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Autophagy (Greek for “self-eating”) is a process by which cytoplasmic material, including organelles, are targeted to lysosomes for degradation. Autophagy is a dynamic process which involves autophagosome synthesis, delivery of materials to be degraded to the lysosome, and degradation of autophagic substrates inside the lysosome. Historically, methods for studying autophagy focused on counting the number of autophagosomes. This approach, however, has inherent limitations because it turns a dynamic process into a static measurement and it provides limited information about what materials or organelles are being targeted for autophagy. The development of several fluorescent autophagy reporters now allows for the measurement of autophagic flux, or the changes in autophagic activity, and are a more reliable indicator of autophagic activity. The aim of this post is to provide an overview of four autophagy biosensors currently available from Addgene.

Kinases: they regulate many proteins, with ~1/3 of human proteins predicted to be phosphorylated on at least one site. Phosphorylation is particularly important for regulating signal transduction and measuring kinase activity at the single-cell level can aid in drawing connections between signaling activity and cell phenotype. One method for monitoring live single-cell kinase activity is FRET, but FRET reporters are challenging to design and difficult to multiplex. The Covert Lab provides an alternative tool with their Kinase Translocation Reporters (KTRs) whose cellular localization serves as a proxy measurement of kinase activity. The key advantage of KTRs is that they are easy to create and simple to multiplex.

Addgenie Mary Gearing contributed to the content of this article.

Biosensors (‘biological sensors’) are biological tools that monitor a process or detect a given molecule. The sensor component is usually a protein that undergoes a conformational change in response to the molecule it detects. This change then generates a reporter signal. Reporter signals may be electrochemical or light-based, with luminescent and fluorescent reporters being especially popular. We’ll give you an introduction to fluorescent biosensors, but keep in mind that there is a lot of variety in how biosensors work, and you should always check the associated publication for the specifics of your chosen plasmid.

Rosella is a pH-sensitive fluorescent biosensor that was recently deposited with Addgene by Dr. Mark Prescott. This system was developed for monitoring and analyzing autophagy of cytosol and organelles in yeast cells. Autophagy (Greek for “self-eating”) is induced by a lack of nutrients and targets cytosol and organelles to the vacuole/lysosome for degradation and recycling. The key to Rosella’s autophagy-sensing abilities is that its fluorescence emission spectra changes when it goes from a more neutral pH compartment, ­­like the cytosol, to the higher pH of the vacuole. Read on to learn more about prior methods for studying autophagy and how Rosella improves upon them.

Epigenetics has recently been hitting the headlines, with sotires like the potential devastation of the palm oil industry through epigenetic effects on the Cover of Nature. So what is epigenetics and what tools are available to study it?