Individual Stem Research Articles

The Effects of Different Grazing Periods on the Functional Traits of Leymus chinensis (Trin.) Tzvelev in a Typical Inner Mongolia Steppe

Plant functional traits are effective indicators and predictors of environmental change, revealing plants’ ecological countermeasures and adaptability through phenotypic plasticity. We conducted a 6-year grazing experiment on typical temperate grassland to assess the impact of different grazing periods on the plasticity and variability of the functional traits of Leymus chinensis and the relationship between traits and individual plant biomass. Our study included four treatments: CK (enclosure), T1 (grazing in May and July), T2 (grazing in June and August), and T3 (grazing in July and September). The results for 13 functional traits indicated that the T3 treatment showed the smallest reduction in individual plant biomass, plant height, leaf area, stem length, and leaf length, making it the most effective type of grassland management and optimal for the maintenance and restoration of L. chinensis traits. Under T1, T2, and T3, the plasticity of stem weight, total leaf weight, total leaf area, and stem length was higher and crucial for regulating individual plant biomass. The results underscore that the changes and plasticity of dominant species under grazing treatments are key to understanding the relationship between ecosystem function and grassland management. This study provides a theoretical basis and data support for the adaptive utilization and restoration management of typical grassland resources.

Tracking foresters and mapping tree stem locations with decimeter-level accuracy under forest canopies using UWB

This paper presents a new method for tracking foresters and mapping tree stem locations under forest canopies utilizing ultra-wideband (UWB) data, in which four estimators (collector, estimator, locator, and extractor) operate closely together. The collector records all the distance measurements (beacon to beacon and terminal to the beacons); the estimator determines the local coordinates of the beacons automatically and precisely based on the distance measured between them; the locator then determines the trajectory of the terminal/forester using the extended Kalman filter (EKF) with the assistance of non-line-of-sight (NLoS) distance measurement classification and processing; the extractor continuously determines the optimal locations of the tree stems. To fully evaluate the performance of the developed method, experiments were conducted under four forest canopies with different tree densities and species. The experimental results show that the root-mean-squared-errors (RMSEs) of the proposed method for the terminal/forester positioning and individual tree stem location are less than 0.3 m with a stable update rate of 20 Hz, and a coverage of larger than approximately 3,000 m2 with only four UWB beacons under forest canopies. Therefore, it is sufficient for forest surveys and management with reduced human efforts.

Large-scale inventory in natural forests with mobile LiDAR point clouds

Large-scale forest inventory at the individual tree level is critical for natural resource management decision making. Terrestrial Laser Scanning (TLS) has been used for individual tree level inventory at plot scale However, due to the inflexibility of TLS and the complex scene of natural forests, it is still challenging to localize and measure every tree at large scale. In this paper, we present a framework to conduct large-scale natural forest inventory at the individual tree level by taking advantage of deep learning models and Mobile Laser Scanning (MLS) systems. First, a deep learning model, ForestSPG, was developed to perform large-scale semantic segmentation on MLS LiDAR data in natural forests. Then, the forest segmentation results were used for individual stem mapping. Finally, Diameter at Breast Height (DBH) was measured for each individual stem. Two natural forests mapped with backpack and Unmanned Aerial Vehicle (UAV) LiDAR systems were tested. The results showed that the proposed ForestSPG is able to segment large-scale forest LiDAR data into multiple ecologically meaningful classes. The proposed framework was able to localize and measure all 5838 stems at individual tree level in a 20 ha natural forest in less than 20 min using UAV LiDAR. DBH measurement results on trees’ DBH larger than 38.1 cm (15 in) showed that backpack LiDAR was able to achieve 1.82 cm of Root Mean Square Error (RMSE) and UAV LiDAR was able to achieve 3.13 cm of RMSE. The proposed framework can not only segment complex forest components with LiDAR data from different platforms but also demonstrate good performance on stem mapping and DBH measurement. Our research provides and automatic and scalable solution for large-scale natural forest inventory at individual tree level, which can be the basis for large-scale estimation of wood volume and biomass.

Biofabrication of engineered tissues by 3D bioprinting of tissue specific high cell-density bioinks.

