The infusoria-shoe is known since school lessons biology. This is one of the types of ciliary unicellular organisms that does not belong to the animal, plant or fungal kingdom, but is included in the intermediate group of protists. The creature lives in fresh water, and interesting name it received for the constant shape of the body, similar to the imprint of the sole of a shoe.
Infusoria slipper - ciliary unicellular organism, which is included in the intermediate group of protists scientific classification
The type of ciliates belongs to the super-kingdom of eukaryotes, that is, organisms with a nucleus. They correspond to the ciliary type, the class Oligohymenophorea and the genus Paramecium. A feature of representatives of this rank is the preference for acidic environmental conditions.
Researchers at one time spent a lot of effort on deciphering the genome of some species related to paramecia. It turned out that it contains 40,000 protein-coding genes, while humans have only about 28,000 of them. The increase in the number of genes occurred as a result of several duplications of the original genome. The method of coding the sequence of amino acid residues in ciliates is unique in the presence of a single, and not triple, as in the universal genetic code, codon that completes the synthesis of the polypeptide chain.
general description
The optimal habitat for the organism is fresh standing water, which contains decaying organic compounds. In particular, these conditions are met by a home aquarium, in the sample of silty water of which protozoa are often found.
The habitat of the infusorian shoe is stagnant water It is possible to consider ciliates only under a microscope, since its size does not exceed 0.1-0.3 mm. Almost 7% of the cell consists of dry matter, chemical composition which is represented by the following components:
- protein (58%);
- lipids (31.4%);
- ash (3.6%).
The body of the ciliate-shoe is covered with a dense layer of cytoplasm, under the outer membrane of which there are elements of the cytoskeleton such as alveoli and microtubules. The body consists of the following elements:
- nucleus (macronucleus);
- nucleolus (micronucleus);
- longitudinal and superficial cilia;
- mouth opening;
- formed and emerging digestive vacuoles (phagosomes);
- an opening through which the digestive vacuole is emptied (cytopig or powder);
- two contractile vacuoles.
Each organelle performs important functions.
Nucleus and nucleolus
The infusoria has two nuclei, each of which has its own structure and functions. Small has a rounded shape, contains hereditary material. Messenger RNAs are poorly read from its genome, so hereditary information is not converted into a protein or other functional product, and there is no gene expression. In the event of the destruction of the nucleolus, the life of the shoe continues, but it will only reproduce asexually, the sexual process will be impossible.
The maturation of a large bean-shaped nucleus leads to complex rearrangements in the hereditary material. All mRNAs are read from its genes, so protein synthesis depends on it. Destroys the nucleus of the sexual process, but at the end of it, the macronucleus is restored again.
Cilia and trichocysts
There are 10 to 15 thousand cilia in a small cell. They grow from basal bodies, which form a complex cytoskeletal system that includes postkinetodesmal fibrils and filaments. At the base of the organelles, parasomal sacs are formed, resulting from the invagination of the outer membrane.
The ciliates have between 10,000 and 15,000 cilia. Between densely spaced infusor cilia there is still room for 5-8 thousand defense organelles called trichocysts. They are one of the varieties of secretory vesicles pushed out by ciliates during exocytosis. They look like bodies with a tip, transversely striated every 7 nm, located in membrane sacs. The protective function is manifested in the instant elongation and firing in case of danger. However, some representatives of ciliates lack such organelles and are quite viable at the same time.
The infusoria-shoe moves with the help of cilia. Making wave-like movements, she swims with a blunt end forward. The organelles make a direct impact in the straightened state. The return is carried out in a curved. This process cannot be called synchronous., since the first eyelash in the row sets the pace, and each subsequent one repeats the action with a slight delay. This leads to the rotation of the shoe around its axis during movement. In a second, it overcomes 2-2.5 mm distances.
