A transient outward-rectifying K+ channel current down-regulated by cytosolic Ca2+ in Arabidopsis thaliana guard cells

Sustained (noninactivating) outward-rectifying K+ channel currents have been identified in a variety of plant cell types and species. Here, in Arabidopsis thaliana guard cells, in addition to these sustained K+ currents, an inactivating outward-rectifying K+ current was characterized (plant A-type current: IAP). IAP activated rapidly with a time constant of 165 ms and inactivated slowly with a time constant of 7.2 sec at +40 mV. IAP was enhanced by increasing the duration (from 0 to 20 sec) and degree (from +20 to −100 mV) of prepulse hyperpolarization. Ionic substitution and relaxation (tail) current recordings showed that outward IAP was mainly carried by K+ ions. In contrast to the sustained outward-rectifying K+ currents, cytosolic alkaline pH was found to inhibit IAP and extracellular K+ was required for IAP activity. Furthermore, increasing cytosolic free Ca2+ in the physiological range strongly inhibited IAP activity with a half inhibitory concentration of ≈ 94 nM. We present a detailed characterization of an inactivating K+ current in a higher plant cell. Regulation of IAP by diverse factors including membrane potential, cytosolic Ca2+ and pH, and extracellular K+ and Ca2+ implies that the inactivating IAP described here may have important functions during transient depolarizations found in guard cells, and in integrated signal transduction processes during stomatal movements.

Evidence for the existence of a sulfonylurea-receptor-like protein in plants: Modulation of stomatal movements and guard cell potassium channels by sulfonylureas and potassium channel openers

Limitation of water loss and control of gas exchange is accomplished in plant leaves via stomatal guard cells. Stomata open in response to light when an increase in guard cell turgor is triggered by ions and water influx across the plasma membrane. Recent evidence demonstrating the existence of ATP-binding cassette proteins in plants led us to analyze the effect of compounds known for their ability to modulate ATP-sensitive potassium channels (K-ATP) in animal cells. By using epidermal strip bioassays and whole-cell patch-clamp experiments with Vicia faba guard cell protoplasts, we describe a pharmacological profile that is specific for the outward K+ channel and very similar to the one described for ATP-sensitive potassium channels in mammalian cells. Tolbutamide and glibenclamide induced stomatal opening in bioassays and in patch-clamp experiments, a specific inhibition of the outward K+ channel by these compounds was observed. Conversely, application of potassium channel openers such as cromakalim or RP49356 triggered stomatal closure. An apparent competition between sulfonylureas and potassium channel openers occurred in bioassays, and outward potassium currents, previously inhibited by glibenclamide, were partially recovered after application of cromakalim. By using an expressed sequence tag clone from an Arabidopsis thaliana homologue of the sulfonylurea receptor, a 7-kb transcript was detected by Northern blot analysis in guard cells and other tissues. Beside the molecular evidence recently obtained for the expression of ATP-binding cassette protein transcripts in plants, these results give pharmacological support to the presence of a sulfonylurea-receptor-like protein in the guard-cell plasma membrane tightly involved in the outward potassium channel regulation during stomatal movements.

Republican Scientific-Medical Library, The Republic of Armenia: progress and programs*

In 1990, the Republican Scientific-Medical Library (RSML) of the Ministry of Health of Armenia in collaboration with the Fund for Armenian Relief created a vision of a national library network supported by information technology. This vision incorporated four goals: (1) to develop a national resource collection of biomedical literature accessible to all health professionals, (2) to develop a national network for access to bibliographic information, (3) to develop a systematic mechanism for sharing resources, and (4) to develop a national network of health sciences libraries. During the last decade, the RSML has achieved significant progress toward all four goals and has realized its vision of becoming a fully functional national library. The RSML now provides access to the literature of the health sciences including access to the Armenian medical literature, provides education and training to health professionals and health sciences librarians, and manages a national network of libraries of the major health care institutions in Armenia. The RSML is now able to provide rapid access to the biomedical literature and train health professionals and health sciences librarians in Armenia in information system use. This paper describes the evolution of the RSML and how it was accomplished.

A European Border and Coast Guard: Fit for purpose? CEPS Commentary, 24 February 2016

In December 2015, The Commission proposed to set up a European Border and Coast Guard (EBCG) as one of the key responses to the 2015 ‘refugee crisis’. The initiative intends to give Frontex, the EU’s current border agency, more competences, staff and equipment, and to rename it the EBCG. The new EBCG would work together with the member states’ national border and coast guard authorities.

A 1990 Ford Taurus into heavy truck rigid rear underride guard in support of CRASH3 damage algorithm reformulation. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

A 1993 Honda Civic DX into heavy truck rigid rear underride guard in support of CRASH3 damage algorithm reformulation. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

A study of critical materials for the U.S. Coast Guard /

Prepared by Enviro Control, Inc.

Supplement to a study of critical materials for the U.S. Coast Guard /

Final report; June 1978.

Assessment of selected lighter-than-air vehicles for mission tasks of the U.S. Coast Guard /

"May 1978."

Underride guard design feasibility study. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Effectiveness of fire control agents on chemical fires : phase I, test methodology and baseline hexane tests : final report ; prepared for U.S. Department of Transportation, United States Coast Guard, Office of Research and Development.

"Report no. CG-D-50-80."

Survey, analysis and evaluation of domestic waste waters on Coast Guard vessels /

Final report; October 1976.

Morphological analysis of underwater sensing for Coast Guard applications /

Final report; April 1978.

Morphological analysis of underwater sensing for Coast Guard applications : appendix C /

Final report; April 1978.

Future underwater activities and their implications for the Coast Guard circa 1978-2000 /

"Report no. CG-D-65-78"--V. 2.