1,721,160 research outputs found
Localization of Phenolic Compounds at an Air-Solid Interface in Plant Seed Mucilage: A Strategy to Maximize Its Biological Function?
No full textGiven a low concentration of phenols in the naturally occurring aqueous lubricant (mucilage) from hydrated seeds, their biological functions should be severely limited. Here, we introduce an undisclosed natural strategy that enables maximization of phenolic functions through exposing the phenols at the air-seed solid interface. Our findings not only offer a new perspective on plant reproduction physiology but also provide insights into an innovative design of lubricating biomaterials with additional phenolic functions.
Terminal contact elements of insect attachment devices studied by transmission X-ray microscopy
No full textFor the first time, the terminal elements (spatulae) of setal ( hairy) attachment devices of the beetle Gastrophysa viridula ( Coleoptera, Chrysomelidae) and the fly Lucilia caesar(Diptera, Calliphoridae) were studied using transmission X-ray microscopy (TXM) with a lateral resolution of about 30 nm. Since images are taken under ambient conditions, we demonstrate here that this method can be applied to study the contact behaviour of biological systems, including animal tenent setae, in a fresh state. We observed that the attached spatulae show a viscoelastic behavior increasing the contact area and providing improved adaptability to the local topography of the surface. The technique can be extended to TXM tomography, which would provide three-dimensional information and a deeper insight into the details of insect attachment structures
Not only for males: the pleon-holding mechanism in female calappids (Crustacea: Decapoda: Brachyura)
No full textAnisotropic Friction: Bioinspired 3D Printed Locomotion Devices Based on Anisotropic Friction (Small 1/2019)
No full textEnhanced Locomotion Efficiency of a Bio-inspired Walking Robot using Contact Surfaces with Frictional Anisotropy
Full text linkBased on the principles of morphological computation, we propose a novel approach that exploits the interaction between a passive anisotropic scale-like material (e.g., shark skin) and a non-smooth substrate to enhance locomotion efficiency of a robot walking on inclines. Real robot experiments show that passive tribologically-enhanced surfaces of the robot belly or foot allow the robot to grip on specific surfaces and move effectively with reduced energy consumption. Supplementing the robot experiments, we investigated tribological properties of the shark skin as well as its mechanical stability. It shows high frictional anisotropy due to an array of sloped denticles. The orientation of the denticles to the underlying collagenous material also strongly influences their mechanical interlocking with the substrate. This study not only opens up a new way of achieving energy-efficient legged robot locomotion but also provides a better understanding of the functionalities and mechanical properties of anisotropic surfaces. That understanding will assist developing new types of material for other real-world applications
Gecko's Feet-Inspired Self-Peeling Switchable Dry/Wet Adhesive
No full textDynamic switchable attachment/detachment behavior can be extensively observed in biological systems. Although wide interest has been focused on the fabrication of biomimetic synthetic switchable adhesives, designing intelligent adhesive material systems under both dry and wet conditions by following a peeling mechanism from mechanical deformation-induced adaptive evolution of the interface geometric contact state is still challenging. Herein, inspired by the rolling behavior of gecko's feet, one kind of novel multilayered self-peeling switchable dry/wet adhesive (SPSA) is developed by integrating thermal-responsive hydrogel layers, gecko's feet-inspired mushroom-structured arrays, and mussel-inspired copolymer adhesive coatings together. The SPSA shows thermal-responsive curving behavior along with switchable dry and underwater adhesion. Theoretical analysis is performed for explaining the dynamic curvature-induced switchable peeling mechanism. By integrating Fe3O4 nanoparticles into the SPSA, remote control over switchable adhesion can be achieved by applying near-infrared laser radiation. Considering potential applications, the SPSA can be used for successfully bonding/separating and capturing/releasing objects in air and in underwater environments. This research provides a new route for developing intelligent adhesion systems and mobile devices/robots.
