The Magic of Insects Disguising as Leaves: The Impact of the New Protein "DBXN" Coloring Green Katydids

1. Is the Green Body a Coincidence or Necessity?—Challenging a Long-standing Mystery

As you sit down on the grassland and gaze at the swaying pampas grass, you notice a grasshopper clinging gently to its stem. Its green tone matches the leaves, with semi-transparent wing veins and a slightly brown-tinged back—this perfect camouflage has deceived predators and even researchers. There was an old myth that insect body color "dyes" by eating chlorophyll, but it was the hypothesis that **"there might be a mechanism to 'create' green within the body"** that led to this discovery. ja.wikipedia.org

2. What is the New Protein "Dibilinoxanthinin (DBXN)"?

The research team purified a water-soluble green protein from the epidermis of *T. cantans*. Mass spectrometry and de novo sequencing revealed it to be a roughly 80 kDa irregular trimer , with each subunit originally being a fragment of the egg yolk protein vitellogenin. It features a "dichromatic pocket" containing yellow pigment lutein ×2, blue bilin ×2, and phospholipids ×4, and the crystal structure analysis (PDB: 9KUE) identified the pigment positions at a resolution of 1.99 Å. ncbi.nlm.nih.govpubmed.ncbi.nlm.nih.gov

3. Behind the Discovery—International Team and Japanese Researchers

The lead author of the paper is Peter Schwarz from the University of Göttingen, Germany. The collaboration involved Uppsala University in Sweden, the Czech University of Life Sciences, and Tohoku University's Graduate School of Science (Structural Biology Group) in Japan, with the beamline BL41XU at SPring-8 used for crystal analysis. Associate Professor Saki Sato, a Japanese co-researcher, stated in a press release, "I had an intuition that there was a 'green protein' in the insect world comparable to GFP, and my 10-year pursuit of this dream has come true." phys.org

4. The "Symphony of Mimicry" Played by Molecules

The key to DBXN producing green is **"additive color mixing"**. The wavelength range perceived as "green" by humans is approximately 500–560 nm. A narrowband reflection spectrum is achieved by overlapping absorption and scattering of yellow (around 560 nm) and blue (around 480 nm), peaking near the middle. This "pigment capsule" approach is different from the biliverdin-binding proteins in frogs or the prism structures in butterflies. pnas.org

5. Perspectives from Japanese Experts

• Shinya Morikawa (Kyoto University, Insect Morphology): "In contrast to the melanin system that mantises use to switch between green and brown, T. cantans maintains its color into adulthood. The evolutionary idea of reusing egg yolk proteins is fascinating."

• Yoshiko Fujita (Tokyo Institute of Technology, Catalytic Chemistry): "The concept of a protein 'embracing' an organic pigment that is stably colored at room temperature and insoluble in both water and oil could be applied to the design of new organic EL dispersions."

6. Application Potential—from Sustainable Materials to Biosensors

1. Natural Green Ink: "Chlorophyll fades quickly, but DBXN enhances the stability of lutein and bilin, maintaining 90% absorbance even after light exposure."

2. Biomarkers for Environmental Monitoring: The emission peak is shifted more towards the red side compared to GFP, making it easier to separate from background fluorescence within plant tissues.

3. Responsive Cosmetics: The pigment coordination shifts with temperature changes, allowing reversible transitions from pale turquoise to deep green.

7. Buzz on Social Media

Shortly after the research was published, the official X account of the American chemical magazine C&EN posted, "This insect uses a protein to go green." The Japanese science community spread it with the hashtag #昆虫発色, and

comments like "Is GBP (Grasshopper Green Protein) next after GFP?"
and "It's an era where not only the nutrition of edible insects but also their pigments are in the spotlight"
recorded thousands of impressions. From the research community, there were practical perspectives such as "It seems possible to create a 'biologically derived DIC camera filter.'" x.com

8. The Marvel of Evolution Seen in Comparison with the GFP Family

Jellyfish-derived GFP self-generates a chromophore within a β-barrel, while DBXN is a subunit assembly that transports and fixes external pigments. The contrasting strategies of **"self-fluorescence" versus "bundling external fluorescence" demonstrate that there is more than one way to acquire color. Furthermore, genetic phylogenetic analysis suggests the process of vitellogenin fragments undergoing **"shearing→condensation→functional transformation,"** offering a glimpse into evolutionary ingenuity. pubmed.ncbi.nlm.nih.gov