Project description:We investigated the functional gene expression changes associated with temperature stress in two psychrophilic sea ice bacteria, Polaribacter sp. ALD9 and Shewanella sp. ALD11.
Project description:Proteorhodopsin has been an ongoing hot topic for the past decade. However the complete physiological role of this extremely widely distributed protein remains mysterious. In this study we aim to give an insight to the physiology of a proteorhodopsin-containing sea ice bacteria – Psychroflexus torquis using gel-free label-free proteomic approach for the first time. We also addressed the life strategy that used by this organism to successfully inhabit extreme sea ice environment.
Project description:The effects of ocean acidification (OA) on nitrous oxide (N2O) production and on the community composition of ammonium oxidising archaea (AOA) were examined in the northern and southern sub-polar and polar Atlantic Ocean. Two research cruises were performed during June 2012 between the North Sea and Arctic Greenland and Barent Seas, and in January-February 2013 to the Antarctic Scotia Sea. Seven stations were occupied in all during which shipboard experimental manipulations of the carbonate chemistry were performed through additions of NaHCO3- + HCl in order to examine the impact of short- term (48 hour for N2O and between 96 and 168 hour for AOA) exposure to control and elevated conditions of OA. During each experiment, triplicate incubations were performed at ambient conditions and at 3 lowered levels of pH which varied between 0.06 and 0.4 units according to the total scale and which were targeted at CO2 partial pressures of ~500, 750 and 1000 μatm. The AOA assemblage in both Arctic and Antarctic regions was dominated by two major archetypes that represent the marine AOA clades most often detected in seawater. There were no significant changes in AOA assemblage composition between the beginning and end of the incubation experiments. N2O production was sensitive to decreasing pHT at all stations and decreased by between 2.4 and 44% with reduced pHT values of between 0.06 and 0.4. The reduction in N2O yield from nitrification was directly related to a decrease of between 28 and 67% in available NH3 as a result of the pH driven shift in the NH3:NH4+ equilibrium. The maximum reduction in N2O production at conditions projected for the end of the 21st century was estimated to be 0.82 Tg N y-1.
Project description:In order to understand the chronic hypoxia (CH) effect upon the absence of dystrophin, Drosophila melanogaster wild type and the model for DMD (dmDys), in which all dystrophins expression was knocked out by iRNA, were exposed to high altitude hypoxia (hypobaric hypoxia) during a 16-day climbing period reaching the summit of Mount McKinley (6194 meters above sea level). Furthermore, dmDys and Drosophila wild type were exposed to normobaric hypoxia (hypoxic chamber) following the same oxygen levels observed during the climbing expedition and to normoxic conditions for comparison. Affymetrix GeneChip® profiling was performed for individual flies from each experimental group. CH-dmDys differentially expressed 1281 genes, whereas control group differentially expressed 57 genes. Eight heat shock protein genes detected in the CH-dmDys microarray study were down-regulated, instead of up-regulated as seen in wild type hypoxic flies. This result suggests a differential gene expression response to CH, which could affect muscle performance.These results suggest that dmDys is more sensitive to CH due to reduced muscle function and hypoxic stress response. In order to understand the chronic hypoxia (CH) effect upon the absence of dystrophin, Drosophila melanogaster wild type and the model for DMD (dmDys), in which all dystrophins expression was knocked out by iRNA, were exposed to high altitude hypoxia (hypobaric hypoxia) during a 16-day climbing period reaching the summit of Mount McKinley (6194 meters above sea level). Furthermore, dmDys and Drosophila wild type were exposed to normobaric hypoxia (hypoxic chamber) following the same oxygen levels observed during the climbing expedition and to normoxic conditions for comparison. Affymetrix GeneChip® profiling was performed for individual flies from each experimental group. CH-dmDys differentially expressed 1281 genes, whereas control group differentially expressed 57 genes. Eight heat shock protein genes detected in the CH-dmDys microarray study were down-regulated, instead of up-regulated as seen in wild type hypoxic flies. This result suggests a differential gene expression response to CH, which could affect muscle performance.These results suggest that dmDys is more sensitive to CH due to