Tail Movements Research Articles

Tail posture and motion in relation to natural behaviour in juvenile and adult pigs

The tail of pigs has been suggested as a welfare indicator as it can provide insight into a pig’s behavioural and emotional states. Tail posture and motion have so far mainly been studied in the context of tail biting behaviour. The aim of this study was to investigate the relationship between pigs’ natural behaviour and their tail posture and tail motion. This was studied in a free-range farm in which tail biting is absent. In total 214 pigs of different age categories were observed individually (sows, gilts, boars, and 6-month old pigs) or by group (6-month and 1-year old pigs) for their tail posture, tail motion and behaviour, using live observations and videos obtained by drone. Results showed that a fully curled tail occurred most during locomotion (P < 0.001); and an actively hanging tail occurred more during foraging (P < 0.001), excavation (P = 0.006), feeding (P = 0.017), receipt of agonistic behaviour (P = 0.036), and non-agonistic social interactions (P = 0.046). A fully curled tail (P < 0.001) and a half curled tail (P < 0.005) occurred least in the group of sows. Tail motion was infrequent (6.7% of observations), and involved mainly loosely wagging, which occurred more during locomotion (P = 0.006) and non-agonistic social interactions (P = 0.006). A higher temperature-humidity index increased the probability of half curled tails (P < 0.001) and loose wagging (P < 0.001), while reducing the probability of active (P < 0.001) and passive hanging tails (P = 0.013). These results provide insight into tail posture and tail motion in pigs under semi-natural conditions, showing especially that hanging tails are not primarily associated with tail biting, and that the use of tail postures for welfare assessment should be in consideration with the context in which the animals are kept.

Zebrafish Embryotoxicity and Teratogenic Effects of Christia vespertilionis Leaf Extract

Christia vespertilionis or butterfly wings is a traditional medicinal plant used to treat, among others, colds and bronchitis. The plant was also reported to be a remedy for cancer, with several products based on the plant becoming commercially available, raising some safety concerns on its consumption. The present study was carried out to assess the toxic and teratogenic effects of the plant on the embryonic development of zebrafish (Danio rerio) as the animal model. Zebrafish embryos were exposed to 50, 100, 200, 400, and 800 μg/mL of the methanolic leaf extract of C. vespertilionis, starting from 5 to 120 hours post-fertilization (hpf). The median lethal concentration (LC50) value of the extract was determined to be 419.84 μg/mL, which is within the safety limit stipulated by the Organisation for Economic Co-operation and Development (OECD) guideline. However, results from the teratogenicity evaluation revealed multiple signs of developmental defects in embryos exposed to 200 μg/mL and higher concentrations of the extract. The magnitude of the defects was observed to be concentration-dependent. Moreover, no hatching and spontaneous movement of tail coiling were observed at 400 and 800 μg/mL concentrations due to the delayed growth and early mortality, respectively. A significant reduction in heartbeat rate was also reported for the surviving embryos at the 400 μg/mL test concentration. The present study has provided preliminary results on the potentially toxic and teratogenic effects of the extract at high concentrations.

Moving forwards, sideways and up in the air: observations on the locomotion of semiterrestrial tadpoles (Cycloramphidae)

Abstract Semiterrestrial tadpoles live on wet rock surfaces and have evolved independently in at least seven anuran families. They have a flat venter, laterally compressed keratinized jaws and elongated, largely finless tails. When threatened, they can jump. Here, we describe the kinematics of locomotion for semiterrestrial tadpoles of the genera Cycloramphus and Thoropa (Cycloramphidae). Forward locomotion can be accomplished solely by the upper jaw cyclically engaging and disengaging from the substrate. Undulating tail movements, in contrast, cause the tadpoles to move laterally, like sidewinding snakes, rather than forwards. Jumping is an explosive escape behaviour with an unpredictable trajectory. Jumping requires rapid elevation of the head and extension of the torso and tail. This is made possible by epaxial musculature that extends onto the cranium and movement of the tail in the sagittal plane. Tadpoles near metamorphosis extend their hindlimbs symmetrically when jumping, even when the limbs are too small to provide thrust. The rapid rostral elevation of the snout, extension of the trunk and symmetrical extension of the hindlimbs is a kinematic pattern shared with post-metamorphic frogs when they jump. This suggests that semiterrestrial tadpoles use essentially the same neural programme as that used by frogs to jump.

