Salamanders and Remembering Scents

Scents are one of the strongest memories a person has but up to now no one could understand exactly how these memories could last more than the sixty days. Every olfactory neuron in the epithelium survives for only 60 days after which it is replaced by a new cell. Generally, when neurons die there is nothing to take its place yet when olfactory neurons die new neurons take their place. These new olfactory neurons are produced by a layer of stem cells directly beneath the old olfactory neurons.

The question still exists though, if these neurons are dying how could we possibly keep that link in our minds which is related to smell? Now we finally know; “Memories survive because the axons of neurons that express the same receptor always go to the same place."

From here many researchers are trying to figure out what happens to the smells after they make their way to the olfactory hub or the olfactory corves. How are these smells processed there? Many researchers believe that this question can be answered with the aid of salamanders. This animal would be the easiest to dissect since its nasal cavity is a “flattened sac”. Salamanders would make it possible to analyze the entire olfactory system. Scientists believe that this recording will be a huge breakthrough and will once and fore all know exactly how those smells are remembered

What is Aromatherapy and Why is it Useless

Aromatherapy is a term that was created by the French chemist Rene Maurice Gatterfosse in order to describe the process of using oils in healing. Opposed to popular belief though, the aromas of these oils are not used in the actual therapy. Rather, the chemical compositions of these oils are used. Vapors are also commonly used in this form of therapy.

While the logic seems completely apt, it seems as though suspicion is the only evidence for this practice to actually work. Many aromatherapists claim that the therapy slowly changes the body to perform better but opinion is all that they can back this up with. Overall, aromatherapy has absolutely no proof of being therapeutic aside from the assertions made by aromatherapists and testimonials given by customers of these treatments.

Pheromone Research Wins Eppendorf/Science Prize

Dr. Pingxi Xu has won the 2005 International Prize in Neurobiology, sponsored by the journal Science and Eppendorf. He received the award for his study in how fruit flies use pheromones to influence the behavior of other fruit flies. His major contribution was the discovery of "odorant binding proteins", which appear to act as adaptors that link pheromone molecules to neurons. Fruit flies may use pheromones for more than just attracting a partner, in fact it seems that the males use pheromones to establish dominance over one another and influence other flies' behavior. Learning how to control the odorant binding proteins could mean manipulating the fruit flies' perception of various pheromones, and thus influencing their behavior as desired. In other words, we would be able to control insects’ behavior using harmless chemical sprays in minute quantities, as opposed to large amounts of toxic pesticides.

For his research, Dr. Xu has the chance to win the grand prize, which includes a $25,000 grant from Eppendorf to continue his research, and a chance to publish his work in the journal Science.

A Mouse's Nose is the Key to Mating

Harvard Universtiy researches have made a surprise discovery that contradicts the general scientific consensus on the matter of how mice detect pheromones. The standing belief was that pheromones were detected by the vomeronasal organ, not by the nose, which detected all other oders. This finding helps explain how humans detect pheromones, which was a subject of debate because humans lack the vomeronasal organ system which was believed to be necessary for pheromone detection.

Biologist Catherine Dulac of Harvard and her team made their discovery using a flourescently-marked benine virus injected into the nervous systems of mice. The virus was used because it travels in the opposite direction of the neurons. The virus was injected into the "mating center" in the brain and tracked as it traveled backward through the nervous system. Dulac and her colleagues expected the virus to end up at the vomeronasal organ, but instead discovered that it wound up in the nose of the mouse. This means that the signals reaching the "mating center" of the brain originate in the nose, not the vomeronasal organ, suggesting that the nose is in fact responsible for pheromone detection.

This discovery directly contradicts the information published in most biology textbooks today. Dulac and her team believe that the nose is the primary organ in detecting pheromones, but that the vomeronasal organ is not completely useless. They believe it may have something to do with differentiating the gender of the pheromones.

Dying Beetles Make a Last-Ditch Effort to Reproduce

Biologist Ben Sadd from the Swiss Federal Institute of Technology recently made an interesting discovery about mealworm beetles along with his colleagues. Sadd discovered that when the male beetles' immune systems become so stressed that death seems likely, the beetles step up their production of pheromones. Apparently, the beetles are making a last-ditch effort at attracting a female partner for reproduction before it's too late for them.

Sadd made the discovery by conducting an experiment with 20 virgin male beetles. Each beetle was placed on a sheet of filter paper. The control group was left alone, while the experimental group was made "sick" when Sadd introduced a piece of nylon to their bodies. Sadd then took note of which sheets seemed to be more attractive to female beetles. Just as he expected, the females spent much more time on the filter papers from the dying beetles than those of the healthy beetles. This seems to support Sadd's hypothesis that dying beetles produce more sex pheromones than normal, healthy ones.

