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Otterstrom, J.

Publications and source records attributed to Otterstrom, J..

2 recordsLinked to original sources

A versatile automated high-throughput drug screening platform for zebrafish embryos

Zebrafish provide a unique opportunity for drug screening in living animals, with the fast developing, transparent embryos allowing for relatively high throughput, microscopy-based screens. However, the limited availability of rapid, flexible imaging and analysis platforms has limited the use of zebrafish in drug screens. We have developed a easy-to-use, customisable automated screening procedure suitable for high-throughput phenotype-based screens of live zebrafish. We utilised the WiScan(R) Hermes High Content Imaging System to rapidly acquire brightfield and fluorescent images of embryos, and the WiSoft(R) Athena Zebrafish Application for analysis, which harnesses an Artificial Intelligence-driven algorithm to automatically detect fish in brightfield images, identify anatomical structures, partition the animal into regions, and exclusively select the desired side-oriented fish. Our initial validation combined structural analysis with fluorescence images to enumerate GFP-tagged haematopoietic stem and progenitor cells in the tails of embryos, which correlated with manual counts. We further validated this system to assess the effects of genetic mutations and x-ray irradiation in high content using a wide range of assays. Further, we performed simultaneous analysis of multiple cell types using dual fluorophores in high throughput. In summary, we demonstrate a broadly applicable and rapidly customisable platform for high content screening in zebrafish.

cell biology↗

Nanoscale decompaction of nucleosomal DNA revealed through multi-color super-resolution microscopy

Chromatin organization plays an important role in regulating gene expression. Previously, we showed that chromatin is organized in the form of nucleosome groups or clutches. The size and nucleosome packing density of clutches decreased in hyperacetylated cells having more open chromatin. While hyperacetylation is thought to disrupt histone-DNA and inter-nucleosome interactions, its impact on higher order DNA compaction by groups of nucleosomes in vivo is not clear. To elucidate this question, we carried out two-color super-resolution imaging of histones and DNA in cells treated with the Histone Deacetylase (HDAC) inhibitor Trichostatin A (TSA). We showed that a lower percentage of DNA was associated to clutches in hyperacetylated cells, suggesting a decrease in nucleosome occupancy. We further identified the presence of \"clutch\" DNA within a nanoscale distance around the clutches. Upon histone hyperacetylation, the radius of the clutch DNA decreased leading to DNA release from the clutches, consistent with disruption of DNA-histone interactions. Finally, the most dramatic decompaction was observed for groups of clutches in close spatial proximity, suggesting that neighboring clutches influence each others DNA compaction.\n\nSummarySuper-resolution imaging of histones and DNA reveals that DNA is compacted by groups of nucleosomes - clutches - at the nanoscale level and clutch compaction of DNA is affected by histone tail acetylation especially in highly folded regions containing several nearby clutches.

cell biology↗