This is a cool video from a textbook publisher (Molecular Biology of the Cell, a very good text) illustrating how Spemann/Mangold’s famous organizer experiment was done.
Also cool: those are apparently Edward De Robertis’ hands doing the experiment.
Pharyngula
Evolution, development, and random biological ejaculations from a godless liberal
Very cool! I just switched fields from straight-up physical biochemistry to an epigenetics and development lab working with Arabidopsis. Wonder if I can do this or something similar with embryonic seedlings?
The other cool part about this is the microscope video. I’d like to invite you PZ and any other interested Pharyngulites to the second ever MicroscoPARTY! This will happen Friday April 12th at 7PM eastern time. This idea for a Hangout On Air with live streams from microscopes was born at SciO13. We had our first session with great success about a month ago and would love to have monthly #MicroscoPARTYs. Currently taking suggestions for future themes. Friday’s theme is food and fungus. Help Hype the Hyphae! Hope to see you there! Watch the video from first #MicroscoPARTY
Here
Oh. That guy. He’s cool.
>_>
Nifty video of nifty experiment. I’m a little confused though.
I see the tissue graft. How does that demonstrate “the pattern of the embryo is created by interactions between one group of cells and another?”
My simple interpretation is that the part of embryo 1 that was going to develop into the head, nervous system, etc was grafted onto embryo 2 and took. What other interpretation could you use for that development if the graft was left on embryo 1 and matured there?
I know I am going to be lambasted for this but that poor frog! I sure hope we’re not insignificant creatures to a future life form which will experiment on us someday. ;-)
Because the cells of the part removed don’t become the head; the underlying cells of embryo 1 that would have been body wall become another head, instead. The donor cells just get incorporated as a small contribution to the notochord. (IIRC this is trackable by dyeing the cells (old school) or by genetic labeling nowadays, but I haven’t found a picture online.)
Here’s some class notes on it: Spemann organizer
A great video, and one I’m definitely going to show my DB students. What the video DOESN’T mention, however, is that Hilde Mangold wasn’t using Xenopus – which was adopted as an experimental system decades later – but salamander embryos from the Black Forest. She had to go out and collect them during the animal’s natural mating season, which is a few weeks in late April, bring them back to the lab and carry out her experiments all in the same day. When the salamanders were done for the year, so was she. It wasn’t yet known how to get amphibians to mate in the lab.
If you read their original paper, there were less than a dozen “twins’ produced, and one was “dropped during mounting”, as a note in the paper anticlimactically says. I can imagine her in the lab, as one of her precious dozen samples drops onto the dirty lab floor “Nooooooooo….”
She was a woman scientist in a man’s world, she has a shitty thesis project, and she died in a gas explosion shortly before Spemann got his Nobel. Since Nobels aren’t given posthumously, she wasn’t even considered. Same thing with Rosalind Franklin.
Hilde deserves way more cred than she gets!
Pteryxx @ 5
Ahhh, there are cells in embryo 2 which become the extra parts.
I missed that, must have been in the fine print.
Airy, gateau, sensai.
DMSO, Airy gateau.
@lesherb #4:
Don’t worry. Our universe is simply a simulation being run on a hugely powerful alien computer. The fact that the simulation is being run by a primary school class on their equivalent of a Raspberry Pi shouldn’t stop you from accepting that your pain and suffering are not actually real. Look at this way: at least those alien kids will learn something from your sacrifice.
Satanic Vivisectionists !
That is very interesting, but it is hard to imagine how a series of random replication errors, perhaps thousands of generations distant from each other, would result in such a specialized and isolated thing as an “organizer”.
And it’s hard to phantom how a person who claims to be evidence based (an engineer) can be so presuppositional at the end of the day without being an utterly to totally delusions fool. You can’t demonstrate your imaginry deity exists. Why do you think you have anything cogent to say? YOU DON’T, AND NEVER WILL UNTIL YOU CAN EVIDENCE YOUR PRESUPPOSITIONS….
But Nerd, my tape-loop playing friend, I have shown you that evidence. I’ve explained to you how (ignorant goat-herder) writers could not have recorded explicit details of the crucifixion a thousand years before it happened. You can read Psalm 22 for yourself and realize that David never endured the things he was writing about. Or you can look at Isaiah 53 and see the life of the Lord, and what His life was like, and what His mission was, and that was 700 years before it happened.
I don’t think I ever got around to showing you that the five wood-clad-with-gold pillars suspending the screen at the front entrance to the Tabernacle in Exodus, which rested on bronze bases. That is because bronze represents the dark, unbending judgment of the Law. The five pillars are about the first five books of the OT, the Pentateuch.
Continuing from there, the Veil separating the internal sections of the Tabernacle, was hung on four columns, also made of wood overlaid with gold, but they were on bases of silver, the metal which represents the commerce of redemption. These silver bases represent the four Gospels. The pillars of acacia wood and gold are perfect announcements of the unique Person of Jesus Christ…the wood representing His humanity, the gold represeting His Deity. Both elements in One Person. The imagery is striking to anyone with their eyes open, especially when you notice that the veil was torn from top to bottom immediately after He died. This was because the Atonement had been accomplished. “It is finished”.
All the Old Testament stuff has severe meaning. The seven Feasts described in Leviticus, are prophetic projections of the 1st Advent (Passover, Unleavened Bread and First Fruits), the great age of the Gentiles (Shavuot, the feast of weeks, which is about to conclude) and the 2nd Advent (Rosh Hashanah, Yom Kippur and Sukkot).. These aren’t reckless, random musings by deluded writers whose followers would copy and recopy to the letter over many generations. Who would do that, and for what reason?
Things like this, which show that, without a doubt, Someone outside of space and time, is directing human affairs towards a conclusion that was predicted many, many centuries ago. In that regard, I am simply not ignorant, and I would hate to be living in the middle of our current circumstances, and not have a clue as to what is going on.
But enough about what I believe, and a short list of why I believe what I believe. Would you care to explain why you think that rare, random, accidental DNA replication errors could result in a group of cells so packed with genetic information that they would be called an “organizer”?