Murine glial protrusion transcripts predict localized Drosophila glial mRNAs involved in plasticity

The polarization of cells often involves the transport of specific mRNAs and their localized translation in distal projections. Neurons and glia are both known to contain long cytoplasmic processes, while localized transcripts have only been studied extensively in neurons, not glia, especially in intact nervous systems. Here, we predict 1,740 localized Drosophila glial transcripts by extrapolating from our meta-analysis of seven existing studies characterizing the localized transcriptomes and translatomes of synaptically associated mammalian glia. We demonstrate that the localization of mRNAs in mammalian glial projections strongly predicts the localization of their high-confidence Drosophila homologs in larval motor neuron-associated glial projections and are highly statistically enriched for genes associated with neurological diseases. We further show that some of these localized glial transcripts are specifically required in glia for structural plasticity at the nearby neuromuscular junction synapses. We conclude that peripheral glial mRNA localization is a common and conserved phenomenon and propose that it is likely to be functionally important in disease.

Optimization of hybridization chain reaction for imaging single RNA molecules in Drosophila larvae

In situ hybridization techniques are powerful methods for exploring gene expression in a wide range of biological contexts, providing spatial information that is most often lost in traditional biochemical techniques. However, many in situ hybridization methods are costly and time-inefficient, particularly for screening-based projects that follow on from single-cell RNA sequencing data, which rely on of tens of custom-synthetized probes against each specific RNA of interest. Here we provide an optimized pipeline for Hybridization Chain Reaction (HCR)-based RNA visualization, including an open-source code for optimized probe design. Our method achieves high specificity and sensitivity with the option of multiplexing using only five pairs of probes, which greatly lowers the cost and time of the experiment. These features of our HCR protocol are particularly useful and convenient for projects involving screening several genes at medium throughput, especially as the method include an amplification step, which makes the signal readily visible at low magnification imaging.