The researchers chose to examine the sperm of crickets, because, as with humans, you can get samples of it without having the male come into contact with a female first.
What’s the News: You might already know that sperm, which can survive for only a few hours when exposed to the outside world, can live for several days in women after ejaculation. But did you know that an ant queen can fertilize her eggs with sperm she’s stored for up to 30 years? And that organisms as diverse as birds, reptiles, and insects can hang onto sperm and keep it fresh for days, weeks, or months?
Scientists studying this ability have been trying to figure out how females do it, and in a recent paper, researchers put forth evidence showing that the ladies may be arresting the aging process, by slowing down sperms’ metabolism.
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If having kids has made you feel like less of a party animal, men, you now have some science backing you up. A new study following men from their single salad days through the early years of their children’s lives found that fathers had a steeper decline in testosterone levels than men who remained single and childless. Though previous studies had indicated that fathers had lower testosterone, this is the first study to look at men before and after fatherhood, showing that it’s not just that lower-testosterone males are more likely to become dads. (In fact, this study shows the opposite—it’s the hormone-pumped guys who are more likely to settle down with a partner and have kids.)
But testosterone declines naturally with age, and stress is known to contribute to cellular aging. Is the accelerated decline because zero sleep, frayed nerves, and other byproducts of procreating are making men old before their time? That’s a question for next time—this study doesn’t address the decline’s cause.
Image courtesy of edenpictures / flickr
What’s the News: The human brains, capable as it is of amazing mental feats, comes with a downside: it shrinks as we get older, contributing to memory loss, reduced inhibitions, and the other cognitive dysfunctions of age. But even chimpanzees, our closest living relatives, don’t suffer this sort of brain loss, according to a study published online yesterday in Proceedings of the National Academy of Sciences. This unusual shrinkage of the human brain, the researchers say, may be a result of our long lifespan. (more…)
What’s the News: It turns out that humans aren’t too different from blue-footed boobies, at least when it comes to age and fertility. Researchers have recently discovered that the sperm of blue-footed boobies declines with age. And unlike humans, the blue feet of the boobies also fade with age, revealing that one reason why female boobies tend to mate with brighter-footed males is to ensure the robustness of the sperm and the health of their offspring. “The study provides us with a new way of looking at what lies behind sexual signals,” lead author Alberto Velando told TIME, “pointing to the importance of sexual selection in eliminating genetic mutations.” (more…)
When doctors want a clue to which seniors might have many years still ahead of them—and who might be in trouble—it seems one of the best pieces of evidence could be simply how fast the person walks.
That’s the conclusion of a study by University of Pittsburgh scientists published this week in the Journal of the American Medical Association. The work reviewed the results of nine other studies over the years that included more than 34,000 people aged 65 or older. When they tallied the total results, the numbers jumped off the page:
Only 19 percent of the slowest walking 75-year-old men lived for 10 more years compared to 87 percent of the fastest walking ones. Only 35 percent of the slowest walking 75-year-old women made it to their 85th birthday compared to 91 percent of the fastest walkers. [Boston Globe]
The results aren’t a huge surprise (“duh” comes to mind). The researchers note that walking is controlled falling, involving fine muscle control and the synchronicity of several systems:
“Walking requires energy, movement control, and support and places demands on multiple organ systems, including the heart, lungs, circulatory, nervous, and musculoskeletal systems,” the authors wrote. “Slowing gait may reflect both damaged systems and a high energy cost of walking.” [Los Angeles Times]
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Researchers have identified targets that could help produce old-age-defying drugs and a fountain of youth for the baby boomer population… but haven’t we heard this all before?
The study, published in Nature this week, used the enzyme telomerase to stop and actually reverse the aging process in prematurely-aged mice.
Telomerase keeps chromosomes structurally sound by beefing up telomeres, the repetitive segments of junk DNA at the ends of chromosomes. Telomeres act as protective buffers for the chromosome’s working genes during cell division, when the chromosome is shortened and genetic material at the tips is lost.
For the new study, researchers created special mice whose telomerase activity could be switched on and off. When telomerase was turned off, the mice aged prematurely.