reduced muscle function and hypoxic stress response. Overall design: Adults wild type and dystrophic flies (3-5 days old) were exposed to hypobaric hypoxia for two weeks during the summer expedition to Mount McKinley, Alaska (6194 MASL). Another set of wild types and dystrophic flies were exposed to normobaric hypoxia according to the table I obtained during the climbing expedition. During the expedition, the flies were maintained in vials with regular molasses and covered by thermo isolation to avoid low temperature, keeping the temperature at 25C. The experiment performed in the laboratory also used vials with regular molasses and at 25C. Table I. Expedition log book for mount McKinley ascent. Information obtained during the ascent and summit of Mount McKinley, June 1st to June 16th of 2007. The oxygen pressure (PO2) was calculated from the barometric pressure. GNB means go and back from the mentioned point. DAY In order to understand the chronic hypoxia (CH) effect upon the absence of dystrophin, Drosophila melanogaster wild type and the model for DMD (dmDys), in which all dystrophins expression was knocked out by iRNA, were exposed to high altitude hypoxia (hypobaric hypoxia) during a 16-day climbing period reaching the summit of Mount McKinley (6194 meters above sea level). Furthermore, dmDys and Drosophila wild type were exposed to normobaric hypoxia (hypoxic chamber) following the same oxygen levels observed during the climbing expedition and to normoxic conditions for comparison. Affymetrix GeneChip® profiling was performed for individual flies from each experimental group. CH-dmDys differentially expressed 1281 genes, whereas control group differentially expressed 57 genes. Eight heat shock protein genes detected in the CH-dmDys microarray study were down-regulated, instead of up-regulated as seen in wild type hypoxic flies. This result suggests a differential gene expression response to CH, which could affect muscle performance.These results suggest that dmDys is more sensitive to CH due to reduced muscle function and hypoxic stress response. In order to understand the chronic hypoxia (CH) effect upon the absence of dystrophin, Drosophila melanogaster wild type and the model for DMD (dmDys), in which all dystrophins expression was knocked out by iRNA, were exposed to high altitude hypoxia (hypobaric hypoxia) during a 16-day climbing period reaching the summit of Mount McKinley (6194 meters above sea level). Furthermore, dmDys and Drosophila wild type were exposed to normobaric hypoxia (hypoxic chamber) following the same oxygen levels observed during the climbing expedition and to normoxic conditions for comparison. Affymetrix GeneChip® profiling was performed for individual flies from each experimental group. CH-dmDys differentially expressed 1281 genes, whereas control group differentially expressed 57 genes. Eight heat shock protein genes detected in the CH-dmDys microarray study were down-regulated, instead of up-regulated as seen in wild type hypoxic flies. This result suggests a differential gene expression response to CH, which could affect muscle performance.These results suggest that dmDys is more sensitive to CH due to reduced muscle function and hypoxic stress response. Overall design: Adults wild type and dystrophic flies (3-5 days old) were exposed to hypobaric hypoxia for two weeks during the summer expedition to Mount McKinley, Alaska (6194 MASL). Another set of wild types and dystrophic flies were exposed to normobaric hypoxia according to the table I obtained during the climbing expedition. During the expedition, the flies were maintained in vials with regular molasses and covered by thermo isolation to avoid low temperature, keeping the temperature at 25C. The experiment performed in the laboratory also used vials with regular molasses and at 25C. Table I. Expedition log book for mount McKinley ascent. Information obtained during the ascent and summit of Mount McKinley, June 1st to June 16th of 2007. The oxygen pressure (PO2) was calculated from the barometric pressure. GNB means go and back from the mentioned point. DAY LOCATION ALTITUDE m PO2 mmHg (%) 1 Base Camp 2200 123.6 (16.3%) 2 Base Camp 2200 123.6 (16.3%) 3 Base Camp 2200 123.6 (16.3%) 4 Ski Hill 2400 120.7 (15.9%) 5 Kahiltna Pass 2950 113.0 (14.9%) 6 Motorcycle Hill 3350 107.7 (14.2%) 7 Motorcycle Hill 3350 107.7 (14.2%) 8 GNB from Motorcycle 4150 (5 hours) 97.7 (12.9%) 9 Medical Camp 4350 95.3 (12.5%) 10 GNB from Medical Camp 4150 (5 hours) 97.7 (12.9%) 11 Medical Camp 4350 95.3 (12.5%) 12 GNB from Medical Camp 4900 89.0 (11.7%) 13 Medical Camp 4350 95.3 (12.5%) 14 High Camp 5250 85.1 (11.2%) 15 Summit 6194 (0.3 hours) 75.4 (9.9%) 16 High Camp 5250 85.1 (11.2%)