Aequorea Victoria
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''Aequorea victoria'', also sometimes called the crystal jelly, is a
bioluminescent Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some fungi, microorganisms inc ...
hydrozoan
jellyfish Jellyfish, also known as sea jellies or simply jellies, are the #Life cycle, medusa-phase of certain gelatinous members of the subphylum Medusozoa, which is a major part of the phylum Cnidaria. Jellyfish are mainly free-swimming marine animal ...
, or hydromedusa, that is found off the west coast of North America. The species is best known as the source of aequorin (a photoprotein), and green fluorescent protein (GFP); two proteins involved in bioluminescence. Their discoverers,
Osamu Shimomura was a Japanese organic chemist and marine biologist, and professor emeritus at Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts and Boston University School of Medicine. He was awarded the Nobel Prize in Chemistry in 2008 for ...
and colleagues, won the 2008 Nobel Prize in Chemistry for their work on GFP.


Description

Almost entirely transparent and colorless, and sometimes difficult to resolve, ''Aequorea victoria'' possess a highly contractile mouth and
manubrium The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, human lung, lungs, and ma ...
at the center of up to 100 radial canals that extend to the bell margin. The bell margin is surrounded by uneven tentacles, up to 150 of them in fully-grown specimens. The tentacles possess
nematocyst A cnidocyte (also known as a cnidoblast) is a type of cell containing a large secretory organelle called a ''cnidocyst'', that can deliver a sting to other organisms as a way to capture prey and defend against predators. A cnidocyte explosively ...
s that aid in prey capture, although they have no effect on humans. Specimens larger than 3 cm usually possess gonads for sexual reproduction, which run most of the length of the radial canals and are visible in the photos in this article as whitish thickenings along the radial canals. The bell margin is ringed with the muscular velum, which is typical of hydromedusae, and aids in locomotion through muscular contraction of the bell. Larger specimens are frequently found with symbiotic hyperiid amphipods attached to the subumbrella, or even occasionally living inside the gut or radial canals.


Distribution

''Aequorea victoria'' are found along the North American west coast of the Pacific Ocean from the Bering Sea to southern California. The medusa part of the life cycle is a
pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...
organism, which is budded off a bottom-living polyp in late spring. The medusae can be found floating and swimming both nearshore and offshore in the eastern Pacific Ocean; this species is particularly common in
Puget Sound Puget Sound ( ; ) is a complex estuary, estuarine system of interconnected Marine habitat, marine waterways and basins located on the northwest coast of the U.S. state of Washington (state), Washington. As a part of the Salish Sea, the sound ...
.


Identification

''Aequorea'' species can be fairly difficult to tell apart, as the morphological features on which identifications are made are mostly the numbers of tentacles, numbers of radial canals, numbers of marginal
statocysts The statocyst is a balance sensory receptor present in some aquatic invertebrates, including bivalves, cnidarians, ctenophorans, echinoderms, cephalopods, crustaceans, and gastropods, A similar structure is also found in ''Xenoturbella''. The ...
, and size. These features are fairly plastic, and the numbers of tentacles and radial canals increase in all species of ''Aequorea'' with size. One other species is occasionally found in the same geographical range as ''Aequorea victoria''; this other form has been called '' Aequorea coerulescens''. While ''A. coerulescens'' is apparently generally found offshore in the eastern Pacific Ocean, rare specimens have been collected in central California and in Friday Harbor, North Puget Sound. While morphologically similar to ''Aequorea victoria'', the ''Aequorea coerulescens'' form is larger (roughly the size of a dinner plate) with many more radial canals. Animals of sizes intermediate between these two forms are also rather intermediate in appearance, making morphological identifications difficult. This species is thought to be synonymous with ''Aequorea aequorea'' of
Osamu Shimomura was a Japanese organic chemist and marine biologist, and professor emeritus at Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts and Boston University School of Medicine. He was awarded the Nobel Prize in Chemistry in 2008 for ...
, the discoverer of green fluorescent protein (GFP). Shimomura together with
Martin Chalfie Martin Lee Chalfie (born January 15, 1947) is an American scientist. He is University Professor at Columbia University. He shared the 2008 Nobel Prize in Chemistry along with Osamu Shimomura and Roger Y. Tsien "for the discovery and develop ...
and Roger Y. Tsien were awarded the 2008 Nobel Prize in Chemistry for the discovery and development of this protein as an important biological research tool. Originally the ''A. victoria'' name was used to designate the variant found in the Pacific, and the ''A. aequorea'' designation was used for specimens found in the Atlantic and Mediterranean. The species name used in GFP purification was later disputed by M.N. Arai and A. Brinckmann-Voss (1980), who decided to separate them on the basis of 40 specimens collected from around Vancouver Island. Shimomura notes that this species in general shows great variation: from 1961 to 1988 he collected around 1 million individuals in the waters surrounding the Friday Harbor Laboratories of
University of Washington The University of Washington (UW and informally U-Dub or U Dub) is a public research university in Seattle, Washington, United States. Founded in 1861, the University of Washington is one of the oldest universities on the West Coast of the Uni ...
, and in many cases there were pronounced variations in the form of the jellyfish.


