MICROBIAL ECOLOGY OF A MANMADE OIL SPILL IN THE GULF OF MEXICO AND A NATURAL, HYDROTHERMAL OIL SEEP IN THE GULF OF CALIFORNIA

Members of the Marinobacter genus play an important role in hydrocarbon degradation in the ocean - a topic of special significance in light of the recent Deepwater Horizon oil spill of 2010. The Marinobacter group has thus far lacked a genus level phylogenetic probe that would allow in situ identification of representative members. Here, two new 16S rRNA-targeted oligonucleotide probes (Mrb-0625-a and Mrb-0625-b) were developed to enumerate Marinobacter species by fluorescence in situ hybridization (FISH). In silico analysis of this probe set demonstrated 80% coverage of the Marinobacter genus. A competitor probe was developed to block hybridization by Mrb-0625-a to six Halomonas species with which it shared a one base pair mismatch. The probe set was optimized using pure cultures, and then used in an enrichment experiment with a deep sea oil plume water sample collected from the Deepwater Horizon oil spill. Marinobacter cells rapidly increased as a significant fraction of total microbial abundance in all incubations of original contaminated seawater as well as those amended with n-hexadecane, suggesting this group may be among the first microbial responders to oil pollution in the marine environment. The new probe set will provide a reliable tool for quantifying Marinobacter in the marine environment, particularly at contaminated sites where these organisms can play an important role in the biodegradation of oil pollutants. The next sections of this dissertation focus on the hydrothermally active sediments at Guaymas Basin, which show a wide range of shallow subsurface temperatures: from 3°C to 200°C in the first 45 cm depth. A combination of extreme thermal gradients and compressed geochemical and metabolic zones limits the depth range of microbial colonization in Guaymas sediments. Using stable carbon isotopic values for methane and dissolved inorganic carbon compared to associated temperatures the upper thermal limits for the anaerobic oxidation of methane and organic carbon remineralization in Guaymas sediments are suggested to be 80oC and 100oC, respectively. At higher temperatures the isotopic imprints of these microbially mediated processes cannot be detected. Additionally, 16S rRNA gene clone libraries demonstrate differential biogeographical zonation patterns for archaea versus bacteria, with archaeal community structure being more heavily influenced by hydrothermal regimes. Chloroflexi and Deltaproteobacteria dominated the bacterial clone libraries, and anaerobic methane-oxidizing (ANME) archaea represented nearly half of the total archaeal clone library. Thermal zonation of ANME archaeal subgroups is strong: ANME-2c is restricted to low temperature sediments (<25oC), ANME-1 is dominant at warmer temperatures, and the ANME-1 Guaymas archaea appear to have access to the deepest and hottest sediment horizons up to approximately 80oC. In the last chapter of this dissertation, microbial life at extreme temperatures was investigated further by RNA-based methodologies. Using push core samples collected by the Alvin submarine at four high temperature sites with 40-cmsbf thermal maxima ranging from 100°C to 185°C, the composition of the active microbial community and its possible influence on carbon and sulfur cycling was investigated. Here, evidence is presented indicating that hydrothermal fluctuations are frequent enough to restrict hyperthermophilic life to sediments with average in situ temperatures between 70°C and 95°C, where temperatures may vary by 25°C in as little as a day. Strong microbially mediated sulfate reduction is implicated by sharp decreases in porewater sulfate within the upper 15 cm of all four high temperature cores, while stable isotopic evidence of methane oxidation is only expressed in a single core. Archaeal sequence recovery was greater than bacterial sequence recovery in six out of eight samples from the four cores, but bacterial sequence recovery was particularly strong for a single core, yielding 35% of the total archaeal and bacterial recovery from all samples. Although putative anaerobic methane oxidizing (ANME) archaea were very common, distinct cores hosted diverse and distinct sequence assemblages, including ANME-1 Guaymas, ANME-2c, and ANME-2d/GoM Arc-1/Methanoperedenaceae. Dominant bacterial groups fell within the Thermodesulfobacteriaceae family in the Thermodesulfobacteria phylum, the Helicobacteriaceae family in the subphylum Epsilonproteobacteria, or were close relatives of Desulfocapsa exigens in the subphylum Deltaproteobacteria. The most probable thermo- or hyperthermophilic groups were investigated by co-occurrence of OTUs across the four hottest samples within the sediment cores and appear to be ANME-1 Guaymas and an uncultured representative of the Miscellaneous Crenarchaeotal Group (MCG)-15 for archaea, and members of the Thermodesulfobacteriaceae family for bacteria.Doctor of Philosoph

Spatial heterogeneity of phylogenetically diverse orange and white Beggiatoa mats in Guaymas Basin hydrothermal sediments

