Tuesday, July 17, 2018

Spin This News: Parental Chromosomes Develop Apart During Embryo's First Division

       Genetic researchers at the European Molecular Biology Lab (EMDL) have shown that mammalian life begins differently than originally suspected.

     It was long hypothesized that during a mammal embryo's first cell division, one spindle is responsible for segregating the embryo's chromosomes into two cells. Researchers now show that there are actually two spindles (as shown below), one for each set of parental chromosomes, meaning that the genetic information from each parent is kept apart throughout the first division.






     The publication Science published the results (which are likely to change biology textbooks) on 7/12/18. {Are there still textbooks?!}.



     This dual spindle formation may explain the high error rate in the early developmental stages of mammals, spanning the first few cell divisions. "The aim of this project was to find out why so many mistakes happen in those first divisions," says Dr. Jan (a guy!) Ellenberg, the group leader at EMBL who led the project. "We already knew about dual spindle formation in simpler organisms like insects, but we never thought (why not?!) this would be the case in mammals like mice. This finding was a big surprise, showing that you should always be prepared for the unexpected."





     Researchers have heretofore seen parental chromosomes occupying two half-moon-shaped parts in the nucleus of two-cell embryos, but it wasn't clear how this could be explained. "First, we were looking at the motion of parental chromosomes only, and we couldn't make sense of the cause of the separation," said Dr. Judith Reichmann. "Only when focusing on the microtubules -- the dynamic structures that spindles are made of -- could we see the dual spindles for the first time. This allowed us to provide an explanation for this 20-year-old mystery."




      Mitosis is the process of cell division, when one cell splits into two daughter cells. It occurs throughout the lifespan of multi-cellular organisms but is particularly important when the organism grows and develops. The key step of mitosis is to pass an identical copy of the genome to the next cell generation. For this to happen, DNA is duplicated and organised into dense thread-like structures known as chromosomes. The chromosomes are then attached to long protein fibres -- organised into a spindle -- which pulls the chromosomes apart and triggers the formation of two new cells. {The following diagram is one which will likely be updated in future embryology textbooks.}




     The spindle is made of thin, tube-like protein assemblies known as microtubules. During mitosis of animal cells, groups of such tubes grow dynamically and self-organize into a bi-polar spindle that surrounds the chromosomes. The microtubule fibres grow towards the chromosomes and connect with them, in preparation for chromosome separation to the daughter cells. Normally there is only one bi-polar spindle per cell, however, this research suggests that during the first cell division there are two: one each for the maternal and paternal chromosomes.




     "The dual spindles provide a previously unknown mechanism -- and thus a possible explanation -- for the common mistakes we see in the first divisions of mammalian embryos," Dr. Ellenberg explains. Such mistakes can result in cells with multiple nuclei, terminating development. "Now, we have a new mechanism to go after and identify new molecular targets. It will be important to find out if it works the same in humans, because that could provide valuable information for research on how to improve human infertility treatment, for example."




      In addition, the knowledge from this paper might impact legislation. In some countries, the law states that human life begins -- and is thus protected -- when the maternal and paternal nuclei fuse after fertilization. If it turns out that the dual spindle process works the same in humans, this definition is not fully accurate, as the union in one nucleus happens slightly later, after the first cell division.




     This discovery would have been impossible without the light-sheet microscopy technology (as seen above) developed at EMBL, which is now available through the spin-off company Luxendo. This allows for real-time and 3D imaging of the early stages of development, when embryos are very sensitive to light and would be damaged by conventional light microscopy methods. The high speed and spatial precision of light-sheet microscopy drastically reduce the amount of light that the embryo is exposed to, making a detailed analysis of these formerly hidden processes possible.






This is one spin we can stay with for awhile.
Steph

Earthquake experiment with brownies representing the stable craton of Canada and jello representing the tectonic plate boundary in Haiti.

The kids made "earthquake-proof" structures and observed the differences of the structures on "Canada" and "Haiti."





