Photosensitive proteins expressed in the CONE PHOTORECEPTOR CELLS. They are the protein components of cone photopigments. Cone opsins are classified by their peak absorption wavelengths.
Photosensitive proteins in the membranes of PHOTORECEPTOR CELLS such as the rods and the cones. Opsins have varied light absorption properties and are members of the G-PROTEIN-COUPLED RECEPTORS family. Their ligands are VITAMIN A-based chromophores.
Photosensitive proteins expressed in the ROD PHOTORECEPTOR CELLS. They are the protein components of rod photoreceptor pigments such as RHODOPSIN.
Photosensitive afferent neurons located primarily within the FOVEA CENTRALIS of the MACULA LUTEA. There are three major types of cone cells (red, blue, and green) whose photopigments have different spectral sensitivity curves. Retinal cone cells operate in daylight vision (at photopic intensities) providing color recognition and central visual acuity.
Phenomena and pharmaceutics of compounds that bind to the same receptor binding-site as an agonist (DRUG AGONISM) for that receptor but exerts the opposite pharmacological effect.
Photosensitive afferent neurons located in the peripheral retina, with their density increases radially away from the FOVEA CENTRALIS. Being much more sensitive to light than the RETINAL CONE CELLS, the rod cells are responsible for twilight vision (at scotopic intensities) as well as peripheral vision, but provide no color discrimination.
Specialized PHOTOTRANSDUCTION neurons in the vertebrates, such as the RETINAL ROD CELLS and the RETINAL CONE CELLS. Non-visual photoreceptor neurons have been reported in the deep brain, the PINEAL GLAND and organs of the circadian system.
A heterotrimeric GTP-binding protein that mediates the light activation signal from photolyzed rhodopsin to cyclic GMP phosphodiesterase and is pivotal in the visual excitation process. Activation of rhodopsin on the outer membrane of rod and cone cells causes GTP to bind to transducin followed by dissociation of the alpha subunit-GTP complex from the beta/gamma subunits of transducin. The alpha subunit-GTP complex activates the cyclic GMP phosphodiesterase which catalyzes the hydrolysis of cyclic GMP to 5'-GMP. This leads to closure of the sodium and calcium channels and therefore hyperpolarization of the rod cells. EC 3.6.1.-.
A carotenoid constituent of visual pigments. It is the oxidized form of retinol which functions as the active component of the visual cycle. It is bound to the protein opsin forming the complex rhodopsin. When stimulated by visible light, the retinal component of the rhodopsin complex undergoes isomerization at the 11-position of the double bond to the cis-form; this is reversed in "dark" reactions to return to the native trans-configuration.
Enzymes that catalyze the rearrangement of geometry about double bonds. EC 5.2.
The process in which light signals are transformed by the PHOTORECEPTOR CELLS into electrical signals which can then be transmitted to the brain.
Photosensitive protein complexes of varied light absorption properties which are expressed in the PHOTORECEPTOR CELLS. They are OPSINS conjugated with VITAMIN A-based chromophores. Chromophores capture photons of light, leading to the activation of opsins and a biochemical cascade that ultimately excites the photoreceptor cells.
A purplish-red, light-sensitive pigment found in RETINAL ROD CELLS of most vertebrates. It is a complex consisting of a molecule of ROD OPSIN and a molecule of 11-cis retinal (RETINALDEHYDE). Rhodopsin exhibits peak absorption wavelength at about 500 nm.
Bulbous enlargement of the growing tip of nerve axons and dendrites. They are crucial to neuronal development because of their pathfinding ability and their role in synaptogenesis.
The ten-layered nervous tissue membrane of the eye. It is continuous with the OPTIC NERVE and receives images of external objects and transmits visual impulses to the brain. Its outer surface is in contact with the CHOROID and the inner surface with the VITREOUS BODY. The outer-most layer is pigmented, whereas the inner nine layers are transparent.
'Eye proteins' are structural or functional proteins, such as crystallins, opsins, and collagens, located in various parts of the eye, including the cornea, lens, retina, and aqueous humor, that contribute to maintaining transparency, refractive power, phototransduction, and overall integrity of the visual system.
Analytical technique for studying substances present at enzyme concentrations in single cells, in situ, by measuring light absorption. Light from a tungsten strip lamp or xenon arc dispersed by a grating monochromator illuminates the optical system of a microscope. The absorbance of light is measured (in nanometers) by comparing the difference between the image of the sample and a reference image.
The conversion of absorbed light energy into molecular signals.
Specialized cells that detect and transduce light. They are classified into two types based on their light reception structure, the ciliary photoreceptors and the rhabdomeric photoreceptors with MICROVILLI. Ciliary photoreceptor cells use OPSINS that activate a PHOSPHODIESTERASE phosphodiesterase cascade. Rhabdomeric photoreceptor cells use opsins that activate a PHOSPHOLIPASE C cascade.
Function of the human eye that is used in bright illumination or in daylight (at photopic intensities). Photopic vision is performed by the three types of RETINAL CONE PHOTORECEPTORS with varied peak absorption wavelengths in the color spectrum (from violet to red, 400 - 700 nm).
Light sensory organ in ARTHROPODS consisting of a large number of ommatidia, each functioning as an independent photoreceptor unit.
Adjustment of the eyes under conditions of low light. The sensitivity of the eye to light is increased during dark adaptation.
Recording of electric potentials in the retina after stimulation by light.
A class in the phylum CNIDARIA which alternates between polyp and medusa forms during their life cycle. There are over 2700 species in five orders.
The relationships of groups of organisms as reflected by their genetic makeup.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
Specialized cells in the invertebrates that detect and transduce light. They are predominantly rhabdomeric with an array of photosensitive microvilli. Illumination depolarizes invertebrate photoreceptors by stimulating Na+ influx across the plasma membrane.
Constriction of the pupil in response to light stimulation of the retina. It refers also to any reflex involving the iris, with resultant alteration of the diameter of the pupil. (Cline et al., Dictionary of Visual Science, 4th ed)
Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)
A phylum of primitive invertebrate animals that exemplify a simple body organization. Trichoplax adhaerens is considered a key species for early metazoan evolution.
A genus of GREEN ALGAE in the family Volvocaceae. They form spherical colonies of hundreds or thousands of bi-flagellated cells in a semi-transparent gelatinous ball.
The function of the eye that is used in the intermediate level of illumination (mesopic intensities) where both the RETINAL ROD PHOTORECEPTORS and the RETINAL CONE PHOTORECEPTORS are active in processing light input simultaneously.

