Directional Migration Research Articles

Spontaneous built-in electric field in W-W2C@C heterostructure: Accelerating Sn2- directed migration in Li-S batteries

The commercialization of Li-S batteries is severely hindered by shuttle effect and sluggish redox reaction kinetics of LiPSs. Heterostructure can resolve the above shortcomings through the synergistic effect of adsorption and catalysis. However, long-chain LiPSs dissolving in electrolyte tend to cluster, resulting in low sulfur utilization and preventing kinetic conversion Thus, it is necessary to regulate the diffusion of Sn2− to achieve the directional diffusion from adsorbent to catalyst. Nevertheless, the design principle has not yet been clarified. W-W2C@C heterostructure with W of strong adsorption ability and high work function and W2C of excellent catalytic activity and low work function is designed by theoretical screening. Due to work function difference, this heterostructure controls the direction of the interface built-in electric field (BIEF), realizing the directional migration process of Sn2− from adsorptive W to catalytic W2C, thereby achieving a continuous “trapping-directional migration-conversion” reaction mechanism. The batteries have an excellent Li+ diffusion rate, high initial discharge specific capacity (1400.6 mAh/g at 0.2C), excellent rate capability (853.2 mAh/g at 2C), high reversible capacity (977.9 mAh/g after 150 cycles at 0.2C) and an extremely low capacity decay rate of 0.09 % per cycle after 300 cycles at 1C.

An experimental and theoretical validation of dual role of Fe on improving the photocatalytic performance of doped mixed phase titania

The present work proposes a strategic approach of using Fe doping to form a mixed-phase TiO2 direct Z-scheme catalyst at low onset temperature. The doping-induced modifications are explained from the experimental and theoretical viewpoint. Fe-doped Z-scheme-based mixed-phase TiO2 at optimal calcination temperature (TiFe-400) exhibits maximum photon absorption and reduces charge carrier recombination, enhancing photocatalytic and PEC performance. TiFe-400 has the highest rate constant for the degradation of MB (0.084 min−1 under solar irradiation) and showed exceptional photooxidation current (0.8 mA, 1.3 V vs Ag/AgCl). The Z-scheme formation significantly inhibits the recombination of photocarriers, resulting in a directed migration of charge carriers to the high redox potential mixed-phase TiO2. This migration is validated by identifying the primary reactive species participating in the photocatalytic process. This work, demonstrating both experimental and theoretical approaches, may provide valuable insight into designing stable and inexpensive catalysts for dual applications on an industrial scale.

Lifecycle of an Isolated Seismic Swarm in Continental Southern Norway from Nucleation, Acceleration, and Yielding to the Demise of Fault Slip

Abstract An intraplate earthquake swarm started near the Bitdal valley in the seismically inactive mountains of Southern Norway in summer 2020 and continued for more than two years. We detected 1600 earthquakes through template matching and obtained high-resolution relative magnitudes and locations for the events to resolve the swarm’s spatiotemporal evolution and tectonic implications. The detection results reveal that no earthquakes occurred at the swarm site for at least 22 yr prior to the current activity. In July 2020, six months before the swarm’s initially recognized onset, weak precursory events appeared. Hypocenter relocation shows that the swarm develops along a single 1.5 km patch on a northwest–southeast-striking fault with oblique-normal sense containing a left-lateral component. The seismicity follows a dual-velocity migration for which the slow, general migration reverses sense twice, and 30 short bursts show internal migration both with and against the general migration direction. Changes in the distribution of events let us divide the swarm into four phases: precursory activity, accelerating growth, main slip, and slow decline. The observed seismicity bursts, pauses, and dual migration velocities are consistent with a rupture-driven mechanism for which slip initiates spontaneously and keeps going in slow and quick failure cascades due to stress transfer and slip weakening.

Micro-fluidic covalent immobilization of multi-gradient RGD peptides on a gelatin surface for studying endothelial cell migration.