Life history

''Aequorea victoria'' have a dimorphic life history, alternating between asexual benthic polyps and sexual planktonic medusae in a seasonal pattern. ''Aequorea victoria'' juvenile medusae are asexually budded off hydroid colonies in late spring; these free-living hydromedusae will spend all of their lives in the plankton. The medusa spends its first stage of life growing quickly, and after reaching approximately 3 cm will begin producing gametes for reproduction. Each medusa is either a male or a female. The eggs and spermatozoa mature daily in the medusa gonads, given enough food, and are free-spawned into the water column in response to a daily light cue, where they are fertilized and eventually settle out to form a new hydroid colony. The hydroids live on hard or rocky substrates on the bottom, where they asexually bud new tiny jellyfish each springtime in response to some (still unknown) environmental cue(s). The medusa form generally lives approximately 6 months, roughly from late spring into the autumn.


Natural history

''Aequorea victoria'' typically feed on soft-bodied organisms, but the diet may also include some crustacean zooplankton such as
copepod Copepods (; meaning 'oar-feet') are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (living in the water column), some are benthos, benthic (living on the sedimen ...
s, crab zoëals,
barnacle Barnacles are arthropods of the subclass (taxonomy), subclass Cirripedia in the subphylum Crustacean, Crustacea. They are related to crabs and lobsters, with similar Nauplius (larva), nauplius larvae. Barnacles are exclusively marine invertebra ...
nauplii & other larval planktonic organisms. Gelatinous organisms consumed include
ctenophores Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that marine habitats, inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs ...
,
appendicularians Larvaceans, copelates or appendicularians, class Appendicularia, are solitary, free-swimming tunicates found throughout the world's oceans. While larvaceans are filter feeders like most other tunicates, they keep their tadpole-like shape as ad ...
and other hydromedusae, including rarely other ''Aequorea victoria'' if conditions are appropriate. ''Aequorea victoria'' is an intraguild predator, it preys upon other gelatinous zooplankton which compete for the same prey, this plays a significant role in the population dynamics of planktonic food webs (Purcell, 1991). Prey is ensnared in long tentacles containing nematocysts, and ingested with a highly contractile mouth that can expand to consume organisms half the medusae's size. Due to their voracious nature, ''Aequorea victoria'' density can be inversely correlated to zooplankton density, indicating a competitive presence in shared environments. The swimming velocity of ''Aequorea victoria'' does not increase as their body size increases which deems them as inefficient swimmers. Therefore, they require direct contact with their prey in order to feed which is effectively done through energetic propulsion in which pressure allows them to passively move in their environment.


