scholarly journals Daytime eyeshine contributes to pupil camouflage in a cryptobenthic marine fish

2017 ◽  
Author(s):  
Matteo Santon ◽  
Pierre-Paul Bitton ◽  
Ulrike K. Harant ◽  
Nico K. Michiels
Keyword(s):  
Marine Fish ◽  
Teleost Fish ◽  
Pigment Epithelium ◽  
Field Measurements ◽  
Surrounding Tissue ◽  
Prey Fish ◽  
Relative Contribution ◽  
Visual Models ◽  
Dim Light ◽  
Scorpaena Porcus

ABSTRACTOcular reflectors enhance eye sensitivity in dim light, but can produce reflected eyeshine when illuminated. Most teleost fish occlude their reflectors during the day. The opposite is observed in cryptic sit-and-wait predators such as scorpionfish and toadfish, where reflectors are occluded at night and exposed during the day. This results in daytime eyeshine, proposed to enhance pupil camouflage by reducing the contrast between the otherwise black pupil and the surrounding tissue. In this study, we test this hypothesis in the scorpionfish Scorpaena porcus and show that eyeshine is the result of two mechanisms: the previously described Stratum Argenteum Reflected (SAR) eyeshine, and Pigment Epithelium Transmitted (PET) eyeshine, a newly described mechanism for this species. We confirm that the ocular reflector is exposed only when the eye is light-adapted, and present field measurements to show that eyeshine reduces pupil contrast against the iris. We then estimate the relative contribution of SAR and PET eyeshine to pupil brightness. Visual models for different light scenarios in the field show that daytime eyeshine enhances pupil camouflage from the perspective of a prey fish. We propose that the reversed occlusion mechanism of some cryptobenthic predators has evolved as a compromise between camouflage and vision.

scholarly journals LRG1 Expression Is Elevated in the Eyes of Patients with Neovascular Age-Related Macular Degeneration

2021 ◽  
Vol 22 (16) ◽  
pp. 8879
Author(s):  
Lucia Mundo ◽  
Gian Marco Tosi ◽  
Stefano Lazzi ◽  
Grazia Pertile ◽  
Barbara Parolini ◽  
...  
Keyword(s):  
Macular Degeneration ◽  
Aqueous Humor ◽  
Smooth Muscle Actin ◽  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Average Concentration ◽  
Age Related Macular Degeneration ◽  
Surrounding Tissue ◽  
Anti Vegf ◽  
Age Related

Leucine-rich a-2-glycoprotein 1 (LRG1) is a candidate therapeutic target for treating the neovascular form of age-related macular degeneration (nvAMD). In this study we examined the expression of LRG1 in eyes of nvAMD patients. Choroidal neovascular membranes (CNVMs) from patients who underwent submacular surgery for retinal pigment epithelium–choroid graft transplantation were collected from 5 nvAMD patients without any prior intravitreal anti-VEGF injection, and from six patients who received intravitreal anti-VEGF injections before surgery. As controls free of nvAMD, retina sections were obtained from the eyes resected from a patient with lacrimal sac tumor and from a patient with neuroblastoma. CNVMs were immunostained for CD34, LRG1, and α-smooth muscle actin (α-SMA). Aqueous humor samples were collected from 58 untreated-naïve nvAMD patients prior to the intravitreal injection of anti-VEGF and 51 age-matched cataract control patients, and LRG1 concentration was measured by ELISA. The level of LRG1 immunostaining is frequently high in both the endothelial cells of the blood vessels, and myofibroblasts in the surrounding tissue of CNVMs of treatment-naïve nvAMD patients. Furthermore, the average concentration of LRG1 was significantly higher in the aqueous humor of nvAMD patients than in controls. These observations provide a strong experimental basis and scientific rationale for the progression of a therapeutic anti-LRG1 monoclonal antibody into clinical trials with patients with nvAMD.

scholarly journals Spatial variations in CO<sub>2</sub> fluxes in the Saguenay Fjord (Quebec, Canada) and results of a water mixing model

2020 ◽  
Vol 17 (2) ◽  
pp. 547-566 ◽  
Author(s):  
Louise Delaigue ◽  
Helmuth Thomas ◽  
Alfonso Mucci
Keyword(s):  
Surface Waters ◽  
Brackish Water ◽  
Field Measurements ◽  
Mixing Model ◽  
Isotopic Tracers ◽  
Lawrence Estuary ◽  
Relative Contribution ◽  
Saguenay Fjord ◽  
Spring Freshet ◽  
St Lawrence Estuary

