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DISCOVERIES

DNA analysis helped target ivory poachers

CONSERVATION
Eighteen years after the ivory trade was banned, soaring ivory prices have led to a sharp increase in elephant poaching and cross-border ivory smuggling. Efforts to stem the illegal trade have been hampered by the difficulty in pinpointing the origin of contraband ivory. Now, an international research team has used DNA analysis to help identify the places where poaching takes place. Examining 532 elephant tusks taken from a recent major ivory seizure, the researchers compared DNA from a selection of the tusks to samples taken from elephant tissue and dung from sites around Africa. The team was able to trace the tusks to a specific area in southern Africa centered on Zambia and, in doing so, rejected the hypothesis that the ivory had come from a wider range of locations in Africa. The team's conclusion led the Zambian government to strengthen its anti-poaching efforts. "We hope the results of the study will help focus enforcement further so that poaching will stop and the elephant population can be saved," said lead author Samuel Wasser, director of the Center for Conservation Biology at the University of Washington.

BOTTOM LINE: DNA analysis was used to track the origins of contraband ivory and helped law enforcement officials better target poachers.

CAUTIONS: Because only a random sample of the elephant tusks from the ivory seizure were used in determining a place of origin, it is possible that some of the remaining tusks would have pointed to a different location.

WHAT'S NEXT: The researchers are working closely with the Interpol Working Group on Wildlife Crime in analyzing recent major ivory seizures to pinpoint places with high incidences of poaching.

WHERE TO FIND IT: Proceedings of the National Academy of Science, March 6.

AMI ALBERNAZ

PEDIATRICS

Children's brains can be reshaped by stress


Severe stress can change the structure of a child's brain, a new study finds, potentially limiting the child's ability to cope with the crisis. Levels of the hormone cortisol are known to rise with stress, and past studies in adults have suggested an association between higher emotional stress and a smaller hippocampus -- a brain region closely connected to the emotion center and involved with memory storage and processing. A group of researchers led by Dr. Victor Carrion from Stanford University looked at the brain structures and bedtime cortisol levels of 15 children, ages 7 to 13, who were suffering from post-traumatic stress disorder. Twelve to 18 months later, participants were assessed again, and researchers found that hippocampus volumes were reduced more in children with more severe stress symptoms and higher bedtime cortisol levels. Because the hippocampus is so important in memory and emotion processing, researchers think that its reduced volume will lower a child's coping ability. This, in turn, will raise stress and cortisol levels, further damaging the hippocampus and continuing the vicious cycle.

BOTTOM LINE: Dr. Carrion said that current psychiatric therapies may work less well in children with post-traumatic stress disorder because of their compromised coping abilities. "We need to develop more focused therapeutic interventions that take this into consideration," he said.

WHAT'S NEXT: The researchers want to see if the functional ability of the hippocampus is also reduced over time by high cortisol levels.

CAUTIONS: This is a small pilot study. More and larger studies are required to confirm its findings. The study does not compare brain structure before and after trauma, or between children with and without post-traumatic stress disorder.

WHERE TO FIND IT: Pediatrics, March 2007

SENA DESAI GOPAL

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