Bioprinting of high cell-density bioinks is a promising technique for cellular condensation-based tissue engineering and regeneration medicine. However, it remains difficult to create precisely controlled complex structures and organization of tissues with high cell-density bioink-based bioprinting for tissue specific condensation. In this study, we present newly biofabricated tissues from directly assembled, tissue specific, high cell-density bioinks which have been three-dimensionally printed into a photocrosslinkable and biodegradable hydrogel microparticle supporting bath. Three types of tissue specific high cell-density bioinks have been prepared with individual stem cells or stem cell aggregates by incorporation of growth factor-loaded gelatin microparticles. The bioprinted tissue specific high cell-density bioinks in the photocrosslinked microgel supporting bath condense together and differentiate down tissue-specific lineages to form multi-phase tissues (e.g., osteochondral tissues). By changing the growth factors and cell types, these tissue specific high cell-density bioinks enable engineering of various functional tissues with controlled architecture and organization of cells.

Wrapping stem cells with wireless electrical nanopatches for traumatic brain injury therapy

Electrical stimulation holds promise for enhancing neuronal differentiation of neural stem cells to treat traumatic brain injury. However, once the stem cells leave the stimulating material and migrate post transplantation, electrical stimulation on them is diminished. Here, we wrap the stem cells with wireless electrical nanopatches, the conductive graphene nanosheets. Under electromagnetic induction, electrical stimulation can thus be applied in-situ to individual nanopatch-wrapped stem cells on demand, stimulating their neuronal differentiation through a MAPK/ERK signaling pathway. Consequently, 41% of the nanopatch-wrapped stem cells differentiate into functional neurons in 5 days, as opposed to only 16.3% of the unwrapped ones. The brain injury male mice implanted with the nanopatch-wrapped stem cells and exposed to a rotating magnetic field 30 min/day exhibit significant recovery of brain tissues, behaviors, and cognitions, within 28 days. This study opens up an avenue to individualized electrical stimulation of transplanted stem cells for treating neurodegenerative diseases.

Regulation of the hematopoietic stem cell pool by C-Kit-associated trogocytosis.

Hematopoietic stem cells (HSCs) are routinely mobilized from the bone marrow (BM) to the blood circulation for clinical transplantation. However, the precise mechanisms by which individual stem cells exit the marrow are not understood. This study identified cell-extrinsic and molecular determinants of a mobilizable pool of blood-forming stem cells. We found that a subset of HSCs displays macrophage-associated markers on their cell surface. Although fully functional, these HSCs are selectively niche-retained as opposed to stem cells lacking macrophage markers, which exit the BM upon forced mobilization. Macrophage markers on HSCs could be acquired through direct transfer by trogocytosis, regulated by receptor tyrosine-protein kinase C-Kit (CD117), from BM-resident macrophages in mouse and human settings. Our study provides proof of concept that adult stem cells utilize trogocytosis to rapidly establish and activate function-modulating molecular mechanisms.

Exploring Wave–Vegetation Interaction at Stem Scale: Analysis of the Coupled Flow–Structure Interactions Using the SPH-Based DualSPHysics Code and the FEA Module of Chrono

Aquatic vegetation in the littoral zone plays a crucial role in attenuating wave energy and protecting coastal communities from hazardous events. This study contributes to the development of numerical models aimed at designing nature-based coastal defense systems. Specifically, a novel numerical application for simulating wave–vegetation interactions at the stem scale is presented. The numerical model employed, DualSPHysics, couples the meshfree Smoothed Particle Hydrodynamics (SPH) fluid solver with a structural solver to accurately capture the two-way interactions between waves and flexible vegetation. The proposed numerical model is validated against experimental data involving a submerged rubber cylinder representing an individual vegetation stem, subjected to regular waves. The results demonstrate excellent agreement in hydrodynamics, force transfer, and the swaying motion of the flexible cylinder. Importantly, the approach explicitly captures energy transfer between the fluid environment and the individual stem. The numerical results indicate persistent turbulent flow along the vegetation stem, even when its swaying speed matches that of the surrounding environment. This reveals the presence of vortex shedding and energy dissipation, which challenges the concept of passive swaying in flexible aquatic vegetation.