Predators

''Aequorea'' medusae are eaten by the voracious scyphozoan ''
Cyanea capillata The lion's mane jellyfish (''Cyanea capillata'') is one of the Largest organisms#Cnidarians (Cnidaria), largest known species of jellyfish. Its range is confined to cold, boreal ecosystem, boreal waters of the Arctic Ocean, Arctic, northern Atla ...
'', commonly called the lion's mane jelly, as well as
ctenophores Ctenophora (; : ctenophore ) is a phylum of marine invertebrates, commonly known as comb jellies, that marine habitats, inhabit sea waters worldwide. They are notable for the groups of cilia they use for swimming (commonly referred to as "combs ...
,
siphonophorae Siphonophorae (from Ancient Greek σίφων (siphōn), meaning "tube" and -φόρος (-phóros), meaning "bearing") is an order within Hydrozoa, a class of marine organisms within the phylum Cnidaria. According to the World Register of Marin ...
and other hydromedusae, including documented cases of cannibalism. Many larger specimens are found with the parasitic
hyperiid The Hyperiidea is one ot the six suborders of amphipods, small aquatic crustaceans. Unlike some other suborders of Amphipoda, hyperiids are exclusively marine and do not occur in fresh water. Hyperiids are distinguished by their large eyes and ...
amphipod ''
Hyperia medusarum ''Hyperia'' is a genus of amphipods in the family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis ...
'' attached to the either the subumbrella or exumbrella; these amphipods may burrow into the jelly, but such activities are not lethal to the jellyfish.


Luminescence

This jellyfish is capable of producing flashes of blue light by a quick release of
calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...
(Ca2+), which interacts with the photoprotein aequorin. The blue light produced is in turn transduced to green by the now famous
green fluorescent protein The green fluorescent protein (GFP) is a protein that exhibits green fluorescence when exposed to light in the blue to ultraviolet range. The label ''GFP'' traditionally refers to the protein first isolated from the jellyfish ''Aequorea victo ...
(GFP). This transduction of energy is called
Förster resonance energy transfer Förster resonance energy transfer (FRET), fluorescence resonance energy transfer, resonance energy transfer (RET) or electronic energy transfer (EET) is a mechanism describing energy transfer between two light-sensitive molecules (chromophores). ...
(FRET). Both aequorin and GFP are important fluorescent markers frequently employed in biochemical research. In 1961, Shimomura and Johnson isolated the protein aequorin, and its small molecule cofactor,
coelenterazine Coelenterazine is a luciferin, a molecule that emits light after reaction with oxygen, found in many aquatic organisms across eight phyla. It is the substrate of many luciferases such as '' Renilla reniformis'' luciferase (Rluc), ''Gaussia'' lu ...
, from large numbers of ''Aequorea'' jellyfish at Friday Harbor Laboratories. They discovered, after initially finding bright luminescence on adding seawater to a purified sample, that calcium ions (Ca2+) were required to trigger
bioluminescence Bioluminescence is the emission of light during a chemiluminescence reaction by living organisms. Bioluminescence occurs in multifarious organisms ranging from marine vertebrates and invertebrates, as well as in some Fungus, fungi, microorgani ...
. This research also marked the beginning of research into green fluorescent protein which was summarized by Shimomura. In 1967, Ridgeway and Ashley microinjected aequorin into single muscle fibers of barnacles, and observed transient calcium ion-dependent signals during muscle contraction. For his research into GFP, Osamu Shimomura was awarded the 2008 Nobel Prize for chemistry, together with
Martin Chalfie Martin Lee Chalfie (born January 15, 1947) is an American scientist. He is University Professor at Columbia University. He shared the 2008 Nobel Prize in Chemistry along with Osamu Shimomura and Roger Y. Tsien "for the discovery and develop ...
and Roger Tsien. This discovery led to great advancements in the field of medicine because it allows for further understanding in treatments and medical diagnoses through research in cells and bacteria.


References


External links


General species overview
{{Taxonbar, from=Q133055 Aequoreidae Bioluminescent cnidarians Animals described in 1902