The cryoprotective potential of propolis supplemented in frozen-thawed bull semen; biochemical and physiological findings.

In this study, the cryoprotective effect of different doses of propolis (P) on bull semen, which has solid pharmacological properties thanks to its rich phenolic components, was investigated biochemically and physiologically. Semen samples were collected from Simmental breed bulls via the artificial vagina and pooled. After dividing into five groups, control (C: no additive) and four different P (200, 100, 50, and 25 μg/mL) groups, the final concentration was diluted to 16×106 per straw. Semen samples were equilibrated at 4°C for approximately 4 hours, then placed in French straws and frozen. After thawing, sperm motility and kinetic parameters, DNA integrity by single-cell gel electrophoresis, sperm abnormalities by liquid fixation, and lipid peroxidation levels by the colorimetric method was analyzed by Computer-Assisted Semen Analyzer. P added to the diluent showed no effect on motility and kinetic parameters at P25 and P50 (p>0.05), while P100 and P200 had a negative effect (p⟨0.001). The addition of P (25 and 50) showed a treatment effect on tail abnormality compared to C (p⟨0.05). Especially P50 had a positive effect on tail length, tail DNA, and tail movement, while P100 and P200 caused DNA damage (p⟨0.001). MDA levels increased in all P dose groups compared to C (p⟨0.001). This study has clearly demonstrated that P25 and P50 supplements could be used therapeutically to treat sperm tail abnormalities and prevent DNA damage in post-thawed bull sperm.

Revising the Impact and Prospects of Activity and Ventilation Rate Bio-Loggers for Tracking Welfare and Fish-Environment Interactions in Salmonids and Mediterranean Farmed Fish

Behavioral parameters are reliable and useful operational welfare indicators that yield information on fish health and welfare status in aquaculture. However, aquatic environment is still constraining for some solutions based on underwater cameras or echo sounder transmitters. Thus, the use of bio-loggers internally or externally attached to sentinel fish emerges as a solution for fish welfare monitoring in tanks- and sea cages-rearing systems. This review is focused on the recently developed AEFishBIT, a small and light data storage tag designed to be externally attached to fish operculum for individual and simultaneous monitoring of swimming activity and ventilation rates under steady and unsteady swimming conditions for short-term periods. AEFishBIT is a tri-axial accelerometer with a frequency sampling of 50–100 Hz that is able to provide proxy measurements of physical and metabolic activities validated by video recording, exercise tests in swim tunnel respirometers, and differential operculum and body tail movements across fish species with differences in swimming capabilities. Tagging procedures based on tag piercing and surgery procedures are adapted to species anatomical head and operculum features, which allowed trained operators to quickly complete the tagging procedure with a fast post-tagging recovery of just 2.5–7 h in both salmonid (rainbow trout, Atlantic salmon) and non-salmonid (gilthead sea bream, European sea bass) farmed fish. Dual recorded data are processed by on-board algorithms, providing valuable information on adaptive behavior through the productive cycle with the changing environment and genetics. Such biosensing approach also provides valuable information on social behavior in terms of adaptive capacities or changes in daily or seasonal activity, linking respiratory rates with changes in metabolic rates and energy partitioning between growth and physical activity. At short-term, upcoming improvements in device design and accompanying software are envisaged, including energy-harvesting techniques aimed to prolong the battery life and the addition of a gyroscope for the estimation of the spatial distribution of fish movements. Altogether, the measured features of AEFishBIT will assist researchers, fish farmers and breeders to establish stricter welfare criteria, suitable feeding strategies, and to produce more robust and efficient fish in a changing environment, helping to improve fish management and aquaculture profitability.

