Locomotor Systems Research Articles

Design as a learning opportunity in biology lessons—a cross-domain STEM approach and its impact on biological subject knowledge

There is a broad consensus in politics, economy and science about the importance of promoting STEM competences. To promote STEM skills in the classroom, we propose a cross-domain approach combining the STEM sub-domains of Biology and Technology/Engineering. Therefore, we have developed a model that illustrates how the STEM sub-domains of Biology and Technology/Engineering can complement each other in a cognitive process. Both sub-domains show similarities in working methods and consider structural and functional relationships. These synergies can be brought together in a design process. This approach leads to the question of the extent to which a cross-domain approach utilising a design process can be a learning opportunity for biological subject knowledge. Based on this model, we have created a learning arrangement on the topic of the ‘locomotor system’. Learners should use a design process to build a feeding machine inspired by structural-functional relationships in different locomotor systems. In a quasi-experimental study, we compared this Design approach with two alternative teaching approaches (a Reconstruction approach and a Biology approach). In the Reconstruction approach, students receive the same input on structural-functional relationships in locomotor systems but build their feeding machine according to a predetermined plan. In the Biology approach, no feeding machine is built; instead, structural-function relationships in locomotor systems are modelled using further examples from the animal world. 413 pupils (age: M = 12.53, SD = 0.818) took part in the study. Longitudinal and cross-sectional analyses emphasise the potential of the Design approach compared to the other methods and show significant differences in long-term learning outcomes. Path models illustrate that cognitive abilities (IQ) and participation in the ‘Design’-intervention group are decisive prerequisites for learning success. The results also show that students following the Design-approach develop a significantly improved understanding of concepts related to the musculoskeletal system. Using a design process combining biology and engineering presents a learning opportunity for students to develop long-term robust biological knowledge and understanding of biological concepts. Thus, using a design approach can be a cross-domain bridge for integrated STEM instruction in order to foster pupils’ knowledge acquisition and competences.

Fish-hunting cone snail disrupts prey’s glucose homeostasis with weaponized mimetics of somatostatin and insulin

Venomous animals have evolved diverse molecular mechanisms to incapacitate prey and defend against predators. Most venom components disrupt nervous, locomotor, and cardiovascular systems or cause tissue damage. The discovery that certain fish-hunting cone snails use weaponized insulins to induce hypoglycemic shock in prey highlights a unique example of toxins targeting glucose homeostasis. Here, we show that, in addition to insulins, the deadly fish hunter, Conus geographus, uses a selective somatostatin receptor 2 (SSTR2) agonist that blocks the release of the insulin-counteracting hormone glucagon, thereby exacerbating insulin-induced hypoglycemia in prey. The native toxin, Consomatin nG1, exists in several proteoforms with a minimized vertebrate somatostatin-like core motif connected to a heavily glycosylated N-terminal region. We demonstrate that the toxin’s N-terminal tail closely mimics a glycosylated somatostatin from fish pancreas and is crucial for activating the fish SSTR2. Collectively, these findings provide a stunning example of chemical mimicry, highlight the combinatorial nature of venom components, and establish glucose homeostasis as an effective target for prey capture.

Evidence of spontaneous cardiac-locomotor coupling during daily activities in healthy adults.

One way to improve exercise performance and protect heart health is the extended synchronization of the stepping with the diastolic phase of the cardiac cycle. Cardiac-locomotor coupling (CLC) happens when the step rate (SR) equals the heart rate (HR). The extent of CLC in daily life is unknown. This study aims to analyze spontaneous occurrences of CLC during daily activities. A retrospective analysis of daily life recordings from a wrist-worn sensor was undertaken (PMData, N = 16, 5months duration). The deviation between HR and SR was used to define CLC (deviation ≤ 1%) and weak CLC (1%< deviation ≤ 10%). The occurrence and the probability of CLC during everyday life were computed from the recordings. The CLC occurrences were stratified depending on the duration and intensity of the physical activity. Finally, a Monte Carlo simulation was run to evaluate the probability of random occurrences of CLC vs. the observed recordings. Participants couple for 5% and weakly couple for 35% of the observational period. The ratio of 1:1 between HR and SR is the dominating occurrence across the study population and this overrepresentation is significant. CLC occurs mostly for long activities. The extent of CLC for various intensities of activity is subject-dependent. The results suggest that CLC is feasible for most people. CLC occurs spontaneously during unsupervised daily activity in everyone in our cohort, which suggests a mechanistic interaction between the cardiac and the locomotor systems. This interaction should be investigated for medical rehabilitation and sports applications in the future.

