A rapid protocol for ribosome profiling of low input samples.

Ribosome profiling provides quantitative, comprehensive, and high-resolution snapshots of cellular translation by the high-throughput sequencing of short mRNA fragments that are protected by ribosomes from nucleolytic digestion. While the overall principle is simple, the workflow of ribosome profiling experiments is complex and challenging, and typically requires large amounts of sample, limiting its broad applicability. Here, we present a new protocol for ultra-rapid ribosome profiling from low-input samples. It features a robust strategy for sequencing library preparation within one day that employs solid phase purification of reaction intermediates, allowing to reduce the input to as little as 0.1 pmol of ∼30 nt RNA fragments. Hence, it is particularly suited for the analyses of small samples or targeted ribosome profiling. Its high sensitivity and its ease of implementation will foster the generation of higher quality data from small samples, which opens new opportunities in applying ribosome profiling.

Ribosome Profiling in the Model Diatom Thalassiosira pseudonana.

Diatoms are an important group of eukaryotic microalgae, which play key roles in marine biochemical cycling and possess significant biotechnological potential. Despite the importance of diatoms, their regulatory mechanisms of protein synthesis at the translational level remain largely unexplored. Here, we describe the detailed development of a ribosome profiling protocol to study translation in the model diatom Thalassiosira pseudonana, which can easily be adopted for other diatom species. To isolate and sequence ribosome-protected mRNA, total RNA was digested, and the ribosome-protected fragments were obtained by a combination of sucrose-cushion ultracentrifugation and polyacrylamide gel electrophoresis for size selection. To minimize rRNA contamination, a subtractive hybridization step using biotinylated oligos was employed. Subsequently, fragments were converted into sequencing libraries, enabling the global quantification and analysis of changes in protein synthesis in diatoms. The development of this novel ribosome profiling protocol represents a major expansion of the molecular toolbox available for diatoms and therefore has the potential to advance our understanding of the translational regulation in this important group of phytoplankton. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC. Basic Protocol: Ribosome profiling in Thalassiosira pseudonana Alternate Protocol: Ribosome profiling protocol for diatoms using sucrose gradient fractionation.