Grammistins are

peptide Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty am ...

toxins synthesised by glands in the skin of soapfishes of the

tribes The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...

Grammistini Grammistini is one of the five tribes in the subfamily Epinephelinae, the group including the groupers, which is part of the family Serranidae which also includes the anthias and the sea basses. They are found in tropical oceans around the world. ...

and

Diploprionini Diploprionini is one of the five Tribe (biology), tribes in the subfamily Epinephelinae, the groupers, which is part of the Family (biology), family Serranidae which also includes the Anthias (genus), anthias and the sea basses. Genera The follo ...

which are both classified within the

grouper Groupers are a diverse group of marine ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all members of this f ...

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Epinephelinae Groupers are a diverse group of marine Actinopterygii, ray-finned fish in the family Epinephelidae, in the order Perciformes. Groupers were long considered a subfamily of the seabasses in Serranidae, but are now treated as distinct. Not all m ...

, a part of 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 for social order. Ideally, families offer predictabili ...

Serranidae Serranidae is a large family (biology), family of fishes belonging to the order Perciformes. The family contains about 450 species in 65 genera, including the sea basses and the groupers (subfamily Epinephelinae). Although many species are small, ...

. Grammistin has a

hemolytic Hemolysis or haemolysis (), also known by several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may occur in vivo ...

and ichthyotoxic action. The grammistins have secondary structures and biological effects comparable to other classes of peptide toxins,

melittin Melittin is the main component (40–60% of the dry weight) and the major pain-producing substance of honeybee (''Apis mellifera'') venom. Melittin is a basic peptide consisting of 26 amino acids. Function The principal function of melittin a ...

from the bee stings and pardaxins which are secreted in the skin of two sole species. A similar toxin has been found to be secreted in the skin of some

clingfish Clingfishes are ray-finned fishes of the family Gobiesocidae, the only family in the suborder Gobiesocoidei of the order Blenniiformes. These fairly small to very small fishes are widespread in tropical and temperate regions, mostly near the coa ...

es. Grammistins have a distinctive bitter taste. Soapfishes increase the amount of toxin released in their skin if they are stressed and other species of fish kept in a confined space with a stressed soapfish normally die. If ingested at a high enough dosage the toxin is lethal to mammals with some symptoms being similar to those produce by

ciguatoxin image:ciguatoxin.svg, 300px, class=skin-invert-image, Chemical structure of the ciguatoxin CTX1B Ciguatoxins are a class of toxic Polycyclic compound, polycyclic polyethers found in fish that cause ciguatera. There are several different chemi ...

s. Grammistins also cause

hemolysis Hemolysis or haemolysis (), also known by #Nomenclature, several other names, is the rupturing (lysis) of red blood cells (erythrocytes) and the release of their contents (cytoplasm) into surrounding fluid (e.g. blood plasma). Hemolysis may ...

of mammalian blood cells. The main purpose of the secretion of grammastin is defensive and when a

lionfish ''Pterois'' is a genus of venomous fish, venomous marine fish, commonly known as the lionfish, native to the Indo-Pacific. It is characterized by conspicuous aposematism, warning coloration with red or black bands and ostentatious dorsal fins tip ...

(''

Pterois miles ''Pterois miles'', the devil firefish or common lionfish, is a species of ray-finned fish native to the western Indo-Pacific region. It is frequently confused with its close relative, the red lionfish (''Pterois volitans''). The scientific name ...

'') tries to predate on a soapfish it immediately ejects it from its mouth, suggesting that it had detected the bitter taste. Grammistins affect organisms by

cytolysis Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to diffuse into the cell. Water can enter the cell by diffusion through the cell membrane or through selective membrane channels ...

and hemolysis. As well as being toxic they are also antibiotic and antimicrobial.

References

{{reflist Ichthyotoxins Peptides Biological toxin weapons