[Wild Fragaria]

This is a relatively short article, and yet interesting.

Nature News  Published online: 5 June 2006; | doi:10.1038/news060605-1

Senior sperm have dodgier DNA

Women who gnash their teeth at men's lack of a biological clock can now take cold comfort from a survey of DNA in sperm, which has found that genetic defects can crop up as men age, potentially diminishing their fertility.

Nearly 100 men aged 22 to 80 who worked at the Lawrence Livermore National Laboratory in California, each donated a semen sample for the study. The samples were then videotaped, counted and tested at the nearby University of California, Berkeley.

Compared to their younger colleagues, the oldest men had five times as many sperm with high levels of fragmentation in their DNA, which is associated with infertility. Sperm from older men were also more likely to carry a mutation that causes achondroplasia, the most common kind of dwarfism.

But there was no age-related effect on the damage that causes Down's syndrome, which is quite closely associated with the mother's age. The study is published this week in the Proceedings of the National Academy of Sciences1.

People are increasingly choosing to delay parenthood, says Brenda Eskenazi, an epidemiologist at Berkeley, and one of the lead investigators on the project. "Men need to consider not just the female's fertility, but their own, and not just their fertility but their ability to produce healthy offspring." She adds that effects of age on many possible genetic abnormalities of sperm remain to be tested.

Routine semen analysis counts the number, mobility and shape of sperm. But standard tests do not look for DNA fragmentation or the achondroplasia mutation.

Craig Niederberger, a urologist at University of Illinois at Chicago, says the results are interesting, but adds that he is cautious about measurements of DNA fragmentation. Some previous research has not found DNA fragmentation to be directly associated with pregnancy outcomes in a fertility clinic2.

"Up until recently, when we had only semen analysis to guide us, it appeared that male reproductive potential was stable through life," Niederberger says. "Now that we have tools to investigate sperm DNA, we are beginning to see potential effects in ageing, but I wouldn't say that they are conclusive."

[Ferret]

Ownage.

[aldo_14]

(is that an order?)

It makes sense, and I'm surprised (well, maybe not so much - how many octegenarians are shagging, let alone women young enough to be fertile?) it's not been noted in studies or such before.  I'm quite curious as to whether there is a possible connection / connotation between this and the genetic triggers for cellular aging, though.

[Prophet]

There is also the issue of sperm "age". IRC the little fellas live about three days. And if a man ejaculates daily, his sperm is young all the time and has better chances of surviving the gauntlet... you know... in there. But a man who doesn't ejaculate regulary has those three days old geezers down there who can't perform as well as younger sperm. So If you hope to have children, you better have a wanky hour daily to keep the troops young and fresh!

[Colonol Dekker]

How the bloody hell does an 80 year old "Give a sample" wring the thing out into a glass ???????????

[aldo_14]

How the bloody hell does an 80 year old "Give a sample" wring the thing out into a glass ???????????

Oooh, classy.

[Wild Fragaria]

I think a lot of times, people take things for 'granted' and either never take time to report what they notice or bother to look at the subject in details.  Take the theory of punctuation evolution as an example (probably not a very good example, because it's not related to the article).  It's been known in the field but it took awhile before someone actually took a step to publish it.

[Wobble73]

There is also the issue of sperm "age". IRC the little fellas live about three days. And if a man ejaculates daily, his sperm is young all the time and has better chances of surviving the gauntlet... you know... in there. But a man who doesn't ejaculate regulary has those three days old geezers down there who can't perform as well as younger sperm. So If you hope to have children, you better have a wanky hour daily to keep the troops young and fresh!

Gee! Thanks for that! Now I can tell the wife I'm just keepin em fresh for her when she catches me!! LOL!

[Colonol Dekker]

you better have a wanky hour daily to keep the troops young and fresh!

Every man does it through genetic programming any male who doesnt get laid daily or bash one out failing having a willing female, is an out and out liar, or impotent 
TFI married

[aldo_14]

you better have a wanky hour daily to keep the troops young and fresh!

Every man does it through genetic programming any male who doesnt get laid daily or bash one out failing having a willing female, is an out and out liar, or impotent 
TFI married

so, the former then?

[Wobble73]

you better have a wanky hour daily to keep the troops young and fresh!

Every man does it through genetic programming any male who doesnt get laid daily or bash one out failing having a willing female, is an out and out liar, or impotent 
TFI married

Doesn't stop the missus disapproving tho! Oh woe is me, especially once a month!

[Wobble73]

By the way I thought WF thread about self abuse was originally about this subject!!

[Colonol Dekker]

WF, i dunno i went a little askew

wobble
Ahhhhhh, the " " week...... I share your agony,
 i just kinda leave hot water bottles and vodka around the house for her to find. She does Tae Kwon DO so that takes a lot of her stress away.  

[karajorma]

I think a lot of times, people take things for 'granted' and either never take time to report what they notice or bother to look at the subject in details.  Take the theory of punctuation evolution as an example (probably not a very good example, because it's not related to the article).  It's been known in the field but it took awhile before someone actually took a step to publish it.

Punctunctuated evolution is quite funny in that it was hailed as a big step by those who published it and everyone else said "And? This is news?"

