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Keywords = gun regulation

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15 pages, 990 KiB  
Commentary
Unpacking Violence: Examining Socioeconomic, Psychological, and Genetic Drivers of Gun-Related Homicide and Potential Solutions
by John Menezes and Kavita Batra
Urban Sci. 2025, 9(6), 190; https://doi.org/10.3390/urbansci9060190 - 26 May 2025
Viewed by 857
Abstract
Background: Gun-related homicide remains a persistent public health crisis in the United States, with over 48,000 firearm-related deaths reported in 2022, including 19,651 homicides and 27,032 suicides. Despite frequent calls for tighter gun control, firearm access alone does not explain the complexity of [...] Read more.
Background: Gun-related homicide remains a persistent public health crisis in the United States, with over 48,000 firearm-related deaths reported in 2022, including 19,651 homicides and 27,032 suicides. Despite frequent calls for tighter gun control, firearm access alone does not explain the complexity of violence. Objective: This commentary aims to unpack the socioeconomic, psychological, and biological drivers of gun-related homicide and propose integrative, evidence-based solutions that extend beyond legislative reform. Methods: We synthesized data from peer-reviewed literature, national crime and health databases (e.g., Centers for Disease Control and Prevention and Federal Bureau of Investigation), and international reports. We examined patterns related to poverty, trauma, male aggression, neurobiology, and firearm acquisition, as well as cross-national comparisons with countries like Switzerland and Mexico. Findings: Young males, particularly those aged 10–29, accounted for 50% of homicide offenders in 2022. African Americans experienced homicide rates of 23.1 per 100,000, ten times the rate among Whites. Up to 56% of incarcerated men report childhood physical trauma, and over 40% of those in prison exhibit symptoms of serious mental illness. While firearm legislation varies widely, analysis reveals that over 90% of crime guns are acquired illegally or through informal sources. International comparisons show that poverty and weak rule of law, more than gun laws alone, correlate with elevated homicide rates. Conclusions: Reducing gun violence sustainably requires a multifaceted approach. Authors advocate for investments in trauma-informed mental health care, focused deterrence programs, early childhood interventions, and improved enforcement against illegal gun trafficking. A public health strategy that integrates social reform with targeted regulation holds the greatest promise for long-term change. Full article
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14 pages, 4842 KiB  
Article
Direct Detection of Biosignature Gasses Using Corrosion-Resistant QIT-MS Sensor for Planetary Exploration
by Dragan Nikolić and Stojan M. Madzunkov
Biophysica 2025, 5(2), 17; https://doi.org/10.3390/biophysica5020017 - 3 May 2025
Cited by 1 | Viewed by 585
Abstract
We present a corrosion-resistant quadrupole ion trap mass spectrometer (QIT-MS) for the direct detection of biosignature gasses in chemically reactive planetary atmospheres, such as Venusian clouds. The system employs a Paul trap with hyperbolic titanium alloy electrodes and alumina spacers for chemical durability [...] Read more.
We present a corrosion-resistant quadrupole ion trap mass spectrometer (QIT-MS) for the direct detection of biosignature gasses in chemically reactive planetary atmospheres, such as Venusian clouds. The system employs a Paul trap with hyperbolic titanium alloy electrodes and alumina spacers for chemical durability and precise ion confinement. An yttria-coated iridium filament serves as the thermionic emitter within a modular electron gun capable of axial and radial ionization. Analytes are introduced through fused silica capillaries and crescent inlets into a miniature pressure cell. The testbed integrates high-voltage RF electronics, pressure-regulated sample delivery, and FPGA-based control for real-time tuning. Continuous operation in 98% sulfuric acid vapor for over three months demonstrated no degradation in emitter or sensor performance. Mass spectra revealed H2SO4 fragmentation and thermally induced decomposition up to 425 K. Spectral variations with filament current and electron energy highlight thermal and electron-induced dissociation dynamics. Operational modes include high-resolution scans and selective ion ejection (e.g., CO2+, N2+) to enhance the detection of PH3+, H2S+, and daughter ions. The compact QIT-MS platform is validated for future missions targeting corrosive atmospheres, enabling in situ astrobiological investigations through the detection of biosignature gasses such as phosphine and hydrogen sulfide. Full article
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33 pages, 1357 KiB  
Article
From Guns to Mental Health and Accountability: Decoding Media Narratives and Audience Reactions in Public Mass Shootings
by Maurice N. Emelu and Brent Brossmann
Journal. Media 2025, 6(1), 11; https://doi.org/10.3390/journalmedia6010011 - 18 Jan 2025
Viewed by 2839
Abstract
Public mass shootings pose a critical safety challenge in the U.S. This study investigates how media framing relates to public online engagement, focusing on gun regulation, mental health, and individual and political accountability across five major TV networks: ABC, CNN, Fox News, MSNBC, [...] Read more.
