Busy Little Thermostats

If you think all insects are just cold-blooded monsters, there’s one fuzzy little creature that will surprise you. Research has shown that bumblebees are actually warm-blooded, and, like us, experience temperature as an important aspect of their busy lives.

Research on a bumblebee colony of the Pacific Northwest demonstrated that temperature regulation of the hive is controlled by the activity of a specific group of bees. To incubate all those little babies in the nest, workers shiver their wings, pushing heat down to their abdomens held over the larvae. Hive too hot? Workers rapidly fan their wings. Since bees could die if the temperature is raised too high, researchers focused on documenting the incubation activity, varying the experimental temperature from 50 to 101 degrees Fahrenheit. They found that when they removed some of the workers, those that remained increased their rate of heat production, instead of calling on others to help them. This prompted the discovery of a size-dependent work assignment. Smaller bees were involved in temperature regulation, while larger bees were committed to gathering food. Although it is not known exactly how such division of labor originates, several mechanisms have been proposed, including genetics, hormones, and interactions with other bees.

How does temperature figure into the lives of the larger bees? A study on flowers accidentally produced the answer. Many flowers contain cone-shaped cells that interact with light in a manner that causes the surface of the flower to be darker, and therefore, warmer. While investigating these cells, researchers also allowed bumblebees to visit flowers of varying temperatures and colors, finding evidence that bumblebees can associate the colors of flowers with the warmth of their nectar.

The usual body temperature of a bumblebee is 100 degrees Fahrenheit. Just as we probably wouldn’t like to stuff ourselves full of freezing victuals, bees efficiently conserve energy by filling themselves with nectar that is already warm. And just as we like a house with a carefully regulated climate, bees have a care for their hive too.

You never thought you’d have something in common with an insect, did you?

Posted by J543 (2)

A cure for AIDS

Is there a cure for AIDS? I typed that question in Google trying to see what I would find. It is amazing how many articles I found, and how interesting they were. Supposedly in 2001 a cure for AIDS was found in South Africa. The news article states that an African medicinal plant Sutherlandia Frutescens could hold the key for treatment of people with AIDS and HIV. However the doctors who are using this plant precised that they did not guarantee that the plant would cure AIDS, but that the people who have Gambia taken it and having a very good diet have shown an improvement in their lives quality. Patients picked up weight, and live longer that they were suppose to. It says in the article that the medical research council was going to make some test. but it is been almost six years and obviously we haven't heard anything. Wonder what happen to the people who announced that they discovered that plant. They also said that this plant could cure cancer too and that ii has been proven many times.
I also saw on television this morning that the president of Gambia in Africa claimed on January 19 that he could cure AIDS. How far people are willing to go? I wish it could really be a cure somewhere. Everybody is looking for an answer for AIDS.
A doctor in Nigeria announced to the world in 2000 that he had a cure for aids. But what has he become? After my research I noticed that more that 80 percent of the AIDS’ cure claims came out of Africa. I am from Africa and it is funny how even when I was younger I heard a lot of stories like those, and it still continues. One funny story that I read was that some people, also in Africa believed that having sex with a Virgin would actually cure AIDS.
The amount of stories and claims that I found is ridiculous. People should be more reasonable and stop claiming false things. Even if one of those stories were right people would not believe because of the number of false stories that have been told.


Posted by LYRS

The Unrecognized Genius

Who has heard of Nikola Tesla, the inventor of the Alternating Current motor, the Tesla coil, the radio (it was not Marconi), neon and fluorescent illumination, x-rays, as well as a pioneer in the wireless transmission of energy? Was the name mentioned in our high school science classes, or in our general science college classes? Perhaps, we are familiar the SI unit of magnetic field, the tesla, the measurement of magnetic flux density, but do we know the scientist in whose honor the unit was termed? I have conversed with engineering majors who are not acquainted with the discoverer of the fundamental principles of physics. When we hear the name Thomas Edison pronounced, conversely, we associate it with one of America’s greatest scientists, the inventor of the lightbulb, phonograph and motion picture camera. Edison, an investor and businessman, was a proponent of the Direct Current motor. He saw a profit in store for his company with the growth of electrical power-utilizing industry, and seeing a rival in AC current he began the War of the Currents. Alternating Current won the race. It was found to be more efficient in energy usage and less costly. So why is Edison more famous than Tesla? Why is Marconi more famous? Tesla’s life may explain this riddle…

Nikola Tesla was born in Croatia in 1856. He was provided with a formal elementary education and enrolled in a polytechnic school for engineering and mathematics. As a student he devised the basic outline of Alternating Current through magnetic reversal. Afterwards, Tesla moved to America in search of an investor to realize his invention and was hired by Thomas Edison, the most renowned electrical engineer. Edison hired Tesla to work in his various laboratories and promised Tesla fifty thousand dollars for improvements in his Direct Current plants but when Tesla completed the undertaking Edison claimed that his offer was made in jest. Tesla left Edison’s plant embittered. Eventually, several investors enabled him to construct his major inventions, most importantly the AC motor. The motor provided a far more efficient electrical current than the established Direct Current motor.

Thomas Edison saw the future of Direct Current threatened and launched a public attack on alternating current using every possible means of damaging its reputation, to the extent of arranging the spectacle of public execution by electrocution.

The AC motor provides constant electrical generation and is used to power every household switch and electrical device in the United States. The basic design of this devise consists of two rings, placed one within the other. The outer ring is static, the stator and the inner ring rotates. Each ring has a set of magnets placed in a specific arrangement, which allows the north and south polarity to alternate. The anatomy of the AC motor consists of twelve sets of poles placed on twelve sets of stators. The reversal of the magnet polarity generates a current that does not need a physical power to generate rotation, in contrast to Direct Current motors.

During his years of production, Tesla was well-known and celebrated in America. He had the reputation of an eccentric and visionary. His popularity fell after important industrial investors turned to other routes for profit. Marconi used influential connections in Britain and America to override Tesla’s patents to be regarded as the sole inventor of the radio, and as a result, won the Nobel Prize. Tesla died at the age of 86, obscured and forgotten to the public’s ears, after living in an impoverished condition for many years. Still today, Tesla is by and large unknown. His inventions place him in the rank of the greatest American scientists. When we hear his name at least one of his inventions should pop up in our minds.

Source: http://www.pbs.org/tesla/

Posted by: Alberta Colakovic
Course Participant Bio 312

Will Gene Therapy Extend Lives?

At the age of 21, I have a lot on my mind. Something I don’t find myself thinking about too often is death and disease. Recent studies show that I should have a good 54 years or so left. That’s a decent chunk of time…but is it possible to stretch our lives longer than we already have?

According to the article “Reprogramming Biology”, we will eventually have the technology available to prolong our lives. The article makes the analogy that we will to improve our bodies like we improve our computers. Anytime we want to update a computer we can simply upload software. Soon, when our body needs an update, we will inject ourselves with healthy cells. For example, researchers are exploring the use of gene therapy as a treatment for pulmonary arterial hypertension, which causes deadly high blood pressure.

During gene therapy, a sample of damaged cells is taken from an organism and genetically modified to produce healthy cells. These cells are then placed in an environment where they reproduce. After they accumulate, the cells are injected into the host and return to their proper tissues. The possibilities of this therapy seem endless as stem cells can be taken from the body and theoretically turned into anything.

Trying to imagine these procedures as an every day occurrence is difficult. Aren’t the costs of genetic research and procedures astronomical? Not everyone seems to think so. This is what the author of "Reprogramming Biology", Ray Kurzweil, believes:

"Information technologies, including biological ones, double their price performance and capacity in less than a year. Sequencing DNA, for example, has come down in price by half annually, from $10 per base pair in 1990 to under a penny today.7 The amount of genetic data we have sequenced has more than doubled every year.This rate of doubling means that we will increase the capability of these technologies by a factor of 1,000 in less than a decade and by a billion in 25 years."

