Study of the luminescence in the black brittle-star Ophiocomina nigra: toward a new pattern of light emission in ophiuroids*

Zoosymposia ◽  
2012 ◽  
Vol 7 (1) ◽  
pp. 139-145 ◽  
Author(s):  
ALICE JONES ◽  
JÉRÔME MALLEFET
Keyword(s):  
Hydrogen Peroxide ◽  
Light Emission ◽  
The Body ◽  
Brittle Star ◽  
Screen Effect ◽  
English Channel ◽  
Defensive Function ◽  
Amphipholis Squamata ◽  
Weak Light ◽  
Intense Light

The black brittle star Ophiocomina nigra, common in the English Channel, is known to produce mucus when attacked. This mucus, already known for its antifouling capabilities and its role in the feeding and the locomotion behaviours of the brittle star, also emits weak light. We describe and characterize this emission of bioluminescence, thanks to a chemical triggering by hydrogen peroxide. It appears that the light emitted is 1000 times less intense than the light emitted by other brittle star species (Ophiopsila aranea and Amphipholis squamata). The luminous capabilities are homogeneously spread along the arms of the brittle star, what goes against the use of bioluminescence as a sacrificial lure. The mechanical stimu­lation of arms before chemical triggering strongly enhances the luminous capabilities of the brittle star. Luminous mucus emission can be associated with other defensive function, such as a smoke screen effect or a burglar alarm, but these two functions require intense light emissions. The fact that the luminous component is excreted outside the body might be in favour of the aposematic use of light, i.e., as a signal to warn predators of the toxicity or unpalatability of its prey.

Individual Differences in the Flexibility of Peripersonal Space

2017 ◽  
Vol 64 (1) ◽  
pp. 49-55 ◽  
Author(s):  
Samuel B. Hunley ◽  
Arwen M. Marker ◽  
Stella F. Lourenco
Keyword(s):  
Individual Differences ◽  
Peripersonal Space ◽  
The Body ◽  
Laser Pointer ◽  
Baseline Measure ◽  
Bisection Task ◽  
Defensive Function ◽  
Representational Space ◽  
Laser Condition ◽  
Line Bisection Task

Abstract. The current study investigated individual differences in the flexibility of peripersonal space (i.e., representational space near the body), specifically in relation to trait claustrophobic fear (i.e., fear of suffocating or being physically restricted). Participants completed a line bisection task with either a laser pointer (Laser condition), allowing for a baseline measure of the size of one’s peripersonal space, or a stick (Stick condition), which produces expansion of one’s peripersonal space. Our results revealed that individuals high in claustrophobic fear had larger peripersonal spaces than those lower in claustrophobic fear, replicating previous research. We also found that, whereas individuals low in claustrophobic fear demonstrated the expected expansion of peripersonal space in the Stick condition, individuals high in claustrophobic fear showed less expansion, suggesting decreased flexibility. We discuss these findings in relation to the defensive function of peripersonal space and reduced attentional flexibility associated with trait anxieties.

scholarly journals Rap1a Overlaps the AGE/RAGE Signaling Cascade to Alter Expression of α-SMA, p-NF-κB, and p-PKC-ζ in Cardiac Fibroblasts Isolated from Type 2 Diabetic Mice

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 557
Author(s):  
Stephanie D. Burr ◽  
James A. Stewart
Keyword(s):  
Oxidative Stress ◽  
Heart Failure ◽  
Hydrogen Peroxide ◽  
Cardiac Fibroblasts ◽  
The Body ◽  
Signaling Cascade ◽  
Diabetic Mice ◽  
Pkc Ζ ◽  
Type 2 Diabetic

