In this week's Science, an international group of researchers publishes a report of genetic mutation signatures associated with tobacco smoke. They analyzed the genomes of 5,000 tumors from smokers and non-smokers, representing 17 different cancers for which smoking is a risk factor. From this, they discovered a complex series of mutations associated with smoke exposure. One mutational signature, which is mainly found in cancers of tissues directly exposed to smoke such as lung, was found to be caused by the misreplication of DNA damage caused by tobacco carcinogens, for instance. Smoking was also found to be associated with limited differences in methylation, which reinforces the theory that smoking increases cancer risk by increasing the somatic mutation load, although there is no direct evidence for this in some smoking-related cancer types. GenomeWeb has more on this study, here.
Also in Science, a multi-institute team presents a new study suggesting that a scientist's professional impact is distributed randomly over the sequence of studies they publish, calling into question the theory that a researcher's best work is done early in their career. In looking at the careers of thousands of scientists, as measured by influential publications, the group found that scientists generally do conduct their best work within the first two decades of their careers, but that they also the most productive during this time — all of which suggests that success is linked to the volume of work conducted. Further, the team found that a scientist's highest-impact papers were rarely their earliest ones, and that the biggest hits occurred at random.