Acute Periprosthetic Hip Fractures With Short, Uncemented Femoral Stems

BackgroundUncemented femoral stems in hip arthroplasty have shown excellent long-term results, and several systematic studies indicate satisfactory performance of short stems. However, biomechanical and finite element analysis studies have suggested that shorter stems allow greater micromotion, producing greater strain at the implant-bone interface, which potentially increases the risk for periprosthetic fracture (PPF). We sought to assess this risk within our unit. MethodsOur institution’s arthroplasty database was searched for all primary total hip arthroplasties using short femoral stems performed between July 14, 2009 and August 29, 2022. The overall PPF rate and the PPF rate for individual femoral stems were established. Preoperative X-rays for each case were analyzed to characterize individual proximal femoral geometry. A data analysis was performed to identify risk factors for PPF. ResultsFor the time period assessed, 3,192 short femoral stems were implanted. This included 1,561 of stem A and 1,631 of stem B. Women constituted 55.37% of the cohort. The average patient age was 66 years (range, 22 to 95). The PPF rate was 0.6%, with 19 PPFs identified at a follow-up of 3 months. There was a significantly higher fracture rate in stem A (0.96%) compared to stem B (0.25%) (P ≤ .01). Proximal femoral geometry, age, and sex were not determined to be risk factors for PPF in our cohort. Individual surgeons and surgical approaches appeared to confer no increased risk. There was no significant difference in average stem length, but multivariate analysis identified stem type and stem length as an independent risk factor for PPF. ConclusionsOur study identified individual stem and stem length as independent risk factors for PPF within our cohort. PPF is a multifactorial issue, and consensus on emerging risk factors such as implant design will hopefully inform decisions that can provide further risk reduction for individual patients.

Optimizing Sowing Density for Parsley, Cilantro, and Sage in Controlled Environment Production: Balancing Productivity and Plant Quality

Sowing density is a key management practice influencing productivity and quality of leafy greens and culinary herbs grown in controlled environments. However, research-based information on optimal density is limited for many culinary herbs. This greenhouse study aimed to quantify sowing density impacts on biomass output, individual plant growth, and morphological traits in hydroponically produced ‘Giant of Italy’ parsley (Petroselinum crispum), ‘Santo’ cilantro (Coriandrum sativum), and sage (Salvia officinalis). Seedlings were grown in phenolic foam cubes with 1, 5, 10, 15, or 20 seeds per cell, transplanted into an ebb-and-flow hydroponic system in a glass-glazed greenhouse with 23 °C target average daily temperature, 16-hour photoperiod, a target daily light integral of 13 mol·m−2·d−1, and harvested at 16 to 28 d after transplanting depending on species. ‘Giant of Italy’ parsley and ‘Santo’ cilantro fresh weight per cell increased quadratically by 274% (57.3 g) and 305% (19 g), respectively, as sowing density increased from 1 to 15 seeds per cell, then plateaued as density further increased. Sage fresh weight plateaued at 10 seeds per cell with an increase of 225% (29.2 g) compared with 1 seed per cell. Cilantro and sage dry weight per cell plateaued at 14 and 8 seeds per cell, respectively, and parsley dry weight quadratically increased as sowing density rose up to 20 seeds per cell. Although fresh and dry weight increased, individual plant height, stem diameter, and individual plant dry weight exhibited linear or quadratic declines as sowing density increased, indicating higher sowing densities restricted individual plant growth. In summary, as sowing density increased, fresh and dry weight per cell generally increased but individual plant quality decreased. For the greatest fresh and dry weight, 20, 18, and 10 seeds per cell should be sown for parsley, cilantro, and sage, respectively. However, to balance fresh weight and crop quality, our results suggest sowing density (seeds per cell) targets of 16 seeds for parsley, 18 seeds for cilantro, and 10 seeds for sage.

