Bioluminescence

Resources

Bioluminescence is the production of light by living organisms. Some single-celled organisms (bacteria and protista) as well as many multicellular animals and fungi demonstrate bioluminescence.

Marine environments support a number of bioluminescent organisms including species of bacteria, dinoflagellates, jellyfish, coral, shrimp, and fish. On any given night one can see the luminescent sparkle produced by the single-celled dinoflagellates when water is disturbed by a ship’s bow or a swimmer’s motions. Many multicellular marine organisms have specialized light emitting organs that project light in a particular direction or convey a unique shape to the light. The anglerfish has a light-emitting organ that projects from its head, which serves as a bait to attract smaller prey fish. The light emitted from this organ in the anglerfish is actually produced by bacteria, living in a symbiotic relationship in which both the fish and bacteria profit from their shared existence.

Bioluminescence that occurs in some species of marine bacteria may be related to the number of bacteria in a given unit of water (such as a milliliter or liter). Specifically, the luminescent reaction is triggered in the bacteria when the cells reach a critical density. Scientists who have studied this phenomenon think that this is related to the production of a chemical by the bacteria. As the bacterial density increases, more of the chemical is present. The formation of bioluminscence is triggered by a threshold concentration of the chemical. This involves the sensing of the chemical by the bacteria and communication between adjacent bacteria (the latter is termed quorum sensing).

Bioluminescent organisms in the terrestrial environment include species of fungi and insects. The most familiar of these is the firefly, which can often be seen glowing during the warm summer months. In some instances organisms use bioluminescence to communicate, such as in fireflies, which use light to attract members of the opposite sex. Certain reef fish use light produced from organs under their eyes to illuminate the interior of crevices and caves. This not only helps the fish to navigate, but also allows it to locate prey. Organisms that are unpalatable or dangerous, such as jellyfish, use bioluminescence as a signal to warn off attacks by predators. A newly-discovered deep sea octopus has bioluminescent organs in place of suckers.

Light is produced by most bioluminescent organisms when a chemical called luciferin reacts with oxygen to produce light and oxyluciferin. The reaction between luciferin and oxygen is catalyzed by the enzyme luciferase. Luciferases, like luciferins, usually have different chemical structures in different organisms.

In addition to luciferin, oxygen, and luciferase, other molecules (called cofactors) must be present for the bioluminescent reaction to proceed. Cofactors are molecules required by an enzyme (in this case

KEY TERMS

Antibody— A molecule created by the immune system in response to the presence of an antigen (a foreign substance or particle). It marks foreign microorganisms in the body for destruction by other immune cells.

Antigen— A molecule, usually a protein, that the body identifies as foreign and toward which it directs an immune response.

Assay— Method used to quantify a biological compound.

ATP— Adenosine triphosphate; a high energy molecule that cells use to drive energy-requiring processes such as biosynthesis, transport, growth, and movement.

Cofactor— Molecule required by an enzyme to perform its catalytic function.

Dinoflagellate— Chloroplast containing protists that primarily inhabit marine environments.

DNA— Deoxyribonucleic acid; the genetic material in a cell.

Enzyme— Biological molecule, usually a protein, which promotes a biochemical reaction but is not consumed by the reaction.

Extract— Solution from a biological material that contains an active compound.

Gene promoter— Regions of DNA that control gene activity.

Luciferase— An enzyme that catalyzes the reaction between oxygen and luciferin.

Luciferin— Complex carbon molecules that produce light when oxidized.

Oxidation— The process where a molecule loses one or more electrons.

Oxyluciferin— An oxidized luciferin molecule which is the product of a bioluminescent reaction.

Protista— Kingdom composed of single-celled organisms whose DNA is enclosed by a nucleus.

luciferase) to perform its catalytic function. Common cofactors required for bioluminescent reactions are calcium and ATP, a molecule used to store and release energy that is found in all organisms.