The concept of living longer is controversial. Can we live too long? If gene therapy becomes as popular as Kurweil believes, we will be facing a different problem as well - overpopulation. With overpopulation comes deficiency of resources. The results of extending our lives could be devastating to the world.

It seems possible that gene therapy will become a popular, affordable health treatment in my lifetime. We'll have to wait and see how this will affect life expectancy, but it seems like I might be here for awhile.

-APentowski

Naps Beneficial to the Heart

As a college student everyone knows of the stress of classes and pulling an all-nighter. Having done this myself, I know the need for a nap during the midday hours during a hectic week. Many times I find myself falling asleep on the couch or even in class just to get a couple of extra ZZZ’s . According to a study in the journal, Archives of Internal Medicine, taking a midday nap is beneficial to the heart. Naps help to the relieve stress, which can lead to many health problems. In the United States heart disease is the leading killer among males, and according to this study, taking a 30 minute nap when needed can alleviate this as the main killer among males.

From what I was told most of my life taking a nap less than 20 minutes was beneficial because one would wake up rejuvenated, and taking a nap any longer than that one would wake up groggy and more tired than before, but according to this new study, a nap of around a half hour alleviates the stress of everyday life, and can actually add years onto ones life.

After a six year study, 34 percent of men who took naps were less likely to die from heart disease than non-nappers which is a large number. I can related to this, as I’m sure a lot of people can because, according to the study 64 percent of working men who do take a midday nap have a lower risk of heart related death compared to working men who do not have a midday shuteye ritual. This is not saying that women do not have it as hard, but the study showed that only around six percent of women died from heart disease during the study so a complete analysis couldn’t be run on those numbers.
As an avid napper myself, I would recommend a 15-30 minute nap a day. A lot of times, especially during finals weeks, I feel like I don’t have the time to nap, but according to this study, it could end up saving you as stress is relieved and ones mind will probably be clearer after a quick shut eye.



Posted by - Sully

Trapping Cells

Insects and pests can be a huge problem for farmers and their crops. One technique farmers use to deal with them is by planting a separate group of crops, called trap crops. These trap crops are not harvested and are mainly used to attract insects and other pests. By doing this, farmers will know which group of crops needs to sprayed with pesticides. Now some scientists are applying this technique to eliminate viruses.

Viruses cannot reproduce by themselves. Instead, they reproduce by attaching onto another cell and releasing their own genetic material into the infected cell. They infected cell will then start producing new copies of the virus. Eventually, the new copies will break open the cell and begin infecting other cells.

According to this study, scientists have used trap cells to slow and sometimes eliminate the growth of viruses within a system. These cells are created with special properties that make it so that they cannot be used by viruses to reproduce. For example, some of the trap cells contains no binding sites for the virus, making it resistant to infection. This makes it difficult for a virus to find a normal cell to infect, slowing down the rate at which the virus can replicate. In the experiment, researchers tested the trap cells against bacteriophage. They discovered that if half of the cells in the system were trap cells, then the bactriophage will eventually go extinct.

Paul Turner, PhD believes that in the future, the trap cells can be used to combat viruses like HIV. HIV is able to recognize T-cells because of the CD4 molecule on its surface. Turner says that a new way to fight HIV could be to create red blood cells that have the CD4 molecule. HIV will now target the red blood cell because of the CD4, but since the red blood cells have no nucleus, HIV will not be able to use it to reproduce.


yz

Spear Wielding Chimps Hunt for Dinner!

We tend to think of the stereotypical Chimpanzee as an active, zany creature who eats bananas and kind of hangs out with other chimpanzees; well it seems nothing could be further from the truth. Researchers at the University of Iowa have documented numerous observations of chimpanzees fashioning spears from tree branches and using them to hunt prey called lesser bush babies. Dr. Jill D. Pruetz of Iowa State University in Ames, Iowa was head of the research team that documented 22 separate instances where the chimpanzees in the study used makeshift spears to capture smaller primates for eating.[1](www.current-biology.com) Members of a chimpanzee population at a habitat in Senegal were closely studied by field observers as they repeatedly went through a five step routine to spear prey. Amazed researchers watched as the chimpanzees went through a routine of preparation once a potential nest was located. Hunters were seen choosing branches of sufficient length and weight that could be pushed into a nest to immobilize prey, breaking these branches off of the tree, then stripping the leaves and side branches before trimming the end (in some cases they trimmed both ends) and using their teeth to sharpen the end to a point.
Apparently they were not just using tools to procure their prey, Dr. Pruetz' team also observed them sniffing and licking the points of their spears after pushing them into nests, thus adding a sensory dimension to the process. According to Dr. Pruetz, "almost without fail, every time they would withdraw the tool, they would sniff it or lick it, and then proceed to stab it in there again." All of this sniffing and licking had a purpose; it let the tool wielding apes know if their hunting implement had hit the mark.
Dr. Pruetz commenting on the deliberateness of these actions was astounded by the connection remarking,"… they did it so forcibly that our assumption is the bush babies would have been injured if there were bush babies in the hollow." What does this mean in the greater scheme of things? Well quite a lot actually.
During all of the 22 observed instances the chimpanzee hunters were immature males and adult females. Observing this particular segment of the population doing the hunting for live prey is stunning news to the scientific community. It lays the groundwork for further study of the historical role of females in the use of tools to acquire prey and how this skill may have impacted human evolution. This research took place is an open savannah; an environment similar to what evolutionary biologists think may have supported the earliest humans of our species. Dr. Pruetz, an anthropologist, sees chimpanzees as a not-so-distant cousin to modern humans. "Looking at our closest living relatives in a habitat that is fairly similar to what we see characterizing early hominids six million years ago can help researchers understand early human ancestors' behavior and ecology," she said. [2](www.anthr.iastate.edu/pruetz.shtml)
As with any observed phenomenon in animal behavior that can only be described as ground breaking, there is a mini-controversy over the use of the word 'spear'. Since the chimps are wielding the spear and not actual throwing it at prey, Craig Stanford, a primatologist at USC, prefers the term "bludgeoner".
[3](www.usc.edu/dept/elab/anth/FacultyPages/stanford.html) Whatever one chooses to call the teeth-sharpened tree branch used to procure a previously alive meal, the fact remains that apes do in fact use tools to hunt. Now if they could only learn to shoot back at the poachers who invade their protected habitat…that would be a true achievement!
I have posted a link [4](www.youtube.com/watch?v=NivAusARwd8) to a youtube video where chimps use tools to crack nuts. This opens up legitimate questions of 'learning'...do the younger ones learn by the example of the older chimps?...I will continue to check for other data relevant to questions raised in comments.




[1]Current Biology : http://www.current-biology.com/
[2]Jill Pruetz: www.anthr.iastate.edu/pruetz.shtml
[3]Craig Stanford : http://www.usc.edu/dept/elab/anth/faculty/stanford.html
[4]http://www.youtube.com/watch?v=NivAusARwd8


Posted by : Catherine Stubbington
Course Participant Bio 312

Caffeine and Heart Disease

If you’re anything like me, you drink a lot of caffeinated drinks. In the U.S., approximately 85% of adults drink a caffeinated beverage in the form of coffee, tea, and sodas. The daily average of cups of coffee per drinker is 3.3 and 64% of all coffee is consumed at breakfast.(Lane, Psychosomatic Medicine.) Researchers have debated the correlation between caffeine and heart disease, as experiments have come up with conflicting results.

