Evaluating Toxicity of Chemicals using a Zebrafish Vibration Startle Response Screening System

We developed a simple screening system for the evaluation of neuromuscular and general toxicity in zebrafish embryos. The modular system consists of electrodynamic transducers above which tissue culture dishes with embryos can be placed. Multiple such loudspeaker-tissue culture dish pairs can be combined. Vibrational stimuli generated by the electrodynamic transducers induce a characteristic startle and escape response in the embryos. A belt-driven linear drive sequentially positions a camera above each loudspeaker to record the movement of the embryos. In this way, alterations to the startle response due to lethality or neuromuscular toxicity of chemical compounds can be visualized and quantified. We present an example of the workflow for chemical compound screening using this system, including the preparation of embryos and treatment solutions, operation of the recording system, and data analysis to calculate benchmark concentration values of compounds active in the assay. The modular assembly based on commercially available simple components makes this system both economical and flexibly adaptable to the needs of particular laboratory setups and screening purposes

Heterozygous Loss-of-Function SEC61A1 Mutations Cause Autosomal-Dominant Tubulo-Interstitial and Glomerulocystic Kidney Disease with Anemia

Autosomal-dominant tubulo-interstitial kidney disease (ADTKD) encompasses a group of disorders characterized by renal tubular and interstitial abnormalities, leading to slow progressive loss of kidney function requiring dialysis and kidney transplantation. Mutations in UMOD, MUC1, and REN are responsible for many, but not all, cases of ADTKD. We report on two families with ADTKD and congenital anemia accompanied by either intrauterine growth retardation or neutropenia. Ultrasound and kidney biopsy revealed small dysplastic kidneys with cysts and tubular atrophy with secondary glomerular sclerosis, respectively. Exclusion of known ADTKD genes coupled with linkage analysis, whole-exome sequencing, and targeted re-sequencing identified heterozygous missense variants in SEC61A1—c.553A>G (p.Thr185Ala) and c.200T>G (p.Val67Gly)—both affecting functionally important and conserved residues in SEC61. Both transiently expressed SEC6A1A variants are delocalized to the Golgi, a finding confirmed in a renal biopsy from an affected individual. Suppression or CRISPR-mediated deletions of sec61al2 in zebrafish embryos induced convolution defects of the pronephric tubules but not the pronephric ducts, consistent with the tubular atrophy observed in the affected individuals. Human mRNA encoding either of the two pathogenic alleles failed to rescue this phenotype as opposed to a complete rescue by human wild-type mRNA. Taken together, these findings provide a mechanism by which mutations in SEC61A1 lead to an autosomal-dominant syndromic form of progressive chronic kidney disease. We highlight protein translocation defects across the endoplasmic reticulum membrane, the principal role of the SEC61 complex, as a contributory pathogenic mechanism for ADTKD

Etude du rôle de CHD8 dans les troubles gastro-intestinaux associés aux troubles du spectre autistique

CHD8 is one of the major candidate genes for autism spectrum disorders (ASD). Individuals carrying a mutation in CHD8 present with ASD, macrocephaly, gastro-intestinal defects, and sleep disorders. We used a stable zebrafish mutant line for chd8 to recapitulate the phenotypes displayed by individuals carrying a mutation in CHD8. Mutant larvae present with a reduced number of enteric neurons, confirming previous results obtained with a transient knock-down of chd8 in zebrafish. We then investigated the origin of the reduced number of enteric neurons and we found that migration, proliferation, and differentiation of the enteric Neural Crest Cells were affected in mutant zebrafish larvae. In addition, the serotonin synthesis and signaling pathway was dysregulated in mutant larvae, leading to possible disruption of signal transduction in enteric neurons, and likely driving the activation of inflammation in the gut of mutant larvae.Les patients porteurs d’une mutation dans CHD8, gène candidat majeur pour les Troubles du Spectre Autistique (TSA), présentent une macrocéphalie, des troubles gastro-intestinaux et des troubles du sommeil. Nous avons utilisé une lignée mutante stable pour chd8 et avons observé qu’elle reproduit les phénotypes observés chez les individus porteurs d’une mutation dans CHD8. Les larves mutantes présentent une diminution du nombre de neurones entériques, dont nous avons cherché l’origine. Nous avons observé des défauts de prolifération, de migration ou de différenciation des Cellules de la Crête Neurale entériques. De plus, la synthèse de la sérotonine et la signalisation sérotoninergique étaient altérées dans les larves mutantes, ce qui pourrait induire une mauvaise transduction du signal dans les neurones entériques, ainsi qu’une activation de l’inflammation dans l’intestin des larves mutantes

Role of CHD8 in the gastrointestinal troubles associated with autism spectrum disorders

