Fish ‘steal’ proteins from their prey to light themselves in the dark sciences

A recent study published in the journal “Nature” and conducted by a Japanese research team documented a type of theft that occurs in the luminous fish “Barbaricanthus ransoniti.” These fish do not produce their own luminous particles, due to the absence of the gene responsible for the formation of the luciferase enzyme responsible for bioluminescence, but rather steal them from their prey that they feed on. This rare biological phenomenon is known as “protein theft.”

This type of luminous fish, about 7 cm long, lives on the Pacific coast, where these fish move in flocks estimated at thousands. They are also ornamental fish that are displayed in home aquariums.

Special enzymes

In a special statement to Al Jazeera Net, lead researcher Manabu Bisho from Japan’s Tohoku University says that the metabolic and physiological functions of living organisms are usually regulated by enzymes and proteins encoded in their genomes.

He added: “However, the phenomenon of biological theft is a rare and interesting exception to this rule. It is a biological phenomenon in which an organism steals and uses functional units or components directly from its prey. Instead of digesting these components, the predator integrates them into its body to expand the range of its characteristics and acquire new abilities without needing the genes necessary to produce them.”

Barbariancanthus ransonetti uses a special form of this phenomenon. This fish feeds on bioluminescent ostracod crustaceans. The fish extracts a protein known as luciferase and stores it in its photosynthetic organs to emit light.

“In our recent study, we sequenced the complete, high-quality genome of this fish and demonstrated that it completely lacks the gene needed to produce the enzyme luciferase,” says Bishou. “This provides conclusive evidence that the fish relies entirely on a protein stolen from its prey to emit light.”

Other objects

Regarding the existence of other living organisms that can benefit from the components of their prey, Bisho says that there are other wonderful examples of the phenomenon of biological appropriation in nature. For example, aeolian nudibranchs isolate cnidarian organelles from their prey and store them in their appendages for use in self-defense.

Another famous example is the sacoglossan marine slug, which feeds on algae and retains its chloroplasts. These isolated chloroplasts remain functional for several months, allowing the animal to take advantage of photosynthesis for energy, a process known as plastid capture.

However, as Pecho explains, protein retention is only observed in this type of fish. He adds: “We seek to clarify the molecular mechanisms behind this unique phenomenon.”

Scientists are interested in understanding this mechanism very precisely, because this could contribute to developing a system for administering functional proteins such as antibody drugs or oral insulin.