Regulation Of Tension Research Articles

Coordination of force-generating actin-based modules stabilizes and remodels membranes in vivo.

Membrane remodeling drives a broad spectrum of cellular functions, and it is regulated through mechanical forces exerted on the membrane by cytoplasmic complexes. Here, we investigate how actin filaments dynamically tune their structure to control the active transfer of membranes between cellular compartments with distinct compositions and biophysical properties. Using intravital subcellular microscopy in live rodents we show that a lattice composed of linear filaments stabilizes the granule membrane after fusion with the plasma membrane and a network of branched filaments linked to the membranes by Ezrin, a regulator of membrane tension, initiates and drives to completion the integration step. Our results highlight how the actin cytoskeleton tunes its structure to adapt to dynamic changes in the biophysical properties of membranes.

Membrane Tension Regulation is Required for Wound Repair.

Disruptions of the eukaryotic plasma membrane due to chemical and mechanical challenges are frequent and detrimental and thus need to be repaired to maintain proper cell function and avoid cell death. However, the cellular mechanisms involved in wound resealing and restoration of homeostasis are diverse and contended. Here, it is shown that clathrin-mediated endocytosis is induced at later stages of plasma membrane wound repair following the actual resealing of the wound. This compensatory endocytosis occurs near the wound, predominantly at sites of previous early endosome exocytosis which is required in the initial stage of membrane resealing, suggesting a spatio-temporal co-ordination of exo- and endocytosis during wound repair. Using cytoskeletal alterations and modulations of membrane tension and membrane area, membrane tension is identified as a major regulator of the wounding-associated exo- and endocytic events that mediate efficient wound repair. Thus, membrane tension changes are a universal trigger for plasma membrane wound repair modulating the exocytosis of early endosomes required for resealing and subsequent clathrin-mediated endocytosis acting at later stages to restore cell homeostasis and function.

Unraveling the impact of pH, sodium concentration, and medium osmolality on Vibrio natriegens in batch processes

BackgroundVibrio natriegens, a halophilic marine γ-proteobacterium, holds immense biotechnological potential due to its remarkably short generation time of under ten minutes. However, the highest growth rates have been primarily observed on complex media, which often suffer from batch-to-batch variability affecting process stability and performance. Consistent bioprocesses necessitate the use of chemically defined media, which are usually optimized for fermenters with pH and dissolved oxygen tension (DOT) regulation, both of which are not applied during early-stage cultivations in shake flasks or microtiter plates. Existing studies on V. natriegens’ growth on mineral media report partially conflicting results, and a comprehensive study examining the combined effects of pH buffering, sodium concentration, and medium osmolality is lacking.ResultsThis study evaluates the influence of sodium concentration, pH buffering, and medium osmolality on the growth of V. natriegens under unregulated small-scale conditions. The maximum growth rate, time of glucose depletion, as well as the onset of stationary phase were observed through online-monitoring the oxygen transfer rate. The results revealed optimal growth conditions at an initial pH of 8.0 with a minimum of 300 mM MOPS buffer for media containing 20 g/L glucose or 180 mM MOPS for media with 10 g/L glucose. Optimal sodium chloride supplementation was found to be between 7.5 and 15 g/L, lower than previously reported ranges. This is advantageous for reducing industrial corrosion issues. Additionally, an osmolality range of 1 to 1.6 Osmol/kg was determined to be optimal for growth. Under these optimized conditions, V. natriegens achieved a growth rate of 1.97 ± 0.13 1/h over a period of 1 h at 37 °C, the highest reported rate for this organism on a mineral medium.ConclusionThis study provides guidelines for cultivating V. natriegens in early-stage laboratory settings without pH and DOT regulation. The findings suggest a lower optimal sodium chloride range than previously reported and establish an osmolality window for optimal growth, thereby advancing the understanding of V. natriegens’ physiology. In addition, this study offers a foundation for future research into the effects of different ions and carbon sources on V. natriegens.

Crystalline Texture Reengineering of Zinc Powder-Based Fibrous Anode for Remarkable Mechano-Electrochemical Stability.

