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This contribution is a histological and scanning electron microscopy study of major flagellar setae of antennules from the most cultured crustacean species, Penaeus vannamei. Antennule samples were collected from females and males of selected species and processed for histological as well as scanning electron microscopy (SEM) evaluation. The histological and SEM description of major setae from antennules, namely aesthetascs, plumose setae, and male spines are presented in detail. A unique sexually dimorphic structure, male spines on the inner (medial) flagella, is reported for the first time in a penaeid shrimp. These spines are robust structures, short and thick with non-permeable cuticle and no terminal pore, innervated by receptor neuron clusters. This histological organization suggests the spines are sensilla for mechanoreception, possibly involved in courtship mechanoreception, complementing chemosensory information from aesthetascs. Additionally, SEM observations of other antennule setae are presented, including asymmetric setae associated with aesthetascs. [ABSTRACT FROM AUTHOR]

Mechanoreceptor organs in hemimetabolous insects are physiologically important not only in the adult insects, but also for sensory functions in the juvenile postembryonic stages. They provide proprioceptive and exteroceptive information, e.g., in locomotion or orientation. In stick insects (Phasmatodea), the subgenual organ complex in the tibia of all legs is an elaborate mechanoreceptor system. This complex contains two chordotonal organs, the subgenual organ and the distal organ. These organs have mainly been studied in adult insects for the neuroanatomy and functional morphology. Here, the sensory organs were investigated in newly hatched Ramulus artemis (Westwood, 1859) to indicate the functional organisation at the beginning of postembryogenesis, when the detection of mechanical stimuli becomes relevant for behaviour. The organs were investigated by axonal tracing for the organ neuroanatomy, innervation, and number of sensilla in the distal organ. In addition, the sensory complex was analysed for the connection by a membrane between the organs. The organs are present after hatching, indicating in particular a possible vibration detection by the subgenual organ. In most cases, the connection between the sensory organs was also present. This indicates the development of sensory neurons and additional tissues during embryogenesis. The sensory neurons in the subgenual organ show a re-organisation, as the dorsal sensilla change from orientation in distal directions to proximal directions. This finding is discussed for implications in vibration detection. The overall results indicate some neuroanatomical modifications during postembryonic development, while the main structures of the subgenual organ complex already originate during embryonic development. [ABSTRACT FROM AUTHOR]

Donna L Kennedy,1,2 Imogen Pateman,1 Andrew SC Rice,3 Caroline M Alexander1,2 1Therapy Department, Imperial College Healthcare NHS Trust, London, UK; 2Human Performance Group, Department of Surgery and Cancer, Imperial College London, London, UK; 3Pain Research Group, Department of Surgery and Cancer, Faculty Medicine, Imperial College London, London, UKCorrespondence: Donna L Kennedy, Therapy Department, Charing Cross Hospital, Fulham Palace Road, London, W6 8RF, United Kingdom, Email d.kennedy@imperial.ac.ukPurpose: Quantitative sensory testing commonly utilizes the unaffected, contralateral side as a control to detect somatosensory dysfunction. There is scant evidence that somatosensory function for the volar dominant and non-dominant hands is equivalent, therefore intra-patient comparisons are unwarranted. This study aimed to identify dominance-related differences in palmar hand somatosensation, thereby determining if the unaffected contralateral hand is a valid comparator in clinical populations.Participants and Methods: With ethical approval (IREC_13_1_10) and informed consent, 110 healthy adult volunteers’ participated in this clinical measurement study. Somatosensory function was assessed with the German Research Network on Neuropathic Pain (DFNS) quantitative sensory testing (QST) protocol. Half of the participants were tested on the dominant hand. Thirteen parameters of thermal and mechanical detection and pain threshold were evaluated at both the dorsal and volar hand (distal middle finger). Tests were performed in the same order and instructions were read from a standardized script. Results for dorsal hand tests were compared to DFNS normative data to confirm participants met study inclusion criteria. Between-group differences for age and sex were investigated with the independent samples t-test and Chi-square test of independence, respectively. Group differences for dominant and non-dominant hands for all 13 continuous QST parameters were investigated with the Mann–Whitney U-test.Results: Data for 106 participants were included in statistical analysis. Fifty percent of participants were tested on the dominant hand [n=53]; there were no differences for age or sex between groups (dominant or non-dominant hand test group). The dominant volar hand was significantly more sensitive to vibration detection threshold than the non-dominant hand (P=0.001). There were no significant differences related to dominance for other DFNS QST measures.Conclusion: For quantitative sensory testing with the DFNS protocol in healthy cohorts, the contralateral, unaffected hand is a valid control, with the exception of vibration detection threshold.Keywords: thermoreception, mechanoreception, vibration, pain, evaluation

The aim of this study was to prevent initial changes in Drosophila melanogaster oocytes under simulated weightlessness and hypergravity at the 2 g level. Phospholipids with polyunsaturated fatty acids in the tail groups (essential phospholipids) at a concentration of 500 mg/kg of nutrient medium were used as a protective agent. Cell stiffness was determined using atomic force microscopy, the change in the oocytes' area was assessed as a mark of deformation, and the contents of cholesterol and neutral lipids were determined using fluorescence microscopy. The results indicate that the administration of essential phospholipids leads to a decrease in the cholesterol content in the oocytes' membranes by 13% (p < 0.05). The stiffness of oocytes from flies that received essential phospholipids was 14% higher (p < 0.05) and did not change during 6 h of simulated weightlessness or hypergravity, and neither did the area, which indicates their resistance to deformation. Moreover, the exposure to simulated weightlessness and hypergravity of oocytes from flies that received a standard nutrient medium led to a more intense loss of cholesterol from cell membranes after 30 min by 13% and 18% (p < 0.05), respectively, compared to the control, but essential phospholipids prevented this effect. [ABSTRACT FROM AUTHOR]

