<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Dillon, Megan L.</style></author><author><style face="normal" font="default" size="100%">Ian Hawes</style></author><author><style face="normal" font="default" size="100%">Jungblut, Anne D.</style></author><author><style face="normal" font="default" size="100%">Mackey, Tyler J.</style></author><author><style face="normal" font="default" size="100%">Eisen, Jonathan A.</style></author><author><style face="normal" font="default" size="100%">Peter T. Doran</style></author><author><style face="normal" font="default" size="100%">Sumner, Dawn Y.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Energetic and environmental constraints on the community structure of benthic microbial mats in Lake Fryxell, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">FEMS Microbiology Ecology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Antarctica</style></keyword><keyword><style  face="normal" font="default" size="100%">energy</style></keyword><keyword><style  face="normal" font="default" size="100%">Lake Fryxell</style></keyword><keyword><style  face="normal" font="default" size="100%">microbial mat</style></keyword><keyword><style  face="normal" font="default" size="100%">Oxygen</style></keyword><keyword><style  face="normal" font="default" size="100%">Photosynthetically Active Radiation</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2020</style></year><pub-dates><date><style  face="normal" font="default" size="100%">02/2020</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://academic.oup.com/femsec/article/96/2/fiz207/5697196</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">96</style></volume><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Ecological communities are regulated by the flow of energy through environments. Energy flow is typically limited by access to photosynthetically active radiation (PAR) and oxygen concentration (O&lt;sub&gt;2&lt;/sub&gt;). The microbial mats growing on the bottom of Lake Fryxell, Antarctica, have well-defined environmental gradients in PAR and (O&lt;sub&gt;2&lt;/sub&gt;). We analyzed the metagenomes of layers from these microbial mats to test the extent to which access to oxygen and light controls community structure. We found variation in the diversity and relative abundances of Archaea, Bacteria and Eukaryotes across three (O&lt;sub&gt;2&lt;/sub&gt;) and PAR conditions: high (O&lt;sub&gt;2&lt;/sub&gt;) and maximum PAR, variable (O&lt;sub&gt;2&lt;/sub&gt;) with lower maximum PAR, and low (O&lt;sub&gt;2&lt;/sub&gt;) and maximum PAR. We found distinct communities structured by the optimization of energy use on a millimeter-scale across these conditions. In mat layers where (O&lt;sub&gt;2&lt;/sub&gt;) was saturated, PAR structured the community. In contrast, (O&lt;sub&gt;2&lt;/sub&gt;) positively correlated with diversity and affected the distribution of dominant populations across the three habitats, suggesting that meter-scale diversity is structured by energy availability. Microbial communities changed across covarying gradients of PAR and (O&lt;sub&gt;2&lt;/sub&gt;). The comprehensive metagenomic analysis suggests that the benthic microbial communities in Lake Fryxell are structured by energy flow across both meter- and millimeter-scales.&lt;/p&gt;</style></abstract><issue><style face="normal" font="default" size="100%">2</style></issue></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Matys, Emily D.</style></author><author><style face="normal" font="default" size="100%">Mackey, Tyler J.</style></author><author><style face="normal" font="default" size="100%">Grettenberger, Christen</style></author><author><style face="normal" font="default" size="100%">Mueller, Elliott</style></author><author><style face="normal" font="default" size="100%">Jungblut, Anne D.</style></author><author><style face="normal" font="default" size="100%">Sumner, Dawn Y.</style></author><author><style face="normal" font="default" size="100%">Ian Hawes</style></author><author><style face="normal" font="default" size="100%">Summons, Roger E.</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Environmental controls on bacteriohopanepolyol profiles of benthic microbial mats from Lake Fryxell, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Geobiology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">anammox</style></keyword><keyword><style  face="normal" font="default" size="100%">bacteriohopanepolyol</style></keyword><keyword><style  face="normal" font="default" size="100%">bacteriohopanetetrol isomer</style></keyword><keyword><style  face="normal" font="default" size="100%">biomarker</style></keyword><keyword><style  face="normal" font="default" size="100%">McMurdo Dry Valleys</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2019</style></year><pub-dates><date><style  face="normal" font="default" size="100%">07/2019</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">https://onlinelibrary.wiley.com/doi/full/10.1111/gbi.12353</style></url></web-urls></urls><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">&lt;p&gt;Bacteriohopanepolyols (BHPs) are pentacyclic triterpenoid lipids that contribute to the structural integrity and physiology of some bacteria. Because some BHPs originate from