From Nature News we have this amazing video, “Fruitfly development, cell by cell.” It’s based on two new papers (references below) that produce a three-dimensional image of animal development:
Current light-sheet microscopy techniques involve illuminating one side of the sample. Either one side of a developing organism is imaged continuously, or two sides are viewed alternately, with the resultant data reconstructed to form a three-dimensional view. However, viewing from one side at a time means that the cells cannot be tracked as they migrate from top to bottom, and rotating the sample to view both sides takes so much time that when the next image is taken the cells have changed, so that they no longer line up.
Simultaneous multi-view imaging solves this problem by taking images from opposing directions at the same time and piecing data together in real time. This required massive computing power; the data sets were as large as 11 terabytes (the amount of data on about 2500 DVDs) in one of the studies1. Now every cell in a D. melanogaster embryo can be visualized as the animal develops from a fertilized egg into hatching larva. . .
Keller says that the techniques allow researchers to see what is happening in an entire animal through every stage of development, and what goes wrong as a result of different mutations. “Until now, developmental biology was a qualitative field, describing different mutations and their effect during development. But we couldn’t see what individual cells were doing in an individual embryo,” he says. Keller and his colleagues are now using the technique to follow the growth and differentiation of neurons in the developing brain of D.melanogaster and other species.
Below is the development of a Drosophila melanogaster embryo within the egg. You can see the classic insect segmentation form as the cells move about. After about a day, this egg will hatch into a larva (the “maggot”), which after about five more days will crawl out of its food (they’re reared in vials of agar-based medium), pupate on the wall of the vial, and then begin the transformation into an adult fly. At 25 degrees C (about 78F), it takes about 8-10 days from when a fly lays an egg until that egg becomes an adult fly (and another 12 hours or so before the adult female can lay another egg), so one can go through 30 or more generations per year. That’s why flies are so good for genetic and evolutionary work.
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Tomer, R., Khairy, K., Amat, F. & Keller, P. Nature Methods http://dx.doi.org/10.1038/nmeth.2062 (2012).
Krzic, U., Gunthur, S., Saunders, T. E., Streichan, S. J. & Hufnagel, L. Nature Methods http://dx.doi.org/10.1038/nmeth.2064 (2012).
Well’p, looks like I’ll be having nightmares for a while.
OT, but absolutely related to the Wright accusations earlier:
http://tpmdc.talkingpointsmemo.com/2012/06/belief-in-god-plummets-millenials.php?ref=fpnewsfeed
“A new survey by the Pew Research Center finds that belief in the existence of God has dropped 15 points in the last five years among Americans 30 and under.”
Well, done Professor Coyne, et al.!
Cool!! Fly pushing has come a long way…
Fantastic! I think there is 3 bit errors among those 11 terabytes.
Funny how they feel compelled to supply the length scale but not the time scale.
One abstract mentions 30-s resolution, so at a guess the video clock is showing hours.
You are correct on the temporal scale, 30 second resolution is the near boundary. Too many photons and the cells are damaged and growth stops. These are rather energetic particles hitting places that normally do not “see” light. My previous boss did this except in mouse embryos. I had to track cell migration in 5-8 day old embryos which was, to say the least, very challenging. The sorting mechanisms at 16-32-64 cell times was difficult enough, try tracking individual trajectories of thousands.
Fly development observations have a considerable advantage, the static nature. In mouse imaging, the embryo moves on all axes, and cannot be fixed. As such the images must registered to properly quantify trajectory and velocity. It is important to measure both direction and speed, in order to discern the emerging pattern.
Is the swirling in the lower right, towards the end of the video, related to the way that each side of the brain governs the opposite side of the body?
Also, now that “real-time” is out of the way; by “3D”, do they mean both images were produced from one dataset (of sequential slices) which could just as easily have been used to produce images from any other angle?
Time scale is in the upper right corner, bro.
Yes, that is the one I am referring to when I am trying to figure their scale. Seems it is in the HH:MM:SS format.
And with “that” I mean their clock. Scale is not stated.
One of the most amazing things I’ve ever seen. Thanks for the post, Professor.
You wanna mo Evo Devo? Read Endless Forms Most Beautiful by Sean B. Carroll (not the physicist Sean Carroll, the biologist Sean Carroll).
Hox genes, don’t you know. Hox genes.
I agree that Carroll’s book is excellent.
“Below is the development of a Drosophila melanogaster larva.”
Technically this is an embryo not a larva. It will be a larva when it hatches, a few hours after the end of the sequence shown in this video.
Indeed, my mistake. I’ve fixed it, thanks!
Oddly enough, I did not see the hand of God in there.
This is a fascinating video that helps non-biologists such as myself “see” what is going on, and get what biologists are talking about. Thanks for posting it Jerry.
Very Cool! I first thought “real time” meant precisely that, and was wondering how much heat is generated by the embryo, and how it was able to deal with it.
I am amazed. 🙂