What are colonial organisms made of? unicellular organisms

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colonial organism- a term that combines two groups of organisms:

Organisms consisting of many cells, poorly differentiated and not divided into tissues; in many cases, each such cell retains the ability to reproduce (Volvox green algae, etc., many species of jack-o'-lanterns, and other groups of protists).
Multicellular organisms that form colonies of several individuals more or less closely related, usually sharing the same genotype and common metabolism and regulatory systems. Among animals, such organisms include many types of coral polyps, bryozoans, sponges, etc. In botany, the term “modular” (as opposed to unitary) is used to refer to such organisms - these are, for example, rhizomatous cereals, lily of the valley, etc.

Distinctive features of colonial organisms

Colonial protists differ from true multicellular organisms primarily in a lower level of integrity (for example, individual individuals often react to individual stimuli, and not the entire colony as a whole), and colonial protists also have a lower level of cell differentiation. In many highly integrated mobile colonies (sea feathers, siphonophores, etc.), the level of integrity reaches the level of a single organism, and individual individuals act as organs of the colony. Such (and many other) colonies have a common part (stem, trunk) that does not belong to any of the individuals.

colony formation

Most colonial organisms have single stages in their life cycle. Usually, after sexual reproduction, development begins with a single cell, which in multicellular animals gives rise to the original multicellular individual. She, in turn, gives rise to a colony as a result of asexual or vegetative reproduction that has not been completed.
In some protists and bacteria, formations similar to colonies (for example, the fruiting bodies of myxomycetes or myxobacteria) can also be formed in another way - by combining initially independent single individuals.

Examples

Prominent representatives of colonial organisms are colonial green algae (for example, Pandorina, Eudorine, as well as volvox, which is a transitional form to true multicellular organisms). Colonial forms are also widespread among other groups of algae - diatoms, golden, etc. There are also many colonial forms among heterotrophic flagellates and ciliates. There are colonial radiolarians.

Most of the animals are colonial

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Coloniesunicellularorganisms

unicellularorganigm molecular vitamin

Unicellular organisms are a non-systematic category of living organisms, the body of which consists of one (unlike multicellular) cells (unicellularity). It can include both prokaryotes and eukaryotes. The term "unicellular" is also sometimes used as a synonym for protist (lat. Protozoa, Protista).

The main groups of unicellular:

Ciliates (12 microns - 3 mm)...

Amoeba (up to 0.3 mm)

Eyelash

Prokaryotes are predominantly unicellular, with the exception of some cyanobacteria and actinomycetes. Among eukaryotes, protozoa, a number of fungi, and some algae have a unicellular structure. Unicellular organisms can form colonies.

Colony (lat. colonia) - in biology, this is the ratio of individual organisms of the same species living together, usually on the basis of mutual benefit, for example, to protect or attack large prey. Some species (such as honey bees and ants) live exclusively in colonies. The species is the Portuguese boat (Physaliaphysalis), one of the examples of polyp forms of a colony. Colonies of unicellular organisms are called a colonial organism.

Colonial organism is a term that combines two groups of organisms:

Organisms consisting of many cells, poorly differentiated and not divided into tissues; in many cases, each such cell retains the ability to reproduce (volvox green algae Pandorina, Eudorine, etc., many species of sandwort and other groups of protists).

Multicellular organisms that form colonies of several individuals more or less closely related, usually sharing the same genotype and common metabolism and regulatory systems. Among animals, such organisms include many types of coral polyps, bryozoans, sponges, etc. In botany, the term “modular” (as opposed to unitary) is used to designate such organisms - these are, for example, rhizomatous cereals, lily of the valley, etc.

Prominent representatives of colonial organisms are colonial green algae (for example, Eudorina, Pandorina, and Volvox, which is a transitional form to true multicellular organisms). Colonial forms are also widespread among other groups of algae - diatoms, golden, etc. There are also many colonial forms among heterotrophic flagellates and ciliates. There are colonial radiolarians.

Colonial animals include most sponges and coelenterates (coral polyps, hydroid polyps, siphonophores), almost all bryozoans and camptozoa, many tunicates, and some wing gills). In many groups of animals, temporary colonies are formed during asexual reproduction.

Most colonial organisms have single stages in their life cycle. Usually, after sexual reproduction, development begins with a single cell, which in multicellular animals gives rise to the original multicellular individual. It, in turn, gives rise to a colony as a result of incomplete asexual or vegetative reproduction. In some protists and bacteria, formations similar to colonies (for example, the fruiting bodies of myxomycetes or myxobacteria) can also be formed in another way - by combining initially independent single individuals.

It is believed that the first living organisms on Earth were single-celled. The most ancient of them are bacteria and archaea. Unicellular animals and prokaryotes were discovered by A. Leeuwenhoek.

Eukaryotes, or Nuclear (lat. Eucaryota from the Greek ee- - good and kbshpn - core) - the domain (superkingdom) of living organisms whose cells contain nuclei. All organisms except bacteria and archaea are nuclear (viruses and viroids are also not eukaryotes, but not all biologists consider them to be living organisms).

Animals, plants, fungi, and the group of organisms collectively called protists are all eukaryotic organisms. They can be unicellular and multicellular, but all have a common cell plan. It is believed that all these dissimilar organisms have a common origin, so the nuclear group is considered as a monophyletic taxon of the highest rank. According to the most common hypotheses, eukaryotes appeared 1.5-2 billion years ago. An important role in the evolution of eukaryotes was played by symbiogenesis - a symbiosis between a eukaryotic cell, apparently already having a nucleus and capable of phagocytosis, and bacteria swallowed by this cell - precursors of mitochondria and chloroplasts.

Interactionregulatorysystemsinbody

The vital activity of the organism is under the constant influence of numerous disturbing factors. A reaction that is a response to a particular impact, as a rule, is not limited to one system. All systems of the body as a whole participate in it, since this reaction is the result of a number of complex and interrelated regulatory processes aimed at maintaining a steady state. As a result of this interaction, the functional level of the organism undergoes constant changes.

