Iodine speciation and cycling in limnic systems: observations from a humic rich headwater lake (Mummelsee)

Abstract. Iodine undergoes several redox changes in the natural environment, existing as iodate, iodide, and covalently bound to organic matter. While considerable attention has been given to iodine speciation and cycling in the marine environment, very little is known about iodine cycling and speciation in terrestrial fresh water systems. Here we show iodine speciation (measured by IC-ICP-MS) data from one year of monthly sampling of a small humic rich lake in the Black Forest (Mummelsee) under varying redox conditions. The aim was to elucidate the seasonal cycles of iodine species in the lake water column and to quantify both inorganic and organic iodine species. A sediment core was also collected for iodine analysis. Total iodine levels in the Mummelsee averaged 1.93±0.3 μg l−1. Organo-I was the dominant species in the lake, making up on average 85±7% of the total iodine. No strong seasonal variation in organo-I was observed, with only small variations occurring in the epi- and hypolimnion. Iodide was scavenged from the epilimnion during the summer and autumn, which could be related to (micro)biological uptake and co-precipitation. This was also suggested by the high iodine levels in the sediment core (av. 11.8±1.7 mg kg −1). In the hypolimnion, a strong flux of iodide was observed from the sediments into the water column during anoxic and hypoxic conditions, observed during the summer, autumn and, in the bottom 2 m, the winter. This iodide flux and is thought to occur during decomposition of biological material. Iodate levels in the epilimnion increased consistently over the year, whereas it was reduced below detection limits in the hypolimnion during low oxygen conditions. The winter partial turnover lead to reintroduction of oxygen into the hypolimnion and the formation of iodate and organo-I, as well as removal of iodide. In conclusions, iodine cycling in the Mummelsee was controlled by organo-I, although redox conditions and perhaps biological activity were also important, particularly in the hypolimnion during stratification.

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Jasus lalandii 'walkouts' or mass strandings in South Africa during the 1990s: an overview

Marine and Freshwater Research ◽

10.1071/mf01100 ◽

2001 ◽

Vol 52 (8) ◽

pp. 1085 ◽

Cited By ~ 47

Author(s):

Andrew C. Cockcroft

Keyword(s):

South Africa ◽

West Coast ◽

The Other ◽

Fishing Industry ◽

Low Oxygen ◽

Rock Lobster ◽

The West ◽

Hypoxic Conditions ◽

Oxygen Conditions ◽

Mass Mortalities

Faunal mass mortalities are a sporadic, but not uncommon, feature of the West and South coasts of South Africa. Five mass mortalities of West Coast rock lobsterJasus lalandii, including three of the most severe ever recorded in South Africa, occurred in the 1990s and resulted in the stranding of about 2263 tonnes of lobster. The bulk (97%) of the loss occurred in the last three years of the decade. The five events occurred within an 80 km stretch of coastline that straddled two fishing zones and resulted from hypoxic conditions associated with highbiomass dinoflagellate blooms. In each case, the quantity of lobsters stranded was directly related to the extent or duration of low-oxygen conditions. Small females constituted the bulk of the lobster stranded in most events. The lobster fisheries in the affected fishing zones suffered severe impacts. Recovery in one zone appears to be extremely slow, whereas the other zone is more resilient. Not only would a continuation of the trend of increasing frequency and severity of lobster strandings devastate the rock-lobster fishing industry and the employment prospects of small fishing communities, but it could also seriously affect the ecology of the region.

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A Sediment Diagenesis Model of Seasonal Nitrate and Ammonium Flux Spatial Variation Contributing to Eutrophication at Taihu, China

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17114158 ◽

2020 ◽

Vol 17 (11) ◽

pp. 4158 ◽

Cited By ~ 1

Author(s):

Linda Sarpong ◽

Yiping Li ◽

Eyram Norgbey ◽

Amechi S. Nwankwegu ◽

Yue Cheng ◽

...