Public mass shootings pose a critical safety challenge in the U.S. This study investigates how media framing relates to public online engagement, focusing on gun regulation, mental health, and individual and political accountability across five major TV networks: ABC, CNN, Fox News, MSNBC, and NBC. Using a mixed-methods approach, the research analyzes 678 news reports and 7605 audience comments. Findings reveal significant differences in audience engagement based on framing, and in key variables show audiences taking opposite positions to their news network’s narratives. ABC, CNN, and NBC’s thematic framing, highlighting systemic failures, elicits more balanced responses, whereas Fox News and MSNBC’s episodic framing, emphasizing individual or political accountability, correlates with polarized reactions. This research extends media framing theories by showing how episodic framing reduces support for systemic reforms, emphasizing personal responsibility. The study offers crucial insights for scholars, policymakers, and journalists on media’s role in shaping public discourse on gun violence. Full article
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19 pages, 8708 KiB  
Article
Genome-Wide Analysis of GLK Gene Family in Four Cotton Species Provides Insights into Their Involvement in Cotton Abiotic Stress Response
by Rui Tang, Xin Zhou, Shuangshuang Weng, Fei Wang, Rong Li, Quanliang Xie, Zihan Li, Shuangquan Xie, Aiping Cao, Lu Zhuo, Manhong Wang and Hongbin Li
Agriculture 2024, 14(11), 2086; https://doi.org/10.3390/agriculture14112086 - 19 Nov 2024
Cited by 1 | Viewed by 1279
Abstract
Cotton is a crucial economic crop that supplies natural fibers for the textile industry, with fiber quality being greatly impacted by abiotic stress throughout its growth stages. The Golden2-Like (GLK) gene family plays a key role in plant development and adaptation [...] Read more.
Cotton is a crucial economic crop that supplies natural fibers for the textile industry, with fiber quality being greatly impacted by abiotic stress throughout its growth stages. The Golden2-Like (GLK) gene family plays a key role in plant development and adaptation to abiotic stress. However, the specific functions and regulatory mechanisms of GLK members in cotton remain largely unexplored. In this study, a thorough analysis of GLK in four cotton species (Gossypium arboreum, G. raimondii, G. hirsutum, and G. barbadense) was conducted. A total of 198 GLK genes were identified in cotton. Conserved sequence analysis revealed that most GLK proteins contain two highly conserved domains: a MYB DNA-binding domain and a C-terminal (GCT) box. Promoter element analysis results show that the GLK gene family contains many stress response-related elements. Expression analysis demonstrated that GhGLK2, GhGLK11, GhGLK16, and GhGLK30 responded significantly to drought, salt, and temperature stresses. And GhGLK2, GhGLK13, GhGLK38, GhGLK42, and GhGLK46 responded significantly to cotton development. Yeast one-hybrid, yeast two-hybrid, and dual-luciferase assay results indicate that GhGLK2 interacts with GhGUN5, GhPIL6, GhNAC6, GhTPX2, and GhERF10. These findings suggest that these GhGLKs may play crucial roles in regulating the response to abiotic stress. Overall, this study provides a solid theoretical foundation for understanding the role of the GLK gene family in cotton’s response to abiotic stress. Full article
(This article belongs to the Section Crop Genetics, Genomics and Breeding)
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11 pages, 1783 KiB  
Article
Characteristics of Carbon Nanotube Cold Cathode Triode Electron Gun Driven by MOSFET Working at Subthreshold Region
by Yajie Guo, Baohong Li, Yu Zhang, Shaozhi Deng and Jun Chen
Nanomaterials 2024, 14(15), 1260; https://doi.org/10.3390/nano14151260 - 28 Jul 2024
Cited by 2 | Viewed by 1683
Abstract
The carbon nanotube cold cathode has important applications in the X-ray source, microwave tube, neutralizer, etc. In this study, the characteristics of carbon nanotube (CNT) electron gun in series with metal-oxide-semiconductor field-effect transistor (MOSFET) were studied. CNTs were prepared on a stainless steel [...] Read more.