68 comments:

  1. This change in our understanding of mitosis is at a level that is unlikely to appear in textbooks (as opposed to research papers) any time soon, if ever. I'm curious how it happened to catch your eye?

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    1. I will likely be filling in for part of a h.s. embryology class this fall. This recent publication caught my eye as I was researching spindles.

      You don't think it will make it into textbooks? I am curious why researchers would NOT expect a dual spindle when other organisms, like insects, have them.

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  2. Replies
    1. "Moonlet" anagrams to "entomol". It bugs me that some of these are small enough that they'd be properly studied by entomologists.

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    2. From “Moon River” to “Moon Brook?”

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  3. Stable Boron Sandwiches: Molecules, not Russian Pp Tapes >>>

    https://news.brown.edu/articles/2018/07/boron

    P.S Blogger is not accepting my link, saying: “Your HTML cannot be accepted: Reference “https:” is not allowed: A” Any thoughts, wise coders? It has been happening more frequently of late and I am using the same HTML codes.


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    1. That's the error message I got when my browser was set to helpfully automagically change plain old double-quotes (") to left-double-quotes and right-double-quotes (for pretty formatting). I got into the settings function and told it to knock that off, and everything was OK after that.

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    2. Stable Boron Sandwiches

      That did the trick. If I copy the address first and then add the HTML codes, it gets confused and tries to help with the quotes. If I do the HTML code first, it leaves the quotes alone.

      Thank you!

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    3. I think Dave Barry once said something like the key to humor is knowing that boron is ten times funnier than bromium.

      Only a moron would eat a boron sandwich.

      Sarah Palin probably thinks Boron is one of Sacha Baron Cohen's aliases.

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    4. Are Boron and Moron the only true rhymes?

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    5. How about Thoron? With a half life is less than a minute, it may not make the word of the year, but it is the word of the decayed.

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    6. eco, I like it! Word of the decayed? This conversation is deteriorating quickly.

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    7. Thanks, I'm always fission for compliments.

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  4. Speaking of fission, here's a glowing review of California (sparkling?) wines.

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    1. eco, this was the most interesting part of the article to me:

      “Since the presence of cesium-137 prior to 1952 is impossible (it's a man-made isotope first released into the surroundings by nuclear testing in the mid-20th century), it has proven quite effective for detecting fraud in old vintage wines, according to the study.”

      And you can test it without opening the wine bottle!

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    2. I saw that too.

      Didn't interest me too much, since I'm very unlikely to buy a "faked" wine. But I suppose for the 1% (we know geologists and teachers are way overpaid!).

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    3. Ha!

      Do you suppose that might apply to some works of art as well?

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    4. Indeed:

      https://physicsworld.com/a/nuclear-fallout-used-to-spot-fake-art/

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  5. “Radar evidence of subglacial liquid water on Mars” is published today.

    http://science.sciencemag.org/content/early/2018/07/24/science.aar7268.full

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    1. I was going to post the same, except my article didn't have all that b o r i n g sciencey stuff.

      It's certainly tempting to send a probe or wommaned mission there to see if there are little critters. I suspect the evangelical congress would stop that.

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    2. Of course I meant womanned. Stupid non-spell check.

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    3. Womanned it is.

      If you like your mechanics popular, read on here:

      https://www.popularmechanics.com/space/moon-mars/a22541370/underground-lake-liquid-water-mars/

      If you like your mechanics to be loners, I don't know what to tell you.

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    4. Not so much a question of popularity, more like I don't need to review their protocols and methodologies, which the Science paper has to include.

      I do like the fact that they spent a year and a half or more reviewing and trying to disprove their findings, rather than immediately shouting Eureka! in the salt tub.

      To bring up an old canard, they weren't on a fusion trip like the old Pons-y scheme.

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    5. I missed that the first time around. Of course, March 1989 was when my son was born so I was happily busy taking care of him.

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    6. I think you had a very good reason to miss out on a big scientific embarrassment. Everyone was excited, except the rational scientists and skeptics who said you don't get something for nothing. One of those Newton things, I suppose.