specific classes of bacteria, BHPs have potential as taxonomically and environmentally diagnostic biomarkers. For example, a stereoisomer of bacteriohopanetetrol (informally BHT II) has been associated with anaerobic ammonium oxidation (anammox) bacteria and suboxic to anoxic marine environments where anammox is active. As a result, the detection of BHT II in the sedimentary record and fluctuations in the relative abundance of BHT II may inform reconstructions of nitrogen cycling and ocean redox changes through the geological record. However, there are uncertainties concerning the sources of BHT II and whether or not BHT II is produced in abundance in non‐marine environments, both of which are pertinent to interpretations of BHT II signatures in sediments. To address these questions, we investigate the BHP composition of benthic microbial mats from Lake Fryxell, Antarctica. Lake Fryxell is a perennially ice‐covered lake with a sharp oxycline in a density‐stabilized water column. We describe the diversity and abundance of BHPs in benthic microbial mats across a transect from oxic to anoxic conditions. Generally, BHP abundances and diversity vary with the morphologies of microbial mats, which were previously shown to reflect local environmental conditions, such as irradiance and oxygen and sulfide concentrations. BHT II was identified in mats that exist within oxic to anoxic portions of the lake. However, anammox bacteria have yet to be identified in Lake Fryxell. We examine our results in the context of BHPs as biomarkers in modern and ancient environments.&lt;/p&gt;</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Ian Hawes</style></author><author><style face="normal" font="default" size="100%">H. Giles</style></author><author><style face="normal" font="default" size="100%">Peter T. Doran</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Estimating photosynthetic activity in microbial mats in an ice-covered Antarctic lake using automated oxygen microelectode profiling and variable chlorophyll fluorescence</style></title><secondary-title><style face="normal" font="default" size="100%">Limnology and Oceanography</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2014</style></year><pub-dates><date><style  face="normal" font="default" size="100%">08/2014</style></date></pub-dates></dates><volume><style face="normal" font="default" size="100%">59</style></volume><pages><style face="normal" font="default" size="100%">674-688</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%"> An automated oxygen microprofiler measured a positive flux of oxygen from microbial mats in ice-covered Lake Hoare, Antarctica, from noon, at a photon flux of 20 µmol m−2 s−1, through to midnight (&lt; 2 µmol photons m−2 s−1). Daily average oxygen flux was 200 µmol m−2 h−1; and, whereas it was maximal at noon, when a 10 mm broad concentration peak was observed 5 mm below the mat surface, flux correlated only weakly with irradiance. In contrast, relative electron transfer rate, estimated from variable chlorophyll fluorescence, suggested a linear relationship between photosystem activity and irradiance. This contradiction arose because of the conjunction of photosynthetic production of oxygen deep into these transparent, gelatinous mats (diel oxygen change was observed to 17 mm depth) and oxygen diffusion rates too slow to allow equilibration of oxygen concentration profiles with instantaneous production and consumption of oxygen. To confirm this, we developed a mathematical simulation of oxygen dynamics that included diffusion, photosynthesis, and respiration. The simulation further indicated that (1) net oxygen evolution is light limited is and confined to the upper few millimeters of the mat, (2) below 5–7 mm, respiration balanced photosynthesis, (3) below 17 mm, respiration and photosynthesis approached zero, even though organic carbon and dissolved oxygen were present, and (4) photosynthesis deep into the mat was dependent on high light transmission through the gelatinous matrix. These conclusions are consistent with current understanding of mat growth dynamics and point to approaches for long-term analysis of microbial mat productivity.</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><section><style face="normal" font="default" size="100%">674</style></section></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Burnett, L</style></author><author><style face="normal" font="default" size="100%">Daryl L. Moorhead</style></author><author><style face="normal" font="default" size="100%">Ian Hawes</style></author><author><style face="normal" font="default" size="100%">Clive Howard-Williams</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Environmental factors associated with deep chlorophyll maxima in dry valley lakes, South Victoria Land, Antarctica</style></title><secondary-title><style face="normal" font="default" size="100%">Arctic, Antarctic, and Alpine Research</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2006</style></year></dates><volume><style face="normal" font="default" size="100%">38</style></volume><pages><style face="normal" font="default" size="100%">179-189</style></pages><language><style face="normal" font="default" size="100%">eng</style></language></record></records></xml>