Science.gov

Sample records for extracellular acidification exerts

  1. Extracellular acidification exerts opposite actions on TREK1 and TREK2 potassium channels via a single conserved histidine residue.

    PubMed

    Sandoz, Guillaume; Douguet, Dominique; Chatelain, Franck; Lazdunski, Michel; Lesage, Florian

    2009-08-25

    Mechanosensitive K(+) channels TREK1 and TREK2 form a subclass of two P-domain K(+) channels. They are potently activated by polyunsaturated fatty acids and are involved in neuroprotection, anesthesia, and pain perception. Here, we show that acidification of the extracellular medium strongly inhibits TREK1 with an apparent pK near to 7.4 corresponding to the physiological pH. The all-or-none effect of pH variation is steep and is observed within one pH unit. TREK2 is not inhibited but activated by acidification within the same range of pH, despite its close homology with TREK1. A single conserved residue, H126 in TREK1 and H151 in TREK2, is involved in proton sensing. This histidine is located in the M1P1 extracellular loop preceding the first P domain. The differential effect of acidification, that is, activation for TREK2 and inhibition for TREK1, involves other residues located in the P2M4 loop, linking the second P domain and the fourth membrane-spanning segment. Structural modeling of TREK1 and TREK2 and site-directed mutagenesis strongly suggest that attraction or repulsion between the protonated side chain of histidine and closely located negatively or positively charged residues in P2M4 control outer gating of these channels. The differential sensitivity of TREK1 and TREK2 to external pH variations discriminates between these two K(+) channels that otherwise share the same regulations by physical and chemical stimuli, and by hormones and neurotransmitters.

  2. Extracellular Acidification Acts as a Key Modulator of Neutrophil Apoptosis and Functions

    PubMed Central

    Cao, Shannan; Liu, Peng; Zhu, Haiyan; Gong, Haiyan; Yao, Jianfeng; Sun, Yawei; Geng, Guangfeng; Wang, Tong; Feng, Sizhou; Han, Mingzhe; Zhou, Jiaxi; Xu, Yuanfu

    2015-01-01

    In human pathological conditions, the acidification of local environment is a frequent feature, such as tumor and inflammation. As the pH of microenvironment alters, the functions of immune cells are about to change. It makes the extracellular acidification a key modulator of innate immunity. Here we detected the impact of extracellular acidification on neutrophil apoptosis and functions, including cell death, respiratory burst, migration and phagocytosis. As a result, we found that under the acid environment, neutrophil apoptosis delayed, respiratory burst inhibited, polarization augmented, chemotaxis differed, endocytosis enhanced and bacteria killing suppressed. These findings suggested that extracellular acidification acts as a key regulator of neutrophil apoptosis and functions. PMID:26340269

  3. Extracellular Acidification Inhibits the ROS-Dependent Formation of Neutrophil Extracellular Traps

    PubMed Central

    Behnen, Martina; Möller, Sonja; Brozek, Antonia; Klinger, Matthias; Laskay, Tamás

    2017-01-01

    The inflammatory microenvironment is commonly characterized by extracellular acidosis (pH < 7.35). Sensitivity to pH, CO2 or bicarbonate concentrations allows neutrophils to react to changes in their environment and to detect inflamed areas in the tissue. One important antimicrobial effector mechanism is the production of neutrophil extracellular traps (NETs), which are released during a programmed reactive oxygen species (ROS)-dependent cell death, the so-called NETosis. Although several functions of neutrophils have been analyzed under acidic conditions, the effect of extracellular acidosis on NETosis remains mainly unexplored and the available experimental results are contradictory. We performed a comprehensive study with the aim to elucidate the effect of extracellular acidosis on ROS-dependent NETosis of primary human neutrophils and to identify the underlying mechanisms. The study was performed in parallel in a CO2–bicabonate-buffered culture medium, which mimics in vivo conditions, and under HEPES-buffered conditions to verify the effect of pH independent of CO2 or bicarbonate. We could clearly show that extracellular acidosis (pH 6.5, 6.0, and 5.5) and intracellular acidification inhibit the release of ROS-dependent NETs upon stimulation of neutrophils with phorbol myristate acetate and immobilized immune complexes. Moreover, our findings suggest that the diminished NET release is a consequence of reduced ROS production and diminished glycolysis of neutrophils under acidic conditions. It was suggested previously that neutrophils can sense the border of inflamed tissue by the pH gradient and that a drop in pH serves as an indicator for the progress of inflammation. Following this hypothesis, our data indicate that an acidic inflammatory environment results in inhibition of extracellular operating effector mechanisms of neutrophils such as release of ROS and NETs. This way the release of toxic components and tissue damage can be avoided. However, we

  4. Optimising methodology for determining the effect of ocean acidification on bacterial extracellular enzymes

    NASA Astrophysics Data System (ADS)

    Burrell, T. J.; Maas, E. W.; Teesdale-Spittle, P.; Law, C. S.

    2015-04-01

    To fully understand the impact of ocean acidification on biogeochemical cycles, the response of bacterial extracellular enzymes needs to be considered as they play a central role in the degradation and distribution of labile organic matter. This study investigates the methodology, and potential artefacts involved in determining the response of bacterial extracellular glucosidase and protease to ocean acidification. The effect of pH on artificial fluorophores and substrates was examined, as well as the impact of three different acidification methods. The results indicate that pH has a significant effect on the fluorescence of the artificial fluorophore 4-methylumbeliferone for glucosidase activity, and 7-amino-4-methylcoumarin for protease activity, while artificial aminopeptidase substrate alters the pH of seawater, confirming previous observations. Before use in ocean acidification research these enzyme assay components must be buffered in order to stabilise sample pH. Reduction of coastal seawater pH to 7.8 was shown to increase β-glucosidase activity rapidly (0.5 h), while no significant response was detected for leucine aminopeptidase, highlighting the need for short-term direct effects of pH on enzyme activities. Bubbling with CO2 gas resulted in higher β-glucosidase activity when compared to acidification using gas-permeable silicon tubing and acidification with HCl. Although bubbling showed variable effects between two experiments conducted at different times of the year. In addition, bacterial cell numbers were 15-40% higher with bubbling relative to seawater acidified with gas-permeable silicon tubing and HCl. Artefacts associated with bubbling may lead to the overestimation of extracellular enzyme activities, and interpretation of the impacts of ocean acidification on organic matter cycling.

  5. Effects of acidification and increased extracellular potassium on dynamic muscle contractions in isolated rat muscles.

    PubMed

    Overgaard, Kristian; Højfeldt, Grith Westergaard; Nielsen, Ole Bækgaard

    2010-12-15

    Since accumulation of both H(+) and extracellular K(+) have been implicated in the reduction in dynamic contractile function during intense exercise, we investigated the effects of acidification and high K(+) on muscle power and the force-velocity relation in non-fatigued rat soleus muscles. Contractions were elicited by supramaximal electrical stimulation at 60 Hz. Force-velocity (FV) curves were obtained by fitting data on force and shortening velocity at different loads to the Hill equation. Acidification of the muscles by incubation with up to 24 mm lactic acid produced no significant changes in maximal power (P(max)) at 30 °C. More pronounced acidification, obtained by increasing CO(2) levels in the equilibration gas from 5% to 53%, markedly decreased P(max) and maximal isometric force (F(max)), increased the curvature of the FV relation, but left maximal shortening velocity (V(max)) unchanged. Increase of extracellular K(+) from 4 to 10 mm caused a depression of 58% in P(max) and 52% in F(max), but had no significant effect on V(max) or curvature of the FV curve. When muscles at 10 mM K(+) were acidified by 20 mm lactic acid, P(max) and F(max) recovered completely to the initial control level at 4 mm K(+). CO(2) acidification also induced significant recovery of dynamic contractions, but not entirely to control levels. These results demonstrate that in non-fatigued muscles severe acidification can be detrimental to dynamic contractile function, but in muscles depolarised by exposure to high extracellular [K(+)], approaching the [K(+)] level seen during intense fatiguing exercise, acidification can have positive protective effects on dynamic muscle function.

  6. Ocean acidification exerts negative effects during warming conditions in a developing Antarctic fish.

    PubMed

    Flynn, Erin E; Bjelde, Brittany E; Miller, Nathan A; Todgham, Anne E

    2015-01-01

    Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [-1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only in

  7. Ocean acidification exerts negative effects during warming conditions in a developing Antarctic fish

    PubMed Central

    Flynn, Erin E.; Bjelde, Brittany E.; Miller, Nathan A.; Todgham, Anne E.

    2015-01-01

    Anthropogenic CO2 is rapidly causing oceans to become warmer and more acidic, challenging marine ectotherms to respond to simultaneous changes in their environment. While recent work has highlighted that marine fishes, particularly during early development, can be vulnerable to ocean acidification, we lack an understanding of how life-history strategies, ecosystems and concurrent ocean warming interplay with interspecific susceptibility. To address the effects of multiple ocean changes on cold-adapted, slowly developing fishes, we investigated the interactive effects of elevated partial pressure of carbon dioxide (pCO2) and temperature on the embryonic physiology of an Antarctic dragonfish (Gymnodraco acuticeps), with protracted embryogenesis (∼10 months). Using an integrative, experimental approach, our research examined the impacts of near-future warming [−1 (ambient) and 2°C (+3°C)] and ocean acidification [420 (ambient), 650 (moderate) and 1000 μatm pCO2 (high)] on survival, development and metabolic processes over the course of 3 weeks in early development. In the presence of increased pCO2 alone, embryonic mortality did not increase, with greatest overall survival at the highest pCO2. Furthermore, embryos were significantly more likely to be at a later developmental stage at high pCO2 by 3 weeks relative to ambient pCO2. However, in combined warming and ocean acidification scenarios, dragonfish embryos experienced a dose-dependent, synergistic decrease in survival and developed more slowly. We also found significant interactions between temperature, pCO2 and time in aerobic enzyme activity (citrate synthase). Increased temperature alone increased whole-organism metabolic rate (O2 consumption) and developmental rate and slightly decreased osmolality at the cost of increased mortality. Our findings suggest that developing dragonfish are more sensitive to ocean warming and may experience negative physiological effects of ocean acidification only

  8. Phosphorylation of carbonic anhydrase IX controls its ability to mediate extracellular acidification in hypoxic tumors.

    PubMed

    Ditte, Peter; Dequiedt, Franck; Svastova, Eliska; Hulikova, Alzbeta; Ohradanova-Repic, Anna; Zatovicova, Miriam; Csaderova, Lucia; Kopacek, Juraj; Supuran, Claudiu T; Pastorekova, Silvia; Pastorek, Jaromir

    2011-12-15

    In the hypoxic regions of a tumor, carbonic anhydrase IX (CA IX) is an important transmembrane component of the pH regulatory machinery that participates in bicarbonate transport. Because tumor pH has implications for growth, invasion, and therapy, determining the basis for the contributions of CA IX to the hypoxic tumor microenvironment could lead to new fundamental and practical insights. Here, we report that Thr443 phosphorylation at the intracellular domain of CA IX by protein kinase A (PKA) is critical for its activation in hypoxic cells, with the fullest activity of CA IX also requiring dephosphorylation of Ser448. PKA is activated by cAMP, which is elevated by hypoxia, and we found that attenuating PKA in cells disrupted CA IX-mediated extracellular acidification. Moreover, following hypoxia induction, CA IX colocalized with the sodium-bicarbonate cotransporter and other PKA substrates in the leading edge membranes of migrating tumor cells, in support of the concept that bicarbonate metabolism is spatially regulated at cell surface sites with high local ion transport and pH control. Using chimeric CA IX proteins containing heterologous catalytic domains derived from related CA enzymes, we showed that CA IX activity was modulated chiefly by the intracellular domain where Thr443 is located. Our findings indicate that CA IX is a pivotal mediator of the hypoxia-cAMP-PKA axis, which regulates pH in the hypoxic tumor microenvironment.

  9. Multiple H(+) sensors mediate the extracellular acidification-induced [Ca(2+)]i elevation in cultured rat ventricular cardiomyocytes.

    PubMed

    Hu, Yuan-Lang; Mi, Xue; Huang, Chao; Wang, Hui-Fang; Song, Jian-Ren; Shu, Qing; Ni, Lan; Chen, Jian-Guo; Wang, Fang; Hu, Zhuang-Li

    2017-03-23

    Acidosis has been known to cause "Ca(2+) transients", however, the mechanism is still uncertain. Here, we demonstrated that multiple H(+) sensors, such as ASICs, TRPV1 and proton-sensing G protein coupled receptors (GPCRs) are involved in extracellular acidification-induced intracellular calcium ([Ca(2+)]i) elevation. By using calcium imaging measures, we observed that both ASIC and TRPV1 channels inhibitors suppressed the [Ca(2+)]i elevation induced by extracellular acidosis in cultured rat cardiac myocytes. Then, both channels mRNA and proteins were identified by RT-PCR, western blotting and immunofluorescence. ASIC-like and TRPV1-like currents were induced by extracellular acidification, suggesting that functional ASIC and TRPV1 channels jointly mediated extracellular calcium entry. Furthermore, either pre-exhaustion of sarcoplasmic reticulum (SR) Ca(2+) with thapsigargin or IP3 receptor blocker 2-APB or PLC inhibitor U73122 significantly attenuated the elevation of [Ca(2+)]i, indicating that the intracellular Ca(2+) stores and the PLC-IP3 signaling also contributed to the acidosis-induced elevation of [Ca(2+)]i. By using genetic and pharmacological approaches, we identified that ovarian cancer G protein-coupled receptor 1 (OGR1) might be another main component in acidosis-induced release of [Ca(2+)]i. These results suggest that multiple H(+)-sensitive receptors are involved in "Ca(2+) transients" induced by acidosis in the heart.

  10. Multiple H+ sensors mediate the extracellular acidification-induced [Ca2+]i elevation in cultured rat ventricular cardiomyocytes

    PubMed Central

    Hu, Yuan-Lang; Mi, Xue; Huang, Chao; Wang, Hui-Fang; Song, Jian-Ren; Shu, Qing; Ni, Lan; Chen, Jian-Guo; Wang, Fang; Hu, Zhuang-Li

    2017-01-01

    Acidosis has been known to cause “Ca2+ transients”, however, the mechanism is still uncertain. Here, we demonstrated that multiple H+ sensors, such as ASICs, TRPV1 and proton-sensing G protein coupled receptors (GPCRs) are involved in extracellular acidification-induced intracellular calcium ([Ca2+]i) elevation. By using calcium imaging measures, we observed that both ASIC and TRPV1 channels inhibitors suppressed the [Ca2+]i elevation induced by extracellular acidosis in cultured rat cardiac myocytes. Then, both channels mRNA and proteins were identified by RT-PCR, western blotting and immunofluorescence. ASIC-like and TRPV1-like currents were induced by extracellular acidification, suggesting that functional ASIC and TRPV1 channels jointly mediated extracellular calcium entry. Furthermore, either pre-exhaustion of sarcoplasmic reticulum (SR) Ca2+ with thapsigargin or IP3 receptor blocker 2-APB or PLC inhibitor U73122 significantly attenuated the elevation of [Ca2+]i, indicating that the intracellular Ca2+ stores and the PLC-IP3 signaling also contributed to the acidosis-induced elevation of [Ca2+]i. By using genetic and pharmacological approaches, we identified that ovarian cancer G protein-coupled receptor 1 (OGR1) might be another main component in acidosis-induced release of [Ca2+]i. These results suggest that multiple H+-sensitive receptors are involved in “Ca2+ transients” induced by acidosis in the heart. PMID:28332558

  11. Extracellular acidification induces connective tissue growth factor production through proton-sensing receptor OGR1 in human airway smooth muscle cells

    SciTech Connect

    Matsuzaki, Shinichi; Ishizuka, Tamotsu; Yamada, Hidenori; Kamide, Yosuke; Hisada, Takeshi; Ichimonji, Isao; Aoki, Haruka; Yatomi, Masakiyo; Komachi, Mayumi; Tsurumaki, Hiroaki; Ono, Akihiro; Koga, Yasuhiko; Dobashi, Kunio; Mogi, Chihiro; Sato, Koichi; Tomura, Hideaki; Mori, Masatomo; Okajima, Fumikazu

    2011-10-07

    Highlights: {yields} The involvement of extracellular acidification in airway remodeling was investigated. {yields} Extracellular acidification alone induced CTGF production in human ASMCs. {yields} Extracellular acidification enhanced TGF-{beta}-induced CTGF production in human ASMCs. {yields} Proton-sensing receptor OGR1 was involved in acidic pH-stimulated CTGF production. {yields} OGR1 may play an important role in airway remodeling in asthma. -- Abstract: Asthma is characterized by airway inflammation, hyper-responsiveness and remodeling. Extracellular acidification is known to be associated with severe asthma; however, the role of extracellular acidification in airway remodeling remains elusive. In the present study, the effects of acidification on the expression of connective tissue growth factor (CTGF), a critical factor involved in the formation of extracellular matrix proteins and hence airway remodeling, were examined in human airway smooth muscle cells (ASMCs). Acidic pH alone induced a substantial production of CTGF, and enhanced transforming growth factor (TGF)-{beta}-induced CTGF mRNA and protein expression. The extracellular acidic pH-induced effects were inhibited by knockdown of a proton-sensing ovarian cancer G-protein-coupled receptor (OGR1) with its specific small interfering RNA and by addition of the G{sub q/11} protein-specific inhibitor, YM-254890, or the inositol-1,4,5-trisphosphate (IP{sub 3}) receptor antagonist, 2-APB. In conclusion, extracellular acidification induces CTGF production through the OGR1/G{sub q/11} protein and inositol-1,4,5-trisphosphate-induced Ca{sup 2+} mobilization in human ASMCs.

  12. Extracellular acidification synergizes with PDGF to stimulate migration of mouse embryo fibroblasts through activation of p38MAPK with a PTX-sensitive manner

    SciTech Connect

    An, Caiyan; Sato, Koichi; Wu, Taoya; Bao, Muqiri; Bao, Liang; Tobo, Masayuki; Damirin, Alatangaole

    2015-05-01

    The elucidation of the functional mechanisms of extracellular acidification stimulating intracellular signaling pathway is of great importance for developing new targets of treatment for solid tumors, and inflammatory disorders characterized by extracellular acidification. In the present study, we focus on the regulation of extracellular acidification on intracellular signaling pathways in mouse embryo fibroblasts (MEFs). We found extracellular acidification was at least partly involved in stimulating p38MAPK pathway through PTX-sensitive behavior to enhance cell migration in the presence or absence of platelet-derived growth factor (PDGF). Statistical analysis showed that the actions of extracellular acidic pH and PDGF on inducing enhancement of cell migration were not an additive effect. However, we also found extracellular acidic pH did inhibit the viability and proliferation of MEFs, suggesting that extracellular acidification stimulates cell migration probably through proton-sensing mechanisms within MEFs. Using OGR1-, GPR4-, and TDAG8-gene knock out technology, and real-time qPCR, we found known proton-sensing G protein-coupled receptors (GPCRs), transient receptor potential vanilloid subtype 1 (TRPV1), and acid-sensing ion channels (ASICs) were unlikely to be involved in the regulation of acidification on cell migration. In conclusion, our present study validates that extracellular acidification stimulates chemotactic migration of MEFs through activation of p38MAPK with a PTX-sensitive mechanism either by itself, or synergistically with PDGF, which was not regulated by the known proton-sensing GPCRs, TRPV1, or ASICs. Our results suggested that others proton-sensing GPCRs or ion channels might exist in MEFs, which mediates cell migration induced by extracellular acidification in the presence or absence of PDGF. - Highlights: • Acidic pH and PDGF synergize to stimulate MEFs migration via Gi/p38MAPK pathway. • Extracellular acidification inhibits the

  13. Moderate extracellular acidification inhibits capsaicin-induced cell death through regulating calcium mobilization, NF-{kappa}B translocation and ROS production in synoviocytes

    SciTech Connect

    Hu, Fen; Yang, Shuang; Zhao, Dan; Zhu, Shuyan; Wang, Yuxiang; Li, Junying

    2012-07-20

    Highlights: Black-Right-Pointing-Pointer Moderate extracellular acidification regulates intracellular Ca{sup 2+} mobilization. Black-Right-Pointing-Pointer Moderate acidification activates NF-{kappa}B nuclear translocation in synoviocytes. Black-Right-Pointing-Pointer Moderate acidification depresses the ROS production induced by capsaicin. Black-Right-Pointing-Pointer Moderate acidification inhibits capsaicin-caused synoviocyte death. -- Abstract: We previously show the expression of transient receptor potential vanilloid 1 (TRPV1) in primary synoviocytes from collagen-induced arthritis (CIA) rats. Capsaicin and lowered extracellular pH from 7.4 to 5.5 induce cell death through TRPV1-mediated Ca{sup 2+} entry and reactive oxygen species (ROS) production. However, under the pathological condition in rheumatoid arthritis, the synovial fluid is acidified to a moderate level (about pH 6.8). In the present study, we examined the effects of pH 6.8 on the TRPV1-mediated cell death. Our finding is different or even opposite from what was observed at pH 5.5. We found that the moderate extracellular acidification (from pH 7.4 to 6.8) inhibited the capsaicin-induced Ca{sup 2+} entry through attenuating the activity of TRPV1. In the mean time, it triggered a phospholipse C (PLC)-related Ca{sup 2+} release from intracellular stores. The nuclear translocation of NF-{kappa}B was found at pH 6.8, and this also depends on PLC activation. Moreover, the capsaicin-evoked massive ROS production and cell death were depressed at pH 6.8, both of which are dependent on the activation of PLC and NF-{kappa}B. Taken together, these results suggested that the moderate extracellular acidification inhibited the capsaicin-induced synoviocyte death through regulating Ca{sup 2+} mobilization, activating NF-{kappa}B nuclear translocation and depressing ROS production.

  14. Neuronal hyperactivity causes Na(+)/H(+) exchanger-induced extracellular acidification at active synapses.

    PubMed

    Chiacchiaretta, Martina; Latifi, Shahrzad; Bramini, Mattia; Fadda, Manuela; Fassio, Anna; Benfenati, Fabio; Cesca, Fabrizia

    2017-03-02

    Extracellular pH impacts on neuronal activity, which is in turn an important determinant of extracellular H(+) concentration. The aim of this study is to describe the spatio-temporal dynamics of extracellular pH at synaptic sites during neuronal hyperexcitability. To address this issue we created ex.E(2)GFP, a membrane-targeted extracellular ratiometric pH indicator exquisitely sensitive to acidic shifts. By monitoring ex.E(2)GFP fluorescence in real time in primary cortical neurons we were able to quantify pH fluctuations during network hyperexcitability induced by convulsant drugs or high frequency electrical stimulation. Sustained hyperactivity caused a pH decrease that was reversible upon silencing of neuronal activity and localized to active synapses. This acidic shift was not attributable to the outflow of synaptic vesicle protons into the cleft nor to the activity of membrane-exposed H(+)-vATPase, but rather to the activity of the Na(+)/H(+)-exchanger. Our data demonstrate that extracellular synaptic pH shifts take place during epileptic-like activity of neural cultures, underlying the strict links existing between synaptic activity and synaptic pH. This evidence may contribute to the understanding of the physio-pathological mechanisms associated with hyperexcitability in the epileptic brain.

  15. Spatially coordinated changes in intracellular rheology and extracellular force exertion during mesenchymal stem cell differentiation

    NASA Astrophysics Data System (ADS)

    McAndrews, Kathleen M.; McGrail, Daniel J.; Quach, Nhat D.; Dawson, Michelle R.

    2014-10-01

    The mechanical properties within the cell are regulated by the organization of the actin cytoskeleton, which is linked to the extracellular environment through focal adhesion proteins that transmit force. Chemical and mechanical stimuli alter the organization of cytoskeletal actin, which results in changes in cell shape, adhesion, and differentiation. By combining particle-tracking microrheology and traction force cytometry, we can monitor the mechanical properties of the actin meshwork and determine how changes in the intracellular network contribute to force generation. In this study, we investigated the effects of chemical (differentiation factors) and mechanical (substrate rigidity) stimuli important in mesenchymal stem cell (MSC) differentiation on the intracellular mechanics and traction stress generation. We found the presence of adipogenic factors resulted in stiffening of the actin meshwork regardless of substrate rigidity. In contrast, these factors increased traction stresses on hard substrates, which was associated with increased expression of contractility genes. Furthermore, MSCs cultured on hard substrates expressed both adipogenic and osteogenic markers indicative of mixed differentiation. On hard substrates, heterogeneity in the local elastic modulus-traction stress correlation was also increased in response to adipogenic factors, indicating that these mechanical properties may be reflective of differences in the level of MSC differentiation. These results suggest intracellular rheology and traction stress generation are spatially regulated and contribute insight into how single cell mechanical forces contribute to MSC differentiation.

  16. Spatially coordinated changes in intracellular rheology and extracellular force exertion during mesenchymal stem cell differentiation.

