Body Bending Research Articles

Oxidative stress response, epigenetic and behavioral alterations in Caenorhabditis elegans exposed to organophosphorus pesticide quinalphos

Abstract Quinalphos (QP), an organophosphate pesticide is used worldwide in agricultural practices. Extensive use of pesticides creates toxicological and environmental nuisances on non-target organisms, where it severely affects cholinergic neurons in higher animals and also induces Parkinson, Alzheimer's disease and male sterility in humans. This study evaluated the sublethal effects of QP using Caenorhabditis elegans on the endpoints of body bend frequency, head thrash frequency, feeding activity for the assay as toxicity parameters. To assess the molecular-level effect, expression pattern of genes associated with locomotion (unc-47, unc-13), pharyngeal pumping (egl-30), epigenetic modulation (utx-1), and oxidative stress (daf-2, daf-16, age-1 and glod-4) was investigated by semi-quantitative PCR. The LC50 value of QP was 0.0323 mM for 1 h of exposure, and L4-stage worms were exposed to sublethal concentrations of 0.00344 mM. After QP exposure, body bend frequency, head thrash frequency and feeding behavior of worms was significantly decreased. Expression analysis results indicate that QP exposure leads to the up-regulation in expression of some stress genes (daf-16 and glod-4) and pharyngeal pumping (egl-30), while other genes responsible for stress like daf-2 and age-1, locomotion (unc-13 and unc-47) and epigenetic modulation (utx-1) are down-regulated. Subsequently, transgenic worms expressing daf-16::GFP were exposed to QP, where induced expression of DAF-16 was evident. Overall, it appears to recruit daf-2/insulin receptor and daf-16/FOXO-dependent pathways to rescue the animals from QP-mediated oxidative stress. Alterations in the expression of many genes by QP are unveiled for the first time in this study, which could serve as biomarkers for monitoring QP exposure.

Behavioral Role of the Reciprocal Inhibition between a Pair of Mauthner Cells during Fast Escapes in Zebrafish.

During many behaviors in vertebrates, the CNS generates asymmetric activities between the left and right sides to produce asymmetric body movements. For asymmetrical activations of the CNS, reciprocal inhibition between the left and right sides is believed to play a key role. However, the complexity of the CNS makes it difficult to identify the reciprocal inhibition circuits at the level of individual cells and the contribution of each neuron to the asymmetric activity. Using larval zebrafish, we examined this issue by investigating reciprocal inhibition circuits between a pair of Mauthner (M) cells, giant reticulospinal neurons that trigger fast escapes. Previous studies have shown that a class of excitatory neurons, called cranial relay neurons, is involved in the reciprocal inhibition pathway between the M cells. Using transgenic fish, in which two of the cranial relay neurons (Ta1 and Ta2) expressed GFP, we showed that Ta1 and Ta2 constitute major parts of the pathway. In larvae in which Ta1/Ta2 were laser-ablated, the amplitude of the reciprocal IPSPs dropped to less than one-third. Calcium imaging and electrophysiological recording showed that the occurrence probability of bilateral M-cell activation upon sound/vibration stimuli was greatly increased in the Ta1/Ta2-ablated larvae. Behavioral experiments revealed that the Ta1/Ta2 ablation resulted in shallower body bends during sound/vibration-evoked escapes, which is consistent with the observation that increased occurrence of bilateral M-cell activation impaired escape performance. Our study revealed major components of the reciprocal inhibition circuits in the M cell system and the behavioral importance of the circuits.SIGNIFICANCE STATEMENT Reciprocal inhibition between the left and right side of the CNS is considered imperative for producing asymmetric movements in animals. It has been difficult, however, to identify the circuits at the individual cell level and their role in behavior. Here, we address this problem by examining the reciprocal inhibition circuits of the hindbrain Mauthner (M) cell system in larval zebrafish. We determined that two paired interneurons play a critical role in the reciprocal inhibition between the paired M cells and that the reciprocal inhibition prevents bilateral firing of the M cells and is thus necessary for the full body bend during M cell-initiated escape. Further, we discussed the cooperation of multiple reciprocal inhibitions working in the hindbrain and spinal cord to ensure high-performance escapes.

