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Larsen, P.

Publications and source records attributed to Larsen, P..

2 recordsLinked to original sources

Deep coverage microscopy exposes a pharmacological window for modifiers of neuronal network connectivity

BackgroundTherapeutic developments for neurodegenerative disorders are redirecting their focus to the mechanisms that contribute to synaptic plasticity and the loss thereof. Identification of novel regulators requires a method to quantify neuronal network connectivity with high accuracy and throughput. To meet this demand, we have established a microscopy-based pipeline that integrates morphological and functional correlates of connectivity in primary neuronal culture. ResultsWe unveiled a connectivity signature that was specific to the cell type and culture age. We defined a score that accurately reports on the degree of neuronal connectivity and we validated this score by targeted perturbation of microtubule stability and selective depletion of anti-oxidants. With a focused compound screen, we discovered that inhibition of dual leucine zipper kinase activity increased neuronal connectivity in otherwise unperturbed cultures and exerted neuroprotective effects in cultures grown under sub-optimal or challenged conditions. ConclusionsOur results illustrate that profiling microscopy images with deep coverage enables sensitive interrogation of neuronal connectivity and allows exposing a dose and time window for pharmacological interventions. Therefore, the current approach holds promise for identifying pathways and compounds that preserve or rescue neuronal connectivity in neurodegenerative disorders.

neuroscience

Interrogation of genes controlling biofilm formation using CRISPR interference in Pseudomonas fluorescens

Bacterial biofilm formation involves multigenic signaling and regulatory pathways that control the transition from motile to sessile lifestyle, production of extracellular polymeric matrix, and maturation of the biofilm complex 3D structure. Biofilms are extensively studied because of their importance in biomedical, ecological and industrial settings. Genetic approaches based on gene inactivation are powerful for mechanistic studies but often are labor intensive, limiting systematic gene surveys to the most tractable bacterial hosts. Here, we adapted the CRISPR interference (CRISPRi) system for use in P. fluorescens. We found that CRISPRi is applicable to three genetically and physiologically diverse species, SBW25, WH6 and Pf0-1 and affords extended periods of time to study complex phenotypes such as cell morphology, motility and biofilm formation. In SBW25, CRISPRi-mediated silencing of the GacA/S two-component system and genes regulated by cylic-di-GMP produced phenotypes similar to those previously described after gene inactivation in various Pseudomonas. Combined with detailed confocal microscopy of biofilms, our study also revealed novel phenotypes associated with biofilm architecture and extracellular matrix biosynthesis as well as the potent inhibition of SBW25 biofilm formation mediated by the PFLU1114 protein. Thus, CRISPRi is a reliable and scalable approach to interrogate gene networks in the diverse P. fluorescens group.

microbiology