Marine iguanas on the Galápagos Islands live without predators – at least this was the case up until 150 years ago. Since then they have been confronted with cats and dogs on some islands of the Archipelago. For scientists, they are therefore a suitable model of study in order to discover if such generally tame animals are capable of adapting their behaviour and endocrine stress response to novel predation threats. Scientists from the Max Planck Institute for Ornithology, the University of Ulm Tufts University and Princeton University were able to show that the stress response induced by corticosterone (CORT) is absent in predator-naïve animals but can be fully restored with experience. However, as the researchers found out, the flight distance of the reptiles does not sufficiently increase, which limits their ability to successfully escape from newly introduced predators
In a study that marks progress in understanding the basis of coral reef recovery, researchers have revealed the critical importance of a rare batfish, Platax pinnatus, in promoting the return to health of a disturbed coral reef overgrown with algae.
How a potentially deadly bacterium that could be used as a bioterrorist tool eludes being killed by the human immune system is now better understood.
Researchers at the National Institutes of Health have developed an experimental vaccine that could, theoretically, eliminate malaria from entire geographic regions, by eradicating the malaria parasite from an area’s mosquitoes. The vaccine, so far tested only in mice, would prompt the immune system of a person who receives it to eliminate the parasite from the digestive tract of a malaria-carrying mosquito, after the mosquito has fed upon the blood of the vaccinated individual. The vaccine would not prevent or limit malarial disease in the person who received it.
An international team led by University of Adelaide palaeontologist Trevor Worthy has discovered a unique, primitive type of land mammal that lived at least 16 million years ago on New Zealand.
Disease-causing organisms can be present in some areas where their hosts are not. If their hosts arrive, novel disease outbreaks may result.
Want biodiversity? Look no further than the air around you. It could be teeming with more than 1,800 types of bacteria, according to a first-of-its-kind census of airborne microbes recently conducted by scientists from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab).
Forthcoming in the January/February 2007 issue of Physiological and Biochemical Zoology, a groundbreaking study reveals an unanticipated way freshwater fish may respond to water diversion and climate change. Endangered naked carp migrate annually between freshwater rivers, where they spawn, and a lake in Western China, where they feed and grow. However, Lake Qinghai is drying up and becoming increasingly more saline–leading to surprising adjustments to the carps’ metabolic rate.
Naked carp take seven to ten years to reach reproductive size. Although historically abundant, overfishing and destruction of spawning habitat through dam-building caused the species to become endangered during the 1990s. Diversion of water for agriculture from the lake has been compounded by climate change, leading to a decline in water level in the lake of 10–12 cm per year during the past fifty years (see accompanying image).
However, Chris M. Wood (McMaster University) and coauthors found that naked carp respond to the increased salinity of the lake water in a surprising way–by taking a “metabolic holiday.” In the first forty-eight hours after transitioning from the freshwater river system to lake water, the carps’ oxygen consumption falls –eventually reaching just 60 percent of that in river fish.
Both gill and kidney functions also decline. The sodium/potassium pump (Na+/K+-ATPase), which is a protein critical for cellular function, operated at only 30 percent of its capacity in lake-water fish compared to river-water fish. Ammonia-N secretion by the kidneys declines by a surprising 70 percent, and urine flow decreases drastically to less than 5 percent of its rate in the freshwater river water.
University of California, Berkeley, graduate student Allen Liu last Friday donned coveralls, a blindfold, earplugs and gloves, then got down on all fours and sniffed out a 33-foot chocolate trail through the grass. This was no fraternity initiation, but part of an experiment to find out whether mammals compare information coming from their two nostrils in order to aid scent-tracking performance, much like they compare information from their ears in order to locate a sound.
Who will be the next Albert Einstein? The next Stephen Hawking? A new report from Vanderbilt University reveals the complex mix of factors that create these intellectual leaders: cognitive abilities, educational opportunities, investigative interests and old-fashioned hard work.
Children who received light therapy (phototherapy) for jaundice as infants appear to have an increased risk of developing skin moles in childhood, according to a report in the December issue of Archives of Dermatology, one of the JAMA/Archives journals. Some types of moles are risk factors for developing the skin cancer melanoma.