Variations in atmospheric phenomena such as El Niño are likely responsible for fluctuations in hurricane strength over the past 5,000 years, Woods Hole researchers have found. Their conclusions suggest that the higher sea temperatures associated with global warming, though conducive to intense storms, are not required to produce them. Jeffrey Donnelly and Jonathan Woodruff constructed a history of hurricane activity in the western North Atlantic by examining sediment from the island of Vieques, Puerto Rico. Distinctive layers within the sediment following storm surges enabled the scientists to distinguish periods of intense hurricane activity from relatively calm ones. After comparing their record with existing data on El Niño and the West African monsoon, the team found that the number of powerful hurricanes increased when El Niño was weak and the West African monsoon strong -- corresponding to previous findings. Because storm intensity has varied greatly among time periods within the last five millennia, with times of intense storm activity sometimes coinciding with relatively cool ocean temperatures, the researchers concluded that warmer waters are probably not required for more frequent, powerful hurricanes. However, Donnelly says, "We don't have an analog in the record for what we've done to the climate in recent years. If we see less El Niño and warmer sea temperatures, we could be in trouble."
BOTTOM LINE: Variations in El Niño and the West African monsoon appear to be responsible for long-term fluctuations in the intensity of hurricanes. Understanding how climate change might affect these patterns will be needed to predict the intensity of hurricanes in the future.
CAUTIONS: The researchers could not determine if recent warmer sea temperatures might have an indirect impact on hurricane activity through affecting climate patterns.
WHAT'S NEXT: Donnelly has begun examining how typhoon activity in the Pacific Ocean has changed over time.
WHERE TO FIND IT: Nature, May 24.
Researchers track down genes that cause antibiotic resistance
More and more infections -- particularly in hospitals -- are becoming resistant to antibiotics, as the bugs learn to outwit the drugs. In an effort to understand how they do it, researchers at Rockefeller University took six samples from one patient as his body was hijacked by a drug-resistant staphylococcus infection called MRSA. Post doctoral fellow Michael Mwangi and his colleagues performed whole-genome sequencing on bacteria from the beginning and end of the infection, uncovering 35 mutations that occurred during that time. By studying intermediate samples taken throughout the infection, they found that the mutations occurred sequentially. They honed in on the mutations that happened before the bug reached its maximal level of resistance, and therefore were the most likely to have triggered resistance. Now, "we have a sense of which of the mutations are responsible for resistance," Mwangi said. One in particular was also found in other strains of MRSA resistant to the same antibiotics -- sparking hopes that treatments could be developed to focus on that genetic location.
BOTTOM LINE: Genome sequencing technology is giving researchers new insights into how bacteria mutate to become drug-resistant, and paving the way for new treatments.
CAUTIONS: The samples for this study were all taken from a single patient; the researchers caution that other strains may yield different mutations.
WHAT'S NEXT: Mwangi and his colleagues are examining samples from around the world to determine how many of the mutations they found can also be found in other strains.
WHERE TO FIND IT: Proceedings of the National Academy of Sciences, May 21.