January 17, 2013
Barnacles are renowned for the size of their penises. The strange-looking creatures, which live inside shells glued to rocks or boat hulls, have outsized members that are among the longest in the animal kingdom relative to their size—their penises can stretch up to eight times their body length. Barnacles can even change the size and shape of their penis depending on the amount of wave action in their ocean real estate.
Perhaps this is why the sex lives of barnacles have long been of interest to scientists—luminaries such as Darwin, among others, closely studied the subject. Until recently, though, scientists recognized just two methods of reproduction in the species, and both left unanswered questions.
Pseudo-copulation, in which the penis enters a neighboring barnacle’s shell and deposits sperm, has been observed, but this method restricts them to reproducing only with others in their vicinity. Scientists have also observed that individual barnacles with no neighbors can reproduce, and they assumed this was accomplished through self-fertilization, because most barnacles are hermaphrodites.
Now, though, researchers at the University of Alberta, Edmonton and Bamfield Marine Sciences Centre in British Columbia seem to have discovered a new reproduction method while studying the gooseneck barnacle (Pollicipes polymerus), upending more than 150 years of theory. Previously, the researchers had noticed that in other studies of the gooseneck barnacle, self-fertilization was never observed. They also saw sperm leaking from the barnacles in the field, which made them consider the possibility that barnacles could pick up sperm from the water.
In the study, the scientists collected gooseneck barnacles—both isolated and in pairs—along with their fertilized eggs from Barkley Sound in British Columbia to take back to the lab so they could genetically analyze the paternal combinations. The DNA of the fertilized eggs revealed that none of the isolated barnacles had produced embryos through self-fertilization—so one hundred percent of these eggs must have been fertilized by capturing sperm from the water.
Surprisingly, though, even some of the barnacles that resided in pairs had embryos that had been fertilized with sperm from a non-neighbor. This left one possibility: that the barnacles release their sperm into the ocean and let the water carry it to distant neighbors. This type of fertilization has been observed in other marine animals that can’t or don’t move, but it was always assumed that barnacles can’t reproduce in this way.
The authors point out that this mode of reproduction may be unusually common in this particular barnacle species because of the small size of their penis—but the fact that this phenomenon occurs at all opens the door to re-thinking the biology of these creatures. Other barnacle species might also have more mating options, with fathers coming from farther afield than previously thought.
Learn more about the ocean from the Smithsonian’s Ocean Portal.
January 15, 2013
For years, when museums, textbooks or other outlets attempted to illustrate what a particular ancient human skeleton would have looked like in the flesh, their method was admittedly unscientific—they basically had to make an educated guess.
Now, though, a group of researchers from Poland and the Netherlands has provided a remarkable new option, described in an article they published in the journal Investigative Genetics on Sunday. By adapting DNA analysis methods originally developed for forensic investigations, they’ve been able to determine the hair and eye color of humans who lived as long as 800 years ago.
The team’s method examines 24 locations in the human genome that vary between individuals and play a role in determining hair and eye color. Although this DNA degrades over time, the system is sensitive enough to generate this information from genetic samples—taken either from teeth or bones—that are several centuries old (although the most degraded samples can provide information for eye color only).
As a proof of concept, the team performed the analysis for a number of people whose eye and hair color we already know. Among others, they tested the DNA of Władysław Sikorski, a former Prime Minister of Poland who died in a 1943 plane crash, and determined that Sikorski had blue eyes and blonde hair, which correctly matches color photographs.
But the more useful application of the new method is providing new information. “This system can be used to solve historical controversies where colour photographs or other records are missing,” co-author Manfred Kayser, of Erasmus University in Rotterdam, said in a statement.
For example, in the paper, the researchers analyzed the hair and eye color for a female skeleton buried in the crypt of a Benedictine Abbey near Kraków, Poland, sometime between the 12th and 14th centuries. The skeleton had been of interest to archaeologists for some time, since male monks were typically the only people buried in the crypt. The team’s analysis showed that she had brown eyes and dark blond or brown hair.
