; Partridge, Harry

    1998-04-01

    The spectroscopic constants of the ground 2Σ + states of CaAr + and CaKr + are determined using high quality ab initio methods. The computed binding energies are 789 and 1252 cm -1, respectively, in good agreement with the experimental determination of Pullins, Scurlock, Reddic and Duncan (J. Chem. Phys. 104 (1996) 7518). The much smaller CaKr + binding energy determined by Buthelezi, Bellert, Lewis and Brucat (Chem. Phys. Lett. 246 (1995) 145) is shown to be due to deficiencies in the method used to approximate the binding energy of the excited state.

  15. Ca2+-dependent facilitation of Cav1.3 Ca2+ channels by densin and Ca2+/calmodulin-dependent protein kinase II

    PubMed Central

    Jenkins, Meagan A.; Christel, Carl J.; Jiao, Yuxia; Abiria, Sunday; Kim, Kristin Y.; Usachev, Yuriy M.; Obermair, Gerald J.; Colbran, Roger J.; Lee, Amy

    2010-01-01

    Cav1 (L-type) channels and calmodulin-dependent protein kinase II (CaMKII) are key regulators of Ca2+ signaling in neurons. CaMKII directly potentiates the activity of Cav1.2 and Cav1.3 channels, but the underlying molecular mechanisms are incompletely understood. Here, we report that the CaMKII-associated protein, densin, is required for Ca2+-dependent facilitation of Cav1.3 channels. While neither CaMKII nor densin independently affect Cav1.3 properties in transfected HEK293T cells, the two together augment Cav1.3 Ca2+ currents during repetitive, but not sustained, depolarizing stimuli. Facilitation requires Ca2+, CaMKII activation and its association with densin, as well as densin binding to the Cav1.3 α1 subunit C-terminal domain. Cav1.3 channels and densin are targeted to dendritic spines in neurons and form a complex with CaMKII in the brain. Our results demonstrate a novel mechanism for Ca2+-dependent facilitation that may intensify postsynaptic Ca2+ signals during high-frequency stimulation. PMID:20392935

  16. Exercise training reverses myocardial dysfunction induced by CaMKIIδC overexpression by restoring Ca2+ homeostasis.

    PubMed

    Høydal, Morten A; Stølen, Tomas O; Kettlewell, Sarah; Maier, Lars S; Brown, Joan Heller; Sowa, Tomas; Catalucci, Daniele; Condorelli, Gianluigi; Kemi, Ole J; Smith, Godfrey L; Wisløff, Ulrik

    2016-07-01

    Several conditions of heart disease, including heart failure and diabetic cardiomyopathy, are associated with upregulation of cytosolic Ca(2+)/calmodulin-dependent protein kinase II (CaMKIIδC) activity. In the heart, CaMKIIδC isoform targets several proteins involved in intracellular Ca(2+) homeostasis. We hypothesized that high-intensity endurance training activates mechanisms that enable a rescue of dysfunctional cardiomyocyte Ca(2+) handling and thereby ameliorate cardiac dysfunction despite continuous and chronic elevated levels of CaMKIIδC CaMKIIδC transgenic (TG) and wild-type (WT) mice performed aerobic interval exercise training over 6 wk. Cardiac function was measured by echocardiography in vivo, and cardiomyocyte shortening and intracellular Ca(2+) handling were measured in vitro. TG mice had reduced global cardiac function, cardiomyocyte shortening (47% reduced compared with WT, P < 0.01), and impaired Ca(2+) homeostasis. Despite no change in the chronic elevated levels of CaMKIIδC, exercise improved global cardiac function, restored cardiomyocyte shortening, and reestablished Ca(2+) homeostasis to values not different from WT. The key features to explain restored Ca(2+) homeostasis after exercise training were increased L-type Ca(2+) current density and flux by 79 and 85%, respectively (P < 0.01), increased sarcoplasmic reticulum (SR) Ca(2+)-ATPase (SERCA2a) function by 50% (P < 0.01), and reduced diastolic SR Ca(2+) leak by 73% (P < 0.01), compared with sedentary TG mice. In conclusion, exercise training improves global cardiac function as well as cardiomyocyte function in the presence of a maintained high CaMKII activity. The main mechanisms of exercise-induced improvements in TG CaMKIIδC mice are mediated via increased L-type Ca(2+) channel currents and improved SR Ca(2+) handling by restoration of SERCA2a function in addition to reduced diastolic SR Ca(2+) leak. PMID:27231311

  17. Ca2+ signals regulate mitochondrial metabolism by stimulating CREB-mediated expression of the mitochondrial Ca2+ uniporter gene MCU.

    PubMed

    Shanmughapriya, Santhanam; Rajan, Sudarsan; Hoffman, Nicholas E; Zhang, Xueqian; Guo, Shuchi; Kolesar, Jill E; Hines, Kevin J; Ragheb, Jonathan; Jog, Neelakshi R; Caricchio, Roberto; Baba, Yoshihiro; Zhou, Yandong; Kaufman, Brett A; Cheung, Joseph Y; Kurosaki, Tomohiro; Gill, Donald L; Madesh, Muniswamy

    2015-03-03

    Cytosolic Ca2+ signals, generated through the coordinated translocation of Ca2+ across the plasma membrane (PM) and endoplasmic reticulum (ER) membrane, mediate diverse cellular responses. Mitochondrial Ca2+ is important for mitochondrial function, and when cytosolic Ca2+ concentration becomes too high, mitochondria function as cellular Ca2+ sinks. By measuring mitochondrial Ca2+ currents, we found that mitochondrial Ca2+ uptake was reduced in chicken DT40 B lymphocytes lacking either the ER-localized inositol trisphosphate receptor (IP3R), which releases Ca2+ from the ER, or Orai1 or STIM1, components of the PM-localized Ca2+ -permeable channel complex that mediates store-operated calcium entry (SOCE) in response to depletion of ER Ca2+ stores. The abundance of MCU, the pore-forming subunit of the mitochondrial Ca2+ uniporter, was reduced in cells deficient in IP3R, STIM1, or Orai1. Chromatin immunoprecipitation and promoter reporter analyses revealed that the Ca2+ -regulated transcription factor CREB (cyclic adenosine monophosphate response element-binding protein) directly bound the MCU promoter and stimulated expression. Lymphocytes deficient in IP3R, STIM1, or Orai1 exhibited altered mitochondrial metabolism, indicating that Ca2+ released from the ER and SOCE-mediated signals modulates mitochondrial function. Thus, our results showed that a transcriptional regulatory circuit involving Ca2+ -dependent activation of CREB controls the Ca2+ uptake capability of mitochondria and hence regulates mitochondrial metabolism.

  18. Phosphorylation and activation of nuclear Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) by Ca{sup 2+}/calmodulin-dependent protein kinase I (CaMKI)

    SciTech Connect

    Onouchi, Takashi; Sueyoshi, Noriyuki; Ishida, Atsuhiko; Kameshita, Isamu

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer CaMKP-N/PPM1E underwent proteolytic processing and translocated to cytosol. Black-Right-Pointing-Pointer The proteolysis was effectively inhibited by the proteasome inhibitors. Black-Right-Pointing-Pointer Ser-480 of zebrafish CaMKP-N was phosphorylated by cytosolic CaMKI. Black-Right-Pointing-Pointer Phosphorylation-mimic mutants of CaMKP-N showed enhanced activity. Black-Right-Pointing-Pointer These results suggest that CaMKP-N is regulated by CaMKI. -- Abstract: Nuclear Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) is an enzyme that dephosphorylates and downregulates multifunctional Ca{sup 2+}/calmodulin-dependent protein kinases (CaMKs) as well as AMP-dependent protein kinase. In our previous study, we found that zebrafish CaMKP-N (zCaMKP-N) underwent proteolytic processing and translocated to cytosol in a proteasome inhibitor-sensitive manner. In the present study, we found that zCaMKP-N is regulated by phosphorylation at Ser-480. When zCaMKP-N was incubated with the activated CaMKI, time-dependent phosphorylation of the enzyme was observed. This phosphorylation was significantly reduced when Ser-480 was replaced by Ala, suggesting that CaMKI phosphorylates Ser-480 of zCaMKP-N. Phosphorylation-mimic mutants, S480D and S480E, showed higher phosphatase activities than those of wild type and S480A mutant in solution-based phosphatase assay using various substrates. Furthermore, autophosphorylation of CaMKII after ionomycin treatment was more severely attenuated in Neuro2a cells when CaMKII was cotransfected with the phosphorylation-mimic mutant of zCaMKP-N than with the wild-type or non-phosphorylatable zCaMKP-N. These results strongly suggest that phosphorylation of zCaMKP-N at Ser-480 by CaMKI activates CaMKP-N catalytic activity and thereby downregulates multifunctional CaMKs in the cytosol.

  19. Imaging intraorganellar Ca2+ at subcellular resolution using CEPIA

    PubMed Central

    Suzuki, Junji; Kanemaru, Kazunori; Ishii, Kuniaki; Ohkura, Masamichi; Okubo, Yohei; Iino, Masamitsu

    2014-01-01

    The endoplasmic reticulum (ER) and mitochondria accumulate Ca2+ within their lumens to regulate numerous cell functions. However, determining the dynamics of intraorganellar Ca2+ has proven to be difficult. Here we describe a family of genetically encoded Ca2+ indicators, named calcium-measuring organelle-entrapped protein indicators (CEPIA), which can be utilized for intraorganellar Ca2+ imaging. CEPIA, which emit green, red or blue/green fluorescence, are engineered to bind Ca2+ at intraorganellar Ca2+ concentrations. They can be targeted to different organelles and may be used alongside other fluorescent molecular markers, expanding the range of cell functions that can be simultaneously analysed. The spatiotemporal resolution of CEPIA makes it possible to resolve Ca2+ import into individual mitochondria while simultaneously measuring ER and cytosolic Ca2+. We have used these imaging capabilities to reveal differential Ca2+ handling in individual mitochondria. CEPIA imaging is a useful new tool to further the understanding of organellar functions. PMID:24923787

  20. Ca2+ dialogue between acidic vesicles and ER.

    PubMed

    Morgan, Anthony J

    2016-04-15

    Extracellular stimuli evoke the synthesis of intracellular second messengers, several of which couple to the release of Ca(2+)from Ca(2+)-storing organelles via activation of cognate organellar Ca(2+)-channel complexes. The archetype is the inositol 1,4,5-trisphosphate (IP3) and IP3receptor (IP3R) on the endoplasmic reticulum (ER). A less understood, parallel Ca(2+)signalling cascade is that involving the messenger nicotinic acid adenine dinucleotide phosphate (NAADP) that couples to Ca(2+)release from acidic Ca(2+)stores [e.g. endo-lysosomes, secretory vesicles, lysosome-related organelles (LROs)]. NAADP-induced Ca(2+)release absolutely requires organellar TPCs (two-pore channels). This review discusses how ER and acidic Ca(2+)stores physically and functionally interact to generate and shape global and local Ca(2+)signals, with particular emphasis on the two-way dialogue between these two organelles.

  1. Coupling Ratio for Ca(2+) Transport by Calcium Oxalate Precipitation.

    PubMed

    Sehgal, Pankaj; Olesen, Claus; Møller, Jesper V

    2016-01-01

    The SERCA isoform 1a is constructed to transport 2 Ca(2+) ions across the sarcoplasmic reticulum membrane coupled to the hydrolysis of one molecule of MgATP. However, observed coupling ratios for Ca(2+) transported/ATP hydrolzyed are usually less than 2:1, since part of the Ca(2+) accumulated at high intravesicular concentrations by the active transport of Ca(2+) leaks out of the vesicles because of Ca(2+)-induced Ca(2+) exchange. However, in the presence of a high concentration of oxalate (5 mM) Ca(2+) will precipitate as Ca-oxalate inside the vesicles and thereby be prevented from leaking out and, in addition, this treatment will reduce the intravesicular free concentration of Ca(2+) to a level where optimal coupling ratios of 2:1 can be achieved.

  2. Generation and Behavior Characterization of CaMKIIβ Knockout Mice

    PubMed Central

    Tu, Tao; Goulding, Danielle S.; Haiech, Jacques; Watterson, D. Martin; Van Eldik, Linda J.

    2014-01-01

    The calcium/calmodulin-dependent protein kinase II (CaMKII) is abundant in the brain, where it makes important contributions to synaptic organization and homeostasis, including playing an essential role in synaptic plasticity and memory. Four genes encode isoforms of CaMKII (α, β, δ, γ), with CaMKIIα and CaMKIIβ highly expressed in the brain. Decades of molecular and cellular research, as well as the use of a large number of CaMKIIα mutant mouse lines, have provided insight into the pivotal roles of CaMKIIα in brain plasticity and cognition. However, less is known about the CaMKIIβ isoform. We report the development and extensive behavioral and phenotypic characterization of a CaMKIIβ knockout (KO) mouse. The CaMKIIβ KO mouse was found to be smaller at weaning, with an altered body mass composition. The CaMKIIβ KO mouse showed ataxia, impaired forelimb grip strength, and deficits in the rotorod, balance beam and running wheel tasks. Interestingly, the CaMKIIβ KO mouse exhibited reduced anxiety in the elevated plus maze and open field tests. The CaMKIIβ KO mouse also showed cognitive impairment in the novel object recognition task. Our results provide a comprehensive behavioral characterization of mice deficient in the β isoform of CaMKII. The neurologic phenotypes and the construction of the genotype suggest the utility of this KO mouse strain for future studies of CaMKIIβ in brain structure, function and development. PMID:25127391

  3. Fabrication aspects of PLA-CaP/PLGA-CaP composites for orthopedic applications: a review.

    PubMed

    Zhou, Huan; Lawrence, Joseph G; Bhaduri, Sarit B

    2012-07-01

    For several decades, composites made of polylactic acid-calcium phosphates (PLA-CaP) and polylactic acid-co-glycolic acid-calcium phosphates (PLGA-CaP) have seen widespread uses in orthopedic applications. This paper reviews the fabrication aspects of these composites, following the ubiquitous materials science approach by studying "processing-structure-property" correlations. Various fabrication processes such as microencapsulation, phase separation, electrospinning, supercritical gas foaming, etc., are reviewed, with specific examples of their applications in fabricating these composites. The effect of the incorporation of CaP materials on the mechanical and biological performance of PLA/PLGA is addressed. In addition, this paper describes the state of the art on challenges and innovations concerning CaP dispersion, incorporation of biomolecules/stem cells and long-term degradation of the composites. PMID:22342596

  4. Differential regulation of Ca2+/calmodulin-dependent enzymes by plant calmodulin isoforms and free Ca2+ concentration.

    PubMed

    Lee, S H; Johnson, J D; Walsh, M P; Van Lierop, J E; Sutherland, C; Xu, A; Snedden, W A; Kosk-Kosicka, D; Fromm, H; Narayanan, N; Cho, M J

    2000-08-15

    Multiple calmodulin (CaM) isoforms are expressed in plants, but their biochemical characteristics are not well resolved. Here we show the differential regulation exhibited by two soya bean CaM isoforms (SCaM-1 and SCaM-4) for the activation of five CaM-dependent enzymes, and the Ca(2+) dependence of their target enzyme activation. SCaM-1 activated myosin light-chain kinase as effectively as brain CaM (K(act) 1.8 and 1.7 nM respectively), but SCaM-4 produced no activation of this enzyme. Both CaM isoforms supported near maximal activation of CaM-dependent protein kinase II (CaM KII), but SCaM-4 exhibited approx.12-fold higher K(act) than SCaM-1 for CaM KII phosphorylation of caldesmon. The SCaM isoforms showed differential activation of plant and animal Ca(2+)-ATPases. The plant Ca(2+)-ATPase was activated maximally by both isoforms, while the erythrocyte Ca(2+)-ATPase was activated only by SCaM-1. Plant glutamate decarboxylase was activated fully by SCaM-1, but SCaM-4 exhibited an approx. 4-fold increase in K(act) and an approx. 25% reduction in V(max). Importantly, SCaM isoforms showed a distinct Ca(2+) concentration requirement for target enzyme activation. SCaM-4 required 4-fold higher [Ca(2+)] for half-maximal activation of CaM KII, and 1.5-fold higher [Ca(2+)] for activation of cyclic nucleotide phosphodiesterase than SCaM-1. Thus these plant CaM isoforms provide a mechanism by which a different subset of target enzymes could be activated or inhibited by the differential expression of these CaM isoforms or by differences in Ca(2+) transients.

  5. Ovarian Hormone Loss Impairs Excitatory Synaptic Transmission at Hippocampal CA3–CA1 Synapses

    PubMed Central

    Bryant, Damani N.; Dorsa, Daniel M.; Adelman, John P.; Maylie, James

    2013-01-01

    Premature and long-term ovarian hormone loss following ovariectomy (OVX) is associated with cognitive impairment. This condition is prevented by estradiol (E2) therapy when initiated shortly following OVX but not after substantial delay. To determine whether these clinical findings are correlated with changes in synaptic functions, we used adult OVX rats to evaluate the consequences of short-term (7–10 d, OVXControl) and long-term (∼5 months, OVXLT) ovarian hormone loss, as well as subsequent in vivo E2 treatment, on excitatory synaptic transmission at the hippocampal CA3–CA1 synapses important for learning and memory. The results show that ovarian hormone loss was associated with a marked decrease in synaptic strength. E2 treatment increased synaptic strength in OVXControl but not OVXLT rats, demonstrating a change in the efficacy for E2 5 months following OVX. E2 also had a more rapid effect: within minutes of bath application, E2 acutely increased synaptic strength in all groups except OVXLT rats that did not receive in vivo E2 treatment. E2's acute effect was mediated postsynaptically, and required Ca2+ influx through the voltage-gated Ca2+ channels. Despite E2's acute effect, synaptic strength of OVXLT rats remained significantly lower than that of OVXControl rats. Thus, changes in CA3–CA1 synaptic transmission associated with ovarian hormone loss cannot be fully reversed with delayed E2 treatment. Given that synaptic strength at CA3–CA1 synapses is related to the ability to learn hippocampus-dependent tasks, these findings provide additional insights for understanding cognitive impairment-associated long-term ovarian hormone loss and ineffectiveness for delayed E2 treatment to maintain cognitive functions. PMID:24107948

  6. Dual Effect of Phosphate Transport on Mitochondrial Ca2+ Dynamics*

    PubMed Central

    Wei, An-Chi; Liu, Ting; O'Rourke, Brian

    2015-01-01

    The large inner membrane electrochemical driving force and restricted volume of the matrix confer unique constraints on mitochondrial ion transport. Cation uptake along with anion and water movement induces swelling if not compensated by other processes. For mitochondrial Ca2+ uptake, these include activation of countertransporters (Na+/Ca2+ exchanger and Na+/H+ exchanger) coupled to the proton gradient, ultimately maintained by the proton pumps of the respiratory chain, and Ca2+ binding to matrix buffers. Inorganic phosphate (Pi) is known to affect both the Ca2+ uptake rate and the buffering reaction, but the role of anion transport in determining mitochondrial Ca2+ dynamics is poorly understood. Here we simultaneously monitor extra- and intra-mitochondrial Ca2+ and mitochondrial membrane potential (ΔΨm) to examine the effects of anion transport on mitochondrial Ca2+ flux and buffering in Pi-depleted guinea pig cardiac mitochondria. Mitochondrial Ca2+ uptake proceeded slowly in the absence of Pi but matrix free Ca2+ ([Ca2+]mito) still rose to ∼50 μm. Pi (0.001–1 mm) accelerated Ca2+ uptake but decreased [Ca2+]mito by almost 50% while restoring ΔΨm. Pi-dependent effects on Ca2+ were blocked by inhibiting the phosphate carrier. Mitochondrial Ca2+ uptake rate was also increased by vanadate (Vi), acetate, ATP, or a non-hydrolyzable ATP analog (AMP-PNP), with differential effects on matrix Ca2+ buffering and ΔΨm recovery. Interestingly, ATP or AMP-PNP prevented the effects of Pi on Ca2+ uptake. The results show that anion transport imposes an upper limit on mitochondrial Ca2+ uptake and modifies the [Ca2+]mito response in a complex manner. PMID:25963147

  7. Dual Effect of Phosphate Transport on Mitochondrial Ca2+ Dynamics.

    PubMed

    Wei, An-Chi; Liu, Ting; O'Rourke, Brian

    2015-06-26

    The large inner membrane electrochemical driving force and restricted volume of the matrix confer unique constraints on mitochondrial ion transport. Cation uptake along with anion and water movement induces swelling if not compensated by other processes. For mitochondrial Ca(2+) uptake, these include activation of countertransporters (Na(+)/Ca(2+) exchanger and Na(+)/H(+) exchanger) coupled to the proton gradient, ultimately maintained by the proton pumps of the respiratory chain, and Ca(2+) binding to matrix buffers. Inorganic phosphate (Pi) is known to affect both the Ca(2+) uptake rate and the buffering reaction, but the role of anion transport in determining mitochondrial Ca(2+) dynamics is poorly understood. Here we simultaneously monitor extra- and intra-mitochondrial Ca(2+) and mitochondrial membrane potential (ΔΨm) to examine the effects of anion transport on mitochondrial Ca(2+) flux and buffering in Pi-depleted guinea pig cardiac mitochondria. Mitochondrial Ca(2+) uptake proceeded slowly in the absence of Pi but matrix free Ca(2+) ([Ca(2+)]mito) still rose to ~50 μm. Pi (0.001-1 mm) accelerated Ca(2+) uptake but decreased [Ca(2+)]mito by almost 50% while restoring ΔΨm. Pi-dependent effects on Ca(2+) were blocked by inhibiting the phosphate carrier. Mitochondrial Ca(2+) uptake rate was also increased by vanadate (Vi), acetate, ATP, or a non-hydrolyzable ATP analog (AMP-PNP), with differential effects on matrix Ca(2+) buffering and ΔΨm recovery. Interestingly, ATP or AMP-PNP prevented the effects of Pi on Ca(2+) uptake. The results show that anion transport imposes an upper limit on mitochondrial Ca(2+) uptake and modifies the [Ca(2+)]mito response in a complex manner. PMID:25963147

  8. Ca-α1T, a fly T-type Ca2+ channel, negatively modulates sleep

    PubMed Central

    Jeong, Kyunghwa; Lee, Soyoung; Seo, Haengsoo; Oh, Yangkyun; Jang, Donghoon; Choe, Joonho; Kim, Daesoo; Lee, Jung-Ha; Jones, Walton D.

    2015-01-01

    Mammalian T-type Ca2+ channels are encoded by three separate genes (Cav3.1, 3.2, 3.3). These channels are reported to be sleep stabilizers important in the generation of the delta rhythms of deep sleep, but controversy remains. The identification of precise physiological functions for the T-type channels has been hindered, at least in part, by the potential for compensation between the products of these three genes and a lack of specific pharmacological inhibitors. Invertebrates have only one T-type channel gene, but its functions are even less well-studied. We cloned Ca-α1T, the only Cav3 channel gene in Drosophila melanogaster, expressed it in Xenopus oocytes and HEK-293 cells, and confirmed it passes typical T-type currents. Voltage-clamp analysis revealed the biophysical properties of Ca-α1T show mixed similarity, sometimes falling closer to Cav3.1, sometimes to Cav3.2, and sometimes to Cav3.3. We found Ca-α1T is broadly expressed across the adult fly brain in a pattern vaguely reminiscent of mammalian T-type channels. In addition, flies lacking Ca-α1T show an abnormal increase in sleep duration most pronounced during subjective day under continuous dark conditions despite normal oscillations of the circadian clock. Thus, our study suggests invertebrate T-type Ca2+ channels promote wakefulness rather than stabilizing sleep. PMID:26647714

  9. Uptake of Ca2+ mediated by the (Ca2+ + Mg2+)-ATPase in reconstituted vesicles.

    PubMed

    Gould, G W; McWhirter, J M; East, J M; Lee, A G

    1987-11-01

    The (Ca2+ + Mg2+)-ATPase was purified from skeletal muscle sarcoplasmic reticulum and reconstituted into sealed phospholipid vesicles by solution in cholate and deoxycholate followed by detergent removal on a column of Sephadex G-50. The level of Ca2+ accumulated by these vesicles, either in the presence or absence of phosphate within the vesicles, increased with increasing content of phosphatidylethanolamine in the phospholipid mixture used for the reconstitution. The levels of Ca2+ accumulated in the absence of phosphate were very low for vesicles reconstituted with egg yolk phosphatidylcholine alone at pH 7.4, but increased markedly with decreasing pH to 6.0. Uptake was also relatively low for vesicles reconstituted with dimyristoleoyl- or dinervonylphosphatidylcholine, and addition of cholesterol had little effect. The level of Ca2+ accumulated increased with increasing external K+ concentration, and was also increased by the ionophores FCCP and valinomycin. Vesicle sizes changed little with changing phosphatidylethanolamine content, and the sidedness of insertion of the ATPase was close to random at all phosphatidylethanolamine contents. It is suggested that the effect of phosphatidylethanolamine on the level of Ca2+ accumulation follows from an effect on the rate of Ca2+ efflux mediated by the ATPase.

  10. Rediscovering area CA2: unique properties and functions

    PubMed Central

    Dudek, Serena M.; Alexander, Georgia M.; Farris, Shannon

    2016-01-01

    Hippocampal area CA2 has several features that distinguish it from CA1 and CA3, including a unique gene expression profile, failure to display long-term potentiation and relative resistance to cell death. A recent increase in interest in the CA2 region, combined with the development of new methods to define and manipulate its neurons, has led to some exciting new discoveries on the properties of CA2 neurons and their role in behaviour. Here, we review these findings and call attention to the idea that the definition of area CA2 ought to be revised in light of gene expression data. PMID:26806628

  11. Endo-lysosomal TRP mucolipin-1 channels trigger global ER Ca2+ release and Ca2+ influx

    PubMed Central

    Kilpatrick, Bethan S.; Yates, Elizabeth; Grimm, Christian; Schapira, Anthony H.

    2016-01-01

    ABSTRACT Transient receptor potential (TRP) mucolipins (TRPMLs), encoded by the MCOLN genes, are patho-physiologically relevant endo-lysosomal ion channels crucial for membrane trafficking. Several lines of evidence suggest that TRPMLs mediate localised Ca2+ release but their role in Ca2+ signalling is not clear. Here, we show that activation of endogenous and recombinant TRPMLs with synthetic agonists evoked global Ca2+ signals in human cells. These signals were blocked by a dominant-negative TRPML1 construct and a TRPML antagonist. We further show that, despite a predominant lysosomal localisation, TRPML1 supports both Ca2+ release and Ca2+ entry. Ca2+ release required lysosomal and ER Ca2+ stores suggesting that TRPMLs, like other endo-lysosomal Ca2+ channels, are capable of ‘chatter’ with ER Ca2+ channels. Our data identify new modalities for TRPML1 action. PMID:27577094

  12. Kinetics and stoichiometry of coupled Na efflux and Ca influx (Na/Ca exchange) in barnacle muscle cells

    PubMed Central

    1989-01-01

    Coupled Na+ exit/Ca2+ entry (Na/Ca exchange operating in the Ca2+ influx mode) was studied in giant barnacle muscle cells by measuring 22Na+ efflux and 45Ca2+ influx in internally perfused, ATP-fueled cells in which the Na+ pump was poisoned by 0.1 mM ouabain. Internal free Ca2+, [Ca2+]i, was controlled with a Ca-EGTA buffering system containing 8 mM EGTA and varying amounts of Ca2+. Ca2+ sequestration in internal stores was inhibited with caffeine and a mitochondrial uncoupler (FCCP). To maximize conditions for Ca2+ influx mode Na/Ca exchange, and to eliminate tracer Na/Na exchange, all of the external Na+ in the standard Na+ sea water (NaSW) was replaced by Tris or Li+ (Tris-SW or LiSW, respectively). In both Na-free solutions an external Ca2+ (Cao)-dependent Na+ efflux was observed when [Ca2+]i was increased above 10(-8) M; this efflux was half-maximally activated by [Ca2+]i = 0.3 microM (LiSW) to 0.7 microM (Tris-SW). The Cao-dependent Na+ efflux was half-maximally activated by [Ca2+]o = 2.0 mM in LiSW and 7.2 mM in Tris-SW; at saturating [Ca2+]o, [Ca2+]i, and [Na+]i the maximal (calculated) Cao-dependent Na+ efflux was approximately 75 pmol#cm2.s. This efflux was inhibited by external Na+ and La3+ with IC50's of approximately 125 and 0.4 mM, respectively. A Nai-dependent Ca2+ influx was also observed in Tris-SW. This Ca2+ influx also required [Ca2+]i greater than 10(-8) M. Internal Ca2+ activated a Nai-independent Ca2+ influx from LiSW (tracer Ca/Ca exchange), but in Tris-SW virtually all of the Cai-activated Ca2+ influx was Nai-dependent (Na/Ca exchange). Half-maximal activation was observed with [Na+]i = 30 mM. The fact that internal Ca2+ activates both a Cao-dependent Na+ efflux and a Nai- dependent Ca2+ influx in Tris-SW implies that these two fluxes are coupled; the activating (intracellular) Ca2+ does not appear to be transported by the exchanger. The maximal (calculated) Nai-dependent Ca2+ influx was -25 pmol/cm2.s. At various [Na+]i between 6 and 106 m

  13. Neuronal Ca(2+) dyshomeostasis in Huntington disease.

    PubMed

    Giacomello, Marta; Oliveros, Juan C; Naranjo, Jose R; Carafoli, Ernesto

    2013-01-01

    The expansion of the N-terminal poly-glutamine tract of the huntingtin (Htt) protein is responsible for Huntington disease (HD). A large number of studies have explored the neuronal phenotype of HD, but the molecular aethiology of the disease is still very poorly understood. This has hampered the development of an appropriate therapeutical strategy to at least alleviate its symptoms. In this short review, we have focused our attention on the alteration of a specific cellular mechanism common to all HD models, either genetic or induced by treatment with 3-NPA, i.e. the cellular dyshomeostasis of Ca(2+). We have highlighted the direct and indirect (i.e. transcriptionally mediated) effects of mutated Htt on the maintenance of the intracellular Ca(2+) balance, the correct modulation of which is fundamental to cell survival and the disturbance of which plays a key role in the death of the cell.

  14. Luminal Ca2+ promoting spontaneous Ca2+ release from inositol trisphosphate-sensitive stores in rat hepatocytes.

    PubMed Central

    Missiaen, L; Taylor, C W; Berridge, M J

    1992-01-01

    1. Spontaneous Ca2+ release from the inositol 1,4,5-trisphosphate (InsP3)-sensitive stores in permeabilized hepatocytes was monitored using Fluo-3 to measure the free [Ca2+] of the medium bathing the cells. 2. Permeabilized cells rapidly sequestered Ca2+, reducing the [Ca2+] to 103 +/- 5 nM. Under conditions that depended critically upon cell density and the amount of Ca2+ in the medium, this was followed by a slow increase in [Ca2+] culminating in a substantial Ca2+ spike representing synchronous discharge from the InsP3-sensitive stores. 3. During the latency preceding the Ca2+ spike, the stores increased their sensitivity to InsP3. This sensitization seemed to be an all-or-none phenomenon. 4. Oxidized glutathione and thimerosal promoted the spontaneous release by sensitizing the InsP3 receptor. 5. An increase in the [Ca2+] within the stores was required for both the increased sensitivity to InsP3 and the subsequent spike. 6. Caffeine (6 mM) antagonized the effect of very low InsP3 concentrations and abolished the Ca2+ spike, without itself releasing Ca2+. 7. Our results suggesting that luminal Ca2+ may sensitive InsP3-sensitive stores leading to spontaneous Ca2+ mobilization will be discussed in the light of a modified version of the two-pool model for explaining cytosolic Ca2+ oscillations. PMID:1484365

  15. Evidence that Ca2+-release-activated Ca2+ channels in rat hepatocytes are required for the maintenance of hormone-induced Ca2+ oscillations.

    PubMed Central

    Gregory, Roland B; Barritt, Gregory J

    2003-01-01

    Store-operated Ca(2+) channels in liver cells have been shown previously to exhibit a high selectivity for Ca(2+) and to have properties indistinguishable from those of Ca(2+)-release-activated Ca(2+) (CRAC) channels in mast cells and lymphocytes [Rychkov, Brereton, Harland and Barritt (2001) Hepatology 33, 938-947]. The role of CRAC channels in the maintenance of hormone-induced oscillations in the cytoplasmic free Ca(2+) concentration ([Ca(2+)](cyt)) in isolated rat hepatocytes was investigated using several inhibitors of CRAC channels. 2-Aminoethyl diphenylborate (2-APB; 75 microM), Gd(3+) (1 microM) and 1-[beta-[3-(4-methoxyphenyl)propoxy]-4-methoxyphenethyl]-1H-imidazole hydrochloride (SK&F 96365; 50 microM) each inhibited vasopressin- and adrenaline (epinephrine)-induced Ca(2+) oscillations (measured using fura-2). The characteristics of this inhibition were similar to those of inhibition caused by decreasing the extracellular Ca(2+) concentration to zero by addition of EGTA. The effect of 2-APB was reversible. In contrast, LOE-908 [( R, S )-(3,4-dihydro-6,7-dimethoxy-isochinolin-1-yl)-2-phenyl- N, N -di[2-(2,3,4-trimethoxyphenyl)ethyl]acetamide mesylate] (30 microM), used commonly to block Ca(2+) inflow through intracellular-messenger-activated, non-selective cation channels, did not inhibit the Ca(2+) oscillations. In the absence of added extracellular Ca(2+), 2-APB, Gd(3+) and SK&F 96365 did not alter the kinetics of the increase in [Ca(2+)](cyt) induced by a concentration of adrenaline or vasopressin that induces continuous Ca(2+) oscillations at the physiological extracellular Ca(2+) concentration. Ca(2+) inflow through non-selective cation channels activated by maitotoxin could not restore Ca(2+) oscillations in cells treated with 2-APB to block Ca(2+) inflow through CRAC channels. Evidence for the specificity of the pharmacological agents for inhibition of CRAC channels under the conditions of the present experiments with hepatocytes is discussed. It

  16. Superconductivity in Ca-doped graphene laminates.

    PubMed

    Chapman, J; Su, Y; Howard, C A; Kundys, D; Grigorenko, A N; Guinea, F; Geim, A K; Grigorieva, I V; Nair, R R

    2016-03-16

    Despite graphene's long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc's strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp.

  17. Positive magnetoresistance in Ca-doped cobaltites

    SciTech Connect

    Zhou, S. M. Li, Y.; Guo, Y. Q.; Zhao, J. Y.; Shi, L.

    2014-12-08

    Transport properties of polycrystalline La{sub 1−x}Ca{sub x}CoO{sub 3} (0.10 ≤ x ≤ 0.25) are systemically studied in this work. Three types of magnetoresistance (MR) effects are found in the Ca-doped cobaltites. Two negative MRs appear around high-temperature ferromagnetic transition and at low temperatures, which correspond to the conventional MR due to the field-induced suppression of spin-disorder scattering and the intergranular giant-MR due to spin-dependent transport between the ferromagnetic clusters, respectively. More interestingly, another exotic positive MR emerges at intermediate temperature region, which had not been previously reported in Sr- and Ba-doped cobaltites. It is found that this positive MR is associated with an abnormally magnetic transition and increases with the increase of x. For x = 0.25, the MR at low temperatures is dominated by the positive one, which is isotropic and nearly linear with the magnetic field. The possible origin of the positive MR in the Ca-doped cobaltites is discussed.

  18. Superconductivity in CaBi2.

    PubMed

    Winiarski, M J; Wiendlocha, B; Gołąb, S; Kushwaha, S K; Wiśniewski, P; Kaczorowski, D; Thompson, J D; Cava, R J; Klimczuk, T

    2016-08-01

    Superconductivity is observed with critical temperature Tc = 2.0 K in self-flux-grown single crystals of CaBi2. This material adopts the ZrSi2 structure type with lattice parameters a = 4.696(1) Å, b = 17.081(2) Å and c = 4.611(1) Å. The crystals of CaBi2 were studied by means of magnetic susceptibility, specific heat and electrical resistivity measurements. The heat capacity jump at Tc is ΔC/γTc = 1.41, confirming bulk superconductivity; the Sommerfeld coefficient γ = 4.1 mJ mol(-1) K(-2) and the Debye temperature ΘD = 157 K. The electron-phonon coupling strength is λel-ph = 0.59, and the thermodynamic critical field Hc is low, between 111 and 124 Oe CaBi2 is a moderate coupling type-I superconductor. Results of electronic structure calculations are reported and charge densities, electronic bands, densities of states and Fermi surfaces are discussed, focusing on the effects of spin-orbit coupling and electronic property anisotropy. We find a mixed quasi-2D + 3D character in the electronic structure, which reflects the layered crystal structure of the material. PMID:27435423

  19. Superconductivity in CaBi2.

    PubMed

    Winiarski, M J; Wiendlocha, B; Gołąb, S; Kushwaha, S K; Wiśniewski, P; Kaczorowski, D; Thompson, J D; Cava, R J; Klimczuk, T

    2016-08-01

    Superconductivity is observed with critical temperature Tc = 2.0 K in self-flux-grown single crystals of CaBi2. This material adopts the ZrSi2 structure type with lattice parameters a = 4.696(1) Å, b = 17.081(2) Å and c = 4.611(1) Å. The crystals of CaBi2 were studied by means of magnetic susceptibility, specific heat and electrical resistivity measurements. The heat capacity jump at Tc is ΔC/γTc = 1.41, confirming bulk superconductivity; the Sommerfeld coefficient γ = 4.1 mJ mol(-1) K(-2) and the Debye temperature ΘD = 157 K. The electron-phonon coupling strength is λel-ph = 0.59, and the thermodynamic critical field Hc is low, between 111 and 124 Oe CaBi2 is a moderate coupling type-I superconductor. Results of electronic structure calculations are reported and charge densities, electronic bands, densities of states and Fermi surfaces are discussed, focusing on the effects of spin-orbit coupling and electronic property anisotropy. We find a mixed quasi-2D + 3D character in the electronic structure, which reflects the layered crystal structure of the material.

  20. Toward Laser Cooling of CaF

    NASA Astrophysics Data System (ADS)

    Hemmerling, Boerge; Drayna, Garrett; Chae, Eunmi; Ravi, Aakash; Lu, Hsin-I.; Yeo, Mark; Hummon, Matthew; Collopy, Alejandra; Stuhl, Benjamin; Ye, Jun; Doyle, John

    2013-05-01

    The prospects of novel physics employing polar cold molecules encompass quantum computing and simulations, controlled ultra-cold chemistry and precision measurements. However, a method liable to bring a general class of chemically diverse molecules to the ultracold regime still needs to be developed. We report on the progress of experiments to laser cool CaF molecules, including the implementation of a magneto-optical trap (MOT). We use a 2-stage buffer-gas cooled beam source to produce a cold and slow beam of particles. In this experiment, we plan to load the trap from this buffer-gas source. As a precursor to working with CaF, we successfully implemented the first buffer-gas loaded MOT of Yb, without the use of a Zeeman slower, but using only a non-chirped slowing laser. The lifetime of the MOT was measured to be > 100 ms, with the distance between the source and the MOT ~ 30 cm. We describe a scheme for the laser cooling and magneto-optical confinement of CaF molecules, following an approach similar to those used in the cooling of SrF and YO.

  1. Superconductivity in Ca-doped graphene laminates

    PubMed Central

    Chapman, J.; Su, Y.; Howard, C. A.; Kundys, D.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Grigorieva, I. V.; Nair, R. R.

    2016-01-01

    Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp. PMID:26979564

  2. Ca sup + emission in the sunlit ionosphere

    SciTech Connect

    Torr, M.R. ); Torr, D.G.; Bhatt, P.; Swift, W.; Dougani, H. )

    1990-03-01

    In the course of a program of twilight airglow observations from the McDonald Observatory in southwest Texas, the resonance fluorescence emissions from calcium ions were measured. In particular, twilight sequences were obtained during the period of December 19-22, 1987, which coincided with the Ursids meteorite shower. During this meteorite event the intensities of the Ca{sup +} emission lines at 3,934 {angstrom} increased to the point that the surface brightness profiles could be inverted to volume emission rate profiles. These profiles show evidence for strong spatial redistribution of the Ca{sup +} over the course of three days. Prior to the onset of the meteorite activity, emissions from the Ca{sup +} originate from below 100 km, on the occasions when the emissions are visible. By the evening of December 19 a peak is measurable at 108 km. On the morning of December 22, a high-altitude peak was observed above 250 km, with a larger peak down at approximately 85 km. By the evening of December 22, the emission had substantially intensified, with the peak of the layer being at 80 km or below, but with emission being produced all the way up to at least 160 km. Observations of these emissions during meteor shower periods could provide a valuable tracer for the processes responsible for the transport of ions in the D, E, and F region, allowing the full altitude and latitude extent of the distribution to be determined.

  3. Superconductivity in Ca-doped graphene laminates

    NASA Astrophysics Data System (ADS)

    Chapman, J.; Su, Y.; Howard, C. A.; Kundys, D.; Grigorenko, A. N.; Guinea, F.; Geim, A. K.; Grigorieva, I. V.; Nair, R. R.