During a two day study, James D. Lane studied the affects of caffeine on the blood pressure in 47 daily coffee drinkers. On the first day, half of the participants were given caffeine capsules and the other half were given a placebo. The next day, this was reversed. The group who had the caffeine capsules was given the placebo and those who had the placebo first were given the caffeine capsules. Using a portable monitor, the participant’s blood pressure and heart rates were measured throughout the two days. Stress hormones levels were monitored from urine samples. When the results from both days were compared, he found that blood pressure was consistently higher on caffeine days. Blood pressure was on average 4mm higher for systolic and 3mm for diastolic on caffeine days. The stress hormone levels were also higher by 32%. (Lane) This clearly shows that caffeine is not good for your heart.

However, another study showed that consuming caffeine regularly may provide protection against heart disease in the elderly whose blood pressure is normal. The idea is that caffeine will boost blood pressure too counteract the drop in pressure after eating a meal, something that occurs more as people age. Of the 6,594 adults participating in the study, 426 died of heart disease in a 9 year period. Researchers found that adults 65 and older who consumed more caffeine had a lower risk of death from heart disease. However, this effect was not seen in people younger than 65.

It appears that consuming large amounts of caffeine will only be helpful to you when you’re older. Heart disease is one of top causes of death in this country. Taking measures to maintain a healthy blood pressure is the key to preventing the risk of disease. Clearly, this will be no easy task; given the amount of coffee (as well as other drinks such as sodas) Americans drink daily.

-Posted by WildThing

The Regeneration of a Newt

When humans lose a leg, their leg never regenerates. On the other hand, newts have the ability to regenerate a lost limb. Although humans and the other higher animals lack the ability, the capability of lower animals to regenerate is excellent. Newts have an especially excellent ability for regeneration; they can even repair their heart. Scientists at the Max Planck Institute for Heart and Lung Research in Bad Nauheim found the molecular mechanism of newt heart regeneration.

Notophthalmus viridescens , a newt found in North America swamps was the subjecti of this study. This newt's heart muscle cells have some particular characteristics. First, after a newt gets a wound in its heart, the heart muscle cells can lose properties they originally had. In this process, proteins of heart muscle cells are rapidly controlled and the cells start cell division in order to create new heart muscle. Then, two weeks later, the heart muscle cells are completely repaired. Second, the heart muscle cells of a newt have a protein, phosphorylated histone H3, and the newt can regrow the heart without relying on stem cells. In addition, the researchers concluded that a newt might not need a blastema, which is a mass of undifferentiated cells capable of regeneration. Third, the researchers showed that the process of regenerating a leg and the process of regenerating a heart were different. In the process of regenerating a leg, a newt needs a blastema. This is because blastema cells have specific chracteristics in common with stem cells. When heart muscle cells are injected into the leg of a newt which is regenerating, the cells lose their characteristic properties. On the other hand, when they are injected into an undamaged leg, they do not dedifferentiate. From these results, the researchers got the idea that particular enzymes operated the cells for regeneration.

Thus, a newt has excellent plasticity of the heart cells when the heart gets damage. Humans do not have the same powers of regeneration that a newt does, but further study of a newt may reveal a way to regenerate damaged or lost tissue and organs.

posted by tsaori

Our dentist knows for sure, or does he/she?

At some point in life we all end up in the dentist’s office. Many of us made the bulk of our dental visits during our childhood years. As children sitting in the dental chair we were often told the actual cause for cavities and tooth problems were poor nutritional choices, with the culprit most often being identified as sweets. I vividly remember one particular visit to the dentist as the most embarrassing. Emerging from his office my pre-molar teeth were all black. I was mortified of course, but the dentist insisted it was the only way to prevent further damage. However, as I later learned, the truth was not that my teeth were being damaged by sweets, but by a lack of fluoridation in the water system that supplied water to the area where we lived.

But patients should be aware that cavities can occur even with regularly scheduled dental care, and dentists are not always able to help them avoid poor oral care. A recent study in the United Kingdom showed that even the teeth of children who frequently went to the dentist fell prey to the oral bacteria that cause cavities. A research team interviewed over one hundred dentists from four different areas of the UK and found, to their surprise, that the advice dentists give to patients varies, which could be a possible cause for the overall decline in oral health.

While 50% of the dentists surveyed advised their patients to abstain from sugary foods and drinks and to brush their teeth on a regular basis, they failed to suggest alternatives such as adding fluoridation to a daily regimen of oral health care. Curiously, the mere mention of fluoridation can spark a debate among dental professionals. Some dentists believe that the use of fluoride is detrimental to humans, and they harbor personal objections regarding “mass fluoridation.” Interestingly enough, the people who are in the best position to impact oral health do not seem to know enough to be able to educate their own patients. So they continue to tell patients young and old to stay away from candy and brush their teeth everyday. The next time you find yourself sitting in the chair with the bright light in your eyes, and someone is digging around in your mouth with a dental instrument, ask them what they think about fluoride and see what kind of response you get.



Posted by Mike

Worldwide Decline in Shark Attacks

Ever since I saw the movie JAWS, I have been a little nervous every time I jump into the water each year. If you feel the same way as me, this article may calm your nerves a little bit. Thanks to some University of Florida research you will be happy to know that shark attacks worldwide have barely risen and are on a downward trend. In 2005 there were 61 attacks and that number has gone up only one. In 2006 there were 62 attacks and only 4 of those were fatalities. This is a great improvement in comparison to the statistics of 2000. In that one year alone there were 79 attacks, 11 of which were deadly.

Scientists are having trouble explaining the overall decline in the attacks. Some attribute this lull in shark attacks to the fact that there is a decrease in the population of sharks located near the shore due to overfishing. Another cause could be changes in weather patterns or variations in the proximity of currents to the shoreline. Also there has been a lot more water safety precautions taken globally and swimmers are more cautious about where they are swimming. Of those attacked in 2006, surfers were the most prevalent and swimmers were a close second. Snorkelers and divers were at a distant third with only 5 attacked.

Of the four fatalities that occurred in 2006, none happened in the United States. In 2005 there were 40 U.S. attacks and that dropped slightly to 38 this past year. Florida still remains the world’s shark attack capital, but the number of attacks has lowered there as well. George Burgess, director of the International Shark Attack File at the University of Florida seemed to be happy with the results of this year’s census. He said, “It's really quite remarkable when you have only four people a year die in the mouth of a shark. The reality is, as a biologist, this is a non-problem. It's a minor, minor thing."

The four fatalities this year occurred in Australia, Brazil, Reunion Island, and the South Pacific island Tonga. The Australian attack was a woman swimming off the coast with her dog. According to Burgess, the attack may have been provoked by bloody fish parts being thrown into the water by fisherman. In Brazil, a man was fatally attacked swimming off of the northeast coast. The death on Reunion Island happened to a man who was surfing in waters that are forbidden for swimming. In Tonga a young woman from the American Peace Corps was attacked while swimming.

Let’s hope that the trend of violent interaction between sharks and humans stays on a downward spiral. Remember the next time you enter the water at the beach, that you are not in a swimming pool in your backyard, but in fact you are in another environment. An environment where sharks and tons of other aquatic life are living and interacting with one another. Also if there is warning in area to not swim, don’t try and swim there.

Chimpanzees and their attention getting noises

Chimpanzees are our closest living relative. They, like us, have close family bonds and are known to be very intelligent. Chimpanzees use facial expressions, vocalizations, and body language to communicate with members in their group. Scientists identified over 32 different call types. Some of these are food calls while others include calls to get the attention of the humans around them. The types of calls of captive and wild chimpanzees differ. For example chimpanzees raised in captivity have specific calls for when there is a human and a food source near by so that they can get the attention of the human and get the food.