Adaptive evolution of cone opsin genes in two colorful cyprinids, Opsariichthys pachycephalus and Candidia barbatus. (1/56)


Retarded developmental expression and patterning of retinal cone opsins in hypothyroid mice. (2/56)


Cone inputs to murine striate cortex. (3/56)


Topographical characterization of cone photoreceptors and the area centralis of the canine retina. (4/56)

PURPOSE: The canine is an important large animal model of human retinal genetic disorders. Studies of ganglion cell distribution in the canine retina have identified a visual streak of high density superior to the optic disc with a temporal area of peak density known as the area centralis. The topography of cone photoreceptors in the canine retina has not been characterized in detail, and in contrast to the macula in humans, the position of the area centralis in dogs is not apparent on clinical funduscopic examination. The purpose of this study was to define the location of the area centralis in the dog and to characterize in detail the topography of rod and cone photoreceptors within the area centralis. This will facilitate the investigation and treatment of retinal disease in the canine. METHODS: We used peanut agglutinin, which labels cone matrix sheaths and antibodies against long/medium wavelength (L/M)- and short wavelength (S)-cone opsins, to stain retinal cryosections and flatmounts from beagle dogs. Retinas were imaged using differential interference contrast imaging, fluorescence, and confocal microscopy. Within the area centralis, rod and cone size and density were quantified, and the proportion of cones expressing each cone opsin subtype was calculated. Using a grid pattern of sampling in 9 retinal flatmounts, we investigated the distribution of cones throughout the retina to predict the location of the area centralis. RESULTS: We identified the area centralis as the site of maximal density of rod and cone photoreceptor cells, which have a smaller inner segment cross-sectional area in this region. L/M opsin was expressed by the majority of cones in the retina, both within the area centralis and in the peripheral retina. Using the mean of cone density distribution from 9 retinas, we calculated that the area centralis is likely to be centered at a point 1.5 mm temporal and 0.6 mm superior to the optic disc. For clinical funduscopic examination, this represents 1.2 disc diameters temporal and 0.4 disc diameters superior to the optic disc. CONCLUSIONS: We have described the distribution of rods and cone subtypes within the canine retina and calculated a predictable location for the area centralis. These findings will facilitate the characterization and treatment of cone photoreceptor dystrophies in the dog.  (+info)

In conditions of limited chromophore supply rods entrap 11-cis-retinal leading to loss of cone function and cell death. (5/56)


Thyroid hormone induces a time-dependent opsin switch in the retina of salmonid fishes. (6/56)


Physiology and morphology of color-opponent ganglion cells in a retina expressing a dual gradient of S and M opsins. (7/56)


The action of 11-cis-retinol on cone opsins and intact cone photoreceptors. (8/56)


Cone opsins are a type of photopigment protein found in the cone cells of the retina, which are responsible for color vision. There are three types of cone opsins in humans, each sensitive to different wavelengths of light: short-wavelength (S) sensitive cone opsin (also known as blue cone opsin), medium-wavelength (M) sensitive cone opsin (also known as green cone opsin), and long-wavelength (L) sensitive cone opsin (also known as red cone opsin).

These cone opsins are activated by light, which triggers a chemical reaction that sends signals to the brain and enables us to perceive color. Differences in the genes that code for these cone opsins can result in variations in color perception and can contribute to individual differences in color vision. Certain genetic mutations can also lead to various forms of color blindness, including red-green color blindness and blue-yellow color blindness.

Opsins are a type of protein that are sensitive to light and play a crucial role in vision. They are found in the photoreceptor cells of the retina, which are the specialized cells in the eye that detect light. Opsins are activated by light, which triggers a series of chemical reactions that ultimately result in the transmission of a signal to the brain, allowing us to see.

There are several different types of opsins, including rhodopsin and the cone pigments, which are found in the rods and cones of the retina, respectively. Rhodopsin is responsible for dim-light vision, while the cone pigments are involved in color vision and bright-light vision.

Opsins belong to a larger family of proteins called G protein-coupled receptors (GPCRs), which are involved in many different physiological processes in the body. In addition to their role in vision, opsins have also been found to be involved in other light-dependent processes, such as the regulation of circadian rhythms and the entrainment of the biological clock.

Rhodopsin, also known as visual purple, is a light-sensitive protein found in the rods of the eye's retina. It is a type of opsin, a class of proteins that are activated by light and play a crucial role in vision. Rhodopsin is composed of two parts: an apoprotein called opsin and a chromophore called 11-cis-retinal. When light hits the retina, it changes the shape of the 11-cis-retinal, which in turn activates the rhodopsin protein. This activation triggers a series of chemical reactions that ultimately lead to the transmission of a visual signal to the brain. Rhodopsin is highly sensitive to light and allows for vision in low-light conditions.

Retinal cone photoreceptor cells are specialized neurons located in the retina of the eye, responsible for visual phototransduction and color vision. They are one of the two types of photoreceptors, with the other being rods, which are more sensitive to low light levels. Cones are primarily responsible for high-acuity, color vision during daylight or bright-light conditions.