Keyword(s):

Water Quality ◽

Water Column ◽

Algal Blooms ◽

Latin Hypercube Sampling ◽

Sediment Flux ◽

Low Oxygen ◽

Four Seasons ◽

Sediment Diagenesis ◽

Oxygen Conditions ◽

Autumn And Winter

Algal blooms have thrived on the third-largest shallow lake in China, Taihu over the past decade. Due to the recycling of nutrients such as nitrate and ammonium, this problem has been difficult to eradicate. Sediment flux, a product of diagenesis, explains the recycling of nutrients. The objective was to simulate the seasonal spatial variations of nitrate and ammonium flux. In this paper, sediment diagenesis modeling was applied to Taihu with Environmental Fluid Dynamics Code (EFDC). Latin hypercube sampling was used to create an input file from twelve (12) nitrogen related parameters of sediment diagenesis and incorporated into the EFDC. The results were analyzed under four seasons: summer, autumn, winter, and spring. The concentration of NH4–N in the sediment–water column increased from 2.744903 to 22.38613 (g/m3). In summer, there was an accumulation of ammonium in the water column. In autumn and winter, the sediment was progressively oxidized. In spring, low-oxygen conditions intensify denitrification. This allows algal blooms to continue to thrive, creating a threat to water quality sustainability. The sediment diagenesis model, coupled with water quality measured data, showed an average relative error for Total Nitrogen (TN) of 38.137%, making the model suitable. Future studies should simulate phosphate flux and measure sediment fluxes on the lake.

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Betaine reduces the expression of inflammatory adipokines caused by hypoxia in human adipocytes

British Journal Of Nutrition ◽

10.1017/s0007114512000888 ◽

2012 ◽

Vol 109 (1) ◽

pp. 43-49 ◽

Cited By ~ 18

Author(s):

K. Olli ◽

S. Lahtinen ◽

N. Rautonen ◽

K. Tiihonen

Keyword(s):

Adipose Tissue ◽

Inflammatory Markers ◽

Mrna Level ◽

Low Grade ◽

Human Adipocytes ◽

Low Oxygen ◽

Hypoxic Conditions ◽

Tnf Α ◽

Oxygen Conditions ◽

Low Grade Inflammation

Obesity is characterised by a state of chronic low-grade inflammation and the elevated circulating and tissue levels of inflammatory markers, including inflammation-related adipokines, released from white adipose tissue. The expression and release of these adipokines generally rises as the adipose tissue expands and hypoxic conditions start to develop within the tissue. Here, the effect of betaine, a trimethylglycine having a biological role as an osmolyte and a methyl donor, on the expression of inflammation-related markers was tested in human adipocytes under hypoxia. Differentiated adipocytes were cultivated under low (1 %) oxygen tension for 8–20 h. The expression of different adipokines, including IL-6, leptin, PPARγ, TNF-α and adiponectin, was measured by quantitative PCR by determining the relative mRNA level from the adipocytes. Hypoxia, in general, led to a decrease in the expression of PPARγ mRNA in human adipocytes, whereas the expression levels of leptin and IL-6 mRNA were substantially increased by hypoxia. The cultivation of adipocytes under hypoxia also led to a reduction in the expression of TNF-α mRNA. The results showed that hypoxia increased the relative quantification of leptin gene transcription, and that betaine (250 μmol/l) reduced this effect, caused by low oxygen conditions. Under hypoxia, betaine also reduced the mRNA level of the pro-inflammatory markers IL-6 and TNF-α. These results demonstrate that the extensive changes in the expression of inflammation-related adipokines in human adipocytes caused by hypoxia can be diminished by the presence of physiologically relevant concentrations of betaine.

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Effects of low oxygen concentrations on aerobic methane oxidation in seasonally hypoxic coastal waters

10.5194/bg-2016-422 ◽

2016 ◽

Author(s):

Lea Steinle ◽

Johanna Maltby ◽

Tina Treude ◽

Annette Kock ◽

Hermann W. Bange ◽

...

