Some fun facts about blood:
There is no substitute for blood.
Red blood cells live about 120 days.
Plasma, which is 90 percent water, is a pale yellow mixture of water, proteins and salts.
Thirteen tests are performed on donated blood, 11 are for infectious disease.
94 percent of blood donors are registered voters.
Newborn baby has about one cup of blood in his or her body.

If an individual becomes infected with harmful bacteria they may be prescribed antibiotics to rid the body of that infection.   As the antibiotic begins to work, the harmful (and some helpful) cells will be killed off but not all of them.  When start to eliminate a number of the bacteria making you ill, you will probably start to feel significantly better.  At this point it is important to continue to take the antibiotic until the prescription is complete.  The reason is that after a few days of the antibiotic some of the harmful cells will still be alive in your body.  It is possible that these cells will take up genes for resistance to the antibiotic from some of the other bacteria that are already living inside of you.  These harmful cells with newly acquired resistance genes will divide and produce clones of themselves.  Unfortunately you will start to feel sick again and if you tried to take the remainder of your antibiotic they would have a defense against it.  

The fact that different types of bacteria can share genes enables them to survive under selective pressure.  Just one of the amazing charactericstics of these simple cells.  Although we may think of bacteria as a nuisance they have much to teach us.

I remember having the chicken pox when I was in sixth grade.  Since I was the first person in my school to get it at the time I remember being amazed every time I heard someone else came down with it because I knew it had come from me.  Where had I picked it up though?  The whole idea of this virus traveling from one person to the next fascinated me.  At the time I just assumed the viruses inside me had been destroyed by my immune system.

I grew up and learned more about viruses but never really studied them.  I am only recently starting to delve into their amazing history and mechanisms for survival.  Until recently I did not understand what the relationship was between chicken pox and shingles.  I was mistaken to think the virus that infected me years ago was eradicated from my system, this is a virus that lays dormant even after you have had the symptoms associated with the infection.

The virus that causes chicken pox, varicella-zoster virus (VZV), remains inactive in nerve cells and can reactivate later in life.  This second infection is referred to as shingles and can be quite serious.  Symptoms of shingles pain throughout the body, numbness, tingling, aches, and a blistering rash.  The discomfort may last for several weeks or even in severe cases, years.

Although we have all been affected by viruses and many of us are fearful of them, so much about them remains a complete mystery to the general population.   I am eager to find out more.  What do you want to learn about them?

The timing of this internal clock is related to the amount of exposure to light.  How do circadian rhythms work in organisms that are not exposed to light?  A Somalian cavefish, Phreatichthys andruzzii, is a blind species that has been living without light for approximately 1.4 to 2.6 million years!

Researchers compared the cave fish to zebrafish during exposures to 12 hour period of light followed by 12 hour period of dark.  The cave fish remained active at irregular times while the zebrafish were active during exposure to light.  Also, it was identified that in the zebrafish, genes associated with circadian rhythms were activated from exposure to light while the same genes in the cavefish were not.

In addition to light, these rhythms can also respond to other factors, including food.  When scientists fed both types of fish at specific times for a month, they found that both fish were ready to eat at those times, demonstrating the circadian rhythms.  Also, the genes associated with the rhythms were activated in both fish.

Photoreceptors are cells with specialized proteins that respond to light.  While the genes associated with circadian rhythms in the cave fish were normal but not activated, it was found that genes for certain photoreceptors were mutated.  The mutation caused important sections of the photoreceptors to be missing.  After introducing functioning genes into cave fish, it appears that these transgenic fish could only respond to blue and green light.  This tells us that there are photoreceptors for light that we do not know about!

The cave fish offers scientists an opportunity to learn more about not only circadian rhythms, but also the mechanisms behind how we respond to various forms of stimuli. 

How is it possible that some organisms have the ability to survive in some of the dirtiest places on earth?  What survival mechanisms do they have that differ from ours?

Scientists ground up the brains and other nerve tissues from two species of insects, the American cockroach and the desert locust.  Material extracted from the samples was shown to kill more than 90 percent of a harmful type of E.coli bacteria.  In addition, the tissue extracts killed a type of staph bacteria.  There seem to be nine molecules within the tissue that are involved in defense against microbes.

Although the nine molecules have not been identified, scientists may be able to utilize the molecules in the future as a form of disease prevention in humans.

