Temptin is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that acts as a water-borne

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

in the marine gastropod mollusk ''

Aplysia californica The California sea hare (''Aplysia californica'') is a species of sea slug in the sea hare family, Aplysiidae.Rosenberg, G.; Bouchet, P. (2011). Aplysia californica J. G. Cooper, 1863. Accessed through: World Register of Marine Species at http:// ...

''. It is an abundant protein that is synthesized in the albumen gland, and is released in the egg cords during oviposition, along with other proteins called attractin, seductin and enticin. Together, they make up a complex of water-soluble proteins that act together to attract mates for reproduction and induce

spawning Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquati ...

History

Temptin was first described in 2004 in the marine gastropod ''

''. In 2017, the knowledge of temptin as a chemical signal was extended to the freshwater gastropod mollusk ''

Biomphalaria glabrata ''Biomphalaria glabrata'' is a species of air-breathing freshwater snail, an aquatic pulmonate gastropod mollusk in the family Planorbidae, the ram's horn snails. ''Biomphalaria glabrata'' is an intermediate snail host for the trematode ''Sch ...

''. In 2019 it was reported as a protein present in the aerial eggs of the freshwater gastropod molluscs ''

Pomacea canaliculata ''Pomacea canaliculata'', commonly known as the golden apple snail or the channeled apple snail, is a species of large freshwater snail with gills and an operculum, an aquatic gastropod mollusc in the family Ampullariidae, the apple snails. S ...

'' and ''

Pomacea maculata ''Pomacea maculata'' is a species of large freshwater snail with an operculum, an aquatic gastropod mollusk in the family Ampullariidae, the apple snails. Common name of its synonymous name ''Pomacea insularum'' is the island applesnail. Toge ...

''. In 2021 a study of the temptin

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

suggests that it is unique to all

Lophotrochozoa Lophotrochozoa (, "crest/wheel animals") is a clade of protostome animals within the Spiralia. The taxon was established as a monophyletic group based on molecular evidence. The clade includes animals like annelids, molluscs, bryozoans, brachi ...

, and that it is present in all

molluscs Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil sp ...

, except in

cephalopods A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head, an ...

Structure

The gene encoding temptin is found the Lophotrochozoa clade. Temptin from ''Aplysia californica'' has

sequence homology Sequence homology is the biological homology between DNA, RNA, or protein sequences, defined in terms of shared ancestry in the evolutionary history of life. Two segments of DNA can have shared ancestry because of three phenomena: either a spe ...

epidermal growth factor Epidermal growth factor (EGF) is a protein that stimulates cell growth and differentiation by binding to its receptor, EGFR. Human EGF is 6-k Da and has 53 amino acid residues and three intramolecular disulfide bonds. EGF was originally descr ...

(EGF)-like domains of higher organisms that mediate protein surface contact with cells during fertilization and blood coagulation. The protein has two disulfide bound, that could stabilize it from proteolysis in the extracellular medium where it is released, and a possible

calcium Calcium is a chemical element with the 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 ...

binding site.

Function

In addition to its

function, in the freshwater bivalve ''

Hyriopsis ''Hyriopsis'' is a genus of bivalves belonging to the family Unionidae. The species of this genus are found in Southeastern Asia. Species: *'' Hyriopsis altealata'' *'' Hyriopsis bialata'' *'' Hyriopsis bogatchevi'' *'' Hyriopsis cumingii'' ...

cumingii'', the protein is expresed in the mantle and it is involved in the

biomineralization Biomineralization, also written biomineralisation, is the process by which living organisms produce minerals, often to harden or stiffen existing tissues. Such tissues are called mineralized tissues. It is an extremely widespread phenomenon; ...

process. Through

gene silencing Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is often used in research. In particular, methods used to silence gen ...

it was shown that their absence alters the biomineral structure of the mollusc

shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses ** Thin-shell structure Science Biology * Seashell, a hard ou ...

References

{{reflist Pheromones