The challenge of inadequate mechano-electrochemical stability in rechargeable fibrous Zn-ion batteries (FZIBs) has emerged as a critical challenge for their broad applications. Traditional rigid Zn wires struggle to maintain a stable electrochemical interface when subjected to external mechanical stress. To address this issue, a wet-spinning technique has been developed to fabricate Zn powder based fibrous anode, while carbon nanotubes (CNTs) introduced to enhance the spinnability of Zn powder dispersion. The followed annealing treatment has been conducted to reengineer the Zn crystalline texture with CNTs assisted surface tension regulation to redirect (002) crystallographic textural formation. The thus-derived annealed Zn@CNTs fiber demonstrates great mechano-electrochemical stability after a long-term bending and electrochemical process. The fabricated FZIB demonstrates a remarkable durability, surpassing 800h at 1mAcm-2 and 1mAhcm-2, with a marginal voltage hysteresis increase of 21.7mV even after 100 twisting cycles under 180 degree twisting angle. The assembled FZIB full cell displays an 88.6% capacity retention even after a long cycle of a series of bending, knotting, and straightening deformation. It has been also woven into a 200cm2 size textile to demonstrate its capability to integrate into smart textiles.

The state against the environment? Water management and the regulation of tensions between sectoral policies in France

AbstractThe effectiveness and efficiency of environmental policy largely depends on how other policies take account of ecological objectives, whether in the industrial, agricultural, urban planning, transport, housing or budget sectors. The state bears responsibility for how these public policies interrelate, including establishing a hierarchy of priority or allowing one area to ignore another. What can we learn about environmental policy from an analysis of the tensions between multiple sectoral policies, and more generally about the state and the political and institutional functioning that shapes the management of an environmental issue? Taking water management in France as a case study, this article argues that an approach focused on the regulation of tensions between various public policies can shed new light on the structural difficulties of environmental policy. It shows how ideas, norms, interests, strategies, professional cultures, and so forth, that underpin public policy outside the environmental field shape the handling of ecological issues. It also highlights the way the state views and handles these tensions between policies through institutional arrangements and socio‐political compromises with influential sectoral actors and social groups.

Shape-fixing hydrogel promotes scarless healing of wounds under tension

The healing of a wound under tension (hereafter, “tension wound”) often coincides with the development of hypertrophic scars in clinical settings. Currently, compress bandages offer a potential alternative for the healing of tension wounds; however, their application in surgery is limited due to their prefabricated patch form. To overcome this, a tension-shielding hydrogel system was designed using photocurable catechol-grafted hyaluronic acid and tannic-acid silver nanoparticles (hereafter, “HTA system”). The hydrogel exhibited tension-shielding capacity, reducing wound tension via shape-fixation and ultimately reducing scar formation. The HTA hydrogel exhibited superior photothermal antibacterial efficacy, self-healing properties, and effective dissipation of energy, thereby promoting tissue regeneration. The hydrogel significantly inhibited the mechanotransduction pathway, thus preventing Engrailed-1 activation and reducing the fibrotic response. The HTA hydrogel system, therefore, provides a treatment strategy for tension wounds, burn wounds and other wounds that are prone to form hypertrophic scars via creating a tension-free local environment. Statement of significanceIn our study, we presented a wound-dressing hydrogel system (HTA) that exhibit shape-fixing capacity in tension wound model. Here, we designed and modified a tension regulator, applied it to mice, and furthermore, established a tension wound model in mice with adjustable tension. Outcomes showed that the HTA hydrogel system can effectively form a shape-fixed environment on tension wounds and dynamic wounds, thus promoting scarless healing. Additionally, HTA performs injectability, rapid crosslinking, biocompatibility, wet adhesion, hemostasis and photothermal antibacterial properties. We believe this research has various potential clinical applications, including scarless-healing in tension wounds, treatment of acute bleeding, treatment of infected wounds, and even internal organ repair.