Octopuses integrate visual, chemical and tactile sensory information while foraging and feeding in complex marine habitats. The respective roles of these modes are of interest ecologically, neurobiologically, and for development of engineered soft robotic arms. While vision guides their foraging path, benthic octopuses primarily search "blindly" with their arms to find visually hidden prey amidst rocks, crevices and coral heads. Each octopus arm is lined with hundreds of suckers that possess a combination of chemo- and mechanoreceptors to distinguish prey. Contact chemoreception has been demonstrated in lab tests, but mechanotactile sensing is less well characterized. We designed a non-invasive live animal behavioral assay that isolated mechanosensory capabilities of Octopus bimaculoides arms and suckers to discriminate among five resin 3D-printed prey and non-prey shapes (all with identical chemical signatures). Each shape was introduced inside a rock dome and was only accessible to the octopus' arms. Octopuses' responses were variable. Young octopuses discriminated the crab prey shape from the control, whereas older octopuses did not. These experiments suggest that mechanotactile sensing of 3D shapes may aid in prey discrimination; however, (i) chemo-tactile information may be prioritized over mechanotactile information in prey discrimination, and (ii) mechanosensory capability may decline with age. [ABSTRACT FROM AUTHOR]

Tachinidae is a large family of flies, but studies on its antennal morphology and ultrastructure are still scarce. Thus, the male and female antennae of Neoeuantha aucta (Wiedmann) were studied using scanning electron microscopy. The three antennal segments are densely covered with microtrichia, with postpedicel being the one that carries the greatest diversity of sensilla. In total, eight types of sensillar structures were observed: trichoid, basiconic (three subtypes), coeloconic, chaetic, setiferous plaques, and pedicellar button. The s. trichoid and s. basiconic have a porous wall, indicating a chemoreceptor function. A central pore was found in the pedicellar button, possibly with mechanoreceptor and chemoreceptor function. Another highlight is the numerous sensory pits covered by microtrichia in the postpedicel, housing only one type of sensilla each. Our results were compared with those available for Tachinidae and other families of dipterans, mainly those of Calyptratae, and provide the basis for future investigations in sensory functions related to the behavior of parasitoid flies, as well as for studies of comparative morphology. [ABSTRACT FROM AUTHOR]

The subgenual organ complex in stick insects (Phasmatodea) consists of two mechanosensory chordotonal organs, the subgenual organ and distal organ, both located in the haemolymph channel in the tibia of the stick insects. The subgenual organ is a highly sensitive receptor organ for substrate vibrations, which are transferred in the haemolymph channel, while the distal organ has not yet been studied in detail physiologically. The neuroanatomy of the subgenual organ complex is unique to stick insects. A membrane between both organs occurs in different Phasmatodea - Carausius morosus (Sinety), Sipyloidea sipylus (Westwood) and Oreophoetes peruana (Saussure). Between the two sensory organs, the thin membrane is placed horizontally in the tibia. The present study investigates the species Peruphasma schultei (Conle et Hennemann) (Phasmatodea: Pseudophasmatidae: Pseudophasmatinae) from South America (Peru) as a representative of Pseudophasmatinae, a prominent group of neotropical stick insects, for the functional morphology of the chordotonal organs. The aim is to provide insights on the sensory complex from an additional stick insect species and on the similarity of the functional morphology. The present work revealed that in P. schultei the fine membrane occurs in both female and male individuals and in all leg pairs. The membrane was absent in a few leg preparations analysed, in which there was either a close contact or a gap between the subgenual organ and the distal organ. The presence of a membrane connection hints at a coupling between the sensory organs which is presumably also relevant for the mechanosensory functions, indicating that the distal organ may also respond to substrate vibrations. [ABSTRACT FROM AUTHOR]

It is well‐recognized that blood flow at branches and bends of arteries generates disturbed shear stress, which plays a crucial in driving atherosclerosis. Flow‐generated fluid shear stress (FSS), as one of the key hemodynamic factors, is appreciated for its critical involvement in regulating angiogenesis to facilitate wound healing and tissue repair. Endothelial cells can directly sense FSS but the mechanobiological mechanism by which they decode different patterns of FSS to trigger angiogenesis remains unclear. In the current study, laminar shear stress (LSS, 15 dyn/cm2) was employed to mimic physiological blood flow, while disturbed shear stress (DSS, ranging from 0.5 ± 4 dyn/cm2) was applied to simulate pathological conditions. The aim was to investigate how these distinct types of blood flow regulated endothelial angiogenesis. Initially, we observed that DSS impaired angiogenesis and downregulated endogenous vascular endothelial growth factor B (VEGFB) expression compared to LSS. We further found that the changes in membrane protein, migration and invasion enhancer 1 (MIEN1) play a role in regulating ERK/MAPK signaling, thereby contributing to endothelial angiogenesis in response to FSS. We also showed the involvement of MIEN1‐directed cytoskeleton organization. These findings suggest the significance of shear stress in endothelial angiogenesis, thereby enhancing our understanding of the alterations in angiogenesis that occur during the transition from physiological to pathological blood flow. [ABSTRACT FROM AUTHOR]

Chemical-based interventions are mostly used to control insects that are harmful to human health and agriculture or that simply cause a nuisance. An overreliance on these insecticides however raises concerns for the environment, human health, and the development of resistance, not only in the target species. As such, there is a critical need for the development of novel nonchemical technologies to control insects. Electrocution traps using UV light as an attractant are one classical nonchemical approach to insect control but lack the specificity necessary to target only pest insects and to avoid harmless or beneficial species. Here we review the fundamental physics behind electric fields (EFs) and place them in context with electromagnetic fields more broadly. We then focus on how novel uses of strong EFs, some of which are being piloted in the field and laboratory, have the potential to repel, capture, or kill (electrocute) insects without the negative side effects of other classical approaches. As EF–insect science remains in its infancy, we provide recommendations for future areas of research in EF–insect science. [ABSTRACT FROM AUTHOR]

The aim of this study was to prevent initial changes in Drosophila melanogaster oocytes under simulated weightlessness and hypergravity at the 2 g level. Phospholipids with polyunsaturated fatty acids in the tail groups (essential phospholipids) at a concentration of 500 mg/kg of nutrient medium were used as a protective agent. Cell stiffness was determined using atomic force microscopy, the change in the oocytes’ area was assessed as a mark of deformation, and the contents of cholesterol and neutral lipids were determined using fluorescence microscopy. The results indicate that the administration of essential phospholipids leads to a decrease in the cholesterol content in the oocytes’ membranes by 13% (p < 0.05). The stiffness of oocytes from flies that received essential phospholipids was 14% higher (p < 0.05) and did not change during 6 h of simulated weightlessness or hypergravity, and neither did the area, which indicates their resistance to deformation. Moreover, the exposure to simulated weightlessness and hypergravity of oocytes from flies that received a standard nutrient medium led to a more intense loss of cholesterol from cell membranes after 30 min by 13% and 18% (p < 0.05), respectively, compared to the control, but essential phospholipids prevented this effect.