By bending the body, the infusoria can change direction. In case of an unexpected collision with an obstacle, it will sharply move back, since the potential difference in its membrane will sharply decrease, and calcium ions will penetrate inside. Then the shoe will move back and forth for some time, during which calcium will leave the cell, and soon continue along the original trajectory.
Nutritional Organs
The mouth of the shoe looks like a depression on the body, turning into a cellular pharynx. Around the mouth opening are complex structures formed from cilia. The infusoria-shoe feeds mainly on algae, bacteria and other small unicellular organisms, which it finds by their secretions. chemicals. Hairy structures around the mouth drive prey down the throat along with the flow of water.
The mouth of the ciliates looks like a depression on the body Next, the food enters the digestive vacuole formed in the process of phagocytosis, and under the influence of the cytoplasmic flow moves to the rear end of the cell, returns to the front, and again goes back. The vacuole merges with lysosomes, which is accompanied by the appearance of an acidic environment, which gradually shifts towards slightly alkaline.
The phagosome migrates and increases the rate of absorption by separating small membrane vesicles. Everything that cannot be digested is thrown out through the powder, devoid of a developed cytoplasm. Digested products are dispersed throughout the intercellular space and are used for life.
After performing its function, the vacuole merges with the outer membrane and collapses, releasing small bubbles. Subsequently, they enter the cell pharynx through microtubules that form the cytoskeleton, where they form a new phagosome.
Interestingly, the abundance of food affects how long the shoe ciliates live. Life expectancy is only a few days with excess nutrition and several months (sometimes up to a year) with a poor diet.
contractile vacuoles
Contractile vacuoles are located on the front and back of the cells. Each of them consists of a reservoir that opens outwards at times, and outgoing radial channels surrounded by many thin tubes that pump fluid from the cytoplasm. The entire fragile system is held by the cytoskeleton.
The main function of these internal organelles is osmoregulation. Diffusion of water molecules into the cell leads to an excess of fluid, which is excreted by vacuoles. The adducting channels pump out water into the reservoir, which then contracts and separates from the tubes, throwing water out of the cell through the pore. Two vacuoles work alternately, each contracting for 10-25 seconds, depending on the ambient temperature. An hour later, the ejected volume of liquid is equal to the volume of the cell itself.
breeding process
The ciliate shoe reproduces asexually, which consists in a peppered division and is accompanied by complex regeneration processes. Since two individuals are obtained from a single individual, each of the new shoes gets one contractile vacuole, and they are forced to complete the missing one on their own. The cell mouth goes to only one ciliate, and the second at this time has to form a mouth opening with the necessary structures around it. Each representative forms basal bodies and new cilia independently.
Ciliates are also characterized by a sexual process called conjugation, which consists in the transfer of nuclei between partner cells. Shoes formed by the division of different mother cells take part in the process. They stick together oral cavities resulting in the formation of a cytoplasmic bridge.
Ciliates can reproduce both asexually and sexually. At this time, large nuclei are destroyed in each individual, and small ones are divided, while halving the number of chromosomes. The result is 4 cores, 3 of which are destroyed. The rest divides into two genetically identical nuclei, and each partner develops male and female pronuclei. The female nuclei each remain in their own cell, while the male ciliates are exchanged. During the exchange, the female and male pronuclei merge and a new nucleus is formed, dividing into two more. They become new large and small nuclei.
Learning Opportunities
The story about the infusoria-shoe can be heard at school, but not everyone knows exactly how the researchers studied the tiny organism. In fact, there is nothing difficult in observing it, besides, the size of tenths of a millimeter is quite large for the simplest. All this means that research can be carried out even at home, but first you need to dilute the culture of ciliates.
Since shoes are present in all bodies of water, water is taken from these sources. For the purity of the experiment, you need to take three glass containers and put decaying twigs and leaves in one of them, living plants in the other, and silt from the bottom in the third. All materials are taken from the reservoir, the liquid is also extracted from there and poured into jars.
