Resarch Rotation Talks

Re-Analyzing Dust Events from the Taklamakan and Gobi Deserts in East Asia
Russell Deitrick
Department of Astronomy
University of Washington

Dust storms associated with the Taklamakan and Gobi deserts in East Asia have gradually decreased in frequency over the last 50 years. Wang et al. (2008) analyzed visibility data recorded by 4 stations around each desert and found that there is a correlation between the dust events and the global temperature increase over this time frame. Indeed, as polar temperatures increase more rapidly than tropical temperature, we would expect that westerly winds over Asia would weaken, and consequently dust events would become less common. We have done a brief re-analysis of the dust data and further investigated correlations with surface temperature, soil moisture, wind speeds, and arctic sea ice. While we can confirm prior results that the decrease in dust frequency does correlate with rising temperatures in Siberia, once global warming trends are removed we find little correlation between dust and other the climate factors we have investigated, thus weakening the evidence for a direct connection. These results highlight the importance of detrending and the need for a longer time baseline.

Presence and Diversity of Reverse Transcriptase and Other Retroelements in Hydrothermal Vents
Anna Simpson
Department of Forestry
University of Washington

Viruses may have existed before the development of the modern cell, and viral genes incorporated into deeply rooted prokaryotic lineages such as thermophilic archaea found in hydrothermal vents may be relics of a pre-LUCA world. There is strong evidence that the shift from RNA to DNA first took place in viruses, and that viral reverse transcriptase genes were responsible for the adoption of DNA in cellular genomes. The evolution of viral reverse transcriptase genes, and reverse transcriptase sequences in bacteria and archaea of viral origin, may hold clues to the origins of modern cells. Working with Dr. Rika Anderson and Dr. John Baross, I explored the presence and diversity of reverse transcriptase, as well as the presence of retroviral integrase and diversity-generating retro-elements, in hydrothermal vent metagenomes of Lost City and Hulk Vent (both cellular and viral) and in the genomes of thermophilic archaea. The Hulk Vent virome in particular contained many sequences closely related to the non-LTR class of retrotransposons, the most deeply rooted class of reverse transcriptase/retrotransposons. Vent viromes appear to be more enriched in the mostly-defunct retrotransposons or endogenous retroviruses found in plants and animals than in the sequences found in retroviruses.