In 2005 there was a study done to test the idea that chimpanzees have context specific vocalizations. Others studies also showed that chimpanzees produce manual gestures on purpose. In these situations the chimpanzee only made the gesture when the humans were facing them. The main aim of this study was to see under what conditions a chimpanzee would make a “raspberry,” and extended grunts which were found to be the two main attention getting expressions. Three main conditions were tested: 1) when a human alone (HA) was placed in front of the cage; 2) when food alone was placed in front of the cage (FA); 3) and when a human and food were placed in front of the cage, with the human in close proximity to the food (HF). For food the chimpanzees were given bananas. The human experimenter had worked frequently with all of the chimpanzees and provided the food over the course of 15 years. The researchers hypothesized that the chimpanzees would use attention getting noises to get the attention of humans. This would mean that the combination of people and food in the presence of the chimpanzee would cause the most reaction by the chimps.

During the observations of the chimpanzees, the number of food calls, and attention getting sounds were recorded once every minute. Each of the three tests was done in thirty second intervals. Like was hypothesized, the number of attention getting sounds were produced the most in the presence of food and a human, more so than in the presence of a human alone or food alone. The study also showed that there was not a very large difference in attention getting calls between the HA and FA conditions. In the food alone conditions, however, the chimpanzees did give a food call more frequently than under conditions with just a human present. These results show that chimpanzees do use attention getting sounds in order to get the attention of a human close by and manipulate them. This also shows that chimpanzees act different depending on the context of the situation. Chimpanzees produce specific noises intentionally for different purposes.

As more studies are done, more interesting information about these magnificent chimpanzees will be learned. There is still a lot that is unknown to us which will become clearer with time. It has to be remembered that they are very intelligent and are also very complex.

HEH

What's killing the cheetah?

Genetic bottlenecks severely alter how a population is able to respond to its environment; bottlenecks drastically reduce size in populations and lead to inbreeding and the massive consequences associated with it. Why is inbreeding bad? Genetic theory predicts inbreeding will reveal deleterious recessive alleles which may be manifested later in lowered fecundity, high infant mortality and reduced growth rate. In situations where it is common, probability of extinction is increased and opportunities for evolution are limited. (Ecological)

It is essential then that we identify the above symptoms in populations of concerned species. Ten thousand years ago cheetahs underwent a genetic bottleneck. By conjecture, it lacked genetic variability. Ecologists began studying the cheetah in captivity, reporting deleterious recessive alleles, consistent with low genetic diversity, as a cause for its poor fecundity. Recent observations, however, have been conducted in the wild, and are designed to literally watch the hand of genetic theory snatching cubs from the lair. What did these studies find? Well, in “Ecological and Genetic Factors in Conservation: A Cautionary Tale”, lions not lack of heterozygosity are being blamed for the cheetahs decline.

First, do populations of cheetah actually lack genetic variability? The answer is yes; there is no doubt the cheetah lacks genetic variability- Individuals in populations almost all can be considered brother and sister. How do we know? The major histocompatibility complex (MHC) is a multigene complex of homologous genes that encode antigens that play a key role in immune response. In most species, MHC gene products display extreme polymorphism- their variability interpreted as an adaptive strategy for accommodating rapidly evolving infectious agents that periodically afflict natural populations. By observing a gene known to be highly polymorphic among individuals in populations thought to be genetically depauperate, we are able to observe percent polymorphism for a gene over that population and directly determine presence or lack of polymorphism. Such was the basis for the study “DNA Variation of the Mammalian Major Histocompatibility Complex Reflects Genomic Diversity and Population History.” In it, N Yuhki et al calculate and compare percent polymorphism in individuals of South African and East African cheetahs. Their quantitative analysis of the genes supported previous qualitative analysis where skin grafts between 12 unrelated and 2 sibling cheetahs all failed to be rejected acutely, suggesting lack of genetic variability. (MHC)

Until recently the Cheetah has categorically realized predictions of genetic theory. The cheetah lacks genetic variability and its ability to respond to the environment and disease has been reduced. But does reduced genetic variability really account for reduced fecundity? In “Captive Breeding of Cheetahs in North American Zoos: 1987-1991,” Kraus et al quantify the results of attempts across North America to breed the cheetah in captivity. For cubs born to related parents (inbred) of southern African origin, the frequency of mortality was 14 of 34, or 41 %. By comparison, the mortality frequency for cubs born to related parents of East/southern African hybrid parents was 15 of 37, or 41 %. By contrast, the frequency for cubs born to unrelated parents (non-inbred) from southern African origin was 22 of 89, or 25%, and for cubs born from unrelated hybrid parents of East/southern African origin, 6 of 41, or 15%. In their study, outbreeding resulted in infant mortality rates that clearly followed a pattern where as genetic dissimilarity in parents increased, infant mortality in offspring decreased. Clearly, fecundity is linked to genetic variability. (Captive)

T.M. Caro et al refused to believe this was the case in the wild. In “Ecological and Genetic Factors in Conservation: A Cautionary Tale,” they tracked the timing of births and locations of lairs. Soon after a female had given birth, they entered lairs to count and weigh the cubs while the mother was known to be away hunting. Of the 125 cubs given birth to, 36 survived and infant mortality was calculated to be a high 80%. It looked as if the wild cheetah too could not escape predictions of genetic theory. However, their study was furthered as next, they sought to directly observe the cubs at their time of death. Observers were shocked. Lions were often caught preying upon entire litters of cubs. Caro writes, “Lions accounted for infant mortality in 35.5 out of 48.5 deaths”. Caro's data offers new explanation for the plight of the cheetah. Moreover, high numbers of females breeding and rapid rates of litter production are implying that neither the reproductive anatomy or physiology of either sex is functionally compromised as a result of genetic monomorphism- this, coupled with the data above, is leaving many wondering whether genetics is being overemphasized in relation to the plight of the cheetah. (Ecological)

Lack of heterozygosity can theoretically affect juvenile mortality. However, data gathered in the wild, taken directly from the lair, show rates of mortality can't be explained primarily by genetic problems. It seems ill-advised to continue to cite the cheetah as a species suffering from a consequence of low genetic diversity. (Extrinsic Factors)

In the wild, the cheetah is not bound by assumptions in theories.




Posted by: John

Worldwide Decline in Shark Attacks

If some of you are like me, and ever since you saw the movie JAWS, you can’t help but get a little nervous each time you jump in the water each summer; this story may help calm your nerves a little bit. Thanks to some University of Florida research you will be happy to know that shark attacks worldwide have barely risen and are on a downward trend. In 2005 there were 61 attacks and that number has gone up only 1. In 2006 there were 62 attacks and 4 of those were fatalities. This is a great improvement in comparison to the statistics of 2000. In that one year alone there were 79 attacks, 11 of which were deadly.

Scientists are having trouble explaining the overall decline in the attacks. Some attribute this lull in shark attacks to the fact that there is a decrease in the population of sharks located near the shore due to overfishing. Another cause could be changes in weather patterns or variations in the proximity of currents to the shoreline. Also there has been a lot more water safety precautions taken globally and swimmers are more cautious about where they are swimming. Of those attacked in 2006, surfers were the most prevalent and swimmers were a close second. Snorkelers and divers were at a distant third with only 5 attacked.

Of the four fatalities that occurred in 2006, none happened in the United States. In 2005 there were 40 U.S. attacks and that dropped slightly to 38 this past year. Florida still remains the world’s shark attack capital, but the number of attacks has lowered there as well. George Burgess, director of the International Shark Attack File at the University of Florida seemed to be happy with the results of this year’s census. He said, “It's really quite remarkable when you have only four people a year die in the mouth of a shark. The reality is, as a biologist, this is a non-problem. It's a minor, minor thing."