The terms luciferin and luciferase were first introduced in 1885. The German scientist Emil Du Bois-Reymond-Reymond obtained two different extracts from bioluminescent clams and beetles. When Du Bois-Reymond-Reymond mixed these extracts they produced light. He also found that if one of these extracts was first heated, no light would be produced upon mixing. Heating the other extract had no effect on the reaction, so Du Bois-Reymond concluded that there were at least two components to the reaction. Du Bois-Reymond hypothesized that the heat-resistant chemical undergoes a chemical change during the reaction, and called this compound luciferin. The heat sensitive chemical, Du Bois-Reymond concluded, was an enzyme which he called luciferase.

The two basic components needed to produce a bioluminescent reaction, luciferin and luciferase, can be isolated from the organisms that produce them. When they are mixed in the presence of oxygen and the appropriate cofactors, these components will produce light with intensity dependent on the quantity of luciferin and luciferase added as well as the oxygen and cofactor concentrations. Luciferases isolated from fireflies and other beetles are commonly used in research.

Scientists have used isolated luciferin and luciferase to determine the concentrations of important biological molecules such as ATP and calcium. After adding a known amount of luciferin and luciferase to a blood or tissuesample, the cofactor concentrations may be determined from the intensity of the light emitted. Scientists have also found numerous other uses for the bioluminescent reaction such as using it to quantify specific molecules that do not directly participate in the bioluminescence reaction. To do this, scientists attach luciferase to antibodies—molecules produced by the immune system that bind to specific molecules called antigens. The antibody-luciferase complex is added to a sample where it binds to the molecule to be quantified. Following washing to remove unbound antibodies, the molecule of interest can be quantified indirectly by adding luciferin and measuring the light emitted. Methods used to quantify particular compounds in biological samples such as the ones described here are called assays.

Luciferase is often used as a reporter gene to study how individual genes are activated to produce protein or repressed to stop producing protein. Most genes are turned on and off by DNA located in front of the part of the gene that codes for protein. This region is called the gene promoter. A specific gene promoter can be attached to the DNA that codes for firefly luciferase and introduced into an organism. The activity of the gene promoter can then be studied by measuring the bioluminescence produced in the luciferase reaction. Thus, the luciferase gene can be used to “report” the activity of a promoter for another gene.

In recent studies, luciferase has been used to study viral and bacterial infections in living animals and to detect bacterial contaminants in food. The luciferase reaction also is used to determine DNA sequences, the order of the four types of molecules that comprise DNA and code for proteins.

Resources

BOOKS

Pieribone, Vincent and David F. Gruber. Aglow in the Dark: The Revolutionary Science of Biofluorescence. Boston: Belknap Press, 2006.

Shimomura, Osamu. Bioluminescence: Chemical Principle and Methods. Singapore: World Scientific Publishing Company, 2006.

Stanley, Philip E., and Larry J. Kricka. Bioluminescence & Chemiluminescence: Progress & Current Applications. Singapore: World Scientific Publishing Company, 2002.

Steven MacKenzie

Bioluminescence

Bioluminescence is the emission of visible light by biological systems, which arises from enzyme-catalyzed chemical reactions. Bioluminescence can be distinguished from chemiluminescence in that it occurs in living organisms and requires an enzyme catalyst . These chemical-dependent emissions of light differ from fluorescence and phosphorescence, which involve the absorption of light by a compound followed by emission of light at a lower energy (higher wavelength) from the excited state of the molecule. The excited molecule produced during bioluminescence reactions, however, is

analogous to that produced during fluorescence, and consequently the luminescence emission spectrum can often be related to the fluorescence emission spectrum. It should also be noted that the processes of fluorescence and phosphorescence also occur in living organisms and should not be confused with bioluminescence.

Bioluminescence has been observed in many organisms and phyla throughout the terrestrial and aquatic worlds, with the majority of luminescent organisms being found in the ocean. Because of the ease with which light can be detected, recorded observations of bioluminescence extend back several thousand years. Both the ancient Chinese and the ancient Greeks recorded luminescence sightings. Aristotle, in the fourth century b.c.e., wrote that "some things, though they are not in their nature fire, nor any species of fire, yet seem to produce light."

