Swimming Speed Research Articles

Seasonal migrations of the European sea bass (Dicentrarchus labrax L.) in UK and surrounding waters

The movements and behaviour of mature European sea bass (Dicentrarchus labrax L.) in UK waters have not been studied extensively since a series of mark-recapture experiments during the 1970s, 80s and 90s. To better understand the timing and extent of seasonal migrations, 171 mature sea bass > 42 cm were internally tagged with floated electronic tags programmed to record temperature and depth, and released in the English Channel, in the southern North Sea and in the Irish Sea. Among the 48 tags returned to date, sea bass were at liberty for 370 ± 337 days and were recovered 172 ± 200 km from their respective release locations. Most tags were recovered from beaches (54%), or via the fishery (44%). A comparison of the reconstructed tracks from returned electronic tags with the recapture locations of 237 mark-recapture returns (6.5%) from 3615 sea bass released between 1970 and 2020 showed strong overlap. Seasonal movements between shallow areas (Q2–Q3) and deeper spawning areas (Q4–Q1) were accompanied by elevated vertical swimming speeds and average water temperatures of 8.5 °C in the English Channel and Irish Sea, but lower temperatures in the North Sea. Movements between the Celtic Sea/Irish Sea and the North Sea and vice versa demonstrate high levels of connectivity in UK waters. We demonstrate that a proportion of sea bass remained resident within the North Sea throughout the year, with a strong suggestion that spawning might be occurring. These data have significant implications for the future sustainable management of sea bass stocks in UK and surrounding waters.

Melatonin attenuates developmental deficits and prevents hippocampal injuries in male and female rats subjected to neonatal anoxia.

Hypoxia in preterm infants is a clinical condition that has been associated with cognitive and behavioral disturbances for which treatment strategies are strongly required. Melatonin administration following brain insults has been considered a promising therapeutic strategy due to its antioxidant and anti-inflammatory effects. Not surprisingly, it has been extensively studied for preventing disturbances following brain injury. This study evaluated the effects of melatonin on developmental disturbances, memory disruption, and hippocampal cell loss induced by neonatal anoxia in rats. Neonatal Wistar rats were subjected to anoxia and subsequently treated with melatonin. Later, maturation of physical characteristics, ontogeny of reflexes, learning and memory in the Morris water maze (MWM), and estimates of the number of hippocampal neurons, were evaluated. Melatonin treatment attenuated (1) female anoxia-induced delay in superior incisor eruption, (2) female anoxia-induced vibrissae placement reflexes, and (3) male and female anoxia-induced hippocampal neuronal loss. Melatonin also promoted an increase (5) in swimming speeds in the MWM. In addition, PCA analysis showed positive associations between the acoustic startle, auditory canal open, and free fall righting parameters and negative associations between the male vehicle anoxia group and the male melatonin anoxia group. Therefore, melatonin treatment attenuates both anoxia-induced developmental deficits and hippocampal neuronal loss.

Effects of Dry Land Speed Training on 100-Meter Freestyle Swimming in Adolescent Swimming

Background and Aim: The specific strength development in swimming tends to start at a younger age, so it becomes particularly important to conduct effective Specific strength training during adolescence. It is essential to utilize training methods and means that align with the developmental characteristics of Specific strengths in young swimmers. Thus, this study has developed a specific dry-land training program to enhance the 100-meter freestyle swimming speed of adolescent swimmers. Methods: This study selected 30 male adolescent swimmers from the Shaanxi Provincial Swimming Team and divided them into an experimental group and a control group (15 individuals in each group) based on their 100-meter freestyle speed. Both groups underwent a 12-week training intervention, with 12 training sessions per week, each lasting 2 hours. The total training time and water-based training content were the same for both groups, but the content of dry-land training differed. The experimental group followed a specific dry-land training program, while the control group followed a traditional training program. Comprehensive tests were conducted before and after the 12-week training intervention for both groups, using the physical fitness and test scores of swimmers in the experimental and control groups as research indicators. Experimental and analytical methods, including experimental and statistical methods, were employed to conduct a targeted study on the changes in physical fitness and test scores before and after the training. Results: show that after 12 weeks of training, the scores for both groups are as follows: Pull-ups (Experimental group: P=0.000<0.01, Control group: P=0.777>0.05), Vertical jump (Experimental group: P=0.032<0.05, Control group: P=0.848>0.05), Abdominal muscle endurance (Experimental group: P=0.000<0.01, Control group: P=0.396>0.05), and Back muscle endurance (Experimental group: P=0.004<0.01, Control group: P=0.583>0.05). The post-test results reveal that swimmers in the experimental group performed significantly better in pull-ups, vertical jumps, abdominal muscle endurance, and back muscle endurance compared to the control group. Conclusion: The specialized training program effectively increased the upper limb strength of the participants, with no significant advantage over the traditional training program.