    PubMed

    McAndrews, Kathleen M; McGrail, Daniel J; Quach, Nhat D; Dawson, Michelle R

    2014-08-26

    The mechanical properties within the cell are regulated by the organization of the actin cytoskeleton, which is linked to the extracellular environment through focal adhesion proteins that transmit force. Chemical and mechanical stimuli alter the organization of cytoskeletal actin, which results in changes in cell shape, adhesion, and differentiation. By combining particle-tracking microrheology and traction force cytometry, we can monitor the mechanical properties of the actin meshwork and determine how changes in the intracellular network contribute to force generation. In this study, we investigated the effects of chemical (differentiation factors) and mechanical (substrate rigidity) stimuli important in mesenchymal stem cell (MSC) differentiation on the intracellular mechanics and traction stress generation. We found the presence of adipogenic factors resulted in stiffening of the actin meshwork regardless of substrate rigidity. In contrast, these factors increased traction stresses on hard substrates, which was associated with increased expression of contractility genes. Furthermore, MSCs cultured on hard substrates expressed both adipogenic and osteogenic markers indicative of mixed differentiation. On hard substrates, heterogeneity in the local elastic modulus-traction stress correlation was also increased in response to adipogenic factors, indicating that these mechanical properties may be reflective of differences in the level of MSC differentiation. These results suggest intracellular rheology and traction stress generation are spatially regulated and contribute insight into how single cell mechanical forces contribute to MSC differentiation.

  17. DNA, histones and neutrophil extracellular traps exert anti-fibrinolytic effects in a plasma environment.

    PubMed

    Varjú, Imre; Longstaff, Colin; Szabó, László; Farkas, Ádám Zoltán; Varga-Szabó, Veronika Judit; Tanka-Salamon, Anna; Machovich, Raymund; Kolev, Krasimir

    2015-06-01

    In response to various inflammatory stimuli, neutrophils secrete neutrophil extracellular traps (NETs), web-like meshworks of DNA, histones and granular components forming supplementary scaffolds in venous and arterial thrombi. Isolated DNA and histones are known to promote thrombus formation and render fibrin clots more resistant to mechanical forces and tissue-type plasminogen activator (tPA)-induced enzymatic digestion. The present study extends our earlier observations to a physiologically more relevant environment including plasma clots and NET-forming neutrophils. A range of techniques was employed including imaging (scanning electron microscopy (SEM), confocal laser microscopy, and photoscanning of macroscopic lysis fronts), clot permeability measurements, turbidimetric lysis and enzyme inactivation assays. Addition of DNA and histones increased the median fibre diameter of plasma clots formed with 16 nM thrombin from 108 to 121 and 119 nm, respectively, and decreased their permeability constant from 6.4 to 3.1 and 3.7×10(-9) cm(2). Histones effectively protected thrombin from antithrombin-induced inactivation, while DNA inhibited plasminogen activation on the surface of plasma clots and their plasmin-induced resolution by 20 and 40 %, respectively. DNA and histones, as well as NETs secreted by phorbol-myristate-acetate-activated neutrophils, slowed down the tPA-driven lysis of plasma clots and the latter effect could be reversed by the addition of DNase (streptodornase). SEM images taken after complete digestion of fibrin in NET-containing plasma clots evidenced retained NET scaffold that was absent in DNase-treated clots. Our results show that DNA and histones alter the fibrin architecture in plasma clots, while NETs contribute to a decreased lytic susceptibility that can be overcome by DNase.

  18. Acid-sensitive TWIK and TASK Two-pore Domain Potassium Channels Change Ion Selectivity and Become Permeable to Sodium in Extracellular Acidification*

    PubMed Central

    Ma, Liqun; Zhang, Xuexin; Zhou, Min; Chen, Haijun

    2012-01-01

    Two-pore domain K+ channels (K2P) mediate background K+ conductance and play a key role in a variety of cellular functions. Among the 15 mammalian K2P isoforms, TWIK-1, TASK-1, and TASK-3 K+ channels are sensitive to extracellular acidification. Lowered or acidic extracellular pH (pHo) strongly inhibits outward currents through these K2P channels. However, the mechanism of how low pHo affects these acid-sensitive K2P channels is not well understood. Here we show that in Na+-based bath solutions with physiological K+ gradients, lowered pHo largely shifts the reversal potential of TWIK-1, TASK-1, and TASK-3 K+ channels, which are heterologously expressed in Chinese hamster ovary cells, into the depolarizing direction and significantly increases their Na+ to K+ relative permeability. Low pHo-induced inhibitions in these acid-sensitive K2P channels are more profound in Na+-based bath solutions than in channel-impermeable N-methyl-d-glucamine-based bath solutions, consistent with increases in the Na+ to K+ relative permeability and decreases in electrochemical driving forces of outward K+ currents of the channels. These findings indicate that TWIK-1, TASK-1, and TASK-3 K+ channels change ion selectivity in response to lowered pHo, provide insights on the understanding of how extracellular acidification modulates acid-sensitive K2P channels, and imply that these acid-sensitive K2P channels may regulate cellular function with dynamic changes in their ion selectivity. PMID:22948150

  19. Influence of extracellular pH on growth, viability, cell size, acidification activity, and intracellular pH of Lactococcus lactis in batch fermentations.

    PubMed

    Hansen, Gunda; Johansen, Claus Lindvald; Marten, Gunvor; Wilmes, Jacqueline; Jespersen, Lene; Arneborg, Nils

    2016-07-01

    In this study, we investigated the influence of three extracellular pH (pHex) values (i.e., 5.5, 6.5, and 7.5) on the growth, viability, cell size, acidification activity in milk, and intracellular pH (pHi) of Lactococcus lactis subsp. lactis DGCC1212 during pH-controlled batch fermentations. A universal parameter (e.g., linked to pHi) for the description or prediction of viability, specific acidification activity, or growth behavior at a given pHex was not identified. We found viability as determined by flow cytometry to remain high during all growth phases and irrespectively of the pH set point. Furthermore, regardless of the pHex, the acidification activity per cell decreased over time which seemed to be linked to cell shrinkage. Flow cytometric pHi determination demonstrated an increase of the averaged pHi level for higher pH set points, while the pH gradient (pHi-pHex) and the extent of pHi heterogeneity decreased. Cells maintained positive pH gradients at a low pHex of 5.5 and even during substrate limitation at the more widely used pHex 6.5. Moreover, the strain proved able to grow despite small negative or even absent pH gradients at a high pHex of 7.5. The larger pHi heterogeneity at pHex 5.5 and 6.5 was associated with more stressful conditions resulting, e.g., from higher concentrations of non-dissociated lactic acid, while the low pHi heterogeneity at pHex 7.5 most probably corresponded to lower concentrations of non-dissociated lactic acid which facilitated the cells to reach the highest maximum active cell counts of the three pH set points.

  20. A fungal homologue of neuronal calcium sensor-1, Bbcsa1, regulates extracellular acidification and contributes to virulence in the entomopathogenic fungus Beauveria bassiana.

    PubMed

    Fan, Yanhua; Ortiz-Urquiza, Almudena; Kudia, Ramsha A; Keyhani, Nemat O

    2012-07-01

    Neuronal calcium sensor proteins and their homologues participate in transducing extracellular signals that affect intracellular Ca(2+) levels, which in turn regulate enzyme activities, secretion, gene expression and other biological processes. The filamentous fungus Beauveria bassiana is a broad-host-range pathogen of insects that acidifies the extracellular milieu during growth and pathogenesis towards target hosts. A collection of B. bassiana random insertion mutants were screened on pH indicator plates and one mutant was isolated that displayed reduced acidification. The random insertion site was mapped to a gene that displayed homology to the neuronal calcium sensor/frequenin protein family and was designated Bbcsa1. To validate the role of Bbcsa1 in B. bassiana, a targeted gene-knockout was constructed. Data confirmed that Bbcsa1 was not an essential gene and the ΔBbcsa1 strain displayed delayed acidification of the medium when grown in Czapek-Dox medium, as compared with the wild-type parent. HPLC profiling of secreted metabolites did not detect any major changes in the production of organic acids, although downregulation of the membrane H(+) pump/ATPase was noted in the mutant. A slight growth-deficient phenotype was observed for the ΔBbcsa1 strain on Czapek-Dox and potato dextrose media, which was accentuated at high calcium concentrations (500 mM) and 1.5 M sorbitol, but was unaffected by EDTA or SDS. Perturbations in vacuole morphology were also noted for the mutant. Insect bioassays using Galleria mellonella as the target host revealed decreased virulence in the ΔBbcsa1 mutant when applied topically, representing the natural route of infection, but no significant effect was observed when fungal cells were directly injected into target hosts. These results suggest that Bbcsa1 participates in pre-penetration or early penetration events, but is dispensable once the insect cuticle has been breached.

  1. Ocean acidification affects parameters of immune response and extracellular pH in tropical sea urchins Lytechinus variegatus and Echinometra luccunter.

    PubMed

    Leite Figueiredo, Débora Alvares; Branco, Paola Cristina; Dos Santos, Douglas Amaral; Emerenciano, Andrews Krupinski; Iunes, Renata Stecca; Shimada Borges, João Carlos; Machado Cunha da Silva, José Roberto

    2016-11-01

    The rising concentration of atmospheric CO2 by anthropogenic activities is changing the chemistry of the oceans, resulting in a decreased pH. Several studies have shown that the decrease in pH can affect calcification rates and reproduction of marine invertebrates, but little attention has been drawn to their immune response. Thus this study evaluated in two adult tropical sea urchin species, Lytechinus variegatus and Echinometra lucunter, the effects of ocean acidification over a period of 24h and 5days, on parameters of the immune response, the extracellular acid base balance, and the ability to recover these parameters. For this reason, the phagocytic capacity (PC), the phagocytic index (PI), the capacity of cell adhesion, cell spreading, cell spreading area of phagocytic amebocytes in vitro, and the coelomic fluid pH were analyzed in animals exposed to a pH of 8.0 (control group), 7.6 and 7.3. Experimental pH's were predicted by IPCC for the future of the two species. Furthermore, a recovery test was conducted to verify whether animals have the ability to restore these physiological parameters after being re-exposed to control conditions. Both species presented a significant decrease in PC, in the pH of coelomic fluid and in the cell spreading area. Besides that, Echinometra lucunter showed a significant decrease in cell spreading and significant differences in coelomocyte proportions. The recovery test showed that the PC of both species increased, also being below the control values. Even so, they were still significantly higher than those exposed to acidified seawater, indicating that with the re-establishment of the pH value the phagocytic capacity of cells tends to restore control conditions. These results demonstrate that the immune system and the coelomic fluid pH of these animals can be affected by ocean acidification. However, the effects of a short-term exposure can be reversible if the natural values ​​are re-established. Thus, the effects of

  2. Proton receptor GPR68 expression in dendritic-cell-like S100β-positive cells of rat anterior pituitary gland: GPR68 induces interleukin-6 gene expression in extracellular acidification.

    PubMed

    Horiguchi, Kotaro; Higuchi, Masashi; Yoshida, Saishu; Nakakura, Takashi; Tateno, Kozue; Hasegawa, Rumi; Takigami, Shu; Ohsako, Shunji; Kato, Takako; Kato, Yukio

    2014-11-01

    S100β-positive cells, which do not express the classical pituitary hormones, appear to possess multifunctional properties and are assumed to be heterogeneous in the anterior pituitary gland. The presence of several protein markers has shown that S100β-positive cells are composed of populations such as stem/progenitor cells, epithelial cells, astrocytes and dendritic cells. Recently, we succeeded in separating S100β-positive cells into round-cell (dendritic-cell-like) and process-cell types. We also found the characteristic expression of anti-inflammatory factors (interleukin-6, Il-6) and membrane receptors (integrin β-6) in the round type. Here, we further investigate the function of the subpopulation of S100β-positive cells. Since IL-6 is also a paracrine factor that regulates hormone producing-cells, we examine whether a correlation exists among extracellular acid stress, IL-6 and hormone production by using primary cultures of anterior pituitary cells. Dendritic-cell-like S100β-positive cells notably expressed Gpr68 (proton receptor) and Il-6. Furthermore, the expression of Il-6 and proopiomelanocortin (Pomc) was up-regulated by extracellular acidification. The functional role of IL-6 and GPR68 in the gene expression of Pomc during extracellular acidification was also examined. Small interfering RNA for Il-6 up-regulated Pomc expression and that for Gpr68 reversed the down-regulation of Il-6 and up-regulated Pomc expression by extracellular acidification. Thus, S100β-positive dendritic-like cells can sense an increase in extracellular protons via GPR68 and respond by the production of IL-6 in order to suppress the up-regulation of Pomc expression.

  3. Extracellular acidification activates ovarian cancer G-protein-coupled receptor 1 and GPR4 homologs of zebra fish

    SciTech Connect

    Mochimaru, Yuta; Azuma, Morio; Oshima, Natsuki; Ichijo, Yuta; Satou, Kazuhiro; Matsuda, Kouhei; Asaoka, Yoichi; Nishina, Hiroshi; Nakakura, Takashi; Mogi, Chihiro; Sato, Koichi; Okajima, Fumikazu; Tomura, Hideaki

    2015-02-20

    Mammalian ovarian G-protein-coupled receptor 1 (OGR1) and GPR4 are identified as a proton-sensing G-protein-coupled receptor coupling to multiple intracellular signaling pathways. In the present study, we examined whether zebra fish OGR1 and GPR4 homologs (zOGR1 and zGPR4) could sense protons and activate the multiple intracellular signaling pathways and, if so, whether the similar positions of histidine residue, which is critical for sensing protons in mammalian OGR and GPR4, also play a role to sense protons and activate the multiple signaling pathways in the zebra fish receptors. We found that extracellular acidic pH stimulated CRE-, SRE-, and NFAT-promoter activities in zOGR1 overexpressed cells and stimulated CRE- and SRE- but not NFAT-promoter activities in zGPR4 overexpressed cells. The substitution of histidine residues at the 12th, 15th, 162th, and 264th positions from the N-terminal of zOGR1 with phenylalanine attenuated the proton-induced SRE-promoter activities. The mutation of the histidine residue at the 78th but not the 84th position from the N-terminal of zGPR4 to phenylalanine attenuated the proton-induced SRE-promoter activities. These results suggest that zOGR1 and zGPR4 are also proton-sensing G-protein-coupled receptors, and the receptor activation mechanisms may be similar to those of the mammalian receptors. - Highlights: • Zebra fish OGR1 and GPR4 homologs (zOGR1, zGPR4) are proton-sensing receptors. • The signaling pathways activated by zOGR1 and zGPR4 are different. • Histidine residues critical for sensing protons are conserved.

  4. Extracellular acidification activates ovarian cancer G-protein-coupled receptor 1 and GPR4 homologs of zebra fish.

    PubMed

    Mochimaru, Yuta; Azuma, Morio; Oshima, Natsuki; Ichijo, Yuta; Satou, Kazuhiro; Matsuda, Kouhei; Asaoka, Yoichi; Nishina, Hiroshi; Nakakura, Takashi; Mogi, Chihiro; Sato, Koichi; Okajima, Fumikazu; Tomura, Hideaki

    2015-02-20

    Mammalian ovarian G-protein-coupled receptor 1 (OGR1) and GPR4 are identified as a proton-sensing G-protein-coupled receptor coupling to multiple intracellular signaling pathways. In the present study, we examined whether zebra fish OGR1 and GPR4 homologs (zOGR1 and zGPR4) could sense protons and activate the multiple intracellular signaling pathways and, if so, whether the similar positions of histidine residue, which is critical for sensing protons in mammalian OGR and GPR4, also play a role to sense protons and activate the multiple signaling pathways in the zebra fish receptors. We found that extracellular acidic pH stimulated CRE-, SRE-, and NFAT-promoter activities in zOGR1 overexpressed cells and stimulated CRE- and SRE- but not NFAT-promoter activities in zGPR4 overexpressed cells. The substitution of histidine residues at the 12th, 15th, 162th, and 264th positions from the N-terminal of zOGR1 with phenylalanine attenuated the proton-induced SRE-promoter activities. The mutation of the histidine residue at the 78th but not the 84th position from the N-terminal of zGPR4 to phenylalanine attenuated the proton-induced SRE-promoter activities. These results suggest that zOGR1 and zGPR4 are also proton-sensing G-protein-coupled receptors, and the receptor activation mechanisms may be similar to those of the mammalian receptors.

  5. Ocean Acidification

    EPA Pesticide Factsheets

    Ocean and coastal acidification is an emerging issue caused by increasing amounts of carbon dioxide being absorbed by seawater. Changing seawater chemistry impacts marine life, ecosystem services, and humans. Learn what EPA is doing and what you can do.

  6. Lake acidification

    SciTech Connect

    Dobson, J.E.; Peplies, R.W.; Rush, R.M.

    1987-06-01

    This paper examined a National Research Council (NRC) report called Acid Deposition: Long-Term Trends. The report has been the final word on acid deposition as the cause of acidification of lakes. The authors considered it important that the tentative nature of this report be kept in perspective so that the work of the NRC would promote rather than inhibit scientific inquiry on the lake acidification issue. In this spirit, this report proposed that degradation of storm damaged trees could increase the acidity of the forest humus and as a result the ground water which would fed local streams and lakes. They proposed that extensive forest blowdown could be a factor in acidification of surface waters.

  7. Ocean Acidification

    ERIC Educational Resources Information Center

    Ludwig, Claudia; Orellana, Mónica V.; DeVault, Megan; Simon, Zac; Baliga, Nitin

    2015-01-01

    The curriculum module described in this article addresses the global issue of ocean acidification (OA) (Feely 2009; Figure 1). OA is a harmful consequence of excess carbon dioxide (CO[subscript 2]) in the atmosphere and poses a threat to marine life, both algae and animal. This module seeks to teach and help students master the cross-disciplinary…

  8. Indicators: Acidification

    EPA Pesticide Factsheets

    Acidification is a broad term that refers to the process by which aquatic ecosystems become more acidic. Acid rain and acid mine drainage are major sources of acidifying compounds, lowering the pH below the range where most living organisms function.

  9. The positive relationship between ocean acidification and pollution.

    PubMed

    Zeng, Xiangfeng; Chen, Xijuan; Zhuang, Jie

    2015-02-15

    Ocean acidification and pollution coexist to exert combined effects on the functions and services of marine ecosystems. Ocean acidification can increase the biotoxicity of heavy metals by altering their speciation and bioavailability. Marine pollutants, such as heavy metals and oils, could decrease the photosynthesis rate and increase the respiration rate of marine organisms as a result of biotoxicity and eutrophication, facilitating ocean acidification to varying degrees. Here we review the complex interactions between ocean acidification and pollution in the context of linkage of multiple stressors to marine ecosystems. The synthesized information shows that pollution-affected respiration acidifies coastal oceans more than the uptake of anthropogenic carbon dioxide. Coastal regions are more vulnerable to the negative impact of ocean acidification due to large influxes of pollutants from terrestrial ecosystems. Ocean acidification and pollution facilitate each other, and thus coastal environmental protection from pollution has a large potential for mitigating acidification risk.

  10. Glucose-Induced Acidification in Yeast Cultures

    ERIC Educational Resources Information Center

    Myers, Alan; Bourn, Julia; Pool, Brynne

    2005-01-01

    We present an investigation (for A-level biology students and equivalent) into the mechanism of glucose-induced extracellular acidification in unbuffered yeast suspensions. The investigation is designed to enhance understanding of aspects of the A-level curriculum that relate to the phenomenon (notably glucose catabolism) and to develop key skills…

  11. Ocean acidification postcards

    USGS Publications Warehouse

    Schreppel, Heather A.; Cimitile, Matthew J.

    2011-01-01

    The U.S. Geological Survey (USGS) is conducting research on ocean acidification in polar, temperate, subtropical, and tropical regions including the Arctic, West Florida Shelf, and the Caribbean. Project activities include field assessment, experimental laboratory studies, and evaluation of existing data. The USGS is participating in international and interagency working groups to develop research strategies to increase understanding of the global implications of ocean acidification. Research strategies include new approaches for seawater chemistry observation and modeling, assessment of physiological effects on organisms, changes in marine ecosystem structure, new technologies, and information resources. These postcards highlight ongoing USGS research efforts in ocean acidification and carbon cycling in marine and coastal ecosystems in three different regions: polar, temperate, and tropical. To learn more about ocean acidification visit: http://coastal.er.usgs.gov/ocean-acidification/.

  12. Communicating Ocean Acidification

    ERIC Educational Resources Information Center

    Pope, Aaron; Selna, Elizabeth

    2013-01-01

    Participation in a study circle through the National Network of Ocean and Climate Change Interpretation (NNOCCI) project enabled staff at the California Academy of Sciences to effectively engage visitors on climate change and ocean acidification topics. Strategic framing tactics were used as staff revised the scripted Coral Reef Dive program,…

  13. Acidification and Acid Rain

    NASA Astrophysics Data System (ADS)

    Norton, S. A.; Veselã½, J.

    2003-12-01

    Air pollution by acids has been known as a problem for centuries (Ducros, 1845; Smith, 1872; Camuffo, 1992; Brimblecombe, 1992). Only in the mid-1900s did it become clear that it was a problem for more than just industrially developed areas, and that precipitation quality can affect aquatic resources ( Gorham, 1955). The last three decades of the twentieth century saw tremendous progress in the documentation of the chemistry of the atmosphere, precipitation, and the systems impacted by acid atmospheric deposition. Chronic acidification of ecosystems results in chemical changes to soil and to surface waters and groundwater as a result of reduction of base cation supply or an increase in acid (H+) supply, or both. The most fundamental changes during chronic acidification are an increase in exchangeable H+ or Al3+ (aluminum) in soils, an increase in H+ activity (˜concentration) in water in contact with soil, and a decrease in alkalinity in waters draining watersheds. Water draining from the soil is acidified and has a lower pH (=-log [H+]). As systems acidify, their biotic community changes.Acidic surface waters occur in many parts of the world as a consequence of natural processes and also due to atmospheric deposition of strong acid (e.g., Canada, Jeffries et al. (1986); the United Kingdom, Evans and Monteith (2001); Sweden, Swedish Environmental Protection Board (1986); Finland, Forsius et al. (1990); Norway, Henriksen et al. (1988a); and the United States (USA), Brakke et al. (1988)). Concern over acidification in the temperate regions of the northern hemisphere has been driven by the potential for accelerating natural acidification by pollution of the atmosphere with acidic or acidifying compounds. Atmospheric pollution ( Figure 1) has resulted in an increased flux of acid to and through ecosystems. Depending on the ability of an ecosystem to neutralize the increased flux of acidity, acidification may increase only imperceptibly or be accelerated at a rate that

  14. Acidification and its policy implications

    SciTech Connect

    Schneider, T.

    1986-01-01

    Papers review the effects of acidification on the aquatic environment, flora, fauna and vegetation, and materials, and also review cultural properties, the ecology as a whole and the economic impact of acidification. Papers on forest-dieback cover potential stress factors and the effects on materials and cultural properties. Scientific research results are presented which deal with models as tools for abatement strategies, and underline the application of models in policy-making. Review papers of scientific research on acidification are followed by presentations by representatives of the EEC member countries giving an overview of national research program and policies regarding acidification.

  15. Exertional Rhabdomyolysis after Spinning

    PubMed Central

    Jeong, Youjin; Oh, Eun-Jung; Ahn, Ah-Leum; Choi, Jae-Kyung; Cho, Dong-Yung

    2016-01-01

    Any strenuous muscular exercise may trigger rhabdomyolysis. We report an episode of clinically manifested exertional rhabdomyolysis due to stationary cycling, commonly known as spinning. Reports of spinning-related rhabdomyolysis are rare in the English literature, and the current case appears to be the first such case reported in South Korea. A previously healthy 21-year-old Asian woman presented with severe thigh pain and reddish-brown urinary discoloration 24–48 hours after attending a spinning class at a local gymnasium. Paired with key laboratory findings, her symptoms were suggestive of rhabdomyolysis. She required hospital admission to sustain renal function through fluid resuscitation therapy and fluid balance monitoring. Because exertional rhabdomyolysis may occur in any unfit but otherwise healthy individual who indulges in stationary cycling, the potential health risks of this activity must be considered. PMID:27900075

  16. Assessing approaches to determine the effect of ocean acidification on bacterial processes

    NASA Astrophysics Data System (ADS)

    Burrell, Timothy J.; Maas, Elizabeth W.; Teesdale-Spittle, Paul; Law, Cliff S.

    2016-08-01

    Bacterial extracellular enzymes play a significant role in the degradation of labile organic matter and nutrient availability in the open ocean. Although bacterial production and extracellular enzymes may be affected by ocean acidification, few studies to date have considered the methodology used to measure enzyme activity and bacterial processes. This study investigated the potential artefacts in determining the response of bacterial growth and extracellular glucosidase and aminopeptidase activity to ocean acidification as well as the relative effects of three different acidification techniques. Tests confirmed that the observed effect of pH on fluorescence of artificial fluorophores, and the influence of the MCA fluorescent substrate on seawater sample pH, were both overcome by the use of Tris buffer. In experiments testing different acidification methods, bubbling with CO2 gas mixtures resulted in higher β-glucosidase activity and 15-40 % higher bacterial abundance, relative to acidification via gas-permeable silicon tubing and acid addition (HCl). Bubbling may stimulate carbohydrate degradation and bacterial growth, leading to the incorrect interpretation of the impacts of ocean acidification on organic matter cycling.