    2016-03-01

    Despite graphene’s long list of exceptional electronic properties and many theoretical predictions regarding the possibility of superconductivity in graphene, its direct and unambiguous experimental observation has not been achieved. We searched for superconductivity in weakly interacting, metal decorated graphene crystals assembled into so-called graphene laminates, consisting of well separated and electronically decoupled graphene crystallites. We report robust superconductivity in all Ca-doped graphene laminates. They become superconducting at temperatures (Tc) between ≈4 and ≈6 K, with Tc’s strongly dependent on the confinement of the Ca layer and the induced charge carrier concentration in graphene. We find that Ca is the only dopant that induces superconductivity in graphene laminates above 1.8 K among several dopants used in our experiments, such as potassium, caesium and lithium. By revealing the tunability of the superconducting response through doping and confinement of the metal layer, our work shows that achieving superconductivity in free-standing, metal decorated monolayer graphene is conditional on an optimum confinement of the metal layer and sufficient doping, thereby bringing its experimental realization within grasp.

  4. CA 19-9: handle with care.

    PubMed

    Galli, Claudio; Basso, Daniela; Plebani, Mario

    2013-07-01

    Since its inception in the mid-1980s of the 20th century testing for carbohydrate antigen 19-9 (CA 19-9) has raised expectation for an earlier diagnosis and accurate monitoring of several malignant diseases. After almost 30 years, the available evidences have confirmed the appropriateness and usefulness of determining CA 19-9 levels as a prognostic indicator and as a reliable tool for monitoring pancreatic and gastrointestinal cancer, but concerns have been raised about its applications in screening, which is actually not recommended, and in the diagnosis of malignancies, due to several interferences that limit the specificity and to the insufficient sensitivity of this marker. In this paper we aimed to review the basic concepts of CA 19-9 testing and its current applications, with a major focus on the most recent evidences dealing with assay interference, methods comparison and monitoring of malignant diseases. The prognostic value and monitoring recommendations for pancreatic, gastric and colorectal cancers are described in depth.

  5. Comparison of Ca and Ar Diffusion in Phlogopite: Implications for K-Ca and K-Ar Geochronology

    NASA Astrophysics Data System (ADS)

    Cruz, M. F.; Szilas, K.; Grove, M. J.

    2015-12-01

    Coupled geochronology based upon branched decay of 40K-40Ar and 40K-40Ca decay is rarely exploited because 40Ca is the major common isotope of calcium and 40Ca and 40K are difficult to resolve isotopically without resorting to isotope dilution wet chemistry. Recently developed ion microprobe methods based upon measurement of doubly ionized species partially overcome the latter problem and have been applied to high K/Ca micas. The ability to interpret K-Ar and K-Ca results is limited due to uncertainty in the relative diffusion properties of Ca and Ar. To address this problem, we are performing Ar and Ca diffusion experiments and fluid-crystal Ar partitioning experiments with anhydrous F-phlogopite that is stable to 1390°C. As an additional check, we are comparing K-Ca and K-Ar ages from natural mantle phlogopites from a variety of settings to assess the relative retentivity of Ar and Ca. South African xenoliths tend to yield 40Ar/39Ar ages that are much older than K-Ca ages from the same phologopites. Possible excess 40Ar and high common Ca render the comparisons inconclusive, but this suggests that Ca diffuses more readily than Ar in phlogopite. Our most definitive K-Ca phlogopite results (i.e., least affected by common Ca) come from the Archean Seqi dunite of SW Greenland. The K-Ca ages of Seqi phlogopites is 927 ± 26 Ma (2s). Incremental heating 40Ar/39Ar results from the same sample yields a much older result with a terminal age of 3.5 Ga. However, the first 5-10% of 39Ar release are consistent with transient heating at ca. 900 Ma. Considered together, the K-Ca and 40Ar/39Ar results from the Seqi dunite locality strongly suggest that Ca diffusion is more rapid than Ar diffusion in phlogopite.

  6. Dissociation of Ca-bearing Molecules as a Source of Mercury's Ca Exosphere

    NASA Astrophysics Data System (ADS)

    Burger, Matthew H.; Killen, Rosemary M.

    2015-11-01

    Observations of Mercury's calcium exosphere by MESSENGER have revealed three key features: (1) The Ca is extremely energetic, with a temperature ~70,000 K if the source is thermal, (2) the source region is located in the dawn hemisphere, and (3) there is a strong annual variation in the Ca source rate (Burger et al. 2014). Killen and Hahn (2015) have shown that the source rate is consistent with impact vaporization by interplanetary dust and the intersection of Mercury with a cometary dust stream (likely associated with Comet Encke, Christou et al., submitted).Killen et al. (2005) suggested that energetic calcium could be produced by the dissociation of Ca-bearing molecules produced in impact vaporization plumes. We test this hypothesis with a Monte Carlo model that follows the evolution of atomic and molecular calcium produced in impact plumes. Ca-bearing molecules such as CaO, CaOH, and Ca(OH)2 are more likely to be are produced in vapor plumes than atomic Ca (Berezhnoy and Klumov 2008); these molecules quickly break apart either through vibrational dissociation or photodissociation. The excess energy associated with dissociation gives the atomic Ca an extra energy boost above the temperature of the impact plumes (~5000 K). We determine impact vaporization rates and excess energies required by the dissociation process to reproduce the scale height and spatial morphology of the Ca exosphere as observed by the MESSENGER Ultraviolet and Visible Spectrometer (UVVS).ReferencesBerezhnoy, A.A. and Klumov, B.A., Impacts as sources of the exosphere on Mercury, Icarus, 195, 511-522, 2008, doi:10.1016/j.icarus.2008.01.005.Burger, M.H., et al., Seasonal variations in Mercury's dayside calcium exosphere, Icarus, 238, 51-58, 2014, doi:10.1016/j.icarus.2014.04.049.Killen, R.M., et al., The calcium exosphere of Mercury, Icarus, 173, 300-311, 2005, doi:10.1016/j.icarus.2004.08.022.Killen, R.M. and Hahn, J.M., Impact vaporization as a possible source ofMercury's calcium exosphere

  7. Predicting Ca2+ -binding sites using refined carbon clusters.

    PubMed

    Zhao, Kun; Wang, Xue; Wong, Hing C; Wohlhueter, Robert; Kirberger, Michael P; Chen, Guantao; Yang, Jenny J

    2012-12-01

    Identifying Ca(2+) -binding sites in proteins is the first step toward understanding the molecular basis of diseases related to Ca(2+) -binding proteins. Currently, these sites are identified in structures either through X-ray crystallography or NMR analysis. However, Ca(2+) -binding sites are not always visible in X-ray structures due to flexibility in the binding region or low occupancy in a Ca(2+) -binding site. Similarly, both Ca(2+) and its ligand oxygens are not directly observed in NMR structures. To improve our ability to predict Ca(2+) -binding sites in both X-ray and NMR structures, we report a new graph theory algorithm (MUG(C) ) to predict Ca(2+) -binding sites. Using carbon atoms covalently bonded to the chelating oxygen atoms, and without explicit reference to side-chain oxygen ligand co-ordinates, MUG(C) is able to achieve 94% sensitivity with 76% selectivity on a dataset of X-ray structures composed of 43 Ca(2+) -binding proteins. Additionally, prediction of Ca(2+) -binding sites in NMR structures was obtained by MUG(C) using a different set of parameters, which were determined by the analysis of both Ca(2+) -constrained and unconstrained Ca(2+) -loaded structures derived from NMR data. MUG(C) identified 20 of 21 Ca(2+) -binding sites in NMR structures inferred without the use of Ca(2+) constraints. MUG(C) predictions are also highly selective for Ca(2+) -binding sites as analyses of binding sites for Mg(2+) , Zn(2+) , and Pb(2+) were not identified as Ca(2+) -binding sites. These results indicate that the geometric arrangement of the second-shell carbon cluster is sufficient not only for accurate identification of Ca(2+) -binding sites in NMR and X-ray structures but also for selective differentiation between Ca(2+) and other relevant divalent cations.

  8. Regulation of RYR2 by sarcoplasmic reticulum Ca(2+).

    PubMed

    Zhang, Joe Z; Waddell, Helen M M; Jones, Peter P

    2015-06-01

    Ca(2+) is arguably the most important ion involved in the contraction of the heart. The cardiac ryanodine receptor (RyR2), the major Ca(2+) release channel located in the sarcoplasmic reticulum (SR) membrane, is responsible for releasing the bulk of Ca(2+) required for contraction. Moreover, RyR2 is also crucial for maintaining SR Ca(2+) homeostasis by releasing Ca(2+) from the SR when it becomes overloaded with Ca(2+) . During normal contraction, RyR2 is activated by cytosolic Ca(2+) , whereas during store overload conditions, the opening of RyR2 is governed by SR Ca(2+) . Although the process of the cytosolic control of RyR2 is well established, the molecular mechanism by which SR luminal Ca(2+) regulates RyR2 has only recently been elucidated and remains controversial. In addition to the activation of RyR2, SR luminal Ca(2+) also determines when the RyR2 channel closes. RyR2-mediated Ca(2+) release from the SR does not continue until the SR is completely depleted. Rather, it ceases when SR luminal Ca(2+) falls below a certain level. Given the importance of SR Ca(2+) , it is not surprising that the SR luminal Ca(2+) level is tightly controlled by SR Ca(2+) -buffering proteins. Consequently, the opening and closing of RyR2 is heavily influenced by the presence of such proteins, particularly those associated with RyR2, such as calsequestrin and the histidine-rich Ca(2+) -binding protein. These proteins appear to indirectly alter RyR2 activity by modifying the microdomain SR Ca(2+) level surrounding RyR2. PMID:25603835

  9. Conserved properties of individual Ca2+-binding sites in calmodulin

    PubMed Central

    Halling, D. Brent; Liebeskind, Benjamin J.; Hall, Amelia W.; Aldrich, Richard W.

    2016-01-01

    Calmodulin (CaM) is a Ca2+-sensing protein that is highly conserved and ubiquitous in eukaryotes. In humans it is a locus of life-threatening cardiomyopathies. The primary function of CaM is to transduce Ca2+ concentration into cellular signals by binding to a wide range of target proteins in a Ca2+-dependent manner. We do not fully understand how CaM performs its role as a high-fidelity signal transducer for more than 300 target proteins, but diversity among its four Ca2+-binding sites, called EF-hands, may contribute to CaM’s functional versatility. We therefore looked at the conservation of CaM sequences over deep evolutionary time, focusing primarily on the four EF-hand motifs. Expanding on previous work, we found that CaM evolves slowly but that its evolutionary rate is substantially faster in fungi. We also found that the four EF-hands have distinguishing biophysical and structural properties that span eukaryotes. These results suggest that all eukaryotes require CaM to decode Ca2+ signals using four specialized EF-hands, each with specific, conserved traits. In addition, we provide an extensive map of sites associated with target proteins and with human disease and correlate these with evolutionary sequence diversity. Our comprehensive evolutionary analysis provides a basis for understanding the sequence space associated with CaM function and should help guide future work on the relationship between structure, function, and disease. PMID:26884197

  10. Ca cycling and isotopic fluxes in forested ecosystems in Hawaii

    USGS Publications Warehouse

    Wiegand, B.A.; Chadwick, O.A.; Vitousek, P.M.; Wooden, J.L.

    2005-01-01

    Biogeochemical processes fractionate Ca isotopes in plants and soils along a 4 million year developmental sequence in the Hawaiian Islands. We observed that plants preferentially take up 40Ca relative to 44Ca, and that biological fractionation and changes in the relative contributions from volcanic and marine sources produce a significant increase in 44Ca in soil exchangeable pools. Our results imply moderate fluxes enriched in 44Ca from strongly nutrient-depleted old soils, in contrast with high 40Ca fluxes in young and little weathered environments. In addition, biological fractionation controls divergent geochemical pathways of Ca and Sr in the plant-soil system. While Ca depletes progressively with increasing soil age, Sr/Ca ratios increase systematically. Sr isotope ratios provide a valuable tracer for provenance studies of alkaline earth elements in forested ecosystems, but its usefulness is limited when deciphering biogeochemical processes involved in the terrestrial Ca cycle. Ca isotopes in combination with Sr/ Ca ratios reveal more complex processes involved in the biogeochemistry of Ca and Sr. Copyright 2005 by the American Geophysical Union.

  11. Ca Isotopic Ratios in Igneous Rocks: Some Preliminary Results

    NASA Astrophysics Data System (ADS)

    Huang, S.; Farkas, J.; Jacobsen, S. B.

    2009-12-01

    Calcium (Ca) is the 5th most abundant element on the Earth, and it is an important geochemical and cosmochemical tracer. It has six isotopes and only H and He have a larger percentage mass difference (Δm/m) between the heaviest and the lightest isotopes. Systematic Ca isotopic studies have mostly focused on low-temperature geochemical processes, and most Ca isotopic analyses have been applied on modern and ancient marine carbonates and sulphates, documenting large and systematic isotopic variations, which were used to infer the chemical evolution of seawater. Detailed work on igneous rocks is very limited. Here we show two examples of how stable Ca isotopic ratios can be a useful geochemical tool in understanding igneous processes. Ca isotopic fractionation between coexisting clinopyroxene and orthopyroxene from mantle peridotites: We report Ca isotopic ratios on co-existing clino- and ortho-pyroxenes from Kilbourne Hole and San Carlos mantle peridotites. The 44Ca/40Ca in orthopyroxenes is ~0.5 per mil heavier than that in co-existing clinopyroxenes. Combined with published Ca isotopic data on low-temperature Ca-bearing minerals (calcite, aragonite and barite), we show that the fractionation of Ca isotopes between Ca-bearing minerals (at both low-temperature and high-temperature) is primarily controlled by the strength of Ca-O bond in the minerals. The mineral with shorter (i.e., stronger) Ca-O bond yields heavier Ca isotopic ratio. Using our measured 44Ca/40Ca in mantle pyroxenes and the relative proportions of major Ca-bearing minerals in the upper mantle, the estimated 44Ca/40Ca of the upper mantle is 1.1 per mil heavier relative to the NIST 915a, ~0.1 to 0.2 per mil higher than basalts. Ca isotopic variation in Hawaiian shield lavas: Large geochemical and isotopic variations have been observed in lavas forming the large tholeiitic shields of Hawaiian volcanoes, with lavas from the surface of the Koolau volcano (Makapuu-stage) defining one compositional and

  12. Determination of the calcium species in coal chars by Ca K-edge XANES analysis

    NASA Astrophysics Data System (ADS)

    Liu, Li-Juan; Liu, Hui-Jun; Cui, Ming-Qi; Hu, Yong-Feng; Zheng, Lei; Zhao, Yi-Dong; Ma, Chen-Yan; Xi, Shi-Bo; Yang, Dong-Liang; Guo, Zhi-Ying; Wang, Jie

    2013-02-01

    Ca-based additives have been widely used as a sulfur adsorbent during coal pyrolysis and gasification. The Ca speciation and evolution during the pyrolysis of coal with Ca additives have attracted great attention. In this paper, Ca species in the coal chars prepared from the pyrolysis of Ca(OH)2 or CaCO3-added coals are studied by using Ca K-edge X-ray absorption near-edge structural spectroscopy. The results demonstrate that Ca(OH)2, CaSO4, CaS and CaO coexist in the Ca(OH)2-added chars, while Ca(OH)2 and CaSO4 are the main species in the Ca(OH)2-added chars. Besides, a carboxyl-bound Ca is also formed during both the pyrolysis for the Ca(OH)2-added and the CaCO3-added coals. A detailed discussion about the Ca speciation is given.

  13. Pressure-induced structural transformation of CaC2.

    PubMed

    Wang, Lu; Huang, Xiaoli; Li, Da; Huang, Yanping; Bao, Kuo; Li, Fangfei; Wu, Gang; Liu, Bingbing; Cui, Tian

    2016-05-21

    The high pressure structural changes of calcium carbide CaC2 have been investigated with Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques in a diamond anvil cell at room temperature. At ambient conditions, two forms of CaC2 co-exist. Above 4.9 GPa, monoclinic CaC2-ii diminished indicating the structural phase transition from CaC2-ii to CaC2-i. At about 7.0 GPa, both XRD patterns and Raman spectra confirmed that CaC2-i transforms into a metallic Cmcm structure which contains polymeric carbon chains. Along with the phase transition, the isolated C2 dumbbells are polymerized into zigzag chains resulting in a large volume collapse with 22.4%. Above 30.0 GPa, the XRD patterns of CaC2 become featureless and remain featureless upon decompression, suggesting an irreversible amorphization of CaC2.

  14. Pressure-induced structural transformation of CaC2

    NASA Astrophysics Data System (ADS)

    Wang, Lu; Huang, Xiaoli; Li, Da; Huang, Yanping; Bao, Kuo; Li, Fangfei; Wu, Gang; Liu, Bingbing; Cui, Tian

    2016-05-01

    The high pressure structural changes of calcium carbide CaC2 have been investigated with Raman spectroscopy and synchrotron X-ray diffraction (XRD) techniques in a diamond anvil cell at room temperature. At ambient conditions, two forms of CaC2 co-exist. Above 4.9 GPa, monoclinic CaC2-ii diminished indicating the structural phase transition from CaC2-ii to CaC2-i. At about 7.0 GPa, both XRD patterns and Raman spectra confirmed that CaC2-i transforms into a metallic Cmcm structure which contains polymeric carbon chains. Along with the phase transition, the isolated C2 dumbbells are polymerized into zigzag chains resulting in a large volume collapse with 22.4%. Above 30.0 GPa, the XRD patterns of CaC2 become featureless and remain featureless upon decompression, suggesting an irreversible amorphization of CaC2.

  15. Ca2+ triggers massive exocytosis in Chinese hamster ovary cells.

    PubMed Central

    Coorssen, J R; Schmitt, H; Almers, W

    1996-01-01

    We have tracked the cell surface area of CHO cells by measuring the membrane capacitance, Cm. An increase in cytosolic [Ca2+], [Ca2+]i, increased the cell surface area by 20-30%. At micromolar [Ca2+]i the increase occurred in minutes, while at 20 microM or higher [Ca2+]i it occurred in seconds and was transient. GTPgammaS caused a 3% increase even at 0.1 microM [Ca2+]i. We conclude that CHO cells, previously thought capable only of constitutive exocytosis, can perform Ca2+-triggered exocytosis that is both massive and rapid. Ca2+-triggered exocytosis was also observed in 3T3 fibroblasts. Our findings add evidence to the view that Ca induces exocytosis in cells other than known secretory cells. PMID:8670883

  16. Phosphate Capacities of CaF2-MgO and CaF2-CaO-MgO Slags

    NASA Astrophysics Data System (ADS)

    Akbari, F.; Pickles, C. A.

    2015-02-01

    Previously published sulphide capacity data and thermodynamic arguments have been employed to calculate the phosphate capacities and the phosphorus partition ratios between a molten carbon saturated iron alloy and binary CaF2-MgO slags and also ternary CaF2 -CaO-MgO slags at 1450 °C. For the CaF2-MgO binary system, a linear relationship was found between the phosphate and the sulphide capacities as follows: log ? = 1.2 log Cs + 25.2. For the ternary CaF2-CaO-MgO system at 1450 °C, the logarithm of the calculated phosphate capacities ranged from 19.47 to 20.15. With the addition of CaO, the phosphate capacities initially increased, reached a maximum and then decreased slightly. The addition of MgO to the CaF2-CaO system resulted in a decrease in the phosphate capacity. The calculated phosphorus partition ratios increased slightly with increasing mole fraction of CaO in the ternary system.

  17. Application of Ca stable isotopes to long-term changes in the Ca cycle of a Northern Hardwood forest

    NASA Astrophysics Data System (ADS)

    Kurtz, A. C.; Takagi, K.; Bailey, S. W.; Bullen, T. D.

    2015-12-01

    The Hubbard Brook Ecosystem Study (New Hampshire, USA) presents an unusual opportunity for the application of innovative isotope methods in forest biogeochemistry. Changes in biogeochemical cycling resulting from decades of acid deposition, subsequent reductions in acid deposition, and a series of experimental treatments (harvesting, Ca amendment) have been studied continuously for 60 years at this site. Importantly, researchers have archived soil, water, and vegetation samples for much of the site's history. Our work seeks to complement earlier mass balance studies of Ca cycling by measuring Ca isotope ratios on archived samples. In the first component of our study, we examined the Ca isotopic response to an experimental clearcut in the early 1980's. Earlier work showed that the clearcut promoted dramatic loss of Ca from the watershed, indicated by a 5-fold increase in streamwater Ca concentrations. The mechanism for this loss was unclear as no resolvable changes in soil Ca pools were observed. Our work shows that streamwater dissolved Ca becomes isotopically lighter as Ca concentrations increase. These data are best accounted for by an increase in Ca loss from the soil cation exchange complex. Soil exchangeable δ44Ca itself evolves towards lighter values in the years following the experimental harvest. We interpret this as replenishment of the soil exchange complex by release of isotopically light Ca from root biomass. In the second component of our study, we examine decadal-scale changes in streamwater and soil Ca in an un-manipulated biogeochemical reference watershed. Historical data from Hubbard Brook show that streamwater Ca concentrations began decreasing sharply in the early 1970's, attributed to decreased deposition of both acidity and Ca with the passage of the Clean Air Act. Preliminary data indicate no resolvable change in the average δ44Ca of streamwater, with variability mostly attributable to discharge (flowpath control). Preliminary data

  18. MicroRNA-145 suppresses ROS-induced Ca{sup 2+} overload of cardiomyocytes by targeting CaMKIIδ

    SciTech Connect

    Cha, Min-Ji; Jang, Jin-Kyung; Ham, Onju; Song, Byeong-Wook; Lee, Se-Yeon; Lee, Chang Yeon; Park, Jun-Hee; Lee, Jiyun; Seo, Hyang-Hee; Choi, Eunhyun; Jeon, Woo-min; Hwang, Hye Jin; Shin, Hyun-Taek; and others

    2013-06-14

    Highlights: •CaMKIIδ mediates H{sub 2}O{sub 2}-induced Ca{sup 2+} overload in cardiomyocytes. •miR-145 can inhibit Ca{sup 2+} overload. •A luciferase assay confirms that miR-145 functions as a CaMKIIδ-targeting miRNA. •Overexpression of miR-145 regulates CaMKIIδ-related genes and ameliorates apoptosis. -- Abstract: A change in intracellular free calcium (Ca{sup 2+}) is a common signaling mechanism of reperfusion-induced cardiomyocyte death. Calcium/calmodulin dependent protein kinase II (CaMKII) is a critical regulator of Ca{sup 2+} signaling and mediates signaling pathways responsible for functions in the heart including hypertrophy, apoptosis, arrhythmia, and heart disease. MicroRNAs (miRNA) are involved in the regulation of cell response, including survival, proliferation, apoptosis, and development. However, the roles of miRNAs in Ca{sup 2+}-mediated apoptosis of cardiomyocytes are uncertain. Here, we determined the potential role of miRNA in the regulation of CaMKII dependent apoptosis and explored its underlying mechanism. To determine the potential roles of miRNAs in H{sub 2}O{sub 2}-mediated Ca{sup 2+} overload, we selected and tested 6 putative miRNAs that targeted CaMKIIδ, and showed that miR-145 represses CaMKIIδ protein expression and Ca{sup 2+} overload. We confirmed CaMKIIδ as a direct downstream target of miR-145. Furthermore, miR-145 regulates Ca{sup 2+}-related signals and ameliorates apoptosis. This study demonstrates that miR-145 regulates reactive oxygen species (ROS)-induced Ca{sup 2+} overload in cardiomyocytes. Thus, miR-145 affects ROS-mediated gene regulation and cellular injury responses.

  19. Caffeine- and ryanodine-sensitive Ca(2+)-induced Ca2+ release from the endoplasmic reticulum in honeybee photoreceptors.

    PubMed

    Walz, B; Baumann, O; Zimmermann, B; Ciriacy-Wantrup, E V

    1995-04-01

    Light stimulation of invertebrate microvillar photoreceptors causes a large rapid elevation in Cai, shown previously to modulate the adaptational state of the cells. Cai rises, at least in part, as a result of Ins(1,4,5)P3-induced Ca2+ release from the submicrovillar endoplasmic reticulum (ER). Here, we provide evidence for Ca(2+)-induced Ca2+ release (CICR) in an insect photoreceptor. In situ microphotometric measurements of Ca2+ fluxes across the ER membrane in permeabilized slices of drone bee retina show that (a) caffeine induces Ca2+ release from the ER; (b) caffeine and Ins(1,4,5)P3 open distinct Ca2+ release pathways because only caffeine-induced Ca2+ release is ryanodine sensitive and heparin insensitive, and because caffeine and Ins(1,4,5)P3 have additive effects on the rate of Ca2+ release; (c) Ca2+ itself stimulates release of Ca2+ via a ryanodine-sensitive pathway; and (d) cADPR is ineffective in releasing Ca2+. Microfluorometric intracellular Ca2+ measurements with fluo-3 indicate that caffeine induces a persistent elevation in Cai. Electrophysiological recordings demonstrate that caffeine mimics all aspects of Ca(2+)-mediated facilitation and adaptation in drone photoreceptors. We conclude that the ER in drone photoreceptors contains, in addition to the Ins(1,4,5)P3-sensitive release pathway, a CICR pathway that meets key pharmacological criteria for a ryanodine receptor. Coexpression of both release mechanisms could be required for the production of rapid light-induced Ca2+ elevations, because Ca2+ amplifies its own release through both pathways by a positive feedback. CICR may also mediate the spatial spread of Ca2+ release from the submicrovillar ER toward more remote ER subregions, thereby activating Ca(2+)-sensitive cell processes that are not directly involved in phototransduction.

  20. Caffeine- and ryanodine-sensitive Ca(2+)-induced Ca2+ release from the endoplasmic reticulum in honeybee photoreceptors

    PubMed Central

    1995-01-01

    Light stimulation of invertebrate microvillar photoreceptors causes a large rapid elevation in Cai, shown previously to modulate the adaptational state of the cells. Cai rises, at least in part, as a result of Ins(1,4,5)P3-induced Ca2+ release from the submicrovillar endoplasmic reticulum (ER). Here, we provide evidence for Ca(2+)- induced Ca2+ release (CICR) in an insect photoreceptor. In situ microphotometric measurements of Ca2+ fluxes across the ER membrane in permeabilized slices of drone bee retina show that (a) caffeine induces Ca2+ release from the ER; (b) caffeine and Ins(1,4,5)P3 open distinct Ca2+ release pathways because only caffeine-induced Ca2+ release is ryanodine sensitive and heparin insensitive, and because caffeine and Ins(1,4,5)P3 have additive effects on the rate of Ca2+ release; (c) Ca2+ itself stimulates release of Ca2+ via a ryanodine-sensitive pathway; and (d) cADPR is ineffective in releasing Ca2+. Microfluorometric intracellular Ca2+ measurements with fluo-3 indicate that caffeine induces a persistent elevation in Cai. Electrophysiological recordings demonstrate that caffeine mimics all aspects of Ca(2+)-mediated facilitation and adaptation in drone photoreceptors. We conclude that the ER in drone photoreceptors contains, in addition to the Ins(1,4,5)P3-sensitive release pathway, a CICR pathway that meets key pharmacological criteria for a ryanodine receptor. Coexpression of both release mechanisms could be required for the production of rapid light-induced Ca2+ elevations, because Ca2+ amplifies its own release through both pathways by a positive feedback. CICR may also mediate the spatial spread of Ca2+ release from the submicrovillar ER toward more remote ER subregions, thereby activating Ca(2+)-sensitive cell processes that are not directly involved in phototransduction. PMID:7608657

  1. Polymorphism of Ca2+ Sparks Evoked from In-Focus Ca2+ Release Units in Cardiac Myocytes

    PubMed Central

    Shen, Jian-Xin; Wang, ShiQiang; Song, Long-Sheng; Han, Taizhen; Cheng, Heping

    2004-01-01

    Ca2+ sparks are the elementary release events in many types of cells. Here we present a morphometric analysis of Ca2+ sparks (i.e., amplitude and kinetic parameters) using an approach that minimizes the confounding factor of the detection of out-of-focus events. By activation and visualization of Ca2+ sparks from Ca2+ release units under loose-seal patch-clamp conditions, we found that the amplitude and rising rate of in-focus sparks exhibited a broad modal distribution, whereas spark rise time and spatial width appeared to be stereotyped. Spark morphometrics were constant irrespective of the latency of spark production and the time-dependent L-type Ca2+ channel activation. Polymorphism of Ca2+ sparks in terms of variable amplitude and rising rate was evident for events from the same release units, and intra- and interrelease unit variability contributed equally to the overall variability. The rising rate, a reporter of the underlying Ca2+ release flux, displayed a strong positive correlation with spark amplitude, but a negative correlation with spark rise time, an index of Ca2+ release duration. On the basis of Ca2+ spark morphometrics measured here, we suggested a model in which cohorts of variable number of ryanodine receptors are activated in the genesis of Ca2+ sparks, and the ensuing negative feedback overrides the regenerative Ca2+-induced Ca2+ release to extinguish the ongoing Ca2+ spark. PMID:14695261

  2. Graded Ca2+/calmodulin-dependent coupling of voltage-gated CaV1.2 channels

    PubMed Central

    Dixon, Rose E; Moreno, Claudia M; Yuan, Can; Opitz-Araya, Ximena; Binder, Marc D; Navedo, Manuel F; Santana, Luis F

    2015-01-01

    In the heart, reliable activation of Ca2+ release from the sarcoplasmic reticulum during the plateau of the ventricular action potential requires synchronous opening of multiple CaV1.2 channels. Yet the mechanisms that coordinate this simultaneous opening during every heartbeat are unclear. Here, we demonstrate that CaV1.2 channels form clusters that undergo dynamic, reciprocal, allosteric interactions. This ‘functional coupling’ facilitates Ca2+ influx by increasing activation of adjoined channels and occurs through C-terminal-to-C-terminal interactions. These interactions are initiated by binding of incoming Ca2+ to calmodulin (CaM) and proceed through Ca2+/CaM binding to the CaV1.2 pre-IQ domain. Coupling fades as [Ca2+]i decreases, but persists longer than the current that evoked it, providing evidence for ‘molecular memory’. Our findings suggest a model for CaV1.2 channel gating and Ca2+-influx amplification that unifies diverse observations about Ca2+ signaling in the heart, and challenges the long-held view that voltage-gated channels open and close independently. DOI: http://dx.doi.org/10.7554/eLife.05608.001 PMID:25714924

  3. The EF-Hand Ca2+ Binding Protein MICU Choreographs Mitochondrial Ca2+ Dynamics in Arabidopsis[OPEN

    PubMed Central

    Carraretto, Luca; Teardo, Enrico; Cendron, Laura; Füßl, Magdalena; Doccula, Fabrizio G.; Szabò, Ildikò

    2015-01-01

    Plant organelle function must constantly adjust to environmental conditions, which requires dynamic coordination. Ca2+ signaling may play a central role in this process. Free Ca2+ dynamics are tightly regulated and differ markedly between the cytosol, plastid stroma, and mitochondrial matrix. The mechanistic basis of compartment-specific Ca2+ dynamics is poorly understood. Here, we studied the function of At-MICU, an EF-hand protein of Arabidopsis thaliana with homology to constituents of the mitochondrial Ca2+ uniporter machinery in mammals. MICU binds Ca2+ and localizes to the mitochondria in Arabidopsis. In vivo imaging of roots expressing a genetically encoded Ca2+ sensor in the mitochondrial matrix revealed that lack of MICU increased resting concentrations of free Ca2+ in the matrix. Furthermore, Ca2+ elevations triggered by auxin and extracellular ATP occurred more rapidly and reached higher maximal concentrations in the mitochondria of micu mutants, whereas cytosolic Ca2+ signatures remained unchanged. These findings support the idea that a conserved uniporter system, with composition and regulation distinct from the mammalian machinery, mediates mitochondrial Ca2+ uptake in plants under in vivo conditions. They further suggest that MICU acts as a throttle that controls Ca2+ uptake by moderating influx, thereby shaping Ca2+ signatures in the matrix and preserving mitochondrial homeostasis. Our results open the door to genetic dissection of mitochondrial Ca2+ signaling in plants. PMID:26530087

  4. T-type Ca2+ channel modulation by otilonium bromide

    PubMed Central

    Strege, Peter R.; Sha, Lei; Beyder, Arthur; Bernard, Cheryl E.; Perez-Reyes, Edward; Evangelista, Stefano; Gibbons, Simon J.; Szurszewski, Joseph H.

    2010-01-01

    Antispasmodics are used clinically to treat a variety of gastrointestinal disorders by inhibition of smooth muscle contraction. The main pathway for smooth muscle Ca2+ entry is through L-type channels; however, there is increasing evidence that T-type Ca2+ channels also play a role in regulating contractility. Otilonium bromide, an antispasmodic, has previously been shown to inhibit L-type Ca2+ channels and colonic contractile activity. The objective of this study was to determine whether otilonium bromide also inhibits T-type Ca2+ channels. Whole cell currents were recorded by patch-clamp technique from HEK293 cells transfected with cDNAs encoding the T-type Ca2+ channels, CaV3.1 (α1G), CaV3.2 (α1H), or CaV3.3 (α1I) alpha subunits. Extracellular solution was exchanged with otilonium bromide (10−8 to 10−5 M). Otilonium bromide reversibly blocked all T-type Ca2+ channels with a significantly greater affinity for CaV3.3 than CaV3.1 or CaV3.2. Additionally, the drug slowed inactivation in CaV3.1 and CaV3.3. Inhibition of T-type Ca2+ channels may contribute to inhibition of contractility by otilonium bromide. This may represent a new mechanism of action for antispasmodics and may contribute to the observed increased clinical effectiveness of antispasmodics compared with selective L-type Ca2+ channel blockers. PMID:20203058

  5. Ca++ induced hypothermia in a hibernator /Citellus beechyi/

    NASA Technical Reports Server (NTRS)

    Hanegan, J. L.; Williams, B. A.

    1975-01-01

    Results of perfusion of excess Ca++ and Na+ into the hypothalamus of the hibernating ground squirrel Citellus beechyi are presented. The significant finding is that perfused excess Ca++ causes a reduction in core temperature when ambient temperature is low (12 C). Ca++ also causes a rise in rectal temperature at high ambient temperature (33 C). Thus hypothalamic Ca++ perfusion apparently causes a nonspecific depression of thermoregulatory control.

  6. High precision calcium isotope analysis using 42Ca-48Ca double-spike TIMS technique

    NASA Astrophysics Data System (ADS)

    Feng, L.; Zhou, L.; Gao, S.; Tong, S. Y.; Zhou, M. L.

    2014-12-01

    Double spike techniques are widely used for determining calcium isotopic compositions of natural samples. The most important factor controlling precision of the double spike technique is the choice of appropriate spike isotope pair, the composition of double spikes and the ratio of spike to sample(CSp/CN). We propose an optimal 42Ca-48Ca double spike protocol which yields the best internal precision for calcium isotopic composition determinations among all kinds of spike pairs and various spike compositions and ratios of spike to sample, as predicted by linear error propagation method. It is suggested to use spike composition of 42Ca/(42Ca+48Ca) = 0.44 mol/mol and CSp/(CN+ CSp)= 0.12mol/mol because it takes both advantages of the largest mass dispersion between 42Ca and 48Ca (14%) and lowest spike cost. Spiked samples were purified by pass through homemade micro-column filled with Ca special resin. K, Ti and other interference elements were completely separated, while 100% calcium was recovered with negligible blank. Data collection includes integration time, idle time, focus and peakcenter frequency, which were all carefully designed for the highest internal precision and lowest analysis time. All beams were automatically measured in a sequence by Triton TIMS so as to eliminate difference of analytical conditions between samples and standards, and also to increase the analytical throughputs. The typical internal precision of 100 duty cycles for one beam is 0.012‒0.015 ‰ (2δSEM), which agrees well with the predicted internal precision of 0.0124 ‰ (2δSEM). Our methods improve internal precisions by a factor of 2‒10 compared to previous methods of determination of calcium isotopic compositions by double spike TIMS. We analyzed NIST SRM 915a, NIST SRM 915b and Pacific Seawater as well as interspersed geological samples during two months. The obtained average δ44/40Ca (all relative to NIST SRM 915a) is 0.02 ± 0.02 ‰ (n=28), 0.72±0.04 ‰ (n=10) and 1

  7. 21. ORIGINAL COMPANY HOUSE AT CORNER OF SANTA ANA AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. ORIGINAL COMPANY HOUSE AT CORNER OF SANTA ANA AND ANAHEIM BLVDS. (BEHIND HOUSE IN CA-242-20), WHICH IS BEING PREPARED FOR DEMOLITION. - Gene Pump Plant, South of Gene Wash Reservoir, 2 miles west of Whitsett Pump Plant, Parker Dam, San Bernardino County, CA

  8. Characterization of materials for Ca/CaCrO/sub 4/ thermal batteries

    SciTech Connect

    Guidotti, R.A.; Reinhardt, F.W.; Poole, R.L.

    1982-01-01

    The performance of pelletized Ca/CaCrO/sub 4/ thermal batteries is known to be sensitive to processing of the catholyte or DEB mix, which consists of CaCrO/sub 4/ depolarizer(D), KCl-LiCl eutectic electrolyte(E), and SiO/sub 2/ binder(B). The chemical composition of the DEB mix affects the electrochemical behavior. Little work has been reported, however, for the characterization of DEB mixes in relation to their performance in Ca/CaCrO/sub 4/ thermal batteries. Considerable variability of battery performance has also been observed when different lots of sheet calcium are used with the same DEB. The causes for this behavior remain elusive. In an effort to resolve these discrepancies in materials behavior, a study was carried out to characterize DEB powders and pellets and, to a lesser extent, sheet calcium, with the primary objective of correlating observed battery performance to easily measured physical and chemical properties. A secondary objective was to examine the suitability of such techniques for process control and quality assurance during battery production. Results are presented and discussed.

  9. High-capacity Ca2+ Binding of Human Skeletal Calsequestrin*

    PubMed Central

    Sanchez, Emiliano J.; Lewis, Kevin M.; Danna, Benjamin R.; Kang, ChulHee

    2012-01-01

    Calsequestrin, the major calcium storage protein in both cardiac and skeletal muscle, binds large amounts of Ca2+ in the sarcoplasmic reticulum and releases them during muscle contraction. For the first time, the crystal structures of Ca2+ complexes for both human (hCASQ1) and rabbit (rCASQ1) skeletal calsequestrin were determined, clearly defining their Ca2+ sequestration capabilities through resolution of high- and low-affinity Ca2+-binding sites. rCASQ1 crystallized in low CaCl2 buffer reveals three high-affinity Ca2+ sites with trigonal bipyramidal, octahedral, and pentagonal bipyramidal coordination geometries, along with three low-affinity Ca2+ sites. hCASQ1 crystallized in high CaCl2 shows 15 Ca2+ ions, including the six Ca2+ ions in rCASQ1. Most of the low-affinity sites, some of which are μ-carboxylate-bridged, are established by the rotation of dimer interfaces, indicating cooperative Ca2+ binding that is consistent with our atomic absorption spectroscopic data. On the basis of these findings, we propose a mechanism for the observed in vitro and in vivo dynamic high-capacity and low-affinity Ca2+-binding activity of calsequestrin. PMID:22337878

  10. Memory retrieval along the proximodistal axis of CA1.

    PubMed

    Nakazawa, Yuki; Pevzner, Aleksandr; Tanaka, Kazumasa Z; Wiltgen, Brian J

    2016-09-01

    The proximal and distal segments of CA1 are thought to perform distinct computations. Neurons in proximal CA1 are reciprocally connected with the medial entorhinal cortex (MEC) and exhibit precise spatial firing. In contrast, cells in distal CA1 communicate with the lateral entorhinal cortex (LEC), exhibit more diffuse spatial firing and are affected by the presence of objects in the environment. To determine if these segments make unique contributions to memory retrieval, we examined cellular activity along the proximodistal axis of CA1 using transgenic reporter mice. Neurons tagged during context learning in proximal CA1 were more likely to be reactivated during testing than those in distal CA1. This was true following context fear conditioning and after exposure to a novel environment. Reactivation was also higher in brain regions connected to proximal CA1 (MEC, distal CA3) than those connected to the distal segment (LEC, proximal CA3). To examine contributions to memory retrieval, we performed neurotoxic lesions of proximal or distal CA1 after training. Lesions of the proximal segment significantly impaired memory retrieval while damage to distal CA1 had no effect. These data suggest that context memories are retrieved by a hippocampal microcircuit that involves the proximal but not distal segment of CA1. © 2016 Wiley Periodicals, Inc. PMID:27068122

  11. Registration of CA0469C025C chickpea germplasm

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Chickpea (Cicer arientinum L.) germplasm CA0469C025C (Reg. No. XXX; PI XXX), was released by the USDA-ARS in 2010. CA0469C025C was released based on its improved yield and reaction to Ascochyta blight relative to the popular commercial cultivars ‘Dwelley’, ‘Sierra’, and ‘Sawyer’. CA0490C025C is deri...

