Check the level. Lesson objectives: To generalize and systematize knowledge about the vital processes of organisms that ensure its integrity and relationship with the environment. Check the level What is food digestion photosynthesis enzyme hemolymph
A substance similar in structure to the hemoglobin found in higher animals has been dissolved. Shining through transparent integuments, hemolymph gives red color to the insect's body. (Photo)
The water content in the hemolymph is 75-90%, depending on the stage of the life cycle and the state (active life,) of the insect. Its reaction is either weakly acidic (as in the blood of animals), or neutral, within the pH range of 6-7. Meanwhile, the osmotic pressure of hemolymph is much higher than that of the blood of warm-blooded animals. Various amino acids and other substances of predominantly organic origin act as osmotically active compounds.
The osmotic properties of hemolymph are especially pronounced in the few insects that inhabit brackish and salty waters. So, even when a coastal fly is immersed in a concentrated salt solution, its blood does not change its properties, and liquid does not come out of the body, which would be expected with such a "bathing".
By weight, hemolymph is 5-40% of body weight.
As you know, the blood of animals tends to coagulate - this protects them from too much blood loss in case of injury. Not all insects have clotting blood; their wounds, if such appear, are usually closed with "plugs" of plasma cells, podocytes and other special hemolymph cells.
Varieties of hemocytes in insects
Insect hemolymph composition
Hemolymph consists of two parts: liquid (plasma) and cellular elements, represented by hemocytes.
In the plasma, organic substances and inorganic compounds are dissolved in ionized form: sodium, potassium, calcium, magnesium, chlorite, phosphate, carbonate ions. Compared to vertebrates, insect hemolymph contains more potassium, calcium, phosphorus and magnesium. For example, in herbivorous species, the concentration of magnesium in the blood can be 50 times higher than in mammals. The same goes for potassium.
Also, nutrients, metabolites (uric acid), hormones, enzymes and pigment compounds are found in the liquid part of the blood. Dissolved oxygen and carbon dioxide, peptides, proteins, lipids, and amino acids are also found there to some extent.
Let us dwell on the nutrients of hemolymph in more detail. Of the carbohydrates, most, about 80%, are trehalose, which consists of two glucose molecules. It is formed in, goes into the hemolymph, and then is cleaved by the enzyme trehalase in the organs. When the temperature drops, glycerin is formed from another carbohydrate - glycogen. By the way, it is glycerin that is of primary importance when insects survive frost: it prevents hemolymph from forming ice crystals that can damage tissues. It turns into a jelly-like substance, and the insect retains its viability sometimes even at sub-zero temperatures (for example, the Braconcephi rider can withstand freezing up to -17 degrees).
Amino acids are present in plasma in a sufficiently large amount and concentration. Especially there is a lot of glutamine and glutamic acid, which play a role in osmoregulation and are used for building. Many amino acids combine with each other in plasma and are "stored" there in the form of simple proteins - peptides. In the hemolymph of female insects there is a group of proteins - vitellogenins, which are used in the synthesis of yolk c. The protein lysozyme, which is present in the blood of both sexes, plays a role in the body's defense against bacteria and viruses.
The "blood" cells of insects - hemocytes - like the erythrocytes of animals, are of mesodermal origin. They are mobile and motionless, have different shapes, are presented with different "concentration". For example, in 1 mm 3 of a ladybug hemolymph there are about 80,000 cells. According to other sources, their number can reach 100,000. The cricket has 15 to 275 thousand of them per 1 mm 3.
Hemocytes are divided according to morphology and functions into the main types: amoebocytes, chromophilic leukocytes, phagocytes with homogeneous plasma, hemocytes with granular plasma. In general, among all hemocytes, as many as 9 species were found: prohemocyte, plasmacyte, granulocyte, enocyte, cystocyte, spherical cell, adipohemocyte, podocyte, worm-like cell. Partly these are cells of different origins, partly - different "ages" of the same hematopoietic germ. They come in a variety of sizes, shapes and functions. (Photo)
Usually, hemocytes settle on the walls of blood vessels and practically do not participate in circulation, and only before the onset of the next stage of transformation or before they begin to move in the bloodstream. They are formed in special hematopoietic organs. In Crickets, Flies, Butterflies, and these organs are located in the region of the dorsal vessel.
Hemolymph functions
They are very diverse.
Nutritional function: transport of nutrients through the body.
Humoral regulation: ensuring the work of the endocrine system, the transfer of hormones and other biologically active substances to the organs.
Respiratory function: transport of oxygen to cells (in some insects, the hemocytes of which have hemoglobin or a pigment close to it). The example from the Chironimus (bell mosquitoes, dergun mosquitoes) has already been described above. This insect in the larval stage lives in water, in swampy areas, where the oxygen content is minimal. This mechanism allows him to use the O 2 reserves in the water in order to survive in such conditions. In others, the blood does not perform the respiratory function. Although there is an interesting exception: after eating, the human erythrocytes swallowed by it can penetrate through the intestinal wall into the body cavity, where they remain unchanged and remain in a state of full viability for a long time. True, they are too unlike hemocytes to take on their function.
Excretory function: accumulation of metabolic products, which will then be excreted from the body by the excretory organs.
