Project description:Bioavailability of electron acceptors is probably the most limiting factor in the restoration of anoxic, contaminated environments. The oxidation of contaminants such as aromatic hydrocarbons, particularly in aquifers, often depends on the reduction of ferric iron or sulphate. We have previously detected a highly active fringe zone beneath a toluene plume at a tar-oil contaminated aquifer in Germany, where a specialized community of contaminant degraders co-dominated by Desulfobulbaceae and Geobacteraceae had established. Although on-site geochemistry links degradation to sulphidogenic processes, dominating catabolic (benzylsuccinate synthase alpha-subunit, bssA) genes detected in situ appeared more related to those of Geobacter spp. Therefore, a stable isotope probing (SIP) incubation of sediment samples with 13C7-toluene and comparative electron acceptor amendment was performed. We introduce pyrosequencing of templates from SIP microcosms as a powerful new strategy in SIP gradient interpretation (Pyro-SIP). Our results reveal the central role of Desulfobulbaceae for sulphidogenic toluene degradation in situ, and affiliate the detected bssA genes to this lineage. This, and the absence of 13C-labelled DNA of Geobacter spp. in SIP gradients preclude their relevance as toluene degraders in situ. In contrast, Betaproteobacteria related to Georgfuchsia spp. became labelled under iron-reducing conditions. Furthermore, secondary toluene degraders belonging to the Peptococcaceae detected in both treatments suggest the possibility of functional redundancy amongst anaerobic toluene degraders on site.

2011-03-18 | GSE25449 | GEO

SIP Identifies a Network of Dosage Compensation Condensin I Loops

Project description:Chromatin loops are a major componant of 3D nuclear organization that appear as intense point-to-point interactions in Hi-C maps. Identification of these loops is an important part of Hi-C analysis. We present SIP, Significant Interaction Peak caller, a platform independent program to identify these loops in a time and memory efficient manner and which is resistant to noise and sequencing depth. We also present a companion tool, SIPMeta, to create more visually accurate average plots of Hi-C and HiChIP data. We then demonstrate that use of SIP and SIPMeta can lead to biological insight through characterizing the contribution of several transcription factors to CTCF loops in human cells. We then use SIP and SIPMeta to discover loops associated with condensin IDCC in C. elegans and confirm these loops by HiChIP. These loops form a network of interactions and likely explain the partial condensation of dosage compensated X chromosomes in hermaphrodites.

2020-02-04 | GSE132640 | GEO