Biogenic Guanine Crystals from the Skin of Fish May Be Designed to Enhance Light Reflectance

Levy-Lior, Avital; Pokroy, Boaz; Levavi‐Sivan, Berta; Leiserowitz, Leslie; Weiner, Steve; Addadi, Lia

doi:10.1021/cg0704753

Cited by 123 publications

(178 citation statements)

References 28 publications

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“…5a). (2) As found in scales of fish, in other biological reflectors the planar purine molecules in reflective crystals are also oriented parallel to the broad face of the crystal platelets (Greenstein, 1973;Levy-Lior et al, 2008). Although in the orthogonal case reflected light is polarized slightly more strongly ( Fig.…”

Section: Orientation Of Guanine Moleculesmentioning

confidence: 89%

“…In fish scales, the planar purine molecules lie essentially parallel to the broad face of the crystals in the x-y-plane (henceforth called the "parallel case"; Fig. 6a, middle sketch), resulting in n x = 1.85, n y = 1.80 and n z = 1.46 (Greenstein, 1973;Levy-Lior et al, 2008). For normal light incidence on the plate (θ i = 0 • ) along the z−axis, reflection is high for light oscillating both along the x−axis and the y−axis since the refractive index differences between crystal and cytoplasm is high for both e-vector orientations (1.85 vs. 1.33 along the x−axis, 1.80 vs. 1.33 along the y−axis).…”

Section: Mathematical Modelingmentioning

confidence: 99%

“…In contrast to fish scales, synthetic crystalline platelets of organic substances with planar molecules mostly consist of molecules oriented orthogonal to the broad face of the platelets in the y-z-plane ("orthogonal case"; Fig. 6a, right sketch), a condition that is also obtained when guanine-hypoxanthine mixtures are crystallized in vitro (Greenstein, 1973;Levy-Lior et al, 2008). In the orthogonal case (n x = 1.46, n y = 1.80, n z = 1.85), reflection for normal incidence along the z−axis remains high for light oscillating along the y−axis, but for polarization along the x−axis, reflection is reduced because the refractive index difference along the x−axis is small (n x = 1.46 vs. n l = 1.33).…”

Section: Mathematical Modelingmentioning

confidence: 99%

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Polarizing optics in a spider eye

Mueller

Labhart

2010

J Comp Physiol A

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Many arthropods including insects and spiders exploit skylight polarization for navigation. One of the four eye pairs of the spider Drassodes cupreus is dedicated to detect skylight polarization. These eyes are equipped with a tapetum that strongly plane-polarizes reflected light. This effectively enhances the polarization-sensitivity of the photoreceptors, improving orientation performance. With a multidisciplinary approach, we demonstrate that D. cupreus exploits reflective elements also present in non-polarizing tapetal eyes of other species such as Agelena labyrinthica. By approximately orthogonal arrangement of two multilayer reflectors consisting of reflecting guanine platelets, the tapetum uses the mechanism of polarization by reflection for polarizing reflected light.Polarizing optics in a spider eye AbstractMany arthropods including insects and spiders exploit skylight polarization for navigation. One of the four eye pairs of the spider Drassodes cupreus is dedicated to detect skylight polarization. These eyes are equipped with a tapetum that strongly plane-polarizes reflected light. This effectively enhances the polarization-sensitivity of the photoreceptors, improving orientation performance. With a multidisciplinary approach, we demonstrate that D. cupreus exploits reflective elements also present in nonpolarizing tapetal eyes of other species such as Agelena labyrinthica. By approximately orthogonal arrangement of two multilayer reflectors consisting of reflecting guanine platelets, the tapetum uses the mechanism of polarization by reflection for polarizing reflected light.

