A5030981978- Coral and Marine Ecosystems Studies
- Photochromic and Fluorescence Chemistry
- Neurobiology and Insect Physiology Research
- Crystallization and Solubility Studies
- Marine Sponges and Natural Products
- Amphibian and Reptile Biology
- Supramolecular Self-Assembly in Materials
- Crustacean biology and ecology
- Food Industry and Aquatic Biology
- Mineralogy and Gemology Studies
- X-ray Diffraction in Crystallography
- Calcium Carbonate Crystallization and Inhibition
- Photoreceptor and optogenetics research
- Biocrusts and Microbial Ecology
- Advanced Scientific Research Methods
- Photonic Crystals and Applications
- Fern and Epiphyte Biology
- Geological Studies and Exploration
- Animal Behavior and Reproduction
- Cephalopods and Marine Biology
- Polydiacetylene-based materials and applications
- Ichthyology and Marine Biology
- bioluminescence and chemiluminescence research
- Nonlinear Optical Materials Studies
- Liquid Crystal Research Advancements
Ben-Gurion University of the Negev
2019-2024
Weizmann Institute of Science
2017-2018
Highly reflective crystals of the nucleotide base guanine are widely distributed in animal coloration and visual systems. Organisms precisely control morphology organization to optimize different optical effects, but little is known about how this achieved. Here we examine a fundamental question that has remained unanswered after over 100 years research on guanine:
Many oceanic prey animals use transparent bodies to avoid detection. However, conspicuous eye pigments, required for vision, compromise the organisms' ability remain unseen. We report discovery of a reflector overlying pigments in larval decapod crustaceans and show how it is tuned render organisms inconspicuous against background. The ultracompact constructed from photonic glass crystalline isoxanthopterin nanospheres. nanospheres' size ordering are modulated tune reflectance deep blue...
A fundamental question regarding light scattering is how whiteness, generated from multiple scattering, can be obtained thin layers of materials. This challenge arises the phenomenon optical crowding, whereby, for scatterers packed with filling fractions higher than ~30%, reflectance drastically reduced due to near-field coupling between scatterers. Here we show that extreme birefringence isoxanthopterin nanospheres overcomes crowding effects, enabling and brilliant whiteness ultra-thin...
Spectacular colors and visual phenomena in animals are produced by light interference from highly reflective guanine crystals. Little is known about how organisms regulate crystal morphology to tune the optics of these systems. By following formation developing spiders, a crystallization mechanism elucidated. Guanine "non-classical," multistep process involving progressive ordering states. Crystallization begins with nucleation partially ordered nanogranules disordered precursor phase....
Abstract Animals precisely control the morphology and assembly of guanine crystals to produce diverse optical phenomena in coloration vision. However, little is known about how organisms regulate crystallization optically useful morphologies which express highly reflective crystal faces. Guanine form inside iridosome vesicles within chromatophore cells called iridophores. By following formation developing scallop eyes, we show that pre-assembled, fibrillar sheets provide an interface for...
Highly reflective assemblies of purine, pteridine, and flavin crystals are used in the coloration visual systems many different animals. However, structure determination biogenic by single-crystal XRD is challenging due to submicrometer size beam sensitivity crystals, powder inhibited small volumes powders, crystalline impurity phases, significant preferred orientation. Consequently, crystal structures materials remain unknown. Herein, we demonstrate that 3D electron diffraction (3D ED)...
Significance Some aquatic animals use reflectors in their eyes either to form images or increase photon capture. Guanine is the most widespread molecular component of these reflectors. Here, we show that crystals isoxanthopterin, a pteridine analog guanine, both image-forming “distal” mirror and intensity-enhancing tapetum reflector compound some decapod crustaceans. The crystal structure isoxanthopterin was determined, providing an explanation for why are so well suited efficient...
Many animals undergo changes in functional colors during development, requiring the replacement of integument or pigment cells. A classic example defensive color switching is found hatchling lizards, which use conspicuous tail to deflect predator attacks away from vital organs. These usually fade concealing ontogeny. Here, we show that ontogenetic blue-to-brown change Acanthodactylus beershebensis lizards results changing optical properties single types developing chromatophore The blue...
Abstract Highly reflective crystals of small organic molecules are the functional materials in a wide variety optical systems animals. We present perspective on this field biomineralization and review evidence for widespread distribution These were, until recently, largely overlooked principally because lost during conventional electron microscopy preparation procedures. document discovery crystalline pteridines as new class biological explain why many more biocrystals will likely be...
Abstract Fish‐scale iridophore cells deposit guanine crystals and assemble them into multilayer reflectors to produce silvery reflectance. The crystal orientation controls the reflective properties of fish scales, but little is known about degree whether this pre‐determined at level an individual cell. Koi fish‐scale‐attached iridophores, iridophores on regenerated cultured were examined by using light microscopy synchrotron micro‐X‐ray diffraction. More than 95 % thin {100} plates in mature...
Many spectacular optical phenomena in animals are produced by reflective assemblies of guanine crystals. The crystals comprise planar H-bonded layers π-stacked molecules with a high in-plane refractive index. By preferentially expressing the highly (100) crystal face and controlling its cross-sectional shape, organisms generate diverse array photonic superstructures. How is this precise control over morphology achieved? Recently, it was found that biogenic composites, containing quantities...
Recent studies of optical reflectors as part the vision apparatus in eyes decapod crustaceans revealed assemblies nanoscale spherulites - spherical core-shell nanoparticles with radial birefringence. Simulations performed on system highlighted advantages anisotropy enhancing functionality these structures. So far, calculations nanoparticle properties have relied refractive indices obtained using ab-initio calculations. Here we describe a direct measurement tangential index spherulites, which...
Abstract Many animals undergo dramatic changes in colour during development 1,2 . Changes predation risk ontogeny are associated with spectacular switches defensive colours, typically involving the replacement of skin or production new pigment cells 3 Ontogenetic systems ideal models for understanding evolution and formation mechanisms animal which remain largely enigmatic 2 We show that switching lizards arises by reorganization a single photonic system, as an incidental by-product...
Abstract The eyes of some aquatic animals form images through reflective optics. Shrimp, lobsters, crayfish and prawns possess reflecting superposition compound eyes, composed thousands square-faceted eye-units (ommatidia). Mirrors in the upper part eye (the distal mirror) reflect light collected from many ommatidia onto underlying photosensitive elements retina, rhabdoms. A second reflector, tapetum, back-scatters dispersed Using microCT cryo-SEM imaging accompanied by situ micro-X-ray...
Photonic structures are responsible for the vivid colors of many animals, and also serve as reflectors filters in vision. Our recent work has explored core–shell photonic nanostructures involved eyes several decapod crustaceans, motivates further research into exploiting spatial variation birefringence designing ultrathin reflecting structures.
Abstract Animals precisely control the morphology and assembly of highly reflective guanine crystals to produce diverse optical phenomena used in coloration vision. However, little is known about how organisms regulate crystallization optically useful crystal morphologies which express faces. Guanine form inside iridosome vesicles within specialized chromatophore cells called iridophores. By following formation iridosomes developing scallop eyes we show that, despite their different physical...