Federal State Educational Institution of Higher Professional Education "Moscow State University named after M.V. Lomonosov

Easily brushing away a web while cleaning or walking through the forest, few people think about how and from what the spider wove it. But this is a unique creation of extraordinary strength. We will find out how spiders weave their web, where they get the material for it and what it consists of, its shape and purpose, as well as how this natural material can be used by humans.

What does it consist of and where is it formed?

The composition of the web includes the following substances:

organic compounds- fibroin protein, which makes up the main internal thread, and glycoproteins that form nanofibers located around the main thread. Thanks to fibroin, the web is similar in composition to silk, but much more elastic and stronger;
inorganic substances- chemical compounds of potassium (hydrogen phosphate and nitrate). Their number is small, but they give the web antiseptic properties and protect it from fungi and bacteria, creating a favorable environment in the spider’s glands for the formation of threads.

In the abdomen of the spider there are arachnoid glands, where a liquid substance is formed that comes out through spinning tubes located on the arachnoid warts. They can be observed at the very bottom of the abdomen.

A viscous liquid comes out of the tube and quickly hardens in air. Using its hind legs, the spider pulls out the thread and uses it for weaving. One spider is capable of producing a thread 0.5 km long.

Did you know? Our most common spider, the cross spider, weaves the most famous round trapping net. The spider always weaves a structure of 39 rays, on which there are 35 spiral circles with 1245 fasteners. The cross workers do this work at night and updatenet every 1–2 days.

What are the types?

Spiders, depending on the species, can weave different webs.

The form could be as follows:

How and how long do spiders weave webs?

The spider weaves the most famous circular web for 0.5–3 hours. The duration of weaving depends on the size of the mesh and the weather. In this case, the wind usually becomes the best assistant, carrying the thread released by the spider over considerable distances.

It is in the direction of the wind that the web stretched between the trees is located. A thin thread is carried by the air flow, clings to a nearby tree and perfectly withstands the movements of its creator.

He periodically renews the woven net, as over time it loses its ability to hold prey.

The spider usually eats old webs to provide itself with the building material needed to weave a new product. Automatic actions for building a network are laid down at the genetic level and are inherited.

Properties and Functions

The web has the following properties:

Very durable. Thanks to its special structure, its strength is comparable to nylon, and it is several times stronger than steel.
Internal articulation. An object suspended on a spider thread can be rotated in one direction for as long as desired without twisting.
Very thin. The spider thread is extremely thin compared to the threads of other living creatures. In many families of spiders it is 2–3 microns. For comparison, the thickness of a silkworm thread is in the range of 14–26 microns.
Stickiness. The threads themselves are not sticky, they are dotted with drops of sticky liquid. However, to create a web, the spider produces not only a sticky thread, but also a thread devoid of glue particles.

Did you know? It was possible to breed a species of silkworms that produce spider silk. Researchers from America were able to develop a technology that makes it possible to produce silk fibers that have the properties of spider web threads. Developments in this direction are still underway, but it is currently impossible to establish the production of such fibers on an industrial scale.

The web is necessary for the life of the spider.
It performs the following functions:

Shelter. The woven web serves as a good shelter from bad weather, as well as from enemies in the natural environment.
Creation of a favorable microclimate. For example, in water spiders it is filled with air and allows them to stay under water. They also use it to cover the shells in which they live at the bottom.
Trap for food items. The spider is carnivorous and its diet consists of insects caught in a sticky web.
Material for creating a cocoon from which new spiders emerge.
A device that plays a role in the process of reproduction. During the mating season, females weave a long thread and leave it hanging so that a passing male can easily reach them.
Deception of predators. Some orb-weaving spiders use it to glue together debris and make dummies to which they attach a thread. In case of danger, they pull the thread and distract attention from themselves with a moving dummy.
Insurance. Before attacking a victim, spiders attach a web thread to some object and jump on the prey, using the thread as insurance.
Vehicle. Young spiders leave their “father’s house” with the help of a long thread. Spiders that live in bodies of water use webs as water transport.

How can a person use the web?

In China, the fabric made from spider webs, which is amazingly durable and light, is called “fabric of the eastern sea.” Polynesians use the web threads of large web spiders for sewing, and in addition to this, they also weave nets from them for catching fish.

Scientists from Japan were able to create violin strings from spider silk. Nowadays, scientists are striving to synthesize a material with the properties of spider thread for use in various fields - from the production of body armor to the construction of bridges.

But science is not yet able to create an analogue of the substance that the spider produces. To do this, some researchers are trying to introduce spider genes into other living organisms.

Dutch biologist Abdul Wahab El-Halbzuri and artist Jalil Essaydi, through research, synthesized super-strong fabric, which is an organic combination of spider web and human skin.
Previously, the strongest fabric was considered to be Kevlar fibers produced by DuPont, which are 5 times stronger than steel - and the material obtained using spider threads is 15 times stronger than steel. But such a synthetic substance has a number of disadvantages, which scientists are still working on.

