The ability to photosynthesize in animals. Green technologies. Plants and the nutrient cycle

Eastern Emerald Elysia (Elysia chlorotica) is a unique species of marine gastropods... In the course of its evolution, Elysia became the only animal (from known to science), which uses photosynthesis for nutrition.

"Elysia chlorotica" or "eastern emerald elysia"

Elysia chlorotica lives along the Atlantic coasts of the United States and Canada. Its juveniles are initially not unusual and have a brownish color with red blotches. But as it grows up, Elysia begins to feed on algae. Vaucherialitorea, piercing her cells with his radula grater and sucking out all the contents. The chloroplasts contained inside the cell are filtered out and assimilated with the mollusk's own cells.

Recall that chloroplasts are components of plant cells, with the help of which the process of photosynthesis is carried out, that is, the process of converting solar energy into bond energy. Chloroplasts contain the photosynthetic pigment chlorophyll, which gives plants their green color.

Gradually absorbing more and more chloroplasts, the mollusk changes its color from brown to green. After the accumulation of a sufficient amount of chloroplast, the animal switches to feeding on solar energy and receives glucose in the process of photosynthesis. This skill gives Eastern Emerald Elysia the ability to survive periods when seaweed Vaucheria litorea are not available. Interestingly, even if the mollusk stays in the shade for a long time at a depth, and all accumulated chloroplasts die, the eastern emerald elysia can again begin to feed on algae and accumulate chloroplast for photosynthesis.

On the this moment Vaucheria litorea is the only known animal that can carry out the process of photosynthesis.

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Photosynthesis is the process of absorption of solar light energy by organisms and converting it into chemical energy. In addition to green plants, algae, other organisms are also capable of photosynthesis - some protozoa, bacteria (cyanobacteria, purple, green, halobacteria). The process of photosynthesis in these groups of organisms has its own characteristics.

During photosynthesis under the influence of light with the obligatory participation of pigments (chlorophyll - in higher plants and bacteriochlorophyll - in photosynthetic bacteria), organic matter is formed from carbon dioxide and water. In green plants, oxygen is released.

All photosynthetic organisms are called phototrophs because they use sunlight to generate energy. Due to the energy of this unique process, all the rest, heterotrophic organisms exist on our planet (see Autotrophs, Heterotrophs).

The process of photosynthesis takes place in the plastids of the cell - chloroplasts. The components of photosynthesis - pigments (green - chlorophylls and yellow - carotenoids), enzymes and other compounds - are ordered in the thylakoid membrane or chloroplast stroma.

The chlorophyll molecule has a system of conjugated double bonds, due to which, upon absorption of a quantum of light, it is able to go into an excited state, that is, one of its electrons changes its position, rising to a higher energy level. This excitation is transferred to the so-called basic chlorophyll molecule, which is capable of separating charge: it gives an electron to an acceptor, which sends it through the carrier system to the electron transport chain, where the electron gives up energy in redox reactions. Due to this energy, hydrogen protons are "pumped" from the outside of the thylakoid membrane to the inside. A potential difference of hydrogen ions is formed, the energy of which is spent on the synthesis of ATP.

The chlorophyll molecule, donating an electron, is oxidized. The so-called electronic deficiency occurs. In order for the photosynthesis process not to be interrupted, it must be replaced by another electron. Where does it come from? It turns out that the source of electrons, as well as protons (remember, they create a potential difference on both sides of the membrane) is water. Under the influence sunlight, as well as with the participation of a special enzyme green plant capable of photooxidizing water:

2H 2 O → light, enzyme → 2H + + 2ẽ + 1 / 2O 2 + H 2 O

The electrons obtained in this way fill the electronic deficiency in the chlorophyll molecule, while the protons go to the reduction of NADP (the active group of enzymes that transport hydrogen), forming another energy equivalent of NADPH in addition to ATP. In addition to electrons and protons, photooxidation of water produces oxygen, thanks to which the Earth's atmosphere is breathable.

Energy equivalents of ATP and NADP H spend their energy of macro-ergic bonds for the needs of the cell - for the movement of the cytoplasm, transport of ions through membranes, synthesis of substances, etc., and also provide energy for the dark biochemical reactions of photosynthesis, as a result of which simple carbohydrates are synthesized and starch. These organic substances serve as a substrate for respiration or are spent on the growth and accumulation of plant biomass.