The four fatalities this year occurred in Australia, Brazil, Reunion Island, and the South Pacific island Tonga. The Australian attack was a woman swimming off the coast with her dog. According to Burgess, the attack may have been provoked by bloody fish parts being thrown into the water by fisherman. In Brazil, a man was fatally attacked swimming off of the northeast coast. The death on Reunion Island happened to a man who was surfing in waters that are forbidden for swimming. In Tonga a young woman from the American Peace Corps was attacked while swimming.

Let’s hope that the trend of violent interaction between sharks and humans stays on a downward spiral. Remember the next time you enter the water at the beach, that you are not in a swimming pool in your backyard, but in fact you are in another environment. An environment that sharks and tons of other aquatic life are living and interacting with one another. Also if there is warning in area to not swim, don’t try and swim there.

Sources:
http://www.sciencedaily.com/releases/1999/03/990316112634.htm

http://www.cnn.com/2007/TECH/science/02/13/sharks.reut/index.html

Mood Disorder – Depression

I always wanted to know more about brain illness- mental disorders. When I took Psychology100, I learned the basic mechanisms and symptoms of various mental disorders including anxiety disorders, mood disorders, personality disorders, schizophrenia, and so forth. I decided to start off with mood disorder, which is well-known to people. If possible, I wanted an article that deals mostly with treatments and causes of mental illness. As we all know, establishing the standard of calling a person “sane,” or “insane” is so hard. There are cultural differences, and unique mental disorders in different cultures. Therefore, the categorization made by scientists is not definite, but can be a great guide for doctors or psychiatrists. “Depression: Studies Bring New Drugs and Insights” by Harold M. Schmeck Jr. from New York Times health section was not that organized and kind of jumped back and forth, but covered a lot of past and recent issues related to severe depression.

This article contained four main points; the discovery of the first antidepressants and their basic mechanisms, their side effects and general problems, an introduction to some new antidepressants and how they can be effective in our brain, and other studies related to antidepressants.

The importance of studying mood disorder (especially depression) is presented at the very end of the article. This should have been presented at the beginning.
Depression is by far the number one cause of suicide among patients suffering from mental illness. Now, when we talk about depression, we should know that it’s not just a mere depression people experience once in a while. Depression here means people who suffer from bipolar disorder or chronic depression. Usually, people get so hopeless and sad that it would not let the person live a normal life in the society. Also, as shown in the chart provided by Dr. Joseph J. Schildkraut of Harvard Medical School, depression is by far the number one cause (40%) of suicide among patients suffering from numerous mental disorders. Fast treatment is the key in dealing with severe depression.
The first idea for an antidepressant occurred by chance in the early 1950s. MAO (monoamine oxidase) inhibitors were developed and then tricyclic antidepressants were invented. Tricyclic antidepressants are the popular “standard drugs” doctors usually use as treatments. The antidepressants either prevent the re-uptaking of excess neurotransmitters, keeping the level of neurotransmitters high enough, or inhibit the neurotransmitters from naturally breaking down.

Other studies argue that depression, especially maniac-depressive illness (also called as bipolar disorder), runs in the family. This might also have to do with the nature versus nurture issue. Scientists are trying to look at every aspect of depression and other mental disorders, hoping to find some clues for better treatment.

I found another interesting article talking about the possibilities of diagnosing various mental disorders by brain scanning in New York Times health section ( “Can Brain Scans See Depression?” by Benedict Carey).

Actually, I was hoping for some cool, clear conclusion about diagnosing depression by studying brain scanning. However, there are still many problems in matching certain states of the brain to a particular disorder. Some scientists or psychiatrists argue that a mental disorder has its own pattern but since the brain is one of the most sophisticated structures on earth, it just takes time to see that pattern.

Scanning technologies are still very useful in finding signs of seizure, tumors, and trauma. However, the “hot spot” of activity detected as “abnormal” can be a very normal activity in another person. The brain is like a person’s personality; it is multidirectional and multidimensional. Furthermore, some apparent findings according to certain mental disorders from brain scanning might not be seen in another observational experiment. The article gives an example of the evident shrinkage of the hippocampus (part of the temporal lobe) found in patients with severe depression in one study, but fails to find those results in another study.

The end of the article was quite interesting and pointed out an important fact. The writer said:

“Which comes first, the disease or the apparent difference in brain
structure or function that is being observed?”

Of course, taking control over the functioning of the brain would bring us a lot of advantages in terms of health. However, I think there is a reason why brain is not revealing its secret too easily. Think about how the world would be like when we can manipulate a brain’s functioning. Maybe we are not supposed to fully understand its secret to maintain the order of life. Anyway, I know we might be able to diagnose certain mental disorders by taking pictures of the brain, or by taking time observing its activity one day. However, I am sure it’s going to be tough; it doesn’t mean a person is actually happy when one is smiling in the picture.

Posted by clearsky83

A Dog's Laughter

It is common to most humans that laughing is one of the best exercises and is also one of our natural responses to something that we find funny. But are humans the only species that is able to laugh? Research has shown that man’s best friend, the dog, might also have its own form of laughter. To the trained ear and with the help of advanced technology the difference in pitches of a dog’s panting may actually indicate that it is able to laugh in its own form of language.
A researcher and her students at the Sierra Nevada College in Lake Tahoe performed experiments testing the pitch and frequencies of a dog’s pant during different types of activities. The research team used fifteen young dogs that they were able to record at a park using a parabolic microphone. They observed that only during play did the dog’s exhibit broader bursts of exhalations that could be defined as laughter. The researchers also played the recordings back to the dogs and observed that the dogs either picked up a toy or ran towards another dog. No aggressive behavior was detected when the dogs heard or displayed the exhalations. Along with the research regarding dog laughter, other scientists have demonstrated that primates and rats also have a distinctive laugh.
Other research found that, the “dog-laugh” or breathy panting of the dogs may help to reduce stress. It was found that dogs that are held in shelters for too long sometimes start to suffer incredible amounts of stress. The stress that the dogs feel is brought on by the fact that they have no interactions with humans or other dogs for long amounts of time. The investigators concluded that the signal of laughter was a form of communication that helped to bring peace to the dogs feeling stress and was able to initiate play.
The laughter between two humans is a distinguishable noise. Would you be able to tell if your dog was laughing with you (or possibly at you)? The pants of a dog may not just be a pant anymore; it could be almost any sign of emotion. The language that humans speak may not be the only language that is used to communicate nonspecifically. So the next time you think that your dog may be smiling at you, he actually might be.

-kamullig

Sleep Connected to Weight Problems

Sleep is something that we all need, and enjoy! How much sleep one needs seems to differ from person to person and the debate about the subject is ongoing. In my hometown, I can remember sporadic discussions all throughout my school days about whether or not school times should be made later. There is certainly controversy over the subject, especially since making school times later would affect many other aspects of children and adults lives such as sports, time for homework, and the times parents are able to work. A current study shows that amount of sleep has important affects on weight. In our society, weight has become a big issue. If the idea of teenagers and children needing more sleep for any other previously studied and stated reasons were not enough to get people to notice, perhaps the fact that inadequate sleep makes children overweight will.

This study compared the amount of sleep and BMI (body mass index) in children ages three to seventeen. Children under age three were not used in the study due to the fact that their sleep patterns are quite different not only from other children within the same age category, but also from children over age three. The data was taken from “the first and second waves of the Child Development Supplement of the Panel Survey of Income Dynamics which was a longitudinal study of a representative sample of U.S. individuals and their families” (Snell, Adam, Duncan). The children in the study kept sleep diaries; recording when they woke up and when they went to sleep. If the children were very young, the adults kept the diaries for them. They did not record what food they ate since the study was just observing the correlation between amount of sleep and BMI. Although food is obviously a factor in one’s BMI it is not what this study was interested in.

