Solving problems of clustering and classification of cancer diseases based on DNA methylation data

The article deals with the problem of diagnosis of oncological diseases based on the analysis of DNA methylation data using algorithms of cluster analysis and supervised learning. The groups of genes are identified, methylation patterns of which significantly change when cancer appears. High accuracy is achieved in classification of patients impacted by different cancer types and in identification if the cell taken from a certain tissue is aberrant or normal. With method of cluster analysis two cancer types are highlighted for which the hypothesis was confirmed stating that among the people affected by certain cancer types there are groups with principally different methylation pattern

Evidence for middle Eocene Arctic sea ice from diatoms and ice-rafted debris

Oceanic sediments from long cores drilled on the Lomonosov ridge, in the central Arctic1, contain ice-rafted debris (IRD) back to the middle Eocene epoch, prompting recent suggestions that ice appeared in the Arctic about 46 million years (Myr) ago2, 3. However, because IRD can be transported by icebergs (derived from land-based ice) and also by sea ice4, IRD records2, 3 are restricted to providing a history of general ice-rafting only. It is critical to differentiate sea ice from glacial (land-based) ice as climate feedback mechanisms vary and global impacts differ between these systems: sea ice directly affects ocean–atmosphere exchanges5, whereas land-based ice affects sea level and consequently ocean acidity6. An earlier report3 assumed that sea ice was prevalent in the middle Eocene Arctic on the basis of IRD, and although somewhat preliminary supportive evidence exists2, these data are neither comprehensive nor quantified. Here we show the presence of middle Eocene Arctic sea ice from an extraordinary abundance of a group of sea-ice-dependent fossil diatoms (Synedropsis spp.). Analysis of quartz grain textural characteristics further supports sea ice as the dominant transporter of IRD at this time. Together with new information on cosmopolitan diatoms and existing IRD records2, our data strongly suggest a two-phase establishment of sea ice: initial episodic formation in marginal shelf areas 47.5 Myr ago, followed 0.5 Myr later by the onset of seasonally paced sea-ice formation in offshore areas of the central Arctic. Our data establish a 2-Myr record of sea ice, documenting the transition from a warm, ice-free3 environment to one dominated by winter sea ice at the start of the middle Eocene climatic cooling phase7.<br/

The impacts of climate change on circumpolar biodiversity

Some of the most rapidly changing ecosystems on our planet are located in the polar regions (IPCC 2007; Turner et al. 2009; SWIPA 2011). In some areas of the Arctic and Antarctic, atmospheric temperatures are rising at rates more than double the global average. In addition, there are other direct human impacts on polar regions such as pollution, exploitation and development. Polar ecosystems and the biodiversity they support are already responding to this change and it is expected that even more profound impacts will occur this century. Compounding the risk to polar biodiversity is the fact that many polar ecosystems have limited functional redundancy; in the event of the loss of a single keystone species, they may potentially be exposed to cascading effects and complete ecosystem restructuring (Post et al. 2009). Rapid climate change affecting the polar regions will also have profound physical and ecological consequences for the rest of the planet since the ice-covered Arctic Ocean, the Antarctic continent, and the globally significant Antarctic Circumpolar Current (ACC) serve a key role in regulating the Earth’s climate and ocean systems. This special issue is intended to provide an overview of circumpolar change that crosses disciplines, systems, taxonomic groups and regions, and integrates papers that address a range of topics including: the monitoring of freshwater, marine, and terrestrial organisms in both the northern and southern polar regions, the role of protected areas in monitoring change in a warming world, polar resource management and development, impacts on northern indigenous peoples, case studies of the biodiversity of selected polar organisms, impacts of sea ice loss on terrestrial and marine organisms and ecosystems, interconnections with lower latitudes, and the influence of historical processes that have impacted polar diversity. This keynote paper is intended to provide background and insight into the issue by comparing and contrasting the Arctic and Antarctic regions in terms of their physical environment, human influences, indications of climate change and impacts on their biodiversity