Dynamic similarity and the peculiar allometry of maximum running speed

Animal performance fundamentally influences behaviour, ecology, and evolution. It typically varies monotonously with size. A notable exception is maximum running speed; the fastest animals are of intermediate size. Here we show that this peculiar allometry results from the competition between two musculoskeletal constraints: the kinetic energy capacity, which dominates in small animals, and the work capacity, which reigns supreme in large animals. The ratio of both capacities defines the physiological similarity index Γ, a dimensionless number akin to the Reynolds number in fluid mechanics. The scaling of Γ indicates a transition from a dominance of muscle forces to a dominance of inertial forces as animals grow in size; its magnitude defines conditions of “dynamic similarity“ that enable comparison and estimates of locomotor performance across extant and extinct animals; and the physical parameters that define it highlight opportunities for adaptations in musculoskeletal “design” that depart from the eternal null hypothesis of geometric similarity. The physiological similarity index challenges the Froude number as prevailing dynamic similarity condition, reveals that the differential growth of muscle and weight forces central to classic scaling theory is of secondary importance for the majority of terrestrial animals, and suggests avenues for comparative analyses of locomotor systems.

The future of artificial hibernation medicine: protection of nerves and organs after spinal cord injury.

Spinal cord injury is a serious disease of the central nervous system involving irreversible nerve injury and various organ system injuries. At present, no effective clinical treatment exists. As one of the artificial hibernation techniques, mild hypothermia has preliminarily confirmed its clinical effect on spinal cord injury. However, its technical defects and barriers, along with serious clinical side effects, restrict its clinical application for spinal cord injury. Artificial hibernation is a future-oriented disruptive technology for human life support. It involves endogenous hibernation inducers and hibernation-related central neuromodulation that activate particular neurons, reduce the central constant temperature setting point, disrupt the normal constant body temperature, make the body "adapt" to the external cold environment, and reduce the physiological resistance to cold stimulation. Thus, studying the artificial hibernation mechanism may help develop new treatment strategies more suitable for clinical use than the cooling method of mild hypothermia technology. This review introduces artificial hibernation technologies, including mild hypothermia technology, hibernation inducers, and hibernation-related central neuromodulation technology. It summarizes the relevant research on hypothermia and hibernation for organ and nerve protection. These studies show that artificial hibernation technologies have therapeutic significance on nerve injury after spinal cord injury through inflammatory inhibition, immunosuppression, oxidative defense, and possible central protection. It also promotes the repair and protection of respiratory and digestive, cardiovascular, locomotor, urinary, and endocrine systems. This review provides new insights for the clinical treatment of nerve and multiple organ protection after spinal cord injury thanks to artificial hibernation. At present, artificial hibernation technology is not mature, and research faces various challenges. Nevertheless, the effort is worthwhile for the future development of medicine.

PECULIARITIES OF CORRELATION PATTERNS BETWEEN MUSCULOSKELETAL AND DENTOALVEOLAR SYSTEM DISORDERS AND ELEVATED PHYSICAL ACTIVITY IN CHILDREN

