Early autonomous patterning of the anteroposterior axis in gastruloids.

Minimal in vitro systems composed of embryonic stem cells (ESCs) have been shown to recapitulate the establishment of the anteroposterior (AP) axis. In contrast to the native embryo, ESC aggregates - such as gastruloids - can break symmetry, which is demarcated by polarization of the mesodermal marker T, autonomously without any localized external cues. However, associated earliest patterning events, such as the spatial restriction of cell fates and concomitant transcriptional changes, remain poorly understood.

Regulation of intercellular viscosity by E-cadherin-dependent phosphorylation of EGFR in collective cell migration.

Collective cell migration is crucial in various physiological processes, including wound healing, morphogenesis, and cancer metastasis. Adherens Junctions (AJs) play a pivotal role in regulating cell cohesion and migration dynamics during tissue remodeling. While the role and origin of the junctional mechanical tension at AJs have been extensively studied, the influence of the actin cortex structure and dynamics on junction plasticity remains incompletely understood.

The positioning mechanics of microtubule asters in embryo explants.

Microtubule asters are essential in localizing the action of microtubules in processes including mitosis and organelle positioning. In large cells, such as the one-cell sea urchin embryo, aster dynamics are dominated by hydrodynamic pulling forces. However, in systems with more densely positioned nuclei such as the early embryo, which packs around 6000 nuclei within the syncytium in a crystalline-like order, it is unclear what processes dominate aster dynamics.

Learning the mechanobiology of development from gastruloids.

Gastruloids acquire their organization and shape through cell biochemical and mechanical activities. Such activities determine the physical forces and changes in material properties that transform simple spherical aggregates into organized tissues. In this Perspective, we discuss why the concepts and approaches of mechanobiology, a discipline that focuses on cell and tissue mechanics and its contribution to the organization and functions of living systems, are essential to the gastruloid field and, in turn, what gastruloids may teach us about mechanobiology.

A microfluidic platform to investigate the role of mechanical constraints on tissue reorganization.

Mechanical constraints have a high impact on development processes, and there is a need for new tools to investigate the role of mechanosensitive pathways in tissue reorganization during development. We present here experiments in which embryonic cell aggregates are aspired through constrictions in microfluidic channels, generating highly heterogeneous flows and large cell deformations that can be imaged using two-photon microscopy. This approach provides a way to measure in situ local viscoelastic properties of 3D tissues and connect them to intracellular and intercellular events, such as cell shape changes and cell rearrangements.

Splenogonadal fusion: A case series of two challenging diagnoses.

Splenogonadal fusion is an abnormal connection between the spleen and gonads. This rare entity can be easily confused with testicular tumors. It usually accompanies congenital malformations, such as cryptorchidism, making diagnosis more difficult.

Readmissions to kidney transplantation department: incidence, causes and risk factors.

Introduction: hospital readmission after kidney transplantation is an important metric for health care quality, which associated with increased morbidity, costs and transition-of-care errors. It is influenced by population demographics and the comprehensiveness of the healthcare system. The aim of this study was to evaluate incidence causes and risk factors associated with hospital readmission within the first year after transplantation.

Condensation of the Drosophila nerve cord is oscillatory and depends on coordinated mechanical interactions.

During development, organs reach precise shapes and sizes. Organ morphology is not always obtained through growth; a classic counterexample is the condensation of the nervous system during Drosophila embryogenesis. The mechanics underlying such condensation remain poorly understood.

Cell-state transitions and collective cell movement generate an endoderm-like region in gastruloids.

Shaping the animal body plan is a complex process that involves the spatial organization and patterning of the different germ layers. Recent advances in live imaging have started to unravel the cellular choreography underlying this process in mammals, however, the sequence of events transforming an unpatterned cell ensemble into structured territories is largely unknown. Here, using gastruloids -3D aggregates of mouse embryonic stem cells- we study the formation of one of the three germ layers, the endoderm.

Chest Wall Monophasic Synovial Sarcoma in a 12-Year-Old Boy: A Case Report.

We report a rare case of synovial sarcoma of the chest wall in a child. A 12-year-old male presented to our pediatric surgery department with chief complaint of swelling accompanied by slight pain of the upper right side of the anterior chest wall since approximately 5 months. Firstly, we performed an ultrasound (US)-mass biopsy.

Detection of AmpC and ESBL-producing Enterobacterales isolated from urinary tract infections in Tunisia.

Urinary tract infections (UTIs) are the most frequent human infections in community and hospitals. This study aimed to determine the distribution of bacterial uropathogens among urinary tract infections diagnosed within the regional hospital Houcine Bouzaiene (Gafsa, South West Tunisia) during a survey of 54 days from the 8th of November to the 31st of December 2017. Enterobacterales strains were tested for antimicrobial resistance by disk diffusion method and extended-spectrum β-lactamase (ESBL) production was tested by double-disc synergy test.