The interaction of regulatory systems can be most easily traced if the body is brought out of equilibrium by acting on it with a supraphysiological stimulus. At the same time, various changes occur in the body, among which one can often note the mobilization of adrenaline, ACTH, corticosteroids, hyperglycemia, increased protein and fat catabolism, gluconeogenesis, the appearance of non-phosphorylated oxidation and increased glycolytic processes, changes in the mechanisms of heat generation and heat transfer, redistribution of blood flow, changes in the volume of circulating blood, the release of incompletely oxidized metabolic products into the bloodstream, a decrease in the buffer capacity of the blood, a change in the filtration function of the kidneys, an increase in cardiovascular activity and respiration, etc.

After the elimination of the disturbing factor, energy needs are satisfied by new values of the volumetric and linear blood flow velocity, frequency and depth of respiration, increased delivery of energy substrates, vitamins, hormones, microelements, electrolytes, etc. to the cells of the body. In this case, in the case of continued exposure, the equilibrium state can be established at new, higher or lower functional level.

A variety of processes in the body are coordinated, interconnected and interdependent. Thus, an increase in heat generation leads to an increase in effective heat transfer, and the additional capacity of the vascular system is filled with blood mobilized from the depot. The regimes of blood flow and alveolar ventilation change in such a way that new conditions for gas exchange are created. The increased concentration of potassium in the blood, which adversely affects the activity of the heart, is reduced by renal filtration. An increase in the rate of blood flow through the capillaries favors an increased intensity of cellular oxidation, etc.

The most complex and interesting question is how, after the impact of a perturbing factor, some new, equilibrium state of the system is ensured.

Perturbation can lead to complete disorganization of the body. However, regulatory systems continuously monitor the state of functions and act on them, preventing unacceptable deviations of variables. In this case, both strengthening and weakening of some regulated function can be noted. For example, the mechanisms of convection, radiation and perspiration increase the efficiency of heat transfer. Ventilation and renal function reduce the concentration of hydrogen ions in the blood, leaching of the substrate from the cell slows down the rate of enzyme-substrate interaction (see, for example, the work of M. Dixon and E. Webb, 1961).

The intensity of cellular oxidation varies depending on the enzymatic system, substrates to be oxidized, end products of oxidation, cell temperature, pH, oxygen tension (/S). The p02 level of a cell depends on blood p02, cell irrigation, and linear blood flow velocity. Oxygen tension in arterial blood depends on blood oxygen saturation pH, pCO2, electrolyte concentration and blood temperature. In turn, these indicators depend on the function of the heart, ventilation modes, etc.

Thus, a single complex of cause-and-effect relationships of a multi-loop, homeostatic "system" is formed, where each cause is simultaneously a consequence, and the output variables of some subsystems simultaneously serve as input "Signals for other subsystems.

This complex can be represented as a set of indirect effects, when each variable has a direct or indirect effect on any other variable. Naturally, this influence manifests itself in different ways in different situations. Under conditions of physiological rest, the activity of all body systems is finely coordinated: the same amount of oxygen enters through the alveoli into the arterial blood, and is carried by the blood to the tissues. At the same time, all systems are “in equal conditions”, none of them interferes with the work of others, they work as if they are links in one chain, which is why the term “oxygen relay race” is so successful when applied to the so-called oxygen regime regulation system (A. 3. Kolchinskaya et al., 1966). Similar "chains" can be distinguished for other substrates - glucose, salts, proteins, etc. The same sequence of reactions can be considered for thermal energy.

All these chains form a single complex in which they are closely (intertwined, often have a common material carrier (for example, blood or lymph), being spatially localized in the same tissues of the body, sometimes using the same structures. With all this, under conditions At rest, the perturbing influence of one system on another is minimized.In practice, they function without intersecting, independently of each other.Thus, under conditions of comfort, the thermoregulation system does not have a perturbing effect on breathing and blood circulation and, in turn, is not affected by them.

Of course, the interaction of systems does not stop under any conditions, and the small influence on this system from the other systems just allows all systems, almost without changing their state, to maintain the consistency of functioning.

A similar situation is observed in the theory of automatic control in the study of complex (so-called multiply connected) control systems. It turns out that if in such systems it is required to change some output signal by a given value, then this can be achieved either by a large, rough change in one of the input signals of this system, or by small changes in several input signals at the same time (E. Mishkin and L. Brown, 1961).

If under conditions of physiological rest all regulatory systems act on an equal footing, act independently, as if in isolation, then under stressful conditions, the regulatory systems sometimes find themselves in very complex relationships. At the same time, "buffer mechanisms that isolate systems from each other are exhausted, and there are effects of a direct perturbing effect of some systems on others - the effects of hierarchical influences, dominance, competitive relationships. This is illustrated by an example of the interaction of blood pressure regulation systems and thermoregulation. The activity of the first in extreme conditions can be aimed at narrowing the blood vessels of the skin, the second - at expansion.In case of intense load in conditions of high ambient temperature, the action of the thermoregulation system predominates, which can sometimes lead to thermal collapse (G. Hensel, 1960).

Immunity is a physiological function that ensures the body's resistance to the action of foreign antigens. Human immunity makes it immune to many bacteria, viruses, fungi, worms, protozoa, various animal poisons, and protects the body from cancer cells. The task of the immune system is to recognize and destroy all foreign structures.

The immune system is the regulator of homeostasis. This function is carried out due to the production of autoantibodies, which, for example, can bind excess hormones.

The immunological reaction, on the one hand, is an integral part of the humoral one, since most physiological and biochemical processes are carried out with the direct participation of humoral mediators. However, often the immunological reaction is targeted and thus resembles nervous regulation. The intensity of the immune response, in turn, is regulated in a neurophilic way. The work of the immune system is corrected by the brain and through the endocrine system. Such nervous and humoral regulation is carried out with the help of neurotransmitters, neuropeptides and hormones. Promediators and neuropeptides reach the organs of the immune system along the axons of the nerves, and hormones are secreted by the endocrine glands unrelatedly into the blood and thus delivered to the organs of the immune system.

Physiological processes in the human body proceed in a coordinated manner due to the existence of certain mechanisms of their regulation. The regulation of various processes in the body is carried out with the help of nervous and humoral mechanisms.

Humoral regulation is carried out with the help of humoral factors (hormones), which are carried by blood and lymph throughout the body.

nervousregulationcarried outwithhelpnervoussystems

Nervous and humoral methods of regulation of functions are closely related. The activity of the nervous system is constantly influenced by chemicals brought with the bloodstream, and the formation of most chemicals and their release into the blood is under constant control of the nervous system.