Collective endothelial migration is a hallmark of wound healing, which is regulated by spatial concentration gradients of extracellular biochemical factors. Arginine-glycine-aspartate (RGD) peptides play a vital role in regulating cell migration through specific binding to integrins. In this study, a micro-fluidic technology combined with a photopolymerization technique is developed to create gelatin methacryloyl (GelMA)-based substrates with various concentration gradients of RGD peptides. The capability of generating linear and nonlinear RGD concentration gradients was quantitatively verified through numerical simulation and immunohistochemical quantitative experiments. The results of the concentration gradients show a strong concurrence between the immunohistochemical quantification experiments and numerical simulations. Furthermore, endothelial migration experiments were conducted with various concentration gradients of RGD peptides. We have observed that endothelial cells on the surface of gels with a linear concentration gradient exhibit a larger cell area, a longer cell perimeter, and more stress fiber density. Furthermore, the cells demonstrate directional alignment and migration towards regions with a higher RGD concentration. High concentration gradients significantly enhance endothelial cell migration, consistent with observations on surfaces of gels with nonlinear concentration gradients. In brief, we proposed a simple and effective micro-fluidic photopolymerization technique capable of generating diverse concentration gradients of RGD and probing their effects on cell migration. The results suggest that regulating the RGD peptide concentration gradients can alter the migration of endothelial cells, showing potential for promoting wound healing.

High-resolution spatiotemporal forecasting of the European crane migration

In this paper we present three different models to forecast bird migration. They are species-specific individual-based models that operate on a high spatiotemporal resolution (kilometres, 15 min-hours), as an addition to radar-based migration forecast models that currently exist. The models vary in complexity, and use GPS-tracked location, flying direction and speed, and/or wind data to forecast migration speed and direction. Our aim is to quantitatively evaluate the forecasting performance and assess which metrics improve forecasts at different ranges. We test the models through cross-validation using GPS tracks of common cranes during spring and autumn migration. Our results show that recordings of flight speed and direction improve the accuracy of forecasts on the short range (<2 h). Adding wind data at flight altitude results in consistent improvements of the forecasts across the entire range, particularly in the predicted speed. Direction forecasts are less affected by adding wind data because cranes mostly compensate for wind drift during migration. Migration in spring is more difficult to forecast than in autumn, resulting in larger errors in flight speed and direction during spring. We further find that a combination of flight behaviours – thermal soaring, gliding, and flapping – complicates the forecasts by inducing variance in flight speed and direction. Fitting those behaviours into flight optimisation models proves to be challenging, and even results in significant biases in speed forecasts in spring. We conclude that flight speed is the most difficult parameter to forecast, whereas flight direction is the most critical for practical applications of these models. Such applications could e.g., be prevention of bird strikes in aviation or with wind turbines, and public engagement with bird migration.

Long range juxtacrine signalling through cadherin for collective cell orientation

Many life phenomena, such as development, morphogenesis, tissue remodelling, and wound healing, are often driven by orderly and directional migration of collective cells. However, when cells are randomly oriented or localized disorder exists in orderly oriented collective cells, cell migration cannot occur in an orderly manner although various motion modes such as global rotation and local swirling and/or various motion patterns such as radial pattern and chiral pattern often occur. Therefore, it is important to control cell orientation to ensure the orderly migration of collective cells. Here, we show that it is not force transmission, but juxtacrine signalling through cadherin that plays a critical role in the orientation of collective cells. Surprisingly, juxtacrine signalling for cell orientation reached cells on a plastic dish that were not directly subjected to mechanical stimulation, up to 7 mm away from the actuator. The present study suggests that even weak mechanical stimulation is transmitted in a long range without force transmission through juxtacrine signalling. The long range juxtacrine signalling might play an important role in various life phenomena. Statement of SignificanceJuxtacrine signalling is direct cell-cell contact-dependent signalling, which plays a crucial role in cell behaviors such as mechanosensing, mechanotransduction and collective cell behaviors, however, there is not enough understanding about juxtacrine signalling. The present study has demonstrated that juxtacrine signalling for collective cell orientation is transmitted over a long range through cadherin. To the best of our knowledge, this is the first report of long range juxtacrine signalling. This finding may lead to the elucidation of various life phenomena such as development, morphogenesis, tissue remodelling, and wound healing.

