1. BIOLUMINESCENCE PELAGOS BIOLOGY
PRODUCTION OF LIGHT BY LIVING ORGANISMS
LIGHT IS REALIZED BY ENERGY DERIVED FROM A CHEMICAL REACTION

2. BIOLUMINESCENCE PELAGOS BIOLOGY NOT phosphorescence, NOT iridescence
Most of the deep sea, pelagic species show the phenomenon
thousands of square miles of the ocean shine with the light of bioluminescent bacteria in the “milky sea effect".
The chemical luciferin (a pigment) reacts with Oxygen to create light, and luciferase (an enzyme) acts as a ctalyst of the reaction, sometimes mediated by cofactors such as Calcium ions or ATP.
The chemical reaction can occur either inside or outside the cell.
In bacteria, the expression of genes related to bioluminescence is controlled by an operon (Lux operon)

3. BIOLUMINESCENCE PELAGOS BIOLOGY
Most marine light-emission is in the blue and green light spectrum, the wavelengths that pass furthest through seawater. However, some loose-jawed fish emit red and infrared light, and the polychaete Tomopteris emits yellow light.

4. BIOLUMINESCENCE PELAGOS BIOLOGY
Aliivibrio fischeri is a Gram - bacterium found globally in the sea world
predominantly in Symbiosis with various marine animals.
Free living A. fischeri are found in very low quantities (almost undetectable) under a heterotrophic life style (on organics within the water).
They are found in higher concentrations in symbiosis with certain deep sea life within special light organs; or in the enteral (gut) microbiota of marine animals.
Symbiotic relationships in fishes and squids appear to have evolved separately. The most prolific of these relationships is with the Hawaiian bobtail squid (Euprymna scolopes).

5. Free-living A. fischeri in the ocean are captured by light organs of juvenile squid and fishes.
E. scolopes  produces mucous to answer the presence of a peptidoglycan (of the bacterial wall). Mucous around the light organ captures bacteria. V. fischeri  can exclude other bacteria from the mucous. When into the mucous, vibrios equips themselvres with flagella to migrate into the light organ.

6. In addition, many bacterial species reactive to the Oxygen produce an unsuitable habitat.  
The squid produces alide peroxydases (a mibcrobicide enzyme) which uses as substrates the H peroxyde.
V. fischeri has a catalases which subtracts the peroxyde before it matches the peroxydases.
After the ciliated ducts of the light organ, vibrios swim towards a large theca where they insert themselves among the epitelial cells.
Vibrios feed on the host Aa and sugar and they colonize completely the space in h from the infection.

7. BIOLUMINESCENCE PELAGOS BIOLOGY
The light organ of certain squid contain reflective plates that intensify and direct the light produced, due to reflectins (proteins). They regulate the light to keep the squid from casting a shadow on moonlit nights, for example.
Sepiolid squids expel 90% of the symbiotic bacteria in its light organ each morning in a process known as "venting". Venting is hypothesised to provide the free-living inoculum source for newly hatched squids.

8. BIOLUMINESCENCE PELAGOS BIOLOGY
The bioluminescence of A. fischeri is caused by transcription of the Lux operon, induced by population-dependent  quorum sensing.
The lux operon is a 9-kilobase fragment of the A. fischeri genome that controls bioluminescence through the catalyzation of the enzyme luciferase
The luminescence appears to be active more during the nighttime.
The bacterial luciferin-luciferase  system is encoded by a set of genes.
In A. fischeri, five genes (luxCDAB(F)E) are involved.

9. BIOLUMINESCENCE PELAGOS BIOLOGY
lux A and lux B code for the components of luciferase
lux CDE codes for a fatty acid reductase complex that makes the fatty acids necessary for the luciferase mechanism.
Lux C codes for the enzyme acyl-reductase,
lux D codes for acyl-transferase,
and lux E makes the proteins needed for the enzyme (acyl-protein synthetase),
two genes (LuxR and LuxI) are involved in regulating the OPERON. Several factors appear to induce and inhibit the transcription of this gene set (light emission).

10. Bacterial luciferin is a reduced riboflavin phosphate (FMNH2) which is oxidized in association with a long-chain aldehyde, oxygen, and a luciferase.
Luciferase produces blue/green light through the oxidation of
reduced flavin mononucleotide and a long-chain aldehyde by O2.
FMNH2+O2+R-CHO → FMN + R-COOH + H2O + Light
The reduced flavinmononucleotide (FMNH) is provided by the gene LuxG.
To generate the aldehyde needed in the reaction above, three additional enzymes are needed. The fatty acids needed for the reaction are pulled out from the fatty acid biosynthesis pathway by the enzyme acyl-transferase.

11. Acyl-transferase reacts with acyl-ACP to release R-COOH, a free fatty acid. R-COOH is reduced by a two-enzyme system to an adehyde.
R-COOH+ATP+NADPH→ R-CHO+AMP+PP+NADP+.
bioluminescence is regulated by autoinduction.
An autoinducer is a transcriptional promoter of the enzymes necessary for bioluminescence. Before the glow can be luminized, a certain concentration of an autoinducer must be present.
So, for bioluminescence to occur, high colony concentrations of A. fischeri should be present in the organism.