The regulation of physiological functions in the body cannot be carried out with the help of only nervous or only humoral regulation - this is a single complex of neurohumoral regulation of functions.

Recently, it has been suggested that there are not two regulatory systems (nervous and humoral), but three (nervous, humoral and immune).

nervousregulation

Nervous regulation is the coordinating influence of the nervous system on cells, tissues and organs, one of the main mechanisms for self-regulation of the functions of the whole organism. Nervous regulation is carried out with the help of nerve impulses. Nervous regulation is fast and local, which is especially important in the regulation of movements, and affects all (!) Systems of the body.

The reflex principle underlies the nervous regulation. A reflex is a universal form of interaction between the body and the environment; it is the body's response to irritation, which is carried out through the central nervous system and is controlled by it.

The structural and functional basis of the reflex is the reflex arc - a series-connected chain of nerve cells that provides a response to irritation. All reflexes are carried out due to the activity of the central nervous system - the brain and spinal cord.

humoralregulation

Humoral regulation is the coordination of physiological and biochemical processes carried out through the liquid media of the body (blood, lymph, tissue fluid) with the help of biologically active substances (hormones) secreted by cells, organs and tissues in the course of their life.

Humoral regulation arose in the process of evolution earlier than nervous regulation. It became more complicated in the process of evolution, as a result of which the endocrine system (endocrine glands) arose.

Humoral regulation is subordinate to nervous regulation and together with it constitutes a single system of neurohumoral regulation of body functions, which plays an important role in maintaining the relative constancy of the composition and properties of the internal environment of the body (homeostasis) and its adaptation to changing conditions of existence.

Roleunicellularorganismsinnatureandlifehuman

Protozoa are a food source for other animals. In the seas and in fresh waters, protozoa, primarily ciliates and flagellates, serve as food for small multicellular animals. Worms, mollusks, small crustaceans, as well as fry of many fish feed mainly on unicellular ones. These small multicellular organisms, in turn, feed on other, larger organisms. The largest animal that has ever lived on Earth, the blue whale, like all other baleen whales, feeds on very small crustaceans that inhabit the oceans. And these crustaceans feed on single-celled organisms. Ultimately, the existence of whales depends on single-celled animals and plants.

The simplest are participants in the formation of rocks. Examining a crushed piece of ordinary writing chalk under a microscope, one can see that it consists mainly of the smallest shells of some animals. Marine protozoa (rhizopods and radiolarians) play a very important role in the formation of marine sedimentary rocks. For many tens of millions of years, their microscopically small mineral skeletons settled to the bottom and formed thick deposits. In ancient geological epochs, during the mountain-building process, the seabed became dry land. Limestones, chalk and some other rocks are largely composed of the remains of the skeletons of marine protozoa. Limestones have long been of great practical importance as a building material.

The study of fossil remains of protozoa plays an important role in determining the age of different layers of the earth's crust and finding oil-bearing layers.

The fight against pollution of water bodies is the most important state task. The simplest are an indicator of the degree of pollution of fresh water bodies. Each species of protozoan animals needs certain conditions for existence. Some protozoa live only in clean water, containing a lot of dissolved air and not polluted by waste from factories and plants; others are adapted to life in moderately polluted water bodies. Finally, there are some protozoa that can live in very polluted, sewage waters. Thus, the presence of a certain type of protozoa in a reservoir makes it possible to judge the degree of its pollution.

So, the simplest are of great importance in nature and in human life. Some of them are not only useful, but necessary; others, on the contrary, are dangerous.

Viruses--non-cellularformslife

Along with unicellular and multicellular organisms, there are other forms of life in nature. These are viruses that do not have a cellular structure. They represent a transitional form between inanimate and living matter.

Viruses (lat. virus - poison) were discovered in 1892 by the Russian scientist D.I. Ivanovsky in the study of mosaic disease of tobacco leaves.

Each viral particle consists of RNA or DNA enclosed in a protein coat called a capsid. A fully formed infectious particle is called a virion. Some viruses (for example, herpes or influenza) also have an additional lipoprotein envelope that arises from the plasma membrane of the host cell.

Since viruses always contain one type of nucleic acid - DNA or RNA, viruses are also divided into DNA-containing and RNA-containing. In this case, along with double-stranded DNA and single-stranded RNA, there are single-stranded DNA and double-stranded RNA. DNA can have linear and circular structures, while RNA is usually linear. The vast majority of viruses are of the RNA type.

Viruses can only replicate in the cells of other organisms. Outside the cells of organisms, they do not show any signs of life. Many of them in the external environment have the form of crystals. Virus sizes range from 20 to 300 nm in diameter.

The tobacco mosaic virus, which has a rod-shaped form and is a hollow cylinder, has been well studied. The cylinder wall is formed by protein molecules, and an RNA helix is located in its cavity (Fig. 5.2). The protein shell protects the nucleic acid from adverse environmental conditions, and also prevents the penetration of cell enzymes to RNA and its cleavage.

Viral RNA molecules can reproduce themselves. This means that viral RNA is a source of genetic information and at the same time mRNA. Therefore, in the affected cell, in accordance with the virus nucleic acid program, specific viral proteins are synthesized on the ribosomes of the host cell and the process of self-assembly of these proteins with the nucleic acid into new viral particles is carried out. The cell becomes exhausted and dies. When affected by some viruses, cells are not destroyed, but begin to divide intensively, often forming malignant tumors in animals, including humans.

Bacteriophages. A special group is represented by bacterial viruses - bacteriophages, or phages that are able to penetrate into a bacterial cell and destroy it.

The body of the Escherichia coli phage consists of a head, from which a hollow rod extends, surrounded by a sheath of contractile protein. The rod ends with a basal plate, on which six threads are fixed (see Fig. 5.2). Inside the head is DNA. The bacteriophage attaches to the surface of E. coli with the help of processes and dissolves the cell wall with the help of an enzyme at the point of contact with it. After that, due to head contraction, the phage DNA molecule is injected through the rod channel into the cell. Approximately 10-15 minutes later, under the action of this DNA, the entire metabolism of the bacterial cell is rebuilt, and it begins to synthesize bacteriophage DNA, and not its own. At the same time, phage protein is also synthesized. The process ends with the appearance of 200-1,000 new phage particles, as a result of which the bacterial cell dies.