Introduction. The physical development and engagement in sports activities have a direct impact on the overall formation of the human body. Previous research on the impact of sports on orthopedic and dental conditions in children has primarily focused on factors and features related to injuries. While some studies have explored the influence of sports on orthopedic conditions, comprehensive research addressing orthopedic and stomatological pathology in connection with sports activities has been lacking.&#x0D; The objective of this study is to investigate the influence of physical activity on the status of both the locomotor and maxillofacial systems and to evaluate their correlation with fundamental anthropometric indicators.&#x0D; Materials and Methods. For this study, a cohort of 78 children (38 girls and 40 boys), aged 14 to 17 years with an average age of 15.5 years, underwent examinations in both 2019-2020 and 2023. A thorough statistical analysis of the gathered data was conducted to draw meaningful conclusions.&#x0D; Orthopedic pathology was observed in 37.21% of individuals engaged in sports and 22.86% of those who did not participate (p=0.263). Dental pathology was found in 23.26% of individuals involved in sports compared to 17.14% in those who did not engage in sports (p=0.581). Over a span of 3 years, individuals participating in sports experienced an average weight change of 14.82 kg, while those not involved in sports had an average change of 10.31 kg (p=0.02). The average height was 177.0 cm in individuals with orthopedic pathology and 170.0 cm in those without a diagnosed orthopedic condition (p=0.008). The mean growth over 3 years was 15.0 cm in individuals with orthopedic pathology and 9.0 cm in those without an established orthopedic diagnosis (p=0.032). Children with dental pathology gained an average of 8.34 kg of body weight over 3 years, whereas those without dental pathology gained 13.89 kg (p=0.019).&#x0D; Conclusions. Engaging in sports activities does not significantly impact the occurrence or development of orthopedic and stomatological pathology. Anthropometric indicators, specifically height and body weight, are associated with orthopedic and dental pathology, respectively. Children exhibiting greater and more intensive growth tend to have a higher frequency of orthopedic pathology. Dental pathology is more prevalent in children with lower body weight.

The dual function of prokinesis in the feeding and locomotor systems of parrots.

Prokinesis, a mode of avian cranial kinesis involving motion between the neurocranium and upper beak, has long been investigated in biomechanical analyses of avian feeding and drinking. However, the modern avian beak is also used for non-feeding functions. Here, we investigate the dual function of prokinesis in the feeding and locomotor systems of the rosy-faced lovebird (Agapornis roseicollis). Lovebirds and other parrots utilize their beak both during feeding and as a third limb during vertical climbing. Thus, we experimentally measured both force-generating potential and movement of the rosy-faced lovebird mandible and maxilla (via prokinetic flexion of the craniofacial hinge) during tripedal climbing and mandibular/maxillary adduction. We found that whereas the maxilla is primarily responsible for generating force during locomotion, the mandible is primarily responsible for generating force during forceful jaw adduction, hinting at a remarkable capacity to alter prokinetic function with differing neuromuscular control. The ability of the prokinetic apparatus to perform functions with competing optimality criteria via modulation of motor control illustrates the functional plasticity of the avian cranial kinesis and sheds new light on the adaptive significance of cranial mobility.

Omnidirectional propulsion in a metachronal swimmer.

Aquatic organisms often employ maneuverable and agile swimming behavior to escape from predators, find prey, or navigate through complex environments. Many of these organisms use metachronally coordinated appendages to execute complex maneuvers. However, though metachrony is used across body sizes ranging from microns to tens of centimeters, it is understudied compared to the swimming of fish, cetaceans, and other groups. In particular, metachronal coordination and control of multiple appendages for three-dimensional maneuvering is not fully understood. To explore the maneuvering capabilities of metachronal swimming, we combine 3D high-speed videography of freely swimming ctenophores (Bolinopsis vitrea) with reduced-order mathematical modeling. Experimental results show that ctenophores can quickly reorient, and perform tight turns while maintaining forward swimming speeds close to 70% of their observed maximum-performance comparable to or exceeding that of many vertebrates with more complex locomotor systems. We use a reduced-order model to investigate turning performance across a range of beat frequencies and appendage control strategies, and reveal that ctenophores are capable of near-omnidirectional turning. Based on both recorded and modeled swimming trajectories, we conclude that the ctenophore body plan enables a high degree of maneuverability and agility, and may be a useful starting point for future bioinspired aquatic vehicles.

The effects of temperature on elastic energy storage and release in a system with a dynamic mechanical advantage latch.