Soft Electrohydraulic Bending Actuators for Untethered Underwater Robots

Traditional underwater rigid robots have some shortcomings that limit their applications in the ocean. In contrast, because of their inherent flexibility, soft robots, which have gained popularity recently, offer greater adaptability, efficiency, and safety than rigid robots. Among them, the soft actuator is the core component to power the soft robot. Here, we propose a class of soft electrohydraulic bending actuators suitable for underwater robots, which realize the bending motion of the actuator by squeezing the working liquid with an electric field. The actuator consists of a silicone rubber film, polydimethylsiloxane (PDMS) films, soft electrodes, silicone oils, an acrylic frame, and a soft flipper. When a square wave voltage is applied, the actuator can generate continuous flapping motions. By mimicking Haliclystus auricula, we designed an underwater robot based on six soft electrohydraulic bending actuators and constructed a mechanical model of the robot. Additionally, a high-voltage square wave circuit board was created to achieve the robot’s untethered motions and remote control using a smart phone via WiFi. The test results show that 1 Hz was the robot’s ideal driving frequency, and the maximum horizontal swimming speed of the robot was 7.3 mm/s.

The Effect of a Limited Underactuated Posterior Joint on the Speed and Energy Efficiency of a Fish Robot

Autonomous underwater vehicles (AUVs) commonly use screw propellers to move in a water environment. However, compared to the propeller-driven AUV, bio-inspired AUVs feature a higher energy efficiency, longer lifespan (due to a lack of cavitation), and better eco-friendliness (due to lower noise, a lack of vibrations, and a weaker wake). To generate propulsion, the design of fish robots—viewed as a special case of a bio-inspired AUV—comprise multiple actuated joints. Underactuated joints have also been adopted in bio-inspired AUVs, primarily for the purpose of achieving a simpler design and more realistic and biologically plausible locomotion. In our work, we propose a limitedly underactuated posterior (tail) joint of a fish robot with the intention of achieving a higher swimming speed and better energy efficiency of the robot. The limited underactuation is achieved by allowing the joint to move freely but only within a limited angular range. The experimental results verified that, for relatively small angular ranges, the limitedly underactuated joint is superior to both fully actuated and fully underactuated joints in that it results in faster and more energy-efficient locomotion of the fish robot.

Fish in the fast lane: the stressful consequences of speeding through a flume

Understanding the swimming ability of different fish species is essential for assessing their ecological niche, behaviour and overall fitness. Changes in swimming ability can relate to the overall health of aquatic ecosystems, as it can be affected by water quality, temperature or habitat quality changes. Our study investigated the effects of stress on swimming performance in wild vairone (Telestes muticellus) in an experimental flume. The obtained data was analysed using k-means clustering to identify stress response patterns. Our findings demonstrate that k-means clustering effectively identified distinct subgroups of fish with similar stress responses in groups with physiological stress responses with high individual variability. We found that short-term exposure to a stress source such as high-velocity running water can increase swimming endurance in this species concerning the velocity in the setup, which was mainly seen in the cortisol and MDA levels in the muscle tissue of the fish. The velocity of the water showed limitations on swimming ability tests and highlighted that fish have a specific range of swimming speeds that they can sustain.

