Shape Shifter

 

(Photo: Cally Harper)

Tongues can do delightful and astonishing things. I am thinking of the way a frog fires its sticky tongue halfway across the universe to snag a passing insect (see below). Or how an alligator snapping turtle wriggles its tongue like a worm as a dinner invitation to fish. And now the Pallas’s long-tongued bat (Glossophaga sorcina) joins this elite club of astonishing animal tongue artists.

These bats, found from Argentina to northern Mexico, and sometimes into Arizona and New Mexico, have the fastest metabolism ever recorded in a mammal, says a 2007 study in the journal Nature. They burn half their body fat each day, and have to make up for it at night by consuming as much as 150 percent of their body weight in nectar from flowers. And of course, they have to do it on the wing. According to a study published today in the Proceedings of the National Academy of Science, the secret to its success is a remarkable ability to change the shape of its tongue into a hemodynamic—or blood-swollen—“nectar mop.”

When lead author Cally Harper, a doctoral candidate in biomechanics at Brown University in Rhode Island, began her study, specialists already knew that bats of this species have an unusual fringe of hair-like structures around the tip of the tongue.  They assumed these were useful for collecting nectar—but passively, like raking icing off a cake using your fingernails. Biologists also knew that these bats have enlarged blood vessels in their tongues. But they didn’t know what to make of them. Harper had a hunch that the two features might be connected, especially since …  Read the full article here.

Her Last Chance at a Baby (Body Eclectic–Part 1)

(Illustration: Stephanie Dalton Cowan)

This is a piece I wrote for the May issue of Smithsonian Magazine, about life on the human body.

Of all the cases Barbara Warner has faced as a pediatrician specializing in newborns, the one that sticks hardest in her mind involved a couple who had been trying for years to have children. Finally, in 1997, the woman was pregnant. She was in her mid-40s. “This was her last chance,” says Warner. Then, too soon, she gave birth to twins. The first child died at two weeks of respiratory failure, at the time the most common killer of preterm babies.

A week later—it happened to be Thanksgiving Day—Warner folded down the blanket on the surviving twin, and even now she draws in her breath at the memory. The baby’s belly was reddened, shining and so swollen “you could have bounced a nickel off it.”

It was necrotizing enterocolitis, or NEC, little known outside neonatal intensive care units, but dreaded there as a sudden, fast-moving bacterial inflammation of the gut. On the operating table, a surgeon opened the baby boy’s abdomen and immediately closed it again. The intestinal tract from stomach to rectum was already dead. Warner, in tears, returned the child to die in the arms of his shattered parents.

“It’s 15 years later, and there’s nothing new,” Warner says bleakly as she moves among her tiny patients, each one covered in tubes and bathed in soft violet light, in a clear plastic incubator. NEC is still one of the leading killers of preterm babies. But that may soon change, thanks to a startling new way of looking at who we are and how we live.

Over the past few years, advances in genetic technology have opened a window into the amazingly populous and powerful world of microbial life in and around the human body—the normal community of bacteria, fungi and viruses that makes up what scientists call the microbiome. It’s Big Science, involving vast international research partnerships, leading edge DNA sequencing technology and datasets on a scale to make supercomputers cringe. It also promises the biggest turnaround in medical thinking in 150 years, replacing the

Opening the Black Box of Human Health (Body Eclectic Part 2)

Relman (Photo: Lea Suzuki / San Francisco Chronicle / Corbis)

The modern microbiome era started in the late 1990s, when David Relman, an infectious disease physician at Stanford University, decided to get a sample of the microbes in his own mouth. It’s a simple process: A dentist scrapes a sort of elongated Q-tip across the outer surface of a tooth, or the gums, or the inside of a cheek. These samples typically look like nothing at all. (“You have to have a lot of faith in the invisible,” one dentistry professor advises.)