Mechanical function: creating turgor, internal pressure to maintain body shape and organ structure. This is especially important for their soft
In a number of insects, for example, locusts or grasshoppers, autohemorrhage is observed: when special muscles contract, their blood splashes out for self-defense. At the same time, it, apparently, mixing with air, sometimes forms foam, which increases its volume. Places of ejection of blood at Leaf beetles, Coccinellids and others are located in the articulation area, in the zone of attachment of the first pair to the body and near the mouth.
Article for the competition "bio / mol / text": The reactions of carbon dioxide in the form of CO 2 or bicarbonate (HCO 3 -) in the cell are controlled by carbonic anhydrase - the most active enzyme among all known, accelerating the reversible reaction of atmospheric CO 2 hydration. In this article, we will look at the process of photosynthesis and the role of carbonic anhydrase in it.
Is it buried
In the absence of even a single
Sun beam to the ground?
Or did he not arise,
Transformed in her,
In emerald leaves.
N.F. Shcherbina
The history of learning the process that turns spoiled air into good air again
Figure 1. Experiment D. Priestley
The term "photosynthesis" itself was proposed in 1877 by the famous German plant physiologist Wilhelm Pfeffer (1845-1920). He believed that from carbon dioxide and water, green plants in the light form organic matter and release oxygen. And the energy of sunlight is absorbed and transformed with the help of green pigment. chlorophyll... The term "chlorophyll" was proposed in 1818 by the French chemists P. Peltier and J. Cavant. It is formed from the Greek words chloros - green - and phillon - leaf. Researchers later confirmed that plants require carbon dioxide and water to feed them, from which most of the plant mass is made.
Photosynthesis is a complex multistep process (Fig. 3). At what stage is the energy of light needed? It turned out that the reaction of the synthesis of organic substances, the inclusion of carbon dioxide in the composition of their molecules does not directly require light energy. These reactions were named dark, although they go not only in the dark, but also in the light, it is just that light is not necessary for them.
The role of photosynthesis in the life of human society
In recent years, humanity has faced a shortage of energy resources. The impending depletion of oil and gas reserves prompts scientists to look for new, renewable energy sources. The use of hydrogen as an energy carrier opens up extremely attractive prospects. Hydrogen is a source of clean energy. When it is burned, only water is formed: 2H 2 + O 2 = 2H 2 O. Higher plants and many bacteria secrete hydrogen.
As for bacteria, most of them live in strictly anaerobic conditions and cannot be used for large-scale production of this gas. Recently, however, a strain of aerobic cyanobacteria was discovered in the ocean, which produces hydrogen very efficiently. Cyanobacterium cyanothece 51142 combines two fundamental biochemical pathways at once - this is energy storage during daylight hours during photosynthesis and nitrogen fixation with the release of hydrogen and energy consumption - at night. The yield of hydrogen, and so high enough, was able to further increase in laboratory conditions by "adjusting" the duration of daylight hours. The reported yield - 150 micromoles of hydrogen per milligram of chlorophyll per hour - is the highest that could be observed for cyanobacteria. If these results are extrapolated to a slightly larger reactor, the yield is 900 ml of hydrogen per liter of bacterial culture in 48 hours. On the one hand, this does not seem to be a lot, but if you imagine reactors with bacteria working at full strength stretching over thousands of square kilometers of equatorial oceans, then the total amount of gas can be impressive.
The new process for producing hydrogen is based on the conversion of the energy of xylose, the most abundant simple sugar. Scientists from Virginia Tech took a set of enzymes from a number of microorganisms and created a unique synthetic enzyme, which has no analogues in nature, which will allow you to extract large amounts of hydrogen from any plant. This enzyme, at a temperature of only 50 ° C, releases an unprecedented amount of hydrogen using xylose - about three times more than the best modern "microbial" techniques. The essence of the process boils down to the fact that the energy stored in xylose and polyphosphates breaks down water molecules and allows you to get high-purity hydrogen, which can be immediately sent to fuel cells that generate electricity. The result is an efficient, environmentally friendly process that requires a little energy just to start the reaction. In terms of energy intensity, hydrogen is not inferior to high-quality gasoline. The flora is a huge biochemical plant, which amazes with the scale and variety of biochemical syntheses.
There is another way for man to use solar energy assimilated by plants - the direct transformation of light energy into electrical energy. The ability of chlorophyll to give and attach electrons under the influence of light underlies the work of generators containing chlorophyll. M. Calvin in 1972 put forward the idea of creating a photocell, in which chlorophyll would serve as a source of electric current, capable of taking electrons from some substances under illumination and transferring them to others. Currently, many developments are underway in this area. For example, the scientist Andreas Mershin ( Andreas Mershin) and his colleagues at the Massachusetts Institute of Technology have created batteries based on a light-harvesting complex of biological molecules - photosystem I from cyanobacteria Thermosynecho coccuselongates(fig. 4). Under normal sunlight, the cells showed an open circuit voltage of 0.5 V, a specific power of 81 µW / cm 2, and a photocurrent density of 362 µA / cm 2. And this, according to the inventors, is 10,000 times more than any previously shown biophotovoltaics based on natural photosystems.
Figure 4. Spatial structure of photosystem 1 (FS1). PS are important components of complexes responsible for photosynthesis in plants and algae. They are made up of several varieties of chlorophyll and related molecules - proteins, lipids, and cofactors. The total number of molecules in such a set is up to more than two hundred.