There were no gender differences in the study which is useful because it makes the results more believable since gender is one less factor to deal with. In fact, the problem with previous studies was that they did not control for other factors that might affect a child’s weight such as previous health problems, previous weight, family schedules, etc. This study focuses solely on the relationship between sleep patterns and BMI. There are no other factors involved. The study does not say that BMI is a direct result of the sleep patterns one has. The study just states that there is a correlation between BMI and sleep patterns. This was a preliminary study and if they wanted to follow up on it to see if the relationship was actually causal, then they would ask questions regarding whether or not chemicals in the brain are involved; or if the reason people who sleep less have a higher BMI is because they simply have more time to eat. In later studies it would likely also address the issue of whether or not there is such a thing as too much sleep or how someone with chronic irregular sleeping patterns BMI would be affected.

This type of study has been done before but this particular study was focused on how exactly BMI and the number of hours of sleep a child gets are related. There is no formula for that can predict ones BMI based on the amount of sleep they get since the two factors are simply found to be correlated. There is no hard and fast rule that says if one gets the right amount of sleep one will have no risk of being obese. Keep in mind that the term child refers to any person between the ages of three and seventeen. Even one hour of sleep can have a positive affect on BMI. A child that repeatedly gets less than eight hours of sleep will end up with negative impacts on their BMI; they will most likely be overweight. Between ten and eleven hours is sufficient; adolescents can get away with a little less (nine hours). At first it was not clear whether the study found that children need a certain amount of sleep overall, or if the actual times that they went to bed and woke up mattered also. Eventually it states that although the actual amount of hours is important, the bedtimes and wake times are important too. Younger children need to have earlier bedtimes; in fact increasingly they found that younger children are getting less sleep than they require. Similarly, all children need to be waking up at a later time. This is nearly impossible due to the early start time of most schools. The article feels that parents should try to get their school districts to change the start times of schools. To sum it all up, early bedtimes, later wake times, and more sleep overall will result in less overweight children. It is important to point out that this study does not imply that BMI is a direct result of the sleeping patterns one has. There are certainly many other factors such as genetics, activity level, eating habits, etc. The study simply points out that there is a correlation between the two.


Posted by KMellman

Vitamin D and Cancer Prevention

Vitamin D and Cancer Prevention

In recent years, many doctors and researchers have struggled to find a cure for cancer. Researchers are currently investigating treatments; not only to cure cancer but also prevent its development before it starts. One such strategy is known as chemopreventive treatment, which is the use of certain chemicals and drugs(both natural and synthetic), to limit the spread of cancer and possible prevention of it.
Surprisingly, one of the most useful and effective chemopreventive treatments is Vitamin D and its analogs. Statistics have shown that women with low vitamin D intake or low direct sunlight(which causes natural vitamin D synthesis) have a higher mortality rate from breast cancer. According to these studies, such women are also more likely to develop breast cancer early in life. This data has led both researchers and doctors to further investigate the potential chemopreventiveness of vitamin D and its analogs.
Clinical trials testing vitamin D and its effects on cancer are rare. The Women’s Health Initiative(WHI) is currently in mid trial of their Clinical Trials and Observational Study of Vitamin D and Cancer, which is set to end later this year(Vijayakumar et al, 2006). This study is testing the effects of vitamin D on Colorectal and Breast Cancer in postmenopausal women(ages 50-79), throughout the world. Researchers are using a vitamin D supplement in this 1:1, double blind study of about 45,000 women. They hope their results will show a decreased risk of colorectal and breast cancer in those who took the supplement, compared to those who received the placebo. Previous studies found minimal benefits of vitamin D on cancer. Although, researchers believe the results of their studies could be faulty, because many trial participants had to withdraw from the study due to hypercalcemia.
This represents one of the major road blocks in the study of vitamin D as a chemopreventive drug. Vitamin D controls the amount of calcium in the blood and how much is taken up by the bones. With too much vitamin D, calcium can build up in the body to very unhealthy levels.
One can only hope that such research can turn out positive results and a possible cure for cancer. Future studies that use vitamin D analogs, such as vitamin D5 (which is a less harmful version of vitamin D), seem to be the most promising. As for now there is no cure for cancer, but there is always hope.

Source:
Clinical Trials Using Chemopreventive Vitamin D Analogs in Breast Cancer, Dr. Vijayakumar, et al, The Cancer Journal, Vol. 12 No. 6 November/ December 2006


Posted by: JMcNeill


Update 2/20/07

First, I would like to thank everyone who read and posted comments on my blog. They were all very helpful, and the questions were great.

Many of you were curious to know what is a healthy amount of Vitamin D to take. Most doctors and medical professionals suggest taking 1,000-1,300 mg per day for adults and even more for adolescence and elderly. Most of the previous studies on Vitamin D and its effects on cancer used doses slightly higher than the 1,300 mg, about 1,500 mg. Researchers found that such a high dose for a prolonged period of time caused hypercalcemia.

Researchers started testing the body’s threshold for Vitamin D in the early 1990's. Since then research has been fairly steady, with the most recent study being started is 1998 by the Women’s Health Initiative(WHI). The study done by the WHI, is the only study, according to the article, that is test Vitamin D’s effect on Colorectal and Breast cancer.

In response to some of your other questions, too much Vitamin D and Calcium does not cause cancer. In fact it only causes hypercalcemia and excess build up of Calcium in the bones which may cause joint tenderness and weakness. Most drugs on the market to combat hypercalcemia due so by limiting the absorption of Calcium by the small intestine. Therefore it would negate the effects of Vitamin D, which promotes the synthesis and absorption Vitamin D. It was asked, since most Vitamin D is gained via sunlight, why not use sunlight of UV lamps to gain Vitamin D? The answer to this is fairly simple, most of the studies of Vitamin D’s effect on cancer are done with patients who either already have cancer (Breast Cancer in particular) or have pre-curses to cancer. As we already know, it has been proven that too much exposure to UV rays(in sunlight) can cause skin cancer. Thus researchers do not want to take the extra and un-needed risk by exposing the these patients to potentially harmful UV rays. They simply do not want to prevent one type of cancer by causing another.


Posted by: JMcNeill
2/20/07

Gene Research Leads to Possible Cures

In a recent experiment involving the MECP2 gene, a gene thought to be a major component in early brain development, mice were given a defective copy of the gene to induce symptoms of Rett Syndrome, the most physically debilitating form of autism. When an enzyme was used to correct the defective gene, the subjects exhibited striking improvements, even full recoveries in mice that were heavily affected and close to death. What is so amazing about these results is that it was previously believed that after improper development due to a malfunctioning MECP2 gene, disabilities could never be repaired- this experiment has turned that assumption upside-down.

Announced by the RSRF, or Rett Syndrome Research Foundation, the new findings from this recent study by Adrian Bird, Ph.D. once again prove that our understanding of the brain and its development is very weak, demonstrating that despite an abnormal development, the brains of adults affected with certain disorders could be repaired later in life. Until this point, it was generally accepted that neurological damage done during early development could never be reversed.

The mice that were tested not only experienced full physical recoveries, but were tested for LTP activity, or Long Term Potentiation. LTP was malfunctioning in mice that received a nonfunctioning copy of the MECP2 gene- upon correction of the gene, LTP functioned normally.

Individuals with Rett Syndrome, often girls, experience a variety of physical afflictions, including breathing problems, tremors, and a limited or nonexistent ability to walk correctly.