There are three types of cone cells, each containing different photopigments that absorb light at distinct wavelengths: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red light, respectively. The combination of signals from these three types of cones allows the human visual system to perceive a wide range of colors and discriminate between them. Cones are densely packed in the central region of the retina, known as the fovea, which provides the highest visual acuity.

Drug inverse agonism is a property of certain drugs that can bind to and stabilize the inactive conformation of a G protein-coupled receptor (GPCR) or other type of receptor. This results in a reduction of the receptor's basal activity, which is the level of signaling that occurs in the absence of an agonist ligand.

An inverse agonist drug can have the opposite effect of an agonist drug, which binds to and stabilizes the active conformation of a receptor and increases its signaling activity. An inverse agonist drug can also have a greater effect than a simple antagonist drug, which binds to a receptor without activating or inhibiting it but rather prevents other ligands from binding.

Inverse agonism is an important concept in pharmacology and has implications for the development of drugs that target GPCRs and other types of receptors. For example, inverse agonist drugs have been developed to treat certain conditions such as anxiety disorders, where reducing the basal activity of a particular receptor may be beneficial.

Retinal rod photoreceptor cells are specialized neurons in the retina of the eye that are primarily responsible for vision in low light conditions. They contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a single photon of light. This triggers a cascade of biochemical reactions that ultimately leads to the generation of electrical signals, which are then transmitted to the brain via the optic nerve.

Rod cells do not provide color vision or fine detail, but they allow us to detect motion and see in dim light. They are more sensitive to light than cone cells, which are responsible for color vision and detailed sight in bright light conditions. Rod cells are concentrated at the outer edges of the retina, forming a crescent-shaped region called the peripheral retina, with fewer rod cells located in the central region of the retina known as the fovea.

Photoreceptor cells in vertebrates are specialized types of neurons located in the retina of the eye that are responsible for converting light stimuli into electrical signals. These cells are primarily responsible for the initial process of vision and have two main types: rods and cones.

Rods are more numerous and are responsible for low-light vision or scotopic vision, enabling us to see in dimly lit conditions. They do not contribute to color vision but provide information about the shape and movement of objects.

Cones, on the other hand, are less numerous and are responsible for color vision and high-acuity vision or photopic vision. There are three types of cones, each sensitive to different wavelengths of light: short (S), medium (M), and long (L) wavelengths, which correspond to blue, green, and red, respectively. The combination of signals from these three types of cones allows us to perceive a wide range of colors.

Both rods and cones contain photopigments that consist of a protein called opsin and a light-sensitive chromophore called retinal. When light hits the photopigment, it triggers a series of chemical reactions that ultimately lead to the generation of an electrical signal that is transmitted to the brain via the optic nerve. This process enables us to see and perceive our visual world.

Transducin is a G protein found in the rod cells of the retina and plays a crucial role in the visual signal transduction pathway. It is responsible for converting the light-induced isomerization of rhodopsin into a biochemical signal, which ultimately leads to the activation of downstream effectors and the generation of a neural response.

Transducin has three subunits: alpha (Tα), beta (Tβ), and gamma (Tγ). When light activates rhodopsin, it interacts with the Tα subunit, causing it to exchange GDP for GTP and dissociate from the Tβγ complex. The activated Tα then interacts with a downstream effector called phosphodiesterase (PDE), which leads to the hydrolysis of cGMP and the closure of cGMP-gated ion channels in the plasma membrane. This results in the hyperpolarization of the rod cell, which is the initial step in the visual signal transduction pathway.

Overall, transducin is a key player in the conversion of light energy into neural signals, allowing us to see and perceive our visual world.

Retinaldehyde, also known as retinal, is a form of vitamin A that is essential for vision. It is the aldehyde form of retinol (vitamin A alcohol) and is involved in the visual cycle, where it plays a crucial role in the process of converting light into electrical signals that are sent to the brain.

When light hits the retina, it activates a protein called rhodopsin, which contains retinaldehyde as one of its components. This activation causes a chemical change in retinaldehyde, leading to the generation of an electrical signal that is transmitted to the brain via the optic nerve.

Retinaldehyde is also involved in other physiological processes, including the regulation of gene expression and cell growth and differentiation. It can be synthesized in the body from beta-carotene, a pigment found in fruits and vegetables, or obtained directly from animal sources such as liver, fish liver oil, and dairy products.

Cis-trans isomeres are molecules that have the same molecular formula and skeletal structure, but differ in the arrangement of their atoms around a double bond. In a cis isomer, the two larger groups or atoms are on the same side of the double bond, while in a trans isomer, they are on opposite sides.

Cis-trans isomerases are enzymes that catalyze the interconversion between cis and trans isomers of various molecules, such as fatty acids, steroids, and retinals. These enzymes play important roles in various biological processes, including membrane fluidity, vision, and the biosynthesis of hormones and other signaling molecules.

Examples of cis-trans isomerases include:

* Fatty acid desaturases, which introduce double bonds into fatty acids and can convert trans isomers to cis isomers
* Retinal isomerases, which interconvert the cis and trans isomers of retinal, a molecule involved in vision
* Steroid isomerases, which catalyze the interconversion of various steroids, including cholesterol and its derivatives.

Ocular vision refers to the ability to process and interpret visual information that is received by the eyes. This includes the ability to see clearly and make sense of the shapes, colors, and movements of objects in the environment. The ocular system, which includes the eye and related structures such as the optic nerve and visual cortex of the brain, works together to enable vision.