Back then, such samples normally went to a laboratory to be grown in a petri dish for analysis, a good way to study those microbes that happen to be at home in a petri dish. Relman had the bold idea of adding DNA sequencing as a way of seeing every living thing. In the years since, the cost of sequencing has plunged and taking swab samples from various neighborhoods of the body for DNA analysis has become the standard practice of microbiome research.

In the laboratory, each Q-tip sample ends up in one of 96 little wells on a plastic collection plate smaller than a paperback book. A technologist then puts the plate on a sort of paint shaker, with a pebble and some detergent in each well to break open the cell walls, the first step in extracting the DNA. The resulting liquid gets drawn up by a pipetter—imagine a device with eight tiny turkey basters in a row—and transferred to wells in a series of eight more collection plates, each step taking the sample closer to pure DNA. The finished product then goes to the sequencer, a countertop device that looks about as impressive as an automated teller machine married to a bar refrigerator. But what it tells us about our own bodies is astonishing.

It’s not just that there are more than 1,000 possible microbial species in your mouth. The census, as it currently stands, also counts 150 behind your ear, 440 on the insides of your forearm and any of several thousand in your intestines. In fact, microbes inhabit almost every corner of the body, from belly button to birth canal, all told more than 10,000 species. Looked at in terms of the microbes they host, your mouth and your gut are more different than a hot spring and an ice cap, according to Rob Knight, a microbial ecologist at the University of Colorado. Even your left and right hands may have only 17 percent of their bacterial species in common, according to a 2010 study.

But the real news is that

Foodie Gift Giving: A Stool Sample? (Body Eclectic Part 3)

How Our Microbes Keep Us HealthyThe public has also embraced the microbiome, beginning a few years ago when researchers at Washington University noticed a curious fact about obesity: Fat mice have more of a bacterial group called Firmicutes in their guts and thin mice have more Bacteroidetes. Feed the mice the same diet, and the ones with more Firmicutes extract more calories and lay on more fat. When the same differences showed up in humans, it seemed to explain the common complaint of many overweight people that they get fat just smelling food their skinny friends gorge on with impunity.

Such studies have stirred up remarkable enthusiasm in a subject matter most people would once have dismissed as yucky, gross or worse. It’s as if people suddenly loved Gulliver’s Travels for the passage where Jonathan Swift depicts a scientifically inclined student trying to return human excrement to the foods from which it originated.

This past winter, two rival efforts invited microbiome enthusiasts to submit their own fecal, oral, genital or skin samples for microbial analysis, and each raised more than $300,000 from crowd-funded donations typically under $100 apiece. The first effort, managed by Rob Knight’s Colorado lab and called American Gut, emphasized participation by top scientists in the field. Prevention magazine ranked the project’s $99 “map of your very own gut bacteria ecosystem” among its top 10 foodie gifts for the holidays. (For romantics, the $189 “Microbes for Two” package included analysis of a stool sample for both you and your partner. Or your dog.)

Microbiome excitement has spread to venture capitalists, who have so far invested in at least four start-ups with the aim of developing new microbiome-focused drugs and diagnostic tools. At Second Genome outside of San Francisco (motto: “The most important genome in your body may not be your own”), chief executive Peter DiLaura has nearly $10 million in seed money and a plan to get to clinical testing within three years for drugs targeted at common conditions like ulcerative colitis, where the micro­biome probably plays a causative role.

That timetable may seem optimistic, especially given that research on the first genome—that is, the human genome—has barely begun to produce the abundance of new therapies originally predicted. But at least in theory it ought to be easier to manipulate individual microbes. According to researchers in the field, several major drug companies working on diabetes and obesity now have

Killing Off Our Microbial Support System (Body Eclectic Part 5)

Blindly tinkering with the microbiome is, however, exactly what some researchers say we have been doing, willy-nilly, for more than 70 years, since the dawn of the antibiotic era. For Martin Blaser, a physician at New York University’s School of Medicine, one trend stands out: The typical child in the developed world now receives 10 to 20 courses of antibiotic treatment by the age of 18, often for conditions where these drugs do little or no good. “For two or three generations we’ve been under the illusion that there is no long-term cost to using antibiotics,” says Blaser, eyebrows rising over the tops of his wire-rimmed eyeglasses. It certainly hasn’t seemed like a cost for the child being treated, and only remotely for society at large (because excess use can lead to antibiotic resistance). But “you can’t have something this powerful,” says Blaser, “and change something as fundamental as our microbiome, at a critical time in development, and not have an effect.”

