Cafeteria roenbergensis
| Cafeteria roenbergensis | ||||||||||||
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Cafeteria roenbergensis |
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| Scientific name | ||||||||||||
| Cafeteria roenbergensis | ||||||||||||
| T. Fennel and DJ Patterson , 1988 |
Cafeteria roenbergensis is a species of single-celled flagellate living in the seafrom the genus Cafeteria within the Stramenopilen . They are small, bacteria-eating ( bacterivorous ) unicellular organisms thatcan be foundin nanoplankton .
features
Exterior
The cells are kidney-shaped and laterally flattened. They are around four to six micrometers long and 4 to 4.5 micrometers wide. They do not have a solid cell envelope, i.e. neither a cell wall nor a pellicle . They lack the Lorica (cup-like cell envelope) of other bicosoecida . The two flagella start below the apex (subapical), often within a conspicuous pocket over which a lip-like structure hangs. The point of attachment of the flagella is defined as the ventral side (ventral side). The younger, front-seated flagella usually points straight ahead, the rear, older one backwards. The front scourge strikes at a frequency of around 20 Hertz. It has two rows of hairs on opposite sides of the scourge. There are around 25 hairs per micrometer per row. They are around 1.2 to 1.4 micrometers long, measured without terminal filaments: these consist of a middle long and two lateral shorter ones. The posterior flagella is smooth. Both flagella are about the same length with a length between five and eight micrometers. The cell mouth ( cytostome ) is also on the abdomen, to the right of the cell center.
Ultrastructural
Each cell has an egg-shaped nucleus in the center of the cell. The large peri- nuclear space observed in the first description is likely to be a preparation artifact. There are also three to five mitochondria that are egg-shaped and have the tubular cristae characteristic of stramenopiles . There is a Golgi apparatus on the abdomen . At the rear end of the cell there are usually two or three vacuoles with remains of digested bacteria. In elongated, branched vesicles there are three-part hairs like on the anterior flagella.
A special feature of Cafeteria roenbergensis is the presence of extrusomes. These are ejectile organelles that are distributed in a characteristic pattern on the cell surface, especially near the cell mouth (cytostome). They are bottle-shaped with the point inside the cell.
Flagellar apparatus
The flagellum apparatus is the structure from which the two flagella arise. At Cafeteria roenbergensis it consists of two basal bodies , three microtubule roots, a forked rhizoplast , connecting fibers between the basal bodies and the microtubule roots, and secondary microtubules of the cytoskeleton .
The two basal bodies form an angle of about 60 ° to 80 °. They are connected to one another by two clearly striped bands that stand on both sides. The transition zone of each basal body contains a basal plate with a central axosome at or near the plasmalemma .
One of the three microtubule roots attaches to the anterior basal body and is associated with secondary cytoskeletal microtubules. This is a common feature of stramenopiles. The other two microtubule roots attach to the posterior basal body. The distal ends of the two posterior roots do not overlap. The wider of the two roots has twelve microtubules and is divided distally into three subunits. The microtubule bands that arise from these three subunits define the mouth of the cell.
distribution and habitat
Cafeteria roenbergensis can be found in all marine areas worldwide and can be found in the deep sea. Like other species of the genus, the species has so far only been found in salt water. C. roenbergensis is part of the nanoplankton floating freely in the water , but it can also attach itself to substrates with its rear flagella. It was u. a. detected in Atlantic deep-sea sediments from a depth of 2300 m. Cafeteria roenbergensis is one of the most common and widespread species of heterotrophic nanoplankton. It forms stocks of several hundred cells per milliliter and can make up 10 to 20 percent of heterotrophic nanoplankton.
Way of life
Cafeteria roenbergensis feeds primarily on the bacterioplankton and small eukaryotes in the sea water, which it swirls in through the cytostome and ingests through phagocytosis . It is considered to be one of the ecologically most important species for the regulation of bacterial occurrences under the marine, heterotrophic nanoplankton. According to one of the first descriptors, David Patterson, the generic name cafeteria alludes to this role in the marine food web , while the species epithet roenbergensis refers to the Danish village of Rønbjerg , near which the species was first found.
Sessile cells sitting on a solid surface rest on the tip of the posterior flagella. In contrast to the related genus Bicosoeca , however, it cannot pull itself up to the substrate with the flagellum. The anterior flagella, on the other hand, creates a stream of water towards the cell body through screwy movements. This behavior is characteristic of the bicosoecida group.
It multiplies through simple cell division; sexual reproduction is just as little known as permanent stages, e.g. B. cyst .
No predators have been identified so far. However, viruses can cause the breakdown of cafeteria populations.
Systematics
Cafeteria roenbergensis is the only closely examined species in the genus. It was discovered in 1981 in a water sample from the Danish Limfjord and was first described by Fennel and Patterson in 1988. Due to the lack of a Lorica, the genus is placed in the family Cafeteriaceae together with Pseudobodo . The structure of the flagellum apparatus and the microtubule ligaments are characteristic of bicosoecida.
Investigations of rRNA sequences in cafeteria roenbergensis and other stramenopiles have shown that the bicosoecida represent a basal group of stramenopiles.
Parasites
The species is parasitized by the giant Cafeteria roenbergensis virus (CroV).
supporting documents
Individual evidence
- ^ A b Charles O'Kelly, David J. Patterson: The Flagellar Apparatus of Cafeteria roenbergensis . 1996.
- ↑ Hartmut Arndt, Klaus Hausmann, Matthias Wolf: Deep-sea heterotrophic nanoflagellates of the Eastern Mediterranean Sea: qualitative and quantitative aspects of their pelagic and benthic occurrence. In: Mar Ecol Prog Ser. Volume 256, 2003, pp. 45-56 ( PDF ; 634 kB).
- ↑ Tom Fenchel, David J. Patterson: Cafeteria roenbergensis nov. gen., nov. sp. 1988.
- ↑ Patterson: Cafeteria roenbergensis in the Encyclopedia of life , accessed September 19, 2012.
- ↑ Ramon Massana, Javier del Campo, Christian Dinter, Ruben Sommaruga: Crash of a population of the marine heterotrophic flagellate Cafeteria roenbergensis by viral infection. In: Environmental Microbiology. Volume 9, 2007, pp. 2660-2669, doi: 10.1111 / j.1462-2920.2007.01378.x .
- ↑ DD Leipe, PO Wainright, JH Gunderson, D. Porter, DJ Patterson, F. Valois, S. Himmerich, ML Sogin: The stramenopiles from a molecular perspective: 16S-like rRNA sequences from Labyrinthuloides minuta and Caferia roenbergensis. In: Phycologia. Volume 34, 1994, pp. 369-377.
literature
- Tom Fennel, David J. Patterson: Cafeteria roenbergensis nov. ge., nov. sp., a heterotrophic microflagellate from marine plankton. In: Marine Micobial Food Webs. 3 (1), 1988, pp. 9-19.
- Charles O'Kelly, David J. Patterson: The Flagellar Apparatus of Cafeteria roenbergensis Fennel & Patterson, 1996 (Bicosoecales = Bicosoecida). In: European Journal of Protistology. 32, 1996, pp. 216-226.