The productivity of agricultural plants is closely related to the intensity of photosynthesis.

Some organisms are able to capture energy from sunlight and use it to make organic compounds. This process, known as photosynthesis, is essential to sustain life as it provides energy for both producers and consumers. Photosynthetic organisms, also known as photoautotrophs, are organisms capable of the process of photosynthesis and include higher plants, some (algae and euglena), and bacteria.

In photosynthesis, light energy is converted into chemical energy, which is stored as glucose (sugar). Inorganic compounds (carbon dioxide, water, and sunlight) are used to produce glucose, oxygen, and water. Photosynthetic organisms use carbon to produce organic molecules (carbohydrates, lipids, and proteins) that are needed to build biomass.

Oxygen, produced as a byproduct of photosynthesis, is used by many organisms, including plants and animals, for. Most organisms rely on photosynthesis, directly or indirectly, for nutrients. Heterotrophic organisms, such as animals, are in most cases incapable of photosynthesis or production of biological compounds from inorganic sources. Thus, they must consume photosynthetic organisms and other autotrophs to obtain nutrients.

The first photosynthetic organisms

We know very little about the earliest sources and organisms of photosynthesis. There have been numerous suggestions as to where and how this process originated, but there is no direct evidence to support any of the possible origins. There is impressive evidence that the first photosynthetic organisms appeared on Earth from about 3.2 to 3.5 billion years ago in the form of stromatolites, layered structures similar to the forms that some modern cyanobacteria form. There is also isotopic evidence of autotrophic carbon fixation around 3.7-3.8 billion years ago, although there is nothing to suggest that these organisms were photosynthetic. All of these statements about early photosynthesis are highly controversial and have caused a lot of controversy in the scientific community.

Although life is believed to have first appeared on Earth about 3.5 billion years ago, it is likely that early organisms did not metabolize oxygen. Instead, they relied on minerals dissolved in hot water around volcanic vents. It is possible that cyanobacteria began producing oxygen as a byproduct of photosynthesis. As the concentration of oxygen in the atmosphere increased, it began to poison many other forms of early life. This led to the evolution of new organisms that could use oxygen in a process known as respiration.

Modern photosynthetic organisms

The main organisms that convert the sun's energy into organic compounds include:

• Plants;
• Algae (diatoms, phytoplankton, green algae);
• Euglena;
• Bacteria - cyanobacteria and anoxygenic photosynthetic bacteria.

Photosynthesis in plants

It occurs in specialized organelles called. Chloroplasts are found in plant leaves and contain the pigment chlorophyll. This green pigment absorbs light energy needed for the photosynthesis process. Chloroplasts contain an internal membrane system made up of structures called thylakoids, which serve as sites for converting light energy into chemical energy. Carbon dioxide is converted to carbohydrates in a process known as carbon fixation or the Calvin cycle. Carbohydrates can be stored as starch, used during respiration or to make cellulose. The oxygen that is produced in the process is released into the atmosphere through pores in the leaves of plants called stomata.

Plants and the nutrient cycle

Plants play an important role in the nutrient cycle, particularly carbon and oxygen. Aquatic and terrestrial plants (flowering plants, mosses, and ferns) help regulate carbon in the atmosphere by removing carbon dioxide from the air. Plants are also important for the production of oxygen, which is released into the air as a valuable byproduct of photosynthesis.

Algae and photosynthesis

Algae are those that have the characteristics of both plants and animals. Like animals, algae are able to feed on organic material in their environment. Some algae also contain structures found in, such as and. Like plants, algae contain photosynthetic organelles called chloroplasts. Chloroplasts contain chlorophyll, a green pigment that absorbs light energy for photosynthesis. Algae also have other photosynthetic pigments such as carotenoids and phycobilins.

Algae can be single-celled or large, multicellular organisms. They live in a variety of habitats including salty and fresh aquatic environments, wet soil or rocks. Photosynthetic algae, known as phytoplankton, are found in both marine and freshwater aquatic environment... Marine phytoplankton are composed of diatoms and dinoflagellates. Freshwater phytoplankton includes green algae and cyanobacteria. Phytoplankton swim close to the surface of the water to gain better access to sunlight, which is essential for photosynthesis. Photosynthetic algae are vital to the global cycle of substances such as carbon and oxygen. They absorb carbon dioxide from the atmosphere and generate more than half of the oxygen at the planetary level.