Cardiovascular disease, specifically heart failure, is a common complication for individuals with type 2 diabetes mellitus. Heart failure can arise with stiffening of the left ventricle, which can be caused by “active” cardiac fibroblasts (i.e., myofibroblasts) remodeling the extracellular matrix (ECM). Differentiation of fibroblasts to myofibroblasts has been demonstrated to be an outcome of AGE/RAGE signaling. Hyperglycemia causes advanced glycated end products (AGEs) to accumulate within the body, and this process is greatly accelerated under chronic diabetic conditions. AGEs can bind and activate their receptor (RAGE) to trigger multiple downstream outcomes, such as altering ECM remodeling, inflammation, and oxidative stress. Previously, our lab has identified a small GTPase, Rap1a, that possibly overlaps the AGE/RAGE signaling cascade to affect the downstream outcomes. Rap1a acts as a molecular switch connecting extracellular signals to intracellular responses. Therefore, we hypothesized that Rap1a crosses the AGE/RAGE cascade to alter the expression of AGE/RAGE associated signaling proteins in cardiac fibroblasts in type 2 diabetic mice. To delineate this cascade, we used genetically different cardiac fibroblasts from non-diabetic, diabetic, non-diabetic RAGE knockout, diabetic RAGE knockout, and Rap1a knockout mice and treated them with pharmacological modifiers (exogenous AGEs, EPAC, Rap1a siRNA, and pseudosubstrate PKC-ζ). We examined changes in expression of proteins implicated as markers for myofibroblasts (α-SMA) and inflammation/oxidative stress (NF-κB and SOD-1). In addition, oxidative stress was also assessed by measuring hydrogen peroxide concentration. Our results indicated that Rap1a connects to the AGE/RAGE cascade to promote and maintain α-SMA expression in cardiac fibroblasts. Moreover, Rap1a, in conjunction with activation of the AGE/RAGE cascade, increased NF-κB expression as well as hydrogen peroxide concentration, indicating a possible oxidative stress response. Additionally, knocking down Rap1a expression resulted in an increase in SOD-1 expression suggesting that Rap1a can affect oxidative stress markers independently of the AGE/RAGE signaling cascade. These results demonstrated that Rap1a contributes to the myofibroblast population within the heart via AGE/RAGE signaling as well as promotes possible oxidative stress. This study offers a new potential therapeutic target that could possibly reduce the risk for developing diabetic cardiovascular complications attributed to AGE/RAGE signaling.

Non-linear light emission of inorganic protonic diodes, H+LEDs

2021 ◽  
Vol 9 (9) ◽  
pp. 3052-3057
Author(s):  
Jerzy J. Langer ◽  
Ewelina Frąckowiak
Keyword(s):  
Light Emission ◽  
Stimulated Raman Scattering ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Light Pulses ◽  
Optical Effects ◽  
Non Linear ◽  
Intense Light ◽  
Light Beams ◽  
Intense Light Pulses

H+LEDs are light emitting devices based on a protonic p–n junction; now with no organic polymers. The unique are non-linear optical effects: collimated light beams and stimulated Raman scattering (SRS), observed while generating intense light pulses.

Descriptive and illustrated diagnosis of Ophiuroidea fauna (Echinodermata) in the shallow waters of North-eastern Brazil

2015 ◽  
Vol 8 ◽  
Author(s):  
Fabilene Gomes Paim ◽  
Maria Cecília Guerrazzi ◽  
Michela Borges
Keyword(s):  
Brittle Star ◽  
Shallow Waters ◽  
Bottom Substrate ◽  
Eastern Brazil ◽  
North Eastern ◽  
Amphipholis Squamata ◽  
Biological Substrates ◽  
Almost All ◽  
First Time ◽  
Ophiocoma Echinata

