Vargulin Explained

Vargulin,^[1] also called Cypridinid luciferin,^[2] Cypridina luciferin, or Vargula luciferin, is the luciferin found in the ostracod Cypridina hilgendorfii, also named Vargula hilgendorfii.^[3] These bottom dwelling ostracods emit a light stream into water when disturbed presumably to deter predation. Vargulin is also used by the midshipman fish, Porichthys.

History

A partial extraction procedure was developed in 1935 which involved reacting the compound with benzoyl chloride to allow it to be separated from the water-soluble components.^[4] The compound was first isolated and purified to crystals by Osamu Shimomura.^[5] The structure of the compound was confirmed some years later.^[6] Feeding experiments suggest that the compound is synthesized in the animal from three amino-acids: tryptophan, isoleucine, and arginine.^[7]

Biochemistry

Vargulin is oxidized by the Vargula luciferase,^[8] a 62 kDa enzyme, to produce blue light at 462 nm (max emission, detected with a 425 to 525 nm filter). The vargulin does not cross react with luciferases using coelenterazine or Firefly luciferin.

Uses

Vargulin (with the associated luciferase) has applications in biotechnology:

• in a variety of assays, to report gene or gene expression after luciferase have been genetically introduced in cells,
• to detect ATP, that is used in the vargulin/luciferase reaction (cell viability assays).^[9]

Although less stable, the Cypridina system is useful because can be used in multiplex assays with other (red-emitting) luciferin assays.

Notes and References

1. Campbell . A. K. . Herring . P. J. . Imidazolopyrazine bioluminescence in copepods and other marine organisms . Marine Biology . Springer Science and Business Media LLC . 104 . 2 . 1990 . 0025-3162 . 10.1007/bf01313261 . 219–225. 1990MarBi.104..219C . 84250053 .
2. Morin . James G. . Based on a review of the data, use of the term 'cypridinid' solves the Cypridina/Vargula dilemma for naming the constituents of the luminescent system of ostracods in the family Cypridinidae . Luminescence . Wiley . 26 . 1 . 2011 . 1522-7235 . 10.1002/bio.1282 . 1–4. 19862683 .
3. Book: Shimomura, O. . 2006 . Bioluminescence: Chemical Principles and Methods . . 978-981-256-801-4.
4. Anderson, RS . Studies on Bioluminescence : II. the Partial Purification of Cypridina Luciferin.. The Journal of General Physiology. 19. 2 . 301–5 . 1935 . 19872927 . 10.1085/jgp.19.2.301 . 2141430.
5. Shimomura, O . Goto, T . Hirata, Y . Crystalline Cypridina Luciferin. Bulletin of the Chemical Society of Japan. 30. 8 . 929–933 . 1957 . 10.1246/bcsj.30.929. free. 10069/20882 .
6. Kishi Y, Goto . T, Hirata Y . Shiromura O . Johnson FH . Kishi Y . 1966 . Cypridina bioluminescence. I. Structure of Cypridina luciferin . Tetrahedron Lett. . 7 . 29 . 10.1016/S0040-4039(01)82806-9 . 3427 - 3436 .
7. Oba, Y . Kato, S . Ojika, M . Inouye, S . Biosynthesis of luciferin in the sea firefly, Cypridina hilgendorfii: l-tryptophan is a component in Cypridina luciferin . Tetrahedron Letters. 43. 12 . 2389–2392 . 2002 . 10.1016/S0040-4039(02)00257-5 .
8. Thompson EM, Nagata S, Tsuji FI . Cloning and expression of cDNA for the luciferase from the marine ostracod Vargula hilgendorfii . . 86 . 17 . 6567–71 . 1989 . 2771943 . 297885 . 10.1073/pnas.86.17.6567. 1989PNAS...86.6567T . free .
9. Web site: Luciferase Reporters . thermofisher.com.