  12. 78 FR 36655 - Drawbridge Operation Regulation; Carquinez Strait, Martinez, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-19

    ... SECURITY Coast Guard 33 CFR Part 117 Drawbridge Operation Regulation; Carquinez Strait, Martinez, CA AGENCY... Drawbridge across the Carquinez Strait, mile 7.0 at Martinez, CA. The deviation is necessary to perform a..., at Martinez, CA. The drawbridge navigation span provides 135 feet vertical clearance above Mean...

  13. 33 CFR 110.210 - San Diego Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Diego Harbor, CA. 110.210... ANCHORAGE REGULATIONS Anchorage Grounds § 110.210 San Diego Harbor, CA. (a) The anchorage grounds. (1... Commander, Naval Base, San Diego, CA. The administration of these anchorages is exercised by the...

  14. 33 CFR 110.210 - San Diego Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Diego Harbor, CA. 110.210... ANCHORAGE REGULATIONS Anchorage Grounds § 110.210 San Diego Harbor, CA. (a) The anchorage grounds. (1... Commander, Naval Base, San Diego, CA. The administration of these anchorages is exercised by the...

  15. Electronic structure of Ca, Sr, and Ba under pressure.

    NASA Technical Reports Server (NTRS)

    Animalu, A. O. E.; Heine, V.; Vasvari, B.

    1967-01-01

    Electronic band structure calculations phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure electronic band structure calculations for fcc phase of Ca, Sr and Ba over wide range of atomic volumes under pressure

  16. Concanavalin A-stimulated Ca2+ uptake in rat splenocytes.

    PubMed

    Larner, A; Rebhun, L I; Larner, J; Oron, Y

    1980-11-20

    Commercially available concanavalin A binds Ca2+ with high apparent affinity. In order to dissociate concanavalin A stimulated Ca2+ uptake (defined as an increased association of 45Ca2+ with cells) in rat splenocytes and Ca2+ binding to cell-bound concanavalin A, conditions were developed to remove more than 75% of the bound concanavalin A. Under these conditions concanavalin A treated cells showed a considerable increase in 45Ca2+ uptake over control. The concanavalin A stimulated uptake of 45Ca2+ occurred within minutes, and required concentrations of concanavalin A which promoted [3H]thymidine uptake into these cells. Succinyl concanavalin A was less potent in promoting Ca2+ uptake than concanavalin A. Sodium periodate inhibited Ca2+ uptake at concentrations which promoted 3H-thymidine incorporation into splenocytes. It is concluded that concanavalin A promotes Ca2+ uptake which is not due to binding of 45Ca2+ to concanavalin A. Although the concanavalin A-promoted Ca2+ uptake occurs at lectin concentrations that cause lymphocyte proliferation as measured by 3H-thymidine incorporation, the role of Ca2+ in this event remains unclear.

  17. The effect of CaF2 on thermodynamics of CaO-CaF2-SiO2(-MgO) slags

    NASA Astrophysics Data System (ADS)

    Choi, Chul-Hwan; Jo, Sung-Koo; Kim, Seon-Hyo; Lee, Kwang-Ro; Kim, Jeong-Tae

    2004-02-01

    To address the role of CaF2 in the CaO-CaF2-SiO2(-MgO) slag system employed for the production of low-pressure rotor steels, the thermodynamic aspects of the slag were investigated by equilibrating it with liquid iron at 1873 K in CaO or MgO crucibles. Presaturation of slag with an oxide block piece of CaO or MgO in a Pt crucible and application of a carbon paste to the outside of an oxide crucible were designed to prevent crucible failure during the slag-metal experiments. The liquidus isotherm and phase boundary of the preceding slag system were investigated using the slag-metal equilibria. Also, the effect of CaF2 on the sulfide capacity and the activity coefficient of Fe t O were of particular interest in controlling the sulfur level and cleanliness of low-pressure rotor steels.

  18. CaMKII-dependent phosphorylation regulates basal cardiac pacemaker function via modulation of local Ca2+ releases.

    PubMed

    Li, Yue; Sirenko, Syevda; Riordon, Daniel R; Yang, Dongmei; Spurgeon, Harold; Lakatta, Edward G; Vinogradova, Tatiana M

    2016-09-01

    Spontaneous beating of the heart pacemaker, the sinoatrial node, is generated by sinoatrial node cells (SANC) due to gradual change of the membrane potential called diastolic depolarization (DD). Spontaneous, submembrane local Ca(2+) releases (LCR) from ryanodine receptors (RyR) occur during late DD and activate an inward Na(+)/Ca(2+)exchange current to boost the DD rate and fire an action potential (AP). Here we studied the extent of basal Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) activation and the role of basal CaMKII-dependent protein phosphorylation in generation of LCRs and regulation of normal automaticity of intact rabbit SANC. The basal level of activated (autophosphorylated) CaMKII in rabbit SANC surpassed that in ventricular myocytes (VM) by approximately twofold, and this was accompanied by high basal level of protein phosphorylation. Specifically, phosphorylation of phospholamban (PLB) at the CaMKII-dependent Thr(17) site was approximately threefold greater in SANC compared with VM, and RyR phosphorylation at CaMKII-dependent Ser(2815) site was ∼10-fold greater in the SA node, compared with that in ventricle. CaMKII inhibition reduced phosphorylation of PLB and RyR, decreased LCR size, increased LCR periods (time from AP-induced Ca(2+) transient to subsequent LCR), and suppressed spontaneous SANC firing. Graded changes in CaMKII-dependent phosphorylation (indexed by PLB phosphorylation at the Thr(17)site) produced by CaMKII inhibition, β-AR stimulation or phosphodiesterase inhibition were highly correlated with changes in SR Ca(2+) replenishment times and LCR periods and concomitant changes in spontaneous SANC cycle lengths (R(2) = 0.96). Thus high basal CaMKII activation modifies the phosphorylation state of Ca(2+) cycling proteins PLB, RyR, L-type Ca(2+) channels (and likely others), adjusting LCR period and characteristics, and ultimately regulates both normal and reserve cardiac pacemaker function. PMID:27402669

  19. Biological fractionation of stable Ca isotopes in Göttingen minipigs as a physiological model for Ca homeostasis in humans.

    PubMed

    Heuser, Alexander; Eisenhauer, Anton; Scholz-Ahrens, Katharina E; Schrezenmeir, Jürgen

    2016-12-01

    In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ(44/40)Ca = [((44)Ca/(40)Ca)sample/((44)Ca/(40)Ca)reference]-1) of diet, faeces, blood, bones and urine from Göttingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (-CaD). In contrast to Con and GIO whose average δ(44/40)Cafaeces values (0.39 ± 0.13‰ and 0.28 ± 0.08‰, respectively) tend to be lower than their diet (0.47 ± 0.02‰), δ(44/40)Cafaeces of -CaD (-0.27 ± 0.21‰) was significantly lower than their δ(44/40)Cadiet (0.37 ± 0.03‰), but also lower than δ(44/40)Cafaeces of Con and GIO. We suggest that the low δ(44/40)Cafaeces of -CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ(44/40)Cafaeces of Con and GIO. The δ(44/40)Caurine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Göttingen minipigs we found a Ca isotope fractionation between blood and bones (Δ(44/40)Cablood-bone) of 0.68 ± 0.15‰.

  20. Reorientable dipolar CuCa antisite and anomalous screening in CaCu3Ti4O12

    NASA Astrophysics Data System (ADS)

    Delugas, Pietro; Alippi, Paola; Fiorentini, Vincenzo; Raineri, Vito

    2010-02-01

    Based on first-principles calculations, we show that the abundant CuCa antisite defect contributes sizably to dielectric screening in single-crystal CaCu3Ti4O12 . CuCa has a multi-minimum off-center equilibrium configuration, whereby it possesses a large and easily reorientable dipole moment. The low-temperature and frequency cut-off behavior of CuCa -induced response is consistent with experiment.

  1. Superdeformed and Triaxial States in 42Ca

    NASA Astrophysics Data System (ADS)

    Hadyńska-KlÈ©k, K.; Napiorkowski, P. J.; Zielińska, M.; Srebrny, J.; Maj, A.; Azaiez, F.; Valiente Dobón, J. J.; Kicińska-Habior, M.; Nowacki, F.; Naïdja, H.; Bounthong, B.; Rodríguez, T. R.; de Angelis, G.; Abraham, T.; Anil Kumar, G.; Bazzacco, D.; Bellato, M.; Bortolato, D.; Bednarczyk, P.; Benzoni, G.; Berti, L.; Birkenbach, B.; Bruyneel, B.; Brambilla, S.; Camera, F.; Chavas, J.; Cederwall, B.; Charles, L.; Ciemała, M.; Cocconi, P.; Coleman-Smith, P.; Colombo, A.; Corsi, A.; Crespi, F. C. L.; Cullen, D. M.; Czermak, A.; Désesquelles, P.; Doherty, D. T.; Dulny, B.; Eberth, J.; Farnea, E.; Fornal, B.; Franchoo, S.; Gadea, A.; Giaz, A.; Gottardo, A.; Grave, X.; GrÈ©bosz, J.; Görgen, A.; Gulmini, M.; Habermann, T.; Hess, H.; Isocrate, R.; Iwanicki, J.; Jaworski, G.; Judson, D. S.; Jungclaus, A.; Karkour, N.; Kmiecik, M.; Karpiński, D.; Kisieliński, M.; Kondratyev, N.; Korichi, A.; Komorowska, M.; Kowalczyk, M.; Korten, W.; Krzysiek, M.; Lehaut, G.; Leoni, S.; Ljungvall, J.; Lopez-Martens, A.; Lunardi, S.; Maron, G.; Mazurek, K.; Menegazzo, R.; Mengoni, D.; Merchán, E.; MÈ©czyński, W.; Michelagnoli, C.; Mierzejewski, J.; Million, B.; Myalski, S.; Napoli, D. R.; Nicolini, R.; Niikura, M.; Obertelli, A.; Özmen, S. F.; Palacz, M.; Próchniak, L.; Pullia, A.; Quintana, B.; Rampazzo, G.; Recchia, F.; Redon, N.; Reiter, P.; Rosso, D.; Rusek, K.; Sahin, E.; Salsac, M.-D.; Söderström, P.-A.; Stefan, I.; Stézowski, O.; Styczeń, J.; Theisen, Ch.; Toniolo, N.; Ur, C. A.; Vandone, V.; Wadsworth, R.; Wasilewska, B.; Wiens, A.; Wood, J. L.; Wrzosek-Lipska, K.; ZiÈ©bliński, M.

    2016-08-01

    Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in 42Ca were determined from E 2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 02+ has been obtained and the role of triaxiality in the A ˜40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time.

  2. San Francisco and Bay Area, CA, USA

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This cloud free color infrared view of San Francisco and Bay Area, CA (38.0N, 122.5W) is unusual because the city is normally concealed from view by clouds and fog. Gray tones represent urban areas and the red toned areas are vegetated. Within the city, parks easily stand out from the well-developed parts of the city as enclaves of color. The trace of the San Andreas fault shows as a straight valley running across the San Francisco peninsula.

  3. Mechanics of Old Faithful Geyser, Calistoga, CA

    USGS Publications Warehouse

    Rudolph, M.L.; Manga, M.; Hurwitz, Shaul; Johnston, Malcolm J.; Karlstrom, L.; Wang, Chun-Yong

    2012-01-01

    In order to probe the subsurface dynamics associated with geyser eruptions, we measured ground deformation at Old Faithful Geyser of Calistoga, CA. We present a physical model in which recharge during the period preceding an eruption is driven by pressure differences relative to the aquifer supplying the geyser. The model predicts that pressure and ground deformation are characterized by an exponential function of time, consistent with our observations. The geyser's conduit is connected to a reservoir at a depth of at least 42 m, and pressure changes in the reservoir can produce the observed ground deformations through either a poroelastic or elastic mechanical model.

  4. Superdeformed and Triaxial States in ^{42}Ca.

    PubMed

    Hadyńska-Klȩk, K; Napiorkowski, P J; Zielińska, M; Srebrny, J; Maj, A; Azaiez, F; Valiente Dobón, J J; Kicińska-Habior, M; Nowacki, F; Naïdja, H; Bounthong, B; Rodríguez, T R; de Angelis, G; Abraham, T; Anil Kumar, G; Bazzacco, D; Bellato, M; Bortolato, D; Bednarczyk, P; Benzoni, G; Berti, L; Birkenbach, B; Bruyneel, B; Brambilla, S; Camera, F; Chavas, J; Cederwall, B; Charles, L; Ciemała, M; Cocconi, P; Coleman-Smith, P; Colombo, A; Corsi, A; Crespi, F C L; Cullen, D M; Czermak, A; Désesquelles, P; Doherty, D T; Dulny, B; Eberth, J; Farnea, E; Fornal, B; Franchoo, S; Gadea, A; Giaz, A; Gottardo, A; Grave, X; Grȩbosz, J; Görgen, A; Gulmini, M; Habermann, T; Hess, H; Isocrate, R; Iwanicki, J; Jaworski, G; Judson, D S; Jungclaus, A; Karkour, N; Kmiecik, M; Karpiński, D; Kisieliński, M; Kondratyev, N; Korichi, A; Komorowska, M; Kowalczyk, M; Korten, W; Krzysiek, M; Lehaut, G; Leoni, S; Ljungvall, J; Lopez-Martens, A; Lunardi, S; Maron, G; Mazurek, K; Menegazzo, R; Mengoni, D; Merchán, E; Mȩczyński, W; Michelagnoli, C; Mierzejewski, J; Million, B; Myalski, S; Napoli, D R; Nicolini, R; Niikura, M; Obertelli, A; Özmen, S F; Palacz, M; Próchniak, L; Pullia, A; Quintana, B; Rampazzo, G; Recchia, F; Redon, N; Reiter, P; Rosso, D; Rusek, K; Sahin, E; Salsac, M-D; Söderström, P-A; Stefan, I; Stézowski, O; Styczeń, J; Theisen, Ch; Toniolo, N; Ur, C A; Vandone, V; Wadsworth, R; Wasilewska, B; Wiens, A; Wood, J L; Wrzosek-Lipska, K; Ziȩbliński, M

    2016-08-01

    Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in ^{42}Ca were determined from E2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 0_{2}^{+} has been obtained and the role of triaxiality in the A∼40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time.

  5. Leukocyte alkaline phosphatase, CA15-3, CA125, and CEA in cancer patients.

    PubMed

    Walach, N; Gur, Y

    1998-01-01

    Peripheral blood leukocyte alkaline phosphatase (LAP) scores and CA15-3, CA125, and CEA levels in plasma were measured in 57 patients with metastatic breast, ovarian, and colorectal cancer, respectively, and in 79 patients with the same types of nonmetastatic cancer. The mean LAP scores of the metastatic cancer patients (261, 272 and 275 for breast, ovary and colon, respectively) were significantly higher than those of the nonmetastatic cancer group (70, 68 and 57, respectively). There was no overlap between the 95% confidence intervals of the two groups (i.e., metastatic versus nonmetastatic), and no patient known to be metastatic had a LAP score within the normal range. The mean levels of other markers in the metastatic patients (CA15-3, 63.4 mu/ml; CA125, 104.8 mu/ml; and CEA, 51.8 ng/ml for metastatic breast, ovarian, and colon cancer, respectively) were also higher than in the nonmetastatic patients (CA15-3, 24 mu/ml; CA125, 25.3 mu/ml; and CEA, 5.8 ng/ml for nonmetastatic breast, ovarian, and colon cancer, respectively). However, the 95% confidence intervals of the nonmetastatic and the metastatic patients overlapped so that there were false-negatives and/or false-positives when the other markers were used. We therefore conclude that the addition of the LAP score to conventional cancer markers could be helpful for the diagnosis of recurrence and follow-up of cancer patients and suggest that our results be confirmed by further studies on a larger series of patients.

  6. Ca2+ Sparks and Ca2+ Waves are the subcellular events underlying Ca2+ overload during ischemia and reperfusion in perfused intact hearts

    PubMed Central

    Alicia, Mattiazzi; Mariana, Argenziano; Yuriana, Aguilar-Sanchez; Gabriela, Mazzocchi; Escobar Ariel, L.

    2014-01-01

    Abnormal intracellular Ca2+ cycling plays a key role in cardiac dysfunction, particularly during the setting of ischemia/reperfusion (I/R). During ischemia there is an increase in cytosolic and sarcoplasmic reticulum (SR) Ca2+. At the onset of reperfusion there is a transient and abrupt increase in cytosolic Ca2+ which occurs timely associated with reperfusion arrhythmias. However, little is known about the subcellular dynamics of Ca2+ increase during I/R and a possible role of the SR as a mechanism underlying this increase has been previously overlooked. The aim of the present work is to test two main hypotheses: 1. An increase in the frequency of diastolic Ca2+ sparks (cspf) constitutes a mayor substrate for the ischemia-induced diastolic Ca2+ increase; 2. An increase in cytosolic Ca2+ pro-arrhythmogenic events (Ca2+ waves), mediates the abrupt diastolic Ca2+ rise at the onset of reperfusion. We used confocal microscopy on mouse intact hearts loaded with Fluo-4. Hearts were submitted to global I/R (12/30 min) to assess epicardial Ca2+ sparks in the whole heart. Intact heart sparks were faster than in isolated myocytes whereas cspf was not different. During ischemia, cspf significantly increased relative to preischemia (2.07±0.33 vs. 1.13±0.20 sp/sec/100μm, n=29/34, 7 hearts). Reperfusion significantly changed Ca2+ sparks kinetics, by prolonging Ca2+ sparks rise time and decreased cspf. However it significantly increased Ca2+ wave frequency relative to ischemia (0.71±0.14 vs. 0.38±0.06 w/sec/100μm, n=32/33, 7 hearts). The results show for the first time the assessment of intact perfused heart Ca2+ sparks and provides direct evidence of increased Ca2+ sparks in ischemia that transform into Ca2+ waves during reperfusion. These waves may constitute a main trigger of reperfusion arrhythmias. PMID:25451173

  7. Ca2+/calmodulin kinase II increases ryanodine binding and Ca2+-induced sarcoplasmic reticulum Ca2+ release kinetics during β-adrenergic stimulation

    PubMed Central

    Ferrero, Paola; Said, Matilde; Sánchez, Gina; Vittone, Leticia; Valverde, Carlos; Donoso, Paulina; Mattiazzi, Alicia; Mundiña-Weilenmann, Cecilia

    2007-01-01

    We aimed to define the relative contribution of both PKA and Ca2+/calmodulin-dependent protein kinase II (CaMKII) cascades to the phosphorylation of RyR2 and the activity of the channel during β-adrenergic receptor (βAR) stimulation. Rat hearts were perfused with increasing concentrations of the β-agonist isoproterenol in the absence and the presence of CaMKII inhibition. CaMKII was inhibited either by preventing the Ca2+ influx to the cell by low [Ca]o plus nifedipine or by the specific inhibitor KN-93. We immunodetected RyR2 phosphorylated at Ser2809 (PKA and putative CaMKII site) and at Ser2815 (CaMKII site) and measured [3H]-ryanodine binding and fast Ca2+ release kinetics in sarcoplasmic reticulum (SR) vesicles. SR vesicles were isolated in conditions that preserved the phosphorylation levels achieved in the intact heart and were actively and equally loaded with Ca2+. Our results demonstrated that Ser2809 and Ser2815 of RyR2 were dose-dependently phosphorylated under βAR stimulation by PKA and CaMKII, respectively. The isoproterenol-induced increase in the phosphorylation of Ser2815 site was prevented by the PKA inhibitor H-89 and mimicked by forskolin. CaMKII-dependent phosphorylation of RyR2 (but not PKA-dependent phosphorylation) was responsible for the β-induced increase in the channel activity as indicated by the enhancement of the [3H]-ryanodine binding and the velocity of fast SR Ca2+ release. The present results show for the first time a dose-dependent increase in the phosphorylation of Ser2815 of RyR2 through the PKA-dependent activation of CaMKII and a predominant role of CaMKII-dependent phosphorylation of RyR2, over that of PKA-dependent phosphorylation, on SR-Ca2+ release during βAR stimulation. PMID:17643448

  8. Encoding, consolidation, and retrieval of contextual memory: differential involvement of dorsal CA3 and CA1 hippocampal subregions.

    PubMed

    Daumas, Stéphanie; Halley, Hélène; Francés, Bernard; Lassalle, Jean-Michel

    2005-01-01

    Studies on human and animals shed light on the unique hippocampus contributions to relational memory. However, the particular role of each hippocampal subregion in memory processing is still not clear. Hippocampal computational models and theories have emphasized a unique function in memory for each hippocampal subregion, with the CA3 area acting as an autoassociative memory network and the CA1 area as a critical output structure. In order to understand the respective roles of the CA3- and CA1-hippocampal areas in the formation of contextual memory, we studied the effects of the reversible inactivation by lidocaine of the CA3 or CA1 areas of the dorsal hippocampus on acquisition, consolidation, and retrieval of a contextual fear conditioning. Whereas infusions of lidocaine never impaired elementary tone conditioning, their effects on contextual conditioning provided interesting clues about the role of these two hippocampal regions. They demonstrated first that the CA3 area is necessary for the rapid elaboration of a unified representation of the context. Secondly, they suggested that the CA1 area is rather involved in the consolidation process of contextual memory. Third, they showed that CA1 or CA3 inactivation during retention test has no effect on contextual fear retrieval when a recognition memory procedure is used. In conclusion, our findings point as evidence that CA1 and CA3 subregions of the dorsal hippocampus play important and different roles in the acquisition and consolidation of contextual fear memory, whereas they are not required for context recognition.

  9. Ca(2+) homeostasis in the budding yeast Saccharomyces cerevisiae: Impact of ER/Golgi Ca(2+) storage.

    PubMed

    D'hooge, Petra; Coun, Catherina; Van Eyck, Vincent; Faes, Liesbeth; Ghillebert, Ruben; Mariën, Lore; Winderickx, Joris; Callewaert, Geert

    2015-08-01

    Yeast has proven to be a powerful tool to elucidate the molecular aspects of several biological processes in higher eukaryotes. As in mammalian cells, yeast intracellular Ca(2+) signalling is crucial for a myriad of biological processes. Yeast cells also bear homologs of the major components of the Ca(2+) signalling toolkit in mammalian cells, including channels, co-transporters and pumps. Using yeast single- and multiple-gene deletion strains of various plasma membrane and organellar Ca(2+) transporters, combined with manipulations to estimate intracellular Ca(2+) storage, we evaluated the contribution of individual transport systems to intracellular Ca(2+) homeostasis. Yeast strains lacking Pmr1 and/or Cod1, two ion pumps implicated in ER/Golgi Ca(2+) homeostasis, displayed a fragmented vacuolar phenotype and showed increased vacuolar Ca(2+) uptake and Ca(2+) influx across the plasma membrane. In the pmr1Δ strain, these effects were insensitive to calcineurin activity, independent of Cch1/Mid1 Ca(2+) channels and Pmc1 but required Vcx1. By contrast, in the cod1Δ strain increased vacuolar Ca(2+) uptake was not affected by Vcx1 deletion but was largely dependent on Pmc1 activity. Our analysis further corroborates the distinct roles of Vcx1 and Pmc1 in vacuolar Ca(2+) uptake and point to the existence of not-yet identified Ca(2+) influx pathways.

  10. Ca2+ entry into neurons is facilitated by cooperative gating of clustered CaV1.3 channels

    PubMed Central

    Moreno, Claudia M; Dixon, Rose E; Tajada, Sendoa; Yuan, Can; Opitz-Araya, Ximena; Binder, Marc D; Santana, Luis F

    2016-01-01

    CaV1.3 channels regulate excitability in many neurons. As is the case for all voltage-gated channels, it is widely assumed that individual CaV1.3 channels behave independently with respect to voltage-activation, open probability, and facilitation. Here, we report the results of super-resolution imaging, optogenetic, and electrophysiological measurements that refute this long-held view. We found that the short channel isoform (CaV1.3S), but not the long (CaV1.3L), associates in functional clusters of two or more channels that open cooperatively, facilitating Ca2+ influx. CaV1.3S channels are coupled via a C-terminus-to-C-terminus interaction that requires binding of the incoming Ca2+ to calmodulin (CaM) and subsequent binding of CaM to the pre-IQ domain of the channels. Physically-coupled channels facilitate Ca2+ currents as a consequence of their higher open probabilities, leading to increased firing rates in rat hippocampal neurons. We propose that cooperative gating of CaV1.3S channels represents a mechanism for the regulation of Ca2+ signaling and electrical activity. DOI: http://dx.doi.org/10.7554/eLife.15744.001 PMID:27187148

  11. Photolysis of caged compounds: studying Ca(2+) signaling and activation of Ca(2+)-dependent ion channels.

    PubMed

    Almassy, Janos; Yule, David I

    2013-01-01

    A wide variety of signaling molecules have been chemically modified by conjugation to a photolabile chromophore to render the substance temporarily biologically inert. Subsequent exposure to ultraviolet (UV) light can release the active moiety from the "caged" precursor in an experimentally controlled manner. This allows the concentration of active molecule to be precisely manipulated in both time and space. These techniques are particularly useful in experimental protocols designed to investigate the mechanisms underlying Ca(2+) signaling and the activation of Ca(2+)-dependent effectors.

  12. An integrated mechanism of cardiomyocyte nuclear Ca(2+) signaling.

    PubMed

    Ibarra, Cristián; Vicencio, Jose Miguel; Varas-Godoy, Manuel; Jaimovich, Enrique; Rothermel, Beverly A; Uhlén, Per; Hill, Joseph A; Lavandero, Sergio

    2014-10-01

    In cardiomyocytes, Ca(2+) plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca(2+) within subcellular microdomains: transcription is regulated by Ca(2+) release within nuclear microdomains, and excitation-contraction coupling is regulated by cytosolic Ca(2+). Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca(2+) signals. However, signaling pathways coupling surface receptor activation to nuclear Ca(2+) release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca(2+) signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca(2+) release from perinuclear Ca(2+) stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca(2+) release. In this review, we discuss mechanisms for the selective control of nuclear Ca(2+) signals with special focus on emerging models of agonist receptor activation.

  13. An integrated mechanism of cardiomyocyte nuclear Ca2+ signaling

    PubMed Central

    Ibarra, Cristián; Vicencio, Jose Miguel; Varas-Godoy, Manuel; Jaimovich, Enrique; Rothermel, Beverly A.; Uhlén, Per; Hill, Joseph A.; Lavandero, Sergio

    2015-01-01

    In cardiomyocytes, Ca2+ plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca2+ within subcellular microdomains: transcription is regulated by Ca2+ release within nuclear microdomains, and excitation–contraction coupling is regulated by cytosolic Ca2+. Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca2+ signals. However, signaling pathways coupling surface receptor activation to nuclear Ca2+ release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca2+ signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca2+ release from perinuclear Ca2+ stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca2+ release. In this review, we discuss mechanisms for the selective control of nuclear Ca2+ signals with special focus on emerging models of agonist receptor activation. PMID:24997440

  14. Influence of Ca2+ on tetracycline adsorption on montmorillonite.

    PubMed

    Parolo, M Eugenia; Avena, Marcelo J; Pettinari, Gisela R; Baschini, Miria T

    2012-02-15

    The adsorption of tetracycline (TC) on montmorillonite was studied as a function of pH and Ca(2+) concentration using a batch technique complemented with X-ray diffraction and transmission electron microscopy. In the absence of Ca(2+), TC adsorption was high at low pH and decreased as the pH increased. In the presence of Ca(2+), at least two different adsorption processes took place in the studied systems, i.e., cation exchange and Ca-bridging. Cation exchange was the prevailing process at pH<5, and thus, TC adsorption decreased by increasing total Ca(2+) concentration. On the contrary, Ca-bridging was the prevailing process at pH>5, and thus, TC adsorption increased by increasing Ca(2+) concentration. The pH 5 represents an isoadsorption pH where both adsorption processes compensate each other. TC adsorption became independent of Ca(2+) concentration at this pH. For TC adsorption on Ca(2+)-montmorillonite in 0.01 M NaCl experiments, the ratio adsorbed TC/retained Ca(2+) was close to 1 in the pH range of 5-9, indicating an important participation of Ca(2+) in the binding of TC to montmorillonite. X-ray diffraction and transmission electron microscopy showed that TC adsorption induced intercalation between montmorillonite layers forming a multiphase system with stacking of layers with and without intercalated TC. PMID:22189389

  15. Accretion rate of extraterrestrial 41Ca in Antarctic snow samples

    NASA Astrophysics Data System (ADS)

    Gómez-Guzmán, J. M.; Bishop, S.; Faestermann, T.; Famulok, N.; Fimiani, L.; Hain, K.; Jahn, S.; Korschinek, G.; Ludwig, P.; Rodrigues, D.

    2015-10-01

    Interplanetary Dust Particles (IDPs) are small grains, generally less than a few hundred micrometers in size. Their main source is the Asteroid Belt, located at 3 AU from the Sun, between Mars and Jupiter. During their flight from the Asteroid Belt to the Earth they are irradiated by galactic and solar cosmic rays (GCR and SCR), thus radionuclides are formed, like 41Ca and 53Mn. Therefore, 41Ca (T1/2 = 1.03 × 105 yr) can be used as a key tracer to determine the accretion rate of IDPs onto the Earth because there are no significant terrestrial sources for this radionuclide. The first step of this study consisted to calculate the production rate of 41Ca in IDPs accreted by the Earth during their travel from the Asteroid Belt. This production rate, used in accordance with the 41Ca/40Ca ratios that will be measured in snow samples from the Antarctica will be used to calculate the amount of extraterrestrial material accreted by the Earth per year. There challenges for this project are, at first, the much longer time for the flight needed by the IDPs to travel from the Asteroid Belt to the Earth in comparison with the 41Ca half-life yields an early saturation for the 41Ca/40Ca ratio, and second, the importance of selecting the correct sampling site to avoid a high influx of natural 40Ca, preventing dilution of the 41Ca/40Ca ratio, the quantity measured by AMS.

  16. Ca(2+)(cyt) negatively regulates the initiation of oocyte maturation.

    PubMed

    Sun, Lu; Machaca, Khaled

    2004-04-01

    Ca(2+) is a ubiquitous intracellular messenger that is important for cell cycle progression. Genetic and biochemical evidence support a role for Ca(2+) in mitosis. In contrast, there has been a long-standing debate as to whether Ca(2+) signals are required for oocyte meiosis. Here, we show that cytoplasmic Ca(2+) (Ca(2+)(cyt)) plays a dual role during Xenopus oocyte maturation. Ca(2+) signals are dispensable for meiosis entry (germinal vesicle breakdown and chromosome condensation), but are required for the completion of meiosis I. Interestingly, in the absence of Ca(2+)(cyt) signals oocytes enter meiosis more rapidly due to faster activation of the MAPK-maturation promoting factor (MPF) kinase cascade. This Ca(2+)-dependent negative regulation of the cell cycle machinery (MAPK-MPF cascade) is due to Ca(2+)(cyt) acting downstream of protein kinase A but upstream of Mos (a MAPK kinase kinase). Therefore, high Ca(2+)(cyt) delays meiosis entry by negatively regulating the initiation of the MAPK-MPF cascade. These results show that Ca(2+) modulates both the cell cycle machinery and nuclear maturation during meiosis.

  17. Vascular CaMKII: heart and brain in your arteries.

    PubMed

    Toussaint, Fanny; Charbel, Chimène; Allen, Bruce G; Ledoux, Jonathan

    2016-09-01

    First characterized in neuronal tissues, the multifunctional calcium/calmodulin-dependent protein kinase II (CaMKII) is a key signaling component in several mammalian biological systems. Its unique capacity to integrate various Ca(2+) signals into different specific outcomes is a precious asset to excitable and nonexcitable cells. Numerous studies have reported roles and mechanisms involving CaMKII in brain and heart tissues. However, corresponding functions in vascular cell types (endothelium and vascular smooth muscle cells) remained largely unexplored until recently. Investigation of the intracellular Ca(2+) dynamics, their impact on vascular cell function, the regulatory processes involved and more recently the spatially restricted oscillatory Ca(2+) signals and microdomains triggered significant interest towards proteins like CaMKII. Heteromultimerization of CaMKII isoforms (four isoforms and several splice variants) expands this kinase's peculiar capacity to decipher Ca(2+) signals and initiate specific signaling processes, and thus controlling cellular functions. The physiological functions that rely on CaMKII are unsurprisingly diverse, ranging from regulating contractile state and cellular proliferation to Ca(2+) homeostasis and cellular permeability. This review will focus on emerging evidence of CaMKII as an essential component of the vascular system, with a focus on the kinase isoform/splice variants and cellular system studied. PMID:27306369

  18. Optogenetic control of endogenous Ca(2+) channels in vivo.

    PubMed

    Kyung, Taeyoon; Lee, Sangkyu; Kim, Jung Eun; Cho, Taesup; Park, Hyerim; Jeong, Yun-Mi; Kim, Dongkyu; Shin, Anna; Kim, Sungsoo; Baek, Jinhee; Kim, Jihoon; Kim, Na Yeon; Woo, Doyeon; Chae, Sujin; Kim, Cheol-Hee; Shin, Hee-Sup; Han, Yong-Mahn; Kim, Daesoo; Heo, Won Do

    2015-10-01

    Calcium (Ca(2+)) signals that are precisely modulated in space and time mediate a myriad of cellular processes, including contraction, excitation, growth, differentiation and apoptosis. However, study of Ca(2+) responses has been hampered by technological limitations of existing Ca(2+)-modulating tools. Here we present OptoSTIM1, an optogenetic tool for manipulating intracellular Ca(2+) levels through activation of Ca(2+)-selective endogenous Ca(2+) release-activated Ca(2+) (CRAC) channels. Using OptoSTIM1, which combines a plant photoreceptor and the CRAC channel regulator STIM1 (ref. 4), we quantitatively and qualitatively controlled intracellular Ca(2+) levels in various biological systems, including zebrafish embryos and human embryonic stem cells. We demonstrate that activating OptoSTIM1 in the CA1 hippocampal region of mice selectively reinforced contextual memory formation. The broad utility of OptoSTIM1 will expand our mechanistic understanding of numerous Ca(2+)-associated processes and facilitate screening for drug candidates that antagonize Ca(2+) signals.

  19. An integrated mechanism of cardiomyocyte nuclear Ca(2+) signaling.

    PubMed

    Ibarra, Cristián; Vicencio, Jose Miguel; Varas-Godoy, Manuel; Jaimovich, Enrique; Rothermel, Beverly A; Uhlén, Per; Hill, Joseph A; Lavandero, Sergio

    2014-10-01

    In cardiomyocytes, Ca(2+) plays a central role in governing both contraction and signaling events that regulate gene expression. Current evidence indicates that discrimination between these two critical functions is achieved by segregating Ca(2+) within subcellular microdomains: transcription is regulated by Ca(2+) release within nuclear microdomains, and excitation-contraction coupling is regulated by cytosolic Ca(2+). Accordingly, a variety of agonists that control cardiomyocyte gene expression, such as endothelin-1, angiotensin-II or insulin-like growth factor-1, share the feature of triggering nuclear Ca(2+) signals. However, signaling pathways coupling surface receptor activation to nuclear Ca(2+) release, and the phenotypic responses to such signals, differ between agonists. According to earlier hypotheses, the selective control of nuclear Ca(2+) signals by activation of plasma membrane receptors relies on the strategic localization of inositol trisphosphate receptors at the nuclear envelope. There, they mediate Ca(2+) release from perinuclear Ca(2+) stores upon binding of inositol trisphosphate generated in the cytosol, which diffuses into the nucleus. More recently, identification of such receptors at nuclear membranes or perinuclear sarcolemmal invaginations has uncovered novel mechanisms whereby agonists control nuclear Ca(2+) release. In this review, we discuss mechanisms for the selective control of nuclear Ca(2+) signals with special focus on emerging models of agonist receptor activation. PMID:24997440

  20. ATP hydrolysis is critically required for function of CaV1.3 channels in cochlear inner hair cells via fueling Ca2+ clearance.

    PubMed

    Weiler, Simon; Krinner, Stefanie; Wong, Aaron B; Moser, Tobias; Pangršič, Tina

    2014-05-14

    Sound encoding is mediated by Ca(2+) influx-evoked release of glutamate at the ribbon synapse of inner hair cells. Here we studied the role of ATP in this process focusing on Ca(2+) current through CaV1.3 channels and Ca(2+) homeostasis in mouse inner hair cells. Patch-clamp recordings and Ca(2+) imaging demonstrate that hydrolyzable ATP is essential to maintain synaptic Ca(2+) influx in inner hair cells via fueling Ca(2+)-ATPases to avoid an increase in cytosolic [Ca(2+)] and subsequent Ca(2+)/calmodulin-dependent inactivation of CaV1.3 channels.

  1. Structure and function of the Ca antigen.

    PubMed Central

    Bramwell, M. E.; Bhavanandan, V. P.; Wiseman, G.; Harris, H.

    1983-01-01

    The Ca antigen, which can be detected in a wide range of malignant human tumours by means of the Cal antibody, is a glycoprotein of the mucin type. At least 95% of the carbohydrate is 0-glycosidically linked to the polypeptide which contains high proportions of glycine, serine and glutamic acid. The carbohydrate has a very simple structure: it is composed almost entirely of tetra- tri- and disaccharides having the general formula (NeuNac)n leads to [Gal leads to GalNac] alpha leads to, where n = 0, 1 or 2. In many malignant cell lines, the antigen is produced constitutively in vitro; but in one that has been examined, its synthesis can be induced by high concentrations of lactate. Evidence is presented for the view that a primary function of this glycoprotein is to shield the cells that produce it from hydrogen ion concentrations outside of the physiological range. The presence of the Ca antigen in malignant tumours may thus be a reflection of metabolic conditions that are known to be characteristics of such tumours. Images Figure 1 Figure 2 PMID:6349673

  2. Intracellular Ca(2+) dynamics and the stability of ventricular tachycardia.

    PubMed Central

    Chudin, E; Goldhaber, J; Garfinkel, A; Weiss, J; Kogan, B

    1999-01-01

    Ventricular fibrillation (VF), the major cause of sudden cardiac death, is typically preceded by ventricular tachycardia (VT), but the mechanisms underlying the transition from VT to VF are poorly understood. Intracellular Ca(2+) overload occurs during rapid heart rates typical of VT and is also known to promote arrhythmias. We therefore studied the role of intracellular Ca(2+) dynamics in the transition from VT to VF, using a combined experimental and mathematical modeling approach. Our results show that 1) rapid pacing of rabbit ventricular myocytes at 35 degrees C led to increased intracellular Ca(2+) levels and complex patterns of action potential (AP) configuration and the intracellular Ca(2+) transients; 2) the complex patterns of the Ca(2+) transient arose directly from the dynamics of intracellular Ca(2+) cycling, and were not merely passive responses to beat-to-beat alterations in AP; 3) the complex Ca(2+) dynamics were simulated in a modified version of the Luo-Rudy (LR) ventricular action potential with improved intracellular Ca(2+) dynamics, and showed good agreement with the experimental findings in isolated myocytes; and 4) when incorporated into simulated two-dimensional cardiac tissue, this action potential model produced a form of spiral wave breakup from VT to a VF-like state in which intracellular Ca(2+) dynamics played a key role through its influence on Ca(2+)-sensitive membrane currents such as I(Ca), I(NaCa), and I(ns(Ca)). To the extent that spiral wave breakup is useful as a model for the transition from VT to VF, these findings suggest that intracellular Ca(2+) dynamics may play an important role in the destabilization of VT and its degeneration into VF. PMID:10585917

  3. Interpreting the Ca isotope record of marine biogenic carbonates

    NASA Astrophysics Data System (ADS)

    Sime, Neil G.; De La Rocha, Christina L.; Tipper, Edward T.; Tripati, Aradhna; Galy, Albert; Bickle, Michael J.

    2007-08-01

    An 18 million year record of the Ca isotopic composition (δ 44/42Ca) of planktonic foraminiferans from ODP site 925, in the Atlantic, on the Ceara Rise, provides the opportunity for critical analysis of Ca isotope-based reconstructions of the Ca cycle. δ 44/42Ca in this record averages +0.37 ± 0.05 (1 σ SD) and ranges from +0.21‰ to +0.52‰. The record is a good match to previously published Neogene Ca isotope records based on foraminiferans, but is not similar to the record based on bulk carbonates, which has values that are as much as 0.25‰ lower. Bulk carbonate and planktonic foraminiferans from core tops differ slightly in their δ 44/42Ca (i.e., by 0.06 ± 0.06‰ ( n = 5)), while the difference between bulk carbonate and foraminiferan values further back in time is markedly larger, leaving open the question of the cause of the difference. Modeling the global Ca cycle from downcore variations in δ 44/42Ca by assuming fixed values for the isotopic composition of weathering inputs (δ 44/42Ca w) and for isotope fractionation associated with the production of carbonate sediments (Δ sed) results in unrealistically large variations in the total mass of Ca 2+ in the oceans over the Neogene. Alternatively, variations of ±0.05‰ in the Ca isotope composition of weathering inputs or in the extent of fractionation of Ca isotopes during calcareous sediment formation could entirely account for variations in the Ca isotopic composition of marine carbonates. Ca isotope fractionation during continental weathering, such as has been recently observed, could easily result in variations in δ 44/42Ca w of a few tenths of permil. Likewise a difference in the fractionation factors associated with aragonite versus calcite formation could drive shifts in Δ sed of tenths of permil with shifts in the relative output of calcite and aragonite from the ocean. Until better constraints on variations in δ 44/42Ca w and Δ sed have been established, modeling the Ca 2+ content

  4. The influence of the 2-neutron elastic transfer on the fusion of 42Ca + 40Ca

    NASA Astrophysics Data System (ADS)

    Stefanini, A. M.; Montagnoli, G.; Corradi, L.; Fioretto, E.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Strano, E.