VLGR1/ADGRV1 (very large G protein‐coupled receptor‐1) is the largest adhesion G protein‐coupled receptor (aGPCR). Mutations in VLGR1/ADGRV1 are associated with human Usher syndrome, the most common form of deaf‐blindness, and also with epilepsy in humans and mice. VLGR1 is expressed almost ubiquitously but is mainly found in the CNS and in the sensory cells of the eye and inner ear. Little is known about the pathogenesis of the diseases related to VLGR1. We previously identified VLGR1 as a vital component of focal adhesions (FAs) serving as a metabotropic mechanoreceptor controls cell spreading and migration. FAs are highly dynamic and turnover in response to internal and external signals. Here, we aimed to elucidate how VLGR1 participates in FA turnover. Nocodazole washouts and live cell imaging of paxillin‐DsRed2 consistently showed that FA disassembly was not altered, but de novo assembly of FA was significantly delayed in Vlgr1‐deficient astrocytes, indicating that VLGR1 is enrolled in FA assembly. In FRAP experiments, recovery rates were significantly reduced in Vlgr1‐deficient FAs, indicating reduced turnover kinetics in VLGR1‐deficient FAs. We showed that VLGR1 regulates cell migration by controlling the FA turnover during their assembly and expect novel insights into pathomechanisms related to pathogenic dysfunctions of VLGR1. [ABSTRACT FROM AUTHOR]

Articular cartilage, composed of collagen type II as a major extracellular matrix and chondrocyte as a unique cell type, is a specialized connective tissue without blood vessels, lymphatic vessels and nerves. This distinctive characteristic of articular cartilage determines its very limited ability to repair when damaged. It is well known that physical microenvironmental signals regulate many cell behaviors such as cell morphology, adhesion, proliferation and cell communication even determine chondrocyte fate. Interestingly, with increasing age or progression of joint diseases such as osteoarthritis (OA), the major collagen fibrils in the extracellular matrix of articular cartilage become larger in diameter, leading to stiffening of articular tissue and reducing its resistance to external tension, which in turn aggravates joint damage or progression of joint diseases. Therefore, designing a physical microenvironment closer to the real tissue and thus obtaining data closer to the real cellular behaviour, and then revealing the biological mechanisms of chondrocytes in pathological states is of crucial importance for the treatment of OA disease. Here we fabricated micropillar substrates with the same topology but different stiffnesses to mimic the matrix stiffening that occurs in the transition from normal to diseased cartilage. It was first found that chondrocytes responded to stiffened micropillar substrates by showing a larger cell spreading area, a stronger enhancement of cytoskeleton rearrangement and more stability of focal adhesion plaques. The activation of Erk/MAPK signalling in chondrocytes was detected in response to the stiffened micropillar substrate. Interestingly, a larger nuclear spreading area of chondrocytes at the interface layer between the cells and top surfaces of micropillars was observed in response to the stiffened micropillar substrate. Finally, it was found that the stiffened micropillar substrate promoted chondrocyte hypertrophy. Taken together, these results revealed the cell responses of chondrocytes in terms of cell morphology, cytoskeleton, focal adhesion, nuclei and cell hypertrophy, and may be beneficial for understanding the cellular functional changes affected by the matrix stiffening that occurs during the transition from a normal state to a state of osteoarthritis.

The subgenual organ complex in the leg of Polyneoptera (Insecta) consists of several chordotonal organs specialized to detect mechanical stimuli from substrate vibrations and airborne sound. In stick insects (Phasmatodea), the subgenual organ complex contains the subgenual organ and the distal organ located distally to the subgenual organ. The subgenual organ is a highly sensitive detector for substrate vibrations. The distal organ has a characteristic linear organization of sensilla and likely also responds to substrate vibrations. Despite its unique combination of sensory organs, the neuroanatomy of the subgenual organ complex of stick insects has been investigated for only very few species so far. Phylogenomic analysis has established for Phasmatodea the early branching of the sister groups Oriophasmata, the Old World phasmids, and Occidophasmata, the New World phasmids. The species studied for the sensory neuroanatomy, including the Indian stick insect Carausius morosus, belong to the Old World stick insects. Here, the neuroanatomy of the subgenual organ complex is presented for a first species of the New World stick insects, the Peruvian stick insect Oreophoetes peruana. To document the sensory organs in the subgenual organ complex and their innervation pattern, and to compare these between females and males of this species and also to the Old World stick insects, axonal tracing is used. This study documents the same sensory organs for O. peruana, subgenual organ and distal organ, as in other stick insects. Between the sexes of this species, there are no notable differences in the neuroanatomy of their sensory organs. The innervation pattern of tibial nerve branches in O. peruana is identical to other stick insect species, although the innervation pattern of the subgenual organ by a single tibial nerve branch is simpler. The shared organization of the organs in the subgenual organ complex in both groups of Neophasmatodea (Old World and New World stick insects) indicates the sensory importance of the subgenual organ but also of the distal organ. Some variation exists in the innervation of the chordotonal organs in O. peruana though a common innervation pattern can be identified. The findings raise the question for the ancestral neuroanatomical organization and innervation in stick insects. [ABSTRACT FROM AUTHOR]

