Cockroach Brains May Hold New Antibiotics?

Cockroaches may make your skin crawl, but the insects—or, to be exact, theirbrains—could one day save your life.

That's because the central nervous systems of American cockroaches produce natural antibiotics that can kill off bacteria often deadly to humans, such as methicillin-resistantStaphylococcus aureus(MRSA) and toxic strains ofEscherichia coli,scientists said this week.

Three species oflocusttested so far also have the same bacteria-killing molecules in their tiny heads.

The findings suggest that theinsect world—which makes up 80 percent of all animals on Earth—may be teeming with new antibiotics, said study co-author Simon Lee of theUniversity of Nottinghamin the U.K.

Such a discovery is crucial, because scientists are scrambling to combat strains of several infectious diseases, including MRSA andE. coli, that are resistant to traditional antibiotics, Lee said.

(Related:"Sharks Carrying Drug-Resistant 'Bacterial Monsters.'")

"It's a promising new lead. We are looking in an unusual place, and to my knowledge no one else is looking there,"Lee said.

"That's what we need in terms of {finding new} antibiotics, because all the usual places"—such as soil microbes, fungi, and purely synthetic molecules—"have been exhausted."

(Also see:"Blockbuster Ocean Drugs on the Horizon?")

Insect Brains Have"Clever Defense"Against Bacteria

Lee and colleagues dissected the tissues and brains of cockroaches—which"smell as bad as they look,"Lee said—and locusts in the lab.

(Read more abouthow locust brains switch on swarming behavior.)

The team tested nine separate types of antibacterial molecules found in the insects' brains and discovered that each molecule is specialized to kill a different type of bacteria.

This"very clever defense mechanism"allows the bugs to survive in the most dirty of domains, Lee said.

The scientists found the bugs had antibiotics only in their brain tissue, the most essential part of the body, he added.

A bug might live with an infected leg, for instance, but a brain infection would almost certainly be fatal.

Insect-brain drugs for humans are still years away, Lee said, but there's one hopeful glimmer: When the team added the insect antibiotics to human cells in the lab, there were no toxic effects.

Preliminary findings on antibiotics in bug brains were presented at theSociety for General Microbiologymeeting held this week at the University of Nottingham.

National Geographic News

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"Lost" Fox Subspecies Found via Saliva Analysis

Long seen as regionally extinct, the Sierra Nevadared foxhas been rediscovered in the mountains of centralCalifornia, thanks to a remote camera, a bag of chicken, and saliva analysis.

The discovery gives conservationists hope that the fox—listed as threatened by California—may just outfox extinction overall, scientists say.

The Sierra Nevada red fox subspecies hadn't been seen in central California since the 1990s and was considered gone from the area. Only one other population of Sierra Nevada foxes are known, farther north in theLassen Peak region (see map).

ButU.S. Forest Serviceofficials suspected photographs taken by a trail camera near the Sierra Nevada mountains'Sonora Pass (see map)in August had captured a Sierra Nevada red fox gnawing on a"bait bag"of chicken scraps.

Researchers at the University of California, Davis, ran DNA tests on saliva samples from the bag, and sure enough, the spit confirmed the fox as a Sierra Nevada. Testing saliva is"not uncommon,"saidBen Sacks, director of the Canid Diversity and Conservation Unit of the Veterinary Genetics Laboratory.

"We thought they were gone,"Sacks added."We were wrong."

(Also see"'Extinct' Booby Exposed—Found 'Masked,' Using Alias.")

Knowing there are two holdout populations of the subspecies"multiplies our reasons for optimism,"Sacks added.

It"tells us not only are they not extinct, but now we're hedged,"he said."If something were to happen to one of those {populations}, we have another to draw from."

Sly Fox Little Studied

Since 2006, Sacks has been studying red foxes in California—often joining the hunt for the Sierra Nevada fox. Even when he's hiking,"if I find fox-size feces at the right elevation, I pick it up and do the analysis,"he said.