Creatine and l-carnitine attenuate muscular laminopathy in the LMNA mutation transgenic zebrafish

Lamin A/C gene (LMNA) mutations contribute to severe striated muscle laminopathies, affecting cardiac and skeletal muscles, with limited treatment options. In this study, we delve into the investigations of five distinct LMNA mutations, including three novel variants and two pathogenic variants identified in patients with muscular laminopathy. Our approach employs zebrafish models to comprehensively study these variants. Transgenic zebrafish expressing wild-type LMNA and each mutation undergo extensive morphological profiling, swimming behavior assessments, muscle endurance evaluations, heartbeat measurement, and histopathological analysis of skeletal muscles. Additionally, these models serve as platform for focused drug screening. We explore the transcriptomic landscape through qPCR and RNAseq to unveil altered gene expression profiles in muscle tissues. Larvae of LMNA(L35P), LMNA(E358K), and LMNA(R453W) transgenic fish exhibit reduced swim speed compared to LMNA(WT) measured by DanioVision. All LMNA transgenic adult fish exhibit reduced swim speed compared to LMNA(WT) in T-maze. Moreover, all LMNA transgenic adult fish, except LMNA(E358K), display weaker muscle endurance than LMNA(WT) measured by swimming tunnel. Histochemical staining reveals decreased fiber size in all LMNA mutations transgenic fish, excluding LMNA(WT) fish. Interestingly, LMNA(A539V) and LMNA(E358K) exhibited elevated heartbeats. We recognize potential limitations with transgene overexpression and conducted association calculations to explore its effects on zebrafish phenotypes. Our results suggest lamin A/C overexpression may not directly impact mutant phenotypes, such as impaired swim speed, increased heart rates, or decreased muscle fiber diameter. Utilizing LMNA zebrafish models for drug screening, we identify l-carnitine treatment rescuing muscle endurance in LMNA(L35P) and creatine treatment reversing muscle endurance in LMNA(R453W) zebrafish models. Creatine activates AMPK and mTOR pathways, improving muscle endurance and swim speed in LMNA(R453W) fish. Transcriptomic profiling reveals upstream regulators and affected genes contributing to motor dysfunction, cardiac anomalies, and ion flux dysregulation in LMNA mutant transgenic fish. These findings faithfully mimic clinical manifestations of muscular laminopathies, including dysmorphism, early mortality, decreased fiber size, and muscle dysfunction in zebrafish. Furthermore, our drug screening results suggest l-carnitine and creatine treatments as potential rescuers of muscle endurance in LMNA(L35P) and LMNA(R453W) zebrafish models. Our study offers valuable insights into the future development of potential treatments for LMNA-related muscular laminopathy.

Testing personality-pace-of-life associations via artificial selection: insights from selected lines of rainbow trout on the context-dependence of correlations.

More than a decade of study since the personality pace-of-life syndrome (POLS) hypotheses were first proposed, there is little support for it within species. Lack of experimental control, insufficient sampling in the face of highly labile behavioural and metabolic traits, and context dependency of trait correlations are suggested as reasons. Here, I argue that artificial selection and/or use of existing selected lines represents a powerful but under-used approach to furthering our understanding of the POLS. To illustrate this potential, I conducted a focussed review of studies that compared the behaviour, metabolism, growth and survival of an artificially selected fast-growing rainbow trout relative to wild unselected strains, under varying food and risk conditions in the laboratory and field. Resting metabolic rate, food intake, and behaviours that enhance feeding but increase energy expenditure (activity, aggression, boldness), were all higher in the fast strain in paired contrasts, under all food and risk conditions, both in the laboratory and the field. Fast-strain fish grew faster in almost every food and risk situation except where food was highly limited (or absent), had higher survival under low or zero predation risk, but had lower survival under high risk. Several other traits rarely considered in POLS studies were also higher in the fast strain, including maximum swimming speed, and hormones (growth hormone (GH), thyroid hormone (T3) and insulin-like growth factor (IGF-1)). I conclude: (i) assumptions and predictions of the POLS hypothesis are well supported, and (ii) context-dependency was largely absent, but when present revealed trade-offs between food acquisition and predation risk. This focused review highlights the potential of artificial selection in testing POLS ideas, and will hopefully motivate further studies using other animals.

Swimming at Increasing Speeds in Steady and Unsteady Flows of Atlantic Salmon Salmo salar: Oxygen Consumption, Locomotory Behaviour and Overall Dynamic Body Acceleration.