When everything is ready, you need to carefully examine the contents of the container and make sure that there are no extraneous organisms visible to the eye, such as insects or larvae. If they are, they will have to be caught, otherwise the ciliates will be eaten. The prepared habitat is placed on the window, covered with glass and left at room temperature for several days. At the same time, it is necessary to ensure that direct Sun rays.
After two days, the jar should be shaken and checked to see if any organisms have appeared there. It can be both shoes and other creatures, but it is easy to check. You need to take a drop of water from the illuminated wall of the vessel closer to the surface, it is in this place that most of the organisms of interest will concentrate. Then the drop should be placed on glass and examined through a microscope or at least a magnifying glass.
If, at the same time, spindle-shaped bodies are visible, moving quickly and smoothly and rotating around their axis, then it turned out to separate the shoes. If there is a piece of greenery or a bacterial film in the drop, many ciliates will immediately accumulate around the food.
To speed up the process of reproduction of ciliates, you need to place them in a favorable environment. It is not difficult to separate the shoe from other animals. Usually they move much faster than other organisms, and this should be used. To do this, a drop, in which there are several types of creatures, is placed on glass and placed in a well-lit place. A small amount of fresh water is poured next to it and a line is drawn with a toothpick from one liquid to another so that a thin water bridge is obtained connecting the two environments. The ciliates will quickly cover the distance and end up in a new drop.
It happens that it is not possible to see anything alive in the water, in which case you can add a few drops of boiled milk to the container and wait another two days. After this time, you can once again try to study the developed organisms.
Further, the shoes will multiply, you can speed up this process by creating favorable conditions for them. To do this, they are placed in one of the following environments:
- on dried banana peel;
- on lettuce leaves;
- into milk;
- in an infusion of hay.
Organisms bred in this way can be used to observe them for research purposes or bring practical benefits. Since ciliates are natural freshwater orderlies, they can disinfect liquid in fish tanks and also serve as food for fry.
Thus, shoe ciliates are amazing organisms with unique features (for example, the sexual process without reproduction), they can be studied even at home.
A typical representative of the class of ciliary ciliates is the ciliate shoe or paramecia (Paramaecium caudatum; Fig. 1)
The structure and reproduction of ciliates shoes
The infusoria shoe lives in small stagnant reservoirs. In shape of the body, it resembles the sole of a shoe, reaches a length of 0.1-0.3 mm, is covered with a strong elastic shell - pellicle, under which there are skeletal supporting threads in the ecto- and endoplasm. This structure allows the ciliates to maintain a constant body shape.
The organelles of movement are hair-like cilia (infusoria have 10-15 thousand of them), covering the entire body. When examining cilia using an electron microscope, it was found that each of them consists of several (about 11) fibers. Each cilium is based on a basal body located in a transparent ectoplasm. The shoe moves quickly thanks to the coordinated work of the cilia that rake in the water.
In the cytoplasm of ciliates, ectoplasm and endoplasm are clearly distinguished. In the ectoplasm, between the bases of the paramecium cilia, there are attack and defense organelles - small spindle-shaped bodies - trichocysts. Photographs taken with an electron microscope show that the discarded trichocysts are equipped with nail-like tips. When irritated, trichocysts are thrown outward, turning into a long, elastic thread that strikes the enemy or prey.
In the endoplasm are located - two nuclei (large and small) and systems of digestive and excretory organelles.
Food organelles. On the so-called ventral side there is a pre-oral recess - a peristome, leading to the cellular mouth, which passes into the pharynx (cytopharynx), which opens into the endoplasm. Water with bacteria and unicellular algae, which the ciliates feed on, is driven through the mouth and pharynx by a special group of cilia of the peristome into the endoplasm, where it is surrounded by a digestive vacuole. The latter gradually moves along the body of the ciliate. As the vacuole moves, the swallowed bacteria are digested within an hour, first with an acidic and then with an alkaline reaction. The undigested residue is thrown out through a special opening in the ectoplasm - the powder, or anal pore.
