Short-term Anoxia Research Articles

Effect of Short-Term Anoxia on Weight Loss and Pigments of Carambola Fruit Cv.See-Thong

The effect of a short-term anoxia may induce stress, which can prolong the good qualities of fresh produce after harvest. The objective of this research was to study the effects of a short-term anoxia (0; control, 12, 24 and 36 h) on weight loss, chlorophyll a (Ca), chlorophyll b (Cb) and carotenoids content of carambola fruit cv. See-Thong. Collected data were analyzed for 2-day intervals during storage at 25±2 °C 60-70%RH up to 8 days. The results showed that short-term anoxia treatment could help retarding weight loss, as well as Ca, and Cb degradations. Treatment of short-term anoxia showed best results at 24 h, followed by 36 h, 12 h, and control, respectively. There was no significant difference between the anoxia treatments and the control at 8 days of storage. Carotenoid content tended to increase all treatments especially in the control, followed by anoxia treatments of 12 h, 36 h, and 24 h, respectively. Therefore, a short-term anoxia treatment at the appropriate time can help maintaining carambola fruit cv. See-Thong after harvest.

Foraminiferal and Palynological Records of an Abrupt Environmental Change at the Badenian/Sarmatian Boundary (Middle Miocene): A Case Study in Northeastern Central Paratethys

The Badenian/Sarmatian boundary in the Central Paratethyan basins is characterised by a change from open marine conditions during the late Badenian to the assumed brackish conditions during the early Sarmatian. The foraminiferal and palynological results of the Badenian/Sarmatian boundary interval in the Babczyn 2 borehole (in SE Poland) showed that the studied interval accumulated under variable, unstable sedimentary conditions. The Badenian/Sarmatian boundary, as correlated with a sudden extinction of stenohaline foraminifera, is interpreted as being due to the shallowing of the basin. The lack of foraminifera and marine palynomorphs just above the Badenian/Sarmatian boundary can reflect short-term anoxia. The composition of the euryhaline assemblages, characteristic for the lower Sarmatian part of the studied succession, indicates from marine to hypersaline conditions.

Short-term Anoxic Treatment of Litchi Fruit (<i>Litchi chinensis</i> Sonn. cv. Hong Huey) Delays Pericarp Browning and Maintains Physicochemical Quality During Storage

The effect of short-term anoxic treatment prior to storage at ambient and cool temperatures on pericarp browning, fruit quality, secondary metabolites, antioxidant activity, and the browning enzyme of litchi (Litchi chinensis Sonn.) cv. Hong Huey were investigated. Litchi fruit were exposed to anoxic conditions for 6, 12, 18 and 24 h before storage at 28 ± 2°C for 5 days, or at 7 ± 2°C for 14 days. Anoxic treatment resulted in significantly decreases in electrical conductivity, weight loss, browning index, while maintaining the total soluble solids (TSS) and delaying increases in polyphenol oxidase (PPO) and peroxidase (POD) activities compared with control fruit. Furthermore, anoxic treatment increased litchi pericarp methanol extract antioxidant capacity, as measured by free-radical scavenging activity. This is associated with greater amounts of ascorbic acid, anthocyanins, and phenolic/flavonoid components as compared with control fruit. Additionally, anoxic treatment considerably delayed litchi fruit pericarp browning. This suggests that with adequate short-term anoxia duration, an enhanced non-enzymatic antioxidant process may directly or indirectly delay litchi pericarp browning. Thus, a short anoxic treatment enables harvested litchi quality to be sustained at ambient and cool temperatures. This non-chemical and inexpensive treatment deserves further development and application, especially in commercial distribution systems where cooling is insufficient.