In this study, we present descriptions, illustrations, comments, and bathymetric and geographic distributions of the brittle star species related to the estuary region of Camamu Bay, located in the State of Bahia, Brazil. The brittle star fauna lives on biological substrates, sand bottoms, mud and rubble in the Camamu Bay and comprises 12 species divided into five families. Almost all of them are common in the tropical and subtropical fauna of the regions of shallow water.Ophiophragmus filograneusis reported for the first time in Bahia, and nine other species are recorded for the first time in Camamu Bay:Amphipholis januarii, Amphipholis squamata, Ophiophragmus filograneus, Ophiostigma isocanthum,Ophioderma cinerea, Ophioderma januarii, Ophiactis lymani, Ophiactis savignyi andOphiocoma echinata.The results suggest that the ophiuroid assemblages are strongly affected by marine currents as well as by different kinds of bottom substrate.

scholarly journals Decontamination of a Diving Suit

2016 ◽  
Vol 57 (4) ◽  
pp. 45-51 ◽  
Author(s):  
Zbigniew Dąbrowiecki ◽  
Małgorzata Dąbrowiecka ◽  
Romuald Olszański ◽  
Piotr Siermontowski
Keyword(s):  
Hydrogen Peroxide ◽  
Protective Clothing ◽  
Fire Department ◽  
Gaseous Hydrogen ◽  
The Body ◽  
Night Vision ◽  
Upper Respiratory Tract ◽  
E Coli ◽  
Fabric Surface ◽  
Micro Organisms

AbstractWhen working in chemical or biological environments, contamination is an extremely dangerous issue for the rescue services of the fire department, police and the army.Modern protective overalls worn by fire fighters or dry “Viking” diving suits made from neoprene or nylon covered with polyurethane, have been proven to ensure sufficient protection. However, once the contaminated area is left, there is a need to perform decontamination of the external and internal surfaces of the protective overalls; in order to ensure the clothing continues to offer a high level of comfort and to retain the durability of said protective clothing, it is of course also necessary to perform a drying procedure.Moreover, there is a risk of a transfer of pathogenic micro-organisms between persons utilising the same protective clothes, particularly in the case of expensive specialist suits. Micro-organisms which may potentially spread through clothing include intestinal bacteria, such as: Salmonella, Shigella, Campylobacter, E. coli (including E. coli O157), C. difficile, viruses inducing infections of the upper respiratory tract and alimentary tract (noraviruses, rotaviruses, adeno and astroviruses). The risk of infection also involves the presence of the flu viruses, herpesviruses and pathogens transferred through skin, such as S. aureus (including MRSA), yeast-like fungi (Candida albicans), fungal strains inducing Tinea pedis and Tinea corporis [1]. Pathogenic micro-organisms can easily transfer from fabric surface onto the body of a person wearing protective clothing.From the numerous available techniques of decontamination of surfaces, equipment and protective clothing we propose to use for this purpose gaseous hydrogen peroxide (H2O2), a very effective biocidal agent. In field conditions, typical for the activities of rescue crews of the fire department, police and army we assume utilisation of a portable decontamination chamber enabling performance of a complete decontamination process.The process lasting approximately 3 hours encompasses 3 phases:• Drying phase;• Decontamination with gaseous hydrogen peroxide;• Catalytic combustion phase of hydrogen peroxide residues to a level safe for the environment.The integrated humidity and H2O2level sensors ensure automatic control of the entire process and the unique distribution system of gaseous H2O2secures full accessibility of the biocidal agent to the external surface of protective clothing as well as its interior. Moreover, the container allows for the conduction of the complete decontamination of the rescue equipment, night vision devices, binoculars, field telephones, radio stations, etc. Upon decontamination cycle completion, we obtain a completely dried suit which can be safely used by another crew member.

scholarly journals Peroxidase Activity of Human Hemoproteins: Keeping the Fire under Control

Molecules ◽  
2018 ◽  
Vol 23 (10) ◽  
pp. 2561 ◽  
Author(s):  
Irina Vlasova
Keyword(s):  
Hydrogen Peroxide ◽  
Peroxidase Activity ◽  
Biological Effects ◽  
Reactive Intermediates ◽  
The Body ◽  
Main Function ◽  
Hypohalous Acids ◽  
Tyrosyl Radicals ◽  
External Conditions ◽  
Structure Properties

