The images above show selective collection of live cells from a mixture of live and dead cells. In (a), the cells are randomly positioned. In (b) and (c), a series of optically projected concentric circles round up live cells, while dead cells (stained with Trypan blue dye) leak out through the dark gaps and are not collected. The optical pattern has a yellowish colour, while weak background scattered light results in a pinkish hue in the non-patterned areas. Section (d) shows the collection of live cells rounded up by the optoelectronic tweezer. (Courtesy of Wu Lab, UC Berkeley) Rounding up wayward cells and particles on a microscope slide can be as difficult as corralling wild horses on the range, particularly if there's a need to separate a single individual from the group.

But now, a new device developed by University of California, Berkeley, engineers, and dubbed an "optoelectronic tweezer," will enable researchers to easily manipulate large numbers of single cells and particles using optical images projected onto a glass slide coated with photoconductive materials.

"This is the first time a single light-emitting diode has been used to trap more than 10,000 microparticles at the same time," said Ming Wu, UC Berkeley professor of electrical engineering and computer sciences and principal investigator of the study. "Optoelectronic tweezers can produce instant microfluidic circuits without the need for sophisticated microfabrication techniques."

Researchers working with rats have zeroed in on the brain circuitry mechanism whose disruption contributes to the impulsive behavior seen in users of cocaine as well as other psychostimulant drugs. The same circuitry has been implicated in such disorders as schizophrenia, depression, and post-traumatic stress disorder, wrote the researchers.

New research suggests that medications commonly referred to as fertility drugs may be ineffective for women who lack a gene called the estrogen receptor beta. The study showed that fertility drugs did not improve ovulation rates in mice that were genetically engineered to lack estrogen receptor beta. The estrogen receptor beta is one of two estrogen receptor proteins which mediate the effects of estrogen hormones and are present throughout the female reproductive tissues. These new data indicate that this receptor plays a critical role in ovulation, and suggests that women who do not have this receptor may benefit more from alternative infertility treatments. The findings are reported in Endocrinology, published in August, 2005.

Ocean bacteria with the light-sensitive proteorhodopsin enzyme live several meters above this coral reef. (Photo: Boaz Harel)About 13% of bacteria near the ocean's surface contain proteorhodopsin, a membrane protein able to harness sunlight's energy, according to a new study by Oded Beja and colleagues in the open-access journal PLoS Biology. Given the dearth of nutrients in their environment, these oligotrophic bacteria must generate their energy from a variety of sources. The study reveals that proteorhodopsin is uniquely suited to capturing the high-radiation sunlight that illuminates the sea. Through the use of meta-genomic analysis, the authors also observed great diversity among proteorhodopsin genes.

Three separate research team reports – one from Louisiana, one from Japan and one from Scotland – are presenting independent research results pointing to involvement of endocannabinoids as a novel neural messenger in various stress-related situations with possible applications in eating, disease treatment and social behavior.

Estimates for the number of living species on earth range from 3.5 million to over 30 million but only 1.9 million species have been classified and described. Estimating historical biodiversity from the fossil record is an even more daunting task.

Fire is an important agent of transformation in the Amazon landscape. Every year, low intensity fires burn thousands of square miles of Amazon forest. To study the effects of these fires on the forest, and the forests' ability to recover from repeated burning, Woods Hole Research Center scientists will burn two and a half square kilometers of forest in the transition forest of northern Mato Grosso state, at Fazenda Tanguro in Querencia, from late August into early September.

Insulin, a hormone long recognized as a generator of fat, also keeps fat in the liver under control, according to a new study in the July issue of Cell Metabolism. The newly discovered role for insulin may explain how an organ frequently flooded with the fat-building hormone normally stays trim and also suggests new dietary strategies and treatments to avoid fatty liver, a growing healthcare epidemic, said the researchers.