  17. Acidification in Finland

    SciTech Connect

    Kauppi, P.; Kenttamies, K.; Anttila, P. )

    1990-01-01

    This book reports on the acidic deposition issue in Finland, representing the main research report of the Finnish Acidification Research Program (HAPRO), designed to support research in this field between 1985 and 1989 with a total budget of about 50 million FIM (about 11 million USD). This overview focuses on a wide selection of acidic deposition topics from an analytical perspective, detailing the background, materials, methods and results of different individual studies. Reports include emission inventories, deposition studies, forest vegetation studies, forest soil investigations, lake chemistry surveys, etc.

  18. Acidification increases microbial polysaccharide degradation in the ocean

    NASA Astrophysics Data System (ADS)

    Piontek, J.; Lunau, M.; Händel, N.; Borchard, C.; Wurst, M.; Engel, A.

    2009-12-01

    With the accumulation of anthropogenic carbon dioxide (CO2), a proceeding decline in seawater pH has been induced that is referred to as ocean acidification. The ocean's capacity for CO2 storage is strongly affected by biological processes, whose feedback potential is difficult to evaluate. The main source of CO2 in the ocean is the decomposition and subsequent respiration of organic molecules by heterotrophic bacteria. However, very little is known about potential effects of ocean acidification on bacterial degradation activity. This study reveals that the degradation of polysaccharides, a major component of marine organic matter, by bacterial extracellular enzymes was significantly accelerated during experimental simulation of ocean acidification. Results were obtained from pH perturbation experiments, where rates of extracellular α- and β-glucosidase were measured and the loss of neutral and acidic sugars from phytoplankton-derived polysaccharides was determined. Our study suggests that a faster bacterial turnover of polysaccharides at lowered ocean pH has the potential to affect the cycling of organic carbon in the future ocean by weakening the biological carbon pump and increasing the respiratory production of CO2.

  19. Acidification increases microbial polysaccharide degradation in the ocean

    NASA Astrophysics Data System (ADS)

    Piontek, J.; Lunau, M.; Händel, N.; Borchard, C.; Wurst, M.; Engel, A.

    2010-05-01

    With the accumulation of anthropogenic carbon dioxide (CO2), a proceeding decline in seawater pH has been induced that is referred to as ocean acidification. The ocean's capacity for CO2 storage is strongly affected by biological processes, whose feedback potential is difficult to evaluate. The main source of CO2 in the ocean is the decomposition and subsequent respiration of organic molecules by heterotrophic bacteria. However, very little is known about potential effects of ocean acidification on bacterial degradation activity. This study reveals that the degradation of polysaccharides, a major component of marine organic matter, by bacterial extracellular enzymes was significantly accelerated during experimental simulation of ocean acidification. Results were obtained from pH perturbation experiments, where rates of extracellular α- and β-glucosidase were measured and the loss of neutral and acidic sugars from phytoplankton-derived polysaccharides was determined. Our study suggests that a faster bacterial turnover of polysaccharides at lowered ocean pH has the potential to reduce carbon export and to enhance the respiratory CO2 production in the future ocean.

  20. NHE1 promotes invadopodial ECM proteolysis through acidification of the peri-invadopodial space.

    PubMed

    Busco, Giovanni; Cardone, Rosa A; Greco, Maria R; Bellizzi, Antonia; Colella, Matilde; Antelmi, Ester; Mancini, Maria T; Dell'Aquila, Maria E; Casavola, Valeria; Paradiso, Angelo; Reshkin, Stephan J

    2010-10-01

    Extracellular matrix (ECM) degradation is a critical process in tumor cell invasion and requires membrane and released proteases focalized at membrane structures called invadopodia. While extracellular acidification is important in driving tumor invasion, the structure/function mechanisms underlying this regulation are still unknown. Invadopodia are similar in structure and function to osteoclast podosomes responsible for bone degradation, and extracellular acidification is central to podosome action, suggesting that it could also be for invadopodial function. Here, utilizing a novel system for in situ zymography in native matrices, we show that the Na(+)/H(+) exchanger (NHE1) and NHE1-generated extracellular acidification are localized at and necessary for invadopodial-dependent ECM degradation, thereby promoting tumor invasion. Stimulation with EGF increased both NHE1-dependent proton secretion and ECM degradation. Manipulation of the NHE1 expression by RNA interference or activity via either transport-deficient mutation or the specific inhibitor cariporide confirmed that NHE1 expression and activity are required for invadopodia-mediated ECM degradation. Taken together, our data show a concordance among NHE1 localization, the generation of a well-defined acidic extracellular pH in the nanospace surrounding invadopodia, and matrix-degrading activity at invadopodia of human malignant breast carcinoma cells, providing a structural basis for the role of NHE1 in invasion and identifying NHE1 as a strategic target for therapeutic intervention.

  1. Vinyl acetate induces intracellular acidification in mouse oral buccal epithelial cells.

    PubMed

    Nakamoto, Tetsuji; Wagner, Mark; Melvin, James E; Bogdanffy, Matthew S

    2005-08-14

    Vinyl acetate exposure in drinking water has been associated with tumor formation in the upper gastrointestinal tract of rats and mice. One potential mechanism for inducing carcinogenesis involves acidification of the intracellular environment due to the metabolism of vinyl acetate to acetic acid. Prolonged intracellular acidification is thought to produce cytotoxic and/or mitogenic responses that are the sentinel pharmacodynamic steps toward cancer. To determine whether exposure to vinyl acetate affects the intracellular pH of intact oral cavity tissue, isolated mouse oral buccal epithelium was loaded with the pH-sensitive dye BCECF, and then exposed to vinyl acetate concentrations ranging from 10 to 1000 microM for up to 4 min. Extracellular vinyl acetate exposure induced a progressive intracellular acidification that was reversible upon removal of the vinyl acetate. The rate of the acidification was concentration-dependent and increased exponentially within the concentration range tested. The magnitude of the vinyl acetate-induced acidification was inhibited by pretreatment with the carboxylesterase inhibitor bis(p-nitrophenyl)phosphate. These results are consistent with the hypothesis that vinyl acetate contributes to the generation and progression of oral cavity tumors via a process of intracellular acidification. Such a process has been proposed to have practical dose-response thresholds below which the intracellular environment can be maintained within homeostatic bounds and the contribution of exposure to carcinogenic risk is negligible.

  2. When exercise causes exertional rhabdomyolysis.

    PubMed

    Furman, Janet

    2015-04-01

    Exertional rhabdomyolysis is a clinical condition caused by intense, repetitive exercise or a sudden increase in exercise in an untrained person, although rhabdomyolysis can occur in trained athletes. In many cases, the presentation of early, uncomplicated rhabdomyolysis is subtle, but serious complications such as renal failure, compartment syndrome, and dysrhythmias may arise if severe exertional rhabdomyolysis is undiagnosed or untreated. Management is further complicated by the lack of concrete management guidelines for treating rhabdomyolysis and returning patients to activity.

  3. Some species tolerate ocean acidification

    NASA Astrophysics Data System (ADS)

    Balcerak, Ernie

    2011-12-01

    Increasing carbon dioxide levels lead to rising ocean acidity, which can harm corals and many other species of ocean life. Acidification causes calcium carbonate, which corals usually need to build skeletons, to dissolve. “Every day, ocean acidification is taking up the weight of 6 million midsize cars' worth of carbon, said Nina Keul, a graduate student at the Alfred Wegener Institute for Polar and Marine Research in Germany during a 7 December press conference at the AGU Fall Meeting. Somewhat surprising, though, is that some species are more tolerant of acidic conditions than scientists had expected. For instance, Keul exposed a species of foraminifera, Ammonia tepida, to seawater with varying acidity and varying carbonate ion concentrations. Previous studies had found that foraminifera growth declined with decreasing carbonate levels, but Keul's foraminifera continued to grow in the acidic conditions. She said that the mechanism that allows this species to tolerate the low carbonate conditions is as yet unknown.

  4. Exertional Rhabdomyolysis in the Athlete

    PubMed Central

    Tietze, David C.; Borchers, James

    2014-01-01

    Context: Exertional rhabdomyolysis is a relatively uncommon but potentially fatal condition affecting athletes that requires prompt recognition and appropriate management. Evidence Acquisition: A search of the PubMed database from 2003 to 2013 using the term exertional rhabdomyolysis was performed. Further evaluation of the bibliographies of articles expanded the evidence. Study Design: Clinical review. Level of Evidence: Level 3. Results: Exertional rhabdomyolysis (ER) is a relatively uncommon condition with an incidence of approximately 29.9 per 100,000 patient years but can have very serious consequences of muscle ischemia, cardiac arrhythmia, and death. The athlete will have pain, weakness, and swelling in the muscles affected as well as significantly elevated levels of creatine kinase (CK). Hydration is the foundation for any athlete with ER; management can also include dialysis or surgery. Stratifying the athlete into high- or low-risk categories can determine if further workup is warranted. Conclusion: Exertional rhabdomyolysis evaluation requires a history, physical examination, and serology for definitive diagnosis. Treatment modalities should include rest and hydration. Return to play and future workup should be determined by the risk stratification of the athlete. Strength-of-Recommendation Taxonomy (SORT): C. PMID:24982707

  5. 1-Naphthyl Acetate-Dependent Medium Acidification by Zea mays L. Coleoptile Segments 1

    PubMed Central

    Salguero, Julio; Calatayud, Angeles; Gonzalez-Daros, Francisco; del Valle-Tascon, Secundino

    1991-01-01

    Zea mays L. cv INRA 5a coleoptile segments ecidify the incubation medium on the addition of 1-naphthyl acetate (1-NA). The buffering capacity of the bathing solution increases during 1-NA stimulated medium acidification. The solution bathing the 1-NA treated coleoptile segment was analyzed by high performance liquid chromatography. A considerable amount of acetic acid was detected in the bathing solution used to measure 1-NA-dependent medium acidification. For the first time, the data demonstrate directly the release of acetic acid from 1-NA. The extent of medium acidification was proportional to 1-NA concentration. Simultaneous measurement of medium acidification and acetate content upon addition of 1-NA showed that both processes were temporally correlated. The stoichiometry of proton equivalents to acetate ion was 0.966. Addition of 50 micromolar N,N′-dicyclohexylcarbodiimide had little effect on 1-NA-dependent medium acidification. The results indicate that 1-NA is hydrolyzed in the extracellular space of coleoptile cells. PMID:16668108

  6. Biotic Proxies For Ocean Acidification?

    NASA Astrophysics Data System (ADS)

    Thomas, E.

    2013-12-01

    Present and future high atmospheric pCO2 levels have caused acidification of the oceans, which has led to studies of past ocean acidification and its biotic response in the geological record (1). Therefore we need proxies for past acidification. Geochemical proxies for ocean pH are being developed (e.g., boron based), and various trace element and stable isotope proxies in part reflect carbonate saturation levels. In addition to geochemical proxies, the relative abundances of some benthic foraminiferal species might serve as proxies for the saturation state of bottom or pore waters. In general, pore waters are less carbonate-saturated than bottom waters, and infaunal benthic foraminifera calcify in such less saturated waters. The relative abundance of infaunal species of benthic foraminifera has commonly been used as a proxy for a high food supply (and/or oxygen depleted bottom or pore waters). This proxy (infaunal %), however, can be used to indicate high food/low oxygen ONLY in the absence of evidence for carbonate dissolution, and is a qualitative proxy for carbonate undersaturation of bottom and pore waters in the presence of such evidence (2). The living species Nuttallides umbonifer can calcify in carbonate-corrosive waters (i.e., below the lysocline), and its extinct Paleogene ancestor N. truempyi may have had a similar tolerance, in view of the fact that it is a deep-water species and commonly abundant in samples which otherwise contain agglutinant taxa only. The pattern of deep-sea benthic foraminiferal abundances across the Paleocene Eocene Thermal Maximum at South Atlantic Site 1263 (Walvis Ridge) can then be interpreted as a time sequence indicative of full dissolution (no calcareous benthics) at the start of the event, followed by strong dissolution (mainly infaunal taxa with relatively high % of N. truempyi), moderate dissolution (high % of N. truempyi), and return to background conditions. On the opposite extreme, extinction of pelagic calcifiers at

  7. Forest blowdown and lake acidification

    SciTech Connect

    Dobson, J.E.; Rush, R.M. ); Peplies, R.W. )

    1990-01-01

    The authors examine the role of forest blowdown in lake acidification. The approach combines geographic information systems (GIS) and digital remote sensing with traditional field methods. The methods of analysis consist of direct observation, interpretation of satellite imagery and aerial photographs, and statistical comparison of two geographical distributions-one representing forest blow-down and another representing lake chemistry. Spatial and temporal associations between surface water pH and landscape disturbance are strong and consistent in the Adirondack Mountains of New York. In 43 Adirondack Mountain watersheds, lake pH is associated with the percentage of the watershed area blown down and with hydrogen ion deposition (Spearman rank correlation coefficients of {minus}0.67 and {minus}0.73, respectively). Evidence of a temporal association is found at Big Moose Lake and Jerseyfield Lake in New York and the Lygners Vider Plateau of Sweden. They conclude that forest blowdown facilities the acidification of some lakes by altering hydrologic pathways so that waters (previously acidified by acid deposition and/or other sources) do not experience the neutralization normally available through contact with subsurface soils and bedrock. Increased pipeflow is suggested as a mechanism that may link the biogeochemical impacts of forest blowdown to lake chemistry.

  8. Geobiological Responses to Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Potts, D. C.

    2008-12-01

    During 240Ma of evolution, scleractinian corals survived major changes in ocean chemistry, yet recent concerns with rapid acidification after ca. 40Ma of almost constant oceanic pH have tended to distract attention from natural pH variation in coastal waters, where most corals and reefs occur. Unaltered skeletal environmental proxies reflect conditions experienced by individual organisms, with any variation on micro- habitat and micro-time scales appropriate for that individual's ecology, behavior and physiology, but proxy interpretation usually extrapolates to larger spatial (habitat, region to global) and temporal (seasonal, annual, interannual) scales. Therefore, predicting consequences of acidification for both corals and reefs requires greater understanding of: 1. Many potential indirect consequences of pH change that may affect calcification and/or carbonate accretion: e.g. an individual's developmental rates, growth, final size, general physiology and reproductive success; its population's distribution and abundance, symbionts, food availability, predators and pathogens; and its community and ecosystem services. 2. Potentially diverse responses to declining pH, ranging from non-evolutionary, rapid physiological changes (acclimation) or long term (seasonal to interannual) plasticity (acclimatization) of individuals, through genetic adaptation in local populations, and up to directional changes in species" characteristics and/or radiations/extinctions. 3. The evolutionary and environmental history of an organism's lineage, its ecological (own lifetime) exposure to environmental variation, and "pre-adaptation" via other factors acting on correlated characters.

  9. Acidification in the epidermis and the role of secretory phospholipases

    PubMed Central

    Chan, Aegean

    2011-01-01

    The function of the epidermis is to form an effective barrier between the dry, external environment and the interior of the body. The barrier specifically resides in the extracellular lipid membranes of the stratum corneum (SC) and an acidic pH is necessary to maintain its competency against various insults. The purpose of this review is to explore the mechanisms which are postulated to contribute to the acidification of the stratum corneum, including both exogenous and endogenous sources. However, recent research as pointed to several endogenous mechanisms as the major source of acidification, including a sodium/proton pump (NHE1) and free fatty acid conversion from phospholipids by secretory phospholipase A2 (sPLA2). sPLA2 has been shown to play a central role in the formation of the SC “acid mantle” in the early maturation of the epidermis postnatally. Many aspects of this enzyme family are complex and still being elucidated in research and the most recent findings on the localization and functions of sPL A2-IB, -IIA, -IIC, -IID, -IIE, -IIF, -III, -V, -X and -XII in the epidermis are presented here. Given their role in inflammatory dermatoses, such as psoriasis and atopic dermatitis, understanding this complex enzyme family can lead to novel, life-changing therapies. PMID:21695017

  10. Ocean acidification impairs crab foraging behaviour

    PubMed Central

    Dodd, Luke F.; Grabowski, Jonathan H.; Piehler, Michael F.; Westfield, Isaac; Ries, Justin B.

    2015-01-01

    Anthropogenic elevation of atmospheric CO2 is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism's ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO2 levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour. PMID:26108629

  11. Ocean acidification impairs crab foraging behaviour.

    PubMed

    Dodd, Luke F; Grabowski, Jonathan H; Piehler, Michael F; Westfield, Isaac; Ries, Justin B

    2015-07-07

    Anthropogenic elevation of atmospheric CO2 is driving global-scale ocean acidification, which consequently influences calcification rates of many marine invertebrates and potentially alters their susceptibility to predation. Ocean acidification may also impair an organism's ability to process environmental and biological cues. These counteracting impacts make it challenging to predict how acidification will alter species interactions and community structure. To examine effects of acidification on consumptive and behavioural interactions between mud crabs (Panopeus herbstii) and oysters (Crassostrea virginica), oysters were reared with and without caged crabs for 71 days at three pCO2 levels. During subsequent predation trials, acidification reduced prey consumption, handling time and duration of unsuccessful predation attempt. These negative effects of ocean acidification on crab foraging behaviour more than offset any benefit to crabs resulting from a reduction in the net rate of oyster calcification. These findings reveal that efforts to evaluate how acidification will alter marine food webs should include quantifying impacts on both calcification rates and animal behaviour.

  12. Ocean Fertilization and Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Cao, L.; Caldeira, K.

    2008-12-01

    It has been suggested that ocean fertilization could help diminish ocean acidification. Here, we quantitatively evaluate this suggestion. Ocean fertilization is one of several ocean methods proposed to mitigate atmospheric CO2 concentrations. The basic idea of this method is to enhance the biological uptake of atmospheric CO2 by stimulating net phytoplankton growth through the addition of iron to the surface ocean. Concern has been expressed that ocean fertilization may not be very effective at reducing atmospheric CO2 concentrations and may produce unintended environmental consequences. The rationale for thinking that ocean fertilization might help diminish ocean acidification is that dissolved inorganic carbon concentrations in the near-surface equilibrate with the atmosphere in about a year. If ocean fertilization could reduce atmospheric CO2 concentrations, it would also reduce surface ocean dissolved inorganic carbon concentrations, and thus diminish the degree of ocean acidification. To evaluate this line of thinking, we use a global ocean carbon cycle model with a simple representation of marine biology and investigate the maximum potential effect of ocean fertilization on ocean carbonate chemistry. We find that the effect of ocean fertilization on ocean acidification depends, in part, on the context in which ocean fertilization is performed. With fixed emissions of CO2 to the atmosphere, ocean fertilization moderately mitigates changes in ocean carbonate chemistry near the ocean surface, but at the expense of further acidifying the deep ocean. Under the SRES A2 CO2 emission scenario, by year 2100 simulated atmospheric CO2, global mean surface pH, and saturation state of aragonite is 965 ppm, 7.74, and 1.55 for the scenario without fertilization and 833 ppm, 7.80, and 1.71 for the scenario with 100-year (between 2000 and 2100) continuous fertilization for the global ocean (For comparison, pre-industrial global mean surface pH and saturation state of

  13. Freshwater plankton response to acidification

    SciTech Connect

    Havens, K.E. III

    1984-01-01

    An in situ bag experiment was performed at circum-neutral Lake O'Woods, West Virgnia, where lakewater inside large enclosures was gradually acidified to pH 6.5 or 4.5, in order to examine plankton community succession during acidification. At acidic Cheat Lake (pH ca. 4.5), West Virginia, in situ feeding experiments and bag experiments were performed to evaluate the importance of selective herbivory in controlling algal community structure in acid lakes. The Lake O'Woods plankton community changed dramatically with increasing acidity. Species richness declined, as sensitive forms were eliminated. The phytoplankton became dominated by Peridinium inconspicuum and the filamentous green alga Mougoetia viridis, while euglenophytes, chrysophytes and diatoms were eliminated. Bosmina longirostris and Chydorus sphaericus were the dominant crustaceans at low pH. Only a single rotifer, Lecane luna, tolerated the acidic conditions. All others were eliminated at pH below 6.0. Despite the rapid acidification regime, the nature of the plankton community changes, as well as community structure at pH 4.5, were as predicted in the literature from earlier comparative studies. During the Cheat Lake feeding experiments, P. inconspicuum was always the extreme dominant alga. However, it was never significantly grazed by the herbivorous zooplankton. The herbivores selectively consumed the other, more rare algae, particularly the unicellular greens. Despite the existence of selective herbivory, algal community structure did not change inside enclosures where herbivores were excluded in a 26 and an 18 day experiment. Cheat Lake herbivores seem to have little effect on algal community structure. This is probably also true in most precipitation-acidified lakes. However, herbivore biomass, and also energy flow to higher trophic levels, may be suppressed because most of the primary producer biomass is inedible.

  14. Regulation of innate immunity by extracellular nucleotides

    PubMed Central

    Gorini, Stefania; Gatta, Lucia; Pontecorvo, Laura; Vitiello, Laura; la Sala, Andrea

    2013-01-01

    Extracellular ATP (eATP) is the most abundant among extracellular nucleotides and is commonly considered as a classical danger signal, which stimulates immune responses in the presence of tissue injury. In fact, increased nucleotide concentration in the extracellular space is generally closely associated with tissue stress or damage. However non-lytic nucleotide release may also occur in many cell types under a variety of conditions. Extracellular nucleotides are sensed by a class of plasma membrane receptors called P2 purinergic receptors (P2Rs). P2 receptors are expressed by all immunological cells and their activation elicits different responses. Extracellular ATP can act as an initiator or terminator of immune responses being able to induce different effects on immune cells depending on the pattern of P2 receptors engaged, the duration of the stimulus and its concentration in the extracellular milieu. Millimolar (high) concentrations of extracellular ATP, induce predominantly proinflammatory effects, while micromolar (low) doses exert mainly tolerogenic/immunosuppressive action. Moreover small, but significant differences in the pattern of P2 receptor expression in mice and humans confer diverse capacities of ATP in regulating the immune response. PMID:23358447

  15. Optogenetic Acidification of Synaptic Vesicles and Lysosomes

    PubMed Central

    Grauel, M. Katharina; Wozny, Christian; Bentz, Claudia; Blessing, Anja; Rosenmund, Tanja; Jentsch, Thomas J.; Schmitz, Dietmar; Hegemann, Peter; Rosenmund, Christian

    2016-01-01

    Acidification is required for the function of many intracellular organelles, but methods to acutely manipulate their intraluminal pH have not been available. Here we present a targeting strategy to selectively express the light-driven proton pump Arch3 on synaptic vesicles. Our new tool, pHoenix, can functionally replace endogenous proton pumps, enabling optogenetic control of vesicular acidification and neurotransmitter accumulation. Under physiological conditions, glutamatergic vesicles are nearly full, as additional vesicle acidification with pHoenix only slightly increased the quantal size. By contrast, we found that incompletely filled vesicles exhibited a lower release probability than full vesicles, suggesting preferential exocytosis of vesicles with high transmitter content. Our subcellular targeting approach can be transferred to other organelles, as demonstrated for a pHoenix variant that allows light-activated acidification of lysosomes. PMID:26551543

  16. Intracellular acidification is required for full activation of the sweet taste receptor by miraculin

    PubMed Central

    Sanematsu, Keisuke; Kitagawa, Masayuki; Yoshida, Ryusuke; Nirasawa, Satoru; Shigemura, Noriatsu; Ninomiya, Yuzo

    2016-01-01

    Acidification of the glycoprotein, miraculin (MCL), induces sweet taste in humans, but not in mice. The sweet taste induced by MCL is more intense when acidification occurs with weak acids as opposed to strong acids. MCL interacts with the human sweet receptor subunit hTAS1R2, but the mechanisms by which the acidification of MCL activates the sweet taste receptor remain largely unexplored. The work reported here speaks directly to this activation by utilizing a sweet receptor TAS1R2 + TAS1R3 assay. In accordance with previous data, MCL-applied cells displayed a pH dependence with citric acid (weak acid) being right shifted to that with hydrochloric acid (strong acid). When histidine residues in both the intracellular and extracellular region of hTAS1R2 were exchanged for alanine, taste-modifying effect of MCL was reduced or abolished. Stronger intracellular acidification of HEK293 cells was induced by citric acid than by HCl and taste-modifying effect of MCL was proportional to intracellular pH regardless of types of acids. These results suggest that intracellular acidity is required for full activation of the sweet taste receptor by MCL. PMID:26960429

  17. Studying ocean acidification in the Arctic Ocean

    USGS Publications Warehouse

    Robbins, Lisa

    2012-01-01

    The U.S. Geological Survey (USGS) partnership with the U.S. Coast Guard Ice Breaker Healey and its United Nations Convention Law of the Sea (UNCLOS) cruises has produced new synoptic data from samples collected in the Arctic Ocean and insights into the patterns and extent of ocean acidification. This framework of foundational geochemical information will help inform our understanding of potential risks to Arctic resources due to ocean acidification.