AbstractThe successful return of mammals to aquatic environments presented numerous sensory challenges to overcome.  Aquatic habitats reduced the utility of vision and the type of chemoreception important in terrestrial perception. In several orders, the sense of touch assumed greater importance, especially when enhanced by the development of vibrissal (sensory hair) systems.  Species of two extant orders, Sirenia and Cetacea, lost all of their hairs except for vibrissae. In the former, these hairs cover the entire bodies of the two families, Trichechidae and Dugongidae.  Hairs in adult cetaceans are more constrained (e.g., some river dolphins and baleen whales) and are restricted primarily to rostral regions.  Pinnipeds and sea otters retained their pelage, but in addition have elaborated their mystacial and other facial vibrissae.  High numbers of vibrissal receptors, associated dense innervation, prominence of neural tracts, and hypertrophy of brain areas associated with touch suggest an importance of tactile senses for aquatic mammals.  Experimental testing has demonstrated the exquisite tactile sensitivity of many marine mammal species. Sensory hairs contribute to that tactile sensitivity in both haptic and mechanosensory contexts.  Several, if not most, pinniped species, seals and sea lions, can track prey based on mechanoreception alone.  In this review we will discuss the neurobiological and behavioral evidence for the tactile senses of marine mammals.

In insects, the detection of mechanical stimuli from body movements, airborne sound, substrate vibration, medium flow, or gravity by mechanosensory organs plays an important role. These mechanosenory organs can have complex morphologies with numerous sensilla, and the functional morphology with specific attachments of the sensory neurons to surrounding tissues and structures determines the stimulation. In stick insects, the subgenual organ complex in the tibia of all legs is an elaborate system of two chordotonal organs, which respond to substrate vibrations, and associated tibial campaniform sensilla, which respond to cuticular strain. One chordotonal organ, the distal organ, is characterized by a linear set of sensilla. This distal organ has not been studied for its physiological characteristics in detail, but the attachment or mechanical coupling is functionally important. Here we characterize two aspects of attachment or mechanical coupling of the distal organ: At the dorsal side, the organ is connected to the inner side of the dorsal cuticle by connective tissue, which is shown to also contain the axons of campaniform sensilla. At the proximal end, a fine membrane runs to the adjacent chordotonal organ, the subgenual organ. This membrane spans the tibia in transverse direction. It does not contain neuronal elements, but as a connection between the subgenual and the distal organ, it may influence the mechanosensory activity of these organs. Such a connection is not present in other insects such as locusts or cockroaches and could affect the sensory function in stick insects (e.g., in vibration detection by the subgenual organ) or even couple the two organs, resulting in similar mechanical responses. [ABSTRACT FROM AUTHOR]

The lack of gravitational loading is a pivotal risk factor during space flights. Biomedical studies indicate that because of the prolonged effect of microgravity, humans experience bone mass loss, muscle atrophy, cardiovascular insufficiency, and sensory motor coordination disorders. These findings demonstrate the essential role of gravity in human health quality. The physiological and pathophysiological mechanisms of an acute response to microgravity at various levels (molecular, cellular, tissue, and physiological) and subsequent adaptation are intensively studied. Under the permanent gravity of the Earth, multicellular organisms have developed a multi-component tissue mechanosensitive system which includes cellular (nucleo- and cytoskeleton) and extracellular (extracellular matrix, ECM) "mechanosensory" elements. These compartments are coordinated due to specialized integrin-based protein complexes, forming a distinctive mechanosensitive unit. Under the lack of continuous gravitational loading, this unit becomes a substrate for adaptation processes, acting as a gravisensitive unit. Since the space flight conditions limit large-scale research in space, simulation models on Earth are of particular importance for elucidating the mechanisms that provide a response to microgravity. This review describes current state of art concerning mammalian ECM as a gravisensitive unit component under real and simulated microgravity and discusses the directions of further research in this field. [ABSTRACT FROM AUTHOR]

Insect antennae are actively moveable, multimodal sensory organs: they are sensorimotor systems. As such they are key to a wide range of different behaviours, ranging from spatial orientation, search and exploration to communication. The role of active movement in antennal sensory function has received increasing attention over the past decades. For example, modern tracking techniques revealed different antennal sampling strategies and action ranges, along with their dependence on behavioural context or sensory environment. At the same time, research on species with different antennal morphology now allow comparisons across insect orders, highlighting the significance of structural and motor constraints on antennal function. Finally, studies on sensory acquisition and processing have contributed a wealth of knowledge on distinct submodalities of mechano- and chemoreception. This includes the mechanosensation of posture, movement, gravity, contact location and surface texture, as well as chemosensation of smell and taste. Here, we review our current understanding of insect antennae as sensorimotor systems. In particular, we discuss how their behavioural function (A) depends on active movement, (B) how it is shaped by structural and motor constraints, and (C) how this relates to mechano- and chemoreception. Based on an overview of antennal function and structure we propose a major functional distinction into contact antennae as opposed to non-contact antennae. Focussing on contact antennae, we then address questions about (i) distinct antennal exploration and sampling patterns, (ii) whether and how they change with behavioural context, and (iii) whether and how they differ between sensory modalities. [ABSTRACT FROM AUTHOR]

Solitary bees play a crucial role in ecological systems, contributing to the pollination of crops and wild plants. All females are reproductive, and their habitat requirements include nesting sites, food resources and nesting materials. Although these activities require the ability to detect biotic and abiotic stimuli in the environment, the sensory system of these species is poorly studied. In this study, the antennal sensilla of five solitary bee species belonging to three Apoidea families were investigated using scanning electron microscopy. These included two species of stem-nesting bees, Ceratina cucurbitina (Rossi, 1792) (Apidae) and Osmia scutellaris (Morawitz, 1868) (Megachilidae), and three species of ground-nesting bees, Lasioglossum brevicorne (Schenck, 1870), Lasioglossum leucozonium (Schrank, 1781), and Lasioglossum villosulum (Kirby, 1802) (Halictidae). Thirteen different types of antennal sensilla were identified in females based on their morphological characteristics: sensilla trichodea (subtypes STI, II, III), chaetica (subtypes SchI, II), basiconica (subtypes SBI, II, III, IV), placodea, campaniformia, coeloconica, and ampullacea. Their functional role was discussed and morphology was compared among the species and within the antennal segments in each species. The results provide a baseline for further physiological and behavioural studies to determine the role of antennal sensilla in habitat selection, food search and nesting site selection. • Antennal sensilla are described in females of five species of Apoidea. • Seven types of sensilla and related morphological subtypes are identified using scanning electron microscopy. • Differences in types and distribution are found among ground and stem nesting species. [ABSTRACT FROM AUTHOR]