The team is not sure yet just how old a skeleton has to be for its DNA to be degraded beyond use—the woman buried in the crypt was the oldest one tested—so it‘s conceivable that it might even work for individuals who’ve been in the ground for more than a millenium. The researchers suggest this sort of analysis could soon become part of a standard anthropological toolkit for evaluating human remains.
January 14, 2013
Last summer, a study published in the Proceedings of the National Academy of Sciences sparked a new round of worries about the dangers of smoking pot—especially for those who start smoking at younger ages. The study found that consistent marijuana use gradually eroded cognitive functioning and IQ, and with the legalization of recreational marijuana in Colorado and Washington, it’s made an appearance in a number of articles arguing that legalized pot poses a serious health hazard. Today, though, a new study published in the very same journal—and using the very same data set—suggests that the case against marijuana is a little less cut-and-dry.
Ole Røgeberg, a researcher at the Frisch Centre for Economic Research in Norway, analyzed the same survey results and found that the declines in cognitive abilities could be entirely attributed to socioeconomic factors. As a result, “the true effect” of marijuana use, he argues, “could be zero.”
Røgeberg is careful to note that his reinterpretation of the data doesn’t entirely discredit the original study, but he does write that its “methodology is flawed and the causal inference drawn from the results premature.”
Both the new and old studies draw upon a data set of 1,037 individuals from Dunedin, New Zealand, who were followed from their birth (either in 1972 or 1973) until they turned 38. At the ages of 18, 21, 26, 32 and 38, each of them were interviewed and scored for marijuana use. The original study found that IQ decline increased proportionately with cannabis dependence—especially for those who started smoking earlier on—and the authors concluded that using the drug was the cause of the decline.
Røgeberg, though, dug a little deeper into the data. He found those who started using marijuana during adolescence were disproportionately likely to have poor self-control and conduct problems in school—both factors that are themselves correlated with low socioeconomic status. In particular, members of the study with these traits were more likely to come from a Maori background, a group indigenous to New Zealand that has much higher unemployment, poverty and incarceration rates than the country’s population as a whole.
Numerous other studies have shown that low socioeconomic status adolescents are more likely to experience steeper IQ declines during adulthood. (Researchers hypothesize this is a result of being exposed to less intellectually stimulating environments.) As a result, Røgeberg wondered, could socioeconomic factors explain the IQ declines originally attributed to marijuana?
In his simulation, he tested whether socioeconomic environmental factors (dropping out of school, being exposed to less stimulating environments, and so on) could conceivably drive the same IQ declines reported in the group without turning to marijuana as an explanation. His statistical analysis found that these other factors could indeed completely account for the cognitive declines observed.
For support, he also points to a 2002 Canadian study that also asked whether long-term marijuana use impacted IQ, but with data entirely from middle-class survey participants. That paper found that IQ only decreased for current cannabis users, and when even heavy users stopped smoking, their IQ rebounded. Since that study largely excluded socioeconomic factors and did not find a permanent trend, he feels that it supports his argument that such factors play a major role.
January 11, 2013
We’re all familiar with the concept of a breathalyzer—a device that indicates someone’s blood alcohol content by precisely analyzing his or her breath. Because the breakdown of alcohol produces predictable quantities of various gases, these machines are reliable enough to be used by law enforcement to declare a driver, say, as legally intoxicated.
Recently, a group of researchers from the University of Vermont saw this idea and had another: What if a device could be designed to detect a chemical signature that indicates a bacterial infection in someone’s lungs? Their result, revealed yesterday in the Journal of Breath Research, is a quick and simple breath test—so far used only with mice—that can diagnose infections such as tuberculosis.
In their study, they focused on analyzing volatile organic compounds (VOCs) in mouse breath to distinguish between different strains of bacteria that were infecting the animals’ lungs. They hypothesized that these bacteria produce VOCs not normally present in the lungs, thus allowing their test to differentiate between a healthy animal and a sick one.