The Centriole's Role in Miscarriages.

Centrioles are subcellular organelles essential for normal cell function and development; they form the cell’s centrosome (a major cytoplasmic microtubule organization center) and cilium (a sensory and motile hair-like cellular extension). Centrioles with evolutionarily conserved characteristics are found in most animal cell types but are absent in egg cells and exhibit unexpectedly high structural, compositional, and functional diversity in sperm cells. As a result, the centriole’s precise role in fertility and early embryo development is unclear. The centrioles are found in the spermatozoan neck, a strategic location connecting two central functional units: the tail, which propels the sperm to the egg and the head, which holds the paternal genetic material. The spermatozoan neck is an ideal site for evolutionary innovation as it can control tail movement pre-fertilization and the male pronucleus’ behavior post-fertilization. We propose that human, bovine, and most other mammals–which exhibit ancestral centriole-dependent reproduction and two spermatozoan centrioles, where one canonical centriole is maintained, and one atypical centriole is formed–adapted extensive species-specific centriolar features. As a result, these centrioles have a high post-fertilization malfunction rate, resulting in aneuploidy, and miscarriages. In contrast, house mice evolved centriole-independent reproduction, losing the spermatozoan centrioles and overcoming a mechanism that causes miscarriages.

Properties of an attention-grabbing motion signal: a comparison of tail and body movements in a lizard

Animals signals must be detected by receiver sensory systems, and overcome a variety of local ecological factors that could otherwise affect their transmission and reception. Habitat structure, competition, avoidance of unintended receivers and varying environmental conditions have all been shown to influence how animals signal. Environmental noise is also crucial, and animals modify their behavior in response to it. Animals generating movement-based visual signals have to contend with wind-blown plants that generate motion noise and can affect the detection of salient movements. The lizard Amphibolurus muricatus uses tail flicking at the start of displays to attract attention, and we hypothesized that tail movements are ideally suited to this function. We compared visual amplitudes generated by tail movements with push-ups, which are a key component of the rest of the display. We show that tail movement amplitudes are highly variable over the course of the display but consistently greater than amplitudes generated by push-ups and not constrained by viewing position. We suggest that these features, combined with the tail being a light structure that does not compromise other activities, provide an ideal introductory component for attracting attention in the ecological setting in which they are generated.

Morphological differences in tardigrade spermatozoa induce variation in gamete motility

BackgroundFertilization is an event at the beginning of ontogeny. Successful fertilization depends on strategies for uniting female and male gametes that developed throughout evolutionary history. In some species of tardigrades, investigations of reproduction have revealed that released spermatozoa swim in the water to reach a female, after which the gametes are stored in her body. The morphology of the spermatozoa includes a coiled nucleus and a species-specific-length acrosome. Although the mating behaviour and morphology of tardigrades have been reported, the motility of male gametes remains unknown. Here, using a high-speed camera, we recorded the spermatozoon motilities of two tardigrades, Paramacrobiotus sp. and Macrobiotus shonaicus, which have longer and shorter spermatozoa, respectively.ResultsThe movement of spermatozoa was faster in Paramacrobiotus sp. than in M. shonaicus, but the beat frequencies of the tails were equal, suggesting that the long tail improved acceleration. In both species, the head part consisting of a coiled nucleus and an acrosome did not swing, in contrast to the tail. The head part of Paramacrobiotus sp. spermatozoa swung harder during turning; in contrast, the tail of M. shonaicus moved more widely than the head. Finally, after mating, the spermatozoa that reached the female aggregated around the cloaca while waiting to enter her body in both tested species.ConclusionsThis study provides results for the first observations and analyses of individual spermatozoon motility in tardigrades. A comparison of the spermatozoon movements of the two tardigrades suggested that the motilities of the male gametes were affected by morphological differences, where the longer spermatozoa swam faster and the shorter ones showed more stable swimming. Swimming was mainly induced by tail movement, but the long head of Paramacrobiotus sp. spermatozoa might be especially important for turning. In addition, observations of mated female cloacae suggested that the head parts of the spermatozoa were required for aggregation around the cloaca of a mated female.

