AP Biology class blog for discussing current research in Biology

Author: engan12

Koalas in danger

We all know that species have been going extinct when faced with threats such as climate change, reduced habitat and diseases. A recent New York Times article reveals one such species that people have realized is in danger is the koala. Besides the loss of habitat and climate changes in Australia, a new bacterium has been found in wild koalas called chlamydia.

There are two strains now known which have been affecting the koala population in Queensland. The first is Chlamydia pecorum and the second is C. pneumoniae. The bacteria are transmitted through mating and birth and possibly fighting. Some of the symptoms are eye infections, which can lead to blindness that will make it hard for them to find eucalyptus leaves, respiratory infections, and cysts that cause female koalas to be infertile.

The bacteria is growing so much in the area of Queensland since many of the koalas there are infected with koala retrovirus which acts like H.I.V. in koalas making their immunes system shut down. There is no way to treat the retrovirus but researchers are trying to create a vaccine to prevent the spread of chlamydia. There is no set plan on how to distribute the vaccine yet but they are still trying to figure out what the most efficient method of vaccination will be after tests have been completed.

from single cell to multi-cellular

Have you ever wondered how single cellular organism evolved into multicellular organisms? In a recent New York Times article, some scientists decided to see if they could get single cellular organisms to somehow evolve into multicellular ones. The problem that they thought of was that in multicellular organisms there are many cells which die so that the entire organism can live on. Why single cell organisms would group together with other single cell organisms just to die for the new multicellular organism was puzzling.

They designed an experiment where they had yeast in flasks of broth where they were being shaken for a day and then left alone for the yeast to settle. Then a drop of the settled yeast was taken and transferred to a new flask where the yeast could continue to grow. This process was continued and would allow the yeast which had evolved to be the densest and to settle furthest down to be carried to the next flask. after a few weeks the scientists observed that the yeast was falling faster and was becoming cloudy at the bottom. When looked at under the microscope the scientists found that the yeast had evolved into snowflake shaped clumps of hundreds of yeast cells stuck together. These cells were not just unrelated clumps since when separated individually, cells would recreate these snowflake shaped clumps. This property of clusters of single celled organisms to make a multicellular like organism is not special to yeast. Another organism called choanoflagellates is a single celled organism that also exhibits these traits.

One of the more amazing parts about this was that to reproduce, branches of the snowflake clump would break off after growing too large. When looked at closer they found that a section of the cells near the branch commit suicide to separate the branch to allow it to grow into a new clump. Being able to create multicellular organisms that had cells willing to commit suicide for the rest of the organism in a matter of weeks was amazing and could mean that the history of single celled organisms evolving into multicellular ones might not be as complicated as previously thought. Even though this form of natural selection was done in flasks, the natural environment could have preferred multicellular organisms over single cellular organisms for a number of reasons.

Learning to kill trees in order to save them

According to a recent New York Times article, there are researchers who are trying to figure out why trees seem to be dying for no reason. The problem they focus on is called the “sudden aspen decline” which is where aspens begin to die in large numbers after a period of drought. The scientists wanted to delve further into the plants to see what exactly was happening to the plants. The two theories were that either the tree would close its stomata to prevent transpiration but also cut off its carbon dioxide supply or that the xylem was collapsing from not having enough water. In the end they decided that in the case of the aspens the xylem had been damaged in the samples they collected from the dead trees but there could have also been other factors such as bugs damaging the trees when they were weakened by the drought. The exact details of the research were presented in a paper by William R. L. Anderegg. This research will help the scientists find ways to prevent these massive deaths of forests but this is not the only reason or the major reason for forest death so a lot of research is still needed to really help these ecosystems. The author of the Times article had also previously published a much longer article on forest deaths which goes into climate issues.

Intentionally making the flu deadlier?

In a recent New York Times article, research has been put into actually genetically enhancing viruses, specifically avian flu, to become more lethal by increaing its transmission. This might sound crazy but the scientists argue that being able to produce a more lethal virus will enable the scientists to come up with a better way of preventing a future epidemic. Other people are afraid that the enhanced viruses could accidentaly get out of the laboratory or be stolen by terrorists to cause an epidemic. Whatever the argument is, it is important for scientists to be able to better understand viruses and their ability to become a pandemic or not. From what scientists know already, the main factors for a virus to be lethal are how the virus is transmitted, what cells the virus affects, and where it enters the body.

Two seperate groups have been working on the avian flu virus, a group at Erasmus Medical Center in Rotterdam and the other at the University of Wisconsin. Dr. Ron Flouchier led the team at the lab in Rotterdam and they were able to modify the virus to transmit through the air for short distances to infect other animals, in this case ferrets because the flu behaves similarly to ferrets as it does to humans. Although they have begun to find ways to make the virus more transmissable, the number of modifications to the temperature the flu can withstand, the location where the virus attacks, and other factors to make the virus actually be threatening to humans is large. The avian flu has only infected 600 people since its discovery in 1997 and even though more than half of them died the chances of people actaully getting the flu is very low and there are vaccines for the flu.

