Summer Assignment: 7.27.10

How Key Enzyme Repairs Sun-Damaged DNA

Maybe the first step in a sunscreen/sun burn lotion that heals DNA mutations. Though in the past, the trip from gene to marketable treatment has been very long.

World's Largest Rat Discovered

13 pound rats? Yeah, I am glad they are extinct.

Comic-Con: Zombies in the Eye of the Beholder

There are two very discreet types of zombies - fast (I am Legend, 28 Days Later) and slow (Zombieland, Night of the Living Dead). It seems rare that someone will enjoy zombies from both sides of the fence.

Summer Assignment: 7.20.10

Great comments last weeks, Keep them coming. Be sure to read other students comments as well as the post. You can also get points for responding to/commenting on a student comment as well as the linked articles.

Only one link this week, because it is a longer article, so the other two I had for this week about why high-heeled shoes are bad and shrimp on Prozac will wait till next week.

How Microbes Defend and Define Us

AN article about my favorite gross-out medical procedure - fecal transplant.

Dr. Khoruts mixed a small sample of her husband’s stool with saline solution and delivered it into her colon. Writing in the Journal of Clinical Gastroenterology last month, Dr. Khoruts and his colleagues reported that her diarrhea vanished in a day. Her Clostridium difficile infection disappeared as well and has not returned since.

It's not really completely about that, it is more about recent advances in our understanding of the bacteria that live in and on our body. Bacterial cells outnumber human cells by about 10 to 1, and scientists are just beginning to understand the roles they play. Current research highlighted here using DNA sequence analysis is uncovering a surprising amount of uniqueness to each person's bacterial load. Each "environment" on the human body has its own set of microbes, and each person may have all or part of the population.

There is even variability within one person:

Only 17 percent of the species living on one person’s left hand also live on the right one.

That number is very interesting, just based on the number of times our right and left hands come in contact. (As I read that sentence, I noticed that my hands were on top of each other and immediately moved them away from each other. Didn't want right-hand-bacteria on my left hand, I guess.)

The article also goes into current evidence for a link between microbe exposure as a baby and health later in life.

[M]any diseases are accompanied by dramatic changes in the makeup of our inner ecosystems. The Imperial College team that discovered microbes in the lungs, for example, also discovered that people with asthma have a different collection of microbes than healthy people.

All of this research may be leading to potential new treatment options for many diseases: the use of probiotics, or helpful bacteria. Just not the ones found in a container of yogurt. Those "probiotics" don't really do much for you.

I am going to stop here, before this becomes a skepticism/critical thinking/evidence-based decision making post. I am sure there will be at least one of those this summer.

Summer Assignment: 7.13.10

Hello and welcome to the official start of the AP Biology Summer Assignment. I know that I told most of you that the first post would be up last week, but a number of factors made it impossible for me to get anything up here. This will be the first post that you can earn points for, and from now until the end of the summer, they should be up once a week. Your comments will be moderated, which means that I will read them first before they show up on the blog, so don't worry if your comment does not show up immediately, it just means that I am not at the computer and have not read through all the comments yet.

Any questions or concerns can be emailed to me, or posted in the comments. On to the links for the week...

The proton shrinks in size

Not exactly biology-related, and it is only 0.00000000000003 millimeters, but that is a 4% difference, and any change in one of the three basic particles of an atom should be pretty big news.

Pohl and his team have a come up with a smaller number by using a cousin of the electron, known as the muon. Muons are about 200 times heavier than electrons, making them more sensitive to the proton's size. To measure the proton radius using the muon, Pohl and his colleagues fired muons from a particle accelerator at a cloud of hydrogen. Hydrogen nuclei each consist of a single proton, orbited by an electron. Sometimes a muon replaces an electron and orbits around a proton. Using lasers, the team measured relevant muonic energy levels with extremely high accuracy and found that the proton was around 4% smaller than previously thought.

Could be something to keep track of...though one researcher quoted in the story does seem to think that this new result could also be an error.


"Sinister Motion" may influence soccer referees

Or, just an excuse to post something about the World Cup. Once again, the third-place match ended up being much more entertaining than the final. The Dutch obviously knew they had to play physical to counter Spain's offensive capabilities. They seemed willing to take as many yellow cards as they needed to get the game to penalty kicks..,not sure it was the best strategy, and I'm still not sure why this was not given a straight red.



Why you should never arm wrestle a saber-tooth tiger.

To be honest, I only clicked through to this story because of the headline, but it is fairly interesting. Because of their oval-shaped cross section, saber-tooth cats had relatively weaker canine teeth than do modern cats, who have conical-shaped teeth. This was made up for by their stronger forelimbs.

Despite their vulnerable canines, prominent muscle attachment scars on sabertooth limb bones suggest the cat was powerfully built. Saber-toothed cats may have used their muscular arms to immobilize prey and protect their teeth from fracture, she explained.