These animals age much faster than normal mice–they are barely fertile and suffer from age-related conditions such as osteoporosis, diabetes and neurodegeneration. They also die young. “If you look at all those data together, you walk away with the idea that the loss of telomerase could be a very important instigator of the ageing process,” says [lead author Ronald] DePinho. [Nature News]
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Forensic scientists of the future may soon have a new tool at their disposal. Given a drop of blood, researchers in the Netherlands have roughly determined the age of the person it came from. But for now, it really is rough–the researchers found they could only estimate a person’s age to within 9 years.
Currently, a crime scene investigator who obtained a spot of blood can check its DNA to see if it matches a known suspect or someone in a law enforcement database, and can use the DNA to determine a few other characteristics like gender and eye color. But age is tougher to estimate. Lead researcher Manfred Kayser, who works on forensic molecular biology at Erasmus University Medical Centre, explains that the best methods of determining age rely on testing bones or teeth, but he wanted to find a method that didn’t require skeletal remains.
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We can predict your chances of living exceptionally long, with 77 percent accuracy, by looking at 150 tiny genetic variants. That’s what researchers claimed in a Science paper that we described last week. Those predictive powers have left some feeling a little uneasy–and not just about what futures are buried in their genomes. Where the paper‘s authors saw correlations, some experts are now seeing errors from DNA testing chips.
No DNA chip is perfect; it can get things wrong as it sorts through hundreds of thousands of genetic variants. In fact, certain chips might even make the same error repeatedly. That could cause problems, because what looks like a genetic variant common to a group of people could instead just be an echoed flaw in one chip’s testing capabilities.
Newsweek, which broke this story, reports that the Boston University researchers who led the study did, in fact, use different chips, but not enough different chips to rule out this potential error. They used two different types of DNA chips to test the centenarian group (about 1,000 people whose ages ranged from 95 to 119): a 370 chip that examines 370,000 genetic variants and a 610-Quad that examines 610,000 variants. The control group (of about 1,200 younger people) was tested with those two chips and a few others, thus possibly hiding any shared errors.
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UPDATE: Some experts are questioning the validity of this study, and are suggesting that technical errors skewed the results. Full coverage here.
If you want to know how to get old, it’s best to ask the experts. That’s what Paola Sebastiani, a researcher at Boston University School of Public Health, did; She decided to look at the genes of 1,055 people, many who had already seen their 100th birthday.
As described in a paper published in Science today, Sebastiani’s team found that they could predict a person’s “exceptional longevity” with 77 percent accuracy.
The researchers looked at small variants called single-nucleotide polymorphisms (or SNPs) on the centenarians’ genomes; Sebastiani found she could use 150 SNPs to predict who would live to such exceptional ages.
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In today’s edition of far-out science, researchers have found evidence that the wafting aroma of food has an effect on an organism’s lifespan–and they’ve demonstrated that interfering with a fruit fly’s sense of smell causes it to live a longer, healthier life. While there’s no guarantee that the trick would work for humans, optimistic researchers suggest that certain odors—or drugs that block us from sensing them—might one day help prevent disease and extend lives [ScienceNOW].
In the past decade, scientists have established a clear connection between extremely low-calorie diets and extended lifespans; studies have demonstrated that yeast, fruit flies, mice, and monkeys on these diets live longer than their peers. While the exact mechanism at work isn’t yet clear, researchers suspect that a near-starvation diet causes an organism’s metabolism to slow down, and triggers other changes that evolved to help organisms survive in times when food was scarce. Now scientists say it may not be just what a creature eats, but also what it smells that has an effect on how long it lives.
In one 2007 study, molecular biologist Scott Pletcher and his colleagues found that completely eliminating fruit flies’ sense of smell caused them to live nearly 20 percent longer than normal flies. They also found that wafting the smell of yeast, a tasty treat for fruit flies, towards flies that were on a low-cal, live-extending diet hastened the death of those flies. This led the scientist to hypothesize that specific odors might be influencing the flies’ lifespans. Luckily, other scientists had identified a receptor in a group of neurons that enable fruit flies to smell carbon dioxide, which signals the presence of a good meal of tasty yeast [ScienceNOW]. So, Pletcher and his team set out to find if the CO2 had anything to do with the duration of the flies’ lives.