Luminescent species are found among marine and terrestrial bacteria, annelids or segmented worms (e.g., fireworms), beetles (e.g., fireflies, click beetles, railroad worms), algae (e.g., dinoflagellates), crustaceans (e.g., shrimp, ostracod), mollusks (e.g., squid, clams, limpets), coelenterates (e.g., jellyfish, sea pansies, hydroids), bony fish (e.g., hatchet fish, flashlight fish, pony fish), and cartilaginous fish (e.g., sharks). Luminescent vertebrates (except for certain fish), mammals, higher plants, and viruses do not exist—except for those versions created by recombinant technology.

Most, if not all, bioluminescence reactions have oxygen as a common reactant and a conjugated system as part of one of the substrates—both needed to generate molecules in an excited state, leading to the emission of light in the visible region. However, the bioluminescence reactions in some organisms are quite different from those in other organisms, and consequently the enzymes catalyzing the reactions (luciferases) and the substrates (often but not always referred to as luciferins) are also quite

distinct. Four bioluminescence systems (fireflies, dinoflagellates, bacteria, and imidazolopyrazine-based e. g., coelenterates) have been studied in greatest detail, and their chemical reactions reflect both their differences and their common features.

Beetles/Fireflies

Luciferases from click beetles, fireflies, and railway worms catalyze the ATP-dependent decarboxylation of luciferin (Figure 1). An AMP derivative of luciferin is formed, which subsequently reacts with O₂. Cleavage of this dioxy derivative results in the emission of light characterized by wavelengths ranging from 550 nanometers (2.17 × 10⁻⁵ inches; green) to 630 nanometers (2.48 × 10⁻⁵ red, depending on the particular luciferase), and the release of CO₂. Fireflies generally emit in the yellow to green range, as part of a courtship process; click beetles emit green to orange light; whereas railway worms emit red light, with green light being emitted on movement.

Dinoflagellates

Much of the brightness that is observed on the surface of the oceans is due to the bioluminescence of certain species of dinoflagellates, or unicellular algae, and this bioluminescence accounts for many of the recorded observations that have described the apparent "phosphorescence" of the sea. Dinoflagellates are very sensitive to motion induced by ships or fish, and respond with rapid and brilliant flashes, thus causing the glow that is sometimes seen in the wake of a ship. The luciferin in these instances is a tetrapyrrole containing four five-member rings of one nitrogen and four carbons, and its oxidation , catalyzed by dinoflagellate luciferase, results in blue-green light centered at about 470 nanometers (1.85 × 10⁻⁵ inches; Figure 2).

Bacteria

Bacterial luciferase catalyzes the reaction of reduced flavin mononucleotide (FMNH₂) with O₂ to form a 4a-peroxyflavin derivative that reacts with a

long chain aldehyde leading to the emission of blue-green light (490 nanometers, or 1.93 × 10⁻⁵ inches) and the formation of riboflavin phosphate (FMN; the phosphorylated form of vitamin B₂), H₂O, and the corresponding fatty acid (Figure 3). Luminescent bacteria are found throughout the marine environment, living free, in symbiosis, or in the gut of marine organisms (including many fish and squid), as well as in the terrestrial environment as symbionts of nematodes.

The luciferins believed to be the most widespread among phyla living in the ocean have structures based on imidazolopyrazine, for example, coelenterazine, found in luminescent coelenterates contains imidazolopyrazine as its central bicyclic ring (Figure 4). The typical reaction involves the oxidation of the imidazolopyrazine ring with the emission of blue light (460–480 nanometers, or 1.81 × 10⁻⁵–1.89 × 10 ⁻⁵ inches), and proceeds according to a mechanism that is very similar to that of the oxidation of firefly luciferin. Among the most commonly studied imidazolopyrazine-utilizing organisms are species of Renilla (sea pansy) and Aequorea (jellyfish) both of which utilize coelenterazine. The luciferin of a crustacean (Cypridina or

Vargula ) also is an imidazolopyrazine-based compound related to coelenterazine. The luciferases of the luminescent species, however, vary widely. Recent evidence suggests that some, and possibly many, marine luminescent organisms (including the jellyfish) acquire luciferins via the ingestion of other luminescent organisms, which would account for the widespread distribution of imidazolopyrazine-based luciferins. Many luminescent species also have a binding protein that releases the luciferin upon Ca⁺⁺ uptake, while some have a fluorescence protein that absorbs and then emits light at a higher wavelength.