Evolutionary transitions from terrestrial to aquatic habitats involve major selective shifts in animal signalling systems. Entirely marine snakes face two challenges during underwater social interactions: (1) finding mates when pheromones are diffused by water currents; and, once a mate is located, (2) maintaining contact and co-ordinating mating when tactile cues are diminished by buoyancy force. We explore the potential tactile roles of scale protuberances in the mating of turtle-headed sea snakes [ Emydocephalus annulatus (Hydrophiinae)] by investigating sexual dimorphism in museum specimens (N = 59). In addition to the previously noted rostral spine on the snout, we found that mature males have enlarged structures located on the chin (genial knobs) and near the cloaca (anal knobs). Ultrastructural data indicates that the rostral spine is comprised of thickened epidermal and dermal layers, similar to rugosities on the body, and likely provide stimulation to the female during prodding by the male. In contrast, the genial and anal knobs have dermally derived central cells indicative of enlarged scale mechanoreceptors (i.e. sensilla). We suggest that these mechanoreceptors are critical to mating success: genial knobs may help amorous males orient to the direction of female motion; whereas, and anal knobs likely give somatosensory feedback for cloacal alignment [ABSTRACT FROM AUTHOR]

Using scanning electron microscopy, the structure of the apical surface of epidermal cells in the head skin and epithelium in the oral cavity of the carp Cyprinus carpio specimens, intact and with chronic olfactory and visual deafferentiation, has been studied. It is shown that sensory-deprived fish differ from intact fish by significant changes in the morphology of the apical surface of epidermal cells. The regular ring-shaped pattern on the apical surface of cells is disturbed but complex patterns or lamellar protrusions of ring-shaped ridges appear. The location and orientation character, as well as the density of distribution and the pattern on the apical surface of even neighboring cells can be completely different. A high concentration of cells with the modified apical surface was found in sensory zones of taste and tactile reception. The changes are similar in epidermal cells of the head skin and epithelial cells of the oral cavity. The individual specificity of structural changes in epidermal cells was not found. The possible relationship between the changes in the apical surface of epidermal cells and activation of the skin reception system and other sensory systems is discussed. [ABSTRACT FROM AUTHOR]

Surface-feeding aquatic animals navigate towards the source of water disturbances and must differentiate prey from other environmental stimuli. Medicinal leeches locate prey, in part, using a distribution of mechanosensory hairs along their body that deflect under fluid flow. Leech's behavioral responses to surface wave temporal frequency are well documented. However, a surface wave's temporal frequency depends on many underlying environmental and fluid properties that vary substantially in natural habitats (e.g., water depth, temperature). The impact of these variables on neural response and behavior is unknown. Here, we developed a physics-based leech mechanosensor model to examine the impact of environmental and fluid properties on neural response. Our model used the physical properties of a leech cilium and was verified against existing behavioral and electrophysiological data. The model's peak response occurred with waves where the effects of gravity and surface tension were nearly equal (i.e., the phase velocity minimum). This suggests that preferred stimuli are related to the interaction between fundamental properties of the surrounding medium and the mechanical properties of the sensor. This interaction likely tunes the sensor to detect the nondispersive components of the signal, filtering out irrelevant ambient stimuli, and may be a general property of cilia across the animal kingdom. • Developed physics-based computational model of leech hair sensors. • Wave model stimulates a sensory hair model, which stimulates a spiking neuron model. • Model results match real-world animal behavioral and electrophysiological data. • Model makes predictions about sensor responses to different water depths. • Leech sensors may detect wave components with minimal distortion across distances. [ABSTRACT FROM AUTHOR]

The lack of gravitational loading is a pivotal risk factor during space flights. Biomedical studies indicate that because of the prolonged effect of microgravity, humans experience bone mass loss, muscle atrophy, cardiovascular insufficiency, and sensory motor coordination disorders. These findings demonstrate the essential role of gravity in human health quality. The physiological and pathophysiological mechanisms of an acute response to microgravity at various levels (molecular, cellular, tissue, and physiological) and subsequent adaptation are intensively studied. Under the permanent gravity of the Earth, multicellular organisms have developed a multi-component tissue mechanosensitive system which includes cellular (nucleo- and cytoskeleton) and extracellular (extracellular matrix, ECM) “mechanosensory” elements. These compartments are coordinated due to specialized integrin-based protein complexes, forming a distinctive mechanosensitive unit. Under the lack of continuous gravitational loading, this unit becomes a substrate for adaptation processes, acting as a gravisensitive unit. Since the space flight conditions limit large-scale research in space, simulation models on Earth are of particular importance for elucidating the mechanisms that provide a response to microgravity. This review describes current state of art concerning mammalian ECM as a gravisensitive unit component under real and simulated microgravity and discusses the directions of further research in this field.

Abstract Electrophorus spp. generate high-voltage electric discharges for defense and hunting, and low-voltage electric discharges (as other Gymnotiformes) for electrolocation and communication. Despite intense interest in the unusual electrogenic and electroreceptive capacities of electric eels, the other sensory systems of Electrophorus spp. are relatively poorly known. Here we describe the ontogenetic development and organization of the cephalic lateral-line canals in the lowland electric eel, Electrophorus varii. Preserved specimens of larvae, juveniles, and adults were examined to describe the spatial distribution of the canals and pores. Ontogenetic shifts of the cephalic lateral line formation were observed for each canal and support a hypothesis of non-synchronized development. The morphogenesis of cephalic canals in larvae and juveniles begins just before the onset of exogenous feeding. In adults, the cephalic sensory canals are formed separately from the skull and overlay cranial and mandibular bones and muscles. This study provides the first detailed description of the development and organization of the cephalic lateral-line system in Electrophorus varii.