Process evaluation of an art therapeutic treatment for children and adolescents with psychosocial problems

The Affect regulating Arts Therapies program is an approach designed to address psychosocial problems among children and adolescents. It focuses on improving affect-regulation skills through tension regulation, attention regulation, and affect-regulation phases. This study encompassed a process evaluation, in which treatment integrity, satisfaction, and perceived benefits and barriers were explored. Treatment integrity was investigated by observing therapeutic actions during recorded sessions applied in practice. Satisfaction was evaluated using a survey. Perceived benefits and barriers were examined using semi-structured interviews. Children, adolescents, parents/caregivers, teachers, and art therapists were all involved. All predefined therapeutic actions were observed during therapy sessions, and participants expressed their satisfaction with and understanding of therapists. The identified benefits of the program included acknowledgment of the child/adolescent, non-verbal work, and the creation of art products. Collaboration, favorable therapy conditions, parental involvement, psychoeducation, and the therapist's attitude also contributed to success. Barriers included goal misalignment, logistical/financial issues, emotional problems among parents/caregivers, parental commitment, and limited teacher involvement. The findings affirm ArAT as a promising strategy for addressing psychosocial problems among children and adolescents. Further research is required in order to evaluate the effectiveness of ArAT.

Water-Responsive Self-Contractive Silk-Based Skin Anti-Aging Tensioners with Customizable Biofunctions.

Skin anti-aging treatments have become increasingly popular. Currently, the prevalent treatment method involves implanting skin tension regulation threads (skin lifting threads) under the skin, and radiofrequency treatments. In this study, inspired by the natural supercontraction of spider silk, the molecular structure of silk fibroin fibers is modulated into an oriented configuration. This modification endows silk proteins with water-responsive self-contraction capabilities, leading to the development of innovative self-contracting silk-based skin tensioners (SSSTs). To align with clinical requirements, skin tension regulation materials are functionalized by testing for their self-contraction, near-infrared laser heating function, and bacteriostatic properties. The SSSTs exhibited remarkable self-contraction properties, drug-loading and sustained-release capabilities, notable antibacterial effects, controllable degradation, and good biocompatibility. Moreover, the near-infrared light heating function effectively increased subcutaneous temperature, demonstrating its potential for enhancing and prolonging skin lifting effects. Therefore, SSSTs can be applied for skin tension regulation to improve and delay skin aging. The results may pave the way for novel strategies in skin rejuvenation, with broad implications for the field of skin anti-aging.

Core release dynamics of double-emulsion droplets induced by temperature gradient

The thermocapillary-driven core release of double-emulsion droplets offers advantages such as simplicity in implementation and a broad range of applications, providing unique strengths in the field of core component release. However, the characteristics and mechanisms related to thermocapillary-driven core release were still unknown. This article employed the Volume of Fluid method to investigate the core release characteristics of double-emulsion droplets driven by thermocapillary. The range of Marangoni (Ma) numbers is from 10 to 500. The results indicate that effective control of the migration and release dynamics of double-emulsion droplets can be achieved through viscosity regulation, which induces the obvious difference between the two types of double-emulsion droplets. The regulation of both viscosity and surface tension is efficient in controlling the release type of the core. A phase diagram distinguishing between one-off and two-off release types is presented. Additionally, by characterizing dimensionless numbers, a formula for the characteristic release time of double-emulsion droplets is derived. The current study contributes to achieving precise control of double-emulsion droplets, expanding the scope of applications for double-emulsion droplets and establishing a fundamental groundwork for subsequent investigations into the release methods of double-emulsion droplets driven by thermocapillary.