His genetic research, for instance, has revealed that many of the red foxes in the western U.S. are actually descendants of native Alaska and eastern U.S. foxes that were introduced in the 20th century.

But still, very little is known about the elusive Sierra Nevada subspecies—so little, in fact, that no one knows its exact population or why it's declining, Sacks said.

Sacks suspects the animals have escaped human detection in part because biologists' surveys are done at lower elevations—Sierra Nevada red foxes generally keep to the hig mountains.

The new discovery"tells us we need to take them seriously,"he said.

"We need some resources to study these guys and to find out how many are out there"and to"figure out how to protect them and ensure their persistence into the future."

forNational Geographic News

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"Whispering" Bat Evolved to Trick Prey

Meet the barbastelle bat, the world's first known moth whisperer.

The European bat has lowered its voice to evade detection by some moth species, allowing the mammal to swoop in for the kill, new research shows.

To help"see"in the dark, most bats echolocate, sending out sound waves and listening for echoes bouncing off objects, including prey.

(Related:"Early Bats Flew First, Developed 'Sonar' Later.")

Moths with ears—a feature that evolved independently in several moth species—can hear the bat calls and avoid the predators. Some species, such as tiger moths, evenuse ultrasonic clicks to"jam"a bat's sonar.

Yet one species of bat, the barbastelle, has evolved a whispering counterstrategy to outwit the eared moths—an unusual occurrence in nature, said study leader Holger Goerlitz, a biologist at theUniversity of Bristolin the United Kingdom.

"Evolution is putting larger pressure on prey to evolve adaptations to win against the predator,"Goerlitz said,"so therefore it's rare when you find cases in nature when a predator is winning in the arms race."

Unlocking the Bat Whisper

Before the study, the researchers had noticed that barbastelle bats are particularly proficient hunters. To find out why, the scientists would need to find out what exactly the bats hunt, so Goerlitz's team ran a genetic analysis of barbastelle feces.

The results showed the bat ate mostly moths with ears, such as the large yellow underwing moth.

The scientists then went out into the night to find out how well eared moths can detect the barbastelle bat's sonar.

At a site in southern England, the team attached a small electrode to the auditory nerve of a captured yellow underwing moth kept on the ground. The electrode recorded when the nerve was activated by a passing bat's echolocation call.

Simultaneously, the researchers recorded with microphones the echolocation calls of several flying barbastelles, which allowed the team to calculate where in space the sound had originated. For comparison, the team also recorded echolocation calls of a related bat species, Leisler's bat.

(Related:"Bats Use Magnetic 'Compasses' to Navigate, Study Says.")

Later, in the lab, the scientists pieced together when the moth's auditory nerve had been firing in relation to an incoming echolocation call.

The results showed the barbastelle can get as close as 11 feet (3.5 meters) to the grounded moth without being detected—most eared other moths can hear bats as far away as 100 feet (30 meters), according to the study.

Further analysis of the echolocation calls revealed that the barbastelle's calls are up to a hundred times fainter than those of other bats. (Interactive:Hear tropical bat calls.)

Bat Whispers Provide Exclusive Food Source

The bats' whispering is something of a disadvantage, since it effectively limits their"vision,"Goerlitz noted.

"All of the other bats have a large call that travels far, {like} a bright torch,"he said, but the barbastelle bats' sonar is like"a candle, only 'illuminating' the area just around them."

Yet this specialized ability also means the barbastelle has a corner on the eared-moth market, since non-whispering bats generally can't catch the insects.

Will the moth develop a counter-counterstrategy to the whispering? Unlikely, Goerlitz said. If the moth becomes even more sensitive to noises, the fragile insect might become too disturbed by innocuous sounds, such as wind and rustling leaves, he said.

So for now it's bat 1, moth 0.

The bat-"whispering"study will appear September 14 in the journalCurrent Biology.