    2016-05-01

    Strong coupling to a single channel with zero Q-value is predicted to produce a characteristic fusion barrier distribution with two peaks, one on each side of the original uncoupled Coulomb barrier. In practical cases, only coupling to an elastic transfer channel may produce such a distribution which, however, has never been observed sofar, probably because low-lying surface vibrations usually have a dominant role, and this may obscure the two-peak structure. The case of the two-neutron (2n) elastic transfer in 42Ca + 40Ca is particularly attractive, because of the relatively rigid nature of the two nuclei. We have measured the fusion excitation function of this system using the 42Ca beam of the XTU Tandem of LNL on a thin 40Ca target enriched to 99.96% in mass 40. Cross sections have been measured down to ≤1 mb. The extracted barrier distribution shows clearly two main peaks. We have performed preliminary CC calculations where the 2+ coupling strengths have been taken from the literature and the schematic 2n pair transfer form factor has been used, with a deformation length σt= 0.39 fm. The excitation function is well reproduced by the calculation including the 2n transfer channel. However, including the octupole excitations destroys the agreement.

  5. Pycnogenol protects CA3-CA1 synaptic function in a rat model of traumatic brain injury.

    PubMed

    Norris, Christopher M; Sompol, Pradoldej; Roberts, Kelly N; Ansari, Mubeen; Scheff, Stephen W

    2016-02-01

    Pycnogenol (PYC) is a patented mix of bioflavonoids with potent anti-oxidant and anti-inflammatory properties. Previously, we showed that PYC administration to rats within hours after a controlled cortical impact (CCI) injury significantly protects against the loss of several synaptic proteins in the hippocampus. Here, we investigated the effects of PYC on CA3-CA1 synaptic function following CCI. Adult Sprague-Dawley rats received an ipsilateral CCI injury followed 15 min later by intravenous injection of saline vehicle or PYC (10 mg/kg). Hippocampal slices from the injured (ipsilateral) and uninjured (contralateral) hemispheres were prepared at seven and fourteen days post-CCI for electrophysiological analyses of CA3-CA1 synaptic function and induction of long-term depression (LTD). Basal synaptic strength was impaired in slices from the ipsilateral, relative to the contralateral, hemisphere at seven days post-CCI and susceptibility to LTD was enhanced in the ipsilateral hemisphere at both post-injury timepoints. No interhemispheric differences in basal synaptic strength or LTD induction were observed in rats treated with PYC. The results show that PYC preserves synaptic function after CCI and provides further rationale for investigating the use of PYC as a therapeutic in humans suffering from neurotrauma. PMID:26607913

  6. CA 72-4 compared with CEA and CA 19-9 as a marker of some gastrointestinal malignancies.

    PubMed

    Lopez, J B; Royan, G P; Lakhwani, M N; Mahadaven, M; Timor, J

    1999-01-01

    The objective of this study was to compare CA 72-4 with CEA and CA 19-9 in gastrointestinal malignancies. CA 72-4 was assayed by radioimmunoassay and CEA and CA 19-9 with the Abbott IMx analyser. The study included 52 patients with gastrointestinal cancer and 20 controls with benign gastrointestinal diseases. The 52 cases showed marker sensitivities of 39%, 49% and 35% for CA 72-4, CEA and CA 19-9, respectively, and 64% when the markers were combined. Marker expression in serum was highest in colorectal carcinoma followed by gastric and esophageal carcinoma. The sensitivities of the individual markers in colorectal, gastric and esophageal carcinomas, respectively, were: CA 72-4, 56%, 32% and 18%; CEA, 83%, 33% and 18%; CA 19-9, 53%, 25% and 18%. The sensitivity of the three markers in combination was 89%, 50% and 46% in colorectal, gastric and esophageal cancer, respectively. The specificity of CA 72-4, CEA and CA 19-9 was 100%, 72% and 86%, respectively. However, CA 72-4 is not a useful a marker for gastrointestinal cancers because of its poor sensitivity. CEA, which had the best overall sensitivity and a reasonable specificity, was the most useful single marker, especially for colorectal cancer. Whereas the single markers were not useful in gastric and esophageal cancer, the combination of the three may be.

  7. Distinct Ca2+ sources in dendritic spines of hippocampal CA1 neurons couple to SK and Kv4 channels

    PubMed Central

    Wang, Kang; Lin, Mike T.; Adelman, John P.; Maylie, James

    2013-01-01

    SUMMARY Ca2+-activated SK channels and voltage-gated A-type Kv4 channels shape dendritic excitatory postsynaptic potentials (EPSPs) in hippocampal CA1 pyramidal neurons. Synaptically evoked Ca2+ influx through N-methyl-D-aspartate receptors (NMDARs) activates spine SK channels, reducing EPSPs and the associated spine head Ca2+ transient. However, results using glutamate uncaging implicated Ca2+ influx through SNX-482 (SNX) sensitive Cav2.3 (R-type) Ca2+ channels as the Ca2+ source for SK channel activation. The present findings show that using Schaffer collateral stimulation the effects of SNX and apamin are not mutually exclusive and SNX increases EPSPs independent of SK channel activity. Dialysis with 1,2-bis(o-aminophenoxy)ethane-N’N’N’-tetraacetic acid (BAPTA), application of 4-Aminopyridine (4-AP), expression of a Kv4.2 dominant negative subunit, and dialysis with a KChIPs antibody occluded the SNX-induced increase of EPSPs. The results suggest two distinct Ca2+ signaling pathways within dendritic spines, that links Ca2+ influx through NMDARs to SK channels and Ca2+ influx through R-type Ca2+ channels to Kv4.2-containing channels. PMID:24462100

  8. The mitochondrial Na+/Ca2+ exchanger upregulates glucose dependent Ca2+ signalling linked to insulin secretion.

    PubMed

    Nita, Iulia I; Hershfinkel, Michal; Fishman, Daniel; Ozeri, Eyal; Rutter, Guy A; Sensi, Stefano L; Khananshvili, Daniel; Lewis, Eli C; Sekler, Israel

    2012-01-01

    Mitochondria mediate dual metabolic and Ca(2+) shuttling activities. While the former is required for Ca(2+) signalling linked to insulin secretion, the role of the latter in β cell function has not been well understood, primarily because the molecular identity of the mitochondrial Ca(2+) transporters were elusive and the selectivity of their inhibitors was questionable. This study focuses on NCLX, the recently discovered mitochondrial Na(+)/Ca(2+) exchanger that is linked to Ca(2+) signalling in MIN6 and primary β cells. Suppression either of NCLX expression, using a siRNA construct (siNCLX) or of its activity, by a dominant negative construct (dnNCLX), enhanced mitochondrial Ca(2+) influx and blocked efflux induced by glucose or by cell depolarization. In addition, NCLX regulated basal, but not glucose-dependent changes, in metabolic rate, mitochondrial membrane potential and mitochondrial resting Ca(2+). Importantly, NCLX controlled the rate and amplitude of cytosolic Ca(2+) changes induced by depolarization or high glucose, indicating that NCLX is a critical and rate limiting component in the cross talk between mitochondrial and plasma membrane Ca(2+) signalling. Finally, knockdown of NCLX expression was followed by a delay in glucose-dependent insulin secretion. These findings suggest that the mitochondrial Na(+)/Ca(2+) exchanger, NCLX, shapes glucose-dependent mitochondrial and cytosolic Ca(2+) signals thereby regulating the temporal pattern of insulin secretion in β cells.

  9. Intracellular Ca(2+) signaling and Ca(2+) microdomains in the control of cell survival, apoptosis and autophagy.

    PubMed

    La Rovere, Rita M L; Roest, Gemma; Bultynck, Geert; Parys, Jan B

    2016-08-01

    The endoplasmic reticulum (ER), mitochondria and lysosomes are physically and/or functionally linked, establishing close contact sites between these organelles. As a consequence, Ca(2+) release events from the ER, the major intracellular Ca(2+)-storage organelle, have an immediate effect on the physiological function of mitochondria and lysosomes. Also, the lysosomes can act as a Ca(2+) source for Ca(2+) release into the cytosol, thereby influencing ER-based Ca(2+) signaling. Given the important role for mitochondria and lysosomes in cell survival, cell death and cell adaptation processes, it has become increasingly clear that Ca(2+) signals from or towards these organelles impact these processes. In this review, we discuss the most recent insights in the emerging role of Ca(2+) signaling in cellular survival by controlling basal mitochondrial bioenergetics and by regulating apoptosis, a mitochondrial process, and autophagy, a lysosomal process, in response to cell damage and cell stress.

  10. Differences and correlation of serum CEA, CA19-9 and CA72-4 in gastric cancer

    PubMed Central

    YU, JUNXIU; ZHANG, SHUGUANG; ZHAO, BINGBO

    2016-01-01

    The sensitivity of three biomarkers, carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9 and CA72-4, in combination has been identified to be greater than that of any of the biomarkers considered in isolation in cases of gastric cancer (GC). However, the fundamental cause underlying this phenomenon remains to be fully elucidated. In the present study, the differences and correlation of these three biomarkers were investigated in patients with GC in order to determine how the three biomarkers in combination work more effectively compared with any of the biomarkers considered alone. The serum levels of CEA, CA19-9 and CA72-4 of 216 patients with gastric adenocarcinoma were analyzed on admission to hospital. The differences in positive rates and the serum levels of CEA, CA19-9 and CA72-4 were analyzed using the χ2 test and the non-parametric Wilcoxon two-sample test. Phi (f) correlation analysis was used to study the correlation among the expression (positive or not) levels of CEA, CA19-9 and CA72-4. The correlation among the serum levels of biomarkers was analyzed using Spearman's test. The results demonstrated that the combined positive rate of CEA, CA19-9 and CA72-4 was significantly higher compared with the individual CEA, CA19-9 and CA72-4 positive rates (44.91% vs. 22.69, 18.98 and 22.69%, respectively; all P<0.05). The positive rate of CA19-9 and CA72-4 in the extent of the primary tumor/involvement of regional lymph node/distant metastases (TNM)-III/IV stage subgroup was higher compared with that in the TNM-I/II subgroup (χ2=5.902, P=0.015; χ2=8.009, P=0.005), although not the positive rate of CEA (χ2=0.302, P=0.583). A significant correlation was identified between the expression level of CEA and CA72-4 (f correlation coefficient=0.182; P=0.008) and between that of CA19-9 and CA72-4 (f correlation coefficient=0.189; P=0.006), although not between that of CEA and CA19-9 (f correlation coefficient=0.048; P=0.482) in the total number of patients

  11. Thermodynamics of Reducing Refining of Phosphorus from Si-Mn Alloy Using CaO-CaF2 Slag

    NASA Astrophysics Data System (ADS)

    Shin, Jae Hong; Park, Joo Hyun

    2012-12-01

    The thermodynamic behavior of phosphide ions in the CaO-CaF2 flux in equilibrium with a SiMn(-Fe) alloy melt was investigated under a strongly reducing atmosphere at 1823 K (1550 °C). The phosphide capacity increased with increasing CaO concentration in the flux before reaching a constant value. The composition for the saturating capacity is in good agreement with the saturation content of CaO in the CaO-CaF2 flux at 1823 K (1550 °C). The relationship between the phosphide capacity and the activity of CaO in the flux exhibited a linear relationship on the logarithmic scale, indicating that phosphorus was removed from the SiMn(-Fe) melt by the reducing refining mechanism.

  12. Intracellular Ca(2+) signaling and Ca(2+) microdomains in the control of cell survival, apoptosis and autophagy.

    PubMed

    La Rovere, Rita M L; Roest, Gemma; Bultynck, Geert; Parys, Jan B

    2016-08-01

    The endoplasmic reticulum (ER), mitochondria and lysosomes are physically and/or functionally linked, establishing close contact sites between these organelles. As a consequence, Ca(2+) release events from the ER, the major intracellular Ca(2+)-storage organelle, have an immediate effect on the physiological function of mitochondria and lysosomes. Also, the lysosomes can act as a Ca(2+) source for Ca(2+) release into the cytosol, thereby influencing ER-based Ca(2+) signaling. Given the important role for mitochondria and lysosomes in cell survival, cell death and cell adaptation processes, it has become increasingly clear that Ca(2+) signals from or towards these organelles impact these processes. In this review, we discuss the most recent insights in the emerging role of Ca(2+) signaling in cellular survival by controlling basal mitochondrial bioenergetics and by regulating apoptosis, a mitochondrial process, and autophagy, a lysosomal process, in response to cell damage and cell stress. PMID:27157108

  13. PGC-1{alpha} accelerates cytosolic Ca{sup 2+} clearance without disturbing Ca{sup 2+} homeostasis in cardiac myocytes

    SciTech Connect

    Chen, Min; Wang, Yanru; Qu, Aijuan

    2010-06-11

    Energy metabolism and Ca{sup 2+} handling serve critical roles in cardiac physiology and pathophysiology. Peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1{alpha}) is a multi-functional coactivator that is involved in the regulation of cardiac mitochondrial functional capacity and cellular energy metabolism. However, the regulation of PGC-1{alpha} in cardiac Ca{sup 2+} signaling has not been fully elucidated. To address this issue, we combined confocal line-scan imaging with off-line imaging processing to characterize calcium signaling in cultured adult rat ventricular myocytes expressing PGC-1{alpha} via adenoviral transduction. Our data shows that overexpressing PGC-1{alpha} improved myocyte contractility without increasing the amplitude of Ca{sup 2+} transients, suggesting that myofilament sensitivity to Ca{sup 2+} increased. Interestingly, the decay kinetics of global Ca{sup 2+} transients and Ca{sup 2+} waves accelerated in PGC-1{alpha}-expressing cells, but the decay rate of caffeine-elicited Ca{sup 2+} transients showed no significant change. This suggests that sarcoplasmic reticulum (SR) Ca{sup 2+}-ATPase (SERCA2a), but not Na{sup +}/Ca{sup 2+} exchange (NCX) contribute to PGC-1{alpha}-induced cytosolic Ca{sup 2+} clearance. Furthermore, PGC-1{alpha} induced the expression of SERCA2a in cultured cardiac myocytes. Importantly, overexpressing PGC-1{alpha} did not disturb cardiac Ca{sup 2+} homeostasis, because SR Ca{sup 2+} load and the propensity for Ca{sup 2+} waves remained unchanged. These data suggest that PGC-1{alpha} can ameliorate cardiac Ca{sup 2+} cycling and improve cardiac work output in response to physiological stress. Unraveling the PGC-1{alpha}-calcium handing pathway sheds new light on the role of PGC-1{alpha} in the therapy of cardiac diseases.

  14. Ca2+ influx via the Na+/Ca2+ exchanger is enhanced in malignant hyperthermia skeletal muscle.

    PubMed

    Altamirano, Francisco; Eltit, José M; Robin, Gaëlle; Linares, Nancy; Ding, Xudong; Pessah, Isaac N; Allen, Paul D; López, José R

    2014-07-01

    Malignant hyperthermia (MH) is potentially fatal pharmacogenetic disorder of skeletal muscle caused by intracellular Ca(2+) dysregulation. NCX is a bidirectional transporter that effluxes (forward mode) or influxes (reverse mode) Ca(2+) depending on cellular activity. Resting intracellular calcium ([Ca(2+)]r) and sodium ([Na(+)]r) concentrations are elevated in MH susceptible (MHS) swine and murine muscles compared with their normal (MHN) counterparts, although the contribution of NCX is unclear. Lowering [Na(+)]e elevates [Ca(2+)]r in both MHN and MHS swine muscle fibers and it is prevented by removal of extracellular Ca(2+) or reduced by t-tubule disruption, in both genotypes. KB-R7943, a nonselective NCX3 blocker, reduced [Ca(2+)]r in both swine and murine MHN and MHS muscle fibers at rest and decreased the magnitude of the elevation of [Ca(2+)]r observed in MHS fibers after exposure to halothane. YM-244769, a high affinity reverse mode NCX3 blocker, reduces [Ca(2+)]r in MHS muscle fibers and decreases the amplitude of [Ca(2+)]r rise triggered by halothane, but had no effect on [Ca(2+)]r in MHN muscle. In addition, YM-244769 reduced the peak and area under the curve of the Ca(2+) transient elicited by high [K(+)]e and increased its rate of decay in MHS muscle fibers. siRNA knockdown of NCX3 in MHS myotubes reduced [Ca(2+)]r and the Ca(2+) transient area induced by high [K(+)]e. These results demonstrate a functional NCX3 in skeletal muscle whose activity is enhanced in MHS. Moreover reverse mode NCX3 contributes to the Ca(2+) transients associated with K(+)-induced depolarization and the halothane-triggered MH episode in MHS muscle fibers. PMID:24847052

  15. Ca2+ Influx via the Na+/Ca2+ Exchanger Is Enhanced in Malignant Hyperthermia Skeletal Muscle*

    PubMed Central

    Altamirano, Francisco; Eltit, José M.; Robin, Gaëlle; Linares, Nancy; Ding, Xudong; Pessah, Isaac N.; Allen, Paul D.; López, José R.

    2014-01-01

    Malignant hyperthermia (MH) is potentially fatal pharmacogenetic disorder of skeletal muscle caused by intracellular Ca2+ dysregulation. NCX is a bidirectional transporter that effluxes (forward mode) or influxes (reverse mode) Ca2+ depending on cellular activity. Resting intracellular calcium ([Ca2+]r) and sodium ([Na+]r) concentrations are elevated in MH susceptible (MHS) swine and murine muscles compared with their normal (MHN) counterparts, although the contribution of NCX is unclear. Lowering [Na+]e elevates [Ca2+]r in both MHN and MHS swine muscle fibers and it is prevented by removal of extracellular Ca2+ or reduced by t-tubule disruption, in both genotypes. KB-R7943, a nonselective NCX3 blocker, reduced [Ca2+]r in both swine and murine MHN and MHS muscle fibers at rest and decreased the magnitude of the elevation of [Ca2+]r observed in MHS fibers after exposure to halothane. YM-244769, a high affinity reverse mode NCX3 blocker, reduces [Ca2+]r in MHS muscle fibers and decreases the amplitude of [Ca2+]r rise triggered by halothane, but had no effect on [Ca2+]r in MHN muscle. In addition, YM-244769 reduced the peak and area under the curve of the Ca2+ transient elicited by high [K+]e and increased its rate of decay in MHS muscle fibers. siRNA knockdown of NCX3 in MHS myotubes reduced [Ca2+]r and the Ca2+ transient area induced by high [K+]e. These results demonstrate a functional NCX3 in skeletal muscle whose activity is enhanced in MHS. Moreover reverse mode NCX3 contributes to the Ca2+ transients associated with K+-induced depolarization and the halothane-triggered MH episode in MHS muscle fibers. PMID:24847052

  16. Induction of CaSR expression circumvents the molecular features of malignant CaSR null colon cancer cells.

    PubMed

    Singh, Navneet; Chakrabarty, Subhas

    2013-11-15

    We recently reported on the isolation and characterization of calcium sensing receptor (CaSR) null human colon cancer cells (Singh et al., Int J Cancer 2013; 132: 1996-2005). CaSR null cells possess a myriad of molecular features that are linked to a highly malignant and drug resistant phenotype of colon cancer. The CaSR null phenotype can be maintained in defined human embryonic stem cell culture medium. We now show that the CaSR null cells can be induced to differentiate in conventional culture medium, regained the expression of CaSR with a concurrent reversal of the cellular and molecular features associated with the null phenotype. These features include cellular morphology, expression of colon cancer stem cell markers, expression of survivin and thymidylate synthase and sensitivity to fluorouracil. Other features include the expression of epithelial mesenchymal transition linked molecules and transcription factors, oncogenic miRNAs and tumor suppressive molecule and miRNA. With the exception of cancer stem cell markers, the reversal of molecular features, upon the induction of CaSR expression, is directly linked to the expression and function of CaSR because blocking CaSR induction by shRNA circumvented such reversal. We further report that methylation and demethylation of the CaSR gene promoter underlie CaSR expression. Due to the malignant nature of the CaSR null cells, inclusion of the CaSR null phenotype in disease management may improve on the mortality of this disease. Because CaSR is a robust promoter of differentiation and mediates its action through diverse mechanisms and pathways, inactivation of CaSR may serve as a new paradigm in colon carcinogenesis.

  17. Ca2+ accumulation into acidic organelles mediated by Ca2+- and vacuolar H+-ATPases in human platelets

    PubMed Central

    2005-01-01

    Most physiological agonists increase cytosolic free [Ca2+]c (cytosolic free Ca2+ concentration) to regulate a variety of cellular processes. How different stimuli evoke distinct spatiotemporal Ca2+ responses remains unclear, and the presence of separate intracellular Ca2+ stores might be of great functional relevance. Ca2+ accumulation into intracellular compartments mainly depends on the activity of Ca2+- and H+-ATPases. Platelets present two separate Ca2+ stores differentiated by the distinct sensitivity to thapsigargin and TBHQ [2,5-di-(t-butyl)-1,4-hydroquinone]. Although one store has long been identified as the dense tubular system, the nature of the TBHQ-sensitive store remains uncertain. Treatment of platelets with GPN (glycylphenylalanine-2-naphthylamide) impaired Ca2+ release by TBHQ and reduced that evoked by thrombin. In contrast, GPN did not modify Ca2+ mobilization stimulated by ADP or AVP ([arginine]vasopressin). Treatment with nigericin, a proton carrier, and bafilomycin A1, an inhibitor of the vacuolar H+-ATPase, to dissipate the proton gradient into acidic organelles induces a transient increase in [Ca2+]c that was abolished by previous treatment with the SERCA (sarcoplasmic/endoplasmic-reticulum Ca2+-ATPase) 3 inhibitor TBHQ. Depleted acidic stores after nigericin or bafilomycin A1 were refilled by SERCA 3. Thrombin, but not ADP or AVP, reduces the rise in [Ca2+]c evoked by nigericin and bafilomycin A1. Our results indicate that the TBHQ-sensitive store in human platelets is an acidic organelle whose Ca2+ accumulation is regulated by both Ca2+- and vacuolar H+-ATPases. PMID:15847604

  18. The interplay between plasma membrane and endoplasmic reticulum Ca(2+)ATPases in agonist-induced temporal Ca(2+) dynamics.

    PubMed

    Cicek, Figen Amber; Ozgur, Ekin Ozge; Ozgur, Erol; Ugur, Mehmet

    2014-12-01

    A change in the intracellular free Ca(2+) concentration ([Ca(2+)]i) functions as a transmitter for signal transduction and shows a broad temporal pattern. Even genetically homogeneous cell types show different Ca(2+) response patterns under permanent agonist stimulation. In Ca(2+) signaling, the dynamics of the Ca(2+) release from the Ca(2+) channels during continuous agonist stimulation and the simultaneous effect of the pumps are unclear. In this study, the dynamic interaction of the Ca(2+) ATPases in the plasma membrane (PMCA) and the endoplasmic reticulum membrane (SERCA) during continuous ACh stimulation is monitored using Fluo-3 and Fura-2 loaded HEK 293 cells. We characterize Ca(2+) release patterns at the sub-maximal and maximal stimulation doses in the absence of extracellular Ca(2+). We analyze the responses regarding their types, oscillation frequency and response times. La(3+) (PMCA blocker) do not change the frequency and time courses in sub-maximal ACh treatment, while with the maximal stimulation oscillation frequency increase as oscillations superimpose on robust release, and response time of [Ca(2+)]i is elongated. A similar effect of La(3+) is observed in quantal Ca(2+) release phenomenon. In the presence of CPA, a SERCA blocker, oscillations are completely abolished, but response time does not change. We also observe that during continuous receptor stimulation, Ca(2+) release do not cease. These data may suggest that Ca(2+) release continues during agonist stimulation, but SERCA and PMCA form a new steady state and return [Ca(2+)]i to its physiological concentration. PMID:25331516

  19. U-Pb Dating of CA/non-CA Treated Zircons Obtained by LA-ICP-MS and CA-TIMS Techniques: Impact for their Geological Interpretation

    NASA Astrophysics Data System (ADS)

    Von Quadt, A.; Gallhofer, D.; Guillong, M.; Peytcheva, I.

    2014-12-01

    Chemical Abrasion Isotope-Dilution Thermal Ionization Mass Spectrometry (CA-ID-TIMS) is known as a high precision technique for resolving lead loss and improving the interpretation of U-Pb zircon age data. We argue that combining CA with the widely applied Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) improves the precision and accuracy of zircon dates, while removing the substantial parts with lead loss, reducing data scatter, and providing meaningful geological interpretations. The samples are magmatic rocks chosen from different geological time periods (Paleozoic, Mesozoic and Cenozoic time). All zircon separates are analysed by LA-ICP-MS before and after CA, and all age data are compared with CA-ID-TIMS 206Pb/238U dates that are considered as the most accurately age. All CA-treated zircon crystals show up to 50% less data scatter compared to the non-CA treated zircon grains and thus a reduction of the calculated uncertainties is apparent. The obtained wt average LA-ICP-MS 206Pb/238U ages of the CA-treated zircon grains are up to 4-6% higher than those of the non-CA treated crystals, exceeding the analytical uncertainties of the LA-ICP-MS dating technique of 1-2%. The damaged crystal parts, caused by U-decay, with lead loss are removed, so that we can exclude younging from the possible geological scenarios. CA-LA-ICP-MS age data are in good agreement with the CA-ID-TIMS dates and suggest advantages of using CA-LA-ICP-MS in order to define accurate ages. The use of the CA technique for very young zircons (~0.2 Ma, Kos rhyolitic tuff, Greece) seems optional; as the obtained mean 206Pb/238U ages of non-CA and CA treated zircons coincide within the uncertainty. The negligible time to produce the lattice damage (based on alpha decay or spontaneous fission) makes lead loss less important for age dating and data interpretation of very young zircons (<1 Ma). Von Quadt, A. et al., 2014, JAAS, doi: 10.1039/c4ja00102h.

  20. Clinical value of CYFRA21-1, NSE, CA15-3, CA19-9 and CA125 assay in the elderly patients with pleural effusions.

    PubMed

    Li, C-S; Cheng, B-C; Ge, W; Gao, J-F

    2007-03-01

    The aim of this study was to evaluate the individual and combined diagnostic value of five tumour markers in the elderly patients with pleural effusions. Serum and pleural fluid levels of cytokeratin fragment 19 (CYFRA21-1), neuron-specific enolase (NSE), carbohydrate antigen 15-3 (CA15-3), carbohydrate antigen 19-9 (CA19-9) and carbohydrate antigen 125 (CA125) were assayed in 32 elderly patients with malignant pleural effusions resulting from advanced lung cancer and in 30 elderly patients with benign pleural effusions by ELISA. Serum levels of CYFRA21-1, NSE, CA15-3, CA19-9 and CA125 in patients with malignant pleural effusions were 12.84 +/- 6.48 microg/l, 22.07 +/- 11.25 microg/l, 65.74 +/- 30.26 kU/l, 56.32 +/- 25.6 kU/l and 71.86 +/- 31.45 kU/l, respectively, and were significantly higher than those in patients with benign pleural effusions (p < 0.01). Pleural fluid levels of CYFRA21-1, CA15-3, CA19-9 and CA125 except NSE in patients with malignant pleural effusions were 18.64 +/- 8.15 microg/l, 59.31 +/- 27.35 kU/l, 48.24 +/- 21.56 kU/l and 62.16 +/- 27.79 kU/l, respectively, and were significantly higher than those in patients with benign pleural effusions (p < 0.01). The parallel combined testing of five tumour markers in serum increased the diagnostic sensitivity to 90.6%, and serial combined testing increased the diagnostic specificity to 93.3%. The sensitivity (%) and specificity (%) of these tumour markers in pleural fluid were as follows: CYFRA21-1, 84.4/90; CA15-3, 62.5/73.3; CA19-9, 37.5/66.7; CA125, 56.3/70; for differentiating malignant effusions from benign effusions. When CYFRA21-1 and CA15-3 combined, the sensitivity and specificity were increased (100% and 90% respectively). Serum and pleural fluid levels of the five tumour markers shows certain values in the diagnosis and differentiate diagnosis for malignant pleural effusions in the elderly patients from benign. The combined assay of five tumour markers in serum and the CYFRA21-1 combined

  1. Modeling Ca2+-Bound Troponin in Excitation Contraction Coupling

    PubMed Central

    Zot, Henry G.; Hasbun, Javier E.

    2016-01-01

    To explain disparate decay rates of cytosolic Ca2+ and structural changes in the thin filaments during a twitch, we model the time course of Ca2+-bound troponin (Tn) resulting from the free Ca2+ transient of fast skeletal muscle. In fibers stretched beyond overlap, the decay of Ca2+ as measured by a change in fluo-3 fluorescence is significantly slower than the intensity decay of the meridional 1/38.5 nm−1 reflection of Tn; this is not simply explained by considering only the Ca2+ binding properties of Tn alone (Matsuo et al., 2010). We apply a comprehensive model that includes the known Ca2+ binding properties of Tn in the context of the thin filament with and without cycling crossbridges. Calculations based on the model predict that the transient of Ca2+-bound Tn correlates with either the fluo-3 time course in muscle with overlapping thin and thick filaments or the intensity of the meridional 1/38.5 nm−1 reflection in overstretched muscle. Hence, cycling crossbridges delay the dissociation of Ca2+ from Tn. Correlation with the fluo-3 fluorescence change is not causal given that the transient of Ca2+-bound Tn depends on sarcomere length, whereas the fluo-3 fluorescence change does not. Transient positions of tropomyosin calculated from the time course of Ca2+-bound Tn are in reasonable agreement with the transient of measured perturbations of the Tn repeat in overlap and non-overlap muscle preparations. PMID:27708586

  2. The Effect of OPA1 on Mitochondrial Ca2+ Signaling

    PubMed Central

    Enyedi, Balázs; Várnai, Péter; Spät, András

    2011-01-01

    The dynamin-related GTPase protein OPA1, localized in the intermembrane space and tethered to the inner membrane of mitochondria, participates in the fusion of these organelles. Its mutation is the most prevalent cause of Autosomal Dominant Optic Atrophy. OPA1 controls the diameter of the junctions between the boundary part of the inner membrane and the membrane of cristae and reduces the diffusibility of cytochrome c through these junctions. We postulated that if significant Ca2+ uptake into the matrix occurs from the lumen of the cristae, reduced expression of OPA1 would increase the access of Ca2+ to the transporters in the crista membrane and thus would enhance Ca2+ uptake. In intact H295R adrenocortical and HeLa cells cytosolic Ca2+ signals evoked with K+ and histamine, respectively, were transferred into the mitochondria. The rate and amplitude of mitochondrial [Ca2+] rise (followed with confocal laser scanning microscopy and FRET measurements with fluorescent wide-field microscopy) were increased after knockdown of OPA1, as compared with cells transfected with control RNA or mitofusin1 siRNA. Ca2+ uptake was enhanced despite reduced mitochondrial membrane potential. In permeabilized cells the rate of Ca2+ uptake by depolarized mitochondria was also increased in OPA1-silenced cells. The participation of Na+/Ca2+ and Ca2+/H+ antiporters in this transport process is indicated by pharmacological data. Altogether, our observations reveal the significance of OPA1 in the control of mitochondrial Ca2+ metabolism. PMID:21980395

  3. Luminal Ca2+ dynamics during IP3R mediated signals

    NASA Astrophysics Data System (ADS)

    Lopez, Lucia F.; Ponce Dawson, Silvina

    2016-06-01

    The role of cytosolic Ca2+ on the kinetics of Inositol 1,4,5-triphosphate receptors (IP3Rs) and on the dynamics of IP3R-mediated Ca2+ signals has been studied at large both experimentally and by modeling. The role of luminal Ca2+ has not been investigated with that much detail although it has been found that it is relevant for signal termination in the case of Ca2+ release through ryanodine receptors. In this work we present the results of observing the dynamics of luminal and cytosolic Ca2+ simultaneously in Xenopus laevis oocytes. Combining observations and modeling we conclude that there is a rapid mechanism that guarantees the availability of free Ca2+ in the lumen even when a relatively large Ca2+ release is evoked. Comparing the dynamics of cytosolic and luminal Ca2+ during a release, we estimate that they are consistent with a 80% of luminal Ca2+ being buffered. The rapid availability of free luminal Ca2+ correlates with the observation that the lumen occupies a considerable volume in several regions across the images.

  4. Characteristics and Possible Functions of Mitochondrial Ca2+ Transport Mechanisms

    PubMed Central

    Gunter, Thomas E.; Sheu, Shey-Shing

    2009-01-01

    Mitochondria produce around 92% of the ATP used in the typical animal cell by oxidative phosphorylation using energy from their electrochemical proton gradient. Intramitochondrial free Ca2+ concentration ([Ca2+]m) has been found to be an important component of control of the rate of this ATP production. In addition, [Ca2+]m also controls the opening of a large pore in the inner mitochondrial membrane, the permeability transition pore (PTP), which plays a role in mitochondrial control of programmed cell death or apoptosis. Therefore, [Ca2+]m can control whether the cell has sufficient ATP to fulfill its functions and survive or is condemned to death. Ca2+ is also one of the most important second messengers within the cytosol, signaling changes in cellular response through Ca2+ pulses or transients. Mitochondria can also sequester Ca2+ from these transients so as to modify the shape of Ca2+ signaling transients or control their location within the cell. All of this is controlled by the action of four or five mitochondrial Ca2+ transport mechanisms and the PTP. The characteristics of these mechanisms of Ca2+ transport and a discussion of how they might function are described in this paper. PMID:19161975

  5. Ca2+ dynamics in oocytes from naturally-aged mice

    PubMed Central

    Haverfield, Jenna; Nakagawa, Shoma; Love, Daniel; Tsichlaki, Elina; Nomikos, Michail; Lai, F. Anthony; Swann, Karl; FitzHarris, Greg

    2016-01-01

    The ability of human metaphase-II arrested eggs to activate following fertilisation declines with advancing maternal age. Egg activation is triggered by repetitive increases in intracellular Ca2+ concentration ([Ca2+]i) in the ooplasm as a result of sperm-egg fusion. We therefore hypothesised that eggs from older females feature a reduced ability to mount appropriate Ca2+ responses at fertilisation. To test this hypothesis we performed the first examination of Ca2+ dynamics in eggs from young and naturally-aged mice. Strikingly, we find that Ca2+ stores and resting [Ca2+]i are unchanged with age. Although eggs from aged mice feature a reduced ability to replenish intracellular Ca2+ stores following depletion, this difference had no effect on the duration, number, or amplitude of Ca2+ oscillations following intracytoplasmic sperm injection or expression of phospholipase C zeta. In contrast, we describe a substantial reduction in the frequency and duration of oscillations in aged eggs upon parthenogenetic activation with SrCl2. We conclude that the ability to mount and respond to an appropriate Ca2+ signal at fertilisation is largely unchanged by advancing maternal age, but subtle changes in Ca2+ handling occur that may have more substantial impacts upon commonly used means of parthenogenetic activation. PMID:26785810

  6. Ca2+/H+ exchange in acidic vacuoles of Trypanosoma brucei.

    PubMed Central

    Vercesi, A E; Moreno, S N; Docampo, R

    1994-01-01

    The use of digitonin to permeabilize the plasma membrane of Trypanosoma brucei procyclic and bloodstream trypomastigotes allowed the identification of a non-mitochondrial nigericin-sensitive Ca2+ compartment. The proton ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) was able to cause Ca2+ release from this compartment, which was also sensitive to sodium orthovanadate. Preincubation of the cells with the vacuolar H(+)-ATPase inhibitor bafilomycin A1 greatly reduced the nigericin-sensitive Ca2+ compartment. Bafilomycin A1 inhibited the initial rate of ATP-dependent non-mitochondrial Ca2+ uptake and stimulated the initial rate of nigericin-induced Ca2+ release by permeabilized procyclic trypomastigotes. ATP-dependent and bafilomycin A1- and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl)-sensitive Acridine Orange uptake was demonstrated in permeabilized cells. Under these conditions Acridine Orange was concentrated in abundant cytoplasmic round vacuoles by a process inhibited by bafilomycin A1, NBD-Cl, nigericin, and Ca2+. Vanadate or EGTA significantly increased Acridine Orange uptake, while Ca2+ released Acridine Orange from these preparations, thus suggesting that the dye and Ca2+ were being accumulated in the same acidic vacuole. Acridine Orange uptake was reversed by nigericin, bafilomycin A1 and NH4Cl. The results are consistent with the presence of a Ca2+/H(+)-ATPase system pumping Ca2+ into an acidic vacuole, that we tentatively named the acidocalcisome. Images Figure 5 PMID:7998937

  7. The 3R polymorph of CaSi{sub 2}

    SciTech Connect

    Nedumkandathil, Reji; Benson, Daryn E.; Grins, Jekabs; Spektor, Kristina; Häussermann, Ulrich

    2015-02-15

    The Zintl phase CaSi{sub 2} commonly occurs in the 6R structure where puckered hexagon layers of Si atoms are stacked in an AA′BB′CC′ fashion. In this study we show that sintering of CaSi{sub 2} in a hydrogen atmosphere (30 bar) at temperatures between 200 and 700 °C transforms 6R-CaSi{sub 2} quantitatively into 3R-CaSi{sub 2}. In the 3R polymorph (space group R-3m (no. 166), a=3.8284(1), c=15.8966(4), Z=3) puckered hexagon layers are stacked in an ABC fashion. The volume per formula unit is about 3% larger compared to 6R-CaSi{sub 2}. First principles density functional calculations reveal that 6R and 3R-CaSi{sub 2} are energetically degenerate at zero Kelvin. With increasing temperature 6R-CaSi{sub 2} stabilizes over 3R because of its higher entropy. This suggests that 3R-CaSi{sub 2} should revert to 6R at elevated temperatures, which however is not observed up to 800 °C. 3R-CaSi{sub 2} may be stabilized by small amounts of incorporated hydrogen and/or defects. - Graphical abstract: The common 6R form of CaSi{sub 2} can be transformed quantitatively into 3R-CaSi{sub 2} upon sintering in a hydrogen atmosphere. - Highlights: • Quantitative and reproducible bulk synthesis of the rare 3R polymorph of CaSi{sub 2}. • Clarification of the energetic relation between 3R and conventional 6R form. • 3R-CaSi{sub 2} is presumably stabilized by small amounts of incorporated hydrogen and/or defects.

  8. Synchrony of Cardiomyocyte Ca2+ Release is Controlled by t-tubule Organization, SR Ca2+ Content, and Ryanodine Receptor Ca2+ Sensitivity

    PubMed Central

    Øyehaug, Leiv; Loose, Kristian Ø.; Jølle, Guro F.; Røe, Åsmund T.; Sjaastad, Ivar; Christensen, Geir; Sejersted, Ole M.; Louch, William E.

    2013-01-01

    Recent work has demonstrated that cardiomyocyte Ca2+release is desynchronized in several pathological conditions. Loss of Ca2+ release synchrony has been attributed to t-tubule disruption, but it is unknown if other factors also contribute. We investigated this issue in normal and failing myocytes by integrating experimental data with a mathematical model describing spatiotemporal dynamics of Ca2+ in the cytosol and sarcoplasmic reticulum (SR). Heart failure development in postinfarction mice was associated with progressive t-tubule disorganization, as quantified by fast-Fourier transforms. Data from fast-Fourier transforms were then incorporated in the model as a dyadic organization index, reflecting the proportion of ryanodine receptors located in dyads. With decreasing dyadic-organization index, the model predicted greater dyssynchrony of Ca2+ release, which exceeded that observed in experimental line-scan images. Model and experiment were reconciled by reducing the threshold for Ca2+ release in the model, suggesting that increased RyR sensitivity partially offsets the desynchronizing effects of t-tubule disruption in heart failure. Reducing the magnitude of SR Ca2+ content and release, whether experimentally by thapsigargin treatment, or in the model, desynchronized the Ca2+ transient. However, in cardiomyocytes isolated from SERCA2 knockout mice, RyR sensitization offset such effects. A similar interplay between RyR sensitivity and SR content was observed during treatment of myocytes with low-dose caffeine. Initial synchronization of Ca2+ release during caffeine was reversed as SR content declined due to enhanced RyR leak. Thus, synchrony of cardiomyocyte Ca2+ release is not only determined by t-tubule organization but also by the interplay between RyR sensitivity and SR Ca2+ content. PMID:23601316

  9. Quantal release of Ca2+ from intracellular stores by InsP3: tests of the concept of control of Ca2+ release by intraluminal Ca2+.