There are several components of ocular vision, including:

* Visual acuity: the clarity or sharpness of vision
* Field of vision: the extent of the visual world that is visible at any given moment
* Color vision: the ability to distinguish different colors
* Depth perception: the ability to judge the distance of objects in three-dimensional space
* Contrast sensitivity: the ability to distinguish an object from its background based on differences in contrast

Disorders of ocular vision can include refractive errors such as nearsightedness or farsightedness, as well as more serious conditions such as cataracts, glaucoma, and macular degeneration. These conditions can affect one or more aspects of ocular vision and may require medical treatment to prevent further vision loss.

Retinal pigments refer to the light-sensitive chemicals found in the retina, specifically within the photoreceptor cells called rods and cones. The main types of retinal pigments are rhodopsin (also known as visual purple) in rods and iodopsins in cones. These pigments play a crucial role in the process of vision by absorbing light and initiating a series of chemical reactions that ultimately trigger nerve impulses, which are then transmitted to the brain and interpreted as visual images. Rhodopsin is more sensitive to lower light levels and is responsible for night vision, while iodopsins are sensitive to specific wavelengths of light and contribute to color vision.

Rhodopsin, also known as visual purple, is a light-sensitive pigment found in the rods of the vertebrate retina. It is a complex protein molecule made up of two major components: an opsin protein and retinal, a form of vitamin A. When light hits the retinal in rhodopsin, it changes shape, which initiates a series of chemical reactions leading to the activation of the visual pathway and ultimately results in vision. This process is known as phototransduction. Rhodopsin plays a crucial role in low-light vision or scotopic vision.

Growth cones are specialized structures found at the tips of growing neurites (axons and dendrites) during the development and regeneration of the nervous system. They were first described by Santiago Ramón y Cajal in the late 19th century. Growth cones play a crucial role in the process of neurogenesis, guiding the extension and pathfinding of axons to their appropriate targets through a dynamic interplay with environmental cues. These cues include various guidance molecules, such as netrins, semaphorins, ephrins, and slits, which bind to receptors on the growth cone membrane and trigger intracellular signaling cascades that ultimately determine the direction of axonal outgrowth.

Morphologically, a growth cone consists of three main parts: the central domain (or "C-domain"), the peripheral domain (or "P-domain"), and the transition zone connecting them. The C-domain contains microtubules and neurofilaments, which provide structural support and transport materials to the growing neurite. The P-domain is rich in actin filaments and contains numerous membrane protrusions called filopodia and lamellipodia, which explore the environment for guidance cues and facilitate motility.

The dynamic behavior of growth cones allows them to navigate complex environments, make decisions at choice points, and ultimately form precise neural circuits during development. Understanding the mechanisms that regulate growth cone function is essential for developing strategies to promote neural repair and regeneration in various neurological disorders and injuries.

The retina is the innermost, light-sensitive layer of tissue in the eye of many vertebrates and some cephalopods. It receives light that has been focused by the cornea and lens, converts it into neural signals, and sends these to the brain via the optic nerve. The retina contains several types of photoreceptor cells including rods (which handle vision in low light) and cones (which are active in bright light and are capable of color vision).

In medical terms, any pathological changes or diseases affecting the retinal structure and function can lead to visual impairment or blindness. Examples include age-related macular degeneration, diabetic retinopathy, retinal detachment, and retinitis pigmentosa among others.

Eye proteins, also known as ocular proteins, are specific proteins that are found within the eye and play crucial roles in maintaining proper eye function and health. These proteins can be found in various parts of the eye, including the cornea, iris, lens, retina, and other structures. They perform a wide range of functions, such as:

1. Structural support: Proteins like collagen and elastin provide strength and flexibility to the eye's tissues, enabling them to maintain their shape and withstand mechanical stress.
2. Light absorption and transmission: Proteins like opsins and crystallins are involved in capturing and transmitting light signals within the eye, which is essential for vision.
3. Protection against damage: Some eye proteins, such as antioxidant enzymes and heat shock proteins, help protect the eye from oxidative stress, UV radiation, and other environmental factors that can cause damage.
4. Regulation of eye growth and development: Various growth factors and signaling molecules, which are protein-based, contribute to the proper growth, differentiation, and maintenance of eye tissues during embryonic development and throughout adulthood.
5. Immune defense: Proteins involved in the immune response, such as complement components and immunoglobulins, help protect the eye from infection and inflammation.
6. Maintenance of transparency: Crystallin proteins in the lens maintain its transparency, allowing light to pass through unobstructed for clear vision.
7. Neuroprotection: Certain eye proteins, like brain-derived neurotrophic factor (BDNF), support the survival and function of neurons within the retina, helping to preserve vision.

Dysfunction or damage to these eye proteins can contribute to various eye disorders and diseases, such as cataracts, age-related macular degeneration, glaucoma, diabetic retinopathy, and others.

Microspectrophotometry (MSP) is a microanalytical technique that combines microspectroscopy and photometry to measure the absorption, reflection, or fluorescence spectra of extremely small samples, typically in the range of micrometers to sub-micrometers. This technique is often used in biomedical research and clinical settings for the analysis of cellular and subcellular structures, such as organelles, inclusion bodies, and single molecules.

MSP can provide detailed information about the chemical composition, molecular structure, and spatial distribution of biological samples, making it a valuable tool for studying various physiological and pathological processes, including gene expression, protein function, and cell-cell interactions. Additionally, MSP has been used in diagnostic applications to identify abnormalities in tissues and cells, such as cancerous or precancerous lesions, and to monitor the efficacy of therapeutic interventions.

The technique involves using a microscope equipped with a high-resolution objective lens and a spectrophotometer to measure the intensity of light transmitted through or reflected from a sample at different wavelengths. The resulting spectra can be used to identify specific chemical components or molecular structures based on their characteristic absorption, reflection, or fluorescence patterns.

MSP is a powerful tool for studying biological systems at the microscopic level and has contributed significantly to our understanding of cellular and molecular biology. However, it requires specialized equipment and expertise to perform and interpret the data, making it a relatively complex and sophisticated technique.

