development
pharyngula | April 5, 2008My brain is most wonderfully agitated, which is the good thing about going to these meetings. Scientists are perverse information junkies who love to get jarred by new ideas and strong arguments, and meetings like this are intense and challenging. I've only got a little time here before the next session, so let me rip through a short summary of my morning.
Hopi Hoekstra talked about Golden mice in them thar hills: the molecular basis of crypsis in Nebraskan deermice. This was an excellent example of the kind of approach Coyne advocated the previous evening: she has a very cool system in mice…
pharyngula | April 4, 2008So here I am at the IGERT Symposium on Evolution, Development, and Genomics, having a grand time, even if I did get called out in the very first talk. There were two keynote talks delivered this evening, both of which I was anticipating very much, and which represented the really good side of science: two differing points of view wrestling with each other for consensus and for testable, discriminating differences. They also had dueling t-shirts.
Here's the argument in brief. The functional part of the genome can be roughly broken down into two components: the coding regions, or the actual bit…
pharyngula | March 19, 2008
Fossils are cool, but some of us are interested in processes and structures that don't fossilize well. For instance, if you want to know more about the evolution of mammalian reproduction, you'd best not pin your hopes on the discovery of a series of fossilized placentas, or fossilized mammary glands … and although a few fossilized invertebrate embryos have been discovered, their preservation relied on conditions not found inside the rotting gut cavity of dead pregnant mammals.
You'd think this would mean we're right out of luck, but as it turns out, we have a place to turn to, a different…
gregladen | March 18, 2008
Stay tuned, more coming.
This episode 8 of the PBS series in six bite sized parts
pharyngula | March 18, 2008
You know how people can be going along, minding their own business, and then they see some cute big-eyed puppy and they go "Awwwww," and their hearts melt, and then it's all a big sloppy mushfest? I felt that way the other day, as I was meandering down some obscure byways of the developmental biology literature, and discovered the dicyemid mesozoa … an obscure phylum which I vaguely recall hearing about before, but had never seriously examined. After reading a few papers, I have to say that these creatures are much more lovable then mere puppy dogs. Look at this and say "Awwwww!"
Light…
pharyngula | February 25, 2008Wilkins tagged me. It's all his fault.
This is supposed to be a historical meme…why bother me with this? I think it's because philosophers have a professional obligation to annoy people with weird questions, and Wilkins takes personal pleasure in poking me now and then, the brute. Here's what I'm supposed to do.
Link to the person who tagged you.
List 7 random/weird things about your favorite historical figure.
Tag seven more people at the end of your blog and link to theirs.
Let the person know they have been tagged by leaving a note on their blog.
Favorite historical figure?? I don't…
pharyngula | February 24, 2008The author of All-Too-Common Dissent has found a bizarre creationist on the web; this fellow, Randy Stimpson, isn't at all unusual, but he does represent well some common characteristics of creationists in general: arrogance, ignorance, and projection. He writes software, so he thinks we have to interpret the genome as a big program; he knows nothing about biology; and he thinks his expertise in an unrelated field means he knows better than biologists. And he freely admits it!
I am not a geneticist or a molecular biologist. In fact, I only know slightly more about DNA than the average college…
pharyngula | February 17, 2008
Since I wrote about the wacky creationist who couldn't wrap his mind around the idea that plants and animals are related, and since I generally do a poor job of discussing that important kingdom of the plants (I admit it, I'm a metazoan bigot…but I do try to overcome my biases), I thought I'd briefly mention an older review by Elliot Meyerowitz that compares developmental processes in plants and animals. The main message is that developmental processes, the mechanisms that assemble the multicellular whole, are very different in the two groups and are non-homologous, but don't get confused:…
pharyngula | January 24, 2008We had Neil Shubin here last week, and now Jerry Coyne is guest-blogging at The Loom. I look forward to the day that I can just sit back and invite prominent scientists to do my work for me here.
Although, I have to say that while Coyne is largely correct, he's being a bit unfair. He's addressing Olivia Judson's recent article on "hopeful monsters", a concept Coyne and the majority of the biological community reject. I reject it, too, but I think there are some legitimate issues that are associated with the idea that are also all too often and unfortunately discarded.
