Science News Shorts for the Week of March 15, 2010

Friday, March 19th, 2010--

Spring Springs Earlier for Butterflies

In Australia, common brown butterflies (heteronympha merope) are emerging from their cocoons an average of ten days earlier than they did 65 years ago, according to researchers reporting in the journal Biology Letters.

Are common brown butterflies (heteronympha merope) in Australia emerging early? Photo by Flickr user Ibsut.

The researchers, led by biologist Michael Kearney from the University of Melbourne, attribute the butterflies’ early appearance to warming temperatures in the region. To make this link, they first raised caterpillars of the common brown butterfly in the laboratory and measured how quickly they emerged when exposed to different temperatures. The warmer the temperature, the earlier the butterflies took flight. They then used these measurements along with historic records of air temperatures around Melbourne, which rose about .25°F per decade, to predict when the butterflies emerged each year. Their predictions matched recorded observations. They concluded that warming temperatures are coaxing the butterflies around Melbourne from their cocoons earlier each year, at a rate of about 1.6 days per decade. The researchers believe the change in temperature is the result of human greenhouse gas emissions, not climate variability.

Source: Kearney, M. et al. 'Early emergence in a butterfly causally linked to anthropogenic warming.' Biology Letters. March 17, 2010.

What Makes Us Unique?

What makes you different from every other human being? The best place to look for an answer may not be in your genes, but in the sequences of DNA between them, according to a team of researchers reporting in the journals Science Express and Nature.

While genes provide instructions for making the proteins that do specific tasks inside a cell, the sequences surrounding them help regulate how those instructions are carried out. These non-coding sequences make up about 98% of our genome. They vary from 1% to 4% among all humans, in contrast to genes, which vary only about .025%. According to the new studies, such slight variations among individuals are enough to affect how well specialized proteins, called transcription factors, bind to the non-coding DNA sequences. By comparing variations in protein binding among ten people and one chimpanzee, researchers found that differences in binding can change the way neighboring genes are expressed. The results suggest that much more of our DNA than just our genes determine how we look, who we become, and the kinds of diseases for which we’re at risk.

Sources:
Kasowski, Maya et al. 'Variation in Transcription Factor Binding Among Humans.' Science Express. March 18, 2010.
Zheng,Wei et al. 'Genetic analysis of variation in transcription factor binding in yeast.' Nature. March 17, 2010.

The 20-Minute Workout

Finding time to exercise may be easier than we think. In fact, 20-minute cycle sprint workouts three times a week can provide some of the same physical benefits as long endurance workouts, according to new research published in The Journal of Physiology.

Exercise -- are short-duration, high-intensity bursts worthwhile? Photo by Flickr user mjmonty.

Previous research has shown that running or cycling at a moderate pace for several hours a week makes muscle cells more efficient at using oxygen, burning fuel, and getting rid of waste. Having more efficient muscles can reduce the risk of a heart attack, stroke or diabetes, according to researchers.

But in the new study, scientists from the McMaster University in Canada show that short, fast workouts can be just as effective at whipping your muscles into shape. They put seven healthy college-age men on a 2-week-long exercise regimen of short-term, high-intensity interval training, or HIT. For these men, HIT meant doing ten 1-minute sprints on a stationary bike with one minute of rest in between on Mondays, Wednesdays, and Fridays. The researchers tested the men’s cycling speed and took biopsies of their thigh muscles before and after the 2-week training period. They found that just two hours total of HIT improved their cycling speed and muscle efficiency just as well as ten cumulative hours of endurance cycling, as demonstrated in earlier studies.

Source: Little, Jonathan P. et al. 'A practical model of low-volume high-intensity interval training induces mitochondrial biogenesis in human skeletal muscle

--Ariel Bleicher