Chapter 9 say taste

Wherever we go, whatever we touch, we leave traces.One of the strange discoveries made by small children is that when two pebbles collide so suddenly, they give off a strange smoky smell.After washing the stones, the smell is light; after burning the stones in the furnace, the smell disappears.But when used to pick it up ready to hit again, the smell reappears. A smart dog with a sharp nose can follow a person by scent across an open field and distinguish that person's tracks from those of others.Not only that, but dogs could detect the faint scent of human fingerprints on a glass slide and remember the glass, sniffing it out from other slides for as long as six weeks before the smell disappeared. .In addition, the animal can sniff out the same scent of identical twins and cross-follow the tracks of the two as if they belonged to a single person.

The chemicals we leave behind in our shoe tracks mark ourselves as precisely and uniquely as the membrane surface antigen marks discernible in allografts of our tissues. Other animals are endowed with similar signaling mechanisms.Groups of ants can smell the difference between the same group and other ants as they crawl along the road.Ants hustle and bustle across the road, leaving trails, which can be followed by close ants, but not by other ants.Some ants are carnivorous ants, endowed with the ability to detect the tracks of ants they are accustomed to take as slaves, follow their victims to their nests, and release special odorous substances that panic the victim colony.

Catfish and catfish can identify each member of their species by their characteristic scent.It's hard to imagine a solitary, independent, existentialist bream that would be recognizable if singled out; a bream in a group behaves like interchangeable identical parts in an animal, but The individual still exists. Smell problems not only can distinguish this from non-this like immunology, but also have the confusion and confusion that exist in current immunology.It has been calculated that a single hare has approximately 100 million taste receptors.The cells of these receptors are constantly and surprisingly rapidly renewed, with new cells emerging from the basal cells within days.There are as many and complex theories trying to explain taste as there are theories of the immune response.It seems likely that the shape of the flavored molecule is most important.In general, odorants are chemically small, simple compounds.In the rose garden, the reason why a rose is a rose is determined by a 10-carbon atom compound called citronellol. It is the geometric shape of the atoms and the angle of the chemical bonds between the atoms that determine the unique smell.The specific vibrations of atoms or groups of atoms in the molecule of the odorant, or the vibrational music of the entire molecule, have been used as the basis for several theories that postulate the "osmium frequency" as the source of the odor.The geometry of a molecule seems to be more important than the names of the atoms themselves; any group of atoms arranged in exactly the same shape, no matter what the chemical name for the arrangement, will have a fragrance.It is not yet known how taste cells are activated by odorants.One idea is that a hole is poked in the receptor's membrane, causing the polarity change.But other workers think the substance might bind to cells that have special receptors for it, and then might just sit there, somehow signaling at a distance, like antigens do to immune cells.It has been proposed that there are special receptor proteins, and that different taste cells carry specialized receptors for different "basic" odors.But so far no one has managed to pinpoint those receptors or name those "basic" smells.

Training cells to taste seems to be an everyday phenomenon.Repeatedly sniffing small doses of the same odorant in an animal resulted in a dramatic increase in olfactory sensitivity, suggesting that new receptor sites may have been added to the cells.Conceivably, new cell clones with specific receptors are stimulated to emerge during training.The well-known pulse mouse in immunology can sense a very small amount of nitrobenzene with its nose after training, without the help of Freund's adjuvant or hapten carrier.The carnos were trained to detect carbolic acid and to distinguish it from p-chlorophenol, which is only present in concentrations of 5 parts per billion.Eels were taught to sniff out two to three molecules of phenylethanol.Of course, eels and salmon must be born with the ability to remember the smell of the waters in which they were hatched in order to swim by scent in the ocean to spawn.Electrodes in the olfactory bulbs spark when the salmon's gustatory epithelium touches water flowing from its spawning grounds, while currents from other waters elicit no response.

Animals around us have all these wonderful sensory technologies.For that, we feel a little inferior, something we don't have.Sometimes, to counteract this sense of loss (or loss of feeling), we console ourselves that we have evolved to leave these primitive mechanisms behind.We like to think of the olfactory bulbs as some kind of archaeological discovery, and it takes a bit of a penchant to refer to the ancient olfactory areas of the human brain as if they were some elderly, deranged relative. However, our actual situation may be better than we imagined.Ordinary people can detect a few molecules of butyl mercaptan, and most people can feel a little bit of musk.Steroids are strangely aromatic, and they give off a variety of musky, sensual scents.Women are acutely aware of the smell of a synthetic steroid called cyclopentadecanolide, but most men are not.Everyone can smell ants, and the big word pismire (ant) was originally coined for this smell (pis = piss: pee, mire: ant).

There may also be odorants that excite receptors in our olfactory epithelium without us being aware of the smell, including information that is exchanged involuntarily between people.Wiener (H.) intuitively suggested that the flaws and misinterpretations of this odor communication system might still be an unexplored area of ​​psychiatry.He proposes that people with schizophrenia may have problems with identity and reality due to deficits in perceiving signals from themselves or others.Indeed, some apparatus may be faulty in schizophrenics; their sweat is said to have an unfamiliar odor recently identified as trans-3-methylhexanoic acid.

Olfactory receptors, which are used for communication between different animals, are crucial for establishing symbiotic systems.Crabs and sea anemones recognize each other as partners by molecular configuration, as do sea anemones and their symbiotic nymphs.Similar devices are also used for self-defense, such as the limpet, which defends against carnivorous starfish by eversioning its mantle so that the starfish loses a foothold; limpets sense a particular starfish protein.To be fair, all starfish make this protein and release it into their environment.This system is clearly ancient, long before the immunosensing of antibodies on which we now rely so heavily to recognize each other.It has recently been known that there is a close link between those genes that mark the self with cellular antigens and those that initiate an immune response through antibody formation.It is possible that the creation of antibodies arises from the early sensory mechanisms required for symbiosis, which may in part be used to avoid uncontrolled symbiotic activity.

The very common system of chemical communication between all living things, whether plants or animals, is called "allelochemistry" (different interspecies chemistry) by Whittaker (RH).Every life form uses signals of one kind or another to announce its proximity to other creatures around it, to draw boundaries to intruders, or to signal welcome to potential symbionts.The overall effect is to form a coordinated mechanism that regulates growth rate and territorial occupation.This is apparently used to make the Earth self-balancing. Jorge Luis Borges (Jorge Luis Borges, 1899~, Argentina) mentioned in his new collection of bestiaries about mythical animals that many thoughtful people have imagined spherical animals, and Cape Johannes Kepler once believed that the earth itself is such a being.In such a gigantic organism, chemical signals may act as overall endogenous hormones, maintaining balance and symmetry in the operation of the various interconnected working parts, through an endless long-distance relay of interconnected messages between all other species , the organization that informed the conditions of the eels in the Sargasso Sea to the plants in the Alps.

If individual computers could be made large enough to hold nearby galaxies, they could be used to solve this interesting problem.It's pleasant to think that there are so many unsolved mysteries that biology still has to solve, though it's not clear we'll ever find enough graduate students to study them.