Category Archives: Journal club

Sugar-coated RNA

A new pre-print from Caroline Bertozzi’s lab shows that some RNA molecules are glycosylated. At least some of these glyco-RNA molecules might reside inside the ER lumen.

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Local translation of ribosomal proteins in axons

A recent bioRxiv pre-print publication from Christine Holt’s lab suggests that ribosomes may be remodeled in axons by locally translated ribosomal proteins. This is surprising because we know that ribosomes are assembled in the nucleolus. Well, I have some concerns about a few of the experiments depicted there.

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Quantum dots for smFISH

Single molecule FISH is currently the best method to get accurate measurements of mRNA levels at single molecule, single cell level in cell culture or tissue slices with a spatial resolution of ~200 nanometer (or less). One of the drawbacks of this method is the deterioration of the fluorescent signal (bleaching) of the organic dyes that are used to label the probes. Andrew Smith’s lab from University of Illinois now show how FISH can work with quantum dots instead of organic dyes. This provides better fluorophore stability and also the possibility to have more colors with less overlap of the emission spectra.

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Single molecule peptide sequencing

One of the greatest breakthroughs of the past decade was the development of the next generation sequencing. Sequencing of DNA of course. It is relatively easy to sequence DNA  – the polymerase is doing it for you – simply add fluorescently labeled nucleotides. For RNA sequencing, we simply convert it into DNA. We now even have a method for in situ sequencing of RNA. But proteins pose a challenge. Now, maybe, this challenge can be overcome with a new-old method to sequence peptides.

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Re-Evaluating the Spherical-Nucleic-Acid (SmartFlare) Technology

I co-authored a Correspondence pre-print article that puts into question the Smartflare technology. SmartFlares (the commercial name of NanoFlares) are gold nanoparticles covered in  oligos specific to a certain mRNA of interest (aka spherical nucleic acids). Supposedly, cells internalize these particles and, once the mRNA hybridize to the oligo, a complementary fluorecently labeled oligo is being unquenched and “flares”, indicating the presence of said mRNA. In this post I want to briefly mention the main topics of our pre-print, and expand on some points. I encourage readers to comment here or on Pubpeer on our article.

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A molecular ribosome counting mechanism – where’s the data?

A recent paper in Nature from the lab of Pavel Baranov and collaborators suggests a new type of mechanism of translation regulation. However, After discussing this paper in a journal club today – I’m not convinced about their model. Continue reading

MS2 mRNA imaging in yeast – problem solved

Previously, on the story of MS2 labeling of mRNA in yeast: Roy Parker published a short letter to the editor, indicating that the MS2 system might cause accumulation of 3′ fragments. We wrote a response, showing that it is not always the case for endogenously expressed mRNAs, but it is exaggerated when over-expressed (Part 1)*. Later, Karsten Weis’s group confirmed Parker’s initial observation but their report still had some questions unanswered, and no solution to the problem; I was unhappy (Part 2).  Now, Evelina Tutucci and Maria Vera together with Jeet Biswas (all from Rob Singer’s lab) seem to have resolved the issue and solved the problem, with the development of the MBS version 6Continue reading