Effect of short-term anoxia on chlorophyll and sensory attributes of ‘See-Thong’ carambola fruit

Effect of short-term anoxia on chlorophyll and sensory attributes of ‘See-Thong’ carambola fruit

Effect of short-term anoxia treatment on endogenous ethanol and postharvest responses of broccoli florets during storage at ambient temperature

Color change is the main factor limiting quality and shelf-life of broccoli florets. The aim of this recent work was to investigate the effectiveness of anoxia treatment on appearance and the contents of chlorophylls and ascorbic acid of broccoli florets during storage at ambient temperature. In preliminary experiment, the broccoli florets were treated in anoxia condition for 24 h. It was found that the exposure period between 18−24 h was the most effective for delaying broccoli florets yellowing. Therefore, the confirmatory experiment of short-term anoxia treatment for 18, 20, 22 and 24 h was carried out to verify ethanol concentration after treatments and color, chlorophylls and ascorbic acid contents were investigated in broccoli florets during storage at 20 ± 1 °C (85–95 % RH) for 3 d. It was found that the longer exposure time was used, the more production of ethanol occurred which the highest level of ethanol was recorded in the treatment of 24 h (951.98 mg kg−1). Anoxia treatment maintained both L* and hue angle values by delaying the degradation of chlorophyll contents during storage. Florets started to turn yellow when total chlorophyll content was about 500 mg kg−1. It was also noted that during 20 h of anoxia treatment, the total ascorbic acid losses was relatively delayed in broccoli florets better than that of other treatments. However, higher ethanol content was observed in an excessive treatment of anoxia-treated broccoli for 22−24 h which contributed to a dark colorization and water soaking of floret tissues. It revealed that, broccoli florets with an appropriate level of endogenous ethanol is a relevant method to retard yellowing of broccoli floret stored at ambient temperature. Our purpose in this present work also indicate that anoxia treatment practicable for using as non-chemical and simple postharvest technology in maintaining visual appearance and delaying the loss of ascorbic acid in broccoli florets during short-term storage at ambient temperature.

Hypoxic preconditioning enhances cell hypoxia tolerance and correlated lncRNA and mRNA analysis

AimsHypoxia makes cells death but it is not always true. Short term anoxia can boost remaining cells activities and promote tissue repair. This study is to explore the effects of hypoxic preconditioning (HP) on osteoblasts and analyze the involved lncRNA and mRNA. Main methodsHuman osteoblast was used. Normoxic control group (N) were cultured in normoxic culture medium (L-DMEM, 10% FBS and 1% penicillin–streptomycin) 8 h. Long-term hypoxic group (H) were cultured in 4 h hypoxic culture medium (200 μmol/L CoCl2 and L-DMEM)/4 h normoxic culture medium. Hypoxic preconditioning group (HP) were received 3 times HP (cultured in 10 min hypoxic culture medium/10 min normoxic culture medium, which was HP 1times) and then cultured in 4 h hypoxic culture medium/4 h normoxic culture medium. Cell proliferation ability, osteonectin, transforming growth factor-β1, insulin like growth factors-1 and osteopontin were test. The lncRNA and mRNA was detected by high-throughput sequencing. p-Value < 0.05 was accepted as statistically significant. Key findingsCell proliferation activity: N > HP > P. Corrected osteonectin, TGF-β1, IGF-1 and osteopontin: HP > P > N. High-throughput sequencing of gene shown the expression of 4630 RNAs. Further, we identified that HP group made 239 and 160 target genes up-regulated and down-regulated respectively compared with H group (p < 0.05). GO, KEGG and PPI analysis indicated relevant biological processes. SignificanceHypoxic preconditioning alleviated cells anoxia tolerance and promoted cells to synthesis many cytokines. The protection mechanism involved many lncRNAs and mRNAs.

Boosted Membrane Potential as Bioenergetic Response to Anoxia in Dinoroseobacter shibae.

Dinoroseobacter shibae DFL 12T is a metabolically versatile member of the world-wide abundant Roseobacter clade. As an epibiont of dinoflagellates D. shibae is subjected to rigorous changes in oxygen availability. It has been shown that it loses up to 90% of its intracellular ATP when exposed to anoxic conditions. Yet, D. shibae regenerates its ATP level quickly when oxygen becomes available again. In the present study we focused on the bioenergetic aspects of the quick recovery and hypothesized that the proton-motive force decreases during anoxia and gets restored upon re-aeration. Therefore, we analyzed ΔpH and the membrane potential (ΔΨ) during the oxic-anoxic transitions. To visualize changes of ΔΨ we used fluorescence microscopy and the carbocyanine dyes DiOC2 (3; 3,3′-Diethyloxacarbocyanine Iodide) and JC-10. In control experiments the ΔΨ-decreasing effects of the chemiosmotic inhibitors CCCP (carbonyl cyanide m-chlorophenyl hydrazone), TCS (3,3′,4′,5-tetrachlorosalicylanilide) and gramicidin were tested on D. shibae and Gram-negative and -positive control bacteria (Escherichia coli and Micrococcus luteus). We found that ΔpH is not affected by short-term anoxia and does not contribute to the quick ATP regeneration in D. shibae. By contrast, ΔΨ was increased during anoxia, which was astonishing since none of the control organisms behaved that way. Our study shows physiological and bioenergetical aspects comparing to previous studies on transcriptomic responses to the transition from aerobic to nitrate respiration in D. shibae. For the lifestyle as an epibiont of a dinoflagellate, the ability to stand phases of temporary oxygen depletion is beneficial. With a boosted ΔΨ, the cells are able to give their ATP regeneration a flying start, once oxygen is available again.

