1. Radiative cooling rates of substituted PAH ions
James N Bull, Mark H Stockett, Boxing Zhu, Henning Zettergren, MingChao Ji J Chem Phys . 2022 Jul 28;157(4):044303. doi: 10.1063/5.0089687.
The unimolecular dissociation and infrared radiative cooling rates of cationic 1-hydroxypyrene (OHPyr+, C16H10O+) and 1-bromopyrene (BrPyr+, C16H9Br+) are measured using a cryogenic electrostatic ion beam storage ring. A novel numerical approach is developed to analyze the time dependence of the dissociation rate and to determine the absolute scaling of the radiative cooling rate coefficient. The model results show that radiative cooling competes with dissociation below the critical total vibrational energies Ec= 5.39(1) eV for OHPyr+and 5.90(1) eV for BrPyr+. These critical energies and implications for radiative cooling dynamics are important for astrochemical models concerned with energy dissipation and molecular lifecycles. The methods presented extend the utility of storage ring experiments on astrophysically relevant ions.
2. Marine and Anthropogenic Bromopyrroles Alter Cellular Ca2+ Dynamics of Murine Cortical Neuronal Networks by Targeting the Ryanodine Receptor and Sarco/Endoplasmic Reticulum Ca2+-ATPase
Jing Zheng, Trevor N Purdy, Isaac N Pessah, Shane Antrobus, Bradley S Moore, Wei Feng Environ Sci Technol . 2021 Dec 7;55(23):16023-16033. doi: 10.1021/acs.est.1c05214.
Bromopyrroles (BrPyr) are synthesized naturally by marine sponge symbionts and produced anthropogenically as byproducts of wastewater treatment. BrPyr interact with ryanodine receptors (RYRs) and sarco/endoplasmic reticulum (SR/ER) Ca2+-ATPase (SERCA). Influences of BrPyr on the neuronal network activity remain uncharted. BrPyr analogues with differing spectra of RYR/SERCA activities were tested using RYR-null or RYR1-expressing HEK293 and murine cortical neuronal/glial cocultures (NGCs) loaded with Fluo-4 to elucidate their mechanisms altering Ca2+dynamics. The NGC electrical spike activity (ESA) was measured from NGCs plated on multielectrode arrays. Nanomolar tetrabromopyrrole (TBP,1) potentiated caffeine-triggered Ca2+release independent of extracellular [Ca2+] in RYR1-HEK293, whereas higher concentrations produce slow and sustained rise in cytoplasmic [Ca2+] independent of RYR1 expression. TBP, 2,3,5-tribromopyrrole (2), pyrrole (3), 2,3,4-tribromopyrrole (4), and ethyl 4-bromopyrrole-2-carboxylate (5) added acutely to NGC showed differential potency; rank orderTBP(IC50≈ 220 nM) >2≫5, whereas3and4were inactive at 10 μM.TBP>2 μM elicited sustained elevation of cytoplasmic [Ca2+] and loss of neuronal viability.TBPdid not alter network ESA. BrPyr from marine and anthropogenic sources are ecological signaling molecules and emerging anthropogenic pollutants of concern to environmental and human health that potently alter ER Ca2+dynamics and warrant further investigationin vivo.
3. Integration of cellular and molecular endpoints to assess the toxicity of polycyclic aromatic hydrocarbons in HepG2 cell line
Patrícia I Morgado, Riccardo Wanke, Alexandra M M Antunes, Ana Sofia Cardoso, Sílvia Jose, Luisa Jordao Environ Toxicol Chem . 2017 Dec;36(12):3404-3414. doi: 10.1002/etc.3927.
Polycyclic aromatic hydrocarbons (PAHs) are persistent pollutants present in the environment with known mutagenic and carcinogenic properties. In the present study the effects of exposure to single or multiple doses of benzo[a]anthracene (BaA), pyrene (Pyr), and 3 halogenated derivatives of these compounds (1-chloropyrene, 1-bromopyrene [1-BrPyr], and 7-chlorobenzo[a]anthracene [7-ClBaA]) were evaluated in a liver-derived human cell line (HepG2). Cytotoxicity as assessed by the classic 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and neutral red assays showed a mild toxic effect in response to single or multiple dose exposure for up to 72 h, except for multiple dose exposure to BaA and 7-ClBaA (1 μM/d for 4 d) and single exposure to 10 μM BaA. Furthermore, selective mitochondrial and lysosomal toxicity was observed for Pyr and BaA series, respectively. To understand the underlying molecular mechanisms responsible for this effect, reactive oxygen species production, mitochondrial membrane depolarization, lysosomal pH, DNA fragmentation, and early and late apoptosis mediators were evaluated after exposure to single doses of the compounds. All compounds were able to trigger oxidative stress after 24 h as measured by catalase activity, and a good correlation was found between mitochondrial membrane depolarization, lysosomal pH increase, and MTT and neutral red assays. Evaluation of cell death mediators showed that caspase-3/7, but not annexin-V, pathways were involved in toxicity triggered by the studied compounds. The integration of all results showed that 1-BrPyr and BaA have a higher toxicity potential. Environ Toxicol Chem 2017;36:3404-3414. © 2017 SETAC.
CAS No.: 2669844-82-8