The carbon nanotube cold cathode has important applications in the X-ray source, microwave tube, neutralizer, etc. In this study, the characteristics of carbon nanotube (CNT) electron gun in series with metal-oxide-semiconductor field-effect transistor (MOSFET) were studied. CNTs were prepared on a stainless steel substrate by chemical vapor deposition and assembled with a mesh gate to form an electron gun. The anode current of the electron gun can be accurately regulated by precisely controlling the MOSFET gate voltage in the subthreshold region from 1 to 40 µA. The current stability measurements show the cathode current fluctuation was 0.87% under 10 h continuous operation, and the corresponding anode current fluctuation was 2.3%. The result has demonstrated that the MOSFET can be applied for the precise control of the CNT electron gun and greatly improve current stability. Full article
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10 pages, 2608 KiB  
Article
Linear Plasma Device for the Study of Plasma–Surface Interactions
by Bauyrzhan Rakhadilov, Zarina Satbayeva, Arystanbek Kusainov, Erasyl Naimankumaruly, Riza Abylkalykova and Laila Sulyubayeva
Appl. Sci. 2023, 13(21), 11673; https://doi.org/10.3390/app132111673 - 25 Oct 2023
Cited by 2 | Viewed by 1812
Abstract
At the research and production company “PlasmaScience” (Ust-Kamenogorsk, Kazakhstan), a linear plasma generator installation, KAZ-PSI (Kazakhstan Plasma Generator for Plasma Surface Interactions), has been developed and constructed for the study of the interaction of plasma and materials. This article outlines some features of [...] Read more.
At the research and production company “PlasmaScience” (Ust-Kamenogorsk, Kazakhstan), a linear plasma generator installation, KAZ-PSI (Kazakhstan Plasma Generator for Plasma Surface Interactions), has been developed and constructed for the study of the interaction of plasma and materials. This article outlines some features of the developed experimental installation designed for the investigation of surface–plasma interactions. The primary components of the linear plasma installation include an electron-beam gun with a LaB6 cathode, a plasma-beam discharge chamber, an interaction chamber, a target device, and an electromagnetic system comprising electromagnetic coils. The KAZ-PSI unit enables continuous plasma generation using hydrogen, deuterium, helium, argon, and nitrogen. The electron density of the plasma is in the range of about 1017–1018 m−3 and the electron temperature is in the range of 1 to 20 eV. The incident ion energy is regulated by applying a negative potential of up to 2 kV to the target. Experiments on the irradiation of tungsten with helium plasma were carried out using the KAZ-PSI installation for the first time. This article presents the research findings on the structure and properties of tungsten relative to the temperature of helium plasma irradiation. Alterations in roughness, microstructure, hardness, modulus of elasticity, and erosion of the tungsten’s surface following helium plasma irradiation at varying temperatures were examined. The study’s results indicate that helium plasma irradiation induces changes in the morphology of the tungsten’s surface, creating surface relief due to sputtering by helium ions, as well as the formation of blisters. Mechanical testing revealed that after irradiation at T = 500 °C, there was an increase in hardness of up to 10%, and a slight decrease in modulus of elasticity. And after irradiation at T = 900 °C and T = 1300 °C, both hardness and elastic modulus decreased with rising temperature. The tungsten surface erosion evaluation results showed that the degrees of surface erosion increase with increasing target temperature. Full article
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12 pages, 1429 KiB  
Review
Gunshot Abdominal Injuries: A Report of Two Cases and a Review of the Literature
by Zlatan Elek, Gojko Igrutinovic, Blagoje Grujic, Ivona Djordjevic and Strahinja Konstantinovic
Medicina 2023, 59(10), 1713; https://doi.org/10.3390/medicina59101713 - 25 Sep 2023
Cited by 2 | Viewed by 4181
Abstract
Abdominal injuries in children caused by guns are a rare clinical entity globally. But, in countries with undefined legal regulations and in war zones, urban violence is a tremendous social problem among older children and adolescents. This manuscript provides details regarding two cases [...] Read more.
