scholarly journals Perturbation of GABA Biosynthesis Links Cell Cycle to Control Arabidopsis thaliana Leaf Development

2020 ◽  
Author(s):  
Yaxin Gong ◽  
Han Yue ◽  
Yu Xiang ◽  
Guanghui Yu
Keyword(s):  
Reactive Oxygen Species ◽  
Leaf Development ◽  
Cell Expansion ◽  
Leaf Blade ◽  
Aminobutyric Acid ◽  
Oxygen Species ◽  
Gaba Level ◽  
Wild Type ◽  
Blade Area ◽  
In The Wild

AbstractTo investigate the molecular mechanism underlying increasing leaf area in γ-Aminobutyric acid (GABA) biosynthetic mutants, the first pair of true leaves of GABA biosynthetic mutants was measured. The results showed that the leaf blade area in GABA biosynthetic mutants was larger than that of the wild type to different extents, and the area of the leaf epidermal cells in mutants was larger than that of the wild type. DNA polyploid analysis showed that polyploid cells in GABA biosynthetic mutants were appearing earlier and more abundant than in the wild type. To check the correlation between cell size and endoreplication, the expression of factors involving endocycles, including D-type cyclin gene (CYCD3;1, CYCD3;2, CYCD3;3, and CYCD4;1) and kinase CKDA;1, were analysed by qRT-PCR. The results showed that CKDA;1 in GABA biosynthetic mutants was downregulated, and four types of CYCDs showed different expression patterns in different GABA biosynthetic mutants. Inconsistent with this result, for CCS52A (CELL CYCLE SWITCH 52A) (controlling the endocycle entry) in gad2 and gad1/gad2 mutants, the expression of CCS52A2 was significantly higher than that in the wild type. The expression of SIM (SIAMESE) and SMR (SIAMESE-RELATED), which inhibit kinase activity, were also upregulated compared with the control. To further study the possible potential relationship between GABA metabolism and endoreplication, we analysed the reactive oxygen species (ROS) levels in guard cells using ROS fluorescent probes. ROS levels were significantly higher in GABA biosynthetic mutants than the control. All results indicated that cyclin, the cyclin-dependent kinase, and its inhibitory protein were coordinated to participate in endoreplication control at the transcription level in the leaves of GABA biosynthetic mutant Arabidopsis.Contribution to the field statementγ-Aminobutyric acid (GABA) metabolic pathway plays a dual role in plant development. This research investigated the perturbation of GABA biosynthesis on Arabidopsis leave endoreplication for the first time. In the GABA biosynthetic mutants, many genes, participating in cell division regulation, are coordinately transcriptionally expressed to trigger the onset and maintenance of endoreplication, and this led to the cell expansion and the increase leaf blade area. However, this initiation of endoreplication links with the decrease of endogenous GABA level and the increase Reactive oxygen species (ROS). This may be a compensation mechanism to adapt to abnormal GABA level in plant leaf development. Present evidence provided hypothesized that the normal GABA level in plant leaf development plays a brake to inhibit the immature cell expansion and differentiation, and this negative regulation functions a guarantee mechanism to watchdog the normal leaf development. In all, this contribution provides an updated perspective on the role of GABA in plant development.

scholarly journals Catalase Protects Biofilm of Staphylococcus aureus against Daptomycin Activity

Antibiotics ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 511
Author(s):  
Cristina El Haj ◽  
Mads Lichtenberg ◽  
Karen Leth Nielsen ◽  
Thomas Bjarnsholt ◽  
Peter Østrup Jensen
Keyword(s):  
Reactive Oxygen Species ◽  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Oxygen Species ◽  
Bacterial Survival ◽  
Wild Type ◽  
Microtiter Plates ◽  
In The Wild ◽  
Ros Formation ◽  
High Concentrations

Daptomycin is recommended for the treatment of Staphylococcus aureus infections due to its bactericidal activity. However, its mechanism of action is poorly understood. The involvement of reactive oxygen species (ROS) in the bactericidal activity of daptomycin has been proved against planktonic S. aureus, but not against the biofilm of S. aureus. Therefore, we evaluated if ROS contributes to the effect of daptomycin against biofilm of S. aureus. Biofilms of wild type, catalase deficient and daptomycin-resistant S. aureus strains were grown in microtiter-plates. After three days, the biofilms were exposed to daptomycin with or without thiourea in the presence of a ROS indicator. After overnight incubation, the amount of ROS and the percentage of surviving bacteria were determined. The bacterial survival was higher and the amount of ROS was lower in the wild type than in the catalase deficient biofilm, demonstrating a protective effect of catalase against daptomycin. The induction of cytotoxic ROS formation by daptomycin was verified by the addition of thiourea, which reduced the amount of ROS and protected the wild type biofilm against high concentrations of daptomycin. Accordingly, only the highest concentration of daptomycin reduced the bacterial survival and increased the ROS formation in the resistant biofilm. In conclusion, daptomycin induced the production of cytotoxic levels of endogenous ROS in S. aureus biofilm and the presence of catalase protected the biofilm against the lethality of the induced ROS.