Changes in temperature alter muscle kinetics and in turn affect whole-organism performance. Some organisms use the elastic recoil of biological springs, structures which are far less temperature sensitive, to power thermally robust movements. For jumping frogs, the use of elastic energy in tendons is facilitated through a geometric latching mechanism that operates through dynamic changes in the mechanical advantage (MA) of the hindlimb. Despite the well-documented use of elastic energy storage, frog jumping is a locomotor behavior that is significantly affected by changes in temperature. Here, we used an in vitro muscle preparation interacting in real time with an in silico model of a legged jumper to understand how changes in temperature affect the flow of energy in a system using a MA latch. We used the plantaris longus muscle-tendon unit (MTU) to power a virtual limb with changing MA and a mass being accelerated through a real-time feedback controller. We quantified the amount of energy stored in and recovered from elastic structures and the additional contribution of direct muscle work after unlatching. We found that temperature altered the duration of the energy loading and recovery phase of the in vitro/in silico experiments. We found that the early phase of loading was insensitive to changes in temperature. However, an increase in temperature did increase the rate of force development, which in turn allowed for increased energy storage in the second phase of loading. We also found that the contribution of direct muscle work after unlatching was substantial and increased significantly with temperature. Our results show that the thermal robustness achieved by an elastic mechanism depends strongly on the nature of the latch that mediates energy flow, and that the relative contribution of elastic and direct muscle energy likely shapes the thermal sensitivity of locomotor systems.

Effect of distance cue and walking speed on matching and discrimination of visually simulated walking speed in treadmill-based locomotor VR

For synchronized treadmill-based virtual reality locomotor systems, the simulated walking speed (SWSof), which is based on optic flow information in the virtual environment, should be perceived as fast as the true walking speed (TWS), which is based on the treadmill. However, previous research has indicated that people often underestimate the SWSof physically equivalent to the TWS in such systems, and the underestimation varies among conditions. Thus, in this study, we focused on factors that influence (1) the difference between the SWSof and the TWS when the two speeds are perceived equivalently and (2) the minimum SWSof that can be perceptually discriminated from the TWS. The two values were obtained by the method of constant stimuli. With a constant TWS (1, 2, or 4 km/h), participants judged if the speed of presented SWSof was perceived faster than their perceived TWS, for various SWSof, in the two different types of virtual environment (with rich distance cues or with poor distance cues). The results showed that the difference between the TWS and the perceptually matched SWSof (level of underestimation) was affected by both the distance cue and TWS. The virtual environment with rich distance cues and a low TWS resulted in a larger underestimation. In addition, for the discrimination threshold, the results showed that a high TWS resulted in a larger discrimination threshold.

Crude saliva of Amblyomma cajennense sensu stricto (Acari: Ixodidae) reduces locomotor activity and increases the hemocyte number in the females of Aedes aegypti (Diptera: Culicidae)

Aedes aegypti are vector insects of arboviruses such as dengue, Zika, and chikungunya. All available vector control methods have limited efficacy, highlighting the urgent need to find alternative ones. Evidence shows that arachnids like ticks are sources of biologically active compounds. Moreover, chemical modulation of the locomotor and immune systems of vector insects can be used to control arbovirus transmission. The present study evaluated the effectiveness of crude saliva of female Amblyomma cajennense sensu stricto (s.s.) ticks in reducing locomotor activity and inducing an immune response in Ae. aegypti females. Additionally, the study evaluated the protein constitution of tick saliva. For this purpose, the crude saliva obtained from several semi-engorged A. cajennense females was used. A volume of 0.2 nL of crude tick saliva was administered to mosquitoes by direct intrathoracic microinjection. The effect of the tick's saliva on the locomotor activity of the mosquito was observed using Flybox, a video-automated monitoring system, and the hemolymph hemocyte levels were quantified by reading slides under a light microscope. The protein concentration of the crude tick saliva was 1.27 μg/μL, and its electrophoretic profile indicates the presence of proteins with a molecular weight ranging between ∼17 and 95 kDa. Microplusins, ixodegrins, cystatin, actins, beta-actin, calponin, albumin, alpha-globulins, and hemoglobin were the main proteins identified by proteomics in the saliva of A. cajennense. The microinjected saliva had low toxicity for Ae. aegypti females and significantly reduced their locomotor activity, especially in the transition between the light and dark phases. The crude tick saliva did not change the period and rhythmicity of the circadian cycle. The tick saliva significantly increased the number of hemocytes two days after injection and reduced it after five days. These results suggest that further evaluation of the biological properties of tick saliva proteins against Ae. aegypti would be of interest.

The Flexible Armor of Chinese Sturgeon: Potential Contribution of Fish Skin on Fracture Toughness and Flexural Response.

