Fishy Findings and Kinky Sex

Findings Log / by The Editors /

In this week's Findings Log, we examine new research on Earth’s magnetic fields, confusion about what constitutes “sex,” frogs that change sex, and more.

Findings Log is a look at some of the research and academic papers that have recently caught the eyes of Seed’s editors, Lee Billings, Greg Boustead, Veronique Greenwood, Joe Kloc, Evan Lerner, and Maywa Montenegro. For more recommended reading and occasional insights, follow them on Twitter.

Read the paperFriedman et al. Science February 19, 2010

Somethin’ Fishy in the Fossil Record
Filter-feeder whales and other plankton-munching species are some of the most prominent denizens of the deep, but for much of the Mesozoic Era, between 248 million to 65 million years ago, plankton-eaters disappeared from the fossil record. Or so it seemed. Now paleontologists have taken a second look at a number of specimens that were languishing in collections (as well as a newly unearthed sample). They’ve found that giant plankton-eating fish were in fact roaming the oceans during that era, sharing the Earth with dinosaurs. This group of fish, which could grow up to 9 meters long, have been hard to spot in the fossil record because their fine bones are easily scattered, but when researchers began to clean off a skull, they found the distinctive gaping maw of a plankton feeder (read about the skull’s discovery here). Such creatures would swim along with their cavernous mouths ajar, filtering water through their gill arches and extracting microorganisms. Scientists had long wondered, the team wrote in Science, why marine reptiles, which grew to gigantic sizes and evolved new feeding methods during this period, had not taken up planktivory. It now seems the reason was that this particular niche in the ecosystem was already occupied by a large and uncannily endowed neighbor.—NG

Read the paperContreras-Vidal et al. Journal of Neuroscience March 3, 2010

Decoding the Mind
Scientists have spent the past decade making great strides in the field of brain-computer interfaces (BCI). By attaching a series of electrodes to a human brain, researchers can feed neural impulses from the brain into a computer to allow the direct control of robotic devices. One major downside, of course, is that the electrodes through which the subject controls these robotic devices have to be placed directly on the brain. This drawback had been in large part considered unavoidable, as electrodes placed outside the skull were thought to gather insufficient information to successfully operate a mechanical device. But in a study published last week in The Journal of Neuroscience, researchers were able to use an array of 34 electrodes attached to test-subjects’ scalps to deduce the subjects’ 3-dimensional hand movements. The importance of this work is clear: It may help patients who have lost a limb to operate a replacement robotic prostheses with their brain. And with a bit of wishful thinking, one can imagine that someday researchers may be able to read information from the brain without even having to attach anything to the scalp at all. In the simplest terms, one can imagine good, old-fashioned, toys in the back-pages-of-Boy’s Life magazine-style mind control devices.—JK

Read the paperHayes et al.
PNAS March 1, 2010

When a He-Frog Becomes a She
“I’m not saying it’s unsafe for humans. All I’m saying is it makes hermaphrodites of frogs.” That was researcher Tyrone B. Hayes speaking to a New York Times reporter back in 2002, after his team at the University of California-Berkeley found that atrazine, a commonly used weed killer in North America, caused frog cells to churn out a potent hormone-converting chemical. Now, eight years later, Hayes’ group is back with some results in actual amphibians: They’ve found that atrazine can indeed turn a he-frog all the way into a she. Reporting this week in PNAS, the team describes how atrazine-exposed males were “both de-masculinized (chemically castrated) and completely feminized as adults.” Ten percent of the males who turned female, the researchers discovered, could even copulate with normal males and produce viable eggs. About 36 million kilograms of atrazine are applied to farm fields each year in the US alone, where it seeps into ground and surface water, and can contaminate otherwise pristine habitats. Some studies have found traces of the potent herbicide more than 1000 kilometers from where it was originally sprayed. Whether atrazine’s effects will translate to humans isn’t clear—amphibians have thinner skins and can spend much of their lives fully immersed in polluted water. But one thing is certain: This is bad news for frogs. For more on how thick-skinned humans affect thin-skinned amphibians, check out The Case of the Deviant Toad, on view at Royal Institution of Great Britain beginning March 15.—MM