scholarly journals Redox crisis underlies conditional light–dark lethality in cyanobacterial mutants that lack the circadian regulator, RpaA

2017 ◽  
Vol 114 (4) ◽  
pp. E580-E589 ◽  
Author(s):  
Spencer Diamond ◽  
Benjamin E. Rubin ◽  
Ryan K. Shultzaberger ◽  
You Chen ◽  
Chase D. Barber ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Response Regulator ◽  
Mechanistic Explanation ◽  
Growth Conditions ◽  
Oxygen Species ◽  
Wild Type ◽  
Profound Influence ◽  
In The Wild ◽  
Pcc 7942 ◽  
Null Mutants

Cyanobacteria evolved a robust circadian clock, which has a profound influence on fitness and metabolism under daily light–dark (LD) cycles. In the model cyanobacterium Synechococcus elongatus PCC 7942, a functional clock is not required for diurnal growth, but mutants defective for the response regulator that mediates transcriptional rhythms in the wild-type, regulator of phycobilisome association A (RpaA), cannot be cultured under LD conditions. We found that rpaA-null mutants are inviable after several hours in the dark and compared the metabolomes of wild-type and rpaA-null strains to identify the source of lethality. Here, we show that the wild-type metabolome is very stable throughout the night, and this stability is lost in the absence of RpaA. Additionally, an rpaA mutant accumulates excessive reactive oxygen species (ROS) during the day and is unable to clear it during the night. The rpaA-null metabolome indicates that these cells are reductant-starved in the dark, likely because enzymes of the primary nighttime NADPH-producing pathway are direct targets of RpaA. Because NADPH is required for processes that detoxify ROS, conditional LD lethality likely results from inability of the mutant to activate reductant-requiring pathways that detoxify ROS when photosynthesis is not active. We identified second-site mutations and growth conditions that suppress LD lethality in the mutant background that support these conclusions. These results provide a mechanistic explanation as to why rpaA-null mutants die in the dark, further connect the clock to metabolism under diurnal growth, and indicate that RpaA likely has important unidentified functions during the day.

scholarly journals Production and scavenging of reactive oxygen species both affect reproductive success in male and female Drosophila melanogaster

2021 ◽  
Author(s):  
Biz R. Turnell ◽  
Luisa Kumpitsch ◽  
Klaus Reinhardt
Keyword(s):  
Reactive Oxygen Species ◽  
Drosophila Melanogaster ◽  
Reactive Oxygen ◽  
Cellular Aging ◽  
Ros Production ◽  
Oxygen Species ◽  
Wild Type ◽  
Ros Scavenging ◽  
Respiratory Pathway ◽  
Male And Female

AbstractSperm aging is accelerated by the buildup of reactive oxygen species (ROS), which cause oxidative damage to various cellular components. Aging can be slowed by limiting the production of mitochondrial ROS and by increasing the production of antioxidants, both of which can be generated in the sperm cell itself or in the surrounding somatic tissues of the male and female reproductive tracts. However, few studies have compared the separate contributions of ROS production and ROS scavenging to sperm aging, or to cellular aging in general. We measured reproductive fitness in two lines of Drosophila melanogaster genetically engineered to (1) produce fewer ROS via expression of alternative oxidase (AOX), an alternative respiratory pathway; or (2) scavenge fewer ROS due to a loss-of-function mutation in the antioxidant gene dj-1β. Wild-type females mated to AOX males had increased fecundity and longer fertility durations, consistent with slower aging in AOX sperm. Contrary to expectations, fitness was not reduced in wild-type females mated to dj-1β males. Fecundity and fertility duration were increased in AOX and decreased in dj-1β females, indicating that female ROS levels may affect aging rates in stored sperm and/or eggs. Finally, we found evidence that accelerated aging in dj-1β sperm may have selected for more frequent mating. Our results help to clarify the relative roles of ROS production and ROS scavenging in the male and female reproductive systems.