A mouse model of disuse osteoporosis based on a movable noninvasive 3D-printed unloading device.

ObjectiveDisuse osteoporosis is a major type of bone loss disease characterized by regional bone loss and microstructure alterations. The condition is induced by a marked decrease in weight bearing over time, which usually occurs due to limb immobilization, therapeutic bed rest or space flight. To date, the most commonly used mouse model of disuse osteoporosis is constructed using the classical tail suspension method, which causes tail injury, movement inconvenience and mental stress. This study aimed to propose a noninvasive and effective method for the establishment of a mouse model of disuse osteoporosis and compared this method with the tail suspension method.Methods3D printing technology was applied to construct a movable unloading device. A movable noninvasive 3D-printed unloading device (3D-ULD) was used to unload the hindlimbs of the mice. The bone microstructure and bone volume of unloaded femurs were analysed through micro-CT and H&E staining, and von Kossa staining was performed for the detection of bone mineralization in the femurs. TRAP staining, IHC-CTSK and Q-PCR were performed for evaluation of the bone resorption ability, and double labelling, IHC-DMP1, ALP staining and Q-PCR assays were conducted to assess the osteogenic ability. The mechanical properties of disused bone were detected using the three-point bending test. The body, thymus and spleen weights of the mice were recorded, and the serum corticosterone level of the mice was assayed by enzyme-linked immunosorbent assay (ELISA).ResultsThe micro-CT results showed significant trabecular bone loss, and 3D-ULD induced cortical bone loss in disused femurs as well as a decrease in the bone mineral density in the unloaded mice. TRAP staining and IHC-CTSK staining results indicated increases in the osteoclast number per bone perimeter (Oc.N/B.Pm) and the osteoclast surface per bone surface (Oc.S/BS) in the unloaded mice. The Ctsk, Trap and Mmp9 expression levels were significantly increased in the unloaded mice. Decreases in the ratio of the mineral surface to bone surface (MS/BS), mineral apposition rate (MAR) and bone formation rate per bone surface (BFR/BS) were found in unloaded mice in the 3D-ULD by double labelling. The IHC-DMP1 and ALP staining results showed decreases in the osteoblast number per bone perimeter (Ob.N/B.Pm) and osteoblast surface per bone surface (Ob. S/BS) in the mice unloaded in the 3D-ULD, and these mice also showed decreased Runx2, Alp and Dmp1 expression levels. Three-point bending test results showed that the mechanical properties were attenuated in the disused femurs of the unloaded mice. Less skin rupture and rare alterations in the thymus and spleen weights were found in the unloaded mice in the 3D-ULD. The ELISA results indicated the serum corticosterone level of the mice unloaded in the 3D-ULD was significantly lower than that of mice suspended by their tail.ConclusionThis new disuse osteoporosis mouse model based on 3D-ULD could induce effective disuse bone loss with significantly alleviated side effects.Translational potential of this articleThis study proposes a new disuse osteoporosis mouse model based on 3D-ULD that can be used to better understand disuse bone loss in the future.

Amelioration of fly annoyance in dairy cattle by using illuminated fly traps

Blood-sucking and biting flies are a significant source of annoyance to warm-blooded animals. Behavioural changes in animals may include attempts to pursue, remove or avoid the disturbance caused by the fly by means of body movement. In the presesnt study the behaviour during a 10 min period in each four-hour interval i.e. 1 AM, 5 AM, 9 AM, 1 PM, 5 PM and 9 PM was analysed and noted for inclusion in the ethogram. The cows with light trap (treatment) were compared with those without light traps (control) to study the effectivenss of the fly trap in reducing annoyance in cattle. All the seven avaoidance behaviours were counted such as head movement, ear shaking, tail movement, skin twitching, licking, kicking on belly and restlessness and were recorded by scan method. The results of this study indicated that the incidence of all the seven fly avoidance behaviours were significantly higher (p&lt;0.01) in the control group. It could also be concluded that the occurance of all the behaviours in the control group at 1 PM were significantly high followed by 5 PM. The findings of the study suggest that fly activity in dairy farms was high during the afternoon hours followed by evening time and illuminated fly traps could be used effectively in controlling flies, so that the fly avoidance behavior by cattle was reduced on dairy farms.

