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1. An Extracellular, Ca ²⁺ ‐Activated Nuclease ( EcnA ) Mediates Transformation in a Naturally Competent Archaeon

   https://doi.org/10.1111/mmi.15311  

   Fonseca, Dallas R; Day, Leslie A; Crone, Kathryn K; Costa, Kyle C (October 2024, Molecular Microbiology)

   ABSTRACT Transformation, the uptake of DNA directly from the environment, is a major driver of gene flow in microbial populations. In bacteria, DNA uptake requires a nuclease that processes dsDNA to ssDNA, which is subsequently transferred into the cell and incorporated into the genome. However, the process of DNA uptake in archaea is still unknown. Previously, we cataloged genes essential to natural transformation inMethanococcus maripaludis, but few homologs of bacterial transformation‐associated genes were identified. Here, we characterize one gene, MMJJ_16440 (named here asecnA), to be an extracellular nuclease. We show that EcnA is Ca²⁺‐activated, present on the cell surface, and essential for transformation. While EcnA can degrade several forms of DNA, the highest activity was observed with ssDNA as a substrate. Activity was also observed with circular dsDNA, suggesting that EcnA is an endonuclease. This is the first biochemical characterization of a transformation‐associated protein in a member of the archaeal domain and suggests that both archaeal and bacterial transformation initiate in an analogous fashion. 

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2. Ca ²⁺ release or Ca ²⁺ entry, that is the question: what governs Ca ²⁺ oscillations in pancreatic β cells?

   https://doi.org/10.1152/ajpendo.00030.2023  

   Fletcher, Patrick A.; Thompson, Ben; Liu, Chanté; Bertram, Richard; Satin, Leslie S.; Sherman, Arthur S. (June 2023, American Journal of Physiology-Endocrinology and Metabolism)

   The standard model for Ca 2+ oscillations in insulin-secreting pancreatic β cells centers on Ca 2+ entry through voltage-activated Ca 2+ channels. These work in combination with ATP-dependent K + channels, which are the bridge between the metabolic state of the cells and plasma membrane potential. This partnership underlies the ability of the β cells to secrete insulin appropriately on a minute-to-minute time scale to control whole body plasma glucose. Though this model, developed over more than 40 years through many cycles of experimentation and mathematical modeling, has been very successful, it has been challenged by a hypothesis that calcium-induced calcium release from the endoplasmic reticulum through ryanodine or inositol trisphosphate (IP3) receptors is instead the key driver of islet oscillations. We show here that the alternative model is in fact incompatible with a large body of established experimental data and that the new observations offered in support of it can be better explained by the standard model. 

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3. Molecular and electrophysiological characterization of anion transport in Arabidopsis thaliana pollen reveals regulatory roles for pH , Ca ²⁺ and GABA

   https://doi.org/10.1111/nph.15863  

   Domingos, Patrícia; Dias, Pedro N.; Tavares, Bárbara; Portes, Maria Teresa; Wudick, Michael M.; Konrad, Kai R.; Gilliham, Matthew; Bicho, Ana; Feijó, José A. (May 2019, New Phytologist)
4. A model of cardiac ryanodine receptor gating predicts experimental Ca ²⁺ -dynamics and Ca ²⁺ -triggered arrhythmia in the long QT syndrome

   https://doi.org/10.1063/1.5000711  

   Wilson, Dan; Ermentrout, Bard; Němec, Jan; Salama, Guy (September 2017, Chaos: An Interdisciplinary Journal of Nonlinear Science)
5. Phosphatidylserine affinity for and flip-flop dependence on Ca ²⁺ and Mg ²⁺ ions

   https://doi.org/10.1039/d4fd00206g  

   Hymas, Preston P; Conboy, John C (January 2025, Faraday Discussions)

   Ca²⁺ions are believed to play a crucial role in enzymatic regulation of lipid membrane asymmetry, yet direct effects of Ca²⁺on lipid flip-flop are unknown. Present work examines the influence of Ca–lipid interactions on lipid translocation. 

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