Physicochemical changes of ‘Phulae’ pineapple fruit treated with short-term anoxia during ambient storage

The effects of short-term anoxia exposure for 16h on physicochemical changes of 'Phulae' pineapple fruit stored at ambient temperature (25±2°C) were investigated. The respiratory rate of the fruit was induced by the anoxia treatment. However, it retarded the increase in moisture loss and maintained both flesh and pulp colour by inhibiting polyphenol oxidase (PPO) activity of the both tissues. The anoxia exposure delayed the increase in total sugar content and enhanced total ascorbic acid content during storage. The half-cut pineapple fruit showed that the anoxia exposure completely inhibited internal transparency of the flesh tissue adjacent to core during the storage. In conclusion, the short-term anoxia exposure for 16h maintained postharvest quality, retarded physiological disorder and enhanced nutritional values of the pineapple fruit stored at ambient temperature (25±2°C).

Na+/K+-ATPase activity in the anoxic turtle (Trachemys scripta) brain at different acclimation temperature

Survival of prolonged anoxia requires a balance between cellular ATP demand and anaerobic ATP supply from glycolysis, especially in critical tissues such as the brain. To add insight into the ATP demand of the brain of the anoxia-tolerant red-eared slider turtle (Trachemys scripta) during prolonged periods of anoxic submergence, we quantified and compared the number of Na+-K+-ATPase units and their molecular activity in brain tissue from turtles acclimated to either 21°C or 5°C and exposed to either normoxia or anoxia (6h 21°C; 14days at 5°C). Na+-K+-ATPase activity and density per g tissue were similar at 21°C and 5°C in normoxic turtles. Likewise, anoxia exposure at 21°C did not induce any change in Na+-K+-ATPase activity or density. In contrast, prolonged anoxia at 5°C significantly reduced Na+-K+-ATPase activity by 55%, which was largely driven by a 50% reduction of the number of Na+-K+-ATPase units without a change in the activity of existing Na+-K+-ATPase pumps or α-subunit composition. These findings are consistent with the “channel arrest” hypothesis to reduce turtle brain Na+-K+-ATPase activity during prolonged, but not short-term anoxia, a change that likely helps them overwinter under low temperature, anoxic conditions.

Effect of prestorage short-term Anoxia treatment and modified atmosphere packaging on the physical and chemical changes of green asparagus

The effects of prestorage short-term Anoxia treatment combined with modified atmosphere packaging (MAP) on quality changes during the storage of green asparagus (Asparagus officinalis L.) spears were investigated. Two sets of asparagus were used in this study. The first set underwent short-term Anoxia treatment via the administration of gaseous N2 for 8h at room temperature, while the second set was kept in ambient air at the same temperature. Consequently, treated and untreated spears were stored either freely or packaged in plastic bags with low density polyethylene, in which a passive modification of the atmosphere was allowed to develop. All samples were stored at 4°C for 8 days, followed by 8 days at 10°C. Samples treated with neither Anoxia nor MAP were used as a control. Our results show that treating the asparagus samples with Anoxia and MAP (Anoxia+PE) caused lower respiration, slowing the decrease in headspace O2. In the Anoxia+PE treated samples, spears lost <12% fresh weight after 8 days at 10°C. All treatments showed less increase in shear force while exposed at 4°C for 8 days, as compared with the significant increase found when transferred to 10°C. This increase in shear force was accompanied by the accumulation of fiber and lignin content. There was a positive relationship between toughening and fiber (R2=0.958) and toughening and lignin (R2=0.915). Moreover, the degradation of chlorophyll, sugar and ascorbic acid content under the Anoxia and MAP treatments were significantly reduced. The results of the present work indicate that Anoxia treatment, a non-chemical and simple postharvest technology, feasible for use in developing countries where food storage technologies are lacking.