The efficiency of the resulting batteries was only about 0.1%. Nevertheless, the creators of the curiosity consider it an important step towards the massive introduction of solar energy into everyday life. Indeed, such devices can potentially be produced at extremely low costs! The creation of photovoltaic cells is just the beginning in the industrial production of alternative types of energy for all mankind.
Another important task of plant photosynthesis is to provide people with organic matter. And not only for food, but also for pharmaceuticals, industrial paper production, starch, etc. Photosynthesis is the main entry point for inorganic carbon into the biological cycle. All free oxygen in the atmosphere is of biogenic origin and is a byproduct of photosynthesis. The formation of an oxidizing atmosphere (the so-called oxygen disaster) completely changed the state of the earth's surface, made possible the appearance of respiration, and later, after the formation of the zone layer, allowed life to exist on land. Considering the importance of the process of photosynthesis, the disclosure of its mechanism is one of the most important and interesting tasks facing plant physiology.
Let's move on to one of the most interesting enzymes that work under the hood of photosynthesis.
Most Active Enzyme: Photosynthesis Volunteer
Under natural conditions, the concentration of CO 2 is rather low (0.04% or 400 μl / l), therefore, the diffusion of CO 2 from the atmosphere into the inner air cavities of the leaf is difficult. Under conditions of low concentrations of carbon dioxide, an essential role in the process of its assimilation during photosynthesis belongs to the enzyme carbonic anhydrase(CA). Probably, the spacecraft helps to ensure ribulose bisphosphate carboxylase / oxygenase(RBPC / O, or RuBisCO) substrate (CO 2) stored in the chloroplast stroma in the form of bicarbonate ion. RuBisc / O is one of the most important enzymes in nature, since it plays a central role in the main mechanism of the entry of inorganic carbon into the biological cycle and is considered the most abundant enzyme on Earth.
Carbonic anhydrase is an extremely important biocatalyst, one of the most active enzymes. CA catalyzes the reversible reaction of CO 2 hydration in the cell:
CO 2 + H 2 O = H 2 CO 3 = H + + HCO 3 -.
The carbonic anhydrase reaction takes place in two stages. In the first stage, the bicarbonate ion HCO 3 - is formed. In the second stage, a proton is released, and it is this stage that limits the process.
Hypothetically, CAs of plant cells can perform various physiological functions in accordance with their location. During photosynthesis, in addition to the rapid transfer of HCO 3 - into CO 2, which is necessary for RuBisCO / O, it can accelerate the transport of inorganic carbon through membranes, maintain the pH status in different parts of cells, mitigate changes in acidity in stressful situations, and regulate the transport of electrons and protons to the chloroplast. ...
Carbonic anhydrase is present in almost all studied plant species. Despite numerous experimental facts in favor of the participation of carbonic anhydrase in photosynthesis, the final mechanism of the participation of the enzyme in this process remains to be elucidated.
Numerous "family" of carbonic anhydrases
In a higher plant Arabidopsis thaliana 19 genes of three (out of five established to date) families encoding carbonic anhydrases were found. In higher plants, CAs belonging to the α-, β-, and γ-families were found. Five γ-family CAs were found in mitochondria; Β-family CAs were found in chloroplasts, mitochondria, cytoplasm, and plasmalemma (Fig. 6). About eight α-CAs it is known only that α-CA1 and α-CA4 are located in chloroplasts. To date, carbonic anhydrases α-KA1, α-KA4, β-KA1, and β-KA5 have been found in chloroplasts of higher plants. Of these four CAs, the location of only one is known, and it is located in the chloroplast stroma (Fig. 6).
CAs are metalloenzymes that contain a metal atom in the active center. Usually such a metal that is bound to the ligands of the CA reaction center is zinc. CAs are completely different from each other at the level of their tertiary and quaternary structures (Fig. 7), but it is especially surprising that the active centers of all CAs are similar.
Figure 7. Quaternary structure of representatives of three families of CAs. In greenα-helices are indicated, yellow- areas of β-folding, pink- zinc atoms in the active centers of enzymes. In the structures of α and γ-CA, β-folded organization of the protein molecule prevails, in the structure of β-CA, α-turns predominate.
Location of CA in plant cells
The variety of CA forms hints at the plurality of functions that they perform in different parts of the cell. To determine the intracellular location of six β-carbonic anhydrases, we used an experiment based on CA labeling with green fluorescent protein (GPB). Carbonic anhydrase was genetically engineered into the same “reading frame” with PBS, and the expression of this “cross-linked” gene was analyzed using laser confocal scanning microscopy (Fig. 8). In mesophilic cells of transgenic plants, in which β-CA1 and β-CA5 are “linked” with PBS, the PBS signal coincided in space with the fluorescence of chlorophyll, which indicated its connection (colocalization) with chloroplasts.
Figure 8. Micrograph of cells with GFP, which is "stitched" with the coding region of the β-KA1-6 genes. Green and red signals show GFP fluorescence and chlorophyll autofluorescence, respectively. Yellow (on right) the combined picture is shown. Fluorescence was recorded using a confocal microscope.
The use of transgenic plants opens up wide opportunities for studying the participation of carbonic anhydrases in photosynthesis.
