Understanding Initiation with Triethylboron and Oxygen: The Differences between Low-Oxygen and High-Oxygen Regimes

2016 ◽  
Vol 138 (24) ◽  
pp. 7741-7752 ◽  
Author(s):  
Dennis P. Curran ◽  
Timothy R. McFadden
Keyword(s):  
High Oxygen ◽  
Low Oxygen

Fine Temporal Mapping of Plasmodium Falciparum growth Inhibition in Hypoxic Sickle Cell Trait Erythrocytes

Blood ◽  
2017 ◽  
Vol 130 (Suppl_1) ◽  
pp. 924-924
Author(s):  
Natasha Archer ◽  
Nicole Petersen ◽  
Martha Clark ◽  
Manoj Duraisingh
Keyword(s):  
Flow Cytometry ◽  
Carbon Monoxide ◽  
Dna Replication ◽  
Oxygen Tension ◽  
Sickle Cell ◽  
Sickle Cell Trait ◽  
High Oxygen ◽  
Low Oxygen ◽  
Trophozoite Stage ◽  
Sickle Hemoglobin

Abstract Background: Despite the global acceptance of Haldane's hypothesis that individuals with sickle cell trait (AS) are protected against malaria, an exact mechanism of resistance remains unknown. Several theories to explain the resistance such as increased splenic destruction, impaired hemoglobin digestion, reduced cytoadherence and specific translocation of host specific microRNAs have been proposed. Here we carefully examine the influence of hypoxia and its relation to parasite cytoadherence and growth in AS and normal (AA) human red blood cells (RBCs). Materials and Methods: To assess the influence of oxygen tension on parasite proliferation in AS RBCs, we followed the proliferation of tightly synchronized P. falciparum within AS and AA RBCs at 1, 5, 10, and 17% oxygen by flow cytometry and microscopy. Carbon monoxide (CO) studies were performed by introducing 100% CO gas into our enclosed chamber system every 21 hours to prevent sickling at low oxygen. Results: Flow cytometry assessment of DNA content confirms the absence of DNA replication within parasites in AS erythrocytes at low oxygen, however normal DNA replication is observed in the presence of high oxygen tension and when CO is introduced at low oxygen. Moving parasites from high to low oxygen tension greatly influences the extent of parasite maturity; parasites moved at 16 and 20 hours post invasion (hpi) do not mature beyond that of the late ring/early trophozoite stage while parasites moved at 24, 28, and 32 hpi develop increasingly more merozoites. Conclusion: Here, we show that in hypoxic conditions parasites in AS erythrocytes stall at the late ring/early trophozoite stage and do not replicate their DNA. We also show that treatment of AS erythrocytes with high oxygen tension or carbon monoxide, a potent inhibitor of sickle hemoglobin polymerization, reverses this phenotype. We propose that the mechanism of AS protection is largely due to P.falciparum's inability to digest polymerized sickle hemoglobin once the parasite sequesters in the hypoxic microvasculature. This is likely a key driver of the reduced parasite densities observed in actual infections in AS individuals. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

323 INTERACTIONS OF OXYGEN TENSION, GLUCOSE CONCENTRATION, AND HEAT SHOCK ON MATURATION OF BOVINE OOCYTES

2006 ◽  
Vol 18 (2) ◽  
pp. 269
Author(s):  
L. A. de Castro e Paula ◽  
P. J. Hansen
Keyword(s):  
Heat Shock ◽  
Oxygen Tension ◽  
High Glucose ◽  
Glucose Concentration ◽  
High Oxygen ◽  
High Glucose Concentration ◽  
Blastocyst Formation ◽  
Low Oxygen ◽  
Main Effects ◽  
Bovine Oocytes