Vocalization and other behaviors as indicators of emotional valence: The case of cow-calf separation and reunion in beef cattle

Vocalization may communicate the emotional state in vocal animals. We aimed to describe and compare vocalization and other behavioral signs of cow-calf pairs in emotionally negative and positive situations, and the potential influence of genetic group, parity category and calf sex on these signs.Forty-two beef cows (16 primiparous and 26 multiparous), and their 24 h-old calves (24 males and 18 females), with no previous separation from their mothers, were studied in Southern Brazil. The dams were daughters of Taurine crossbred mothers, 16 with Limousin (LIMO), 15 Charolais (CHAR), six Brahman (BRAH) and five Blond d'Aquitaine (BLON) bulls. We recorded 3 minute-videos to analyse animal responses to three sequential treatments: AR – arrival of cow and calf together in corral one (C1); SE – separation of the pair, calf removal from C1, isolated in corral 2 (C2), not seeing but hearing the cow; RU – reunion of calf and mother in C1. For cows and calves, the vocalization count per minute, fundamental frequency (f0), duration of the vocal call and latency to vocal response in AR, SE and RU were measured, as well as selected behaviour signals. A significant interaction effect between treatment and genetic group was observed for duration, pitch and vocalization count per minute. In SE, LIMO and CHAR cows expressed longer vocal responses than during AR, 24.6% and 18.2%, respectively, and RU (LIMO 15.7% and CHAR 33.6%). In SE, LIMO (114.2Hz) and BRAH (124.6Hz) cows showed higher f(0). CHAR and BRAH cows vocalized 2.8 and 5.1 times more frequently during SE than RU. Cows showed higher frequency of tail movements and smelling the corral in SE than in AR and RU. Cows presented higher frequency of head movement in SE as compared with RU. Calves showed greater head and body movement during SE than during AR and RU. In SE, male calves showed higher frequency of ear movements than female calves. Body movements of the cow were also more frequent during SE than in RU. Overall, cows showed higher pitch, longer vocal calls and other behavioral changes in SE, such as tail flapping, sniffing the corral, and head and body movements; calves showed higher frequency of head and body movement in SE. The results suggest that the studied indicators may be useful to identify emotionally negative situations, with genetic group and calf sex as factors which deserve further studies.

Structural basis of constitutive c-Src kinase activity due to R175L and W118A mutations

Cellular Src (c-Src) belongs to a non-receptor membrane-associated tyrosine kinase family that plays essential roles in cellular processes. Growing evidence suggests that R175L and W118A mutations in SH2/SH3 domains of c-Src functionally inactivate these domains leading to constitutive activation of kinase domain (KD). Here we modeled c-SrcR175L, c-SrcW118A and c-SrcW118A+R175L structures by inducing phosphorylation at Y416 or Y527, respectively to characterize the comparative dynamics in the active versus inactive states through molecular dynamics simulation assay. We observed more conformational readjustments in c-Srcopen than its close variants. In particular, C-terminal tail residues of c-SrcW118A-open and c-SrcW118A+R175L-open demonstrate significantly higher transitions. The cross-correlation analysis revealed an anticorrelation behavior in the motion of KD with respect to SH2, SH3 and the linker region of SrcW118A+R175L-open, while in c-SrcWT-open, SH2 and SH3 domains were anticorrelated, while KD and C-terminal tail motions were correlated. Due to these conformational differences, c-Src open forms exhibited lower interaction between pY527 and SH2 domain. Through detailed structural analysis, we observed a uniform myristate binding cavity in c-SrcWT-open, while the myristoyl pockets of mutant forms were deformed. We propose that constitutive activation of mutant Src forms may presumably be achieved by the prolonged membrane binding due to unusual conformations of C-terminal and myristoyl switch residues that may result in a higher dephosphorylation rate at pY527 in the myristoylated c-Src. Thus, our study establishes novel clues to decipher the constitutive activation status of c-Src in response to known mutations that may help in devising novel therapeutic strategies for cancer metastasis treatment. Communicated by Ramaswamy H. Sarma