The heme in the active center of peroxidases reacts with hydrogen peroxide to form highly reactive intermediates, which then oxidize simple substances called peroxidase substrates. Human peroxidases can be divided into two groups: (1) True peroxidases are enzymes whose main function is to generate free radicals in the peroxidase cycle and (pseudo)hypohalous acids in the halogenation cycle. The major true peroxidases are myeloperoxidase, eosinophil peroxidase and lactoperoxidase. (2) Pseudo-peroxidases perform various important functions in the body, but under the influence of external conditions they can display peroxidase-like activity. As oxidative intermediates, these peroxidases produce not only active heme compounds, but also protein-based tyrosyl radicals. Hemoglobin, myoglobin, cytochrome c/cardiolipin complexes and cytoglobin are considered as pseudo-peroxidases. Рeroxidases play an important role in innate immunity and in a number of physiologically important processes like apoptosis and cell signaling. Unfavorable excessive peroxidase activity is implicated in oxidative damage of cells and tissues, thereby initiating the variety of human diseases. Hence, regulation of peroxidase activity is of considerable importance. Since peroxidases differ in structure, properties and location, the mechanisms controlling peroxidase activity and the biological effects of peroxidase products are specific for each hemoprotein. This review summarizes the knowledge about the properties, activities, regulations and biological effects of true and pseudo-peroxidases in order to better understand the mechanisms underlying beneficial and adverse effects of this class of enzymes.

scholarly journals Hydrogen Indirectly Suppresses Increases in Hydrogen Peroxide in Cytoplasmic Hydroxyl Radical-Induced Cells and Suppresses Cellular Senescence

2019 ◽  
Vol 20 (2) ◽  
pp. 456 ◽  
Author(s):  
Takahiro Sakai ◽  
Ryosuke Kurokawa ◽  
Shin-ichi Hirano ◽  
Jun Imai
Keyword(s):  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Cellular Senescence ◽  
Physiological Role ◽  
Lipid Peroxide ◽  
Gut Bacteria ◽  
The Body ◽  
Translation Initiation Factor ◽  
Initiation Factor ◽  
Plant Fibers

Bacteria inhabiting the human gut metabolize microbiota-accessible carbohydrates (MAC) contained in plant fibers and subsequently release metabolic products. Gut bacteria produce hydrogen (H2), which scavenges the hydroxyl radical (•OH). Because H2 diffuses within the cell, it is hypothesized that H2 scavenges cytoplasmic •OH (cyto •OH) and suppresses cellular senescence. However, the mechanisms of cyto •OH-induced cellular senescence and the physiological role of gut bacteria-secreted H2 have not been elucidated. Based on the pyocyanin-stimulated cyto •OH-induced cellular senescence model, the mechanism by which cyto •OH causes cellular senescence was investigated by adding a supersaturated concentration of H2 into the cell culture medium. Cyto •OH-generated lipid peroxide caused glutathione (GSH) and heme shortage, increased hydrogen peroxide (H2O2), and induced cellular senescence via the phosphorylation of ataxia telangiectasia mutated kinase serine 1981 (p-ATMser1981)/p53 serine 15 (p-p53ser15)/p21 and phosphorylation of heme-regulated inhibitor (p-HRI)/phospho-eukaryotic translation initiation factor 2 subunit alpha serine 51 (p-eIF2α)/activating transcription factor 4 (ATF4)/p16 pathways. Further, H2 suppressed increased H2O2 by suppressing cyto •OH-mediated lipid peroxide formation and cellular senescence induction via two pathways. H2 produced by gut bacteria diffuses throughout the body to scavenge cyto •OH in cells. Therefore, it is highly likely that gut bacteria-produced H2 is involved in intracellular maintenance of the redox state, thereby suppressing cellular senescence and individual aging. Hence, H2 produced by intestinal bacteria may be involved in the suppression of aging.

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