Although other luminescent systems have been studied (including those of the fireworm and the limpet, both of which use aldehydes as luciferins), bioluminescence remains somewhat mysterious. Elucidation of the chemical and biological bases for luminescence systems in other organisms should improve understanding of why the remarkable and beautiful phenomenon of bioluminescence appears in so many species.

see also Chemiluminescence.

Edward A. Meighen

Bibliography

Cormier, Milton J.; Lee, John; and Wampler, John E. (1975). "Bioluminescence: Recent Advances." Annual Review of Biochemistry 44:255–272.

Haddock, Steven H. D.; Rivers, Trevor J.; and Robinson, Bruce H. (2001). "Can Coelenterates Make Coelenterazine? Dietary Requirement for Luciferin in Cnidarian Bioluminescence." Proceedings National Academy Science 98:11,148–11,151.

Harvey, E. Newton (1952). Bioluminescence. New York: Academic Press.

Johnson, Frank H., and Shimomura, Osamu (1978). "Introduction to the Cypridina System." In Methods in Enzymology, Vol. LVII: Bioluminescence and Chemiluminescence, Section V. New York: Academic Press.

McElroy, William D., and Seliger, Howard H. (1962). "Biological Luminescence: A Remarkable Variety of Organisms from Bacteria to Fishes Shine by Their Own Light." Scientific American 207(6):76–91.

Meighen, Edward A. (1991). "Molecular Biology of Bacterial Bioluminescence." Microbiological Reviews 55:123–142.

Thomson, Catherine M.; Herring, P. J.; and Campbell, A. K. (1997). "The Widespread Occurrence and Tissue Distribution of the Imidazolopyrazine Luciferins." Journal of Bioluminescence and Chemiluminescence 12:87–91.

Wilson, Thérèse, and Hastings, J. Woodland. (1998). "Bioluminescence." Annual Review of Cell and Developmental Biology 14:197–230.

Bioluminescence

Bioluminescence is the production of light by living organisms. Some single-celled organisms (bacteria and protista ) as well as many multicellular animals and fungi demonstrate bioluminescence.

Bioluminescence in nature

Marine environments support a number of bioluminescent organisms including species of bacteria, dinoflagellates, jellyfish , coral, shrimp , and fish . On any given night one can see the luminescent sparkle produced by the single-celled dinoflagellates when water is disturbed by a ship's bow or a swimmer's motions. Many multicellular marine organisms have specialized light emitting organs that project light in a particular direction or convey a unique shape to the light. The anglerfish has a light-emitting organ that projects from its head, which serves as a bait to attract smaller prey fish. The light emitted from this organ in the anglerfish is actually produced by bacteria, living in a symbiotic relationship in which both the fish and bacteria profit from their shared existence.

Bioluminescent organisms in the terrestrial environment include species of fungi and insects . The most familiar of these is the firefly, which can often be seen glowing during the warm summer months. In some instances organisms use bioluminescence to communicate, such as in fireflies, which use light to attract members of the opposite sex. Certain reef fish use light produced from organs under their eyes to illuminate the interior of crevices and caves. This not only helps the fish to navigate, but also allows it to locate prey. Organisms that are unpalatable or dangerous, such as jellyfish, use bioluminescence as a signal to warn off attacks by predators. A newly-discovered deep sea octopus has bioluminescent organs in place of suckers.

Biochemical mechanism

Light is produced by most bioluminescent organisms when a chemical called luciferin reacts with oxygen to produce light and oxyluciferin. The reaction between luciferin and oxygen is catalyzed by the enzyme luciferase. Luciferases, like luciferins, usually have different chemical structures in different organisms.

In addition to luciferin, oxygen, and luciferase, other molecules (called cofactors) must be present for the bioluminescent reaction to proceed. Cofactors are molecules required by an enzyme (in this case luciferase) to perform its catalytic function. Common cofactors required for bioluminescent reactions are calcium and ATP, a molecule used to store and release energy that is found in all organisms.

