Archive for: May, 2012

Subtractive Criterion

May 17 2012 Published by under Uncategorized

Currently I'm in the process of writing an application for a Very Fancy Fellowship (VFF). Probably several thousand other folks are also doing the same and it's extremely competitive, but with a very high payoff. Yesterday, a senior faculty in my university who used to be in the scientific board of VFF was kind enough to meet with a group of faculty that are applying for VFF to give us some insight into their review process. One thing he said that they look for is whether an applicant passes the subtraction criterion. Which is basically this: If you were to suddenly drop out of science, would it make a difference to the field? Who would notice? Have your contributions been so essential that the field would be impoverished if they were missing?

This is a very harsh criterion and a very high bar. I don't think that I would pass this at all. And its not because I don't have a productive lab, publish in good places, and steadily contribute to my field. But rather because I think to pass this bar you either need to work on something so transformative and so essential that if your papers were never published, the field would be severely depleted, or that you are very good at making yourself ubiquitous at all the key conferences and talking at all the right places. And I don't think I would necessarily fit into those categories. And maybe that's the point of this VFF, that they want the tip of the creamy tippy top crop.

How about you? Would you survive the subtractive criterion?

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Lions and Babies

May 15 2012 Published by under Uncategorized

I'm sure you've seen this posted all over the internet, but I couldn't stop watching this video of a lion unsuccessfully trying to apparently eat a baby at the zoo. What is the lion doing? Is she trying to eat the baby? Play with it, kind of what cats do to mice? Is the lion attracted to the contrasty pattern in the baby's sweatshirt? I'd be happy to hear from some animal behaviorists out there.

My first reaction to this video was "Cool!", but my Supercoolwife was horrified. How about you, if this were your baby would you let this go on or pick him up immediately?

[youtube:http://www.youtube.com/watch?v=6fbahS7VSFs&feature=player_embedded]

9 responses so far

A Neuroscience Field Guide: Nerve Growth Factor

May 09 2012 Published by under Uncategorized

Nerve growth factor, NGF for short, is a soluble protein that is secreted by various tissues in the body, and it promotes the growth of nerve cell processes and survival of neurons. It is the first of a class of molecules known as neurotrophins which are very important for the development and function of the nervous system.

What is remarkable about NGF is how it was discovered and by whom. NGF was discovered by Rita Levi-Montalcini an Italian, Jewish young doctor. She originally became interested in a set of experiments by renowned embryologist Viktor Hamburger which had observed that removing a limb bud from a chicken embryo caused the sensory neurons that innervated the undeveloped limb to die off. This suggested that there was something about the target tissue that promoted neurons' survival in the embryo.

Levi-Montalcini had just graduated from medical school when Mussolini issued the "Manifesto per la Difesa della Razza", which ultimately led to a ban of all non-Aryans from having professional and academic careers. Undaunted, Levi-Montalcini set up a laboratory in her bedroom in her parents house and then after the bombing of Turin in her family's country cottage. After the War she was invited to St. Louis, MO to join Viktor Hamburger where she remained for many years and where she performed her Nobel Prize-winning research.

One of her initial observations was that if you implant specific mouse tumor cells on a chick embryo, sensory neurons will grow rapidly and sprout new axons which will innervate the tumor cells, again confirming that certain target tissues can promote nerve growth in embryonic tissues. The question was how did the target tissues do this? The key experiment came when she and her colleagues grew on one end of a cell culture dish some of these mouse tumor cells, and on the other a bit of neural tissue known as a sensory ganglion. After a few days, she observed that the neurons in the sensory ganglia grew a bunch new axons, and these axons seemed to be oriented toward the tumor cells. As if they were being attracted. This told her that the tumor cells were actually releasing some soluble factor into the growth media. The factor promoted growth of nerve cells and helped them live longer in a culture dish. This factor was later isolated by biochemist Stanley Cohen and shown to be a protein which they dubbed, imaginatively, nerve growth factor. Both Cohen and Levi-Montalcini received Nobel Prize in 1986.

 

From Levi-Montalcini's Nobel Lecture: Drawing of the cell culture experiment. The tissue on the left is the mouse tumor cells, the tissue on the left is the sensory ganglion. Note the axons growing out towards the mouse tissue.

