Enhanced expression of Ang-(1-7) during pregnancy

Pregnancy is a physiological condition characterized by a progressive increase of the different components of the renin-angiotensin system (RAS). The physiological consequences of the stimulated RAS in normal pregnancy are incompletely understood, and even less understood is the question of how this system may be altered and contribute to the hypertensive disorders of pregnancy. Findings from our group have provided novel insights into how the RAS may contribute to the physiological condition of pregnancy by showing that pregnancy increases the expression of both the vasodilator heptapeptide of the RAS, angiotensin-(1-7) [Ang-(1-7)], and of a newly cloned angiotensin converting enzyme (ACE) homolog, ACE2, that shows high catalytic efficiency for Ang II metabolism to Ang-(1-7). The discovery of ACE2 adds a new dimension to the complexity of the RAS by providing a new arm that may counter-regulate the activity of the vasoconstrictor component, while amplifying the vasodilator component. The studies reviewed in this article demonstrate that Ang-(1-7) increases in plasma and urine of normal pregnant women. In preeclamptic subjects we showed that plasma Ang-(1-7) was suppressed as compared to the levels found in normal pregnancy. In addition, kidney and urinary levels of Ang-(1-7) were increased in pregnant rats coinciding with the enhanced detection and expression of ACE2. These findings support the concept that in normal pregnancy enhanced ACE2 may counteract the elevation in tissue and circulating Ang II by increasing the rate of conversion to Ang-(1-7). These findings provide a basis for the physiological role of Ang-(1-7) and ACE2 during pregnancy

Enhanced expression of Ang-(1-7) during pregnancy

Pregnancy is a physiological condition characterized by a progressive increase of the different components of the renin-angiotensin system (RAS). The physiological consequences of the stimulated RAS in normal pregnancy are incompletely understood, and even less understood is the question of how this system may be altered and contribute to the hypertensive disorders of pregnancy. Findings from our group have provided novel insights into how the RAS may contribute to the physiological condition of pregnancy by showing that pregnancy increases the expression of both the vasodilator heptapeptide of the RAS, angiotensin-(1-7) [Ang-(1-7)], and of a newly cloned angiotensin converting enzyme (ACE) homolog, ACE2, that shows high catalytic efficiency for Ang II metabolism to Ang-(1-7). The discovery of ACE2 adds a new dimension to the complexity of the RAS by providing a new arm that may counter-regulate the activity of the vasoconstrictor component, while amplifying the vasodilator component. The studies reviewed in this article demonstrate that Ang-(1-7) increases in plasma and urine of normal pregnant women. In preeclamptic subjects we showed that plasma Ang-(1-7) was suppressed as compared to the levels found in normal pregnancy. In addition, kidney and urinary levels of Ang-(1-7) were increased in pregnant rats coinciding with the enhanced detection and expression of ACE2. These findings support the concept that in normal pregnancy enhanced ACE2 may counteract the elevation in tissue and circulating Ang II by increasing the rate of conversion to Ang-(1-7). These findings provide a basis for the physiological role of Ang-(1-7) and ACE2 during pregnancy

Desulfovibrio strain PCS, a novel metal reducing pleomorphic sulfate reducing bacterium

ABSTRACT=A sulfate reducing bacterium was isolated from the Paleta Creek site in San Diego Bay with 60mM lactate as the sole carbon source and electron donor, and 50mM sulfate as the electron acceptor. The novel isolate, strain PCS is an anaerobic, non-sporulating, gram-negative organism that is highly motile. The optimum temperature for growth of strain PCS was determined to be 370C. Preliminary 16S rDNA analysis revealed that the closest relative to strain PCS is Desulfovibrio africanus (98 % similar). Light microscopy and SEM images of individual cells reveal sigmoid morphology. Cells of strain PCS appear like slender curved rods during the early log phase and spiral in exponential/stationery phase to approx 5-10mM in length and 0.2mM in width. In this regard, strain PCS is less than half the width of its closest known relative D.africanus. The images also reveal the presence of lemon shaped/spherical structures approx 1mM in diameter especially in early log and stationa

Characterization of Stress Response in a Sulfate Reducer/Methanogen Coculture

Sulfate-reducing bacteria and methanogens are found to coexist in a variety of anoxic marine sediments. In these systems they either compete for substrates or engage in successful syntrophic relationships. In our experimental setup, Desulfovibrio vulgaris Hildenborough ferments lactate, producing acetate and hydrogen. Methanococcus maripaludis, a hydrogenotrophic methanogen, then utilizes hydrogen while also incorporating limited amounts of acetate as a carbon source. Mid-log growth phase of this co-culture is achieved in 3 days growing at 37oC at which point, nearly 50percent of the initial lactate was depleted. In this study we investigate the stress response of this coculture and compare it to the D. vulgaris monoculture. Minimum Inhibitory Concentration (MIC) determinations of two environmentally relevant stressors (NO3- and NaCl) on the coculture and monoculture suggest nitrate predominantly affects M. maripaludis with a MIC of 25mM while sodium stress affects D. vulgaris with a MIC of 100mM. The response of the coculture to stressors like nitrate, nitrite, salt and peroxide was monitored by several methods. The fate of metabolites was tracked in the cultures and rates of gas evolution/utilization were measured with the Micro-Oxymax. Total biomass was measured over time with direct cell counts (including ratios of SRB: methanogen), cell protein and optical density. Metal reducing capability of log phase co-culture under NO3 stress was investigated and compared to that of under NaCl stress. Phenotype Microarray substrate utilization profiles generated by the Omnilog technology for a variety of metabolic substrates showed differential profiles for the coculture and the monoculture. Whole-genome transcriptional analysis of NaCl stressed coculture indicates up-regulation of genes coding for numerous transmembrane electron transfer enzymes