МІНІМІЗАЦІЯ МІЖКЛІТЬОВОГО НАТЯГУ НА БЕЗПЕРЕРВНИХ СТАНАХ ЗА ЯКІРНИМИ СТРУМАМИ ЕЛЕКТРОПРИВОДІВ ПРОКАТНИХ КЛІТЕЙ

In the conditions of continuous rolling of graded profiles with no or too little metal deflection between adjacent rolling cages, the most promising is tension regulation based on information about the armature currents of the main electric drives. The effectiveness of the method of minimizing the tension of graded rolled products based on information about the armature currents of the main electric drives was investigated. The method is based on the hypothesis of the constant ratio of the armature current of the drive of the next cage to the armature current of the drive of the previous cage in the free rolling mode. The method involves predicting the free-rolling current in rolling electric drives based on information about the free-rolling current in the electric drives of previous cages. The study is based on a complex model of the process of continuous bar rolling in four finishing cages of a small-grade mill with individual electric drives equipped with subordinate speed control systems. Given the fundamental impossibility of approbation of the proposed method by the methods of an industrial experiment, verification of its operability requires computer simulation modeling. The created computer model allows for adequate simulation of the operation of the control system in the conditions of rolling in a continuous group of cages with an accuracy that is sufficient for conclusions about the effectiveness of its operation. According to the results of the study of the control system by means of computer simulation, the effectiveness of its work was proven, in particular, the reduction of the specific tension in all intercell spaces of the finishing group of roll stands to an acceptable level of 10 N/mm2 and a significant narrowing of the range of changes in the width of the finished rolled product.

Regulation of Oxygen Tension as a Strategy to Control Chondrocytic Phenotype for Cartilage Tissue Engineering and Regeneration.

Cartilage defects and osteoarthritis are health problems which are major burdens on health care systems globally, especially in aging populations. Cartilage is a vulnerable tissue, which generally faces a progressive degenerative process when injured. This makes it the 11th most common cause of global disability. Conservative methods are used to treat the initial phases of the illness, while orthopedic management is the method used for more progressed phases. These include, for instance, arthroscopic shaving, microfracturing and mosaicplasty, and joint replacement as the final treatment. Cell-based implantation methods have also been developed. Despite reports of successful treatments, they often suffer from the non-optimal nature of chondrocyte phenotype in the repair tissue. Thus, improved strategies to control the phenotype of the regenerating cells are needed. Avascular tissue cartilage relies on diffusion for nutrients acquisition and the removal of metabolic waste products. A low oxygen content is also present in cartilage, and the chondrocytes are, in fact, well adapted to it. Therefore, this raises an idea that the regulation of oxygen tension could be a strategy to control the chondrocyte phenotype expression, important in cartilage tissue for regenerative purposes. This narrative review discusses the aspects related to oxygen tension in the metabolism and regulation of articular and growth plate chondrocytes and progenitor cell phenotypes, and the role of some microenvironmental factors as regulators of chondrocytes.

Elastic Contractile Stress in the Basement Membrane Generates Basal Tension in Epithelia

The shaping of epithelial tissues into functional organs often depends on dynamic changes of mechanical tension at the apical and basal sides of cells. While on the apical side, tension is known to be regulated by the apical actomyosin meshwork, basal tension regulation remains elusive due to the presence of a basal sheet of specialized extracellular matrix, the basement membrane. Here, we use atomic force microscopy to provide direct measurements of mechanical tension in the basal surface of the wing disk epithelium of in control and perturbed conditions. We find that next to actomyosin, the basement membrane is a key structure for the generation of basal tension. Furthermore, we show that the basement membrane is a solidlike sheet subject to an expansile stretch in epithelial homeostasis. Performing osmotic shocks and optogenetic actomyosin activation, we find evidence that basal stretch and tension can be generated by intracellular hydrostatic pressure and actomyosin tension in lateral cell faces of the epithelium. In conclusion, we propose that elastic contractile stress corresponding to the actomyosin-induced expansile stretch of the basement membrane generates a major contribution to basal tension. We thereby disclose fundamental differences in the mechanical regulation of apical and basal epithelial tension. Published by the American Physical Society 2024

Affect regulating art therapy for children and adolescents experiencing psychosocial problems