Three-dimensional imaging of swirled spray injection in a generic aero engine burner under realistic operating conditions

Tomographic shadowgraph imaging is applied to reconstruct the instantaneous three-dimensional spray field immediately downstream of a generic aero engine fuel injector. Within the swirl passage of the injector model, a single kerosene jet undergoes air-blast atomization in a cross-flow configuration at Weber numbers of text {We}=360-770, air pressures of p_a=4-7,text{ bar } and air temperatures of T_a=440-570,text{ K }. High-speed, high magnification shadowgraphy is used to visualize the initial fuel atomization stages within the fuel injector before the spray enters the spray chamber. The 4-camera tomographic measurement setup is described in detail and includes a depth-of-field analysis with respect to droplet size based on Mie simulations and calibration data of the point-spread function. For a volume size of 16times 13times 10,text{ mm}^3 , the smallest resolvable droplet diameter is estimated to be d=10,mu text{ m } within the focal plane and increases to d approx 20,mu text{ m } toward the edges of the volume. Droplet velocities above the resolution limit were retrieved by 3-d cross-correlation of two volumetric reconstructions recorded at two consecutive time-steps. This is accompanied by an error analysis on the random error dependency on the camera viewing geometry. The results indicate increasing motion and fluctuations of the spray tail with increasing temperature and Weber number. Validation against PDA data further downstream of the burner plate revealed consistency for size classes d=10,mu text{ m } and d=15,mu text{ m }. Deviations from PDA occur in regions with strong velocity gradients due to different spatial resolutions, the presence of reconstruction ambiguities (ghost particles), uncertainties inherent to the two-frame cross-correlation of spray volumes and the finite LED pulse duration.Graphical

Morphological characteristics of the drop on the travelling substrate with a sharp stepped configuration

The shape of a drop on a partially wetting substrate strongly depends on not only its wetting velocity but also the surface characteristics of the substrate. The unexpected deformation or even breakup of the drop on the heterogeneous travelling substrate is a common phenomenon and needs to be carefully controlled in industrial processes. In this work, we designed an experiment to investigate the morphological characteristics of the drop on the substrate with a sharp stepped configuration. We experimentally studied the entire process of the drop motion on the substrate with a vertical-edged stepped structure and subdivided it into three stages: the collision stage, the inserting stage, and the stretching stage. For the collision stage, substrate velocity was determined as an important factor influencing the tail of the drop before and after the collision. For the inserting stage, it was found that the liquid is transferred to the pre-inserting zone with the reduced gap height due to the squeezing, resulting in an increase in the tail length; it was verified that the tail lengths vary with the position of the stepped frame by assuming that the drop volume is constant and the tail is simplified as a cone. For the stretching stage, three types of drop tails were observed by balancing the motion of the constraint tail in two directions: the one along the substrate movement and the one for anti-constraint of the stepped configuration; we experimentally analyzed the three types of drop tails and found that they are related to the substrate velocity, the gap height, and the height of stepped configuration.

In utero treatment of myelomeningocele with allogenic umbilical cord-derived mesenchymal stromal cells in an ovine model