scholarly journals Somatic production of reactive oxygen species does not predict its production in sperm cells across Drosophila melanogaster lines

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Biz R. Turnell ◽  
Luisa Kumpitsch ◽  
Anne-Cécile Ribou ◽  
Klaus Reinhardt
Keyword(s):  
Reactive Oxygen Species ◽  
Drosophila Melanogaster ◽  
Reactive Oxygen ◽  
Future Research ◽  
Ros Production ◽  
Oxygen Species ◽  
Loss Of Function ◽  
Wild Type ◽  
Ros Scavenging ◽  
Transport Chain

Abstract Objective Sperm ageing has major evolutionary implications but has received comparatively little attention. Ageing in sperm and other cells is driven largely by oxidative damage from reactive oxygen species (ROS) generated by the mitochondria. Rates of organismal ageing differ across species and are theorized to be linked to somatic ROS levels. However, it is unknown whether sperm ageing rates are correlated with organismal ageing rates. Here, we investigate this question by comparing sperm ROS production in four lines of Drosophila melanogaster that have previously been shown to differ in somatic mitochondrial ROS production, including two commonly used wild-type lines and two lines with genetic modifications standardly used in ageing research. Results Somatic ROS production was previously shown to be lower in wild-type Oregon-R than in wild-type Dahomey flies; decreased by the expression of alternative oxidase (AOX), a protein that shortens the electron transport chain; and increased by a loss-of-function mutation in dj-1β, a gene involved in ROS scavenging. Contrary to predictions, we found no differences among these four lines in the rate of sperm ROS production. We discuss the implications of our results, the limitations of our study, and possible directions for future research.

scholarly journals MNB1 gene is involved in regulating the iron-deficiency stress response in Arabidopsis thaliana

2021 ◽  
Author(s):  
Hui Song ◽  
Feng Chen ◽  
Xi Wu ◽  
Min Hu ◽  
Qingliu Geng ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Arabidopsis Thaliana ◽  
Normal Growth ◽  
Developmental Changes ◽  
Fe Deficiency ◽  
Oxygen Species ◽  
Mineral Element ◽  
Wild Type ◽  
Transcription Level ◽  
Fe Uptake

Abstract Abstract Iron (Fe) is an indispensable mineral element for normal growth of plants. Fe deficiency induces a complex series of responses in plants, involving physiological and developmental changes, to increase Fe uptake from soil. However, the molecular mechanism involved in plant Fe-deficiency is not well understood. Here, we found that the MNB1 gene is involved in modulating Fe-deficiency response in Arabidopsis thaliana . The expression of MNB1 was inhabited by Fe-deficiency stress. Knockout of MNB1 led to enhanced Fe accumulation and tolerance, whereas the MNB1-overexpressing plants were sensitive to Fe-deficiency stress. Lower H 2 O 2 concentrations in mnb1 mutant plants were examined under Fe deficiency circumstances compared to wild-type. On the contray, higher H 2 O 2 concentrations were found in MNB1-overexpressing plants, which was adversely linked with malondialdehyde (MDA) concentrations. Furthermore, in mnb1 mutants, the transcription level of the Fe-uptake and translocation genes, FIT , IRT1 , FRO2 , Z IF , FRD3 , NAS4 , PYE and MYB72 , were considerably elevated during Fe-deficiency stress, resulting in higher Fe accumulation. Together, our findings show that the MNB1 gene negatively controls the Fe-deficiency response in Arabidopsis via modulating reactive oxygen species (ROS) levels and the ROS-mediated signaling pathway, thereby affecting the expression of Fe-uptake and translocation genes.

Abstract 066: Cyclooxygenase-depended Signaling Via Thromboxane Prostanoid Receptors Mediates Endothelin-i Induced Ros Generation In Mesenteric Resistance Vessels From Mice Infused With Angiotensin Ii

Hypertension ◽  
2014 ◽  
Vol 64 (suppl_1) ◽  
Author(s):  
Christopher S Wilcox ◽  
Cheng Wang ◽  
Dan Wang
Keyword(s):  
Reactive Oxygen Species ◽  
Angiotensin Ii ◽  
Ros Generation ◽  
Oxygen Species ◽  
Ang Ii ◽  
Wild Type ◽  
Prostanoid Receptors ◽  
Resistance Vessels ◽  
Cox 2 ◽  
Cox 1

