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Rhodopsin is a protein found in the outer segment discs of rod cells. It mediates scotopic vision , which is monochromatic vision in dim light. [ 7 ] [ 19 ] Rhodopsin most strongly absorbs green-blue light (~500 nm) [ 20 ] [ 21 ] and appears therefore reddish-purple, hence the archaic term "visual purple".
It has also been identified in other places such as the heart, and in aggressive breast cancer tumors. [2] [3] The physical origins of eye lens transparency and its relationship to cataract are an active area of research. [4] Since it has been shown that lens injury may promote nerve regeneration, [5] crystallin has been an area of neural research.
The seven transmembrane α-helical domains in opsins are connected by three extra-cellular and three cytoplasmic loops. Along the α-helices and the loops, many amino acid residues are highly conserved between all opsin groups, indicating that they serve important functions and thus are called functionally conserved residues.
The goal of gene therapy studies is to virally supplement retinal cells expressing mutant genes associated with the retinitis pigmentosa phenotype with healthy forms of the gene; thus, allowing the repair and proper functioning of retinal photoreceptor cells in response to the instructions associated with the inserted healthy gene.
The four pigments in a bird's cone cells (in this example, estrildid finches) extend the range of color vision into the ultraviolet. [1]Tetrachromacy (from Greek tetra, meaning "four" and chroma, meaning "color") is the condition of possessing four independent channels for conveying color information, or possessing four types of cone cell in the eye.
The polymorphisms may be in an OCA2 regulatory sequence, where they may influence the expression of the gene product, which in turn affects pigmentation. [13] A specific mutation within the HERC2 gene, a gene that regulates OCA2 expression, is partly responsible for blue eyes. [9] Other genes implicated in eye color variation are SLC24A4 [22 ...
Additionally, the genetic toolkit for positioning eyes is shared by all animals: The PAX6 gene controls where eyes develop in animals ranging from octopuses [17] to mice and fruit flies. [ 18 ] [ 19 ] [ 20 ] Such high-level genes are, by implication, much older than many of the structures that they control today; they must originally have ...
Pit eyes, also known as stemmata, are eye-spots which may be set into a pit to reduce the angles of light that enters and affects the eye-spot, to allow the organism to deduce the angle of incoming light. Found in about 85% of phyla, these basic forms were probably the precursors to more advanced types of "simple eyes".