  18. Coral Carbonic Anhydrases: Regulation by Ocean Acidification.

    PubMed

    Zoccola, Didier; Innocenti, Alessio; Bertucci, Anthony; Tambutté, Eric; Supuran, Claudiu T; Tambutté, Sylvie

    2016-06-03

    Global change is a major threat to the oceans, as it implies temperature increase and acidification. Ocean acidification (OA) involving decreasing pH and changes in seawater carbonate chemistry challenges the capacity of corals to form their skeletons. Despite the large number of studies that have investigated how rates of calcification respond to ocean acidification scenarios, comparatively few studies tackle how ocean acidification impacts the physiological mechanisms that drive calcification itself. The aim of our paper was to determine how the carbonic anhydrases, which play a major role in calcification, are potentially regulated by ocean acidification. For this we measured the effect of pH on enzyme activity of two carbonic anhydrase isoforms that have been previously characterized in the scleractinian coral Stylophora pistillata. In addition we looked at gene expression of these enzymes in vivo. For both isoforms, our results show (1) a change in gene expression under OA (2) an effect of OA and temperature on carbonic anhydrase activity. We suggest that temperature increase could counterbalance the effect of OA on enzyme activity. Finally we point out that caution must, thus, be taken when interpreting transcriptomic data on carbonic anhydrases in ocean acidification and temperature stress experiments, as the effect of these stressors on the physiological function of CA will depend both on gene expression and enzyme activity.

  19. Ocean acidification challenges copepod phenotypic plasticity

    NASA Astrophysics Data System (ADS)

    Vehmaa, Anu; Almén, Anna-Karin; Brutemark, Andreas; Paul, Allanah; Riebesell, Ulf; Furuhagen, Sara; Engström-Öst, Jonna

    2016-11-01

    Ocean acidification is challenging phenotypic plasticity of individuals and populations. Calanoid copepods (zooplankton) are shown to be fairly plastic against altered pH conditions, and laboratory studies indicate that transgenerational effects are one mechanism behind this plasticity. We studied phenotypic plasticity of the copepod Acartia sp. in the course of a pelagic, large-volume mesocosm study that was conducted to investigate ecosystem and biogeochemical responses to ocean acidification. We measured copepod egg production rate, egg-hatching success, adult female size and adult female antioxidant capacity (ORAC) as a function of acidification (fCO2 ˜ 365-1231 µatm) and as a function of quantity and quality of their diet. We used an egg transplant experiment to reveal whether transgenerational effects can alleviate the possible negative effects of ocean acidification on offspring development. We found significant negative effects of ocean acidification on adult female size. In addition, we found signs of a possible threshold at high fCO2, above which adaptive maternal effects cannot alleviate the negative effects of acidification on egg-hatching and nauplii development. We did not find support for the hypothesis that insufficient food quantity (total particulate carbon < 55 µm) or quality (C : N) weakens the transgenerational effects. However, females with high-ORAC-produced eggs with high hatching success. Overall, these results indicate that Acartia sp. could be affected by projected near-future CO2 levels.

  20. Ocean acidification challenges copepod reproductive plasticity

    NASA Astrophysics Data System (ADS)

    Vehmaa, A.; Almén, A.-K.; Brutemark, A.; Paul, A.; Riebesell, U.; Furuhagen, S.; Engström-Öst, J.

    2015-11-01

    Ocean acidification is challenging phenotypic plasticity of individuals and populations. Calanoid copepods (zooplankton) are shown to be fairly plastic against altered pH conditions, and laboratory studies indicate that transgenerational effects are one mechanism behind this plasticity. We studied phenotypic plasticity of the copepod Acartia bifilosa in the course of a pelagic, large-volume mesocosm study that was conducted to investigate ecosystem and biogeochemical responses to ocean acidification. We measured copepod egg production rate, egg hatching success, adult female size and adult female antioxidant capacity (ORAC) as a function of acidification (fCO2 ~ 365-1231 μatm), and as a function of quantity and quality of their diet. We used an egg transplant experiment to reveal if transgenerational effects can alleviate the possible negative effects of ocean acidification on offspring development. We found significant negative effects of ocean acidification on adult female copepod size and egg hatching success. In addition, we found a threshold of fCO2 concentration (~ 1000 μatm), above which adaptive maternal effects cannot alleviate the negative effects of acidification on egg hatching and nauplii development. We did not find support for the hypothesis that insufficient food quantity (total particulate carbon ~ 55 μm) or quality (C : N) weakens the transgenerational effects. However, females with high ORAC produced eggs with high hatching success. Overall, these results indicate that A. bifilosa could be affected by projected near future CO2 levels.

  1. Biochemical adaptation to ocean acidification.

    PubMed

    Stillman, Jonathon H; Paganini, Adam W

    2015-06-01

    The change in oceanic carbonate chemistry due to increased atmospheric PCO2  has caused pH to decline in marine surface waters, a phenomenon known as ocean acidification (OA). The effects of OA on organisms have been shown to be widespread among diverse taxa from a wide range of habitats. The majority of studies of organismal response to OA are in short-term exposures to future levels of PCO2 . From such studies, much information has been gathered on plastic responses organisms may make in the future that are beneficial or harmful to fitness. Relatively few studies have examined whether organisms can adapt to negative-fitness consequences of plastic responses to OA. We outline major approaches that have been used to study the adaptive potential for organisms to OA, which include comparative studies and experimental evolution. Organisms that inhabit a range of pH environments (e.g. pH gradients at volcanic CO2 seeps or in upwelling zones) have great potential for studies that identify adaptive shifts that have occurred through evolution. Comparative studies have advanced our understanding of adaptation to OA by linking whole-organism responses with cellular mechanisms. Such optimization of function provides a link between genetic variation and adaptive evolution in tuning optimal function of rate-limiting cellular processes in different pH conditions. For example, in experimental evolution studies of organisms with short generation times (e.g. phytoplankton), hundreds of generations of growth under future conditions has resulted in fixed differences in gene expression related to acid-base regulation. However, biochemical mechanisms for adaptive responses to OA have yet to be fully characterized, and are likely to be more complex than simply changes in gene expression or protein modification. Finally, we present a hypothesis regarding an unexplored area for biochemical adaptation to ocean acidification. In this hypothesis, proteins and membranes exposed to the

  2. Ocean acidification accelerates reef bioerosion.

    PubMed

    Wisshak, Max; Schönberg, Christine H L; Form, Armin; Freiwald, André

    2012-01-01

    In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO(2)) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process - biologically induced carbonate dissolution via bioerosion - has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO(2) world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia's Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO(2) confirms a significant enforcement of the sponges' bioerosion capacity with increasing pCO(2) under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation.

  3. Ocean Acidification Accelerates Reef Bioerosion

    PubMed Central

    Wisshak, Max; Schönberg, Christine H. L.; Form, Armin; Freiwald, André

    2012-01-01

    In the recent discussion how biotic systems may react to ocean acidification caused by the rapid rise in carbon dioxide partial pressure (pCO2) in the marine realm, substantial research is devoted to calcifiers such as stony corals. The antagonistic process – biologically induced carbonate dissolution via bioerosion – has largely been neglected. Unlike skeletal growth, we expect bioerosion by chemical means to be facilitated in a high-CO2 world. This study focuses on one of the most detrimental bioeroders, the sponge Cliona orientalis, which attacks and kills live corals on Australia’s Great Barrier Reef. Experimental exposure to lowered and elevated levels of pCO2 confirms a significant enforcement of the sponges’ bioerosion capacity with increasing pCO2 under more acidic conditions. Considering the substantial contribution of sponges to carbonate bioerosion, this finding implies that tropical reef ecosystems are facing the combined effects of weakened coral calcification and accelerated bioerosion, resulting in critical pressure on the dynamic balance between biogenic carbonate build-up and degradation. PMID:23028797

  4. Projected climate change impact on oceanic acidification

    PubMed Central

    McNeil, Ben I; Matear, Richard J

    2006-01-01

    Background Anthropogenic CO2 uptake by the ocean decreases the pH of seawater, leading to an 'acidification' which may have potential detrimental consequences on marine organisms [1]. Ocean warming or circulation alterations induced by climate change has the potential to slowdown the rate of acidification of ocean waters by decreasing the amount of CO2 uptake by the ocean [2]. However, a recent study showed that climate change affected the decrease in pH insignificantly [3]. Here, we examine the sensitivity of future oceanic acidification to climate change feedbacks within a coupled atmosphere-ocean model and find that ocean warming dominates the climate change feedbacks. Results Our results show that the direct decrease in pH due to ocean warming is approximately equal to but opposite in magnitude to the indirect increase in pH associated with ocean warming (ie reduced DIC concentration of the upper ocean caused by lower solubility of CO2). Conclusion As climate change feedbacks on pH approximately cancel, future oceanic acidification will closely follow future atmospheric CO2 concentrations. This suggests the only way to slowdown or mitigate the potential biological consequences of future ocean acidification is to significantly reduce fossil-fuel emissions of CO2 to the atmosphere. PMID:16930458

  5. How ocean acidification can benefit calcifiers.

    PubMed

    Connell, Sean D; Doubleday, Zoë A; Hamlyn, Sarah B; Foster, Nicole R; Harley, Christopher D G; Helmuth, Brian; Kelaher, Brendan P; Nagelkerken, Ivan; Sarà, Gianluca; Russell, Bayden D

    2017-02-06

    Reduction in seawater pH due to rising levels of anthropogenic carbon dioxide (CO2) in the world's oceans is a major force set to shape the future of marine ecosystems and the ecological services they provide [1,2]. In particular, ocean acidification is predicted to have a detrimental effect on the physiology of calcifying organisms [3]. Yet, the indirect effects of ocean acidification on calcifying organisms, which may counter or exacerbate direct effects, is uncertain. Using volcanic CO2 vents, we tested the indirect effects of ocean acidification on a calcifying herbivore (gastropod) within the natural complexity of an ecological system. Contrary to predictions, the abundance of this calcifier was greater at vent sites (with near-future CO2 levels). Furthermore, translocation experiments demonstrated that ocean acidification did not drive increases in gastropod abundance directly, but indirectly as a function of increased habitat and food (algal biomass). We conclude that the effect of ocean acidification on algae (primary producers) can have a strong, indirect positive influence on the abundance of some calcifying herbivores, which can overwhelm any direct negative effects. This finding points to the need to understand ecological processes that buffer the negative effects of environmental change.

  6. Significant acidification in major Chinese croplands.

    PubMed

    Guo, J H; Liu, X J; Zhang, Y; Shen, J L; Han, W X; Zhang, W F; Christie, P; Goulding, K W T; Vitousek, P M; Zhang, F S

    2010-02-19

    Soil acidification is a major problem in soils of intensive Chinese agricultural systems. We used two nationwide surveys, paired comparisons in numerous individual sites, and several long-term monitoring-field data sets to evaluate changes in soil acidity. Soil pH declined significantly (P < 0.001) from the 1980s to the 2000s in the major Chinese crop-production areas. Processes related to nitrogen cycling released 20 to 221 kilomoles of hydrogen ion (H+) per hectare per year, and base cations uptake contributed a further 15 to 20 kilomoles of H+ per hectare per year to soil acidification in four widespread cropping systems. In comparison, acid deposition (0.4 to 2.0 kilomoles of H+ per hectare per year) made a small contribution to the acidification of agricultural soils across China.

  7. Impacts of ocean acidification on marine seafood.

    PubMed

    Branch, Trevor A; DeJoseph, Bonnie M; Ray, Liza J; Wagner, Cherie A

    2013-03-01

    Ocean acidification is a series of chemical reactions due to increased CO(2) emissions. The resulting lower pH impairs the senses of reef fishes and reduces their survival, and might similarly impact commercially targeted fishes that produce most of the seafood eaten by humans. Shelled molluscs will also be negatively affected, whereas cephalopods and crustaceans will remain largely unscathed. Habitat changes will reduce seafood production from coral reefs, but increase production from seagrass and seaweed. Overall effects of ocean acidification on primary productivity and, hence, on food webs will result in hard-to-predict winners and losers. Although adaptation, parental effects, and evolution can mitigate some effects of ocean acidification, future seafood platters will look rather different unless CO(2) emissions are curbed.

  8. Extracellular protonation modulates cell-cell interaction mechanics and tissue invasion in human melanoma cells

    PubMed Central

    Hofschröer, Verena; Koch, Kevin Alexander; Ludwig, Florian Timo; Friedl, Peter; Oberleithner, Hans; Stock, Christian; Schwab, Albrecht

    2017-01-01

    Detachment of cells from the primary tumour precedes metastatic progression by facilitating cell release into the tissue. Solid tumours exhibit altered pH homeostasis with extracellular acidification. In human melanoma, the Na+/H+ exchanger NHE1 is an important modifier of the tumour nanoenvironment. Here we tested the modulation of cell-cell-adhesion by extracellular pH and NHE1. MV3 tumour spheroids embedded in a collagen matrix unravelled the efficacy of cell-cell contact loosening and 3D emigration into an environment mimicking physiological confinement. Adhesive interaction strength between individual MV3 cells was quantified using atomic force microscopy and validated by multicellular aggregation assays. Extracellular acidification from pHe7.4 to 6.4 decreases cell migration and invasion but increases single cell detachment from the spheroids. Acidification and NHE1 overexpression both reduce cell-cell adhesion strength, indicated by reduced maximum pulling forces and adhesion energies. Multicellular aggregation and spheroid formation are strongly impaired under acidification or NHE1 overexpression. We show a clear dependence of melanoma cell-cell adhesion on pHe and NHE1 as a modulator. These effects are opposite to cell-matrix interactions that are strengthened by protons extruded via NHE1. We conclude that these opposite effects of NHE1 act synergistically during the metastatic cascade. PMID:28205573

  9. Extracellular protonation modulates cell-cell interaction mechanics and tissue invasion in human melanoma cells.

    PubMed

    Hofschröer, Verena; Koch, Kevin Alexander; Ludwig, Florian Timo; Friedl, Peter; Oberleithner, Hans; Stock, Christian; Schwab, Albrecht

    2017-02-13

    Detachment of cells from the primary tumour precedes metastatic progression by facilitating cell release into the tissue. Solid tumours exhibit altered pH homeostasis with extracellular acidification. In human melanoma, the Na(+)/H(+) exchanger NHE1 is an important modifier of the tumour nanoenvironment. Here we tested the modulation of cell-cell-adhesion by extracellular pH and NHE1. MV3 tumour spheroids embedded in a collagen matrix unravelled the efficacy of cell-cell contact loosening and 3D emigration into an environment mimicking physiological confinement. Adhesive interaction strength between individual MV3 cells was quantified using atomic force microscopy and validated by multicellular aggregation assays. Extracellular acidification from pHe7.4 to 6.4 decreases cell migration and invasion but increases single cell detachment from the spheroids. Acidification and NHE1 overexpression both reduce cell-cell adhesion strength, indicated by reduced maximum pulling forces and adhesion energies. Multicellular aggregation and spheroid formation are strongly impaired under acidification or NHE1 overexpression. We show a clear dependence of melanoma cell-cell adhesion on pHe and NHE1 as a modulator. These effects are opposite to cell-matrix interactions that are strengthened by protons extruded via NHE1. We conclude that these opposite effects of NHE1 act synergistically during the metastatic cascade.

  10. Sampling depth confounds soil acidification outcomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the northern Great Plains (NGP) of North America, surface sampling depths of 0-15 or 0-20 cm are suggested for testing soil characteristics such as pH. However, acidification is often most pronounced near the soil surface. Thus, sampling deeper can potentially dilute (increase) pH measurements an...

  11. Predicting watershed acidification under alternate rainfall conditions

    USGS Publications Warehouse

    Huntington, T.G.

    1996-01-01

    The effect of alternate rainfall scenarios on acidification of a forested watershed subjected to chronic acidic deposition was assessed using the model of acidification of groundwater in catchments (MAGIC). The model was calibrated at the Panola Mountain Research Watershed, near Atlanta, Georgia, U.S.A. using measured soil properties, wet and dry deposition, and modeled hydrologic routing. Model forecast simulations were evaluated to compare alternate temporal averaging of rainfall inputs and variations in rainfall amount and seasonal distribution. Soil water alkalinity was predicted to decrease to substantially lower concentrations under lower rainfall compared with current or higher rainfall conditions. Soil water alkalinity was also predicted to decrease to lower levels when the majority of rainfall occurred during the growing season compared with other rainfall distributions. Changes in rainfall distribution that result in decreases in net soil water flux will temporarily delay acidification. Ultimately, however, decreased soil water flux will result in larger increases in soil- adsorbed sulfur and soil-water sulfate concentrations and decreases in alkalinity when compared to higher water flux conditions. Potential climate change resulting in significant changes in rainfall amounts, seasonal distribution of rainfall, or evapotranspiration will change net soil water flux and, consequently, will affect the dynamics of the acidification response to continued sulfate loading.

  12. Acidification of the lower Mississippi River

    SciTech Connect

    Bryan, C.F.; Rutherford, D.A.; Walker-Bryan, B.

    1992-05-01

    Nonpoint-source pollutants are implicated in the global acidification of fresh waters. Our ability to differentiate the effects of point-source and nonpoint-source pollution on the acidification of large rivers is limited. Most studies of point-source discharges have been concerned with municipal programs for reducing biochemical oxygen demand, bacterial counts, and total phosphorus; few have addressed acidification of rivers. Because of the meager information on the role of nonpoint-source and industrial pollution in the acidification of large rivers, we examined long-term trends (and cyclic seasonal events) in pH, alkalinity, and selected ions in the lower Mississippi River basin from 1958 to 1986. Time-series analyses disclosed significant declines in pH and alkalinity and increases in strong acid anions in the lower 300 km (industrial corridor) of the lower Mississippi River. However, upstream from most industry on the Mississippi River and throughout the Atchafalaya River, where agricultural development has predominated, long-term trends in those characteristics were variable or nonsignificant. 34 refs., 4 figs., 1 tab.

  13. Coral calcification and ocean acidification

    USGS Publications Warehouse

    Jokiel, Paul L.; Jury, Christopher P.; Kuffner, Ilsa B.

    2016-01-01

    Over 60 years ago, the discovery that light increased calcification in the coral plant-animal symbiosis triggered interest in explaining the phenomenon and understanding the mechanisms involved. Major findings along the way include the observation that carbon fixed by photosynthesis in the zooxanthellae is translocated to animal cells throughout the colony and that corals can therefore live as autotrophs in many situations. Recent research has focused on explaining the observed reduction in calcification rate with increasing ocean acidification (OA). Experiments have shown a direct correlation between declining ocean pH, declining aragonite saturation state (Ωarag), declining [CO32_] and coral calcification. Nearly all previous reports on OA identify Ωarag or its surrogate [CO32] as the factor driving coral calcification. However, the alternate “Proton Flux Hypothesis” stated that coral calcification is controlled by diffusion limitation of net H+ transport through the boundary layer in relation to availability of dissolved inorganic carbon (DIC). The “Two Compartment Proton Flux Model” expanded this explanation and synthesized diverse observations into a universal model that explains many paradoxes of coral metabolism, morphology and plasticity of growth form in addition to observed coral skeletal growth response to OA. It is now clear that irradiance is the main driver of net photosynthesis (Pnet), which in turn drives net calcification (Gnet), and alters pH in the bulk water surrounding the coral. Pnet controls [CO32] and thus Ωarag of the bulk water over the diel cycle. Changes in Ωarag and pH lag behind Gnet throughout the daily cycle by two or more hours. The flux rate Pnet, rather than concentration-based parameters (e.g., Ωarag, [CO3 2], pH and [DIC]:[H+] ratio) is the primary driver of Gnet. Daytime coral metabolism rapidly removes DIC from the bulk seawater. Photosynthesis increases the bulk seawater pH while providing the energy that drives

  14. Ocean acidification and global warming impair shark hunting behaviour and growth

    PubMed Central

    Pistevos, Jennifer C. A.; Nagelkerken, Ivan; Rossi, Tullio; Olmos, Maxime; Connell, Sean D.

    2015-01-01

    Alterations in predation pressure can have large effects on trophically-structured systems. Modification of predator behaviour via ocean warming has been assessed by laboratory experimentation and metabolic theory. However, the influence of ocean acidification with ocean warming remains largely unexplored for mesopredators, including experimental assessments that incorporate key components of the assemblages in which animals naturally live. We employ a combination of long-term laboratory and mesocosm experiments containing natural prey and habitat to assess how warming and acidification affect the development, growth, and hunting behaviour in sharks. Although embryonic development was faster due to temperature, elevated temperature and CO2 had detrimental effects on sharks by not only increasing energetic demands, but also by decreasing metabolic efficiency and reducing their ability to locate food through olfaction. The combination of these effects led to considerable reductions in growth rates of sharks held in natural mesocosms with elevated CO2, either alone or in combination with higher temperature. Our results suggest a more complex reality for predators, where ocean acidification reduces their ability to effectively hunt and exert strong top-down control over food webs. PMID:26559327

  15. Ocean acidification and global warming impair shark hunting behaviour and growth.

    PubMed

    Pistevos, Jennifer C A; Nagelkerken, Ivan; Rossi, Tullio; Olmos, Maxime; Connell, Sean D

    2015-11-12

    Alterations in predation pressure can have large effects on trophically-structured systems. Modification of predator behaviour via ocean warming has been assessed by laboratory experimentation and metabolic theory. However, the influence of ocean acidification with ocean warming remains largely unexplored for mesopredators, including experimental assessments that incorporate key components of the assemblages in which animals naturally live. We employ a combination of long-term laboratory and mesocosm experiments containing natural prey and habitat to assess how warming and acidification affect the development, growth, and hunting behaviour in sharks. Although embryonic development was faster due to temperature, elevated temperature and CO2 had detrimental effects on sharks by not only increasing energetic demands, but also by decreasing metabolic efficiency and reducing their ability to locate food through olfaction. The combination of these effects led to considerable reductions in growth rates of sharks held in natural mesocosms with elevated CO2, either alone or in combination with higher temperature. Our results suggest a more complex reality for predators, where ocean acidification reduces their ability to effectively hunt and exert strong top-down control over food webs.

  16. Reflections on the Design of Exertion Games.

    PubMed

    Mueller, Florian Floyd; Altimira, David; Khot, Rohit Ashot

    2015-02-01

    The design of exertion games (i.e., digital games that require physical effort from players) is a difficult intertwined challenge of combining digital games and physical effort. To aid designers in facing this challenge, we describe our experiences of designing exertion games. We outline personal reflections on our design processes and articulate analyses of players' experiences. These reflections and analyses serve to highlight the unique opportunities of combining digital games and physical effort. The insights we seek aim to enhance the understanding of exertion game design, contributing to the advancement of the field, and ultimately resulting in better games and associated player experiences.

  17. Evolutionary change during experimental ocean acidification.

    PubMed

    Pespeni, Melissa H; Sanford, Eric; Gaylord, Brian; Hill, Tessa M; Hosfelt, Jessica D; Jaris, Hannah K; LaVigne, Michèle; Lenz, Elizabeth A; Russell, Ann D; Young, Megan K; Palumbi, Stephen R

    2013-04-23

    Rising atmospheric carbon dioxide (CO2) conditions are driving unprecedented changes in seawater chemistry, resulting in reduced pH and carbonate ion concentrations in the Earth's oceans. This ocean acidification has negative but variable impacts on individual performance in many marine species. However, little is known about the adaptive capacity of species to respond to an acidified ocean, and, as a result, predictions regarding future ecosystem responses remain incomplete. Here we demonstrate that ocean acidification generates striking patterns of genome-wide selection in purple sea urchins (Strongylocentrotus purpuratus) cultured under different CO2 levels. We examined genetic change at 19,493 loci in larvae from seven adult populations cultured under realistic future CO2 levels. Although larval development and morphology showed little response to elevated CO2, we found substantial allelic change in 40 functional classes of proteins involving hundreds of loci. Pronounced genetic changes, including excess amino acid replacements, were detected in all populations and occurred in genes for biomineralization, lipid metabolism, and ion homeostasis--gene classes that build skeletons and interact in pH regulation. Such genetic change represents a neglected and important impact of ocean acidification that may influence populations that show few outward signs of response to acidification. Our results demonstrate the capacity for rapid evolution in the face of ocean acidification and show that standing genetic variation could be a reservoir of resilience to climate change in this coastal upwelling ecosystem. However, effective response to strong natural selection demands large population sizes and may be limited in species impacted by other environmental stressors.