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Louise Brown, the first baby conceived through in vitro fertilization, will be turning 32 this year, and most people born through IVF are still younger than 30. While the technique has become commonplace for would-be parents struggling with fertility problems, doctors note that the long-term effects of the procedure still aren’t certain. Now, some scientists are saying they see slight differences in the DNA expression of people born via IVF, and that it’s possible they could be at higher risk for conditions like cancer or diabetes later in life.
Says lead researcher Carmen Sapienza said “By and large these children are just fine, it’s not like they have extra arms or extra heads, but they have a small risk of undesirable outcomes” [The Guardian]. Rather, the team found a very subtle impact. In 75 IVF babies and 100 naturally conceived ones, they examined 700 genes that particularly interested the researchers because they are linked to fat cell development, insulin signaling, and other functions associated with diseases for which people tend to be at higher risk as they age. The scientists checked DNA methylation, a modification to DNA which affects gene expression, and found that 5 to 10 percent of IVF babies had abnormal patterns of methylation.
Sapienza’s team published the study in October in Human Molecular Genetics, but his work is picking up attention after he spoke at the American Association of the Advancement of Science meeting in San Diego.
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Sure, Botox can banish crows feet, smooth those wrinkles, and lift those frown lines, making the client look more youthful–and somewhat expressionless. But the treatment may have effects that are more than skin deep. A new study suggests that by paralyzing the frown muscles that ordinarily are engaged when we feel angry, Botox short-circuits the emotion itself [Newsweek].
In the now-common cosmetic treatment, a doctor injects botulinum toxin, sold under the brand name Botox, under the skin. The toxin kicks in, temporarily paralyzing facial muscles, smoothing skin out, and making a person look less wrinkly as a result. That paralysis, however, seems to interfere with a known feedback loop, in which smiling adds to your happiness and frowning multiplies your sadness [LiveScience]. And tamping down a person’s emotions seems to interfere with the ability to read emotions in others. Says study leader David Havas: “Botox [also] induces a kind of mild, temporary cognitive blindness to information in the world, social information about the emotions of other people” [Discovery News].
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There’s your chronological age, the number that creeps depressingly upward with each passing birthday, and then there’s your biological age, associated with the condition of your body. In a study this week in Nature Genetics, a British team discovered a link between a particular genetic variation and people being several years older in their biological age.
Says study leader Nilesh Samani: “What we studied are structures called telomeres which are parts of one’s chromosomes. Individuals are born with telomeres of certain length and in many cells telomeres shorten as the cells divide and age” [Press Association]. Some people, however, are born with shorter telomeres to begin with, which sets them up to age faster, biologically speaking, and could put them at greater risk for age-related diseases.
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Researchers have long sought an answer to burning question of why women live longer on average then men (you know, other than the fact that, as Harry Belafonte puts it, “man smart, woman smarter“). Now a new study in Human Reproduction by Japanese researchers reinforces the argument that the fault lies in men’s genes, a conclusion they reached by taking males completely out of the picture.
They studied mice created with genetic material from two mothers, but no father. This was achieved by manipulating DNA in mouse eggs so the genes behaved like those in sperm [BBC News]. The scientists then implanted those sperm-behaving eggs into female mice, creating 13 “bimaternal” mice. On average, these fatherless mice lived a third longer than those conceived in the usual manner, according to study leader Tomohiro Kono.
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The naked mole rat is a species with a long list of peculiarities. The mole rat is about the same size as the more hirsute wild mouse, but lives seven times as long, sometimes reaching the ripe old age of 28. The creatures almost never poke their noses beyond the snug confines of their burrows and tunnels, and instead live out their lives underground in the dark. They’re also the only mammals who have a social structure that resembles an ants’ nest or beehive, where only one dominant female mates and reproduces.
Finally–and this is the part that most interests researchers–naked mole rats never get cancer.
A new study in the Proceedings of the National Academy of Sciences probed the mole rats’ robust good health, and determined how they beat cancer. The naked mole rat’s cells hate to be crowded, it turns out, so they stop growing before they can form tumors…. Normal human and mouse cells will grow and divide in a petri dish until they mash tightly against one another in a single, dense layer–a mechanism known as “contact inhibition.” Naked mole rat cells are even more sensitive to their neighbors, the researchers found. The cells stop growing as soon as they touch [ScienceNOW Daily News]. Researchers hope that the mechanism can one day lead to novel treatments for cancer, where cancerous cells won’t stop multiplying and form tumors.
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