National Geographic News

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Pictures: Crab Swarms Overtake Island—Mystery Solved

Migrating Christmas Island red crabs congregate on a beach in theAustralianterritory ofChristmas Island (map)in an undated picture.

A new study solves a longstanding mystery surrounding the crabs: how the the normally sedentary species has the stamina to"undergo one of the most arduous migrations on Earth,"in the words of study co-author Lucy Turner. 

When the wet season blows into Christmas Island (map)each year, millions of Christmas Island red crabs hike for several days, from a high rain forest plateau down to Indian Ocean beaches, where the crabs mate in burrows.

"It's an amazing feat—going from not being able to exercise for more than ten minutes to walking for several miles,"said Turner, a biologist at theUniversity of Bristolin the United Kingdom. 

But by sampling circulatory fluid—the equivalent of blood—from migrating crabs, Turner and colleagues discovered that a surge in the crustacean hyperglycemic hormone works with glucose, an energy-producing sugar, to fuel the epic trek. 

(See"World's Longest Migration Found—Two Times Longer Than Thought.")

The crab's endocrine system also stockpiles enough sugar to allow the crabs to return to their forest homes, Turner added.

Study published in the September issue of theJournal of Experimental Biology.

—Christine Dell'Amore

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Tarzan Chameleon Found in Tarzan Forest, Near Tarzanville

There's a new, scalier lord of the jungle: Tarzan the chameleon.

Five-inch-long (13-centimeter-long)Calumma tarzanwas found recently in a tiny patch of forest on the vast African island ofMadagascar, a new study says.

The new species' name has multiple roots. For one thing, the chameleon's habitat—in what locals call the Tarzan Forest—is near the village formerly known as Tarzanville (recently renamed Ambodimeloka).

For another, the team thought naming the new species after the vine-swinging"ape man"might be a good way to"promote the conservation of this species and of course of the forest that it's living in,"according to study leader Philip-Sebastian Gehring, an evolutionary biologist at theTechnical University of Braunschweigin Germany. (SeeMadagascar pictures.)

After all,"Tarzan stands for a jungle hero and fighting for protecting the forest,"Gehring said.

(Related:"Lemur Forests Pillaged by 'Gangs' as Madagascar Reels.")

Unique Snout Gave Tarzan Chameleon Away

The Tarzan chameleon was found on a 2009 night survey in eastern Madgascar, which lies off the east coast of mainland Africa.

Scientists immediately recognized thereptileas unique from other chameleons, due to its flat, spadelike snout, Gehring said.

Though the species' numbers are unknown, Gehring and colleagues suspect the Tarzan chameleon will be added to the ranks of critically endangered species on theInternational Union for Conservation of Nature's Red List of Threatened Species.

(See relatedpictures:"Over 200 New Amphibians Found in Madagascar.")

Tarzan Forest Fragmented

Rampant deforestation—which has accelerated throughout Madagascar since a 2009 political coup—has turned the chameleon's habitat into a patchwork of isolated forest fragments, some no bigger than a soccer field. (See"Madagascar's Logging Crisis: Separating Myth From Fact.")

Combined, the fragments account for just about four square miles (ten square kilometers), Gehring said.

Even so, the team found up to 60 chameleons in one fragment alone, suggesting the new species can survive in the remaining pockets—and that the Tarzan chameleon could still come out swinging.

Tarzan-chameleon study published August 20 in the journalSalamandra.

National Geographic News

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Evolution in Action: Lizard Moving From Eggs to Live Birth

Evolution has been caught in the act, according to scientists who are decoding how a species ofAustralianlizard is abandoning egg-laying in favor of live birth.

Along the warm coastal lowlands ofNew South Wales (map), the yellow-bellied three-toed skink lays eggs to reproduce. But individuals of the same species living in the state's higher, colder mountains are almost all giving birth to live young.