  18. Insufficient Acidification of Autophagosomes Facilitates Group A Streptococcus Survival and Growth in Endothelial Cells

    PubMed Central

    Lu, Shiou-Ling; Kuo, Chih-Feng; Chen, Hao-Wen; Yang, Yi-Shuan; Liu, Ching-Chuan; Anderson, Robert

    2015-01-01

    ABSTRACT Group A streptococcus (GAS) is an important human pathogen, and its invasion via blood vessels is critically important in serious events such as bacteremia or multiorgan failure. Although GAS was identified as an extracellular bacterium, the internalization of GAS into nonphagocytic cells may provide a strategy to escape from immune surveillance and antibiotic killing. However, GAS has also been reported to induce autophagy and is efficiently killed within lysosome-fused autophagosomes in epithelial cells. In this study, we show that GAS can replicate in endothelial cells and that streptolysin O is required for GAS growth. Bacterial replication can be suppressed by altering GAS gene expression in an acidic medium before internalization into endothelial cells. The inhibitory effect on GAS replication can be reversed by treatment with bafilomycin A1, a specific inhibitor of vacuolar-type H+-ATPase. Compared with epithelial cells in which acidification causes autophagy-mediated clearance of GAS, there was a defect in acidification of GAS-containing vesicles in endothelial cells. Consequently, endothelial cells fail to maintain low pH in GAS-containing autophagosomes, thereby permitting GAS replication inside LAMP-1- and LC3-positive vesicles. Furthermore, treatment of epithelial cells with bafilomycin A1 resulted in defective GAS clearance by autophagy, with subsequent bacterial growth intracellularly. Therefore, low pH is a key factor for autophagy-mediated suppression of GAS growth inside epithelial cells, while defective acidification of GAS-containing vesicles results in bacterial growth in endothelial cells. PMID:26419882

  19. Modeling past and future acidification of Swedish lakes.

    PubMed

    Moldan, Filip; Cosby, Bernard J; Wright, Richard F

    2013-09-01

    Decades of acid deposition have caused acidification of lakes in Sweden. Here we use data for 3000 lakes to run the acidification model MAGIC and estimate historical and future acidification. The results indicate that beginning in about 1920 a progressively larger number of lakes in Sweden fell into the category of "not naturally acidified" (∆pH > 0.4). The peak in acidification was reached about 1985; since then many lakes have recovered in response to lower levels of acid deposition. Further recovery from acidification will occur by the year 2030 given implementation of agreed legislation for emissions of sulphur (S) and nitrogen (N) in Europe. But the number of catchments with soils being depleted in base cations will increase slightly. MAGIC-reconstructed history of acidification of lakes in Sweden agrees well with information on fish populations. Future acidification of Swedish lakes can be influenced by climate change as well as changes in forest harvest practices.

  20. Yeast extracellular proteases.

    PubMed

    Ogrydziak, D M

    1993-01-01

    Many species of yeast secrete significant amounts of protease(s). In this article, results of numerous surveys of yeast extracellular protease production have been compiled and inconsistencies in the data and limitations of the methodology have been examined. Regulation, purification, characterization, and processing of yeast extracellular proteases are reviewed. Results obtained from the sequences of cloned genes, especially the Saccharomyces cerevisiae Bar protease, the Candida albicans acid protease, and the Yarrowia lipolytica alkaline protease, have been emphasized. Biotechnological applications and the medical relevance of yeast extracellular proteases are covered. Yeast extracellular proteases have potential in beer and wine stabilization, and they probably contribute to pathogenicity of Candida spp. Yeast extracellular protease genes also provide secretion and processing signals for yeast expression systems designed for secretion of heterologous proteins. Coverage of the secretion of foreign proteases such as prochymosin, urokinase, and tissue plasminogen activator by yeast in included.

  1. Euechinoidea and Cidaroidea respond differently to ocean acidification.

    PubMed

    Collard, Marie; Dery, Aurélie; Dehairs, Frank; Dubois, Philippe

    2014-08-01

    The impact of the chemical changes in the ocean waters due to the increasing atmospheric CO₂ depends on the ability of an organism to control extracellular pH. Among sea urchins, this seems specific to the Euechinoidea, sea urchins except Cidaroidea. However, Cidaroidea survived two ocean acidification periods: the Permian-Trias and the Cretaceous-Tertiary crises. We investigated the response of these two sea urchin groups to reduced seawater pH with the tropical cidaroid Eucidaris tribuloides, the sympatric euechinoid Tripneustes ventricosus and the temperate euechinoid Paracentrotus lividus. Both euechinoid showed a compensation of the coelomic fluid pH due to increased buffer capacity. This was linked to an increased concentration of DIC in the coelomic fluid and thus of bicarbonate ions (most probably originating from the surrounding seawater as isotopic signature of the carbon - δ¹³C - was similar). On the other hand, the cidaroid showed no changes within the coelomic fluid. Moreover, the δ¹³C of the coelomic fluid did not match that of the seawater and was not significantly different between the urchins from the different treatments. Feeding rate was not affected in any species. While euechinoids are able to regulate their extracellular acid-base balance, many questions are still unanswered on the costs of this capacity. On the contrary, cidaroids do not seem affected by a reduced seawater pH. Further investigations need to be undertaken to cover more species and physiological and metabolic parameters in order to determine if energy trade-offs occur and how this mechanism of compensation is distributed among sea urchins.

  2. Neutrophil extracellular traps in cancer progression.

    PubMed

    Cools-Lartigue, Jonathan; Spicer, Jonathan; Najmeh, Sara; Ferri, Lorenzo

    2014-11-01

    Neutrophils are being increasingly recognized as an important element in tumor progression. They have been shown to exert important effects at nearly every stage of tumor progression with a number of studies demonstrating that their presence is critical to tumor development. Novel aspects of neutrophil biology have recently been elucidated and its contribution to tumorigenesis is only beginning to be appreciated. Neutrophil extracellular traps (NETs) are neutrophil-derived structures composed of DNA decorated with antimicrobial peptides. They have been shown to trap and kill microorganisms, playing a critical role in host defense. However, their contribution to tumor development and metastasis has recently been demonstrated in a number of studies highlighting NETs as a potentially important therapeutic target. Here, studies implicating NETs as facilitators of tumor progression and metastasis are reviewed. In addition, potential mechanisms by which NETs may exert these effects are explored. Finally, the ability to target NETs therapeutically in human neoplastic disease is highlighted.

  3. Temperature increase prevails over acidification in gene expression modulation of amastigote differentiation in Leishmania infantum

    PubMed Central

    2010-01-01

    Background The extracellular promastigote and the intracellular amastigote stages alternate in the digenetic life cycle of the trypanosomatid parasite Leishmania. Amastigotes develop inside parasitophorous vacuoles of mammalian phagocytes, where they tolerate extreme environmental conditions. Temperature increase and pH decrease are crucial factors in the multifactorial differentiation process of promastigotes to amastigotes. Although expression profiling approaches for axenic, cell culture- and lesion-derived amastigotes have already been reported, the specific influence of temperature increase and acidification of the environment on developmental regulation of genes has not been previously studied. For the first time, we have used custom L. infantum genomic DNA microarrays to compare the isolated and the combined effects of both factors on the transcriptome. Results Immunofluorescence analysis of promastigote-specific glycoprotein gp46 and expression modulation analysis of the amastigote-specific A2 gene have revealed that concomitant exposure to temperature increase and acidification leads to amastigote-like forms. The temperature-induced gene expression profile in the absence of pH variation resembles the profile obtained under combined exposure to both factors unlike that obtained for exposure to acidification alone. In fact, the subsequent fold change-based global iterative hierarchical clustering analysis supports these findings. Conclusions The specific influence of temperature and pH on the differential regulation of genes described in this study and the evidence provided by clustering analysis is consistent with the predominant role of temperature increase over extracellular pH decrease in the amastigote differentiation process, which provides new insights into Leishmania physiology. PMID:20074347

  4. Optogenetic approaches addressing extracellular modulation of neural excitability

    PubMed Central

    Ferenczi, Emily A.; Vierock, Johannes; Atsuta-Tsunoda, Kyoko; Tsunoda, Satoshi P.; Ramakrishnan, Charu; Gorini, Christopher; Thompson, Kimberly; Lee, Soo Yeun; Berndt, Andre; Perry, Chelsey; Minniberger, Sonja; Vogt, Arend; Mattis, Joanna; Prakash, Rohit; Delp, Scott; Deisseroth, Karl; Hegemann, Peter

    2016-01-01

    The extracellular ionic environment in neural tissue has the capacity to influence, and be influenced by, natural bouts of neural activity. We employed optogenetic approaches to control and investigate these interactions within and between cells, and across spatial scales. We began by developing a temporally precise means to study microdomain-scale interactions between extracellular protons and acid-sensing ion channels (ASICs). By coupling single-component proton-transporting optogenetic tools to ASICs to create two-component optogenetic constructs (TCOs), we found that acidification of the local extracellular membrane surface by a light-activated proton pump recruited a slow inward ASIC current, which required molecular proximity of the two components on the membrane. To elicit more global effects of activity modulation on ‘bystander’ neurons not under direct control, we used densely-expressed depolarizing (ChR2) or hyperpolarizing (eArch3.0, eNpHR3.0) tools to create a slow non-synaptic membrane current in bystander neurons, which matched the current direction seen in the directly modulated neurons. Extracellular protons played contributory role but were insufficient to explain the entire bystander effect, suggesting the recruitment of other mechanisms. Together, these findings present a new approach to the engineering of multicomponent optogenetic tools to manipulate ionic microdomains, and probe the complex neuronal-extracellular space interactions that regulate neural excitability. PMID:27045897

  5. Ocean acidification: setting the record straight

    NASA Astrophysics Data System (ADS)

    Andersson, A. J.; MacKenzie, F. T.

    2011-06-01

    In recent years, ocean acidification has gained continuously increasing attention from scientists and a number of stakeholders and has raised serious concerns about its effects on marine organisms and ecosystems. With the increase in interest and the number of scientific investigations of this environmental problem, the number of opinions, often emotional, and misinterpretations of the issue have also increased. Regrettably, this is not necessarily helping to advance scientific understanding of the problem. In this article, we revisit a number of issues relevant to ocean acidification that we think require thoughtful consideration including: (1) surface seawater CO2 chemistry in shallow water coastal areas, (2) experimental manipulation of marine systems using CO2 gas or by acid addition, (3) net versus gross calcification and dissolution, and (4) CaCO3 mineral dissolution and seawater buffering.

  6. Lake acidification: Effects on crustacean zooplankton populations

    SciTech Connect

    Havens, K.E. ); Yan, N.D. ); Keller, W. )

    1993-08-01

    The ranked acid sensitivities of six common crustacean zooplankton taxa were determined from a multilake field survey in Ontario and from laboratory bioassays. The two approaches gave the same ranking (from most to least sensitive): Daphnia galeata mendotae, Daphnia retrocurva, and Skistodiaptomus oregonensis > Diaphanosoma birgei > Mesocyclops edax > Bosmina longirostris. This finding suggests that acidification has caused the widespread damage which has been documented for the zooplankton of Ontario and northeastern US lakes. 24 refs., 3 figs., 2 tabs.

  7. Mussel byssus attachment weakened by ocean acidification

    NASA Astrophysics Data System (ADS)

    O'Donnell, Michael J.; George, Matthew N.; Carrington, Emily

    2013-06-01

    Biomaterials connect organisms to their environments. Their function depends on biological, chemical and environmental factors, both at the time of creation and throughout the life of the material. Shifts in the chemistry of the oceans driven by anthropogenic CO2 (termed ocean acidification) have profound implications for the function of critical materials formed under these altered conditions. Most ocean acidification studies have focused on one biomaterial (secreted calcium carbonate), frequently using a single assay (net rate of calcification) to quantify whether reductions in environmental pH alter how organisms create biomaterials. Here, we examine biological structures critical for the success of ecologically and economically important bivalve molluscs. One non-calcified material, the proteinaceous byssal threads that anchor mytilid mussels to hard substrates, exhibited reduced mechanical performance when secreted under elevated pCO2 conditions, whereas shell and tissue growth were unaffected. Threads made under high pCO2 (>1,200μatm) were weaker and less extensible owing to compromised attachment to the substratum. According to a mathematical model, this reduced byssal fibre performance, decreasing individual tenacity by 40%. In the face of ocean acidification, weakened attachment presents a potential challenge for suspension-culture mussel farms and for intertidal communities anchored by mussel beds.

  8. Ocean acidification in a geoengineering context.

    PubMed

    Williamson, Phillip; Turley, Carol

    2012-09-13

    Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO(2)) in the atmosphere. Ocean acidity (H(+) concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO(2); they will, therefore, depend on the success of emission reduction, and could also be constrained by geoengineering based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO(2), although with additional temperature-related effects on CO(2) and CaCO(3) solubility and terrestrial carbon sequestration.

  9. Symbiosis increases coral tolerance to ocean acidification

    NASA Astrophysics Data System (ADS)

    Ohki, S.; Irie, T.; Inoue, M.; Shinmen, K.; Kawahata, H.; Nakamura, T.; Kato, A.; Nojiri, Y.; Suzuki, A.; Sakai, K.; van Woesik, R.

    2013-04-01

    Increasing the acidity of ocean waters will directly threaten calcifying marine organisms such as reef-building scleractinian corals, and the myriad of species that rely on corals for protection and sustenance. Ocean pH has already decreased by around 0.1 pH units since the beginning of the industrial revolution, and is expected to decrease by another 0.2-0.4 pH units by 2100. This study mimicked the pre-industrial, present, and near-future levels of pCO2 using a precise control system (±5% pCO2), to assess the impact of ocean acidification on the calcification of recently-settled primary polyps of Acropora digitifera, both with and without symbionts, and adult fragments with symbionts. The increase in pCO2 of 100 μatm between the pre-industrial period and the present had more effect on the calcification rate of adult A. digitifera than the anticipated future increases of several hundreds of micro-atmospheres of pCO2. The primary polyps with symbionts showed higher calcification rates than primary polyps without symbionts, suggesting that (i) primary polyps housing symbionts are more tolerant to near-future ocean acidification than organisms without symbionts, and (ii) corals acquiring symbionts from the environment (i.e. broadcasting species) will be more vulnerable to ocean acidification than corals that maternally acquire symbionts.

  10. Ocean acidification in a geoengineering context

    PubMed Central

    Williamson, Phillip; Turley, Carol

    2012-01-01

    Fundamental changes to marine chemistry are occurring because of increasing carbon dioxide (CO2) in the atmosphere. Ocean acidity (H+ concentration) and bicarbonate ion concentrations are increasing, whereas carbonate ion concentrations are decreasing. There has already been an average pH decrease of 0.1 in the upper ocean, and continued unconstrained carbon emissions would further reduce average upper ocean pH by approximately 0.3 by 2100. Laboratory experiments, observations and projections indicate that such ocean acidification may have ecological and biogeochemical impacts that last for many thousands of years. The future magnitude of such effects will be very closely linked to atmospheric CO2; they will, therefore, depend on the success of emission reduction, and could also be constrained by geoengineering based on most carbon dioxide removal (CDR) techniques. However, some ocean-based CDR approaches would (if deployed on a climatically significant scale) re-locate acidification from the upper ocean to the seafloor or elsewhere in the ocean interior. If solar radiation management were to be the main policy response to counteract global warming, ocean acidification would continue to be driven by increases in atmospheric CO2, although with additional temperature-related effects on CO2 and CaCO3 solubility and terrestrial carbon sequestration. PMID:22869801

  11. Apoptosis in an interleukin-2-dependent cytotoxic T lymphocyte cell line is associated with intracellular acidification. Role of the Na(+)/H(+)-antiport.

    PubMed

    Li, J; Eastman, A

    1995-02-17

    Apoptosis is a form of cell death associated with DNA fragmentation and chromatin condensation. We recently established that intracellular acidification occurred during apoptosis following cytotoxic insult. The current studies were designed to determine whether intracellular acidification was more generally associated with apoptosis, specifically in a model of growth factor withdrawal. Upon withdrawal of interleukin-2, CTLL-2 cells accumulated in the G1 phase of the cell cycle and started to fragment their DNA around 12 h concurrent with both decreased pH and increased Ca2. Chelation of Ca2+ did not inhibit DNA digestion, whereas incubation with a calcium ionophore prevented both acidification and DNA digestion. Hence, acidification rather than increased Ca2+ was associated with apoptosis. The acidified cells represented a discrete population up to 0.7 pH units below normal. The extent of acidification depended upon the extracellular pH; above pH 6.3, intracellular pH was significantly below extracellular pH, whereas below pH 6.3, the cells still regulated their pH. Inhibition of the Na+/H(+)-antiport prevented the apoptotic cells from regulating their intracellular pH under these acidic conditions. These intracellular pH under these acidic conditions. These results demonstrate that apoptotic cells retain a functional antiport but that its set-point has changed. Many survival factors are known to phosphorylate and activate the antiport, hence apoptosis is likely to be associated with dephosphorylation. Although acidification always occurred during apoptosis, maintaining intracellular pH above 7.2 did not prevent apoptosis, suggesting that an acid pH is not essential for apoptosis. We hypothesize that other critical regulators of apoptosis must be subject to dephosphorylation.

  12. Investigating Undergraduate Science Students' Conceptions and Misconceptions of Ocean Acidification.

    PubMed

    Danielson, Kathryn I; Tanner, Kimberly D

    2015-01-01

    Scientific research exploring ocean acidification has grown significantly in past decades. However, little science education research has investigated the extent to which undergraduate science students understand this topic. Of all undergraduate students, one might predict science students to be best able to understand ocean acidification. What conceptions and misconceptions of ocean acidification do these students hold? How does their awareness and knowledge compare across disciplines? Undergraduate biology, chemistry/biochemistry, and environmental studies students, and science faculty for comparison, were assessed on their awareness and understanding. Results revealed low awareness and understanding of ocean acidification among students compared with faculty. Compared with biology or chemistry/biochemistry students, more environmental studies students demonstrated awareness of ocean acidification and identified the key role of carbon dioxide. Novel misconceptions were also identified. These findings raise the question of whether undergraduate science students are prepared to navigate socioenvironmental issues such as ocean acidification.

  13. Investigating Undergraduate Science Students’ Conceptions and Misconceptions of Ocean Acidification

    PubMed Central

    Danielson, Kathryn I.; Tanner, Kimberly D.

    2015-01-01

    Scientific research exploring ocean acidification has grown significantly in past decades. However, little science education research has investigated the extent to which undergraduate science students understand this topic. Of all undergraduate students, one might predict science students to be best able to understand ocean acidification. What conceptions and misconceptions of ocean acidification do these students hold? How does their awareness and knowledge compare across disciplines? Undergraduate biology, chemistry/biochemistry, and environmental studies students, and science faculty for comparison, were assessed on their awareness and understanding. Results revealed low awareness and understanding of ocean acidification among students compared with faculty. Compared with biology or chemistry/biochemistry students, more environmental studies students demonstrated awareness of ocean acidification and identified the key role of carbon dioxide. Novel misconceptions were also identified. These findings raise the question of whether undergraduate science students are prepared to navigate socioenvironmental issues such as ocean acidification. PMID:26163563

  14. Extracellular calcium sensing and extracellular calcium signaling

    NASA Technical Reports Server (NTRS)

    Brown, E. M.; MacLeod, R. J.; O'Malley, B. W. (Principal Investigator)

    2001-01-01

    The cloning of a G protein-coupled extracellular Ca(2+) (Ca(o)(2+))-sensing receptor (CaR) has elucidated the molecular basis for many of the previously recognized effects of Ca(o)(2+) on tissues that maintain systemic Ca(o)(2+) homeostasis, especially parathyroid chief cells and several cells in the kidney. The availability of the cloned CaR enabled the development of DNA and antibody probes for identifying the CaR's mRNA and protein, respectively, within these and other tissues. It also permitted the identification of human diseases resulting from inactivating or activating mutations of the CaR gene and the subsequent generation of mice with targeted disruption of the CaR gene. The characteristic alterations in parathyroid and renal function in these patients and in the mice with "knockout" of the CaR gene have provided valuable information on the CaR's physiological roles in these tissues participating in mineral ion homeostasis. Nevertheless, relatively little is known about how the CaR regulates other tissues involved in systemic Ca(o)(2+) homeostasis, particularly bone and intestine. Moreover, there is evidence that additional Ca(o)(2+) sensors may exist in bone cells that mediate some or even all of the known effects of Ca(o)(2+) on these cells. Even more remains to be learned about the CaR's function in the rapidly growing list of cells that express it but are uninvolved in systemic Ca(o)(2+) metabolism. Available data suggest that the receptor serves numerous roles outside of systemic mineral ion homeostasis, ranging from the regulation of hormonal secretion and the activities of various ion channels to the longer term control of gene expression, programmed cell death (apoptosis), and cellular proliferation. In some cases, the CaR on these "nonhomeostatic" cells responds to local changes in Ca(o)(2+) taking place within compartments of the extracellular fluid (ECF) that communicate with the outside environment (e.g., the gastrointestinal tract). In others

  15. Biogenic acidification reduces sea urchin gonad growth and increases susceptibility of aquaculture to ocean acidification.

    PubMed

    Mos, Benjamin; Byrne, Maria; Dworjanyn, Symon A

    2016-02-01

    Decreasing oceanic pH (ocean acidification) has emphasised the influence of carbonate chemistry on growth of calcifying marine organisms. However, calcifiers can also change carbonate chemistry of surrounding seawater through respiration and calcification, a potential limitation for aquaculture. This study examined how seawater exchange rate and stocking density of the sea urchin Tripneustes gratilla that were reproductively mature affected carbonate system parameters of their culture water, which in turn influenced growth, gonad production and gonad condition. Growth, relative spine length, gonad production and consumption rates were reduced by up to 67% by increased density (9-43 individuals.m(-2)) and reduced exchange rates (3.0-0.3 exchanges.hr(-1)), but survival and food conversion efficiency were unaffected. Analysis of the influence of seawater parameters indicated that reduced pH and calcite saturation state (ΩCa) were the primary factors limiting gonad production and growth. Uptake of bicarbonate and release of respiratory CO2 by T. gratilla changed the carbonate chemistry of surrounding water. Importantly total alkalinity (AT) was reduced, likely due to calcification by the urchins. Low AT limits the capacity of culture water to buffer against acidification. Direct management to counter biogenic acidification will be required to maintain productivity and reproductive output of marine calcifiers, especially as the ocean carbonate system is altered by climate driven ocean acidification.

  16. Adaptive acidification tolerance response of Salmonella typhimurium.

    PubMed

    Foster, J W; Hall, H K

    1990-02-01

    Salmonella typhimurium can encounter a wide variety of environments during its life cycle. One component of the environment which will fluctuate widely is pH. In nature, S. typhimurium can experience and survive dramatic acid stresses that occur in diverse ecological niches ranging from pond water to phagolysosomes. However, in vitro the organism is very sensitive to acid. To provide an explanation for how this organism survives acid in natural environments, the adaptive ability of S. typhimurium to become acid tolerant was tested. Logarithmically grown cells (pH 7.6) shifted to mild acid (pH 5.8) for one doubling as an adaptive procedure were 100 to 1,000 times more resistant to subsequent strong acid challenge (pH 3.3) than were unadapted cells shifted directly from pH 7.6 to 3.3. This acidification tolerance response required protein synthesis and appears to be a specific defense mechanism for acid. No cross protection was noted for hydrogen peroxide, SOS, or heat shock. Two-dimensional polyacrylamide gel electrophoretic analysis of acid-regulated polypeptides revealed 18 proteins with altered expression, 6 of which were repressed while 12 were induced by mild acid shifts. An avirulent phoP mutant was 1,000-fold more sensitive to acid than its virulent phoP+ parent, suggesting a correlation between acid tolerance and virulence. The Mg2(+)-dependent proton-translocating ATPase was also found to play an important role in acid tolerance. Mutants (unc) lacking this activity were unable to mount an acid tolerance response and were extremely acid sensitive. In contrast to these acid-sensitive mutants, a constitutively acid-tolerant mutant (atr) was isolated from wild-type LT2 after prolonged acid exposure. This mutant overexpressed several acidification tolerance response polypeptides. The data presented reveal an important acidification defense modulon with broad significance toward survival in biologically hostile environments.

  17. Investigating Undergraduate Science Students' Conceptions and Misconceptions of Ocean Acidification

    ERIC Educational Resources Information Center

    Danielson, Kathryn I.; Tanner, Kimberly D.

    2015-01-01

    Scientific research exploring ocean acidification has grown significantly in past decades. However, little science education research has investigated the extent to which undergraduate science students understand this topic. Of all undergraduate students, one might predict science students to be best able to understand ocean acidification. What…

  18. An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress.

    PubMed

    Gao, Guang; Liu, Yameng; Li, Xinshu; Feng, Zhihua; Xu, Juntian

    2016-01-01

    Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli's acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity. The inhibitors experiment for photosynthetic inorganic carbon utilization demonstrated that acidic compartments, extracellular carbonic anhydrase (CA) and intracellular CA worked together in the thalli grown at LC and the acquisition of exogenous carbon source in the thalli could be attributed to the collaboration of acidic compartments and extracellular CA. Contrastingly, when U. linza was grown at HC, extracellular CA was completely inhibited, acidic compartments and intracellular CA were also down-regulated to different extents and thus the acquisition of exogenous carbon source solely relied on acidic compartments. The down-regulated CCMs in U. linza did not affect its responses to changes of seawater carbon chemistry but led to a decrease of net photosynthetic rate when thalli were exposed to increased light intensity. This decrease could be attributed to photodamage caused by the combination of the saved energy due to the down-regulated CCMs and high light intensity. Our findings suggest future ocean acidification might impose depressing effects on green tide events when combined with increased light exposure.