Keyword(s):

Water Column ◽

Methane Oxidation ◽

Coastal Waters ◽

Bacterial Biomass ◽

Low Oxygen ◽

Overlying Water ◽

Hypoxic Conditions ◽

Environmental Controls ◽

Effect Of Oxygen ◽

Oxygen Concentrations

Abstract. Coastal seas may account for more than 75 % of global oceanic methane emissions. There, methane is mainly produced microbially in anoxic sediments from where it can escape to the overlying water column. Aerobic methane oxidation (MOx) in the water column acts as a biological filter reducing the amount of methane that eventually evades to the atmosphere. The efficiency of the MOx filter is potentially controlled by the availability of dissolved methane and oxygen, as well as temperature, salinity, and hydrographic dynamics, and all of these factors undergo strong temporal fluctuations in coastal ecosystems. In order to elucidate the key environmental controls, specifically the effect of oxygen availability, on MOx in a seasonally stratified and hypoxic coastal marine setting, we conducted a 2-year time-series study with measurements of MOx and physico-chemical water column parameters in a coastal inlet in the southwestern Baltic Sea (Eckernförde Bay). We found that MOx rates always increased toward the seafloor, but were not directly linked to methane concentrations. MOx exhibited a strong seasonal variability, with maximum rates (up to 11.6 nmol l−1 d−1) during summer stratification when oxygen concentrations were lowest and bottom-water temperatures were highest. Under these conditions, 70–95 % of the sediment-released methane was oxidized, whereas only 40–60 % were consumed during the mixed and oxygenated periods. Laboratory experiments with manipulated oxygen concentrations in the range of 0.2–220 µmol l−1 revealed a sub-micromolar oxygen-optimum for MOx at the study site. In contrast, the fraction of methane-carbon incorporation into the bacterial biomass (compared to the total amount of oxidised methane) was up to 38-fold higher at saturated oxygen concentrations, suggesting a different partitioning of catabolic and anabolic processes under oxygen-replete and oxygen-starved conditions, respectively. Our results underscore the importance of MOx in mitigating methane emission from coastal waters and indicate an organism-level adaptation of the water column methanotrophs to hypoxic conditions.

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Harnessing hypoxia as an evolutionary driver of complex multicellularity

Interface Focus ◽

10.1098/rsfs.2019.0101 ◽

2020 ◽

Vol 10 (4) ◽

pp. 20190101 ◽

Cited By ~ 2

Author(s):

Emma U. Hammarlund

Keyword(s):

Vascular Plants ◽

Animal Tissue ◽

Cell Phenotype ◽

Low Oxygen ◽

Immature Cell ◽

Hypoxic Conditions ◽

Animal Physiology ◽

Animal Diversity ◽

Oxygen Conditions ◽

Multicellular Organisms

Animal tissue requires low-oxygen conditions for its maintenance. The need for low-oxygen conditions contrasts with the idea of an evolutionary leap in animal diversity as a result of expanding oxic conditions. To accommodate tissue renewal at oxic conditions, however, vertebrate animals and vascular plants demonstrate abilities to access hypoxia. Here, I argue that multicellular organisms sustain oxic conditions first after internalizing hypoxic conditions. The ‘harnessing’ of hypoxia has allowed multicellular evolution to leave niches that were stable in terms of oxygen concentrations for those where oxygen fluctuates. Since oxygen fluctuates in most settings on Earth's surface, the ancestral niche would have been a deep marine setting. The hypothesis that ‘large life’ depends on harnessing hypoxia is illustrated in the context of conditions that promote the immature cell phenotype (stemness) in animal physiology and tumour biology and offers one explanation for the general rarity of diverse multicellularity over most of Earth's history.