What can be the functions of CA in photosynthesis?
Figure 9. Pigment-protein complexes PS1 and PS2 in the thylakoid membrane. Arrows the transport of electrons from one system to another and the reaction products are shown.
It is known that bicarbonate ions are necessary for the normal transport of electrons in the section of the electron transport chain of chloroplasts. QA → Fe 2+ → QB, where QA is the primary and QB is the secondary quinone acceptors, and QB is located on the acceptor side of photosystem 2 (PS2) (Fig. 9). A number of facts indicate the participation of these ions in the water oxidation reaction on the donor side of PS2. The presence of carbonic anhydrases in the pigment-protein complex of PS2, which regulate the supply of bicarbonate to the desired site, could provide an efficient course of these reactions. It has already been suggested that CAs participate in the protection of PS2 from photoinhibition under intense illumination by binding excess protons to form an uncharged CO 2 molecule that is readily soluble in the lipid phase of the membrane. The presence of CA was shown in a multienzyme complex that fixes CO 2 and bonds ribulose bis phosphate carboxylase / oxygenase with thylakoid membrane. It has been hypothesized that membrane-associated CA dehydrates bicarbonate, producing CO 2. Recently, it was shown that intrathylakoid protons accumulated in the light are used in the dehydration of bicarbonate added to a suspension of isolated thylakoids, and it was assumed that this reaction can occur on the stromal membrane surface if the CA provides a channel for proton leakage from the lumen.
Surprisingly, so much depends on one building block of the system. And by revealing its location and function, the entire system can be controlled.
Conclusion
Carbon dioxide for animals is an unused product of metabolic reactions, so to speak - "exhaust" released during the "combustion" of organic compounds. Surprisingly, plants and other photosynthetic organisms use this very carbon dioxide for the biosynthesis of almost all organic matter on Earth. Life on our planet is built on the basis of a carbon skeleton, and it is carbon dioxide that is the "brick" from which this skeleton is built. And it is the fate of carbon dioxide - whether it is included in the composition of organic matter or released during its decomposition - that underlies the circulation of substances on the planet (Fig. 10).
Literature
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- Artamonov V.I. Entertaining plant physiology. M .: "Agropromizdat", 1991;
- Aliev D.A. and Guliev N.M. Plant carbonic anhydrase. M .: "Science", 1990;
- Chernov N.P. Photosynthesis. Chapter: The structure and levels of organization of the protein. M .: "Bustard", 2007;
- Bacteria for hydrogen energy;
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Teacher of biology, chemistry and geography of the first category
Generalization on the topic "Life of organisms"
(Biology lesson in grade 6)
Lesson Objectives:
To generalize and systematize knowledge about the life processes of organisms, ensuring its integrity and relationship with the environment.
Check the level of formation of skills to highlight the essential signs and properties of phenomena, apply knowledge in practice.
Promote the formation of students' understanding of plants and animals as whole organisms.
^ Basic concepts and terms of the lesson : nutrition, digestion, photosynthesis, enzyme, blood, cold-blooded, warm-blooded, external skeleton, internal skeleton, nervous system, reflex, instinct, hormones, spore, gamete, seed, growth, development, reproduction.
Equipment: computer presentation “Vital activity of organisms. Generalization of knowledge ”, processor, video projector, screen.
During the classes:
Organizing time.
Repetition and generalization of knowledge.
Solution of biological problems.
What stages of development of organisms do these objects belong to?
Reasoned answers to the tasks "Which statements are correct?" (accompanied by a slide show with the text of the statements and the corresponding pictures and diagrams, the students comment on their answer - why do they agree or disagree)
Only plants can directly absorb solar energy.
All animals are omnivorous.
All living organisms breathe.
The stomata is the respiratory organ of the earthworm.
Only terrestrial vertebrates have lungs.
Organics in plants move through sieve tubes.
The earthworm has a closed circulatory system.
The fish has a three-chambered heart.
Metabolism occurs in all living organisms.
Fish are warm-blooded animals.
Plants and fungi do not have special excretory systems.
The excretory organs of the worm are the kidneys.
All animals have an internal skeleton.
The skeleton of vertebrates consists of the skeleton of the head, trunk, and limbs.
Plants are capable of active movement, they can move.
Hormones are substances secreted by the endocrine glands into the blood.
The vertebrate nervous system consists of the brain and spinal cord and nerves.
Two individuals take part in asexual reproduction.
Budding is a way of asexual reproduction.
Flowering plants have double fertilization.
Insects have an indirect type of development.
Tasks to reproduce the definitions of the basic concepts of the topic.
^ Nutrition, digestion, photosynthesis, enzyme.
What type of plant nutrition is photosynthesis?
What organisms is digestion typical for?
What do enzymes have to do with the digestion process?
^ Hemolymph, plasma, blood cells, artery, vein, capillary.
What is blood plasma? How is it related to blood cells?
What unites these concepts - arteries, veins, capillaries?
How are these vessels different?
^ 3. Cold-blooded, warm-blooded, kidney, ureter, bladder.
How do warm-blooded animals differ from cold-blooded ones?
Which animals are warm-blooded and which are cold-blooded?
What unites these three concepts - kidneys, ureters, bladder.
^ 4. Outer skeleton, inner skeleton, wing lift.