Income level as a differentiating factor in assessing the impact of migration on economic growth

Aim. To study the nature of the impact of migration on economic growth depending on the level of gross domestic product (GDP) per capita and the direction of migration flows.Objectives. Study of theoretical approaches to the research of the impact of labor migration on economic growth; analysis of factors that differentiate the assessment of the impact of migration flows on economic growth indicators; collection and analysis of statistical information for the development of econometric models for assessing the impact of migration on economic growth.Methods. The authors used general scientific methods of research, such as deduction, analysis, synthesis. Statistical methods of data analysis were applied, linear regression models were built.Results. The research shows that the impact of migration on economic growth in countries with different levels of GDP per capita is due to different factors. For developed economies, the positive factors of the impact of immigration on economic growth are replenishment of scarce labor resources; improvement of labor force quality due to structural changes caused by the transition of the permanent working-age population to new professional fields. For countries with a low level of GDP per capita we can identify a number of positive factors of the impact of emigration (with a negative balance of migration growth) on economic growth. In particular, the outflow of excess labor force creates conditions for reducing unemployment; remittances of migrants support effective demand in the consumer market, contribute to the development of the banking system and investment in the country of origin; the expansion of social ties leads to the development of human capital, increasing the potential for innovation.Conclusions. The value of correlation coefficients in the constructed regression models indicates that there is a weak correlation between the variable characterizing the volume and nature of migration in the country (the ratio of migration balance to population) and the variable characterizing economic growth (GDP per capita at purchasing power parity) only for the group of high-income countries. There is little statistical dependence of these variables for other groups of countries. With regard to econometric modeling of the impact of migration on economic growth, this means that it is necessary to develop separate models for each group of countries depending on the level of GDP per capita and the direction of migration flows.

Spatially defined microenvironment for engineering organoids

In the intricately defined spatial microenvironment, a single fertilized egg remarkably develops into a conserved and well-organized multicellular organism. This observation leads us to hypothesize that stem cells or other seed cell types have the potential to construct fully structured and functional tissues or organs, provided the spatial cues are appropriately configured. Current organoid technology, however, largely depends on spontaneous growth and self-organization, lacking systematic guided intervention. As a result, the structures replicated in vitro often emerge in a disordered and sparse manner during growth phases. Although existing organoids have made significant contributions in many aspects, such as advancing our understanding of development and pathogenesis, aiding personalized drug selection, as well as expediting drug development, their potential in creating large-scale implantable tissue or organ constructs, and constructing multicomponent microphysiological systems, together with functioning at metabolic levels remains underutilized. Recent discoveries have demonstrated that the spatial definition of growth factors not only induces directional growth and migration of organoids but also leads to the formation of assembloids with multiple regional identities. This opens new avenues for the innovative engineering of higher-order organoids. Concurrently, the spatial organization of other microenvironmental cues, such as physical stresses, mechanical loads, and material composition, has been minimally explored. This review delves into the burgeoning field of organoid engineering with a focus on potential spatial microenvironmental control. It offers insight into the molecular principles, expected outcomes, and potential applications, envisioning a future perspective in this domain.