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A link in the chain of the Cambrian zooplankton: bradoriid arthropods invade the water column

Geological Magazine ◽

10.1017/s0016756815000059 ◽

2015 ◽

Vol 152 (5) ◽

pp. 923-934 ◽

Cited By ~ 10

Author(s):

MARK WILLIAMS ◽

THIJS R. A. VANDENBROUCKE ◽

VINCENT PERRIER ◽

DAVID J. SIVETER ◽

THOMAS SERVAIS

Keyword(s):

Sea Level Rise ◽

Water Column ◽

Sea Level ◽

Global Distribution ◽

Geographical Range ◽

Low Oxygen ◽

Active Lifestyle ◽

Environmental Controls ◽

Continental Shelves ◽

Oxygen Conditions

AbstractBradoriids are small bivalved arthropods that had global distribution for about 20 million years beginning at Cambrian Epoch 2 (c. 521 Ma). The majority of bradoriids are considered to be benthic, favouring oxygenated waters, as suggested by their anatomy, lithofacies distribution, faunal associates and provinciality. Most bradoriids were extinct by the end of the Drumian Age (middle of Cambrian Epoch 3). The post-Drumian is characterized by widespread dysoxic shelf lithofacies in southern Britain and Scandinavia and by the abundance of phosphatocopid arthropods. This interval is also associated with two bradoriid species with wide intercontinental distribution: Anabarochilina primordialis, which had a geographical range from the palaeo-tropics to high southern palaeo-latitude, and Anabarochilina australis, which extended through the palaeo-tropics from Laurentia to Gondwana. The wide environmental and geographical range of these species, coupled with a carapace anatomy that suggests an active lifestyle, is used to infer a zooplanktonic lifestyle. A possible driver of this widespread Cambrian bradoriid zooplankton was sea-level rise coupled to the periodic spread of low oxygen conditions onto continental shelves, acting in tandem with anatomical pre-adaptations for swimming. Parallels exist with the myodocope ostracod colonization of the water column during Silurian time, which may also have been influenced by extrinsic environmental controls acting on anatomical pre-adaptations for swimming. Similar biological and environmental mechanisms may have facilitated arthropod zooplankton colonizations across Phanerozoic time.

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Transcriptome sequencing revealed differences in the response of renal cancer cells to hypoxia and CoCl2 treatment

F1000Research ◽

10.12688/f1000research.7571.1 ◽

2015 ◽

Vol 4 ◽

pp. 1518 ◽

Cited By ~ 9

Author(s):

Nadezhda Zhigalova ◽

Artem Artemov ◽

Alexander M. Mazur ◽

Egor B. Prokhortchouk

Keyword(s):

Cancer Cells ◽

Human Cancer ◽

Hypoxia Inducible Factor ◽

Low Oxygen ◽

Human Cancer Cells ◽

Hypoxic Conditions ◽

Pathway Activation ◽

Oxygen Conditions ◽

Order Of Magnitude ◽

Transcriptional Changes

Human cancer cells are subjected to hypoxic conditions in many tumours. Hypoxia causes alterations in the glycolytic pathway activation through stabilization of hypoxia-inducible factor 1. Currently, two approaches are commonly used to model hypoxia: an alternative to generating low-oxygen conditions in an incubator, cells can be treated with CoCl2. We performed RNA-seq experiments to study transcriptomes of human Caki-1 cells under real hypoxia and after CoCl2 treatment. Despite causing transcriptional changes of a much higher order of magnitude for the genes in the hypoxia regulation pathway, CoCl2 treatment fails to induce alterations in the glycolysis / gluconeogenesis pathway. Moreover, CoCl2 caused aberrant activation of other oxidoreductases in glycine, serine and threonine metabolism pathways.

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Culture of Mobilized Human CD34+ Cells in Hypoxic Conditions Improves Lentiviral Transduction Efficiency in SCID-Repopulating Cells

Blood ◽

10.1182/blood.v112.11.3545.3545 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3545-3545

Author(s):

Andre Larochelle ◽

Hezhi Gan ◽

Joshua R. Clevenger ◽

Cynthia E. Dunbar

Keyword(s):