Bacteriophages that form a new generation of phage particles in infected cells, which leads to lysis (decay) of the bacterial cell, are called virulent phages.

Some bacteriophages do not replicate inside the host cell. Instead, their nucleic acid is incorporated into the host's DNA, forming with it a single molecule capable of replication. Such phages are called temperate phages or prophages.

Viral diseases. Settling in the cells of living organisms, viruses cause dangerous diseases of many agricultural plants (mosaic disease of tobacco, tomatoes, cucumbers; leaf curling, dwarfism, jaundice, etc.) and domestic animals (foot and mouth disease, plague in pigs and birds, infectious anemia in horses, cancer and etc.). These diseases drastically reduce crop yields and lead to mass death of animals. Viruses also cause many dangerous human diseases: influenza, measles, smallpox, poliomyelitis, mumps, rabies, yellow fever, etc. In recent years, another terrible disease has been added to them - AIDS.

AIDS - Acquired Immune Deficiency Syndrome - is an epidemic disease that primarily affects the human immune system, which protects it from various pathogens. Damage to the cellular immune system leads to infectious diseases and malignant tumors. The body becomes defenseless to microbes that normally do not cause disease.

The causative agent of the disease is the human immunodeficiency virus (HIV). The HIV genome is represented by two identical RNA molecules, consisting of approximately 10 thousand base pairs. At the same time, HIV isolated from various AIDS patients differ from each other in the number of bases (from 80 to 1,000).

HIV has a unique variability that is five times greater than that of the influenza virus and one hundred times greater than that of the hepatitis B virus. The continuous genetic and antigenic variability of the virus in the human population leads to the emergence of new HIV virions, which greatly complicates the problem of obtaining a vaccine and makes it difficult to conduct special AIDS prevention. Moreover, this property of HIV, according to some experts, casts doubt on the very fundamental possibility of creating an effective vaccine to protect against AIDS.

One of the manifestations of human infection with the AIDS virus is damage to the central nervous system. Typical symptoms specific to AIDS have not been identified.

AIDS is characterized by a very long incubation period (calculated from the moment of defeat until the first signs of the disease appear). In adults, it averages 5 years. It is assumed that HIV can persist in the human body for life. This means that for the rest of their lives, infected people can infect others, and under the right conditions, they themselves can become ill with AIDS.

One of the main ways of transmitting HIV and spreading AIDS is through sexual contact, since the pathogen is most often found in the blood, semen and vaginal secretions of infected people.

Another way of infection is the use of non-sterile medical instruments, which are often used by drug addicts. It is also possible to transmit the infection through blood and some drugs, during transplantation of organs and tissues, using donor sperm, etc. Infection can also occur during gestation, during the birth of a child or during breastfeeding by a mother infected with HIV or AIDS.

The leading risk factors in the spread of this disease are also prostitution and the frequent change of sexual partners in both homo- and bisexual, and heterosexual transmission of the infection. According to various estimates, in married couples, transmission of infection from one of the infected occurs at a frequency of 35 to 60%. The consequences of the spread of infection and its impact on health are unpredictable.

The guarantee of safety from AIDS is a healthy lifestyle, the strength of marriage and family, a negative attitude towards sexual perversion and promiscuity, casual sex. As a special preventive measure, the use of physical contraceptives - condoms - should be highlighted.

stemcells

Stem cells are undifferentiated (immature) cells found in all multicellular organisms. Stem cells are capable of self-renewal, forming new stem cells, dividing through mitosis and differentiating into specialized cells, that is, turning into cells of various organs and tissues.

The development of multicellular organisms begins with a single stem cell, the zygote. As a result of numerous cycles of division and the process of differentiation, all types of cells characteristic of a given biological species are formed. There are more than 220 such types of cells in the human body. Stem cells are preserved and function in the adult body, thanks to them renewal and restoration of tissues and organs can be carried out. However, as the body ages, their number decreases.

In modern medicine, human stem cells are transplanted, that is, they are transplanted for medicinal purposes. For example, transplantation of hematopoietic stem cells is performed to restore the process of hematopoiesis (hematopoiesis) in the treatment of leukemia and lymphomas.

Embryonic stem cells (ESCs) form the inner cell mass (ICM), or embryoblast, at an early stage of embryonic development. They are pluripotent. An important advantage of ESCs is that they do not express HLA (humanleucocyteantigens), that is, they do not produce tissue compatibility antigens. Each person has a unique set of these antigens, and their mismatch between the donor and recipient is the most important cause of incompatibility in transplantation. Accordingly, the chance that donor embryonic cells will be rejected by the recipient's body is very low. When transplanted into immunodeficient animals, embryonic stem cells are able to form tumors of a complex (multi-tissue) structure - teratomas, some of which can become malignant. There is no reliable data on how these cells behave in an immunocompetent organism, for example, in the human body. At the same time, it should be noted that clinical trials using differentiated derivatives (derived cells) of ESCs have already begun. To obtain ESCs in the laboratory, it is necessary to destroy the blastocyst in order to isolate the ECM, that is, to destroy the embryo. Therefore, researchers prefer not to work with embryos directly, but with ready-made, previously isolated ESC lines.

Clinical studies using ESCs are subject to special ethical review. In many countries, ESC research is restricted by law.

One of the main disadvantages of ESCs is the impossibility of using autogenous, i.e. own material, during transplantation, since the isolation of ESCs from an embryo is incompatible with its further development.

Fetal stem cells are obtained from the fetal material after an abortion (usually the gestational age, that is, intrauterine development of the fetus, is 9-12 weeks). Naturally, the study and use of such biomaterial also gives rise to ethical problems. In some countries, for example, in Ukraine and the UK, work continues on their study and clinical application. For example, the British company ReNeuron is exploring the possibility of using fetal stem cells for stroke therapy.

Despite the fact that stem cells of a mature organism have a lower potency than embryonic and fetal stem cells, that is, they can give rise to a smaller number of different cell types, the ethical aspect of their research and use does not cause serious controversy. In addition, the possibility of using autogenous material ensures the effectiveness and safety of treatment. Stem cells of an adult organism can be divided into three main groups: hematopoietic (hematopoietic), multipotent mesenchymal (stromal) and tissue-specific progenitor cells. Sometimes umbilical cord blood cells are isolated into a separate group, since they are the least differentiated of all cells of a mature organism, that is, they have the greatest potency. Cord blood mainly contains hematopoietic stem cells, as well as multipotent mesenchymal stem cells, but it also contains other unique varieties of stem cells that, under certain conditions, are capable of differentiating into cells of various organs and tissues.

