Super-resolution microscopy of a novel marine fluorescent protein

The use of light to examine biological form and function has been a cornerstone of biomedical research for over 300 years. In the intervening period, biological advances have mirrored the development of new optical technologies increasing sensitivity, resolution and speed. Coupled with the ability to selectively label specific cellular molecules, with spectrally resolvable fluorophores, fluorescence optical microscopy provides the state-of-the-art non-invasive approach to probe intracellular function. However, despite numerous technological advances during this period, the ability of optical microscopes to distinguish adjacent objects, their resolving power was limited by the physical properties of the light itself. Recently with the advent of super-resolution microscopy, this barrier has been broken, permitting the observation and quantitation of cellular processes down to the single-molecule level.

Photoactivation localisation microscopy (PALM) allows the observation of single protein molecules (between 10,000 and 100,000 per cell) with an accuracy of the order of 10 nm. Although there has been proof of concept studies utilising two colour PALM, at present, this is only routinely achievable using photoactivatable proteins in the red part of the visible spectrum. This is primarily due to the absence of a photoactivatable green fluorescent protein with well-controlled switching behaviour and high levels of brightness. We have recently been studying a novel fluorescent protein that was first isolated from a marine comb jelly in the Pacific Ocean and exhibits some natural photoactivation. This talk will discuss some of the controversies surrounding its discovery, present some of the amazing properties of this protein and demonstrate its application in PALM microscopy.