Brakes and leverages for reducing the environmental impact of laboratory animal facilities: A case study at the Institut Pasteur.

The Institut Pasteur has set the ambition to encourage all staff to get involved in sustainable development across all departments on campus. The animal facility staff joined the efforts of the sustainable development department to analyse current and future processes and identify potential solutions and related brakes and leverages for the reduction of the animal facilities' environmental impact. The first step was to collect the managers' experience on the local initiatives.

Anti-diarrheal drug loperamide induces dysbiosis in zebrafish microbiota via bacterial inhibition.

Background: Perturbations of animal-associated microbiomes from chemical stress can affect host physiology and health. While dysbiosis induced by antibiotic treatments and disease is well known, chemical, nonantibiotic drugs have recently been shown to induce changes in microbiome composition, warranting further exploration. Loperamide is an opioid-receptor agonist widely prescribed for treating acute diarrhea in humans.

Apical size and expression predict adult neural stem cell decisions along lineage progression.

The maintenance of neural stem cells (NSCs) in the adult brain depends on their activation frequency and division mode. Using long-term intravital imaging of NSCs in the zebrafish adult telencephalon, we reveal that apical surface area and expression of the Notch ligand DeltaA predict these NSC decisions. -negative NSCs constitute a bona fide self-renewing NSC pool and systematically engage in asymmetric divisions generating a self-renewing daughter, which regains the size and behavior of its mother, and a neurogenic daughter, eventually engaged in neuronal production following further quiescence-division phases.

Dynamic spatiotemporal coordination of neural stem cell fate decisions occurs through local feedback in the adult vertebrate brain.

Neural stem cell (NSC) populations persist in the adult vertebrate brain over a lifetime, and their homeostasis is controlled at the population level through unknown mechanisms. Here, we combine dynamic imaging of entire NSC populations in their in vivo niche over several weeks with pharmacological manipulations, mathematical modeling, and spatial statistics and demonstrate that NSCs use spatiotemporally resolved local feedback signals to coordinate their decision to divide in adult zebrafish brains. These involve Notch-mediated short-range inhibition from transient neural progenitors and a dispersion effect from the dividing NSCs themselves exerted with a delay of 9-12 days.

Life-Long Neurogenic Activity of Individual Neural Stem Cells and Continuous Growth Establish an Outside-In Architecture in the Teleost Pallium.

Spatiotemporal variations of neurogenesis are thought to account for the evolution of brain shape. In the dorsal telencephalon (pallium) of vertebrates, it remains unresolved which ancestral neurogenesis mode prefigures the highly divergent cytoarchitectures that are seen in extant species. To gain insight into this question, we developed genetic tools to generate here the first 4-dimensional (3D + birthdating time) map of pallium construction in the adult teleost zebrafish.

Large-scale live imaging of adult neural stem cells in their endogenous niche.

Live imaging of adult neural stem cells (aNSCs) in vivo is a technical challenge in the vertebrate brain. Here, we achieve long-term imaging of the adult zebrafish telencephalic neurogenic niche and track a population of >1000 aNSCs over weeks, by taking advantage of fish transparency at near-infrared wavelengths and of intrinsic multiphoton landmarks. This methodology enables us to describe the frequency, distribution and modes of aNSCs divisions across the entire germinal zone of the adult pallium, and to highlight regional differences in these parameters.

Spatial regionalization and heterochrony in the formation of adult pallial neural stem cells.

Little is known on the embryonic origin and related heterogeneity of adult neural stem cells (aNSCs). We use conditional genetic tracing, activated in a global or mosaic fashion by cell type-specific promoters or focal laser uncaging, coupled with gene expression analyses and Notch invalidations, to address this issue in the zebrafish adult telencephalon. We report that the germinal zone of the adult pallium originates from two distinct subtypes of embryonic progenitors and integrates two modes of aNSC formation.

Inter-individual and inter-strain variations in zebrafish locomotor ontogeny.

Zebrafish exhibit remarkable alterations in behaviour and morphology as they develop from early larval stages to mature adults. In this study we compare the locomotion parameters of six common zebrafish strains from two different laboratories to determine the stability and repeatability of these behaviours. Our results demonstrate large variability in locomotion and fast swim events between strains and between laboratories across time.