Bioluminescence is the production of light, such as by the photophores of marine animals,[40] and the tails of glow-worms and fireflies. Bioluminescence, like other forms of metabolism, releases energy derived from the chemical energy of food. A pigment, luciferin is catalysed by the enzyme luciferase to react with oxygen, releasing light.[41] Comb jellies such as Euplokamis are bioluminescent, creating blue and green light, especially when stressed; when disturbed, they secrete an ink which luminesces in the same colours. Since comb jellies are not very sensitive to light, their bioluminescence is unlikely to be used to signal to other members of the same species (e.g. to attract mates or repel rivals); more likely, the light helps to distract predators or parasites.[42] Some species of squid have light-producing organs (photophores) scattered all over their undersides that create a sparkling glow. This provides counter-illumination camouflage, preventing the animal from appearing as a dark shape when seen from below.[43] Some angler fish of the deep sea, where it is too dark to hunt by sight, contain symbiotic bacteria in the 'bait' on their 'fishing rods'. These emit light to attract prey Luciferase is a generic term for the class of oxidative enzymes used in bioluminescence and is distinct from a photoprotein. The name is derived from Lucifer, the root of which means 'light-bearer' (lucem ferre). One example is the firefly luciferase (EC from the firefly Photinus pyralis.[1] "Firefly luciferase" as a laboratory reagent oftenrefers to P. pyralis luciferase although recombinant luciferases from several other species of fireflies are also commercially available. A variety of organisms regulate their light production using different luciferases in a variety of light-emitting reactions. The most famous are the fireflies,[2] although the enzyme exists in organisms as different as the Jack-O-Lantern mushroom (Omphalotus olearius) and many marine creatures. [edit]Firefly and click beetle luciferases The luciferases of fireflies - of which there are over 2000 species - and of the Elateroidea (fireflies, click beetles and relatives) in general - are diverse enough to be useful in molecular phylogeny. In fireflies, the oxygen required is supplied through a tube in the abdomen called the abdominal trachea. One well-studied luciferase is that of the Photinini firefly Photinus pyralis, which has an optimum pH of 7.8.[3] [edit]Sea Pansy luciferase Also well studied is the luciferase from Renilla reniformis. In this organism, the luciferase (Renilla-luciferin 2-monooxygenase)is closely associated with a luciferin-binding protein as well as a green fluorescent protein (GFP). Calcium triggers release of the luciferin (coelenterazine) from the luciferin binding protein. The substrate is then available for oxidation by the luciferase, where it is degraded to coelenteramide with a resultant release of energy. In the absence of GFP, this energy would be released as a photon of blue light (peak emission wavelength 482 nm). However, due to the closely associated GFP, the energy released by the luciferase is instead coupled through resonance energy transfer to the fluorophore of the GFP, Dinoflagellate luciferase is a multi-domain protein, consisting of an N-terminal domain, and three catalytic domains, each of which preceded by a helical bundle domain. The structure of the dinoflagellate luciferase catalytic domain has been solved.[6] The core part of the domain is a 10 stranded beta barrel that is structurally similar to lipocalins and FABP.[6] The N-terminal domain is conserved between dinoflagellate luciferase and luciferin binding proteins (LBPs). It has been suggested that this region may mediate an interaction between LBP and luciferase or their association with the vacuolar membrane.[7] The helical bundle domain has a three helix bundle structure that holds four important histidines that are thought to play a role in the pH regulation of the enzyme