Les patients porteurs d’une mutation dans CHD8, gène candidat majeur pour les Troubles du Spectre Autistique (TSA), présentent une macrocéphalie, des troubles gastro-intestinaux et des troubles du sommeil. Nous avons utilisé une lignée mutante stable pour chd8 et avons observé qu’elle reproduit les phénotypes observés chez les individus porteurs d’une mutation dans CHD8. Les larves mutantes présentent une diminution du nombre de neurones entériques, dont nous avons cherché l’origine. Nous avons observé des défauts de prolifération, de migration ou de différenciation des Cellules de la Crête Neurale entériques. De plus, la synthèse de la sérotonine et la signalisation sérotoninergique étaient altérées dans les larves mutantes, ce qui pourrait induire une mauvaise transduction du signal dans les neurones entériques, ainsi qu’une activation de l’inflammation dans l’intestin des larves mutantes.CHD8 is one of the major candidate genes for autism spectrum disorders (ASD). Individuals carrying a mutation in CHD8 present with ASD, macrocephaly, gastro-intestinal defects, and sleep disorders. We used a stable zebrafish mutant line for chd8 to recapitulate the phenotypes displayed by individuals carrying a mutation in CHD8. Mutant larvae present with a reduced number of enteric neurons, confirming previous results obtained with a transient knock-down of chd8 in zebrafish. We then investigated the origin of the reduced number of enteric neurons and we found that migration, proliferation, and differentiation of the enteric Neural Crest Cells were affected in mutant zebrafish larvae. In addition, the serotonin synthesis and signaling pathway was dysregulated in mutant larvae, leading to possible disruption of signal transduction in enteric neurons, and likely driving the activation of inflammation in the gut of mutant larvae

Etude du rôle de CHD8 dans les troubles gastro-intestinaux associés aux troubles du spectre autistique

CHD8 is one of the major candidate genes for autism spectrum disorders (ASD). Individuals carrying a mutation in CHD8 present with ASD, macrocephaly, gastro-intestinal defects, and sleep disorders. We used a stable zebrafish mutant line for chd8 to recapitulate the phenotypes displayed by individuals carrying a mutation in CHD8. Mutant larvae present with a reduced number of enteric neurons, confirming previous results obtained with a transient knock-down of chd8 in zebrafish. We then investigated the origin of the reduced number of enteric neurons and we found that migration, proliferation, and differentiation of the enteric Neural Crest Cells were affected in mutant zebrafish larvae. In addition, the serotonin synthesis and signaling pathway was dysregulated in mutant larvae, leading to possible disruption of signal transduction in enteric neurons, and likely driving the activation of inflammation in the gut of mutant larvae.Les patients porteurs d’une mutation dans CHD8, gène candidat majeur pour les Troubles du Spectre Autistique (TSA), présentent une macrocéphalie, des troubles gastro-intestinaux et des troubles du sommeil. Nous avons utilisé une lignée mutante stable pour chd8 et avons observé qu’elle reproduit les phénotypes observés chez les individus porteurs d’une mutation dans CHD8. Les larves mutantes présentent une diminution du nombre de neurones entériques, dont nous avons cherché l’origine. Nous avons observé des défauts de prolifération, de migration ou de différenciation des Cellules de la Crête Neurale entériques. De plus, la synthèse de la sérotonine et la signalisation sérotoninergique étaient altérées dans les larves mutantes, ce qui pourrait induire une mauvaise transduction du signal dans les neurones entériques, ainsi qu’une activation de l’inflammation dans l’intestin des larves mutantes

Role of CHD8 in the gastrointestinal troubles associated with autism spectrum disorders

Les patients porteurs d’une mutation dans CHD8, gène candidat majeur pour les Troubles du Spectre Autistique (TSA), présentent une macrocéphalie, des troubles gastro-intestinaux et des troubles du sommeil. Nous avons utilisé une lignée mutante stable pour chd8 et avons observé qu’elle reproduit les phénotypes observés chez les individus porteurs d’une mutation dans CHD8. Les larves mutantes présentent une diminution du nombre de neurones entériques, dont nous avons cherché l’origine. Nous avons observé des défauts de prolifération, de migration ou de différenciation des Cellules de la Crête Neurale entériques. De plus, la synthèse de la sérotonine et la signalisation sérotoninergique étaient altérées dans les larves mutantes, ce qui pourrait induire une mauvaise transduction du signal dans les neurones entériques, ainsi qu’une activation de l’inflammation dans l’intestin des larves mutantes.CHD8 is one of the major candidate genes for autism spectrum disorders (ASD). Individuals carrying a mutation in CHD8 present with ASD, macrocephaly, gastro-intestinal defects, and sleep disorders. We used a stable zebrafish mutant line for chd8 to recapitulate the phenotypes displayed by individuals carrying a mutation in CHD8. Mutant larvae present with a reduced number of enteric neurons, confirming previous results obtained with a transient knock-down of chd8 in zebrafish. We then investigated the origin of the reduced number of enteric neurons and we found that migration, proliferation, and differentiation of the enteric Neural Crest Cells were affected in mutant zebrafish larvae. In addition, the serotonin synthesis and signaling pathway was dysregulated in mutant larvae, leading to possible disruption of signal transduction in enteric neurons, and likely driving the activation of inflammation in the gut of mutant larvae

A dominant vimentin variant causes a rare syndrome with premature aging

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