The article is interesting but it doesn't actually state enough facts to be of much use. Okay so the sperm of an 80 year old is 5 times  more likely to carry a mutation but what about that of a 40 year old? Is this a linear progression or does it increase in speed as the body ages? It's quite possible that a 40 year old has only a minor increase

[Flipside]

Also, I think you'd need to use a much larger test base, after all, how many 80 year olds still work in a Lab? 3 at the very most I would guess, so there were probably far less results to go by.

[Colonol Dekker]

And those 3 are probably buried underneath Black Mesa........

[Turambar]

i would make babies

but really babies are the last things i need to be worrying about now, at this stage in my life
considering i make no money and don't enjoy responsibility

[Janos]

There is also the issue of sperm "age". IRC the little fellas live about three days. And if a man ejaculates daily, his sperm is young all the time and has better chances of surviving the gauntlet... you know... in there. But a man who doesn't ejaculate regulary has those three days old geezers down there who can't perform as well as younger sperm. So If you hope to have children, you better have a wanky hour daily to keep the troops young and fresh!

Gee! Thanks for that! Now I can tell the wife I'm just keepin em fresh for her when she catches me!! LOL!

you could always, you know, USE her

maybe as a dumpster

i dunno

[Wild Fragaria]

The article is interesting but it doesn't actually state enough facts to be of much use. Okay so the sperm of an 80 year old is 5 times  more likely to carry a mutation but what about that of a 40 year old? Is this a linear progression or does it increase in speed as the body ages? It's quite possible that a 40 year old has only a minor increase

Also, I think you'd need to use a much larger test base, after all, how many 80 year olds still work in a Lab? 3 at the very most I would guess, so there were probably far less results to go by.

I think it's a pretty 'new' study.  I am a bit dissapointed that they didn't talk much about the corelation between DNA fragmentation and aging; and description of the sample size.  I agree with you guys that those are very important questions.

I read another pretty interesting report about a newly discovered small RNA in mice -- Piwi interacting or PiRNA, which is somewhat related to this topic.

Nature News  Published online: 4 June 2006; | doi:10.1038/news060529-12

Mice testicles reveal new class of RNAs

Time to revise biology textbooks once again: scientists have discovered a new class of small RNAs lurking in mouse testicles.

The discovery is the latest to open up new frontiers in the study of small RNAs, a kind of genetic cousin to DNA. Discovered less than a decade ago, small RNAs are now known to regulate key processes in human health; RNA interference, for example, describes one important way that the body can shut off genes in invading pathogens.

The discovery of a new class of these genetic molecules is even more intriguing because it comes just after a report that RNA may transmit inherited information down through the generations.

"It's almost like the beginning of the RNA interference field all over again — now we have a whole other class of small RNAs and proteins to figure out," says Greg Hannon of Cold Spring Harbor Laboratory in New York.

Hannon's lab publishes one of two papers reporting the discovery today in Nature1. The other paper comes from the labs of Thomas Tuschl at the Rockefeller University in New York and Mihaela Zavolan at the University of Basel in Switzerland.

Both Tuschl and Hannon found the new class of RNAs by cataloging the entire RNA content of mouse testicles. When they did this, they uncovered a glut of RNAs that were slightly longer than the varieties of small RNAs that have already been discovered — such as microRNAs (mRNAs) and short interfering RNAs (siRNAs).

The researchers decided to check whether the new RNAs might be associated with a set of mysterious yet important proteins, called Piwi proteins. These proteins are expressed in the testes, and when they're shut off, mice can't make normal sperm. Piwis resemble other proteins that interact with small RNAs, but no one had yet identified an RNA partner for a Piwi protein.

Making an educated guess, the scientists pulled individual Piwi proteins out of mouse testes and checked what came along with them. Lo and behold, they found strands of the mysterious new RNAs stuck to the Piwi proteins.

They have named the new molecules "Piwi-interacting RNAs" — piRNAs for short.

Now the race is on to try to figure out what, exactly, the piRNAs do.

Scientists only know a few things about them. The teams have sequenced the "letters" of these longer RNAs; like DNA, RNA is a string of chemical building blocks called nucleotides. They found that piRNAs have many different sequences, but they almost always start with one chemical letter: uridine.

Tuschl and Hannon found that they come from specific regions of chromosomes. They also know that similar types of RNAs exist in zebrafish and flies, and in human testes.

Given that mice need piRNAs and Piwi proteins to make sperm, scientists are now intrigued by the idea that piRNAs and Piwis might control some of the huge changes that give rise to sperm — for example, the cell divisions that halve a cell's genetic material in the process of meiosis.

There is, as yet, no evidence for that, says Tuschl, who is reluctant to guess how the piRNAs work: "You can make really wild speculations, but I didn't make any of these in the paper because I'm afraid it's going to be too embarrassing later."

But what is clear, scientists say, is that the new discovery is yet another promising lead for the fast-moving RNA field. "The message for me is that every time we think we understand something about this process, we open a whole new door, and we see data that makes us view this in a whole new light," Hannon says.

[aldo_14]

Interesting.  I wonder if/how it bears onto the general theories (which I, er, don't know offhand) of RNA evolution?