The swimming performance of cultured finfish species is typically studied under steady flow conditions. However, flow conditions are mostly unsteady, for instance, as experienced in sea pens in exposed sea areas. Using a Loligo swim tunnel, we investigated the effects of swimming in steady and unsteady flows at increasing swimming speeds on post-smolt Atlantic salmon. Oxygen consumption (MO2), locomotory behaviour, and overall dynamic body acceleration (ODBA), as determined with implanted acoustic sensor tags, were compared between both flow conditions. Results were obtained for mean swimming speeds of 0.2 to 0.8 m.s-1 under both flow conditions. Sensor tags that were implanted in the abdominal cavity had no significant effects on MO2 and locomotory parameters. The MO2 of fish swimming in unsteady flows was significantly higher (15-53%) than when swimming in steady flows (p < 0.05). Significant interaction effects of ODBA with flow conditions and swimming speed were found. ODBA was strongly and positively correlated with swimming speed and MO2 in unsteady flow (R2 = 0.94 and R2 = 0.93, respectively) and in steady flow (R2 = 0.91 and R2 = 0.82, respectively). ODBA predicts MO2 well over the investigated range of swimming speeds in both flow conditions. In an unsteady flow condition, ODBA increased twice as fast with MO2 compared with steady flow conditions (p < 0.05). From these results, we can conclude that (1) swimming in unsteady flow is energetically more costly for post-smolt Atlantic salmon than swimming in steady flow, as indicated by higher MO2, and (2) ODBA can be used to estimate the oxygen consumption of post-smolt Atlantic salmon in unsteady flow in swim tunnels.

Comparative effects of polyvinyl chloride microplastics on the brittle star Ophiactis virens and the amphibian Xenopus laevis

In this study, we investigated the effects of PVC microplastics (PVC-MPs) using two different animal models: the brittle star Ophiactis virens, and the African clawed frog Xenopus laevis. This is the first study using an environmental relevant sample of PVC-MPs obtained through mechanical fragmentation of a common PVC plumbing pipe. Exposure experiments on brittle star were performed on the adult stage for a duration of 14 days, while those on African clawed frog were performed on the embryogenic developmental stage according to the standardized FETAX protocol (Frog Embryo Teratogenesis Assay-Xenopus). For both models, different endpoints were analysed: mortality, developmental parameters, behavioural assays and histological analyses on target organs by optical and electronic microscopy. Results showed that the concentration of 0.1 μg mL−1 PVC do not cause any adverse effects in both models (common NOEC concentration), while exposure to 1 μg mL−1 PVC adversely affected at least one species (common LOEC concentration). In particular arm regeneration efficiency was the most affected parameters in O. virens leading to a significantly lower differentiation pattern at 1 μg mL−1 PVC. On the contrary, in X. laevis larvae histopathological analyses and behavioural tests were the most susceptible endpoints, exhibiting several abnormal figures and different swimming speed at 10 μg mL−1 PVC. Histopathological analyses revealed a higher abundance of degenerating cells, pyknotic nuclei and cellular debris in the gut of exposed larvae in respect to control. The comparative analyses performed in this work allowed to characterize the specificity of action of the PVC-MPs on the two species, underlining the importance of exploring a large spectrum of endpoints to offer adequate protection in the emerging fields of microplastic research.

Morphology and metabolic traits related to swimming performance in Australasian snapper (Chrysophrys auratus) selected for fast growth.

Changes in body shape are linked to swimming performance and become relevant for selective breeding programmes in cultured finfish. We studied how the selection for fast growth could affect phenotypes by investigating the relationship between swimming performance and body shape. We also investigated how swimming might affect plasma metabolite concentrations. Critical swimming speed (UCrit), body traits (e.g., BW, body weight; BL, body length; K, condition factor), and plasma lactate and glucose concentrations were evaluated in two cohorts of Australasian snapper (Chrysophrys auratus): one derived from wild broodstock (F1), and the other selected for fast growth (F4). UCrit tests (n = 8) were applied in groups of 10 snapper of similar BW (71.7 g) and BL (14.6 cm). The absolute or relative UCrit values of both cohorts were similar (0.702 m⋅s-1 and 4.795 BL⋅s-1, respectively), despite the F4 cohort displaying a higher K. A positive correlation between K and absolute UCrit (Pearson's r = 0.414) was detected in the F4 cohort, but not in the F1 cohort, which may be linked to differences in body shape. A negative correlation between relative UCrit and body size (Pearson's r between -0.682 and -0.501), but no correlation between absolute UCrit and body size, was displayed in both cohorts. Plasma lactate and glucose concentrations were higher in the F4 cohort at UCrit. Whether a longer selective breeding programme could result in more changes in body shape, potentially affecting swimming performance, should be explored, along with the potential outcomes of the differences in metabolic traits detected.