Impacts of Various Insecticide Forms on Avian Health and Mortality: A Comprehensive Review

Since the time of its synthesis and application, insecticides have prevented millions of deaths in humans, animals and avian lives. They have significantly contributed to the revolution in agriculture and human health by reducing agricultural pests and vector-borne illnesses. The chance of birds being exposed to insecticides is increased by a number of factors, including farming methods, insect and crop kinds, pesticide form, food, and habitat preferences. Granular insecticides, often used in agriculture, are highly concentrated and attractive to songbirds, shorebirds, and waterfowl. Liquid sprays, particularly those used for locust control, can affect bird species beyond agricultural areas due to wide-range applications. Treated seeds can poison birds depending on various factors like toxicity and seed availability. Despite the known dangers, many pesticide-related bird deaths go unreported, highlighting the need for comprehensive studies to understand and mitigate these effects. Insecticides have a variety of sub lethal effects on birds, such as deformed embryos, smaller broods, less vigilant parenting, weakened territorial defence, anorexia and weight loss, weakened immune response, lethargic behaviour, increased susceptibility to predators, disruption of the endocrine system, interference with thermoregulation, and inability to orient in the correct direction for migration. Therefore, exposure to pesticides lowers the likelihood of survival and successful reproduction, which eventually interferes with the growth of a robust bird population.

Synergistic promotion of reaction kinetics for LiPSs at high loadings by interfacial built-in electric field and sulfur vacancies of ternary heterostructure for high-performance Li-S batteries

The practical application of lithium-sulfur batteries is significantly impeded by the chaotic migration of lithium polysulfides, sluggish redox-reaction kinetics, and pronounced shuttle effect. Herein, a ternary heterostructure (MoS2-x/MoO2/CoP) is developed with a spontaneous built-in electric field (BIEF) and enriched sulfur vacancies. This heterostructure comprises MoS2-x, which has a high adsorption capability and work function; CoP, noted for its low work function and potent catalytic properties; and MoO2, which features a work function between that of MoS2-x and CoP and serves as a bridge with excellent electronic conductivity. An appropriate combination of the catalyst and adsorbent with sulfur vacancies controls the direction of the BIEF, realizing the “adsorption-directed migration-catalytic” reaction mechanism for sulfur species. Specifically, the synergetic effect of the BIEF and sulfur vacancies enhances electron migration from CoP to MoS2-x, which improves the lithium polysulfide (LiPSs) trapping and accelerates the directional migration of LiPSs to CoP, thereby enabling the efficient catalytic conversion of sulfur species. Consequently, batteries equipped with MoS2-x/MoO2/CoP interlayers that contain sulfur vacancies demonstrate an ultrahigh initial specific capacity of 1356.2 mA h g−1 at 0.2 C, maintaining a capacity of 708.3 mAh g−1 after 1000 cycles at 2 C. Even with sulfur loading increased to 7.13 mg cm−2, these batteries display an initial specific capacity of 7.2 mAh cm−2. This work provides a feasible approach for the rational design of vacancy-containing ternary heterostructure catalysts for commercial lithium-sulfur batteries.

Microtubules and actin filaments direct nuclear movement during the polarisation of Marchantia spore cells.

The multicellular haploid stage of land plants develops from a single haploid cell produced by meiosis - the spore. Starting from a non-polar state, these spores develop polarity, divide asymmetrically and establish the first axis of symmetry. Here, we show that the nucleus migrates from the cell centroid to the basal pole during polarisation of the Marchantia polymorpha spore cell. A microtubule organising centre on the leading edge of the nucleus initiates a microtubule array between the nuclear surface and the cortex at the basal pole. Simultaneously, cortical microtubules disappear from the apical hemisphere but persist in the basal hemisphere. This is accompanied by the formation a dense network of fine actin filaments between the nucleus and the basal pole cortex. Experimental depolymerisation of either microtubules or actin filaments disrupts cellular asymmetry. These data demonstrate that the cytoskeleton reorganises during spore polarisation and controls the directed migration of the nucleus to the basal pole. The presence of the nucleus at the basal pole provides the cellular asymmetry for the asymmetric cell division that establishes the apical-basal axis of the plant.