Cancer-Causing Pheromones

Microbiologist Steve Winans of Cornell University has discovered cancerous bacteria that use pheromones to find their victims. The bacteria are found in soil and home in on pheromones released from plants' wounds. A wounded plant is more susceptible to infection, so naturally bacteria would be better off attacking a wounded plant. Unfortunately for several types of fruit plants and grape vines, one variety of bacteria has the ability to detect the pheromones released by a plant's wound. The particular bacteria, Agrobacterium tumefaciens, cause a type of cancer known as crown gall. Crown gall exacts a costly economic toll on fruit crops each year. As of now, there is no known way of controlling the crown gall infection, there are no pesticides or other chemicals known to combat the cancerous pathogens. Mr. Winans' recognition of the unique ability of the bacteria to detect pheromones is a big step towards finding a pesticide for crown gall. One possible remedy might be the introduction of a chemical that masks the pheromone released from the plants' wounds. This chemical could be sprayed on the plants like a pesticide and would greatly reduce the effectiveness of the bacteria.

Song Inducing Pheromones?

Two researchers at Washington University in St. Louis recently made an interesting discovery about the effect of female mouse pheromones on male mice. It seems that female pheromones stimulate the males to "burst into song". After exposing the male mice to the pheromones of females, the researchers made recordings of the mice and then dropped the pitch to a level audible to the human ear. The vocalizations of the mice sounded quite similar to bird songs, and are believed to be a response to the apparent presence of a potential mate. Since pheromones are linked to sex, the songs are most likely linked to sex as well. The next step for the researchers is to begin analyzing and comparing the songs of mice, to deteremine if the songs of wild mice and laboratory mice differ and so on. It has already been found that the songs of the 45 mice tested appear similar, yet each have their own distinctions, meaning the song may contain information about the mouse singing it. Further study is necessary before drawing any firm conclusions, but it does appear that the songs are indeed a response to female pheromones, and are intended to attract the interest of a potential mate.

Pheromones for Pest Control

Scientists in the Great Lakes region of the U.S. have devised a plan to control the population of sea lamprey in the region's streams. The parasitic lamprey are negatively impacting the area's economy by killing commerically valuable species of fish. The current method of controlling the sea lamprey is through the use of a poison that also negatively impacts other species in the surrounding environment and is quite costly. But scientists believe they have found the lampreys' Achilles' heel. Each year, the lamprey follow pheromone trails from the opposite sex into the streams of the Great Lakes to mate. The Great Lakes Fishery Commission (GLFC) plans to use the pheromones they have successfully isolated to attract the lamprey to traps, and then sterilize the males.

Lamprey have some of the most potent pheromones researchers have ever encountered. Just 1 single gram of pheromone in 10 billion liters of water is detectably by lamprey. The GLFC scientists isolated the pheromone from 8,000 liters of water that contained 35,000 larvae. Less than 1 milligram was extracted from this sample.

Characteristic Scents

Scents being used as a means for sexual attraction are not new findings which is why research by popular companies have been conducted excessively to find the perfect scents for their fragrances. Fragrances are created around a “note”, or a scent that stands out while around other scents. Companies have gone far enough to create characteristic type fragrances. For example, Enrique Iglesias uses the cologne, True Star Men by Tommy Hilfiger, because he is someone who is easygoing and relaxed. This is presented through his cologne as well. Other companies are also making fragrances to target their popular buyers. Estee Lauder's Aramis uses a certain scent which is described by Ray Matts as, “It had to be something that you don't have to worry about having too much or not enough on. ... It had to be cozy and comfortable.” Many of the scents also have a connection to aphrodisiacs. Spices are the top sources for aphrodisiacs which are the common ingredients for the perfect fragrances.

Sexual Orientation and Pheromones

Pheromones have only been proven to be used by various animals; however, recent studies show they may also work in the sexual field for humans. If humans do respond to pheromones, two compounds most likely to cause the effect are a testosterone derivative called 4,16-androstadien-3-one (AND), and the estrogen-like steroid estra-1,3-5(10),16-tetraen-3-ol (EST). Older studies from Ivanka Savic and colleagues show that the hypothalamus region of the brain is triggered when men smell EST and women smell AND. The recent study expands on the previous study showing that the compound triggering the hypothalamus region is not necessarily gender based. They’re studies shows it has to do with a person’s sexual orientation. The experiment was conducted by giving homosexual men, heterosexual women, and heterosexual men the two compounds, EST and AND, as well as regular scents such as lavender. AND activated the hypothalamus region of the brain for homosexual men and heterosexual women, but not heterosexual men. The EST only activated the hypothalamus region for heterosexual men. All three groups experienced the same effect by the regular scents though. This proves the brain can differentiate between pheromones and regular scents. This also suggests that brain function is connected to sexual orientation.