Hematopoietic stem cells (HSCs) are multipotent stem cells that give rise to all blood cells of the myeloid (monocytes, macrophages, neutrophils, basophils, eosinophils, erythrocytes, megakaryocytes and platelets, dendritic cells) and lymphoid series (T-lymphocytes, B-lymphocytes and natural killers). The definition of hematopoietic cells has been fundamentally revised over the past 20 years. Hematopoietic tissue contains cells with long and short term regeneration capabilities, including multipotent, oligopotent and progenitor cells. Myeloid tissue contains one HSC per 10,000 cells. HSCs are a heterogeneous population. There are three subpopulations of HSCs, according to the proportional ratio of lymphoid to myeloid progeny (L/M). Myeloid-oriented HSCs have a low L/M ratio (>0,<3), у лимфоидно ориентированных -- высокое (>ten). The third group consists of "balanced" HSCs, for which 3 ? L/M ? 10. Currently, the properties of various groups of HSCs are being actively studied, however, intermediate results show that only myeloid-oriented and “balanced” HSCs are capable of long-term self-reproduction. In addition, transplantation experiments have shown that each HSC group preferentially recreates its own blood cell type, suggesting that there is an inherited epigenetic program for each subpopulation.

The HSC population is formed during embryogenesis, that is, embryonic development. It has been proven that in mammals, the first HSCs are found in mesoderm regions called aorta, gonad and mesonephros, before the formation of bone marrow, the population expands in the fetal liver. Such studies contribute to the understanding of the mechanisms responsible for the genesis (formation) and expansion of the HSC population, and, accordingly, the discovery of biological and chemical agents (active substances) that can ultimately be used for the cultivation of HSCs in vitro.

Prior to the introduction of cord blood, the main source of HSCs was considered to be the bone marrow. This source is still widely used in transplantation today. HSCs are located in the bone marrow in adults, including the femur, ribs, sternum mobilizations, and other bones. Cells can be obtained directly from the thigh using a needle and syringe, or from the blood after pretreatment with cytokines, including G-CSF (granulocyte colony stimulating factor), which promotes the release of cells from the bone marrow.

The second most important and promising source of HSC is umbilical cord blood. The concentration of HSC in umbilical cord blood is ten times higher than in the bone marrow. In addition, this source has a number of advantages. The most important of them:

Age. Cord blood is collected at a very early stage in the life of the organism. Cord blood HSCs are maximally active, since they have not been exposed to the negative effects of the external environment (infectious diseases, unhealthy diet, etc.). Cord blood HSCs are able to create a large cell population in a short time.

Compatibility. The use of autologous material, i.e. own cord blood, guarantees 100% compatibility. Compatibility with brothers and sisters is up to 25%, as a rule, it is also possible to use the child's umbilical cord blood to treat other close relatives. By comparison, the odds of finding a suitable stem cell donor are between 1:1,000 and 1:1,000,000.

Multipotent mesenchymal stromal cells (MMSCs) are multipotent stem cells capable of differentiating into osteoblasts (bone tissue cells), chondrocytes (cartilage cells), and adipocytes (fat cells).

The precursors of MMSCs during the embryogenic period of development are mesenchymal stem cells (MSCs). They can be found in the distribution of mesenchyme, that is, the embryonic connective tissue.

The main source of MMSC is the bone marrow. In addition, they are found in adipose tissue and a number of other tissues with a good blood supply. There is some evidence that the natural tissue niche of MMSCs is located perivascularly around blood vessels. In addition, MMSCs were found in the pulp of milk teeth, amniotic (amniotic) fluid, cord blood, and Wharton's jelly. These sources are researched but rarely applied in practice. For example, the isolation of young MMSCs from Wharton's jelly is an extremely laborious process, since the cells in it are also located perivascularly. In 2005-2006, MMSC specialists officially determined a number of parameters that cells must meet in order to classify them as MMSC population. Articles have been published presenting the MMSC immunophenotype and directions of orthodox differentiation. These include differentiation into cells of bone, adipose and cartilaginous tissues. A number of experiments have been carried out to differentiate MMSCs into neuron-like cells, but researchers still doubt that the resulting neurons are functional. Experiments are also being carried out in the field of MMSC differentiation into myocytes - muscle tissue cells. The most important and most promising area of clinical application of MMSCs is co-transplantation with HSCs in order to improve the engraftment of a bone marrow sample or cord blood stem cells. Numerous studies have shown that human MMSCs can avoid transplant rejection, interact with dendritic cells and T-lymphocytes, and create an immunosuppressive microenvironment through the production of cytokines. It has been shown that the immunomodulatory functions of human MMSCs are enhanced when they are transplanted into an inflamed environment with elevated interferon gamma levels. Other studies contradict these findings, due to the heterogeneous nature of isolated MSCs and significant differences between them, depending on the cultivation method.

MSCs can be activated if necessary. However, their efficiency is relatively low. So, for example, muscle damage even after MSC transplantation heals very slowly. Currently, studies are underway on the activation of MSCs. Previous studies on intravenous transplantation of MSCs have shown that this method of transplantation often leads to a crisis of rejection and sepsis. Today, it is recognized that diseases of peripheral tissues, such as intestinal inflammation, are best treated not by transplantation, but by methods that increase the local concentration of MSCs.

Cane-specific progenitor cells (predecessor cells) are poorly differentiated cells that are located in various tissues and organs and are responsible for updating their cell population, that is, they replace dead cells. These include, for example, myosatellocytes (precursors of muscle fibers), precursor cells of lympho- and myelopoiesis. These cells are oligo- and unipotent, and their main difference from other stem cells is that progenitor cells can divide only a certain number of times, while other stem cells are capable of unlimited self-renewal. Therefore, their belonging to true stem cells is questioned. Neural stem cells, which also belong to the tissue-specific group, are being studied separately. They differentiate during the development of the embryo and during the fetal period, resulting in the formation of all the nervous structures of the future adult organism, including the central and peripheral nervous systems. These cells were also found in the CNS of an adult organism, in particular, in the subependymal zone, in the hippocampus, olfactory brain, etc. Despite the fact that most of the dead neurons are not replaced, the process of neurogenesis in the adult CNS is still possible due to neural stem cells, that is, the population of neurons can “recover”, however, this occurs in such a volume that it does not significantly affect the outcomes of pathological processes.