Light signal transduction is a biological process that refers to the way in which cells convert light signals into chemical or electrical responses. This process typically involves several components, including a light-sensitive receptor (such as a photopigment), a signaling molecule (like a G-protein or calcium ion), and an effector protein that triggers a downstream response.

In the visual system, for example, light enters the eye and activates photoreceptor cells in the retina. These cells contain a light-sensitive pigment called rhodopsin, which undergoes a chemical change when struck by a photon of light. This change triggers a cascade of signaling events that ultimately lead to the transmission of visual information to the brain.

Light signal transduction is also involved in other biological processes, such as the regulation of circadian rhythms and the synthesis of vitamin D. In these cases, specialized cells contain light-sensitive receptors that allow them to detect changes in ambient light levels and adjust their physiology accordingly.

Overall, light signal transduction is a critical mechanism by which organisms are able to sense and respond to their environment.

Photoreceptor cells are specialized neurons in the retina of the eye that convert light into electrical signals. These cells consist of two types: rods and cones. Rods are responsible for vision at low light levels and provide black-and-white, peripheral, and motion sensitivity. Cones are active at higher light levels and are capable of color discrimination and fine detail vision. Both types of photoreceptor cells contain light-sensitive pigments that undergo chemical changes when exposed to light, triggering a series of electrical signals that ultimately reach the brain and contribute to visual perception.

Color vision is the ability to perceive and differentiate colors, which is a result of the way that our eyes and brain process different wavelengths of light. In the eye, there are two types of photoreceptor cells called rods and cones. While rods are more sensitive to low levels of light and help us see in dim conditions, cones are responsible for color vision.

There are three types of cone cells in the human eye, each containing a different type of pigment that is sensitive to specific wavelengths of light. One type of cone cell is most sensitive to short wavelengths (blue light), another is most sensitive to medium wavelengths (green light), and the third is most sensitive to long wavelengths (red light). When light enters the eye, it is absorbed by these pigments in the cones, which then send signals to the brain. The brain interprets these signals and translates them into the perception of color.

People with normal color vision can distinguish between millions of different colors based on the specific combinations of wavelengths that are present in a given scene. However, some people have deficiencies or abnormalities in their color vision, which can make it difficult or impossible to distinguish between certain colors. These conditions are known as color vision deficiencies or color blindness.

A compound eye is a characteristic type of eye found in arthropods, including insects, crustaceans, and some extinct fossil groups. Each eye is composed of numerous individual photoreceptor units called ommatidia, which function together to provide a wide field of vision and excellent motion detection capabilities.

In an arthropod compound eye, each ommatidium contains a group of visual cells (called retinula cells) surrounding a central rhabdomere, which is the light-sensitive structure that converts light into electrical signals. The number of ommatidia in a compound eye can vary greatly between species and even within different regions of an individual's eye, ranging from just a few to tens of thousands.

Compound eyes offer several advantages for arthropods:

1. Wide Field of Vision: Compound eyes provide a panoramic view of the environment, allowing arthropods to detect predators, prey, or mates from various directions simultaneously.
2. Motion Detection: The apposition-type compound eye (one type of compound eye structure) is particularly adept at detecting motion due to the neural processing of signals between adjacent ommatidia. This allows arthropods to respond quickly to potential threats or opportunities.
3. Light Adaptation: Compound eyes can adapt to different light conditions, allowing arthropods to function effectively in both bright daylight and dimly lit environments. Some species have specialized regions within their compound eyes that are optimized for specific light conditions, such as the dorsal rim area in insects, which is sensitive to polarized skylight.
4. UV Sensitivity: Many arthropods can detect ultraviolet (UV) light due to the presence of photopigments within their ommatidia that absorb UV wavelengths. This ability allows them to perceive patterns and cues in their environment that are invisible to humans, such as floral guides in bees or mate-recognition signals in certain insects.

Despite their limitations in terms of resolution and image quality compared to vertebrate eyes, compound eyes have evolved to serve the unique needs and ecological roles of arthropods effectively.

Dark adaptation is the process by which the eyes adjust to low levels of light. This process allows the eyes to become more sensitive to light and see better in the dark. It involves the dilation of the pupils, as well as chemical changes in the rods and cones (photoreceptor cells) of the retina. These changes allow the eye to detect even small amounts of light and improve visual acuity in low-light conditions. Dark adaptation typically takes several minutes to occur fully, but can be faster or slower depending on various factors such as age, prior exposure to light, and certain medical conditions. It is an important process for maintaining good vision in a variety of lighting conditions.

Electroretinography (ERG) is a medical test used to evaluate the functioning of the retina, which is the light-sensitive tissue located at the back of the eye. The test measures the electrical responses of the retina to light stimulation.

During the procedure, a special contact lens or electrode is placed on the surface of the eye to record the electrical activity generated by the retina's light-sensitive cells (rods and cones) and other cells in the retina. The test typically involves presenting different levels of flashes of light to the eye while the electrical responses are recorded.

The resulting ERG waveform provides information about the overall health and function of the retina, including the condition of the photoreceptors, the integrity of the inner retinal layers, and the health of the retinal ganglion cells. This test is often used to diagnose and monitor various retinal disorders, such as retinitis pigmentosa, macular degeneration, and diabetic retinopathy.

Hydrozoa is a class of predominantly marine, simple aquatic animals in the phylum Cnidaria. They are characterized by having a polyp form, which is typically colonial and sessile, and a medusa form, which is usually free-swimming and solitary. The polyp stage is often modular, with individual polyps being connected by stolons to form colonies. Hydrozoans have specialized cells called cnidocytes that contain stinging organelles called nematocysts, which they use for capturing prey and defense. Some well-known examples of hydrozoans include the Portuguese man o' war (Physalia physalis) and fire corals (Millepora spp.).