Abdominal injuries in children caused by guns are a rare clinical entity globally. But, in countries with undefined legal regulations and in war zones, urban violence is a tremendous social problem among older children and adolescents. This manuscript provides details regarding two cases of severe gunshot injuries in young children. The injuries were very complicated and included damage to the parenchymatous and hollow organs and major blood vessels. The clinical presentation on admission was severe and dramatic, but the patients survived. However, one patient developed numerous complications that required repeated surgical interventions and long treatment. This article provides a detailed description of injuries and how to treat them. Patient care requires a multidisciplinary approach, and the initial decision on further treatment depends on the patient’s hemodynamic stability. Full article
(This article belongs to the Section Surgery)
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12 pages, 1362 KiB  
Article
Oct4 and Hypoxia Dual-Regulated Oncolytic Adenovirus Armed with shRNA-Targeting Dendritic Cell Immunoreceptor Exerts Potent Antitumor Activity against Bladder Cancer
by Che-Yuan Hu, Chi-Feng Hung, Pi-Che Chen, Jia-Yu Hsu, Chung-Teng Wang, Ming-Derg Lai, Yuh-Shyan Tsai, Ai-Li Shiau, Gia-Shing Shieh and Chao-Liang Wu
Biomedicines 2023, 11(10), 2598; https://doi.org/10.3390/biomedicines11102598 - 22 Sep 2023
Cited by 4 | Viewed by 1805
Abstract
Immunotherapy has emerged as a promising modality for cancer treatment. Dendritic cell immunoreceptor (DCIR), a C-type lectin receptor, is expressed mainly by dendritic cells (DCs) and mediates inhibitory intracellular signaling. Inhibition of DCIR activation may enhance antitumor activity. DCIR is encoded by CLEC4A [...] Read more.
Immunotherapy has emerged as a promising modality for cancer treatment. Dendritic cell immunoreceptor (DCIR), a C-type lectin receptor, is expressed mainly by dendritic cells (DCs) and mediates inhibitory intracellular signaling. Inhibition of DCIR activation may enhance antitumor activity. DCIR is encoded by CLEC4A in humans and by Clec4a2 in mice. Gene gun-mediated delivery of short hairpin RNA (shRNA) targeting Clec4a2 into mice bearing bladder tumors reduces DCIR expression in DCs, inhibiting tumor growth and inducing CD8+ T cell immune responses. Various oncolytic adenoviruses have been developed in clinical trials. Previously, we have developed Ad.LCY, an oncolytic adenovirus regulated by Oct4 and hypoxia, and demonstrated its antitumor efficacy. Here, we generated a Clec4a2 shRNA-expressing oncolytic adenovirus derived from Ad.LCY, designated Ad.shDCIR, aimed at inducing more robust antitumor immune responses. Our results show that treatment with Ad.shDCIR reduced Clec4a expression in DCs in cell culture. Furthermore, Ad.shDCIR exerted cytolytic effects solely on MBT-2 bladder cancer cells but not on normal NIH 3T3 mouse fibroblasts, confirming the tumor selectivity of Ad.shDCIR. Compared to Ad.LCY, Ad.shDCIR induced higher cytotoxic T lymphocyte (CTL) activity in MBT-2 tumor-bearing immunocompetent mice. In addition, Ad.shDCIR and Ad.LCY exhibited similar antitumor effects on inhibiting tumor growth. Notably, Ad.shDCIR was superior to Ad.LCY in prolonging the survival of tumor-bearing mice. In conclusion, Ad.shDCIR may be further explored as a combination therapy of virotherapy and immunotherapy for bladder cancer and likely other types of cancer. Full article
