Quantum Tunnnelling In Olfaction
Your nose can smell quantum differences. 1
The human nose can detect over one trillion distinct odors. Our genome is pretty amazing, but not amazing enough to produce one trillion separate smell-detecting receptor proteins. So how do we delight in the scent of daisies and gag at the stench of that yogurt we forgot we were eating when we started writing this article a day ago? It’s suggested that the receptors in our nose can sense differences between slight quantum alterations in molecules, such a molecule that contains a hydrogen atom versus the same molecule containing a deuterium atom (just a hydrogen atom with a neutron).
The sense of smell of animals, including ourselves, is remarkable. A bear can smell a carcass 20 kilometres away. A moth can detect a mate from six to seven miles away; rats smell in stereo and snakes smell with their tongues. Many other animals use their sense of smell to migrate. For example, every year, along ocean coasts around the world, millions of salmon assemble into large schools at the mouths of rivers before venturing inland to battle against the flow of current, rapids, waterfalls and sand banks to follow a scent that takes them back to their spawning ground.
All of these olfactory skills are essential for animals that must find food, mates or avoid predators; so they utilise volatile cues that betray the proximity of these resources or dangers, whether in air or water. But how does this extraordinary sense work?
The conventional theory of olfaction is that odour molecules are detected by odour receptors via a kind of lock (the odour receptor) and key (the smelly molecule) mechanism inside our nose. However the theory fails to account adequately for certain observations, such as that very similarly shaped molecules often smell very differently; and vice versa. An alternative theory has molecular vibrations rather than shape providing the lock and key. This received a quantum twist in 1996 when biophysicist Luca Turin proposed that vibrations promote quantum tunnelling of electrons to open the olfactory lock. Turin proposed that when odour molecules are captured by olfactory receptors their bonds vibrations promote a quantum tunnelling event in the receptor molecule that, eventually, sends a signal to the brain.
The theory received a boost when it was recently found that fruit flies can distinguish odorants with exactly the same shape but made of different isotopes of the same elements, something that is hard to explain without quantum mechanics.
Sex pheromones 5
Pheromone-biosynthetic fatty acid desaturases, enzymes that introduce double bonds at specific positions and configurations into fatty acyl pheromone precursors of various chain lengths, contribute significantly to the number of possible pheromone structures. To maintain an efficient chemical communication, the signal receiver must stay tuned to the signal producer: This means that the pheromone composition and the pheromone preference should be inter-coordinated and therefore not undergo any changes. Since traits underlying pheromone production and the underlying preference for particular pheromone are probably not genetically linked to each other
The question is how this inter-coordination was achieved. If it were not functional right from the beginning, the male could not recognize the female, and the species would die.
Bombykol receptors in the silkworm moth and the fruit fly 3
Male moths are endowed with odorant receptors (ORs) to detect species-specific sex pheromones with remarkable sensitivity and selectivity. The silkmoth, Bombyx mori, utilizes the simplest possible pheromone system, in which a single pheromone component 4 Like many animal species, moths use chemical signals called sex pheromones to communicate with conspecific individuals of the opposite sex in the context of reproduction. Typically, male moths depend on sex pheromones emitted by conspecific females to identify and locate their mates. Therefore, the behavioral preference of male moths to conspecific pheromones is a critical factor for successful reproduction. Sex pheromone receptor proteins expressed in specialized antennal olfactory receptor neurons reportedly play a central role in sex pheromone discrimination.Our results show that the initiation of a complex programmed sexual behavior can depend on the properties of a single pheromone receptor gene expressed in a population of olfactory receptor neurons.the sex pheromone communication systems in moths is proposed to play an important role in reproductive isolation and speciation
Elephants communicate seismically 2
With their great, big ears, it’s no surprise that elephants have an especially keen sense of hearing. What’s less expected is that some of their sonic communication goes not through the air but through the ground. Elephants can make very low-frequency vocalizations—too low for the human ear to catch—that vibrate through soil for miles. In one experiment, Stanford biologist Caitlin O’Connell-Rodwell transmitted recorded “danger” calls through the ground to a group of elephants, who immediately starting acting nervously. But they didn’t react to gibberish ground rumblings that she produced. The physical structure of an elephant’s foot, such as thick pads of fat inside, may help transmit those ground vibrations up to the ear.
Bumblebees sense the electric fields of flowers
For years scientists have known that a handful of aquatic creatures—including electric eels, platypuses, and sharks—can sense electric fields generated by the twitching nerves and muscles of their prey. But then came a more surprising discovery: Bumblebees also can use electric fields to find food: The bees usually carry a positive charge, and they can pick up on the slightly negative natural charge of most flowers. (The opposite potentials also help pollen stick to the insects.) The bees even seem to distinguish between the differently shaped electric fields produced by various flowers. We humans can appreciate flowers for their beauty, but without a bee’s ultraviolet vision, keen smell, and electric sense, we can’t really experience flowers in their full glory.
Dung beetles orient themselves by the light of the Milky Way
Dung beetles do not have great vision. They cannot pick out individual stars or constellations in the night sky. But one particular species that lives in the South African grasslands can, even with its weak beetle eyes, see the bright stripe across the sky that is the Milky Way. According to an experimentreplicating these conditions in a planetarium, this dung beetle seems to use the Milky Way as a reference so it can roll fresh dung in a straight line. (Moving in a straight line without any visual cues is, in fact, pretty hard for any creature.) Animals senses are often remarkable because they exceed the boundaries of human perception, but sometimes, they just as remarkable for how limited they can be and still be perfectly suited to their purpose.
Birds navigate using magnetic fields
Birds routinely migrate over thousands of miles, maintaining their courses even on overcast days without the Sun or stars for guidance. Instead they rely on an internal magnetic compass. How exactly birds sense the earth’s magnetic field, however, is an enduring scientific mystery. Currently there are two main hypotheses. In the first, birds may use specialized cells in the ear or beak that contain a magnetic iron compound appropriately called magnetite. (The exact cells have, however, have never been identified in birds.) The second and more complicated hypothesis involves quantum mechanics. When light hits a protein called cryptochrome in a bird’s eye, it creates unpaired electrons that are sensitive to magnetic fields. And according to quantum mechanics, “entangled” electrons can interact to provide information on the magnetic field. Whether birds see, hear, or feel the magnetic field is still up for debate, but it’s clear that they do somehow sense it.
Snakes find their prey by sensing heat
A mouse can hide or stay quiet, but it cannot stop heat from radiating out of its furry little body. And unfortunately for warm-blooded mice, snakes have specialized organs just for detecting heat. Pitvipers, pythons, and boas have all independently evolved pit organs on each side of their faces. These organs contain cells that are exquisitely sensitive to heat, sensitive enough to detect the warmth of a small rodent one meter away. That’s how snakes can hunt so effectively at night. [url=http://public.wsu.edu/~kkardong/Web of KVK_06b/Publications/congenital_blind91.pdf]Even a blind snake without working eyes[/url] but with pit organs intact is about as good as a normal snake. (Visit “How Animals See the World” to get a great demonstration of snakes’ infrared vision.)