Characteristics of embryonic stem cells:

Pluripotency -- the ability to form any of the approximately 350 cell types of an adult organism (in mammals);

Homing - the ability of stem cells, when introduced into the body, to find the area of damage and fix there, performing the lost function;

Totipotency - the ability to differentiate into a whole organism (11 days after fertilization);

The factors that determine the uniqueness of stem cells are not located in the nucleus, but in the cytoplasm. This is an excess of mRNA of all 3 thousand genes that are responsible for the early development of the embryo;

Telomerase activity. With each replication, part of the telomeres is lost (see the Hayflick limit). Stem, germ and tumor cells have telomerase activity, the ends of their chromosomes are built up, that is, these cells are capable of undergoing a potentially infinite number of cell divisions, they are immortal.

Mmolecularvitaminshormonalfactorsgrowththemroleinlifehuman

In maintaining the life of higher organisms, the control of proliferation, differentiation, and directed cell movement plays a key role. The normal course of these processes ensures the correct development and protective reactions of the body. Constantly regenerating tissues (eg epithelium or blood cells) also require strict regulation of stem cell proliferation. Loss or weakening of control can lead to serious diseases, including cancer and atherosclerosis. The necessary regulation of cell proliferation, differentiation and cell motility is carried out by various mechanisms. One of them is the interaction of the cell with growth factors.

Growth factors are a group of protein molecules that induce DNA synthesis in a cell (Goustin A.S. ea, 1986). Later it was found that the range of effects on the cells of these components is much wider than originally thought. Thus, some proteins of this group, depending on the type of responding cells, can induce differentiation and suppress proliferation. In addition, they include regulatory polypeptides that modulate cell motility, but do not necessarily affect cell division (Stoker M. and Gherardi E., 1987). The main difference between growth factors and protein hormones is an autocrine mechanism of action or a paracrine mechanism of action (holocrine mechanism of action for hormones; Deuel T.F., 1987).

The first publications on the possibility of maintaining biological tissue fragments in vitro appeared 90 years ago, but the routine cultivation of individual cells became possible less than 50 years ago. Successful maintenance of the process of division of mammalian cells depends on the components of the culture medium. Traditionally, the culture medium consists of nutrients and vitamins in a buffered saline solution. The key component is animal serum, such as fetal bovine serum. Without such an additive, most cultured cells will not reproduce their own DNA and therefore will not proliferate. Later, a platelet-secreted polypeptide with a molecular weight of 30 kD and possessing mitogenic properties was isolated. It has been named platelet-derived growth factor (PDGF).

As with hormones, growth factors interact with their respective growth factor receptors with a high degree of affinity and can initiate multiple effects ranging from growth regulation, differentiation and gene expression to initiation of apoptosis. The effects of growth factors, unlike hormones, can last for several days.

Growth factors are usually small polypeptides that stimulate or inhibit the proliferation of certain cell types. As a rule, they are secreted by one cell and act on other cells, although it sometimes happens that they act on the same cells that secrete them. These factors are important for the developmental processes of the embryo and also for the maintenance of cellular balance in the adult organism. For example, for a balanced renewal of skin cells, intestines and the hematopoietic system. In all these cases, a relatively small number of pluripotent stem cells set the stage for the formation of a significantly larger number of progenitor cells, which then differentiate further into mature post-mitotic cells. The latter replace old cells that die, for example, due to apoptosis.

Growth factors act on their target cells, which differ from other cells by receptors exposed on the surface of cell membranes and characteristic of this particular cell type.

Eventually, the cell exits the G0 rest phase and begins to divide. The integral picture of the interactions of many factors with many cells is complex, especially since often even a single growth factor has several functions. Removal of growth factors from the medium does not always lead to a simple arrest of cell division, but often causes programmed cell death.

Growth factors not only mimic cell division, but, on the contrary, some of them inhibit this process. The role of the inhibitor, in particular, is performed by members of a large family of growth factors - TGF-beta. see Figure 5 cs and Table 2. Growth factors and their role in the normal body

Despite the huge variety of characterized growth factors and the enormous difference in cellular responses (reviewed by Cross M. andDexter T.M., 1991), general rules of regulation can be formulated:

1. To maintain the life of normal cells of higher organisms, their interaction with a unique combination of specific growth factors is absolutely necessary.

2. The same cell can interact with several growth factors; the same growth factor can affect different types of cells.

3. The level of expression of a given growth factor, as well as the susceptibility and nature of the response, are specific for each given cell type.

At the heart of cancer are violations of the control of proliferation, as well as cell interactions with each other. Often, neoplastic transformation affects the cell's own regulatory program - reactions to growth factors. The functions of most oncogenes are somehow connected with this.

The processes of cell proliferation and their gradual acquisition of a specialized character (differentiated) occur in the body in a highly ordered and coordinated manner. This ordering is based on the fact that as a result of intercellular interactions, various intracellular programs are activated that determine the behavior of the cell depending on the behavior of its neighbors and on the needs of the organism. A key role in intercellular signaling is played by secreted polypeptides, which are called polypeptide growth factors.

Growth factors, which are endogenous polypeptides, are ideal candidates for the treatment of stroke, as they have neuroprotective, reparative and proliferative properties.

Cytotechnologiesopportunitiesandperspectivesthemuse

Development of principles for controlled cultivation of mammalian cells based on the concepts of pericellular mass transfer and mass transfer, as well as on the assumptions underlying cell adhesion and locomotiveness, on the use of models of the kinetics of cell populations and allowing research on cell cultures in a monolayer, suspension and on microcarriers .

Study of the effect of periodic precision temperature effects on cell culture (cell cycle, cell proliferation and death) and study of thermal tolerance of animal cells under the combined effect of hyperthermia and some antioxidants on cell culture in order to increase the effectiveness of thermotherapy methods in clinical oncology.

The study of hypoxic conditions at the cellular level and the study of the mechanisms of action of some antihypoxants

Modeling of cell proliferation, death and differentiation based on modern concepts of the cell cycle.

