English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Others have shown that exposing oocytes to high levels of NH(3)/NH(4)(+) (10-20 mM) causes a paradoxical fall in intracellular pH (pH(i)), whereas low levels (e.g., 0.5 mM) cause little pH(i) change. Here we monitored pH(i) and extracellular surface pH (pH(S)) while exposing oocytes to 5 or 0.5 mM NH(3)/NH(4)(+). We confirm that 5 mM NH(3)/NH(4)(+) causes a paradoxical pH(i) fall (-DeltapH(i) approximately equal 0.2), but also observe an abrupt pH(S) fall (-DeltapH(S) approximately equal 0.2)-indicative of NH(3) influx-followed by a slow decay. Reducing [NH(3)/NH(4)(+)] to 0.5 mM minimizes pH(i) changes but maintains pH(S) changes at a reduced magnitude. Expressing AmtB (bacterial Rh homologue) exaggerates -DeltapH(S) at both NH(3)/NH(4)(+) levels. During removal of 0.5 or 5 mM NH(3)/NH(4)(+), failure of pH(S) to markedly overshoot bulk extracellular pH implies little NH(3) efflux and, thus, little free cytosolic NH(3)/NH(4)(+). A new analysis of the effects of NH(3) vs. NH(4)(+) fluxes on pH(S) and pH(i) indicates that (a) NH(3) rather than NH(4)(+) fluxes dominate pH(i) and pH(S) changes and (b) oocytes dispose of most incoming NH(3). NMR studies of oocytes exposed to (15)N-labeled NH(3)/NH(4)(+) show no significant formation of glutamine but substantial NH(3)/NH(4)(+) accumulation in what is likely an acid intracellular compartment. In conclusion, parallel measurements of pH(i) and pH(S) demonstrate that NH(3) flows across the plasma membrane and provide new insights into how a protein molecule in the plasma membrane-AmtB-enhances the flux of a gas across a biological membrane.

Concentration-Dependent Effects on Intracellular and Surface pH of Exposing Xenopus oocytes to Solutions Containing NH3/NH4 +