Euglena

Euglena are unicellular protists that have been classified by the type of euglena ( Euglenophyta) with algae due to its ability to photosynthesize. Currently, scientists believe that they are not algae, but acquired their photosynthetic abilities through an endosymbiotic relationship with green algae. Thus, euglena was placed in the typology of euglenozoa ( Euglenozoa).

Photosynthetic bacteria:

Cyanobacteria

Cyanobacteria are oxygenated photosynthetic bacteria. They collect solar energy, absorb carbon dioxide and give off oxygen. Like plants and algae, cyanobacteria contain chlorophyll and convert carbon dioxide to glucose through carbon fixation. Unlike eukaryotic plants and algae, cyanobacteria are prokaryotic organisms. They lack the membrane-surrounded chloroplasts and other organelles found in plant and algal cells. Instead, cyanobacteria have double outer and folded inner thylakoid membranes that are used in photosynthesis. Cyanobacteria are also capable of nitrogen fixation, the process of converting atmospheric nitrogen into ammonia, nitrite and nitrate. These substances are absorbed by plants to synthesize biological compounds.

Cyanobacteria are found in various terrestrial and aquatic environments. Some of them are considered because they live in extremely harsh conditions, such as hot springs and hypersaline bodies of water. Cyanobacteria also exist as phytoplankton and can live in other organisms such as fungi (lichens), protozoa and plants. They contain the pigments phycoerythrin and phycocyanin, which are responsible for their blue-green color. These bacteria are sometimes mistakenly referred to as blue-green algae, although they do not belong to them at all.

Anoxygenic bacteria

Anoxygenic photosynthetic bacteria are photoautotrophs (synthesize food using sunlight) that do not produce oxygen. Unlike cyanobacteria, plants, and algae, these bacteria do not use water as an electron donor in the electron transport chain to produce ATP. Instead, they use hydrogen, hydrogen sulfide, or sulfur as their main electron donors. Anoxygenic bacteria also differ from cyanobacteria in that they do not have chlorophyll to absorb light. They contain bacteriochlorophyll, which is able to absorb shorter wavelengths of light than chlorophyll. Thus, bacteria with bacteriochlorophyll tend to be found in deep water areas, where shorter wavelengths of light can penetrate.

Examples of anoxygenic photosynthetic bacteria include purple and green bacteria. Purple bacterial cells come in a variety of shapes (spherical, rod, spiral) and they can be mobile or non-mobile. Purple sulfur bacteria are commonly found in aquatic environments and sulfur springs where hydrogen sulfide is present and oxygen is absent. Purple non-sulfur bacteria use lower sulfide concentrations than purple sulfur bacteria. Green bacterial cells are usually spherical or rod-shaped, and are generally immobile. Green sulfur bacteria use sulfide or sulfur for photosynthesis and cannot live in the presence of oxygen. They thrive in sulfide-rich aquatic environments and sometimes develop a greenish or brown color in their habitats.

Find three mistakes in the above text. Indicate the numbers of sentences in which mistakes were made, correct them.

1. Algae are a group of lower plants that live in the aquatic environment.

2. They lack organs, but they have tissues: integumentary, photosynthesizing and educational.

3. In unicellular algae, both photosynthesis and chemosynthesis are carried out.

4. In the cycle of development of algae, there is an alternation of sexual and asexual generations.

5. During sexual reproduction, the gametes merge, fertilization occurs, as a result of which the gametophyte develops.

6. In aquatic ecosystems, algae perform the function of producers.

Explanation.

1) 2 - green algae consist of identical cells and do not have tissues;

2) 3 - chemosynthesis does not occur in algal cells;

3) 5 - when gametes merge, a zygote is formed, from which a sporophyte develops, and a gametophyte develops from a spore.

Source: Demo version of the USE-2016 in biology.

Natalya Evgenievna Bashtannik

Can be supplemented, subject to other corrections :)

Anna Bondarenko 20.12.2016 20:26

2. They lack organs, but they have tissues: integumentary, photosynthesizing and educational.

Algae have neither tissues nor organs ..