ARTseq-FISH reveals position-dependent differences in gene expression of micropatterned mESCs

Differences in gene-expression profiles between individual cells can give rise to distinct cell fate decisions. Yet how localisation on a micropattern impacts initial changes in mRNA, protein, and phosphoprotein abundance remains unclear. To identify the effect of cellular position on gene expression, we developed a scalable antibody and mRNA targeting sequential fluorescence in situ hybridisation (ARTseq-FISH) method capable of simultaneously profiling mRNAs, proteins, and phosphoproteins in single cells. We studied 67 (phospho-)protein and mRNA targets in individual mouse embryonic stem cells (mESCs) cultured on circular micropatterns. ARTseq-FISH reveals relative changes in both abundance and localisation of mRNAs and (phospho-)proteins during the first 48 hours of exit from pluripotency. We confirm these changes by conventional immunofluorescence and time-lapse microscopy. Chemical labelling, immunofluorescence, and single-cell time-lapse microscopy further show that cells closer to the edge of the micropattern exhibit increased proliferation compared to cells at the centre. Together these data suggest that while gene expression is still highly heterogeneous position-dependent differences in mRNA and protein levels emerge as early as 12 hours after LIF withdrawal.

Cerebral organoids display dynamic clonal growth and tunable tissue replenishment.

During brain development, neural progenitors expand through symmetric divisions before giving rise to differentiating cell types via asymmetric divisions. Transition between those modes varies among individual neural stem cells, resulting in clones of different sizes. Imaging-based lineage tracing allows for lineage analysis at high cellular resolution but systematic approaches to analyse clonal behaviour of entire tissues are currently lacking. Here we implement whole-tissue lineage tracing by genomic DNA barcoding in 3D human cerebral organoids, to show that individual stem cell clones produce progeny on a vastly variable scale. By using stochastic modelling we find that variable lineage sizes arise because a subpopulation of lineages retains symmetrically dividing cells. We show that lineage sizes can adjust to tissue demands after growth perturbation via chemical ablation or genetic restriction of a subset of cells in chimeric organoids. Our data suggest that adaptive plasticity of stem cell populations ensures robustness of development in human brain organoids.

Integrating personal laser scanning with uncrewed aerial vehicle-based photogrammetry or laser scanning for accurate stem volume estimation in temperate coniferous forests

ABSTRACT An extensive number of trees are surveyed for logging purposes, necessitating efficient and precise logging survey methods. Integrating over- and under-canopy remote sensing, such as personal laser scanning (PLS) with uncrewed aerial vehicle-based laser scanning (ULS) or digital aerial photogrammetry (DAP), is a promising method. In this study, we aimed to estimate stem volume in a 16.89-ha coniferous forest using these techniques at the individual, plot, and stand levels. The root mean square error (RMSE) and relative RMSE (rRMSE) when compared to conventional field surveys of PLS-based volume estimations were 0.14 m3 (21.6%) before and 0.08 m3 (12.3%) after bias correction. When integrating PLS with ULS and DAP, the RMSE and rRMSE values were 0.16 m3 (26.7%) and 0.16 m3 (27.0%), respectively. The F-score for the individual tree detection analysis by ULS and DAP were 0.94 and 0.96, respectively. The RMSE of the estimated volume in the plots was 0.08 m3 for both ULS and DAP. The estimated volumes of timber produced in the stand using the utilization rate overestimated the actual volume by 30.6%, 13.0%, and 17.0%, for PLS, ULS, and DAP, respectively. While the individual stem volume estimation accuracy of ULS and DAP was lower than that of the field survey, at the plot level the results were comparable, with ULS and DAP showing results significantly closer to the actual results than those of PLS at the stand level. This study highlights the potential for integrating PLS with uncrewed aerial vehicle methods for estimating stem and log volumes at the plot and stand levels.

A creative solution to simple experiments in the subject of technology within the STEM concept

Teaching with the STEM concept represents education that uses the connection of science, technology, mathematics, engineering, and the natural sciences. The “STEMkey” project, whose solutions are members of the KTIT PF UKF in Nitra, contributes to modernising STEM teacher education in Europe and strengthens teachers' professional development. It supports the development of better quality and more attractive STEM courses for students motivated to teach about individual STEM subjects and how they can use them to solve problems arising from simple experiments. The article describes an activity prepared for the summer school in Lisbon by researchers from Nitra. In a prepared task, it was necessary to solve the pumping of polluted water, controlled by the BBC microcontroller, into a sand filter. Students and future teachers from several European universities participated in the summer school. The prepared activities aimed at developing student teachers' abilities to apply the concept of STEM education in the educational process.