What is the difference between the external skeleton and the internal one?
For which organisms is the external skeleton characteristic, and for which - the internal one?
What is wing lift?
^ 5. Reticular nervous system, nodular nervous system, nerve impulse, reflex, instinct.
What organisms is the reticular nervous system typical for? What are its features?
What are the features of the nodal nervous system?
What is a nerve impulse?
What is a reflex?
What is instinct?
^ 6. Budding, spores, vegetative organs.
What do all these concepts have in common?
What organisms are budding typical for?
What are vegetative organs?
What organisms most often reproduce by vegetative organs?
^ 7. Gamete, hermaphrodite, sperm, egg, fertilization, zygote.
What do the concepts have in common - gamete, sperm, egg?
What organisms are called hermaphrodites?
Make a sentence using the last four terms.
^ 8. Pollination, embryo sac, central cell, double fertilization, seedling.
What is pollination?
What do concepts such as the embryo sac and the central cell have in common?
What are the features of double fertilization characteristic of flowering plants?
What is a seedling?
^ 9. Crushing, blastula, gastrula, neurula, mesoderm.
What is crushing?
What is the result of this process?
What do such concepts as blastula, gastrula and neurula have in common?
What is mesoderm?
Generalization of the material.
How is living things different from non-living things?
Lesson conclusion: Living organisms differ from bodies of inanimate nature in that they are characterized by such processes as nutrition, respiration, metabolism, excretion, movement, irritability, growth, development and reproduction.
Summing up the results of the lesson, assigning marks to students for work in the lesson
Hemolymph composition. In higher animals, two fluids circulate in the body: blood, which performs the respiratory function, and lymph, which mainly performs the function of carrying nutrients. Due to the significant difference from the blood of higher animals, the blood of insects received a special name - hemolymph ... It is the only tissue fluid in the body of insects. Like the blood of vertebrates, it consists of a liquid intercellular substance - plasma and the cells in it - hemocytes ... Unlike the blood of vertebrates, hemolymph does not contain cells supplied with hemoglobin or other respiratory pigment. As a result, the hemolymph does not perform the respiratory function. All organs, tissues and cells take the nutrients and other substances they need from the hemolymph and release metabolic products into it. Hemolymph transports digestive products from the walls of the intestinal canal to all organs, and transfers the decay products to the excretory organs.
The amount of hemolymph in the body of bees varies: in a mated queen - 2.3 mg; in the oviparous uterus - 3.8; the drone - 10.6; for a worker bee - 2.7-7.2 mg.
Hemolymph plasma is the internal environment in which all cells of the insect's body live and function. It is an aqueous solution of inorganic and organic substances. The water content in hemolymph is from 75 to 90%. The hemolymph reaction is mostly weakly acidic or neutral (pH from 6.4 to 6.8). Free inorganic substances of hemolymph are very diverse and are in the plasma in the form of ions. Their total number exceeds 3%. They are used by insects not only to maintain the osmotic pressure of hemolymph, but also as a reserve of ions necessary for the functioning of living cells.
The main cations of hemolymph include sodium, potassium, calcium and magnesium. In each insect species, the quantitative ratios between these ions depend on its systematic position, habitat and dietary regime.
Ancient and relatively primitive insects (dragonflies and Orthoptera) are characterized by a high concentration of sodium ions with a relatively low concentration of all other cations. However, in such orders as Hymenoptera and Lepidoptera, the sodium content in the hemolymph is low, and therefore other cations (magnesium, potassium, and calcium) become dominant. In bee larvae, potassium cations prevail in hemolymph, and sodium cations in adult bees.
Chlorine is in the first place among hemolymph anions. In insects developing with incomplete metamorphosis, from 50 to 80% of hemolymph cations are balanced by chlorine anions. However, in the hemolymph of insects developing with complete metamorphosis, the concentration of chlorides is greatly reduced. So, in Lepidoptera, chlorine anions can balance only 8-14% of the cations contained in the hemolymph. In this group of insects, organic acid anions predominate.
In addition to chlorine, insect hemolymph has other anions of inorganic substances, for example H 2 PO 4 and HCO 3. The concentration of these anions is usually low, but they can play an important role in maintaining the acid-base balance in the hemolymph plasma.
The hemolymph of a bee larva contains the following cations and anions of inorganic substances, g per 100 g of hemolymph:
Sodium - 0.012-0.017 magnesium - 0.019-0.022
potassium - 0.095 phosphorus - 0.031
calcium - 0.014 chlorine - 0.00117
The hemolymph always contains soluble gases - a little oxygen and a significant amount of CO 2.
The hemolymph plasma contains a variety of organic substances - carbohydrates, proteins, lipids, amino acids, organic acids, glycerol, dipeptides, oligopeptides, pigments, etc.
The composition of hemolymph carbohydrates in bees of different ages is not stable and directly reflects the composition of sugars absorbed with food. Young bees (no older than 5-6 days) have a low content of glucose and fructose, and among worker bees - nectar collectors, hemolymph is rich in these monosaccharides. The level of fructose in the hemolymph of bees is always higher than that of glucose. The glucose contained in the hemolymph is completely consumed by the bee during 24 hours of fasting. The reserves of glucose in the hemolymph are enough for the collecting bee to fly for 15 minutes. With a longer flight of the bee, the volume of its hemolymph decreases.