ABSTRACT Background The program Affect regulating Art(s) Therapy(ies) (ArAT) has been developed to address self regulation problems in children and adolescents with psychosocial problems. Therapeutic actions are hypothesised to be applied sequentially across three treatment phases: a tension regulation phase, an attention regulation phase, and an affect regulation phase. This study aimed to investigate whether the theoretical framework describing the phases of the ArAT program is observable in practice. Method We collected film recordings of ArAT sessions. These recordings were viewed and rated using a checklist to explore whether the therapeutic actions were present. Results There were no discernible differences in therapeutic interventions across the treatment phases. Therapists frequently utilised therapeutic actions from the tension and attention regulation phases throughout all stages of treatment. Moreover, the frequency of applied therapeutic actions were consistent across all treatment phases, with tension regulation actions being the most frequently applied and attention-improving actions and affect-regulating actions being the least frequently applied. Conclusion The supposed phasing of the development-oriented ArAT program could not be detected in this research, indicating the need to reconsider the stage-wise description of the program. Art therapists need to recognise that reducing stress seems to remain important during all treatment phases. Plain-language summary An art(s) therapeutic program called ArAT has been developed in the Netherlands for children and adolescents with psychosocial problems. ArAT aims to improve the self regulation of emotions so that children and adolescents can better regulate their feelings and therefore have fewer psychosocial problems. The therapist's therapeutic actions are theoretically supposed to be performed in three phases: a tension-regulating phase, an attention-enhancing phase, and an affect-regulating phase. This study aimed to examine whether the phasing could be observed in practice in this way. For this, we have collected films of ArAT sessions from practice. These were examined whether the therapeutic actions were detectable using a checklist. No differences were discernible in the three different phases. What was striking was that the therapists most often use tension-regulating and attention-regulating therapeutic actions. A similar pattern also became visible within each phase: stress-regulating therapeutic actions were used most, then attention-regulating therapeutic actions and affect-regulating actions were used least. The presumed phasing of the developmental ArAT program could not be observed. This suggests that we should think again if and how we describe the different phases of the program. The least used are therapeutic actions intended to develop thinking and talking about feelings. For art therapists, reducing stress seems important during all treatment phases for children and adolescents with psychosocial problems.

Toll-like receptor signalling via IRAK4 affects epithelial integrity and tightness through regulation of junctional tension.

Toll-like receptors (TLRs) in mammalian systems are well known for their role in innate immunity. In addition, TLRs also fulfil crucial functions outside immunity, including the dorsoventral patterning function of the original Toll receptor in Drosophila and neurogenesis in mice. Recent discoveries in flies suggested key roles for TLRs in epithelial cells in patterning of junctional cytoskeletal activity. Here, we address the function of TLRs and the downstream key signal transduction component IRAK4 in human epithelial cells. Using differentiated human Caco-2 cells as a model for the intestinal epithelium, we show that these cells exhibit baseline TLR signalling, as revealed by p-IRAK4, and that blocking IRAK4 function leads to a loss of epithelial tightness involving key changes at tight and adherens junctions, such as a loss of epithelial tension and changes in junctional actomyosin. Changes upon IRAK-4 inhibition are conserved in human bronchial epithelial cells. Knockdown of IRAK4 and certain TLRs phenocopies the inhibitor treatment. These data suggest a model whereby TLR receptors near epithelial junctions might be involved in a continuous sensing of the epithelial state to promote epithelial tightness and integrity.

Differences in Mechanical, Electrical and Calcium Transient Performance of the Isolated Right Atrial and Ventricular Myocardium of Guinea Pigs at Different Preloads (Lengths)

There are only a few studies devoted to the comparative and simultaneous study of the mechanisms of the length-dependent regulation of atrial and ventricular contractility. Therefore, an isometric force-length protocol was applied to isolated guinea pig right atrial (RA) strips and ventricular (RV) trabeculae, with a simultaneous measurement of force (Frank–Starling mechanism) and Ca2+ transients (CaT) or transmembrane action potentials (AP). Over the entire length-range studied, the duration of isometric contraction, CaT and AP, were shorter in the RA myocardium than in the RV myocardium. The RA myocardium was stiffer than the RV myocardium. With the increasing length of the RA and RV myocardium, the amplitude and duration of isometric contraction and CaT increased, as well as the amplitude and area of the “CaT difference curves” (shown for the first time). However, the rates of the tension development and relaxation decreased. No contribution of AP duration to the heterometric regulation of isometric tension was found in either the RA or RV myocardium of the guinea pig. Changes in the degree of overlap of the contractile proteins of the guinea pig RA and RV myocardium mainly affect CaT kinetics but not AP duration.