Natalya Evgenievna Bashtannik

yes, and this proposal is wrong, it needs to be corrected

Ekaterina Gromova 02.11.2017 18:58

Division into sporophyte and gametophyte appears only in higher plants

Natalya Evgenievna Bashtannik

Gametophyte and sporophyte - alternation of generations, this is a sign of plants. Sporophyte is a diploid (2n) multicellular phase that develops from a fertilized egg (zygote) and produces haployd (1n) spores. Gametophyte is a haploid (1n) multicellular phase that develops from spores and produces germ cells, or gametes. Accordingly, there are male and female gametophytes.

If the sporophyte and gametophyte are morphologically identical, then an isomorphic alternation of generations occurs, if they are different, heteromorphic. In algae, creatures have both forms, in higher plants, only heteromorphic.

Vasily Rogozhin 09.03.2019 13:54

Some algae may have real tissue. These are algae with the so-called tissue (parenchymal) type of thallus differentiation. These include, for example, Porphyra (from Red algae, wrapper for rolls), Laminaria (brown seaweed "seaweed"), Ulva (green seaweed "sea salad"), known to many.

Algae cannot have ORGANS! Fabrics can be. In such "tissue" algae, even the type of thallus differentiation was called tissue (parenchymal). Reference to the source: "Botany, Algae and Fungi", Vol. 1 and 2, Belyakova G.A., Dyakov Yu.T., Tarasov K.L., Moscow State University, 2006.

Therefore, an amendment should be made to the first element of the answer: “some algae may have real tissues, but they are not divided into integumentary, photosynthetic and educational (this is the name of the tissues of higher plants).

Support service

Nevertheless, in this task from the demo version of the USE-2016, it is the specified answer that is considered correct by the examiners. Unfortunately, such inaccuracies are not uncommon on the USE in biology itself.

Diana Yesherova 24.04.2019 19:43

1. They live not only in the aquatic environment, but even in the mountains under a layer of snow.

5. When gametes merge, a zygote is formed, isn't it?

Natalya Evgenievna Bashtannik

5 point - corrected in the criteria.

And if you add 1 point correction to those specified in the criteria, it will not be a mistake.

Oxidative phosphorylation is a stage

1) photosynthesis

2) glycolysis

3) plastic exchange

4) energy metabolism

Explanation.

Oxidative phosphorylation is a metabolic pathway in which the energy generated during the oxidation of nutrients is stored in the mitochondria of cells in the form of ATP.

Answer: 4.

Answer: 4

1. Plastids are found in the cells of plant organisms and some bacteria and animals, capable of both heterotrophic and autotrophic nutrition. 2. Chloroplasts, like lysosomes, are two-membrane, semi-autonomous cell organelles. 3. Stroma - the inner membrane of the chloroplast, has numerous outgrowths. 4. Membrane structures - thylakoids - are immersed in the stroma. 5. They are stacked in the form of crystals. 6. On the membranes of thylakoids, reactions of the light phase of photosynthesis take place, and in the stroma of the chloroplast - reactions of the dark phase.

Explanation.

Errors were made in sentences:

1) 2 - Lysosomes - one-membrane structures of the cytoplasm.

2) 3 - Stroma - the semi-liquid content of the inner part of the chloroplast.

3) 5 - Thylakoids are stacked in the form of granules, and cristae are folds and outgrowths of the inner mitochondrial membrane.

Note.

1 sentence in the criteria has not been corrected, but we believe that it also needs to be corrected.

1 - Plastids are found in the cells of plant organisms and some animals capable of both heterotrophic and autotrophic nutrition.

From this proposal you need to remove bacteriasince bacteria have no membrane organelles. Among prokaryotic organisms, many groups possess photosynthetic apparatuses and, in this regard, have special structure... For photosynthetic microorganisms (blue-green algae and many bacteria), it is characteristic that their photosensitive pigments are localized in the plasma membrane or in its outgrowths directed deep into the cell.

the guest 05.02.2016 08:50

1. Plastids are found in the cells of plant organisms and some bacteria and animals, capable of both heterotrophic and autotrophic nutrition

This proposal was not flagged as erroneous. But it contains a mistake: plastids are found only in eukaryotes and are semi-autonomous descendants of prokaryotes. Photosynthetic bacteria carry out photosynthesis by thylakoids and phycobilisomes. Please correct the inaccuracy.