Study of the functional characteristics of cells of the secretory epithelium of the venom glands of snakes in vitro.

Investigation of multilayer tissue-like growth of cell culture under conditions of precision pericellular mass transfer.

Applied

Development of technology for obtaining biologically active substances and materials by methods of culturing cells and tissues. Study of biocompatibility of various materials and cells.

Screening of anticancer drugs using organ and cell cultures.

Development of methods for culturing stem cells and tissue-specific fragments to solve the issues of tissue engineering in replacement maxillofacial surgery.

Fundamental

The theoretical foundations of controlled cultivation of mammalian cells have been created.

The role of diffusion restrictions in the regulation of monolayer and multilayer growth of minimally transformed and normal cells is shown.

The growth kinetics of attachment-dependent cells in multilayer cell cultures was studied.

It has been shown that it is possible to increase the selectivity of the effect of temperature on the death of normal and tumor cells, since the sensitivity to temperature effects of proliferating cells varies in the cell cycle: at a temperature of 370 C, cells die only in the G2 + M phase of the cycle, and at a temperature of 40 ° C, in the G1 and in G2+M phases; cell death in the S phase in the temperature range of 37-400C was not observed; in carrying out these studies, a model of cell proliferation and death under nonspecific external influences, developed in the laboratory of Cytotechnology, was used. It has been established that periodic temperature exposure makes it possible to increase the rate of cell death per unit of their stay during chronic hyperthermia by about 1.5 times.

A culture of venom-secreting epithelial cells capable of proliferation and synthesis of venom components was obtained in the form of spheroids; the ultrastructure of cells of the venom gland in vivo and in vitro was studied, the mechanism of cell resistance to the autotoxic action of the venom was elucidated, and the effect of agonists and antagonists on venom secretion in vitro was evaluated.

Studies of the molecular-cellular mechanisms of the antitumor effect of organocobalt compounds have been carried out.

A phenomenological multiparametric model of vital activity and regulation of the proliferation rate of animal somatic cells has been developed.

...

See what "Colonial organisms" are in other dictionaries:

Aquatic organisms in which, when reproduced asexually, the daughter generations remain connected to the mother organisms. Colonial organisms are found mainly among unicellular algae, sponges, coelenterates (coral ... Big Encyclopedic Dictionary

Organisms in which individuals of daughter generations during asexual reproduction (budding) remain connected to the parent organism, forming b. or m. a complex association of a colony. K. o. meet ch. arr. among unicellular algae, sponges, ... ... Biological encyclopedic dictionary

Aquatic organisms in which, when reproducing asexually, the daughter generations remain connected to the mother organisms. Colonial organisms are found mainly among unicellular algae, sponges, coelenterates (coral ... encyclopedic Dictionary

colonial organisms- kolonijiniai organizmai statusas T sritis ekologija ir aplinkotyra apibrėžtis Nelytinio dauginimosi vandens organizmai, kurių antriniai individai neatsiskiria nuo pagrindinių ir sudaro koloniją (pvz., melsvadumbliai, šarvadumbliai, infuzorijos… Ekologijos terminų aiskinamasis žodynas

COLONIAL ORGANISMS- organisms that, during asexual (vegetative) reproduction, remain connected with the daughter and subsequent generations, forming b. m. complex compound colony ... Glossary of botanical terms

Aquatic organisms, in which, during asexual reproduction, the daughter generations remain connected with the mother organisms. K. o. Chap. arr. among unicellular algae, sponges, coelenterates (coral polyps), bryozoans ... Natural science. encyclopedic Dictionary

Organisms in which, during asexual reproduction, the daughter and later generations remain associated with the original individual. O. to., consisting of homogeneous individuals, are called by functions polymorphic. Geological dictionary: in 2 x ... ... Geological Encyclopedia

Colonial organism is a term that combines two groups of organisms: Organisms consisting of many cells, poorly differentiated and not divided into tissues; in many cases, each such cell retains the ability to reproduce ... ... Wikipedia

ORGANISM- ORGANISM, a set of interacting organs that form an animal or plant. The very word O. comes from the Greek organon, that is, a work, a tool. For the first time, apparently, Aristotle called living beings organisms, because according to him ... ... Big Medical Encyclopedia

A genus of green algae. Mobile colonial organisms (spherical colonies up to 3 mm in diameter). About 20 types. They live in stagnant fresh waters, giving them a green color. * * * VOLVOX VOLVOX, a genus of green algae. Movable… … encyclopedic Dictionary

Colonial living organisms are made up of identical cells living together (corals) The colonial organism term that combines two groups of organisms:

1. Organisms consisting of a small number of cells, poorly differentiated and not divided into tissues; in many cases, such a cell retains the ability to reproduce (volvox green algae pandorina, Eudorine and others, many types of suviyoka and other groups resist).

2. Multicellular organisms that form colonies of several individuals, more or less closely related to each other, which usually have the same genotype and common metabolism and regulatory systems.

Colonial organisms that, during asexual (vegetative) reproduction, remain connected with the daughter and subsequent generations, forming a more or less complex association - a colony. Colonial plants include various unicellular algae: blue-green, green, golden, yellow-green, diatoms, pyrophytes, euglenovi. According to the method of formation of colonies, they are divided into Zoospores and motorsport (reproduce by zoospores or motorsport). Colonial animals include mainly marine animals - invertebrates and lower chordates. Of the unicellular - some flagellates, radiolarians, ciliates; of other invertebrates there are many sponges, most of the intestinal cavities, including siphonophores, almost all hydroids, many coral polyps and polypoid generations of some scyphoids, bryozoans. Of the lower chordates - salps and doliolids (Doliolida). This also includes extinct graptolites. Some colonial animals (bryozoans, hydroids, coral polyps, synascidia, etc.) lead an attached lifestyle; the colony is usually immobile on the substrate and has a more or less developed skeleton. Colonial radiolarians, siphonophores, pyrosomes, caskers, and salps live in the water column. Usually they are translucent, their skeleton is not developed. Many are characterized by metagenesis: colonial generation, vegetatively reproduces, alternating with a single, sexual one. Colonial organisms played the role of an intermediate link in the process of the emergence of multicellular animals from unicellular ones.

Colonial organisms consist of a certain number of cells of one or more types. However, unlike multicellular organisms, colonial cells usually function independently.