A Conceptual Exploration of Hamstring Muscle-Tendon Functioning during the Late-Swing Phase of Sprinting: The Importance of Evidence-Based Hamstring Training Frameworks.

An eccentrically lengthening, energy-absorbing, brake-driven model of hamstring function during the late-swing phase of sprinting has been widely touted within the existing literature. In contrast, an isometrically contracting, spring-driven model of hamstring function has recently been proposed. This theory has gained substantial traction within the applied sporting world, influencing understandings of hamstring function while sprinting, as well as the development and adoption of certain types of hamstring-specific exercises. Across the animal kingdom, both spring- and motor-driven muscle-tendon unit (MTU) functioning are frequently observed, with both models of locomotive functioning commonly utilising some degree of active muscle lengthening to draw upon force enhancement mechanisms. However, a method to accurately assess hamstring muscle-tendon functioning when sprinting does not exist. Accordingly, the aims of this review article are three-fold: (1) to comprehensively explore current terminology, theories and models surrounding muscle-tendon functioning during locomotion, (2) to relate these models to potential hamstring function when sprinting by examining a variety of hamstring-specific research and (3) to highlight the importance of developing and utilising evidence-based frameworks to guide hamstring training in athletes required to sprint. Due to the intensity of movement, large musculotendinous stretches and high mechanical loads experienced in the hamstrings when sprinting, it is anticipated that the hamstring MTUs adopt a model of functioning that has some reliance upon active muscle lengthening and muscle actuators during this particular task. However, each individual hamstring MTU is expected to adopt various combinations of spring-, brake- and motor-driven functioning when sprinting, in accordance with their architectural arrangement and activation patterns. Muscle function is intricate and dependent upon complex interactions between musculoskeletal kinematics and kinetics, muscle activation patterns and the neuromechanical regulation of tensions and stiffness, and loads applied by the environment, among other important variables. Accordingly, hamstring function when sprinting is anticipated to be unique to this particular activity. It is therefore proposed that the adoption of hamstring-specific exercises should not be founded on unvalidated claims of replicating hamstring function when sprinting, as has been suggested in the literature. Adaptive benefits may potentially be derived from a range of hamstring-specific exercises that vary in the stimuli they provide. Therefore, a more rigorous approach is to select hamstring-specific exercises based on thoroughly constructed evidence-based frameworks surrounding the specific stimulus provided by the exercise, the accompanying adaptations elicited by the exercise, and the effects of these adaptations on hamstring functioning and injury risk mitigation when sprinting.

3D cell segregation geometry and dynamics are governed by tissue surface tension regulation

Tissue morphogenesis and patterning during development involve the segregation of cell types. Segregation is driven by differential tissue surface tensions generated by cell types through controlling cell-cell contact formation by regulating adhesion and actomyosin contractility-based cellular cortical tensions. We use vertebrate tissue cell types and zebrafish germ layer progenitors as in vitro models of 3-dimensional heterotypic segregation and developed a quantitative analysis of their dynamics based on 3D time-lapse microscopy. We show that general inhibition of actomyosin contractility by the Rho kinase inhibitor Y27632 delays segregation. Cell type-specific inhibition of non-muscle myosin2 activity by overexpression of myosin assembly inhibitor S100A4 reduces tissue surface tension, manifested in decreased compaction during aggregation and inverted geometry observed during segregation. The same is observed when we express a constitutively active Rho kinase isoform to ubiquitously keep actomyosin contractility high at cell-cell and cell-medium interfaces and thus overriding the interface-specific regulation of cortical tensions. Tissue surface tension regulation can become an effective tool in tissue engineering.

Research Progress and Molecular Mechanisms of Endothelial Cells Inflammation in Vascular-Related Diseases.