Enhancement of southern flounder (Paralichthys lethostigma) sperm velocity and fertility by direct activation of sperm epidermal growth factor and adenylyl cyclase signaling pathways

Development of southern flounder commercial aquaculture is limited by poor sperm motility and fertility, but the underlying causes and mechanisms regulating sperm motility are unknown. In vitro treatment of southern flounder sperm with progestin hormones rapidly increases velocity (swimming speed), a major component of sperm motility, and also fertility through membrane progestin receptor alpha (mPRα) and increases in Acy (adenylyl cyclase)/cAMP signaling. The progestin-induced increase of Atlantic croaker sperm velocity is also mediated through epidermal growth factor receptor (Egfr) transactivation resulting in extracellular-regulated kinase 1/2 (Erk1/2) signaling, but its role in regulating southern flounder sperm velocity is unknown. The hypotheses that Egfr transactivation and Erk1/2 signaling mediates progestin-induced increases in sperm velocity and calcium levels in southern flounder, and that direct stimulation of sperm Egfr/Erk1/2 and Acy/cAMP pathways increases sperm fertility in strip spawning trials were tested in the present study. Golf, Egfr, Erk1/2, and protein kinase A were detected on southern flounder sperm by immunocytochemistry. Involvement of Egfr/Erk1/2 signaling in increasing sperm velocity and calcium levels was investigated by preincubating sperm with two EGFR inhibitors, AG1478, and AG825, a matrix metalloproteinase inhibitor, Ilomastat, and two ERK1/2 inhibitors, PD98059, and U0126, for 30 min prior to 1 min treatment with progestins. Sperm swimming speed was observed under a microscope after activation with a hyperosmotic medium and recorded for 1 min. Whereas treatment with the inhibitors did not alter basal sperm velocity and calcium levels, all of them significantly attenuated velocity and calcium increases in response to progestins. Treatment in vitro for 1 min with the Egfr agonist, recombinant human EGF (0.1 nM and 100 nM), mimicked the stimulatory effects of progestins on sperm velocity, the increase in calcium, and also fertility in a strip spawning trials with ovulated southern flounder eggs. The results suggest Egfr/Erk1/2 signaling is involved in sperm velocity and fertility responses to progestins in southern flounder. Direct in vitro treatment with the Acy activator, forskolin (10 μM) for 1 min mimicked the stimulatory action of progestins on sperm calcium levels, velocity, and fertility, suggesting that Acy/cAMP signaling also mediates increased sperm swimming speed and fertility. Importantly, both EGF and forskolin also directly stimulated southern flounder sperm velocity and fertility at the end of the reproductive season when sperm were no longer responsive to progestins. The results suggest that EGF and forskolin could potentially be used as pharmacological agents to enhance reproductive performance of male southern flounder broodstock.

Application of Functional Analysis in Solving River Crossing Problems under Dynamic Water Flow Conditions

Considering the urgent need for efficient and safe river crossing strategies in natural disaster relief and outdoor sports, in-depth research on river crossing strategies based on mathematical modeling and optimization theory is of great significance for improving river crossing safety and efficiency and guiding practical operations in related fields. Aiming at the goal of "rushing across the Yangtze River", based on the variational method and functional analysis theory, the Hamilton-Lagrange multiplier method is used to solve the constrained functional extremum problem. By solving the Euler equation, a universal continuous-time optimal control model is established. Using dichotomy and numerical analysis, the optimal trajectory and direction control law of swimming speed is solved, and the optimal path scheme to reach the endpoint is proposed, which contributes to the efficiency and safety of river crossing and provides practical suggestions in related fields.

