Luminous squid

Soon after the hypothetical structure was published, coelenterazine was isolated as an actual substance from the liver of the luminous squid Watasenia scintillans, and it was chemically synthesized (Inoue et al., 1975). The availability of synthetic coelenterazine led to the important discovery that the treatment of the luminescence product of aequorin with coelenterazine results in the regeneration of active aequorin (Shimomura and Johnson, 1975c), which consequently confirmed the presence of a coelenterazine moiety in the aequorin molecule. During the same period, it became increasingly evident that coelenterazine is involved as a luciferin in various bioluminescent organisms, such as the sea cactus Cavernularia, the sea pen Ptilosarcus, and the sea pansy Renilla (Shimomura and Johnson, 1975b). 

There are many kinds of bioluminescent squids. Some of them harbor luminous bacteria for their light emission (Harvey, 1952 Haneda, 1985), but all other luminous squids currently known utilize coelenterazine or its derivatives in their bioluminescence systems, and... 

Takahashi, H., and Isobe, M. (1993). Symplectoteuthis bioluminescence. (1). Structure and binding form of chromophore in photoprotein of a luminous squid. Bioorg. Med. Chem. Lett. 3 2647-2652. 

Takahashi H, Isobe M. Photoprotein of luminous squid, Symplectoteuthis oualaniensis and reconstruction of the luminous system. Chem Lett 1994 843-... 

STUDY ON ATP-DEPENDENT LUMINESCENCE REACTION OF THE ARM LIGHT ORGANS OF THE LUMINOUS SQUID WA TASEN1A SCINTILLANS... 

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). 

In Mollusca, bioluminescence occurs in a great variety of organisms having distinctly different appearances, such as the classes Gastropoda (limpets, snails and sea hares), Bivalvia (clams), and Cephalopoda (squids and octopuses). All luminous molluscs currently known are marine organisms, except the New Zealand fresh water limpet Latia neritoides and the Malaysian land snail Quantula (Dyakia) striata. No information is yet available on the biochemical aspects of the Quantula luminescence. 

The luminous Flying Squid Symplectoteuthis luminosa (Suji-ika)... 

Fig. 6.3.10 The luminous flying squid Symplectoteuthis (Eucleoteuthis) luminosa (photo by Dr. Satoshi Inouye).

Bioluminescence is the production of light by living systems. The best-known example of this phenomenon is the characteristic glow of the firefly, but other luminous species include bacteria, fungi and other animals such as jellyfish, scale-worms, deep-sea squid, prawn and fish. In animals bioluminescence is used as a diversionary tactic when disturbed, to attract prey and of course as a mating signal during courtship. 

Watas6 S. The luminous organ of the firefly squid. Dobutsugaku Zasshi 1905 17 119-23. 

In contrast to the bacterial-squid story, little is known about the horizontal transfer of luminous symbionts in bacteria-fish symbioses. Recently, however, we successfully raised Leiognathus nuchalis, pony fish juveniles, and infected them with symbiotic Photobacterium leiognathi. Juvenile L nuchalis raised separately from adults are apo-symbiotic and therefore not luminous. When the juveniles were kept with adults, a significant number became infected and luminescent. These results strongly support, the horizontal transfer of expelled P. leiognathi. 

For bioluminescent symbiotic fish and squid, expulsion of luminous bacteria into surrounding SW is a fundamental process that ensures horizontal transfer of the bacterial partner to future host generations. Considering the sophisticated coordination of various shutter mechanisms surrounding the internal LO of leiognathids, we believe the expulsion event to be a finely controlled discharge of symbiotic bacteria, rather than an uncontrolled phenomenon. 

Luminous bacteria are bioluminescent microorganisms whose luciferase genes (lux), proteins and intact cells are widely used in applied research and commercial products. Acknowledging the commercial value of luminescent cells also in entertainment and education, we have conducted research on luminous bacteria from marine samples and have isolated Photobacterium phosphoreum (strain RL-1) from coastal marine sediment. In order to maximize the luminescence activity of RL-1, we examined a series of extracts prepared from dried marine foodstuff. Because chitinous compounds and some amino acids are known to be abundant in dried squid and shrimp, we also tested the effects of those compounds on the luminescence activity. Among the supplemental compounds tested, chitosan, cysteine, and aspartic acid were found to enhance the luminescence activity of RL-1. The present results indicate that some amino acids and chitinous compounds are effective supplements for further enhancing bacterial light production in an enriched medium (SWC ). 

Quorum sensing may be useful for symbiotic associations, and especially for bioluminescent fish and ceph-alopods. The Hawaiian squid Euprymna sco/opcs hosts the luminous bacteria Vibrio fisheri in its light organs, and uses quorum sensing to bioluminescence at high cell densities with 3-oxo-C6-HSL as autoinducer (Ruby and Lee, 1998). 

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