In electrically nonexcitable cells, Ca2+ influx is essential for regulating a host of kinetically distinct processes involving exocytosis, enzyme control, gene regulation, cell growth and prolifera...

Store-operated calcium channels.

Cellular Mechanisms of Aluminum Toxicity and Resistance in Plants

Excitation−emission matrixes (EEMs) of 379 dissolved organic matter (DOM) samples from diverse aquatic environments were modeled by parallel factor analysis (PARAFAC). Thirteen components likely representing groups of similarly fluorescing moieties were found to explain the variation in this data set. Seven of the thirteen components were identified as quinone-like based on comparison of their excitation and emission spectra to spectra of model quinones. These quinone-like fluorophores were found to vary in redox state and degree of conjugation. Two components were identified as amino acid-like based on comparison to tyrosine and tryptophan fluorescence spectra. The other four components are not yet associated with any class of molecules. The quinone-like fluorophores account for about 50% of the fluorescence for every sample analyzed, showing that quinone-like fluorophores are an important and ubiquitous fluorescing moiety and in natural waters. Further, the distribution of the quinone-like fluorophores ...

Fluorescence spectroscopy reveals ubiquitous presence of oxidized and reduced quinones in dissolved organic matter.

Single cardiac transmembranous Ca channels have three modes of gating behaviour in the absence of drugs, expressed as current records with brief openings (mode 1), with no openings because of channel unavailability (mode 0 or null mode) and with long-lasting openings and very brief closings that appear only rarely (mode 2). The dihydropyridine Ca agonist Bay K 8644 enhances Ca channel current by promoting mode 2, while the Ca antagonists nitrendipine and nimodipine inhibit the current by favouring mode 0.

Different modes of Ca channel gating behaviour favoured by dihydropyridine Ca agonists and antagonists

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The replacement of the nondescript term ‘heavy metals’ by a biologically and chemically significant classification of metal ions

Calcium in biological systems

Spectroscopic approaches to the study of the interaction of aluminum with humic substances

The contribution of nuclear Overhauser enhancements to signal intensities in proton decoupled 13C nuclear magnetic resonance spectra can be determined by comparing the spectrum obtained with continuous proton irradiation to the spectrum obtained with a gated decoupler technique. The gated decoupler technique utilizes a sequence of acquiring data with the decoupler on followed by a delay time with the decoupler turned off; under appropriate conditions, it gives a fully decoupled spectrum with no nuclear Overhauser enhancements. The mathematical relationship describing the delay requirements for accurate intensity comparisons depends on the ratio of the acquisition and delay times to the longitudinal relaxation time of the carbon, as well as on the magnitude of the nuclear Overhauser enhancement.

Donald J. Nelson

Papers

Calcium in biological systems

Spectroscopic approaches to the study of the interaction of aluminum with humic substances

Dynamics of nuclear Overhauser enhancement in proton decoupled carbon‐13 nuclear magnetic resonance

Fluorescence and FT-IR spectroscopic studies of Suwannee River fulvic acid complexation with aluminum, terbium and calcium.

Antileishmanial effect of allopurinol and allopurinol ribonucleoside on intracellular forms of Leishmania donovani.