Multi-level toxicity assessment of polylactic acid (PLA) microplastics on the cladoceran Daphnia magna

The accumulation of plastics waste in the environment has raised a worrisome concern, moving the society to seek out for sustainable solutions, such as the transition from the use of fossil-based, conventional plastics to bioplastics (BPs). However, once in the environment bioplastics have the same probability to accumulate and experience weathering processes than conventional plastics, leading to the formation of microplastics (MPs). However, to date the information on the potential toxicity of MPs originated from the weathering of bioplastics is limited. Thus, this study aimed at investigating the adverse effects induced by the exposure to MPs made of a bioplastic polymer, the polylactic acid (PLA), towards the freshwater cladoceran Daphnia magna. Organisms were exposed for 21 days to three concentrations (0.125 µg/mL, 1.25 µg/mL and 12.5 µg/mL) of PLA microplastics (hereafter PLA-MPs). A multi-level approach was performed to investigate the potential effects through the biological hierarchy, starting from the sub-individual up to the individual level. At the sub-individual level, changes in the oxidative status (i.e., the amount of reactive oxygen species and the activity of antioxidant and detoxifying enzymes) and oxidative damage (i.e., lipid peroxidation) were explored. Moreover, the total caloric content as well as the content of protein, carbohydrate and lipid content assess were used to investigate the effects on energy reserves. At individual level the changes in swimming activity (i.e., distance moved and swimming speed) were assessed. Our results showed that the exposure to PLA-MPs induced a slight modulation in the oxidative status and energy reserves, leading to an increase in swimming behavior of treated individuals compared to control conspecifics. These results suggest that the exposure to MPs made of a bioplastic polymer can induce adverse effects similar to those caused by conventional polymers.

The function of the ATG8 in the cilia and cortical microtubule maintenance of Euplotes amieti.

Autophagy regulates the formation of primary cilia, which in turn affects autophagy. The relationship between autophagy and cilia is known to be bidirectional although the specific mechanisms involved have yet to be elucidated. In this study, we found for the first time that ATG8 protein localizes in the basal body of the dorsal kineties and the base of the ventral cirri in Euplotes amieti. ATG8 protein maintains the structural integrity of cilia and plays a role in the construction of the cortical ciliature and microtubule cytoskeleton associated with cilia. ATG8 gene interference leads to the degradation of IFT88, the transport protein in cilia, thus inhibiting the generation of cilia, and affecting the swing of cilia. This influences the swimming speed and cilia pattern, leading to death in Euplotes amieti.

The Relationship between Anthropometric, Biomotor, and Psychomotor Factors on the Performance of Paralympic 100 Meters Freestyle Swimming Athletes in National Paralympic Committee Indonesia

This research aims to relationship the anthropometric, biomotor, and psychomotor factors with disabled athlete's swimming speed in the National Paralympic Committee (NPC) (Indonesian) 100-meter freestyle competition in 2022. This research was a cross-sectional study conducted by the National Paralympic Committee (NPC) (Indonesia). The sample used in this research was 15 disabled athletes from NPC Indonesia with the S7-S10 classification who got medals at the ASEAN Para Games event in 2022. The data collection includes seven independent variable tests there are anthropometric factors (height, weight, body mass index, arm length, and leg length); biomotor factors (abdominal muscle strength and arm muscle power); psychomotor factors by measuring balance using Balance Tests; and dependent variables by measuring swimming speed using the 100-meter freestyle swimming ability test. Statistical analysis used the Pearson correlation coefficient test with a significance level of 5%. The results of the Pearson correlation coefficient analysis show that swimming speed was negatively related to body height, body weight, arm length, abdominal muscle strength, and arm muscle power indicating a moderate correlation between variables (p ≤ 0.001). However, unfortunately, other anthropometric variables such as leg length and age showed a weak negative correlation with swimming speed (p ≤ 0.05). Meanwhile, body mass index and balance did not show a significant correlation with swimming speed (p ≥ 0.05). Based on the research results, it was concluded that anthropometric and biomotor factors showed a negative relationship with swimming speed, while psychomotor factors did not. Keyword: Anthropometry, biomotor, psychomotor, disabled athletes, swimming speed, achievement.