There is less glucose in the hemolymph of drones than in worker bees, and its amount is fairly constant - 1.2%. In infertile queens, a high content of glucose in the hemolymph (1.7%) was noted during mating flights, but with the transition to the laying of eggs, the amount of sugars decreases and is maintained at one fairly constant level, regardless of its age. In the hemolymph of the queens, there is a significant increase in the concentration of sugar when they are in families that are preparing for swarming.
In addition to glucose and fructose, hemolymph contains significant amounts of trehalose disaccharide. In insects, trehalose serves as a transport form of carbohydrates. The cells of the fatty body synthesize it from glucose and then release it into the hemolymph. The synthesized disaccharide with the flow of hemolymph is carried throughout the body and absorbed by those tissues that need carbohydrates. In tissues, trehalose is broken down to glucose by a special enzyme - trehalase. Trehalase is especially abundant in pollen-collecting bees.
Carbohydrates are stored in the body of bees in the form of glycogen and accumulate in the fat body and muscles. In the pupa, glycogen is contained in the hemolymph, released into it from the cells during histolysis of the organs of the larva's body.
Proteins make up an essential part of the hemolymph. The total protein content in the hemolymph of insects is quite high - from 1 to 5 g per 100 ml of plasma. By the method of disk electrophoresis on a polyacrylamide body, it is possible to isolate from 15 to 30 protein fractions from hemolymph. The number of such fractions varies depending on taxonomic position, sex, stage of insect development and diet.
The hemolymph of the bee larva contains significantly more protein than the hemolymph of the larvae of other insects. The share of albumin in the bee larva is 3.46%, and the share of globulin is 3.10%. The protein content is more constant in adult bees than in larvae. In the hemolymph of the uterus and the worker bee, there are slightly more proteins in comparison with the hemolymph of the drone. In addition, in many insects, the hemolymph of sexually mature females contains protein fractions that are absent in males. Such proteins are called - vitellogenins , female-specific yolk protein, because they are used for the purposes of vitellogenesis - the formation of yolk in the developing eggs. Vitellogenins are synthesized in the fat body, and hemolymph transports them to maturing oocytes (germ cells).
The hemolymph of bees, like most other insects, is especially rich in amino acids, there are 50-100 times more of them than in the plasma of vertebrates. Usually, 15-16 free amino acids are found in hemolymph, among them glutamic acid and proline reach the maximum content. The replenishment of the amino acid reserve in the hemolymph occurs from the food that is digested in the intestine and from the fatty body, the cells of which can synthesize nonessential amino acids. The fatty body, which supplies the hemolymph with amino acids, also acts as a consumer of them. It absorbs amino acids from the hemolymph, which are consumed for protein synthesis.
Lipids (fats) enter the hemolymph mainly from the intestines and the fat body. The most significant part of the lipid fraction of hemolymph are glycerides, i.e. esters of glycerol and fatty acids. The fat content is not constant and depends on the feed of the insects, reaching in some cases 5% or more. 100 cm 3 of hemolymph of worker bee larvae contains from 0.37 to 0.58 g of lipids.
Almost all organic acids can be found in the hemolymph of insects. In insect larvae developing with complete metamorphosis, a particularly high content of citric acid in the hemolymph plasma is noted.
Among the pigments contained in hemolymph, the most common are carotenoids and flavonoids, which create a yellow or greenish color of hemolymph. The hemolymph of honey bees contains a colorless melanin chromogen.
In the hemolymph, decay products are always present in the form of free uric acid or in the form of its salts (urates).
Along with the noted organic substances, the hemolymph of honey bees always contains oxidizing and reducing, as well as digestive enzymes.
The bees' hemolymph contains hemocytes , which are nucleated cells that originate from the mesoderm. Most of them usually settle on the surface of various internal organs, and only some of them circulate freely in the hemolymph. Hemocytes adjacent to the tissues and heart form phagocytic organs. In bees, hemocytes penetrate into the heart and circulate even in the thin veins of the wings.
The total number of hemocytes freely circulating in the body of the insect is 13 million, and their total volume reaches 10% of the hemolymph volume. They are very diverse in their form and are subdivided into several types. All hemocytes found in larvae, pupae, young and old bees are 5-7 types. BA Shishkin (1957) studied in detail the structure of hemocytes in bees and identified five main types: plasma cells, nymphocytes, spherulocytes, enocytoids and plateocytes (Fig. 22). Each type is an independent group of hemocytes that are not related to each other in origin and do not have morphological transitions. He also described the stages of development of hemocytes from young growing forms to mature and degenerating ones.
Rice. 22.
A - plasma cells; B - nymphocytes; B - spherulocytes; G - enocytoids; D - plateocytes (in the stage of development and degeneration); c - cytoplasm; I am the core; c - vacuoles; bz - basophilic grains; c - spherules; xr - chromatin clumps; xs - chromatin grains
Plasmacytes are the cellular elements of the hemolymph of the larva. Young cells often divide mitotic and go through five stages of development. Cells differ in size and structure.
Nymphocytes are cellular elements of the pupal hemolymph, which are half the size of plasma cells. Nymphocytes have light-refracting granules and vacuoles.
Spherulocytes are found in the pupa and in the adult bee. These cells are distinguished by the presence of inclusions in the cytoplasm - spherules.