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Section: Orientation Of Guanine Moleculesmentioning

confidence: 89%

Section: Mathematical Modelingmentioning

confidence: 99%

Section: Mathematical Modelingmentioning

confidence: 99%

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Polarizing optics in a spider eye

Mueller

Labhart

2010

J Comp Physiol A

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“…32,33) A shining mechanism of guanine crystals has also been reported. 34,35) This explains why the skin of gnomefishes and other such fish with a metallic color have a large amount of guanine (296.7 mg/100 g for the gnomefish skin, 105.8 mg/100 g for sardine).…”

Section: Amount Of Purines In Fresh Fishmentioning

confidence: 90%

Total Purine and Purine Base Content of Common Foodstuffs for Facilitating Nutritional Therapy for Gout and Hyperuricemia

Kaneko

Aoyagi

Fukuuchi

et al. 2014

Biological & Pharmaceutical Bulletin

185

131

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Purines are natural substances found in all of the body's cells and in virtually all foods. In humans, purines are metabolized to uric acid, which serves as an antioxidant and helps to prevent damage caused by active oxygen species. A continuous supply of uric acid is important for protecting human blood vessels. However, frequent and high intake of purine-rich foods reportedly enhances serum uric acid levels, which results in gout and could be a risk factor for cardiovascular disease, kidney disease, and metabolic syndrome. In Japan, the daily intake of dietary purines is recommended to be less than 400 mg to prevent gout and hyperuricemia. We have established an HPLC method for purine analysis and determined purines in a total of 270 foodstuffs. A relatively small number of foods contained concentrated amounts of purines. For the most part, purine-rich foods are also energy-rich foods, and include animal meats, fish meats, organs such as the liver and fish milt, and yeast. When the ratio of the four purine bases (adenine, guanine, hypoxanthine, and xanthine) was compared, two groups of foods were identified: one that contained mainly adenine and guanine and one that contained mainly hypoxanthine. For patients with gout and hyperuricemia, the amount of total purines and the types of purines consumed, particularly hypoxanthine, are important considerations. In this context, the data from our analysis provide a purine content reference, and thereby clinicians and patients could utilize that reference in nutritional therapy for gout and hyperuricemia.

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“…8 An anhydrous guanine crystal has parallel stacked guanine molecules. 9 In the previous studies, it was found that biogenic guanine crystals showed a quick response to external magnetic fields where the crystal platelets oriented parallel to the magnetic field and distinctly switched the intensity of light reflection. [10][11][12][13] The present study focused on assessing the dynamic behaviour of guanine by using synthetic guanine crystals.…”

Section: Introductionmentioning

confidence: 99%

Quenching of light flickering in synthetic guanine crystals in aqueous solutions under strong static magnetic fields

2017

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The present study focused on the vibration of micro crystal particles of guanine due to Brownian motion. The organic particle has a refractive index of 1.83 and caused a flickering of light. To test the possibility of using magnetic properties under wet conditions, changes in the frequency of particle vibration by applying magnetic fields were investigated. At first, we found that the exposure at 5 T inhibited the flickering light intensities and the particle vibration slightly decreased. Next, we carried out a high speed camera measurement of the Brownian motion of the particle with a time resolution of 100 flame per second (fps) with and without magnetic field exposures. It was revealed that the vibrational speed of synthetic particles was enhanced at 500 mT. Detailed analyses of the particle vibration by changing the direction of magnetic fields versus the light source revealed that the Brownian motion’s vibrational frequency was entrained under magnetic fields at 500 mT, and an increase in vibration speed to 20Hz was observed. Additional measurements of light scattering fluctuation using photo-detector and analyses on auto-correlation also confirmed this speculation. The studied Brownian vibration may be influenced by the change in mechanical interactions between the vibration particles and surrounding medium. The discovered phenomena can be applied for molecular and biological interactions in future studies.

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Biogenic Guanine Crystals from the Skin of Fish May Be Designed to Enhance Light Reflectance

Cited by 123 publications

References 28 publications

Polarizing optics in a spider eye

Polarizing optics in a spider eye

Total Purine and Purine Base Content of Common Foodstuffs for Facilitating Nutritional Therapy for Gout and Hyperuricemia

Quenching of light flickering in synthetic guanine crystals in aqueous solutions under strong static magnetic fields

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