When the reflectins in both iridocytes and leucophores are induced to condense, the refractive index increases, causing light to be reflected in two distinct ways: Bragg reflection and Mie scattering. ![]() Switchable white cells, called leucophores, also contain reflectins, but in a thousand or more small membrane-enclosed spherical vesicles of varying sizes and shapes. The internal arrangement of the reflectins in switchable color cells, called iridocytes, creates an accordion-like structure or, in scientific terms, alternating lamellae. The switchable color and white cells have two different systems for reflecting light, because when activated, the reflectins produce two distinct biological nanostructures. "The facts that the switchable white cells contain some of the same reflectins, that they're triggered by the same neurotransmitter, and that this drives a change in the membrane assemblies containing the reflectins all suggest that they operate by a molecular mechanism fundamentally related to that controlling the switchable color," he added. "Whether colored or white, these cells become switchable when activated by the neurotransmitter acetylcholine," explained study co-author Daniel Morse, professor of molecular genetics and biochemistry in the Department of Molecular, Cellular, and Developmental Biology. The current research builds on the scientists' previous work that revealed the mechanism responsible for the dramatic changes in color used by such creatures as squids and octopuses. The findings are published in the Journal of Experimental Biology. This marks the first time that switchable white cells based on reflectins –– the proteins responsible for reflecting light as color –– have been observed. These flank a single stripe, which can go from complete transparency to bright white. Researchers at UC Santa Barbara have discovered that this glamorous cephalopod possesses a pair of stripes that can sparkle with rainbow iridescence. The female common market squid –– AKA Doryteuthis opalescens –– may not be so common after all.
0 Comments
Leave a Reply. |