Ion Torrent of  Vostok Basal Ice
Quartered sections from the Vostok (Antarctica) 5G ice core were surface sterilized and meltwater was collected in 50 ml aliquots. Meltwater from each section (as well as a control sample consisting of sterile ultrapure water) was then subjected to ultracentrifugation at 100,000 xg. Each pellet was rehydrated in 50 ul of sterile ultrapure water. Each sample was divided into two equal parts. One was subjected to nucleic acid extraction and the other was subjected to ribonucleic acid extraction. Equal volumes from each sample were combined together and cDNA was synthesized from the RNA using random primers. Then, EcoRI (NotI) adapters were ligated onto the cDNA and DNA. Each sample was then fractionated and the cDNA and DNA was amplified by PCR, using EcoRI(Not) primers. Fractions between the 100 bp and 1 kb (as determined by agarose gels) were pooled for further processing. Each sample was then amplified again with primers that contained EcoRI (NotI) sequences on the 3 end, multiplex identifier sequences (MID tags) in the middle (unique for each section), and either an A-key or P1-key sequence on the 5 end. These were paired for each PCR reaction. The amplified products were purified, pooled, and mailed to University of Pennsylvania Core Sequencing Lab for Ion Torrent sequencing. The returned sequences were separated in silico based on their MID sequences (corresponding to each of the ice core sections). After clipping off the primer sequences, the sequences were subjected to BLAST analysis. The data from the BLAST analysis was then used to retrieve taxonomic and gene information.