Impact of nuclear distribution element genes in the typical and atypical antipsychotics effects on nematode Caenorhabditis elegans: Putative animal model for studying the pathways correlated to schizophrenia

The nuclear distribution element genes are conserved from fungus to humans. The nematode Caenorhabditis elegans expresses two isoforms of nuclear distribution element genes, namely nud-1 and nud-2. While nud-1 was functionally demonstrated to be the worm nudC ortholog, bioinformatic analysis revealed that the nud-2 gene encodes the worm ortholog of the mammalian NDE1 (Nuclear Distribution Element 1 or NudE) and NDEL1 (NDE-Like 1 or NudEL) genes, which share overlapping roles in brain development in mammals and also mediate the axon guidance in mammalian and C. elegans neurons. A significantly higher NDEL1 enzyme activity was shown in treatment non-resistant compared to treatment resistant SCZ patients, who essentially present response to the therapy with atypical clozapine but not with typical antipsychotics. Using C. elegans as a model, we tested the consequence of nud genes suppression in the effects of typical and atypical antipsychotics. To assess the role of nud genes and antipsychotic drugs over C. elegans behavior, we measured body bend frequency, egg laying and pharyngeal pumping, which traits are controlled by specific neurons and neurotransmitters known to be involved in SCZ, as dopamine and serotonin. Evaluation of metabolic and behavioral response to the pharmacotherapy with these antipsychotics demonstrates an important unbalance in serotonin pathway in both nud-1 and nud-2 knockout worms, with more significant effects for nud-2 knockout. The present data also show an interesting trend of mutant knockout worm strains to present a metabolic profile closer to that observed for the wild-type animals after the treatment with the typical antipsychotic haloperidol, but which was not observed for the treatment with the atypical antipsychotic clozapine. Paradoxically, behavioral assays showed more evident effects for clozapine than for haloperidol, which is in line with previous studies with rodent animal models and clinical evaluations with SCZ patients. In addition, the validity and reliability of using this experimental animal model to further explore the convergence between the dopamine/serotonin pathways and neurodevelopmental processes was demonstrated here, and the potential usefulness of this model for evaluating the metabolic consequences of treatments with antipsychotics is also suggested.

A preliminary mechanical design evaluation of the Wikispeed car: for light-weighting implications

Purpose Road passenger transportation faces a global challenge of reducing environmental pollution and greenhouse gas emissions because of the vehicle weight increases needed to enhance passenger safety and comfort. This paper aims to present a preliminary mechanical design evaluation of the Wikispeed Car (with a focus on body bending, body torsion and body crash) to assess light-weighting implications and improve the vehicle’s environmental performance without compromising safety. Design/methodology/approach For this research, finite element analysis (FEA) was performed to examine the Wikispeed chassis for light-weighting opportunities in three key aspects of the vehicle’s design, namely, for body bending the rockers (or longitudinal tubes), for body torsion (again on the rockers but also the chassis as a whole) and for crash safety – on the frontal crash structure. A two-phase approach was adopted, namely, in phase one, a 3D CAD geometry was generated and in phase, two FEA was generated. The combination of analysis results was used to develop the virtual model using FEA tools, and the model was updated based on the correlation process. Findings The research revealed that changing the specified material Aluminium Alloy 6061-T651 to Magnesium EN-MB10020 allows vehicle mass to be reduced by an estimated 110 kg, thus producing a concomitant 10 per cent improvement in fuel economy. The initial results imply that the current beam design made from magnesium would perform worst during a crash as the force required to buckle the beam is the lowest (between 95.2 kN and 134 kN). Steel has the largest bandwidth of force required for buckling and also requires the largest force for buckling (between 317 kN and 540 kN). Originality/value This is the first study of its kind to compare and contrast between material substitution and its impact upon Wikispeed car safety and performance.

Design of a Novel Single-Angle Inclination HTS Maglev Train PMG Turnout

High-temperature superconducting (HTS) magnetic levitation vehicles are one of the next-generation high-level magnetic levitation (Maglev) transportation systems. With the development of high-temperature superconducting materials technology, in the future HTS Maglev train will be vigorously developed. The non-contact wheel–rail system causes many difficulties for the turnout system. In this paper, a novel mechanical permanent magnetic guideway (PMG) turnout system is proposed utilizing a single inclination permanent magnet (PM) for PMG turnout. To assemble the PMG turnout with the proposed single inclination PMs, the wedge-shape air gap between two fixed PMs is used to adjust the PMG body bending in the horizontal plane for Maglev vehicle guideway switching purposes. The relationship of the geometric dimensions of the single inclination PM and its inclination angle and the negative turning radius of the PMG turnout is successfully derived. The magnetic field uniformity of the PMG turnout under the condition of the minimum turning radius of 4 meters, which responds to angle 1.1459° of the single inclination PMs, has been simulated by the finite element method. The calculation results show that the influences of the wedge air gap on the magnetic field uniformity along the PMG longitude direction are small despite the turnout PMG being in a straight state or in a switching state. There are only minor differences in the magnetic fields on both sides of the PMG between the normal PMG and the turnout PMG in straight state and in switching state and so may not influence the HTS Maglev vehicles running stability during the PMG switching operation.