12. BIOLUMINESCENCE PELAGOS BIOLOGY
krill are bioluminescent animals with photophores.
The light is generated by an enzyme – catalysed reaction,
wherein a luciferin is activated by a luciferase.
Luciferin of many krill species is a fluorescent tetrapyrrole similar but not identical to dinoflagellate luciferin
the krill probably do not produce this substance themselves but acquire it as part of their diet, which contains dinoflagellates.

13. longitudinal section through a ventral
photophore from krill.
Light is produced in the lantern (La) made up by photocytes processes (B) and refractive rods. Light produced in the lantern is reflected by the
reflector (R) and passes through a
lens (Le) before to go outside.
Apart from B-cells, are present large cells (A), small cells (C) and D-cells.
On both sides of the lens, photophore vessels (V) and nerves (N) enter the organ. Capillaries branch off from the arteries and pass both D- and C-cells before they reach the lantern.
Nerves follow the capillaries and end at a sphincter-like structure at the base of the C-cells. Modified from Herring and Locket (Herring and Locket, 1978) with permission.
The function of these organs include mating, social interaction or orientation and a form of counter-illumination camouflage against overhead ambient light

14. BIOLUMINESCENCE PELAGOS BIOLOGY
Bathypelagic fish are black, or sometimes red, with few photophores. When photophores are used, it is usually to entice prey or attract a mate.
Flashlike fish have a retroflector behind the retina which they use with photophores to detect eyeshine in other fish.

15. PELAGOS BIOLOGY
BIOLUMINESCENCE
also known as Pyrrhophyta, "fire plants". Some produce bioluminescence.
Agitation of seawater containing dinoflagellates will stimulate light flashes.
When the cell is disturbed by a
grazing predator, such as a copepod
(the burglar), it gives a light flash
(the alarm)
which lasts 0.1 to 0.5 sec.
The flash attracts a secondary
predator, such as a small fish
(the police), which closes
in looking for food.
When the copepod sees
the luminescent flash it gives a jump,
because staying put means it is
vulnerable to predation.

16. Dinoflagellate luciferin is thought to be derived from Chlorophyll, and has a very similar structure. In  Gonyaulax, at pH 8 the molecule is "protected" from the luciferase by a "luciferin-binding protein", but when the pH lowers to 6, the luciferin reacts and light is produced.
The production of light is due to the association of luciferine with a protein, luciferase, a catalyst.
In the process of being oxidized, luciferin briefly exists in an excited state, after which it decays to its ground state, releasing energy in the form of photons (light).

17. PELAGOS BIOLOGY
BIOLUMINESCENCE
Dinoflagellates are the most common sources of bioluminescence in the surface waters of the ocean. The light displays created by breaking waves, swimming fish, or boats are mainly due to dinoflagellates.

18. the λ of emission is approximately in the blue-green region of the visible spectrum.
In most dinoflagellates the bioluminescence is controlled by an internal clock. At the end of the day the luminescent chemicals are packaged in vesicles (scintillons), which then migrate into the cytoplasm. An action-potential is generated in the internal vescicle membrane. It propagates throughout the cell allowing protons to pass from the vacuole into the cytoplasm. The cytoplasm is acidified, and the chemiluminescence is activated in the scintillons.

20. PELAGOS BIOLOGY
BIOLUMINESCENCE
Many jellyfish have bioluminescence, especially comb jellies, where more than 90% of planktonic species are known to produce light. Arguably, the most famous of all bioluminescent invertebrates is Aequorea victoria, which is the first species from which GFP (Green Fluorescent Protein) was isolated, a discovery which went on to win the Nobel prize.

21. BIOLUMINESCENCE Aequoraea victoria produces flashes of blue
PELAGOS BIOLOGY
BIOLUMINESCENCE
Aequoraea victoria produces flashes of blue
light by a quick release of Ca2+ which
interacts with the photoprotein aequorin.
The blue light is in turn transduced to green
by the GFP. Both aequorin and GFP are
important in biological research.
In 1961, Shimomura and Johnson isolated
the aequorin, and its small molecule cofactor, coelenterazine, from large numbers
of Aequorea jellyfish at Friday Harbor Laboratories.
In 1967, Ridgeway and Ashley microinjected aequorin into single muscle fibers of barnacles, and observed transient Ca ion-dependent signals during muscle contraction.
For his research into GFP, Osamu Shimomura was awarded the 2008 Nobel Prize for chemistry.

22. Ostracoda

24. PELAGOS BIOLOGY
BIOLUMINESCENCE
Bioluminescence is a form of intraspecific communication between animals, and can be used also for defense, and offense.
Many animals use bioluminescence in multiple ways. The different ways in which jellyfish use bioluminescence are still being discovered.