Natalya Evgenievna Bashtannik

If you correct the inaccuracy indicated by you when writing the answer, the point will not be counted, but it will not be reduced either.

Note.

Structure plastids in lower photosynthetic plants (green, brown and red algae) and chloroplasts of cells of higher plants in in general terms similar. Their membrane systems also contain photosensitive pigments. Chloroplasts green and brown algae (sometimes called chromatophores) also have outer and inner membranes; the latter forms flat bags arranged in parallel layers; these forms do not have facets.

Plastids are membrane organelles found in photosynthetic eukaryotic organisms (higher plants, lower algae, some unicellular organisms).

Regina Singer 09.06.2016 13:33

Plastids (from ancient Greek πλαστός - sculpted) are semi-autonomous organelles of higher plants, algae and some photosynthetic protozoa. Plastids have from two to four membranes, their own genome and protein synthesizing apparatus. Source: Wikipedia. Not words about bacteria. It is EXTREMELY WRONG to use plastids against prokaryotes.

Natalya Evgenievna Bashtannik

To use Wikipedia as a SOURCE without rechecking is extremely wrong.

1 sentence can be corrected, if it is not specified in the criteria, this does not mean that it does not need to be corrected. Read the note to the explanation.

Which of the processes provides energy to eukaryotic cells most efficiently?

1) photosynthesis

2) glycolysis

3) alcoholic fermentation

4) oxidative phosphorylation

Explanation.

Oxidative phosphorylation provides energy to eukaryotic cells most effectively.

Oxidative phosphorylation is a stage in energy metabolism.

Oxidative phosphorylation is a metabolic pathway in which the energy generated during the oxidation of nutrients is stored in the mitochondria of cells in the form of ATP.

Oxidation of two molecules of three-carbon acid, formed during the enzymatic cleavage of glucose to CO 2 and H 2 O, leads to the release of a large amount of energy, sufficient for the formation of 36 ATP molecules.

During glycolysis, two ATP molecules are formed from one glucose molecule.

Answer: 4.

Answer: 4

1) photosynthesis

2) oxidative phosphorylation

3) glycolysis

4) recovery of carbon dioxide

Explanation.

Pyruvic acid is formed during glycolysis. This is one of the stages of energy metabolism.

Answer: 3

Answer: 3

1) oxidize minerals

2) create organic matter in the process of photosynthesis

3) accumulate solar energy

4) decompose organic matter to mineral

Explanation.

Saprotrophic bacteria in the ecosystem of the lake decompose organic matter to mineral.

Saprotrophs (saprophytes) feed on dead organisms, process corpses to inorganic substances.

Saprotroph bacteria are decomposers, they decompose organic matter (proteins, fats, carbohydrates) to inorganic (carbon dioxide, water, ammonia). Inorganic substances are needed by producers (plants) for the synthesis of organic substances. Thus, decomposers, including saprotrophic bacteria, close the cycle of substances in nature.

Answer: 4.

Answer: 4

Source: Unified State Exam in Biology 04/09/2016. Early wave

All but two of the features listed below are used to describe the cell shown in the figure. Identify two signs that "fall out" from the general list, and write down the numbers under which they are indicated in the table.

1) the presence of chloroplasts

2) the presence of glycocalyx

3) the ability to photosynthesis

4) the ability to phagocytosis

5) the ability to biosynthesize protein

Explanation.

The figure shows a plant cell (because a dense cell wall, a large central vacuole and chloroplasts are clearly visible). At the same time, all types of cells are capable of protein biosynthesis. The signs "out of the general list" are the presence of glycocalyx and the ability to phagocytosis.

Answer: 24.

Answer: 24

Source: Demo version of the USE-2017 in biology.

Explanation.

1) chromatography method

2) the method is based on the separation of pigments due to differences in the speed of movement of pigments in the solvent (mobile phase in the stationary phase)

Note.