In many cell types, oxygen tension and glucose concentration affect the magnitude of heat shock effects. Experiments were performed to (1) develop oocyte maturation protocols under high (20.95%) and low (5%) oxygen tensions, and (2) test the hypothesis that low oxygen tension and high glucose concentration reduce the magnitude of the deleterious effects of heat shock on in vitro maturation of bovine oocytes. In Experiment 1, oocytes were matured in tissue culture medium-199 (TCM-199) or synthetic oviduct fluid (SOF) containing 5.6 or 20 mM glucose, under either high or low oxygen. Fertilization was performed under high oxygen and embryos were cultured in KSOM-BE2 under low oxygen. Data were analyzed by least squares analysis of variance using the GLM procedure of SAS (SAS Institute, Inc., Cary, NC, USA), with maturation medium, glucose concentration, and oxygen tension as main effects. Oxygen concentration affected percent blastocyst formation when TCM-199 was used (greater for high oxygen than low oxygen) but not when SOF was used (medium � oxygen, P < 0.05). Similarly, glucose had no effect on percent blastocyst formation under high oxygen but high glucose was superior under low oxygen (glucose � oxygen, P < 0.05). Therefore, SOF with either 5.6 or 20 mM glucose was used to study the effect of heat shock on maturation under high and low oxygen in Experiment 2. Maturation was at 38.5�C for 22 h (control) or 41�C for 12 h and 38.5�C for 10 h (heat shock). Fertilization was performed at 38.5�C under high oxygen and embryos were cultured in KSOM-BE2 under low oxygen at 38.5�C. Data were analyzed as described above with glucose concentration, temperature and oxygen tension as main effects. The experiment was replicated nine times with a total of 3215 embryos. Heat shock decreased the cleavage rate slightly regardless of the maturation conditions (69 � 1% vs. 66 � 1%, P < 0.01). For oocytes matured in 5.6 mM glucose, percent blastocyst formation was greater for high oxygen while there was no effect of oxygen tension for oocytes matured in 20 mM glucose (glucose � oxygen, P < 0.01). Heat shock decreased the percent blastocyst formation under all maturation conditions except for the group matured under high oxygen and high glucose (temperature � oxygen � medium, P = 0.07; temperature � oxygen for oocytes under 5% oxygen; P < 0.05). The percent blastocyst formation for control and heat-shocked oocytes was 25.9% vs. 22.5% (low oxygen-5.6 mM glucose), 41.6% vs. 34.9% (low-20 mM), 41.7% vs. 35.0% (high-5.6 mM), and 37.6% vs. 37.5% (high-20 mM) (SEM = 2.0%). In conclusion, heat shock during maturation under an oxygen tension (5% oxygen) that approaches physiological conditions reduces the percent blastocyst formation. Moreover, a high glucose concentration protects oocytes from heat shock under high oxygen. This work was supported by USDA NRICGP 2002-35203-12664 and CAPES #134202-9.

scholarly journals High Oxygen Level in a Soaking Treatment Improves Early Root and Shoot Development of Black Willow Cuttings

2004 ◽  
Vol 4 ◽  
pp. 899-907 ◽  
Author(s):  
L.T. Martin ◽  
S.R. Pezeshki ◽  
F.D. Shields
Keyword(s):  
Biomass Production ◽  
Shoot Growth ◽  
Rapid Development ◽  
High Oxygen ◽  
Stem Cuttings ◽  
Low Oxygen ◽  
Growth And Survival ◽  
Black Willow ◽  
Shoot Initiation ◽  
High Oxygen Level

Black willow (Salix nigra) stem cuttings are commonly used to stabilize eroded streambanks with survival dependent on rapid development of adventitious roots to maintain plant water balance, absorb nutrients, and provide anchorage and support especially during flood and drought events. Soaking cuttings in water prior to planting increases survival and growth rates, but it is not known whether oxygen content in the soaking water affects the rate of early root and shoot initiation and growth. A laboratory experiment tested the hypothesis that cuttings treated with high oxygen (>95% saturation, 8.62 mg O2l–-1) soaking exhibit more rapid initiation and growth of roots and shoots than cuttings treated with low oxygen (<15% saturation, 1.24 mg O2l-1) soaking and control (unsoaked). Root initiation was enhanced in both high and low O2soaking treatments compared to control (100, 93, and 41%, respectively, n = 27). High O2soaking led to greater root length than low O2soaking during the fourth week after planting (26.5 and 12.3 cm on day 22; 27.7 and 19.1 cm on day 27, respectively). Shoot growth was greater in high O2compared to low O2soaking on days 36 and 56 after planting (9.3 and 6.3 cm on day 36, 10.7 and 7.2 cm on day 56, respectively). Shoot and root biomass production was stimulated in both soaking treatments, with 200% more biomass production by day 59 compared to control. Results of this study demonstrated that a high oxygen soaking treatment has potential for improving early root and shoot growth, and survival in willow cuttings planted at riparian restoration sites.