Osmoregulation organelles. At the anterior and posterior ends of the body, on the border of the ecto- and endoplasm, there is one pulsating vacuole each (central reservoir), around which 5-7 adductor tubules are located in a corolla. The vacuole fills with fluid from these afferent canals, after which the fluid-filled vacuole (diastolic phase) contracts, pours fluid out through a small opening, and collapses (systole phase). Following this, the liquid, which again filled the adductor channels, pours into the vacuole. The anterior and posterior vacuoles contract alternately. Pulsating vacuoles perform a dual function - the return of excess water, which is necessary to maintain a constant osmotic pressure in the body of paramecium, and the release of dissimilation products.
Slipper nuclear apparatus represented by at least two qualitatively different nuclei located in the endoplasm. The shape of the nuclei is usually oval.
- The large vegetative nucleus is called the macronucleus. Transcription takes place in it - synthesis on DNA matrices of informational and other forms of RNA, which go to the cytoplasm, where protein synthesis is carried out on ribosomes.
- Small generative - micronucleus. It is located next to the macronucleus. In it, before each division, the number of chromosomes doubles, so the micronucleus is considered as a "depot" of hereditary information transmitted from generation to generation.
The infusoria-shoe reproduces both asexually and sexually.
- In asexual reproduction, the cell is laced in half along the equator and reproduction is carried out by transverse division. This is preceded by the mitotic division of the small nucleus and the processes characteristic of mitosis in the large nucleus.
After repeated asexual reproduction in life cycle the sexual process, or conjugation, takes place.
- The sexual process consists in the temporary connection of two individuals with mouth openings and the exchange of parts of their nuclear apparatus with a small amount of cytoplasm. At the same time, large nuclei break up into parts and gradually dissolve in the cytoplasm. Small nuclei first divide twice, the number of chromosomes is reduced, then three of the four nuclei are destroyed and dissolved in the cytoplasm, and the fourth divides again. As a result of this division, two haploid sex nuclei are formed. One of them - migrating, or male - passes into a neighboring individual and merges with the female (stationary) nucleus remaining in it. The same process occurs in the other conjugate. After the fusion of the male and female nuclei, the diploid set of chromosomes is restored and the ciliates diverge. After that, in each ciliate, the new nucleus is divided into two unequal parts, as a result of which a normal nuclear apparatus is formed - a large and a small nucleus.
Conjugation does not lead to an increase in the number of individuals. Its biological essence consists in the periodic reorganization of the nuclear apparatus, its renewal and increase in the viability of the infusoria, its adaptability to the environment.
Slipper and some other free-living ciliates feed on bacteria and algae. In turn, ciliates serve as food for fish fry and many invertebrates. Sometimes shoes are bred to feed fish fry that have just hatched from eggs.
The value of ciliates
Balantidium (Balantidium coli)
Localization. Colon.
Geographic distribution. Everywhere.
There are two contractile vacuoles. The macronucleus is bean-shaped or rod-shaped. A rounded micronucleus lies near its concave surface (Fig. 2). It reproduces by transverse division and by conjugation. Cysts are oval or spherical in shape (50-60 microns in diameter).
Domestic and wild pigs are considered the main reservoir of balantidiasis. In some farms, infection reaches 100%.
In the intestines of animals, balantidia easily encyst, while in the human body, cysts are formed in a relatively small amount. Animals excrete cysts in faeces and contaminate environment. Pig farm workers can become infected when caring for animals, cleaning livestock premises, etc. The infection rate of workers in this category is much higher compared to other specialties. Cysts in pig faeces persist for several weeks. Vegetative forms at room temperature live 2-3 days.
Infection occurs through contaminated vegetables, fruits, dirty hands, unboiled water.
Pathogenic action. Formation of bleeding ulcers in the intestinal wall, bloody diarrhea. Without treatment, the death rate reaches 30%.
Laboratory diagnostics. Detection in faeces of vegetative forms or cysts.