The web is notable not only for its strength. The antibacterial properties of such spider products have been used for a long time. Even in ancient times, people used spider webs as bandages.

This sticky material adhered to the skin and created a barrier for bacteria and viruses to enter the wound. Many research institutions are working with spider silk, trying to apply its properties in medicine to create a material that can regenerate limbs.

Scientists in Europe say that within 5 years they will be able to synthesize artificial tendons and ligaments from arachnoid threads.

Important! The use of spider webs in the field of medicine is primarily due to the fact that the human body does not reject the spider protein introduced into it.

In the modern world, spider web threads are used in the optical industry to designate crosshairs in optical devices, and also as threads in microsurgery. It is also known that microbiologists have created an air analyzer using the properties of spider threads to capture microparticles from surrounding traces.
It should be noted that studying the properties of the web will make it possible in the future to achieve great results in many industries, as well as contribute to the development and emergence of advanced technologies important for humanity.

Why doesn't a spider stick to its web?

While hunting for its victims (flies, midges and other insects), which become entangled in the sticky nets placed, the spider itself does not stick to its own trap.

Let's consider the factors due to which the spider does not stick to its product:

Not all spider webs are covered with an adhesive liquid, but only some areas that are well known to its creator. It is the circular threads that are sticky, and the central ones are not saturated with an adhesive substance.
The spider's legs are completely covered with short and thin hairs. These hairs quickly remove droplets of glue invisible to the eye from the threads of the web. When the paw is on a section of the spider web, particles of glue are on the hairs. When the spider removes its leg from an area without glue, the hairs, when sliding on the thread, return the glue particles back.
A special substance that coats the spider's legs reduces the level of interaction with the glue, which further helps against sticking.

Video: about the web of spiders So, the web is synthesized in the arachnoid glands located on the abdomen of spiders, and has a predominantly protein composition. These arthropods weave it for different needs, and it comes in different shapes.

Important! Dust accumulated on the spider web, as well as insects entangled in it, contribute to the creation of unsanitary conditions in the living room. So don't forgetremove cobwebs when cleaning.

Moreover, it has extraordinary properties that humanity can use for their own purposes. Scientists from different countries are trying to synthesize a substance similar to it.

Practical benefits of the web.

Every Most of us are well aware of the web: we have repeatedly encountered cobwebs in the forest, and even in our own home. They brush cobwebs out of the corners with a broom, and in the forest, when they accidentally land their face in them, they shake them off with displeasure.

Meanwhile, spider web is a very interesting and useful natural material in practical applications, the enormous importance of which has undeservedly been overshadowed today by numerous synthetic polymers.

The finest threads of the oldest web were discovered in a piece of amber by workers at the University of Oxford in East Sussex. The age of the unique find is estimated at approximately 140 million years. Until this point, the oldest was considered to be a web in a piece of amber found in Lebanon, dated 130 million years ago, and the oldest spider was found in amber about 120 million years old. Amber, formed more than 100 million years ago, is extremely rare.

Using the most modern ultramicroscopy technologies, scientists were able to identify the oldest spider web, the length of the threads of which was slightly more than a millimeter. Interestingly, the web is similar to the one weaved by modern spiders. The location of the discovered threads made it possible to establish that they were supports for the orb web. The same piece of amber preserved two skeins of ancient cobwebs.

Thanks to this discovery, the paleobiologists who studied it suggested that arachnids are actually much more ancient creatures than previously thought. Previously, it was believed that the wide distribution of flying insects, which served as prey for arachnids, was caused by the appearance of flowering plants on our planet. After studying the discovery of Oxford scientists, it was suggested that the oldest arachnids hunted crawling and jumping insects by weaving webs on the soil surface.

In addition to the cobwebs, the same piece of amber preserved charred particles of burnt bark and sap of a coniferous tree. Presumably, the tree released resin that absorbed the cobwebs and subsequently turned into amber during a forest fire.

Spiders themselves use webs to build shelters, lining burrows, trapping nets and egg cocoons; males make a sperm net out of it for the purpose of reproduction. In the juveniles of some spiders, long threads of web serve as parachutes when dispersing by wind. When making a catch net, the spider first tensions the frame and radial threads, then lays a temporary support spiral thread, and only after that weaves an adhesive spiral catch net, after which the cut bites off the support thread.

Spider web is a protein enriched in glycine, alanine and serine. Inside the arachnoid gland it exists in liquid form. When secreted through numerous spinning tubes that open on the surface of the arachnoid warts, the structure of the protein changes, as a result of which it hardens in the form of a thin thread. Subsequently, the spider weaves these primary threads into a thicker web fiber.

The backbone of the web consists of two proteins: the stronger spidroin-1 and the more elastic spidroin-2. It is the combination of their properties that determines the unique properties of the web.