Phylogeny is the evolutionary history and relationship among biological entities, such as species or genes, based on their shared characteristics. In other words, it refers to the branching pattern of evolution that shows how various organisms have descended from a common ancestor over time. Phylogenetic analysis involves constructing a tree-like diagram called a phylogenetic tree, which depicts the inferred evolutionary relationships among organisms or genes based on molecular sequence data or other types of characters. This information is crucial for understanding the diversity and distribution of life on Earth, as well as for studying the emergence and spread of diseases.

In the context of medical terminology, "light" doesn't have a specific or standardized definition on its own. However, it can be used in various medical terms and phrases. For example, it could refer to:

1. Visible light: The range of electromagnetic radiation that can be detected by the human eye, typically between wavelengths of 400-700 nanometers. This is relevant in fields such as ophthalmology and optometry.
2. Therapeutic use of light: In some therapies, light is used to treat certain conditions. An example is phototherapy, which uses various wavelengths of ultraviolet (UV) or visible light for conditions like newborn jaundice, skin disorders, or seasonal affective disorder.
3. Light anesthesia: A state of reduced consciousness in which the patient remains responsive to verbal commands and physical stimulation. This is different from general anesthesia where the patient is completely unconscious.
4. Pain relief using light: Certain devices like transcutaneous electrical nerve stimulation (TENS) units have a 'light' setting, indicating lower intensity or frequency of electrical impulses used for pain management.

Without more context, it's hard to provide a precise medical definition of 'light'.

Photoreceptor cells in invertebrates are specialized sensory neurons that convert light stimuli into electrical signals. These cells are primarily responsible for the ability of many invertebrates to detect and respond to light, enabling behaviors such as phototaxis (movement towards or away from light) and vision.

Invertebrate photoreceptor cells typically contain light-sensitive pigments that absorb light at specific wavelengths. The most common type of photopigment is rhodopsin, which consists of a protein called opsin and a chromophore called retinal. When light hits the photopigment, it changes the conformation of the chromophore, triggering a cascade of molecular events that ultimately leads to the generation of an electrical signal.

Invertebrate photoreceptor cells can be found in various locations throughout the body, depending on their function. For example, simple eyespots containing a few photoreceptor cells may be scattered over the surface of the body in some species, while more complex eyes with hundreds or thousands of photoreceptors may be present in other groups. In addition to their role in vision, photoreceptor cells can also serve as sensory organs for regulating circadian rhythms, detecting changes in light intensity, and mediating social behaviors.

A pupillary reflex is a type of reflex that involves the constriction or dilation of the pupils in response to changes in light or near vision. It is mediated by the optic and oculomotor nerves. The pupillary reflex helps regulate the amount of light that enters the eye, improving visual acuity and protecting the retina from excessive light exposure.

In a clinical setting, the pupillary reflex is often assessed as part of a neurological examination. A normal pupillary reflex consists of both direct and consensual responses. The direct response occurs when light is shone into one eye and the pupil of that same eye constricts. The consensual response occurs when light is shone into one eye, causing the pupil of the other eye to also constrict.

Abnormalities in the pupillary reflex can indicate various neurological conditions, such as brainstem injuries or diseases affecting the optic or oculomotor nerves.

An encyclopedia is a comprehensive reference work containing articles on various topics, usually arranged in alphabetical order. In the context of medicine, a medical encyclopedia is a collection of articles that provide information about a wide range of medical topics, including diseases and conditions, treatments, tests, procedures, and anatomy and physiology. Medical encyclopedias may be published in print or electronic formats and are often used as a starting point for researching medical topics. They can provide reliable and accurate information on medical subjects, making them useful resources for healthcare professionals, students, and patients alike. Some well-known examples of medical encyclopedias include the Merck Manual and the Stedman's Medical Dictionary.

Placozoa is not a medical term, but rather a taxonomic category in biology. Placozoa is a phylum that includes only one described species, Trichoplax adhaerens, which is a simple, microscopic marine animal. It has a flat, irregularly shaped body without any distinct organs or tissue layers. Its cells are totipotent, meaning they can transform into different types of cells as needed for the organism's survival.

Placozoa has been studied in some developmental and cell biology research contexts, but it is not directly relevant to medical definitions or human health.

I'm sorry for any confusion, but "Volvox" is not a medical term. It is actually the name of a genus of green algae that form colonies and are often found in freshwater environments. Each Volvox colony is composed of many individual cells that are surrounded by a shared protective covering. If you have any questions about medical terminology or concepts, I would be happy to help with those instead!

Mesopic vision is a term used to describe the intermediate level of vision that occurs in conditions of decreased illumination, specifically between 0.02 and 3 candelas per square meter (cd/m²). This range falls between photopic vision, which is vision in bright light (>3 cd/m²), and scotopic vision, which is vision in very low light (

