The Holy Grail of Fluorescent Proteins Sunday, June 24 Why do we travel across the world to study biofluorescence in marine creatures? While fluorescence in corals has been known since the invention of the ultraviolet lamp around the turn of the 20th century, the story of the study of this phenomenon began in the 1960s. This fluorescent phenomenon was first described scientifically in a jellyfish from the decidedly nontropical waters of the Puget Sound in Washington State. Jellyfish are cousins to corals and sea anemones. The fluorescence in this jellyfish comes from green fluorescent protein, or G.F.P. This protein became a biotechnology superstar in the 1990s as its DNA can be inserted into almost any organism, making that organism fluorescent. The utility of this technique lies in allowing biologists to observe the invisible inner workings of cells by making the otherwise transparent proteins visible with this fluorescent tag. The identification and exploitation of this method earned the involved scientists the 2008 Nobel Prize in Chemistry. Scientists found that introducing mutations into G.F.P. could produce proteins that fluoresce in other colors, like yellow or blue. However, the holy grail remained proteins that produce fluorescent light that is in the near infrared - light that is deep red and just on the edge of being visible to humans. This color has the advantage of being safer for living tissue, affords better penetration into tissue and has less interfering autofluorescence, allowing for the study of cells deeper within a living organism. Although many laboratories have made millions of mutants of G.F.P., they were unable to produce a red fluorescent protein. This changed with the discovery of a red fluorescent protein in coral-like animals, which opened the door to exploring for novel fluorescent proteins in phylum Cnidaria, including corals, jellyfish and anemones. But few exhaustive studies of reef corals have been conducted searching for the elusive near-infrared emitting fluorescent protein. That is in part what has brought us to the Solomon Islands, where nature's diversity still exceeds anything we can produce in the laboratory. To find creatures with these infrared properties, we have designed an underwater camera that is sensitive to this fluorescence at night. Because colors at the red end of the spectrum of light are lost the deeper you go into the ocean, we are searching in shallow water (above 130 feet) for creatures that fluoresce in the near-infrared range. The problem is that chlorophyll, the main energy molecule in autotrophs, produces a weak fluorescence in the near infrared. Coral reefs are full of chlorophyll, which we need to separate. To do this we also carry an underwater spectrophotometer that allows us to separate chlorophyll fluorescence from the ones we are seeking. When we find a glowing creature, we extract RNA from a small sample to isolate the fluorescent protein sequence. One of the exciting findings of this trip has been the widespread presence of fluorescence in a range of other reef inhabitants. Now the question is, are they G.F.P.-like or something completely new?