The web can have a diameter of up to several millimeters and consists of very thin threads. The web is extremely thin and light. To encircle the equator of our planet, it would take only 340 g!

Scientists are most interested in the frame thread of the web, which is unusually strong and elastic. Few people know that spider thread is close to nylon in strength - its tensile strength ranges from 40 to 260 kg/mm2, which is several times stronger than steel. If the web had a diameter of 1 mm, it could support a load weighing approximately 200 kg. Steel wire of the same diameter can withstand significantly less: 30-100 kg, depending on the type of steel. In addition, it is unusually elastic.

Interestingly, when the web gets wet, it contracts greatly (this phenomenon is called supercontraction). This occurs because water molecules penetrate the fiber and make the disordered hydrophilic regions more mobile. If the web has stretched and sagged due to insects, then on a humid or rainy day it contracts and at the same time restores its shape.

Another unusual property of a spider's web is its internal articulation: an object suspended on a spider's web fiber can be rotated indefinitely in the same direction, and at the same time it will not only not twist, but will not create a noticeable counterforce at all.

As you know, people extracted natural threads from natural materials with quite a lot of ingenuity. Subsequently, fabrics appeared from such threads - from wool, cotton, flax, nettle, and even from the finest threads of silkworm cocoons. However, the use of the web opens up new prospects in this direction, because is an excellent material for making durable and lightweight fabrics.

The first attempt to make such fabric was made three centuries ago by the French scientist and entomologist Bon, who presented his proposals to replace imported silk with spider silk to the Royal Scientific Society. As a sample, stockings and gloves made from spider silk were included. The scientist’s idea did not find support due to the difficulty of mass breeding of spiders. Nowadays there is a solution to this problem, but the emergence of a large number of synthetic threads has sharply reduced the demand for spider silk.

Exceptional in strength, lightness and beauty, spider web fabric is still used today and is known in China under the name “Eastern Sea Fabric”. Polynesians used the web of large web spiders as thread for sewing and weaving fishing gear. At the beginning of the 18th century in France, gloves and stockings were made from the web of crosses, which aroused universal admiration. It is known that up to 500 m of thread can be obtained from one spider at once. In 1899, they tried to obtain fabric to cover an airship from the web of a large Madagascar spider and managed to produce a sample of luxurious fabric 5 m long.

Today, spider web threads are used mainly in the optical industry for applying crosshairs in optical instruments and as threads in microsurgery, and due to their high content of bactericidal properties, they can be successfully used in medicine as suture material, artificial ligaments and tendons, films for healing wounds, burns, etc.

It is impossible to synthesize this kind of proteins in the laboratory chemically - they are too complex. However, scientists managed to create some kind of artificial analogue using biotechnological technologies. This thread was tested for strength by specialists at the Uglekhimvolokno Research Center in Mytishchi. A thread just a few microns thick can withstand 50-100 mg of load at break. It turned out to be only four times less durable than that of a spider, and this is a very good result. At the same time, the value of the rupture energy (elasticity) of this thread is already higher than that of bone or tendon.

Not only threads, but also films can be made from cobwebs. It is in this form that it is planned to use “artificial web” to make healing coverings for wounds and burns, which will not be rejected by the body and will stimulate the regeneration of its own epithelium.

Attempts have been made to obtain cobwebs naturally, similar to silk. Various devices were even invented for “milking” the spider and carefully winding the delicate threads onto a slowly rotating spool.

There were several obstacles. Firstly, the quarrelsome nature of spiders: when kept together, these animals quarrel and eat each other. Secondly, each spider produces very little web: it is estimated that 27 thousand average-sized spiders will be needed to produce 500 g of fiber. It is clear that the productivity of arthropods is unlikely to satisfy industrial demands. There is only one way out: learn to obtain it artificially.

Residents of the Pacific Islands “force” spiders to weave fishing nets that are unusually strong and almost invisible in the water. And on the island of Madagascar, located near the eastern coast of Africa, many villagers still use spider webs instead of threads.

The technology, developed about a hundred years ago by a French preacher, made it possible to collect golden webs from a million Madagascar spiders.

Art critic Simon Peers and his American business partner Nicholas Godley hired several dozen workers to create a unique canvas measuring 3.4 by 1.2 meters.

The suppliers of “threads” were a million orb-weaving spiders (golden orb spiders), belonging to the genus Nephila. The scientist and entrepreneur spent almost five years of his life and about $500 thousand to produce a piece of perhaps the most unusual fabric.

Goodley first came to Madagascar in 1994, where he created a small company producing goods from fibers of the Raphia palm tree. In 1999, Nicholas released his first collection of fashion bags (apparently from the same material), and in 2005 he closed the factory and completely switched to the production of “spider fabric” together with Pierce.

Goodley was inspired to create this unusual painting by stories about how, in the 19th century, the French governor of one of the Madagascar provinces tried to do something similar. However, Nicholas did not know for certain whether these stories were true or fiction.