Effect of ionic strength on bioaccumulation and toxicity of silver nanoparticles in Caenorhabditis elegans

The behavior of silver nanoparticles (AgNPs) is influenced by environmental factors which altered their bioaccumulation and toxicity. In this study, we comprehensively investigated the influence of ionic strength on the ecotoxicity of AgNPs to Caenorhabditis elegans (C. elegans) through the transfer from Escherichia coli (E. coli). Three different exposure media (deionized water, EPA water and KM) were used to pretreat AgNPs. E. coli was then exposed to these transformed AgNPs and fed to C. elegans. Our results indicated that ionic strength significantly enhanced the reproductive toxicity (germ cell corpses, brood size and lifespan) and neurotoxicity (head trash and body bend) of AgNPs in C. elegans. Moreover, ICP-MS analysis showed that higher ionic strength increased bioaccumulation of AgNPs in E. coli and the resulting Ag body burden of E. coli affected the transfer of AgNPs to C. elegans, which might be responsible for the increased toxicity to nematodes. Furthermore, we also found that the reactive oxygen species (ROS) level in C. elegans was significantly increased after exposed to E. coli contaminated with ionic strength-treated AgNPs, which might play another important role for the enhanced toxicity of AgNPs. Overall, this study showed that the bioavailability and potential ecotoxicity of AgNPs are associated with the environmental factors.

Anti-parasitic effects of water-soluble alkaloid fractions from ethanolic extracts of Sophora moorcroftiana seeds in Caenorhabditis elegans

Parasite infections of humans and animals remain a major global health problem, with limited choice of drugs being available to the treatment of parasitosis in the clinic. Sophora moorcroftiana (S. moorcroftiana) is a shrub that grows in Tibet Plateau of China. Decoction of the seeds has been used as a traditional Tibetan medicine to treat parasitosis for years. But the anti-parasitic effects of water-soluble fractions in the seeds need further investigation. In the present study, the water-soluble alkaloid fractions (E2) were obtained from S. moorcroftiana seeds by refluxing extraction with 60% ethanol and low polarity fraction (E2-a) and high polarity fraction (E2-b) were subsequently isolated from E2 using column chromatography. As a parasite model, Caenorhabditis elegans (C. elegans) were treated with different fractions and their survivals were recorded. The results showed that that E2-a induced a lower survival rate in C. elegans than E2-b and E2. The protoscoleces of Echinococcus granulosus (E. granulosus) were cultured in the presence of E2-a. Compared with E2-b and E2, protoscoleces exhibited decreased survival rate following E2-a treatment. Furtherly, the effects of E2-a on the behavior, brood size, and lifespan of the worms were investigated. Body bend frequencies of the worms treated with the high concentration of E2-a were reduced by two-thirds compared with the control group (P < 0.01). Compared with non-E2-a-treated group, exposure of nematodes to E2-a led to a decrease in head thrashes and pharyngeal pumps frequency (P < 0.01). E2-a treatment resulted in a significantly lower brood size (P < 0.01). Additional E2-a treatment induced a significantly shortened lifespan, compared with the control (P < 0.05). These findings indicated that water-soluble fraction E2-a from S. moorcroftiana seeds was a potential helminthic agent.

