''Vampyrella lateritia'' is a freshwater species of predatory

amoebae An amoeba (; less commonly spelled ameba or amœba; plural ''am(o)ebas'' or ''am(o)ebae'' ), often called an amoeboid, is a type of cell or unicellular organism with the ability to alter its shape, primarily by extending and retracting pseudopo ...

that feeds on species of algae and is known for its specialized feeding strategy of removing, digesting, and ingesting the cellular contents of its prey. It is the

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specime ...

of the genus ''Vampyrella'' and has been identified in numerous locations around the world including Brazil, Germany, and the eastern United States. Along with ''Vampyrella pendula'', its genome was sequenced in 2012.

Life cycle

''Vampyrella lateritia'' has four life stages that revolve about the feeding cycle: motile

trophozoites A trophozoite (G. ''trope'', nourishment + ''zoon'', animal) is the activated, feeding stage in the life cycle of certain protozoa such as malaria-causing '' Plasmodium falciparum'' and those of the '' Giardia'' group. (The complement of the tropho ...

(the activated, feeding stage), plasmodia in which the cytoplasm contains many nuclei, digestive cysts, and resting cysts. It has been observed feeding on species from the genera '' Zygnema'', ''

Spirogyra ''Spirogyra'' (common names include water silk, mermaid's tresses, and blanket weed) is a genus of filamentous charophyte green algae of the order Zygnematales, named for the helical or spiral arrangement of the chloroplasts that is character ...

'', and '' Mougeotia'' and is considered a specialist predator as its known prey is restricted to a limited number of green algal species. Like other vampyrellids, ''Vampyrella lateritia'' grows well between 10°C and room temperature. It contains intracellular bacteria that have not yet been conclusively identified, although the morphology of the

endosymbiotic An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within ...

bacteria resembles Ca. ''Megaira polyxenopila'', a species of bacteria in the family

Rickettsiaceae The Rickettsiaceae are a family of bacteria. The genus '' Rickettsia'' is the most prominent genus within the family. The bacteria that eventually formed the mitochondrion (an organelle in eukaryotic cells) is believed to have originated from ...

Trophozoites

In this stage of action and feeding, the cells are compact and spherical with radiating

filopodia Filopodia (singular filopodium) are slender cytoplasmic projections that extend beyond the leading edge of lamellipodia in migrating cells. Within the lamellipodium, actin ribs are known as ''microspikes'', and when they extend beyond the lame ...

and pseudopodia, moving freely through the

water column A water column is a conceptual column of water from the surface of a sea, river or lake to the bottom sediment.Munson, B.H., Axler, R., Hagley C., Host G., Merrick G., Richards C. (2004).Glossary. ''Water on the Web''. University of Minnesota-D ...

. The central cell body is orange and the pseudopodia are colourless. In order to move, the filopodia are positioned under the spherical body and slowly rolls the entire cell. Along the pseudopodia, numerous granules known as membranosomes shoot rapidly out of the

cell cortex The cell cortex, also known as the actin cortex, cortical cytoskeleton or actomyosin cortex, is a specialized layer of cytoplasmic proteins on the inner face of the cell membrane. It functions as a modulator of membrane behavior and cell surface p ...

, connected by a thin strand of

cytoplasm In cell biology, the cytoplasm is all of the material within a eukaryotic cell, enclosed by the cell membrane, except for the cell nucleus. The material inside the nucleus and contained within the nuclear membrane is termed the nucleoplasm. ...

, and are retracted. Trophozoites attach to an algal cell and retract their long pseudopodia, flattening the cell body tightly against the algae to increase the contact area. Feeding is proceeded by the dissolution of a hole 5-7 µm in diameter in the algae's cell wall. After several minutes of this, the cell wall bursts and the exposed protoplast is engulfed into a large food

vacuole A vacuole () is a membrane-bound organelle which is present in plant and fungal cells and some protist, animal, and bacterial cells. Vacuoles are essentially enclosed compartments which are filled with water containing inorganic and organic m ...

. This process is known as plasmoptysis and resembles a sucking motion. It is likely the origin of the genus name Vampyrella, Latin for 'small vampire'. The remains of the destroyed protoplast still within the algal cell are then engulfed by an ingestion pseudopodium. ''Vampyrella lateritia'' can consume several algal cells before entering the digestive cyst phase. After absorbing a single algal cell, ''Vampyrella lateritia'' is about ten times its original volume. However the dramatic increase in volume is only temporary and the amoeba returns to its normal volume within a few minutes. ''Vampyrella lateritia'' are known to only feed on live prey.

Plasmodia

Individual amoeba can fuse into large and deformed plasmodia. The structure and colour are the same as the trophozoites, however this stage occurs predominantly in old cultures of ''Vampyrella lateritia'' where cell density is high and nutrients are limited. However this stage has been observed in laboratory settings, so it is unclear the conditions under which ''Vampyrella lateritia'' would form plasmodia in natural conditions.

Digestive cysts

During digestive cyst formation, the trophozoite retracts its pseudopodia and secretes a cell wall. The digestive cysts have two cyst envelopes, where the inner is stronger than the outer. Unlike other vampyrellid amoebae, ''Vampyrella lateritia'' retains its separate food vacuoles throughout the entire digestive phase. The digestive phase is marked by a colour change of the cytoplasm as nutrients are digested - as a result, the colour of the digestive cyst is a good indicator for the cyst's maturity. ''Vampyrella lateritia'' is often seen as red or orange. After digestion is complete, trophozoites hatch and leave the parent cell through holes in the cell wall created as part of the exocytosis of food remnants. Although the feeding process only lasts for several minutes in ''Vampyrella lateritia'', the digestive process takes much longer, typically one to two days.

Resting cysts

As resting cysts, ''Vampyrella lateritia'' can survive freezing and desiccation for at least three years. Resting cysts have condensed contents and numerous cell walls, however the resting cyst stage of life is not an obligatory part of all ''Vampyrella lateritia'' life cycle, unlike the digestive cyst phase. The ''Vampyrella lateritia'' can return to the trophozoite phase in the presence of algae prey organisms and fresh medium.

References

{{Taxonbar, from=Q2509702 Aconchulinida Taxa described in 1865