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18 pages, 4860 KiB  
Article
The Chemical Composition and Transcriptome Analysis Reveal the Mechanism of Color Formation in Tea (Camellia sinensis) Pericarp
by Yueyang Du, Yongen Lin, Kaikai Zhang, Dylan O’Neill Rothenberg, Huan Zhang, Hui Zhou, Hongfeng Su and Lingyun Zhang
Int. J. Mol. Sci. 2023, 24(17), 13198; https://doi.org/10.3390/ijms241713198 - 25 Aug 2023
Cited by 2 | Viewed by 2391
Abstract
To elucidate the molecular mechanisms underlying the differential metabolism of albino (white), green, and purple pericarp coloration, biochemical profiling and transcriptome sequencing analyses were performed on three different tea pericarps, Zhongbaiyihao (Camellia sinensis L. var. Zhongbai), Jinxuan (Camellia sinensis L. var. [...] Read more.
To elucidate the molecular mechanisms underlying the differential metabolism of albino (white), green, and purple pericarp coloration, biochemical profiling and transcriptome sequencing analyses were performed on three different tea pericarps, Zhongbaiyihao (Camellia sinensis L. var. Zhongbai), Jinxuan (Camellia sinensis L. var. Jinxuan), and Baitangziya (Camellia sinensis L. var. Baitang). Results of biochemical analysis revealed that low chlorophyll content and low chlorophyll/carotene ratio may be the biochemical basis for albino characteristics in the ‘Zhongbaiyihao’ pericarp. The differentially expressed genes (DEGs) involved in anthocyanin biosynthesis, including DFR, F3′5′H, CCoAOMT, and 4-coumaroyl-CoA, were highly expressed in the purple ‘Baitangziya’ pericarp. In the chlorophyll synthesis of white pericarp, GUN5 (Genome Uncoupled 5) and 8-vinyl-reductase both showed high expression levels compared to the green one, which indicated that albino ‘Zhongbaiyihao’ pericarp had a higher chlorophyll synthesis capacity than ‘Jinxuan’. Meanwhile, chlorophyllase (CLH, CSS0004684) was lower in ‘Baitang’ than in ‘Jinxuan’ and ‘Zhongbaiyihao’ pericarp. Among the differentially expressed transcription factors, MYB59, WRKY41-like2 (CS ng17509), bHLH62 like1 (CS ng6804), and bHLH62-like3 (CSS0039948) were downregulated in Jinxuan pericarp, suggesting that transcription factors played a role in regulating tea pericarp coloration. These findings provide a better understanding of the molecular mechanisms and theoretical basis for utilizing functional components of tea pericarp. Full article
(This article belongs to the Special Issue Molecular and Metabolic Regulation of Plant Secondary Metabolism)
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14 pages, 4422 KiB  
Article
Design and Verification of Adaptive Adjustable Output Control on Micro Spray Gun
by Jiun-Hung Lin, Chih-Hong Chen and Shih-Tsang Tang
Machines 2023, 11(3), 354; https://doi.org/10.3390/machines11030354 - 4 Mar 2023
Cited by 1 | Viewed by 2112
Abstract
The general spray gun is used for industrial large-area spraying, and there is less demand for different pressures and the accuracy of spraying pressure, so mechanical pressure regulators are mostly used. However, as the demand for artistic innovation continues to grow, it promotes [...] Read more.