Endothelial cells (ECs) are widely distributed inside the vascular network, forming a vital barrier between the bloodstream and the walls of blood vessels. These versatile cells serve myriad functions, including the regulation of vascular tension and the management of hemostasis and thrombosis. Inflammation constitutes a cascade of biological responses incited by biological, chemical, or physical stimuli. While inflammation is inherently a protective mechanism, dysregulated inflammation can precipitate a host of vascular pathologies. ECs play a critical role in the genesis and progression of vascular inflammation, which has been implicated in the etiology of numerous vascular disorders, such as atherosclerosis, cardiovascular diseases, respiratory diseases, diabetes mellitus, and sepsis. Upon activation, ECs secrete potent inflammatory mediators that elicit both innate and adaptive immune reactions, culminating in inflammation. To date, no comprehensive and nuanced account of the research progress concerning ECs and inflammation in vascular-related maladies exists. Consequently, this review endeavors to synthesize the contributions of ECs to inflammatory processes, delineate the molecular signaling pathways involved in regulation, and categorize and consolidate the various models and treatment strategies for vascular-related diseases. It is our aspiration that this review furnishes cogent experimental evidence supporting the established link between endothelial inflammation and vascular-related pathologies, offers a theoretical foundation for clinical investigations, and imparts valuable insights for the development of therapeutic agents targeting these diseases.

Homosexual Courtship in Young Wild Capuchin Monkeys: A Case Study.

In primates, many species exhibit same-sex sexual behaviors (SSB), defined as "genital contact or genital manipulation between same-sex individuals." Several sociosexual functions have been proposed, including proceptivity enhancement, receptivity reduction, dominance assertion, practice for heterosexual copulation, tension regulation, reconciliation, and alliance formation. Capuchin monkeys are known for their rich and flexible sexual behavioral repertoire and elaborated courtships. At present, the few reports of SSB in capuchin monkeys (genera Sapajus and Cebus) focused on mounting. Here, we describe the case observed in a population of wild yellow-breasted capuchin monkeys (Sapajus xanthosternos) in which two young males, aged 5-6years and 19months, performed a 15-min uninterrupted sequence of courtship behaviors and mounting. Comparing with a previously established ethogram of 20 behaviors typical for heterosexual behavior of tufted capuchins, we show that these males performed 16 of them. Thus, SSBs are already present in the repertoire of young individuals and the practice may serve to create or strengthen bonds. Although same-sex mounting and genital inspection are common in capuchins' play and other social interactions, the almost entire array of courtship behaviors has never been observed in youngsters. Additionally, this example supports the notion that primate (homo)sexual behavior is not limited to genitalia and copulation, since the observed courtship included diverse behaviors different from genital contact. Thus, we propose a broader definition of sexual behavior.

The surface ectoderm exhibits spatially heterogenous tension that correlates with YAP localisation during spinal neural tube closure in mouse embryos

The single cell layer of surface ectoderm (SE) which overlies the closing neural tube (NT) plays a crucial biomechanical role during mammalian NT closure (NTC), challenging previous assumptions that it is only passive to the force-generating neuroepithelium (NE). Failure of NTC leads to congenital malformations known as NT defects (NTDs), including spina bifida (SB) and anencephaly in the spine and brain respectively. In several mouse NTD models, SB is caused by misexpression of SE-specific genes and is associated with disrupted SE mechanics, including loss of rostrocaudal cell elongation believed to be important for successful closure. In this study, we asked how SE mechanics affect NT morphology, and whether the characteristic rostrocaudal cell elongation at the progressing closure site is a response to tension anisotropy in the SE. We show that blocking SE-specific E-cadherin in ex utero mouse embryo culture influences NT morphology, as well as the F-actin cable. Cell border ablation shows that cell shape is not due to tension anisotropy, but that there are regional differences in SE tension. We also find that YAP nuclear translocation reflects regional tension heterogeneity, and that its expression is sensitive to pharmacological reduction of tension. In conclusion, our results confirm that the SE is a biomechanically important tissue for spinal NT morphogenesis and suggest a possible role of spatial regulation of cellular tension which could regulate downstream gene expression via mechanically-sensitive YAP activity.