  19. An Ocean Acidification Acclimatised Green Tide Alga Is Robust to Changes of Seawater Carbon Chemistry but Vulnerable to Light Stress

    PubMed Central

    Li, Xinshu; Feng, Zhihua; Xu, Juntian

    2016-01-01

    Ulva is the dominant genus in the green tide events and is considered to have efficient CO2 concentrating mechanisms (CCMs). However, little is understood regarding the impacts of ocean acidification on the CCMs of Ulva and the consequences of thalli’s acclimation to ocean acidification in terms of responding to environmental factors. Here, we grew a cosmopolitan green alga, Ulva linza at ambient (LC) and elevated (HC) CO2 levels and investigated the alteration of CCMs in U. linza grown at HC and its responses to the changed seawater carbon chemistry and light intensity. The inhibitors experiment for photosynthetic inorganic carbon utilization demonstrated that acidic compartments, extracellular carbonic anhydrase (CA) and intracellular CA worked together in the thalli grown at LC and the acquisition of exogenous carbon source in the thalli could be attributed to the collaboration of acidic compartments and extracellular CA. Contrastingly, when U. linza was grown at HC, extracellular CA was completely inhibited, acidic compartments and intracellular CA were also down-regulated to different extents and thus the acquisition of exogenous carbon source solely relied on acidic compartments. The down-regulated CCMs in U. linza did not affect its responses to changes of seawater carbon chemistry but led to a decrease of net photosynthetic rate when thalli were exposed to increased light intensity. This decrease could be attributed to photodamage caused by the combination of the saved energy due to the down-regulated CCMs and high light intensity. Our findings suggest future ocean acidification might impose depressing effects on green tide events when combined with increased light exposure. PMID:28033367

  20. Commercial Cow Milk Contains Physically Stable Extracellular Vesicles Expressing Immunoregulatory TGF-β

    PubMed Central

    Bennink, Miranda B.; Broeren, Mathijs G. A.; van Caam, Arjan P. M.; Koenders, Marije I.; van Lent, Peter L. E. M.; van den Berg, Wim B.; de Vries, Marieke; van der Kraan, Peter M.; van de Loo, Fons A. J.

    2015-01-01

    Scope Extracellular vesicles, including exosomes, have been identified in all biological fluids and rediscovered as an important part of the intercellular communication. Breast milk also contains extracellular vesicles and the proposed biological function is to enhance the antimicrobial defense in newborns. It is, however, unknown whether extracellular vesicles are still present in commercial milk and, more importantly, whether they retained their bioactivity. Here, we characterize the extracellular vesicles present in semi-skimmed cow milk available for consumers and study their effect on T cells. Methods and Results Extracellular vesicles from commercial milk were isolated and characterized. Milk-derived extracellular vesicles contained several immunomodulating miRNAs and membrane protein CD63, characteristics of exosomes. In contrast to RAW 267.4 derived extracellular vesicles the milk-derived extracellular vesicles were extremely stable under degrading conditions, including low pH, boiling and freezing. Milk-derived extracellular vesicles were easily taken up by murine macrophages in vitro. Furthermore, we found that they can facilitate T cell differentiation towards the pathogenic Th17 lineage. Using a (CAGA)12-luc reporter assay we showed that these extracellular vesicles carried bioactive TGF-β, and that anti-TGF-β antibodies blocked Th17 differentiation. Conclusion Our findings show that commercial milk contains stable extracellular vesicles, including exosomes, and carry immunoregulatory cargo. These data suggest that the extracellular vesicles present in commercial cow milk remains intact in the gastrointestinal tract and exert an immunoregulatory effect. PMID:25822997

  1. Bacterial extracellular lignin peroxidase

    DOEpatents

    Crawford, Donald L.; Ramachandra, Muralidhara

    1993-01-01

    A newly discovered lignin peroxidase enzyme is provided. The enzyme is obtained from a bacterial source and is capable of degrading the lignin portion of lignocellulose in the presence of hydrogen peroxide. The enzyme is extracellular, oxidative, inducible by lignin, larch wood xylan, or related substrates and capable of attacking certain lignin substructure chemical bonds that are not degradable by fungal lignin peroxidases.

  2. The force exerted by a fireball

    SciTech Connect

    Makrinich, G.; Fruchtman, A.

    2014-02-15

    The force exerted by a fireball was deduced both from the change of the equilibrium position of a pendulum and from the change in the pendulum oscillation period. That measured force was found to be several times larger than the force exerted by the ions accelerated across the double layer that is assumed to surround the fireball. The force enhancement that is expected by ion-neutral collisions in the fireball is evaluated to be too small to explain the measured enhanced force. Gas pressure increase, due to gas heating through electron-neutral collisions, as recently suggested [Stenzel et al., J. Appl. Phys. 109, 113305 (2011)], is examined as the source for the force enhancement.

  3. Exertional leg pain: teasing out arterial entrapments.

    PubMed

    Pham, Thomas T; Kapur, Rahul; Harwood, Marc I

    2007-12-01

    Vascular causes of exertional lower extremity pain are relatively rare, but may be the answer in athletes refractory to treatment for the more common overuse syndromes of the lower extremities. It is important to differentiate these vascular causes from chronic exertional compartment syndrome (CECS), medial tibial stress syndrome (MTSS), and stress fractures in order to develop appropriate treatment plans, avoid complications, and return athletes to play expeditiously. Important vascular etiologies to be considered are popliteal artery entrapment syndrome (PAES), endofibrotic disease, popliteal artery aneurysm, cystic adventitial disease, and peripheral arterial dissections. The diagnostic workup involves angiography or noninvasive vascular studies such as Doppler ultrasound or magnetic resonance angiography in both the neutral and provocative positions. Treatment of these vascular abnormalities typically involves surgical correction of the vascular anomaly.

  4. Vulnerability and adaptation of US shellfisheries to ocean acidification

    NASA Astrophysics Data System (ADS)

    Ekstrom, Julia A.; Suatoni, Lisa; Cooley, Sarah R.; Pendleton, Linwood H.; Waldbusser, George G.; Cinner, Josh E.; Ritter, Jessica; Langdon, Chris; van Hooidonk, Ruben; Gledhill, Dwight; Wellman, Katharine; Beck, Michael W.; Brander, Luke M.; Rittschof, Dan; Doherty, Carolyn; Edwards, Peter E. T.; Portela, Rosimeiry

    2015-03-01

    Ocean acidification is a global, long-term problem whose ultimate solution requires carbon dioxide reduction at a scope and scale that will take decades to accomplish successfully. Until that is achieved, feasible and locally relevant adaptation and mitigation measures are needed. To help to prioritize societal responses to ocean acidification, we present a spatially explicit, multidisciplinary vulnerability analysis of coastal human communities in the United States. We focus our analysis on shelled mollusc harvests, which are likely to be harmed by ocean acidification. Our results highlight US regions most vulnerable to ocean acidification (and why), important knowledge and information gaps, and opportunities to adapt through local actions. The research illustrates the benefits of integrating natural and social sciences to identify actions and other opportunities while policy, stakeholders and scientists are still in relatively early stages of developing research plans and responses to ocean acidification.

  5. Tracing acidification induced by Deccan volcanism

    NASA Astrophysics Data System (ADS)

    Font, Eric; Adatte, Thierry; Fantasia, Alicia; Ponte, Jorge; Florindo, Fabio; Abrajevitch, Alexandra; Samant, Bandana; Mohabey, Dhananjay; Thakre, Deepali

    2015-04-01

    The Deccan Volcanic Province (DVP) is constituted by three major phases of eruptions, for which the most voluminous - the Deccan Phase-2 - encompassed the Cretaceous-Paleogene (KT) boundary and has been pointed as the main contributor of the KT mass extinction. However, the mechanisms (including acidification) by which the massive Deccan Phase eruptions contributed to the end-Cretaceous global changes and to the controversial KT mass extinction are still poorly constrained. Here we identify the regional climate and environmental effects of the Deccan eruptions by studying the magnetic and mineral assemblages preserved in the lacustrine and continental intertrappeans sediments from the western Maharashtra Deccan Volcanic Provinces (DVP). To achieve this objective, we applied rock magnetic techniques coupled to scanning electron microscopy and diffuse reflectance spectrophotometry to samples collected in three different stratigraphic sections. Our results show that the main magnetic carriers of the Deccan lacustrine and continental sediments are represented by allogenic (detrital) magnetite and hematite inherited from the weathering of the surrounding underlying basaltic bedrocks. Iron sulphides (pyrrhotite or greigite) are accessorily observed. Interestingly, the Podgawan deposits show peculiar and very distinct magnetic and mineralogical signatures, including iron oxide reductive dissolution and widespread crystallisation of iron vanadates, that we interpreted as the effect of Deccan induced acidification. Keywords: Deccan Volcanic Province, intertrappean continental sediments, environmental magnetism Funded by FCT (PTDC/CTE-GIX/117298/2010)

  6. Acidification of animal slurry--a review.

    PubMed

    Fangueiro, David; Hjorth, Maibritt; Gioelli, Fabrizio

    2015-02-01

    Ammonia emissions are a major problem associated with animal slurry management, and solutions to overcome this problem are required worldwide by farmers and stakeholders. An obvious way to minimize ammonia emissions from slurry is to decrease slurry pH by addition of acids or other substances. This solution has been used commonly since 2010 in countries such as Denmark, and its efficiency with regard to the minimization of NH3 emissions has been documented in many studies. Nevertheless, the impact of such treatment on other gaseous emissions during storage is not clear, since the studies performed so far have provided different scenarios. Similarly, the impact of the soil application of acidified slurry on plant production and diffuse pollution has been considered in several studies. Also, the impact of acidification upon combination with other slurry treatment technologies (e.g. mechanical separation, anaerobic digestion …) is important to consider. Here, a compilation and critical review of all these studies has been performed in order to fully understand the global impact of slurry acidification and assess the applicability of this treatment for slurry management.

  7. Autophagy extends lifespan via vacuolar acidification

    PubMed Central

    Ruckenstuhl, Christoph; Netzberger, Christine; Entfellner, Iryna; Carmona-Gutierrez, Didac; Kickenweiz, Thomas; Stekovic, Slaven; Gleixner, Christina; Schmid, Christian; Klug, Lisa; Hajnal, Ivan; Sorgo, Alice G.; Eisenberg, Tobias; Büttner, Sabrina; Marin͂o, Guillermo; Koziel, Rafael; Magnes, Christoph; Sinner, Frank; Pieber, Thomas R.; Jansen-Dürr, Pidder; Fröhlich, Kai-Uwe; Kroemer, Guido; Madeo, Frank

    2014-01-01

    Methionine restriction (MetR) is one of the rare regimes that prolongs lifespan across species barriers. Using a yeast model, we recently demonstrated that this lifespan extension is promoted by autophagy, which in turn requires vacuolar acidification. Our study is the first to place autophagy as one of the major players required for MetR-mediated longevity. In addition, our work identifies vacuolar acidification as a key downstream element of autophagy induction under MetR, and possibly after rapamycin treatment. Unlike other amino acids, methionine plays pleiotropic roles in many metabolism-relevant pathways. For instance, methionine (i) is the N-terminal amino acid of every newly translated protein; (ii) acts as the central donor of methyl groups through S-adenosyl methionine (SAM) during methylation reactions of proteins, DNA or RNA; and (iii) provides the sulfhydryl groups for FeS-cluster formation and redox detoxification via transsulfuration to cysteine. Intriguingly, MetR causes lifespan extension, both in yeast and in rodents. We could show that in Saccharomyces cerevisiae, chronological lifespan (CLS) is increased in two specific methionine-auxotrophic strains (namely Δmet2 and Δmet15).

  8. Modulation of Human Cardiac TRPM7 Current by Extracellular Acidic pH Depends upon Extracellular Concentrations of Divalent Cations

    PubMed Central

    Mačianskienė, Regina; Almanaitytė, Mantė; Jekabsone, Aistė; Mubagwa, Kanigula

    2017-01-01

    TRPM7 channels participate in a variety of physiological/pathological processes. TRPM7 currents are modulated by protons but opposing effects of external pH (pHo) (potentiation vs inhibition) have been reported. TRPM7 has been less studied in human cardiomyocytes than in heart-derived non-cardiomyocyte cells. We used the whole-cell patch-clamp technique on isolated human atrial cardiomyocytes to investigate the impact of an acidic pHo on the TRPM7 current. With voltage-dependent and other ion channels inhibited, cardiomyocytes were challenged with external acidification in either the presence or the absence of extracellular divalent cations. TRPM7 outward and inward currents were increased by acidic pHo in extracellular medium containing Ca2+ and Mg2+, but suppressed by acidic pHo in the absence of extracellular Ca2+ and Mg2+. The potentiating effect in the presence of extracellular divalents occurred at pHo below 6 and was voltage-dependent. The inhibitory effect in the absence of extracellular divalents was already marked at pHo of 6 and was practically voltage-independent. TRPM7 current density was higher in cardiomyocytes from patients with history of coronary vascular disease and the difference compared to cardiomyocytes from patients without history of myocardial ischemia increased with acidic pHo. We demonstrate that proton-induced modification of TRPM7 currents depends on the presence of extracellular Ca2+ and Mg2+. Variability of the TRPM7 current density in human cardiomyocytes is related to the clinical history, being higher in atrial fibrillation and in ischemic cardiomyopathy. PMID:28129376

  9. Extracellular proton release by stimulated neutrophils

    SciTech Connect

    van Zwieten, R.; Wever, R.; Hamers, M.N.; Weening, R.S.; Roos, D.

    1981-07-01

    We have tried to elucidate the mechanism of phagosome acidification in human neutrophils. Assuming that phenomena occurring at the plasma membrane reflect reactions in the phagocytic vacuoles, we have stimulated human neutrophils with agents that induce a ''respiratory burst,'' and we have measured the release of protons into the extracellular medium. Phorbol myristate acetate, N-formyl-methionyl-leucyl-phenylalanine and serum-opsonized zymosan particles each caused a rapid release of protons, concomitant with the increase in oxygen consumption. The stimulated release of protons was strictly coupled to the increase respiration of the cells, because inhibition of the respiration of either anaerobiosis, chlorpromazine, or glycolytic inhibitors also inhibited the release of protons. Also, in the presence of the above-mentioned stimulating agents, neutrophils from three patients with chronic granulomatous disease enhanced neither respiration not proton release. In normal cells, the ratio of deltaH+/-deltaO2 was 1.04 +/- 0.19 (mean +/ SD, n . 13). The mechanism of this proton release is not clear. The amount of lactic and carbonic acid produced by stimulated neutrophils was inadequate to explain the amount of protons released. Perhydroxyl radicals were also ruled out as the source of the protons. Because the cells did not release measurable amounts of phosphate ions, a phosphate-hydroxyl-ion antiport was also excluded. Finally, the lack of any effect of uncouplers renders it unlikely that a respiration-driven proton gradient is built up across the plasma membrane.

  10. Physiological compensation for environmental acidification is limited in the deep-sea urchin Strongylocentrotus fragilis

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.; Lovera, C.; Whaling, P. J.; Buck, K. R.; Pane, E. F.; Barry, J. P.

    2013-05-01

    Anthropogenic CO2 is now reaching depths over 1000 m in the Eastern Pacific, overlapping the Oxygen Minimum Zone (OMZ). Deep-sea animals - particularly, calcifiers - are suspected to be especially sensitive to environmental acidification associated with global climate change. We have investigated the effects of hypercapnia and hypoxia on the deep-sea urchin Strongylocentrotus fragilis, during two long-term exposure experiments (1 month and 4 month) at three levels of reduced pH at in situ O2 levels of approx. 10% saturation, and also to control pH at 100% O2 saturation. During the first experiment, internal acid-base balance was investigated during a one-month exposure; results show S. fragilis has limited ability to compensate for the respiratory acidosis brought on by reduced pH, due in part to low non-bicarbonate extracellular fluid buffering capacity. During the second experiment, longer-term effects of hypercapnia and variable O2 on locomotion, feeding, growth, and gonadosomatic index (GSI) were investigated; results show significant mortality and correlation of all measured parameters with environmental acidification at pH 6.6. Transient adverse effects on locomotion and feeding were seen at pH 7.2, without compromise of growth or GSI. Based on the expected changes in ocean pH and oxygen, results suggest extinction of S. fragilis in the eastern North Pacific is unlikely. Rather, we expect a shoaling and contraction of its bathymetric range.

  11. Intraorganellar acidification by V-ATPases: a target in cell proliferation and cancer therapy.

    PubMed

    Hernández, Agustín; Serrano, Gloria; Herrera-Palau, Rosana; Pérez-Castiñeira, José R; Serrano, Aurelio

    2010-06-01

    Vacuolar-type ATPases are multicomponent proton pumps involved in the acidification of single membrane intracellular compartments such as endosomes and lysosomes. They couple the hydrolysis of ATP to the translocation of one to two protons across the membrane. Acidification of the lumen of single membrane organelles is a necessary factor for the correct traffic of membranes and cargo to and from the different internal compartments of a cell. Also, V-ATPases are involved in regulation of pH at the cytosol and, possibly, extracellular milieu. The inhibition of V-ATPases has been shown to induce apoptosis and cell cycle arrest in tumour cells and, therefore, chemicals that behave as inhibitors of this kind of proton pumps have been proposed as putative treatment agents against cancer and many have been patented as such. The compounds filed in patents fall into five major types: plecomacrolides, benzolactone enamides, archazolids, chondropsins and indoles. All these have proved to be apoptosis inducers in cell culture and many to be able to reduce xenograft tumor growth in murine models. The present review will summarize their general structure, origin and mechanisms of action and put them in relation to the patents registered so far for the treatment of cancer.

  12. Ocean acidification reduces spine mechanical strength in euechinoid but not in cidaroid sea urchins.

    PubMed

    Dery, Aurélie; Collard, Marie; Dubois, Philippe

    2017-03-07

    Echinoderms are considered as particularly sensitive to ocean acidification (OA) as their skeleton is made of high-magnesium calcite, one of the most soluble forms of calcium carbonate. Recent studies have investigated effects of OA on the skeleton of "classical" sea urchins (euechinoids) but the impact of etching on skeleton mechanical properties is almost unknown. Furthermore, the integrity of the skeleton of cidaroids has never been assessed although their extracellular fluid is undersaturated with respect to their skeleton and the skeleton of their primary spines is in direct contact with seawater. In this study, we compared the dissolution of test plates and spines as well as the spine mechanical properties (two-points bending tests) in a cidaroid (Eucidaris tribuloides) and a euechinoid (Tripneustes ventricosus) submitted to a 5-weeks acidification experiment (pHT 8.1, 7.7, 7.4). Test plates of both species were not affected by dissolution. Spines of E. tribuloides showed no mechanical effects at pHSW-T 7.4 despite traces of corrosion on secondary spines. On the contrary, spines of the T. ventricosus were significantly etched at both pHSW-T 7.7 and 7.4 and their fracture force reduced by 16 to 35%, respectively. This increased brittleness is probably of little significance with regards to predation protection but has consequences in terms of energy allocation.

  13. Mineralogical response of the Mediterranean crustose coralline alga Lithophyllum cabiochae to near-future ocean acidification and warming

    NASA Astrophysics Data System (ADS)

    Nash, Merinda C.; Martin, Sophie; Gattuso, Jean-Pierre

    2016-11-01

    Red calcareous coralline algae are thought to be among the organisms most vulnerable to ocean acidification due to the high solubility of their magnesium calcite skeleton. Although skeletal mineralogy is proposed to change as CO2 and temperature continue to rise, there is currently very little information available on the response of coralline algal carbonate mineralogy to near-future changes in pCO2 and temperature. Here we present results from a 1-year controlled laboratory experiment to test mineralogical responses to pCO2 and temperature in the Mediterranean crustose coralline alga (CCA) Lithophyllum cabiochae. Our results show that Mg incorporation is mainly constrained by temperature (+1 mol % MgCO3 for an increase of 3 °C), and there was no response to pCO2. This suggests that L. cabiochae thalli have the ability to buffer their calcifying medium against ocean acidification, thereby enabling them to continue to deposit magnesium calcite with a significant mol % MgCO3 under elevated pCO2. Analyses of CCA dissolution chips showed a decrease in Mg content after 1 year for all treatments, but this was affected neither by pCO2 nor by temperature. Our findings suggest that biological processes exert a strong control on calcification on magnesium calcite and that CCA may be more resilient under rising CO2 than previously thought. However, previously demonstrated increased skeletal dissolution with ocean acidification will still have major consequences for the stability and maintenance of Mediterranean coralligenous habitats.

  14. Recognising ocean acidification in deep time: An evaluation of the evidence for acidification across the Triassic-Jurassic boundary

    NASA Astrophysics Data System (ADS)

    Greene, Sarah E.; Martindale, Rowan C.; Ritterbush, Kathleen A.; Bottjer, David J.; Corsetti, Frank A.; Berelson, William M.

    2012-06-01

    While demonstrating ocean acidification in the modern is relatively straightforward (measure increase in atmospheric CO2 and corresponding ocean chemistry change), identifying palaeo-ocean acidification is problematic. The crux of this problem is that the rock record is a constructive archive while ocean acidification is essentially a destructive (and/or inhibitory) phenomenon. This is exacerbated in deep time without the benefit of a deep ocean record. Here, we discuss the feasibility of, and potential criteria for, identifying an acidification event in deep time. Furthermore, we investigate the evidence for ocean acidification during the Triassic-Jurassic (T-J) boundary interval, an excellent test case because 1) it occurs in deep time, beyond the reach of deep sea drilling coverage; 2) a potential trigger for acidification is known; and 3) it is associated with one of the 'Big Five' mass extinctions which disproportionately affected modern-style invertebrates. Three main criteria suggest that acidification may have occurred across the T-J transition. 1) The eruption of the Central Atlantic Magmatic Province (CAMP) and the associated massive and rapid release of CO2 coincident with the end-Triassic mass extinction provide a suitable trigger for an acidification event (full carbonate undersaturation in the surface ocean is possible but improbable). 2) Tentative evidence for a global paucity of carbonate across the end-Triassic mass extinction versus the adjacent stratigraphy is consistent with a predicted sedimentary response to acidification. 3) The end-Triassic mass extinction was particularly selective against acid-sensitive organisms (more so than perhaps any other extinction event) and temporarily eliminated coral reefs. Therefore multiple lines of evidence are consistent with a T-J ocean acidification event within our current resolution to recognise such events in deep time. The conclusion that the end-Triassic extinction was influenced by acidification

  15. Physiological, toxicological, and population responses of smallmouth bass to acidification. Lake Acidification and Fisheries Project

    SciTech Connect

    Marcus, M.D.; Gulley, D.D.; Christensen, S.W.; McDonald, D.G.; Van Winkle, W.; Mount, D.R.; Wood, C.M.; Bergman, H.L.

    1992-08-01

    The Lake Acidification and Fisheries (LAF) project examined effects of acidic water chemistries on four fish species. This report presents an overview of investigations on smallmouth bass (Micropterus dolomieui). Experiments conducted with this species included as many as 84 exposure combinations of acid, aluminum, and low calcium. In egg, fry, and juvenile stages of smallmouth bass, increased acid and aluminum concentrations increased mortality and decreased growth, while increased calcium concentrations often improved survival. Relative to the juvenile life stages of smallmouth bass tested, yolksac and swim-up fry were clearly more sensitive to stressful exposure conditions. While eggs appeared to be the most sensitive life stage, this conclusion was compromised by heavy mortalities of eggs due to fungal infestations during experimental exposures. As found in our earlier studies with brook and rainbow trout, acid-aluminum stressed smallmouth bass exhibited net losses of electrolytes across gills and increased accumulation of aluminum on gill tissues. Overall, our results indicated that smallmouth bass were generally more sensitive to increased exposure concentrations of aluminum than to increased acidities. Compared to toxicology results from earlier LAF project studies, smallmouth bass were more sensitive than brook trout and slightly less sensitive than rainbow trout when exposed to water quality conditions associated with acidification.An example application of the LAF modeling framework shows how different liming scenarios can improve survival probabilities for smallmouth bass in a set of lakes sensitive to acidification.

  16. The contribution of lactic acid to acidification of tumours: studies of variant cells lacking lactate dehydrogenase.

    PubMed Central

    Yamagata, M.; Hasuda, K.; Stamato, T.; Tannock, I. F.

    1998-01-01

    Solid tumours develop an acidic extracellular environment with high concentration of lactic acid, and lactic acid produced by glycolysis has been assumed to be the major cause of tumour acidity. Experiments using lactate dehydrogenase (LDH)-deficient ras-transfected Chinese hamster ovarian cells have been undertaken to address directly the hypothesis that lactic acid production is responsible for tumour acidification. The variant cells produce negligible quantities of lactic acid and consume minimal amounts of glucose compared with parental cells. Lactate-producing parental cells acidified lightly-buffered medium but variant cells did not. Tumours derived from parental and variant cells implanted into nude mice were found to have mean values of extracellular pH (pHe) of 7.03 +/- 0.03 and 7.03 +/- 0.05, respectively, both of which were significantly lower than that of normal muscle (pHe = 7.43 +/- 0.03; P < 0.001). Lactic acid concentration in variant tumours (450 +/- 90 microg g(-1) wet weight) was much lower than that in parental tumours (1880 +/- 140 microg/g(-1)) and similar to that in serum (400 +/- 35 microg/g(-1)). These data show discordance between mean levels of pHe and lactate content in tumours; the results support those of Newell et al (1993) and suggest that the production of lactic acid via glycolysis causes acidification of culture medium, but is not the only mechanism, and is probably not the major mechanism responsible for the development of an acidic environment within solid tumours. PMID:9667639

  17. The lake acidification mitigation project (LAMP)

    SciTech Connect

    Porcella, D.P. )

    1987-01-01

    In areas where there is limited capacity to resist input of acid deposition, acid soils and surface waters have affected natural communities and man's uses of the environment. In response to problems of acid soils, farmers added limestone materials to their soil during Roman times; this method of agricultural management continues today. The addition of limestone (CaCo/sub 3/), called liming, has been used more recently to mitigate acidic conditions in lakes and streams. Liming neutralizes acidity directly, provides buffering as acid neutralizing capacity (ANC) or alkalinity, and increases calcium ion concentration which mitigates toxicity in low ionic strength waters. The Lake Acidification Mitigation Project (LAMP) has the objective of identifying and quantifying environmental impacts of liming, and evaluating the effectiveness of liming and stocking procedures in restoring acid lakes. The purpose of this paper is to provide an overview of LAMP and to summarize results from the initial phases of the project.

