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Biotech Science

The 'Weird' Male Y Chromosome Has Finally Been Fully Sequenced (theconversation.com) 145

An anonymous reader quotes a report from The Conversation: The Y chromosome is a never-ending source of fascination (particularly to men) because it bears genes that determine maleness and make sperm. It's also small and seriously weird; it carries few genes and is full of junk DNA that makes it horrendous to sequence. However, new "long-read" sequencing techniques have finally provided a reliable sequence from one end of the Y to the other. The paper describing this Herculean effort has been published in Nature. The findings provide a solid base to explore how genes for sex and sperm work, how the Y chromosome evolved, and whether -- as predicted -- it will disappear in a few million years. [...]

Spoiler alert -- the Y turns out to be just as weird as we expected from decades of gene mapping and the previous sequencing. A few new genes have been discovered, but these are extra copies of genes that were already known to exist in multiple copies. The border of the pseudoautosomal region (which is shared with the X) has been pushed a bit further toward the tip of the Y chromosome. We now know the structure of the centromere (a region of the chromosome that pulls copies apart when the cell divides), and have a complete readout of the complex mixture of repetitive sequences in the fluorescent end of the Y.

But perhaps the most important outcome is how useful the findings will be for scientists all over the world. Some groups will now examine the details of Y genes. They will look for sequences that might control how SRY and the sperm genes are expressed, and to see whether genes that have X partners have retained the same functions or evolved new ones. Others will closely examine the repeated sequences to determine where and how they originated, and why they were amplified. Many groups will also analyze the Y chromosomes of men from different corners of the world to detect signs of degeneration, or recent evolution of function. It's a new era for the poor old Y.

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The 'Weird' Male Y Chromosome Has Finally Been Fully Sequenced

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  • That us Y's are full of junk!
  • According to Reddit this is going to be used for quick DNA test strips for identify people's true gender identity when there's a question.

    • The genius of Reddit. This is biology, not ideology. Biological testing for gender identity would be akin to a CAT scan to determine a patient's preferred colour of cat.

      • Comment removed based on user account deletion
        • Re: (Score:3, Insightful)

          Neither.

          Gender is now about forcing other people to accept the delusions of the mentally ill as reality upon threat of physical or economic force or just good old fashioned harassment.

      • Comment removed based on user account deletion
      • The genius of Reddit. This is biology, not ideology. Biological testing for gender identity would be akin to a CAT scan to determine a patient's preferred colour of cat.

        Wait!

        Isn't that what they're for?!?

    • Not really.

      You do get individuals with XY chromosomes who look very much like women, and can get pregnant and so on. That is due to chromosomes elswhere not doing what they usually do in the presence of a Y chromosome.

      • You also get individuals who suffer from Galactosemia and cannot be breastfed.

        We don't redefine the taxonomy class Mammalia to account for the fact that these specific individual members don't conform to the normal definition. Nor do we suddenly pretend that humans aren't mammals because these individuals exist. Yes, you can get people with genetic abnormalities who develop in extremely unusual ways. That doesn't mean that male and female don't exist in nature. That doesn't mean that they don't have well un

    • Re:The future (Score:5, Informative)

      by omnichad ( 1198475 ) on Saturday August 26, 2023 @07:06AM (#63798484) Homepage

      The Y chromosome contains almost none of the information to define what makes a body male or female. It has a big toggle switch in it to activate genes that everyone - XX and XY have. And since there are other activation triggers to some of these genes, you get a lot of characteristics activated differently than just whether there is a Y chromosome present.

  • All that noise a couple of decades ago about sequencing of the human genome... What did that effort sequence?

    What still remains to be sequenced?

    • by vivian ( 156520 )

      It sequenced all the obvious stuff.
      It was done by sequencing lots of little bits of DNA, putting that all in a massive database, then matching sections at each end of the small sequences to others, to join them all together.
      The problem with this is that when there are lots of long repeating sections, that couldn't be accurately matched.

      Also there are lots of sections that don't seem to code for any known proteins or enzymes, so they were called "junk" DNA - though they might actually not be junk at all, but

    • by geantvert ( 996616 ) on Saturday August 26, 2023 @01:33AM (#63798048)

      The issue was that the Y chromosome contains very long sequences of repeating junk DNA and the old sequencing methods were producing very small pieces.

      Here is an analogy with all letters instead of just the four ATCG found in DNA.

      Let's imagine that sequencing gives you a lot of small pieces of no more than 10 characters such as
      (1) eThatIsT
      (2) ToBeThatI
      (3) eOrNotToB
      (4) ToBeOr
      (5) hatIsThe
      (6) OrNotToBe
      (7) BeThatIs
      (8) Question
      (9) IsTheQuest ...