Only two other modernreptiles—another skink species and a European lizard—use both types of reproduction. (Related:"Virgin Birth Expected at Christmas—By Komodo Dragon.")

Evolutionary records shows that nearly a hundred reptile lineages have independently made the transition from egg-laying to live birth in the past, and today about 20 percent of all living snakes and lizards give birth to live young only.

(See"Oldest Live-Birth Fossil Found; Fish Had Umbilical Cord.")

But modern reptiles that have live young provide only a single snapshot on a long evolutionary time line, said study co-authorJames Stewart, a biologist at East Tennessee State University. The dual behavior of the yellow-bellied three-toed skink therefore offers scientists a rare opportunity.

"By studying differences among populations that are in different stages of this process, you can begin to put together what looks like the transition from one {birth style} to the other."

Eggs-to-Baby Switch Creates Nutrient Problem

One of the mysteries of how reptiles switch from eggs to live babies is how the young get their nourishment before birth.

Inmammalsa highly specialized placenta connects the fetus to the ovary wall, allowing the baby to take up oxygen and nutrients from the mother's blood and pass back waste. (See relatedpictures of"extreme"animals in the womb.)

In egg-laying species, the embryo gets nourishment from the yolk, but calcium absorbed from the porous shell is also an important nutrient source.

Some fish and reptiles, meanwhile, use a mix of both birthing styles. The mother forms eggs, but then retains them inside her body until the very last stages of embryonic development. (Related:"Dinosaur Eggs Discovered Inside Mother—A First.")

The shells of these eggs thin dramatically so that the embryos can breathe, until live babies are born covered with only thin membranes—all that remains of the shells.

This adaptation presents a potential nourishment problem: A thinner shell has less calcium, which could cause deficiencies for the young reptiles.

Stewart and colleagues, who have studied skinks for years, decided to look for clues to the nutrient problem in the structure and chemistry of the yellow-bellied three-toed skink's uterus.

"Now we can see that the uterus secretes calcium that becomes incorporated into the embryo—it's basically the early stages of the evolution of a placenta in reptiles,"Stewart explained.

Evolutionary Transition Surprisingly Simple

Both birthing styles come with evolutionary tradeoffs: Eggs are more vulnerable to external threats, such as extreme weather and predators, but internal fetuses can be more taxing for the mother.

(Related:"Human Sperm Gene Traced to Dawn of Animal Evolution.")

For the skinks, moms in balmier climates may opt to conserve their own bodies' resources by depositing eggs on the ground for the final week or so of development. Moms in harsh mountain climates, by contrast, might find that it's more efficient to protect their young by keeping them longer inside their bodies.

In general, the results suggest the move from egg-laying to live birth in reptiles is fairly common—at least in historic terms—because it's relatively easy to make the switch, Stewart said.

"We tend to think of this as a very complex transition,"he said,"but it's looking like it might be much simpler in some cases than we thought."

The skink-evolution research was published online August 16 by theJournal of Morphology.

forNational Geographic News

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New Deep-Sea Pictures: Chimaera, Ten-armed Starfish, More

Asea anemonehitches a ride on a hermit crab in one of the"rare and exciting"new pictures released last week by a joint Indonesian-U.S.oceanexpedition.

Taken near theIndonesianisland ofSulawesi (map), the high-definition,"never-before-seen views of seascapes and colorful, fascinating marine animals"were captured by a remotely operated vehicle aboard the expedition's U.S. shipOkeanos Explorer.

The ROV conducted 27 dives between 800 feet (240 meters) and 2 miles (3.2 kilometers), spotting at least 40 species that might be unknown to science, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).

(Seepictures of a giant undersea volcano released by the project team in June.)

The first in a multiyear partnership between NOAA and theIndonesian Ministry for Marine Affairs and Fisheries, the approximately two-month expedition was meant to document Indonesia's sea life and to learn more about resolving ocean problems, such asacidificationandoverfishing. (Read aboutten things you do can do save the ocean.)

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