Kevin... Here's four of them.

February 20, 2010 03:27 PM

How nerve cells grow

Brain researcher Hiroshi Kawabe has discovered the workings of a process that had been completely overlooked until now, and that allows nerve cells in the brain to grow and form complex networks. The study shows that an enzyme which usually controls the destruction of protein components has an unexpected function in nerve cells: it controls the structure of the cytoskeleton and thus ensures that nerve cells can form the tree-like extensions that are necessary for signal transmission in the brain.

In order to be able to receive signals from other cells, nerve cells form complex extensions called dendrites (from the Greek 'dendron' meaning tree). The growth of dendrites in the human brain takes place mainly during late embryonic and infantile brain development. During this phase, dendrites, with a total length of many hundred kilometres, grow from the 100 billion nerve cells in our brain. The result is a highly-complex network of nerve cells that controls all bodily functions - from breathing to complicated learning processes.

In order that this incredible growth phase of brain development does not lead to chaos, the growth of the dendrites must be accurately controlled. In fact, a large number of signal processes control the direction and the speed of dendrite growth by influencing the structure of the cytoskeleton, which is inside the growing dendrite and responsible for its shape and extension.

The Göttingen-based brain researcher Hiroshi Kawabe has now discovered exactly how the growth of the cytoskeleton is controlled during the dendrite development. Using specially bred genetically engineered mice, the Japanese guest scientist, who conducts research at the Max Planck Institute for Experimental Medicine, discovered that the Nedd4-1 enzyme is essential for regular dendrite growth. Nedd4-1 is an enzyme that usually controls the degradation of protein components in cells by combining them with another protein called ubiquitin. The cell identifies these ubiquitinated molecules as "waste" and degrades them. In some cases, however, the ubiquitination does not lead to the degradation of the marked protein but changes its function instead.

Nedd4-1 prevents degradation of the cytoskeleton

Hiroshi Kawabe has now shown that the Nedd4-1 enzyme ubiquitinates a signal protein called Rap2, and thus prevents it causing the dismemberment of the cytoskeleton and the collapse of the dendrites. "As long as Nedd4-1 is active, the nerve cell dendrites can grow normally," reports Kawabe. "In its absence, the dendrite growth comes to a standstill and previously formed dendrites collapse, with dramatic consequences for the function of nerve cell networks in the brain." There are, however, probably a number of parallel operating signal paths which control the dendrite growth. This explains why nerve cells can also form dendrites without Nedd4-1 - albeit significantly fewer in number and shorter. The Nedd4/Rap2/TNIK mechanism would then be only one of several that can partially compensate each other.

Kawabe's discovery provides important new insight into the mechanisms which control the development of the brain. "What is surprising is that no-one has investigated this before," says the Japanese biochemist. Scientists have long been aware that Nedd4-1 is one of the most prevalent ubiquitination enzymes in nerve cells and is produced with great frequency in the developmental phase when nerve cells grow and form their dendrites. As Kawabe points out, the function of Nedd4-1 has already been investigated in dozens of studies. "But very little work has been carried out on its role in nerve cell development, which would have been the obvious thing to do." Source : Max-Planck-Gesellschaft

Michelle.

William Yu
5th period English
2/19/10

Autobiography

People can see what you look like, but not who you really are. You can see that I’m Chinese and wear a lot of black, but you won’t see my background and that my favorite color is purple. Judging people by their looks is bad, because when you misjudge them, they might get mad. You can't judge a book by it's cover. I’m here to tell you who I really am and not what I look like.
I am told I’m nice and kind, but whenever I am mad, I would isolate myself and listen to really loud music that fits my mood so I wouldn’t hurt anyone. I would lock myself in my room or leave my house and just sit at the 14 Muni Transit bus stop until I calm down. To myself, I find that when I’m having fun I can be immature and all, but when times are serious, I would be mature about the situation. I don’t know if you see this in me, but I like misty nights more than sunny days. Nights are the best to me. Especially if it's cold and rainy for some reason. This is why I would prefer sunsets over sunrises because after the sunsets, it's dark. Also my favorite color is purple even though I wear a lot of black. I like black and white, but purple is my favorite color even if I don't wear it much. These are stuff that you can’t see in me when you just look at me. By telling you I like nights, I should tell you about what I do until so late at night.
On Fridays, Saturdays, and Sundays I would play basketball in Chinatown until pretty late or just hanging out with friends in Downtown. When I stay out so late, it gets dangerous. I remember times like riding the bus home with my friend and seeing brawls on the back of the 8x because someone stole another person’s cell phone. Another incident is when I saw a cops surrounding a dead body in Visitation Valley while I was riding the bus. It was scary when I saw it, but I get use to it since I've seen a lot of these incidents already. Recently I saw two people fighting at a bus stop because one accused the other of stealing his phone and the other was denying it. Everyone started leaving the bus stop, but I didn't really see a big reason of leaving. Cops came soon after and people were nosy. They rather skip a 14 Limited than to miss out on what happens when the cops came. I just got on the 14 Limited since I've seen incidents like this and was pretty sure about how it ends like other fights when cops arrive. Where I was raised and live really effects the way I am now. I was raised near the Mission, go to the Mission when I was young with my mom, and live in Excelsior. I think this really effect the way I am now.
The songs I listen to are by underground rappers. My thoughts for the future is becoming a famous rapper. I wasn't really interested in rap until December of 2009. It was back when on AIM, my friend invited me into a chat room full of underground artists. I searched them up on Youtube and listened to their songs and soon realized they were around my age. They really inspired me especially two rappers in the chat room with rapper names Moc Five and Illmillion. Soon after I searched up more underground artists. Many other underground artists inspired me by their voices and lyrics such as D-Pryde, Lil Crazed, and J.Reyez. My goal right now is to record my first song and place it up on Youtube.
In conclusion, you can't see these things in people when you look at them. Would you be able to see that my goal is to become a rapper? Or did you know that my favorite color is purple? I don't think so. So please don't judge a person by what they look like because if you did that to me, you would probably be completely wrong about me. So let me tell you once more that people can see what you look like, but not who you really are.