FAU Institutional Repository http://purl.fcla.edu/fau/fauir This paper was submitted by the faculty of FAU’s Harbor Branch Oceanographic Institute. Notice: © 2001 McGraw-Hill. This manuscript is an author version with the final publication available and may be cited as: Widder, E. A. (2001). Bioluminescence. In McGraw-Hill yearbook of science & technology 2001 (pp. 52-55). New York: McGraw-Hill. McGRAW-HILL YEAitBOOK OF ctence• Techiiology 2001 Comprehensive coverage of recent events and research as compiled by the staff of the McGraw-Hill Encyclopedia of Science & Technology McGraw-Hill New York San Francisco Washington, D.C. Auckland Bogota Caracas Lisbon London Madrid Mexico City Milan Montreal New Delhi San Juan Singapore Sydney Tokyo Toronto 52 Bioluminescence top view based studies, and microscopy, scientists are poised to greatly increase the understanding of how microbes live attached to a surface. For backgronnd information see ANITBIOTIC RESIS­ TANCE; BACTERIAL GENETICS; BIOfllM; FUNGI; MEOI­ CAL BACTERIOLOGY in the McGraw-Hill Eng-dope­ dia of Science & Technology. George O'Toole Bibliography. ]. W. Costerton et al., Microbial bio­ films,Annu. Rev.Microbiol,49:711-745, 1995; D. G. Davies et al., The involvement of cell-to-cell signals in the development of a bacterial biofilm, Sdence, 280(5361):295-298, 1998; M. Givskovetal., Eukary­ otic interference with homoserine lactone-mediated prokaryotic signalling, J Bacterial., 178(22):6618- side view 6622, 1996; A. T Henrici, Studies of freshwater bac­ teria, L A direct microscopic technique, j Bacte­ rial., pp. 277-287, 1933; P. E. Kolenbrander and]. London, Adhere today, here tomorrow: Oral bacterial (a) adherence.] Bacterial., 175(11):3247-3252, 1993; ]. R Lawrence et al., Optical sectioning of microbial biofilms, j Bacterial., 173(20):6558-6567, 1991; wild type mutant G. A. O'Toole et aL, Genetic approaches to the study of biofilms, Metb. Enzymol., 310:91- 109, 1999; G. A. O'Toole, H. Kaplan, and R Kolter, Biotilm formation as microbial development, Annu. Rev. Microbial., 54:49-79, 2000; G. A. O'Toole and R Kolter, Flagellar and twitching motility are neces­ sary for Pseudomonas aeruginosa biotilm develop­ ment, Mol. Microbial., 30(2):295-304, 1998; L S. Thomashow and D. M. Weller, Current concepts in (b) the use of introduced bacteria for biological disease control: Mechanisms and antifungal metabolites., in Fig. 3. Testing for biofilm formation. (a) 96-well dish. G. Stacey and N. Keen (eds.), Plant Microbe Interac­ (b) Wild type leaves a dark ring; mutant bacteria do not form a ring. tions, Chapman and Hall, New York, 1995. researchers that they are looking at an aspect of the bacterial lifestyle that is poorly understood or bas Bioluminescence not been studied in any detail at the level of the Bioluminescence, which is the ability of an organ­ gene. ism to emit ~ible light, is a common attribute of Future research. While understanding the biology marine creatures. The phenomenon is relatively rare of biofilm formation is an important endeavor, long­ on land, where fireflies are the best-known exam­ term goals also include devising new strategies for ple. In the oceans it is ubiquitous, and is found at controlling biofilm formation. Implant-based infec­ all depths. The most common sources in the ma­ tions are an increasing problem in clinical settings. rine environment are bacteria, dinoflagellates, jelly­ Recent studies also implicate biofilm formation in fish, crustaceans, cephalopods, and fish. Among infectious diseases, including the infections associ­ cephalopods, which indude squids, cuttlefish, and ated with cystic fibrosis. Biofilms can also lead to the octopods, the expression of bioluminescence is clogging of pipelines and contamination in industrial extremely diverse. Out of 100 genera of squids and processes. Another current area ofstudy is the search cuttlefish, 63 have been fonnd to include biolumi­ for new means to control the formation of biofilms. nescent spedes, but in octopods only 3 out of One class of recently discovered compounds that can 43 genera do. interfere with the formation of biofilms is the fura­ Evolution. Bioluminescence is produced when an nones. Furanones,i which are analogs of homoser­ enzyme, known as luciferase, catalyzes the oxidation ine lactones, were briginally isolated from a particu­ of a substrate, known as luciferin, by molecular oxy­ lar marine alga that was unusually free of microbial gen. Luciferase and luciferin are generic designations biotilms (most algae are covered with bacteria). The for any enzyme or substrate involved in a biolumi­ furanones appear to interfere with the development nescent reaction. Based on the number of different of the typical biofilm structure and apparently render chemistries and the variety ofexpress ions of biolumi­ these organisms more susceptible to treatment with nescence in different organisms, it appears that the natural biocides. Using bacterial genetics in conjnnc­ ability to produce light arose independently many tion with the newest molecular techniques, genome- different times in many different groups of