Abstract. The Saguenay Fjord is a major tributary of the St. Lawrence Estuary and is strongly stratified. A 6–8 m wedge of brackish water typically overlies up to 270 m of seawater. Relative to the St. Lawrence River, the surface waters of the Saguenay Fjord are less alkaline and host higher dissolved organic carbon (DOC) concentrations. In view of the latter, surface waters of the fjord are expected to be a net source of CO2 to the atmosphere, as they partly originate from the flushing of organic-rich soil porewaters. Nonetheless, the CO2 dynamics in the fjord are modulated with the rising tide by the intrusion, at the surface, of brackish water from the Upper St. Lawrence Estuary, as well as an overflow of mixed seawater over the shallow sill from the Lower St. Lawrence Estuary. Using geochemical and isotopic tracers, in combination with an optimization multiparameter algorithm (OMP), we determined the relative contribution of known source waters to the water column in the Saguenay Fjord, including waters that originate from the Lower St. Lawrence Estuary and replenish the fjord's deep basins. These results, when included in a conservative mixing model and compared to field measurements, serve to identify the dominant factors, other than physical mixing, such as biological activity (photosynthesis, respiration) and gas exchange at the air–water interface, that impact the water properties (e.g., pH, pCO2) of the fjord. Results indicate that the fjord's surface waters are a net source of CO2 to the atmosphere during periods of high freshwater discharge (e.g., spring freshet), whereas they serve as a net sink of atmospheric CO2 when their practical salinity exceeds ∼5–10.

scholarly journals Gadusol, an enolic derivative of cyclohexane-1,3-dione present in the roes of cod and other marine fish. Isolation, properties and occurrence compared with ascorbic acid

1981 ◽  
Vol 199 (3) ◽  
pp. 741-747 ◽  
Author(s):  
P A Plack ◽  
N W Fraser ◽  
P T Grant ◽  
C Middleton ◽  
A I Mitchell ◽  
...  
Keyword(s):  
Ascorbic Acid ◽  
Marine Fish ◽  
Teleost Fish ◽  
Gadus Morhua ◽  
Marine Teleost ◽  
Assay Procedure ◽  
Acetate Derivative ◽  
Marine Teleost Fish

Gadusol, C8H12O6, has been isolated from roes of the cod (Gadus morhua L.), i.e., ovaries that contain ripe eggs just before spawning. The concentration is about 4 g/kg dry wt. It has been identified as 1,4,5-trihydroxy-5-hydroxymethyl-2-methoxycyclo-hex-1-en-3-one and this structure was confirmed by synthesis of the anhydro tetra-acetate derivative from methyl 3,5-diacetoxy-4-methoxybenzoate. Concentrations of gadusol in the roes of other marine teleost fish examined are of the same order as in cod roes. Gadusol has some properties similar to ascorbic acid and both compounds, after oxidation, react with 2,4-dinitrophenylhydrazine in the commonly-used assay procedure for ascorbic acid. Specific assays showed that the concentrations of gadusol in the roes of marine fish are severalfold greater than those of ascorbic acid. Gadusol is structurally related to the mycosporines previously reported from a number of different organisms.

A New Fundamental Bioheat Equation for Muscle Tissue—Part II: Temperature of SAV Vessels

2001 ◽  
Vol 124 (1) ◽  
pp. 121-132 ◽  
Author(s):  
Liang Zhu ◽  
Lisa X. Xu ◽  
Qinghong He ◽  
Sheldon Weinbaum
Keyword(s):  
Source Term ◽  
Vascular Anatomy ◽  
Blood Perfusion ◽  
Surrounding Tissue ◽  
Inlet Temperature ◽  
Bioheat Equation ◽  
Temperature Variations ◽  
Relative Contribution ◽  
Branching Patterns ◽  
Vascular Branching

In this study, a new theoretical framework was developed to investigate temperature variations along countercurrent SAV blood vessels from 300 to 1000 μm diameter in skeletal muscle. Vessels of this size lie outside the range of validity of the Weinbaum-Jiji bioheat equation and, heretofore, have been treated using discrete numerical methods. A new tissue cylinder surrounding these vessel pairs is defined based on vascular anatomy, Murray’s law, and the assumption of uniform perfusion. The thermal interaction between the blood vessel pair and surrounding tissue is investigated for two vascular branching patterns, pure branching and pure perfusion. It is shown that temperature variations along these large vessel pairs strongly depend on the branching pattern and the local blood perfusion rate. The arterial supply temperature in different vessel generations was evaluated to estimate the arterial inlet temperature in the modified perfusion source term for the s vessels in Part I of this study. In addition, results from the current research enable one to explore the relative contribution of the SAV vessels and the s vessels to the overall thermal equilibration between blood and tissue.

