Difference between revisions of "Part:BBa K638003"

Latest revision as of 12:18, 28 September 2020

Reflectin 1B from Euprymna scolopes

Coding sequence for [http://www.ncbi.nlm.nih.gov/nuccore/AY294650.1 Reflectin 1B] from Euprymna scolopes (codon optimised for E.coli). Read more about [http://2011.igem.org/Team:Cambridge/Project/Background the background to this protein].

Usage and Biology

Cross-sectional TEM micrograph of reflectin platelet stacks from the light organ of Euprymna scolopes. Scale bar: 5 m. Image taken from [http://www.nature.com/nmat/journal/v6/n7/full/nmat1930.html Kramer et al, 2007.]

Reflectin Proteins

Many cephalopods (octopuses, squids, cuttlefish, etc.) demonstrate camouflage capabilities by adaptive transparency. Some chalepods can even vanish from the environment by performing these capabilities. These animals can change the optical properties of their skin, how their skin transmits, absorbs, and reflects light [3]. Reflectivity in these animal tissues is achieved by stacking flat, insoluble, structural platelets by alternating layers of high and low refractive index in iridocytes [4]. This alternate arrangement, called a Bragg reflector, creates a thin-film interference pattern which is the reason for reflection of incident light from the tissue [3]. In aquatic animals, reflector platelets generally consist of purine crystals, particularly guanine and hypoxanthine. However, cephalopod reflector platelets contain reflectin proteins instead of these purine crystals. Reflectin proteins found in cephalopods are responsible for transparency abilities by employing structural coloration and iridescence [1, 2].

Optical characterization of these proteins is an important work for studies using reflectin proteins. However, it is hard to characterize the refractive index of these proteins since there are multiple Bragg stacks with unknown variation in spacings, refractive indices and orientations in a typical tissue of a chalepod. Ghoshal et al (2014) employed a microspectroscopy procedure to investigate these properties. They found a progressively higher refractive index from 1.33 to 1.43 from the same Bragg stack as they immersed these Bragg stacks in solutions of different reflectivities.

[1] Junko Ogawa et al. (2020) Genetic manipulation of the optical refractive index in living cells https://doi.org/10.1101/2020.07.09.196436

[2] Atrouli Chatterjee et al. (2020) Cephalopod-inspired optical engineering of human cells https://doi.org/10.1038/s41467-020-16151-6

[3] Wendy J. Crookes et al. (2004) Reflectins: The Unusual Proteins of Squid Reflective Tissues https://doi.org/10.1126/science.1091288

[4] Amitabh Ghoshal et al. (2014) Experimental determination of refractive index of condensed reflectin in squid iridocytes http://dx.doi.org/10.1098/rsif.2014.0106 Sequence and Features