Crustacean Cardioactive Peptide
Encyclopedia
Crustacean cardioactive peptide (CCAP) is a highly conserved, amidated cyclic nonapeptide with the primary structure PFCNAFTGC-NH2 (ProPheCysAsnAlaPheTyrGlyCys-NH2) and a disulfide bridge between Cys3 and Cys9. It is found in crustacean
s and insect
s where it behaves as a cardioaccelerator, neuropeptide transmitter
for other areas of the nervous system
and a hormone
. CCAP was first isolated from the pericardial
organs of the shore crab Carcinus maenas
, where it has a role in regulating heartbeat. It was assumed that this was the peptide's main function and its name reflects this.
, CCAP has cardioacceleratory properties in Manduca sexta and Drosophila melanogaster
; it is a highly conserved protein
found in species as diverse as moths and fruit flies in addition to the crustacean it was originally identified in. Interestingly, under specific conditions, CCAP has also been shown to induce cardiac reversal in M. sexta and D. melanogaster
.
Since CCAP was first identified and its possible role suggested, it has been proven it serves many other functions. It regulates release of adipokinetic hormone
during sustained flight in L. migratoria. It is also important in metabolism
and digestion
in other species; CCAP is involved as a hormone in the cockroach Periplaneta americana by upregulating digestive hormones after the insect has fed on nutritional matter. In the crab Cancer borealis CCAP controls passage of food through the forgut by modulating the stomatogastric ganglion's pyloric rhythm. This suggests CCAP is involved primarily in movement of food along the gut, facilitating digestion by secretion of digestive hormones and increasing flow of blood.
The effects of CCAP on the reproductive organs of females of the species L. migratoria have also been studied. The peptide stimulates the contraction of the oviducts and spermatheca
. There is no CCAP or CCAP-like immunoreactivity shown in the oviduct or the nerves innervating the oviduct so it is probable that CCAP acts as a neurohormone
to perform these functions.
CCAP is one of several peptides and hormones to be involved in the moulting
process of crustaceans and insects.
would be lethal. In Drosophila the destruction of CCAP-containing neurons during development causes major changes in and disruptions to timing and behaviour of moulting.
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s and insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s where it behaves as a cardioaccelerator, neuropeptide transmitter
Neurotransmitter
Neurotransmitters are endogenous chemicals that transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to...
for other areas of the nervous system
Nervous system
The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous...
and a hormone
Hormone
A hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
. CCAP was first isolated from the pericardial
Pericardium
The pericardium is a double-walled sac that contains the heart and the roots of the great vessels.-Layers:...
organs of the shore crab Carcinus maenas
Carcinus maenas
Carcinus maenas is a common littoral crab, and an important invasive species, listed among the 100 "world's worst alien invasive species". It is native to the north-east Atlantic Ocean and Baltic Sea, but has colonised similar habitats in Australia, South Africa, South America and both Atlantic and...
, where it has a role in regulating heartbeat. It was assumed that this was the peptide's main function and its name reflects this.
Function
As well as C. maenasCarcinus maenas
Carcinus maenas is a common littoral crab, and an important invasive species, listed among the 100 "world's worst alien invasive species". It is native to the north-east Atlantic Ocean and Baltic Sea, but has colonised similar habitats in Australia, South Africa, South America and both Atlantic and...
, CCAP has cardioacceleratory properties in Manduca sexta and Drosophila melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
; it is a highly conserved protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
found in species as diverse as moths and fruit flies in addition to the crustacean it was originally identified in. Interestingly, under specific conditions, CCAP has also been shown to induce cardiac reversal in M. sexta and D. melanogaster
Drosophila melanogaster
Drosophila melanogaster is a species of Diptera, or the order of flies, in the family Drosophilidae. The species is known generally as the common fruit fly or vinegar fly. Starting from Charles W...
.
Since CCAP was first identified and its possible role suggested, it has been proven it serves many other functions. It regulates release of adipokinetic hormone
Adipokinetic hormone
Adipokinetic hormone is a short peptide hormone that has been studied in insects. It is a lipid mobilising hormone and is responsible for regulating fuel transport in the haemolymph, for redirecting energy to other processes as required by the insect. AKH was initially discovered in the desert...
during sustained flight in L. migratoria. It is also important in metabolism
Metabolism
Metabolism is the set of chemical reactions that happen in the cells of living organisms to sustain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories...
and digestion
Digestion
Digestion is the mechanical and chemical breakdown of food into smaller components that are more easily absorbed into a blood stream, for instance. Digestion is a form of catabolism: a breakdown of large food molecules to smaller ones....
in other species; CCAP is involved as a hormone in the cockroach Periplaneta americana by upregulating digestive hormones after the insect has fed on nutritional matter. In the crab Cancer borealis CCAP controls passage of food through the forgut by modulating the stomatogastric ganglion's pyloric rhythm. This suggests CCAP is involved primarily in movement of food along the gut, facilitating digestion by secretion of digestive hormones and increasing flow of blood.
The effects of CCAP on the reproductive organs of females of the species L. migratoria have also been studied. The peptide stimulates the contraction of the oviducts and spermatheca
Spermatheca
The spermatheca , also called receptaculum seminis , is an organ of the female reproductive tract in insects, some molluscs, oligochaeta worms and certain other invertebrates and vertebrates...
. There is no CCAP or CCAP-like immunoreactivity shown in the oviduct or the nerves innervating the oviduct so it is probable that CCAP acts as a neurohormone
Neurohormone
A neurohormone is any hormone produced and released by neurons.Examples include:*Thyrotropin-releasing hormone *Gonadotropin-releasing hormone *Adrenocorticotropin-releasing hormone*Oxytocin*Antidiuretic hormone *Epinephrine...
to perform these functions.
CCAP is one of several peptides and hormones to be involved in the moulting
Ecdysis
Ecdysis is the moulting of the cuticula in many invertebrates. This process of moulting is the defining feature of the clade Ecdysozoa, comprising the arthropods, nematodes, velvet worms, horsehair worms, rotifers, tardigrades and Cephalorhyncha...
process of crustaceans and insects.
Effects of lack of CCAP
There have been no mutant individuals of any species found to possess CCAP who have a genetic defect meaning they are not able to produce the peptide. It is likely any such mutationMutation
In molecular biology and genetics, mutations are changes in a genomic sequence: the DNA sequence of a cell's genome or the DNA or RNA sequence of a virus. They can be defined as sudden and spontaneous changes in the cell. Mutations are caused by radiation, viruses, transposons and mutagenic...
would be lethal. In Drosophila the destruction of CCAP-containing neurons during development causes major changes in and disruptions to timing and behaviour of moulting.