A catecholamine freestanding film is discovered to be spontaneously formed at the air–water interface, and the film has unique properties of robust surface adhesiveness, self‐healing, and ...stimuli‐responsive properties. The interfacial film‐producing procedure is a simple single step containing polyamines and catechol(amine)s. It is found that oxygen‐rich regions existing at an air–water interface greatly accelerate the catecholamine crosslinking reaction.
Resilin is an elastomeric protein typically occurring in exoskeletons of arthropods. It is composed of randomly orientated coiled polypeptide chains that are covalently cross-linked together at ...regular intervals by the two unusual amino acids dityrosine and trityrosine forming a stable network with a high degree of flexibility and mobility. As a result of its molecular prerequisites, resilin features exceptional rubber-like properties including a relatively low stiffness, a rather pronounced long-range deformability and a nearly perfect elastic recovery. Within the exoskeleton structures, resilin commonly forms composites together with other proteins and/or chitin fibres. In the last decades, numerous exoskeleton structures with large proportions of resilin and various resilin functions have been described. Today, resilin is known to be responsible for the generation of deformability and flexibility in membrane and joint systems, the storage of elastic energy in jumping and catapulting systems, the enhancement of adaptability to uneven surfaces in attachment and prey catching systems, the reduction of fatigue and damage in reproductive, folding and feeding systems and the sealing of wounds in a traumatic reproductive system. In addition, resilin is present in many compound eye lenses and is suggested to be a very suitable material for optical elements because of its transparency and amorphousness. The evolution of this remarkable functional diversity can be assumed to have only been possible because resilin exhibits a unique combination of different outstanding properties.
Dragonflies count among the most skilful of the flying insects. Their exceptional aerodynamic performance has been the subject of various studies. Morphological and kinematic investigations have ...showed that dragonfly wings, though being rather stiff, are able to undergo passive deformation during flight, thereby improving the aerodynamic performance. Resilin, a rubber‐like protein, has been suggested to be a key component in insect wing flexibility and deformation in response to aerodynamic loads, and has been reported in various arthropod locomotor systems. It has already been found in wing vein joints, connecting longitudinal veins to cross veins, and was shown to endow the dragonfly wing with chordwise flexibility, thereby most likely influencing the dragonfly's flight performance. The present study revealed that resilin is not only present in wing vein joints, but also in the internal cuticle layers of veins in wings of Sympetrum vulgatum (SV) and Matrona basilaris basilaris (MBB). Combined with other structural features of wing veins, such as number and thickness of cuticle layers, material composition, and cross‐sectional shape, resilin most probably has an effect on the vein′s material properties and the degree of elastic deformations. In order to elucidate the wing vein ultrastructure and the exact localisation of resilin in the internal layers of the vein cuticle, the approaches of bright‐field light microscopy, wide‐field fluorescence microscopy, confocal laser‐scanning microscopy, scanning electron microscopy and transmission electron microscopy were combined. Wing veins were shown to consist of up to six different cuticle layers and a single row of underlying epidermal cells. In wing veins of MBB, the latter are densely packed with light‐scattering spheres, previously shown to produce structural colours in the form of quasiordered arrays. Longitudinal and cross veins differ significantly in relative thickness of exo‐ and endocuticle, with cross veins showing a much thicker exocuticle. The presence of resilin in the unsclerotised endocuticle suggests its contribution to an increased energy storage and material flexibility, thus to the prevention of vein damage. This is especially important in the highly stressed longitudinal veins, which have much lower possibility to yield to applied loads with the aid of vein joints, as the cross veins do. These results may be relevant not only for biologists, but may also contribute to optimise the design of micro‐air vehicles.
Gut microbiota represent a potential novel target for future prediabetes and type 2 diabetes therapies. In that respect, niacin has been shown to beneficially affect the host-microbiome interaction ...in rodent models.
We characterized more than 500 human subjects with different metabolic phenotypes regarding their niacin (nicotinic acid NA and nicotinamide NAM) status and their gut microbiome. In addition, NA and NAM delayed-release microcapsules were engineered and examined in vitro and in vivo in two human intervention studies (bioavailability study and proof-of-concept/safety study).