Background: Angiotensin II (Ang II) increases reactive oxygen species (ROS) and contractions to thromboxane and endothelin-1 (ET-1). Therefore, we tested the hypothesis that cyclooxygenase (COX) and/or thromboxane-prostanoid receptors (TP-Rs) mediate enhanced ROS generations with ET-1 in Ang II-infused mice. Methods: ROS was assessed by urinary 8-isoprotane(8-Iso) excretion and ethedium : dihydroetheldium (DHE) in mesenteric resistance arterioles (MRAs) from wild type (+/+) and littermate COX-1 -/- or TP-R -/- mice infused with vehicle or angiotensin II (Ang II, 400 ng/kg/min for 14 days) (n=6/ group, mean ±SEM). Results: Ang II infusion increased excretion (ng/mg creatine) of TxB 2 (1.3±0.1±1.0±0.1 in COX-1 +/+ mice and 1.9±0.1 vs 1.2±0.1 in TP-R +/+ mice, all P<0.05) and 8-Iso (2.1±0.2 vs 1.4±0.1 in COX-1 +/+ mice and 2.2±0.1 vs 1.4±0.2 in TP-R +/+ mice, all P<0.05) but not in COX-1 -/- or TP-R -/- mice. Ang II enhanced ROS generation (Δunit) with 10 -7 M ET-1 in MRAs from both +/+ mouse genotypes (1.7±0.2 vs 0.1±0.1 in COX-1 +/+ mice and 3.2±0.3 vs 0.1±0.1 in TP-R +/+ mice, all P<0.01). However, this increase in ROS was fully prevented in TP-R-/- mouse vessels (0.3±0.2 vs 0.2±0.1, NS) and in COX-1 +/+ mouse vessels after combined blockade of COX-1( 10 -5 M SC-560) and -2 (paracoxib 10 -5 M) (0.2±0.1 vs 0.1±0.1, NS) and in COX-1 -/- mouse vessels after paracoxib (0.2±0.1 vs 0.2±0.2, NS). Increased ROS generation was only partially prevented in COX-1 -/- mouse vessels (0.5±0.1 vs 0.2±0.2, P<0.05) or in COX-1 +/+ mouse vessels after blockade of COX-1 ( 0.7±0.1 vs 0.1±0.1, NS) or COX-2 (1.0±0.1 vs 0.1±0.1,P<0.05). Conclusions: Increased ROS generation with ET-1 in microvessels from Ang II infused mice depends on products of both COX-1 and -2 that activate TP-Rs. Thus, combined blockade of COX-1 and -2 or TP-Rs may prevent vascular ROS and its many complications during increased Ang II and ET-1, such as hypertension, hypoxia or shock.

scholarly journals Role of mitochondrial superoxide dismutase in contraction-induced generation of reactive oxygen species in skeletal muscle extracellular space

2004 ◽  
Vol 286 (5) ◽  
pp. C1152-C1158 ◽  
Author(s):  
A. McArdle ◽  
J. van der Meulen ◽  
G. L. Close ◽  
D. Pattwell ◽  
H. Van Remmen ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Hydroxyl Radical ◽  
Hydroxyl Radicals ◽  
Extracellular Space ◽  
Superoxide Anion ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Superoxide Anions ◽  
Wild Type ◽  
Mnsod Activity

Contractions of skeletal muscles produce increases in concentrations of superoxide anions and activity of hydroxyl radicals in the extracellular space. The sources of these reactive oxygen species are not clear. We tested the hypothesis that, after a demanding isometric contraction protocol, the major source of superoxide and hydroxyl radical activity in the extracellular space of muscles is mitochondrial generation of superoxide anions and that, with a reduction in MnSOD activity, concentration of superoxide anions in the extracellular space is unchanged but concentration of hydroxyl radicals is decreased. For gastrocnemius muscles from adult (6–8 mo old) wild-type ( Sod2+/+) mice and knockout mice heterozygous for the MnSOD gene ( Sod2+/-), concentrations of superoxide anions and hydroxyl radical activity were measured in the extracellular space by microdialysis. A 15-min protocol of 180 isometric contractions induced a rapid, equivalent increase in reduction of cytochrome c as an index of superoxide anion concentrations in the extracellular space of Sod2+/+ and Sod2+/- mice, whereas hydroxyl radical activity measured by formation of 2,3-dihydroxybenzoate from salicylate increased only in the extracellular space of muscles of Sod2+/+ mice. The lack of a difference in increase in superoxide anion concentration in the extracellular space of Sod2+/+ and Sod2+/- mice after the contraction protocol supported the hypothesis that superoxide anions were not directly derived from mitochondria. In contrast, the data obtained suggest that the increase in hydroxyl radical concentration in the extracellular space of muscles from wild-type mice after the contraction protocol most likely results from degradation of hydrogen peroxide generated by MnSOD activity.