Spatial and Temporal Change Analysis of Urban Built-Up Area via Nighttime Lighting Data—A Case Study with Yunnan and Guizhou Provinces

As urbanization accelerates, characteristics of urban spatial expansion play a significant role in the future utilization of land resources, the protection of the ecological environment, and the coordinated development of population and land. In this study, Yunnan and Guizhou provinces were selected as the study area, and the 2013–2021 National Polar-Orbiting Partnership’s Visible Infrared Imaging Radiometer Suite (NPP-VIIRS) nighttime light (NTL) data were utilized for spatial and temporal change analysis of urban built-up areas. Firstly, the built-up areas in Yunnan and Guizhou provinces were extracted through ENUI (Enhanced Nighttime Lighting Urban Index) indices, and then the urban expansion speed and urban center of gravity migration were constructed and used to explore and analyze the spatial and temporal change and expansion characteristics of built-up areas in Yunnan and Guizhou provinces. The results showed the following. (1) Due to the complementarity between data types, such as NTL, EVI, NDBI, and NDWI, ENUI has better performance in expressing urban characteristics. (2) Influenced by national and local policies, such as “One Belt, One Road”, transportation infrastructure construction, geographic location, the historical background, and other factors, the urban expansion rate of Yunnan and Guizhou provinces in general showed a continuous advancement from 2013 to 2021, and there were three years in which the expansion rate was positive. (3) The center of gravity migration distance of most cities in Guizhou Province shows a trend of increasing and then decreasing, while the center of gravity migration distance in Yunnan Province shows a trend of continuous decrease in general. From the perspective of migration direction, Guizhou Province has the largest number of migrations to the northeast, while Yunnan Province has the largest number of migrations to the southeast. (4) Influenced by policy, economy, population, geography, and other factors, urban compactness in Yunnan and Guizhou provinces continued to grow from 2013 to 2021. The results of this study can help us better understand urbanization in western China, reveal the urban expansion patterns and spatial characteristics of Yunnan and Guizhou provinces, and provide valuable references for development planning and policymaking in Yunnan and Guizhou provinces.

Mangroves Invaded by Spartina alterniflora Loisel: A Remote Sensing-Based Comparison for Two Protected Areas in China

Mangroves are one of the world’s most productive and ecologically important ecosystems, and they are threatened by the widespread invasion of Spartina alterniflora Loisel in China. As few studies have examined the spatial pattern differences of S. alterniflora invasion and the nearby mangroves in different latitudes, we chose the Zhangjiang Estuary and the Dandou Sea, two representative mangrove–salt marsh ecotones in the north and south of the Tropic of Cancer, as the study areas for comparison. The object-based image analysis and visual interpretation methods were combined to construct fine-scale mangrove and S. alterniflora maps using high-resolution satellite imagery from 2005 to 2019. We applied spatial analysis, centroid migration, and landscape indexes to analyze the spatio–temporal distribution changes of mangroves and S. alterniflora in these two ecotones over time. We used the landscape expansion index to investigate the S. alterniflora invasion process and expansion patterns. The annual change rates of mangrove and S. alterniflora areas in the Zhangjiang Estuary showed a continuous growth trend. However, the mangrove areas in the Dandou Sea showed a fluctuating trend of increasing, decreasing, and then increasing again, while S. alterniflora areas kept rising from 2005 to 2019. Spartina alterniflora showed larger annual change rates compared with mangroves, indicating rapid S. alterniflora invasion in the intertidal zones. The opposite centroid migration directions of mangroves and S. alterniflora and the decreasing distances between the mangrove and S. alterniflora centroids indirectly revealed the fierce competition between mangroves and S. alterniflora for habitat resources. Both regions saw a decrease in mangrove patch integrality and connectivity. The integrality of mangrove patches in the Zhangjiang Estuary was always higher than those in the Dandou Sea. We observed the growth stage (2011–2014) and outbreak stage (2014–2019) of S. alterniflora expansion in the Zhangjiang Estuary and the outbreak stage (2005–2009) and plateau stage (2009–2019) of S. alterniflora expansion in the Dandou Sea. The expansion pattern of S. alterniflora varies in time and place. Since the expansion of S. alterniflora in the outbreak stage is rapid, with a large annual change rate, early warning of S. alterniflora invasion is quite important for the efficient and economical removal of the invasive plant. Continuous and accurate monitoring of S. alterniflora is highly necessary and beneficial for the scientific management and sustainable development of coastal wetlands.