Patterns in nematode community during and after experimentally induced anoxia in the northern Adriatic Sea

The effect of short and long-term induced anoxia on a benthic nematode community and its potential for recovery after reoxygenation were investigated in an in situ experiment on a silty-sand bottom in the Gulf of Trieste, the northern Adriatic Sea. Anoxia was created artificially by three underwater benthic Plexiglas chambers at a depth of 24 m. Treatments lasted for 2, 23 and 307 days. Control samples (Normoxia) were taken on 3 (Normoxia 1) and 25 (Normoxia 2) August 2010 outside the chambers (4–5 m further). After opening the chambers, recovery cores were taken after 7 days (Anoxia 2D), 30 days (Anoxia 23D) and 90 days (Anoxia 307D).Our results revealed that short-term anoxia (Anoxia 2D) did not affect nematode total density and diversity, community structure and their vertical distribution in the sediment. However, total and vertical nematode density, species richness and diversity decreased at 23 days and decreased further at 307 days anoxia. Some nematode species like Metalinhomoeus effilatus, Paralinhomoeus caxinus and Terschellingia longicaudata even survived at 307 days anoxia treatment. Our results also demonstrated that nematode community exposed to 23 days anoxia did not recover after 30 days sediment reoxygenation but, a full recovery was observed after 90 days for nematode community exposed to 307 days anoxia.Feeding type contribution (functional aspect) of the nematode community also changed at the anoxia treatments and during the recovery process. This change was most drastic at the Anoxia 23D and 307D treatments. At both Normoxia and Anoxia 2D treatments, selective deposit feeders (1A), non-selective deposit feeders (1B) and epistrate (diatom) feeders (2A) nematodes were observed in the dominant nematode community. Epistrate feeders disappeared from in the Anoxia 23D treatment epistrate and also selective deposit feeders did not belong to the dominant nematode species in the Anoxia 307D treatment. After the recovery process, epistrate feeders and selective deposit feeding nematodes reappeared again amongst the dominant nematode species after 30 and 90 days of recovery, respectively.

Phosphorus mobility under short-term anoxic conditions in two shallow eutrophic coastal systems (Curonian and Sacca di Goro lagoons)

The effects of short-term anoxia on phosphorus mobility were investigated in estuarine sediments collected from two eutrophic European lagoons. Study areas differ with regard to climate and salinity: the boreal Curonian Lagoon (Lithuania) is oligohaline while the Mediterranean Sacca di Goro (Italy) is mesohaline. In each lagoon two sites were chosen representing areas impacted by river plume discharge and areas impacted by high organic matter deposition. Benthic fluxes of dissolved oxygen, inorganic phosphorus (DIP), iron (Fe2+) and manganese (Mn2+) were measured by dark intact core incubations in oxic and anoxic conditions. The latter were induced by incubation prolonged by up to 40 h depending on oxygen consumption rates. Solid phase P pools and pore water profiles of DIP, Fe2+, Mn2+ and sulfides were also measured before and after the induction of anoxia. Although incubation temperature and organic matter content were similar in plume and organic impacted areas of the two estuaries, higher benthic oxygen consumption rates were observed in Sacca di Goro, suggesting higher reactivity of the organic pool. Short-term anoxia had a significant effect on benthic fluxes of DIP (sulfide and Fe2+) only at the organic-rich and saline site of Sacca di Goro while internal buffers prevented inorganic P regeneration at the remaining sites. However, the analysis of pore water and solid phase pools revealed large variations during the transition and provided insights on the mechanisms controlling P dynamics. Both stations influenced by river plume deposition had high total inorganic P content (but most of it was refractory) and high reactive Mn pools, continuously regenerated by ventilation and irrigation of sediments by macrofauna. In these sites, oxygen depletion resulted in large accumulation of reduced Mn in the pore water but high fluxes of Mn2+ were also measured in the oxic part of the incubation suggesting the relevance of this respiration process. Thus Mn reduction preserved oxidized Fe pool and ultimately prevent P mobilization. Our results suggest that fluxes of DIP across the sediment–water interface are controlled by an array of different and site-specific mechanisms. These biogeochemical buffers are effective and contrast massive P release to the water column in highly productive systems as coastal lagoons, where episodes of transient oxygen shortage are frequent.