Electrophorus spp. generate high-voltage electric discharges for defense and hunting, and low-voltage electric discharges (as other Gymnotiformes) for electrolocation and communication. Despite intense interest in the unusual electrogenic and electroreceptive capacities of electric eels, the other sensory systems of Electrophorus spp. are relatively poorly known. Here we describe the ontogenetic development and organization of the cephalic lateral-line canals in the lowland electric eel, Electrophorus varii. Preserved specimens of larvae, juveniles, and adults were examined to describe the spatial distribution of the canals and pores. Ontogenetic shifts of the cephalic lateral line formation were observed for each canal and support a hypothesis of non-synchronized development. The morphogenesis of cephalic canals in larvae and juveniles begins just before the onset of exogenous feeding. In adults, the cephalic sensory canals are formed separately from the skull and overlay cranial and mandibular bones and muscles. This study provides the first detailed description of the development and organization of the cephalic lateral-line system in Electrophorus varii. [ABSTRACT FROM AUTHOR]

Leg chordotonal organs in insects show different adaptations to detect body movements, substrate vibrations, or airborne sound. In the proximal tibia of stick insects occur two chordotonal organs: the subgenual organ, a highly sensitive vibration receptor organ, and the distal organ, of which the function is yet unknown. The distal organ consists of a linear set of scolopidial sensilla extending in the tibia in distal direction toward the tarsus. Similar organs occur in the elaborate hearing organs in crickets and bushcrickets, where the auditory sensilla are closely associated with thin tympanal membranes and auditory trachea in the leg. Here, we document the position and attachment points for the distal organ in three species of stick insects without auditory adaptations (Ramulus artemis, Sipyloidea sipylus, and Carausius morosus). The distal organ is located in the dorsal hemolymph channel and attaches at the proximal end to the dorsal and posterior leg cuticle by tissue strands. The central part of the distal organ is placed closer to the dorsal cuticle and is suspended by fine tissue strands. The anterior part is clearly separated from the tracheae, while the distal part of the organ is placed over the anterior trachea. The distal organ is not connected to a tendon or muscle, which would indicate a proprioceptive function. The sensilla in the distal organ have dendrites oriented in distal direction in the leg. This morphology does not reveal obvious auditory adaptations as in tympanal organs, while the position in the hemolymph channel and the direction of dendrites indicate responses to forces in longitudinal direction of the leg, likely vibrational stimuli transmitted in the leg’s hemolymph. The evolutionary convergence of complex chordotonal organs with linear sensilla sets between tympanal hearing organs and atympanate organs in stick insects is emphasized by the different functional morphologies and sensory specializations.

Spiders show a broad range of motions in addition to walking and running with their eight coordinated legs taking them towards their resources and away from danger. The usefulness of all these motions depends on the ability to control and adjust them to changing environmental conditions. A remarkable wealth of sensory receptors guarantees the necessary guidance. Many facets of such guidance have emerged from neuroethological research on the wandering spider Cupiennius salei and its allies, although sensori-motor control was not the main focus of this work. The present review may serve as a springboard for future studies aiming towards a more complete understanding of the spider's control of its different types of motion. Among the topics shortly addressed are the involvement of lyriform slit sensilla in path integration, muscle reflexes in the walking legs, the monitoring of joint movement, the neuromuscular control of body raising, the generation of vibratory courtship signals, the sensory guidance of the jump to flying prey and the triggering of spiderling dispersal behavior. Finally, the interaction of sensors on different legs in oriented turning behavior and that of the sensory systems for substrate vibration and medium flow are addressed. [ABSTRACT FROM AUTHOR]

It has long been assumed that the elongated rostra (the saws) of sawsharks (family: Pristiophoridae) and sawfish (family: Pristidae) serve a similar function. Recent behavioural and anatomical studies have shed light on the dual function of the pristid rostrum in mechanosensory and electrosensory prey detection and prey manipulation. Here, the authors examine the distributions of the mechanosensory lateral line canals and electrosensory ampullae of Lorenzini in the southern sawshark, Pristiophorus nudipinnis and the longnose sawshark, Pristiophorus cirratus. In both species, the receptive fields of the mechano‐ and electrosensory systems extend the full length of the rostrum indicating that the sawshark rostrum serves a sensory function. Interestingly, despite recent findings suggesting they feed at different trophic levels, minimal interspecific variation between the two species was recorded. Nonetheless, compared to pristids, the pristiophorid rostrum possesses a reduced mechanosensory sampling field but higher electrosensory resolution, which suggests that pristiophorids may not use their rostrums to disable large prey like pristids do. [ABSTRACT FROM AUTHOR]

Animals often rely on different sources of information when making decisions about the environment. Here, we assessed whether two jumping spiders (Salticidae), Trite planiceps and Portia fimbriata , take two different sources of information into account when jumping over water, to which they are averse. Specifically, we investigated whether salticids can assess both mechanical (wind) and visual cues (distance) while jumping from one platform within a pool arena to another. In the first experiment, salticids were exposed to either no wind, low wind speed or high wind speed. Spiders adjusted the horizontal direction of the jump depending on wind presence, such that the wind would favour the jump. Furthermore, independent of wind presence, the vertical trajectory of the jump affected jump outcome (success or failure) in Portia , but not in Trite. In a second experiment, salticids were exposed to intermittent wind in 10 s bouts to assess whether they preferred to jump during bouts without wind. As expected, spiders preferred to jump when there was no wind. Overall, we found that salticids do account for wind conditions when initiating a potentially risky jump, but that sound also affects salticid behaviour before the jump, possibly due to stress. • Animals rely on different information sources when making decisions. • We gauged jumping spider's ability to attend to vision and wind-based cues in jumps. • Spiders used both sources of information to 'calculate' jump trajectories. • Wind affected spider's ability to make careful judgements, suggesting trade-offs. [ABSTRACT FROM AUTHOR]