Weak magnetic field for enhanced degradation of sulfamethoxazole by the CoFe2O4/PAA system: Insights into performance and mechanism

In this work, a novel approach coupling a heterogeneous weak magnetic field (WMF) with the CoFe2O4/peroxyacetic acid (PAA) system was employed to enhance the degradation of sulfamethoxazole (SMX). Under the optimized conditions of 50 mT WMF, 0.1 g/L CoFe2O4, 0.2 mM PAA, and initial pH 6.0, a complete degradation of 10 μM SMX was achieved in 25 min, exhibiting a high synergistic coefficient of 1.61. This result indicates a significant synergistic effect among WMF, CoFe2O4, and PAA in effectively degrading SMX. The introduction of WMF did not alter the pH application range of the CoFe2O4/PAA system. Furthermore, the degradation efficiency of SMX by the CoFe2O4/PAA/WMF system was significantly reduced in the presence of humic acid (HA) and bicarbonate ions (HCO3−), while chloride ions (Cl−) exhibited a minor inhibitory effect. Quenching experiments and electron paramagnetic resonance (EPR) analysis reveal that WMF did not alter the types of reactive oxygen species (ROS) generated in the CoFe2O4/PAA system. The degradation of SMX in the CoFe2O4/PAA/WMF system involved both radical (CH3C(O)O∙ and CH3C(O)OO∙) and non-radical (1O2) oxidation pathways, driven by the redox cycling between ≡Co2+/≡Co3+ and PAA, as well as the rapid adsorption and transformation of oxygen (O2) at oxygen vacancies (OV), respectively. The presence of WMF enhanced the utilization of PAA by CoFe2O4 by improving the convection and mass transport in the solution, facilitating the formation of superoxide anion (O2∙−) and supplemented lattice oxygen (O2−) through the directional migration of paramagnetic O2 towards the CoFe2O4 surface, thus significantly promoting ROS formation. Additionally, the degradation pathways of SMX in the CoFe2O4/PAA/WMF system were proposed based on density functional theory (DFT) calculations and the detected transformation products (TPs). The toxicity of SMX was effectively reduced, as verified by predictions from the Ecological Structure-Activity Relationship Model (ECOSAR) procedure. The excellent catalytic performance, reusability, and effective degradation of various organic pollutants demonstrated by the CoFe2O4/PAA/WMF system suggest its potential as a promising strategy for water treatment.

Recent and active faulting along the exposed front of the Northern Apennines (Italy): New insights from field and geochronological constraints

Establishing genetic links between active shallow faulting and deep seismogenic sources is challenging, especially in areas where seismogenic faults lack clear and readily interpretable geological evidence at the surface. The architecture of the Pedeapenninic margin of the Northern Apennines (Italy) reflects a regional-scale and complex NE-verging blind thrust system, which is dissected by transpressive/transtensive faults resulting from active NE-SW orogenic compression. The local geological framework is defined by allochthonous ocean-derived units resting atop Pliocene-to-present successions exposed along the Northern Apennines margin and to the NE of it, while the innermost chain sector mostly contains Adria-related units. We present results from field structural-geological investigations to identify and characterize potential active faults along the margin. There, the Pliocene-to-present units are faulted and folded, indicating that tectonic activity is still on-going, thus contributing to the local seismic hazard. Top-to-the NE and SW normal faults are common in the area and deform the Pliocene-to-present succession together with NE-SW strike-slip and transpressional/transtensional faults. Based on field evidence, we define four potentially active thrust segments affecting Middle Pleistocene to Holocene deposits exposed along the margin. Calcite U-Th dating on samples from faults extend the most recent datable tectonic activity back to the Middle Pleistocene. Paleostress analysis from inversion of fault-slip data from the most recent identified striated fault planes constrains a NE-SW shortening direction parallel to the Apennines regional migration direction. A distinct but coaxial extensional stress regime, recorded by structures measured within Plio-Pleistocene formations, was also identified. Our results offer a sound starting point for future investigations aimed at improving our understanding of active and seismogenic faulting in the area, so as to create robust Probabilistic Seismic and Fault Displacement Hazard Assessment (PSHA and PFDHA) models that can implement refined seismic hazard maps benefitting from structural-geological deterministic inputs in addition to the classic seismological constraints.