Fish skin is a biological material with high flexibility and compliance and can provide good mechanical protection against sharp punctures. This unusual structural function makes fish skin a potential biomimetic design model for flexible, protective, and locomotory systems. In this work, tensile fracture tests, bending tests, and calculation analyses were conducted to study the toughening mechanism of sturgeon fish skin, the bending response of the whole Chinese sturgeon, and the effect of bony plates on the flexural stiffness of the fish body. Morphological observations showed some placoid scales with drag-reduction functions on the skin surface of the Chinese sturgeon. The mechanical tests revealed that the sturgeon fish skin displayed good fracture toughness. Moreover, flexural stiffness decreased gradually from the anterior region to the posterior region of the fish body, which means that the posterior region (near the tail) had higher flexibility. Under large bending deformation, the bony plates had a specific inhibition effect on the bending deformation of the fish body, especially in the posterior region of the fish body. Furthermore, the test results of the dermis-cut samples showed that the sturgeon fish skin had a significant impact on flexural stiffness, and the fish skin could act as an external tendon to promote effective swimming motion.

Influence of coronary artery disease on cardiolocomotor coupling during walking: a preliminary study

The mechanisms involved in the coupling between cardiac and locomotor rhythms in patients with heart disease remain unclear. It was speculated that reduced function of the cardiovascular and/or locomotor systems would increase the coupling of these systems to increase energy efficiency in response to increased energy demand during exercise. We investigated the development of cardiolocomotor coupling (CLC) in patients with coronary artery disease. Eight outpatients with coronary artery disease (CAD group) and eight healthy individuals (control group) underwent cardiopulmonary exercise testing involving a cycle ergometer ramp protocol and treadmill walk test to record CLC strength. The coefficient of determination (R2 value) of the interval between R waves on the electrocardiograph and step interval reflects CLC strength intensity. The Student’s t-test was used to compare cardiopulmonary exercise testing data and R2 values between the study groups. The R2 value was significantly higher in the CAD group than the control group. Peak oxygen uptake and oxygen uptake at the anaerobic threshold were significantly lower in the CAD group than the control group. Our findings showed that CLC intensity was higher in patients with CAD, suggesting that CLC is more likely to occur in individuals with reduced exercise tolerance due to cardiorespiratory deterioration. Key highlights Eight outpatients with coronary artery disease and eight healthy individuals underwent cardiopulmonary exercise and treadmill walk tests to determine cardiolocomotor coupling strength and physiological characteristics. This study reports a stronger cardiolocomotor coupling during exercise in patients with coronary artery disease compared with healthy individuals, suggesting that cardiolocomotor coupling is more likely to occur in people with reduced exercise tolerance attributed to impaired cardiorespiratory function. Our results support the theory that patients with cardiorespiratory impairment due to coronary artery disease have greater dynamic interaction between the locomotor and cardiovascular systems during exercise, which is concurrent with the hypothesis that cardiolocomotor coupling is a compensatory phenomenon for exercise maintenance.

Study on the explicitation of implicit knowledge and the construction of knowledge graph on moxibustion in medical case records of ZHOU Mei-sheng's Jiusheng

To explore the methods of the explicitation of implicit knowledge and the construction of knowledge graph on moxibustion in medical case records of ZHOU Mei-sheng's Jiusheng. The medical case records data of Jiusheng was collected, the frequency statistic was analyzed based on Python3.8.6, complex network analysis was performed using Gephi9.2 software, community analysis was performed by the ancient and modern medical case cloud platform V2.3.5, and analysis and verification of correlation graph and weight graph were proceed by Neo4j3.5.25 image database. The disease systems with frequency≥10 % were surgery, ophthalmology and otorhinolaryngology, locomotor, digestive and respiratory systems. The diseases under the disease system were mainly carbuncle, arthritis, lumbar disc herniation and headache. The commonly used moxibustion methods were fumigating moxibustion, blowing moxibustion, direct moxibustion and warming acupuncture. The core prescription of points obtained by complex network analysis included Yatong point, Zhiyang(GV 9), Sanyinjiao(SP 6), Dazhui(GV 14), Zusanli(ST 36), Lingtai(GV 10), Xinshu(BL 15), Zhijian point and Hegu(LI 4), which were basically consistent with high-frequency points. A total of 6 communities were obtained by community analysis, corresponding to different diseases. Through the analysis of correlation graph, 13 pairs of strong association rule points were obtained. The correlation between Zhiyang(GV 9)-Dazhui(GV 14) and Yatong point-Lingtai(GV 10) was the strongest. The acupoints with high correlation with Yatong point were Zhiyang(GV 9), Lingtai(GV 10), Dazhui(GV 14), Zusanli(ST 36) and Sanyinjiao(SP 6). In the weight graph of the high-frequency disease system, the relationship of the first weight of the surgery system disease was fumigating moxibustion-carbuncle-Yatong point, and the relationship of the first weight of the ophthalmology and otorhinolaryngology system disease was blowing moxibustion-laryngitis-Hegu (LI 4). The results of correlation graph and weight graph are consistent with the results of data mining, which can be used as an effective way to study the knowledge base of moxibustion diagnosis and treatment in the future.