Cheer up, its not depression, its just hypothydroidism

Have you ever felt depressed and you don’t want to take pills to make you feel better? If the answer is yes then you might be in luck. A recent article in The New York Times reports on scientists finding a correlation between some cases of depression and levels of thyroid hormones in the blood. The specific hormones are Thyroxine and Triiodothyronine known as T4 and T3 respectively which regulate a wide variety of things such as body temperature and cognitive functioning. There are two cases which can have an irregular effect on the body. The first is hyperthyroidism which is having too much of the thyroid hormone which can cause a faster metabolism, sweating, weight loss and anxiety. The other case is hypothyroidism which is having too little of the thyroid hormone which can cause physical fatigue, weight gain, and depression which is what Dr. Russell Joffe, a psychiatrist, has been looking into. He says that “treating [hypothyroidism], which affects about 2 percent of Americans, could alleviate some patients’ psychiatric symptoms and might even prevent future cognitive decline.” Patients can be given synthetic thyroid hormones such as levothyroxine if their thyroid stimulation hormone, or TSH, is too high.

This subject is still controversial because it is hard for some doctors to tell what an abnormal level of TSH is since the normal levels can range from 0.4 to 5. This is only a problem if one doctor sees a patient with a 5 and thinks nothing of but if the normal level for the patient is 0.5 then the patient has 10 times as much TSH than they should have. Other cases can be difficult since it is sometimes hard to tell if it is a case of depression or if it is just stress and anxiety instead of mild depression. The research is still being done on trying to get a better sense of how the thyroid hormones and mood link.

Aging, a side effect of preventing Cancer?

Nobody wants cancer and about 50 years ago scientists found the body’s natural defense against cancerous cells which was either to kill the cells or to turn them into senescent cells. But in a recent study by The Mayo Clinic researchers they found that if you destroy these senescent cells then the health of the mice improves as the mice get older such as longer lasting fat deposits which would cause wrinkles if they had gone and prolonged development of cataracts. The original mice they had tested had shorter life spans than normal mice so they have started to test normal life span mice to try and replicate the results. The only problem is that the method used to destroy the cells in the mice is not applicable to humans because it requires altering the cells so that any cell which turns into a senescent cell destroys itself. The scientists have gotten around this by saying that people could develop drugs to block anything produced from the senescent cells so that they won’t actually affect the rest of the body. The have already been approached by people who are interested in these results and who want to start development on these drugs. The scientists say this does not actually extend life but it does extend the healthy part of life.

Bilingual Babies?

Everyone learns to speak one language from their parents when they are young. But when they get older they have to take classes to relearn a second language. This isn’t easy and people spend most of their elementary school life trying to learn the basics. Learning a second language in today’s world is very useful because so many people travel to different countries for business and there is not one main language yet. The question of should parents teach their children two languages when they are babies or shouldn’t they has been a question for a long time. The trouble is that it is very hard to see when babies actually start learning to understand languages. Antoher worry with teaching babies two languages is that they will become confused with both languages. Researchers have begun to use Electroencephalography (EEG) on babies to see if their brains were even recongnizing words from different languages.

In a recent New York Times article, one group of researchers from the University of Washington used babies between the ages of 6 and 12 months from both monolingual and bilingual families. They found that all monolingual babies were able to recognize different phonetic sounds regardless of what language it was. But the monolingual babies who were 10 to 12 months old only registered sounds from the language spoken at home and had no recognition of the second language. The bilingual babies recognized sounds from both languages but couldn’t differentiate between them from ages 6 to 9 months, but from 10 to 12 months old the bilingual babies were able to discriminate sounds from both languages. In a different recent study researches from the University of British Columbia studied newborn babies and found that newborn babies had preferences for whatever language or languages their mothers spoke while pregnant. Other research has shown that bilingual babies are also able to “learn different ways to solve logic problems or to handle multitasking.”

So if you ever have a baby, make sure that you expose it to two languages to make it an adorable genius!

History through Hair

We all know that DNA makes up who we are and what our bodies are like. But scientists have been trying to do new things with genes and specifically what the sequences of a gene can tell us about our history. DNA becomes mixed when people from different places migrate around the world and reproduce with other people. Because of this, human DNA has become very similar around the world with certain traits being associated with certain areas of the world, but an over all diffusion of most traits.

But recently scientists have found a people who have some how managed to stay isolated for thousands of years. In a recent article in The New York Times, the scientists were finally able to get a lock of hair from one of these Australian Aborigines. When scientists sequenced a lock of hair from an Australian Aborigine, they found that it had “no evidence of European admixture and estimate contamination levels to be below .5%.” This means that the Aborigine’s DNA hasn’t been influenced by any other people around the world since they migrated from Africa to Australia about 50,000 years ago. For these people to have kept themselves isolated for so long is amazing, but it also means that these people’s DNA is one of the closest to links to the human race’s ancestors.

These scientists have tried to use their knowledge about human DNA to figure out how the earliest people migrated from place to place through history. This is limited because DNA has a very random component of what genes get passed on. Also scientists look for mutations which have developed in one group of people that isn’t present in another group of people to see when these people could have diverged in migration in history. This is only a guess becuase mutations are random and so is their frequency. When trying to estimate when things could have happened by using the differences in the number of mutations in DNA, scientists have to make guesses that span around ten thousand years depending on how far back they go.

Scientists have been studying DNA for a very long time. There have been many different ways people have thought of using DNA, some which seem like crazy science fiction such as the movie GATTACA which uses the idea of controlling every bit of a person’s DNA to make them perfect. Then there are the other ones which people might never have thought possible but which are now well known such as cloning an animal by implanting DNA from one animal into another animal’s egg cell. How far can people go with cloning and other DNA research? What other uses does DNA provide?

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