Prevention: observance of the rules of personal hygiene is of primary importance; public - the fight against pollution of the environment with the feces of pigs, as well as people, the appropriate organization of working conditions on pig farms, the timely detection and treatment of patients.
The most typical widespread representative of ciliary - infusoria slipper(Paramecium). It lives in stagnant water, as well as in freshwater bodies with a very weak current, containing decaying organic material.
The figure gives an idea of the pretty complex structure these organisms, typical for ciliates. The complexity of the cell structure in paramecia is explained by the fact that it has to perform all the functions inherent in the whole organism, namely nutrition, osmoregulation and movement. The body of the paramecium has a characteristic shape: its anterior end is blunt, and the posterior end is somewhat pointed.
Cilia ciliates shoes arranged in pairs over the entire surface of the cell. Located in longitudinal diagonal rows, they, making beatings, make the ciliate rotate and move forward. Between the cilia are openings leading to special chambers called trichocysts. From these chambers, under the influence of certain stimuli, thin pointed threads can shoot out, probably used to hold prey.
Under the pellicle of ciliates shoes ectoplasm is located - a transparent layer of dense cytoplasm of the gel consistency. In the ectoplasm there are basal bodies (identical to centrioles) from which cilia extend, and between the basal bodies there is a network of thin fibrils involved, apparently, in coordinating the beating of cilia.
The bulk cytoplasm of ciliates slippers represented by endoplasm, which has a more liquid consistency than ectoplasm. It is in the endoplasm that most of the organelles are located. On the ventral (lower) surface of the shoe, closer to its front end, there is a perioral funnel, at the bottom of which there is a mouth, or cytostome.
Mouth of infusoria shoe leads to a short channel - the cytopharynx, or pharynx. Both the perioral funnel and the pharynx can be lined with cilia, the movements of which direct a stream of water towards the cytostome, carrying with it various food particles, such as bacteria. A food vacuole is formed around the food particles that have entered the cytoplasm by endocytosis. These vacuoles move along the endoplasm to the so-called powder, through which undigested residues are brought out by exocytosis.
In the cytoplasm of ciliates shoes there are also two contractile vacuoles, the location of which in the cell is strictly fixed. These vacuoles are responsible for osmoregulation, that is, they maintain a certain water potential in the cell. Life in fresh water is complicated by the fact that water constantly enters the cell as a result of osmosis; this water must be continuously expelled from the cell to prevent it from bursting.
This happens with the help of the process of active transport, which requires the expenditure of energy. Around every contractile vacuole of ciliates shoe there is a series of radiating canals that collect water before releasing it into the central vacuole.
In a cage paramecium ciliates slippers there are two cores. Most of them - - polyploid; it has more than two sets of chromosomes and controls metabolic processes not related to reproduction. The micronucleus is a diploid nucleus. It controls the reproduction and formation of macronuclei during nuclear division.
Paramecium infusoria slippers It can reproduce both asexually (by transverse fission in two) and sexually (by conjugation).
About 6000 species of protozoa are classified as Ciliates, the organelles of which are a large number of cilia. Most ciliates are characterized by the presence of two nuclei: a large vegetative - macronucleus - and a smaller generative - micronucleus. The macronucleus has a polyploid set of chromosomes and regulates metabolic processes. The micronucleus contains a diploid set of chromosomes and is involved in the sexual process.
Free-living ciliates include ciliate slipper. Cell dimensions are 0.1-0.3 mm. The simplest has a constant shape, since the ectoplasm is compacted and forms a pellicle. The body of the ciliate is covered with cilia. They number from 10 to 15 thousand. In the ectoplasm, ciliates have protective formations - trichocysts. When irritated, trichocysts shoot outward, turning into long threads that paralyze the victim. After using some trichocysts, new ones develop in their place in the ectoplasm.
