The Euplotes are a genus of ciliated protozoa passing freely through the surface of muddy water, where they get the necessary bacteria for food.
These microorganisms are called ciliates because they have the presence of cilia, hair-like appendages, essential for their movement from one place to another and for obtaining food.
By Galbas, from Wikimedia CommonsEuplotes have a rigid, armored-looking body that does not lose its shape with movement, not even when diving through sediment in search of food.
The cilia it presents are grouped in tufts called cirrus, which the microorganism uses as a paddle or to walk, depending on the surface where it is. These cirrus clouds are in the front, on the sides and at the end of its body, resembling a tail.
The ventral area (belly) of these organisms is flat and the dorsal area (back) is bulky or ribbed, resembling a coffee bean. It has several separate ribs that run the length of the body from end to end.
Most of the current ciliates correspond to the Euplotes Charon species that have an oval shape and a transparent appearance. They live in areas of slow or stagnant water circulation.
General characteristics
The body of the Euplotes is made up of: ectoplasm, contractile vacuole (mouth), cirri, membranelas, neuromotor apparatus, anal opening, endoplasm, macronucleus and micronucleus.
Its body is transparent, rigid, oval, measures approximately 80 to 200 µm long and is distinguished by a macronucleus that is visible inside, in the shape of an inverted “C”, with an adjacent micronucleus.
The mouth of the Euplotes is in the anterior region and its perimeter is triangular. This mouth is large and has cilia around it, which form a membrane that looks like fangs. When these cilia move, they allow them to eat diatom algae and small particles of plant material.
Despite this challenging aspect, they are calm, harmless and peaceful beings, unlike the Paramecians, who have a harmless appearance but are really dangerous.
From the side, the Euplotes look quite thin and you can see their cilia joined in tufts to form the cirrus, which it uses to move around. Sometimes they have a ciliary row on each side of the ventral area.
The cirrus clouds located in the lateral and rear areas have a spiny appearance and allow the mobility of these microorganisms, to climb or walk, other times to swim according to the need and the environment.
Taxonomy
The number and location of ventral cirrus in Euplotes, and the geometry of the ventral argyrome, are the criteria used to divide this taxon into four morphologically different subgenera: Euplotes, Euplotoides, Euplotopsis, and Monoeuplotes.
Taxonomically, Euplotes are classified as follows: Biota Chromista (Kingdom) Harosa (Sub-kingdom) Alveolata (Infra-kingdom) Protozoa (Phylum) Ciliophora (Sub-phylum) Ciliata (class) Euciliata (Sub-class) Spirotricha (Order).
In turn, within the genus Euplotes, there are the following species
Euplotes aberrans, Euplotes acanthodus, Euplotes aediculatus, Euplotes affinis, Euplotes alatus, Euplotes antarcticus, Euplotes apsheronicus, Euplotes arenularum, Euplotes balteatus, Euplotes balticus, Euplotes, Euplotes, Euplotes bisulcatronus elegans, Euplotes cherries, Euplotes bisulcatronus, Euplotes crayfish, Euplotes bisulcatronus, Euplotes euryhalinus, Euplotes eurystomus, Euplotes focardii, Euplotes gracilis, Euplotes harpa, Euplotes iliffei, Euplotes latus, Euplotes mediterraneus, Euplotes minor, Euplotes minuta, Euplotes moebupiusiotes, Euplotes nectopolitanisuplotes, Euplotes musculature parabalteatus, Euplotes parawoodruffi, Euplotes patella, Euplotes poljanski, Euplotes quinquecincarinatus, Euplotes quinquicarinatus, Euplotes raikovi, Euplotes rariseta, Euplotes salina,Euplotes sinica, Euplotes strelkovi, Euplotes thononensis, Euplotes trisulcatus, Euplotes vannus, Euplotes woodruffi and Euplotes zenkewitchi.
Habitat
It is common to observe Euplotes in both fresh and salty waters. When used for microbiological experimentation and other cellular analysis techniques, they should be preserved in mixed cultures with molds, algae, yeasts, bacteria, or other protozoa that serve as food.
Under these conditions, laboratory work options for biochemical tests, for example, are limited. But due to its large size and diversity of organizational patterns, its experimental use remains a great advantage over the technical deficiencies of cultivation.
These particular ciliates are easy to collect because of their ubiquity (they are found anywhere in the world) and can be comfortably grown in the laboratory, making them a great tool for studying biological processes in general.
Natural environments
In natural environments, Euplotes must deal with predators. This prey-predator interaction forces them to use two types of defense: individual and group.
In the individual escape strategy, the microorganism is capable of reacting and moving away from predators that carry out toxic discharges in radii of 300 microns in diameter and in a maximum time of 90 seconds.
The group escape strategy is more refined and complex. These ciliates have a low concentration non-protein molecule that generates a repulsive action to repel predators. A few Euplotes from each demographic group are qualified to secrete such a substance that encourages the escape of predators.
Euplotes have a very wide bioecological range and are considered cosmopolitan species, due to their physiological diversity that gives them great adaptability.
They can be located in different ecosystems such as the coastal waters of California, Japan, Denmark and Italy. It is also common to locate them in plankton as benthic ciliates and there are also some that colonize snow particles.
Nutrition
The diet of the Euplotes is very varied and they use several feeding tactics. They consume cells of different sizes, from bacteria to diatom algae, and they also eat other protozoa.
They can be omnivorous, consume bodontids (a type of flagellates) and a great variety of heterotrophic flagellates (which transform organic matter into nutrients and energy), including other kinds of ciliates.
Some species have selective feeding, such as Euplotes vannus. Some studies describe a relationship between the type of food, its concentration and the growth of the population of these microorganisms.
Reproduction
The reproduction of Euplotes is especially characteristic due to the process of DNA synthesis that takes place in the macronucleus.
In some species, such as Euplotes eurystomus, the reproductive generation time is short and its growth is high, if the medium where it is found is adequate. This species uses Aerobacter aerogenes as its main source of food.
Most protozoa reproduce asexually, by mitotic cell division, but some species have the ability to reproduce sexually, through a process called: conjugation.
When Euplotes mate, there is an exchange of genetic material through a cytoplasmic bridge. After this exchange, the new generation that has been formed by cell division will make various combinations of genes from the cells of the parents.
After fertilization, the cells separate when the diffusion zone is reabsorbed and the contraction processes become operative. Many specialists consider that the sexual cycle is superimposed on an asexual cycle that precedes it.
Sometimes a mating called intraclonal conjugation or selfing occurs and occurs when there is no sexual or asexual fertilization.
This is advantageous because it restores the life cycle clock and disadvantageous because it can only be performed for a short time since it can lead to a loss of adaptation due to loss of genetic variation.
References
- Guillén, A. (March 12, 2011). Virtual Biodiversity. Obtained from biodiversityvirtual.org
- Lynn, D. (1979). The Ciliated Protozoa: Characterization, Classification, and Guide to the Literature. New York: Springer.
- Parker, S. (1982). Synopsis and classification of living organisms. New York: McGraw-Hill.
- Pelczar, MJ and Reid, RD (1966). Microbiology. Mexico: McGraw-Hill.
- Prescott, D. (1964). Methods in Cell Biology, Volume 1. New York and London: Academic Press.
- Turanov, AA, Lobanov AV, Fomenko, DE, Morrison HG, Sogin, Ml, Klobutcher, LA, Hatfield DL, Gladyshev VN. (2009). Genetic Code Supports Targeted Insertion of Two Amino Acids by One Codon. Science, 259-261.
- Van Dijk, T. (2008). Microbial Ecology Research Trends. New York: Nova Science Publisher, Inc.