Gliadin intake induces oxidative-stress responses in Caenorhabditis elegans

Clinical attention to gluten-related disorders, such as celiac disease and nonceliac gluten sensitivity, is on the rise. However, identifying the pathophysiological mechanisms of gluten-related disorders remains elusive. Gliadin, a component of gluten, is known to play a major role in gluten toxicity. Caenorhabditis elegans has been widely used as the predominant experimental animal model to study toxicity and stress response in biomedical research. We investigated the stress response induced by gliadin intake in C. elegans to evaluate its toxicity and found brood size, body bending, and pumping rates to be significantly altered in response to gliadin. Notably, reactive oxygen species (ROS) production and Pgst-4::GFP transgene expression, an indicator of the oxidative-stress response, were significantly increased after gliadin intake. Reduced pumping rates were most likely caused by gliadin-induced oxidative stress, since pumping rates in oxidative stress-sensitive mev-1 mutants were more severely reduced than in oxidative stress-resistant daf-2 mutants following gliadin intake. Our results indicated that gluten/gliadin intake in C. elegans triggered ROS production and induced an oxidative stress response that reduced pumping rates and decreased brood size. We suggest C. elegans to be a useful model system for studying gluten/gliadin toxicity.

Active and species-specific dispersal behaviour in a marine nematode cryptic species complex

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 600:71-83 (2018) - DOI: https://doi.org/10.3354/meps12658 Active and species-specific dispersal behaviour in a marine nematode cryptic species complex N. De Meester1,2,*, T. Van Daele1, J. Van Malderen1, L. Monteiro1, C. Van Colen1, S. Derycke1,2,3, T. Moens1 1Marine Biology Unit, Department of Biology, Ghent University, Gent 9000, Belgium 2Center for Molecular Phylogeny and Evolution, Ghent University, Gent 9000, Belgium 3Aquatic Environment and Quality, Research Institute for Agriculture, Fisheries and Food, Oostende 8400, Belgium *Corresponding author: nele.demeester@ugent.be ABSTRACT: Dispersal is a 3-step process, consisting of a departure, transience and settlement step. In marine nematodes, dispersal is expected to be passive because nematodes lack an active planktonic phase. The transoceanic distribution of several species suggests effective large-scale dispersal. Nevertheless, it remains unclear whether nematodes can actively influence their dispersal and whether species-specific differences exist. Such differences could contribute to the commonly observed co-existence of ecologically similar species. Three separate experiments were conducted on 4 species of the cryptic species complex of Litoditis marina (Pm I, Pm II, Pm III and Pm IV) to test the effect of species identity and behaviour in the dispersal steps. A flume experiment demonstrated that nematode emergence increased with increasing flow speed and that they could also actively emerge from decomposing algae (departure step). Movement analysis of nematodes in seawater highlighted behaviour which contributes to the transience step. The settlement experiment demonstrated that L. marina can choose on which substratum to settle in still water. Species-specific differences were found in the departure and transience steps. In the departure step, Pm IV exhibited more active behaviour than Pm I. In the transience step, Pm II and Pm IV showed the highest body bend frequency. These species-specific differences correspond with geographical distribution patterns, which are smaller in the species with weaker dispersal behaviour, and lend support to the idea that dispersal can facilitate coexistence of closely related species through a trade-off between competition and dispersal. KEY WORDS: Active dispersal · Cryptic species · Nematodes Full text in pdf format PreviousNextCite this article as: De Meester N, Van Daele T, Van Malderen J, Monteiro L, Van Colen C, Derycke S, Moens T (2018) Active and species-specific dispersal behaviour in a marine nematode cryptic species complex. Mar Ecol Prog Ser 600:71-83. https://doi.org/10.3354/meps12658 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 600. Online publication date: July 30, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Role of tyramine in calcium dynamics of GABAergic neurons and escape behavior in Caenorhabditis elegans

BackgroundTyramine, known as a “trace amine” in mammals, modulates a wide range of behavior in invertebrates; however, the underlying cellular and circuit mechanisms are not well understood. In the nematode Caenorhabditis elegans (C. elegans), tyramine affects key behaviors, including foraging, feeding, and escape responses. The touch-evoked backward escape response is often coupled with a sharp omega turn that allows the animal to navigate away in the opposite direction. Previous studies have showed that a metabotropic tyramine receptor, SER-2, in GABAergic body motor neurons controls deep body bending in omega turns. In this study, we focused on the role of tyramine in GABAergic head motor neurons. Our goal is to understand the mechanism by which tyraminergic signaling alters neural circuit activity to control escape behavior.ResultsUsing calcium imaging in freely moving C. elegans, we found that GABAergic RME motor neurons in the head had high calcium levels during forward locomotion but low calcium levels during spontaneous and evoked backward locomotion. This calcium decrease was also observed during the omega turn. Mutant analyses showed that tbh-1 mutants lacking only octopamine had normal calcium responses, whereas tdc-1 mutants lacking both tyramine and octopamine did not exhibit the calcium decrease in RME. This neuromodulation was mediated by SER-2. Moreover, tyraminergic RIM neuron activity was negatively correlated with RME activity in the directional switch from forward to backward locomotion. These results indicate that tyramine released from RIM inhibits RME via SER-2 signaling. The omega turn is initiated by a sharp head bend when the animal reinitiates forward movement. Interestingly, ser-2 mutants exhibited shallow head bends and often failed to execute deep-angle omega turns. The behavioral defect and the abnormal calcium response in ser-2 mutants could be rescued by SER-2 expression in RME. These results suggest that tyraminergic inhibition of RME is involved in the control of omega turns.ConclusionWe demonstrate that endogenous tyramine downregulates calcium levels in GABAergic RME motor neurons in the head via the tyramine receptor SER-2 during backward locomotion and omega turns. Our data suggest that this neuromodulation allows deep head bending during omega turns and plays a role in the escape behavior in C. elegans.