Nutritional organelles include the oral opening located on the ventral side and leading to the cellular mouth, which passes into the cellular pharynx. Water with bacteria through the mouth enters the endoplasm, where digestive vacuoles are formed. Vacuoles move along the body of the ciliate.
The undigested food residues remaining inside the vacuole are removed outward through the powder - a hole located near the posterior end of the body of the ciliate.
The shoe ciliate has two contractile vacuoles located in the front and back of the body. Each vacuole consists of a rounded reservoir and 5-7 tubules approaching it in the form of a star. Liquid products and water from the cytoplasm first enter the adductor tubules, then the tubules all at once contract and pour their contents into the reservoir, after which the latter contracts and ejects the liquid through the hole to the outside, and the tubules at this time refill. The vacuoles contract one by one.
Asexual reproduction of ciliates is carried out by transverse division and is accompanied by the division of macro- and micronuclei. Reproduction is repeated 1 - 2 times a day. After several generations in the life cycle of ciliates, a sexual process occurs, which is called conjugation. Two ciliates approach each other with their ventral sides, the shell dissolves at the point of contact, and a cytoplasmic bridge forms between them. In this case, macronuclei are destroyed, and micronuclei are divided by meiosis into four nuclei, three of which are destroyed, and the fourth is again divided in half by mitosis.
As a result, male (migratory) and female (stationary) nuclei are formed in each ciliate. Then, between individuals, the exchange of migrating nuclei occurs, followed by the fusion of the stationary and migrating nuclei, after which the individuals disperse. Soon, in each of them, the nucleus divides and subsequently micro- and macronuclei are formed. Thus, during the sexual process, the number of ciliates does not increase, but the hereditary properties of the macronucleus are updated and new combinations of genetic information arise.
Diagnosis is made by finding balantidia in feces. Prevention is the same as for other intestinal diseases.
Structure
The most typical widespread representative of the ciliary is the shoe ciliate (Paramecium). It lives in stagnant water, as well as in freshwater bodies with a very weak current, containing decaying organic material.
The complexity of the cell structure in paramecia is explained by the fact that it has to perform all the functions inherent in the whole organism, namely nutrition, osmoregulation and movement. The body of the paramecium has a characteristic shape: its anterior end is blunt, and the posterior end is somewhat pointed.
Cilia ciliates shoes arranged in pairs over the entire surface of the cell. Located in longitudinal diagonal rows, they, making beatings, make the ciliate rotate and move forward. Between the cilia are holes leading to special chambers called trichocysts. From these chambers, under the influence of certain stimuli, thin pointed threads can shoot out, probably used to hold prey.
Under the pellicle of ciliates shoes ectoplasm is located - a transparent layer of dense cytoplasm of the gel consistency. In the ectoplasm there are basal bodies (identical to centrioles) from which cilia extend, and between the basal bodies there is a network of thin fibrils involved, apparently, in coordinating the beating of cilia.
The bulk cytoplasm of ciliates slippers represented by endoplasm, which has a more liquid consistency than ectoplasm. It is in the endoplasm that most of the organelles are located. On the ventral (lower) surface of the shoe, closer to its front end, there is a perioral funnel, at the bottom of which there is a mouth, or cytostome.
Mouth of infusoria shoe leads to a short channel - the cytopharynx, or pharynx. Both the perioral funnel and the pharynx can be lined with cilia, the movements of which direct a stream of water towards the cytostome, carrying with it various food particles, such as bacteria. A food vacuole is formed around the food particles that have entered the cytoplasm by endocytosis. These vacuoles move along the endoplasm to the so-called powder, through which undigested residues are brought out by exocytosis.
In the cytoplasm of ciliates shoes there are also two contractile vacuoles, the location of which in the cell is strictly fixed. These vacuoles are responsible for osmoregulation, that is, they maintain a certain water potential in the cell. Life in fresh water is complicated by the fact that water constantly enters the cell as a result of osmosis; this water must be continuously expelled from the cell to prevent it from bursting.
