Sorting Human Sperm By The Good, The Bad…But Not The Ugly

Microsort has been sorting human sperm by sex for years. By isolating X-chromosome bearing sperm (which create sugar-and-spice girls) from Y-chromosome bearing sperm (which creates puppy dog tails, er, boys), the company produced its first selected-sex success story in 1996: Jessica Collins. Since then, they’ve offered their X-linked genetic disease prevention services and their family balancing services to over 300 couples so far. Their technique is based on the fact that X chromosomes are bigger than Y ones, so sperm containing them have around 3% more DNA – and therefore weight. The slightly heavier “girl” sperm can be separated from their sleeker “boy” competition using a flow cytometer – not exactly the environment the sperm had hoped to find themselves in, to be sure. Around 85% of Microsort’s customers use the technique strictly for gender selection, with a success rate of 90 percent for producing girls and 75 percent for producing boys at $2300 a pop. When the company gets to 750 cases, it can seek FDA certification for the technique.

A more urgent need in fertility medicine is to separate good sperm from bad regardless of what sex child they would produce. Naturally, that’s where this month’s breakthrough in microfluidics comes in, er, handy. Michigan scientists have developed a chip that can separate the good sperm from the bad ones…but unfortunately not the ugly ones, yet. Obstetrics researcher Gary Smith hit on the idea when he heard about a curious phenomenon of fluids: microscopically narrow streams running side by side barely mix. “I thought well, gosh, this would help to sort sperm!” (For this insight, Smith gets the Geek of the Year award in my book. He hears about a fluid dynamics phenomenon, he thinks up practical sex applications. Somebody needs to explain wormholes to this guy.) A chip Smith and others developed can now take an ejaculation with only 45% motile sperm and have 98% motile sperm come out the other end – a boon for infertility treatments. Previously such treatments meant hours in a centrifuge for sperm (which left them dizzy?). Now, one pass through the Microscale Integrated Sperm Sorter yields a healthy pack of contenders that are ready for a hot night out on the town.

7 thoughts on “Sorting Human Sperm By The Good, The Bad…But Not The Ugly”

  1. Surely rickyjames is testing us, right?

    the fact that Y chromosomes are bigger than X ones, so sperm containing them have around 3% more DNA – and therefore weight.

    I understood that it’s the boys who have the “stunted” chromosome (the Y) and that therefore boy-sperms are lighter. Do I get a prize for being the first one to catch this? ;-) The Microsort site has a pretty picture.

  2. Well, it’s corrected in the article now, but Sweetwind is right, I originally had that part backwards. I’d like to claim sleepiness because I got up early to write this one, but fact is, I just plain blew it. I even thought to myself at the time, hmm, this doesn’t account for why slightly more boys are born than girls…which in fact it does. Congrats, SW! It’s always a comfort to know somebody’s actually reading this stuff, even at the expense of having to laugh at myself a little – which I do regularly anyway.

    BTW, consider this comment a receipt for a future prize – as soon as I figure out a good one. Hmm.

  3. The teaspoon of fluid in the average human ejaculation is a good way to hold Infinity in the palm of your hand.

    I’m not normally one to criticize, but if it ends up in your hand, I don’t think you’re doing it right.

  4. …that’s what you get when you wax metaphorical, so to speak. Actually, I learned something myself today on this topic I didn’t know while scanning sites to find an appropriate Big E link. There is in fact another way to do it wrong I had never heard of….

  5. …A Free One-Year Subscription to SciScoop.com!

    Oh, and I forgot to mention I really liked your comparison of the info in semen to a computer download.

  6. This is a classic example of the difference between “data” and “information.”

    IIRC, the sperm starts out from a single seed cell with 23 chromosome pairs. They’re split, half going to one sperm cell and the rest going to the other. That means each sperm contains “data” equal to half of the male’s DNA, but “information” that equals the entire DNA base plus 23 bits of information – if the bit is lit the “left branch,” for lack of a better name, is present in the sperm cell. Otherwise the “right branch” is.

    This means that when you’re looking at 100 million wigglers, the amount of data is staggering but the amount of information is exactly the same as the original set of DNA. All the 23 bits of additional data provide is a way to label the wigglers. In fact, since 2^23 is only a hair over 8 million, statistically any single wiggler present will have a dozen “identical” twins in the mix. If you think about it, this has to be the case – if spermazola and ova really contained that much more information, where did it come from? Where are the billions of people who have no resemblence at all to either parent?

    Where life gets complicated is any child involves DNA from both parents, plus 46 bits of random data (23 from each parent), plus any less common randomization.

  7. …it assumes that chromosomes are unchanging discrete bundles of information, which is not actually the case. There is also a process known as “crossover” occuring in the seed cell before splitting, in which the matching chromosomes may line up with each other and exchange pieces with each other. That is, while any chomosome YOU have is definitely from either your father or your mother, you cannot say with any confidence that a chromosome you got from your mother is from either your grandma or your grandpa – it could be a combination of grandma’s and grandpa’s. Check out this page (at the very bottom) where just like you they derive 8 million if the chromosomes were discrete, but 70,368,744,000,000 when crossover is taken into effect.

    Good thing too! In effect the chromosomes are only temporary containers for a fluid, continuous genetic code. This makes the characteristics of the offspring much more flexible (i.e. if Dad has color blindness AND the mutant power to shoot laser beams from his eyes like Cyclops on his X chromosome, I don’t have to inherit the entire package, if I’m lucky I’ll just inherit the laser beams) . I’m not sure what you mean by “if you think about it this has to be the case.” Why would this cause offspring to resemble their parents less than they would if chromosomes were discrete?

Comments are closed.