Вплив зміненого парціального тиску кисню на резистентність до гіпоксії та експресію киснечутливих генів Drosophilа melanogaster

As a result of resistance test to hypoxia of Drosophilas melanogaster of Oregon strain, we identified a high resistance (Group II) and low resistance (Group III) subpopulations of flies. Flies from groups II and III were incubated in a constant normobaric hypoxia (Po2=62-64 mm Hg) for 10 generations. A highly resistant group (Group IV) were exposed to a shortterm anoxia (Po,=1,5 mm Hg, 5 min) every generation. Larvae from Groups II, III, and IV demonstrated significantly elevated levels of Sir and CG 14740 expression. Larvae from Group II had a significantly higher expression of CG 14740 compared to group III. The restitution time after exposure to anoxia was significantly reduced in Group II (on 31% of the control values) Our results suggest that long-term adaptation to low oxygen partial pressure of highly resistant Drosophila significantly reduces the time of restitution and increases the expression of Sir2 and CG14740 genes.

Meiofauna winners and losers of coastal hypoxia: case study harpacticoid copepods

Abstract. The impact of anoxia on meiobenthic copepod species was assessed by means of a field experiment. Four plexiglass chambers were deployed in situ in 24 m depth to simulate an anoxic event of 9 days, 1 month, 2 months and 10 months. From normoxic to anoxic conditions, we recorded a drop in copepod density and species richness. With increasing duration of anoxia the relative abundance of the individuals of the family Cletodidae increased, and they survived the 1 month and 2 month anoxia, the latter with few specimens. They were the true "winners" of the experimentally induced anoxia. Dominance did not increase in the deployments because not one, but several species from this family were tolerant to anoxia. The overall rate of survival was the same for males and females, but no juvenile stages of copepods survived in anoxia. During a recovery phase of 7 days after a short-term anoxia of 9 days, harpacticoid copepod density did not increase significantly, and there was only a slight increase in species diversity. We concluded that no substantial colonisation from the surrounding sediment took place. The survivors, however, showed a high potential for recovery according to the number of gravid females, whose number increased significantly once the oxygen was available again. These findings imply that substantial energy is allocated to reproduction in the recovery phase.

CellTracker Green labelling vs. rose bengal staining: CTG wins by points in distinguishing living from dead anoxia-impacted copepods and nematodes

Abstract. Hypoxia and anoxia have become a key threat to shallow coastal seas. Much is known about their impact on macrofauna, less on meiofauna. In an attempt to shed more light on the latter group, in particular from a process-oriented view, we experimentally induced short-term anoxia (1 week) in the northern Adriatic Sea (Mediterranean) and examined the two most abundant meiofauna taxa – harpacticoid copepods and nematodes. Both taxa also represent different ends of the tolerance spectrum, with copepods being the most sensitive and nematodes among the most tolerant. We compared two methods: CellTracker Green (CTG) – new labelling approach for meiofauna – with the traditional rose bengal (RB) staining method. CTG binds to active enzymes and therefore colours live organisms only. The two methods show considerable differences in the number of living and dead individuals of both meiofauna taxa. Generally, RB will stain dead but not yet decomposed copepods and nematodes equally as it does live ones. Specifically, RB significantly overestimated the number of living copepods in all sediment layers in anoxic samples, but not in any normoxic samples. In contrast, for nematodes, the methods did not show such a clear difference between anoxia and normoxia. RB overestimated the number of living nematodes in the top sediment layer of normoxic samples, which implies an overestimation of the overall live nematofauna. For monitoring and biodiversity studies, the RB method might be sufficient, but for more precise quantification of community degradation, especially after an oxygen depletion event, CTG labelling is a better tool. Moreover, it clearly highlights the surviving species within the copepod or nematode community. As already accepted for foraminiferal research, we demonstrate that the CTG labelling is also valid for other meiofauna groups.