    PubMed

    Tregear, R T; Dawson, A P; Irvine, R F

    1991-03-22

    A possible mechanism for the generation of 'quantal' release of intracellular Ca2+ by InsP3 (Muallem et al., J. biol. Chem. 264, 205-212 (1989)) has been put forward in which intraluminal Ca2+ levels modulate InsP3 receptor structure (Irvine, FEBS Lett. 263, 5-9 (1990)). Here we have modelled such a steady-state mechanism, with an InsP3-sensitive store plus an InsP3-insensitive one, to test its ability to mimic published data. We have also performed experiments on InsP3-stimulated rat liver microsomes to test whether the model is consistent with one-way Ca2+ fluxes at a steady state. The model can simulate quantal release, in that InsP3 produces a release of part of the stored Ca2+ which is initially rapid relative to the one-way flux. In the original form of the model, in which InsP3-modulated Ca2+ binding to the intraluminal site opens the Ca2+ channel, the range of InsP3 concentrations needed to release Ca2+ is greater than that observed. When the model is changed so that Ca2(+)-modulated InsP3 binding opens the channels, the effective InsP3 range is shortened, but the quantal release effect is reduced. Other published data on one-way fluxes, and our own data on microsomes, can be simulated when leakage from the InsP3-insensitive store is adjusted to fit the observations; these data therefore do not test the existence of a steady state in the InsP3-sensitive store. We conclude that sensitivity of Ca2+ release to intraluminal Ca2+ provides a steady-state explanation of most, but not all, current quantal release observations.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:1675803

  10. FAST INVERSION OF SOLAR Ca II SPECTRA

    SciTech Connect

    Beck, C.; Choudhary, D. P.; Rezaei, R.; Louis, R. E.

    2015-01-10

    We present a fast (<<1 s per profile) inversion code for solar Ca II lines. The code uses an archive of spectra that are synthesized prior to the inversion under the assumption of local thermodynamic equilibrium (LTE). We show that it can be successfully applied to spectrograph data or more sparsely sampled spectra from two-dimensional spectrometers. From a comparison to a non-LTE inversion of the same set of spectra, we derive a first-order non-LTE correction to the temperature stratifications derived in the LTE approach. The correction factor is close to unity up to log τ ∼ –3 and increases to values of 2.5 and 4 at log τ = –6 in the quiet Sun and the umbra, respectively.

  11. Superdeformed and Triaxial States in ^{42}Ca.

    PubMed

    Hadyńska-Klȩk, K; Napiorkowski, P J; Zielińska, M; Srebrny, J; Maj, A; Azaiez, F; Valiente Dobón, J J; Kicińska-Habior, M; Nowacki, F; Naïdja, H; Bounthong, B; Rodríguez, T R; de Angelis, G; Abraham, T; Anil Kumar, G; Bazzacco, D; Bellato, M; Bortolato, D; Bednarczyk, P; Benzoni, G; Berti, L; Birkenbach, B; Bruyneel, B; Brambilla, S; Camera, F; Chavas, J; Cederwall, B; Charles, L; Ciemała, M; Cocconi, P; Coleman-Smith, P; Colombo, A; Corsi, A; Crespi, F C L; Cullen, D M; Czermak, A; Désesquelles, P; Doherty, D T; Dulny, B; Eberth, J; Farnea, E; Fornal, B; Franchoo, S; Gadea, A; Giaz, A; Gottardo, A; Grave, X; Grȩbosz, J; Görgen, A; Gulmini, M; Habermann, T; Hess, H; Isocrate, R; Iwanicki, J; Jaworski, G; Judson, D S; Jungclaus, A; Karkour, N; Kmiecik, M; Karpiński, D; Kisieliński, M; Kondratyev, N; Korichi, A; Komorowska, M; Kowalczyk, M; Korten, W; Krzysiek, M; Lehaut, G; Leoni, S; Ljungvall, J; Lopez-Martens, A; Lunardi, S; Maron, G; Mazurek, K; Menegazzo, R; Mengoni, D; Merchán, E; Mȩczyński, W; Michelagnoli, C; Mierzejewski, J; Million, B; Myalski, S; Napoli, D R; Nicolini, R; Niikura, M; Obertelli, A; Özmen, S F; Palacz, M; Próchniak, L; Pullia, A; Quintana, B; Rampazzo, G; Recchia, F; Redon, N; Reiter, P; Rosso, D; Rusek, K; Sahin, E; Salsac, M-D; Söderström, P-A; Stefan, I; Stézowski, O; Styczeń, J; Theisen, Ch; Toniolo, N; Ur, C A; Vandone, V; Wadsworth, R; Wasilewska, B; Wiens, A; Wood, J L; Wrzosek-Lipska, K; Ziȩbliński, M

    2016-08-01

    Shape parameters of a weakly deformed ground-state band and highly deformed slightly triaxial sideband in ^{42}Ca were determined from E2 matrix elements measured in the first low-energy Coulomb excitation experiment performed with AGATA. The picture of two coexisting structures is well reproduced by new state-of-the-art large-scale shell model and beyond-mean-field calculations. Experimental evidence for superdeformation of the band built on 0_{2}^{+} has been obtained and the role of triaxiality in the A∼40 mass region is discussed. Furthermore, the potential of Coulomb excitation as a tool to study superdeformation has been demonstrated for the first time. PMID:27541463

  12. 77 FR 15801 - Notice of Inventory Completion: California Department of Parks and Recreation, Sacramento, CA

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-16

    ... Mound site (CA-SAC-199) in Sacramento County, CA. This notice is published as part of the National Park..., nine individuals were removed from Morris Mound (site CA-SAC-199) in Sacramento County, CA....

  13. Experimental identification of Ca isotopic fractionations in higher plants

    NASA Astrophysics Data System (ADS)

    Cobert, Florian; Schmitt, Anne-Désirée; Bourgeade, Pascale; Labolle, François; Badot, Pierre-Marie; Chabaux, François; Stille, Peter

    2011-10-01

    Hydroponic experiments have been performed in order to identify the co-occurring geochemical and biological processes affecting the Ca isotopic compositions within plants. To test the influence of the Ca concentration and pH of the nutritive solution on the Ca isotopic composition of the different plant organs, four experimental conditions were chosen combining two different Ca concentrations (5 and 60 ppm) and two pHs (4 and 6). The study was performed on rapid growing bean plants in order to have a complete growth cycle. Several organs (root, stem, leaf, reproductive) were sampled at two different growth stages (10 days and 6 weeks of culture) and prepared for Ca isotopic measurements. The results allow to identify three Ca isotopic fractionation levels. The first one takes place when Ca enters the lateral roots, during Ca adsorption on cation-exchange binding sites in the apoplasm. The second one takes place when Ca is bound to the polygalacturonic acids (pectins) of the middle lamella of the xylem cell wall. Finally, the last fractionation occurs in the reproductive organs, also caused by cation-exchange processes with pectins. However, the cell wall structures of these organs and/or number of available exchange sites seem to be different to those of the xylem wall. These three physico-chemical fractionation mechanisms allow to enrich the organs in the light 40Ca isotope. The amplitude of the Ca isotopic fractionation within plant organs is highly dependent on the composition of the nutritive solution: low pH (4) and Ca concentrations (5 ppm) have no effect on the biomass increase of the plants but induce smaller fractionation amplitudes compared to those obtained from other experimental conditions. Thus, Ca isotopic signatures of bean plants are controlled by the external nutritive medium. This study highlights the potential of Ca isotopes to be applied in plant physiology (to identify Ca uptake, circulation and storage mechanisms within plants) and in

  14. Modelling Changes of the Paleogene Ca Budget Using Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Pabich, S.; Gussone, N. C.; Vollmer, C.; Palike, H.; Rabe, K.; Teichert, B. M.

    2014-12-01

    Understanding the earth's climate as well as the oceanic chemical and isotopic evolution in the past is one of the main aims in earth science. Ca as one of the major elements in the ocean is especially important. Its variation in concentration are controlled by different factors including the CO2 concentration of the atmosphere, continental weathering and Ca carbonate sedimentation. We used samples from IODP Exp. 320/321 to establish a δ44/40Ca paleo-seawater record between 45 and 25 Ma and model changes in the Ca budget through time. Our results show differences in the Eocene and Oligocene Ca isotope record of benthic foraminifers. The δ44/40Ca values during the Eocene are relatively constant with no significant fluctuations during phases of large short term CCD fluctuations[1]. The Oligocene is characterized by sediments with uniformly high carbonate content and increasing δ44/40Ca towards the late Oligocene. Past seawater δ44/40Ca values (Fig. 1) were calculated from the measured benthic foraminifer record applying the calibration for Gyroidinoides spp.[2]. The Ca budget during the Eocene is relatively constant and not affected by short term CCD fluctuations, indicating that they are too small to alter the isotopic Ca budget. The Oligocene, in contrast is characterized by a general increase in δ44/40Ca seawater values and a continuously deep CCD[1]. This is consistent with a massive long term (>1Ma) CaCO3 deposition and decreasing Ca concentration in the ocean water. To examine the preservation (dissolution and recrystallization) of the foraminifer test through time, we studied additionally the changes in the crystallographic orientations trough time by Electron Backscatter Diffraction (EBSD) analysis and Raman spectroscopy. As a final step we use our δ44/40Ca seawater record to run a combined Ca and C model showing the effect of Ca weathering input, carbonate remobilization and dolomitization on the Ca and carbonate system of seawater [1]. [1]Pälike H

  15. The many phases of CaC2

    NASA Astrophysics Data System (ADS)

    Konar, Sumit; Nylén, Johanna; Svensson, Gunnar; Bernin, Diana; Edén, Mattias; Ruschewitz, Uwe; Häussermann, Ulrich

    2016-07-01

    Polymorphic CaC2 was prepared by reacting mixtures of CaH2 and graphite with molar ratios between 1:1.8 and 1:2.2 at temperatures between 700 and 1400 °C under dynamic vacuum. These conditions provided a well controlled, homogeneous, chemical environment and afforded products with high purity. The products, which were characterized by powder X-ray diffraction, solid state NMR and Raman spectroscopy, represented mixtures of the three known polymorphs, tetragonal CaC2-I and monoclinic CaC2-II and -III. Their proportion is dependent on the nominal C/CaH2 ratio of the reaction mixture and temperature. Reactions with excess carbon produced a mixture virtually free from CaC2-I, whereas high temperatures (above 1100 °C) and C-deficiency favored the formation of CaC2-I. From first principles calculations it is shown that CaC2-I is dynamically unstable within the harmonic approximation. This indicates that existing CaC2-I is structurally/dynamically disordered and may possibly even occur as slightly carbon-deficient phase CaC2-δ. It is proposed that monoclinic II is the ground state of CaC2 and polymorph III is stable at temperatures above 200 °C. Tetragonal I represents a metastable, heterogeneous, phase of CaC2. It is argued that a complete understanding of the occurrence of three room temperature modifications of CaC2 will require a detailed characterization of compositional and structural heterogeneities within the high temperature form CaC2-IV, which is stable above 450 °C. The effect of high pressure on the stability of the monoclinic forms of CaC2 was studied in a diamond anvil cell using Raman spectroscopy. CaC2-II and -III transform into tetragonal CaC2-I at about 4 and 1GPa, respectively.

  16. A Ca2+-induced Ca2+ Release Mechanism Involved in Asynchronous Exocytosis at Frog Motor Nerve Terminals

    PubMed Central

    Narita, K.; Akita, T.; Osanai, M.; Shirasaki, T.; Kijima, H.; Kuba, K.

    1998-01-01

    The extent to which Ca2+-induced Ca2+ release (CICR) affects transmitter release is unknown. Continuous nerve stimulation (20–50 Hz) caused slow transient increases in miniature end-plate potential (MEPP) frequency (MEPP-hump) and intracellular free Ca2+ ([Ca2+]i) in presynaptic terminals (Ca2+-hump) in frog skeletal muscles over a period of minutes in a low Ca2+, high Mg2+ solution. Mn2+ quenched Indo-1 and Fura-2 fluorescence, thus indicating that stimulation was accompanied by opening of voltage-dependent Ca2+ channels. MEPP-hump depended on extracellular Ca2+ (0.05–0.2 mM) and stimulation frequency. Both the Ca2+- and MEPP-humps were blocked by 8-(N,N-diethylamino)octyl3,4,5-trimethoxybenzoate hydrochloride (TMB-8), ryanodine, and thapsigargin, but enhanced by CN−. Thus, Ca2+-hump is generated by the activation of CICR via ryanodine receptors by Ca2+ entry, producing MEPP-hump. A short interruption of tetanus (<1 min) during MEPP-hump quickly reduced MEPP frequency to a level attained under the effect of TMB-8 or thapsigargin, while resuming tetanus swiftly raised MEPP frequency to the previous or higher level. Thus, the steady/equilibrium condition balancing CICR and Ca2+ clearance occurs in nerve terminals with slow changes toward a greater activation of CICR (priming) during the rising phase of MEPP-hump and toward a smaller activation during the decay phase. A short pause applied after the end of MEPP- or Ca2+-hump affected little MEPP frequency or [Ca2+]i, but caused a quick increase (faster than MEPP- or Ca2+-hump) after the pause, whose magnitude increased with an increase in pause duration (<1 min), suggesting that Ca2+ entry-dependent inactivation, but not depriming process, explains the decay of the humps. The depriming process was seen by giving a much longer pause (>1 min). Thus, ryanodine receptors in frog motor nerve terminals are endowed with Ca2+ entry-dependent slow priming and fast inactivation mechanisms, as well as Ca2+ entry

  17. Evaluation of serum CA27.29, CA15-3 and CEA in patients with breast cancer.

    PubMed

    Hou, M F; Chen, Y L; Tseng, T F; Lin, C M; Chen, M S; Huang, C J; Huang, Y S; Hsieh, J S; Huang, T J; Jong, S B; Huang, Y F

    1999-09-01

    The Truquant BR radioimmunoassay (RIA) using monoclonal antibody BR 27.29 to recognize a peptide sequence on the MUC-1 gene product for quantification of the CA 27.29 antigen in serum was used in this report to evaluate in 145 patients with breast cancer and compared the other conventional serum markers such as CA15-3 and CEA. The upper limit of normal (25 u/ml) was determined from CA27.29 values 12.4 +/- 4.1 u/ml (mean +/- 3 S.D.) for 112 female subjects apparently free of disease. The CA15-3 levels above 25 u/ml and CEA levels above 5 ng/ml were considered positive values. Thirty-seven cases of 145 patients studied had elevated CA 27.29 levels (sensitivity: 25.5%), 35 of 145 had positive CA15-3 levels (sensitivity 24.1%) and 27 of 145 patients had positive CEA levels (sensitivity: 18.6%) (p < 0.05). One hundred and ten cases of the breast cancer patients (75.8%) did not have metastatic disease. In this group CA 27.29 sensitivity was 6.4%, while CA15-3 sensitivity was 5.5% and CEA sensitivity was 4.5% (p > 0.05). Mean values were 10.2 +/- 9.2 u/ml for CA 27.29, 14.1 +/- 5.6 u/ml for CA 15-3 and 1.7 +/- 1.5 ng/ml for CEA. Thirty-five patients (24.2%) had metastatic disease. In this group CA 27.29 sensitivity was 85.7%, CA15-3 sensitivity was 82.8% and CEA sensitivity was 62.8% (p < 0.05). Mean values for CA27.29 was 152.6 +/- 131.6 u/ml, CA15-3 was 123.1 +/- 107.6 u/ml and 21.8 +/- 36.9 ng/ml of CEA. With regard to the correlation of three tumor markers with clinical stages, patients had significantly higher levels of CA27.29 than CEA, but they were similar to CA 15-3 in metastatic breast cancer. These results suggest CA27.29 to be more sensitive and specific than CEA, but that it is similar to CA15-3 for metastatic breast cancer detection and monitoring.

  18. Metabolic Oscillations in Pancreatic Islets Depend on the Intracellular Ca2+ Level but Not Ca2+ Oscillations

    PubMed Central

    Merrins, Matthew J.; Fendler, Bernard; Zhang, Min; Sherman, Arthur; Bertram, Richard; Satin, Leslie S.

    2010-01-01

    Abstract Plasma insulin is pulsatile and reflects oscillatory insulin secretion from pancreatic islets. Although both islet Ca2+ and metabolism oscillate, there is disagreement over their interrelationship, and whether they can be dissociated. In some models of islet oscillations, Ca2+ must oscillate for metabolic oscillations to occur, whereas in others metabolic oscillations can occur without Ca2+ oscillations. We used NAD(P)H fluorescence to assay oscillatory metabolism in mouse islets stimulated by 11.1 mM glucose. After abolishing Ca2+ oscillations with 200 μM diazoxide, we observed that oscillations in NAD(P)H persisted in 34% of islets (n = 101). In the remainder of the islets (66%) both Ca2+ and NAD(P)H oscillations were eliminated by diazoxide. However, in most of these islets NAD(P)H oscillations could be restored and amplified by raising extracellular KCl, which elevated the intracellular Ca2+ level but did not restore Ca2+ oscillations. Comparatively, we examined islets from ATP-sensitive K+ (KATP) channel-deficient SUR1−/− mice. Again NAD(P)H oscillations were evident even though Ca2+ and membrane potential oscillations were abolished. These observations are predicted by the dual oscillator model, in which intrinsic metabolic oscillations and Ca2+ feedback both contribute to the oscillatory islet behavior, but argue against other models that depend on Ca2+ oscillations for metabolic oscillations to occur. PMID:20655835

  19. Aluminum Chloride Induces Osteoblasts Apoptosis via Disrupting Calcium Homeostasis and Activating Ca(2+)/CaMKII Signal Pathway.

    PubMed

    Cao, Zheng; Liu, Dawei; Zhang, Qiuyue; Sun, Xudong; Li, Yanfei

    2016-02-01

    Aluminum promotes osteoblast (OB) apoptosis. Apoptosis is induced by the disordered calcium homeostasis. Therefore, to investigate the relationship between Al-induced OB apoptosis and calcium homeostasis, calvarium OBs from neonatal rats (3-4 days) were cultured and exposed to 0.048-mg/mL Al(3+) or 0.048-mg/mL Al(3+) combined with 5 μM BAPTA-AM (OBs were pretreated with 5 μM BAPTA-AM for 1 h, then added 0.048 mg/mL Al(3+)), respectively. Then OB apoptosis rate, intracellular calcium ions concentration ([Ca(2+)]i), mRNA expression level of calmodulin (CaM), and protein expression levels of CaM and p-CaMKII in OBs were examined. The result showed that AlCl3 increased OB apoptosis rate, and [Ca(2+)]i and p-CaMKII expression levels and decreased CaM expression levels, whereas BAPTA-AM relieved the effects. These results proved that AlCl3 induced OB apoptosis by disrupting the intracellular Ca(2+) homeostasis and activating the Ca(2+)/CaMKII signal pathway. Our findings can provide new insights for revealing the apoptosis mechanism of OBs exposed to AlCl3.

  20. Oestrogen directly inhibits the cardiovascular L-type Ca{sup 2+} channel Ca{sub v}1.2

    SciTech Connect

    Ullrich, Nina D. . E-mail: ullrich@pyl.unibe.ch; Koschak, Alexandra; MacLeod, Kenneth T.

    2007-09-21

    Oestrogen can modify the contractile function of vascular smooth muscle and cardiomyocytes. The negative inotropic actions of oestrogen on the heart and coronary vasculature appear to be mediated by L-type Ca{sup 2+} channel (Ca{sub v}1.2) inhibition, but the underlying mechanisms remain elusive. We tested the hypothesis that oestrogen directly inhibits the cardiovascular L-type Ca{sup 2+} current, I {sub CaL}. The effect of oestrogen on I {sub CaL} was measured in Ca{sub v}1.2-transfected HEK-293 cells using the whole-cell patch-clamp technique. The current revealed typical activation and inactivation profiles of nifedipine- and cadmium-sensitive I {sub CaL}. Oestrogen (50 {mu}M) rapidly reduced I {sub CaL} by 50% and shifted voltage-dependent activation and availability to more negative potentials. Furthermore, oestrogen blocked the Ca{sup 2+} channel in a rate-dependent way, exhibiting higher efficiency of block at higher stimulation frequencies. Our data suggest that oestrogen inhibits I {sub CaL} through direct interaction of the steroid with the channel protein.

  1. EF-hand protein Ca2+ buffers regulate Ca2+ influx and exocytosis in sensory hair cells.

    PubMed

    Pangršič, Tina; Gabrielaitis, Mantas; Michanski, Susann; Schwaller, Beat; Wolf, Fred; Strenzke, Nicola; Moser, Tobias

    2015-03-01

    EF-hand Ca(2+)-binding proteins are thought to shape the spatiotemporal properties of cellular Ca(2+) signaling and are prominently expressed in sensory hair cells in the ear. Here, we combined genetic disruption of parvalbumin-α, calbindin-D28k, and calretinin in mice with patch-clamp recording, in vivo physiology, and mathematical modeling to study their role in Ca(2+) signaling, exocytosis, and sound encoding at the synapses of inner hair cells (IHCs). IHCs lacking all three proteins showed excessive exocytosis during prolonged depolarizations, despite enhanced Ca(2+)-dependent inactivation of their Ca(2+) current. Exocytosis of readily releasable vesicles remained unchanged, in accordance with the estimated tight spatial coupling of Ca(2+) channels and release sites (effective "coupling distance" of 17 nm). Substitution experiments with synthetic Ca(2+) chelators indicated the presence of endogenous Ca(2+) buffers equivalent to 1 mM synthetic Ca(2+)-binding sites, approximately half of them with kinetics as fast as 1,2-Bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA). Synaptic sound encoding was largely unaltered, suggesting that excess exocytosis occurs extrasynaptically. We conclude that EF-hand Ca(2+) buffers regulate presynaptic IHC function for metabolically efficient sound coding. PMID:25691754

  2. Apocalmodulin and Ca2+ calmodulin bind to the same region on the skeletal muscle Ca2+ release channel

    NASA Technical Reports Server (NTRS)

    Moore, C. P.; Rodney, G.; Zhang, J. Z.; Santacruz-Toloza, L.; Strasburg, G.; Hamilton, S. L.

    1999-01-01

    The skeletal muscle Ca2+ release channel (RYR1) is regulated by calmodulin in both its Ca2+-free (apocalmodulin) and Ca2+-bound (Ca2+ calmodulin) states. Apocalmodulin is an activator of the channel, and Ca2+ calmodulin is an inhibitor of the channel. Both apocalmodulin and Ca2+ calmodulin binding sites on RYR1 are destroyed by a mild tryptic digestion of the sarcoplasmic reticulum membranes, but calmodulin (either form), bound to RYR1 prior to tryptic digestion, protects both the apocalmodulin and Ca2+ calmodulin sites from tryptic destruction. The protected sites are after arginines 3630 and 3637 on RYR1. These studies suggest that both Ca2+ calmodulin and apocalmodulin bind to the same or overlapping regions on RYR1 and block access of trypsin to sites at amino acids 3630 and 3637. This sequence is part of a predicted Ca2+ CaM binding site of amino acids 3614-3642 [Takeshima, H., et al. (1989) Nature 339, 439-445].

  3. Improving transesterification acitvity of CaO with hydration technique.

    PubMed

    Yoosuk, Boonyawan; Udomsap, Parncheewa; Puttasawat, Buppa; Krasae, Pawnprapa

    2010-05-01

    An efficient technique for increasing the transesterification activity of CaO obtained from calcination of CaCO(3) was proposed in order to make them highly suitable for use as heterogeneous catalysts for biodiesel production. CaO was refluxed in water followed by the synthesis of the oxide from hydroxide species. The characterization results indicate that this procedure substantially increases both the specific surface area and the amount of basic site. Hydration and subsequent calcination also generates a new calcium oxide with less crystalline. Transesterification of palm olein was used to determine the activity of catalysts to show that the decomposed-hydrated CaO exhibits higher catalytic activity than CaO generated from calcination of CaCO(3). The methyl ester content was enhanced 18.4 wt.%. PMID:20089395

  4. Expression of CA III in rodent models of obesity.

    PubMed

    Stanton, L W; Ponte, P A; Coleman, R T; Snyder, M A

    1991-06-01

    To achieve a better understanding of the biochemical basis of obesity, we have undertaken comparative analyses of adipose tissue of lean and obese mice. By two-dimensional gel analysis, carbonic anhydrase-III (CA III) has been identified as a major constituent of murine adipose tissue. Quantitative comparisons of CA III protein and mRNA levels indicate that this enzyme is expressed at lower levels in adipose tissue from animals that were either genetically obese or had experimentally induced obesity compared to levels in the corresponding lean controls. This decrease in CA III expression was unique to adipose tissue, since other CA III-containing organs and tissues did not show a change when lean and obese animals were compared. Additionally, levels of CA III in adipose tissue from obese animals responded to acute changes in energy balance of the animal. These results are discussed in light of possible metabolic roles for CA III.

  5. Factors influencing serum concentration of CA125 and CA15-3 in Iranian healthy postmenopausal women.

    PubMed

    Dehaghani, Alamtaj Samsami; Ghiam, Alireza Fotouhi; Hosseini, Marjan; Mansouri, Sareh; Ghaderi, Abbas

    2007-01-01

    Screening for breast and ovarian cancers are required due to the late stage at diagnosis and poor survival. Serum CA125 and CA15-3 are important cancerdetecting agents in patients with ovarian and breast cancers, respectively. Elevation of CA125 and CA15-3 level correlates with malignant and non-malignant conditions. Moreover, a series of individual characteristics affect the serum level of these markers. The objective of the present study was to evaluate CA125 and CA15-3 levels in cancer-free postmenopausal women to investigate the impacts of patient parameters on the serum level of these markers. 203 subjects were studied prospectively. Serum CA125 and CA15-3 assessment was done subsequent to the direct interview. The associations between marker levels and presenting features were examined. CA125 and CA15-3 levels were elevated in 35 (17.2%) and 12 (5.9%) of persons, respectively. A higher CA125 level was associated with advanced age (p = 0.046), while a lower level was correlated with hormone replacement therapy (HRT) and having smoking habits (p = 0.000 and p = 0.01, respectively). CA15-3 level was remarkably lower amongst oral contraceptive (OCP) users (p = 0.03). Serum marker levels were not significantly related to menarche age, age at menopause, height, weight, BMI and parity. Serum CA125 is imperative indicator for malignancies of the ovary; however, personal and medical factors influence its serum level. A fair interpretation of results must be due to an accurate attention to the individual characteristics.

  6. Citrus bergamia Risso Elevates Intracellular Ca2+ in Human Vascular Endothelial Cells due to Release of Ca2+ from Primary Intracellular Stores

    PubMed Central

    Kang, Purum; Han, Seung Ho; Moon, Hea Kyung; Lee, Jeong-Min; Kim, Hyo-Keun; Min, Sun Seek; Seol, Geun Hee

    2013-01-01

    The purpose of the present study is to examine the effects of essential oil of Citrus bergamia Risso (bergamot, BEO) on intracellular Ca2+ in human umbilical vein endothelial cells. Fura-2 fluorescence was used to examine changes in intracellular Ca2+ concentration [Ca2+]i . In the presence of extracellular Ca2+, BEO increased [Ca2+]i , which was partially inhibited by a nonselective Ca2+ channel blocker La3+. In Ca2+-free extracellular solutions, BEO increased [Ca2+]i in a concentration-dependent manner, suggesting that BEO mobilizes intracellular Ca2+. BEO-induced [Ca2+]i increase was partially inhibited by a Ca2+-induced Ca2+ release inhibitor dantrolene, a phospholipase C inhibitor U73122, and an inositol 1,4,5-triphosphate (IP3)-gated Ca2+ channel blocker, 2-aminoethoxydiphenyl borane (2-APB). BEO also increased [Ca2+]i in the presence of carbonyl cyanide m-chlorophenylhydrazone, an inhibitor of mitochondrial Ca2+ uptake. In addition, store-operated Ca2+ entry (SOC) was potentiated by BEO. These results suggest that BEO mobilizes Ca2+ from primary intracellular stores via Ca2+-induced and IP3-mediated Ca2+ release and affect promotion of Ca2+ influx, likely via an SOC mechanism. PMID:24348719

  7. Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit

    PubMed Central

    Prince, Luke Y.; Bacon, Travis J.; Tigaret, Cezar M.; Mellor, Jack R.

    2016-01-01

    The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval. PMID:27799909

  8. Imaging local Ca2+ signals in cultured mammalian cells.

    PubMed

    Lock, Jeffrey T; Ellefsen, Kyle L; Settle, Bret; Parker, Ian; Smith, Ian F

    2015-01-01

    Cytosolic Ca2+ ions regulate numerous aspects of cellular activity in almost all cell types, controlling processes as wide-ranging as gene transcription, electrical excitability and cell proliferation. The diversity and specificity of Ca2+ signaling derives from mechanisms by which Ca2+ signals are generated to act over different time and spatial scales, ranging from cell-wide oscillations and waves occurring over the periods of minutes to local transient Ca2+ microdomains (Ca2+ puffs) lasting milliseconds. Recent advances in electron multiplied CCD (EMCCD) cameras now allow for imaging of local Ca2+ signals with a 128 x 128 pixel spatial resolution at rates of >500 frames sec(-1) (fps). This approach is highly parallel and enables the simultaneous monitoring of hundreds of channels or puff sites in a single experiment. However, the vast amounts of data generated (ca. 1 Gb per min) render visual identification and analysis of local Ca2+ events impracticable. Here we describe and demonstrate the procedures for the acquisition, detection, and analysis of local IP3-mediated Ca2+ signals in intact mammalian cells loaded with Ca2+ indicators using both wide-field epi-fluorescence (WF) and total internal reflection fluorescence (TIRF) microscopy. Furthermore, we describe an algorithm developed within the open-source software environment Python that automates the identification and analysis of these local Ca2+ signals. The algorithm localizes sites of Ca2+ release with sub-pixel resolution; allows user review of data; and outputs time sequences of fluorescence ratio signals together with amplitude and kinetic data in an Excel-compatible table. PMID:25867132

  9. SNL/CA Environmental Management System Program Manual.

    SciTech Connect

    Larsen, Barbara L.

    2007-04-01

    The Sandia National Laboratories, California (SNL/CA) Environmental Management System (EMS) Program Manual documents the elements of the site EMS Program. The SNL/CA EMS Program conforms to the International Standard on Environmental Management Systems, ISO 14001:2004. Elements of the ISO standard overlap with those of Department of Energy (DOE) Order 450.1, thus SNL/CA's EMS program also meets the DOE requirements.

  10. Expression of Ca2+-ATPase and Na+/Ca2+-exchanger is upregulated during epithelial Ca2+ transport in hypodermal cells of the isopod Porcellio scaber.

    PubMed

    Ziegler, A; Weihrauch, D; Towle, D W; Hagedorn, M

    2002-09-01

    It is thought that a plasma membrane Ca(2+)-transport ATPase (PMCA) and a Na(+)/Ca(2+)-exchange (NCE) mechanism are involved in epithelial Ca(2+) transport (ECT) in a variety of crustacean epithelia. The sternal epithelium of the terrestrial isopod Porcellio scaber was used as a model for the analysis of Ca(2+)-extrusion mechanisms in the hypodermal epithelium. Using RT-PCR, we amplified a cDNA fragment of 1173 bp that encodes a protein sequence possessing 72% identity to the PMCA from Drosophila melanogaster and a cDNA fragment of 791 bp encoding a protein sequence with 50% identity to the NCE from Loligo opalescens. Semiquantitative RT-PCR revealed that the expression of both mRNAs increases from the non-Ca(2+)-transporting condition to the stages of CaCO(3) deposit formation and degradation. During Ca(2+)-transporting stages, the expression of PMCA and NCE was larger in the anterior sternal epithelium (ASE) than in the posterior sternal epithelium (PSE). The results demonstrate for the first time the expression of a PMCA and a NCE in the hypodermal epithelium of a crustacean and indicate a contribution of these transport mechanisms in ECT.

  11. Calbindin-D28K dynamically controls TRPV5-mediated Ca2+ transport

    PubMed Central

    Lambers, Tim T; Mahieu, Frank; Oancea, Elena; Hoofd, Louis; de Lange, Frank; Mensenkamp, Arjen R; Voets, Thomas; Nilius, Bernd; Clapham, David E; Hoenderop, Joost G; Bindels, René J

    2006-01-01

    In Ca2+-transporting epithelia, calbindin-D28K (CaBP28K) facilitates Ca2+ diffusion from the luminal Ca2+ entry side of the cell to the basolateral side, where Ca2+ is extruded into the extracellular compartment. Simultaneously, CaBP28K provides protection against toxic high Ca2+ levels by buffering the cytosolic Ca2+ concentration ([Ca2+]i) during high Ca2+ influx. CaBP28K consistently colocalizes with the epithelial Ca2+ channel TRPV5, which constitutes the apical entry step in renal Ca2+-transporting epithelial cells. Here, we demonstrate using protein-binding analysis, subcellular fractionation and evanescent-field microscopy that CaBP28K translocates towards the plasma membrane and directly associates with TRPV5 at a low [Ca2+]i. 45Ca2+ uptake measurements, electrophysiological recordings and transcellular Ca2+ transport assays of lentivirus-infected primary rabbit connecting tubule/distal convolute tubule cells revealed that associated CaBP28K tightly buffers the flux of Ca2+ entering the cell via TRPV5, facilitating high Ca2+ transport rates by preventing channel inactivation. In summary, CaBP28K acts in Ca2+-transporting epithelia as a dynamic Ca2+ buffer, regulating [Ca2+] in close vicinity to the TRPV5 pore by direct association with the channel. PMID:16763551

  12. Hindrance in the fusion of {sup 48}Ca+{sup 48}Ca

    SciTech Connect

    Esbensen, H.; Jiang, C. L.; Stefanini, A. M.

    2010-11-15

    The coupled-channels technique is applied to analyze recent fusion data for {sup 48}Ca+{sup 48}Ca. The calculations include the excitations of the low-lying 2{sup +}, 3{sup -}, and 5{sup -} states in projectile and target, and the influence of mutual excitations as well as the two-phonon quadrupole excitations is also investigated. The ion-ion potential is obtained by double-folding the nuclear densities of the reacting nuclei with the M3Y+repulsion effective interaction but a standard Woods-Saxon potential is also applied. The data exhibit a strong hindrance at low energy compared to calculations that are based on a standard Woods-Saxon potential but they can be reproduced quite well by applying the M3Y+repulsion potential with an adjusted radius of the nuclear density. The influence of the polarization of high-lying states on the extracted radius is discussed.

  13. Amorphous Ca-phosphate precursors for Ca-carbonate biominerals mediated by Chromohalobacter marismortui.

    PubMed

    Rivadeneyra, María Angustias; Martín-Algarra, Agustín; Sánchez-Román, Mónica; Sánchez-Navas, Antonio; Martín-Ramos, José Daniel

    2010-07-01

    Although diverse microbial metabolisms are known to induce the precipitation of carbonate minerals, the mechanisms involved in the bacterial mediation, in particular nucleation, are still debated. The study of aragonite precipitation by Chromohalobacter marismortui during the early stages (3-7 days) of culture experiments, and its relation to bacterial metabolic pathways, shows that: (1) carbonate nucleation occurs after precipitation of an amorphous Ca phosphate precursor phase on bacterial cell surfaces and/or embedded in bacterial films; (2) precipitation of this precursor phase results from local high concentrations of PO(4)(3-) and Ca(2+) binding around bacterial cell envelopes; and (3) crystalline nanoparticles, a few hundred nanometres in diametre, form after dissolution of precursor phosphate globules, and later aggregate, allowing the accretion of aragonite bioliths.

  14. 118. STUDY DRAWING FOR WATER WHEELS, CA. 1822 Frederic Graff, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    118. STUDY DRAWING FOR WATER WHEELS, CA. 1822 Frederic Graff, Collection of the Franklin Institute - Fairmount Waterworks, East bank of Schuylkill River, Aquarium Drive, Philadelphia, Philadelphia County, PA

  15. Ca²+ sorption on regenerated cellulose fibres.

    PubMed

    Fitz-Binder, Christa; Bechtold, Thomas

    2012-10-01

    High calcium content in cellulose materials can cause considerable problems in pulp processing, textile chemical treatment and consumer use, e.g. dyeing operations or household laundry. The Ca(2+) binding capacity of cellulose also is of relevance in food and medical applications. Through their carboxyl group content regenerated cellulose fibres can act as weak anion exchangers, thus all types of regenerated cellulose fibres such as lyocell, viscose and modal fibres, show a distinct ability to bind Ca(2+) ions. The binding capacity is limited by the carboxyl group content, which was determined with 15 mmol/kg for lyocell fibres and 20 mmol/kg for viscose fibres, using the Methylene Blue sorption method. The presence of bound Ca(2+) also was demonstrated by complex formation with alizarin. The molar ratio between carboxylic group content and bound Ca(2+) ions was one Ca(2+) ion for a single carboxyl group. As a result of Ca(2+) sorption a positive net charge of the cellulose results and another anion has to be bound as counter ion for reasons of charge neutralisation. Results of potentiometric titrations indicate HCO(3)(-) to be present as counter ion in the Ca(2+) cellulose system. Thus under the experimental conditions studied, bound Ca(2+) is proposed to be present in the form COO(-)Ca(2+)HCO(3)(-).

  16. Pharmacological analysis of intracellular Ca2+ signalling: problems and pitfalls.

    PubMed

    Taylor, C W; Broad, L M

    1998-09-01

    The complex changes in intracellular Ca2+ concentration that follow cell stimulation reflect the concerted activities of Ca2+ channels in the plasma membrane and in the membranes of intracellular stores, and the opposing actions of the mechanisms that extrude Ca2+ from the cytosol. Disentangling the roles of each of these processes is hampered by the lack of adequately selective pharmacological tools. In this review, Colin Taylor and Lisa Broad summarize the more serious problems associated with some of the commonly used drugs, and describe specific situations in which the multiple effects of drugs on Ca2(+)-signalling pathways have confused analysis of these pathways.

  17. Pathways for energization of Ca in Mercury's exosphere

    NASA Astrophysics Data System (ADS)

    Killen, Rosemary M.

    2016-04-01

    We investigate the possible pathways to produce the extreme energy observed in the calcium exosphere of Mercury. Any mechanism must explain the facts that Ca in Mercury's exosphere is extremely hot, that it is seen almost exclusively on the dawnside of the planet, and that its content varies seasonally, not sporadically. Simple diatomic molecules or their clusters are considered, focusing on calcium oxides while acknowledging that Ca sulfides may also be the precursor molecules. We first discuss impact vaporization to justify the assumption that CaO and Ca-oxide clusters are expected from impacts on Mercury. Then we discuss processes by which the atomic Ca is energized to a 70,000 K gas. The processes considered are (1) electron-impact dissociation of CaO molecules, (2) spontaneous dissociation of Ca-bearing molecules following impact vaporization, (3) shock-induced dissociative ionization, (4) photodissociation and (5) sputtering. We conclude that electron-impact dissociation cannot produce the required abundance of Ca, and sputtering cannot reproduce the observed spatial and temporal variation that is measured. Spontaneous dissociation is unlikely to result in the high energy that is seen. Of the two remaining processes, shock-induced dissociative ionization produces the required energy and comes close to producing the required abundance, but rates are highly dependent on the incoming velocity distribution of the impactors. Photodissociation probably can produce the required abundance of Ca, but simulations show that photodissociation cannot reproduce the observed spatial distribution.

  18. TRPV5-mediated Ca2+ Reabsorption and Hypercalciuria

    NASA Astrophysics Data System (ADS)

    Renkema, Kirsten Y.; Hoenderop, Joost G. J.; Bindels, René J. M.

    2007-04-01

    The concerted action of the intestine, kidney and bone results in the maintenance of a normal Ca2+ balance, a mechanism that is tightly controlled by the calciotropic hormones vitamin D, parathyroid hormone and calcitonin. Disturbances in the Ca2+ balance have been linked to diverse pathophysiological disorders like urolithiasis, hypertension, electroencephalogram abnormalities and rickets. Importantly, the final amount of Ca2+ that is released from the body is determined in the distal part of the nephron, where active Ca2+ reabsorption occurs. Here, Transient Receptor Potential Vanilloid member 5 (TRPV5), a highly Ca2+-selective channel, has been recognized as the gatekeeper of active Ca2+ reabsorption. The in vivo relevance of TRPV5 has been further investigated by the characterization of TRPV5 knockout (TRPV5-/-) mice, which exhibit severe disturbances in renal Ca2+ handling, such as profound hypercalciuria, intestinal Ca2+ hyperabsorption and reduced bone thickness. Hypercalciuria increases the risk of kidney stone formation in these mice. This review highlights our current knowledge about TRPV5-mediated Ca2+ reabsorption and emphasizes the physiological relevance and the clinical implications related to the TRPV5-/- mice model.

  19. 41Ca - a possible neutron specific biomarker in tooth enamel

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Arazi, A.; Faestermann, T.; Knie, K.; Korschinek, G.; Maier, H. J.; Nakamura, N.; Rühm, W.; Rugel, G.

