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Cuticulosome
The cuticulosome is a spherical, iron-rich structure located in the cuticular plate of auditory and vestibular hair cells in birds. Cuticulosomes are 300-600 nm in diameter and are composed of ferritin-like granules that in some cases are structured in paracrystalline arrays. Due to its specific location in sensory hair cells of the inner ear and its iron-rich composition it was proposed to be involved in the magnetic sense of birds. However, physical simulations and calculations showed that it lacks sufficient magnetic susceptibility In electromagnetism, the magnetic susceptibility (Latin: , "receptive"; denoted ) is a measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization (magnetic moment per unit volume) to the ap ... to act as a torque based magnetoreceptor. An alternative hypothesis suggests that the cuticulosome might work as an intracellular electromagnetic oscillator to detect magnetic fields. References ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Sense
Magnetoreception is a sense which allows an organism to detect the Earth's magnetic field. Animals with this sense include some arthropods, molluscs, and vertebrates (fish, amphibians, reptiles, birds, and mammals, though not humans). The sense is mainly used for orientation and navigation, but it may help some animals to form regional maps. Experiments on migratory birds provide evidence that they make use of a cryptochrome protein in the eye, relying on the quantum radical pair mechanism to perceive magnetic fields. This effect is extremely sensitive to weak magnetic fields, and readily disturbed by radio-frequency interference, unlike a conventional iron compass. Birds have iron-containing materials in their upper beaks. There is some evidence that this provides a magnetic sense, mediated by the trigeminal nerve, but the mechanism is unknown. Cartilaginous fish including sharks and stingrays can detect small variations in electric potential with their electroreceptive ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cuticular Plate
The reticular membrane (RM, also called reticular lamina or apical cuticular plate)Histology and Virtual Microscopy Learning Resources ; accessed 4 Apr 2013 is a thin, stiff lamina that extends from the outer hair cells to the Hensen's cells.Radivoj V. Krstic Human Microscopic Anatomy: An Atlas for Students of Medicine and Biology Springer, 1991; pp 554. . The RM is composed of "minute-fiddle-shaped ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hair Cells
Hair cells are the sensory receptors of both the auditory system and the vestibular system in the ears of all vertebrates, and in the lateral line organ of fishes. Through mechanotransduction, hair cells detect movement in their environment. In mammals, the auditory hair cells are located within the spiral organ of Corti on the thin basilar membrane in the cochlea of the inner ear. They derive their name from the tufts of stereocilia called ''hair bundles'' that protrude from the apical surface of the cell into the fluid-filled cochlear duct. The stereocilia number from 50-100 in each cell while being tightly packed together and decrease in size the further away they are located from the kinocilium. The hair bundles are arranged as stiff columns that move at their base in response to stimuli applied to the tips. Mammalian cochlear hair cells are of two anatomically and functionally distinct types, known as outer, and inner hair cells. Damage to these hair cells results in d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ferritin
Ferritin is a universal intracellular protein that stores iron and releases it in a controlled fashion. The protein is produced by almost all living organisms, including archaea, bacteria, algae, higher plants, and animals. It is the primary ''intracellular iron-storage protein'' in both prokaryotes and eukaryotes, keeping iron in a soluble and non-toxic form. In humans, it acts as a buffer against iron deficiency and iron overload. Ferritin is found in most tissues as a cytosolic protein, but small amounts are secreted into the serum where it functions as an iron carrier. Plasma ferritin is also an indirect marker of the total amount of iron stored in the body; hence, serum ferritin is used as a diagnostic test for iron-deficiency anemia. Aggregated ferritin transforms into a toxic form of iron called hemosiderin. Ferritin is a globular protein complex consisting of 24 protein subunits forming a hollow nanocage with multiple metal–protein interactions. Ferritin that is n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paracrystalline
In materials science, paracrystalline materials are defined as having short- and medium-range ordering in their lattice (similar to the liquid crystal phases) but lacking crystal-like long-range ordering at least in one direction. Origin and definition The words "paracrystallinity" and "paracrystal" were coined by the late Friedrich Rinne in the year 1933. Their German equivalents, e.g. "Parakristall", appeared in print one year earlier. A general theory of paracrystals has been formulated in a basic textbook, and then further developed/refined by various authors. Rolf Hosemann's definition of an ideal paracrystal is: "The electron density distribution of any material is equivalent to that of a paracrystal when there is for every building block one ideal point so that the distance statistics to other ideal points are identical for all of these points. The electron configuration of each building block around its ideal point is statistically independent of its counterpart in ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magnetic Susceptibility
In electromagnetism, the magnetic susceptibility (Latin: , "receptive"; denoted ) is a measure of how much a material will become magnetized in an applied magnetic field. It is the ratio of magnetization (magnetic moment per unit volume) to the applied magnetizing field intensity . This allows a simple classification, into two categories, of most materials' responses to an applied magnetic field: an alignment with the magnetic field, , called paramagnetism, or an alignment against the field, , called diamagnetism. Magnetic susceptibility indicates whether a material is attracted into or repelled out of a magnetic field. Paramagnetic materials align with the applied field and are attracted to regions of greater magnetic field. Diamagnetic materials are anti-aligned and are pushed away, toward regions of lower magnetic fields. On top of the applied field, the magnetization of the material adds its own magnetic field, causing the field lines to concentrate in paramagnetism, or be excl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