Effects of short-term anoxia treatment on browning of fresh-cut Chinese water chestnut in relation to antioxidant activity

The effects of short-term anoxia pre-treatment on browning of fresh-cut Chinese water chestnut (CWC), stored at 4°C, in relation to antioxidant activity were investigated. CWC slices were exposed to pure N2 for 4h and then stored at 4°C for 18d. Anoxia significantly inhibited browning of CWC slices during storage, accompanied by lower contents of malondialdehyde, H2O2, and lipoxygenase activity. Furthermore, anoxia induced the activities of superoxide dismutase and ascorbate peroxidase, which could benefit scavenging reactive oxygen species and alleviating lipid peroxidation. In addition, better maintenance of reducing power and free-radical-scavenging activities against α,α-diphenyl-β-picrylhydrazy (DPPH), superoxide anions and hydroxyl was observed in N2-treated CWC slices, with higher phenolic compounds and ascorbic acid contents. Collectively, these finds suggest that N2 pre-treatment enhanced enzymatic and non-enzymatic antioxidant activity in CWC slices, and thereby contributed to alleviating lipid peroxidation and maintenance of storage quality.

Influence of angular velocity on Vastus Lateralis and Rectus Femoris oxygenation dynamics during knee extension exercises

The purpose of this study was to investigate whether changes in angular velocity would alter vastus lateralis (VL) and rectus femoris (RF) oxygenation status during maximal isokinetic knee extension exercises. Eleven recreationally active male participants randomly performed ten maximal knee extensions at 30, 60, 120 and 240° s(-1). Tissue oxygenation index (TOI) and total haemoglobin concentration ([tHb]) were acquired from the VL and RF muscles by means of near-infrared spectroscopy (NIRS). Breath-by-breath pulmonary oxygen consumption (VO(2p)) was recorded throughout the tests. Peak torque and VO(2p) significantly decreased as a function of velocity (P<0·05). Interestingly, RF and VL TOI significantly increased as a function of velocity (P<0·05), whereas [tHb] significantly decreased as a function of velocity (P<0·05). A greater number of muscle fibre recruited at slow velocity, where the torque and VO(2p) were the highest, might explain the lower VL and RF TOI observed herein. Furthermore, the increase in local blood flow (suggested by [tHb] changes) during isokinetic knee extension exercises performed at slow angular velocity might have been induced by a higher intramuscular pressure during the contraction phases as well as a greater microcirculatory vasodilatation during relaxation phases. Implementing slow-velocity isokinetic exercises in rehabilitation or other training programmes could delay the short-term anoxia generated by such exercises and result in muscle metabolism enhancement.

Abstract 41: Role of the novel glucose-phosphorylating enzyme ADP-dependent glucokinase in human cancer cell lines featuring knockouts generated by zinc finger nucleases

Abstract Increased glucose metabolism under aerobic conditions is a well-known hallmark of cancer, and has wide therapeutic implications. ADP-dependent glucokinase (ADPGK) is a novel mammalian glucose-phosphorylating enzyme (Ronimus &amp; Morgan 2004) with the unique ability to utilize ADP as phosphate donor. Mouse recombinant ADPGK is a monomeric protein of 54 kDa with high specificity for glucose and an apparent Km for glucose of 96 μM, which is about a third of that of hexokinase 2 (HK2). Based on its biochemical properties, we hypothesize that ADPGK has a protective role under stress conditions such as hypoxia or low glucose, utilizing ADP to prime glycolysis when ATP becomes limiting. Given the importance of hypoxia in tumor progression and resistance to therapy, this would make ADPGK a potential therapeutic target. To study the role of this novel enzyme in cancer biology, we determined its expression in 23 human cancer cell lines by mRNA microarray and western blot. Real-time PCR and westerns were used to test changes in ADPGK expression under anoxia. siRNA for ADPGK and HK2, and ADPGK knockouts generated with CompoZrTM (Sigma-Aldrich) zinc finger nucleases (ZFN), were used to investigate the role of ADPGK in glycolysis (lactate production and glucose consumption) and clonogenic survival under short-term anoxia and glucose deprivation. High expression of ADPGK was demonstrated across most tumor cell lines tested at both mRNA and protein levels. In contrast to HK2, ADPGK expression was unchanged under anoxia (up to 18 h), which might indicate its constitutive availability in case of a decrease in ATP. 70-80% ADPGK knockdown in H460 cells, validated by western blot and real-time PCR, did not decrease glycolytic activity during 4 hours of anoxia, while ∼60% HK2 knockdown reduced glycolysis by 30-50%. In the same experiments, clonogenic survival was reduced 30% by ADPGK siRNA and 60% by HK2 siRNA, but 4 hours anoxia did not cause an additional decrease. To provide more complete suppression of ADPGK, we used ZFNs to generate ADPGK knockout clones in the human colon cancer cell line HCT116. These were characterized by western blotting, and bi-allelic gene disruption was validated by sequencing across the ZFN cutting site. Knockouts and wildtype were similar in growth and clonogenic survival under oxic as well as anoxic conditions. Initial experiments with 10 mM 2-deoxyglucose under anoxia resulted in a small but non-significant decrease in clonogenic survival for knockout cells. In summary, suppression (siRNA) or knockout (ZFN) of ADPGK appears to have only minor effects on glycolysis and cell survival in vitro in the cell lines evaluated. This may reflect the elasticity and redundancy of glucose phosphorylation by the ATP-dependent hexokinases under the conditions tested to date. The role of ADPGK in hypoxic cell survival in human tumor xenografts is under evaluation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 41.