The purpose of our study was to investigate the effects of ovine umbilical cord-derived mesenchymal stromal cells (UC-MSCs) seeded in a fibrin patch as an adjuvant therapy for fetal myelomeningocele repair in the ovine model. MMC defects were surgically created at 75 days of gestation and repaired 15 days later with UC-MSCs patch or an acellular patch. At birth, motor function, tail movements, and voiding abilities were recorded. Histological and immunohistochemical analysis included study of MMC defect's healing, spinal cord, UC-MSCs survival, and screening for tumors. Six lambs were born alive in each group. There was no difference between the two groups on the median sheep locomotor rating score but all lambs in the control group had a score between lower than 3 compared to 50% in UC-MSCs group. There were more lambs with tail movements and voiding ability in UC-MSCs group (83% vs 0% and 50% vs 0%, respectively). gray matter area and large neurons density were higher in UC-MSCs group (2.5vs 0.8 mm2 and 19.3vs 1.6 neurons/mm2 of gray matter, respectively). Fibrosis thickness at the myelomeningocele scar level was reduced in UC-MSCs group (1269µm vs 2624µm). No tumors were observed. Fetal repair of myelomeningocele using allogenic UC-MSCs patch provides a moderate improvement in neurological functions, gray matter and neuronal preservation and prevented from fibrosis development at the myelomeningocele scar level.

Turtling the Salamander: Tail Movements Mitigate Need for Kinematic Limb Changes during Walking in Tiger Salamanders (Ambystoma tigrinum) with Restricted Lateral Movement.

SynopsisLateral undulation and trunk flexibility offer performance benefits to maneuverability, stability, and stride length (via speed and distance traveled). These benefits make them key characteristics of the locomotion of tetrapods with sprawling posture, with the exception of turtles. Despite their bony carapace preventing lateral undulations, turtles are able to improve their locomotor performance by increasing stride length via greater limb protraction. The goal of this study was to quantify the effect of reduced lateral flexibility in a generalized sprawling tetrapod, the tiger salamander (Ambystoma tigrinum). We had two potential predictions: (1) either salamanders completely compensate by changing their limb kinematics, or (2) their performance (i.e., speed) will suffer due to the reduced lateral flexibility. This reduction was performed by artificially limiting trunk flexibility by attaching a 2-piece shell around the body between the pectoral and pelvic girdles. Adult tiger salamanders (n = 3; SVL = 9–14.5 cm) walked on a 1-m trackway under three different conditions: unrestricted, flexible shell (Tygon tubing), and rigid shell (PVC tubing). Trials were filmed in a single, dorsal view, and kinematics of entire midline and specific body regions (head, trunk, tail), as well as the fore and hind limbs, were calculated. Tygon individuals had significantly higher curvature than both PVC and unrestricted individuals for the body, but this trend was primarily driven by changes in tail movements. PVC individuals had significantly lower curvature in the trunk region compared with unrestricted individuals or Tygon; however, there was no difference between unrestricted and Tygon individuals suggesting the shells performed as expected. PVC and Tygon individuals had significantly higher curvature in the tails compared with unrestricted individuals. There were no significant differences for any limb kinematic variables among treatments including average, minimum, and maximum angles. Thus, salamanders respond to decreased lateral movement in their trunk by increasing movements in their tail, without changes in limb kinematics. These results suggest that tail undulations may be a more critical component to sprawling-postured tetrapod locomotion than previously recognized.

Motion planning of a fish-like piezoelectric actuated robot using model-based predictive control

This work proposes a novel methodology for planning the motion of fish-like soft robots actuated by macro-fiber composite (MFC) pairs. These structures should mimic oscillatory and undulation movements, which can be accomplished if the amplitude of the tail motion is larger than that of the head motion. Design strategies, such as the use of concentrated and distributed masses, are addressed to mimic fish-like motion since they guarantee suitable mode shapes for the structure. The motion planning proposal explores a model-based predictive control (MPC) strategy for deriving the input signals for the MFC actuators. This model-based control strategy requires the use of reasonably small-sized models. This is accomplished by extracting modal state-space models based on the free–free Euler–Bernoulli beam theory considering the electro-mechanical coupling of the MFC actuator pairs. Numerical results demonstrate the capability of the proposal for deriving bounded input signals that generate oscillatory and undulation movements even in the presence of disturbances. This general approach can be further extended for other applications.

