More Like this

1. 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. 

   more » « less
2. Marine and Anthropogenic Bromopyrroles Alter Cellular Ca 2+ Dynamics of Murine Cortical Neuronal Networks by Targeting the Ryanodine Receptor and Sarco/Endoplasmic Reticulum Ca 2+ -ATPase

   https://doi.org/10.1021/acs.est.1c05214  

   Zheng, Jing ; Antrobus, Shane ; Feng, Wei ; Purdy, Trevor N. ; Moore, Bradley S. ; Pessah, Isaac N. ( December 2021 , Environmental Science & Technology)
3. Phosphatidylinositol 3, 5‐bisphosphate regulates Ca 2+ transport during yeast vacuolar fusion through the Ca 2+ ATPase Pmc1

   https://doi.org/10.1111/tra.12736  

   Miner, Gregory E. ; Sullivan, Katherine D. ; Zhang, Chi ; Rivera‐Kohr, David ; Guo, Annie ; Hurst, Logan R. ; Ellis, Ez C. ; Starr, Matthew L. ; Jones, Brandon C. ; Fratti, Rutilio A. ( June 2020 , Traffic)

   The transport of Ca²⁺across membranes precedes the fusion and fission of various lipid bilayers. Yeast vacuoles under hyperosmotic stress become fragmented through fission events that requires the release of Ca²⁺stores through the TRP channel Yvc1. This requires the phosphorylation of phosphatidylinositol‐3‐phosphate (PI3P) by the PI3P‐5‐kinase Fab1 to produce transient PI(3,5)P₂pools. Ca²⁺is also released during vacuole fusion upontrans‐SNARE complex assembly, however, its role remains unclear. The effect of PI(3,5)P₂on Ca²⁺flux during fusion was independent of Yvc1. Here, we show that while low levels of PI(3,5)P₂were required for Ca²⁺uptake into the vacuole, increased concentrations abolished Ca²⁺efflux. This was as shown by the addition of exogenous dioctanoyl PI(3,5)P₂or increased endogenous production of by the hyperactivefab1^T2250Amutant. In contrast, the lack of PI(3,5)P₂on vacuoles from the kinase deadfab1^EEEmutant showed delayed and decreased Ca²⁺uptake. The effects of PI(3,5)P₂were linked to the Ca²⁺pump Pmc1, as its deletion rendered vacuoles resistant to the effects of excess PI(3,5)P₂. Experiments with Verapamil inhibited Ca²⁺uptake when added at the start of the assay, while adding it after Ca²⁺had been taken up resulted in the rapid expulsion of Ca²⁺. Vacuoles lacking both Pmc1 and the H⁺/Ca²⁺exchanger Vcx1 lacked the ability to take up Ca²⁺and instead expelled it upon the addition of ATP. Together these data suggest that a balance of efflux and uptake compete during the fusion pathway and that the levels of PI(3,5)P₂can modulate which path predominates.

    

   more » « less
4. 3D time-varying simulations of Ca 2+ dynamics in arterial coupled cells: A massively parallel implementation: TIME-VARYING SIMULATIONS OF Ca 2+ DYNAMICS IN ARTERIAL COUPLED CELLS

   https://doi.org/10.1002/cnm.2786  

   Zakkaroff, Constantine ; Moore, Stephen ; Dowding, Stewart ; David, Tim ( January 2016 , International Journal for Numerical Methods in Biomedical Engineering)
5. Ca 2+ /Sr 2+ /Ba 2+ dependent phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass

   https://doi.org/10.1111/jace.17299  

   Xu, Xiuxia ; Zhao, Junjie ; Chen, Xiaotong ; Xu, Qian ; Wang, Ting ; Yu, Siu Fung ; Xu, Xuhui ; Qiao, Xvsheng ; Du, Jincheng ; Fan, Xianping ; et al ( June 2020 , Journal of the American Ceramic Society)

   Fluoride phase separation is the initial stage of nanocrystallization in oxyfluoride glasses, and it is a key step in achieving transparent glass‐ceramics with good luminescence. In this work, we combine molecular dynamics (MD) simulations and experimental studies to investigate the phase separation, nanocrystallization and photoluminescence in fluoroaluminosilicate glass and glass‐ceramics containing alkali earth fluoride (MF₂). The results reveal different phase separation behaviors due to the field strength difference of M²⁺. The composition and size similarity between the fluoride‐rich regions in the MD simulated glass and the fluoride nanocrystals in the experimental prepared glass‐ceramics are observed, suggesting that the separated fluoride phase is the structural origin of the observed MF₂nanocrystals. Besides, in order to understand the M²⁺dependent glass structural features, the crystallization temperatures, the luminescent properties of Eu³⁺and Eu²⁺doped glass‐ceramics, and the lasing performance of Er³⁺doped glass‐ceramics are discussed. Based on these comprehensions, some strategies are proposed to help to efficiently design oxyfluoride glass with desired luminescence performance.

    

   more » « less