Environmental Description in the Design of Fish Farms at Exposed Locations

2017 ◽  
Author(s):  
David Kristiansen ◽  
Vegard Aksnes ◽  
Biao Su ◽  
Pål Lader ◽  
Hans V. Bjelland
Keyword(s):  
Marine Fish ◽  
Environmental Conditions ◽  
Measurement Data ◽  
Field Measurements ◽  
Fish Farm ◽  
Fish Farms ◽  
Coastal Regions ◽  
Waves And Currents ◽  
Farm Structures

This paper addresses the description of exposure from waves and currents in coastal regions for design of marine fish farms. Representative descriptions of environmental conditions are important inputs to the design and dimensioning of reliable fish farm structures. A trend with moving production to more exposed sites and introduction of new and novel fish farm structures increase the need for more precise descriptions of the marine environment to keep control of uncertainties in design. Dedicated field measurements at two exposed aquaculture sites from February to December 2016 are presented. Results from statistical analyses of the measurement data demonstrate that common practice for characterization of exposure in design of fish farms has several deficiencies that should be improved to reduce uncertainties in design.

Studies on the eyes of gars (Lepisosteidae) with special reference to the tapetum lucidum

1973 ◽  
Vol 51 (5) ◽  
pp. 501-508 ◽  
Author(s):  
J. A. C. Nicol ◽  
H. J. Arnott
Keyword(s):  
Pigment Epithelium ◽  
Retinal Pigment ◽  
Visible Spectrum ◽  
Tapetum Lucidum ◽  
Tubular System ◽  
Noteworthy Feature ◽  
Membrane Bound ◽  
Dim Light ◽  
Ammoniacal Silver ◽  
Pigment Epithelial Cells

Eyes of gars (Lepisosteus) possess a yellow tapetum lucidum which is located in processes of the pigment epithelium. A yellow reflecting pigment is involved, enclosed in tapetal spheres each about 240 nm in diameter. Retinomotor movements take place: in darkness (or dim light) the black retinal pigment retracts, exposing the tapetum, and the rods shorten; in the light the pigment migrates inwards, obscuring the tapetum, and the rods elongate. The tapetal pigment is soluble in water, dilute acid, and alkali, and insoluble in organic solvents; it is rendered insoluble (to water) by heavy metals; and it stains with reagents used to visualize phenolic compounds (ferric–ferricyanide; ammoniacal silver nitrate). A method of extracting the pigment is described, and the ultraviolet/visible spectrum shown. The refractive index is high (n23 1.59) and that, in conjunction with the size and arrangement of the tapetal spheres, is conducive to backscatter. A second noteworthy feature of the pigment epithelial cells is the presence of an extensive Golgi apparatus consisting of many dictyosomes interconnected by a complicated tubular system of smooth membranes. The tubules exhibit periodic swellings or vesiculations in which the tapetal spheres individually are formed. Comparisons are made with a similar Golgi complex in Styela, and with membrane-bound vesicles, derived from Golgi and concerned with formation of ommochrome granules, in Drosophila.

Pontobdella muricata and Trachelobdella lubrica (Hirudinea: Piscicolidae) on some marine fish in the Dardanelles, Turkey

2003 ◽  
Vol 83 (6) ◽  
pp. 1315-1316 ◽  
Author(s):  
Naim Saglam ◽  
Mehmet Cemal Oguz ◽  
Ekrem Sanver Celik ◽  
Seydi Ali Doyuk ◽  
Ahmet Usta
Keyword(s):  
Marine Fish ◽  
Fish Species ◽  
Marine Fish Species ◽  
Torpedo Marmorata ◽  
Raja Clavata ◽  
Scorpaena Scrofa ◽  
Scorpaena Porcus

Fifteen individuals of four marine fish species (Torpedo marmorata, Raja clavata, Scorpaena porcus and Scorpaena scrofa) caught in the Dardanelles, Turkey, were examined for the leech Pontobdella muricata and Trachelobdella lubrica; 18 P. muricata and 23 T. lubrica were found on gills, at the base of the fins, and abdomen on 14 of the 15 fish.

scholarly journals Urine patch size and nitrogen load: effects on nitrogen uptake from the urine patch in plantain and ryegrass/white clover pastures

2018 ◽  
pp. 195-200
Author(s):  
Mark A Shepherd ◽  
Bill T Carlson
Keyword(s):  
Perennial Ryegrass ◽  
White Clover ◽  
Patch Size ◽  
Field Measurements ◽  
N Leaching ◽  
Relative Contribution ◽  
Load Effects ◽  
Urine Patch ◽  
Model Improvement ◽  
Wetted Area