 

How does NGF work? Now we know that NGF, as well as several other similar proteins known as neurotrophins, activate receptors in target cells which are called tyrosine receptor kinases, or Trk. Trks are proteins which are on the surface of neurons that when activated by NGF cause a series of cellular processes which cause embryonic neurons to grow new axons and to survive. Any cells which do not find their target will undergo a self-destructive process called apoptosis, thus help in the developing nervous system keep appropriate connections and eliminate inappropriate ones. Furthermore, NGF could form the basis of new therapies for treating various degenerative brain disorders and maybe promote neural regeneration after injury.

Rita Levi-Montalcini is now 103 years old, the oldest living Nobel laureate. Apparently she uses NGF eye-drops daily (it's true!).

Rita Levi-Montalcini in 2009, at her 100th birthday party.

 

Further Reading

Rita Levi-Montalcini Nobel Lecture and her Autobiography

Stanley Cohen Nobel Lecture

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Some bones

May 08 2012 Published by under Uncategorized

My family and I recently took a trip to northern Patagonia in Argentina. We visited a place called Bahía Bustamante, which is in the coast. It is beautiful, with a great deal of biodiversity including magellanic penguins, sea lions, rheas, guanacos, foxes, hares and many, many bird species. As well as fossils and lots and lots of petrified wood. The place was desolate, devoid of people for the most part, and a great place for bone collecting, since the weather is so dry it seems like boned stay fairly well preserved. The kids, my wife and I had fun finding and identifying bones of all sorts (though mostly of sheep) scattered all over the place, and when we arrived at the place where we stayed it was clear that the owner was a keen bone gatherer since he had bones displayed everywhere. We were quite excited when we saw the skull shown in the picture (front and back views). Can you guess what it is?

'Tis the top.

This is the bottom.

According to our host, it was from a group of pilot whales that got beached a few years ago. It seems that they got confused in the series of bays and small islands and a bunch of them beached. Group stranding is not uncommon among pilot whales. Apparently since they form very strong social bonds they will tend to stay together even if their "leader" is taking them into dangerous waters. During our stay we came across this pilot whale carcass which is supposedly about 3 years old (the carcass not the whale). When the whales beached, a group of biologists performed autopsies on several of them and tagged them. Thus the open flap on it's belly and the tag in its mouth.

Patagonian monster

We did not find any dinosaur eggs, but there was plenty of petrified wood, and nearby in Trelew there is a fairly well-known paleontology museum.

Our lovely bone collection.

We also made a few friends.

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Frail memories of Rock and Roll

May 07 2012 Published by under Uncategorized

Recently a post by fellow blogger Abel Pharmboy about his memories of going to an Elvis Costello concert when he was a teenager prompted me to comment about my first rock concert experience. While I was growing up in Mexico City all big rock concerts were actually banned. This policy started soon after the 1968 student massacre in Tlatelolco and persisted for about 20 years. The ban was lifted in the late 80's with a rock concert by Rod Stewart (of all people). I vividly remember my first concert when I was 16 or so. It was Carlos Santana in the former Olympic bicycle arena. I remember being about 15 or 16, and taking the subway all the way out there with my friend Luis. I remember my folks being worried, because I'd never been to a rock concert. I even remember the T-shirt I bought and how it shrunk to half its size after one washing. I remember being surrounded by what seemed to me like aging hippy dudes and very few people of my generation. I also remember the show was amazing, with a particularly good solo in "Samba pa' ti."  I also remember the ride home on an abandoned subway, late at night, and just feeling electrified for days afterward..

The problem was, most of this was not true. Its amazing how many things that simply appear etched in one's memory are totally wrong, or just mash-ups of a whole bunch of thematically-related events. Even though my memories of the Santana concert are vivid, after consulting with the Santana website and finding out that Santana didn't tour Mexico (since 1973) until 1991, and then consulting with my friend Luis, it turns out we didn't go to the concert until 1993, after I graduated college. It was at the old olympic arena, but we didn't take the subway, we drove in my friend's car. And it was he who bought the shrinking t-shirt, not me. We did go together to several concerts by subway in high school, but neither of us could remember which and exactly when. Maybe it was Pink Floyd. Or was that one in Guanajuato? Who the hell knows. I do know that neither  of us liked Rod Stewart, so that's a given that we didn't go to that one.

I wonder how many more of my formative memories I'm getting wrong!

One response so far