MicroRNAs (miRNAs, miRs) are short noncoding RNAs that act to repress expression of proteins from target mRNA transcripts. miRNAs influence many cellular processes including stemness, proliferation, differentiation, maintenance, and survival, and miRNA mutations or misexpression are associated with a variety of disease states. The miR-183 family gene cluster including miR-183, miR-96, and miR-182 is highly conserved among vertebrate and invertebrate organisms, and the miRNAs are coordinately expressed with marked specificity in sensory neurons and sensory epithelial cells. The crucial functions of these miRNAs in normal cellular processes are not yet fully understood, but expectedly dependent upon the transcriptomes of specific cell types at different developmental stages or in various maintenance circumstances. This article provides an overview of evidence supporting roles for miR-183 family members in normal biology of the nervous system, including mechanoreception for auditory and vestibular function, electroreception, chemoreception, photoreception, circadian rhythms, sensory ganglia and pain, and memory formation. [ABSTRACT FROM AUTHOR]

Non-nervous auxiliary structures play a significant role in sensory biology. They filter the stimulus and transform it in a way that fits the animal's needs, thereby contributing to the avoidance of the central nervous system's overload with meaningless stimuli and a corresponding processing task. The present review deals with mechanoreceptors mainly of invertebrates and some remarkable recent findings stressing the role of mechanics as an important source of sensor adaptedness, outstanding performance, and diversity. Instead of organizing the review along the types of stimulus energy (force) taken up by the sensors, processes associated with a few basic and seemingly simple mechanical principles like lever systems, viscoelasticity, resonance, traveling waves, and impedance matching are taken as the guideline. As will be seen, nature makes surprisingly competent use of such "simple mechanics". [ABSTRACT FROM AUTHOR]

The role of vision and the lateral‐line system in fish‐screen avoidance behaviours was investigated in shiner surfperch Cymatogaster aggregata and staghorn sculpin Leptocottus armatus. Avoidance experiments were conducted in front of water‐diversion‐type wedge‐wire fish screens in a laboratory flume with a 0.3 m s−1 water velocity. Fish contacted the screens less frequently during the day than night, indicating that fish screen avoidance is visually mediated during the day. Input from the fishes' lateral‐line systems was also blocked with streptomycin‐sulphate treatments during the night to determine if these fishes use mechanoreceptive cues to guide screen avoidance in darkened conditions. Streptomycin‐treated and untreated fish had similar contact rates suggesting that mechanoreceptive guidance was not increasing the fishes' abilities to avoid contact with non‐vibrating screens at night. Fishes were stained with 2‐(4‐(dimethylamino)styryl)‐N‐ethylpyridinium iodide (DASPEI) to assess the streptomycin treatment's effectiveness. We also tested the fishes' ability to avoid contact with the screens at night, when a strobe light or industrial vibrator was operated on the screens, to respectively increase the screen's visual and mechanoreceptory guidance potential. Cymatogaster aggregata contacted the screens significantly less frequently when they were vibrating, compared with their night‐time controls, suggesting useful mechanoreceptive guidance. Leptocottus armatus contacted the screens significantly less frequently under strobe‐light illumination, compared with their night‐time controls, suggesting useful visual guidance. This research should benefit fishery and water‐resource managers, regarding the development of future fish‐protection decisions at screened water diversions. [ABSTRACT FROM AUTHOR]

Vibrational communication is common in insects and often includes signals with prominent frequency components below 200 Hz, but the sensory adaptations for their detection are scarcely investigated. We performed an integrative study of the subgenual organ complex in Troglophilus cave crickets (Orthoptera: Rhaphidophoridae), a mechanosensory system of three scolopidial organs in the proximal tibia, for mechanical, anatomical and physiological aspects revealing matches to low frequency vibration detection. Microcomputed tomography shows that a part of the subgenual organ sensilla and especially the accessory organ posteriorly in this complex are placed closely underneath the cuticle, a position suited to evoke responses to low-frequency vibration via changes in the cuticular strain. Laser-Doppler vibrometry shows that in a narrow low-frequency range the posterior tibial surface reacts stronger to low frequency sinusoidal vibrations than the anterior tibial surface. This finding suggests that the posterior location of sensilla in tight connection to the cuticle, especially in the accessory organ, is adapted to improve detectability of low-frequency vibration signals. By electrophysiological recordings we identify a scolopidial receptor type tuned to 50–300 Hz vibrations, which projects into the central mechanosensory region specialised for processing low-frequency vibratory inputs, and most likely originates from the accessory organ or the posterior subgenual organ. Our findings contribute to understanding of the mechanical and neuronal basis of low-frequency vibration detection in insect legs and their highly differentiated sensory systems. • The accessory organ (AO) is a scolopidial organ in the legs of orthopteroid insects, presumed to detect low frequency vibration signals (< 200 Hz). • In Troglophilus cave crickets, the AO is situated closely underneath the cuticle posteriorly in the proximal tibia. • The mechanical leg response to low-frequency vibration stimuli is stronger at the posterior than at the anterior side of the proximal tibia. • A vibratory receptor neuron was identified in Troglophilus with physiological and anatomical characteristics indicating the origin in the AO. [ABSTRACT FROM AUTHOR]

Hawkmoths (Lepidoptera, Sphingidae) comprise around 1500 species, most of which forage on nectar from flowers in their adult stage, usually while hovering in front of the flower. The majority of species have a nocturnal lifestyle and are important nocturnal pollinators, but some species have turned to a diurnal lifestyle. Hawkmoths use visual and olfactory cues including CO2 and humidity to detect and recognise rewarding flowers; they find the nectary in the flowers by means of mechanoreceptors on the proboscis and vision, evaluate it with gustatory receptors on the proboscis, and control their hovering flight position using antennal mechanoreception and vision. Here, we review what is presently known about the sensory organs and sensory-guided behaviour that control feeding behaviour of this fascinating pollinator taxon. We also suggest that more experiments on hawkmoth behaviour in natural settings are needed to fully appreciate their sensory capabilities. [ABSTRACT FROM AUTHOR]