  18. Ocean acidification changes the male fitness landscape

    NASA Astrophysics Data System (ADS)

    Campbell, Anna L.; Levitan, Don R.; Hosken, David J.; Lewis, Ceri

    2016-08-01

    Sperm competition is extremely common in many ecologically important marine taxa. Ocean acidification (OA) is driving rapid changes to the marine environments in which freely spawned sperm operate, yet the consequences of OA on sperm performance are poorly understood in the context of sperm competition. Here, we investigated the impacts of OA (+1000 μatm pCO2) on sperm competitiveness for the sea urchin Paracentrotus lividus. Males with faster sperm had greater competitive fertilisation success in both seawater conditions. Similarly, males with more motile sperm had greater sperm competitiveness, but only under current pCO2 levels. Under OA the strength of this association was significantly reduced and there were male sperm performance rank changes under OA, such that the best males in current conditions are not necessarily best under OA. Therefore OA will likely change the male fitness landscape, providing a mechanism by which environmental change alters the genetic landscape of marine species.

  19. Ocean acidification changes the male fitness landscape

    PubMed Central

    Campbell, Anna L.; Levitan, Don R.; Hosken, David J.; Lewis, Ceri

    2016-01-01

    Sperm competition is extremely common in many ecologically important marine taxa. Ocean acidification (OA) is driving rapid changes to the marine environments in which freely spawned sperm operate, yet the consequences of OA on sperm performance are poorly understood in the context of sperm competition. Here, we investigated the impacts of OA (+1000 μatm pCO2) on sperm competitiveness for the sea urchin Paracentrotus lividus. Males with faster sperm had greater competitive fertilisation success in both seawater conditions. Similarly, males with more motile sperm had greater sperm competitiveness, but only under current pCO2 levels. Under OA the strength of this association was significantly reduced and there were male sperm performance rank changes under OA, such that the best males in current conditions are not necessarily best under OA. Therefore OA will likely change the male fitness landscape, providing a mechanism by which environmental change alters the genetic landscape of marine species. PMID:27531458

  20. Ocean acidification impairs vermetid reef recruitment

    PubMed Central

    Milazzo, Marco; Rodolfo-Metalpa, Riccardo; Chan, Vera Bin San; Fine, Maoz; Alessi, Cinzia; Thiyagarajan, Vengatesen; Hall-Spencer, Jason M.; Chemello, Renato

    2014-01-01

    Vermetids form reefs in sub-tropical and warm-temperate waters that protect coasts from erosion, regulate sediment transport and accumulation, serve as carbon sinks and provide habitat for other species. The gastropods that form these reefs brood encapsulated larvae; they are threatened by rapid environmental changes since their ability to disperse is very limited. We used transplant experiments along a natural CO2 gradient to assess ocean acidification effects on the reef-building gastropod Dendropoma petraeum. We found that although D. petraeum were able to reproduce and brood at elevated levels of CO2, recruitment success was adversely affected. Long-term exposure to acidified conditions predicted for the year 2100 and beyond caused shell dissolution and a significant increase in shell Mg content. Unless CO2 emissions are reduced and conservation measures taken, our results suggest these reefs are in danger of extinction within this century, with significant ecological and socioeconomic ramifications for coastal systems. PMID:24577050

  1. Episodic acidification of Adirondack lakes during snowmelt

    SciTech Connect

    Schaefer, D.A.; Driscoll, C.T.; Van Dreason, R.; Yatsko, C.P.

    1990-07-01

    Maximum values of acid neutralizing capacity (ANC) in Adirondack, New York lake outlets generally occur during summer and autumn. During spring snowmelt, transport of acidic water through acid-sensitive watersheds causes depression of upper lake water ANC. In some systems lake outlet ANC reaches negative values. The authors examined outlet water chemistry from II Adirondack lakes during 1986 and 1987 snowmelts. In these lakes, SO concentrations were diluted during snowmelt and did not depress ANC. For lakes with high baseline ANC values, springtime ANC depressions were primarily accompanied by basic cation dilution. For lakes with low baseline ANC, No increases dominated ANC depressions. Lakes with intermediate baseline ANC were affected by both processes and exhibited larger ANC depressions. Ammonium dilution only affected wetland systems. A model predicting a linear relationship between outlet water ANC minima and autumn ANC was inappropriate. To assess watershed response to episodic acidification, hydrologic flow paths must be considered. (Copyright (c) 1990 by the American Geophysical Union.)

  2. Ocean acidification impairs vermetid reef recruitment

    NASA Astrophysics Data System (ADS)

    Milazzo, Marco; Rodolfo-Metalpa, Riccardo; Chan, Vera Bin San; Fine, Maoz; Alessi, Cinzia; Thiyagarajan, Vengatesen; Hall-Spencer, Jason M.; Chemello, Renato

    2014-02-01

    Vermetids form reefs in sub-tropical and warm-temperate waters that protect coasts from erosion, regulate sediment transport and accumulation, serve as carbon sinks and provide habitat for other species. The gastropods that form these reefs brood encapsulated larvae; they are threatened by rapid environmental changes since their ability to disperse is very limited. We used transplant experiments along a natural CO2 gradient to assess ocean acidification effects on the reef-building gastropod Dendropoma petraeum. We found that although D. petraeum were able to reproduce and brood at elevated levels of CO2, recruitment success was adversely affected. Long-term exposure to acidified conditions predicted for the year 2100 and beyond caused shell dissolution and a significant increase in shell Mg content. Unless CO2 emissions are reduced and conservation measures taken, our results suggest these reefs are in danger of extinction within this century, with significant ecological and socioeconomic ramifications for coastal systems.

  3. Effects of acidification on aquatic primary producers and decomposers

    SciTech Connect

    Hendrey, G.R.

    1981-06-01

    Acidification of nutrient-poor, clearwater lakes and streams is associated with a variety of changes in communities of aquatic organisms. While acidification may eliminate fish, it does not kill the lake. Some species become very abundant in acidified waters and the balance among organisms, which provide stability to the aquatic ecosystem, is lost. This is reflected in accumulations of algae and dead plant litter. While these kinds of changes are observed, studies which quantitatively link the effects of acidification at one ecological level to changes in some other level are lacking. One can only surmise that such links are significant to ecosystem structure and functioning.

  4. Ocean acidification alters fish-jellyfish symbiosis.

    PubMed

    Nagelkerken, Ivan; Pitt, Kylie A; Rutte, Melchior D; Geertsma, Robbert C

    2016-06-29

    Symbiotic relationships are common in nature, and are important for individual fitness and sustaining species populations. Global change is rapidly altering environmental conditions, but, with the exception of coral-microalgae interactions, we know little of how this will affect symbiotic relationships. We here test how the effects of ocean acidification, from rising anthropogenic CO2 emissions, may alter symbiotic interactions between juvenile fish and their jellyfish hosts. Fishes treated with elevated seawater CO2 concentrations, as forecast for the end of the century on a business-as-usual greenhouse gas emission scenario, were negatively affected in their behaviour. The total time that fish (yellowtail scad) spent close to their jellyfish host in a choice arena where they could see and smell their host was approximately three times shorter under future compared with ambient CO2 conditions. Likewise, the mean number of attempts to associate with jellyfish was almost three times lower in CO2-treated compared with control fish, while only 63% (high CO2) versus 86% (control) of all individuals tested initiated an association at all. By contrast, none of three fish species tested were attracted solely to jellyfish olfactory cues under present-day CO2 conditions, suggesting that the altered fish-jellyfish association is not driven by negative effects of ocean acidification on olfaction. Because shelter is not widely available in the open water column and larvae of many (and often commercially important) pelagic species associate with jellyfish for protection against predators, modification of the fish-jellyfish symbiosis might lead to higher mortality and alter species population dynamics, and potentially have flow-on effects for their fisheries.

  5. Coastal ocean acidification: The other eutrophication problem

    NASA Astrophysics Data System (ADS)

    Wallace, Ryan B.; Baumann, Hannes; Grear, Jason S.; Aller, Robert C.; Gobler, Christopher J.

    2014-07-01

    Increased nutrient loading into estuaries causes the accumulation of algal biomass, and microbial degradation of this organic matter decreases oxygen levels and contributes towards hypoxia. A second, often overlooked consequence of microbial degradation of organic matter is the production of carbon dioxide (CO2) and a lowering of seawater pH. To assess the potential for acidification in eutrophic estuaries, the levels of dissolved oxygen (DO), pH, the partial pressure of carbon dioxide (pCO2), and the saturation state for aragonite (Ωaragonite) were horizontally and vertically assessed during the onset, peak, and demise of low oxygen conditions in systems across the northeast US including Narragansett Bay (RI), Long Island Sound (CT-NY), Jamaica Bay (NY), and Hempstead Bay (NY). Low pH conditions (<7.4) were detected in all systems during summer and fall months concurrent with the decline in DO concentrations. While hypoxic waters and/or regions in close proximity to sewage discharge had extremely high levels of pCO2, (>3000 μatm), were acidic pH (<7.0), and were undersaturated with regard to aragonite (Ωaragonite < 1), even near-normoxic but eutrophic regions of these estuaries were often relatively acidified (pH < 7.7) during late summer and/or early fall. The close spatial and temporal correspondence between DO and pH and the occurrence of extremes in these conditions in regions with the most intense nutrient loading indicated that they were primarily driven by microbial respiration. Given that coastal acidification is promoted by nutrient-enhanced organic matter loading and reaches levels that have previously been shown to negatively impact the growth and survival of marine organisms, it may be considered an additional symptom of eutrophication that warrants managerial attention.

  6. Water acidification trends in a reservoir of the Iberian Pyrite Belt (SW Spain).

    PubMed

    Cánovas, C R; Olías, M; Macias, F; Torres, E; San Miguel, E G; Galván, L; Ayora, C; Nieto, J M

    2016-01-15

    Scarcity of waters is the main limiting factor of economic development in most arid and semi-arid regions worldwide. The construction of reservoirs may be an optimal solution to assure water availability if the drainage area shows low disturbances. This is the quandary of mining areas where economic development relies on water accessibility. Water acidification trends were investigated in the Sancho Reservoir (SW Spain) in the last 20 years. The acidity (pH3-5) and high dissolved metal concentrations (e.g., 4.4 mg/L of Al, 2.1mg/L of Mn, 1.9 mg/L of Zn) observed in the Sancho, together with the large volume stored (between 37 and 55 Mm(3)), makes this reservoir an extreme case of surface water pollution worldwide. A progressive acidification has been observed since 2003, as evidenced by decreasing pH values and increasing dissolved metal concentrations, especially noticeable after 2007. The increase in the net acidity in the reservoir originates from the higher input of metals and acidity due to the rebound effect after the mining closure in 2001. This trend was not detected in the river feeding the reservoir due to its great hydrological and hydrochemical variability, typical of the Mediterranean climate. Chemical analysis and absolute dating of sediments identified a progressive enrichment in S and metals (i.e., Fe, Zn Cu, Ni, Co and Cd) in the upper 20 cm, which reinforce the year 2002/03 as the onset of the acidification of the reservoir. The decrease of pH values from 4-5 to 3-4 occurred later than the increase in sulfate and metals due to pH-buffering by Al. The acid mine drainage (AMD) pressure has caused an increment of dissolved Fe and other metals, as well as a change in the pH buffering role, exerted now by Fe. These processes were simulated by PHREEQC, which confirms that the acidification trend will continue, causing pH values to reach 2.5 if AMD pressure persists.

  7. Effect of ocean acidification on iron availability to marine phytoplankton.

    PubMed

    Shi, Dalin; Xu, Yan; Hopkinson, Brian M; Morel, François M M

    2010-02-05

    The acidification caused by the dissolution of anthropogenic carbon dioxide (CO2) in the ocean changes the chemistry and hence the bioavailability of iron (Fe), a limiting nutrient in large oceanic regions. Here, we show that the bioavailability of dissolved Fe may decline because of ocean acidification. Acidification of media containing various Fe compounds decreases the Fe uptake rate of diatoms and coccolithophores to an extent predicted by the changes in Fe chemistry. A slower Fe uptake by a model diatom with decreasing pH is also seen in experiments with Atlantic surface water. The Fe requirement of model phytoplankton remains unchanged with increasing CO2. The ongoing acidification of seawater is likely to increase the Fe stress of phytoplankton populations in some areas of the ocean.

  8. Effect of Ocean Acidification on Iron Availability to Marine Phytoplankton

    NASA Astrophysics Data System (ADS)

    Shi, Dalin; Xu, Yan; Hopkinson, Brian M.; Morel, François M. M.

    2010-02-01

    The acidification caused by the dissolution of anthropogenic carbon dioxide (CO2) in the ocean changes the chemistry and hence the bioavailability of iron (Fe), a limiting nutrient in large oceanic regions. Here, we show that the bioavailability of dissolved Fe may decline because of ocean acidification. Acidification of media containing various Fe compounds decreases the Fe uptake rate of diatoms and coccolithophores to an extent predicted by the changes in Fe chemistry. A slower Fe uptake by a model diatom with decreasing pH is also seen in experiments with Atlantic surface water. The Fe requirement of model phytoplankton remains unchanged with increasing CO2. The ongoing acidification of seawater is likely to increase the Fe stress of phytoplankton populations in some areas of the ocean.

  9. An improved flow cytometry assay to monitor phagosome acidification.

    PubMed

    Colas, Chloé; Menezes, Shinelle; Gutiérrez-Martínez, Enric; Péan, Claire B; Dionne, Marc S; Guermonprez, Pierre

    2014-10-01

    Phago-lysosome formation is important for cell-autonomous immunity to intracellular pathogens, antigen presentation and metabolism. A hallmark feature of phago-lysosomal compartments is that they undergo progressive luminal acidification controlled by the activation of vacuolar V-ATPase. Acidification is required for many enzymatic processes taking place in phago-lysosomes, like proteolysis, and supports the microbicidal activity of macrophages. Here we present a new quantitative methodology to assess phagosome acidification by flow cytometry based on the use of bi-fluorescent particles. This method relies on the use of UV polystyrene beads labelled with the acid sensor pHrodo-succinimidyl ester (pHrodo(TM) SE red) and enables us to dissociate particle association with phagocytes from their engulfment in acidified compartments. This methodology is well suited to monitor the acidification of phagosomes formed in vivo after fluorescent bead administration.

  10. Climate change and ocean acidification-interactions with aquatic toxicology.

    PubMed

    Nikinmaa, Mikko

    2013-01-15

    The possibilities for interactions between toxicants and ocean acidification are reviewed from two angles. First, it is considered how toxicant responses may affect ocean acidification by influencing the carbon dioxide balance. Second, it is introduced, how the possible changes in environmental conditions (temperature, pH and oxygenation), expected to be associated with climate change and ocean acidification, may interact with the toxicant responses of organisms, especially fish. One significant weakness in available data is that toxicological research has seldom been connected with ecological and physiological/biochemical research evaluating the responses of organisms to temperature, pH or oxygenation changes occurring in the natural environment. As a result, although there are significant potential interactions between toxicants and natural environmental responses pertaining to climate change and ocean acidification, it is very poorly known if such interactions actually occur, and can be behind the observed disturbances in the function and distribution of organisms in our seas.

  11. Towards improved socio-economic assessments of ocean acidification's impacts.

    PubMed

    Hilmi, Nathalie; Allemand, Denis; Dupont, Sam; Safa, Alain; Haraldsson, Gunnar; Nunes, Paulo A L D; Moore, Chris; Hattam, Caroline; Reynaud, Stéphanie; Hall-Spencer, Jason M; Fine, Maoz; Turley, Carol; Jeffree, Ross; Orr, James; Munday, Philip L; Cooley, Sarah R

    2013-01-01

    Ocean acidification is increasingly recognized as a component of global change that could have a wide range of impacts on marine organisms, the ecosystems they live in, and the goods and services they provide humankind. Assessment of these potential socio-economic impacts requires integrated efforts between biologists, chemists, oceanographers, economists and social scientists. But because ocean acidification is a new research area, significant knowledge gaps are preventing economists from estimating its welfare impacts. For instance, economic data on the impact of ocean acidification on significant markets such as fisheries, aquaculture and tourism are very limited (if not non-existent), and non-market valuation studies on this topic are not yet available. Our paper summarizes the current understanding of future OA impacts and sets out what further information is required for economists to assess socio-economic impacts of ocean acidification. Our aim is to provide clear directions for multidisciplinary collaborative research.

  12. Ocean and Coastal Acidification off New England and Nova Scotia

    EPA Science Inventory

    New England coastal and adjacent Nova Scotia shelf waters have a reduced buffering capacity because of significant freshwater input, making the region’s waters potentially more vulnerable to coastal acidification. Nutrient loading and heavy precipitation events further acid...

  13. Cold thermoregulatory responses following exertional fatigue.

    PubMed

    Castellani, John W; Sawka, Michael N; DeGroot, David W; Young, Andrew J

    2010-06-01

    Participants in prolonged, physically demanding cold-weather activities are at risk for a condition called "thermoregulatory fatigue". During cold exposure, the increased gradient favoring body heat loss to the environment is opposed by physiological responses and clothing and behavioral strategies that conserve body heat stores to defend body temperature. The primary human physiological responses elicited by cold exposure are shivering and peripheral vasoconstriction. Shivering increases thermogenesis and replaces body heat losses, while peripheral vasoconstriction improves thermal insulation of the body and retards the rate of heat loss. A body of scientific literature supports the concept that prolonged and/or repeated cold exposure, fatigue induced by sustained physical exertion, or both together, can impair the shivering and vasoconstrictor responses to cold ("thermoregulatory fatigue"). The mechanisms accounting for this thermoregulatory impairment are not clear, but there is evidence to suggest that changes in central thermoregulatory control or peripheral sympathetic responsiveness to cold lead to thermoregulatory fatigue and increased susceptibility to hypothermia.

  14. A global pattern of soil acidification caused by nitrogen deposition

    NASA Astrophysics Data System (ADS)

    Niu, S.; Tian, D., Sr.

    2014-12-01

    Nitrogen (N) deposition-induced soil acidification has become a global problem. However, the response patterns of soil acidification to N addition and the underlying mechanisms remain far from unclear. Here, we conducted a meta-analysis of 106 studies to reveal global patterns of soil acidification in responses to N addition. We found that N addition significantly reduced soil pH by 0.23 on average globally. However, the response ratio of soil pH varied with ecosystem types, N addition rate, N fertilization forms, and experimental durations. Soil pH decreased most in grassland, whereas boreal forest was insensitive to N addition in soil acidification. Soil pH decreased linearly with N addition rates. Addition of urea and NH4NO3 contributed more to soil acidification than NH4-form fertilizer. When experimental duration was longer than 20 years, N addition effects on soil acidification diminished. Environmental factors such as initial soil pH, soil carbon and nitrogen content, precipitation, and temperature all influenced the response ratio of soil pH. Base cations of Ca2+, Mg2+ and K+ were critical important in buffering against N-induced soil acidification at the early stage. However, N addition has shifted global soils into the Al3+ buffering phase. Overall, this study indicates that acidification in global soils is very sensitive to N deposition, which is greatly modified by biotic and abiotic factors. Global soils are now at a buffering transition from base cations (Ca2+, Mg2+ and K+) to non-base cations (Mn2+ and Al3+). This calls our attention to care about the limitation of base cations and the toxic impact of non-base cations for terrestrial ecosystems with N deposition.

  15. A global analysis of soil acidification caused by nitrogen addition

    NASA Astrophysics Data System (ADS)

    Tian, Dashuan; Niu, Shuli

    2015-02-01

    Nitrogen (N) deposition-induced soil acidification has become a global problem. However, the response patterns of soil acidification to N addition and the underlying mechanisms remain far from clear. Here, we conducted a meta-analysis of 106 studies to reveal global patterns of soil acidification in responses to N addition. We found that N addition significantly reduced soil pH by 0.26 on average globally. However, the responses of soil pH varied with ecosystem types, N addition rate, N fertilization forms, and experimental durations. Soil pH decreased most in grassland, whereas boreal forest was not observed a decrease to N addition in soil acidification. Soil pH decreased linearly with N addition rates. Addition of urea and NH4NO3 contributed more to soil acidification than NH4-form fertilizer. When experimental duration was longer than 20 years, N addition effects on soil acidification diminished. Environmental factors such as initial soil pH, soil carbon and nitrogen content, precipitation, and temperature all influenced the responses of soil pH. Base cations of Ca2+, Mg2+ and K+ were critical important in buffering against N-induced soil acidification at the early stage. However, N addition has shifted global soils into the Al3+ buffering phase. Overall, this study indicates that acidification in global soils is very sensitive to N deposition, which is greatly modified by biotic and abiotic factors. Global soils are now at a buffering transition from base cations (Ca2+, Mg2+ and K+) to non-base cations (Mn2+ and Al3+). This calls our attention to care about the limitation of base cations and the toxic impact of non-base cations for terrestrial ecosystems with N deposition.

  16. Devising a Coral Reef Ocean Acidification Monitoring Portfolio

    NASA Astrophysics Data System (ADS)

    Gledhill, D. K.; Jewett, L.

    2012-12-01

    Coral reef monitoring has frequently been based only on descriptive science with limited capacity to assign specific attribution to agents of change. There is a requirement to engineer a diagnostic monitoring approach that can test predictions regarding the response of coral reef ecosystems to ocean acidification, and to identify potential areas of refugia or areas of particular concern. The approach should provide the means to detect not only changes in water chemistry but also changes in coral reef community structure and function which can be anticipated based upon our current understanding of paleo-OA events, experimental findings, process investigations, and modeling projections In August, 2012 a Coral Reef Ocean Acidification Monitoring Portfolio Workshop was hosted by the NOAA Ocean Acidification Program and the National Coral Reef Institute at the Nova Southeastern University Oceanographic Center. The workshop convened researchers and project managers from around the world engaged in coral reef ecosystems ocean acidification monitoring and research. The workshop sought to define a suite of metrics to include as part of long-term coral reef monitoring efforts that can contribute to discerning specific attribution of changes in coral reef ecosystems in response to ocean acidification. This portfolio of observations should leverage existing and proposed monitoring initiatives and would be derived from a suite of chemical, biogeochemical and ecological measurements. This talk will report out on the key findings from the workshop which should include identifying the most valuable that should be integrated into long-term coral reef ecosystem monitoring that will aid in discerning changes in coral reef ecosystems in response to ocean acidification. The outcomes should provide: recommendations of the most efficient and robust ways to monitor these metrics; identified augmentations that would be required to current ocean acidification monitoring necessary to achieve

  17. Extracellular histones inhibit efferocytosis.

    PubMed

    Friggeri, Arnaud; Banerjee, Sami; Xie, Na; Cui, Huachun; De Freitas, Andressa; Zerfaoui, Mourad; Dupont, Hervé; Abraham, Edward; Liu, Gang

    2012-07-18

    The uptake and clearance of apoptotic cells by macrophages and other phagocytic cells, a process called efferocytosis, is a major component in the resolution of inflammation. Increased concentrations of extracellular histones are found during acute inflammatory states and appear to contribute to organ system dysfunction and mortality. In these studies, we examined the potential role of histones in modulating efferocytosis. We found that phagocytosis of apoptotic neutrophils or thymocytes by macrophages was significantly diminished in the presence of histones H3 or H4, but not histone H1. Histone H3 demonstrated direct binding to macrophages, an effect that was diminished by preincubation of macrophages with the opsonins growth arrest-specific gene 6 (Gas6) and milk fat globule-epidermal growth factor (EGF) 8 (MFG-E8). Incubation of histone H3 with soluble α(v)β₅ integrin and Mer, but not with α(v)β₃, diminished its binding to macrophages. Phagocytosis of apoptotic cells by alveolar macrophages in vivo was diminished in the presence of histone H3. Incubation of histone H3 with activated protein C, a treatment that degrades histones, abrogated its inhibitory effects on efferocytosis under both in vitro and in vivo conditions. The present studies demonstrate that histones have inhibitory effects on efferocytosis, suggesting a new mechanism by which extracellular histones contribute to acute inflammatory processes and tissue injury.