The general spray gun is used for industrial large-area spraying, and there is less demand for different pressures and the accuracy of spraying pressure, so mechanical pressure regulators are mostly used. However, as the demand for artistic innovation continues to grow, it promotes the advent of the micro spray gun. The micro spray gun is currently commonly known as an airbrush. The micro spray gun is mainly used for fine drawing, so it must provide different pressures with high precision pressures, but the existing mechanical regulators cannot meet this requirement. For these unmet requirements, this study proposed a solution for PID (proportional-integral-derivative) control micro spray gun system. The results showed that the PID control could effectively provide various stable output pressures of the micro spray gun. The pressure-varying range of 30 kPa could rapidly return to the target value in 10 s (the usual spraying time). The proposed solution then presents better spraying effects. Full article
(This article belongs to the Topic Designs and Drive Control of Electromechanical Machines)
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16 pages, 1582 KiB  
Article
Bacteriophage Infection of the Marine Bacterium Shewanella glacialimarina Induces Dynamic Changes in tRNA Modifications
by Mirka Lampi, Pavlina Gregorova, M. Suleman Qasim, Niklas C. V. Ahlblad and L. Peter Sarin
Microorganisms 2023, 11(2), 355; https://doi.org/10.3390/microorganisms11020355 - 31 Jan 2023
Cited by 4 | Viewed by 2797
Abstract
Viruses are obligate intracellular parasites that, throughout evolution, have adapted numerous strategies to control the translation machinery, including the modulation of post-transcriptional modifications (PTMs) on transfer RNA (tRNA). PTMs are critical translation regulators used to further host immune responses as well as the [...] Read more.
Viruses are obligate intracellular parasites that, throughout evolution, have adapted numerous strategies to control the translation machinery, including the modulation of post-transcriptional modifications (PTMs) on transfer RNA (tRNA). PTMs are critical translation regulators used to further host immune responses as well as the expression of viral proteins. Yet, we lack critical insight into the temporal dynamics of infection-induced changes to the tRNA modification landscape (i.e., ‘modificome’). In this study, we provide the first comprehensive quantitative characterization of the tRNA modificome in the marine bacterium Shewanella glacialimarina during Shewanella phage 1/4 infection. Specifically, we show that PTMs can be grouped into distinct categories based on modification level changes at various infection stages. Furthermore, we observe a preference for the UAC codon in viral transcripts expressed at the late stage of infection, which coincides with an increase in queuosine modification. Queuosine appears exclusively on tRNAs with GUN anticodons, suggesting a correlation between phage codon usage and PTM modification. Importantly, this work provides the basis for further studies into RNA-based regulatory mechanisms employed by bacteriophages to control the prokaryotic translation machinery. Full article
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46 pages, 4459 KiB  
Article
Categorizing Active Marine Acoustic Sources Based on Their Potential to Affect Marine Animals
by Carolyn D. Ruppel, Thomas C. Weber, Erica R. Staaterman, Stanley J. Labak and Patrick E. Hart
J. Mar. Sci. Eng. 2022, 10(9), 1278; https://doi.org/10.3390/jmse10091278 - 9 Sep 2022
Cited by 12 | Viewed by 9487
Abstract
Marine acoustic sources are widely used for geophysical imaging, oceanographic sensing, and communicating with and tracking objects or robotic vehicles in the water column. Under the U.S. Marine Mammal Protection Act and similar regulations in several other countries, the impact of controlled acoustic [...] Read more.
