kottke.org posts about Carl Zimmer

Monet's ultraviolet visionApr 17 2012

In a review of the Color Uncovered iPad app, Carl Zimmer highlights something I hadn't heard before: Claude Monet could see in ultraviolet.

Late in his life, Claude Monet developed cataracts. As his lenses degraded, they blocked parts of the visible spectrum, and the colors he perceived grew muddy. Monet's cataracts left him struggling to paint; he complained to friends that he felt as if he saw everything in a fog. After years of failed treatments, he agreed at age 82 to have the lens of his left eye completely removed. Light could now stream through the opening unimpeded. Monet could now see familiar colors again. And he could also see colors he had never seen before. Monet began to see -- and to paint -- in ultraviolet.

The condition is called aphakia.

The human body's microbial ecosystemJan 27 2012

In this transcript of a talk given to the attendees of the Joint Summits on Translational Science, Carl Zimmer highlights an important aspect of understanding the human body and how to treat its many maladies: the ecosystem of microbes.

The microbes in your body at this moment outnumber your cells by ten to one. And they come in a huge diversity of species -- somewhere in the thousands, although no one has a precise count yet. By some estimates there are twenty million microbial genes in your body: about a thousand times more than the 20,000 protein-coding genes in the human genome. So the Human Genome Project was, at best, a nice start. If we really want to understand all the genes in the human body, we have a long way to go.

Now you could say "Who cares? They're just wee animalcules." Those wee animacules are worth caring about for many reasons. One of the most practical of those reasons is that they have a huge impact on our "own" health. Our collection of microbes-the microbiome-is like an extra organ of the human body. And while an organ like the heart has only one function, the microbiome has many.

When food comes into the gut, for example, microbes break some of them down using enzymes we lack. Sometimes the microbes and our own cells have an intimate volley, in which bacteria break down a molecule part way, our cells break it down some more, the bacteria break it down even more, and then finally we get something to eat.

Another thing that the microbiome does is manage the immune system. Certain species of resident bacteria, like Bacteroides fragilis, produce proteins that tamp down inflammation. When scientists rear mice that don't have any germs at all, they have a very difficult time developing a normal immune system. The microbiome has to tutor the immune system in how to do its job properly. It also acts like an immune system of its own, fighting off invading microbes, and helping to heal wounds.

While the microbiome may be an important organ, it's a peculiar one. It's not one solid hunk of flesh. It's an ecosystem, made up of thousands of interacting species.

NASA study of arsenic-based life flawed?Dec 07 2010

Carl Zimmer in Slate:

Redfield blogged a scathing attack on Saturday. Over the weekend, a few other scientists took to the Internet as well. Was this merely a case of a few isolated cranks? To find out, I reached out to a dozen experts on Monday. Almost unanimously, they think the NASA scientists have failed to make their case. "It would be really cool if such a bug existed," said San Diego State University's Forest Rohwer, a microbiologist who looks for new species of bacteria and viruses in coral reefs. But, he added, "none of the arguments are very convincing on their own." That was about as positive as the critics could get. "This paper should not have been published," said Shelley Copley of the University of Colorado.

(thx, anil)

Killer carnivorous plantsFeb 19 2010

Writing for National Geographic, Carl Zimmer on the fascinating plants that eat animals. Like the Venus flytrap, "an electrical plant":

When an insect brushes against a hair on the leaf of a Venus flytrap, the bending triggers a tiny electric charge. The charge builds up inside the tissue of the leaf but is not enough to stimulate the snap, which keeps the Venus flytrap from reacting to false alarms like raindrops. A moving insect, however, is likely to brush a second hair, adding enough charge to trigger the leaf to close.

Volkov's experiments reveal that the charge travels down fluid-filled tunnels in a leaf, which opens up pores in cell membranes. Water surges from the cells on the inside of the leaf to those on the outside, causing the leaf to rapidly flip in shape from convex to concave, like a soft contact lens. As the leaves flip, they snap together, trapping an insect inside.

See also the accompanying photo gallery.

Tags related to Carl Zimmer:
biology science

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