In fact, spider silk is not particularly popular among the inhabitants of Madagascar (this is understandable, since the “standard” silkworm is much easier to grow). However, in the 19th century, subjects of the Merina Kingdom still decided to work with him. Products made from spider webs were presented to members of royal families. There was even a special tradition of weaving threads.

Pearce and Goodley's work began when they hired 70 workers to collect spiders of the species Nephila madagascariensis near the capital of Madagascar, Antananarivo.

Only females create a unique, durable web with a golden hue. The collection took place during the rainy season, since arthropods produce their webs only at this time of year (which imposes additional restrictions on the production process of the web).

To create a kind of spinning factory, the spiders were placed in special chambers where they were kept motionless. It must be said that Nephila madagascariensis are not poisonous, but bite. They may also escape or eat each other. “At first we had 20 females, but we soon ended up with three, but they were very fat,” says Pierce.

So, in the end, the restless creatures were isolated from each other, while simultaneously increasing the number of individuals simultaneously living in the factory.

Ten workers were collecting webs hanging from the spiders' spinning organs. In this way, it was possible to obtain about 25 meters of precious material from one individual.

Pearce notes that fourteen thousand spiders produce approximately 28 grams of spider silk, and the total weight of the final piece of fabric was as much as 1180 grams!

Next, to create the primary thread, weavers manually twisted 24 pieces of web into one, four primary ones were then turned into one main thread (a total of 96 pieces), and only from this they wove the fabric. You can imagine how painstaking the work must be.

Material from spider webs will be useful on the battlefield, in surgery and even in space, many experts are sure. The Institute of Bioorganic Chemistry of the Russian Academy of Sciences, as well as the Institute of Transplantology and Artificial Organs, are interested in obtaining products from spider web proteins.

In folk medicine there is such a recipe: to stop the bleeding, you can apply a cobweb to a wound or abrasion, carefully clearing it of insects and small twigs stuck in it. It turns out that spider webs have a hemostatic effect and accelerate the healing of damaged skin. Surgeons and transplantologists could use it as a material for suturing, strengthening implants, and even as a blank for artificial organs. Using spider webs, the mechanical properties of many materials currently used in medicine can be significantly improved.

In different countries, biotechnology companies have learned to produce artificial analogues of spider webs, but they are still far from achieving the perfection of a natural polymer. It can only be achieved by understanding which physical or chemical structural features are responsible for the unique mechanical properties of the web, and success in solving an applied problem directly depends on the results of fundamental research.

Since 2007, a group of researchers from the Department of Bioengineering, Faculty of Biology, has been involved in this work Moscow State University named after M.V. Lomonosov under the guidance of Doctor of Physical and Mathematical Sciences, Professor K.V.Shaitana, and the results of their research lifted the curtain on some of the secrets of this natural polymer.

But what does it have to do with it? biotechnology? Maybe cobwebs can be produced naturally, like silk? After all, the production volumes of silk threads from cocoons woven by silkworm caterpillars are very significant. Such attempts have actually been made; various devices have even been invented for "milking" the spider and carefully winding delicate threads onto a slowly rotating spool (Debabov and Bogush, 1999; Work and Emerson, 1982).

There were several obstacles. Firstly, the quarrelsome nature of spiders: when kept together, these animals quarrel and eat each other. Secondly, each spider produces very little web: it is estimated that To produce 500 g of fiber, 27 thousand spiders will be required medium size. It is clear that the productivity of arthropods is unlikely to satisfy industrial demands. There is only one way out: learn to obtain it artificially.

The 90s of the last century and the beginning of this century were marked by a growing stream of research into the properties and structure of the web. Particularly great interest was shown in the UK, Germany, the USA and Japan. It was found that the web has a protein nature similar to silk. Spiders have several types of arachnoid glands and different types of webs:

one is for the construction of cocoons, where females lay eggs,
the other is for parachuting, if you have to flee,
sticky - for the construction of the catching part of the web,
frame - on which it is superimposed.

The strongest web is frame, and it has been studied better than others. It is dominated by two proteins, called spidroins(from the English spider - spider). They are very long - each contains 2.5-3 thousand amino acid residues.

One of the proteins of the frame web orb weaving spider Nephila clavipes, widespread in the southern United States, with a fishing net up to a meter in diameter, was named spidroin-1, another - spidroin-2. The first is slightly shorter than the second: the molecular weight of spidroin-1 is 275 thousand atomic mass units, spidroin-2 is 320.

In different species of spiders, these proteins differ slightly both in size - from 180 to 720 thousand amu, and in the sequence of amino acids, but they all have a common feature - repetition of the same or almost identical amino acid sequences, including a section of several consecutive residues alanine (usually four to nine) and a region with frequent repetition of glycine residues.

