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BIOLUMINESCENCE. Submitted by, SELMA ABDUL SAMAD BCH- 10 – 05 – 02 S2 MSc BIOCHEMISTRY. Phenomenon of production and emission of light by a living organism. Creatures ( unicellular bacteria to vertebrates ) chemical energy Light energy ( Wilson and Hastings, 1998)
BIOLUMINESCENCESubmitted by,SELMA ABDUL SAMADBCH- 10 – 05 – 02S2 MSc BIOCHEMISTRYPhenomenon of production and emission of light by a living organism.
  • Creatures ( unicellular bacteria to vertebrates )
  • chemical energy Light energy(Wilson and Hastings, 1998)
  • Bioluminescent animals
  • Are mostly - marine Very few - terrestrial
  • Process is 100 % efficient
  • It is different from fluorescence
  • Fluorescence – Needs high energy radiation
  • The molecule absorbs a photon and excites an electron It comes back to low energy state releasing energy in the form of light.(Williamson & Cummins,1983)The original molecule is restored following fluorescent emission.
  • Bioluminescence – A characteristic chemical reaction takes place in the organism which releases enough energy producing a visible photon of light.
  • The expended molecule must be replaced by synthesis or diet, it is not regenerated.Chart from lap as on page 1Next chart as on page 2Luciferins
  • From different biological sources - chemically unrelated
  • They are polycyclic aromatic compounds that are inherently fluorescent since their orbitals have multiple energy levels.
  • Bacterial luciferin – a derivative of riboflavin
  • Dinoflagellate luciferin – related to the chlorophyll structure
  • Firefly luciferin – Requires ATP for bioluminescence
  • Coelenterazine – extremely common,found in several species
  • Vargulin – found in some shrimp species
  • (Vargula & Cypridina)Structures of luciferins as on page 2The spectrum of radiation observed in bioluminescence is very broad
  • ranges from violet to red
  • most common are blue or blue green (~470 nm)
  • This may be because the phenomenon is largely prevalent in oceans ; and seawater is especially transparent to blue light ; Since other light do not travel far in water , evolution might have selected blue color in bioluminescence.
  • Thecolor of bioluminescence depends on
  • mainly the structure of luciferin (Wilson & Hastings,1998)
  • 3D structure and amino acid sequence of luciferase protein
  • The presence of accessory proteins or other chromophores also affect the spectrum of radiated light
  • (Wilson & Hastings,1998)Physiological control of bioluminescence
  • Complicated
  • Involves wide variety of mechanisms for subcellular localisation, signal induction & chemical regeneration.
  • Eg. Bioluminescent bacteria – the photochemicals are present throughout the cytoplasm and glow continuosly without flashing.
  • Eg. Fireflies – highly structured specialised light producing organs( the lantern) that is regulated by flow of oxygen to it.
  • Eg. Dinoflagellates – special light producing organelles (scintillons) regulated by shifts in pH.
  • Eg. Some worms – flashes controlled by Ca2+ entry into cells
  • (William & Hastings,1998)
  • Basic principle of bioluminescence is preserved across diverse species.
  • But its physiological implementation is extremely variegated.Uses of Bioluminescence
  • As a defense mechanism – night time
  • Two logics a) distract primary predator
  • b) make primary predator visible to larger secondary predator
  • Eg. Dinoflagellates – have a circadian rhythm of bioluminescence ; trigger light flash when they are mechanically disturbed (wave, motion of fish nearby etc)
  • They bioluminesce and produce beautiful displays during red tide blooms.
  • Camouflage at mid-ocean depths
  • Where light is still available ~90% of animals in mesopelagic zone (200-1000 m depth) are bioluminescent - Some squids – symbiotic association of biolum.bacteria – uses their bioluminescence to match envir. light Defense mechanism – Daytime Some animals bioluminesce blue on their underbellies – the color blends with blue color of the surface water – thus masks them from the predators lurking below.Repulsion of predators – certain squids and shrimps give out biolum. bacterial slurry,like smoke that repels predators.
  • Defense mechanism – Terrestrial
  • Eg. Fireflies , centipedes , millipedes , worms Warning potential predators that they do not taste pleasant (They also bioluminesce to procure food)
  • Procure food
  • Eg. Isistius brasiliensis (cookie-cutter shark)Underbelly bioluminesce except a patch of skin near the throat - appears like a small fish & attracts large predators - suctions to large fish , clamps with teeth into their flesh and cuts and bites off cookie shaped chunk of flesh Some predators lure prey by mimicking their signals. Another eg. : Malacosteus (Black dragon fish) - Has 2 different bioluminescent organs - one produces blue-green light - the other (under the eye) produces long IR (red) light - IR light or red light are invisible to most deep sea animals (other than malacosteus) - Thus it can see its prey without alerting them
  • Attracting & Signaling Potential Mates
  • - By varying their light output - eg. Fireflies and Deep Sea Angler fish - Signaling by light help choose a compatible mate - Intensity or Frequency of signals help discern the health of the mate. (so stronger evolutionary advantage) eg. Fireflies – light production maybe a continuous glow, a certain frequency of flashes or a sequence of repeated flashes that can alternate in frequency.CommunicationBetweenbacteria - Bacterial lux operon controls bioluminescence - In many bioluminescent bacteria, it is turned on only when the bacteria are in high cell densities (Quorum sensing – The ability of bacteria to regulate gene expression in response to cell density ) - eg. Vibrio, Photomicrobium etc. (mainly found in seawater and in symbiotic association with fishes like angler fish, flashlight fish, bobtail squid etc)PicturesPicturesPicturesThusBioluminescence is an example of convergent evolution – different organisms develop the same physical or functional feature through separate evolutionary routes.
  • Of greater need to marine dwellers – especially in dark faces of water – they produce light for survival , reproduction , species recognition etc.
  • Not much terrestrial animals – light is abundant and life is restricted to the surface of earth.(fireflies, glow-worms, some larvae, insects, arachnids, annelids , fungi etc)
  • Also known as cold light emission
  • Fireflies
  • Photinus pyralis, Lampyris noctiluca etc.
  • Family – Lampyridae About 2000 species Found in temperate & tropical environments Their larvae (glow worms) need wet areas.
  • Luminescent organs – Lanterns
  • The luminescent cells of lanterns are close to the cells at the end of tracheoles(that bring O2 and take away CO2 from tissues)
  • These cells have NO synthase (NOS)activated by a nerve impulse
  • Arginine Nitric oxide
  • The NO diffuses to lantern cells and blocks cyt.c oxidase and thus inhibits cellular respiration in mitochondria.
  • As such, the O2 content in the cells increase and this turns on light production in peroxisomes.
  • Peroxisomes contain luciferase and luciferin-ATP (ATP is generated when lanterns are dark)
  • Luciferin + ATP luciferase Luciferyl adenylate + PPi
  • Luciferyl adenylate + O2 Oxyluciferin + AMP + Light (Light ~560 nm and 100% efficient)When oxyluciferin is of - ketoform -- red / green to red light - enolate from -- yellow-green light
  • The quick decay of NO probably contributes to the short duration of the flash.
  • Fireflies produce light from their lower abdomen
  • Green, Yellow or pale-red 510 – 670 nm
  • Fireflies usually use bioluminescence for sexual selection
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