For the first time, an accurate understanding of the green leaf pigments of higher plants was obtained thanks to the work of the largest Russian botanist M.S. Colors (1872-1919). He developed a chromatographic method for separating substances and isolated leaf pigments in pure form... Chromatographic separation of substances is based on their different adsorption capacity. This method has been widely used. M.S. The color passed the extract from the sheet through a glass tube filled with a powder - chalk or sucrose (chromatographic column). The individual components of the pigment mixture differed in the degree of adsorption and moved at different speeds, as a result of which they were concentrated in different zones of the column. By dividing the column into separate parts (zones) and using the appropriate solvent system, each pigment could be isolated. It turned out that the leaves of higher plants contain chlorophyll a and chlorophyll b, as well as carotenoids (carotene, xanthophyll, etc.). Chlorophylls, like carotenoids, are insoluble in water, but highly soluble in organic solvents. Chlorophylls a and b differ in color: chlorophyll a is blue-green and chlorophyll b is yellow-green. The content of chlorophyll a in a leaf is about three times that of chlorophyll b.

Scientists have discovered animals capable of self-assimilation of the energy of the sun. At least that's what it says in, published in a journal from the reputable publication Nature Publishing Group. This amazing animal turned out to be an ordinary aphid. Outwardly unsightly insect in recent times regularly supplies biologists with scientific sensations. What are her unique abilities and whether there really are animals that do not need to search for food, tried to find out "Lenta.ru"

Generally speaking, a self-photosynthesizing multicellular animal is a sensation. Moreover, a sensation of this kind, which evokes the reaction of biologists "this can not be, because this can never be." However, the article about the amazing aphid was published in a peer-reviewed journal, which means it does not contain obvious errors. On the other hand, she did not appear in the very Nature, and in her " younger brother", a young magazine Scientific Reports... Before you understand what the essence of the work is and how fair it is to call it a sensation, you need to figure out what the study of the inconspicuous aphid gave for modern biology.

It's hard to believe, but biologists quite seriously call the bean aphid a superorganism. This term is largely artificial and in the case of many animals it looks tense. They are called "organisms consisting of many organisms" and usually means colonial insects. Aphids, however, are not a colonial insect, but at the same time they are, of course, a superorganism.

This humble insect feeds on plant sap, sucking it directly from the vessels that transport sugar from the leaves to the root. It is good that aphids closely interact with ants. The latter provide her with protection from enemies in exchange for droplets of sugar syrup. Aphids do not mind a sweet tribute for ants - they still cannot assimilate the amount of sugar contained in plant juice.

This is one of the paradoxes of aphid nutrition - despite the fact that animals consume much more sugar than they can assimilate, in a sense, they are constantly starving. The fact is that vegetable juice contains almost nothing but sugar, and insects live in conditions of constant lack of amino acids, fats, vitamins and microelements. Even when there are no ants nearby, aphids still emit a sweet solution, having previously filtered out substances useful for it.

Soon after the discovery of symbiotic buchneria in aphids, entomologists found their neighbors. They turned out to be bacteria Serratia symbiotica, which settled in aphids much later than buchneria and have not yet lost the ability to live outside the host. In some aphids, however, the cooperation of aphids, buchneria and serratia has already advanced greatly - it turned out that some amino acids of serrata help to synthesize pampered buchneria, who have lost this ability.

The third lodger of the aphid superorganism turned out to be protective bacteria. Scientists have found that Hamiltonella defensa helps aphids in the fight against riders. These wasps are, along with ladybirds, one of the main enemies of aphids. Riders lay eggs in their bodies. The rider larva, when hatching from the egg, eats the aphids from the inside, and uses their mummified body instead of a cocoon. At one time, this cruelty of the riders made such a strong impression on Charles Darwin that he put forward their existence as one of the arguments against the existence of an all-good God.

The last of the currently known lodgers of aphids were bacteria that help synthesize bright pigments. It turned out that the bright green color of aphids is determined by intracellular bacteria Ricketsiellathat help aphids synthesize their specific polycyclic dyes - athens. Why insects need it is still difficult to say, but it is known that color plays an important role in the interaction of an insect with predators. Of individuals of the same species, riders, for example, prefer green ones, and ladybugs - red aphids.