Characterization of Stress Response in a Sulfate Reducer/Methanogen Coculture

Sulfate-reducing bacteria and methanogens are found to coexist in a variety of anoxic marine sediments. In these systems they either compete for substrates or engage in successful syntrophic relationships. In our experimental setup, Desulfovibrio vulgaris Hildenborough ferments lactate, producing acetate and hydrogen. Methanococcus maripaludis, a hydrogenotrophic methanogen, then utilizes hydrogen while also incorporating limited amounts of acetate as a carbon source. Mid-log growth phase of this co-culture is achieved in 3 days growing at 37oC at which point, nearly 50percent of the initial lactate was depleted. In this study we investigate the stress response of this coculture and compare it to the D. vulgaris monoculture. Minimum Inhibitory Concentration (MIC) determinations of two environmentally relevant stressors (NO3- and NaCl) on the coculture and monoculture suggest nitrate predominantly affects M. maripaludis with a MIC of 25mM while sodium stress affects D. vulgaris with a MIC of 100mM. The response of the coculture to stressors like nitrate, nitrite, salt and peroxide was monitored by several methods. The fate of metabolites was tracked in the cultures and rates of gas evolution/utilization were measured with the Micro-Oxymax. Total biomass was measured over time with direct cell counts (including ratios of SRB: methanogen), cell protein and optical density. Metal reducing capability of log phase co-culture under NO3 stress was investigated and compared to that of under NaCl stress. Phenotype Microarray substrate utilization profiles generated by the Omnilog technology for a variety of metabolic substrates showed differential profiles for the coculture and the monoculture. Whole-genome transcriptional analysis of NaCl stressed coculture indicates up-regulation of genes coding for numerous transmembrane electron transfer enzymes

A Conceptual model of coupled biogeochemical and hydrogeological processes affected by in situ Cr(VI) bioreduction in groundwater at Hanford 100H Site

The overall objective of this presentation is to demonstrate a conceptual multiscale, multidomain model of coupling of biogeochemical and hydrogeological processes during bioremediation of Cr(VI) contaminated groundwater at Hanford 100H site. A slow release polylactate, Hydrogen Release Compound (HRCTM), was injected in Hanford sediments to stimulate immobilization of Cr(VI). The HRC injection induced a 2-order-of-magnitude increase in biomass and the onset of reducing biogeochemical conditions [e.g., redox potential decreased from +240 to -130 mV and dissolved oxygen (DO) was completely removed]. A three-well system, comprised of an injection well and upgradient and downgradient monitoring wells, was used for conducting the in situ biostimulation, one regional flow (no-pumping) tracer test, and five pumping tests along with the Br-tracer injection. Field measurements were conducted using a Br ion-selective electrode and a multiparameter flow cell to collect hourly data on temperature, pH, redox potential, electrical conductivity, and DO. Groundwater sampling was conducted by pumping through specially designed borehole water samplers. Cross-borehole radar tomography and seismic measurements were carried out to assess the site background lithological heterogeneity and the migration pathways of HRC byproducts through groundwater after the HRC injection

Comparison of Desulfovibrio vulgaris Hildenborough response to microaerobic and aerobic exposure

Though considered obligate anaerobes for many years after their discovery, sulfate reducing bacteria like Desulfovibrio vulgaris Hildenborough (DvH) are found in environments with very low sulfate and in many environments that are regularly exposed to oxygen or are normally aerobic. The best growth condition for DvH, measured as increase in biomass, remains a completely anaerobic environment. However, DvH is clearly able to tolerate sub-aerobic environments and can survive exposure to air for up to 20 days. Controlled experiments were conducted to expose DvH to aerobic and microaerobic conditions (0.1% O2). Cell-wide responses were monitored via transcriptomics and proteomics measurements. Microaerobic conditions caused an overall decrease in growth without affecting the viability of the bacterium. Cellular responses to microaerobic conditions were mild and primarily included up-regulation of the putative PerR regulon, but other known oxidative stress response candidates remained unchanged. Other transcripts that show an expression profile similar to the PerR regulon genes included the cydA/B operon, encoding putative oxidative phosphorylation proteins. However, comparison with data from prior DvH functional genomics studies suggested that many of these changes could be part of a general stress response in DvH. In contrast, exposure to air produced drastic changes at both the transcriptome and proteome levels and had a detrimental effect on both growth and viability of DvH. During aerobic stress, increases in proteases and chaperones signified air exposure to be a very harsh stress in DvH. However, quantitative proteomics also indicated an accumulation of superoxide-dismutase, catalase as well as ferritins and thioredoxins, and these candidates may be critical for the survival of the small fraction of cells which survive air exposure. Our results indicated that DvH has very different responses towards microaerobic vs. aerobic exposure. Growth of DvH strains under these different O2 exposures and the data from our integrated genomics experiment are presented and have been used to improve the model for O2 stress response in DvH