Towards effective collaborations: Reflections and recommendations for adult education and STEM

AbstractThis article presents a general and overarching view on partnerships between adult education and STEM disciplines. Drawing from their individual STEM backgrounds, personal perspectives and experiences with such partnerships, and the science of team science, the authors consider the benefits of adult eeducation for STEM, the benefits of STEM for adult education, and some best practices and pitfalls of collaborations. In this way, they address some of the “why?” and “how?” that adult educators may wish to consider as they seek new collaborations, or navigate existing partnerships.

Quantitative association between gene expression and blood cell production of individual hematopoietic stem cells in mice.

Individual hematopoietic stem cells (HSCs) produce different amounts of blood cells upon transplantation. Taking advantage of the intercellular variation, we developed an experimental and bioinformatic approach to evaluating the quantitative association between gene expression and blood cell production across individual HSCs. We found that most genes associated with blood production exhibit the association only at some levels of blood production. By mapping gene expression with blood production, we identified four distinct patterns of their quantitative association. Some genes consistently correlate with blood production over a range of levels or across all levels, and these genes are found to regulate lymphoid but not myeloid production. Other genes exhibit one or more clear peaks of association. Genes with overlapping peaks are found to be coexpressed in other tissues and share similar molecular functions and regulatory motifs. By dissecting intercellular variations, our findings revealed four quantitative association patterns that reflect distinct dose-response molecular mechanisms modulating the blood cell production of HSCs.

Retaining the largest aspen stems during motor-manual release allows to control aspen suckering in young mixedwood stands

Mixedwood stands containing aspens (Populus tremuloides or P. grandidentata) often convert to hardwood-dominated stands after harvesting due to the rapid regeneration of aspen from root suckers, even when sites are promptly replanted with conifer seedlings. Without the use of herbicides, this problem is usually dealt with several passes of motor-manual (“manual”) release of overtopped seedlings. The aim of this study was to test a variation of thinning from below treatment (thinning; only 20% of the largest aspens are retained), and to compare it against two traditional release treatments: broadcast brushing (brushing; 100% removal of aspen) or crop tree release (CTR; removal of competing vegetation 60 to 90 cm around planted spruce) and an un-treated control. The thinning treatment left the 20% larger aspen stems in place, in order that they continue exerting apical dominance on smaller suckers and limit re-suckering of the treated plots. Aspen suckering and growth of planted black spruce seedlings (Picea mariana (Mill.) B.S.P) were measured two- and four-growing seasons following treatments. Results four years after release application showed that the thinning and CTR treatments reduced aspen density by 61% compared to the brushing treatment. In addition, aspen individual stem volume in the thinning treatment was almost 10 times larger than the brushing and twice that of the CTR treatments. Spruce height and ground collar diameter (GCD; 5 cm aboveground line) were both measured, and while height increment was similar in all treatments, diameter increment was greater in the thinning treatment (+42%) compared to the control, brushing and CTR treatments (+17%). Thinning yielded better short-term results than the brushing release in terms of aspen re-suckering and aspen sawlog potential, highlighting the need for adapted silvicultural treatments based on the species’ ecology.