Initially, a number of the mice were infected with either Pseudomonas aeruginosa or Staphylococcus aureus—both common types of bacteria in either acute and chronic lung infections—and their breath was tested 24 hours later. The researchers used a technique called “secondary electrospray ionization mass spectrometry” (a name that, admittedly, requires quite a mouthful of expelled air), which can detect VOC quantities of as little as a few parts per trillion.
Their test was a success: There was a significant difference between the chemical signatures of healthy and infected mouse breath, and their test was even able to indicate which type of bacteria were the source of the infection.
Although the concept has only been used on mice so far, the researchers think that you could someday be blowing into a bacterial breathalyzer as part of your routine medical exam. Their prediction stems from the fact that the approach offers several advantages over conventional ways of detecting bacterial infections in the lungs.
“Traditional methods employed to diagnose bacterial infections of the lung require the collection of a sample that is then used to grow bacteria,” said Jane Hill, one of the paper’s co-authors, in a statement. “The isolated colony of bacteria is then biochemically tested to classify it and to see how resistant it is to antibiotics.”
This process can take days and sometimes even weeks just to identify the type of bacteria. By contrast, she said, “Breath analysis would reduce the time-to-diagnosis to just minutes.”
This type of test would also be less invasive than current methods. Thus, for patients suffering from bacterial infections…a breath of fresh air.
January 10, 2013
Another one of the products of science that seem too amazing to be true: Researchers at MIT have invented the technological equivalent of Mexican jumping beans. As seen in the video above, they’ve created polymer films that act like artificial fast-twitch muscles, spontaneously curling up and dancing around in an eerily life-like way.
The polymer sheets are specially designed to rapidly expand when they come into contact with water, and contract when they expel it. Thus, by placing the sheets on a slightly moist surface, Mingming Ma and colleagues were able to make them dance around completely on their own. They published the details of their invention today in a paper in Science.
Although the polymers are simply pretty cool to watch, the researchers had a practical application in mind when they developed them: producing electricity. When they covered the sheets with a piezoelectric polymer that generates electricity from pressure and stress (30 seconds into the video), and wired it to a capacitor, they were able to store minute amounts of energy expelled by all that folding and flipping.
They say the sheets produced bursts of electricity peaking at about 1 volt. Since the polymer can also be stimulated by the mere presence of water vapor in the air—and not just water on a table—they speculate that these types of thin water-powered sheets could someday be harnessed to provide electricity for small ubiquitous objects, like environmental sensors.
“With a sensor powered by a battery, you have to replace it periodically,” lead author Ma said in a statement. “If you have this device, you can harvest energy from the environment so you don’t have to replace it very often.”
It’s even possible, they suggest, that this type of material could be sewn into clothing, in order to harvest electricity from the sweat that evaporates off your body. ”You could be running or exercising and generating power,” said Liang Guo, a co-author.
The sheets are made from a pair of polymers: one called polypyrrole, which serves as a rigid supporting matrix, and another called polyol-borate, a flexible gel substance woven throughout that does the expanding and contracting when in contact with water. The researchers were inspired by the configuration of animal muscles (including our own), which are made from a rigid network of collagen fibers woven with elastic microfibrils.
In the video above, when the superthin film comes in contact with minute amounts of moisture, the bottom layer absorbs water and quickly curls upward. Then, once the bottom is lifted off the table and comes into contact with the air, the moisture evaporates off of it, and it flattens back out.
The team even tested the strength of this fascinating polymer construction, using clamps and heavy objects, to see just how much weight the polymer sheets could lift when stimulated. They found that a 25-milligram piece of film could lift a stack of glass slides 380 times heavier than itself and produce up to 27 megapascals of pressure—80 times more than the amount of pressure generated by typical mammalian muscle. Pretty amazing for a paper-thin sheet of film.