One point that Coyne…
gregladen | January 15, 2008You know that organisms develop, grow, and function in part because genes code for proteins that form the building blocks of life or that function as working bioactive molecules (like enzymes). You also know that most DNA is junk, only a couple percent actually coding for anything useful. Most importantly, however, you know that everything you know is wrong. Right?
The "Junk DNA" story is largely a myth, as you probably already know. DNA does not have to code for one of the few tens of thousands of proteins or enzymes known for any given animal, for example, to have a function. We know…
pharyngula | January 15, 2008
Hagfish are wonderful, beautiful, interesting animals. They are particularly attractive to evolutionary biologists because they have some very suggestive features that look primitive: they have no jaws, and they have no pectoral girdle or paired pectoral fins. They have very poorly developed eyes, no epiphysis, and only one semicircular canal; lampreys, while also lacking jaws, at least have good eyes and two semicircular canals. How hagfish fit into the evolutionary tree is still an open question, however.
There is a strong temptation to see hagfish as representing an earlier grade of…
pharyngula | January 7, 2008I know most of you have already read it with your print subscription to Seed, but I'll mention it anyway: my last column can now be read on the web. This one is all about the weird, accidental, clumsy way segmentation patterns in flies are set up.
pharyngula | January 2, 2008
Neurulation is a series of cell movements and shape changes, inductive interactions, and changes in gene expression that partitions tissues into a discrete neural tube. It is one of those early and significant morphogenetic events that define an important tissue, in this case the nervous system, and it's also an event that can easily go wrong, producing relatively common birth defects like holoprosencephaly and spina bifida. Neurulation has been a somewhat messy phenomenon for comparative embryology, too, because there are not only subtle differences between different vertebrate lineages in…
pharyngula | December 21, 2007
A while back, I summarized a review of the evolution of eyes across the whole of the metazoa — it doesn't matter whether we're looking at flies or jellyfish or salmon or shrimp, when you get right down to the biochemistry and cell biology of photoreception, the common ancestry of the visual system is apparent. Vision evolved in the pre-Cambrian, and we have all inherited the same basic machinery — since then, we've mainly been elaborating, refining, and randomly varying the structures that add functionality to the eye.
Now there's a new and wonderfully comprehensive review of the evolution…
gregladen | December 15, 2007Every year around this time, we start to get a lot of two-faced animal stories. I'm not sure why.
[story here]
[hat tip: Science Buzz]
pharyngula | December 15, 2007
Those of you who have been pregnant, or have been a partner to someone who has been pregnant, are familiar with one among many common consequences: lower back pain. It's not surprising—pregnant women are carrying this low-slung 7kg (15lb) weight, and the closest we males can come to the experience would be pressing a bowling ball to our bellybutton and hauling it around with us everywhere we go. This is the kind of load that can put someone seriously out of balance, and one way we compensate for a forward-projecting load is to increase the curvature of our spines (especially the lumbar…
pharyngula | December 3, 2007Here's a useful excercise: can you summarize a key concept in your field in less than a minute? Chris Mims takes a stab at explaining evo-devo — he's not trying to explain the whole field, actually, but the central concept of a master gene. He uses the analogy of a power strip for a transcription factor, which I like quite a bit, and I'm probably going to have to steal it someday.
pharyngula | November 28, 2007
Last week, I reported on this new breakthrough in stem cell research, in which scientists have discovered how to trigger the stem cell state in adult somatic cells, like skin cells, producing an induced stem cell, a pluripotent cell that can then be lead down the path to any of a multitude of useful tissue types. I tried to get across the message that this is not the end of embryonic stem cell (ESC) research: the work required ESCs to be developed, the technique being used is unsuitable for therapeutic stem cell work, and there's a long, long road to follow before we actually have stem cell…
pharyngula | November 21, 2007
A recent discovery in stem cell research is no minor event: researchers have figured out how to reprogram adult cells into a state that is nearly indistinguishable from that of embryonic, pluripotent stem cells. This is huge news that promises to accelerate the pace of research in the field.
The problem has always been that cells exist in distinct states. A skin cell, for instance, has one set of genes essential for its specific function activated, and other sets of genes turned off; an egg cell has different patterns of gene activation and inactivation. Just taking the DNA from a skin cell…