Field measurements from micro-plots (0.20 - 0.36 m2) of perennial ryegrass/white clover and of pure plantain were used to mimic a urine patch (UP) and to test the effects of UP nitrogen (N) load and size on pasture N offtake. Urine N offtake was greater with plantain than with standard pasture; however, the relative contribution to uptake from the wetted area and surrounding edge was the same for both species. Most (>90%) of the apparent offtake of urine N by plantain and standard pastures was within 20 cm of the edge of the UP. For the two urine patch sizes tested, edge contribution to urine N offtake was on average about 30% of the total from the UP, but was higher for at 600 kg N/ha urine N (45%) than at 300 kg N/ha (18%). Understanding this edge contribution is important for model improvement, and for the development of mitigations to decrease N leaching.

scholarly journals To fear or to feed: the effects of turbidity on perception of risk by a marine fish

2011 ◽  
Vol 7 (6) ◽  
pp. 811-813 ◽  
Author(s):  
Susannah M. Leahy ◽  
Mark I. McCormick ◽  
Matthew D. Mitchell ◽  
Maud C. O. Ferrari
Keyword(s):  
Marine Fish ◽  
Visual Information ◽  
Primary Sources ◽  
Human Populations ◽  
Activity Levels ◽  
Sources Of Information ◽  
Prey Fish ◽  
Baseline Activity ◽  
Antipredator Responses ◽  
High Turbidity

Coral reefs are currently experiencing a number of worsening anthropogenic stressors, with nearshore reefs suffering from increasing sedimentation because of growing human populations and development in coastal regions. In habitats where vision and olfaction serve as the primary sources of information, reduced visual input from suspended sediment may lead to significant alterations in prey fish behaviour. Here, we test whether prey compensate for reduced visual information by increasing their antipredator responses to chemically mediated risk cues in turbid conditions. Experiments with the spiny damselfish, Acanthochromis polyacanthus , found that baseline activity levels were reduced by 23 per cent in high turbidity conditions relative to low turbidity conditions. Furthermore, risk cues elicited strong antipredator responses at all turbidity levels; the strongest antipredator responses were observed in high turbidity conditions, with fish reducing their foraging by almost 40 per cent, as compared with 17 per cent for fish in clear conditions. This provides unambiguous evidence of sensory compensation in a predation context for a tropical marine fish, and suggests that prey fish may be able to behaviourally offset some of the fitness reductions resulting from anthropogenic sedimentation of their habitats.

scholarly journals Spatial variations of CO<sub>2</sub> fluxes in the Saguenay Fjord (Québec, Canada) and results of a water mixing model

2019 ◽  
Author(s):  
Louise Delaigue ◽  
Helmuth Thomas ◽  
Alfonso Mucci
Keyword(s):  
Surface Waters ◽  
Brackish Water ◽  
Field Measurements ◽  
Mixing Model ◽  
Isotopic Tracers ◽  
Lawrence Estuary ◽  
Relative Contribution ◽  
Saguenay Fjord ◽  
Spring Freshet ◽  
St Lawrence Estuary

Abstract. The Saguenay Fjord is a major tributary of the St. Lawrence Estuary and is strongly stratified. A 6–8 m wedge of brackish water typically overlies up to 270 m of seawater. Relative to the St. Lawrence River, the surface waters of the Saguenay Fjord are less alkaline and host higher dissolved organic carbon (DOC) concentrations. In view of the latter, surface waters of the fjord are expected to be a net source of CO2 to the atmosphere, as they partly originate from the flushing of organic-rich soil porewaters. Nonetheless, the intrusion, at the surface, of brackish water from the upper estuary with the rising tide, as well as mixing of seawater, overflowing the sill from the lower estuary, modulate the CO2 dynamics in the fjord. Using geochemical and isotopic tracers, in combination with an optimization multiparameter algorithm (OMP), we determined the relative contribution of known source-waters to the water column in the Saguenay Fjord, including waters that originate from the Lower St. Lawrence Estuary and replenish the fjord’s deep basins. These results, when combined to a conservative mixing model and compared to field measurements, serve to identify the dominant factors, other than physical mixing, such as biological activity (photosynthesis, respiration) and gas exchange at the air-water interface, that impact the water properties (e.g., pH, pCO2) of the fjord. Results indicate that the fjord’s surface waters are a net source of CO2 to the atmosphere during periods of high freshwater discharge (e.g., spring freshet) whereas they serve as a net sink of atmospheric CO2 when their practical salinity exceeds ~ 5–10.

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