The Limpet Latia

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 

Purification of Latia luciferase and the purple protein. According to Shimomura and Johnson (1968c), frozen specimens of Latia (10 g) are vigorously shaken in 200 ml of cold 5mM sodium phosphate buffer (pH 6.8) for 15 minutes. Latia luciferase is extracted into the buffer and the solution becomes turbid. Four batches of such turbid solutions are combined and centrifuged, and the clear supernatant is 

Thirty-two years later, Ko jima etal. (2000a) purified Latia luciferase by the following steps ammonium sulfate fractionation, gel-filtration, affinity chromatography and Mono-Q anion-exchange FPLC. 

Assay of luciferin and luciferase. To assay luciferin, 1 ml of 5 mM phosphate buffer, pH 6.8, containing crude luciferase (which contains the purple protein) is added to 5—l0 xl of an ethanolic solution of luciferin, and the total light emitted is measured. To assay the activity of luciferase in crude material, 1 ml of 5 mM phosphate buffer, pH 6.8, containing a standard amount of luciferin is added to 5-10 xl of the sample, and the intensity of emitted light is measured. To assay purified luciferase, 1 ml of 5 mM phosphate buffer, pH 6.8, containing a standard amount of luciferin and a standard amount of purple protein is added to 5-10 xl of a sample, and the light intensity is measured (Shimomura and Johnson, 1968b,c). 

Properties of Latia luciferin. Latia luciferin is a highly hydrophobic, fat-soluble compound, and volatile under vacuum. It is a colorless liquid, with an absorption maximum at 207nm (s approx. 13,700 Fig. 6.1.2). The chemical structure of Latia luciferin has been determined to be 1 (C15H24O2), an enol formate of a terpene aldehyde 3 (Fig. 6.1.3 Shimomura and Johnson, 1968b). The enol formate group of Latia luciferin is unstable the luciferin is spontaneously hydrolyzed 

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A very different light-producing reaction is used by the limpet Latia. The luciferin is an unusual terpene derivative (Fig. 23-51) that lacks any chromophore suitable for light emission.678 Evidently oxidation of this luciferin causes electronic excitation of some other molecule, presumably a "purple protein" which is also needed for luminescence. A complex of luciferin plus the purple protein is believed to react with the luciferase (abbreviated E-NH2 in Fig. 23-51). It is... 

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. 

Fig. 6.1.1 The freshwater limpet Latia neritoides in day light (left) and in the dark (right).

Shimomura, O., Johnson, F. H., and Haneda, Y. (1966b). Isolation of the luciferin of the New Zealand fresh-water limpet, Latia neritoides Gray. In Johnson, F. H., and Haneda, Y. (eds.), Bioluminescence in Progress, pp. 391-404. Princeton University Press, Princeton, NJ. 

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