      Overlapping of (7), (1) , (5), (9) and (8) produces the longer sequence BeThatIsTheQuestion
      Similarly, (4), (3) and (6) produces ToBeOrNoToBe
      And finally (2) connects those 2 sequences to form the full genome ToBeOrNotToBeThatIsTheQuestion

      That this technique does not work well if you have a lot of repeating sequences in the genome.

      Imagine that the genome contains ToBeOrNoToBe repeated a few hundred times.

      Sequencing would produce a lot of fragments such as ToBeOr, eOrNotT, ToBeOrNo, rNotToBeToB, ToBeToBe, eOrNotToB, oBeToBeOr, eToBeXrNotT, oBeOrN, oBeOr, BeOrNotT , ...

      It would be easy to figure out that ToBeOrNoToBe is repeating itself but not how many times.

      Also, some fragments may contain single mutations like the X in one of the fragments above there would be no way to figure out where that X occurs in the repetition.

      The new sequencing methods produce longer fragments and so make decoding a lot easier.

      • by jeti ( 105266 )
        The abstract says that the Y-chromosome has a 62,460,029-base-pair sequence. How long are the fragments that can now be sequenced?
        • by Entrope ( 68843 )

          https://phys.org/news/2023-08-... [phys.org] says the old techniques sequence fragments about 100 bases long, but the new ones can handle "thousands".

          https://en.wikipedia.org/wiki/... [wikipedia.org] says the trade-off with long-read techniques is a higher error rate (compared to previous sequencing techniques) that goes up as a function of the read length, which perhaps explains why it's not qualified very clearly.

      • by AmiMoJo ( 196126 ) on Saturday August 26, 2023 @04:03AM (#63798158) Homepage Journal

        So basically it's that typical man thing of never wanting to throw old junk away "just in case".

        I'll tell my wife it's not my fault, it's in my DNA!

      • So you're saying our genes are typewriters and we are the monkeys writing Shakespeare..

        Actually, that might make plenty of sense. We only need one good copy of X. The Y is a truncated mutated copy that may not matter for a lot besides turning on sex-specific genes on other chromosomes. But we won't know until we analyze the sequence. Sequencing might have been hard but it still might be because it is mostly junk.

      • Junk DNA meaning mysterious.
  • Speak for yourself, pal.
  • If you're going to repeat everything, this is going to take a long time.

  • When tons of people say you have to find your why... This dude went out and did it literally

  • Did they find the gene for penis size and has someone figured out how to adjust it via crispr?

    • by dvice ( 6309704 )

      1. You need SRY gene to get testicles (you can't have penis without them, because it would look stupid)
      2. You need AR gene. When embryo develops a tube, AR creates receptors for testosterone to attach.
      3. You need MKRN3 and KISS1R for androgen production. It might be interesting to see what happens if you leave one out, but it might not be what you want.
      4. You need SRD5A2 to convert testosterone into DHT (dihydrotestosterone) which affects the penis growth.

      Simply inactivate SRD5A2 to get smaller penis and yo

    • It's not in Y. Virtually nothing that makes you male is in the Y other than the toggle switch.

  • Most of the complex lifeforms (plants, animals) have sexual reproduction, and have done for hundreds of millions of years, Is that all done with the same X and Y chromosome?

    • Is that all done with the same X and Y chromosome?

      No [wikipedia.org].

      • Interesting, but "many" do. It would be interesting to see if all mammals had it, then it evolved away, some must be very close to that point.

    • by Agripa ( 139780 )

      Most of the complex lifeforms (plants, animals) have sexual reproduction, and have done for hundreds of millions of years, Is that all done with the same X and Y chromosome?

      No, there are other methods of sex selection. For instance reptiles use incubation temperature.

  • About 'junk' DNA (Score:5, Interesting)

    by Baron_Yam ( 643147 ) on Saturday August 26, 2023 @07:41AM (#63798552)

    A lot of what is apparently still labelled 'junk' DNA is sequences scientists thought did nothing because it didn't code proteins.

    They were wrong - it turns out DNA does a lot more than just create proteins. Which really seems like something they should have figured out right away, but maybe that's just me.

  • The idea that women biologists would be less interested in animalian sexual reproduction than men is the most mysogynistic thing I've read in edited content here.

    This site is devolving into telling us how to feel, not what to know. Stick to news.

    • The idea that men would be more interested in the mechanics of themselves than women is mundane. Try not to get triggered by men having interests.
  • I tell them it's genetic.

    Now science has proved it!

  • I thought the human genome was 'completely sequenced' by the craig ventner institute in the early 2000's? then there is this article: https://www.genome.gov/about-n... [genome.gov] are these people scam artists or what?
  • Q: This being the lowest level, the machine code if you will, was any excuse for women to love men found?

    A; Nothing to see here. Please move along.

  • Sure. Because sexual dimorphism is just a passing fad...

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