sentences:  The Lake Erie sample exhibited many signals of human habitation, while the Lake Vostok ice samples exhibited no signals of human habitation.The Lake Erie sample also had an almost completely different profile of bacterial and eukaryotic phyla.Russian and French scientists have been carrying out molecular DNA studies of the water from Lake Vostok that was frozen in the borehole, by constructing numerous DNA libraries, which are collections of fragments of DNA that allow scientists to identify which species of bacteria may belong to.