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In the telencephalon of adult zebrafish, the inhibitor of DNA binding 1(id1) gene is expressed in radial glial cells (RGCs), behaving as neural stem cells (NSCs), during constitutive and regenerative neurogenesis. Id1 controls the balance between resting and proliferating states of RGCs by promoting quiescence. Here, we identified a phylogenetically conserved cis‐regulatory module (CRM) mediating the specific expression of id1in RGCs.Systematic deletion mapping and mutation of conserved transcription factor binding sites in stable transgenic zebrafish lines reveal that this CRM operates via conserved smad1/5and 4binding motifs under both homeostatic and regenerative conditions. Transcriptome analysis of injured and uninjured telencephala as well as pharmacological inhibition experiments identify a crucial role of bone morphogenetic protein (BMP) signaling for the function of the CRM. Our data highlight that BMP signals control id1expression and thus NSC proliferation during constitutive and induced neurogenesis. The bone morphogenetic protein (BMP) pathway controls inhibitor of DNA binding 1(id1) expression in the radial glial cells (RGCs) during both constitutive and regenerative neurogenesis. An evolutionary conserved cis‐regulatory module (CRM) of id1is necessary for its RGC‐specific expression. The id1CRM contains a BMP responsive element, which is necessary but not sufficient for the expression of id1in the ventricular zone of the zebrafish adult telencephalon. The human CRM2 works in zebrafish. Thus its function was conserved during evolution.

Systems biology methods, such as transcriptomics and metabolomics, require large numbers of small model organisms, such as zebrafish embryos. Manual separation of mutant embryos from wild-type embryos is a tedious and time-consuming task that is prone to errors, especially if there are variable phenotypes of a mutant. Here we describe a zebrafish embryo sorting system with two cameras and image processing based on template-matching algorithms. In order to evaluate the system, zebrafish rx3 mutants that lack eyes due to a patterning defect in brain development were separated from their wild-type siblings. These mutants show glucocorticoid deficiency due to pituitary defects and serve as a model for human secondary adrenal insufficiencies. We show that the variable phenotypes of the mutant embryos can be safely distinguished from phenotypic wild-type zebrafish embryos and sorted from one petri dish into another petri dish or into a 96-well microtiter plate. On average, classification of a zebrafish embryo takes approximately 1 s, with a sensitivity and specificity of 87% to 95%, respectively. Other morphological phenotypes may be classified and sorted using similar techniques.

Systems biology methods, such as transcriptomics and metabolomics, require large numbers of small model organisms, such as zebrafish embryos. Manual separation of mutant embryos from wild-type embryos is a tedious and time-consuming task that is prone to errors, especially if there are variable phenotypes of a mutant. Here we describe a zebrafish embryo sorting system with two cameras and image processing based on template-matching algorithms. In order to evaluate the system, zebrafish rx3 mutants that lack eyes due to a patterning defect in brain development were separated from their wild-type siblings. These mutants show glucocorticoid deficiency due to pituitary defects and serve as a model for human secondary adrenal insufficiencies. We show that the variable phenotypes of the mutant embryos can be safely distinguished from phenotypic wild-type zebrafish embryos and sorted from one petri dish into another petri dish or into a 96-well microtiter plate. On average, classification of a zebrafish embryo takes approximately 1 s, with a sensitivity and specificity of 87% to 95%, respectively. Other morphological phenotypes may be classified and sorted using similar techniques.

Mutations in myosin chaperones Unc45b and Hsp90aa1.1 as well as in the Unc45b-binding protein Smyd1b impair formation of myofibrils in skeletal muscle and lead to the accumulation of misfolded myosin. The concomitant transcriptional response involves up-regulation of the three genes encoding these proteins, as well as genes involved in muscle development. The transcriptional up-regulation of unc45b, hsp90aa1.1and smyd1bis specific to zebrafish mutants with myosin folding defects, and is not triggered in other zebrafish myopathy models. By dissecting the promoter of unc45b, we identify a Heat shock factor 1 (Hsf1) binding element as a mediator of unc45bup-regulation in myofibers lacking myosin folding proteins. Loss-of-function of Hsf1 abolishes unc45bup-regulation in mutants with defects in myosin folding. Taken together, our data show that skeletal muscle cells respond to defective myosin chaperones with a complex gene program and suggest that this response is mediated by Hsf1 activation.

The teleost brain has the remarkable ability to generate new neurons and to repair injuries during adult life stages. Maintaining life‐long neurogenesis requires careful management of neural stem cell pools. In a genome‐wide expression screen for transcription regulators, the id1gene, encoding a negative regulator of E‐proteins, was found to be upregulated in response to injury. id1expression was mapped to quiescent type I neural stem cells in the adult telencephalic stem cell niche. Gain and loss of id1function in vivo demonstrated that Id1 promotes stem cell quiescence. The increased id1expression observed in neural stem cells in response to injury appeared independent of inflammatory signals, suggesting multiple antagonistic pathways in the regulation of reactive neurogenesis. Together, we propose that Id1 acts to maintain the neural stem cell pool by counteracting neurogenesis‐promoting signals. StemCells2015;33:892–903

AbstractWe have established a European Zebrafish Resource Center (EZRC) at the KIT. This center not only maintains and distributes a large number of existing mutant and transgenic zebrafish lines but also gives zebrafish researchers access to screening services and technologies such as imaging and high-throughput sequencing, provided by the Institute of Toxicology and Genetics (ITG). The EZRC maintains and distributes the stock collection of the Nüsslein-Volhard laboratory, comprising over 2000 publicly released mutations, as frozen sperm samples. Within the framework of the ZF-HEALTH EU project, the EZRC distributes over 10,000 knockout mutations from the Sanger Institute (United Kingdom), as well as over 100 mutant and transgenic lines from other sources. In this article, we detail the measures we have taken to ensure the health of our fish, including hygiene, quarantine, and veterinary inspections.