Primers in 2022

Principal component analysis is a multivariate statistical method that reduces a large number of variables into fewer variables, called principal components. This Primer describes how the method can be used for data analysis, explaining the mathematical background, analytical workflows, how to interpret a biplot and variants of the method.

Hydrogels are used to mimic cells’ local environment, enabling the study of cellular responses to biochemical and mechanical cues. Here, Blache et al. discuss the challenges of creating hydrogels for mechanobiology studies and how they can be used to analyse cell behaviour in the context of mechanobiological processes and harnessed to create regenerative therapies.

Tandem mass spectrometry is increasingly utilized for clinical applications in laboratory medicine. In this Primer, Thomas et al. discuss experimental considerations and quality management for implementing clinical tandem mass spectrometry in the clinic with an overview of some key applications.

Organoids are cell-based in vitro models derived from stem cells, reconstituting the complex structure and function of the corresponding tissue. In this Primer, Zhao, Chen, Dowbaj, Sljukic, Bratlie, Lin et al. discuss the development of organoids and methods for controlling their cellular environment.

Magnetic nanomaterials can be used to transduce magnetic fields into biologically relevant signals. This Primer describes different magnetic transduction mechanisms, the design of nanotransducers and example applications for studying cell signalling and neuroscience.

Intravital microscopy (IVM) techniques are used to visualize intact and live tissues at the cellular and subcellular level. In this Primer, Scheele, Herrmann et al. discuss IVM in rodents, outlining challenges and opportunities for using the technique.

Imaging flow cytometry combines the high-event-rate nature of flow cytometry with single-cell image acquisition associated with microscopy. In this Primer, Rees et al. discuss the typical imaging flow instrumentation, the type of data acquired and how to analyse them.

Electrochemical water splitting using renewable electricity is a promising method for the sustainable production of hydrogen. This Primer overviews considerations, techniques and methods for water electrolysis and describes methods to improve rigour and reproducibility when analysing electrochemical data.

Holographic microscopy is based on collecting holograms, patterns of dark and light fringes, and analysing them to obtain information about the specimen’s properties. This Primer introduces in-line holographic microscopy, with a focus on three analysis methods: generative modelling, machine learning and hybrid approaches.

Optical coherence tomography can be used as a conventional microscope, ophthalmic scanner or endoscope. In this Primer, Bouma et al. outline the instrumentation and data processing in obtaining topological and internal microstructure information from samples in three dimensions.

The combination of single-cell RNA sequencing with metabolic RNA labelling enables a time-resolved view of transcriptional responses in individual cells. In this Primer, Erhard and Saliba et al. discuss metabolic labelling approaches and how to assess the temporal dynamics of transcriptional responses in different conditions.

Ocean biogeochemical models use coupled differential equations to describe the transformation of the ocean’s circulation, physical and biogeochemical properties under different conditions. This Primer introduces the process of model construction and explains the characteristics of various model types, from simple to complex, alongside their advantages and disadvantages.

In-depth interviews are a versatile form of qualitative data collection used by researchers across the social sciences. In this Primer, Knott et al. describe the stages and challenges involved in designing and conducting interviews, how to analyse the data and strategies to overcome challenges.

Electrochemical methods of CO₂ separation offer potentially cheap, low-energy, scalable carbon capture technologies. In this Primer, Diederichsen et al. provide an overview of the experimentation and analysis needed for the study of electrochemical methods for CO₂ separation.

Two-photon calcium imaging is a technique used for recording neuronal activity in the brain. In this Primer, Grienberger et al. outline the experimental design and execution of two-photon calcium imaging, providing examples of ideal preparations and how data are analysed.

Contributory citizen science is a method in which non-professional participants contribute to data collection in whole or in part to advance scientific research. This Primer outlines the use of citizen science in the environmental and ecological sciences, discussing participant engagement, data quality assurance and bias correction.

Trace quantities of metal cations, inorganic anions, organic compounds and biomolecules can be measured using electrochemical stripping analysis (ESA). This Primer describes the principles of ESA, including methods of performing the pre-concentration and stripping steps, instrumentation and technique optimization.

Serial femtosecond crystallography is a high-throughput, serial crystallography technique for studying macromolecular crystals at an X-ray free-electron laser. This Primer gives an overview of microcrystallization methods, sample delivery and data analysis for applications including membrane proteins, radiation damage-prone systems and time-resolved experiments.

Van der Waals epitaxy provides numerous opportunities for materials integration in heterostructures. This Primer provides an overview of methodologies for producing van der Waals heterostructures, focusing on top-down assembly and bottom-up synthesis, and discusses future opportunities for their continued development.

Optogenetic techniques involve the introduction of photoreceptors into selected cells to allow control over their activity using light. In this Primer, Emiliani et al. discuss the most commonly used optogenetic tools, illumination approaches and applications in medicine, cardiovascular science and plants, among many other uses.