Age-induced diminution of free radicals by Boeravinone B in Caenorhabditis elegans.

Oxidative damage is accrual of molecular deterioration from reactive oxygen species (ROS) while decrease in generation of ROS is related with free radical scavenging enzymes. Boerhaavia diffusa L. (Nyctaginaceae) derived novel molecule Boeravinone B (BOB) possesses a variety of pharmacological activities, yet their anti-aging potential has not been explored. The aim of the present study was to elucidate the mechanism of BOB mediated oxidative stress resistance and lifespan extension in Caenorhabditis elegans. The results showed that the BOB significantly extends the lifespan of C. elegans with its anti-oxidative potential via reducing accumulation of reactive oxygen species (ROS). BOB was found to recover the shortened lifespan of oxidative stress prone mutants mev-1 and gas-1 (14.75 and 16.11%, respectively). Additionally, this finding supported by the reduced ROS levels seen in BOB treated worms. Further, the effective concentration of BOB (25 μM) significantly enhanced the expressions of target genes such as superoxide dismutase (SOD-3), glutathione-S-transferase (GST-4) and heat shock protein (HSP-16.2) fused to green fluorescent protein (GFP), and it does so by modulating the stress-related signaling pathways (SEK-1) and transcription factors (SKN-1/Nrf and DAF-16/Foxo). Moreover, BOB exposure (25 μM) caused significant changes of age-dependent biomarkers such as pharyngeal pumping, body bend, locomotor activity and lipofuscin accumulation were also showed that BOB retards the aging. Overall, the findings highlight the antioxidant supplement triggering pharmaceutical potential of BOB which may serve as a new future perspective for healthy aging or delayed onset of oxidative related diseases.

Biomechanical Analysis of Posture and Movement Coordination in Standing Humans during Bending of the Trunk in the Sagittal Plane

Achievement of the behavioral aim of most motor acts requires coordination of posture and movement. We report here our studies of this coordination using body bending in the sagittal plane in standing humans as an example. These movements are particularly complex to study, as both components of the motor act (the main component, with the aim of producing a behavioral result, i.e., bending per se, and the “accessory” postural component, i.e., with the aim of maintaining balance during the movement) include movements of large body parts, which hinders the separation of these two components. These were discriminated on the basis of current views of the features of postural components as compared with those of the main target component. The main and postural components were shown to correspond to movements along the eigenvectors of the dynamic equation. These movements were unique, as they simultaneously demonstrated both “kinematic” and “dynamic” synergies, so they were termed “natural synergies.” The coordination of natural synergies in conditions of standing on wide and narrow supports was studied. The experimentally observed coordination was found to be close to the optimum coordination providing minimal movements of the center of pressure. This guarantees maintenance of the position of the center of pressure within the support area, as required to maintain balance.

The UBR-1 ubiquitin ligase regulates glutamate metabolism to generate coordinated motor pattern in Caenorhabditis elegans.

UBR1 is an E3 ubiquitin ligase best known for its ability to target protein degradation by the N-end rule. The physiological functions of UBR family proteins, however, remain not fully understood. We found that the functional loss of C. elegans UBR-1 leads to a specific motor deficit: when adult animals generate reversal movements, A-class motor neurons exhibit synchronized activation, preventing body bending. This motor deficit is rescued by removing GOT-1, a transaminase that converts aspartate to glutamate. Both UBR-1 and GOT-1 are expressed and critically required in premotor interneurons of the reversal motor circuit to regulate the motor pattern. ubr-1 and got-1 mutants exhibit elevated and decreased glutamate level, respectively. These results raise an intriguing possibility that UBR proteins regulate glutamate metabolism, which is critical for neuronal development and signaling.