Sulfide-oxidizing bacteria of the genus Beggiatoa form colorful mats on the seafloor above active hydrothermal seeps at Guaymas Basin. 113 temperature profiles were taken around 15 Beggiatoa mats to investigate spatial relationships between mat color and hydrothermal seeps. Average in situ temperatures of phylogenetically diverse orange and white filaments are 8-12 degree C, indicating that Guaymas Beggiatoa live in relatively cool conditions. Average temperatures 40 centimeters beneath all Beggiatoa mats are approximately 90C. Orange filaments are usually concentrated over hotter subsurface temperatures in the center of a mat than the major concentration of white filaments at the periphery; however, the range of subsurface temperatures changes from one mat to another. Elevated temperature profiles beneath orange Beggiatoa correlate with the shallowest sulfide accumulation maxima. We propose that spatial heterogeneity of orange and white filaments in a Guaymas Beggiatoa mat is controlled by delivery of, and proximity to, energy sources in the shallow subsurface

What Do Healthy Rural Economies Look Like in the U.S., and How Might Conservation Organizations Help Support Them?

Report of the 2012 Berkley Workshop Held at the Wingspread Conference Center, Racine,WI - July 201

Speculative Aesthetics

This series of interventions on the ramifications of Speculative Realism for aesthetics ranges from contemporary art’s relation to the aesthetic, to accelerationism and abstraction, logic and design. From varied perspectives of philosophy, art and design, participants examine the new technological mediations between the human sensorium and the massive planetary media network within which it now exists, and consider how the aesthetic enables new modes of knowledge by processing sensory data through symbolic formalisms and technological devices. Speculative Aesthetics anticipates the possibility of a theory and practice no longer invested in the otherworldly promise of the aesthetic, but acknowledging the real force and traction of images in the world today, experimentally employing techniques of modelling, formalisation, and presentation so as to simultaneously engineer new domains of experience and map them through a reconfigured aesthetics that is inseparable from its sociotechnical conditions

Clinical and surgical management of holocervical spinal cord ependymomas.

Background:Spinal ependymomas are rare tumors of the central nervous system, and those spanning the entire cervical spine are atypical. Here, we present two unusual cases of holocervical (C1-C7) spinal ependymomas. Case Description:Two patients, a 32-year-old female and a 24-year-old male presented with neck pain, motor, and sensory deficits. Sagittal MRI confirmed hypointense lesions on T1 and hyperintense regions on T2 spanning the entire cervical spine. These were accompanied by cystic cavities extending caudally into the thoracic spine and rostrally to the cervicomedullary junction. Both patients underwent gross total resection of these lesions and sustained excellent recoveries. Conclusion:Two holocervical cord intramedullary ependymomas were safely and effectively surgically resected without incurring significant perioperative morbidity

Timing is everything, but does it really matter? Impact of 8-weeks morning versus evening iron supplementation in ballet and contemporary dancers

The effectiveness of a morning versus evening oral iron supplement strategy to increase iron stores was explored. Ballet and contemporary dancers with serum ferritin (sFer) \u3c 50 g/L (n = 14), were supplemented daily with 105 mg elemental oral iron in either the morning (FeAM) or evening (FePM) for 8 weeks. A control group (n = 6) with sFer \u3e 50 g/L were given no supplement over the same period. Dancers’ sFer were measured at baseline and post-intervention. Assessment of daily training load, dietary intake, and menstruation were made. A significant interaction (p \u3c 0.001) showed the within group sFer change over the 8-week intervention in FeAM (+25.9 ± 10.5 g/L) and FePM, (+22.3 ± 13.6 g/L) was significantly different to CON (−30.17 ± 28.7 g/L; both p = 0.001). This change was not different between FeAM and FePM (p = 0.778). sFer levels within FeAM and FePM significantly increased over the 8-weeks; however, they significantly decreased in the CON group (all p \u3c 0.05). Post-intervention sFer levels were no longer different between the three groups (p \u3e 0.05). Training load, dietary intake, and number of menstrual cycles incurred were similar between FeAM and FePM (p \u3e 0.05). Oral iron supplementation in either the morning or evening appears equally effective in increasing sFer levels in dancers with sub-optimal iron status

Dietary iron and the elite dancer

Dancers are an athlete population at high risk of developing iron deficiency (ID). The aesthetic nature of the discipline means dancers potentially utilise dietary restriction to meet physique goals. In combination with high training demands, this means dancers are susceptible to problems related to low energy availability (LEA), which impacts nutrient intake. In the presence of LEA, ID is common because of a reduced mineral content within the low energy diet. Left untreated, ID becomes an issue that results in fatigue, reduced aerobic work capacity, and ultimately, iron deficient anaemia (IDA). Such progression can be detrimental to a dancer’s capacity given the physically demanding nature of training, rehearsal, and performances. Previous literature has focused on the manifestation and treatment of ID primarily in the context of endurance athletes; however, a dance-specific context addressing the interplay between dance training and performance, LEA and ID is essential for practitioners working in this space. By consolidating findings from identified studies of dancers and other relevant athlete groups, this review explores causal factors of ID and potential treatment strategies for dancers to optimise absorption from an oral iron supplementation regime to adequately support health and performance