Variations in opsin coding sequences cause X-linked cone dysfunction syndrome with myopia and dichromacy. ... Dive into the research topics of Variations in opsin coding sequences cause X-linked cone dysfunction syndrome with myopia and ...
Ciliary opsins, found in vertebrates and cnidarians, attach to ciliary structures such as rods and cones. Rhabdomeric opsins ... Animal opsins fall phylogenetically into five groups: The ciliary opsins (cilopsins, c-opsins), the rhabdomeric opsins (r- ... Rhabdomeric opsins (rhabopsins, r-opsins) are also known as Gq-opsins, because they couple to a Gq-protein. Rhabopsins are used ... Both RGR-opsins and retinochromes, belong to the chromopsins. RGR-opsins and retinochromes also bind unlike most opsins all- ...
Coexpression of three opsins in cone photoreceptors of the salamander Ambystoma tigrinum. J Comp Neurol. 2014 Jul 01; 522(10): ... Coexpression of three opsins in cone photoreceptors of the salamander Ambystoma tigrinum. ... Coexpression of three opsins in cone photoreceptors of the salamander Ambystoma tigrinum. ...
Glycosylation and palmitoylation are not required for the formation of the X-linked cone opsin visual pigments. / Ostrer, H.; ... Glycosylation and palmitoylation are not required for the formation of the X-linked cone opsin visual pigments. Molecular ... Glycosylation and palmitoylation are not required for the formation of the X-linked cone opsin visual pigments.. ... title = "Glycosylation and palmitoylation are not required for the formation of the X-linked cone opsin visual pigments.", ...
... it has been controversial whether the same requirement holds for cone … ... it has been controversial whether the same requirement holds for cone opsin inactivation. Mouse cone photoreceptors express two ... Arrestin-independent inactivation is 70-fold more rapid in cones than in rods, however. Dual arrestin expression in cones could ... Mouse cones require an arrestin for normal inactivation of phototransduction Neuron. 2008 Aug 14;59(3):462-74. doi: 10.1016/j. ...
... and middle-wavelength sensitive cone photoreceptor visual pigments in humans, induce splicing defects and have been associated ... Keywords: Blue Cone Monochromacy; Bornholm Eye Disease; cone photoreceptor LWS and MWS opsin genes; exonic splicing defect; ... Novel OPN1LW/OPN1MW Exon 3 Haplotype-Associated Splicing Defect in Patients with X-Linked Cone Dysfunction Int J Mol Sci. 2022 ... Patients carrying the novel L-I-V-V-A haplotype presented with a mild form of Blue Cone Monochromacy or Bornholm Eye Disease- ...
Most mammals are dichromats possessing, in addition to a single rod photopigment, two classes of cone photopigment, LWS and ... Spalax lacks a functional UVS/VS cone photopigment due to the accumulation of several deleterious mutational changes that have ... cone photopigments have been isolated from the eye of the subterranean blind mole rat (Spalax ehrenbergi superspecies). Spalax ... and is not an artefact of having an ancestor which lacked a functional UVS/VS cone photopigment. We conclude that colour ...
7e). Photoreceptors expressing L/M- or S-opsins were also observed (Fig. 7f-i). The morphologies of the rods and cones and the ... rod opsin (mouse, 1:100, gift from Dr David Hicks), L/M-opsin (rabbit, 1:50,000, gift from Dr Jeremy Nathans), S-opsin (rabbit ... In addition, expression of L/M- and S-cone opsins was not apparent. As RA has been shown to influence photoreceptor ... Rods (green) and cones (red) displayed advanced morphological differentiation, with their opsin expression, polarization and ...
Previous symbols and names : CBBM, CBP, RCP, color blindness, protan, opsin 1 (cone pigments), long-wave-sensitive, red cone ... OPN1LW - opsin 1, long wave sensitive. *Synonym(s) : COD5, cone dystrophy 5 (X-linked) ... Disease-causing germline mutation(s) in Blue cone monochromatism ORPHA:16. *Disease-causing germline mutation(s) in Cone rod ... Candidate gene tested in X-linked cone dysfunction syndrome with myopia ORPHA:90001. ...
A feasible approach for humans may be to develop compounds that specifically prevent the activation of rod but not cone opsins ... Localization of T4R opsin in the T4R/RPE65−/− dog was not reported, so it is unknown whether unliganded T4R opsin is retained ... 5B). In contrast, T17M rhodopsin caused clear loss of total rod opsin even at expression levels ,2% of total rod opsin (Fig. 5B ... Inactive T4K and T17M opsins exhibited reduced rod toxicity. A, C, Plots of transgenic opsin expression levels versus total rod ...
Each cone type carries a specific opsin. In rodents, S-cones express the ultraviolet-sen-sitive or SWS1 opsin, 1,2 and M/L- ... The distribution of L-cones seemed to be comple-mentary to the S-cones. The highest densities were observed in the superior ... Discussion: The fact that a single cone type and double cones reacted with an antibody that had been shown earlier to label ... Two automated routines were developed to quantify the whole population of S-and L-cones. Detailed isodensity maps of each cone ...
Opsin genes, cone photopigments, color vision, and color blindness. Pp. 3-51 in Color vision: From Genes to Perception. K.R. ...
Restoration of high-sensitivity and adapting vision with a cone opsin. Article ... Exogenously expressed opsins are valuable tools for optogenetic control of neurons in circuits. A deeper understanding of ... Inherited and age-related retinal degenerative diseases cause progressive loss of rod and cone photoreceptors, leading to ...
Restoration of high-sensitivity and adapting vision with a cone opsin. Nat Commun 10, 1221 (2019). ... The retina is a complex tissue in the back of the eye that contains the rod and cone photoreceptor cells. The photoreceptors ... 7. Fortuny, C. & Flannery, J.G. Mutation-Independent Gene Therapies for Rod-Cone Dystrophies. Adv Exp Med Biol 1074, 75-81 ( ... Viral-mediated RdCVF and RdCVFL expression protects cone and rod photoreceptors in retinal degeneration. J Clin Invest 125, 105 ...
Bound within these opsin proteins is a small organic light-absorbing molecule (or chromophore) called retinal. Retinal is a ... Within the retinas of our eyes, we have photoreceptor cells (called rods and cones) that are responsible for detecting all the ... Bound within these opsin proteins is a small organic light-absorbing molecule (or chromophore) called ,i,retinal.,/i, Retinal ... Bound within these opsin proteins is a small organic light-absorbing molecule (or chromophore) called ,i,retinal.,/i, Retinal ...