Cell Cycle ◽

Transduction Efficiency ◽

Low Oxygen ◽

Lentiviral Transduction ◽

Hypoxic Conditions ◽

Human Cd34 ◽

Cd34 Cells ◽

Oxygen Conditions ◽

Cells Cultured

Abstract Under normal physiological conditions, hematopoietic stem cells (HSC) are sequestered in a hypoxic microenvironment in the bone marrow (BM), suggesting that low oxygen levels may play a fundamental role in the maintenance of normal stem cell function and protect these cells from the damaging effects of reactive oxygen species (ROS). In vitro culture of human BM CD34+ cells under hypoxic conditions has been shown to result in expansion of SCID-repopulating cells (SRC) as compared to culture under normoxic conditions (JCI112 (1); 126, 2003). We investigated whether culture of human mobilized CD34+ cells under low oxygen conditions (5% O2) could improve lentiviral transduction efficiency in SRC compared with culture under atmospheric O2 conditions (21%). G-CSF mobilized CD34+ cells from 4 healthy volunteers were prestimulated for 48 hours in the presence of cytokines (SCF, Flt-3 ligand and thrombopoietin) and subsequently transduced in fibronectin coated plates for 24 hours with SIN-lentiviral vectors carrying the GFP gene under the control of an EF1α promoter. In 3 experiments, cells were used for in vitro assays, including ROS, phenotypic, cell cycle, clonogenic and apoptosis assays. In one experiment, cells were injected intravenously in the tail vein of sublethally irradiated NOD/SCID IL2rγ −/− mice after transduction. Intracellular ROS levels increased more significantly in human CD34+ cells cultured for 3 days in 21% O2 compared with cells cultured in 5% O2. When cultures were maintained more than 3 days, ROS levels were similar between the 2 conditions. The levels of expansion of CD34+ cells compared with baseline were similar in hypoxia (3.9-fold) and normoxia (3.5-fold) (p=0.47). In contrast, the expansion of CD34+CD38− cells, a subpopulation enriched in HSCs, was greater in hypoxia (3.8-fold) than in normoxia (2.2-fold) (p=0.02). After 3 days of culture, the total number of colony-forming cells (CFC) increased 1.1-fold and 1.3-fold under hypoxic and normoxic conditions, respectively (p=0.32) compared with freshly isolated CD34+ cells. The level of O2 had no significant effect on lineage commitment of the CFC. At baseline, the majority (59.5%) of the CD34+ cells were in the G0 phase of the cell cycle. After 3 days in culture under hypoxic or normoxic conditions, the percentages of cells in G0 were 5.5% and 3.5%, respectively (p=0.03). The differences in percentages of cells in the G1 and G2/S/M phases of the cell cycle were not statistically different. The percentages of CD34+ apoptotic cells were similar between hypoxic (32.8%) and normoxic (29.5%) conditions (p=0.18). The pO2 also had no impact on CD34+ cell death (12.2% at 5% O2 and 11.7% at 21% O2, p=0.9). When considering the bulk of CD34+ cells after transduction with GFP-lentiviral vectors, there was no statistically significant difference in the percentages of GFP+ cells under hypoxia (22.3%) or normoxia (21%) (p=0.88). In contrast, when CD34+ cells cultured under hypoxia were injected into NOD/SCID IL2rγ −/− mice at the end of the transduction period, improved human cell engraftment and lentiviral transduction efficiency were detected 2 months after transplantation compared with CD34+ cells cultured under normoxia. Human cell engraftment in the mouse BM, as determined by flow cytometry using a human specific CD45 antibody, was 84% in the hypoxic group (n=4) and 54% in the normoxic group (n=4) (p=0.04). The level of O2 had no significant impact on the lineage commitment of the SRC, with a majority of CD45+CD15+ granulocytes in both groups. The percentage of GFP+CD45+ cells was 54% (hypoxia) and 43% (normoxia) (p=0.02), indicating an improved transduction efficiency of SRC under hypoxic conditions. Overall, these data indicate that human CD34+ cells cultured under low oxygen conditions maintain a more primitive phenotype and have an increased susceptibility to lentiviral transduction compared with cells cultured in 21% O2 conditions. Improved engraftment and transduction efficiency do not appear to be related to decreased apoptosis in lower O2 concentrations; instead, increased ROS production in higher O2 concentrations could lead to increased cell signaling and differentiation. Use of low O2 levels for in vitro transduction of human CD34+ cells could have important clinical implications in gene therapy.