The physicochemical properties of proteins are determined by the characteristics of their amino acid sequences, and spidroins are no exception. A unique property of spidroins is the alternation of segments rich in glycine and alanine. It is this that determines how the molecule is folded in space, how several molecules fold into fibril and ordered packing of such fibrils into nanofibrils spider fiber, and, in addition, at the ends of the molecules there are special groups of several dozen amino acids with hydrophilic properties.

Thanks to the significant efforts devoted to studying all these levels of spatial organization of spider web proteins, much has become clear, although complete clarity is not yet complete.

First, main question: due to which the remarkable mechanical properties of the web are achieved?

Studies using X-ray diffraction analysis (Warwicker, 1960; Glisovic and Salditt, 2007) showed that in the secretion of the arachnoid gland, threads of several protein molecules form many dense packs measuring 2 × 5 × 7 nm. It is believed that these are closely adjacent alanine sites. Such structures are called β-sheets. Many researchers of spider silk believe that the web owes its strength to them, and fragments rich in glycine curl into spirals and provide elasticity (Simmons et al., 1994; Parkhe et al., 1997, van Beek et al., 2002, etc. .).

To further understand the processes occurring at the molecular level, biologists from Moscow University turned to computer modeling. It allows, in a numerical experiment, based on data on the structure of molecules and the energy of interatomic interactions, to determine such properties of molecules as elongation and tensile strength, to observe how molecules interact with each other - in a natural experiment this is extremely difficult, if not achievable. Numerical experiments were carried out using supercomputer technologies.

“Using the example of arachnoid fiber peptides, we were able to show that the stability of the secondary structure depends not only on the amino acid sequence, but also on the molecular environment,” says the author of the study I. Orshansky. “Complexes of several peptides have a more stable secondary structure, both in the case of polyalanine peptides and in the case of interalanine peptides.”

And yet it remains a mystery: what makes the liquid secretion turn into a wonderful strong thread - solid and insoluble?

If this could be found out in detail, the key to reproducing this process would appear, and therefore to artificially obtaining a thread with the same qualities. In addition, the spider does this quickly, which means high productivity can be achieved.

It is now known (Scheibel et al., 2009) that during the “maturation” of the web, before leaving the spider gland, the spidroin solution undergoes many changes: the spider tissues extract water from it, due to which the concentration of proteins increases, and they are extracted from the surrounding solution sodium and chlorine ions, but the content of potassium, phosphate ions and hydrogen increases, while the reaction of the medium decreases from 6.9 to 6.3 and becomes slightly more acidic.

As a result of all these and other, not yet taken into account, processes, the protein quickly changes configuration. And, what’s most remarkable, this happens at ordinary temperature and pressure and without the use of toxic reagents, which, for example, have to be used in the production of other synthetic polymers, in particular Kevlar, and without toxic waste. It is also known that the tension of the released thread affects its strength: if a fresh thread is stretched with force, the web turns out thinner and stronger.

To date, some success has been achieved in obtaining artificial spider webs. Early 90s American researchers cloned in cells Escherichia coli spidroin genes that make up the backbone of the spider Nephila clavipes. It has become possible, using genetic engineering techniques, to insert spidroin gene fragments into the genomes of other organisms and isolate the protein synthesized from them in vivo.

For similar purposes, the same bacterium Echerichia coli is often used, but this technology is not suitable for spidroins: their molecules are too large for bacteria, so biotechnologists turned their attention to larger organisms.

IN Germany managed to implant orb weaving genes into the genomes of potatoes and tobacco, and the yield of spidroin amounted to up to 2% of the total protein mass of these plants.

IN Japanese Shinsu University inserted the spidroin gene into the genome of the silkworm Bombyx mori, now their caterpillars produce fiber consisting of 10% spider web proteins.

Canadian Biotech firm Nexia has reported that it has successfully introduced the spidroin gene into first hamsters and then goats, resulting in proteins that can be isolated from their milk, albeit in very small quantities. But most often, incl. in Russian biotechnological laboratories, for these purposes they use yeast - Pichia pastoris, which oxidizes methane, and brewer's yeast - Saccharomices cerevisiae.

IN Russia recognized leader in the production of artificial spidroins - State Research Institute of Genetics and Selection of Industrial Microorganisms(GosNIIGenetics). Since 2001, a scientific group led by academician of the Russian Academy of Agricultural Sciences, corresponding member of the Russian Academy of Sciences, professor V.G. Debabova is developing methods for the production of recombinant spidroins.

From the known nucleotide sequence of the cDNA of the orb-weaving spider Nephila clavipes, biotechnologists selected several typical sections, synthesized the corresponding genes and inserted them into the yeast genome. The solution prepared from the isolated protein is “spun”, released through a tiny hole into concentrated ethyl alcohol, where it turns into fiber.

Their colleague from Institute of Bioorganic Chemistry RAS D.V.Klinov developed a method for producing films of different thicknesses from a solution by electrospraying. By adjusting the protein content of the initial solution and the concentration of alcohol, and changing the course of subsequent processing, which includes stretching in alcohol, soaking in water and hot drying, the researchers try to select conditions for creating the strongest and most elastic fiber.