D. V. Naumov, T. V. Sedova.

- discoveries-conquests of Europeans in the early 15th - mid-17th century. in Africa, Asia, America and Oceania...
Geographic Encyclopedia
- see Art. War...
Soviet historical encyclopedia
- goods brought to European countries from colonies - from overseas and tropical countries ...
Reference commercial dictionary
- aquatic organisms, in which, during asexual reproduction, the daughter generations remain connected to the mother organisms ...
Natural science. encyclopedic Dictionary
- organisms in which, during asexual reproduction, the daughter and later generations remain associated with the original individual. O. to., consisting of homogeneous individuals, are called according to their functions - polymorphic ...
Geological Encyclopedia
- goods imported from other parts of the world...
- ...
Encyclopedic Dictionary of Economics and Law
- see Colonization...
- this is the name of the raw products of the hot zone - coffee, sugar, tea, spices, mosquito products, rice, cotton, paints, some wood products used for handicrafts, etc.
Encyclopedic Dictionary of Brockhaus and Euphron
- the banks of the imperialist states that dominated the colonial and dependent countries. They were used by the financial capital of the metropolises for the enslavement and colonial exploitation of the peoples of these countries ...
- military formations and organizations of the armed forces of the capitalist states, serving to maintain the rule of the colonialists and suppress the national liberation movement in the colonies and ...
Great Soviet Encyclopedia
- aquatic organisms that, during asexual reproduction, remain connected with the daughter and subsequent generations, forming a more or less complex association - a colony ...
Great Soviet Encyclopedia
- COLONIAL banks - banks of metropolitan countries or their branches, which functioned in colonial and dependent countries. They were used for the export of capital and non-equivalent trade exchange between metropolises and colonies ...
- 1) military formations in the colonies of the metropolitan states, which served to maintain their dominance 2) Troops formed in the colonies and participated in the battles in the 1st and 2nd world wars ...
Big encyclopedic dictionary
- aquatic organisms in which, when reproducing asexually, the daughter generations remain connected with the mother organisms ...
Big encyclopedic dictionary
- raw products brought to Europe from the colonies of Europeans, predominantly. West Indies and India...
Dictionary of foreign words of the Russian language

"Colonial organisms" in books

colonial markets

From the book British Empire author Bespalova Natalya Yurievna

Colonial Markets However, we got ahead of ourselves and did not have time to tell the reader about the circumstances under which Britain received possessions in the West Indies, that is, on the islands of the Caribbean Sea and in Central and South America. "Elizabeth's Sea Dogs" in these

GEOPOLITICAL COLONIAL OPPORTUNITIES

From the book On Geopolitics: Works of Different Years author Haushofer Karl

GEOPOLITICAL COLONIAL OPPORTUNITIES Before discussing and describing an important matter - geopolitical colonial opportunities, one should first think and understand, realizing at the same time three absolutely different in their basis, far from each other

§ 2. The first colonial empires

From the book General History. History of the New Age. 7th grade author Burin Sergey Nikolaevich

§ 2. The first colonial empires Portuguese dominion in the East Following the sailors, all those who craved quick enrichment rushed to the newly discovered lands: out of work nobles, ruined peasants and artisans, criminals and adventurers

Chapter 25 COLONIAL WARS

From the book France. A story of enmity, rivalry and love author Shirokorad Alexander Borisovich

Chapter 25 COLONIAL WARS In almost every country liberated from colonial dependence, on the main squares there are monuments to "field commanders" - participants in the struggle against the colonialists. However, if the native authorities had a conscience, they would install three

PORTUGUESE COLONIAL POLITIES

author Team of authors

PORTUGUESE COLONIAL POSSESSIONS History of the Portuguese colonial empire in the 17th century. largely marked by confrontation with the new rising colonial powers - the Netherlands and later with England. In the XVI century. Portuguese possessions in Asia and

COLONIAL POSSESSIONS OF THE NETHERLANDS

From the book World History: in 6 volumes. Volume 3: The World in Early Modern Times author Team of authors

COLONIAL POSSESSIONS OF THE NETHERLANDS The colonial empire of the Netherlands began to take shape at the very end of the 16th century, after the northern provinces were liberated from the power of the Spanish crown. The young state sought to participate in profitable trade with Asia. At first

FRENCH COLONIAL POSSESSIONS

From the book World History: in 6 volumes. Volume 3: The World in Early Modern Times author Team of authors

FRENCH COLONIAL POSSESSIONS "The sun shines for me, as well as for others ... God created the earth not only for some Spaniards ..." - so, according to legend, back in the 16th century. French King Francis I outlined his attitude to the division of spheres of influence outside of Europe between Spain

2. COLONIAL WARS OF NAPOLEON III

From the book Volume 1. Diplomacy from ancient times to 1872. author Potemkin Vladimir Petrovich

2. COLONIAL WARS OF NAPOLEON III War in Indo-China (1858? 1862). Since 1860, a series of French colonial wars began. With these wars, Napoleon III tried to gain popularity among the big bourgeoisie, with whom he was intimately connected. Since 1858, and especially since 1860,

From the book History of Portugal author Saraiva José Ermanu

Colonial possessions of Portugal XIX-XX centuries.

colonial finance

From the book The Persian Campaign of Peter the Great. Grassroots corps on the shores of the Caspian Sea (1722-1735) author Kurukin Igor Vladimirovich

Colonial finances As already mentioned, the Russian command tried to establish tax collection in the new possessions. According to the tsar's instructions, the collection of duties and taxes should have been started immediately: as soon as the troops "settle down", Matyushkin was obliged "in Baku

Colonial banks

TSB

colonial troops

From the book Great Soviet Encyclopedia (KO) of the author TSB

colonial organisms

From the book Great Soviet Encyclopedia (KO) of the author TSB

colonial dreams

From the book Myths about China: everything you knew about the most populous country in the world is not true! by Chu Ben

Colonial Dreams By the way, we should try an honest introspection. Constant conversations and fantasies about China “ruling the world” give out a subconscious mind that is still filled with gunboats and pith helmets. Chinese investment in African countries,

colonial wars

From the book Man of the Future author Burovsky Andrey Mikhailovich

Colonial wars It can be shown by many examples that with the course of historical time, wars become less and less bloody. The principles of "knightly war" triumph, and the attitude towards the enemy is becoming more and more humane, regulated by more and more

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