Category: Living World

Quadruple Helix Detected in Human DNA

By Breanna Draxler | January 21, 2013 3:05 pm

The quadruple helix structure is shown at the left. Fluorescent markers on the right show where the helix appears on an individual chromosome (top) and in cells (bottom).

What does DNA look like? According to the biology textbooks of the last half century, it consists of a twisting ladder of base pairs: A with T and C with G. But a new study in Nature presents evidence that some human DNA may actually have four strands instead of two, and researchers say the quadruple helix may be linked to cancer.

The now-ubiquitous double-helix structure was first published in the journal Nature in 1953 by scientists James Watson and Francis Crick from the University of Cambridge. Nearly 60 years later, scientists from the same institution have published a paper in the same journal, but their results suggest that there may be more to the structure of DNA than their predecessors thought.

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MORE ABOUT: cancer, DNA

Blueprints for Mouse Burrows Coded in Their DNA

By Breanna Draxler | January 17, 2013 2:20 pm

Image credit: Vera Domingues/Hopi Hoekstra, Harvard University

A burrow is just a hole in the ground, right? Wrong. Different species of mice have very different burrow designs, and a new study suggests that a mouse’s architectural know-how is written in its DNA: Mice constructed these species-specific burrows even when they had never seen one before.

Researchers examined the burrowing behaviors of two related mouse species. The deer mouse makes a simple burrow, just a short tunnel that leads to a nest. The closely related oldfield mouse puts a little more feng shui in its design, extending the entry tunnel and adding a back door for quick escapes from the nest. To see if the blueprints for these burrow designs were based on instinct, researchers brought the mice into the lab.

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CATEGORIZED UNDER: Living World, Top Posts

Paleontologists Use 3-D Models to Rewrite Evolution

By Breanna Draxler | January 16, 2013 10:56 am

Illustrated version of an Ichthyostega tetrapod, zooming in on the correct orientation of two vetrebrae reconstructed in the study. Credit: Julia Molnar.

When the earliest animals hauled themselves out of the ocean and evolved legs, they began flopping and eventually walking down the evolutionary path toward terrestrial life as we know it. The fossil remains of these first four-legged creatures, called tetrapods, have played a crucial role in understanding this sea-to-land transition. The spine is of particular interest, but it turns out that paleontologists had it backward.

Tetrapod fossils have long proven difficult to study since the bones often can’t be separated from the petrified material that surrounds them. Using a new modeling method, researchers bombarded these 360-million-year-old fossils with high-energy X-rays in order to make 3-D models of the ancient remains. The new method, reported in Nature this week, allowed researchers to isolate the otherwise-hidden bones and see them in their original orientation.

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CATEGORIZED UNDER: Human Origins, Living World, Top Posts

The Unforeseen Social Effects of China’s One-Child Policy

By Breanna Draxler | January 11, 2013 4:20 pm

China’s One-Child Policy, now in its fourth decade, has achieved its goal of controlling population growth in the world’s most populous country, but it has also created major age and gender imbalances in the process.

In addition to sweeping social and economic instability, the policy has proven problematic on an individual level. An entire generation of Chinese has essentially grown up spoiled and without siblings. The resulting shift in social behavior is often referred to as the “little emperor effect,” and researchers have now quantified its impact in a study published this week in Science.

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CATEGORIZED UNDER: Living World, Top Posts

Oil Spill Cleanup Could Kill Coral

By Breanna Draxler | January 11, 2013 11:02 am

Mustard hill coral (Porites asteroides)

When the Deepwater Horizon oil rig blew in 2010, it spewed some 200 million gallons of oil into the Gulf of Mexico. In order to break up the slick, another 1.84 million gallons of dispersant was added to the mix. This one-two punch of toxic chemicals devastated coastal ecosystems [pdf], but how would such a chemical bombardment affect underwater ecosystems like coral reefs? According to a new study, the picture is no prettier.

Researchers at the Mote Marine Laboratory in Florida tested the effects of Deepwater Horizon-type oil and the dispersant used to clean it up, Corexit® 9500int, on coral larvae in the lab to replicate what may have happened following the spill. Larvae colonize reefs by sampling a surface, sticking to it and then changing into a polyp to get growing. They do this based on chemical cues in the water. Adding oil and dispersant, it turns out, severely hinders this sensitive settlement process.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

New Virus Causes Deadly Brain Cancer in Raccoons

By Breanna Draxler | January 10, 2013 9:16 am

Nine of the virus’s victims were found just north of San Francisco and a tenth in southern Oregon. There may be more, too, since raccoons have a habit of hiding when they get sick.

Ten raccoons in the past three years have been found on the West Coast with a deadly brain cancer, and scientists are linking the animals’ deaths to a virus they had never seen before.

While typically elusive and nocturnal, the infected raccoons were seen approaching humans, meandering around during the day, and even passing out. Once the raccoons died, veterinarians conducted autopsies and were surprised to find tumors—a rare occurrence in raccoons—in their brains.

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CATEGORIZED UNDER: Living World, Top Posts
MORE ABOUT: polyomavirus, raccoons

Parasite Wasp Sanitizes Its Six-Legged Meal

By Breanna Draxler | January 9, 2013 8:00 am

This emerald cockroach wasp (Ampulex compressa) leads a cockroach to its burrow using its own antennae as a leash.

The emerald cockroach wasp is a mother on a mission. This parasitic insect lays its eggs on cockroaches, but to minimize the risk of the host’s many microbes and pathogens to her eggs, the wasp does what many human mothers today would do. The wasp arms her babies with sanitizer before dropping them off.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

The Fish That Climbs Waterfalls With Its Mouth

By Breanna Draxler | January 8, 2013 11:41 am

Hawaii’s environmental extremes (read a series of active volcanic islands isolated in the middle of the ocean) make it a hotbed of novel evolutionary adaptations. Take goby fish in the genus Sicyopterus, for example. These lowly little bottom-feeders spend their days sucking algae off the rocks of stream beds. But that same sucking mechanism also allows the fish to climb up waterfalls over 300 feet tall. The question is how these two activities are related.

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CATEGORIZED UNDER: Living World, Top Posts

Phasing Out Polluting Microplastics

By Breanna Draxler | January 2, 2013 2:19 pm

Exfoliation is good for the skin, but the scrubbers in some soaps are bad for the environment. Last week global consumer-goods company Unilever acknowledged the growing concerns of scientists and environmentalists by saying the company will no longer use these plastic beads in its products.

The plastics in question are called microplastics, itty bitty pieces of plastic less than five millimeters in diameter. The problem with their small size is that these plastics rinse right down drains and collect in marine environments and the stomachs of marine animals. Studies published in the last month have reported microplastics inside fish in the English Channel and harbour seals in the Netherlands. In fact, a review of microplastics published last year demonstrated that these tiny plastics are now all over the place.

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CATEGORIZED UNDER: Environment, Living World, Top Posts

The Bat: A Long-Lived, Virus-Proof Anomaly

By Breanna Draxler | January 1, 2013 8:00 am

The Australian black flying-fox (Pteropus alecto) was one of the bat species whose genome was sequenced in the study.

Bats are pretty impressive critters. They are notorious for carrying viruses like Ebola and SARS, but somehow avoid getting these diseases themselves. They are the only mammal that can fly, and they live far longer than other mammals their size. What’s their secret? Researchers in Australia sequenced two different bat genomes and found that these unique bat characteristics are not only genetically linked, but may help in the treatment of human diseases.

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