This happens with the help of the process of active transport, which requires the expenditure of energy. Around every contractile vacuole of ciliates shoe there is a series of radiating canals that collect water before releasing it into the central vacuole.
In a cage paramecium ciliates slippers there are two cores. The larger of them - the macronucleus - is polyploid; it has more than two sets of chromosomes and controls metabolic processes not related to reproduction. The micronucleus is a diploid nucleus. It controls the reproduction and formation of macronuclei during nuclear division.
Paramecium infusoria slippers It can reproduce both asexually (by transverse fission in two) and sexually (by conjugation).
Motion
Making wave-like movements with cilia, the shoe moves (floats with a blunt end forward). The eyelash moves in one plane and makes a direct (effective) blow in a straightened state, and a return blow in a curved state. Each next eyelash in a row strikes with a slight delay compared to the previous one. Floating in the water column, the shoe rotates around the longitudinal axis. The movement speed is about 2 mm/s. The direction of movement can change due to the bending of the body. When hitting an obstacle, the direction of the direct impact is reversed and the shoe bounces back. Then it “swings” back and forth for a while, and then starts moving forward again. Upon collision with an obstacle, the cell membrane depolarizes, and calcium ions enter the cell. In the "rocking" phase, calcium is pumped out of the cell
Respiration, excretion, osmoregulation
The shoe breathes the entire surface of the cage. It is able to exist due to glycolysis at a low concentration of oxygen in water. The products of nitrogen metabolism are also excreted through the cell surface and partially through the contractile vacuole. The main function of contractile vacuoles is osmoregulatory. They remove excess water from the cell, penetrating there due to osmosis. First, the leading channels swell, then the water from them is pumped into the tank. When the reservoir shrinks, it separates from the supply channels, and water is ejected through the pore. Two vacuoles work in antiphase, each under normal physiological conditions is reduced once every 10-15 s. In an hour, vacuoles eject from the cell a volume of water approximately equal to the volume of the cell.
reproduction
The shoe has asexual and sexual reproduction (sexual process). Asexual reproduction - transverse division in the active state. It is accompanied by complex regeneration processes. For example, one of the individuals re-forms a cell mouth with a perioral cilia, each completes the missing contractile vacuole, the basal bodies multiply and new cilia form, etc.
The sexual process, like that of other ciliates, occurs in the form of conjugation. Shoes belonging to different clones are temporarily "glued" by their mouth sides, and a cytoplasmic bridge is formed between the cells. Then the macronuclei of the conjugating ciliates are destroyed, and the micronuclei are divided by meiosis. Of the four haploid nuclei formed, three die, and the remaining one divides by mitosis. Each ciliate now has two haploid pronuclei - one is female (stationary) and the other is male (migratory). Ciliates exchange male pronuclei, while females remain in "their" cell. Then, in each ciliate, "own" female and "alien" male pronuclei merge, forming a diploid nucleus - a synkaryon. When the synkaryon divides, two nuclei are formed. One of them becomes a diploid micronucleus, and the second turns into a polyploid macronucleus. In reality, this process is more complicated and is accompanied by special post-conjugation divisions.
Suvoyka
A genus of protozoa from the subclass of ciliated ciliates (Peritricha). Includes over 100 widespread species living in sea and fresh water. S. are sessile animals, attached to the substrate (unlike other genera Peritricha) with the help of a non-branching contractile stalk. S.'s body, shaped like a bell, is devoid of cilia. At its extended front end (adoral zone) there is a double row of eyelashes (usually merging into memoranella), twisted to the left (in contrast to spiral ciliary ciliates, in which the adoral zone of membranell is twisted to the right). The perioral spiral leads to the mouth opening. S. feed on small organic particles suspended in water (for example, bacteria, detritus). During asexual reproduction, as a result of division, free-floating "tramps" equipped with a corolla of eyelashes are formed, which then form a stalk and attach to the substrate. Sexual process - according to the type of anisogamous conjugation (large immobile macroconjugants and small mobile microconjugants).