Marine acoustic sources are widely used for geophysical imaging, oceanographic sensing, and communicating with and tracking objects or robotic vehicles in the water column. Under the U.S. Marine Mammal Protection Act and similar regulations in several other countries, the impact of controlled acoustic sources is assessed based on whether the sound levels received by marine mammals meet the criteria for harassment that causes certain behavioral responses. This study describes quantitative factors beyond received sound levels that could be used to assess how marine species are affected by many commonly deployed marine acoustic sources, including airguns, high-resolution geophysical sources (e.g., multibeam echosounders, sidescan sonars, subbottom profilers, boomers, and sparkers), oceanographic instrumentation (e.g., acoustic doppler current profilers, split-beam fisheries sonars), and communication/tracking sources (e.g., acoustic releases and locators, navigational transponders). Using physical criteria about the sources, such as source level, transmission frequency, directionality, beamwidth, and pulse repetition rate, we divide marine acoustic sources into four tiers that could inform regulatory evaluation. Tier 1 refers to high-energy airgun surveys with a total volume larger than 1500 in3 (24.5 L) or arrays with more than 12 airguns, while Tier 2 covers the remaining low/intermediate energy airgun surveys. Tier 4 includes most high-resolution geophysical, oceanographic, and communication/tracking sources, which are considered unlikely to result in incidental take of marine mammals and therefore termed de minimis. Tier 3 covers most non-airgun seismic sources, which either have characteristics that do not meet the de minimis category (e.g., some sparkers) or could not be fully evaluated here (e.g., bubble guns, some boomers). We also consider the simultaneous use of multiple acoustic sources, discuss marine mammal field observations that are consistent with the de minimis designation for some acoustic sources, and suggest how to evaluate acoustic sources that are not explicitly considered here. Full article
(This article belongs to the Section Marine Environmental Science)
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12 pages, 1638 KiB  
Article
β-Cyclocitral Does Not Contribute to Singlet Oxygen-Signalling in Algae, but May Down-Regulate Chlorophyll Synthesis
by Thomas Roach, Theresa Baur and Ilse Kranner
Plants 2022, 11(16), 2155; https://doi.org/10.3390/plants11162155 - 19 Aug 2022
Cited by 6 | Viewed by 2658
Abstract
Light stress signalling in algae and plants is partially orchestrated by singlet oxygen (1O2), a reactive oxygen species (ROS) that causes significant damage within the chloroplast, such as lipid peroxidation. In the vicinity of the photosystem II reaction centre, [...] Read more.
Light stress signalling in algae and plants is partially orchestrated by singlet oxygen (1O2), a reactive oxygen species (ROS) that causes significant damage within the chloroplast, such as lipid peroxidation. In the vicinity of the photosystem II reaction centre, a major source of 1O2, are two β-carotene molecules that quench 1O2 to ground-state oxygen. 1O2 can oxidise β-carotene to release β-cyclocitral, which has emerged as a 1O2-mediated stress signal in the plant Arabidopsis thaliana. We investigated if β-cyclocitral can have similar retrograde signalling properties in the unicellular alga Chlamydomonas reinhardtii. Using RNA-Seq, we show that genes up-regulated in response to exogenous β-cyclocitral included CAROTENOID CLEAVAGE DIOXYGENASE 8 (CCD8), while down-regulated genes included those associated with porphyrin and chlorophyll anabolism, such as tetrapyrrole-binding protein (GUN4), magnesium chelatases (CHLI1, CHLI2, CHLD, CHLH1), light-dependent protochlorophyllide reductase (POR1), copper target 1 protein (CTH1), and coproporphyrinogen III oxidase (CPX1). Down-regulation of this pathway has also been shown in β-cyclocitral-treated A. thaliana, indicating conservation of this signalling mechanism in plants. However, in contrast to A. thaliana, a very limited overlap in differential gene expression was found in β-cyclocitral-treated and 1O2-treated C. reinhardtii. Furthermore, exogenous treatment with β-cyclocitral did not induce tolerance to 1O2. We conclude that while β-cyclocitral may down-regulate chlorophyll synthesis, it does not seem to contribute to 1O2-mediated high light stress signalling in algae. Full article
(This article belongs to the Special Issue 10th Anniversary of Plants—Recent Advances and Perspectives)
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15 pages, 3248 KiB  
Article
Genome-Wide Identification of the Eucalyptus urophylla GATA Gene Family and Its Diverse Roles in Chlorophyll Biosynthesis
by Kang Du, Yufei Xia, Dingju Zhan, Tingting Xu, Te Lu, Jun Yang and Xiangyang Kang
Int. J. Mol. Sci. 2022, 23(9), 5251; https://doi.org/10.3390/ijms23095251 - 8 May 2022
Cited by 16 | Viewed by 2997
Abstract
GATA transcription factors have been demonstrated to play key regulatory roles in plant growth, development, and hormonal response. However, the knowledge concerning the evolution of GATA genes in Eucalyptus urophylla and their trans-regulatory interaction is indistinct. Phylogenetic analysis and study of conserved motifs, [...] Read more.
