scholarly journals Rehydration of the Lichen Ramalina lacera Results in Production of Reactive Oxygen Species and Nitric Oxide and a Decrease in Antioxidants

2005 ◽  
Vol 71 (4) ◽  
pp. 2121-2129 ◽  
Author(s):  
Lior Weissman ◽  
Jacob Garty ◽  
Ayala Hochman

ABSTRACT Lichens are slow-growing associations of fungi and unicellular green algae or cyanobacteria. They are poikilohydric organisms whose lifestyle in many cases consists of alternating periods of desiccation, with low metabolic activity, and hydration, which induces increase in their metabolism. Lichens have apparently adapted to such extreme transitions between desiccation and rehydration, but the mechanisms that govern these adaptations are still poorly understood. In this study, the effect of rehydration on the production of reactive oxygen species and nitric oxide as well as low-molecular-weight antioxidants was investigated with the lichen Ramalina lacera. Rehydration of R. lacera resulted in the initiation of and a rapid increase in photosynthetic activity. Recovery of photosynthesis was accompanied by bursts of intracellular production of reactive oxygen species and nitric oxide. Laser-scanning confocal microscopy using dichlorofluorescein fluorescence revealed that formation of reactive oxygen species following rehydration was associated with both symbiotic partners of the lichen. The rate and extent of reactive oxygen species production were similar in the light and in the dark, suggesting a minor contribution of photosynthesis. Diaminofluorescein fluorescence, indicating nitric oxide formation, was detected only in fungal hyphae. Activities associated with rehydration did not have a deleterious effect on membrane integrity as assessed by measurement of electrolyte leakage, but water-soluble low-molecular-weight antioxidants decreased significantly.

2017 ◽  
Vol 5 (46) ◽  
pp. 9157-9164 ◽  
Author(s):  
Long Xu ◽  
Mingying Zhao ◽  
Yidi Yang ◽  
Yan Liang ◽  
Changzhen Sun ◽  
...  

A ROS-responsive low molecular weight hydrogel was fabricated and loaded with an anticancer drug and a photosensitizer for efficient chemo-photodynamic therapy.


2019 ◽  
Vol 7 (21) ◽  
pp. 3383-3389 ◽  
Author(s):  
Alfonso E. Garcia-Bennett ◽  
Arun Everest-Dass ◽  
Irene Moroni ◽  
Ishan Das Rastogi ◽  
Lindsay M. Parker ◽  
...  

The protein corona of nanodiamonds is dominated by low molecular weight proteins and is largely independent of surface chemistry. The pre-incubation of nanodiamonds in serum and the formation of a protein corona decrease the production of reactive oxygen species, increasing the cell viability of macrophages.


2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Krzysztof Gwozdzinski ◽  
Anna Pieniazek ◽  
Lukasz Gwozdzinski

Reactive oxygen species (ROS) released in cells are signaling molecules but can also modify signaling proteins. Red blood cells perform a major role in maintaining the balance of the redox in the blood. The main cytosolic protein of RBC is hemoglobin (Hb), which accounts for 95-97%. Most other proteins are involved in protecting the blood cell from oxidative stress. Hemoglobin is a major factor in initiating oxidative stress within the erythrocyte. RBCs can also be damaged by exogenous oxidants. Hb autoxidation leads to the generation of a superoxide radical, of which the catalyzed or spontaneous dismutation produces hydrogen peroxide. Both oxidants induce hemichrome formation, heme degradation, and release of free iron which is a catalyst for free radical reactions. To maintain the redox balance, appropriate antioxidants are present in the cytosol, such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and peroxiredoxin 2 (PRDX2), as well as low molecular weight antioxidants: glutathione, ascorbic acid, lipoic acid, α-tocopherol, β-carotene, and others. Redox imbalance leads to oxidative stress and may be associated with overproduction of ROS and/or insufficient capacity of the antioxidant system. Oxidative stress performs a key role in CKD as evidenced by the high level of markers associated with oxidative damage to proteins, lipids, and DNA in vivo. In addition to the overproduction of ROS, a reduced antioxidant capacity is observed, associated with a decrease in the activity of SOD, GPx, PRDX2, and low molecular weight antioxidants. In addition, hemodialysis is accompanied by oxidative stress in which low-biocompatibility dialysis membranes activate phagocytic cells, especially neutrophils and monocytes, leading to a respiratory burst. This review shows the production of ROS under normal conditions and CKD and its impact on disease progression. Oxidative damage to red blood cells (RBCs) in CKD and their contribution to cardiovascular disease are also discussed.


Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1180
Author(s):  
Jiunn-Woei Liaw ◽  
Chia-Yu Kuo ◽  
Shiao-Wen Tsai

The performance of quasi-spherical gold nanoparticles (GNPs) on the generation of reactive oxygen species (ROS) to cause cell damage, as irradiated by a two-photon laser, is studied. In this mechanism, hot electrons are generated from GNPs as irradiated by the two-photon laser, reacting with the molecules in the medium to produce ROS. We used laser scanning confocal microscopy with a low-fluence femtosecond Ti:Sapphire laser of 800 nm to observe the generated ROS in A431 cells, which were incubated with GNPs in advance. Subsequently, the cell morphology, cytoskeleton, and viability were investigated. In comparison with the control (no GNPs), the expression of ROS in these GNP-treated cells was enhanced after irradiation by the two-photon laser. Additionally, the disruption of cytoskeletons and the follow-up apoptosis of these GNP-treated cells are significantly increased as the number of laser shots increases. Moreover, we used N-acetyl-L-cysteine (NAC), an antioxidant, to inhibit the formation of ROS, to clarify whether the cytoskeletal disruption is caused by ROS rather than photothermal effects. Our results show that after two-photon irradiation, the ROS expression in these cells treated with GNPs plus NAC was significantly reduced. In addition, the cytoskeletal damage of these cells treated with GNPs and NAC was less than that of those treated with GNPs but without NAC; their cell viability after three days was almost the same with the control. These results illustrate that the induced ROS from the two-photon excited GNPs is the main cause of cell damage. The study may pave a way for the use of GNPs as a photosensitized therapeutic agent for two-photon photodynamic therapy on tumor treatment.


2018 ◽  
Vol 2 (10) ◽  
pp. 1866-1875 ◽  
Author(s):  
Atanu Panja ◽  
Kumaresh Ghosh

Azo and imine-based 2-naphthols 1–3 are established as low molecular weight supramolecular gelators. While gel of 1 in CH3CN : H2O (1 : 1, v/v) is responsive to Fe3+ and Cu2+ ions, under identical conditions gel of 2 is sensitive to Fe3+ ions involving gel-to-sol transition. Gel of 3 in DMSO : H2O (1 : 1 v/v) senses Fe3+ ions by exhibiting color change of the gel and also senses Fe2+ in presence of ROS.


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