Speaking of animals with an unusual way of feeding, one cannot fail to mention the unique mollusk Elysia chloroticawho have mastered "green technologies". In the early stages of its development, it looks and behaves like an ordinary sea slug - it feeds on algae and has a brownish color. However, unlike all other herbivorous animals, he, as economists would say, prefers a fishing rod to fish. Simply put, the mollusk absorbs the photosynthetic chloroplasts of the algae Vaucheria litorea, and keeps them alive inside their cells. Plants did the same at the dawn of their evolution, once absorbing blue-green algae. The difference is that chloroplasts enter the mollusk cells helpless - over millions of years of co-evolution, they have transferred the synthesis of ninety percent of the necessary proteins to their owners. Therefore, the mollusk has to go to tricks to preserve the fragile endosymbionts. He copied some genes responsible for photosynthesis directly from the genome. Vaucheria, as a result of which it was able to support the life of chloroplasts for about nine months. This is how long it lasts life cycle.

With the coloring of aphids, not everything is simple either. It is partly determined by Athens and partly by carotenoids. For the synthesis of the former, rickettsiella are responsible, as already mentioned, but the situation with carotenoids is even more interesting. The fact is that carotenoids are very common pigments, but no animal can synthesize them. Retinol, or vitamin A, is half of the carotene molecule. As a pigment that directly perceives light, it is used in the eyes of absolutely all organisms - from unicellular organisms to humans. In addition, carotenoids play an important and still not fully understood role when interacting with reactive oxygen species. However, all animals are forced to receive carotenoids from their food.

Nevertheless, even the authors of the article themselves did not understand why aphids need to synthesize carotenoids on their own and why their bodies contain so many of these substances.
Two years later, French scientists, they know why - in their opinion, aphids use carotenoids to supply solar energy.

It must be said right away that biologists call photosynthesis the fixation of carbon dioxide from the air and its transfer into organic matter due to the energy of the sun. The use of light energy itself is called phototrophy, and the organisms in which it occurs are called photoheterotrophs. However, this phenomenon is so rare compared to photosynthesis that even the scientific editors of Nature News made a mistake in the title.

It was about phototrophy that was discussed in the last article of French scientists. They found that insects that are grown at different temperatures environment, acquire different colors. This, according to the authors, occurs with the help of epigenetic mechanisms - making changes not in the DNA itself, but in the way it is read. Be that as it may, those animals that were raised at 8 degrees Celsius turned green, and those that grew at 22 degrees - orange. There was also a group of just pale insects that lived in conditions of increased crowding and lack of resources. Green aphids contained the highest amount of carotenoids of any cousin.

Elysia pusilla... Click to enlarge. Photo from blogs.ngm.com

So, it turned out that if aphids are exposed to light after being imprisoned in the dark, the concentration of ATP, the energy currency of every cell, increases significantly in its body. Moreover, the energy recharging of the green aphid is much faster than that of the orange one. In pale insects, devoid of any pigments, it is clear that the difference in ATP reserves in the dark and in the light was not observed. In addition, the pigment was distributed directly under the surface of the insect's cuticle, where the greatest penetration of sunlight is.

It turns out that the aphids have learned to extract the energy of the sun? Moreover, they have overtaken specialists in this - plants, since they do without chloroplasts and chlorophyll at all, but for this they use ordinary carotenoids synthesized by seven genes stolen from mushrooms?

To be honest, this is very hard to believe. To the authors' credit, they only suggest the possibility of phototrophy as a hypothesis, and do not consider it proven. Every reader of an article in Scientific Reports many questions immediately arise. First, it is not clear how exactly the electronic excitation accumulated by carotene is transmitted. The authors believe that excited electrons are transferred to ATP synthase, but there is no evidence of this yet. Second, it is not clear which genes are involved in the process. Thirdly, it has not been shown in which cells the ATP content increases - in those cells that contain carotenoids or not. Fourth, it has not been shown - do the observed changes occur in the cells of the aphid or within its numerous, as we have seen, endosymbionts?

However, all these questions seem to be common quibbles after remembering the most important fact about the life of aphids - what it eats. One of the authors of the same article in Science, which showed the horizontal transfer of genes for the synthesis of carotenoids, commented on the new work as follows: "Getting energy is the smallest problem in the life of aphids. Her diet consists of a little less than all sugar, most of which she cannot use."
In light of this fact, the discovery of plant abilities in an insect looks very suspicious.