Luminous organisms

The elaterid Pyrophorus is of special importance in the history of bioluminescence, because it was used by Dubois in his first demonstration of the luciferin-luciferase reaction in 1885. The Jamaican click beetle (Pyrophorus noctilucus) is commonly found in the West Indies. The beetle possesses two kinds of luminous organs. A... 

Distribution of luminous bacteria. Luminous bacteria are widely distributed in the marine environment, and have been isolated from various sources, including seawater, the light organs and various other parts of marine luminous organisms, sometimes even from nonmarine sources as well. There are several major groups of luminous bacteria... 

The existence of coelenterazine in various nonluminous organisms suggests that some of the coelenterazine-dependent luminous organisms might obtain coelenterazine from their food, either as the sole source of this substance or as a supplement to the coelenterazine biosynthesized in the body. In the case of the hydrozoan Aequorea aequorea, it was reported that the medusa is unable to produce its own coelenterazine and is dependent on a dietary supply of this compound for its capability of bioluminescence (Haddock et al., 2001). The organisms that biosynthesize coelenterazine remain to be identified, but it seems to be a common opinion at present that at least copepods do make their own coelenterazine. According to Thomson etal. (1995), the shrimp Systellaspis debilis is capable of coelenterazine... 

The enol-sulfate form (I), which is the precursor of the luciferin in the bioluminescence system of the sea pansy Renilla (Hori et al., 1972), can be readily converted into coelenterazine by acid hydrolysis. The enol-sulfate (I), dehydrocoeienterazine (D) and the coelenterazine bound by the coelenterazine-binding proteins are important storage forms for preserving unstable coelenterazine in the bodies of luminous organisms. The disulfate form of coelenterazine (not shown in Fig. 5.5) is the luciferin in the firefly squid Watasenia (Section 6.3.1). An enol-ether form of coelenterazine bound with glucopyra-nosiduronic acid has been found in the liver of the myctophid fish Diapbus elucens (Inoue et al., 1987). 

There are many kinds of luminous organisms that utilize coelenterazine as their luciferin. These organisms possess luciferases to catalyze the luminescent oxidation of coelenterazine. Coelenterazine luciferases have been isolated from about 10 kinds of organisms, including the anthozoans Renilla and Ptilosarcus, the scyphozoan... 

The New Zealand freshwater limpet Latia neritoides (Fig. 6.1.1) is the only known example of a freshwater luminous organism, with two possible exceptions certain species of luminous bacteria and the larvae of certain species of fireflies. The limpet inhabits shallow clear streams in the North Island of New Zealand, clinging to stones and rocks. Latia has a small oval-shaped shell (6-8 mm long), and secretes a luminous mucus that emits a greenish glow around the body only when disturbed the limpet does not show a spontaneous luminescence. The luminescence of Latia was first reported by Suter (1890) and further details including a positive luciferin-luciferase reaction were described by Bowden (1950). Both the luciferin and the luciferase have... 

Fig. 6.3.7 Luminescence spectrum of a homogenate of the luminous organ of Symplectoteuthis oualaniensis in the presence of 0.5 M KC1 (from Tsuji and Leisman, 1981). A homogenate suspension (1 ml) and 1MKC1 (1 ml), both made with 50 mM Tris-HCl, pH 7.6, containing 1 mM dithioerythritol, were mixed and the spectrum was measured 6 min after mixing. Note that the luminescence of the photoprotein symplectin isolated from the luminous organs showed a maximum at 470—480 nm (Takahashi and Isobe, 1993, 1994).

The diverse group Protozoa consists of microscopic single-celled organisms. Of the various protozoan types, only Radiolaria and Dinoflagellata are known to contain luminous organisms (Harvey, 1952 Herring, 1978). 

Chemical studies on fish luminescence have been hampered by difficulties in obtaining specimens and the minute sizes of the luminous organs and photophores. Despite the setbacks, it might be possible to find out the basic nature of a luminescence reaction when coelenterazine (or Cypridina luciferin) is utilized in the luminescence. Once the basic nature of the luminescence reaction is found, then further details might become available by comparison with an organism having the same type of luminescence system. 

Sometimes an aqueous extract of a luminous organism is nonlu-minous although it contains all the components necessary for light emission. If that is due to the presence of various inhibitors that are extracted together with the luminescent substances, the extract will become luminous by merely diluting the extract with water or a buffer solution. A means of reversible inhibition will be needed to purify such a luminous extract. 

In some luminous organisms, luciferases and photoproteins exist in particulate forms that are insoluble in water or common buffer solutions, resembling membrane proteins. The protein is probably highly aggregated or bound to an insoluble material thus, the protein... 

Raw materials. Most luminous organisms can be stored at —70°C or below under aerobic conditions, or with dry ice, without a significant loss of luminescence activity for a period of several months or more, although a trial is always recommended. Even if a substance already extracted is unstable when stored with dry ice (like the luciferase of Cypridina and the luciferins of euphausiids and dinoflag-ellates), the same substance in the organisms before extraction can be safely stored at — 70° C or with dry ice. The material can also be stored with liquid nitrogen for added safety, but the quantity storable in a laboratory setup (e.g., Dewar flask) is limited. 

Haneda, Y. (1985). Luminous Organisms (Hakko Seibutsu) (in Japanese). Koseisha-koseikaku, Tokyo. 

Harvey, E. N. (1917). The chemistry of light production in luminous organisms. Publ. Carneg. Instn. 251 171-234. 

Herring, P. J. (1978b). A classification of luminous organisms. In Herring, P. J. (ed.), Bioluminescence in Action, pp. 461 476. Academic Press, London. 

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