scholarly journals NADPH Oxidase-Mediated Reactive Oxygen Species Production: Subcellular Localization and Reassessment of Its Role in Plant Defense

2009 ◽  
Vol 22 (7) ◽  
pp. 868-881 ◽  
Author(s):  
Jeannine Lherminier ◽  
Taline Elmayan ◽  
Jérôme Fromentin ◽  
Khadija Tantaoui Elaraqui ◽  
Simona Vesa ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Hydrogen Peroxide ◽  
Plasma Membrane ◽  
Nadph Oxidase ◽  
Subcellular Localization ◽  
Acquired Resistance ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Wild Type ◽  
Hydrogen Peroxide Production

Chemiluminescence detection of reactive oxygen species (ROS) triggered in tobacco BY-2 cells by the fungal elicitor cryptogein was previously demonstrated to be abolished in cells transformed with an antisense construct of the plasma membrane NADPH oxidase, NtrbohD. Here, using electron microscopy, it has been confirmed that the first hydrogen peroxide production occurring a few minutes after challenge of tobacco cells with cryptogein is plasma membrane located and NtrbohD mediated. Furthermore, the presence of NtrbohD in detergent-resistant membrane fractions could be associated with the presence of NtrbohD-mediated hydrogen peroxide patches along the plasma membrane. Comparison of the subcellular localization of ROS in wild-type tobacco and in plants transformed with antisense constructs of NtrbohD revealed that this enzyme is also responsible for the hydrogen peroxide production occurring at the plasma membrane after infiltration of tobacco leaves with cryptogein. Finally, the reactivity of wild-type and transformed plants to the elicitor and their resistance against the pathogenic oomycete Phytophthora parasitica were examined. NtrbohD-mediated hydrogen peroxide production does not seem determinant for either hypersensitive response development or the establishment of acquired resistance but it is most likely involved in the signaling pathways associated with the protection of the plant cell.

scholarly journals Superoxide Dismutase Influences the Virulence of Cryptococcus neoformans by Affecting Growth within Macrophages

2003 ◽  
Vol 71 (1) ◽  
pp. 173-180 ◽  
Author(s):  
Gary M. Cox ◽  
Thomas S. Harrison ◽  
Henry C. McDade ◽  
Carlos P. Taborda ◽  
Garrett Heinrich ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Superoxide Dismutase ◽  
Cryptococcus Neoformans ◽  
Fungal Infections ◽  
Reactive Oxygen ◽  
Oxygen Species ◽  
Wild Type ◽  
Pathogenic Yeast ◽  
Antioxidant Defense Systems

ABSTRACT Superoxide dismutase (SOD) is an enzyme that converts superoxide radicals into hydrogen peroxide and molecular oxygen and has been shown to contribute to the virulence of many human-pathogenic bacteria through its ability to neutralize toxic levels of reactive oxygen species generated by the host. SOD has also been speculated to be important in the pathogenesis of fungal infections, but the role of this enzyme has not been rigorously investigated. To examine the contribution of SOD to the pathogenesis of fungal infections, we cloned the Cu,Zn SOD-encoding gene (SOD1) from the human-pathogenic yeast Cryptococcus neoformans and made mutants via targeted disruption. The sod1 mutant strains had marked decreases in SOD activity and were strikingly more susceptible to reactive oxygen species in vitro. A sod1 mutant was significantly less virulent than the wild-type strain and two independent reconstituted strains, as measured by cumulative survival in the mouse inhalational model. In vitro studies established that the sod1 strain had attenuated growth compared to the growth of the wild type and a reconstituted strain inside macrophages producing reduced amounts of nitric oxide. These findings demonstrate that (i) the Cu,Zn SOD contributes to virulence but is not required for pathogenicity in C. neoformans; (ii) the decreased virulence of the sod1 strain may be due to increased susceptibility to oxygen radicals within macrophages; and (iii) other antioxidant defense systems in C. neoformans can compensate for the loss of the Cu,Zn SOD in vivo.

scholarly journals Role of Reactive Oxygen Species during Cell Expansion in Leaves

2016 ◽  
Vol 172 (4) ◽  
pp. 2098-2106 ◽  
Author(s):  
Romy Schmidt ◽  
Alicja B. Kunkowska ◽  
Jos H.M. Schippers
Keyword(s):  
Reactive Oxygen Species ◽  
Cell Expansion ◽  
Reactive Oxygen ◽  
Oxygen Species
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