    2004-08-01

    The measurement of long-lived radionuclides, produced by neutrons originating from the atomic-bomb explosions, offers the possibility to reconstruct neutron fluences to which survivors in Hiroshima and Nagasaki were exposed. The long-lived radionuclide, 41Ca (T1/2=103 000 years), is suggested here as a means for a retrospective determination of thermal neutron fluences, directly within the human body of a survivor. As proper material tooth enamel is proposed. The 41Ca signal in tooth enamel may be correlated with the exposure to A-bomb induced thermal neutron fluences, provided the natural background level of 41Ca/Ca is significantly lower. Therefore, tooth samples of unexposed survivors of the A-bomb explosions have been examined by means of accelerator mass spectrometry, in order to quantify the natural background level of 41Ca/Ca. Measured 41Ca/Ca ratios were confirmed to be as low as about 2 × 10-15. Thus, the A-bomb induced additional signal should be detectable for survivors at epidemiological relevant distances. Since tooth enamel had already been used as a dosemeter for gamma radiation from the A-bomb explosion, the detection of 41Ca in tooth enamel would allow, for the first time, an assessment of both, γ-ray and neutron exposures in the same biological material.

  20. Semantic web data warehousing for caGrid.

    PubMed

    McCusker, James P; Phillips, Joshua A; González Beltrán, Alejandra; Finkelstein, Anthony; Krauthammer, Michael

    2009-10-01

    The National Cancer Institute (NCI) is developing caGrid as a means for sharing cancer-related data and services. As more data sets become available on caGrid, we need effective ways of accessing and integrating this information. Although the data models exposed on caGrid are semantically well annotated, it is currently up to the caGrid client to infer relationships between the different models and their classes. In this paper, we present a Semantic Web-based data warehouse (Corvus) for creating relationships among caGrid models. This is accomplished through the transformation of semantically-annotated caBIG Unified Modeling Language (UML) information models into Web Ontology Language (OWL) ontologies that preserve those semantics. We demonstrate the validity of the approach by Semantic Extraction, Transformation and Loading (SETL) of data from two caGrid data sources, caTissue and caArray, as well as alignment and query of those sources in Corvus. We argue that semantic integration is necessary for integration of data from distributed web services and that Corvus is a useful way of accomplishing this. Our approach is generalizable and of broad utility to researchers facing similar integration challenges.

  1. A new tumor marker: CA125 for ovarian carcinomas

    SciTech Connect

    Sakahara, H.; Endo, K.; Nakajima, K.; Nakashima, T.; Koizumi, M.; Ohta, H.; Torizuka, K.; Konishi, I.; Fujii, S.; Mori, T.

    1985-05-01

    To evaluate CA125 as a tumor marker for ovarian carcinomas, CA125 concentrations were measured by the simultaneous immunoradiometric assay. The binding of I-125 labeled monoclonal antibody to the bead-bound antigen was greatly influenced by many factors, such as the incubation time, pH, IgG concentrations of samples, the sequence of addition of the tracer and samples and so on. By applying the forward two-step assay, diminished binding was observed than in the simultaneous assay, probably due to the relatively low affinity of the antibody. This simultaneous immunoradiometric assay resulted in the ''prozone'' or ''hook'' effect at high CA125 samples and proper dilution was necessary to determine the accurate CA125 values. All 72 normal control subjects had low concentrations of under 35 U/ml. Elevated serum CA125 was observed in 43% (9/21) cases with malignant ovarian tumors, depending on the stage and the histopathological findings. All 4 serous cystadenocarcinomas and 2 of 3 endometrioid carcinomas were positive and the measurement of serum CA125 was useful in the sequential monitoring of these cases. In contrast, 51 benign gynecological diseases, none had elevated serum CA125 except one with follicular cyst. Among 75 cases with non-gynecological benign and malignant diseases, only 1 of 12 gastric carcinomas and 2 of 13 pancreatic carcinomas had elevated CA125 levels. In summary, CA125 is a promising and relatively specific marker for ovarian carcinomas.

  2. Study of OSL in NaF: Ca,Cu

    NASA Astrophysics Data System (ADS)

    More, Y. K.; Wankhede, S. P.; Moharil, S. V.

    2013-06-01

    Sodium Fluoride containing Cu+ ions was prepared by R.A.P. followed by melt-quenching technique. Results on photo, thermo and optically stimulated luminescence in NaF:Ca,Cu are reported. OSL sensitivity of NaF:Ca,Cu is approximately 2 times than that of standard phosphor LMP. The rate of OSL depletion for 90% decay for NaF:Ca,Cu is 0.3 times as that of OSL phosphor LMP. NaF:Ca,Cu thus deserves much more attention than it has received up till now.

  3. 3. HISTORIC PHOTOGRAPH, VIEW TO GRUMMAN AVENUE BRIDGE, CA. COLLECTION ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. HISTORIC PHOTOGRAPH, VIEW TO GRUMMAN AVENUE BRIDGE, CA. COLLECTION CONNECTICUT DEPARTMENT OF TRANSPORTATION. - Merritt Parkway, Grumman Avenue Bridge, Spanning Merritt Parkway, Norwalk, Fairfield County, CT

  4. 6. HISTORIC PHOTOGRAPH, VIEW TO GRUMMAN AVENUE BRIDGE, CA. 1940. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. HISTORIC PHOTOGRAPH, VIEW TO GRUMMAN AVENUE BRIDGE, CA. 1940. COLLECTION CONNECTICUT DEPARTMENT OF TRANSPORTATION. - Merritt Parkway, Grumman Avenue Bridge, Spanning Merritt Parkway, Norwalk, Fairfield County, CT

  5. 4. HISTORIC PHOTOGRAPH, DETAIL OF ABUTMENT, GRIFFIN RELIEF SCULPTURE, CA. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. HISTORIC PHOTOGRAPH, DETAIL OF ABUTMENT, GRIFFIN RELIEF SCULPTURE, CA. 1940. COLLECTION CONNECTICUT DEPARTMENT OF TRANSPORTATION. - Merritt Parkway, Grumman Avenue Bridge, Spanning Merritt Parkway, Norwalk, Fairfield County, CT

  6. 5. HISTORIC PHOTOGRAPH, DETAIL OF BEARING WALL IN UNDERPASS, CA. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. HISTORIC PHOTOGRAPH, DETAIL OF BEARING WALL IN UNDERPASS, CA. 1940, COLLECTION CONNECTICUT DEPARTMENT OF TRANSPORTATION. - Merritt Parkway, Grumman Avenue Bridge, Spanning Merritt Parkway, Norwalk, Fairfield County, CT

  7. Studies of Ca{sup 2+} binding in spinach photosytem II using {sup 45}Ca{sup 2+}

    SciTech Connect

    Aedelroth, P.; Lindberg, K.; Andreasson, L.E.

    1995-07-18

    The Ca{sup 2+}-binding properties of photosystem II were investigated with radioactive {sup 45}Ca{sup 2+}. PS II membranes, isolated from spinach grown on a medium containing {sup 45}Ca{sup 2+}, contained 1.5 Ca{sup 2+} per PS II unit. Approximately half of the incorporated radioactivity was lost after incubation for 30 h in nonradioactive buffer. About 1 Ca{sup 2+}/PS II bound slowly to Ca{sup 2+}-depleted membranes in the presence of the extrinsic 16- and 23-kDa polypeptides in parallel with restoration of oxygen-evolving activity. The binding was heterogeneous with dissociation constants of 60 {mu}M (0.7 Ca{sup 2+}/PS II) and 1.7 mM (0.3 Ca{sup 2+}/ PS II), respectively, which could reflect different affinities of the dark-stable S-states for Ca{sup 2+}. The reactivation of oxygen-evolving activity closely followed the binding of Ca{sup 2+}, showing that a single exchangeable Ca{sup 2+} per PS II is sufficient for the water-splitting reaction to function. In PS II, depleted of the 16- and 23-kDa polypeptides, about 0.7 exchangeable Ca{sup 2+}/PS II binds with a dissociation constant of 26 {mu}M, while 0.3 Ca{sup 2+} binds with a much weaker affinity (K{sub d} > 0.5 mM). The rate of binding of Ca{sup 2+} in the absence of the two extrinsic polypeptides was significantly higher than with the polypeptides bound. The rate of dissociation of bound Ca{sup 2+} in the dark, which had a half-time of about 80 h in intact PS H, increased in the absence of the 16-and 23-kDa polypeptides and showed a further increase after the additional removal of the 33-kDa protein and manganese. The rate of dissociation was also significantly faster in weak light than in the dark. Removal of the 33-kDa donor-side polypeptide together with the two lighter ones led to a reduction in the amount of bound Ca{sup 2+}, while practically no Ca{sup 2+} bound after treatments to dissociate also the manganese of the water-oxidizing site. 34 refs., 9 figs., 2 tabs.

  8. Deficits of neuronal density in CA1 and synaptic density in the dentate gyrus, CA3 and CA1, in a mouse model of Down syndrome.

    PubMed

    Kurt, M Ayberk; Kafa, M Ilker; Dierssen, Mara; Davies, D Ceri

    2004-10-01

    Ts65Dn mice are partially trisomic for the distal region of MMU16, which is homologous with the obligate segment of HSA21 triplicated in Down syndrome (DS). Ts65Dn mice are impaired in learning tasks that require an intact hippocampus. In order to investigate the neural basis of these deficits in this mouse model of Down syndrome, quantitative light and electron microscopy were used to compare the volume densities of neurons and synapses in the hippocampus of adult Ts65Dn (n=4) and diploid mice (n=4). Neuron density was significantly lower in the CA1 of Ts65Dn compared to diploid mice (p<0.01). Total synapse density was significantly lower in the dentate gyrus (DG; p<0.001), CA3 (p<0.05) and CA1 (p<0.001) of Ts65Dn compared to diploid mice. The synapse-to-neuron ratio was significantly lower in the DG (p<0.001), CA3 (p<0.01) and CA1 (p<0.001) of Ts65Dn compared to diploid mice. When the data were broken down by synapse type, asymmetric synapse density was found to be significantly lower in the DG (p<0.001), CA3 (p<0.05) and CA1 (p<0.001) of Ts65Dn compared to diploid mice, while such a difference in symmetric synapse density was only present in the DG (p<0.01). The asymmetric synapse-to-neuron ratio was significantly lower in the DG (p<0.001), CA3 (p<0.01) and CA1 (p<0.001) of Ts65Dn compared to diploid mice, but there were no such significant differences in symmetric synapse-to-neuron ratios. These results suggest that impaired synaptic connectivity in the hippocampus of Ts65Dn mice underlies, at least in part, their cognitive impairment.

  9. Sr2+/Ca2+ and 44Ca/40Ca fractionation during inorganic calcite formation: III. Impact of salinity/ionic strength

    PubMed Central

    Tang, Jianwu; Niedermayr, Andrea; Köhler, Stephan J.; Böhm, Florian; Kısakürek, Basak; Eisenhauer, Anton; Dietzel, Martin

    2012-01-01

    In order to apply Sr/Ca and 44Ca/40Ca fractionation during calcium carbonate (CaCO3) formation as a proxy to reconstruct paleo-environments, it is essential to evaluate the impact of various environmental factors. In this study, a CO2 diffusion technique was used to crystallize inorganic calcite from aqueous solutions at different ionic strength/salinity by the addition of NaCl at 25 °C. Results show that the discrimination of Sr2+ versus Ca2+ during calcite formation is mainly controlled by precipitation rate (R in μmol/m2/h) and is weakly influenced by ionic strength/salinity. In analogy to Sr incorporation, 44Ca/40Ca fractionation during precipitation of calcite is weakly influenced by ionic strength/salinity too. At 25 °C the calcium isotope fractionation between calcite and aqueous calcium ions (Δ44/40Cacalcite-aq = δ44/40Cacalcite − δ44/40Caaq) correlates inversely to log R values for all experiments. In addition, an inverse relationship between Δ44/40Cacalcite-aq and log DSr, which is independent of temperature, precipitation rate, and aqueous (Sr/Ca)aq ratio, is not affected by ionic strength/salinity either. Considering the log DSr and Δ44/40Cacalcite-aq relationship, Sr/Ca and δ44/40Cacalcite values of precipitated calcite can be used as an excellent multi-proxy approach to reconstruct environmental conditions (e.g., temperature, precipitation rate) of calcite growth and diagenetic alteration. PMID:22347722

  10. Estimation Model for Electrical Conductivity of CaF2-CaO-Al2O3 Slags

    NASA Astrophysics Data System (ADS)

    Shi, Guan-yong; Zhang, Ting-an; Dou, Zhi-he; Niu, Li-ping

    2016-09-01

    Electrical conductivity is one of the most important properties of molten slags. It has an important influence on process parameter selection of the electroslag remelting process. In the present work, a new model for estimating electrical conductivity of high-temperature slags has been proposed via calculating the conductivity by electrical conductivity of pure substances and interaction parameters between the different components in the slag has been proposed. In this model, the Arrhenius law is used to describe the relationship between electrical conductivity and temperature of slags. This model has been successfully applied to the CaF2-Al2O3, CaF2-CaO, and CaO-Al2O3, as well as CaF2-CaO-Al2O3 systems, and the calculated results are in good agreement with the measured values.

  11. Silver ions trigger Ca2+ release by interaction with the (Ca2+-Mg2+)-ATPase in reconstituted systems.

    PubMed

    Gould, G W; Colyer, J; East, J M; Lee, A G

    1987-06-01

    It has been suggested that vesicles derived from the sarcoplasmic reticulum of skeletal muscle contain Ca2+ channels which can be opened by interaction with sulfhydryl reagents such as Ag+ or Hg2+. We show that, in reconstituted vesicles containing the (Ca2+-Mg2+)-ATPase purified from sarcoplasmic reticulum as the only protein, the ATPase can act as a pathway for Ca2+ efflux and that Ag+ induces a rapid release of Ca2+ from such reconstituted vesicles. We also show that Ag+ has a marked inhibitory effect on the ATPase activity of the purified ATPase. We suggest that the (Ca2+-Mg2+)-ATPase can act as a pathway for rapid Ca2+ release from sarcoplasmic reticulum.

  12. Nonspatial Sequence Coding in CA1 Neurons

    PubMed Central

    Allen, Timothy A.; Salz, Daniel M.; McKenzie, Sam

    2016-01-01

    The hippocampus is critical to the memory for sequences of events, a defining feature of episodic memory. However, the fundamental neuronal mechanisms underlying this capacity remain elusive. While considerable research indicates hippocampal neurons can represent sequences of locations, direct evidence of coding for the memory of sequential relationships among nonspatial events remains lacking. To address this important issue, we recorded neural activity in CA1 as rats performed a hippocampus-dependent sequence-memory task. Briefly, the task involves the presentation of repeated sequences of odors at a single port and requires rats to identify each item as “in sequence” or “out of sequence”. We report that, while the animals' location and behavior remained constant, hippocampal activity differed depending on the temporal context of items—in this case, whether they were presented in or out of sequence. Some neurons showed this effect across items or sequence positions (general sequence cells), while others exhibited selectivity for specific conjunctions of item and sequence position information (conjunctive sequence cells) or for specific probe types (probe-specific sequence cells). We also found that the temporal context of individual trials could be accurately decoded from the activity of neuronal ensembles, that sequence coding at the single-cell and ensemble level was linked to sequence memory performance, and that slow-gamma oscillations (20–40 Hz) were more strongly modulated by temporal context and performance than theta oscillations (4–12 Hz). These findings provide compelling evidence that sequence coding extends beyond the domain of spatial trajectories and is thus a fundamental function of the hippocampus. SIGNIFICANCE STATEMENT The ability to remember the order of life events depends on the hippocampus, but the underlying neural mechanisms remain poorly understood. Here we addressed this issue by recording neural activity in hippocampal

  13. Distribution of calcium (Ca) and magnesium (Mg) in the leaves of Brassica rapa under varying exogenous Ca and Mg supply

    PubMed Central

    Rios, Juan Jose; Ó Lochlainn, Seosamh; Devonshire, Jean; Graham, Neil S.; Hammond, John P.; King, Graham J.; White, Philip J.; Kurup, Smita; Broadley, Martin R.

    2012-01-01

    Background and Aims Leafy vegetable Brassica crops are an important source of dietary calcium (Ca) and magnesium (Mg) and represent potential targets for increasing leaf Ca and Mg concentrations through agronomy or breeding. Although the internal distribution of Ca and Mg within leaves affects the accumulation of these elements, such data are not available for Brassica. The aim of this study was to characterize the internal distribution of Ca and Mg in the leaves of a vegetable Brassica and to determine the effects of altered exogenous Ca and Mg supply on this distribution. Methods Brassica rapa ssp. trilocularis ‘R-o-18’ was grown at four different Ca:Mg treatments for 21 d in a controlled environment. Concentrations of Ca and Mg were determined in fully expanded leaves using inductively coupled plasma-mass spectrometry (ICP-MS). Internal distributions of Ca and Mg were determined in transverse leaf sections at the base and apex of leaves using energy-dispersive X-ray spectroscopy (EDS) with cryo-scanning electron microscopy (cryo-SEM). Key Results Leaf Ca and Mg concentrations were greatest in palisade and spongy mesophyll cells, respectively, although this was dependent on exogenous supply. Calcium accumulation in palisade mesophyll cells was enhanced slightly under high Mg supply; in contrast, Mg accumulation in spongy mesophyll cells was not affected by Ca supply. Conclusions The results are consistent with Arabidopsis thaliana and other Brassicaceae, providing phenotypic evidence that conserved mechanisms regulate leaf Ca and Mg distribution at a cellular scale. The future study of Arabidopsis gene orthologues in mutants of this reference B. rapa genotype will improve our understanding of Ca and Mg homeostasis in plants and may provide a model-to-crop translation pathway for targeted breeding. PMID:22362665

  14. Different Levels of CEA, CA153 and CA125 in Milk and Benign and Malignant Nipple Discharge

    PubMed Central

    Zhao, Song; Mei, Yu; Wang, Jianli; Zhang, Kai; Ma, Rong

    2016-01-01

    Background The aim of this study was to assess the diagnostic values of three breast tumor markers (i.e., CEA, CA153 and CA125) in milk and nipple discharge in the prediction of different breast diseases diagnoses. Methods Three hundred thirty-six patients (96 breast cancer and 240 benign disease patients) with nipple discharge and a control group of 56 healthy parturient participants were enrolled in the present study. Nipple discharge samples were preoperatively collected from the patients, and milk was collected from the colostrum of the parturient participants. The samples were assayed for the CEA, CA153 and CA125 levels. Cutoff values were determined for the detection of breast diseases using ROC curves. Results The levels of CEA, CA153 and CA125 were significantly different between the nipple discharge and the milk (all ps < 0.001). In the nipple discharge, the CEA and CA153 levels in the breast cancer group were significantly greater than those in the benign group (all ps < 0.001), and cutoff values of 263.3 ng/mL and 1235.3 U/mL, respectively, were established. However, the expression of CA125 did not differ significantly between the breast cancer and benign groups. Conclusion Differences in the apparent expression levels of CEA, CA153 and CA125 in patients with nipple discharge and healthy persons were validated. The present data suggest that CEA and CA153 might potentially be useful in the differential diagnoses of benign tumors and breast cancer. CA125 did not seem to be useful for breast cancer detection. PMID:27327081

  15. The pepper oxidoreductase CaOXR1 interacts with the transcription factor CaRAV1 and is required for salt and osmotic stress tolerance.

    PubMed

    Lee, Sung Chul; Choi, Du Seok; Hwang, In Sun; Hwang, Byung Kook

    2010-07-01

    RAV1 (Related to ABI3/VP1) proteins function as a transcription factor in signal transduction pathways in plants. The yeast-two-hybrid and in vivo coimmunoprecipitation assays identified the pepper (Capsicum annuum) oxidoreductase protein CaOXR1 that physically interacts with the pepper CaRAV1 transcription factor. The AP2 domain of CaRAV1 protein is essential for its direct interaction with CaOXR1. Both CaRAV1 and CaOXR1 proteins co-localize to the nuclei of plant cells. Virus-induced gene silencing of CaRAV1 and CaRAV1/CAOXR1 confers enhanced susceptibility to high salinity and osmotic stresses, which is accompanied by altered expression of the stress marker genes in pepper. Expression of CaAMP1 (pepper antimicrobial protein) and CaOSM1 (pepper osmotin) is suppressed by 1.2-6.6-fold in silenced leaves upon treatment with NaCl or mannitol. Overexpression of CaRAV1, CaOXR1 and CaOXR1/CaRAV1 in Arabidopsis also confers enhanced resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis infection. In addition, CaRAV1- and CaOXR1/CaRAV1-overexpression (OX) Arabidopsis plants are highly tolerant to high salinity and osmotic stress. Together, these results suggest that CaOXR1 protein positively controls CaRAV1-mediated plant defense during biotic and abiotic stresses.

  16. Regulation of airway ciliary activity by Ca2+: simultaneous measurement of beat frequency and intracellular Ca2+.

    PubMed Central

    Lansley, A B; Sanderson, M J

    1999-01-01

    Airway ciliary activity is influenced by [Ca2+]i, but this mechanism is not fully understood. To investigate this relationship, ciliary activity and [Ca2+]i were measured simultaneously from airway epithelial ciliated cells. Ciliary beat frequency was determined, for each beat cycle, with phase-contrast optics and high-speed video imaging (at 240 images s-1) and correlated with [Ca2+]i determined, at the ciliary base, by fast imaging (30 images s-1) of fura-2 fluorescence. As a mechanically induced intercellular Ca2+ wave propagated through adjacent cells, [Ca2+]i was elevated from a baseline concentration of 45 to 100 nM, to a peak level of up to 650 nM. When the Ca2+ wave reached the ciliary base, the beat frequency rapidly increased, within a few beat cycles, from a basal rate of 6.4 to 11.6 Hz at 20-23 degrees C, and from 17.2 to 26.7 Hz at 37 degrees C. Changes in [Ca2+]i, above 350 nM, had no effect on the maximum beat frequency. We suggest that airway ciliary beat frequency is 1) controlled by a low range of [Ca2+]i acting directly at an axonemal site at the ciliary base and 2) that a maximum frequency is induced by a change in [Ca2+]i of approximately 250-300 nM. PMID:10388787

  17. Effect of exchangeable cations on apparent diffusion of Ca 2+ ions in Na- and Ca-montmorillonite mixtures

    NASA Astrophysics Data System (ADS)

    Kozaki, T.; Sawaguchi, T.; Fujishima, A.; Sato, S.

    Compacted Na-bentonite, of which the major mineral is montmorillonite, is a candidate buffer material for the geological disposal of high-level radioactive waste. A potential alteration of the bentonite in a repository is the partial replacement of the exchangeable cations of Na + with Ca 2+. The Ca 2+ cations could be released from cementitious materials and diffuse into the buffer material in the repository. In this study, to evaluate the alteration that could reduce the performance of the bentonite buffer, the apparent diffusion coefficients of HTO and Ca 2+ ions were determined from non-steady, one-dimensional diffusion experiments using Na- and Ca-montmorillonite mixtures with different ionic equivalent fractions of Ca 2+ ions. The apparent diffusion coefficient of HTO at a dry density of 1.0 Mg m -3 slightly increased with an increase in the ionic equivalent fraction of Ca 2+ ions. However, the apparent diffusion coefficient of Ca 2+ and the activation energy for diffusion at the same dry density were independent of the ionic equivalent fraction of Ca 2+ ions. These findings suggest that unlike HTO, which can be postulated to diffuse mainly in pore water, Ca 2+ ion diffusion could occur predominantly in interlayer spaces, of which the basal spacing was determined to be constant by the XRD technique.

  18. Measurement of cytosolic Ca2+ in isolated contractile lymphatics.

    PubMed

    Souza-Smith, Flavia M; Kurtz, Kristine M; Breslin, Jerome W

    2011-01-01

    Lymphatic vessels comprise a multifunctional transport system that maintains fluid homeostasis, delivers lipids to the central circulation, and acts as a surveillance system for potentially harmful antigens, optimizing mucosal immunity and adaptive immune responses. Lymph is formed from interstitial fluid that enters blind-ended initial lymphatics, and then is transported against a pressure gradient in larger collecting lymphatics. Each collecting lymphatic is made up of a series of segments called lymphangions, separated by bicuspid valves that prevent backflow. Each lymphangion possesses a contractile cycle that propels lymph against a pressure gradient toward the central circulation. This phasic contractile pattern is analogous to the cardiac cycle, with systolic and diastolic phases, and with a lower contraction frequency. In addition, lymphatic smooth muscle generates tone and displays myogenic constriction and dilation in response to increases and decreases in luminal pressure, respectively. A hybrid of molecular mechanisms that support both the phasic and tonic contractility of lymphatics are thus proposed. Contraction of smooth muscle is generally regulated by the cytosolic Ca(2+) concentration ([Ca(2+)](i)) plus sensitivity to Ca(2+) of the contractile elements in response to changes in the environment surrounding the cell. [Ca(2+)](i) is determined by the combination of the movement of Ca(2+) through plasma membrane ligand or voltage gated Ca(2+) channels and the release and uptake of Ca(2+) from internal stores. Cytosolic Ca(2+) binds to calmodulin and activates enzymes such as myosin light chain (MLC) kinase (MLCK), which in turn phosphorylates MLC leading to actin-myosin-mediated contraction. However, the sensitivity of this pathway to Ca(2+) can be regulated by the MLC phosphatase (MLCP). MLCP activity is regulated by Rho kinase (ROCK) and the myosin phosphatase inhibitor protein CPI-17. Here, we present a method to evaluate changes in [Ca(2+)](i

  19. Ca2+-activated Cl− current in rabbit sinoatrial node cells

    PubMed Central

    Verkerk, Arie O; Wilders, Ronald; Zegers, Jan G; van Borren, Marcel M G J; Ravesloot, Jan H; Verheijck, E Etienne

    2002-01-01

    The Ca2+-activated Cl− current (ICl(Ca)) has been identified in atrial, Purkinje and ventricular cells, where it plays a substantial role in phase-1 repolarization and delayed after-depolarizations. In sinoatrial (SA) node cells, however, the presence and functional role of ICl(Ca) is unknown. In the present study we address this issue using perforated patch-clamp methodology and computer simulations. Single SA node cells were enzymatically isolated from rabbit hearts. ICl(Ca) was measured, using the perforated patch-clamp technique, as the current sensitive to the anion blocker 4,4′-diisothiocyanostilbene-2,2′-disulphonic acid (DIDS). Voltage clamp experiments demonstrate the presence of ICl(Ca) in one third of the spontaneously active SA node cells. The current was transient outward with a bell-shaped current-voltage relationship. Adrenoceptor stimulation with 1 μm noradrenaline doubled the ICl(Ca) density. Action potential clamp measurements demonstrate that ICl(Ca) is activate late during the action potential upstroke. Current clamp experiments show, both in the absence and presence of 1 μm noradrenaline, that blockade of ICl(Ca) increases the action potential overshoot and duration, measured at 20 % repolarization. However, intrinsic interbeat interval, upstroke velocity, diastolic depolarization rate and the action potential duration measured at 50 and 90 % repolarization were not affected. Our experimental data are supported by computer simulations, which additionally demonstrate that ICl(Ca) has a limited role in pacemaker synchronization or action potential conduction. In conclusion, ICl(Ca) is present in one third of SA node cells and is activated during the pacemaker cycle. However, ICl(Ca) does not modulate intrinsic interbeat interval, pacemaker synchronization or action potential conduction. PMID:11927673

  20. {sup 48}Ca HETEROGENEITY IN DIFFERENTIATED METEORITES

    SciTech Connect

    Chen, Hsin-Wei; Lee, Typhoon; Lee, Der-Chuen; Shen, Jason Jiun-San; Chen, Jiang-Chang

    2011-12-10

    Isotopic heterogeneities of {sup 48}Ca have been found in numerous bulk meteorites that are correlated with {sup 50}Ti and {sup 54}Cr anomalies among differentiated planetary bodies, and the results suggest that a rare subset of neutron-rich Type Ia supernova (nSN Ia) was responsible for contributing these neutron-rich iron-group isotopes into the solar system (SS). The heterogeneity of these isotopes found in differentiated meteorites indicates that the isotopic compositions of the bulk SS are not uniform, and there are significant amounts of nSNe Ia dust incompletely mixed with the rest of SS materials during planetary formation. Combined with the data of now-extinct short-lived nuclide {sup 60}Fe, which can be produced more efficiently from an nSN Ia than a Type II supernova ejecta, the observed planetary-scale isotopic heterogeneity probably reflects a late input of stellar dust grains with neutron-rich nuclear statistical equilibrium nuclides into the early SS.

  1. RESEM-CA: Validation and testing

    SciTech Connect

    Pal, Vineeta; Carroll, William L.; Bourassa, Norman

    2002-09-01

    This report documents the results of an extended comparison of RESEM-CA energy and economic performance predictions with the recognized benchmark tool DOE2.1E to determine the validity and effectiveness of this tool for retrofit design and analysis. The analysis was a two part comparison of patterns of (1) monthly and annual energy consumption of a simple base-case building and controlled variations in it to explore the predictions of load components of each program, and (2) a simplified life-cycle cost analysis of the predicted effects of selected Energy Conservation Measures (ECMs). The study tries to analyze and/or explain the differences that were observed. On the whole, this validation study indicates that RESEM is a promising tool for retrofit analysis. As a result of this study some factors (incident solar radiation, outside air film coefficient, IR radiation) have been identified where there is a possibility of algorithmic improvements. These would have to be made in a way that does not sacrifice the speed of the tool, necessary for extensive parametric search of optimum ECM measures.

  2. Towards ultracold RbCa molecules

    NASA Astrophysics Data System (ADS)

    Kleinert, Michaela

    2011-10-01

    Ultracold heteronuclear molecules have received much attention lately because of their potential applications in high-precision spectroscopy, studies of fundamental symmetries and quantum information processing. So far the focus has been on alkaline/alkaline dimers since their constituent atoms have been studied extensively. Recently, several groups have begun work on more challenging alkaline/alkaline-earth or alkaline/rare-earth combinations. In addition to a permanent electric dipole moment, which makes the alkaline/alkaline dimers such an intriguing system, alkaline/alkaline-earth molecules also possess a permanent magnetic dipole moment, thus allowing the manipulation with electric and magnetic fields. In addition, the molecular ground state of an alkaline/alkaline-earth dimer has a non-vanishing spin. Interesting collision dynamics, for example the suppression of collisions in carefully tailored external fields, have been predicted. At Willamette University, we will trap ultracold gases of rubidium and calcium together to form the molecular dimer RbCa via photoassociation of the constituent atoms. In this talk we will discuss the current state of the experiment and our future plans.[4pt] In collaboration with Hayley Whitson, Garrett Potter, and Kristen Norton, Willamette University.

  3. Seawater nutrient and carbonate ion concentrations recorded as P/Ca, Ba/Ca, and U/Ca in the deep-sea coral Desmophyllum dianthus

    NASA Astrophysics Data System (ADS)

    Anagnostou, Eleni; Sherrell, Robert M.; Gagnon, Alex; LaVigne, Michele; Field, M. Paul; McDonough, William F.

    2011-05-01

    As paleoceanographic archives, deep sea coral skeletons offer the potential for high temporal resolution and precise absolute dating, but have not been fully investigated for geochemical reconstructions of past ocean conditions. Here we assess the utility of skeletal P/Ca, Ba/Ca and U/Ca in the deep sea coral D. dianthus as proxies of dissolved phosphate (remineralized at shallow depths), dissolved barium (trace element with silicate-type distribution) and carbonate ion concentrations, respectively. Measurements of these proxies in globally distributed D. dianthus specimens show clear dependence on corresponding seawater properties. Linear regression fits of mean coral Element/Ca ratios against seawater properties yield the equations: P/Ca coral (μmol/mol) = (0.6 ± 0.1) P/Ca sw(μmol/mol) - (23 ± 18), R2 = 0.6, n = 16 and Ba/Ca coral(μmol/mol) = (1.4 ± 0.3) Ba/Ca sw(μmol/mol) + (0 ± 2), R2 = 0.6, n = 17; no significant relationship is observed between the residuals of each regression and seawater temperature, salinity, pressure, pH or carbonate ion concentrations, suggesting that these variables were not significant secondary dependencies of these proxies. Four D. dianthus specimens growing at locations with Ωarag ⩽ 0.6 displayed markedly depleted P/Ca compared to the regression based on the remaining samples, a behavior attributed to an undersaturation effect. These corals were excluded from the calibration. Coral U/Ca correlates with seawater carbonate ion: U/Ca coral(μmol/mol) = (-0.016 ± 0.003) [CO32-] (μmol/kg) + (3.2 ± 0.3), R2 = 0.6, n = 17. The residuals of the U/Ca calibration are not significantly related to temperature, salinity, or pressure. Scatter about the linear calibration lines is attributed to imperfect spatial-temporal matches between the selected globally distributed specimens and available water column chemical data, and potentially to unresolved additional effects. The uncertainties of these initial proxy calibration regressions

  4. Hierarchic stochastic modelling applied to intracellular Ca(2+) signals.

    PubMed

    Moenke, Gregor; Falcke, Martin; Thurley, Keven

    2012-01-01

    Important biological processes like cell signalling and gene expression have noisy components and are very complex at the same time. Mathematical analysis of such systems has often been limited to the study of isolated subsystems, or approximations are used that are difficult to justify. Here we extend a recently published method (Thurley and Falcke, PNAS 2011) which is formulated in observable system configurations instead of molecular transitions. This reduces the number of system states by several orders of magnitude and avoids fitting of kinetic parameters. The method is applied to Ca(2+) signalling. Ca(2+) is a ubiquitous second messenger transmitting information by stochastic sequences of concentration spikes, which arise by coupling of subcellular Ca(2+) release events (puffs). We derive analytical expressions for a mechanistic Ca(2+) model, based on recent data from live cell imaging, and calculate Ca(2+) spike statistics in dependence on cellular parameters like stimulus strength or number of Ca(2+) channels. The new approach substantiates a generic Ca(2+) model, which is a very convenient way to simulate Ca(2+) spike sequences with correct spiking statistics.

  5. Intracellular Ca-carbonate biomineralization is widespread in cyanobacteria

    PubMed Central

    Benzerara, Karim; Skouri-Panet, Feriel; Li, Jinhua; Férard, Céline; Gugger, Muriel; Laurent, Thierry; Couradeau, Estelle; Ragon, Marie; Cosmidis, Julie; Menguy, Nicolas; Margaret-Oliver, Isabel; Tavera, Rosaluz; López-García, Purificación; Moreira, David

    2014-01-01

    Cyanobacteria have played a significant role in the formation of past and modern carbonate deposits at the surface of the Earth using a biomineralization process that has been almost systematically considered induced and extracellular. Recently, a deep-branching cyanobacterial species, Candidatus Gloeomargarita lithophora, was reported to form intracellular amorphous Ca-rich carbonates. However, the significance and diversity of the cyanobacteria in which intracellular biomineralization occurs remain unknown. Here, we searched for intracellular Ca-carbonate inclusions in 68 cyanobacterial strains distributed throughout the phylogenetic tree of cyanobacteria. We discovered that diverse unicellular cyanobacterial taxa form intracellular amorphous Ca-carbonates with at least two different distribution patterns, suggesting the existence of at least two distinct mechanisms of biomineralization: (i) one with Ca-carbonate inclusions scattered within the cell cytoplasm such as in Ca. G. lithophora, and (ii) another one observed in strains belonging to the Thermosynechococcus elongatus BP-1 lineage, in which Ca-carbonate inclusions lie at the cell poles. This pattern seems to be linked with the nucleation of the inclusions at the septum of the cells, showing an intricate and original connection between cell division and biomineralization. These findings indicate that intracellular Ca-carbonate biomineralization by cyanobacteria has been overlooked by past studies and open new perspectives on the mechanisms and the evolutionary history of intra- and extracellular Ca-carbonate biomineralization by cyanobacteria. PMID:25009182

  6. Intracellular Ca-carbonate biomineralization is widespread in cyanobacteria

    NASA Astrophysics Data System (ADS)

    Benzerara, Karim; Skouri-Panet, Feriel; Li, Jinhua; Férard, Céline; Gugger, Muriel; Laurent, Thierry; Couradeau, Estelle; Ragon, Marie; Cosmidis, Julie; Menguy, Nicolas; Margaret-Oliver, Isabel; Tavera, Rosaluz; López-García, Purificación; Moreira, David

    2014-07-01

    Cyanobacteria have played a significant role in the formation of past and modern carbonate deposits at the surface of the Earth using a biomineralization process that has been almost systematically considered induced and extracellular. Recently, a deep-branching cyanobacterial species, Candidatus Gloeomargarita lithophora, was reported to form intracellular amorphous Ca-rich carbonates. However, the significance and diversity of the cyanobacteria in which intracellular biomineralization occurs remain unknown. Here, we searched for intracellular Ca-carbonate inclusions in 68 cyanobacterial strains distributed throughout the phylogenetic tree of cyanobacteria. We discovered that diverse unicellular cyanobacterial taxa form intracellular amorphous Ca-carbonates with at least two different distribution patterns, suggesting the existence of at least two distinct mechanisms of biomineralization: (i) one with Ca-carbonate inclusions scattered within the cell cytoplasm such as in Ca. G. lithophora, and (ii) another one observed in strains belonging to the Thermosynechococcus elongatus BP-1 lineage, in which Ca-carbonate inclusions lie at the cell poles. This pattern seems to be linked with the nucleation of the inclusions at the septum of the cells, showing an intricate and original connection between cell division and biomineralization. These findings indicate that intracellular Ca-carbonate biomineralization by cyanobacteria has been overlooked by past studies and open new perspectives on the mechanisms and the evolutionary history of intra- and extracellular Ca-carbonate biomineralization by cyanobacteria.

  7. 33 CFR 80.1134 - Monterey Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Monterey Harbor, CA. 80.1134 Section 80.1134 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1134 Monterey Harbor, CA. A line drawn from Monterey Harbor Light 6 to the...

  8. Credit USAF, ca. 1943. Original housed in the Photograph Files, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit USAF, ca. 1943. Original housed in the Photograph Files, AFFTC/HO, Edwards AFB, California. Historic view of finished swimming pool, with fence and lifeguard station. View looks west - Edwards Air Force Base, North Base, Swimming Pool, Second Street, Boron, Kern County, CA

  9. 33 CFR 80.1120 - Port Hueneme, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Port Hueneme, CA. 80.1120 Section... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1120 Port Hueneme, CA. (a) A line drawn from Port Hueneme East Jetty Light 4 to Port Hueneme West Jetty Light 3....

  10. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Marina Del Rey, CA. 80.1118... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del...

  11. 33 CFR 80.1124 - Ventura Marina, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Ventura Marina, CA. 80.1124... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1124 Ventura Marina, CA. A line drawn from Ventura Marina South Jetty Light 6 to Ventura Marina Breakwater South Light 3; thence to Ventura...

  12. Intracellular Ca-carbonate biomineralization is widespread in cyanobacteria.

    PubMed

    Benzerara, Karim; Skouri-Panet, Feriel; Li, Jinhua; Férard, Céline; Gugger, Muriel; Laurent, Thierry; Couradeau, Estelle; Ragon, Marie; Cosmidis, Julie; Menguy, Nicolas; Margaret-Oliver, Isabel; Tavera, Rosaluz; López-García, Purificación; Moreira, David

    2014-07-29

    Cyanobacteria have played a significant role in the formation of past and modern carbonate deposits at the surface of the Earth using a biomineralization process that has been almost systematically considered induced and extracellular. Recently, a deep-branching cyanobacterial species, Candidatus Gloeomargarita lithophora, was reported to form intracellular amorphous Ca-rich carbonates. However, the significance and diversity of the cyanobacteria in which intracellular biomineralization occurs remain unknown. Here, we searched for intracellular Ca-carbonate inclusions in 68 cyanobacterial strains distributed throughout the phylogenetic tree of cyanobacteria. We discovered that diverse unicellular cyanobacterial taxa form intracellular amorphous Ca-carbonates with at least two different distribution patterns, suggesting the existence of at least two distinct mechanisms of biomineralization: (i) one with Ca-carbonate inclusions scattered within the cell cytoplasm such as in Ca. G. lithophora, and (ii) another one observed in strains belonging to the Thermosynechococcus elongatus BP-1 lineage, in which Ca-carbonate inclusions lie at the cell poles. This pattern seems to be linked with the nucleation of the inclusions at the septum of the cells, showing an intricate and original connection between cell division and biomineralization. These findings indicate that intracellular Ca-carbonate biomineralization by cyanobacteria has been overlooked by past studies and open new perspectives on the mechanisms and the evolutionary history of intra- and extracellular Ca-carbonate biomineralization by cyanobacteria.