We found a reduced α-diversity and
abundance in the microbiome of obese human subjects associated with a low dietary niacin intake. We therefore developed delayed-release microcapsules targeting the ileocolonic region to deliver increasing amounts of NA and NAM to the microbiome while preventing systemic resorption to avoid negative side effects (e.g., facial flushing). In vitro studies on these delayed-release microcapsules revealed stable conditions at pH 1.4, 4.5, and 6.8, followed by release of the compounds at pH 7.4, simulating the ileocolonic region. In humans in vivo, gut-targeted delayed-release NA but not NAM produced a significant increase in the abundance of
. In the absence of systemic side effects, these favorable microbiome changes induced by microencapsulated delayed-release NA were associated with an improvement of biomarkers for systemic insulin sensitivity and metabolic inflammation.
Targeted microbiome intervention by delayed-release NA might represent a future therapeutic option for prediabetes and type 2 diabetes.
Iridescence is an optical effect that produces angle dependent coloration in animals. Recently, studies have attempted to unveil structures behind such elaborated visual signals and associated ...behaviors in Odonata. Here, we studied males of the Amazonian damselfly Chalcopteryx scintillans, which have hindwings that exhibit pronounced iridescence. This optical feature is used by the damselflies for intra-specific communication during territorial fights and courtship. The main question we addressed was whether male wing structural coloration may predict the outcome of male-male contests. We also studied the wing ultrastructure, in order to reveal the mechanisms that are responsible for wing coloration. Using various microscopal and spectroscopal techniques, we demonstrate that hindwing coloration is derived from two main effects: (1) light interference in the cuticle multilayer and (2) a specific angle dependent light scattering and antireflective properties of the epicuticular wax coverage. The results of our field experiment show that wing pigmentation and the hue of the dorsal surface of the hindwings is correlated with the outcome of territorial contests. This is one of the first studies showing that structural coloration derived from multilayer interference may influence the outcome of intrasexual agonistic interactions. This indicates that multicomponent structural coloration in visually guided insects may be under selective forces of male-male competition for resources and females.
•Structural coloration in an Amazonian damselfly is a result of a multilayered structure.•Male damselflies use the dorsal wing coloration during territorial contests.•Color hue seems to be the wing trait that predicts contest outcome.•Angle dependent structural coloration may be an adaptation to Rainforest light environment.
Octopus suckers are able to attach to any smooth surface and many rough surfaces. Here, we have discovered that the sucker surface, which has been hypothesised to be responsible for sealing the ...orifice during adhesion, is not smooth as previously assumed, but is completely covered by a dense network of hair-like micro-outgrowths. This finding is particularly important because it provides another demonstration of the role of hair-structures in a sealing mechanism in water, similar to that previously described for clingfish and abalones. Moreover, the discovered hairs may provide an additional adhesive mechanism that works in concert with suction. The discovered surface structures might be potentially interesting for biomimetics of novel technical suction cups with improved adhesion capabilities on non-smooth surfaces.
•Genital morphology of the Cassida beetles is described in detail.•The female spermathecal duct is strongly spiralled and variable within a population.•The male flagellum is located in the ...ejaculatory duct at rest and inserted in the female duct.•Contraction of the ejaculatory duct muscles causes flagellum propulsion in the female duct.•Evolution of the flagellum and ejaculatory duct muscles is discussed.
The peculiar phenomenon of hyper-elongation of intromittent organs is well known in a number of insect groups. However, the unresolved questions of how and why such a phenomenon originated independently many times continue to attract biologists’ attention. To be able to detect the evolutionary driving mechanisms that enabled insects to repeatedly acquire such a peculiarity, first of all the structural key features and the mechanics of these organs have to be determined. In the present study, the morphology of the reproductive organs of two species of the beetle genus Cassida, with a special focus on the male structures, was scrutinised in detail during copulation and at rest using different microscopy techniques. We found that the hyper-elongated structure of the intromittent organ, called flagellum, is part of the male ejaculatory duct. When the flagellum is inserted into the female spermathecal duct, longitudinal muscles of the ejaculatory duct, but not the flagellum, are shortened. These results strongly suggest that the contraction of the longitudinal muscles of the ejaculatory duct causes propulsion of the flagellum into the highly spiralled spermathecal duct of the female. The tip of the cuticular flagellum is curled up, which can suggest that its physical properties differ from those of the rest of the flagellum. Considering the preceding modelling studies, this property aids the flagellum in penetrating within the highly spiralled and very variable female duct. Based on our morphological results and in comparison with the morphology of intromittent organs of other beetles, we discuss the evolutionary origin of the hyper-elongation in the Cassida species and propose a hypothesis that explains the independent origin of the hyper-elongation of intromittent organs.