The research was published in the online version of the journal Science Express. It was conducted under the authority of Adrian Bird, Ph.D., who is Buchanan Professor of Genetics at the University of Edinburgh, Director of the Wellcome Trust Centre for Cell Biology, and Chairman of the RSRF Scientific Advisory Board. His lab work was carried out by Jacky Guy.

Posted by Jeremy

FROG-SICLES


Cyronics is the practice of preserving humans, animals, or any biological organism. The premise for cryonics is that frozen humans and organisms will be revived in the future when there is knowledge, and scientific techniques for the organism to live healthier and longer. It is a dream of youth and immortality. Presently, it is only legal to cryoperserve legally dead humans, though ideally it would expand to those living with cancer or autoimmune diseases in hopes of being revived when there are cures. Some people, even fellow scientists, believe cryonics is a wild sci-fi fantasy. Those who believe in cryonics point to various organisms that can freeze themselves and come back to life fully functioning. An organism in which this amazing process occurs is the North American common wood frog.


NOVA, Dr. Boris Rubinsky, and Jon Costanzo give insight on this miraculous phenomenon. The common wood frog freezes for weeks or months every winter when temperatures reach freezing or if they come in contact with an ice crystal with a freezing temperature. Their body physiology goes into a state of freeze tolerance to prepare for the cold weeks ahead. “There is no breathing, no kidney function, the heart stops.” We would think lowering the temperature would cause major cell damage, disruption of physiological reactions, or death. How is it possible that the frog can do this and survive? The wood frog secretes sugar, glucose, from the liver to the rest of his body through the circulatory system, a “natural antifreeze.” Rubinskys says

"by lowering the amount of water that leaves the cell during freezing, the glucose offers protection against the rise in ionic concentration and excessive cell shrinkage, thereby reducing chemical harm."

Once spring arrives and temperatures rise, the wood frog defrosts with his internal organs warming up first and eventually the rest of his body. The whole process occurs within a day. Soon after waking up from this almost dead state the wood frog will proceed to another important process in his life, mating.

Another common question is why the wood frogs freeze as opposed to hibernating in a warmer environment underground. Storey claim that freezing is unavoidable for the wood frogs

Unlike salamanders and toads that retreat underground to hibernate, frogs remain at the soil surface in sites with good cover of damp leaf litter to prevent desiccation. When ice penetrates these sites, frogs cannot avoid freezing because their highly-water permeable skin presents no barrier to the propagation of ice.

Exploration into how the wood frog can naturally do this gives scientists hope into using the knowledge to expand on cryosurgery, a medical technique where surgeons freeze unwanted or deadly tissue. Dr. Rubinsky used the knowledge to successfully freeze a liver, transplant it to another animal, and the animal lived!


The common wood frog is another way in which nature astounds us showing us how much an organism can go through. The wood frog provides exciting news for the time window for transplants, surgery, and hope for those who believe in cryonics. The success for cryonics is still far in the future though. The wood frog is only able to survive a few degrees below freezing (-3º), but currently organisms are cryoperserved at temperatures of -130ºC. Perhaps with further investigation of natural freeze tolerant animals combined with increasingly sophisticated technology, a frozen human now may be revived in the future.



further reading:

-- happyfeet

A Pressing Problem, Antibiotic Resistance

As we all know Antibiotics are given to sick individuals to help them fight off their illness. The first antibiotic, Penicillin, was discovered by Alexander Fleming in 1927. Most antibiotics are made from microorganisms that kill specific bacteria. They are also composed of synthetic material that will kill the microbes.

Resistance is a good thing when you are trying to stay off a certain food when you’re on a diet. Resistance on the other hand is bad when you are trying to fight an infection. The Center for Disease Control (CDC) has found that the United States has a serious problem with antibiotic resistance. Antibiotic resistance is the inability of the antibiotics to fight off bacteria. The bacteria can change its chemical makeup to fight off the affect of the antibiotic. The bacteria also become stronger or immune to the antibiotic.

If your doctor prescribes an Antibiotic for you then you have to follow some rules to make sure that your body fights off the bacteria. When you are on antibiotics you can not drink and if you’re on some other medication it might lose its effect. When taking antibiotics, make sure you follow the directions and take them for the prescribed time so you can fight off the infection. This also helps to keep that antibiotic from becoming resistant to the bacteria. Taking antibiotics when not completely necessary also increases antibiotic resistance.

The problem of bacterial resistance results from the rapid duplication of the bacteria. As a result, these bacteria can also fight off the antibiotics before it can destroy them and bacteria can also change its chemical composition at the binding site with the antibiotic and then the antibiotic does not destroy the function of the bacteria. Another reason this resistant is occurring is because the bacteria can mutate itself so it will not be destroyed by the antibiotic.

There are a few things that can be done to stop antibiotic resistance. Make sure that you only take antibiotics when you have a bacterial infection. If you take them when they are not necessary your body develops a resistance to the antibiotic. You must take the medicine for as long as it is prescribed if you stop taking it then there is a good chance that the infection will come back. Make sure you follow the proper instructions so you can fight off the infection and prevent antibiotic resistant infections.

Another approach to stop resistance is known as Phage Therapy. Phage Therapy was most commonly used in the United States before the discovery of antibiotics. A phage is a virus that enters a bacteria and destroys the metabolism and causes the bacteria to destroy itself. The success rate of Phage Therapy is fairly high having only slight side effects. (Wikipedia)


Post by: barkley519 (1)

Source: http://www.cdc.gov/drugresistance/community/anitbiotic-resistance.htm
http://en.wikipedia.org/wiki/Antibiotic_resistance

The Sex Life of a Hypolimnas bolina Male Seems to be Going Well

What happens in a group of butterflies when there are not enough males to mate? Female great eggfly butterflies(Hypolimnas bolina) don’t seem to have a problem fertilizing their eggs. Even in a population where females outnumber males 40 to 1 the females still are able to fertilize their eggs with success. How is this done?

In this week’s issue of Current Biology and Scientific American News, a study examimed these questions. Because of a parasite called Wolbachia, which kills males before they even hatch, the male population has decreased to an extreme low level. Even though females greatly outnumber the males within the population, there is no decrease in female mating. Female mating has actually increased. This is due to a small package of male sperm called a spermatophore. When a female mates with a male this spermatophore is inserted inside her. Since males have to comply with the female’s excessive need to mate they are unable to generate a suitable size of spermatophore. Smaller spermatophore have fewer sperm, and that makes it harder for the female to fertilize her eggs. The female is able to measure the diameter of the spermatophore. The females are able to sense a smaller diameter in the spermatophore and collect more sperm to fertilize her eggs. Not just one male’s spermatophore is large enough to fulfill the needs of the female great eggfly. Although the male's spermatophore is smaller than usual, due to the males capacity of sperm and sperm production, the population does not suffer in following generations.

This story seems like a continuous cycle. The females are mating with as many males as they can due to the small spermatophore size, but the trouble arises due to the fact that the spermatophore is small because the males have to impregnate females so often, and they are not able to build up a large enough spermatophore to fertilize a female. Although it interesting to notice that the population of the great eggfly has not suffered even though there is highly uneven ratio offemale and male Hypolimnas bolina.

Posted by Chris

Courtship Behavior of Spiders

The next time you take a date to the movies you may want to consider opting for an extra large popcorn, or else risk getting walked out on -- or worse, eaten! This may seem like a ludicrously unlikely scenario from a human perspective, but a male spider of the Pisauridae family would not be laughing. Research conducted at the Institute of Botany & Zoology in Masaryk University in the Czech Republic and the Department of Ecology & Genetics in Aarhus University in Denmark has delved into the courtship behavior of spiders of the family/genus Pisaura mirabilis (see cite 1). The research focused on the conditions that determine whether a female spider will mate or not. When presented with an offering of an egg sac, unwrapped fly, or a wrapped fly, the female's behavioral response was observed. It was hypothesized that the female's preoccupation with the egg sac may distract her into mating. It was opposingly proposed that the female may focus her attention on eating while mating takes place.