  13. CA Condensates as a Retrospective Search Tool. A Commentary

    ERIC Educational Resources Information Center

    Hansen, Inge Berg

    1973-01-01

    A retrospective test search on one year of CA Condensates was carried out in order to calculate the costs per profile and to get an impression of how CA Condensates would suffice as a database for retrospective use. (11 references) (Author)

  14. 72. MISSISSIPPI, MONROE CO. MAP OF MONROE COUNTY, ca. 1925 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    72. MISSISSIPPI, MONROE CO. MAP OF MONROE COUNTY, ca. 1925 Broad side of map of Monroe Co., 'Compliments of Home Mortgage & Realty Co., Amory, Miss.' Orig. scale: ca. 1 in. to 2 mi. No date. Property of Helen (Mrs. Sam L.) Crawford, Hamilton, Ms. Sarcone Photography, Columbus, Ms., Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  15. 68. MISSISSIPPI, LOWNDES CO. COLUMBUS MAP OF COLUMBUS ca. 1875 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    68. MISSISSIPPI, LOWNDES CO. COLUMBUS MAP OF COLUMBUS ca. 1875 BIRD'S EYE VIEW OF COLUMBUS MISSISSIPPI by Camille Drie ca. 1875. Copy of snapshot in Lowndes Co. Public Library, Columbus, Ms. Snow status in early 1870s: includes M&O RR bridge, but no highway bridge. Sarcone Photography, Columbus, Ms., Sept 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  16. 33 CFR 80.1138 - Santa Cruz Harbor, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Santa Cruz Harbor, CA. 80.1138... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1138 Santa Cruz Harbor, CA. A line drawn from the seaward extremity of the Santa Cruz Harbor East Breakwater to Santa Cruz Harbor West...

  17. 33 CFR 80.1138 - Santa Cruz Harbor, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Santa Cruz Harbor, CA. 80.1138... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1138 Santa Cruz Harbor, CA. A line drawn from the seaward extremity of the Santa Cruz Harbor East Breakwater to Santa Cruz Harbor West...

  18. 33 CFR 80.1138 - Santa Cruz Harbor, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Santa Cruz Harbor, CA. 80.1138... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1138 Santa Cruz Harbor, CA. A line drawn from the seaward extremity of the Santa Cruz Harbor East Breakwater to Santa Cruz Harbor West...

  19. 33 CFR 80.1138 - Santa Cruz Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Santa Cruz Harbor, CA. 80.1138... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1138 Santa Cruz Harbor, CA. A line drawn from the seaward extremity of the Santa Cruz Harbor East Breakwater to Santa Cruz Harbor West...

  20. 73. MISSISSIPPI, MONROE CO. MAP OF MONROE CO., ca. 1925 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    73. MISSISSIPPI, MONROE CO. MAP OF MONROE CO., ca. 1925 Broadside map of Monroe Co., published by the Examiner Printing Co., Aberdeen, Ms. Original scale: ca. 1 in. to 2 mi. No date. Property of Helen (Mrs. Sam L.) Crawford, Hamilton, Ms. Sarcone Photograpy, Columbus, Ms., Sep 1978. - Bridges of the Upper Tombigbee River Valley, Columbus, Lowndes County, MS

  1. PVP-CA composite preparation and its characteristics

    NASA Astrophysics Data System (ADS)

    Cui, Ruiyao

    Polyvinylpyrrolidone (PVP) is a commonly used polymer that has some excellent properties, such as great strength and biocompatibility. Cellulose Acetate (CA) is another excellent polymer that has been employed in many applications, including drug. PVP-CA composite has both strength and flexible properties that can be used as ultrafiltration membranes or the drug release system. PVP-CA composites comprise a new class of materials that have been the scope of this work. In this research, the electrospun PVP-CA composites were prepared under different concentrations. Then, the impact of different electrospinning parameters on fiber diameters was investigated. Moreover, acetic acid and acetone were used as solvents for dissolving PVP, CA respectively. For comparison, PVP in water and CA in acetone was each deposited on the aluminum foil by electrospinning, forming a two-layer structure. Scanning electron microscopy(SEM) and Raman spectroscopy test were carried out. From the test results, fibers with 200nm to 1um diameter were prepared and the interaction between PVP and CA were proved. Then the oil absorption testing was carried out. The membrane structure of the electrospun composite fibers showed good oil absorption capacity, that was twice higher than the 2-layer PVP-CA fibers.

  2. 33 CFR 80.1102 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Santa Catalina Island, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1102 Santa Catalina Island, CA. The 72 COLREGS shall apply to the harbors on Santa Catalina Island....

  3. 33 CFR 80.1122 - Channel Islands Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Channel Islands Harbor, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1122 Channel Islands Harbor, CA. (a) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor...

  4. 46 CFR 7.115 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Santa Catalina Island, CA. 7.115 Section 7.115 Shipping... Coast § 7.115 Santa Catalina Island, CA. (a) A line drawn from the northernmost point of Lion Head to the north tangent of Bird Rock Island; thence to the northernmost point of Blue Cavern Point. (b)...

  5. 33 CFR 80.1102 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Santa Catalina Island, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1102 Santa Catalina Island, CA. The 72 COLREGS shall apply to the harbors on Santa Catalina Island....

  6. 33 CFR 80.1102 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Santa Catalina Island, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1102 Santa Catalina Island, CA. The 72 COLREGS shall apply to the harbors on Santa Catalina Island....

  7. 46 CFR 7.115 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Santa Catalina Island, CA. 7.115 Section 7.115 Shipping... Coast § 7.115 Santa Catalina Island, CA. (a) A line drawn from the northernmost point of Lion Head to the north tangent of Bird Rock Island; thence to the northernmost point of Blue Cavern Point. (b)...

  8. 46 CFR 7.115 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Santa Catalina Island, CA. 7.115 Section 7.115 Shipping... Coast § 7.115 Santa Catalina Island, CA. (a) A line drawn from the northernmost point of Lion Head to the north tangent of Bird Rock Island; thence to the northernmost point of Blue Cavern Point. (b)...

  9. 33 CFR 80.1102 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Santa Catalina Island, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1102 Santa Catalina Island, CA. The 72 COLREGS shall apply to the harbors on Santa Catalina Island....

  10. 46 CFR 7.115 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Santa Catalina Island, CA. 7.115 Section 7.115 Shipping... Coast § 7.115 Santa Catalina Island, CA. (a) A line drawn from the northernmost point of Lion Head to the north tangent of Bird Rock Island; thence to the northernmost point of Blue Cavern Point. (b)...

  11. 33 CFR 80.1122 - Channel Islands Harbor, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Channel Islands Harbor, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1122 Channel Islands Harbor, CA. (a) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor...

  12. 33 CFR 80.1122 - Channel Islands Harbor, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Channel Islands Harbor, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1122 Channel Islands Harbor, CA. (a) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor...

  13. 33 CFR 80.1102 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Santa Catalina Island, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1102 Santa Catalina Island, CA. The 72 COLREGS shall apply to the harbors on Santa Catalina Island....

  14. 33 CFR 80.1122 - Channel Islands Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Channel Islands Harbor, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1122 Channel Islands Harbor, CA. (a) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor...

  15. 46 CFR 7.115 - Santa Catalina Island, CA.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Santa Catalina Island, CA. 7.115 Section 7.115 Shipping... Coast § 7.115 Santa Catalina Island, CA. (a) A line drawn from the northernmost point of Lion Head to the north tangent of Bird Rock Island; thence to the northernmost point of Blue Cavern Point. (b)...

  16. 33 CFR 80.1122 - Channel Islands Harbor, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Channel Islands Harbor, CA. 80... INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1122 Channel Islands Harbor, CA. (a) A line drawn from Channel Islands Harbor South Jetty Light 2 to Channel Islands Harbor...

  17. Synthesis and characterisation of copper doped Ca-Li hydroxyapatite

    NASA Astrophysics Data System (ADS)

    Pogosova, M. A.; Kazin, P. E.; Tretyakov, Y. D.

    2012-08-01

    Hydroxyapapites M10(PO4)6(OH)2 (MHAP), where M is an alkaline earth metal, colored by incorporation of copper ions substituting protons, were discovered recently [1]. Now this kind of apatite-type materials can be used as inorganic pigments. Until now blue (BaHAP), violet (SrHAP) and wine-red (CaHAP) colors were achieved by the copper ions introduction [2]. The task of the present work was to study possibility of further M-ion substitution to affect the color and shift it toward the red-orange tint. Polycrystalline hydroxyapatites Ca10-xLix+yCuz(PO4)6O2H2-y-z-σ (Ca-LiHAP) were synthesized by solid state reaction at 1150 °C (ceramic method) and studied by X-ray powder diffraction (XRD), infrared absorption and diffuse-reflectance spectroscopy. Refinement of the X-ray diffraction patterns by the Rietveld method shows that CaHAP unit cell parameters are a little bigger, than Ca-LiHAP ones. Small difference between unit cell parameters could be caused by two ways of the Li+ ions introduction: (1) at the Ca2+ sites (Ca-Li substitution); (2) into hexagonal channels (H-Li substitution). The Li ions doping changes the color of the copper doped CaHAP from wine-red to pink and red.

  18. 10. "TEST STAND 15, AIR FORCE FLIGHT TEST CENTER." ca. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. "TEST STAND 1-5, AIR FORCE FLIGHT TEST CENTER." ca. 1958. Test Area 1-115. Original is a color print, showing Test Stand 1-5 from below, also showing the superstructure of TS1-4 at left. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Leuhman Ridge near Highways 58 & 395, Boron, Kern County, CA

  19. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Marina Del Rey, CA. 80.1118... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del...

  20. 33 CFR 80.1124 - Ventura Marina, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Ventura Marina, CA. 80.1124... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1124 Ventura Marina, CA. A line drawn from Ventura Marina South Jetty Light 6 to Ventura Marina Breakwater South Light 3; thence to Ventura...

  1. 33 CFR 80.1124 - Ventura Marina, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Ventura Marina, CA. 80.1124... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1124 Ventura Marina, CA. A line drawn from Ventura Marina South Jetty Light 6 to Ventura Marina Breakwater South Light 3; thence to Ventura...

  2. 33 CFR 80.1124 - Ventura Marina, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Ventura Marina, CA. 80.1124... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1124 Ventura Marina, CA. A line drawn from Ventura Marina South Jetty Light 6 to Ventura Marina Breakwater South Light 3; thence to Ventura...

  3. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Marina Del Rey, CA. 80.1118... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del...

  4. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Marina Del Rey, CA. 80.1118... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light 1 to Marina Del Rey Light 4. (b) A line drawn from Marina Del...

  5. 33 CFR 80.1136 - Moss Landing Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Moss Landing Harbor, CA. 80.1136... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1136 Moss Landing Harbor, CA. A line drawn from the seaward extremity of the pier located 0.3 mile south of Moss Landing Harbor Entrance to...

  6. 33 CFR 80.1136 - Moss Landing Harbor, CA.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Moss Landing Harbor, CA. 80.1136... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1136 Moss Landing Harbor, CA. A line drawn from the seaward extremity of the pier located 0.3 mile south of Moss Landing Harbor Entrance to...

  7. 33 CFR 80.1136 - Moss Landing Harbor, CA.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Moss Landing Harbor, CA. 80.1136... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1136 Moss Landing Harbor, CA. A line drawn from the seaward extremity of the pier located 0.3 mile south of Moss Landing Harbor Entrance to...

  8. 33 CFR 80.1136 - Moss Landing Harbor, CA.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Moss Landing Harbor, CA. 80.1136... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1136 Moss Landing Harbor, CA. A line drawn from the seaward extremity of the pier located 0.3 mile south of Moss Landing Harbor Entrance to...

  9. 33 CFR 80.1136 - Moss Landing Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Moss Landing Harbor, CA. 80.1136... NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1136 Moss Landing Harbor, CA. A line drawn from the seaward extremity of the pier located 0.3 mile south of Moss Landing Harbor Entrance to...

  10. SNL/CA Environmental Management System Program Manual.

    SciTech Connect

    Larsen, Barbara L.

    2005-09-01

    The Sandia National Laboratories, California (SNL/CA) Environmental Management System (EMS) Program Manual documents the elements of the site EMS Program. The SNL/CA EMS Program was developed in accordance with Department of Energy (DOE) Order 450.1 and incorporates the elements of the International Standard on Environmental Management Systems, ISO 14001.

  11. Diffusive transport through compacted Na- and Ca-bentonite

    NASA Astrophysics Data System (ADS)

    Choi, J.-W.; Oscarson, D. W.

    1996-04-01

    The effect of exchangeable cation — Na + and Ca 2+ — on the diffusive transport of I -, Sr 2+ and 3H (as HTO) in compacted bentonite was examined using a through-diffusion method. Total intrinsic diffusion coefficients, Di, were determined from the steady-state flux of the diffusants through the clays, and apparent diffusion coefficients, Da, were obtained from the time lag technique. The clays were compacted to a dry bulk density of 1.3 Mg/m 3, and Na-bentonite was saturated with a solution of 100 mol NaCl/m3 and Ca-bentonite with one of 50 mol CaCl 2/m 3. The Di values for all diffusants are 2 to 6 times higher in the Ca- than Na-clay. We attribute this to the larger quasicrystal, or particle, size of Ca- compared to Na-bentonite. Hence, Ca-bentonite has a greater proportion of relatively large pores; this was confirmed by Hg intrusion porosimetry. This means the diffusion pathways in Ca-bentonite are less tortuous than those in Na-bentonite. Moreover, in some cases the effective porosity, or the porosity available for diffusive transport, may be greater in Ca-bentonite. The D a values are inversely proportional to the distribution coefficients of the diffusants with the clays.

  12. 33 CFR 80.1108 - Oceanside Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Oceanside Harbor, CA. 80.1108 Section 80.1108 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1108 Oceanside Harbor, CA. A line drawn from Oceanside South Jetty Light 4...

  13. 33 CFR 80.1120 - Port Hueneme, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Port Hueneme, CA. 80.1120 Section 80.1120 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1120 Port Hueneme, CA. (a) A line drawn from Port Hueneme East Jetty Light 4 to...

  14. 33 CFR 80.1134 - Monterey Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Monterey Harbor, CA. 80.1134 Section 80.1134 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1134 Monterey Harbor, CA. A line drawn from Monterey Harbor Light 6 to the...

  15. 33 CFR 80.1126 - Santa Barbara Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Santa Barbara Harbor, CA. 80.1126 Section 80.1126 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1126 Santa Barbara Harbor, CA. A line drawn from Santa Barbara Harbor Light 4...

  16. 33 CFR 80.1150 - Arcata-Humboldt Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Arcata-Humboldt Bay, CA. 80.1150 Section 80.1150 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1150 Arcata-Humboldt Bay, CA. A line drawn from Humboldt Bay Entrance Light 4...

  17. 33 CFR 80.1116 - Redondo Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Redondo Harbor, CA. 80.1116 Section 80.1116 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1116 Redondo Harbor, CA. A line drawn from Redondo Beach East Jetty Light 2 to...

  18. 33 CFR 80.1106 - Mission Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Mission Bay, CA. 80.1106 Section 80.1106 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1106 Mission Bay, CA. A line drawn from Mission Bay South Jetty Light 2 to Mission...

  19. 33 CFR 80.1132 - Estero-Morro Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Estero-Morro Bay, CA. 80.1132 Section 80.1132 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1132 Estero-Morro Bay, CA. A line drawn from the seaward extremity of the Morro...

  20. 33 CFR 80.1146 - Albion River, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Albion River, CA. 80.1146 Section 80.1146 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1146 Albion River, CA. A line drawn on an axis of 030° true through Albion River Light...

  1. 33 CFR 80.1152 - Crescent City Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Crescent City Harbor, CA. 80.1152 Section 80.1152 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1152 Crescent City Harbor, CA. A line drawn from Crescent City Entrance Light...

  2. 33 CFR 80.1140 - Pillar Point Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Pillar Point Harbor, CA. 80.1140 Section 80.1140 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1140 Pillar Point Harbor, CA. A line drawn from Pillar Point Harbor Light 6...

  3. 33 CFR 80.1148 - Noyo River, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Noyo River, CA. 80.1148 Section 80.1148 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1148 Noyo River, CA. A line drawn from Noyo River Entrance Daybeacon 4 to Noyo...

  4. 33 CFR 80.1112 - Newport Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Newport Bay, CA. 80.1112 Section 80.1112 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1112 Newport Bay, CA. A line drawn from Newport Bay East Jetty Light 4 to Newport...

  5. 33 CFR 80.1118 - Marina Del Rey, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Marina Del Rey, CA. 80.1118 Section 80.1118 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1118 Marina Del Rey, CA. (a) A line drawn from Marina Del Rey Breakwater South Light...

  6. 33 CFR 80.1110 - Dana Point Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Dana Point Harbor, CA. 80.1110 Section 80.1110 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1110 Dana Point Harbor, CA. A line drawn from Dana Point Jetty Light 6 to...

  7. 33 CFR 80.1144 - Bodega and Tomales Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bodega and Tomales Bay, CA. 80.1144 Section 80.1144 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1144 Bodega and Tomales Bay, CA. (a) An east-west line drawn from Sand...

  8. 33 CFR 80.1138 - Santa Cruz Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Santa Cruz Harbor, CA. 80.1138 Section 80.1138 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1138 Santa Cruz Harbor, CA. A line drawn from the seaward extremity of the...

  9. 33 CFR 80.1124 - Ventura Marina, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Ventura Marina, CA. 80.1124 Section 80.1124 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1124 Ventura Marina, CA. A line drawn from Ventura Marina South Jetty Light 6...

  10. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  11. 33 CFR 80.1104 - San Diego Harbor, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Diego Harbor, CA. 80.1104 Section 80.1104 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1104 San Diego Harbor, CA. A line drawn...

  12. 33 CFR 80.1104 - San Diego Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Diego Harbor, CA. 80.1104 Section 80.1104 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1104 San Diego Harbor, CA. A line drawn...

  13. 33 CFR 80.1130 - San Luis Obispo Bay, CA.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false San Luis Obispo Bay, CA. 80.1130 Section 80.1130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1130 San Luis Obispo Bay, CA. A line drawn...

  14. 33 CFR 80.1130 - San Luis Obispo Bay, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Luis Obispo Bay, CA. 80.1130 Section 80.1130 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1130 San Luis Obispo Bay, CA. A line drawn...

  15. 33 CFR 80.1142 - San Francisco Harbor, CA.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false San Francisco Harbor, CA. 80.1142 Section 80.1142 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Coast § 80.1142 San Francisco Harbor, CA. A straight...

  16. 78 FR 30267 - Humboldt County (CA) Resource Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-22

    ... received at Six Rivers National Forest Supervisor's Office, 1330 Bayshore Way, Eureka, CA. 95501. Please... Forest Service Humboldt County (CA) Resource Advisory Committee AGENCY: Forest Service, USDA. ACTION: Notice of meetings. SUMMARY: The Humboldt Resource Advisory Committee (RAC) will meet in...

  17. CA 125 in tissues and amniotic fluid during pregnancy.

    PubMed

    Quirk, J G; Brunson, G L; Long, C A; Bannon, G A; Sanders, M M; O'Brien, T J

    1988-09-01

    CA 125 was assayed in amniotic fluid and tissue extracts by immunoradiometric assay, and immunohistochemical studies were performed on paraffin-embedded sections of endometrium, decidua, and fetal membranes with the monoclonal antibody OC 125 used as primary antibody. The concentration of CA 125 in amniotic fluid changes during pregnancy so that levels of 800 to 1000 U/ml are found before 12 weeks. Thereafter, levels of 4000 to 10,000 U/ml are detected routinely. As term approaches, amniotic fluid CA 125 concentrations fall to a range of 1000 to 2000 U/ml. Levels of CA 125 in tissue extracts of secretory endometrium and decidua were 65,000 and 29,500 U/gm of tissue, respectively. CA 125 was readily detected on the apical surfaces of glandular epithelium and in the secretions of endometrial glands obtained throughout the menstrual cycle. It was also detected in the lumina of decidualized glands throughout pregnancy. No antigen was detectable within glandular epithelial cells. We have previously reported high concentrations of CA 125 in chorionic tissue extracts (42,000 U/gm) and low concentrations in amniotic tissue extracts (275 U/gm). In contrast to those findings, immunohistochemical techniques detected CA 125 within the intercellular canaliculi that surround amniotic epithelial cells but not in chorion. We conclude that the likely source of amniotic fluid CA 125 is the decidua and that it gains access to the amniotic fluid via the intercellular canalicular system that traverses the amniotic epithelium.

  18. Credit USAF, ca. 1945. Original housed in the Photograph Files, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Credit USAF, ca. 1945. Original housed in the Photograph Files, AFFTC/HO, Edwards AFB, California. Early view of the Control Tower (designated T-65, Building 4500) fitted out with radio antennae. Structure at base of tower was T42 (later Building 4503), Flight Operations - Edwards Air Force Base, North Base, Radio & Control Tower T-65, Northeast of A Street, Boron, Kern County, CA

  19. Store-Operated Ca2+ Release-Activated Ca2+ Channels Regulate PAR2-Activated Ca2+ Signaling and Cytokine Production in Airway Epithelial Cells.

    PubMed

    Jairaman, Amit; Yamashita, Megumi; Schleimer, Robert P; Prakriya, Murali

    2015-09-01

    The G-protein-coupled protease-activated receptor 2 (PAR2) plays an important role in the pathogenesis of various inflammatory and auto-immune disorders. In airway epithelial cells (AECs), stimulation of PAR2 by allergens and proteases triggers the release of a host of inflammatory mediators to regulate bronchomotor tone and immune cell recruitment. Activation of PAR2 turns on several cell signaling pathways of which the mobilization of cytosolic Ca(2+) is likely a critical but poorly understood event. In this study, we show that Ca(2+) release-activated Ca(2+) (CRAC) channels encoded by stromal interaction molecule 1 and Orai1 are a major route of Ca(2+) entry in primary human AECs and drive the Ca(2+) elevations seen in response to PAR2 activation. Activation of CRAC channels induces the production of several key inflammatory mediators from AECs including thymic stromal lymphopoietin, IL-6, and PGE2, in part through stimulation of gene expression via nuclear factor of activated T cells (NFAT). Furthermore, PAR2 stimulation induces the production of many key inflammatory mediators including PGE2, IL-6, IL-8, and GM-CSF in a CRAC channel-dependent manner. These findings indicate that CRAC channels are the primary mechanism for Ca(2+) influx in AECs and a vital checkpoint for the induction of PAR2-induced proinflammatory cytokines.

  20. Identification of the site on calcineurin phosphorylated by Ca sup + /CaM-dependent kinase II: Modification of the CaM-binding domain

    SciTech Connect

    Martensen, T.M.; Kincaid, R.L. ); Martin, B.M. )

    1989-11-28

    The catalytic subunit of the Ca{sup 2+}/calmodulin- (CaM) dependent phosphoprotein phosphatase calcineurin (CN) was phosphorylated by an activated form of Ca{sup 2+}/CaM-dependent protein kinase II (CaM-kinase II) incorporating approximately 1 mol of phosphoryl group/mol of catalytic subunit, in agreement with a value previously reported. Cyanogen bromide cleavage of radiolabeled CN followed by peptide fractionation using reverse-phase high-performance liquid chromatography yielded a single labeled peptide that contained a phosphoserine residue. Microsequencing of the peptide allowed both the determination of the cleavage cycle that released ({sup 32}P)phosphoserine and the identity of amino acids adjacent to it. Comparison of this sequence with the sequences of methionyl peptides deduced from the cDNA structure of CN allowed the phosphorylated serine to be uniquely identified. Interestingly, the phosphoserine exists in the sequence Met-Ala-Arg-Val-Phe-Ser(P)-Val-Leu-Arg-Glu, part of which lies within the putative CaM-binding sites. The phosphorylated serine residue was resistant to autocatalytic dephosphorylation, yet the slow rate of hydrolysis could be powerfully stimulated by effectors of CN phosphatase activity. The mechanism of dephosphorylation may be intramolecular since the initial rate was the same at phosphoCN concentrations of 2.5-250 nM.

  1. Cytoplasmic Na+-dependent modulation of mitochondrial Ca2+ via electrogenic mitochondrial Na+–Ca2+ exchange

    PubMed Central

    Kim, Bongju; Matsuoka, Satoshi

    2008-01-01

    To clarify the role of mitochondrial Na+–Ca2+ exchange (NCXmito) in regulating mitochondrial Ca2+ (Ca2+mito) concentration at intact and depolarized mitochondrial membrane potential (ΔΨmito), we measured Ca2+mito and ΔΨmito using fluorescence probes Rhod-2 and TMRE, respectively, in the permeabilized rat ventricular cells. Applying 300 nm cytoplasmic Ca2+ (Ca2+c) increased Ca2+mito and this increase was attenuated by cytoplasmic Na+ (Na+c) with an IC50 of 2.4 mm. To the contrary, when ΔΨmito was depolarized by FCCP, a mitochondrial uncoupler, Na+c enhanced the Ca2+c-induced increase in Ca2+mito with an EC50 of about 4 mm. This increase was not significantly affected by ruthenium red or cyclosporin A. The inhibition of NCXmito by CGP-37157 further increased Ca2+mito when ΔΨmito was intact, while it suppressed the Ca2+mito increase when ΔΨmito was depolarized, suggesting that ΔΨmito depolarization changed the exchange mode from forward to reverse. Furthermore, ΔΨmito depolarization significantly reduced the Ca2+mito decrease via forward mode, and augmented the Ca2+mito increase via reverse mode. When the respiratory chain was attenuated, the induction of the reverse mode of NCXmito hyperpolarized ΔΨmito, while ΔΨmito depolarized upon inducing the forward mode of NCXmito. Both changes in ΔΨmito were remarkably inhibited by CGP-37157. The above experimental data indicated that NCXmito is voltage dependent and electrogenic. This notion was supported theoretically by computer simulation studies with an NCXmito model constructed based on present and previous studies, presuming a consecutive and electrogenic Na+–Ca2+ exchange and a depolarization-induced increase in Na+ flux. It is concluded that Ca2+mito concentration is dynamically modulated by Na+c and ΔΨmito via electrogenic NCXmito. PMID:18218682

  2. Plasmalemmal Na+/Ca2+ exchanger modulates Ca2+-dependent exocytotic release of glutamate from rat cortical astrocytes

    PubMed Central

    Reyes, Reno C; Verkhratsky, Alexei; Parpura, Vladimir

    2012-01-01

    Astroglial excitability operates through increases in Ca2+cyt (cytosolic Ca2+), which can lead to glutamatergic gliotransmission. In parallel fluctuations in astrocytic Na+cyt (cytosolic Na+) control metabolic neuronal-glial signalling, most notably through stimulation of lactate production, which on release from astrocytes can be taken up and utilized by nearby neurons, a process referred to as lactate shuttle. Both gliotransmission and lactate shuttle play a role in modulation of synaptic transmission and plasticity. Consequently, we studied the role of the PMCA (plasma membrane Ca2+-ATPase), NCX (plasma membrane Na+/Ca2+ exchanger) and NKA (Na+/K+-ATPase) in complex and coordinated regulation of Ca2+cyt and Na+cyt in astrocytes at rest and upon mechanical stimulation. Our data support the notion that NKA and PMCA are the major Na+ and Ca2+ extruders in resting astrocytes. Surprisingly, the blockade of NKA or PMCA appeared less important during times of Ca2+ and Na+ cytosolic loads caused by mechanical stimulation. Unexpectedly, NCX in reverse mode appeared as a major contributor to overall Ca2+ and Na+ homoeostasis in astrocytes both at rest and when these glial cells were mechanically stimulated. In addition, NCX facilitated mechanically induced Ca2+-dependent exocytotic release of glutamate from astrocytes. These findings help better understanding of astrocyte-neuron bidirectional signalling at the tripartite synapse and/or microvasculature. We propose that NCX operating in reverse mode could be involved in fast and spatially localized Ca2+-dependent gliotransmission, that would operate in parallel to a slower and more widely distributed gliotransmission pathway that requires metabotropically controlled Ca2+ release from the ER (endoplasmic reticulum). PMID:22268447

  3. Role of Hippocampal CA2 Region in Triggering Sharp-Wave Ripples.

    PubMed

    Oliva, Azahara; Fernández-Ruiz, Antonio; Buzsáki, György; Berényi, Antal

    2016-09-21

    Sharp-wave ripples (SPW-Rs) in the hippocampus are implied in memory consolidation, as shown by observational and interventional experiments. However, the mechanism of their generation remains unclear. Using two-dimensional silicon probe arrays, we investigated the propagation of SPW-Rs across the hippocampal CA1, CA2, and CA3 subregions. Synchronous activation of CA2 ensembles preceded SPW-R-related population activity in CA3 and CA1 regions. Deep CA2 neurons gradually increased their activity prior to ripples and were suppressed during the population bursts of CA3-CA1 neurons (ramping cells). Activity of superficial CA2 cells preceded the activity surge in CA3-CA1 (phasic cells). The trigger role of the CA2 region in SPW-R was more pronounced during waking than sleeping. These results point to the CA2 region as an initiation zone for SPW-Rs. PMID:27593179

  4. Ca cofactor of the water-oxidation complex: Evidence for a Mn/Ca heteronuclear cluster

    SciTech Connect

    Cinco, Roehl M.; Robblee, John H.; Messinger, Johannes; Fernandez, Carmen; McFarlane, Karen L.; Pizarro, Shelly A.; Sauer, Ken; Yachandra, Vittal K.

    2001-07-25

    Calcium and chloride are necessary cofactors for the proper function of the oxygen-evolving complex (OEC) of Photosystem II (PS II). Located in the thylakoid membranes of green plants, cyanobacteria and algae, PS II and the OEC catalyze the light-driven oxidation of water into dioxygen (released into the biosphere), protons and electrons for carbon fixation. The actual chemistry of water oxidation is performed by a cluster of four manganese atoms, along with the requisite cofactors Ca{sup 2+} and Cl{sup -}. While the Mn complex has been extensively studied by X-ray absorption techniques, comparatively less is known about the Ca{sup 2+} cofactor. The fewer number of studies on the Ca{sup 2+} cofactor have sometimes relied on substituting the native cofactor with strontium or other metals, and have stirred some debate about the structure of the binding site. past efforts using Mn EXAFS on Sr-substituted PSII are suggestive of a close link between the Mn cluster and Sr, within 3.5 {angstrom}. The most recent published study using Sr EXAFS on similar samples confirms this finding of a 3.5 {angstrom} distance between Mn and Sr. This finding was base3d on a second Fourier peak (R {approx} 3 {angstrom}) in the Sr EXAFS from functional samples, but is absent from inactive, hydroxylamine-treated PS II. This Fourier peak II was found to fit best to two Mn at 3.5 {angstrom} rather than lighter atoms (carbon). Nevertheless, other experiments have given contrary results. They wanted to extend the technique by using polarized Sr EXAFS on layered Sr-substituted samples, to provide important angle information. Polarized EXAFS involves collecting spectra for different incident angles ({theta}) between the membrane normal of the layered sample and the X-ray electric field vector. Dichroism in the EXAFS can occur, depending on how the particular absorber-backscatterer (A-B) vector is aligned with the electric field. Through analysis of the dichroism, they extract the average number

  5. CaO interaction in the staged combustion of coal

    SciTech Connect

    Levy, A.; Merryman, E.L.; Rising, B.W.

    1983-12-19

    The LIMB (limestone injection multi-stage burner) process offers special potential for reducing NO/sub x/ and SO/sub x/ by at least 50 percent in coal combustion. This is to be accomplished by adding limestone with fuel and/or air in a low NO/sub x/ burner. This program has been directed to defining the chemistry and kinetics necessary to optimize sulfur capture in LIMB combustion. More specifically, this program has attempted to clarify the role of calcium sulfide in LIMB chemistry. When limestone is added in a staged burner, there is a strong possibility that under certain circumstances CaS is produced in the reducing (fuel-rich) zone of the burner. Since CaS is more stable than CaSO/sub 4/, this affords the opportunity to (1) operate the burner at a higher temperature, 2200 to 2500 F, (2) pass the CaS rapidly through the high temperature zone (before dissociation), and (3) complete the combustion in a lean (air-rich) region where the sulfur is finally retained in CaSO/sub 4/. For these reasons this program has concentrated on the high temperature chemistry and kinetics of CaS. To achieve the program objective, the program was divided into three tasks. These involved (1) a study of CaS formation, (2) a brief examination of CaS oxidation, and (3) a laboratory examination of the combustion of coal in the presence of CaO under first stage, fuel-rich conditions. In the most general sense, the study has shown that the formation of CaS in the reducing zones of the burner may be restricted by competing kinetics and thermodynamics. The addition of lime in LIMB will require special care to optimize the ability to capture sulfur. 36 references, 44 figures, 10 tables.

  6. Modulation of the matrix redox signaling by mitochondrial Ca(2.).

    PubMed

    Santo-Domingo, Jaime; Wiederkehr, Andreas; De Marchi, Umberto

    2015-11-26

    Mitochondria sense, shape and integrate signals, and thus function as central players in cellular signal transduction. Ca(2+) waves and redox reactions are two such intracellular signals modulated by mitochondria. Mitochondrial Ca(2+) transport is of utmost physio-pathological relevance with a strong impact on metabolism and cell fate. Despite its importance, the molecular nature of the proteins involved in mitochondrial Ca(2+) transport has been revealed only recently. Mitochondrial Ca(2+) promotes energy metabolism through the activation of matrix dehydrogenases and down-stream stimulation of the respiratory chain. These changes also alter the mitochondrial NAD(P)H/NAD(P)(+) ratio, but at the same time will increase reactive oxygen species (ROS) production. Reducing equivalents and ROS are having opposite effects on the mitochondrial redox state, which are hard to dissect. With the recent development of genetically encoded mitochondrial-targeted redox-sensitive sensors, real-time monitoring of matrix thiol redox dynamics has become possible. The discoveries of the molecular nature of mitochondrial transporters of Ca(2+) combined with the utilization of the novel redox sensors is shedding light on the complex relation between mitochondrial Ca(2+) and redox signals and their impact on cell function. In this review, we describe mitochondrial Ca(2+) handling, focusing on a number of newly identified proteins involved in mitochondrial Ca(2+) uptake and release. We further discuss our recent findings, revealing how mitochondrial Ca(2+) influences the matrix redox state. As a result, mitochondrial Ca(2+) is able to modulate the many mitochondrial redox-regulated processes linked to normal physiology and disease.

  7. Extracellular Ca(2+) sensing in salivary ductal cells.

    PubMed

    Bandyopadhyay, Bidhan C; Swaim, William D; Sarkar, Ankana; Liu, Xibao; Ambudkar, Indu S

    2012-08-31

    Ca(2+) is secreted from the salivary acinar cells as an ionic constituent of primary saliva. Ions such as Na(+) and Cl(-) get reabsorbed whereas primary saliva flows through the salivary ductal system. Although earlier studies have shown that salivary [Ca(2+)] decreases as it flows down the ductal tree into the oral cavity, ductal reabsorption of Ca(2+) remains enigmatic. Here we report a potential role for the G protein-coupled receptor, calcium-sensing receptor (CSR), in the regulation of Ca(2+) reabsorption by salivary gland ducts. Our data show that CSR is present in the apical region of ductal cells where it is co-localized with transient receptor potential canonical 3 (TRPC3). CSR is activated in isolated salivary gland ducts as well as a ductal cell line (SMIE) by altering extracellular [Ca(2+)] or by aromatic amino acid, L-phenylalanine (L-Phe, endogenous component of saliva), as well as neomycin. CSR activation leads to Ca(2+) influx that, in polarized cells grown on a filter support, is initiated in the luminal region. We show that TRPC3 contributes to Ca(2+) entry triggered by CSR activation. Further, stimulation of CSR in SMIE cells enhances the CSR-TRPC3 association as well as surface expression of TRPC3. Together our findings suggest that CSR could serve as a Ca(2+) sensor in the luminal membrane of salivary gland ducts and regulate reabsorption of [Ca(2+)] from the saliva via TRPC3, thus contributing to maintenance of salivary [Ca(2+)]. CSR could therefore be a potentially important protective mechanism against formation of salivary gland stones (sialolithiasis) and infection (sialoadenitis).

  8. The clinical significance of CA-125 in pulmonary tuberculosis.

    PubMed

    Kim, Eun Sun; Park, Kyoung Un; Song, JungHan; Lim, Hyo-Jeong; Cho, Young-Jae; Yoon, Hoil; Lee, JaeHo; Lee, Choon-Taek; Park, Jong Sun

    2013-03-01

    Cancer antigen 125 (CA-125) is usually elevated in ovarian cancer. However, there are several reports that serum CA-125 is elevated in tuberculosis. This study investigated the clinical significance of serum CA-125 measurements in patients with active pulmonary tuberculosis (TB). Between September 2008 and March 2011, Serum CA-125 was measured in patients with active pulmonary TB before treatment (baseline), and 6 and 12 months after initiation of anti-TB treatment. Patients with pulmonary TB confirmed by culture or polymerase chain reaction for Mycobacterium tuberculosis (TB-PCR) were included. The study enrolled 100 patients. The mean serum CA-125 was 38.9 ± 41.4 U/ml (reference value, <35 U/ml). Thirty-eight patients showed elevated CA-125. Significantly more of those with elevated CA-125 were female (p < 0.001), and had a positive sputum smear for acid-fast bacilli (AFB) (p = 0.030). They also significantly more showed extensive pulmonary lesions on chest X-ray (p = 0.004). Elevated CA-125 was independently associated with female gender (OR = 12.5, 95% CI: 3.4-45.2), positive acid-fast staining of sputum (OR = 6.0, 95% CI: 1.8-19.7), cavitary lung lesion (OR = 4.0, 95% CI: 1.2-12.9), and involvement of more than one lung on chest X-ray (OR = 9.4, 95% CI: 2.2-40.1). The CA-125 level decreased with anti-TB treatment (p = 0.001). Serum CA-125 was related to the activity and severity of pulmonary TB, and it may be useful in the monitoring of therapeutic responses in certain cases of active pulmonary TB, especially in female patients of active pulmonary TB. PMID:23414674

  9. Modulation of the matrix redox signaling by mitochondrial Ca2+

    PubMed Central

    Santo-Domingo, Jaime; Wiederkehr, Andreas; De Marchi, Umberto

    2015-01-01

    Mitochondria sense, shape and integrate signals, and thus function as central players in cellular signal transduction. Ca2+ waves and redox reactions are two such intracellular signals modulated by mitochondria. Mitochondrial Ca2+ transport is of utmost physio-pathological relevance with a strong impact on metabolism and cell fate. Despite its importance, the molecular nature of the proteins involved in mitochondrial Ca2+ transport has been revealed only recently. Mitochondrial Ca2+ promotes energy metabolism through the activation of matrix dehydrogenases and down-stream stimulation of the respiratory chain. These changes also alter the mitochondrial NAD(P)H/NAD(P)+ ratio, but at the same time will increase reactive oxygen species (ROS) production. Reducing equivalents and ROS are having opposite effects on the mitochondrial redox state, which are hard to dissect. With the recent development of genetically encoded mitochondrial-targeted redox-sensitive sensors, real-time monitoring of matrix thiol redox dynamics has become possible. The discoveries of the molecular nature of mitochondrial transporters of Ca2+ combined with the utilization of the novel redox sensors is shedding light on the complex relation between mitochondrial Ca2+ and redox signals and their impact on cell function. In this review, we describe mitochondrial Ca2+ handling, focusing on a number of newly identified proteins involved in mitochondrial Ca2+ uptake and release. We further discuss our recent findings, revealing how mitochondrial Ca2+ influences the matrix redox state. As a result, mitochondrial Ca2+ is able to modulate the many mitochondrial redox-regulated processes linked to normal physiology and disease. PMID:26629314

  10. Extracellular Ca2+ Sensing in Salivary Ductal Cells*

    PubMed Central

    Bandyopadhyay, Bidhan C.; Swaim, William D.; Sarkar, Ankana; Liu, Xibao; Ambudkar, Indu S.

    2012-01-01

    Ca2+ is secreted from the salivary acinar cells as an ionic constituent of primary saliva. Ions such as Na+ and Cl− get reabsorbed whereas primary saliva flows through the salivary ductal system. Although earlier studies have shown that salivary [Ca2+] decreases as it flows down the ductal tree into the oral cavity, ductal reabsorption of Ca2+ remains enigmatic. Here we report a potential role for the G protein-coupled receptor, calcium-sensing receptor (CSR), in the regulation of Ca2+ reabsorption by salivary gland ducts. Our data show that CSR is present in the apical region of ductal cells where it is co-localized with transient receptor potential canonical 3 (TRPC3). CSR is activated in isolated salivary gland ducts as well as a ductal cell line (SMIE) by altering extracellular [Ca2+] or by aromatic amino acid, l-phenylalanine (l-Phe, endogenous component of saliva), as well as neomycin. CSR activation leads to Ca2+ influx that, in polarized cells grown on a filter support, is initiated in the luminal region. We show that TRPC3 contributes to Ca2+ entry triggered by CSR activation. Further, stimulation of CSR in SMIE cells enhances the CSR-TRPC3 association as well as surface expression of TRPC3. Together our findings suggest that CSR could serve as a Ca2+ sensor in the luminal membrane of salivary gland ducts and regulate reabsorption of [Ca2+] from the saliva via TRPC3, thus contributing to maintenance of salivary [Ca2+]. CSR could therefore be a potentially important protective mechanism against formation of salivary gland stones (sialolithiasis) and infection (sialoadenitis). PMID:22778254

  11. CA_OPPUSST - Cantera OPUS Steady State

    2005-03-01

    The Cantera Opus Steady State (ca-opusst) applications solves steady reacting flow problems in opposed-flow geometries. It is a 1-0 application that represents axisymmetnc 3-0 physical systems that can be reduced via a similarity transformation to a 1-0 mathematical representation. The code contain solutions of the general dynamic equations for the particle distribution functions using a sectional model to describe the particle distribution function. Operators for particle nucleation, coagulation, condensation (i.e., growth/etching via reactions with themore » gas ambient), internal particle reactions. particle transport due to convection and due to molecular transport, are included in the particle general dynamics equation. Heat transport due to radiation exchange of the environment with particles in local thermal equilibrium to the surrounding gas will be included in the enthalpy conservation equation that is solved for the coupled gas! particle system in an upcoming version of the code due in June 2005. The codes use Cantera , a C++ Cal Tech code, for determination of gas phase species transport, reaction, and thermodynamics physical properties and source terms. The Codes use the Cantera Aerosol Dynamics Simulator (CADS) package, a general library for aerosol modeling, to calculate properties and source terms for the aerosol general dynamics equation, including particle formation from gas phase reactions, particle surface chemistry (growth and oxidation), bulk particle chemistry, particle transport by Brownian diffusion, thermophoresis, and diffusiophoresis, and thermal radiative transport involving particles. Also included are post-processing programs, cajost and cajrof, to extract ascii data from binary output files to produce plots.« less

  12. ANALOG I/O MODULE TEST SYSTEM BASED ON EPICS CA PROTOCOL AND ACTIVEX CA INTERFACE

    SciTech Connect

    YENG,YHOFF,L.

