Kleptoplasty or kleptoplastidy is a process in

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

plastid A plastid is a membrane-bound organelle found in the Cell (biology), cells of plants, algae, and some other eukaryotic organisms. Plastids are considered to be intracellular endosymbiotic cyanobacteria. Examples of plastids include chloroplasts ...

s, notably

chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s from

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

, are sequestered by the host. The word is derived from ''Kleptes'' (κλέπτης) which is

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

for thief. The alga is eaten normally and partially digested, leaving the plastid intact. The plastids are maintained within the host, temporarily continuing

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

and benefiting the host.

Etymology

The word kleptoplasty is derived from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

(), meaning , and (), originally meaning formed or moulded, and used in biology to mean a

Process

Kleptoplasty is a process in

symbiotic Symbiosis (Ancient Greek : living with, companionship < : together; and ''bíōsis'': living) is any type of a close and long-term biolo ...

relationships whereby

s, notably

s from

, are sequestered by the host. The alga is eaten normally and partially digested, leaving the plastid intact. The plastids are maintained within the host, temporarily continuing

and benefiting the host. The term was coined in 1990 to describe chloroplast symbiosis.

Occurrence

Kleptoplasty has been acquired in various independent clades of

eukaryote The eukaryotes ( ) constitute the Domain (biology), domain of Eukaryota or Eukarya, organisms whose Cell (biology), cells have a membrane-bound cell nucleus, nucleus. All animals, plants, Fungus, fungi, seaweeds, and many unicellular organisms ...

s, namely

single-celled A unicellular organism, also known as a single-celled organism, is an organism that consists of a single cell (biology), cell, unlike a multicellular organism that consists of multiple cells. Organisms fall into two general categories: prokaryotic ...

protists A protist ( ) or protoctist is any Eukaryote, eukaryotic organism that is not an animal, Embryophyte, land plant, or fungus. Protists do not form a Clade, natural group, or clade, but are a Paraphyly, paraphyletic grouping of all descendants o ...

of the

SAR supergroup SAR is a highly diverse clade of eukaryotes, often considered a supergroup, that includes stramenopiles (heterokonts), alveolates, and rhizarians. It is a node-based taxon (under the Sar name), including all descendants of the three groups' ...

and the Euglenozoa phylum, and some marine invertebrate

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

In protists

Foraminifera

Some species of the

foraminifera Foraminifera ( ; Latin for "hole bearers"; informally called "forams") are unicellular organism, single-celled organisms, members of a phylum or class (biology), class of Rhizarian protists characterized by streaming granular Ectoplasm (cell bio ...

n genera '' Bulimina'', '' Elphidium'', '' Haynesina'', '' Nonion'', '' Nonionella'', '' Nonionellina'', '' Reophax'', and '' Stainforthia'' sequester

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

chloroplasts.

Dinoflagellates

The stability of transient plastids varies considerably across plastid-retaining species. In the

dinoflagellate The Dinoflagellates (), also called Dinophytes, are a monophyletic group of single-celled eukaryotes constituting the phylum Dinoflagellata and are usually considered protists. Dinoflagellates are mostly marine plankton, but they are also commo ...

s ''Gymnodinium'' spp. and '' Pfiesteria piscicida'', kleptoplastids are photosynthetically active for only a few days, while kleptoplastids in ''Dinophysis'' spp., taken from cryptophytes, can be stable for 2 months. In other dinoflagellates, kleptoplasty has been hypothesized to represent either a mechanism permitting functional flexibility, or perhaps an early

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

ary stage in the permanent acquisition of chloroplasts.

Ciliates

'' Mesodinium rubrum'' is a

ciliate The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to flagellum, eukaryotic flagella, but are in general shorter and present in much larger numbers, with a ...

that steals chloroplasts from the cryptomonad '' Geminigera cryophila''. ''M. rubrum'' participates in additional endosymbiosis by transferring its plastids to its predators, the dinoflagellate planktons belonging to the genus ''Dinophysis''. Karyoklepty is a related process in which the nucleus of the prey cell is kept by the host as well. This was first described in 2007 in ''M. rubrum''.

Euglenozoa

The first and only case of kleptoplasty within Euglenozoa belongs to the species '' Rapaza viridis'', the earliest diverging lineage of Euglenophyceae. This microorganism requires a constant supply of a strain of '' Tetraselmis'' microalgae, which it ingests to extract chloroplasts. The kleptoplasts are then progressively transformed into ones that resemble the permanent chloroplasts of the remaining Euglenophyceae. Cells of ''Rapaza viridis'' can survive for up to 35 days with these kleptoplasts. Kleptoplasty is considered the mode of nutrition of the euglenophycean common ancestor. It is hypothesized that kleptoplasty allowed for various events of

horizontal gene transfer Horizontal gene transfer (HGT) or lateral gene transfer (LGT) is the movement of genetic material between organisms other than by the ("vertical") transmission of DNA from parent to offspring (reproduction). HGT is an important factor in the e ...

that eventually allowed the establishment of permanent chloroplasts in the remaining Euglenophyceae.

