Happy hour in the rain forest

The pen-tailed tree shrew, in particular, takes advantage of it. By watching the animal and analysing fur samples, the researchers estimated that the tree shrews consumed enough alcohol that they had about a 36 percent chance of being intoxicated (by human standards). But the researchers never saw any signs of inebriation, and from an evolutionary standpoint, it makes no sense to be drunk anyway. With predators all around, Wiens said, “it’s just too risky for an animal”.

The findings suggest that the animals have some efficient means of metabolising alcohol and there must be benefits to having chronic low levels of alcohol in the bloodstream—otherwise the behaviour would not have evolved.

Those benefits may be psychological, Wiens said, perhaps enabling the animals to cope with stress. Further studies to determine the benefits may help in understanding humans’ relationship to alcohol, he said. And because tree shrews are similar to species that were precursors of primates more than 50 million years ago, they might also provide some evolutionary background for human drinking, he added.

The micro-microscope
In the drive to miniaturise laboratory tools, to create a so-called lab-on-a-chip, the conventional light microscope has been a stumbling block. Microscopes require lenses and, above all, space to focus and magnify images.

Changhuei Yang (below) and others at the California Institute of Technology have developed an approach, one that eliminates the need for lenses and space. In their device, called an optofluidic microscope, a specimen passes directly over a digital imaging chip that is masked by a metal film with a micron-size hole over each pixel. By arranging the holes in a certain way and illuminating the specimen as it flows at a constant rate over the chip, a high-resolution image can be obtained.

In a paper in The Proceedings of the National Academy of Sciences, Yang and colleagues report the development of two fully functioning microscopes-on-a-chip. One is designed to image long, thin objects like C. elegans, those tiny worms that are used as model organisms in laboratories around the world. The other can be used to look at spherical or ellipsoidal objects like cells.

The basic imaging technique is the same in both devices; the differences arise in how the specimens are moved across the sensor chip. In the first device, gravity moves the worms or other specimens in water through a tiny channel. But because of small differences in flow velocity, that method could cause a spherical object like a cell to tumble. So in the second device, the researchers use a small electric field to keep the specimens stable and move them across the chip.

Acidity gets to coral reefs
The gradual acidification of oceans through increasing absorption of atmospheric carbon dioxide is thought to be potentially bad news for coral reefs. As seawater pH falls, the saturation level of carbonate ions in the water also declines. Since reefs are made up of calcium carbonate they should be slower to form and faster to fall apart. But given that ocean pH is changing very slowly, and reefs form over millennia, it’s difficult to see any effects. There is an area of the eastern Pacific off Central America, however, where the water is more acidic than elsewhere. Coral reefs in this region are poorly developed and tend to erode rapidly. Derek P. Manzello of the University of Miami and colleagues report that the carbonate saturation level is low and that there is relatively little inorganic calcium carbonate “cement” that helps bind the coral skeletons together in the area. This may serve as a model in further studies to help understand what reef systems elsewhere will encounter in a higher-CO2 environment.
(New York Times)