Working with artificial web has not only applied, but also fundamental scientific meaning.

“This problem is at the intersection of biology, protein engineering and materials science,” says K.V., professor of the Department of Bioengineering, Faculty of Biology, Moscow State University. Shaitan. “Understanding how the amino acid sequence affects the properties of nanofibers will open the way to the artificial creation of nanofibrils with desired capabilities.”

Specialists from the Department of Bioengineering, Faculty of Biology, Moscow State University, together with colleagues from the State Research Institute of Genetics and Institute of Transplantology and Artificial Organs The Ministry of Health and Social Development of the Russian Federation is studying the properties of the thread at different stages of its processing in order to unravel the mysteries of its secondary, tertiary and quaternary structure (Bougush et al., 2008).

By examining the surface and fractures of fresh, unprocessed artificial thread—a sort of analogue of the mature spinning solution in the arachnoid gland—under an electron scanning microscope, they discovered that the thread was actually a hollow tube of spongy material, riddled with many spherical holes with a diameter of 0.15 -1 micron, and in the thickness of the solid material there are protein globules of the same size. Smaller globules with a size of 50-250 nm are found on the surface of the threads with some processing options.

Scientists have noticed that formations of the same shape and size are also found in the spinning solution of spiders - maybe these are the same micelles, on which the Americans' hypothesis is based? But the fragments of spidroins synthesized at GosNIIgenetika are devoid of specific terminal fragments characteristic of natural spidroins! This means that the way molecules are packaged into micelles is different than expected in existing hypotheses.

If a thread of recombinant spidroin is stretched before being removed from alcohol - this is seen as an analogy of a spider spinning a natural web - then its structure will change: thin fibrils with a diameter of 200-900 nm appear, they can be seen using an atomic force microscope. The natural web also contains microfibrils, however, they are ten times thinner.

Upon closer examination, the thin fibrils turned out to be more like beads: they alternate between thickening and thinner areas. Under a transmission electron microscope, which allows one to examine the object through transmission and at higher magnification, inclusions with a diameter of 10-15 nm were found inside the microfibrils, which are grouped into longitudinal structures up to 250 nm long. There is reason to believe that these are clusters of the same nanofibrils, which provide the unique mechanical properties of natural spider webs.

E. Krasnova, Candidate of Biological Sciences

In the 18th century, a certain Bon from Montpellier knitted himself a pair of stockings and gloves from spider webs. This experience of using spider thread for textile purposes turned out to be the only one. Currently, spider webs are used only as crosshairs for precision optical instruments.

The web is synthesized from amino acids in the spider's blood. This happens in the cells located in the walls of the arachnoid glands. The web is produced in droplets; they merge in the hollow central part of the gland. This viscous liquid is actually a concentrated solution of spider webs. The solution accumulates in the glands until the spider has a need for the web and it is drawn from the ducts of the arachnoid warts. The web quickly stretches into a thin thread and immediately passes from a viscous state to a solid one.

Substances that can be drawn into threads are usually high molecular weight polymers. They consist of long thin molecules. Molecules are twisted when in solution. However, if they are pulled from a thin hole, they unfold and are positioned along the entire length of the fiber. The molecules are held in this position by cross-links that form between adjacent chains.

When moving, the spider usually weaves a double thread - the so-called hanging thread. It keeps it from falling and is attached with connecting discs whenever the spider needs to descend.

The hanging thread is sometimes reinforced by two thinner threads. They are also used to make the outer frame and radial threads of the fishing net. The other main part of the catch net is the spiral thread; it actually captures the flies that fall on it.

The entire network is very sticky and extremely elastic. What makes it sticky is the many droplets of a very viscous substance that covers both webs and holds them together. At the slightest contact with the viscous thread, the fly sticks. The thread can stretch without breaking, no matter how strong the victim is. This usually results in the fly becoming entangled in nearby sticky threads. Holding the fly, the spider rotates it with its jaws, toes and front legs, while its hind legs pull out the web from the arachnoid warts. The fly thus ends up in a web “bandage”, and the spider often takes the victim to its shelter, where it will either be eaten immediately or be hung up “in reserve”.

There is another web; it is used to make a cocoon. The spider envelops the eggs laid in the fall with this thread. The cocoon protects the eggs from bad weather and attacks from various predators.

The web consists of proteins. Proteins are known to play a vital role in the structure and functioning of all living organisms. They consist of myosin in muscles, collagen in connective tissues, hemoglobin in the blood, as well as enzymes that control all chemical reactions in a living organism.

Proteins are large molecules built from twenty different amino acids. A spider web protein molecule may consist of one or more chains linked in one or more places. Strong cross-links are formed by the amino acid cystine and can “cling” to two different chains. Cystine can also form bonds between different parts of the same chain, forming loops.

