Bioluminescence – Is the phenomenon of emission of light from living organism that performs some biological function? During the process chemical energy is converted to light energy. It serves various purposes like sexual attraction and courtship,predation and defense. Possibly evolved from early ultra-weak chemo luminescent oxidase reactions, to become very efficient light-emitting process.
In nineteenth century Raphael Dubois performed a significant experiment to isolate two key components of bioluminescence reaction. First Luciferin was isolated in 1956. Luciferin are a class of light emitting heterocyclic compounds found in organisms that cause bioluminescence. These are oxidised in presence of enzyme luciferase to produce oxyluciferin and energy in the form of light. It’s oxidation with oxygen under luciferase is catalysed by magnesium ion and adenosine triphosphate (ATP).
Biochemistry of light production –
In 1885, Raphael Dubois demonstrated that three substances are involved in bioluminescence: luciferin, luciferase and molecular oxygen. Bioluminescence is due to the substrate enzyme complex of luciferin and luciferase within the cellular cytoplasm.
ATP first activates the luciferin in presence of magnesium ion and luciferase to produce adenyl luciferin, which is then oxidized to form excited oxyluciferin. Enzymatic activation of luciferin results in release of energy. Synaptic fluid near nerve endings, which are chemical intermediaries between nerve and light organ, triggers the light production.
Bioluminescence colour variation –
|
Diptera |
Blue-green light |
|
Hemiptera |
White light |
|
Coleoptera |
Yellow-green light |
Significance –
Mating signal – For aggregation, in some species of lampyridae female are wingless and sedentary, light production is therefore important to attract winged males.
Predation – New Zealand glow worm fly, Arachnocampa luminosa, female deposit eggs on the ceiling of dark caves. Upon hatching, larvae hang down by sticky thread and produce light to attract insects. Caves inherited by them are called ‘Luminous Caves’.
Defense – In railroad worm, the continuous glow of head region suggest a possible illumination function, whereas circumstances under which lateral light organs are switched on suggest of defense function.
Bioluminescence in pest management –
It is used as a tool for mapping organism distribution patterns. Recently in USA, genetic material of cotton pink bollworm was modified with green fluorescent protein (GFP) derived from jellyfish. The GFP transgenic pink bollworm strain emits a strong green light at the larval stages. The future objective of study is to add temperature-sensitive lethal gene along with GFP gene to pink bollworm, for management.