      The Mars water is potentially exciting, but I think it's a long shot that there would be life there. Just because you have some water.... But it would be a scientific (and cultural) find of epic proportions. Even more so if the life didn't contain the a-t-g-c combination.

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    7. Weird, I don’t remember much world news from 1989 until the Berlin Wall came down that November.

      As to the life combination, a mean old acid trip, eh?

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    8. Maybe Ken Kesey was a prophet with his own mysterious message?

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    9. A Tremendously Great Culturist? Counter-Culturist?

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  6. Weren’t we just talking about sinkholes?

    https://denver.cbslocal.com/2018/07/24/sinkhole-swallows-vehicle-sheridan/

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    1. Bunch of nattering nabobs of negativity out there. Here's what you do for a sinkhole.

      Full disclosure, my largest current project is just a half block away from this site, and they did, unfortunately fill the sinkhole last November, so no terrible two's.

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    2. That old sinking feeling. . .

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  7. To your kids' pics above, the current best practice in seismic resistance is base isolation - I'm not sure if the marshmallows are intended to create that or if those are just means of connecting pieces using elements made from horse toenails. You could make a base isolation pad with a greased plate, which moves with the ground but its low friction surface keeps the building from moving as much.

    Quick aside, the Japanese had an ingenious method for seismic resistance in pagodas over 1000 years ago, and this article describes it well, though I could swear I read this in Scientific American in the 80's.

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    1. eco, we are working toward base isolation, but on a very basic level ;-). And because we have some Muslim kids who do not eat gelatin, we use gelatin-free marshmallows (no horse toenails).

      That pagoda article was fascinating. The shinbashira as pendulum really struck me (pun intended). I am going to incorporate the three ideas discussed in the article in my fall classes. Thank you!

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    2. Structural engineers have also been impressed by the pagoda, and thanks for stimulating me to look again - last time I searched I couldn't find any articles.

      I think there is debate in the Muslim community about whether horse bits are halal. It's fun to see the shock on other vegetarians (especially Indians) who did not know where marshmallows came from. Veggie friends who've spent time in the hospital have a hard time with the ubiquitous jello, though more progressive hospitals like Kaiser offer alternatives.

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    3. Yes, there's also a boxed non-gelatinous "jello" in my local store. It costs about twice as much and doesn't jell as well, though.

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    4. I can't read the pagoda article above. The Economist says I've reached my free article limit.

      Speaking of which, I just sent this cartoon to my son, the economist.

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    5. jan, what does your son think of 45’s latest headline-grabbing news about the economy?

      And, check your inbox.

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    6. My son's a game theorist. Trump's trade war doesn't stand up to Econ 101 scrutiny.

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    7. Just heard a radio lecture with Richard Wolff, who said that all aspects of Trumponomics are insane, especially cutting taxes for profitable corporations and the super wealthy while raising military spending. He's a Marxist economist, so he's very concerned about the long term impacts of increasing disparities in wealth for the 1%. But he also said conservative economists will give grudging assents to that.

      Meanwhile, while my computer is slowly processing drawings, I took the liberty of recreating the pagoda article here. Download if you want.

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  8. Some argue that Darwin was only off in his theory that evolution was a gradual process. This article shows how evolution can happen quickly....

    Still a big Darwin fan, wonder how that flat earth dude with the rocket is doing?

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  9. Thanks for the link.

    Clingy lizards—that was a surprise. I thought only babies, plastic wrap, and peaches were clingy.

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  10. 40,000-year old nematodes from Siberian permafrost.

    I hope there's no 40,000-year old smallpox in any of that thawing permafrost out there...

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    1. Absolutely.

      That image of the excuvial cuticle near the tail is cool.

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  11. PEOTS doesn't dance around the issue of lack of recognition of women in science, so I'm not just waltzing Matilda here.

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    1. Fascinating. Thanks, jan. I sent it on to Zoë, my favorite scientist. They are working toward total elimination of malaria in Ethiopia. In June, Paraguay reached 100 percent malaria free status, so Ethiopian scientists and Peace Corps workers are determinedly studying how they accomplished this status:

      https://news.un.org/en/story/2018/06/1011922

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    2. Science isn't the only field with this unfortunate distinction. Full disclosure, I know the aggrieved party slightly, she's a wonderful woman.