Ex vivo validation of magnetically actuated intravascular untethered robots in a clinical setting

Intravascular surgical instruments require precise navigation within narrow vessels, necessitating maximum flexibility, minimal diameter, and high degrees of freedom. Existing tools often lack control during insertion due to undesirable bending, limiting vessel accessibility and risking tissue damage. Next-generation instruments aim to develop hemocompatible untethered devices controlled by external magnetic forces. Achieving this goal remains complex due to testing and implementation challenges in clinical environments. Here we assess the operational effectiveness of hemocompatible untethered magnetic robots using an ex vivo porcine aorta model. The results demonstrate a linear decrease in the swimming speed of untethered magnetic robots as arterial blood flow increases, with the capability to navigate against a maximum arterial flow rate of 67 mL/min. The untethered magnetic robots effectively demonstrate locomotion in a difficult-to-access target site, navigating through the abdominal aorta and reaching the distal end of the renal artery.

Biomechanical analysis of little penguins' underwater locomotion from the free-ranging dive data.

Penguins are proficient swimmers, and their survival depends on their ability to catch prey. The diving behaviour of these fascinating birds should then minimize the associated energy cost. For the first time, the energy cost of penguin dives is computed from the free-ranging dive data, on the basis of an existing biomechanical model. Time-resolved acceleration and depth data collected for 300 dives of little penguins (Eudyptula minor) are specifically employed to compute the bird dive angles and swimming speeds, which are needed for the energy estimate. We find that the numerically obtained energy cost by using the free-ranging dive data is not far from the minimum cost predicted by the model. The outcome, therefore, supports the physical soundness of the chosen model; however, it also suggests that, for closer agreement, one should consider previously neglected effects, such as those due to water currents and those associated with motion unsteadiness. Additionally, from the free-ranging dive data, we calculate hydrodynamic forces and non-dimensional indicators of propulsion performance - Strouhal and Reynolds numbers. The obtained values further confirm that little penguins employ efficient propulsion mechanisms, in agreement with previous investigations.

Functional and biochemical characterisation of remote homologues of type IV pili proteins PilN and PilO in Helicobacter pylori.

Helicobacter pylori encodes homologues of PilM, PilN and PilO from bacteria with Type IV pili, where these proteins form a pilus alignment complex. Inactivation of pilO changes H. pylori motility in semi-solid media, suggesting a link to the chemosensory pathways or flagellar motor. Here, we showed that mutation of the pilO or pilN gene in H. pylori strain SS1 reduced the mean linear swimming speed in liquid media, implicating PilO and PilN in the function, or regulation of, the flagellar motor. We also demonstrated that the soluble variants of H. pylori PilN and PilO share common biochemical properties with their Type IV pili counterparts which suggests their adapted function in the bacterial flagellar motor may be similar to that in the Type IV pili.

Intranasal insulin treatment ameliorates spatial memory, muscular strength, and frailty deficits in 5xFAD mice

The 5xFAD mouse model shows age-related weight loss as well as cognitive and motor deficits. Metabolic dysregulation, especially impaired insulin signaling, is also present in AD. This study examined whether intranasal delivery of insulin (INI) at low (0.875 U) or high (1.750 U) doses would ameliorate these deficits compared to saline in 10-month-old female 5xFAD and B6SJL wildtype (WT) mice. INI increased forelimb grip strength in the wire hang test in 5xFAD mice in a dose-dependent manner but did not improve the performance of 5xFAD mice on the balance beam. High INI doses reduced frailty scores in 5xFAD mice and improved spatial memory in both acquisition and reversal probe trials in the Morris water maze. INI increased swim speed in 5xFAD mice but had no effect on object recognition memory or working memory in the spontaneous alternation task, nor did it improve memory in the contextual or cued fear memory tasks. High doses of insulin increased the liver, spleen, and kidney weights and reduced brown adipose tissue weights. P-Akt signaling in the hippocampus was increased by insulin in a dose-dependent manner. Altogether, INI increased strength, reduced frailty scores, and improved visual spatial memory. Hypoglycemia was not present after INI, however alterations in tissue and organ weights were present. These results are novel and important as they indicate that intra-nasal insulin can reverse cognitive, motor and frailty deficits found in this mouse model of AD.