Resilin in Insect Flight Systems Appel, Esther; Michels, Jan; Gorb, Stanislav N.
Advanced functional materials,
08/2023
Journal Article
Recenzirano
Odprti dostop
Abstract
Compared to wingless insects, pterygote insects profit from numerous wing‐related benefits including a wider distribution range, the exploitation of various food resources and the escape ...from water‐ or land‐confined predators. In order to maintain the wings´ functionality, the wing design and resistance to material fatigue are of key importance. This is even more essential for survival when considering that wings are used for millions of wing beat cycles but cannot be repaired and do not contain inner muscles so that their aerodynamic performance is mainly based on passive, structure‐based wing deformations. One of the components serving this purpose is the endowment of certain wing components with the elastomeric protein resilin building stable and complex material composites with the tanned cuticle. Resilin endows the respective structures with, e.g., higher flexibility and compliance and enables elastic energy storage. In this study, the occurrence of resilin in the insect flight system is reviewed based on previous studies of several insect orders including Odonata, Orthoptera, Hymenoptera, Coleoptera, Dermaptera, and Diptera, and the function of resilin is discussed with reference to the respective structures.
The world’s only member of Hemiptera Auchenorrhyncha known to form true galls, the leafhopper Scenergates viridis (Vilbaste) (Cicadellidae), transforms leaves of camelthorn (Alhagi maurorum Medikus, ...Fabaceae) into pod-like chambers, up to 35 mm long, inside which individual leafhoppers develop, mate, and lay eggs. At the study site 40 km SE of Bukhara (Uzbekistan), two generations develop annually. First-instar nymphs cause young leaves to fold along the midrib. The subsequent development takes place inside the tightly closed growing gall, plugged at both ends with a mixture of leafhopper excrement, brochosomes, and crushed exuviae. These plugs act as mechanical barriers and sticky traps for intruders. The inner surface of the gall, lined with brochosomes and wax platelets, is hydrophobic. Adult males emerge from their galls and squeeze into female galls. Fertilized females insert an average of 146 eggs under the gall’s inner epidermis and remain inside, possibly protecting the brood, until they die. The walls of the galls containing eggs are approximately three times thicker than regular leaves. The galls are subject to predation by Gelechiidae caterpillars; the eggs of the leafhopper are parasitized by two species of Trichogrammatidae and one Mymaridae (Hymenoptera), and its larvae by one species of Pipunculidae (Diptera).
Hymenoptera are characterised by the presence of one forewing pair and one hindwing pair. The two wings of each body side are coupled to each other during flight making the morphologically ...four-winged insects functionally two-winged. This coupling is formed by a row of hook-like structures, called hamuli, that are located at the leading edge of the hindwing and interlock with a thickened and recurved margin present at the trailing edge of the forewing. In this study, autofluorescence analyses performed with confocal laser scanning microscopy revealed differences in the exoskeleton material composition of the interlocking structures. While the wing veins and the recurved margin are strongly sclerotised and chitinous, the wing membranes mainly contain the elastomeric protein resilin. The hamuli are composed of sclerotised chitinous material, and each hamulus base is surrounded by and embedded in material that features large proportions of resilin and is located in strongly sclerotised socket-like wing vein structures. This exoskeleton organisation likely allows movements of the hamuli and, in combination with the exoskeleton material gradients visualized in the other interlocking structures, is assumed to guarantee an effective wing coupling and to simultaneously decrease the risk of wear and damage under mechanical loads occurring in flight, coupling and decoupling situations.
•Honeybee wing-interlocking structures feature material composition gradients.•The hook-like hamuli consist of sclerotised chitinous material.•Each hamuli base is surrounded by and embedded in flexible resilin-rich material.•The material composition gradients likely guarantee an effective wing coupling.•The risk of damage and wear is presumably reduced by the material composition gradients.
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