麻豆淫院

From a distance, a green bush cricket (Tettigonia cantans) can easily be mistaken for a plant appendage, and that's exactly the point. Its leafy green hue allows it to blend seamlessly into its surroundings, camouflaging itself in meadows, marshes, and fields, the habitats it calls home. What makes the bush cricket green? It's a question that has sparked a debate in the scientific community for over a hundred years.

discovered that the secret to this camouflaging superpower comes from a water-soluble protein called dibilinoxanthinin (DBXN), which binds two distinct pigments鈥攁 blue bilin and a yellow lutein鈥攖o mimic the color of green foliage closely.

With the help of the genetic sequence of protein and cloning, the researchers found that the protein was a highly fragmented form of vitellogenin, a protein family essential for embryonic development.

The findings of this study are published in PNAS.

In the animal kingdom, green pigmentation is a popular disguise strategy that enables animals to blend into their green surroundings. Despite the common end goal, the molecular and evolutionary mechanisms responsible for this behavior are unique.

In some frogs, the bright green color and far-red fluorescence of the species that accumulate large amounts of the yellow bile pigment biliverdin in their skin bind with special soluble proteins belonging to the serpin family. For most species, however, the molecular underpinnings behind pigmentation are still poorly understood.

Studies from as early as the 1930s have established that the green pigment found in insects is made of yellow and blue components. The idea that the green color results from the appearance of blue chromoproteins on a yellow background has also been widely discussed.

To test this theory, the researchers collected over 100 specimens of bush crickets, then extracted and purified the green-colored protein from their green integuments鈥攁 tough outer protective layer.

The purified protein was then subjected to size-exclusion chromatography (SEC)鈥攁 separation technique that separates molecules based on their size鈥攚hich presented three main absorbance bands (~280 nm, ~470 nm, and ~660 nm) within a single protein peak, suggesting simultaneous binding of two different chromophores.

With the help of chromatographic separation of the green pigment, the researchers identified the yellow pigment as lutein and the blue chromophore as bilin, results that were further supported by absorbance spectrum analysis.

High-resolution crystal structure analysis revealed an ~80 kDa dichromophoric (dual-color bearing) protein, which the researchers named dibilinoxanthinin (DBXN). The structure includes a large hydrophobic cavity that binds two bilins, two luteins, and four phosphatidylcholine (lipids), all of which are stabilized by hydrogen bonds.

The researchers note that DBXN-like proteins were found in other green insects and even in a green spider, hinting at the convergent evolution of this camouflage mechanism.

They also believe that a better understanding of camouflage-related pigment-protein interactions could serve as inspiration for fabricating new materials for stealth technology or adaptive coloration.

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