MODELING OF LATERALLY SUPPORTED EMBEDDED STRUCTURES

At lateral load-displacement response of embedded structures, the subgrade reaction method is most extensively used because the nonlinearity of soil and variation of subgrade reaction with depth can be considered relatively easily. In this method, the laterally loaded embedded structure is idealized as a beam on an elastic foundation loaded transversely and restrained by independent elastic springs acting along the length of the beam. The actual subgrade reaction distribution and the structure displacements are not dependent only on the soil stiffness but are rather a result of the mutual relationship between the structural element stiffness and the soil stiffness. A simplified distribution of springs and its stiffness coefficients is presented in this study. Through decoupling the embedded structure deformations into rigid body movement and bending deformation, the subgrade reaction modulus is estimated depending on experimental data of rigid wall movement and its accompanier ultimate passive earth pressure from literatures. The produced structural analysis results using the developed model are in a good agreement comparing with the analytical and numerical results. In addition, a parametric study is carried out, which shows that the effect of structure stiffness is more significant than the soil stiffness and with regarding the economical design is fulfilled by using flexible structural elements than the rigid one when the displacement limits is regarded.

Nociceptive interneurons control modular motor pathways to promote escape behavior in Drosophila.

Rapid and efficient escape behaviors in response to noxious sensory stimuli are essential for protection and survival. Yet, how noxious stimuli are transformed to coordinated escape behaviors remains poorly understood. In Drosophila larvae, noxious stimuli trigger sequential body bending and corkscrew-like rolling behavior. We identified a population of interneurons in the nerve cord of Drosophila, termed Down-and-Back (DnB) neurons, that are activated by noxious heat, promote nociceptive behavior, and are required for robust escape responses to noxious stimuli. Electron microscopic circuit reconstruction shows that DnBs are targets of nociceptive and mechanosensory neurons, are directly presynaptic to pre-motor circuits, and link indirectly to Goro rolling command-like neurons. DnB activation promotes activity in Goro neurons, and coincident inactivation of Goro neurons prevents the rolling sequence but leaves intact body bending motor responses. Thus, activity from nociceptors to DnB interneurons coordinates modular elements of nociceptive escape behavior.

General principles of control method of passenger car bodies bending vibration parameters

Weight reduction of passenger cars is a promising direction of reducing the cost of their production and increasing transportation profitability. One way to reduce the weight of passenger cars is the lightweight metal body design by means of using of high-strength aluminum alloys, low-alloy and stainless steels. However, it has been found that the limit of the lightweight metal body design is not determined by the total mode of deformation, but its flexural rigidity, as the latter influences natural frequencies of body bending vibrations. With the introduction of mandatory certification for compliance with the Customs Union technical regulations, the following index was confirmed: “first natural frequency of body bending vibrations in the vertical plane”. This is due to the fact that vibration, noise and car motion depend on this index. To define the required indexes, the principles of the control method of bending vibration parameters of passenger car bodies are proposed in this paper. This method covers all stages of car design – development of design documentation, manufacturing and testing experimental and pilot models, launching the production. The authors also developed evaluation criteria and the procedure of using the results for introduction of control method of bending vibration parameters of passenger car bodies.

Extracellular Matrix Elasticity Regulates Osteocyte Gap Junction Elongation: Involvement of Paxillin in Intracellular Signal Transduction

Background/Aims: Osteocytes can sense and respond to extracellular stimuli, including biochemical factors throughout the cell body, dendritic processes, and cilia bending. However, further exploration is required of osteocyte function in response to substrate stiffness, an important passive mechanical cue at the interface between osteocytes and the extracellular matrix, and the deep bio-mechanism in osteocytes involving mechanosensing of cell behavior. Methods: We fabricated silicon-based elastomer polydimethylsiloxane substrates with different stiffnesses but with the same surface topologies. We then seeded osteocytes onto the substrates to examine their responses. Methodologies used included scanning electron microscopy (SEM) for cell morphology, confocal laser scanning microscopy (CLSM) for protein distribution, western blot for protein levels, co-immunoprecipitation for protein interactions, and quantitative real-time polymerase chain reaction for gene expression. Results: SEM images revealed that substrate stiffness induced a change in osteocyte morphology, and CLSM of F-actin staining revealed that substrate stiffness can alter the cytoskeleton. These results were accompanied by changes in focal adhesion capacity in osteocytes, determined via characterization of vinculin expression and distribution. Furthermore, on the exterior of the cell membrane, fibronectin was altered by substrate stiffness. The fibronectin then induced a change in paxillin on the inner membrane of the cell via protein–protein interaction through transmembrane processing. Paxillin led to changes in connexin 43 via protein–protein binding, thereby influencing osteocyte gap junction elongation. Conclusion: This process -from mechanosensing and mechanotransduction to cell function - not only indicates that the effects of mechanical factors on osteocytes can be directly sensed from the cell body, but also indicates the involvement of paxillin transduction.