Though they have always known that antibiotics kill “good” bacteria as well as “bad,” doctors generally assumed the body’s microbial community was resilient enough to bounce back. But new studies show that the microbiome struggles to recover from repeated assaults, and may lose species permanently. Blaser suspects that diversity loss is cumulative, worsening from one generation to the next. He calls it “the disappearing microbiota hypothesis.” It’s like somebody played the piano solo with a two-by-four.

Along with the antibiotics, Blaser blames our obsession with cleanliness and antibacterial soaps and lotions. In addition, about 30 percent of American children are now born by Caesarean section. They start life without the microbiome they would normally have picked up passing through the mother’s birth canal, and some research suggests that this puts them at a disadvantage. Studies show that a diverse microbial community is essential to jump-start a baby’s immune system, establish a healthy digestive tract and even help

“There Is No Yuck Factor for People Who Are This Sick” (Body Eclectic Conclusion)

In a procedure room at Rhode Island Hospital in Providence, a gastroenterologist named Colleen Kelly sprays a little air freshener, says “Breathe through your mouth” and then opens a plastic container of donor material, delivered fresh this morning by a relative of today’s patient. Kelly mixes it into a half liter of saline solution, then shakes it up like a bartender mixing a mai tai. She draws the liquid off into a half-dozen syringes the size of handheld bicycle pumps, and then it’s time to wheel in the patient.

The idea of fecal transplants is not new. Veterinarians have long used them to treat livestock with digestive troubles. Human cases in the United States, though rare, date back at least to the 1950s. But the procedure has become more common recently because it seems to cure C. diff. infection. Janet O’Leary, a medical imaging technologist in Massachusetts, went to Kelly for the procedure last October. “I told my boyfriend what I was going to do,” she recalls, “and he said, ‘I absolutely don’t believe it. You’re making this up.’”

Her personal physician felt almost as horrified. “It’s considered fringe, and this is how medicine in America works,” O’Leary says. “It’s not a drug. Nobody’s making money off it. Yet. It’s not being pushed by a dozen companies. It’s just a natural way to get the normal flora back in your gut. My response is that there is no ‘yuck factor’ for people who are this sick.”

O’Leary had come down with C. diff. after a vacation trip on which she used a powerful antibiotic for turista. Back home, her doctor prescribed another round of the same antibiotic, and the problem just got worse. A different antibiotic followed, and then repeated courses of a third antibiotic. It got so bad O’Leary couldn’t go to work at her hospital. She became a patient instead. “This wasn’t getting better. It was pretty scary, and the doctors were saying

Fur, Feathers, and Pharmaceuticals

The pharmacist is in

House sparrows and finches pad their nests with nicotine-laced cigarette butts to reduce mite infestations.  Wood ants do the same sort of thing with an antimicrobial resin from conifer trees, preventing microbial growth in the colony. Monarch butterflies infected with parasites protect their offspring from that irritating fate by laying their eggs on anti-parasitic milkweed.  (Well, if they can find any milkweed.)   And baboons exploit a well-stocked medicine chest, treating parasitic infections with the fruit of the Balanites tree, halting bouts of diarrhea by eating leaves from the Sodom apple, and relieving menstrual cramps by munching on the leaves of the candelabra tree.

“When we watch animals foraging for food in nature, we now have to ask, are they visiting the grocery store or are they visiting the pharmacy?” says Mark Hunter, co-author of an article on “Self-Medication in Animals,” published online today in the journal Science. “We can learn a lot about how to treat parasites and disease by watching other animals.