ПРОФЕСІЙНА ПІДГОТОВКА МАЙБУТНІХ БАКАЛАВРІВ З КОМП’ЮТЕРНОЇ ІНЖЕНЕРІЇ В УМОВАХ МУЛЬТИДИСЦИПЛІНАРНОСТІ STEM-ОСВІТИ

The article is devoted to one of the urgent problems of training future bachelors in computer engineering in the conditions of multidisciplinarity of STEM education. In particular, the essence of such concepts as STEM education, the analysis of its functioning in the international educational space is revealed. The purpose of the article is to analyze the essence, content, approaches and features of modern innovative STEM education in the preparation of bachelors in computer engineering in Ukraine, as a new and priority direction, taking into account world and domestic historical experience. The main approaches to the implementation of STEM education programs are highlighted: the expansion of educational experience in individual STEM subjects, using problem-oriented educational activities, during which analytical concepts are applied to real world problems, with the aim of better understanding of complex concepts by students; integrating knowledge of STEM subjects to create a deeper understanding of their content, which will ultimately lead to the expansion of opportunities for students to choose a career path in the future; the use of a multidisciplinary approach, which relies on integrativeness in teaching the necessary disciplines, as it is done in real production conditions. Thus, the student will be able to apply his knowledge to solve poorly structured technological problems, develop technical capabilities and more intensively master the skills of highly organized thinking; the introduction of innovations in the teaching methodology of each of the individual STEM subjects. The importance of teachers’ readiness to introduce STEM education is proven, which is due to the fact that in the education system the emphasis is on theoretical subject knowledge, and the connection between learning and solving pract ical tasks remains weak. Therefore, it is important to popularize STEM technologies, organize practice-oriented courses to improve the qualifications of teachers. It is emphasized that the implementation of STEM education programs in the training of future bachelors in computer engineering allows to satisfy the need of the state and society for highly qualified engineering specialists, to increase the interest of modern youth in engineering professions, to significantly improve the quality of education, and to prepare students for real life. Our analysis allows us to consider STEM education as a complex valuable, socially important, systemic-institutional, personal-developmental, process-active and technological phenomenon.

Cellular Barcoding of JAK2-V617F Hematopoietic Stem Cells Reveals No Substantial Preferences in the Contribution of Individual Stem Cell Clones to Erythroid Versus Megakaryocytic Lineages

JAK2-V617F is the most frequent driver gene mutation in patients with myeloproliferative neoplasms (MPN) but the phenotypic manifestation is heterogeneous with some patients presenting as polycythemia vera (PV), whereas others with essential thrombocythemia (ET) or myelofibrosis (MF). JAK2-V617F is acquired in a hematopoietic stem cell (HSC) and leads to clonal expansion of HSCs and progenitor cells that gain dominance over unmutated hematopoiesis. We tested the hypothesis that the preferential expansion of megakaryopoiesis in ET versus erythropoiesis in PV could be due to the acquisition of JAK2-V617F in different subsets of HSCs with inherent bias towards megakaryopoiesis or erythropoiesis. In addition, we addressed the question of whether sensitivity or resistance to interferon-α (IFNα), currently the only treatment that can induce a deep molecular remission in some MPN patients, could be also due to heterogeneity in HSC subpopulations. We used a mouse model of JAK2-V617F driven MPN in combination with molecular barcoding that allowed us to monitor expansion and lineage contribution of individual HSC subclones. First, we genetically barcoded HSCs from our tamoxifen-inducible SclCre;JAK2-V617F ( VF) mice with a lentiviral vector, and transplanted 2'000 HSCs into lethally irradiated recipient mice. After 12 weeks we sequenced the barcodes in bone marrow (BM) progenitors by next generation sequencing (NGS). We observed a strong selection of 1-2 HSCs clones per recipient mouse, which alone contributed to > 80% of all the myeloid cells. Since cytokine storm after irradiation and aplasia during the reconstitution with lentivirally transduced BM may favor such oligo-clonal dominance observed in this experiment, we characterized the clonal composition of JAK2-mutant HSCs in non-transplanted MPN mice. To this end, we crossed a CRISPR-based genetic barcoding mouse line ( CARLIN) (Bowling, S. et al, Cell 2020) with our VF mice to obtain VF;CARLIN mice. Cas9-mediated barcoding in VF;CARLIN or in CARLIN mice with wildtype Jak2(WT;CARLIN) was induced with doxycycline and immediately followed by the activation of the JAK2-V617F by tamoxifen (Figure 1A). After 12 weeks, when the mice developed full PV phenotype (hemoglobin 195 g/L; platelets 4.3x10 12 /L and neutrophils 10.5x10 9/L), we performed scRNAseq on lin- cKit+ BM cells using the 10X-platform to retrieve the cellular barcodes and transcriptomic profiles. MPN hematopoiesis in these non-transplanted VF;CARLIN mice was polyclonal (Figure 1B). A total of > 500 barcoded clones per mouse were detected and in both VF;CARLIN and WT;CARLIN mice, but ~5 individual barcodes accounted for 25% of the cells in all progenitor subsets analyzed (Figure 1B). Overall, clonal composition was similar between WT;CARLIN and VF;CARLIN mice, indicating that clonal selection was not more prominent in JAK2-mutant mice. Importantly, in the offspring of HSCs that accounted for 25% of the cells, we did not observe preferential presence of some barcodes in MkP versus EryP and other barcodes in EryP versus MkP, arguing against the model predicting that erythrocytosis and thrombocytosis originated in different subsets of biased HSCs. To investigate the question of whether sensitivity or resistance to IFNα could be also due to heterogeneity in HSC subpopulations, we transplanted BM cells from these barcoded VF;CARLIN mice together with an excess of WT competitor cells into irradiated WT recipient mice, and treated them with IFNα or vehicle for 16 weeks. IFNα normalized hemoglobin (122 g/L) compared to vehicle (177 g/L) and reduced VF;CARLIN chimerism in granulocytes from 85% to 44%. BM cells were harvested and the clonal composition is currently being analyzed by NGS in order to identify IFNα resistant and sensitive subclones. Our barcoding analyses of individual HSCs showed that, during recovery after BM transplantations, a few VF clones dominated, whereas induction of VF expression in situ without transplantation resulted in a polyclonal disease that showed a similar number of HSCs actively contributing to hematopoiesis as in a control experiment with WT mice. The lack of substantial preference in the clonal contribution of individual HSCs to erythropoiesis versus megakaryopoiesis in VF mice suggests that PV and ET are not caused by acquiring JAK2-V617F in HSCs with a pre-existing lineage bias.

