Cometary particles returned by the Stardust Discovery Mission are primarily silicate materials of solar system origin. Some of the grains were formed at high temperatures close to the Sun, but then transported far out to the Kuiper belt region of the solar system before being incorporated in the comet.

Single cell gel electrophoresis (the comet assay), continues to gain popularity as a means of assessing DNA damage. However, the assay's low sample throughput and laborious sample workup procedure are limiting factors to its application. "Scoring", or individually determining DNA damage levels in 50 cells per treatment, is time-consuming, but with the advent of high-throughput scoring, the limi...

The nucleus of comet C/1996 J1, whose duplicity was first detected in early May 1997, ∼ 4 months after perihelion, is found to have split nontidally∼ 70 days before perihelion at 1.65 AU from the Sun. The secondary nucleus, discovered when in outburst and subsequently observed for 8 2 months, had separated from the primary nucleus at a rate of 1.7 m/s and drifted away from it with a radial nong...

The Comet assay has been used widely in genetic toxicology, radiation biology and medical and environmental research. This assay detects single-strand breaks and alkali-labile sites in DNA and DNA degradation due to necrosis or apoptosis. It may also be modified to detect DNA cross-linking. Although a considerable number of chemicals have been tested in the assay there are many aspects of valid...

The contributions to this special issue of Mutagenesis have been selected to cover the main research areas served by the comet assay, namely genotoxicology, environmental toxicology, human biomonitoring and fundamental investigations into mechanisms of DNA damage and repair. Innovative methods are described, technical issues are explored, and guidelines are given for venturing into relatively n...