“Perhaps the biggest surprise for us was that animals like fruit flies and butterflies can choose food for their offspring that minimizes the impacts of disease in the next generation,” says Hunter, can ecologist at the University of Michigan. “There are strong parallels with the emerging field of

Fraudulent Food Labeling: It’s Not Just the Fish.

Snacking on mountain zebra?

It’s amazing, and sometimes dismaying, what you can find out with DNA.  We all know that the fish being sold by most retailers and restaurants may not be as labeled:  They price it as red snapper, but it’s really just tilapia.

Now it turns out the same thing may be happening with at least one form of red meat.

When I travel in southern Africa, I routinely pick up a bag of biltong, dried wild meat, to snack on as I drive.  It’s usually labeled wildebeest, kudu, or even giraffe.  But now it turns out it may be something entirely different, even including an endangered species.  Here’s the report:

Want to know what you are eating? DNA barcodes can be used to identify even very closely related species, finds an article published in BioMed Central’s open access journal Investigative Genetics. Results from the study show that the labelling of game meat in South Africa is very poor with different species being substituted almost 80% of the time.

In South Africa game meat biltong (air dried strips) is big business with over 10,000 wildlife farms and is supplemented by private hunting. This meat is considered to be ‘healthier’ than beef because it is lower in fat and cholesterol and perceived to be lower in additives.

Using mitochondrial COI DNA barcoding and cytb sequencing, researchers analysed samples of game meat from supermarkets, wholesalers and other outlets and compared them to known samples and library sequences. From 146 samples over 100 were mislabelled.

All the beef samples were correct, but for the most badly labelled case 92% of

Score Another Round for Mosquitoes

The first time I used the insect repellent DEET while reporting a story was in the late 1980s, in the rain forest in eastern Peru.  I remember it because laptop computers were a new phenomenon then.  They typically cost about $3500 (about $5600 in today’s money)  and a biologist on that trip had boldly brought hers  into the field.   She also used DEET, generally regarded as the most effective protection against mosquitoes, and thus against malaria, yellow fever, dengue fever, and so on.  Unfortunately, DEET also melts plastic.  She didn’t realize this until the keys on her laptop became gooey as asphalt at noon on a hot summer day.

So now comes the news that the whole idea of DEET leaves mosquitoes totally bored.  After the first few hours of revulsion, they just ignore it and zoom in for the blood meal.

Happily, lower tech methods still work:

 

Here’s the report from the Public Library of Science:

 Feb. 20, 2013 — Mosquitoes are able to ignore the smell of the insect repellent DEET within a few hours of being exposed to it, according to research published February 20 in the open access journal PLOS ONE by James Logan, Nina Stanczyk and colleagues from the London School of Hygiene & Tropical Medicine, UK.

Though most insects are strongly repelled by the smell of DEET, previous studies by Logan’s research group have shown that some flies and mosquitoes carry a genetic change in their odor receptors that makes them insensitive to this smell. The new results reported in the PLOS ONE study uncover a response in mosquitoes based on short-term changes, not genetic ones.

“Our study shows that the effects of this exposure last up

Shut the Damned Door! Those Are Dragons Out There

This comes in from CBS News by way of photographer Mark Moffett.  (He and I have been sometime-colleagues at National Geographic, and once spent a couple of weeks together hunting tarantulas in Peru.):

Last year we visited the office HQ at Komodo National Park, dragons resting outside the open door, and noticed that the head ranger sitting at the front desk had a badly scarred leg and arm. Dragons had swarmed into the office two years before and tried to kill him. We were amazed he was still working there, at the same desk in the same room. Guess what…

Komodo dragon wanders into office, attacks two wildlife park employees in Indonesia

CBS NEWS–JAKARTA, Indonesia A park official says two people have been hospitalized after being attacked by a giant komodo dragon that wandered into the office of a wildlife park in eastern Indonesia.

An official at Komodo National Park, Heru Rudiharto, said Wednesday the 6 1/2-foot-long komodo dragon attacked a park ranger after