Aster repulsion drives short-ranged ordering in the Drosophila syncytial blastoderm.

Biological systems are highly complex, yet notably ordered structures can emerge. During syncytial stage development of the Drosophila melanogaster embryo, nuclei synchronously divide for nine cycles within a single cell, after which most of the nuclei reach the cell cortex. The arrival of nuclei at the cortex occurs with remarkable positional order, which is important for subsequent cellularisation and morphological transformations.

Type 2 transverse testicular ectopia: A case report.

Transverse testicular ectopia(TTE) is a rare anomaly defined by the presence of both testis in the same hemiscrotum or in the same inguinal canal.The main treatment of TTE is surgical intervention. Here we report a case of type 2 transverse testicular ectopia in an eight months old child.

New challenges of marine ecotoxicology in a global change context.

Currently, research agenda in marine ecotoxicology is facing new challenges with the emergence of newly and complex synthetized chemicals. The study of the fate and adverse effects of toxicants remains increasingly complicated with global change events. Ecotoxicology had provided for a decades, precious scientific data and knowledge but also technical and management tools for the environmental community.

Migrating Epithelial Monolayer Flows Like a Maxwell Viscoelastic Liquid.

We perform a bidimensional Stokes experiment in an active cellular material: an autonomously migrating monolayer of Madin-Darby canine kidney epithelial cells flows around a circular obstacle within a long and narrow channel, involving an interplay between cell shape changes and neighbor rearrangements. Based on image analysis of tissue flow and coarse-grained cell anisotropy, we determine the tissue strain rate, cell deformation, and rearrangement rate fields, which are spatially heterogeneous. We find that the cell deformation and rearrangement rate fields correlate strongly, which is compatible with a Maxwell viscoelastic liquid behavior (and not with a Kelvin-Voigt viscoelastic solid behavior).

Amoeboid Swimming Is Propelled by Molecular Paddling in Lymphocytes.

Mammalian cells developed two main migration modes. The slow mesenchymatous mode, like crawling of fibroblasts, relies on maturation of adhesion complexes and actin fiber traction, whereas the fast amoeboid mode, observed exclusively for leukocytes and cancer cells, is characterized by weak adhesion, highly dynamic cell shapes, and ubiquitous motility on two-dimensional and in three-dimensional solid matrix. In both cases, interactions with the substrate by adhesion or friction are widely accepted as a prerequisite for mammalian cell motility, which precludes swimming.

Primary hydatid cyst of the small intestine masquerading as intestinal duplication in a child.

Hydatid disease or hydatidosis is a worldwide zoonosis disease caused by the tapeworm of and still widely endemic in Tunisia especially in rural areas where the sheep-dog cycle is dominant. It is an important public health problem in the pediatric age group causing significant morbidity and mortality. We report a case of primary hydatid cyst of the small intestine in a child and we want to highlight the difficulty that we meet in the diagnosis despite the contribution of imaging.

Microplastics mixture exposure at environmentally relevant conditions induce oxidative stress and neurotoxicity in the wedge clam Donax trunculus.

Contamination by micro and nano plastics is actually considered as a global environmental preoccupation. The quantification of microplastics in natural habitats and the characterization of their potential effects in marine wild organisms is currently of high importance. The main objective of this work was to investigate the fate and the effects of a microplastic mixture (ratio of 1: polyethylene (PE), 1: polypropylene (PP)) in the wedge clam Donax trunculus.

Pcdh18a regulates endocytosis of E-cadherin during axial mesoderm development in zebrafish.

The notochord defines the axial structure of all vertebrates during development. Notogenesis is a result of major cell reorganization in the mesoderm, the convergence and the extension of the axial cells. However, it is currently not fully understood how these processes act together in a coordinated way during notochord formation.

Shaping the zebrafish myotome by intertissue friction and active stress.

Organ formation is an inherently biophysical process, requiring large-scale tissue deformations. Yet, understanding how complex organ shape emerges during development remains a major challenge. During zebrafish embryogenesis, large muscle segments, called myotomes, acquire a characteristic chevron morphology, which is believed to aid swimming.

Fast determination of coarse-grained cell anisotropy and size in epithelial tissue images using Fourier transform.

Mechanical strain and stress play a major role in biological processes such as wound healing or morphogenesis. To assess this role quantitatively, fixed or live images of tissues are acquired at a cellular precision in large fields of views. To exploit these data, large numbers of cells have to be analyzed to extract cell shape anisotropy and cell size.

Activation of butterfly eyespots by Distal-less is consistent with a reaction-diffusion process.

Eyespots on the wings of nymphalid butterflies represent colorful examples of pattern formation, yet the developmental origins and mechanisms underlying eyespot center differentiation are still poorly understood. Using CRISPR-Cas9 we re-examine the function of Distal-less (Dll) as an activator or repressor of eyespots, a topic that remains controversial. We show that the phenotypic outcome of CRISPR mutations depends upon which specific exon is targeted.