animals. Bioluminescence 53 Titis remarkable degree of convergent evolution is a dear indication of the selective advantages afforded by light production. The prevalence of bioluminescence in the open ocean is believed to be a consequence of selection pressures imposed by the struggle to survive in an environment that lacks hiding places. There are no uees or bushes to hide behind in the vast expanses of the open ocean, constituting most of the living space on Earth. However, survival frequently depends on the ability to hide from predators. During evolution­ ary history, as the oceans filled up with ever swifter and more ferocious predators, many prey that could not outswim them found refuge in the dark depths. Among these were many that depended on vision and visual signals to attract mates, to lure prey, and to avoid predators. As these vision-dependent animals colonized the twilight depths of the ocean, natural selection favored those with enhanced \-isual sensi­ tivity and amplified visual signals. Bioluminescence is one way to enhance a visual signal in an environment with little light. For exam­ ple, the ink used by a squid or an octopus to distract or confuse a predator has little or no visual impact Fig. 1. Location of bioluminescence (indicated in color) in ~ dark depths. However, releasing bioluminescent the octopus Japetella diaphana. (Redrawn from P. J. ·chemicals directly into the water serves as a highly Herring, Luminescent organs, in E. R. Trueman and M. R. ef(ective distraction, and is a common trick of many Clarke, eds., The Mollusca, vol. II, Academic Press, New Yorlc) deep-ocean dwellers, including some shrimp, jelly­ fish, squid, and fish. Similarly, visual signals such as lures used to attract prey or body parts displayed Differences in light organ distribution between to attract a mate, are made visible by biolumines­ males and females, which are usually taken as ev­ cence. Many animals also have bioluntioescem head­ idence that they function in sexual signaling, are lamps that they can use to help them see in the rare in squid and cuttlefish. However, in two of dark. Bioluminescence can also function as camou­ the tltree genera of octopods with luminescent spe­ flage. In the depths between 200 and 1000 m (660 cies, the bolitaenids Japetella and EledoneUa, light and 3300 ft), sunlight filtering down tltrough sur­ organs take the unusual form of a ring around the face waters creates a dim background light when mouths of breeding females (Fig. 1). The fact that viewed from below. Against this background, the sil­ these light organs occur only in breeding females houette of an opaque animal is an easy target for and actually disappear following spawning pro­ an upward-looking visual predat01: Many fish, squid, vides sound evidence that they function in sexual and shrimp camouflage their silhouettes by pro­ signaling. ducing downward-directed bioluminescence that The only other confirmed case of bioluminescence exactly matches the color, intensity, and angular dis­ among octopods is in the deep-sea cirrate (finned) tribution of the background light field. octopus Stauroteuthis syrumsis (Fig. 2). Although Ught organs. light organs in cephalopods run the this octopus was first described in 1879, it was not gamut from simple patches of light-producing tissue until 1999, when a live specimen was collected to elaborate light organs known as pbotophores that using a midwater submersible, that it was discovered contain complex optical elements such as lenses, fil­ to be bioluminescent. When this specimen, which ters, irises, reflectors, and shutters. Although there was collecte d from 755 m (2490 ft) in the Gulf of is little direct evidence for the functions served by l'rlaine, was placed in a shipboard aquarium, re­ these light organs, their anatomical locations often searchers were surprised to note that its "suckers• provide some hint as to their purpose. For example, did not stick to anything, and moreover that these in many otherwise transparent squid, phptophores suckers were capable of emitting blue light may occur beneath pigmented structures s1Jch as the (Fig. 3). l eyes or liver, and it is thought that luminescence An investigation of the anatomy and ultrastructure serves to eliminate the shadows that these opaque or­ of the suckers-photophores revealed that although gans would cast. Similarly, many opaque squid have these organs still had sucke.rlike traits, light­ photophores arrayed over most of the underside of producing cells replaced many of the muscles that their bodies, and these too can provide camouflage. are prominent features of normal suckers. In effect, Ught organs are also found on arms and tentacles, they appear to be light organs that have evolved perhaps serving as sexual signals or lures to attract from suckers. Because there is no fossil record prey. of bioluminescence, the evolutionary history of 54 Bioluminescence be assumed that under such circumstances biolu­ minescence function defen ively, sen·ing either to startle a p redator or to auract larger secondary pre­ dators that may prey on the primary predaror.