Read the paperVijay-Kumar et al. Science March 4, 2010

Do These Microbes Make Me Look Fat?
You know the type. The one with the “fast metabolism”: the person who can snarf hamburgers and pizza washed down with milkshakes and beer without seemingly putting on the pounds. Then there are those who make concerted efforts to eat sensibly, yet still tend to gain weight. The underlying genetic basis of a condition known as “metabolic syndrome”—a host of obesity-related problems that can lead to diabetes and heart disease and is estimated to affect nearly 25 percent of the US population—has perplexed doctors and scientists for decades. Results of a new study, however, suggest that the answer may lie with the microbes that live in our guts. Researchers reported in last week’s Science that mice lacking a critical immune-system protein (TLR5) exhibit metabolic syndrome as well as an abnormal microbial community in their intestines. When the team transferred these microbes into other mice, the otherwise-healthy mice also exhibited symptoms characteristic of metabolic syndrome, including hypertension and insulin resistance. The researchers also sequenced some of the microbes’ genetic material, taken from the guts of mutant mice, enabling them to identify a specific set of bacterial species whose abundance was off-balance as a result of the loss of TLR5. The findings lead the researchers to conclude that deficiencies in the immune system must alter the microbial environment in the gut, which in turn disrupts insulin-receptor signaling, ultimately leading to the conditions that drive metabolic syndrome.—GB

Read the paperTarduno et al. Science March 5, 2010

The Magnetic Biosphere
As the only planet in the entire universe known to harbor life, the Earth seems rather special. But what are the factors that make it so conducive to life being here in the first place? An abundance of liquid water and atmospheric oxygen is high on the list, but one underappreciated contributor to our planet’s hospitality is its intrinsic magnetic field, which shields us from dangerous high-energy solar radiation. In the latest issue of Science, an international team of researchers reports that the Earth’s magnetic field existed 3.45 billion years ago, and was some 50 to 70 percent weaker than it is today. The team estimated the age and strength of Earth’s ancient magnetic field by measuring the relic magnetism of nanoscale grains of iron found within pristine samples of continental crust. This time period, roughly a billion years before high levels of oxygen accumulated in the atmosphere, and 450 million years after the Earth was bombarded and sterilized by debris leftover from the solar system’s formation, is a good bet for life’s genesis. How life could have emerged during this era has been a long-standing puzzle for researchers: Back then, the Sun likely was less luminous but emitted x-rays and solar winds that could have destroyed cells and damaged Earth’s atmosphere. Proof that a sufficiently strong global magnetic field existed to protect against some of these effects helps clarify life’s probable origins on Earth, and also could aid our search for habitable planets around certain low-mass stars.—LB

Read the paperSanders, et. al., Sexual Health February 2010

What We Talk about When We Talk about “Doing It”
The Kinsey Institute at the University of Indiana is well known for its research on human sexual behavior—its founder, Alfred Kinsey, literally wrote the books on the subject: Sexual Behavior in the Human Male and Sexual Behavior in the Human Female. In the 40s and 50s, those two groundbreaking studies helped set a baseline for understanding the prevalence of sexual practices, but a new study from the Kinsey Institute suggests sex researchers need to be more careful in how they structure future investigations. A survey of about 500 Indiana residents, aged 18 to 96, showed no consensus over what the phase “had sex” means. While there was no significant difference between men’s and women’s definition, the study showed that more subjects in the oldest and youngest age groups did not think practices such as oral or anal sex “counted” as sex. These findings are particularly relevant in constructing studies of STD transmission, as subjects are often asked the number of partners they have had sex with, or whether they have had sex with partners of their own gender. Without explicit definitions on the part of researchers, subjects answering truthfully could provide answers that don’t mesh with those of other subjects or researchers’ expectations.—EL

Originally published March 9, 2010


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