Animals

Rhabdocoel flatworms

Two species of rhabdocoel marine flatworms, ''Baicalellia solaris'' and ''Pogaina paranygulgus,'' make use of kleptoplasty. The group was previously classified as having algal endosymbionts, though it was already discovered that the endosymbionts did not contain nuclei. While consuming diatoms, ''B. solaris'' and ''P. paranygulus'', in a process not yet discovered, extract plastids from their prey, incorporating them subepidermally, while separating and digesting the frustule and remainder of the diatom. In ''B. solaris'' the extracted plastids, or kleptoplasts, continue to exhibit functional photosynthesis for a short period of roughly 7 days. As the two groups are not sister taxa, and the trait is not shared among groups more closely related, there is evidence that kleptoplasty evolved independently within the two taxa.

Sea slugs (gastropods)

= Sacoglossa

Sea slug Sea slug is a common name for some Marine biology, marine invertebrates with varying levels of resemblance to terrestrial Slug, slugs. Most creatures known as sea slugs are gastropods, i.e. they are Sea snail, sea snails (marine gastropod moll ...

s in the clade

Sacoglossa Sacoglossa are a superorder of small sea slugs and sea snails, marine gastropod mollusks that belong to the clade Heterobranchia known as sacoglossans. There are 284 valid species recognized within this superorder. Sacoglossans live by ingestin ...

practise kleptoplasty. Several species of Sacoglossan sea slugs capture intact, functional chloroplasts from algal food sources, retaining them within specialized cells lining the

mollusc Mollusca is a phylum of protostome, protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant taxon, extant species of molluscs are recognized, making it the second-largest animal phylum ...

's digestive

diverticula In medicine or biology, a diverticulum is an outpouching of a hollow (or a fluid-filled) structure in the body. Depending upon which layers of the structure are involved, diverticula are described as being either true or false. In medicine, t ...

. The longest known kleptoplastic association, which can last up to ten months, is found in '' Elysia chlorotica'', which acquires chloroplasts by eating the alga '' Vaucheria litorea'', storing the chloroplasts in the cells that line its gut. Juvenile sea slugs establish the kleptoplastic endosymbiosis when feeding on algal cells, sucking out the cell contents, and discarding everything except the chloroplasts. The chloroplasts are phagocytosed by digestive cells, filling extensively branched digestive tubules, providing their host with the products of photosynthesis. It is not resolved, however, whether the stolen plastids actively secrete photosynthate or whether the slugs profit indirectly from slowly degrading kleptoplasts. Due to this unusual ability, the sacoglossans are sometimes referred to as "solar-powered sea slugs", though the actual benefit from photosynthesis on the survival of some of the species that have been analyzed seems to be marginal at best. Studies have found that photosynthates from captured chloroplasts are able to influence growth in '' Elysia viridis.'' How long a sacoglossan can live without food seems not to depend on the photosynthetic activity of its kleptoplasts, but rather on the ability of that sacoglossan species to manage starvation. Changes in temperature have been shown to negatively affect kleptoplastic abilities in sacoglossans. Rates of photosynthetic efficiency as well as kleptoplast abundance have been shown to decrease in correlation to a decrease in temperature. The patterns and rate of these changes, however, varies between different species of sea slug.

= Nudibranchia

= Some species of another group of sea slugs,

nudibranch Nudibranchs () are a group of soft-bodied marine gastropod molluscs, belonging to the order Nudibranchia, that shed their shells after their larval stage. They are noted for their often extraordinary colours and striking forms, and they have b ...

s such as '' Pteraeolidia ianthina'', sequester whole living symbiotic zooxanthellae within their digestive diverticula, and thus are similarly "solar-powered".Sutton & Hoegh-Guldberg, ''Host-Zooxanthella Interactions in Four Temperate Marine Symbioses; Assessment of Effect of Host Extract on Symbionts''; The Biological bulletin, Marine Biological Laboratory (Woods Hole, Mass.). v. 178 (1990) p. 175
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References

External links

* {{cite web , url=http://www.abc.net.au/science/scribblygum/june2007/#a , title=Solar Powered Sea Slugs , date=June 2007 , publisher=ABC Science Online , access-date=2008-11-24 Algae Ecology terminology Endosymbiotic events