Scientists have recently identified a section of “junk” DNA that can regain function and cause disease. The section of DNA is made of repeat regions of the same sequence. They found that individuals who have 1-10 repeats on the end of chromosome 4 can develop one of the most common forms of muscular dystrophy, FSHD. The goal now is to identify a way to turn off this once non-functioning gene.

One of the important insights from the resurrection of this gene is that although some diseases can be easily explained, others result from very complicated cellular interactions. What other information will our “junk”DNA reveal in the future?

To learn more about the effects of this gene being turned on read the paper published in Science: http://www.sciencemag.org/cgi/rapidpdf/science.1189044.pdf

Neandertals, the extinct species of what are most likely our closest relatives, lived on earth at the same time as our human ancestors but died out about 30,000 years ago. With the sequence of their genome now complete, we can compare the DNA to humans and chimpanzees to learn more about what makes humans unique as a species.

The discovery of fossils is an exciting link to our past. Although the fossil bones do contain DNA, much of it is contaminated. Dr. Emily Hodges at the Cold Spring Harbor Laboratory developed a technique to quickly identify and amplify specific portions of contaminated DNA accurately. Referred to by her team as ‘array capture re-sequencing’, the procedure uses regions of human exons (lengths of DNA that code for proteins) to probe for (or fish out) the Neandertal exons from contaminated DNA samples.

Through the technique they were able to identify 88 differences (in a total of only 83 proteins) between human and Neandertal protein sequences. Amazing!

Go to the following links to access both papers:

The Draft Sequence of the Neandertal Genome:

http://www.sciencemag.org/cgi/reprint/328/5979/710.pdf

Targeted Investigation of the Neandertal Genome by Arrary-Based Sequence Capture:

http://www.sciencemag.org/cgi/reprint/328/5979/723.pdf

For addition information on Neandertals:

Science Magazine:

http://www.sciencemag.org/special/neandertal/feature/index.html

DNA Interactive:
http://www.dnai.org/ (under applications>human origins)

Interviews with Svante Paabo:

DNA From the Beginning:
http://www.dnaftb.org/30/concept/index.html (under audio/video)

The recent sequencing of the panda genome has provided even greater insight into the significance of microorganisms. Panda’s have a mutation in the gene that enables them to taste food high in protein, including meat and cheese. Since they are unable to taste these foods, they eat bamboo as an alternative. Interestingly, panda’s do not contain the genes necessary to produce the enzymes to digest bamboo. So how do they get any nutrients? The small organisms living within their digestive system are responsible for releasing the nutrients from their diet. Amazing!

How much of our own health due we owe to the organisms within us?

One example of controlled behaviors has stirred up a variety of questions. A species of fungus, Ophiocordyceps unilateralis, infects a type of carpenter ant. What is unusual about the infection is that the fungus somehow directs the ant to move to a location on the leaves of the trees normally inhabited by the ants. The location is highly specific in regard to temperature, humidity, and sunlight – ideal conditions for the fungus to grow.

Once the ant has been guided to the correct site, it is forced to bite down and lock its mandibles in place like an anchor. The ant quickly dies as the fungus takes over and uses the body to grow and produce spores. Any ants walking below are susceptible to the falling spores once they are released. You can check out the fantastic YouTube clip from FreeScienceLectures by clicking here.

How does the fungus control the ant? The scenario does bring up questions about why organisms have certain behaviors and what controls exist to direct them. What about our own behaviors is it predetermined by our genes?

I have to remind myself that the students I work with have a lot of interesting ideas and can gain a lot from the ideas in science. It helps me to think about how exciting it can be to learn about DNA and proteins for the first time. I remember all of the negative experiences I have had as a student and how I can offer a better option for those I teach. I look out at their faces and remember just how hard it is to grow up. Not only are they learning new ideas in school and being tested, they are trying to figure out who they are and how they fit in. I guess what this does for me is break my focus on the negative and allows me to see what is right in front of me with a clear perspective. I hate getting caught up in myself because the greatest feeling I have is when I know that my energy today has helped someone. Maybe I just encouraged them to participate in class or showed them how they can understand more than they thought they were capable of, but that is important to me.

As teachers we become exhausted and burnt out if we allow ourselves to stop seeing all the reasons we love what we do. There are days when it is hard for me to remember and I need to have other teachers help me. I would be grateful to have you share your ideas. What do you do to stay positive and have fun?