Morphologies of eumelanins from the ink of six cephalopods species measured by atomic force microscopy

Sun, Yulin; Tian, Liangliang; Wen, Jing; Zhao, Juan; Zhang, Wei; Xie, Chunyao; Zhou, Meiqing; Qiu, Xiaoying; Chen, Daohai

doi:10.1007/s11802-017-3010-8

Cited by 4 publications

(3 citation statements)

References 35 publications

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“…Furthermore, ‘granule’ is typically used to designate a membrane‐less aggregate of molecules [e.g. melanin aggregates of cephalopod inks (Sun et al, )] whereas known ommochrome organelles are membrane‐bound. It is not known whether ommochromes are aggregated or fully soluble in this environment.…”

Section: Ommochromes Within the Cell: The Ommochromasome Life Cyclementioning

confidence: 99%

Ommochromes in invertebrates: biochemistry and cell biology

2018

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Ommochromes are widely occurring coloured molecules of invertebrates, arising from tryptophan catabolism through the so-called Tryptophan → Ommochrome pathway. They are mainly known to mediate compound eye vision, as well as reversible and irreversible colour patterning. Ommochromes might also be involved in cell homeostasis by detoxifying free tryptophan and buffering oxidative stress. These biological functions are directly linked to their unique chromophore, the phenoxazine/phenothiazine system. The most recent reviews on ommochrome biochemistry were published more than 30 years ago, since when new results on the enzymes of the ommochrome pathway, on ommochrome photochemistry as well as on their antiradical capacities have been obtained. Ommochromasomes are the organelles where ommochromes are synthesised and stored. Hence, they play an important role in mediating ommochrome functions. Ommochromasomes are part of the lysosome-related organelles (LROs) family, which includes other pigmented organelles such as vertebrate melanosomes. Ommochromasomes are unique because they are the only LRO for which a recycling process during reversible colour change has been described. Herein, we provide an update on ommochrome biochemistry, photoreactivity and antiradical capacities to explain their diversity and behaviour both in vivo and in vitro. We also highlight new biochemical techniques, such as quantum chemistry, metabolomics and crystallography, which could lead to major advances in their chemical and functional characterisation. We then focus on ommochromasome structure and formation by drawing parallels with the well-characterised melanosomes of vertebrates. The biochemical, genetic, cellular and microscopic tools that have been applied to melanosomes should provide important information on the ommochromasome life cycle. We propose LRO-based models for ommochromasome biogenesis and recycling that could be tested in the future. Using the context of insect compound eyes, we finally emphasise the importance of an integrated approach in understanding the biological functions of ommochromes.

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Section: Ommochromes Within the Cell: The Ommochromasome Life Cyclementioning

confidence: 99%

Ommochromes in invertebrates: biochemistry and cell biology

2018

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“…The carrier frequency was much greater than the first resonant frequency of the cantilever (typically MHz frequencies were used), while the variation of the slower modulation frequency (typically a few kHz) was measured by the detection apparatus. The output of lock-in amplifier can also provide information about elastic and adhesive properties of the surface and subsurface features [30,31] (see supplementary materials available online at stacks.iop.org/NANO/30/ 075502/mmedia for further discussion of this application of UFM).…”

Section: Experimental Methodologymentioning

confidence: 99%

Mechanisms of friction reduction of nanoscale sliding contacts achieved through ultrasonic excitation

Sharahi¹,

Egberts²,

Kim³

2018

Nanotechnology

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Friction reduction is an important issue for proper functioning of nano-/micro-electromechanical systems (N-/MEMS) due to their large surface to volume ratios and the inability of traditional liquid lubricants to effectively lubricate sliding contacts. One efficient technique to achieve substantially lowered friction at nanoscale, as well as superlubricity in some instances, was investigated with the coupling of ultrasonic actuation of the sliding contact in an atomic force microscope (AFM). Despite the successful application of ultrasonic AFM methods in achieving mechanical property measurements and nanoscale subsurface imaging of soft and hard materials, the mechanism of friction reduction in the microscopic contact and the influence of the ultrasonic parameters on friction reduction are still elusive. In this study, the effects of excitation amplitude, applied normal force, tip radius, and humidity on friction have been investigated in detail. Ultrasonic force microscopy (UFM) results are compared against those collected with conventional contact-AFM (C-AFM) and indicate that a reduction in the adhesive interaction between the tip and sample, as well as a reduction in the shear strength can explain the mechanisms of the friction reduction in UFM method. This study opens up a new door for the control of friction and wear, which is critical for the increased lifetime of AFM probes, N-/MEMS devices and would potentially bridge the gap between nanotribology and other fields, such as nanomachining, nanolithography and biomaterials imaging.

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“…AFM studies typically show melanin particle aggregates (≈100–200 nm) of smaller particles (≈1–10 nm) that either assemble into larger particles in natural samples, or are deposited as thin films on substrates for more applied studies. AFM has been used to analyze melanins from a variety of sources including: synthetic melanins (e.g., based on l ‐DOPA, [ 514–518 ] DHI, [ 229,519 ] DHICA, [ 520 ] DHI and DHICA, [ 521 ] DHN [ 522 ] ); Nigella sativa ; [ 412 ] fungi (Aspergillus fumigatus [ 484 ] ); cuttlefish ( Sepia officinalis [ 201,523,524 ] ), various other cephalopods species ( Sepia esculenta , Sepia lycidas , Sepia pharaonis , Sepiella japonica , Euprymna berryi , and Uroteuthis ( Photololigo ) edulis [ 525 ] ); feathers of black fish crows ( Corvus ossifragus ) and iridescent wild turkeys ( Melleagris gallopavo ), [ 524 ] black human hair, [ 524 ] human neuromelanin, [ 490 ] and human eye melanosomes. [ 189,526 ] Such studies have also enabled the elucidation of features such as the shape and size of melanosomes (e.g., in black hair are ellipsoidal eumelanosomes, whereas those in red hair are mainly spherical pheomelanosomes [ 527 ] ), and the presence of cosmetic residues on the surface of hair.…”

Section: Analysis Of Melaninsmentioning

confidence: 99%

Melanins as Sustainable Resources for Advanced Biotechnological Applications

et al. 2020

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Melanins are a class of biopolymers that are widespread in nature and have diverse origins, chemical compositions, and functions. Their chemical, electrical, optical, and paramagnetic properties offer opportunities for applications in materials science, particularly for medical and technical uses. This review focuses on the application of analytical techniques to study melanins in multidisciplinary contexts with a view to their use as sustainable resources for advanced biotechnological applications, and how these may facilitate the achievement of the United Nations Sustainable Development Goals.

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Morphologies of eumelanins from the ink of six cephalopods species measured by atomic force microscopy

Cited by 4 publications

References 35 publications

Ommochromes in invertebrates: biochemistry and cell biology

Ommochromes in invertebrates: biochemistry and cell biology

Mechanisms of friction reduction of nanoscale sliding contacts achieved through ultrasonic excitation

Melanins as Sustainable Resources for Advanced Biotechnological Applications

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