GATA transcription factors have been demonstrated to play key regulatory roles in plant growth, development, and hormonal response. However, the knowledge concerning the evolution of GATA genes in Eucalyptus urophylla and their trans-regulatory interaction is indistinct. Phylogenetic analysis and study of conserved motifs, exon structures, and expression patterns resolved the evolutionary relationships of these GATA proteins. Phylogenetic analysis showed that EgrGATAs are broadly distributed in four subfamilies. Cis-element analysis of promoters revealed that EgrGATA genes respond to light and are influenced by multiple hormones and abiotic stresses. Transcriptome analysis revealed distinct temporal and spatial expression patterns of EgrGATA genes in various tissues of E. urophylla S.T.Blake, which was confirmed by real-time quantitative PCR (RT-qPCR). Further research revealed that EurGNC and EurCGA1 were localized in the nucleus, and EurGNC directly binds to the cis-element of the EurGUN5 promoter, implying its potential roles in the regulation of chlorophyll synthesis. This comprehensive study provides new insights into the evolution of GATAs and could help to improve the photosynthetic assimilation and vegetative growth of E. urophylla at the genetic level. Full article
(This article belongs to the Collection Genetics and Molecular Breeding in Plants)
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15 pages, 6015 KiB  
Article
GUN4 Affects the Circadian Clock and Seedlings Adaptation to Changing Light Conditions
by Tao Li, Rui Wu, Zhixin Liu, Jiajing Wang, Chenxi Guo, Yaping Zhou, George Bawa and Xuwu Sun
Int. J. Mol. Sci. 2022, 23(1), 194; https://doi.org/10.3390/ijms23010194 - 24 Dec 2021
Cited by 5 | Viewed by 3490
Abstract
The chloroplast is a key organelle for photosynthesis and perceiving environmental information. GENOME UNCOUPLED 4 (GUN4) has been shown to be required for the regulation of both chlorophyll synthesis, reactive oxygen species (ROS) homeostasis and plastid retrograde signaling. In this study, we found [...] Read more.
The chloroplast is a key organelle for photosynthesis and perceiving environmental information. GENOME UNCOUPLED 4 (GUN4) has been shown to be required for the regulation of both chlorophyll synthesis, reactive oxygen species (ROS) homeostasis and plastid retrograde signaling. In this study, we found that growth of the gun4 mutant was significantly improved under medium strong light (200 μmol photons m−2s−1) compared to normal light (100 μmol photons m−2s−1), in marked contrast to wild-type (WT). Further analysis revealed that GUN4 interacts with SIGNAL RECOGNITION PARTICLE 54 KDA SUBUNIT (SRP43) and SRP54. RNA-seq analysis indicated that the expression of genes for light signaling and the circadian clock is altered in gun4 compared with (WT). qPCR analysis confirmed that the expression of the clock genes CLOCK-RELATED 1 (CCA1), LATE ELONGATION HYPOCOTYL (LHY), TIMING OF CAB EXPRESSION 1 (TOC1) and PSEUDO RESPONSE REGULATOR 7 (PRR7) is significantly changed in the gun4 and srp54 mutants under normal and medium strong light conditions. These results suggest that GUN4 may coordinate the adaptation of plants to changing light conditions by regulating the biological clock, although it is not clear whether the effect is direct or indirect. Full article
(This article belongs to the Special Issue Chloroplast and Stress Signaling)
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