The experiment involved the pairing of each male spider in the study with one of three food offerings: an egg sac, an unwrapped fly, and a wrapped fly. Male spiders were then paired with female spiders, and presented their offerings. The condition of the females fell into four different categories: starved or well fed, and lacking in mating experience or experienced. Male spiders with one of the three varieties of offerings were paired with each of the four varieties of females. The investigators found that the majority of females showed no preference for food type. It would appear that motherly care on behalf of the female plays little role in her decision to eat the egg sac. The female’s desire to eat did play a role in her behavior, as starved females stole or accepted the food more quickly than fed females.

What of the instances when females are compelled to devour males? Bilde and his co-investigators concluded that as a result of females eating males during mating attempts, male food giving is selected for. The researchers further reference Randy Thornhill, who incorporating Trivers, states:

“ ..It is the relative parental investment of the sexes in their offspring that controls the operation of sexual selection. In most species a female’s investment per offspring greatly exceeds that of the male” (Thornhill 1976 on Trivers 1972).

In light of this hypothesis, it would seem appropriate that male behavior would change given the desire of the females to eat. Males that did not offer food were selected against and likely eaten, while males that offered a meal and distracted the female were more likely to be spared during mating (and thereby able to spread their “giving” genes) (Bilde). The take home message is that, along with protection, it would behoove all of us to bring an extra candy bar along …just in case.

Buabbud6 and defuria6 both included that the act of the female eating the male is not restricted to this species of spider (or only spiders for that matter). Defuria6 brought up the example of the praying mantis, a non-spider species which often exhibits eating of the male during mating. Buabbud6 offered a profound statement, "what hurts more to a spider, rejection, or death?". Across these species it seems that some "risks" are taken on behalf of the male in order to obtain mating attempts. Some of the evidence would suggest that mating is important enough to risk one's life. Additionally, the low occurance of male killing (in the spider) may be outwieghed by the advantages of mating and spreading ones genes (Blide and co-authors). Chances are that a male will not be killed during a mating attempt. Thus, it is probably in the male's favor to take the risk.

Alvarez6 asked," is there another way for the male to avoid being eaten or left behind?". Discussed in the article is the concept of thanatosis (faking death). The male, when presenting the food offering, will sometimes "fake" being dead in order to avoid provoking the female. This tactic may result in the survival of many males who would otherwise be noticed and eaten.

Posted by AKE(2)



(cite 1.) Trine Bilde, Christina Tuni, Rehab Elsayed, Stano Pekar, Soren Toft

Institute of Botany & Zoology, Masaryk University, Czech Republic
Department of Ecology & Genetics, Aarhus University Denmark

Animal Behaviour, Volume 73, Issue 2, February 2007, pages 267-273: Nuptial gifts of male spiders: sensory exploitation of the female's maternal care instinct or foraging motivation?


Randy Thornhill

The American Naturalist, Volume 110, No. 974, Juy- August 1976: Sexual Selection and Nuptial Feeding Behavior in Bittacus Apicalis (Insecta: Mecoptera)

Yellowstone Wolves

Yellowstone Wolves

I have spent a majority of my life around dogs and I find wolves very interesting. There is something thrilling about learning about the roots of man’s best friend. In modern day America wolves are seldom seen. Not only are they quick and witty in their habitat, man has hunted them off the land to protect livestock. To me it is sad that there is no surviving population in the Northeast section of the United States. Someday I hope to see live wolves. Nonetheless, there have been some successful reintroductions in other parts of the country. Yellowstone National Park is such a place. A recent article in Science Daily, “Why Wolves are not Dispersing as Fast as Expected in Yellowstone," explains why the wolf population didn’t expand the way they were predicted to after two initial reintroductions in following years.

Wolves were hunted to extinction in America by the 1970’s in order to protect cattle. Unknown at the time was the fact that wolves were a keystone species and removing them would mess up the ecosystem. In order to help halt the increasing number of elk and cougar, experts agreed reintroduction of the wolf would help regain balance. Adding wolves would slow the the growth of the cougar population by giving cougars competition for prey. Wolves of course would hunt elk and slow their population growth down as well. However, years after the initial populations were introduced biologists became baffled as to why the population of wolves was not expanding as fast as wolf populations in other areas. Prior studies determined that wolf population can disperse from an initial location at a rate of one hundred kilometers a year. The Yellowstone wolves were only dispersing ten kilometers. Mark Lewis, from the University of Alberta, and his team of researchers discovered why dispersal distances were short. They hypothesized that wolves traveling away from the original population had a hard time finding a mate. The wolves at Yellowstone remained closer to each other to keep track of each other. This meant a much slower dispersal rate to maintain higher reproduction rates.

Domesticated canines that I have spent a lot of time around have a much easier time surviving then their wild counterparts. Humans can easily arrange for two dogs to breed. They can then sell them, in turn dispersing their genealogy. Other wild canines, such as the coyote, have an easier time surviving in American forests as well. Theoretical and contributing factors for this would take up another blog, but the answer in short probably has to do with the size of the animals. So the wolf was nearly eradicated from America, but the article says from the original 32 wolves reintroduced from Canada to Yellowstone about a thousand offspring have descended.

Posted by Paul (1)

Smelly Seas

Looking toward the summer, most of us are just longing to take a rejuvenating lungful of that good old salty sea smell. But you may be surprised to learn that salt might not be the only player that triggers those olfactory nerves. Scientists from the University of East Anglia have finally found the gene that causes certain ocean-dwelling bacteria to produce the gas dimethyl sulfide (DMS), responsible not only for the ocean smell, but for cloud formation and location of food by seaside animals as well.

After comparing the gene sequences of bacteria in samples of mud from the North Norfolk coast of Britain to the sequences of other bacteria, the scientists isolated the gene responsible for production of the gas. Although they knew that DMS is produced in areas of marine plant decay such as dense algal blooms, the interesting discovery was that the DMS-producing mechanism in the bacteria is turned on only by the presence of these plant decay products (DMSP); otherwise, the gene is silent.

Such a discovery is important in explaining related ecological issues such as climate and animal behavior. DMS particles produced by the active bacteria can diffuse into the air where they act as condensation nuclei, small particles in the atmosphere around which water condenses to form clouds. Clouds can reflect radiation and cool the climate; or they can keep heat close to the surface- the specific result is affected by the cloud’s density and altitude. Dense areas of DMS particles acting as cloud condensation nuclei may reduce solar radiation by engendering denser clouds. And while there are no outstanding drawbacks to the presence of atmospheric DMS particles, it is a crucial source of atmospheric sulfur.

Moreover, research has shown that these gas particles also serve as indicators of food to birds and other sea animals, leading them to areas of high prey concentration. Small ocean animals like krill eat the plant matter of these algal blooms, attracting larger fish to feed on them, and so on until a gluttonous assembly of the food chain has appeared. Birds have the ability to smell the odor of DMS which, it appears, could either lead the birds directly to these areas or cause them to exhibit certain strategic behavior in locating the food.

While these phenomena have been exhibited from the Pacific Northwest to the oceans of Antarctica, scientists are still researching the kinds and locations of marine plants that have DMSP, in order to answer questions of where, and therefore to what degree, DMS is affecting the climate (Nissan).

So next time you visit the seaside, look at the clouds, watch the birds, and smell the dimethyl sulfurous smell of decay!

Posted by J543