Twenty amino acids can form a huge number of different proteins. One of the main goals that protein chemists strive for is to determine the number of amino acids in a protein and their relative positions.

To determine the amino acid composition, it is decomposed into its constituent amino acids by boiling in hydrochloric acid. Then all components are isolated from the mixture of amino acids. Twenty-five years ago this was a rather complicated procedure, requiring a large amount of material and time and, moreover, not always giving accurate results. Currently, a complete amino acid analysis can be performed on a few milligrams of material in a single day. Scientists have created a device in which a mixture of amino acids is first decomposed into components, and then their quantities are automatically recorded and recorded in the form of graphs.

These analytical methods have been used to analyze a number of webs. There is a big difference in the composition of the cocoon thread and the hanging thread. The main amino acids of the first are alanine and serine, the second are glycine and alanine. More than half of the protein in each case is made up of only two amino acids, although many other amino acids are also present. Most of the web contains amino acids with very short side chains.

Knowing how amino acids are arranged in protein is very important. But this still does not make it possible to explain all the properties of fibers. These properties depend largely on how the chains are positioned relative to each other.

In 1913, father and son Bragg showed that a crystal of any substance, rotated in X-rays, reflects them at certain angles, since it consists of orderly arranged atoms that form planes of reflection. In the same year, two Japanese - Nikishawa and Ono - discovered that many fibers, which were supposed to have no crystalline structure, also give certain reflections.

Existing X-ray diffraction patterns of spider threads look insignificant when compared with X-ray images of true crystals, but they can provide significant information about the structure of the web. The fact that such an X-ray pattern contains spots indicates the presence in the fibers of the web of crystalline regions with an ordered arrangement of atoms. The credit for determining the structure of these crystalline regions goes primarily to Professor Linus Pauling of the California Institute of Technology and Professor Warwicker.

Thanks to these studies, we know that almost all types of webs have a similar structure. An approximate idea of it can be obtained by drawing several equally spaced parallel lines on a piece of paper, and then folding this sheet at right angles to the lines. The lines represent the long peptide chains, and the places where they intersect the folds indicate the positions of the carbon atoms from which the side chains extend. They go at right angles to the plane of the sheet.

Now let’s consider a certain number of similar sheets folded together; the density of their “packing” will depend on the size of the I-groups. Almost all webs have chains arranged in a similar way within the sheets, and differ only in the distance between the sheets: it ranges from 3.3 to 15.6 angstroms.

The web threads underneath are long, regular cylinders with an almost regular circular cross-section. One way to compare the fineness of fibers is to report the weight of a specific length of fiber. For spider webs, it is usually expressed in denier - the weight in grams of 9 kilometers of thread. In this measurement system, a silkworm thread weighs 1 denier, while a human hair weighs 40-50 denier. The weight of the spider cocoon thread is 0.7 denier, and the hanging thread is even less, 0.07 denier. A hanging thread wrapped around the globe at the equator would weigh only about 340 grams.

The strength and elongation of threads are important for the textile industry. To compare threads of different thicknesses, their strength is usually expressed in terms of tensile strength, that is, breaking load divided by denier. Tensile strength is thus expressed in grams per denier. The average tensile strength of cocoon threads is 2.2 g/denier, and that of hanging threads is 7.8 g/denier. The elongation at the moment of rupture reaches 46% and 31%, respectively.

Unlike the hanging thread, the cocoon thread is relatively weak, and this is explained by its purpose. It should not withstand great stress; its task is to create a protective shell for the cocoon eggs. To do this, the spider weaves a six-layer yarn from a curly thread. Each thread of the cocoon consists of six webs. This arachnoid is reminiscent of the bulky yarn that has been developed in recent years to make elastic knitwear from man-made fibers.

The spiral thread of the trapping net, which forms the sticky web trap, is very elastic. Its expansion and compression are completely reversible, and in this respect it resembles rubber.

One of the challenges of the artificial materials industry is to provide customers with materials with specific properties. Underwear fabric, for example, must retain heat and absorb moisture, while tire cords require very durable fabric.

The development of artificial protein fibers is still in its infancy, since we cannot yet create long chains with complex amino acid structures. It is possible, however, to take one amino acid and polymerize it into long chains, such as polyalanine or poly-methyl glutamate, to produce good tissues. It is also possible to obtain high molecular weight polymers with a repeating dipeptide sequence, for example ... glycine - alanine - glycine - alanine - glycine-alanine ...

Further study of various types of spider webs is the path that will certainly help us in creating artificial protein fibers.

P.S. What else are British scientists talking about: that in the future, based on a more detailed, molecular study of both spider thread and other natural materials, scientists will be able to obtain various ultra-useful things for our everyday life, for example, ultra-strong
reinforced concrete products made from special polymers or something like that.

