Editor's Note: Science Scan is a roundup of recently published biotechnology-relevant research.

Adding to the paradox of prion diseases, Dartmouth Medical School researchers have discovered that RNA plays a role in converting a normal prion protein into a mutant that leads to bovine spongiform encephalopathy (BSE) - also known as mad cow disease - and other fatal brain illnesses. Their study, reported in the Oct. 16, 2003, issue of Nature, provides clues to understanding the role of prions (which stands for proteinacious infectious particle). Those unorthodox infectious agents, with the ability to transmit disease, have confounded scientists and physicians for 30 years. The Nature article is titled "RNA molecules stimulate prion protein conversion."

The work opens exploration avenues of neurodegenerative disorders called prion diseases. Prions lack RNA or DNA, the nucleic acids that contain genetic information. No one knows what spurs conversion of a normal prion protein to a disease-causing counterpart. Dartmouth co-authors said that RNA might be a catalyst for transformation. "It has been well proven," stated the paper's senior author, Surachai Supattapone, "that nucleic acids, including RNA, are not part of the infectious agent, so it's an ironic twist that a catalyst for the reaction may be RNA." He emphasized, however, that the findings are consistent with the "protein-only" hypothesis of prion diseases because the nucleic acids are in the host and are not contained in the disease-spreading particle.

Prions related to infectious disorders such as Cruetzfeldt-Jakob disease (CJD) in humans and chronic wasting or scrapie in animals, often develop over years, so research has moved slowly. CJD, once an affliction of the elderly, now attacks victims in their prime of life who are suspected of ingesting meat from infected mad cows. The discovery more than a quarter-century ago that prions were proteins, devoid of nucleic acid, upended what scientists assumed not only about disease transmission but also about life itself. All mammals have a gene to make a prion protein, but the normal protein is a different shape from the infectious prion. Somehow, this normal protein is modified into an abnormal counterpart that accumulates in the brain until death. (The new disorder is called "variant" CJD.)

"It's a curious thing," Supattapone remarked, "because this protein is able to stimulate its own formation and change without nucleic acids. It's been a fascinating question for scientists, besides being the central reaction in an important medical problem." Now his team has discovered that specific RNA molecules are required to transform prion proteins into their abnormal shapes. The team devised a technique to observe how the normal prion protein, called PrPSc, efficiently converts into the abnormal infectious protein PrPSc (for scrapie) in a test tube. This permitted pinpointing the conversion in the cell. The existence of RNA-converting factors could aid early detection of prion diseases.

Marijuana Therapy For Multiple Sclerosis? Mixed Results Of Large-Scale Survey

Multiple sclerosis (MS) symptoms feature muscle stiffness, spasm, pain and tremor. Much anecdotal evidence suggests that cannabinoids (marijuana derivatives) could alleviate those symptoms.

An article in The Lancet dated Nov. 8, 2003, carries the title "Cannabinoids for treatment of spasticity and other symptoms related to multiple sclerosis (CAMS study) multicenter randomized placebo-controlled trial." The trial enrolled 667 patients with stable multiple sclerosis and muscle spasticity. Another cohort of 630 participants was treated at 33 UK centers with oral cannabis extract. Trial duration was 15 weeks.

Although the main research finding showed no improvement in spasticity scores among patients given cannabinoids compared with placebo, the results suggest that cannabinoids could have potential clinical use for improving patients' mobility and pain control. In all three participating groups, while on treatment, patients were observed to have a small reduction in time taken to walk a short distance.

In the cannabinoid treatment groups, 60 percent of patients reported improvement in pain, compared with 37 percent in the placebo group. However, when patients become aware, owing to side effects of the treatments they are receiving, might explain some of the subjective ratings.

An accompanying commentary made several points: "We still have no data to compare the risks and benefits of smoked cannabis. Hopefully, this study will stimulate further research to develop and evaluate safe effective formulations of cannabis, and will inform debate over the social and legal restrictions that limit its use. In the meantime, when other treatment inadequately controls spasticity, oral cannabinoids should be considered where law permits their possession and use."

New Dangers Assail Future Life Styles Of Monarch Butterfly Migrations, Long A Target For Ag Biotech

A paper in Nature dated May 20, 1999, set off chaos in the agricultural biotechnology movement that may still be resonating. Its title: "Transgenic pollen harms monarch [butterfly] larvae." The authors, at their Cornell lab in Ithaca, N.Y., allowed the monarch butterfly larvae to feed on pollen from transgenic corn, which they had dusted on milkweed leaves, the monarch's fodder of choice. Result: only 56 percent of the larvae survived. The bright orange and black insects (Danaus plexippus) quickly became the poster bug for opponents of biotechnology.

Contrary voices suggested from time to time that a lab bench and artificial provender doesn't stack up against field conditions. At long length, an article turned up in the current Proceedings of the National Academy of Sciences (PNAS), released online Nov. 10, 2003. Its title: "Modeling current and future potential wintering distribution of eastern North American monarch butterflies." It might prove the last word on the subject.

The co-authors noted that the monarch's Herculean annual migrations to Mexican wintering grounds might one day be in vain. Within 50 years, the high-altitude fir forests of Central Mexico that support and protect millions of these winged insects could become unsuitable wintering grounds - too much wet, cold weather and the butterflies will die.

A technique called ecological niche modeling identified specific areas suitable for overwintering monarch colonies. The model produced a distribution of sites that closely match the monarchs' current distribution. Based strictly on ecological parameters, it ignored other events, like logging, that could also endanger the poster bug's migratory habitat.