Enocytoids are also found in pupae and adult bees. The cells are round. The cytoplasm of enocytoids contains granular or crystalline inclusions. All cells of this type go through six stages of development.
Platocytes are small, of various shapes and the most numerous hemocytes in the hemolymph of an adult bee, accounting for 80-90% of all hemocytes in a bee. Platocytes go through seven developmental stages from young to mature.
Due to the ability and transformations, hemolymph cells, which are in different morphological states, can perform different functions. Typically, each type of hemocyte accumulates in maximum numbers at certain stages of the life cycle. Especially sharply decreases the number of hemocytes in the hemolymph from the 10th day of life of bees. Apparently, this is a turning point in the life of the bee and is associated with a change in its function.
In the summer-autumn period, in the hemolymph of bees infected with the varroa mite, there is an increase in the number of mature and old age plateocytes, as well as the presence of a large number of young cell forms. This is apparently due to the fact that when the tick feeds on the bee, the volume of hemolymph decreases, leading to metabolic disorders and the regeneration of plateocytes.
Hemolymph functions. Hemolymph washes all cells, tissues and organs of the insect. It is the internal environment in which all cells of the bee's body live and function. Hemolymph has seven essential vital functions.
Hemolymph carries nutrients from the intestinal walls to all organs. In carrying out this trophic function hemocytes and plasma chemical compounds are involved. Part of the nutrients comes from the hemolymph to the cells of the fatty body and is deposited there in the form of reserve nutrients, which again pass into the hemolymph when the bees starve.
The second important function of hemolymph is participation in the removal of decay products ... Hemolymph, flowing in the body cavity, is gradually saturated with decay products. Then it comes into contact with the malpighian vessels, the cells of which select decay products from the solution, uric acid. Thus, the hemolymph transports uric acid, urates and other substances from the cells of the bee's body to the malpighian vessels, which gradually reduce the concentration of decay products in the hemolymph. From the malpighian vessels, uric acid enters the hind intestine, from where it is expelled with feces.
N. Ya. Kuznetsov (1948) showed that bacterial phagocytosis consists of two processes. First, the chemical agents of hemolymph act on the bacteria, and then the process of absorption of bacteria by phagocytes takes place.
OF Grobov (1987) showed that the organism of the larva always responds to the introduction of the pathogen of American foulbrood with a protective reaction - phagocytosis. Phagocytes capture and destroy larvae bacilli, but this does not provide complete protection of the body. Reproduction of bacilli is more intensive than their phagocytosis, and the larva dies. At the same time, there was a complete absence of phagocytosis.
Also essential mechanical function hemolymph - creating the necessary internal pressure, or turgor. Due to this, the larvae maintain a certain body shape. In addition, by contraction of the muscles, an increased pressure of the hemolymph can arise and be transmitted through it to another place to perform another function, for example, to rupture the cuticular cover in larvae during molting or to spread the wings of bees that have just emerged from the cells.
The role of hemolymph in maintaining a constant active acidity
... Almost all life processes in the body can proceed normally with a constant reaction of the environment. Maintaining a constant active acidity (pH) is achieved due to the buffering properties of hemolymph.
MI Reznichenko (1930) showed that the hemolymph of bees is distinguished by good buffering capacity. So, when the hemolymph was diluted 10 times, its active acidity almost did not change.
Hemolymph takes participation in gas exchange , although it does not carry oxygen through the body of the bee. The CO 2 formed in the cells directly enters the hemolymph and is carried away with it to the places where the increased possibilities of aeration ensure its removal through the tracheal system.
There is no doubt that antibiotics and some plasma proteins can create insect resistance to pathogens (immunity).
As you know, two independent immune systems operate in the blood of vertebrates - nonspecific and specific.
Nonspecific immunity is due to the release of antibacterial protein products into the bloodstream, which create a natural or acquired resistance of animals to diseases. Among the most studied compounds of this kind is lysozyme, an enzyme that destroys the membrane of bacterial cells. It has been established that in insects the nonspecific immune system also includes the use of the same enzyme.
Specific immunity in vertebrates is associated with the formation of antibodies. Antibodies belong to globulin proteins. The protective effect of any antibody is based on its ability to bind to a specific antigen. Vaccination, that is, the use of a vaccine with weakened or killed pathogens of an infectious disease, stimulates the formation of specific antibodies and creates resistance to this disease.
It is believed that antibodies are not formed in the hemolymph of insects. However, despite this, it is known that vaccination effectively protects insects from a number of diseases.
Back in 1913, I.L.Serbinov put forward a hypothesis about the possibility of creating immunity in bees with the help of a vaccine introduced into the body through the mouth. Later, V.I. Poltev and G.V. Aleksandrova (1953) noted that when adult bees were infected with the causative agent of European foulbrood, they developed immunity after 10-12 days.
Hemolymph washes all organs and tissues of the bee, unites them into a single whole. The hemolymph contains hormones, enzymes and other substances that are carried throughout the body. Under the influence of hormones, the processes of metamorphosis occur: the transformation of the larva into a pupa and a pupa into an adult bee. Thus, the main metabolic processes in the bee's body are directly related to hemolymph.
