SCIENCE SHORTS

T

Categorizing Species by DNA

Some scientists are proposing to replace the unreliable process of distinguishing plant and animal species by physical attributes with a taxonomy based on DNA. One key gene, called COI, plays a crucial role in metabolism and is present in all animals. But its sequence — the exact order of its chemical bases — varies substantially and is unique for each animal species. This makes it a prime candidate to serve as a bar code. The sequence has 10 elements, each of which can be adenine, cytosine, guanine or thymine, so there are 4¹⁰ (over a million) possible combinations or ‘bar codes’.

Trans Fats Under Siege

It looks like a rerun of the war against second-hand smoke. A few years ago no one knew what trans fats were (they’re partially hydrogenated oils, transforming them from liquid to solid form). Now they’re pegged as a major cause of heart disease and other ailments and moves are afoot to require them to be identified on all food product labels. Already many people are saying that’s not enough, and there should be health hazard warnings on the package, or even suggesting they be banned entirely. It’s interesting how quickly change can be demanded, and achieved, when two criteria are met: (a) there’s a high perceived risk to health or safety, and (b) the change is easy to make and has limited economic and social consequences. Too bad the changes that are most needed don’t meet those criteria.

Cities Change Climates

New research by atmospheric scientists in NASA indicates cities play a major role in local climate variation. Three major causes have been found so far — the 1-to-10 degree higher temperature in cities than in surrounding areas, the high level of particulates (which reduces precipitation in the city and increases it downwind), and the high ground cover of asphalt (which absorbs heat, increases water runoff and affects wind patterns). The scientists hope NASA’s simulations will help to explain and predict some of the local climatic effects of human activity, and then lead to the ability to explain and predict global impact, swaying skeptics on the need to address global warming, and giving those that understand the problem more ammunition to figure out just what, and how much, needs to be done to mitigate it, and what will happen if we don’t.