The reduced hindwings of flies, known as halteres, are specialized mechanosensory organs that detect body rotations during flight. Primary afferents of the haltere encode its oscillation frequency linearly over a wide bandwidth and with precise phase-dependent spiking. However, it is not currently known whether information from haltere primary afferent neurons is sent to higher brain centers where sensory information about body position could be used in decision making, or whether precise spike timing is useful beyond the peripheral circuits that drive wing movements. We show that in cells in the central brain, the timing and rates of neural spiking can be modulated by sensory input from experimental haltere movements (driven by a servomotor). Using multichannel extracellular recording in restrained flesh flies (Sarcophaga bullata of both sexes), we examined responses of central complex cells to a range of haltere oscillation frequencies alone, and in combination with visual motion speeds and directions. Haltere-responsive units fell into multiple response classes, including those responding to any haltere motion and others with firing rates linearly related to the haltere frequency. Cells with multisensory responses showed higher firing rates than the sum of the unisensory responses at higher haltere frequencies. They also maintained visual properties, such as directional selectivity, while increasing response gain nonlinearly with haltere frequency. Although haltere inputs have been described extensively in the context of rapid locomotion control, we find haltere sensory information in a brain region known to be involved in slower, higher-order behaviors, such as navigation. [ABSTRACT FROM AUTHOR]

Mechanosensation provides animals with important sensory information in addition to olfaction and gustation during feeding behavior. Here, we used Drosophila melanogaster larvae to investigate the role of softness sensing in behavior and learning. In the natural environment, larvae need to dig into soft foods for feeding. Finding foods that are soft enough to dig into is likely to be essential for their survival. We report that larvae can discriminate between different agar concentrations and prefer softer agar. Interestingly, we show that larvae on a harder surface search for a softer surface using memory associated with an odor, and that they evaluate foods by balancing softness and sweetness. These findings suggest that larvae integrate mechanosensory information with chemosensory input while foraging. Moreover, we found that the larval preference for softness is affected by genetic background. [ABSTRACT FROM AUTHOR]

This study was conducted to determine the senses that facilitate prey detection in the marble goby (Oxyeleotris marmorata) larvae. The ingestion ratios of live (generate chemical and mechanical stimuli) or frozen Artemia nauplii (generate chemical but no mechanical stimuli) by the intact or free neuromast (mechanoreceptor)-ablated O. marmorata larvae (11 mg/L streptomycin treatment before feeding) under the light or dark (fish vision was obstructed) condition were examined. Vision, mechano-, and chemoreceptions were all found to be essential in prey detection of the O. marmorata larvae. Prey movement has a significant influence as a visual stimuli on the O. marmorata larval feeding as the Artemia nauplii ingestion ratio was approximately 40% higher with significant (p = 0.001, d = 3.0), when the intact larvae were fed with the live (78.1 ± 1.5%), rather than the frozen (40.9 ± 2.8%) Artemia nauplii, under the light condition. This result was assured when no significant difference (p = 0.572, d = 0.2) was found between the ingestion ratios of frozen Artemia nauplii by the intact O. marmorata larvae under light and dark conditions. These findings demonstrate that prey detection in the O. marmorata larvae was facilitated by multi-modal senses, allowing O. marmorata larvae to survive in their natural habitats. • Vision is essential in prey detection of O. marmorata larvae. • Mechano- and chemoreceptions are also involved in prey detection of O. marmorata larvae. • O. marmorata larvae are attracted to prey movement. [ABSTRACT FROM AUTHOR]

Flying animals need continual sensory feedback about their body position and orientation for flight control. The visual system provides essential but slow feedback. In contrast, mechanosensory channels can provide feedback at much shorter timescales. How the contributions from these two senses are integrated remains an open question in most insect groups. In Diptera, fast mechanosensory feedback is provided by organs called halteres and is crucial for the control of rapid flight manoeuvres, while vision controls manoeuvres in lower temporal frequency bands. Here, we have investigated the visual-mechanosensory integration in the hawkmoth Macroglossum stellatarum. They represent a large group of insects that use Johnston’s organs in their antennae to provide mechanosensory feedback on perturbations in body position. Our experiments show that antennal mechanosensory feedback specifically mediates fast flight manoeuvres, but not slow ones. Moreover, we did not observe compensatory interactions between antennal and visual feedback.

Surface sensitivity disorders are observed in many diseases of the central and peripheral nervous system. Surface sensitivity thresholds were estimated in healthy individuals and patients with carpal tunnel syndrome. There was a statistically significant (p < 0.001) increase in the sensitivity threshold in the distal phalanx of the index finger in patients with carpal tunnel syndrome as compared to healthy individuals, by evaluating the surface sensitivity by Semmes–Weinstein monofilaments.

It is recognized that the changes in the physical properties of extracellular matrix (ECM) result in fine-tuned cell responses including cell morphology, proliferation and differentiation. In this study, a novel patterned equidistant micropillar substrate based on polydimethylsiloxane (PDMS) is designed to mimic the collagen fiber-like network of the cartilage matrix. By changing the component of the curing agent to an oligomeric base, micropillar substrates with the same topology but different stiffnesses are obtained and it is found that chondrocytes seeded onto the soft micropillar substrate maintain their phenotype by gathering type II collagen and aggrecan more effectively than those seeded onto the stiff micropillar substrate. Moreover, chondrocytes sense and respond to micropillar substrates with different stiffnesses by altering the ECM-cytoskeleton-focal adhesion axis. Further, it is found that the soft substrate-preserved chondrocyte phenotype is dependent on the activation of Wnt/β-catenin signaling. Finally, it is indicated that the changes in osteoid-like region formation and cartilage phenotype loss in the stiffened sclerotic area of osteoarthritis cartilage to validate the changes triggered by micropillar substrates with different stiffnesses. This study provides the cell behavior changes that are more similar to those of real chondrocytes at tissue level during the transition from a normal state to a state of osteoarthritis., (© 2023 Wiley-VCH GmbH.)