Zebrafish larva’s response and habituation to electric signal: Effects of voltage, current and pulsation studied in a microfluidic device

We previously showed that electric current induces zebrafish larvae to move towards the anode pole along a microchannel. For a larva with a fixed head and a moving tail, we observed that the response to electricity depended on the current magnitude. The effects of electric signal direction, voltage magnitude and habituation to repeated exposures to electric pulses were not characterized. Here, this knowledge gap was addressed by exploiting them in a microfluidic device with a head-trap to immobilize a zebrafish larva and a downstream chamber for tail movement phenotypic characterization based on response duration (RD) and tail beat frequency (TBF). We first assessed larvae’s response to electric current direction (at 3 µA) and voltage magnitude. Changing the current direction significantly altered the RD and TBF with long and low-frequency responses seen when the anode was positioned at the larvae’s tail. The electric voltage had a significant effect on larvae’s locomotion with long RD and low TBF observed at 5.6 V in the range of 1.3–9 V. We also demonstrated that the zebrafish locomotor response to repeated 3 µA current pulses diminished with dependency on the interstimulus interval. However, the diminished response was fully recovered after a 5-min resting period or introduction of a novel light stimulus (i.e., habituation-dishabituation strategy). Therefore, electric response suppression in zebrafish was attributed to the habituation as a form of non-associative learning. Our microfluidic platform has a broad application potential in behavioral neuroscience to study cognitive phenotypes, fundamental studies on the biological roots of electric response, and in pharmacological screening.

Modeling and linearization of longitudinal dynamics for a flapping wing micro aerial vehicle dragonfly-like with active rigid tail

The main purpose of this paper is to model and simulate flight dynamics for a flapping wing micro aerial vehicle dragonfly-like with two pair clap and fling mechanism and active rigid tail. This article simulates the flight dynamics of a micro aerial vehicle dragonfly-like that can also use tail movements for longitudinal stability. Initially, using Kane's method, the equations of motion of the longitudinal mode are obtained. Then aerodynamics forces of Delfly II micro aerial vehicle and gearbox simulation are added to the equations of motion. Also, a novel design for a flapping wing micro aerial vehicle dragonfly-like is presented, in which tail movement is similar to the movement of insect tails in longitudinal mode. In this work, the tail movement is not used as an elevator, but the rigid tail movement is used as a control torque. The difference in brush motor rpm leads to differential thrust and pitch moment generation, similar to a quadrotor. Finally, the dynamic equations and aerodynamics and gearbox are all linearized and presented as state-space equations. Also, the response of the open-loop linearized model is compared with the nonlinear response by creating suitable initial conditions for the brush motor rpm.

Probing the biological toxicity of pyrene to the earthworm Eisenia fetida and the toxicity pathways of oxidative damage: A systematic study at the animal and molecular levels

Pyrene (Pyr), a widely used tetracyclic aromatic hydrocarbon, enters soil in large quantities and causes environmental pollution due to its production and mining. In order to systematically study the biotoxicity of pyrene to model organisms Eisenia fetida in soil, experiments were carried out from four dimensions: animal, tissue, cell and molecule. Experimental results proved that the mortality rate increased with increasing concentration and time of exposure to pyrene, while the mean body weight and spawning rate decreased. Meanwhile, when the pyrene concentration reached 900 mg/kg, the seminal vesicle and longitudinal muscle of the earthworm showed obvious atrophy. Experimental results at the cellular level showed that pyrene induced cell membrane damage and Ca2+ influx triggered mitochondrial membrane depolarization and a surge in ROS levels. Oxidative stress causes damage to proteins and lipids and DNA inside cells. When the mortality rate was 91.67 %, the Olive Tail Movement (OTM) of the comet experiment reached 15. The results of molecular level tests showed that pyrene inhibited the activity of Cu/Zn-superoxide dismutase (Cu/Zn-SOD) mainly by changing the microenvironment and secondary structure of amino acid Tyr 108. The weakened function of direct antioxidant enzymes may be the root cause of the excessive increase of reactive oxygen species (ROS) in cells. The systematic approach used in this study enriches the network of toxic pathways in toxicological studies, and basic data on the biological toxicity of pyrene can provide support for future soil contamination detection.