    2003-10-13

    Analog input (ADC) and output (DAC) modules play a substantial role in device level control of accelerator and large experiment physics control system. In order to get the best performance some features of analog modules including linearity, accuracy, crosstalk, thermal drift and so on have to be evaluated during the preliminary design phase. Gain and offset error calibration and thermal drift compensation (if needed) may have to be done in the implementation phase as well. A natural technique for performing these tasks is to interface the analog VO modules and GPIB interface programmable test instruments with a computer, which can complete measurements or calibration automatically. A difficulty is that drivers of analog modules and test instruments usually work on totally different platforms (vxworks VS Windows). Developing new test routines and drivers for testing instruments under VxWorks (or any other RTOS) platform is not a good solution because such systems have relatively poor user interface and developing such software requires substantial effort. EPICS CA protocol and ActiveX CA interface provide another choice, a PC and LabVIEW based test system. Analog 110 module can be interfaced from LabVIEW test routines via ActiveX CA interface. Test instruments can be controlled via LabVIEW drivers, most of which are provided by instrument vendors or by National Instruments. Labview also provides extensive data analysis and process functions. Using these functions, users can generate powerful test routines very easily. Several applications built for Spallation Neutron Source (SNS) Beam Loss Monitor (BLM) system are described in this paper.

  13. Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

    NASA Astrophysics Data System (ADS)

    Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.; Salvador, James R.; Meyer, Martin S.; Haddad, Daad B.; Wang, Hsin; Cai, W.

    2014-12-01

    Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled YbxBayCo4Sb12 with ZT values around 1.1 at 750 K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique, has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434-448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.

  14. Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

    SciTech Connect

    Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.; Salvador, James R.; Meyer, Martin S.; Haddad, Daad B.; Wang, Hsin; Cai, W.

    2014-12-28

    Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled YbxBayCo4Sb12 with ZT values around 1.1 at 750K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique, has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434-448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Finally, Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.

  15. Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

    DOE PAGES

    Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.; Salvador, James R.; Meyer, Martin S.; Haddad, Daad B.; Wang, Hsin; Cai, W.

    2014-12-28

    Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled YbxBayCo4Sb12 with ZT values around 1.1 at 750K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique, has been recently claimedmore » by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434-448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Finally, Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.« less

  16. Improved thermoelectric performance of n-type Ca and Ca-Ce filled skutterudites

    SciTech Connect

    Thompson, Daniel R.; Liu, Chang; Ellison, Nicole D.; Salvador, James R.; Meyer, Martin S.; Haddad, Daad B.; Wang, Hsin; Cai, W.

    2014-12-28

    Thermoelectric (TE) technology for use in automotive waste heat recovery is being advanced by General Motors with support from the US Department of Energy. Skutterudites are a very promising material for this application of TE technology due to their superior mechanical properties and good TE performance. Double-filled Yb{sub x}Ba{sub y}Co{sub 4}Sb{sub 12} with ZT values around 1.1 at 750 K are the best performing n-type skutterudites produced on a large scale using an economically viable approach of melt spinning (MS) in conjunction with spark plasma sintering (SPS). Another economical production method on the tons scale, the melt quench annealing (MQA) technique, has been recently claimed by Treibacher Industrie AG, further information is available [G. Rogl et al., Acta Mater. 76, 434–448 (2014)]. A possible hurdle to commercial implementation of these materials is the use of rare earths as the fillers to reduce thermal conductivity and improve the electrical transport properties. It will be shown herein that skutterudites double-filled with Ca and Ce, both of which are lower-cost fillers, display markedly different TE properties depending on whether they are produced by MQA or MS + SPS synthesis techniques. Ca and Ce double-filled skutterudites prepared by MS + SPS have TE properties that are superior to the same compositions prepared by MQA and that are comparable to the best performing Yb and Ba filled materials. Furthermore, the results of this study suggest that the unusually poor transport properties of MQA Ca-filled skutterudites can be ascribed to deleterious secondary phases, which is contrary to reports in the literature attempting to explain these irregularities via band structure features.

  17. Ca2+/Calmodulin-Dependent Protein Kinase Kinases (CaMKKs) Effects on AMP-Activated Protein Kinase (AMPK) Regulation of Chicken Sperm Functions

    PubMed Central

    Nguyen, Thi Mong Diep; Combarnous, Yves; Praud, Christophe; Duittoz, Anne; Blesbois, Elisabeth

    2016-01-01

    Sperm require high levels of energy to ensure motility and acrosome reaction (AR) accomplishment. The AMP-activated protein kinase (AMPK) has been demonstrated to be strongly involved in the control of these properties. We address here the question of the potential role of calcium mobilization on AMPK activation and function in chicken sperm through the Ca2+/calmodulin-dependent protein kinase kinases (CaMKKs) mediated pathway. The presence of CaMKKs and their substrates CaMKI and CaMKIV was evaluated by western-blotting and indirect immunofluorescence. Sperm were incubated in presence or absence of extracellular Ca2+, or of CaMKKs inhibitor (STO-609). Phosphorylations of AMPK, CaMKI, and CaMKIV, as well as sperm functions were evaluated. We demonstrate the presence of both CaMKKs (α and β), CaMKI and CaMKIV in chicken sperm. CaMKKα and CaMKI were localized in the acrosome, the midpiece, and at much lower fluorescence in the flagellum, whereas CaMKKβ was mostly localized in the flagellum and much less in the midpiece and the acrosome. CaMKIV was only present in the flagellum. The presence of extracellular calcium induced an increase in kinases phosphorylation and sperm activity. STO-609 reduced AMPK phosphorylation in the presence of extracellular Ca2+ but not in its absence. STO-609 did not affect CaMKIV phosphorylation but decreased CaMKI phosphorylation and this inhibition was quicker in the presence of extracellular Ca2+ than in its absence. STO-609 efficiently inhibited sperm motility and AR, both in the presence and absence of extracellular Ca2+. Our results show for the first time the presence of CaMKKs (α and β) and one of its substrate, CaMKI in different subcellular compartments in germ cells, as well as the changes in the AMPK regulation pathway, sperm motility and AR related to Ca2+ entry in sperm through the Ca2+/CaM/CaMKKs/CaMKI pathway. The Ca2+/CaMKKs/AMPK pathway is activated only under conditions of extracellular Ca2+ entry in the cells

  18. Plasma membrane Ca2+-ATPase 4: interaction with constitutive nitric oxide synthases in human sperm and prostasomes which carry Ca2+/CaM-dependent serine kinase.

    PubMed

    Andrews, Rachel E; Galileo, Deni S; Martin-DeLeon, Patricia A

    2015-11-01

    Deletion of the gene encoding the widely conserved plasma membrane calcium ATPase 4 (PMCA4), a major Ca(2+) efflux pump, leads to loss of sperm motility and male infertility in mice. PMCA4's partners in sperm and how its absence exerts its effect on fertility are unknown. We hypothesize that in sperm PMCA4 interacts with endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) which are rapidly activated by Ca(2+), and that these fertility-modulating proteins are present in prostasomes, which deliver them to sperm. We show that in human sperm PMCA4 is present on the acrosome, inner acrosomal membrane, posterior head, neck, midpiece and the proximal principal piece. PMCA4 localization showed inter- and intra-individual variation and was most abundant at the posterior head/neck junction, co-localizing with NOSs. Co-immunoprecipitations (Co-IP) revealed a close association of PMCA4 and the NOSs in Ca(2+) ionophore-treated sperm but much less so in uncapacitated untreated sperm. Fluorescence resonance energy transfer (FRET) showed a similar Ca(2+)-related association: PMCA4 and the NOSs are within 10 nm apart, and preferentially so in capacitated, compared with uncapacitated, sperm. FRET efficiencies varied, being significantly (P < 0.001) higher at high cytosolic Ca(2+) concentration ([Ca(2+)]c) in capacitated sperm than at low [Ca(2+)]c in uncapacitated sperm for the PMCA4-eNOS complex. These dynamic interactions were not seen for PMCA4-nNOS complexes, which had the highest FRET efficiencies. Further, along with Ca(2+)/CaM-dependent serine kinase (CASK), PMCA4 and the NOSs are present in the seminal plasma, specifically in prostasomes where Co-IP showed complexes similar to those in sperm. Finally, flow cytometry demonstrated that following co-incubation of sperm and seminal plasma, PMCA4 and the NOSs can be delivered in vitro to sperm via prostasomes. Our findings indicate that PMCA4 interacts simultaneously with the NOSs preferentially at

  19. Plasma membrane Ca2+-ATPase 4: interaction with constitutive nitric oxide synthases in human sperm and prostasomes which carry Ca2+/CaM-dependent serine kinase.

    PubMed

    Andrews, Rachel E; Galileo, Deni S; Martin-DeLeon, Patricia A

    2015-11-01

    Deletion of the gene encoding the widely conserved plasma membrane calcium ATPase 4 (PMCA4), a major Ca(2+) efflux pump, leads to loss of sperm motility and male infertility in mice. PMCA4's partners in sperm and how its absence exerts its effect on fertility are unknown. We hypothesize that in sperm PMCA4 interacts with endothelial nitric oxide synthase (eNOS) and neuronal nitric oxide synthase (nNOS) which are rapidly activated by Ca(2+), and that these fertility-modulating proteins are present in prostasomes, which deliver them to sperm. We show that in human sperm PMCA4 is present on the acrosome, inner acrosomal membrane, posterior head, neck, midpiece and the proximal principal piece. PMCA4 localization showed inter- and intra-individual variation and was most abundant at the posterior head/neck junction, co-localizing with NOSs. Co-immunoprecipitations (Co-IP) revealed a close association of PMCA4 and the NOSs in Ca(2+) ionophore-treated sperm but much less so in uncapacitated untreated sperm. Fluorescence resonance energy transfer (FRET) showed a similar Ca(2+)-related association: PMCA4 and the NOSs are within 10 nm apart, and preferentially so in capacitated, compared with uncapacitated, sperm. FRET efficiencies varied, being significantly (P < 0.001) higher at high cytosolic Ca(2+) concentration ([Ca(2+)]c) in capacitated sperm than at low [Ca(2+)]c in uncapacitated sperm for the PMCA4-eNOS complex. These dynamic interactions were not seen for PMCA4-nNOS complexes, which had the highest FRET efficiencies. Further, along with Ca(2+)/CaM-dependent serine kinase (CASK), PMCA4 and the NOSs are present in the seminal plasma, specifically in prostasomes where Co-IP showed complexes similar to those in sperm. Finally, flow cytometry demonstrated that following co-incubation of sperm and seminal plasma, PMCA4 and the NOSs can be delivered in vitro to sperm via prostasomes. Our findings indicate that PMCA4 interacts simultaneously with the NOSs preferentially at

  20. Thermoelectric properties of antiperovskite calcium oxides Ca3PbO and Ca3SnO

    NASA Astrophysics Data System (ADS)

    Okamoto, Y.; Sakamaki, A.; Takenaka, K.

    2016-05-01

    We report the thermoelectric properties of polycrystalline samples of Ca3Pb1-xBixO (x = 0, 0.1, 0.2) and Ca3SnO, both crystallizing in a cubic antiperovskite-type structure. The Ca3SnO sample shows metallic resistivity and its thermoelectric power approaches 100 μV K-1 at room temperature, resulting in the thermoelectric power factor of Ca3SnO being larger than that of Ca3Pb1-xBixO. On the basis of Hall and Sommerfeld coefficients, the Ca3SnO sample is found to be a p-type metal with a carrier density of ˜1019 cm-3, a mobility of ˜80 cm2 V-1 s-1, both comparable to those in degenerated semiconductors, and a moderately large hole carrier effective mass. The coexistence of moderately high mobility and large effective mass observed in Ca3SnO, as well as possible emergence of a multivalley electronic structure with a small band gap at low-symmetry points in k-space, suggests that the antiperovskite Ca oxides have strong potential as a thermoelectric material.

  1. Co and Mn doping effect in polycrystalline (Ca,La) and (Ca,Pr)FeAs2 superconductors

    NASA Astrophysics Data System (ADS)

    Yakita, Hiroyuki; Ogino, Hiraku; Sala, Alberto; Okada, Tomoyuki; Yamamoto, Akiyasu; Kishio, Kohji; Iyo, Akira; Eisaki, Hiroshi; Shimoyama, Jun-ichi

    2015-06-01

    The superconducting properties of Mn and Co doped (Ca,RE)FeAs2 ((Ca,RE)112: RE = La, Pr) were investigated. Co doping increased Tc of (Ca,Pr)112 while Mn doping suppressed the superconductivity of (Ca,RE)112. The Co doped (Ca,La)112 exhibited a large diamagnetic screening, as well as sharper superconducting transition than Co-free (Ca,La)112. Tc zero observed in the resistivity measurements increased from 14 to 30 K by Co doping, while {{T}c}onset was not increased. The critical current density, Jc, of Co doped (Ca,La)112 was approximately 2.1 × 104 A cm-2 and 3.2 × 103 A cm-2 at 2 K and 25 K, respectively, at near zero field. These relatively high Jc values and large diamagnetic screening observed in the susceptibility measurements of the polycrystalline bulks are evidence that Co doped (Ca,RE)112 compounds possess bulk superconductivity.

  2. A fast passive Ca2+ efflux mediated by the (Ca2+ + Mg2+)-ATPase in reconstituted vesicles.

    PubMed

    Gould, G W; McWhirter, J M; East, J M; Lee, A G

    1987-11-01

    The (Ca2+ + Mg2+)-ATPase from skeletal muscle sarcoplasmic reticulum was reconstituted into phospholipid bilayers. The permeability of lipid bilayers to Co2+ and glucose was increased slightly by incorporation of the ATPase, and the permeability of mixed bilayers of phosphatidylethanolamine and phosphatidylcholine increased with increasing content of phosphatidylethanolamine both in the presence and absence of the ATPase. The presence of the ATPase, however, resulted in a marked increase in permeability to Ca2+, the permeability decreasing with increasing phosphatidylethanolamine content. Permeability to Ca2+ was found to be dependent on pH and the external concentrations of Mg2+ and Ca2+, was stimulated by adenine nucleotides but was unaffected by inositol trisphosphate. A kinetic model is presented for Ca2+ efflux mediated by the ATPase. It is shown that the kinetic parameters that describe Ca2+ efflux from vesicles of sarcoplasmic reticulum also describe efflux from the vesicles reconstituted from the purified ATPase and phosphatidylcholine. It is shown that the effects of phosphatidylethanolamine on efflux can be simulated in terms of changes in the rates of the transitions linking conformations of the ATPase with inward- and outward-facing Ca2+-binding sites, and that effects of phosphatidylethanolamine on the ATPase activity of the ATPase can also be simulated in terms of effects on the corresponding conformational transitions. We conclude that the ATPase can act as a specific pathway for Ca2+ efflux from sarcoplasmic reticulum.

  3. Contracted State as an Energy Source for Ca Binding and Ca + Inorganic Phosphate Accumulation by Corn Mitochondria 1

    PubMed Central

    Kenefick, D. G.; Hanson, J. B.

    1966-01-01

    An investigation has been made of the possibility of utilizing the potential energy of the contracted state of corn mitochondria to drive Ca + inorganic phosphate accumulation. Contraction was obtained with succinate or NADH oxidation. In the succinate experiments the mitochondria were contracted in buffered KCl layered over sucrose in centrifuge tubes and centrifuged down through distinct wash, reactive and isotope exchange layers. In the NADH experiments, ion accumulation was initiated upon exhaustion of the substrate. The results show that mitochondria in the contracted state will actively bind some 45Ca, but no real accumulation occurs until inorganic phosphate is available. Substrate powered contraction in the presence of inorganic phosphate also provides a potential for accumulation upon subsequent reaction of the mitochondria with Ca. It is deducted that contraction is due to X∼I formation, to which Ca will bind. Subsequent reaction with inorganic phosphate produces CaX∼P, which is the transport moiety. When X∼P is formed first, Ca also reacts to produce CaX∼P. Hence it is immaterial which ion reacts first with the contracted state. Contraction is believed to result from the action of a mechanoenzyme, presumably I∼. The stability of CaX∼I must be low for the mitochondria swell very rapidly upon exhaustion of NADH or blocking of succinate oxidation by cyanide. PMID:16656446

  4. A Giant Simple Liver Cyst That Caused Increases in Serum CA 19-9 and CA 15-3 Levels.

    PubMed

    Dinc, Bulent; Mesci, Ayhan; Dinc, Selcan Enver; Oskay, Alten

    2014-12-01

    Simple cysts (SCs) of the liver are not associated with the biliary malformations in intrahepatic bile duct biliary. Seen in 0.1% to 7% of adult population, biliary malformations are more common in women. The levels of glycoprotein-like tumor markers (carbohydrate antigen (CA) 19-9) in the cysts and serum could be high. Although studies regarding CA 19-9 exist, sufficient data on cancer antigen (CA) 15-3 are not available. This case is about a 76-year-old woman who complained of painless intra-abdominal mass. The patient with a giant simple cyst extending from the gallbladder to the pelvis had preoparative CA 19-9 and CA 15-3 serum levels of 87.3 IU/L and 37 IU/L respectively. It was observed that CA 19-9 levels had decreased to 36 IU/L and CA 15-3 to 28.1 IU/L in blood samples taken in the third month after the surgery. There is a need for comprehensive studies to investigate the relationship between the size of the cyst and biomarkers (including markers such as CA 15-3) in the assesment of liver SC.

  5. Interfacial ferromagnetism and exchange bias in CaRuO3/CaMnO3 superlattices.

    PubMed

    He, C; Grutter, A J; Gu, M; Browning, N D; Takamura, Y; Kirby, B J; Borchers, J A; Kim, J W; Fitzsimmons, M R; Zhai, X; Mehta, V V; Wong, F J; Suzuki, Y

    2012-11-01

    We have found ferromagnetism in epitaxially grown superlattices of CaRuO(3)/CaMnO(3) that arises in one unit cell at the interface. Scanning transmission electron microscopy and electron energy loss spectroscopy indicate that the difference in magnitude of the Mn valence states between the center of the CaMnO(3) layer and the interface region is consistent with double exchange interaction among the Mn ions at the interface. Polarized neutron reflectivity and the CaMnO(3) thickness dependence of the exchange bias field together indicate that the interfacial ferromagnetism is only limited to one unit cell of CaMnO(3) at each interface. The interfacial moment alternates between the 1 μ(B)/interface Mn ion for even CaMnO(3) layers and the 0.5 μ(B)/interface Mn ion for odd CaMnO(3) layers. This modulation, combined with the exchange bias, suggests the presence of a modulating interlayer coupling between neighboring ferromagnetic interfaces via the antiferromagnetic CaMnO(3) layers.

  6. A SIMS Calibration of Benthic Foraminiferal Mg/Ca

    NASA Astrophysics Data System (ADS)

    Curry, W. B.; Marchitto, T. M.

    2005-12-01

    Using a suite of multi-core tops, we have produced a calibration of C. pachyderma Mg/Ca versus temperature spanning the temperature range of 5 to 18 °C. The core tops are located along the Florida margin south of Dry Tortugas (KNR166), along the Bahamas west of Andros Island and Great Bahama Bank (KNR166), and along the southeastern margin of Brazil (KNR159). Water depths range from about 200 to 800 m for the Florida Straits multi-cores and 400 to 800 m for the Brazil margin multi-cores. Five of the KNR166 core tops contain post-1950 bomb radiocarbon with Fmodern> 1; several others have bomb radiocarbon mixed in with pre-bomb sediments to give ages less than 0 BP. Core top ages are generally older for the KNR159 multi-cores, but each is from a location with a well documented Holocene section. Sedimentation rates for KNR166 multi-cores vary from 10 to 100 cm kyr-1; for KNR159 multi-cores, sedimentation rates vary from 5 to 10 cm kyr-1. Elemental ratios were determined by Secondary Ionization Mass Spectrometry (SIMS) using a Cameca IMS 3f ion probe calibrated for Mg/Ca and Sr/Ca using two standards which were independently measured using ICP-MS. Using SIMS, the external precision of the calibration standards averages ±3.5% (1σ RSD) for Mg/Ca and ± 1.7% (1σ RSD) for Sr/Ca. SIMS elemental measurements were performed on one to three individual C. pachyderma tests in each core top; more than 30 tests have been measured from 18 multi-core tops. Mg/Ca variability within C. pachyderma tests averages ± 20% (1σ RSD) with a small but significant trend toward higher variability at higher Mg/Ca. Higher Mg/Ca is observed in warmer waters, but the Mg/Ca values are generally lower (at comparable warm temperatures) than observed in previous calibration studies. At temperatures below 8 °C, C. pachyderma Mg/Ca values are less than 2 mmole/mole. At temperatures warmer than 15 °C, C. pachyderma Mg/Ca values exceed 3 mmole/mole. The slope of Mg/Ca versus temperature (~0.14 mmole

  7. Regional and interspecific variation in Sr, Ca, and Sr/Ca ratios in avian eggshells from the USA.

    PubMed

    Mora, Miguel A; Brattin, Bryan; Baxter, Catherine; Rivers, James W

    2011-08-01

    To examine regional variation in strontium (Sr), which at high concentrations may reduce eggshell quality, increase egg breakage and reproductive failure, we analyzed Sr, and calcium (Ca) concentrations and Sr/Ca ratios in eggshells from 20 avian species from California, Texas, Idaho, Kansas, and Michigan. In addition, we included data previously reported from Arizona to expand the regional comparisons and to better establish patterns of Sr, and Sr/Ca ratios in bird species across the United States. We found Sr concentrations varied significantly among regions, among species, and among foraging guilds; this variability is strongly influenced by the Sr/Ca ratios in surface water from locations close to the region where the eggshells were collected. Sr concentrations and Sr/Ca ratios were significantly higher in bird eggshells from the Volta wildlife region in the San Joaquin Valley, California and in various locales from Arizona. Sr concentrations and Sr/Ca ratios in bird eggshells from other locations in the USA were lower than those detected in these two regions. Among foraging guilds, invertivores had the highest Sr concentrations and Sr/Ca ratios and carnivores had the lowest. In general, the Sr/Ca ratio increased strongly with increasing Sr concentrations (R(2) = 0.99, P < 0.0001). There was a significant correlation (R(2) = 0.58, P < 0.0001) between Sr/Ca ratios in water and the average Sr/Ca ratios in eggshells suggesting that these values could be determined from Sr/Ca ratios in water. Eggshell thickness was poorly correlated with Sr (R(2) = 0.03) but had a significant and positive correlation with Ca and was more properly correlated by a quadratic equation (R(2) = 0.50, Thickness = 2.13 - 0.02Ca - 3.07 * 10(-5)Ca(2)). Our study provides further evidence that Sr accumulates significantly in the avian eggshell, in some regions at concentrations which could be of concern for potential negative effects on reproduction. We suggest that when assessing the effects

  8. Regional and interspecific variation in Sr, Ca, and Sr/Ca ratios in avian eggshells from the USA.

    PubMed

    Mora, Miguel A; Brattin, Bryan; Baxter, Catherine; Rivers, James W

    2011-08-01

    To examine regional variation in strontium (Sr), which at high concentrations may reduce eggshell quality, increase egg breakage and reproductive failure, we analyzed Sr, and calcium (Ca) concentrations and Sr/Ca ratios in eggshells from 20 avian species from California, Texas, Idaho, Kansas, and Michigan. In addition, we included data previously reported from Arizona to expand the regional comparisons and to better establish patterns of Sr, and Sr/Ca ratios in bird species across the United States. We found Sr concentrations varied significantly among regions, among species, and among foraging guilds; this variability is strongly influenced by the Sr/Ca ratios in surface water from locations close to the region where the eggshells were collected. Sr concentrations and Sr/Ca ratios were significantly higher in bird eggshells from the Volta wildlife region in the San Joaquin Valley, California and in various locales from Arizona. Sr concentrations and Sr/Ca ratios in bird eggshells from other locations in the USA were lower than those detected in these two regions. Among foraging guilds, invertivores had the highest Sr concentrations and Sr/Ca ratios and carnivores had the lowest. In general, the Sr/Ca ratio increased strongly with increasing Sr concentrations (R(2) = 0.99, P < 0.0001). There was a significant correlation (R(2) = 0.58, P < 0.0001) between Sr/Ca ratios in water and the average Sr/Ca ratios in eggshells suggesting that these values could be determined from Sr/Ca ratios in water. Eggshell thickness was poorly correlated with Sr (R(2) = 0.03) but had a significant and positive correlation with Ca and was more properly correlated by a quadratic equation (R(2) = 0.50, Thickness = 2.13 - 0.02Ca - 3.07 * 10(-5)Ca(2)). Our study provides further evidence that Sr accumulates significantly in the avian eggshell, in some regions at concentrations which could be of concern for potential negative effects on reproduction. We suggest that when assessing the effects

  9. Development of Ca2+ hotspots between Lymnaea neurons during synaptogenesis.

    PubMed

    Feng, Zhong-Ping; Grigoriev, Nikita; Munno, David; Lukowiak, Ken; MacVicar, Brian A; Goldberg, Jeffrey I; Syed, Naweed I

    2002-02-15

    Calcium (Ca2+) channel clustering at specific presynaptic sites is a hallmark of mature synapses. However, the spatial distribution patterns of Ca2+ channels at newly formed synapses have not yet been demonstrated. Similarly, it is unclear whether Ca2+ 'hotspots' often observed at the presynaptic sites are indeed target cell contact specific and represent a specialized mechanism by which Ca2+ channels are targeted to select synaptic sites. Utilizing both soma-soma paired (synapsed) and single neurons from the mollusk Lymnaea, we have tested the hypothesis that differential gradients of voltage-dependent Ca2+ signals develop in presynaptic neuron at its contact point with the postsynaptic neuron; and that these Ca2+ hotspots are target cell contact specific. Fura-2 imaging, or two-photon laser scanning microscopy of Calcium Green, was coupled with electrophysiological techniques to demonstrate that voltage-induced Ca2+ gradients (hotspots) develop in the presynaptic cell at its contact point with the postsynaptic neuron, but not in unpaired single cells. The incidence of Ca2+ hotspots coincided with the appearance of synaptic transmission between the paired cells, and these gradients were target cell contact specific. In contrast, the voltage-induced Ca2+ signal in unpaired neurons was uniformly distributed throughout the somata; a similar pattern of Ca2+ gradient was observed in the presynaptic neuron when it was soma-soma paired with a non-synaptic partner cell. Moreover, voltage clamp recording techniques, in conjunction with a fast, optical differential perfusion system, were used to demonstrate that the total whole-cell Ca2+ (or Ba2+) current density in single and paired cells was not significantly different. However, the amplitude of Ba2+ current was significantly higher in the presynaptic cell at its contact side with the postsynaptic neurons, compared with non-contacted regions. In summary, this study demonstrates that voltage-induced Ca2+ hotspots develop

  10. Development of Ca2+ hotspots between Lymnaea neurons during synaptogenesis

    PubMed Central

    Feng, Zhong-Ping; Grigoriev, Nikita; Munno, David; Lukowiak, Ken; MacVicar, Brian A; Goldberg, Jeffrey I; Syed, Naweed I

    2002-01-01

    Calcium (Ca2+) channel clustering at specific presynaptic sites is a hallmark of mature synapses. However, the spatial distribution patterns of Ca2+ channels at newly formed synapses have not yet been demonstrated. Similarly, it is unclear whether Ca2+ ‘hotspots’ often observed at the presynaptic sites are indeed target cell contact specific and represent a specialized mechanism by which Ca2+ channels are targeted to select synaptic sites. Utilizing both soma–soma paired (synapsed) and single neurons from the mollusk Lymnaea, we have tested the hypothesis that differential gradients of voltage-dependent Ca2+ signals develop in presynaptic neuron at its contact point with the postsynaptic neuron; and that these Ca2+ hotspots are target cell contact specific. Fura-2 imaging, or two-photon laser scanning microscopy of Calcium Green, was coupled with electrophysiological techniques to demonstrate that voltage-induced Ca2+ gradients (hotspots) develop in the presynaptic cell at its contact point with the postsynaptic neuron, but not in unpaired single cells. The incidence of Ca2+ hotspots coincided with the appearance of synaptic transmission between the paired cells, and these gradients were target cell contact specific. In contrast, the voltage-induced Ca2+ signal in unpaired neurons was uniformly distributed throughout the somata; a similar pattern of Ca2+ gradient was observed in the presynaptic neuron when it was soma–soma paired with a non-synaptic partner cell. Moreover, voltage clamp recording techniques, in conjunction with a fast, optical differential perfusion system, were used to demonstrate that the total whole-cell Ca2+ (or Ba2+) current density in single and paired cells was not significantly different. However, the amplitude of Ba2+ current was significantly higher in the presynaptic cell at its contact side with the postsynaptic neurons, compared with non-contacted regions. In summary, this study demonstrates that voltage-induced Ca2+ hotspots

  11. Ca²⁺ channel and Na⁺/Ca²⁺ exchange localization in cardiac myocytes.

    PubMed

    Scriven, David R L; Moore, Edwin D W

    2013-05-01

    L-type Ca(2+) channels and the Na(+)/Ca(2+) exchanger are the main pathways for Ca(2+) influx and efflux across the sarcolemma. The majority of Ca(2+) channels are found in couplons adjacent to ryanodine receptors, but there are at least two smaller, physically and functionally distinct, extradyadic populations. NCX is more widely dispersed in the membrane although a subpopulation is closely associated with the alpha-2 isoform of the Na(+)/K(+) ATPase and has a direct effect on ECC. In addition to Ca(2+) channels and ryanodine receptors, couplons in adult animals contain a variety of other occupants that modulate their function. These modulators can vary from one couplon to another creating a variety of molecular architectures. In this review we examine our current understanding of the molecular composition, binding partners and determinants of the localization of these proteins. PMID:23220152

  12. Na(+)-Ca sup 2+ exchange in cultured rat hepatocytes: Evidence against a role in cytosolic Ca sup 2+ regulation or signaling

    SciTech Connect

    Lidofsky, S.D.; Xie, M.H.; Scharschmidt, B.F. )

    1990-07-01

    Plasma membrane Na(+)-Ca2+ exchange contributes importantly to the regulation of cytosolic Ca2+ concentration ((Ca2+)i) in excitable cells. Despite extensive study in excitable tissues, the role of this transporter in the regulation of (Ca2+)i in hepatocytes is unknown, and conflicting information has been reported regarding the presence of Na(+)-Ca2+ exchange in hepatocyte plasma membrane vesicles. We have therefore assessed the role of Na(+)-dependent Ca2+ transport in the regulation of (Ca2+)i in rat hepatocytes in primary culture under basal conditions and after exposure to vasopressin, a hormone that elevates (Ca2+)i. Ca2+ efflux, measured using 45Ca, did not differ in the presence or absence of extracellular Na+, either under basal conditions or in response to vasopressin. (Ca2+)i, measured using the Ca2(+)-sensitive dye fura-2, was not altered by transient or prolonged exposure to Na(+)-free media or by exposure to ouabain in concentrations sufficient to produce a five-fold elevation in intracellular Na+ concentration. The (Ca2+)i response to vasopressin was also unaffected by Na+ removal or ouabain. By contrast, in cultured rat cardiac myocytes, cells that possess Na(+)-Ca2+ exchange, transient or prolonged Na+ removal as well as ouabain exposure produced greater than fivefold increases in (Ca2+)i compared with controls. We conclude that Na(+)-Ca2+ exchange does not contribute to the regulation of (Ca2+)i in hepatocytes.

  13. Development and evaluation of materials for thermochemical heat storage based on the CaO/CaCO3 reaction couple

    NASA Astrophysics Data System (ADS)

    Sakellariou, Kyriaki G.; Tsongidis, Nikolaos I.; Karagiannakis, George; Konstandopoulos, Athanasios G.; Baciu, Diana; Charalambopoulou, Georgia; Steriotis, Theodore; Stubos, Athanasios; Arlt, Wolfgang

    2016-05-01

    The current work relates to the development of synthetic calcium oxide (CaO) based compositions as candidate materials for energy storage under a cyclic carbonation/decarbonation reaction scheme. Although under such a cyclic scheme the energy density of natural lime based CaO is high (˜ 3MJ/kg), the particular materials suffer from notable cycle-to-cycle deactivation. To this direction, pure CaO and CaO/Al2O3 composites have been prepared and preliminarily evaluated under the suggested cyclic carbonation/decarbonation scheme in the temperature range of 600-800°C. For the composite materials, Ca/Al molar ratios were in the range between 95/5 and 52/48 and upon calcination the formation of mixed Ca/Al phases was verified. The preliminary evaluation of materials studied was conducted under 3 carbonation/decarbonation cycles and the loss of activity for the case of natural CaO was obvious. Synthetic materials with superior stability/capture c.f. natural CaO were further subjected to multi-cyclic carbonation/decarbonation, via which the positive effect of alumina addition was made evident. Selected compositions exhibited adequately high CO2 capture capacity and stable performance during multi-cyclic operation. Moreover, this study contains preliminary experiments referring to proof-of-principle validation of a concept based on the utilization of a CaO-based honeycomb reactor/heat exchanger preliminary design. In particular, cordierite monolithic structures were coated with natural CaO and in total 11 cycles were conducted. Upon operation, clear signs of heat dissipation by the imposed flow in the duration of the exothermic reaction step were identified.

  14. Hypomethylation of the MN/CA9 promoter and upregulated MN/CA9 expression in human renal cell carcinoma

    PubMed Central

    Cho, M; Uemura, H; Kim, S-C; Kawada, Y; Yoshida, K; Hirao, Y; Konishi, N; Saga, S; Yoshikawa, K

    2001-01-01

    MN/CA9 is a cancer-related gene, frequently activated in human renal cell carcinomas (RCCs). To reveal the activation mechanism, we investigated the relationship between methylation status of the MN/CA9 promoter region and gene expression using 13 human RCCs, and examined the effect of in vitro CpG methylation on the MN/CA9 promoter activity using a human RCC cell line (SK-RC-44), expressing MN/CA9. MN/CA9 expression was evaluated by RT-PCR and observed in 10 of 13 RCCs (77%). A total of 9 out of 10 MN/CA9-positive RCCs (90%) contained clear cell components. Methylation status of 6 CpGs in the MN/CA9 promoter region was decided by using the bisulfite genomic sequencing protocol. Out of 13 RCCs 9 (69%) showed partial hypomethylation of the CpG at −74 bp, while the other 4 RCCs and 3 normal kidney tissue samples showed complete methylation. Hypomethylation of the CpG at −74 bp was strongly correlated with MN/CA9 expression. Luciferase assay revealed that the MN/CA9 promoter activity was strongly suppressed by methylation of the CpG at −74 bp. These findings suggest that hypomethylation of the CpG at −74 bp in the MN/CA9 promoter region might play an important role in this gene activation of human RCC. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11506497

  15. Nipple discharge of CA15-3, CA125, CEA and TSGF as a new biomarker panel for breast cancer.

    PubMed

    Wang, Gangping; Qin, Yan; Zhang, Junxi; Zhao, Jinhui; Liang, Yun'ai; Zhang, Zuofeng; Qin, Meihua; Sun, Yanqing

    2014-05-28

    Breast cancer is the second leading cause of cancer death in women. Serum biomarkers such as cancer antigen 15-3 (CA15-3), cancer antigen 125 (CA125), and carcinoembryonic antigen (CEA) can be used as diagnostic and prognostic factors and can also provide valuable information during follow-up. However, serum protein biomarkers show limited diagnostic sensitivity and specificity in stand-alone assays because their levels reflect tumor burden. To validate whether biomarkers in nipple discharge may serve as novel biomarkers for breast cancer, we composed a panel of potential cancer biomarkers, including CA15-3, CA125, CEA, and malignant tumor-specific growth factor (TSGF), and evaluated their expression in both serum and nipple discharge in order to explore the expression and significance of estrogen receptor (ER), progestrone receptor (PR), epidermal growth factor receptor type 2 (HER2/neu), CA15-3, CA125, CEA, and TSGF expression for their combined predictive value for breast cancer and in judging the prognosis of breast cancer. Univariate analysis revealed that combined detection of CA15-3, CA125, CEA, and TSGF in nipple discharge served as novel biomarkers for the diagnosis and prognosis of breast cancer, but in the multivariate analyses the adverse effects of the four biomarkers combination in nipple discharge positivity on overall survival were lost. Multivariate analysis revealed that the positivity of the combined detection of the four biomarkers in both nipple discharge and serum was significantly higher than that of other detection methods. Thus, the combined detection of these four biomarkers both in serum and nipple discharge was retained as an independent prognostic variable in breast cancer patients. Our results indicate that CA15-3, CA125, CEA, and TSGF in nipple discharge can serve as novel biomarkers in the diagnosis and prognosis of breast cancer.

  16. The Oral History of Evaluation: The Professional Development of George Grob

    ERIC Educational Resources Information Center

    Miller, Robin L.; Caracelli, Valerie J.

    2014-01-01

    In this article the authors present the full interview conducted with George Grob in 2011 at the American Evaluation Association (AEA) Conference in Anaheim, CA. George Grob is former Director of the Office of Evaluation and Inspections in the Office of Inspector General. Prior to serving in that Office, he was Director of Planning and Policy…

  17. Technology 2003: The Fourth National Technology Transfer Conference and Exposition, volume 1

    NASA Technical Reports Server (NTRS)

    Hackett, Michael (Compiler)

    1994-01-01

    Proceedings from symposia of the Technology 2003 Conference and Exposition, December 7-9, 1993, Anaheim, CA, was discussed. Volume 1 features the Plenary Session and the Plenary Workshop, plus papers presented in Advanced Manufacturing, Biotechnology/Medical Technology, Environmental Technology, Materials Science, and Power and Energy.

  18. Technology 2003: The Fourth National Technology Transfer Conference and Exposition, volume 1

    SciTech Connect

    Not Available

    1994-02-01

    Proceedings from symposia of the Technology 2003 Conference and Exposition, December 7-9, 1993, Anaheim, CA, was discussed. Volume 1 features the Plenary Session and the Plenary Workshop, plus papers presented in Advanced Manufacturing, Biotechnology/Medical Technology, Environmental Technology, Materials Science, and Power and Energy.

  19. Technology 2003: The Fourth National Technology Transfer Conference and Exposition, volume 2

    NASA Technical Reports Server (NTRS)

    Hackett, Michael (Compiler)

    1994-01-01

    Proceedings from symposia of the Technology 2003 Conference and Exposition, Dec. 7-9, 1993, Anaheim, CA, are presented. Volume 2 features papers on artificial intelligence, CAD&E, computer hardware, computer software, information management, photonics, robotics, test and measurement, video and imaging, and virtual reality/simulation.

  20. Ca intercalated bilayer graphene as a thinnest limit of superconducting C6Ca.

    PubMed

    Kanetani, Kohei; Sugawara, Katsuaki; Sato, Takafumi; Shimizu, Ryota; Iwaya, Katsuya; Hitosugi, Taro; Takahashi, Takashi

    2012-11-27

    Success in isolating a 2D graphene sheet from bulky graphite has triggered intensive studies of its physical properties as well as its application in devices. Graphite intercalation compounds (GICs) have provided a platform of exotic quantum phenomena such as superconductivity, but it is unclear whether such intercalation is feasible in the thinnest 2D limit (i.e., bilayer graphene). Here we report a unique experimental realization of 2D GIC, by fabricating calcium-intercalated bilayer graphene C(6)CaC(6) on silicon carbide. We have investigated the structure and electronic states by scanning tunneling microscopy and angle-resolved photoemission spectroscopy. We observed a free-electron-like interlayer band at the Brillouin-zone center, which is thought to be responsible for the superconductivity in 3D GICs, in addition to a large π* Fermi surface at the zone boundary. The present success in fabricating Ca-intercalated bilayer graphene would open a promising route to search for other 2D superconductors as well as to explore its application in devices.