Rhim, I., Coello-Reyes, G., Ko, H. K., and Nauhaus, I. (2017). Maps of cone opsin input to mouse V1 and higher visual areas. J ... 2020). True S-cones are concentrated in the ventral mouse retina and wired for color detection in the upper visual field. eLife ... However, when considering the distribution of short-wavelength (s) opsins alone, a much deeper gradient can be seen across the ... 1994). Two different visual pigments in one retinal cone cell. Neuron 13, 1159-1166. doi: 10.1016/0896-6273(94)90053-1 ...
Targeting Gene Expression To Canine Cones With The Human Cone Opsin Promoters ... Longitudinal in vivo Characterization of Expression of Viral Delivered Genes for L-opsin and Green Fluorescent Protein in Cone ... AAV-GC1 Restores Subcellular Distribution of Cone Arrestin and GCAP1 Expression in Cone Cells of the GC1 Ko Mouse ... Lentiviral-Mediated Gene Transfer of Rpe65 in Mouse Models of Leber Congenital Amaurosis: Effects on Cone Degeneration and ...
Unlike other light responsive opsins, it isnt produced by rod and cone cells. Experiments have shown that mice without rods ... "The Opsins." Genome Biology 6.3 (2005): 213. PMC. Web. 27 Feb. 2018.. 2Nickle, B., and P. R. Robinson. "The opsins of the ... Were able to produce proteins known as opsin and retinal which work together to detect light. To function, retinal and opsin ... This movement disrupts the chemical bond between retinal and opsin, causing the opsin protein to move a little as well. These ...
Cone cells responsible for color vision in the stickleback retina contain SWS2, an opsin protein sensitive to blue light. Amino ... Next, the authors compared their stickleback results to previously published opsin genes in two related species of fish ( ... Convergent evolution of SWS2 opsin facilitates adaptive radiation of threespine stickleback into different light environments. ... maximizing the opsins sensitivity in the dark water; no such pattern was seen in clearwater sticklebacks. In blackwater fish ...
GRK1-dependent phosphorylation of S and M opsins and their binding to cone arrestin during cone phototransduction in the mouse ... These were antibodies for S-and M-opsins, and M-cone arrestin (M-Car) [97,98]: gifts from Cheryl Craft; vesicular glutamate ... For example, inhibition of glycolysis by iodoacetate produces rod cell death before cone cell death [17-19], rod- and cone- ... The higher expression of CKs in cones, compared to rods, also suggests that cones buffer and sustain the ATP more efficiently ...
"A mouse M-opsin monochromat: retinal cone photoreceptors have increased M-opsin expression when S-opsin is knocked out". Vision ... "An S-Opsin knock-in mouse (F81Y) reveals a role for the native ligand 11-cis-retinal in cone opsin biosynthesis". Journal of ... The S-opsin knockout mouse has revealed a competitive inhibition between S- and M-opsin mRNA during translation in cones that ... These include the functional co-expression of both mouse cone opsins (S- and M-) in most cones, the requirement for the G- ...
Humans eye have four different other opsins beside rhodopsin. The photopsins found in the different types of the cone cells of ... cones. 721, outer nuclear layer. 722 made up of nuclei from rods and cones, outer limiting membrane. 707 formed by Müller cells ... Cones, on the other hand, allow us to see colors and can adapt quickly to stark changes in light intensity. Cones rely on light ... The "cones" are specialized photoreceptor cells. They fill the central part of the retina called macula lutea. The cones sense ...
a) Rhodopsin, the photoreceptor in vertebrates, has two parts: the trans-membrane protein opsin, and retinal. When light ... Is opsin a Photopigment?. The photopigment in the outer segment of the cone consists of two covalently linked parts, a protein ... What are the three opsins?. Vertebrate Ancient (VA) opsin has three isoforms VA short (VAS), VA medium (VAM), and VA long (VAL) ... Is mouse opsin sensitive to light?. Rods mediate vision in dim light, whereas cones mediate vision in bright light. Mouse ...
Cones use three types of opsins that react to short, medium, and long wavelengths of light. Those frequencies correspond ... Specifically, blue cones are most sensitive at frequencies of 445 nanometers, green cones 535 nanometers, and red cones at 575 ... In the human eye, there are four main types of opsins that react to different light wavelengths. Cones use three types and Rods ... Rods far outnumber Cones in the human eye, approximately 120 million compared to just 6-7 million cones. They are much more ...
Any of three visual pigments, composed of 11-cis-retinal bound to an opsin, found in the cones of the retina. SYN: visual ...
Cones function in well-lit conditions and are responsible for the perception of colour through the use of a range of opsins, as ... Apices of the RPE cells which encase part of the cone OSs. Poorly distinguishable from RPE. Previously: "cone outer segment ... Cone-rod dystrophy (CORD) describes a number of diseases where vision loss is caused by deterioration of the cones and/or rods ... The center of the fovea holds very few blue-sensitive cones.. Distribution of rods and cones along a line passing through the ...
The OPN1LW, OPN1MW, and OPN1SW genes provide instructions for making the three opsin pigments in cones. The opsin made from the ... These changes lead to an absence of L or M cones or to the production of abnormal opsin pigments in these cones that affect red ... These mutations lead to the premature destruction of S cones or the production of defective S cones. Impaired S cone function ... and cones with this pigment are called middle-wavelength-sensitive or M cones. The opsin made from the OPN1SW gene is more ...
In mouse, S-opsins are co-expressed with M-opsins in cone photoreceptors and there are more S-opsins expressed in the ventral ... For example, mouse cones co-express medium wavelength and short wavelength opsins (M-opsin and S-opsin), with a dorsal-to- ... Ekesten, B. & Gouras, P. Cone and rod inputs to murine retinal ganglion cells: evidence of cone opsin specific channels. Vis. ... Applebury, M. L. et al. The murine cone photoreceptor: a single cone type expresses both S and M opsins with retinal spatial ...

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