Comparative study of the morphology of the female seminal receptacles of Ilia nucleus and Persephona mediterranea (Decapoda, Brachyura, Leucosiidae)
No full textBecause of the poor knowledge of the morphology of the female reproductive organs of most brachyuran crabs, this study investigated two Atlantic representatives of the family Leucosiidae, Ilia nucleus (Linnaeus, 1758) and Persephona mediterranea (Herbst, 1794), using histological methods and magnetic resonance imaging (MRI). While the vagina conforms to the concave type, the arrangement of the two chambers of the seminal receptacle differs strongly from that of other eubrachyuran sperm storage organs. Both chambers are oriented laterally within the crab's body. This is in contrast to the dorso-ventral orientation described in most other known brachyuran crabs. The lateral chamber is covered by cuticle, whereas the medial chamber is covered by a holocrine glandular epithelium. The oviduct connection is located ventrally, posterior to the vagina. The oviduct orifice is characterized by a transition from the epithelium lining the oviduct to the seminal receptacle's holocrine glandular epithelium. Moreover, muscle fibres are attached to the oviduct orifice and to the sternal cuticle. This musculature can be interpreted as an important feature in the fertilization and egg-laying process by supporting and controlling the inflow of eggs into the seminal receptacle lumen. The results of this study are compared to the morphology of the seminal receptacle of another leucosiid crab, Ebalia tumefacta (Montagu, 1808), and to those of other known eubrachyuran crabs. (C) 2017 Elsevier Ltd. All rights reserved
The Evolution of Tarsal Adhesive Microstructures in Stick and Leaf Insects (Phasmatodea)
No full textInsects have developed specialized structures on their feet for adhering to surfaces, with stick and leaf insects or Phasmatodea exhibiting an unexpectedly high diversity of these structures. In Phasmatodea, attachment on different substrates is achieved by two types of pads on the legs: the euplantulae on the tarsomeres and the arolium on the pretarsus. The euplantulae are adhesive structures capable of adaptability to the substrate profile and generation of the required attachment strength. The diversity of euplantular microstructures of 56 species that represent all major lineages recognized within Phasmatodea and the whole biogeographical distribution of the group are examined using scanning electron microscopy (SEM). Nine different types of attachment structures can be distinguished whereby one, the nubby type, can be further divided into three different distinct types based on the specific ratio of each conical outgrowth. We mapped the morphological data from the SEM onto a phylogenetic tree we reconstructed based on molecular data. Previously, the evolution of different adhesive microstructures (AMs) on these pads has been suggested to reflect phylogenetic groups. However, different types of AMs are found within monophyletic groups, and our ancestral character state reconstruction suggests smooth euplantulae in the ground pattern of Euphasmatodea and multiple independent origins of other forms. The type of AM appears to be strongly associated with ecomorphs, e.g., smooth euplantular surfaces are more frequently found in tree-dwellers than in ground-dwellers, whilst the attachment pads of ground-dwelling species primarily bear conical cuticular outgrowths (nubby euplantulae)
Shell dissolution state of the thecosome pteropod Limacina helicina antarctica during Polarstern cruise PS111 (ANT-XXXIII/2)
No full textAt high latitudes, thecosome pteropods (marine pelagic mollusks) can dominate zooplankton communities and are important food web components. Due to their calcium carbonate shell made of aragonite, they significantly contribute to ocean carbon flux and are particularly vulnerable to ocean acidification. Aragonite undersaturation (Ωar < 1) events are projected to rapidly increase in frequency and duration in the Antarctic Weddell Sea by 2050 due to uptake of increasing amounts of anthropogenic CO2. This potentially perils thecosomes by inducing shell dissolution. The project aim was to describe the importance of thecosome pteropods in terms of their biomass contribution relative to that of other mesozooplankton groups in the Weddell Sea pelagic ecosystem and to describe the current shell dissolution state of thecosome pteropods in relation to prevailing ocean carbonate chemistry conditions as a benchmark for possible future monitoring of ongoing ocean change processes. This dataset includes the shell dissolution assessment performed on scanning electron microscopy (SEM) pictures of individual thecosome pteropod specimen of the species Limacina helicina antarctica. It also includes accompanying overview pictures of the pteropods taken prior to SEM analysis with a stereomicroscope. Total dissolution severity was assessed based on the occurrence of three severity types of dissolution (Type I, Type II, Type III) on the surface of the protoconch and first two whorls of the individual shells. Along with the dataset individual SEM pictures of each shell (overview and close-ups of the 2nd whorl, 1st whorl and the protoconch) are provided. Individual Pteropods were usually collected from 500–0 m depth during PS111 at the eastern Weddell Sea Shelf and the Filchner-Ronne ice shelf
Leaves that walk and eggs that stick: comparative functional morphology and evolution of the adhesive system of leaf insect eggs (Phasmatodea: Phylliidae)
Full text linkAbstract Phylliidae are herbivorous insects exhibiting impressive cryptic masquerade and are colloquially called “walking leaves”. They imitate angiosperm leaves and their eggs often resemble plant seeds structurally and in some cases functionally. Despite overall morphological similarity of adult Phylliidae, their eggs reveal a significant diversity in overall shape and exochorionic surface features. Previous studies have shown that the eggs of most Phylliidae possess a specialised attachment mechanism with hierarchical exochorionic fan-like structures (pinnae), which are mantled by a film of an adhesive secretion (glue). The folded pinnae and glue respond to water contact, with the fibrous pinnae expanding and the glue being capable of reversible liquefaction. In general, the eggs of phylliids appear to exhibit varying structures that were suggested to represent specific adaptations to the different environments the eggs are deposited in. Here, we investigated the diversity of phylliid eggs and the functional morphology of their exochorionic structure. Based on the examination of all phylliid taxa for which the eggs are known, we were able to characterise eleven different morphological types. We explored the adhesiveness of these different egg morphotypes and experimentally compared the attachment performance on a broad range of substrates with different surface roughness, surface chemistry and tested whether the adhesion is replicable after detachment in multiple cycles. Furthermore, we used molecular phylogenetic methods to reconstruct the evolutionary history of different egg types and their adhesive systems within this lineage, based on 53 phylliid taxa. Our results suggest that the egg morphology is congruent with the phylogenetic relationships within Phylliidae. The morphological differences are likely caused by adaptations to the specific environmental requirements for the particular clades, as the egg morphology has an influence on the performance regarding the surface roughness. Furthermore, we show that different pinnae and the adhesive glue evolved convergently in different species. While the evolution of the Phylliidae in general appears to be non-adaptive judging on the strong similarity of the adults and nymphs of most species, the eggs represent a stage with complex and rather diverse functional adaptations including mechanisms for both fixation and dispersal of the eggs
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