Spiders belong to the oldest inhabitants of the Earth: traces of the first arachnids were found in rocks that are 340–450 million years old. Spiders are about 200–300 million years older than dinosaurs and more than 400 million years older than the first mammals. Nature has had enough time to not only increase the number of spider species (about 60 thousand are known), but also to equip many of these eight-legged predators with an amazing means of hunting - a web.

The pattern of the web can be different not only among different species, but also among one spider in the presence of certain chemicals, such as explosives or narcotics. Spiders were even going to be launched into space to study the effect of microgravity on the web pattern.

However, the substance that makes up the web hid the most mysteries.

The web, like our hair, animal fur, and silkworm threads, consists mainly of proteins. But the polypeptide chains in each spider thread are intertwined in such an unusual way that they have acquired almost record strength. A single thread produced by a spider is as strong as a steel wire of equal diameter. A rope woven from a web, only about the thickness of a pencil, could hold a bulldozer, a tank, and even such a powerful airbus as a Boeing 747 in place. But the density of steel is six times greater than that of spider webs.

It is known how high the strength of silk threads is. A classic example is an observation made by an Arizona doctor back in 1881. In front of this doctor, a shootout took place in which one of the shooters was killed. Two bullets hit the chest and went right through. At the same time, pieces of a silk handkerchief stuck out from the back of each wound. The bullets passed through clothing, muscles and bones, but were unable to tear the silk that got in their way.

Glycoprotein fibers, the diameter of which can be only a few nanometers, can be located parallel to the axis of the fibroin thread or form spirals around the thread. Glycoproteins - complex proteins that contain carbohydrates and have a molecular weight from 15,000 to 1,000,000 amu - are present not only in spiders, but also in all tissues of animals, plants and microorganisms (some proteins in blood plasma, muscle tissues, cell membranes, etc.).

During the formation of a web, glycoprotein fibers are connected to each other due to hydrogen bonds, as well as bonds between CO and NH groups, and a significant proportion of bonds are formed in the arachnoid glands of arachnids. Glycoprotein molecules can form liquid crystals with rod-shaped fragments that stack parallel to each other, giving the structure the strength of a solid while maintaining the ability to flow like a liquid.

The main components of the web are the simplest amino acids: glycine H 2 NCH 2 COOH and alanine CH 3 CHNH 2 COOH. The web also contains inorganic substances - potassium hydrogen phosphate and potassium nitrate. Their functions are reduced to protecting the web from fungi and bacteria and, probably, creating conditions for the formation of the thread itself in the glands.

A distinctive feature of the web is its environmental friendliness. It consists of substances that are easily absorbed by the natural environment and does not harm this environment. In this regard, the web has no analogues created by human hands.

A spider can produce up to seven threads of different structure and properties: some for catching “nets”, others for its own movement, others for signaling, etc. Almost all of these threads could find wide application in industry and everyday life, if It would be possible to establish their widespread production. However, it is hardly possible to “tame” spiders, like silkworms, or to organize unique spider farms: the aggressive habits of spiders and the individual-farming traits in their character are unlikely to allow this to be done. And to produce just 1 m of web fabric, the “work” of more than 400 spiders is required.

Is it possible to reproduce the chemical processes that take place in the body of spiders and copy natural material? Scientists and engineers have long ago developed the technology of Kevlar - aramid fiber:

produced on an industrial scale and approaching the properties of spider webs. Kevlar fibers are five times weaker than spider webs, but are still so strong that they are used to make lightweight bulletproof vests, hard hats, gloves, ropes, etc. But Kevlar is produced in hot sulfuric acid solutions, while spiders require regular temperature. Chemists do not yet know how to approach such conditions.

However, biochemists have come closer to solving the materials science problem. First, spider genes were identified and deciphered, programming the formation of threads of one or another structure. Today this applies to 14 species of spiders. Then American specialists from several research centers (each group independently) introduced these genes into bacteria, trying to obtain the necessary proteins in solution.

Scientists at the Canadian biotechnology company Nexia introduced such genes into mice, then switched to goats, and the goats began to produce milk with the same protein that forms the thread of the web. In the summer of 1999, two African pygmy bucks, Peter and Webster, were genetically programmed to produce goats whose milk contained this protein. This breed is good because the offspring become adults at the age of three months. The company is still silent on how to make threads from milk, but has already registered the name of the new material it created - “BioSteel”. An article on the properties of “biosteel” was published in the journal “Science” (“Science”, 2002, vol. 295, p. 427).

German specialists from Gatersleben took a different path: they introduced spider-like genes into plants - potatoes and tobacco. They managed to obtain up to 2% soluble proteins in potato tubers and tobacco leaves, consisting mainly of spidroin (the main fibroin of spiders). It is expected that when the quantities of spidroin produced become significant, it will first be used to make medical bandages.

Milk obtained from genetically modified goats can hardly be distinguished by taste from natural milk. Genetically modified potatoes are similar to regular ones: in principle, they can also be boiled and fried.