Transparent, Stretchable and Direct Skin-Touchable Multi-Functional Electronic Skin Sensors

Multi-functional electronic skin (e-skin) sensors, which can be directly skin-attachable to human body for normally monitoring the outside illumination environment and the movement situations of human body, can play a vital role in personal health and body rehabilitation. However, multi-functional e-skin sensors with transparency, stretchability, and skin-attachable to human body still keep challenge. In this paper, an optical transparent, low resistivity, good flexibility, light-sensitivity, and biocompatible multilayer film e-skin sensor was fabricated with the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene buried in between silk fibroin (SF) film and poly (dimethylsiloxane) (PDMS) film. The multilayer film e-skin with thickness of 150 μm can light a light-emitting diode (LED) chip under direct current, and the super thin SF film of the e-skin sensor can provide good biocompatibility for human skin due to similar human skin protein structures, and the interpenetrating networks containing the silver nanowire (Ag NW) and the azobenzene can produce an obvious response for UV illumination, human body bending and/or uniaxial tensile. Moreover, the three-sublayer-structured e-skin is low-cost, less equipment-intensive, and easily mass-produced, and be widely used in commercial applications of medicine, bionic-robot, and other wearable electronics.

Toxicity profile of organic extracts from Magdalena River sediments.

The Magdalena River, the main river of Colombia, receives contaminated effluents from different anthropogenic activities along its path. However, the Magdalena River is used as drinking water source for approximately 30 million inhabitants, as well as a major source of fish for human consumption. Only a few studies have been conducted to evaluate the environmental and toxicological quality of the Magdalena River. To evaluate sediment toxicity, wild-type and GFP transgenic Caenorhabditis elegans were exposed to methanolic extracts, and effects on lethality, locomotion, growth, and gene expression were determined based on fluorescence spectroscopy. These biological and biochemical parameters were correlated with measured pollutant concentrations (PAHs and trace elements), identifying patterns of toxicity along the course of the river. Effects on lethality, growth, and locomotion were observed in areas influenced by industrial, gold mining, and petrochemical activities. Changes in gene expression were evident for cyp-34A9, especially in the sampling site located near an oil refinery, and at the seaport, in Barranquilla City. Body bend movements were moderately correlated with Cr and As concentrations. The expression of mtl-1, mtl-2, hsp-6, and hsp-70 were significantly associated with Pb/U, Pb, Sr, and As/Sr/Pb/U, respectively. Interestingly, toxicity of methanolic as well as aqueous extracts were more prone to be dependent on Cd, Zn, and Th. In general, ecological risk assessment showed sediments display low environmental impact in terms of evaluated metals and PAHs. Different types of waste disposal on the Magdalena River, as a result of mining, domestic, agricultural, and industrial activities, incorporate toxic pollutants in sediments, which are capable of generating a toxic response in C. elegans.

Design of a multilink-articulated wheeled pipeline inspection robot using only passive elastic joints

This paper presents a multilink-articulated robot with omni and hemispherical wheels (AIRo-2.1) for inspecting and exploring pipelines. To quickly adapt to winding pipes, holonomic rolling movement without moving forward and backward is useful. However, this requires the rolling actuators to replace the driving actuators at the expense of the driving force. Furthermore, so far the number of driving wheels and torsion springs, magnitude of driving forces, stiffness and natural angle of the spring that are required to adapt to various pipelines have not been clarified. In this paper, we investigate the possibility of high maneuverability of multilink-articulated robots in winding pipes with as few driving actuators as possible and only elastic joints (torsion springs) for body bending. We further validate its effectiveness by experimental verification.