Eelgrass ( Zostera marina) tolerance to anoxia

The tolerance of eelgrass ( Zostera marina L.) to anoxia was assessed experimentally to evaluate the potential role of short-term anoxia on eelgrass performance. Eelgrass ramets (terminal leaf bundles with rhizomes and roots) were submerged in anoxic seawater for variable periods of time (0.5 to 48 h) at three temperatures (20, 25 and 30 °C) in darkness. Photosynthetic efficiency (Fv/Fm), leaf growth and shoot mortality were assessed as response parameters. Photosynthetic efficiency and leaf growth of ramets exposed to anoxia were closely coupled and declined with both increasing exposure time and temperature. At 20 °C, negative effects of anoxia occurred after 12 h (Fv/Fm) and 24 h (leaf growth). Shoot mortality appeared after 24 h. The negative impacts of anoxia on photosynthesis and growth increased markedly with increasing temperature. At 30 °C, Fv/Fm declined after 1 h, leaf growth after 2 h and no plants survived 8 h of anoxia. The results show that eelgrass is surprisingly intolerant to anoxia and support the hypotheses that anoxia may induce sudden eelgrass die-off and that high temperature strengthens the negative impact of anoxia. The study documents that anoxia in itself may have strong negative impacts on eelgrass performance within ecologically relevant time scales.

Molecular Records of Primary Producers and Sedimentary Environmental Conditions of Late Permian Rocks in Northeast Sichuan, China

A series of biomarkers were identified in the aliphatic and aromatic fractions of the extracts from Late Permian Dalong and Wujiaping formations in Shangsi Section, Northeast Sichuan, South China, on the basis of the analysis of gas chromatography-mass spectrometry (GC-MC). The dominance of lower-molecular-weight n -alkanes throughout the profile suggests the dominant contribution of algae and bacteria to the organics preserved in the marine section. Wujiaping Formation is characterized by the elevated contribution from algae as well as other photoautotrophs such as photosynthetic bacteria as shown by the molecular ratios of hopanes to steranes or tricyclic terpanes as well as the ratio of pristane (Pr) and phytane (Ph) to C 17 and C 18 n -alkanes. This is in accord with the data from the microscopic measurement on the calcareous algae. In contrast, Dalong Formation is featured by enhanced contribution from bacteria and probably terrestrial organics indicated by the enhanced C 24 tetracyclic terpanes relative to tricyclic terpanes. The two formations also show a distinct discrimination in sedimentary environmental conditions including redox condition and salinity. The anoxic condition was only found in the middle of the Dalong Formation as shown by the ratios of Pr/Ph and dibenzothiophene to phenanthrene, consistent with the reported data of Mo and U. An enhanced salinity indicated by the homohopane index is observed at the shallow Wujiaping Formation. On the basis of the composition of primary productivity and the redox condition, Dalong Formation is proposed, herein, to be potential hydrocarbon source rocks in the study site. It is notable that the topmost end-Permian is characterized by a large perturbance in both the redox condition and salinity, with oxic conditions being frequently interrupted by short-term anoxia, likely showing a causal relationship with the episodic biotic crisis across the Permian—Triassic boundary.