The terms luciferin and luciferase were first introduced in 1885. The German scientist Emil Du Bois-Reymond obtained two different extracts from bioluminescent clams and beetles . When Du Bois mixed these extracts they produced light. He also found that if one of these extracts was first heated, no light would be produced upon mixing. Heating the other extract had no effect on the reaction, so Reymond concluded that there were at least two components to the reaction. Reymond hypothesized that the heat-resistant chemical undergoes a chemical change during the reaction, and called this compound luciferin. The heat sensitive chemical, Reymond concluded, was an enzyme which he called luciferase.

Bioluminescence as a research tool

The two basic components needed to produce a bioluminescent reaction, luciferin and luciferase, can be isolated from the organisms that produce them. When they are mixed in the presence of oxygen and the appropriate cofactors, these components will produce light with an intensity dependent on the quantity of luciferin and luciferase added as well as the oxygen and cofactor concentrations. Luciferases isolated from fireflies and other beetles are commonly used in research.

Scientists have used isolated luciferin and luciferase to determine the concentrations of important biological molecules such as ATP and calcium. After adding a known amount of luciferin and luciferase to a blood or tissue sample , the cofactor concentrations may be determined from the intensity of the light emitted. Scientists have also found numerous other uses for the bioluminescent reaction such as using it to quantify specific molecules that do not directly participate in the bioluminescence reaction. To do this, scientists attach luciferase to antibodies—molecules produced by the immune system that bind to specific molecules called antigens. The antibody-luciferase complex is added to a sample where it binds to the molecule to be quantified. Following washing to remove unbound antibodies, the molecule of interest can be quantified indirectly by adding luciferin and measuring the light emitted. Methods used to quantify particular compounds in biological samples such as the ones described here are called assays.

Luciferase is often used as a "reporter gene" to study how individual genes are activated to produce protein or repressed to stop producing protein. Most genes are turned on and off by DNA located in front of the part of the gene that codes for protein. This region is called the gene promoter. A specific gene promoter can be attached to the DNA that codes for firefly luciferase and introduced into an organism . The activity of the gene promoter can then be studied by measuring the bioluminescence produced in the luciferase reaction. Thus, the luciferase gene can be used to "report" the activity of a promoter for another gene.

In recent studies, luciferase has been used to study viral and bacterial infections in living animals and to detect bacterial contaminants in food. The luciferase reaction also is used to determine DNA sequences, the order of the four types of molecules that comprise DNA and code for proteins .

Resources

books

Herring, Peter, Anthony Campbell, Michael Whitfield, and Linda Maddock, eds. Light and Life in the Sea. Cambridge, England: Cambridge University Press, 1990.

Herring, Peter, ed. Bioluminescence in Action. New York: Academic Press, 1978.

Purves, William, Gordon Orians, and H. Heller. Life: The Science of Biology. 3rd ed. Sunderland, Massachusetts: Sinaur Associates, Inc., 1992.

Smith, D.C., and A.E. Douglas. The Biology of Symbiosis. Baltimore: Edward Arnold, 1987.

Steven MacKenzie

KEY TERMS

Antigen

—A molecule, usually a protein, that the body identifies as foreign and toward which it directs an immune response.

Assay

—Method used to quantify a biological compound.

ATP

—Adenosine triphosphate; a high energy molecule that cells use to drive energy-requiring processes such as biosynthesis, transport, growth, and movement.

Cofactor

—Molecule required by an enzyme to perform its catalytic function.

Dinoflagellate

—Chloroplast containing protists that primarily inhabit marine environments.

DNA

—Deoxyribonucleic acid; the genetic material in a cell.

Enzyme

—Biological molecule, usually a protein, which promotes a biochemical reaction but is not consumed by the reaction.

Extract

—Solution from a biological material that contains an active compound.

Gene promoter

—Regions of DNA that control gene activity.

Luciferase

—An enzyme that catalyzes the reaction between oxygen and luciferin.

Luciferin

—Complex carbon molecules that produce light when oxidized.

Oxidation

—The process where a molecule loses one or more electrons.

Oxyluciferin

—An oxidized luciferin molecule which is the product of a bioluminescent reaction.

Protista

—Kingdom composed of single-celled organisms whose DNA is enclosed by a nucleus.

