Articles by Leslie Pray

In less than three decades, the polymerase chain reaction has evolved from a slow, labor-intensive practice that was initially performed manually and only by the initiated few, to a fast, powerful, easy-to-use tool found in life science laboratories everywhere.

Towering figure of 20th century evolutionary biology was 100

More than 2,000 years ago, Hippocrates wrote: "Leave your drugs in the chemist's pot if you can heal the patient with food."

MULTIPHOTON MICROSCOPY APPARATUSCourtesy of Watt WebbDeveloped just over a decade ago, multiphoton microscopy (MPM) has taken neuroscientists to places that Leeuwenhoek probably couldn't fathom. It's taken them further even than confocal microscopy has – further into the light-scattering depths of the brain, that is. By relying on more targeted and less damaging light than its confocal predecessor, MPM gives neuroscientists the ability to noninvasively image hundreds of microns below the s

Earlier this summer scientists from New England Biolabs in Beverly, Mass., announced they had discovered a new way to copy DNA. Their method, called helicase-dependent amplification (HDA), reportedly mimics in vivo DNA replication better than PCR does.1 Moreover, HDA can be conducted at a single temperature, thus obviating the need for thermocycling. In the future, perhaps the limitations of PCR – that it is reagent intensive, requires expensive equipment, is difficult to reproduce, and ge

Theodor Diener's 1971 discovery of viroids was hard sell. The now-retired Diener, who was working as a plant pathologist with the Agricultural Research Service in Maryland, was trying to isolate the infectious agent responsible for potato spindle tuber disease. He presumed it was a virus. Instead, he detected a novel pathogen, which, unlike viruses, was not protected by a protein coat and appeared to comprise a single RNA molecule.1Many investigators weren't convinced that the hypothesized entit

PATHOGENICITY MODEL:© National Academy of Sciences, USAViroid replication generates dsRNA intermediates, which are processed by Dicer into 21- to 25-nucleotide siRNAs. These siRNAs are then incorporated into siRNA – ribonuclease complexes (RISC). If the siRNA sequences significantly match host mRNAs, RISC may target them for degradation leading to disease symptoms. RISC can also target the viroid, forcing it to evolve and to adopt and maintain an RNA silencing-resistant structure. (Fr

©Mehau Kulyk/Photo Researchers, IncToward the end of World War II, a German-imposed food embargo in western Holland – a densely populated area already suffering from scarce food supplies, ruined agricultural lands, and the onset of an unusually harsh winter – led to the death by starvation of some 30,000 people. Detailed birth records collected during that so-called Dutch Hunger Winter have provided scientists with useful data for analyzing the long-term health effects of prenat

Courtesy of Cristina K. MoreiraAt least two years ago, scientists began creating genetically engineered mosquitoes with reduced capacity to transmit malarial parasites. But recent studies offer mixed messages as to whether bio-engineered skeeters can compete in the wild.In a laboratory study with Anopheles stephensi, Case Western Reserve University's Marcelo Jacobs-Lorena and colleagues showed that a transgene encoding the protein SM1, which interrupts parasite development, did not affect mosqui

Would popping daily citaloprams, I wonder, have restrained Jackie Kennedy's celebrated spending sprees and prevented the purported ensuing marital discord? How about a fluvoxamine prescription? Or natrexone? And what about publisher William Randolph Hearst who, at the peak of his purchasing power in the 1920s, spent $15 million a year? Even after achieving near bankruptcy, Hearst continued feeding his mania for antiquities, tapestries, oriental rugs, paintings, and other collectibles. Would medd

Eye of Science / Photo Researchers, Inc. "The general character and structure of the rod-like individuals, together with their vegetative multiplication by fission, renders their schizomycetous nature as individuals a matter hardly to be doubted: but, on the other hand, the question may fairly be asked whether the remarkable phenomena may not indicate a possible relationship in other directions." --Roland Thaxter, 1892 While walking through the New England woods one day in the late 19th c

Mechanisms of Speciation New examples of sympatric speciation revive some nagging questions | By Leslie Pray "A new species develops if a population which has become geographically isolated from its parental species acquires during this period of isolation characters which promote or guarantee reproductive isolation when the external barriers break down." --Ernst Mayr, Systematics and the Origin of Species, 19421 The duration of a cell cycle lasts anywhere from one hour to one day; Droso

Courtesy of Chloe Hutton, Functional Imaging Lab  THICK OR THIN? The cerebral cortex thickness metric can be used to study the progression of diseases such as Alzheimer disease, epilepsy, mental retardation, and schizophrenia, and to investigate how brain function is affected in the abnormal regions. According to legend, functional neuroimaging can trace its roots to the stroke of noon on a day in the late 19th century, when Italian physiologist Angelo Mosso observed a sudden increase in

Photo: Denis Crawford of Graphic Science  CAN'T TAKE THE HEAT: Drosophila birchii, the Australian rainforest vinegar fly, was unable to evolve adaptations for a hot, dry environment in laboratory tests. Average global temperatures are expected to rise by 5°C or more over the next century. That's a lot of heat to handle for thousands of plant and wildlife species that already have been affected by a seemingly paltry 0.60°C temperature change over the past century. Eggs hatch and

"I lost concentration and began to think of our scholarly daughter working at Yale on a project called Zinc Fingers scanning a protein with pseudopods each with a trace of zinc that latch on to our DNA and help determine what we become." --From Zinc Fingers, Peter Meinke  "GREEN" FINGERS: Zinc finger- based artificial transcription factors (background) have been applied in plants such as Arabidopsis thaliana (foreground). Reprinted with permission, Curr Opin Plant Biol, 6:163-8, Apri