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SQAP, an acyl sulfoquinovosyl derivative, suppresses expression of histone deacetylase and induces cell death of cancer cells under hypoxic conditions

Bioscience Biotechnology and Biochemistry ◽

10.1093/bbb/zbaa015 ◽

2021 ◽

Vol 85 (1) ◽

pp. 85-91

Author(s):

Hirofumi Kawakubo ◽

Shinji Kamisuki ◽

Kei Suzuki ◽

Jesus Izaguirre-Carbonell ◽

Shiki Saito ◽

...

Keyword(s):

Histone Deacetylase ◽

Biological Activities ◽

Hypoxia Inducible Factor ◽

Hdac Inhibitors ◽

Low Oxygen ◽

Hypoxic Conditions ◽

Oxygen Conditions ◽

Model Mouse ◽

Hepatocarcinoma Cells ◽

Hepatoma Model

Abstract Sulfoglycolipid, SQAP, is a radiosensitizing agent that makes tumor cells more sensitive to radiation therapy. A previous study revealed that SQAP induced the degradation of hypoxia-inducible factor-1α (HIF-1α) and inhibited angiogenesis in a hepatoma model mouse. Herein, we examined the biological activities of SQAP against hepatocarcinoma cells under low oxygen conditions. Cell growth inhibition of SQAP under hypoxic conditions was significantly higher than that under normoxic conditions. In addition, SQAP was found to impair the expression of histone deacetylase (HDAC) under low oxygen conditions. Our present data suggested that SQAP induced the degradation of HIF-1α and then decreased the expression of HDAC1. Unlike known HDAC inhibitors, SQAP increased the acetylation level of histone in cells without inhibition of enzymatic activity of HDACs. Our data demonstrated hypoxia-specific unique properties of SQAP.

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The Ediacaran ‘Miaohe Member’ of South China: new insights from palaeoredox proxies and stable isotope data

Geological Magazine ◽

10.1017/s0016756821000261 ◽

2021 ◽

pp. 1-15

Author(s):

Paul Bridger ◽

Simon W. Poulton ◽

Ying Zhou ◽

Chao Li ◽

Kun Zhang ◽

...

Keyword(s):

Trace Metal ◽

Water Column ◽

Southern China ◽

Life Forms ◽

Black Shales ◽

Redox Conditions ◽

Geochemical Data ◽

Ecological Niches ◽

Low Oxygen ◽

Reactive Iron

Abstract Throughout the Ediacaran Period, variable water-column redox conditions persisted along productive ocean margins due to a complex interplay between nutrient supply and oceanographic restriction. These changing conditions are considered to have influenced early faunal evolution, with marine anoxia potentially inhibiting the development of the ecological niches necessary for aerobic life forms. To understand this link between oxygenation and evolution, the combined geochemical and palaeontological study of marine sediments is preferable. Located in the Yangtze Gorges region of southern China, lagoonal black shales at Miaohe preserve alga and putative metazoans, including Eoandromeda, a candidate total-group ctenophore, thereby providing one example of where integrated study is possible. We present a multi-proxy investigation into water-column redox variability during deposition of these shales (c. 560–551 Ma). For this interval, reactive iron partitioning indicates persistent water-column anoxia, while trace metal enrichments and other geochemical data suggest temporal fluctuations between ferruginous, euxinic and rare suboxic conditions. Although trace metal and total organic carbon values imply extensive basin restriction, sustained trace metal enrichment and δ15Nsed data indicate periodic access to open-ocean inventories across a shallow-marine sill. Lastly, δ13Corg values of between −35‰ and −40‰ allow at least partial correlation of the shales at Miaohe with Member IV of the Doushantuo Formation. This study provides evidence for fluctuating redox conditions in the lagoonal area of the Yangtze platform during late Ediacaran time. If these low-oxygen environments were regionally characteristic, then the restriction of aerobic fauna to isolated environments can be inferred.

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