scholarly journals Hypoxia increases the risk of egg predation in a nest-guarding fish

2016 ◽  
Vol 3 (8) ◽  
pp. 160326 ◽  
Author(s):  
Karin H. Olsson ◽  
Charlotta Kvarnemo ◽  
Maria Norevik Andrén ◽  
Therése Larsson
Keyword(s):  
Carcinus Maenas ◽  
High Oxygen ◽  
Filial Cannibalism ◽  
Defensive Behaviour ◽  
Low Oxygen ◽  
Pomatoschistus Minutus ◽  
Oxygen Treatment ◽  
Large Nest ◽  
Shore Crabs ◽  
Egg Guarding

For fish with parental care, a nest should meet both the oxygenation needs of the eggs and help protect them against predators. While a small nest opening facilitates the latter, it impedes the former and vice versa. We investigated how the presence of potential egg predators in the form of shore crabs Carcinus maenas affects nest building, egg fanning, defensive displays and filial cannibalism of egg-guarding male sand gobies Pomatoschistus minutus under two levels of dissolved oxygen. In the high oxygen treatment, males retained their nest opening size in the presence of crabs, while males in low oxygen built large nest openings both in the absence and presence of crabs, despite the fact that crabs were more likely to successfully intrude into nests with large entrances. Males in low oxygen also fanned more. In the presence of crabs males increased their defensive displays, but while males in high oxygen reduced fanning, males in low oxygen did not. Filial cannibalism was unaffected by treatment. Sand gobies thus prioritize egg ventilation over the protection afforded by small nest openings under hypoxia and adopt defensive behaviour to avert predator attention, even though this does not fully offset the threat from the egg predators.

Getter Effects in Low Oxygen and High Oxygen Czochralski Silicon Wafers

2019 ◽  
Vol 33 (11) ◽  
pp. 113-120 ◽  
Author(s):  
Gudrun Kissinger ◽  
Dawid Kot ◽  
Walter Häckl
Keyword(s):  
Silicon Wafers ◽  
High Oxygen ◽  
Low Oxygen ◽  
Czochralski Silicon

scholarly journals Shifts in microbial transcription patterns prior to onset of Necrotizing enterocolitis may indicate low oxygen levels in the gut

2018 ◽  
Author(s):  
Yonatan Sher ◽  
Matthew R. Olm ◽  
Tali Raveh-Sadka ◽  
Christopher Brown ◽  
Ruth Sher ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Necrotizing Enterocolitis ◽  
Premature Infants ◽  
Oxygen Affinity ◽  
High Oxygen ◽  
Host Cells ◽  
Multiple Time ◽  
List Type ◽  
Low Oxygen ◽  
High Oxygen Affinity

SummaryPremature infants are at risk for developing necrotizing enterocolitis (NEC), an inflammatory disease that can progress to necrosis of gut tissue. Previous attempts have failed to identify any consistent predictor of NEC. We hypothesized that prior to the appearance of NEC symptoms, the gut microbiome shifts in its transcriptional profile. To test this hypothesis we integrated genome-resolved metagenomic and metatranscriptomic data from multiple time-points in the first month of life of four preterm infants, two of whom later developed NEC. Gut microbiomes of NEC infants showed increased transcription of high oxygen affinity cytochrome oxidases and lower transcription of genes to detoxify nitric oxide, an antimicrobial compound released by host cells. These results, and high transcription of H2 production genes, suggest low O2 conditions prior to NEC onset, and are consistent with hypoxic conditions in diseased gut tissue. The findings motivate further testing of transcript data as a predictor of NEC.HighlightsTranscription of high oxygen affinity microbial cytochrome oxidase may predict necrotizing enterocolitis (NEC) development.Lower transcription of microbial genes to detoxify nitric oxide (NO) may also predict NEC development.Higher transcription of H2 production genes by Escherichia sp. was found in the gut of premature infants that develop NEC.

scholarly journals Geology and Production Significance of Dolomite, Arab-D Reservoir, Ghawar Field, Saudi Arabia