Differential adhesion during development establishes individual neural stem cell niches and shapes adult behaviour in Drosophila.

Neural stem cells (NSCs) reside in a defined cellular microenvironment, the niche, which supports the generation and integration of newborn neurons. The mechanisms building a sophisticated niche structure around NSCs and their functional relevance for neurogenesis are yet to be understood. In the Drosophila larval brain, the cortex glia (CG) encase individual NSC lineages in membranous chambers, organising the stem cell population and newborn neurons into a stereotypic structure. We first found that CG wrap around lineage-related cells regardless of their identity, showing that lineage information builds CG architecture. We then discovered that a mechanism of temporally controlled differential adhesion using conserved complexes supports the individual encasing of NSC lineages. An intralineage adhesion through homophilic Neuroglian interactions provides strong binding between cells of a same lineage, while a weaker interaction through Neurexin-IV and Wrapper exists between NSC lineages and CG. Loss of Neuroglian results in NSC lineages clumped together and in an altered CG network, while loss of Neurexin-IV/Wrapper generates larger yet defined CG chamber grouping several lineages together. Axonal projections of newborn neurons are also altered in these conditions. Further, we link the loss of these 2 adhesion complexes specifically during development to locomotor hyperactivity in the resulting adults. Altogether, our findings identify a belt of adhesions building a neurogenic niche at the scale of individual stem cell and provide the proof of concept that niche properties during development shape adult behaviour.

Single-cell characterization of deformation and dynamics of mesenchymal stem cells in microfluidic systems: A computational study.

Understanding the homing dynamics of individual mesenchymal stem cells (MSCs) in physiologically relevant microenvironments is crucial for improving the efficacy of MSC-based therapies for therapeutic and targeting purposes. This study investigates the passive homing behavior of individual MSCs in micropores that mimic interendothelial clefts through predictive computational simulations informed by previous microfluidic experiments. Initially, we quantified the size-dependent behavior of MSCs in micropores and elucidated the underlying mechanisms. Subsequently, we analyzed the shape deformation and traversal dynamics of each MSC. In addition, we conducted a systematic investigation to understand how the mechanical properties of MSCs impact their traversal process. We considered geometric and mechanical parameters, such as reduced cell volume, cell-to-nucleus diameter ratio, and cytoskeletal prestress states. Furthermore, we quantified the changes in the MSC traversal process and identified the quantitative limits in their response to variations in micropore length. Taken together, the computational results indicate the complex dynamic behavior of individual MSCs in the confined microflow. This finding offers an objective way to evaluate the homing ability of MSCs in an interendothelial-slit-like microenvironment.