Lateral migration of a deformable fluid particle in a square channel flow of viscoelastic fluid

Cross-stream migration of a deformable fluid particle is investigated computationally in a pressure-driven channel flow of a viscoelastic fluid via interface-resolved simulations. Flow equations are solved fully coupled with the Giesekus model equations using an Eulerian–Lagrangian method and extensive simulations are performed for a wide range of flow parameters to reveal the effects of particle deformability, fluid elasticity, shear thinning and fluid inertia on the particle migration dynamics. Migration rate of a deformable particle is found to be much higher than that of a solid particle under similar flow conditions mainly due to the free-slip condition on its surface. It is observed that the direction of particle migration can be altered by varying shear thinning of the ambient fluid. With a strong shear thinning, the particle migrates towards the wall while it migrates towards the channel centre in a purely elastic fluid without shear thinning. An onset of elastic flow instability is observed beyond a critical Weissenberg number, which in turn causes a path instability even for a nearly spherical particle. An inertial path instability is also observed once particle deformation exceeds a critical value. Shear thinning is found to be suppressing the path instability in a viscoelastic fluid with a high polymer concentration whereas it reverses its role and promotes path instability in a dilute polymer solution. It is found that migration of a deformable particle towards the wall induces a secondary flow with a velocity that is approximately an order of magnitude higher than the one induced by a solid particle under similar flow conditions.

Why We Need Diverse Methods for Assessing Cultural Identity: Introduction to the Special Issue

In this introduction to the special issue on diverse methods for cultural identity, we begin by addressing the evolving complexities of defining oneself amidst modern globalization and immigration. We then preview the current collection of papers, which collectively showcase the complexity of cultural identity by exploring how people, especially adolescents and young adults, navigate a plethora of cultural influences—whether through direct migration or the pervasive impact of global cultures—as they psychologically manage diverse and sometimes conflicting allegiances and worldviews. The studies featured in this issue employ a range of methodologies, from qualitative analyses to mixed-methods approaches, to expand our knowledge of the constitution of contemporary cultural identities beyond common quantitative metrics of self-categorization and group belongingness. For instance, research on Jamaican American adolescents highlights how cultural identity is formed through reciprocal socialization processes and systemic factors such as racism. Similarly, studies involving Hmong American youth and Guatemalan adolescents reveal tensions and creative harmonizations in identity management, challenging notions of a homogenized global culture. We conclude by underscoring the need for future research to take a nuanced, intersectional approach to the study of cultural identity, to explore creative measurement tools that are sensitive to local meaning-making among diverse groups around the world, and to attend to the impact of power dynamics in shaping one’s sense of self in relation to their cultural group(s).

APC orchestrates microtubule dynamics by acting as a positive regulator of KIF2A and a negative regulator of CLASPs

Tumor suppressor protein Adenomatous polyposis coli protein (APC) is an EB-binding and microtubule (MT) plus end-tracking protein; however, how exactly APC regulates MT dynamics remains elusive. Here, we show that in LLC-PK1 cells, APC and KIF2A, an MT depolymerase, form a complex clustering at the cell edge and destabilize MTs at the MT plus ends. Further biochemical characterization and mutational analysis reveal key residues for the APC-KIF2A interaction. In addition, APC counteracts the major MT-stabilizer CLASPs at MT plus ends and promotes directional cell migration via modulating cell adhesion force. Reconstitution experiments demonstrate that APC potentiates KIF2A-induced MT catastrophes and antagonizes the stabilizing effect of CLASP2 in vitro. In summary, APC functions as a positive regulator of MT-destabilizer and a negative regulator of MT-stabilizer to orchestrate MT dynamics.