      Cost to eliminate malaria through 2030: $8.5 billion (estimate)
      Cost for a new aircraft carrier: $13 billion

      Which wins us more friends?

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    3. I am glad there is still time for Denise Scott Brown to receive the Pritzker Prize. I hope she does; I will watch for the news of her receiving the award!

      Wow, it seems clear to me which one to choose. It seems a small amount for such a great gains in eradicating malaria. The Ethiopian program is working to supply people with treated nets for malaria prevention and untreated nets for fishing and other uses.

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    4. I'm not sure their methodology on malaria eradication is valid. In their study, "historical funding is assessed against trends in country-level malaria annual parasite incidences and income per capita," and they extrapolate that to get a cost for total eradication. But, while genetic engineering shows some promise, none of the methods currently used have the ability to eliminate the pool of susceptible hosts or insect vectors. Smallpox was able to be eradicated because the virus only infected humans and an effective vaccine was developed. Malaria infects non-humans, so even if an effective vaccine were developed, the organism would still be out there, unless some way is also devised to eliminate the vector (perhaps by rendering them unable to serve as a vector, say by gene drive techniques). I don't think you can validly extrapolate from the historical reduction in malaria rates to eradication.

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    5. Plus, of course, our government is headed by a moron who would never spend the money on helping fight disease in shithole countries when he could buy an aircraft carrier and name it after himself.

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    6. All good points, jan. I had not thought about the non-human animal transmission.

      How did Paraguay ensure no non-human animal transmission?

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    7. WW: I doubt Denise will ever get the Pritzker. 50 years ago they were much needed agitators; their books "Complexity and Contradiction in Architecture" and "Learning from Las Vegas" were seminal in breaking the stranglehold of reductivist Modernism - though that spawned atrocious but thankfully short-lived Post Modernism.

      But those books were written in the late 60's and early 70's, and their style never really caught on, in fact it was never that popular 40 years ago.

      Jan, thanks for the biological clarifications, and yes, the report only spoke of eradication for a limited time - 20 years or so. Unless, as you say, we got rid of all mosquitoes (a popular sentiment in the summer) which would probably have some ecological downside.

      "The Lord in his wisdom made the fly,
      And then forgot to tell us why."

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    8. And then He made the mosquito, but without our chance to veto.

      Maybe Denise with have a later-in-life surge of a new architectural movement. . .

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  12. Replies
    1. Oh, I have no doubt that a technological solution is possible. But I see no evidence at all of the collective will to implement it. Quite the contrary.

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    2. I enjoyed parts 1, 2, and the epilogue. Quite worthwhile reading on climate change and politics. . .Thanks, jan.

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    3. And if you don't think that's bad enough try this.

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    4. The future for our planet is quite bleak. . .Sigh.

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  13. Not science related. >>> I thought Gilda was so funny and warm. Saturday nights watching with our whole house/dorm at Smith were magical:

    https://youtu.be/1B44XRFotuo

    It’s a probable Dames and Docs outing in September.

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    1. Gilda was hilarious and poignant, what would have happened had her life not been cut short?

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    2. eco, I wonder that as well. I think it was the warm and poignant part of Gilda that made her comedy so special. She poured her humanity into each and every funny character.

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  14. New post on “Forty-four More Planets Beyond Our Own Solar System: Four Have a Year of Less Than 24 Hours” is now up.

    There’s a new photo of Zoë and the Ethiopian Malaria Elimination Team, too!

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    1. No, it's not. And I think you're pushing it.

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    2. OK, now it's up. But I still think you're pushing it. ;-)

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    3. <<< Maybe so. It's very exciting though. . .as are my peaches ripening on my two peach trees. They ought to look like this image in a couple of weeks.

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    4. P.S. It is August, after all, "pushing it" month here in Denver in 1993 ;-).

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