Study on the explicitation of implicit knowledge and the construction of knowledge graph on moxibustion in medical case records of ZHOU Mei-sheng's Jiusheng

To explore the methods of the explicitation of implicit knowledge and the construction of knowledge graph on moxibustion in medical case records of ZHOU Mei-sheng's Jiusheng. The medical case records data of Jiusheng was collected, the frequency statistic was analyzed based on Python3.8.6, complex network analysis was performed using Gephi9.2 software, community analysis was performed by the ancient and modern medical case cloud platform V2.3.5, and analysis and verification of correlation graph and weight graph were proceed by Neo4j3.5.25 image database. The disease systems with frequency≥10 % were surgery, ophthalmology and otorhinolaryngology, locomotor, digestive and respiratory systems. The diseases under the disease system were mainly carbuncle, arthritis, lumbar disc herniation and headache. The commonly used moxibustion methods were fumigating moxibustion, blowing moxibustion, direct moxibustion and warming acupuncture. The core prescription of points obtained by complex network analysis included Yatong point, Zhiyang(GV 9), Sanyinjiao(SP 6), Dazhui(GV 14), Zusanli(ST 36), Lingtai(GV 10), Xinshu(BL 15), Zhijian point and Hegu(LI 4), which were basically consistent with high-frequency points. A total of 6 communities were obtained by community analysis, corresponding to different diseases. Through the analysis of correlation graph, 13 pairs of strong association rule points were obtained. The correlation between Zhiyang(GV 9)-Dazhui(GV 14) and Yatong point-Lingtai(GV 10) was the strongest. The acupoints with high correlation with Yatong point were Zhiyang(GV 9), Lingtai(GV 10), Dazhui(GV 14), Zusanli(ST 36) and Sanyinjiao(SP 6). In the weight graph of the high-frequency disease system, the relationship of the first weight of the surgery system disease was fumigating moxibustion-carbuncle-Yatong point, and the relationship of the first weight of the ophthalmology and otorhinolaryngology system disease was blowing moxibustion-laryngitis-Hegu (LI 4). The results of correlation graph and weight graph are consistent with the results of data mining, which can be used as an effective way to study the knowledge base of moxibustion diagnosis and treatment in the future.探究周楣声《灸绳》医案灸法隐性知识显性化及其知识图谱构建的方法。收集《灸绳》医案数据，基于Python3.8.6进行频数统计分析，利用Gephi9.2软件进行复杂网络分析，登录古今医案云平台V2.3.5进行社团分析，并运用Neo4j3.5.25图数据库进行关联图谱和权值图谱的分析及验证。出现频率≥10%的疾病系统分别为外科、五官、运动、消化和呼吸系统。疾病系统下属疾病以痈、关节炎、腰椎间盘突出症、头痛为主。治疗常用灸法为熏灸、吹灸、直接灸和温针灸。复杂网络分析所得腧穴核心组方为压痛穴、至阳、三阴交、大椎、足三里、灵台、心俞、指尖、合谷，基本与高频腧穴相一致。社团分析共得到6个社团，分别与不同疾病相对应。关联图谱分析得到强关联规则穴对13条，至阳-大椎、压痛穴-灵台的关联性最强，与压痛穴关联性较高的腧穴为至阳、灵台、大椎、足三里、三阴交。高频疾病系统权值图谱中，外科系统疾病权值排名第一的关系为熏灸-痈-压痛穴，五官系统疾病权值排名第一的关系为吹灸-喉炎-合谷。关联图谱及权值图谱所得结论与数据挖掘结果相一致，可作为未来研究灸法诊疗知识库的有效途径。.