Aligned fibrous scaffolds promote directional migration of breast cancer cells via caveolin-1/YAP-mediated mechanosensing

Tumorigenesis and metastasis are highly dependent on the interactions between the tumor and the surrounding microenvironment. In 3D matrix, the fibrous structure of the extracellular matrix (ECM) undergoes dynamic remodeling during tumor progression. In particular, during the late stage of tumor development, the fibers become more aggregated and oriented. However, it remains unclear how cancer cells respond to the organizational change of ECM fibers and exhibit distinct morphology and behavior. Here, we used electrospinning technology to fabricate biomimetic ECM with distinct fiber arrangements, which mimic the structural characteristics of normal or tumor tissues and found that aligned and oriented nanofibers induce cytoskeletal rearrangement to promote directed migration of cancer cells. Mechanistically, caveolin-1(Cav-1)-expressing cancer cells grown on aligned fibers exhibit increased integrin β1 internalization and actin polymerization, which promoted stress fiber formation, focal adhesion dynamics and YAP activity, thereby accelerating the directional cell migration. In general, the linear fibrous structure of the ECM provides convenient tracks on which tumor cells can invade and migrate. Moreover, histological data from both mice and patients with tumors indicates that tumor tissue exhibits a greater abundance of isotropic ECM fibers compared to normal tissue. And Cav-1 downregulation can suppress cancer cells muscle invasion through the inhibition of YAP-dependent mechanotransduction. Taken together, our findings revealed the Cav-1 is indispensable for the cellular response to topological change of ECM, and that the Cav-1/YAP axis is an attractive target for inhibiting cancer cell directional migration which induced by linearization of ECM fibers.

Assessment of suitable region of Asparagus cochinchinensis (Lour.) Merr. under different climatic conditions in China by the MaxEnt model and HPLC analysis.

Asparagus cochinchinensis is a member of the Asparagaceae family whose medicinal part is the dried root tuber. The distribution of A. cochinchinensis and its secondary metabolites are closely associated with environmental factors, such as climate and soil properties. By establishing and optimizing a maximum entropy model, we analyzed and predicted the distribution pattern and migration direction of suitable habitats for A. cochinchinensis and determined the main environmental factors affecting the accumulation of secondary metabolites. Under current climatic conditions, the area of suitable habitats for A. cochinchinensis (208.38 × 104 km2) accounts for 21.71% of the land area of China, and the areas of lowly, moderately, and highly suitable areas were 64.15 × 104 km2, 113.66 × 104 km2, and 30.57 × 104 km2, respectively. Under future climate scenarios, the total area of suitable habitats hardly changes. The area of highly suitable habitats significantly decreases under the SSP1-RCP2.6 scenario (to 83.22% of the current value) and the SSP3-RCP7 scenario (to 48.94% of the current value), but eventually increases to 112.86% of the current value under the SSP5-RCP8.5 scenario, which indicates that A. cochinchinensis might adapt better to a high-carbon-emissions scenario. Under different climate scenarios, low-impact areas mainly occur in southern China and will correspond 92.07% of the current suitable area. Highly suitable habitats primarily occur in the southeastern Sichuan Basin, northern Guangxi, eastern Guizhou, and western Hunan. HPLC analysis showed that the content of protodioscin (0.373%) and protogracillin (0.044%) in S2 was the highest. The total saponins contents of S1 and S2 were the highest, which were 35.6586 and 33.1262 mg/g, respectively. The total polysaccharide content of S9 was the highest (16.9467%). The total contents of saponins and polysaccharides in A. cochinchinensis were significantly, but oppositely, correlated with temperature, precipitation, and other factors. This study has identified environmental factors affecting the growth and quality of A. cochinchinensis, which has guiding significance for resource conservation and site selection for large-scale cultivation.