Hemolymph to some extent provides thermoregulation of the body. By washing the places of increased heat production (chest muscles), the hemolymph heats up and transfers this heat to places with a lower temperature.
The new design of the hive allows you to get honey "from the tap" and not disturb the bees
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Answers to school textbooks
Nutrition is the process of obtaining substances and energy by organisms. Food contains the chemicals needed to create new cells and provide energy for the body's processes.
2. What is the essence of digestion?
Once in the body, food in most cases cannot be assimilated immediately. Therefore, it undergoes mechanical and chemical processing, as a result of which complex organic substances are converted into simpler ones; then they are absorbed into the bloodstream and carried throughout the body.
3. Tell us about soil nutrition of plants.
With soil nutrition, plants, with the help of the root, absorb water and minerals dissolved in it, which enter the stems and leaves through conductive tissues.
4. What is aerial plant nutrition?
The main organs of air nutrition are green leaves. Air enters them through special slit-like cell formations - the stomata, from which the plant uses only carbon dioxide for nutrition. The chloroplasts in the leaf contain the green pigment chlorophyll, which has an amazing ability to capture solar energy. Using this energy, plants, through complex chemical transformations from simple inorganic substances (carbon dioxide and water), form the organic substances they need. This process is called photosynthesis (from the Greek "photos" - light and "synthesis" - connection). During photosynthesis, solar energy is converted into chemical energy, enclosed in organic molecules. The resulting organic matter from the leaves is transferred to other parts of the plant, where it is spent on vital processes or deposited in a reserve.
5. In what organelles of a plant cell does photosynthesis take place?
The process of photosynthesis takes place in the chloroplasts of the plant cell.
6. How is digestion carried out in protozoa?
Digestion in protozoa, for example, in amoeba, is carried out as follows. Having met a bacterium or unicellular algae on its way, the amoeba slowly envelopes its prey with the help of pseudopods, which, merging, form a bubble - a digestive vacuole. Digestive juice enters it from the surrounding cytoplasm, under the influence of which the contents of the vesicle are digested. The resulting nutrients through the wall of the bubble enter the cytoplasm - from which the body of the animal is built. Undigested residues move to the surface of the body and are pushed out, and the digestive vacuole disappears.
7. What are the main divisions of the vertebrate digestive system?
The vertebrate digestive system usually consists of the mouth, pharynx, esophagus, stomach, intestines, and anus, as well as numerous glands. The digestive glands secrete enzymes (from the Latin "fermentum" - fermentation) - substances that ensure the digestion of food. The largest glands are the liver and pancreas. In the oral cavity, food is crushed and moistened with saliva. Here, under the influence of saliva enzymes, the digestion process begins, which continues in the stomach. In the intestines, food is finally digested and nutrients are absorbed into the bloodstream. Undigested residues are excreted from the body.
8. What organisms are called symbionts?
Symbionts (from the Greek "symbiosis" - living together) are organisms that feed together. For example, mushrooms - boletus, boletus, boletus and many others - grow in certain plants. The mycelium of the fungus entwines the roots of the plant and even grows into its cells, while the roots of the tree receive additional water and mineral salts from the fungus, and the fungus from the plant receives organic substances that it cannot synthesize without chlorophyll.
10. How does the digestive system of a planaria differ from the digestive system of an earthworm?
In the digestive system of a planarian, like a hydra, there is only one mouth opening. Therefore, until digestion is over, the animal cannot swallow new prey.
The earthworm has a more complex and perfect digestive system. It begins with the mouth opening and ends with the anal, and food passes through it in only one direction - through the pharynx, esophagus, stomach and intestines. Unlike the planaria, the nutrition of the earthworm does not depend on the digestion process.
11. What carnivorous plants do you know?
Sundew lives on poor soils and swamps. This small plant traps insects with the sticky hairs that cover its leaves. To them unwary insects adhere, attracted by the glitter of sticky droplets of sweet juice. They get stuck in it, the hairs tightly press the prey to the leaf plate, which, curving up, grabs the prey. A sap resembling the digestive sap of animals is released, and the insect is digested, and the nutrients are absorbed by the leaf. Another predatory plant, pemphigus, also grows in the swamps. She hunts small crustaceans using special pouches. But the Venus flytrap with its jaw-leaves can capture even a young frog. The American plant Darlingtonia lures insects into real traps - trapping leaves that look like a brightly colored jug. They are equipped with nectar-bearing glands that secrete a fragrant sweet juice, very attractive to future victims.
12. Give examples of omnivores.
Examples of omnivores are primates, pigs, rats, and others.
13. What is an enzyme?
An enzyme is a special chemical that facilitates the digestion of food.
14. What adaptations for the absorption of food are found in animals?
Small herbivorous animals that feed on coarse plant foods have strong chewing organs. In insects that feed on liquid food - flies, bees, butterflies - the mouth organs are turned into a sucking proboscis.
A number of animals have devices for straining food. For example, bivalve molluscs, sea acorns strain food (microscopic organisms) with the help of cilia or bristle antennae. In some whales, this function is performed by the mouth plates - the whalebone. Having collected water in its mouth, the whale filters it through the plates, and then swallows small crustaceans stuck between them.
Mammals (rabbits, sheep, cats, dogs) have well-developed teeth, with which they bite off and grind food. The shape, size and number of teeth depend on the way the animal feeds,