Higher diversity of Brucella canis in Latin America, according to an MLVA_13 Bc analysis

Brucella canis is the main causative agent of canine brucellosis, which affects domestic and wild canids and leads to clinical signs and symptoms of the reproductive and locomotor systems. Owing to the scarce information on this pathogen, here we addressed the genetic diversity of the circulating strains of this species in Argentina by following an MVLA_13 Bc scheme. The analyzed sample set consisted of 101 strains of B. canis isolates collected between 2006 and 2020 from canines of the Autonomous City of Buenos Aires (CABA) and other regions of Argentina, as well as 235 isolates from North America. The analysis yielded 336 variants (Hunter–Gaston Diversity Index, HGDI equal to 1.0) showing high diversity on a global scale. The analysis of the six most variable markers also reveled high diversity and allowed further analysis regarding variant relationships. Although the diversity obtained using both schemes (all or the 6 most variable markers) was higher for the Latin American than for the North American strains, we cannot discard that this was due to biases in the sampling methodology or to the different health policies employed in these regions regarding the management of infected individuals. Altogether, the Argentine circulating strains are genetically diverse, but with no apparent geographical association. The markers used in the MLVA_13 Bc are variable and highly useful for the evaluation of outbreaks. Furthermore, the reduced panel of 6 markers (MLVA_6 Bc) proposed in this study is convenient for the study of B. canis strain diversity.

Design features of the kinematic chain of the ant exoskeleton

New challenges in engineering design are about resilience, frugality and sustainability. Nature offers remarkable examples of successful mechanical designs that respond to those constraints. Therefore, biological systems deserve to be explored from a design perspective. The study of design features of biological locomotor systems would allow engineers to get inspiration for solving technological problems. The ant Messor barbarus is specialized in load bearing; hence the interest of studying their skeletal structure from an engineering perspective. In this work, we propose a topological architecture of the ant exoskeleton for kinematic analysis. The proposed architecture is obtained by a geometrical analysis of the articular surfaces of the exoskeleton joints. In this analysis, the mobility as well as the geometrical parameters of the joints are estimated from a 3D geometrical model of the ant exoskeleton. This model was obtained from X-ray micro-computed tomography. The proposed topological architecture was implemented in a multibody model and evaluated by means of inverse kinematic simulations. The results of these simulations, in terms of the root mean square errors (RMSE) regarding the input kinematic data, suggest that the proposed topological architecture is able to reproduce well the kinematic during walking of this ant. This study is one step toward a better understanding of the locomotor performance features of ants.

Dynamic visual acuity during asymmetric walking

Necessary for effective ambulation, head stability affords optimal conditions for the perception of visual information during dynamic tasks. This maintenance of head-in-space equilibrium is achieved, in part, by the attenuation of the high frequency impact shock resulting from ground contact. While a great deal of experimentation has been done on the matter during steady state locomotion, little is known about how locomotor asymmetry might affect head stability or dynamic visual acuity. In this study, fifteen participants walked on a split-belt treadmill while verbally reporting the orientation of a randomized Landolt-C optotype that was projected at heel strike. Participants were exposed to baseline, adaptation, and washout conditions, as characterized by belt speed ratios of 1:1, 1:3, and 1:1, respectively. Step length asymmetry, shock attenuation, high and low frequency head signal power, and dynamic visual acuity were averaged across the first and last fifty strides of each condition. Across the first fifty strides, step length asymmetry was significantly greater during adaptation than during baseline (p<0.001; d=2.442), and shock attenuation was significantly lower during adaptation than during baseline (p=0.041; d=-0.679). High frequency head signal power was significantly greater during adaptation than during baseline (p<0.001; d=-1.227), indicating a reduction in head stability. While dynamic visual acuity was not significantly lower during adaptation than during baseline (p=0.052), a moderate effect size suggests a decrease in the measure between the two conditions (d=0.653). Across the last fifty strides, many of the decrements observed between the baseline and adaptation conditions were greatly reduced. The results of this study indicate that the locomotor asymmetry imposed by the split-belt treadmill during early adaptation might lead to moderate decrements in shock attenuation, head stability, and dynamic visual acuity. Moreover, the relative reduction in magnitude of these decrements across the last fifty strides underscores the adaptive nature of the locomotor and visuomotor systems.

