Recognising the importance and impact of Imaging Scientists: Global guidelines for establishing career paths within core facilities.

In the dynamic landscape of scientific research, imaging core facilities are vital hubs propelling collaboration and innovation at the technology development and dissemination frontier. Here, we present a collaborative effort led by Global BioImaging (GBI), introducing international recommendations geared towards elevating the careers of Imaging Scientists in core facilities. Despite the critical role of Imaging Scientists in modern research ecosystems, challenges persist in recognising their value, aligning performance metrics and providing avenues for career progression and job security. The challenges encompass a mismatch between classic academic career paths and service-oriented roles, resulting in a lack of understanding regarding the value and impact of Imaging Scientists and core facilities and how to evaluate them properly. They further include challenges around sustainability, dedicated training opportunities and the recruitment and retention of talent. Structured across these interrelated sections, the recommendations within this publication aim to propose globally applicable solutions to navigate these challenges. These recommendations apply equally to colleagues working in other core facilities and research institutions through which access to technologies is facilitated and supported. This publication emphasises the pivotal role of Imaging Scientists in advancing research programs and presents a blueprint for fostering their career progression within institutions all around the world.

PTEN maintains haematopoietic stem cells and acts in lineage choice and leukaemia prevention.

Haematopoietic stem cells (HSCs) must achieve a balance between quiescence and activation that fulfils immediate demands for haematopoiesis without compromising long-term stem cell maintenance, yet little is known about the molecular events governing this balance. Phosphatase and tensin homologue (PTEN) functions as a negative regulator of the phosphatidylinositol-3-OH kinase (PI(3)K)-Akt pathway, which has crucial roles in cell proliferation, survival, differentiation and migration. Here we show that inactivation of PTEN in bone marrow HSCs causes their short-term expansion, but long-term decline, primarily owing to an enhanced level of HSC activation. PTEN-deficient HSCs engraft normally in recipient mice, but have an impaired ability to sustain haematopoietic reconstitution, reflecting the dysregulation of their cell cycle and decreased retention in the bone marrow niche. Mice with PTEN-mutant bone marrow also have an increased representation of myeloid and T-lymphoid lineages and develop myeloproliferative disorder (MPD). Notably, the cell populations that expand in PTEN mutants match those that become dominant in the acute myeloid/lymphoid leukaemia that develops in the later stages of MPD. Thus, PTEN has essential roles in restricting the activation of HSCs, in lineage fate determination, and in the prevention of leukaemogenesis.

Oscillations of the snail genes in the presomitic mesoderm coordinate segmental patterning and morphogenesis in vertebrate somitogenesis.

The segmented body plan of vertebrate embryos arises through segmentation of the paraxial mesoderm to form somites. The tight temporal and spatial control underlying this process of somitogenesis is regulated by the segmentation clock and the FGF signaling wavefront. Here, we report the cyclic mRNA expression of Snail 1 and Snail 2 in the mouse and chick presomitic mesoderm (PSM), respectively. Whereas Snail genes' oscillations are independent of NOTCH signaling, we show that they require WNT and FGF signaling. Overexpressing Snail 2 in the chick embryo prevents cyclic Lfng and Meso 1 expression in the PSM and disrupts somite formation. Moreover, cells mis-expressing Snail 2 fail to express Paraxis, remain mesenchymal, and are thereby inhibited from undergoing the epithelialization event that culminates in the formation of the epithelial somite. Thus, Snail genes define a class of cyclic genes that coordinate segmentation and PSM morphogenesis.

Sterile and disposable fluidic subsystem suitable for clinical high speed fluorescence-activated cell sorting.

BACKGROUND: Applications of fluorescence-activated cell sorting (FACS) are ideally performed under aseptic conditions so that isolated cells can be successfully cultured, transplanted, or processed for the isolation of protein and nucleic acids. However, modern "off-the shelf" flow cytometers are suboptimally designed for these purposes because nonsterile instrument hardware components directly contact sample-harboring fluids, compromising their sterility. METHODS: We have described the design and modular modification of a cytometer with a sterile and disposable FACS fluid handling system that meets requirements of high-speed FACS and good manufacturing practice. This system was tested for functionality and its ability to maintain a clean and sterile fluid environment. RESULTS: Our data have shown that this new fluidic subsystem completely replicated the intended function of the manufacturer's standard fluid handling system, and isolates the fluid from contaminants such as bacteria and fungus, endotoxins, mycoplasma, and helicobacter. CONCLUSIONS: FACS has emerged as a powerful tool used to study and manipulate stem cells. However, if stem cell discoveries are to be fully utilized in clinical transplant medicine, aseptic instrument configurations must be developed. For this purpose, we have designed a disposable sterile fluid handling system.

Tcof1/Treacle is required for neural crest cell formation and proliferation deficiencies that cause craniofacial abnormalities.

Neural crest cells are a migratory cell population that give rise to the majority of the cartilage, bone, connective tissue, and sensory ganglia in the head. Abnormalities in the formation, proliferation, migration, and differentiation phases of the neural crest cell life cycle can lead to craniofacial malformations, which constitute one-third of all congenital birth defects. Treacher Collins syndrome (TCS) is characterized by hypoplasia of the facial bones, cleft palate, and middle and external ear defects. Although TCS results from autosomal dominant mutations of the gene TCOF1, the mechanistic origins of the abnormalities observed in this condition are unknown, and the function of Treacle, the protein encoded by TCOF1, remains poorly understood. To investigate the developmental basis of TCS we generated a mouse model through germ-line mutation of Tcof1. Haploinsufficiency of Tcof1 leads to a deficiency in migrating neural crest cells, which results in severe craniofacial malformations. We demonstrate that Tcof1/Treacle is required cell-autonomously for the formation and proliferation of neural crest cells. Tcof1/Treacle regulates proliferation by controlling the production of mature ribosomes. Therefore, Tcof1/Treacle is a unique spatiotemporal regulator of ribosome biogenesis, a deficiency that disrupts neural crest cell formation and proliferation, causing the hypoplasia characteristic of TCS craniofacial anomalies.