Glowing Insights: Fluorescent Proteins Illuminate the Path to Discovery

During daylight, as you gaze at the blue sky, the stars that you see at night are still present, albeit invisible to the naked eye due to the overwhelming brightness of the sun. Just as a firefly gliding across a field remains unseen during the day but becomes visible at night with its flashes, or how proteins and bacteria within cells are invisible under normal conditions, the stars wait patiently for the cover of darkness to reveal their brilliance once again.

Bioluminescent beach which lights up due to the fluorescent bacteria and virus

The Radiant Charm of the First Fluorescent Protein

In the realm of scientific exploration, the development and utilization of fluorescent proteins represent a revolutionary breakthrough. From the pioneering green fluorescent protein discovered in the Aequorea Victoria jellyfish to the extensive palette of genetic variants spanning the visible light spectrum, these proteins have revolutionized biological research; they provide unprecedented insights into cellular dynamics. GFP’s ability to easily detect and measure emitted light has facilitated tracking protein localization and measuring gene transcription. Its discovery marked a groundbreaking moment in the deciphering of countless natural phenomena, significantly impacting scientific innovation in the last century.

Following the discovery of the green fluorescent jellyfish protein, a plethora of fluorescent proteins have emerged–both from natural sources and through laboratory creation. This expanded palette provides a spectrum of fluorescent colors, unveiling previously unseen biological structures and processes in vibrant brilliance. From reds to blues, these fluorescent hues illuminate the intricate world of life sciences, allowing researchers to visualize and study cellular phenomena with unprecedented clarity and detail.

The Fluorescent Protein Color Palette

The realm of fluorescent protein has undergone a vibrant evolution, boasting an extensive array of genetic variants with fluorescence emissions covering the entire visible light spectrum. Originating from mutagenesis endeavors in the Aequorea Victoria jellyfish, a spectrum of probes now spans from blue to yellow, establishing themselves as pivotal in vivo reporter molecules for biological research. Beyond this, the orange and red regions find representation in longer-wavelength fluorescent proteins, hailing from sources like the marine anemone, Disco soma striata, and Anthozoa reef corals. Species exploration continues, yielding proteins with cyan, green, yellow, orange, and deep red emissions. The developmental frontier persistently refines these proteins and strives to enhance brightness and stability, thereby augmenting their overall utility in scientific inquiry.

Flashing light on images

Fluorescent protein technology has revolutionized scientific imaging by enabling breakthroughs such as super-resolution microscopy (STED, PALM). Additionally, it has expanded optogenetics (a biological technique used to control the activity of neurons or other cell types with light), multi-color imaging, FRET-based biosensors, genetically encoded voltage indicators, and in vivo imaging advancements. These innovations, fueled by the radiant glow of fluorescent proteins, redefine precision in observing cellular processes. From fine structural details to real-time manipulation and tracking, these developments inspire continual exploration into the hidden realms of biology.

CaMPARI fluorescence in a larval zebrafish brain showing active neurons (magenta) that were marked while the fish was swimming freely.

Transparent and expanding the brain

Even with the help of fluorescent proteins it has been difficult to image neurons tangled in the deep end of the brain. Ed Boyden, a neuroscientist from MIT, has created a method to expand brains to make fluorescent neurons deeply entrenched in the brain more visible. He uses Acrylate (the salts, esters and conjugate bases of acrylic acids) , which forms a dense mesh to hold the brain in place and expands in the presence of water. Acrylate essentially inflates the brain equally by about 4.5 times in each direction–a lot like a diaper expanding when it gets wet.

Like stars at night, fluorescent proteins have been lighting up science for the last 20 years. And it won’t be long before they’re guiding surgeons to tumorous growths during surgery and allowing researchers to switch on and off selected biomolecular processes. This groundbreaking technique allows scientists to visualize and understand the dynamic and otherwise unseen workings of cellular machinery, bringing to light the hidden complexities of the microscopic world.

References

The STEAM Blog