Infusoria trumpeter
A genus of the simplest class of ciliates of the suborder of ciliary. Length up to 1 mm. Over 10 types. Funnel shaped body. At the expanded anterior end there is a powerfully developed zone of perioral membranolls that direct the flow of food particles to the mouth opening. The rest of the body is covered with longitudinal rows of small cilia. They are able to contract sharply, taking on a spherical shape due to contractile filaments - myonemes. They can float freely or attach to the substrate with a narrowed rear end. They live in the seas and fresh waters. Some species in the cytoplasm have numerous symbionts - unicellular algae.
Infusoria-stylochonia
There is such an infusoria - stylonychia. Under the influence of volatile onion phytoncides, it breaks up into tiny grains and even dissolves. Microbiologists call this phenomenon lysis. The body of the infusoria "disappears". The same thing happens with the infusoria called "loxodes rostrum". Within 10-15 seconds, her entire body dissolves in the surrounding liquid medium!
Under exactly the same conditions, another ciliate - spirostomum teres - under the influence of the same phytoncides breaks up into grains, but the dissolution of the whole body does not occur. We call this death grainy decay.
This is a fairly common type of protozoan organisms that live in fresh water bodies with stagnant water. The main condition for the habitation of ciliates-shoes are stagnant water bodies with a sufficient amount of organic materials in them that serve as food for these protozoa. The second name of this creature is the tailed paramecia of the genus Paramecium. It is curious that the structure of the shoe ciliates is the most complex of all representatives of this group of organisms.
Infusoria shoe. Structure
This single-celled organism got its name because of the resemblance to the sole of a shoe. It is curious that such an unusual shape of this creature is due to the dense outer layer of the cytoplasm. The entire body of the ciliates-shoes is covered with tiny cilia (flagella) located in longitudinal rows. It is they who help the ciliates move in the aquatic environment: in 1 second, the simplest can cover a distance 15 times greater than itself. The infusoria-shoe moves with a blunt end forward, constantly rotating during movement around its own axis.
Between the flagella of the ciliates are trichocysts - small spindle-shaped organelles that provide it with protection from external stimuli. Each such trichocyst consists of a body and a tip, which reacts to any stimulus (heating, collision, cooling) with a sharp shot. The mouth of this simplest organism has a funnel-shaped shape: when food enters it, it is surrounded by a food vacuole, making a short “journey” with it until it is digested. Waste is thrown out through the so-called powder (a specific organelle).
The bulk of these creatures is the endoplasm (the liquid part of the cytoplasm). Ectoplasm is next to cytoplasmic membrane, having a denser consistency and forming a pellicle. The ciliate shoe absorbs oxygen with its entire surface, existing even at its low concentration in water. All this allows us to rightfully call ciliates-shoes the most highly organized protozoa, the pinnacle of their evolution.
Infusoria shoe. reproduction
This unicellular organism reproduces in two ways: asexual and sexual. Asexual reproduction occurs due to the transverse division of the cell into two equal parts. At the same time, the organism of the ciliates retains its activity. Further, complex regeneration processes take place, as a result of which each of the parts of the body "finishes" all the necessary organelles.
The sexual method of reproduction of ciliates-shoes, for obvious reasons, looks somewhat different. Two individuals temporarily "stick together" with each other, forming between themselves a kind of bridge from the cytoplasm. At this time, the macronuclei of both organisms are destroyed, and the smallest nucleoli begin to divide by meiosis.
After some time, four nuclei appear, three of which are sure to die. The remaining nucleus divides by mitosis. As a result, two protonuclei are formed - male and female. Both individuals begin to exchange "male" protonuclei, after which an additional fusion of two nuclei occurs in each of them, accompanied by the formation of a synkaryaon. As a result of the next mitosis, one of the newly minted nuclei becomes a micronucleus, and the second becomes a macronucleus.