GeoArabia ◽  
2001 ◽  
Vol 6 (1) ◽  
pp. 45-60 ◽  
Author(s):  
David L. Cantrell ◽  
Peter K. Swart ◽  
Robertson C. Handford ◽  
Christopher G. Kendall ◽  
Hildegard Westphal
Keyword(s):  
Saudi Arabia ◽  
Quantitative Analysis ◽  
Oxygen Isotope ◽  
High Flow ◽  
High Oxygen ◽  
Reservoir Quality ◽  
Low Oxygen ◽  
Structural Element ◽  
Log Data Analysis ◽  
Ghawar Field

ABSTRACT At least five distinct types of dolomite occur in the Arab-D Reservoir in Ghawar field, Saudi Arabia – one of which appears to be responsible for high flow or ‘super-k’. These dolomite types are distinct petrographically, geochemically and stratigraphically: a finely-crystalline non-fabric-preserving (NFP) variety of dolomite in the lower Arab-D (Zone 3) with low oxygen isotope values and generally poor reservoir quality;a medium-crystalline NFP dolomite with high oxygen isotope values and very poor reservoir quality in the upper Arab-D (Zone 2);a medium to coarsely-crystalline NFP dolomite with low oxygen isotopic values and very good reservoir quality (‘super-k’) occurring in Zone 2; anda finely-crystalline fabric-preserving (FP) dolomite in the uppermost Arab-D (Zone 1) that contains high oxygen isotope values and has generally fair to poor reservoir quality. Previous studies have documented a rare fifth type of dolomite, baroque or ‘saddle’ dolomite, that occurs locally in the reservoir as well. This study also quantified and mapped the abundance and distribution of dolomite across the field, using all available core and log data. Analysis of dolomite distribution map patterns reveals that dolomite occurs in Ghawar as a series of linear trends extending for tens’s of kilometers. These map pattern trends are best-developed in Zone 2B, but are also visible in Zones 2A and 3A as well. Baroque dolomite appears to be limited to a few areas of vertically pervasive dolomite occurring on the same trends of high dolomite content. The linearity of these dolomite trends strongly suggests that some structural element is responsible for controlling their orientation. We interpret these linear patterns to have formed in response to a series of fracturing and/or faulting events that allowed dolomitizing fluids to move up into the reservoir from below, and preferentially dolomitize there. Both a qualitative and a quantitative analysis of performance data (flowmeters) in southern Ghawar (Haradh) indicate that these trends of high dolomite have a profound influence on fluid flow in the reservoir. A qualitative analysis of occurrences of ‘super-k’ in the Arab-D in Haradh suggests that most ‘super-k’ zones (seen as ‘spikes’ or step profiles on the flowmeter) occur in the high dolomite trend in Haradh. A quantitative analysis of flowmeter data and a comparison of this analysis with dolomite map patterns indicate that most reservoir flow occurs where dolomite is abundant, and suggests that there is a direct relationship between patterns of high flow and high dolomite.

scholarly journals Integrin α6 upregulation in nucleus pulposus cell under high oxygen tension attenuates intervertebral disc degeneration

2021 ◽  
Author(s):  
Zeng Xu ◽  
Jiancheng Zheng ◽  
Ying Zhang ◽  
Huiqiao Wu ◽  
Bin Sun ◽  
...  
Keyword(s):  
Oxygen Tension ◽  
Protective Factor ◽  
Cell Function ◽  
Hypoxia Inducible Factor ◽  
Nucleus Pulposus Cell ◽  
Intervertebral Disk ◽  
High Oxygen ◽  
Low Oxygen ◽  
Induced Apoptosis

AbstractThe destruction of low oxygen microenvironment played critical roles in the pathogenesis of intervertebral disk degeneration (IVDD). In this study, high oxygen tension (HOT) treatment upregulated integrin α6(ITG α6) expression, which could be alleviated by blocking PI3K/AKT signaling pathway. And the levels of ITG α6 expression were increased in the NP tissue from IVDD patients and IVDD rat model with mild degeneration, which were reduced as degeneration degree increases. Further studies found that ITG α6 could protect NP cells against HOT-induced apoptosis and oxidative stress, and protect NP cells from HOT-inhibited ECM proteins synthesis. ITG α6 upregulation by HOT contributed to maintain a NP tissue homeostasis through the interaction with hypoxia inducible factor-1α (HIF-1α). Furthermore, silencing of ITG α6 in vivo could obviously accelerate puncture-induced IVDD. Taken together, ITG α6 upregulation by HOT in NP cells might be a protective factor in IVDD as well as restore NP cell function.

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