Science Briefs: Miniature frogs discovered, Duke scientists’ 3-D map of brain stem, NC State and Clemson find limits to pest control in GM crop

One of the species of miniaturized frog found in the Brazilian Atlantic Forest, shows the extent of the miniaturization.
One of the species of miniaturized frog found in the Brazilian Atlantic Forest, shows the extent of the miniaturization. CC BY SA

Quite a small surprise: Mini frogs discovered in Brazilian rainforest

After nearly five years in mountainous areas of the southern Brazilian Atlantic rainforest, Brazilian researchers have uncovered seven new species of a highly miniaturized, brightly colored frog genus. Each species is restricted to cloud forests in one or a few adjacent mountaintops, making them highly vulnerable to extinction.

These Brachycephalus frogs are among the smallest terrestrial vertebrates, with adult sizes often not exceeding 0.39 inches in length – leading to a variety of changes in their body structure, such as reduction in the number of toes and fingers. In addition, many species of Brachycephalus are brightly colored, possibly as a warning to the presence of a highly potent neurotoxin in their skin.

The study was published in the peer-review journal PeerJ.

Duke scientists produce detailed 3D map of brain stem

Scientists at Duke University Medical Center have produced a 3-D map of the human brain stem at an unprecedented level of detail using MRI technology.

In a study published in Human Brain Mapping, the researchers unveil an ultra high-resolution brain stem model that could better guide brain surgeons treating conditions such as tremors and Parkinson’s disease with deep brain stimulation. The new 3-D model could eliminate risky trial-and-error as surgeons implant electrodes – a change akin to trading an outdated paper road atlas for a real-time GPS.

“On the conventional MRI that we take before surgery, the thalamus looks like a gray mass where you can see only the borders,” said neurosurgeon Nandan Lad, M.D., Ph.D., director of the Duke NeuroOutcomes Center and an author of the paper. “Now we will have actual detail. With this map, for the first time we’re able to see the thalamus and that underlying circuitry that we are modulating.”

NCSU field study: GM crop can have diminishing success fighting pest

A new study from N.C. State and Clemson University finds that the toxin in a widely used genetically modified crop is having little impact on the crop pest called corn earworm – which is consistent with predictions made almost 20 years ago that had been largely ignored. The study may be a signal to pay closer attention to warning signs about the development of resistance in agricultural pests to GM crops.

At issue is genetically engineered corn that produces a Bacillus thuringiensis protein that, in turn, produces a toxin called Cry1Ab. This GM corn was originally designed to address a pest called the European corn borer and went on the market in 1996.

In the late 1990s, scientists found that Cry1Ab was also fairly effective against corn earworm. But the scientists also predicted that enough corn earworm were surviving to lead to the species developing resistance to Cry1Ab. That work was done, in part, by Fred Gould, an entomology researcher at N.C. State.

More than 15 years later, N.C. State researcher Dominic Reisig, an associate professor of entomology, wanted to see if Gould’s predictions held up.

He and his collaborator, Francis Reay-Jones of Clemson, evaluated corn crop sites in North Carolina and South Carolina over two years – and the results were fairly stark.

In the late 1990s, Cry1Ab reduced both the number and size of corn earworm larvae and the size of the larvae, compared to non-Bt corn. But Reisig and Reay-Jones found Cry1Ab now has little or no effect on number or size of larvae compared to non-Bt corn.