Bioluminescence

Bioluminescence is the production of light by living organisms. Some single-celled organisms (bacteria and protista) as well as many multicellular animals and fungi demonstrate bioluminescence.

Light is produced by most bioluminescent organisms when a chemical called luciferin reacts with oxygen to produce light and oxyluciferin. The reaction between luciferin and oxygen is catalyzed by the enzyme luciferase. Luciferases, like luciferins, usually have different chemical structures in different organisms. In addition to luciferin, oxygen, and luciferase, other molecules (called cofactors) must be present for the bioluminescent reaction to proceed. Cofactors are molecules required by an enzyme (in this case luciferase) to perform its catalytic function. Common cofactors required for bioluminescent reactions are calcium and ATP, a molecule used to store and release energy that is found in all organisms.

The terms luciferin and luciferase were first introduced in 1885. The German scientist Emil du Bois-Reymond obtained two different extracts from bioluminescent clams and beetles. When Dubois mixed these extracts they produced light. He also found that if one of these extracts was first heated, no light would be produced upon mixing. Heating the other extract had no effect on the reaction, so Dubois concluded that there were at least two components to the reaction. Dubois hypothesized that the heat-resistant chemical undergoes a chemical change during the reaction, and called this compound luciferin. The heat sensitive chemical, Dubois concluded, was an enzyme which he called luciferase.

The two basic components needed to produce a bioluminescent reaction, luciferin and luciferase, can be isolated from the organisms that produce them. When they are mixed in the presence of oxygen and the appropriate cofactors, these components will produce light with an intensity dependent on the quantity of luciferin and luciferase added, as well as the oxygen and cofactor concentrations. Luciferases isolated from fireflies and other beetles are commonly used in research.

Scientists have used isolated luciferin and luciferase to determine the concentrations of important biological molecules such as ATP and calcium. After adding a known amount of luciferin and luciferase to a blood or tissue sample, the cofactor concentrations may be determined from the intensity of the light emitted. Scientists have also found numerous other uses for the bioluminescent reaction such as using it to quantify specific molecules that do not directly participate in the bioluminescence reaction. To do this, scientists attach luciferase to antibodies—molecules produced by the immune system that bind to specific molecules called antigens. The antibodyluciferase complex is added to a sample where it binds to the molecule to be quantified. Following washing to remove unbound antibodies, the molecule of interest can be quantified indirectly by adding luciferin and measuring the light emitted. Methods used to quantify particular compounds in biological samples such as the ones described here are called assays.

In recent studies, luciferase has been used to study viral and bacterial infections in living animals and to detect bacterial contaminants in food. The luciferase reaction also is used to determine DNA sequences, the order of the four types of molecules that comprise DNA and code for proteins.

Luciferase is often used as a "reporter gene" to study how individual genes are activated to produce protein or repressed to stop producing protein. Most genes are turned on and off by DNA located in front of the part of the gene that codes for protein. This region is called the gene promoter. A specific gene promoter can be attached to the DNA that codes for firefly luciferase and introduced into an organism. The activity of the gene promoter can then be studied by measuring the bioluminescence produced in the luciferase reaction. Thus, the luciferase gene can be used to "report" the activity of a promoter for another gene.

Bioluminescent organisms in the terrestrial environment include species of fungi and insects. The most familiar of these is the firefly, which can often be seen glowing during the warm summer months. In some instances organisms use bioluminescence to communicate, such as in fireflies, which use light to attract members of the opposite sex. Marine environments support a number of bioluminescent organisms including species of bacteria, dinoflagellates , jellyfish, coral, shrimp, and fish. On any given night one can see the luminescent sparkle produced by the single-celled dinoflagellates when water is disturbed by a ship's bow or a swimmer's motions.

See also Antibiotic resistance, tests for; Biotechnology; Food safety; Immunoflorescence; Microbial genetics

bi·o·lu·mi·nes·cence / ˌbīōˌloōməˈnesəns/ • n. the biochemical emission of light by living organisms such as fireflies and deep-sea fishes. ∎  the light emitted in such a way.DERIVATIVES: bi·o·lu·mi·nes·cent / -ˈnesənt/ adj.