A Step Forward: Functional Diversity and Emerging Themes of Slow-Speed Locomotion in Vertebrates.

Walking can be defined broadly as a slow-speed movement produced when appendages interact with the ground to generate forward propulsion. Until recently, most studies of walking have focused on humans and a handful of domesticated vertebrates moving at a steady rate over highly simplified, static surfaces, which may bias our understanding of the unifying principles that underlie vertebrate locomotion. In the last few decades, studies have expanded to include a range of environmental contexts (e.g., uneven terrain, perturbations, deformable substrates) and greater phylogenetic breadth (e.g., non-domesticated species, small and/or ectothermic tetrapods and fishes); these studies have revealed that even a gait as superficially simple as walking is far more complex than previously thought. In addition, technological advances and accessibility of imaging systems and computational power have recently expanded our capabilities to test hypotheses about the locomotor movements of extant and extinct organisms in silico. In this symposium, scientists showcased diverse taxa (from extant fishes to extinct dinosaurs) moving through a range of variable conditions (speed perturbations, inclines, and deformable substrates) to address the causes and consequences of functional diversity in locomotor systems and discuss nascent research areas and techniques. From the symposium contributions, several themes emerged: (1) slow-speed, appendage-based movements in fishes are best described as walking-like movements rather than true walking gaits, (2) environmental variation (e.g., deformable substrates) and dynamic stimuli (e.g., perturbations) trigger kinematic and neuromuscular changes in animals that make defining a single gait or the transition between gaits more complicated than originally thought, and (3) computational advances have increased the ability to process large data sets, emulate the 3D motions of extant and extinct taxa, and even model species interactions in ancient ecosystems. Although this symposium allowed us to make great strides forward in our understanding of vertebrate walking, much ground remains to be covered. First, there is a much greater range of vertebrate appendage-based locomotor behaviors than has been previously recognized and existing terminology fails to accurately capture and describe this diversity. Second, despite recent efforts, the mechanisms that vertebrates use modify locomotor behaviors in response to predictable and unpredictable locomotor challenges are still poorly understood. Third, while computer-based models and simulations facilitate a greater understanding of the kinetics and kinematics of movement in both extant and extinct animals, a universal, one-size-fits-all, predictive model of appendage-based movement in vertebrates remains elusive.

The Magnetic Resonance Imaging Pattern of the Lesions Caused by Knee Overuse in the Pediatric Population.

Background and Objectives: Excessive use of the knee in patients with immature locomotor systems leads to a whole spectrum of morphological changes with possible consequences in adulthood. This study aimed to examine the morphological pattern in magnetic resonance imaging (MRI) that is associated with recurrent pain due to increased physical activity in children. Materials and Methods: This was a retrospective study conducted among pediatric patients treated at the University Children’s Hospital in Belgrade in 2018 and 2019. MRI findings of patients who reported recurrent pain in the knee joint during physical activity and who were without any pathological findings on both clinical examination and knee radiographs were included in the study. Results: MRI findings of 168 patients (73 boys and 95 girls, mean age 14.07 ± 3.34 years) were assessed. Meniscus and cartilage lesions were the most commonly detected morphological findings: meniscus lesions in 49.4%, cartilage ruptures in 44.6%, and cartilage edema in 26.2% of patients. The medial meniscus was more often injured in girls (p = 0.030), while boys were more prone to other joint injuries (p = 0.016), re-injury of the same joint (p = 0.036), bone bruises (p < 0.001), and ligament injuries (p = 0.001). In children older than 15 years, tibial plateau cartilage edema (p = 0.016), chondromalacia patellae (p = 0.005), and retropatellar effusion (p = 0.011) were detected more frequently compared to younger children. Conclusions: Children reporting recurrent knee pain due to increased physical activity, without any detected pathological findings on clinical examination and knee radiography, may have morphological changes that can be detected on MRI. Timely diagnosis of joint lesions should play a significant role in preventing permanent joint dysfunction in the pediatric population as well as in preventing the development of musculoskeletal diseases in adulthood.