  18. Ocean acidification and its potential effects on marine ecosystems.

    PubMed

    Guinotte, John M; Fabry, Victoria J

    2008-01-01

    Ocean acidification is rapidly changing the carbonate system of the world oceans. Past mass extinction events have been linked to ocean acidification, and the current rate of change in seawater chemistry is unprecedented. Evidence suggests that these changes will have significant consequences for marine taxa, particularly those that build skeletons, shells, and tests of biogenic calcium carbonate. Potential changes in species distributions and abundances could propagate through multiple trophic levels of marine food webs, though research into the long-term ecosystem impacts of ocean acidification is in its infancy. This review attempts to provide a general synthesis of known and/or hypothesized biological and ecosystem responses to increasing ocean acidification. Marine taxa covered in this review include tropical reef-building corals, cold-water corals, crustose coralline algae, Halimeda, benthic mollusks, echinoderms, coccolithophores, foraminifera, pteropods, seagrasses, jellyfishes, and fishes. The risk of irreversible ecosystem changes due to ocean acidification should enlighten the ongoing CO(2) emissions debate and make it clear that the human dependence on fossil fuels must end quickly. Political will and significant large-scale investment in clean-energy technologies are essential if we are to avoid the most damaging effects of human-induced climate change, including ocean acidification.

  19. Differentiated Ratings of Perceived Exertion during Physical Exercise

    DTIC Science & Technology

    1982-01-01

    MEDICINE AND SCIENCE IN SPORTS AND EXERCISE VOl 14, No 5. Pp 397-405. 1982 -1982 Differentiated ratings of perceived exertion during physical ...that PANDOLF, KENT B. Differentiated ratings of perceived exertion utilizes differentiated ratings of perceived exertion (RPE) during physical exercise ...in the eval- Specific instructions and procedures for the utilization uation of effort sensations during physical exercise . Ekblom and Goldbarg (17

  20. Sensitivity of pelagic calcification to ocean acidification

    NASA Astrophysics Data System (ADS)

    Gangstø, R.; Joos, F.; Gehlen, M.

    2011-02-01

    Ocean acidification might reduce the ability of calcifying plankton to produce and maintain their shells of calcite, or of aragonite, the more soluble form of CaCO3. In addition to possibly large biological impacts, reduced CaCO3 production corresponds to a negative feedback on atmospheric CO2. In order to explore the sensitivity of the ocean carbon cycle to increasing concentrations of atmospheric CO2, we use the new biogeochemical Bern3D/PISCES model. The model reproduces the large scale distributions of biogeochemical tracers. With a range of sensitivity studies, we explore the effect of (i) using different parameterizations of CaCO3 production fitted to available laboratory and field experiments, of (ii) letting calcite and aragonite be produced by auto- and heterotrophic plankton groups, and of (iii) using carbon emissions from the range of the most recent IPCC Representative Concentration Pathways (RCP). Under a high-emission scenario, the CaCO3 production of all the model versions decreases from ~1 Pg C yr-1 to between 0.36 and 0.82 Pg C yr-1 by the year 2100. The changes in CaCO3 production and dissolution resulting from ocean acidification provide only a small feedback on atmospheric CO2 of -1 to -11 ppm by the year 2100, despite the wide range of parameterizations, model versions and scenarios included in our study. A potential upper limit of the CO2-calcification/dissolution feedback of -30 ppm by the year 2100 is computed by setting calcification to zero after 2000 in a high 21st century emission scenario. The similarity of feedback estimates yielded by the model version with calcite produced by nanophytoplankton and the one with calcite, respectively aragonite produced by mesozooplankton suggests that expending biogeochemical models to calcifying zooplankton might not be needed to simulate biogeochemical impacts on the marine carbonate cycle. The changes in saturation state confirm previous studies indicating that future anthropogenic CO2 emissions may

  1. Vitamin A Deficiency and Alterations in the Extracellular Matrix

    PubMed Central

    Barber, Teresa; Esteban-Pretel, Guillermo; Marín, María Pilar; Timoneda, Joaquín

    2014-01-01

    Vitamin A or retinol which is the natural precursor of several biologically active metabolites can be considered the most multifunctional vitamin in mammals. Its deficiency is currently, along with protein malnutrition, the most serious and common nutritional disorder worldwide. It is necessary for normal embryonic development and postnatal tissue homeostasis, and exerts important effects on cell proliferation, differentiation and apoptosis. These actions are produced mainly by regulating the expression of a variety of proteins through transcriptional and non-transcriptional mechanisms. Extracellular matrix proteins are among those whose synthesis is known to be modulated by vitamin A. Retinoic acid, the main biologically active form of vitamin A, influences the expression of collagens, laminins, entactin, fibronectin, elastin and proteoglycans, which are the major components of the extracellular matrix. Consequently, the structure and macromolecular composition of this extracellular compartment is profoundly altered as a result of vitamin A deficiency. As cell behavior, differentiation and apoptosis, and tissue mechanics are influenced by the extracellular matrix, its modifications potentially compromise organ function and may lead to disease. This review focuses on the effects of lack of vitamin A in the extracellular matrix of several organs and discusses possible molecular mechanisms and pathologic implications. PMID:25389900

  2. Extracellular matrix structure.

    PubMed

    Theocharis, Achilleas D; Skandalis, Spyros S; Gialeli, Chrysostomi; Karamanos, Nikos K

    2016-02-01

    Extracellular matrix (ECM) is a non-cellular three-dimensional macromolecular network composed of collagens, proteoglycans/glycosaminoglycans, elastin, fibronectin, laminins, and several other glycoproteins. Matrix components bind each other as well as cell adhesion receptors forming a complex network into which cells reside in all tissues and organs. Cell surface receptors transduce signals into cells from ECM, which regulate diverse cellular functions, such as survival, growth, migration, and differentiation, and are vital for maintaining normal homeostasis. ECM is a highly dynamic structural network that continuously undergoes remodeling mediated by several matrix-degrading enzymes during normal and pathological conditions. Deregulation of ECM composition and structure is associated with the development and progression of several pathologic conditions. This article emphasizes in the complex ECM structure as to provide a better understanding of its dynamic structural and functional multipotency. Where relevant, the implication of the various families of ECM macromolecules in health and disease is also presented.

  3. Will ocean acidification affect marine microbes?

    PubMed Central

    Joint, Ian; Doney, Scott C; Karl, David M

    2011-01-01

    The pH of the surface ocean is changing as a result of increases in atmospheric carbon dioxide (CO2), and there are concerns about potential impacts of lower pH and associated alterations in seawater carbonate chemistry on the biogeochemical processes in the ocean. However, it is important to place these changes within the context of pH in the present-day ocean, which is not constant; it varies systematically with season, depth and along productivity gradients. Yet this natural variability in pH has rarely been considered in assessments of the effect of ocean acidification on marine microbes. Surface pH can change as a consequence of microbial utilization and production of carbon dioxide, and to a lesser extent other microbially mediated processes such as nitrification. Useful comparisons can be made with microbes in other aquatic environments that readily accommodate very large and rapid pH change. For example, in many freshwater lakes, pH changes that are orders of magnitude greater than those projected for the twenty second century oceans can occur over periods of hours. Marine and freshwater assemblages have always experienced variable pH conditions. Therefore, an appropriate null hypothesis may be, until evidence is obtained to the contrary, that major biogeochemical processes in the oceans other than calcification will not be fundamentally different under future higher CO2/lower pH conditions. PMID:20535222

  4. Population-dependent effects of ocean acidification.

    PubMed

    Wood, Hannah L; Sundell, Kristina; Almroth, Bethanie Carney; Sköld, Helén Nilsson; Eriksson, Susanne P

    2016-04-13

    Elevated carbon dioxide levels and the resultant ocean acidification (OA) are changing the abiotic conditions of the oceans at a greater rate than ever before and placing pressure on marine species. Understanding the response of marine fauna to this change is critical for understanding the effects of OA. Population-level variation in OA tolerance is highly relevant and important in the determination of ecosystem resilience and persistence, but has received little focus to date. In this study, whether OA has the same biological consequences in high-salinity-acclimated population versus a low-salinity-acclimated population of the same species was investigated in the marine isopod Idotea balthica.The populations were found to have physiologically different responses to OA. While survival rate was similar between the two study populations at a future CO2 level of 1000 ppm, and both populations showed increased oxidative stress, the metabolic rate and osmoregulatory activity differed significantly between the two populations. The results of this study demonstrate that the physiological response to OA of populations from different salinities can vary. Population-level variation and the environment provenance of individuals used in OA experiments should be taken into account for the evaluation and prediction of climate change effects.

  5. Ocean acidification and marine trace gas emissions.

    PubMed

    Hopkins, Frances E; Turner, Suzanne M; Nightingale, Philip D; Steinke, Michael; Bakker, Dorothee; Liss, Peter S

    2010-01-12

    The oceanic uptake of man-made CO(2) emissions is resulting in a measureable decrease in the pH of the surface oceans, a process which is predicted to have severe consequences for marine biological and biogeochemical processes [Caldeira K, Wickett ME (2003) Nature 425:365; The Royal Society (2005) Policy Document 12/05 (Royal Society, London)]. Here, we describe results showing how a doubling of current atmospheric CO(2) affects the production of a suite of atmospherically important marine trace gases. Two CO(2) treatments were used during a mesocosm CO(2) perturbation experiment in a Norwegian fjord (present day: approximately 380 ppmv and year 2100: approximately 750 ppmv), and phytoplankton blooms were stimulated by the addition of nutrients. Seawater trace gas concentrations were monitored over the growth and decline of the blooms, revealing that concentrations of methyl iodide and dimethylsulfide were significantly reduced under high CO(2.) Additionally, large reductions in concentrations of other iodocarbons were observed. The response of bromocarbons to high CO(2) was less clear cut. Further research is now required to understand how ocean acidification might impact on global marine trace gas fluxes and how these impacts might feed through to changes in the earth's future climate and atmospheric chemistry.

  6. Ocean acidification bends the mermaid's wineglass.

    PubMed

    Newcomb, Laura A; Milazzo, Marco; Hall-Spencer, Jason M; Carrington, Emily

    2015-09-01

    Ocean acidification lowers the saturation state of calcium carbonate, decreasing net calcification and compromising the skeletons of organisms such as corals, molluscs and algae. These calcified structures can protect organisms from predation and improve access to light, nutrients and dispersive currents. While some species (such as urchins, corals and mussels) survive with decreased calcification, they can suffer from inferior mechanical performance. Here, we used cantilever beam theory to test the hypothesis that decreased calcification would impair the mechanical performance of the green alga Acetabularia acetabulum along a CO₂ gradient created by volcanic seeps off Vulcano, Italy. Calcification and mechanical properties declined as calcium carbonate saturation fell; algae at 2283 µatm CO₂ were 32% less calcified, 40% less stiff and 40% droopier. Moreover, calcification was not a linear proxy for mechanical performance; stem stiffness decreased exponentially with reduced calcification. Although calcifying organisms can tolerate high CO₂ conditions, even subtle changes in calcification can cause dramatic changes in skeletal performance, which may in turn affect key biotic and abiotic interactions.

  7. Ocean acidification bends the mermaid's wineglass

    PubMed Central

    Newcomb, Laura A.; Milazzo, Marco; Hall-Spencer, Jason M.; Carrington, Emily

    2015-01-01

    Ocean acidification lowers the saturation state of calcium carbonate, decreasing net calcification and compromising the skeletons of organisms such as corals, molluscs and algae. These calcified structures can protect organisms from predation and improve access to light, nutrients and dispersive currents. While some species (such as urchins, corals and mussels) survive with decreased calcification, they can suffer from inferior mechanical performance. Here, we used cantilever beam theory to test the hypothesis that decreased calcification would impair the mechanical performance of the green alga Acetabularia acetabulum along a CO2 gradient created by volcanic seeps off Vulcano, Italy. Calcification and mechanical properties declined as calcium carbonate saturation fell; algae at 2283 µatm CO2 were 32% less calcified, 40% less stiff and 40% droopier. Moreover, calcification was not a linear proxy for mechanical performance; stem stiffness decreased exponentially with reduced calcification. Although calcifying organisms can tolerate high CO2 conditions, even subtle changes in calcification can cause dramatic changes in skeletal performance, which may in turn affect key biotic and abiotic interactions. PMID:26562936

  8. Exercise Device Would Exert Selectable Constant Resistance

    NASA Technical Reports Server (NTRS)

    Smith, Damon C.

    2003-01-01

    An apparatus called the resistive exercise device (RED) has been proposed to satisfy a requirement for exercise equipment aboard the International Space Station (ISS) that could passively exert a selectable constant load on both the outward and return strokes. The RED could be used alone; alternatively, the RED could be used in combination with another apparatus called the treadmill with vibration isolation and stabilization (TVIS), in which case the combination would be called the subject load device (SLD). The basic RED would be a passive device, but it could incorporate an electric motor to provide eccentric augmentation (augmentation to make the load during inward movement greater than the load during outward movement). The RED concept represents a unique approach to providing a constant but selectable resistive load for exercise for the maintenance and development of muscles. Going beyond the original ISS application, the RED could be used on Earth as resistive weight training equipment. The advantage of the RED over conventional weight-lifting equipment is that it could be made portable and lightweight.

  9. Negative radiation pressure exerted on kinks

    SciTech Connect

    Forgacs, Peter; Lukacs, Arpad; Romanczukiewicz, Tomasz

    2008-06-15

    The interaction of a kink and a monochromatic plane wave in one dimensional scalar field theories is studied. It is shown that in a large class of models the radiation pressure exerted on the kink is negative, i.e. the kink is pulled towards the source of the radiation. This effect has been observed by numerical simulations in the {phi}{sup 4} model, and it is explained by a perturbative calculation assuming that the amplitude of the incoming wave is small. Quite importantly the effect is shown to be robust against small perturbations of the {phi}{sup 4} model. In the sine-Gordon (SG) model the time-averaged radiation pressure acting on the kink turns out to be zero. The results of the perturbative computations in the SG model are shown to be in full agreement with an analytical solution corresponding to the superposition of a SG kink with a cnoidal wave. It is also demonstrated that the acceleration of the kink satisfies Newton's law.

  10. Extracellular calmodulin regulates growth and cAMP-mediated chemotaxis in Dictyostelium discoideum

    SciTech Connect

    O'Day, Danton H.; Huber, Robert J.; Suarez, Andres

    2012-09-07

    Highlights: Black-Right-Pointing-Pointer Extracellular calmodulin is present throughout growth and development in Dictyostelium. Black-Right-Pointing-Pointer Extracellular calmodulin localizes within the ECM during development. Black-Right-Pointing-Pointer Extracellular calmodulin inhibits cell proliferation and increases chemotaxis. Black-Right-Pointing-Pointer Extracellular calmodulin exists in eukaryotic microbes. Black-Right-Pointing-Pointer Extracellular calmodulin may be functionally as important as intracellular calmodulin. -- Abstract: The existence of extracellular calmodulin (CaM) has had a long and controversial history. CaM is a ubiquitous calcium-binding protein that has been found in every eukaryotic cell system. Calcium-free apo-CaM and Ca{sup 2+}/CaM exert their effects by binding to and regulating the activity of CaM-binding proteins (CaMBPs). Most of the research done to date on CaM and its CaMBPs has focused on their intracellular functions. The presence of extracellular CaM is well established in a number of plants where it functions in proliferation, cell wall regeneration, gene regulation and germination. While CaM has been detected extracellularly in several animal species, including frog, rat, rabbit and human, its extracellular localization and functions are less well established. In contrast the study of extracellular CaM in eukaryotic microbes remains to be done. Here we show that CaM is constitutively expressed and secreted throughout asexual development in Dictyostelium where the presence of extracellular CaM dose-dependently inhibits cell proliferation but increases cAMP mediated chemotaxis. During development, extracellular CaM localizes within the slime sheath where it coexists with at least one CaMBP, the matricellular CaM-binding protein CyrA. Coupled with previous research, this work provides direct evidence for the existence of extracellular CaM in the Dictyostelium and provides insight into its functions in this model amoebozoan.

  11. Making recombinant extracellular matrix proteins.

    PubMed

    Ruggiero, Florence; Koch, Manuel

    2008-05-01

    A variety of approaches to understand extracellular matrix protein structure and function require production of recombinant proteins. Moreover, the expression of heterologous extracellular matrix proteins, in particular collagens, using the recombinant technology is of major interest to the biomedical industry. Although extracellular matrix proteins are large, modular and often multimeric, most of them have been successfully produced in various expression systems. This review provides important factors, including the design of the construct, the cloning strategies, the expression vectors, the transfection method and the host cell systems, to consider in choosing a reliable and cost-effective way to make recombinant extracellular matrix proteins. Advantages and drawbacks of each system have been appraised. Protocols that may ease efficient recombinant production of extracellular matrix are described. Emphasis is placed on the recombinant collagen production. Members of the collagen superfamily exhibit specific structural features and generally require complex post-translational modifications to retain full biological activity that make more arduous their recombinant production.

  12. Ocean Acidification: Adaptive Challenge or Extinction Threat?

    NASA Astrophysics Data System (ADS)

    Caldeira, K.

    2012-12-01

    these small scale experiments the potential for adaptation in ecological or evolutionary time. The current evidence points to ocean acidification being catastrophic for at least some organisms and ecosystems (e.g., possibly coral reefs) and likely to lead to the extinction of at least some species. On the other hand, for many organisms and ecosystems (e.g., perhaps some open ocean fish-dominated ecosystems), ocean acidification may represent little more than a minor adaptive challenge. Science can help us to understand the risks, even if some central questions will of necessity remain unanswered. Hopefully, CO2 emissions will be curtailed, and we will never find out which of the more pessimistic or more optimistic projections were correct.

  13. Individual and population-level responses to ocean acidification

    PubMed Central

    Harvey, Ben P.; McKeown, Niall J.; Rastrick, Samuel P. S.; Bertolini, Camilla; Foggo, Andy; Graham, Helen; Hall-Spencer, Jason M.; Milazzo, Marco; Shaw, Paul W.; Small, Daniel P.; Moore, Pippa J.

    2016-01-01

    Ocean acidification is predicted to have detrimental effects on many marine organisms and ecological processes. Despite growing evidence for direct impacts on specific species, few studies have simultaneously considered the effects of ocean acidification on individuals (e.g. consequences for energy budgets and resource partitioning) and population level demographic processes. Here we show that ocean acidification increases energetic demands on gastropods resulting in altered energy allocation, i.e. reduced shell size but increased body mass. When scaled up to the population level, long-term exposure to ocean acidification altered population demography, with evidence of a reduction in the proportion of females in the population and genetic signatures of increased variance in reproductive success among individuals. Such increased variance enhances levels of short-term genetic drift which is predicted to inhibit adaptation. Our study indicates that even against a background of high gene flow, ocean acidification is driving individual- and population-level changes that will impact eco-evolutionary trajectories. PMID:26822220

  14. Individual and population-level responses to ocean acidification.

    PubMed

    Harvey, Ben P; McKeown, Niall J; Rastrick, Samuel P S; Bertolini, Camilla; Foggo, Andy; Graham, Helen; Hall-Spencer, Jason M; Milazzo, Marco; Shaw, Paul W; Small, Daniel P; Moore, Pippa J

    2016-01-29

    Ocean acidification is predicted to have detrimental effects on many marine organisms and ecological processes. Despite growing evidence for direct impacts on specific species, few studies have simultaneously considered the effects of ocean acidification on individuals (e.g. consequences for energy budgets and resource partitioning) and population level demographic processes. Here we show that ocean acidification increases energetic demands on gastropods resulting in altered energy allocation, i.e. reduced shell size but increased body mass. When scaled up to the population level, long-term exposure to ocean acidification altered population demography, with evidence of a reduction in the proportion of females in the population and genetic signatures of increased variance in reproductive success among individuals. Such increased variance enhances levels of short-term genetic drift which is predicted to inhibit adaptation. Our study indicates that even against a background of high gene flow, ocean acidification is driving individual- and population-level changes that will impact eco-evolutionary trajectories.

  15. Paleoecological Investigation of Recent Lake Acidification (PIRLA), 1983--1985

    SciTech Connect

    Charles, D.F.; Whitehead, D.R. )

    1989-10-01

    The Paleoecological Investigation of Recent Lake Acidification'' (PIRLA) project, funded by the Electric Power Research Institute, is a broadly interdisciplinary paleoecological study of recent lake acidification. Approximately ten lakes are being studied in each of four low alkalinity regions in North America that are currently receiving acid deposition. The areas are the Adirondack Mountains (NY), northern New England, northern Great Lakes Region, and northern Florida. Sediment cores are being analyzed for diatom and chrysophyte remains to reconstruct acidification histories, including magnitude, rate, and timing of pH and alkalinity changes. Cores are dated using lead-210 and pollen and charcoal. Other sediment analyses include metals, sulfur, soot, and polycyclic aromatic hydrocarbons (PAH). These provide information on lake acidification histories, and the relative roles of natural acidification processes, watershed disturbance, and atmospheric deposition of strong acids. This interim report contains seven papers representing the status of project research as of March 1985. Results support the hypothesis that diatom and chrysophyte sediment stratigraphies can be used to determine the extent of past variations in the pH levels of lakes.

  16. Acidification of forest soil in Russia: From 1893 to present

    SciTech Connect

    Lapenis, A.G.; Lawrence, G.B.; Andreev, A.A.; Bobrov, A.A.; Torn, M.S.; Harden, J.W.

    2003-01-02

    It is commonly believed that fine-textured soils developed on carbonate parent material are well buffered from possible acidification. There are no data, however, that document resistance of such soils to acidic deposition exposure on a timescale longer than 30-40 years. In this paper, we report on directly testing the long-term buffering capacity of nineteenth century forest soils developed on calcareous silt loam. In a chemical analysis comparing archived soils with modern soils collected from the same locations similar to 100 years later, we found varying degrees of forest-soil acidification in the taiga and forest steppe regions. Land-use history, increases in precipitation, and acidic deposition were contributing factors in acidification. The acidification of forest soil was documented through decreases in soil pH and changes in concentrations of exchangeable calcium and aluminum, which corresponded with changes in communities of soil microfauna. Although acidification was found at all three analyzed locations, the trends in soil chemistry were most pronounced where the highest loading of acidic deposition had taken place.

  17. Acidification of forest soil in Russia: From 1893 to present

    USGS Publications Warehouse

    Lapenis, A.G.; Lawrence, G.B.; Andreev, A.A.; Bobrov, A.A.; Torn, M.S.; Harden, J.W.

    2004-01-01

    It is commonly believed that fine-textured soils developed on carbonate parent material are well buffered from possible acidification. There are no data, however, that document resistance of such soils to acidic deposition exposure on a timescale longer than 30-40 years. In this paper, we report on directly testing the long-term buffering capacity of nineteenth century forest soils developed on calcareous silt loam. In a chemical analysis comparing archived soils with modern soils collected from the same locations ???100 years later, we found varying degrees of forest-soil acidification in the taiga and forest steppe regions. Land-use history, increases in precipitation, and acidic deposition were contributing factors in acidification. The acidification of forest soil was documented through decreases in soil pH and changes in concentrations of exchangeable calcium and aluminum, which corresponded with changes in communities of soil microfauna. Although acidification was found at all three analyzed locations, the trends in soil chemistry were most pronounced where the highest loading of acidic deposition had taken place. Copyright 2004 by the American Geophysical Union.

  18. Status of soil acidification in North America

    USGS Publications Warehouse

    Fenn, M.E.; Huntington, T.G.; Mclaughlin, S.B.; Eagar, C.; Gomez, A.; Cook, R.B.

    2006-01-01

    Forest soil acidification and depletion of nutrient cations have been reported for several forested regions in North America, predominantly in the eastern United States, including the northeast and in the central Appalachians, but also in parts of southeastern Canada and the southern U.S. Continuing regional inputs of nitrogen and sulfur are of concern because of leaching of base cations, increased availability of soil Al, and the accumulation and ultimate transmission of acidity from forest soils to streams. Losses of calcium from forest soils and forested watersheds have now been documented as a sensitive early indicator and a functionally significant response to acid deposition for a wide range of forest soils in North America. For red spruce, a clear link has been established between acidic deposition, alterations in calcium and aluminum supplies and increased sensitivity to winter injury. Cation depletion appears to contribute to sugar maple decline on some soils, specifically the high mortality rates observed in northern Pennsylvania over the last decade. While responses to liming have not been systematically examined in North America, in a study in Pennsylvania, restoring basic cations through liming increased basal area growth of sugar maple and levels of calcium and magnesium in soil and foliage. In the San Bernardino Mountains in southern California near the west coast, the pH of the A horizon has declined by at least 2 pH units (to pH 4.0-4.3) over the past 30 years, with no detrimental effects on bole growth; presumably, because of the Mediterranean climate, base cation pools are still high and not limiting for plant growth.

  19. Biological responses of sharks to ocean acidification.

    PubMed

    Rosa, Rui; Rummer, Jodie L; Munday, Philip L

    2017-03-01

    Sharks play a key role in the structure of marine food webs, but are facing major threats due to overfishing and habitat degradation. Although sharks are also assumed to be at relatively high risk from climate change due to a low intrinsic rate of population growth and slow rates of evolution, ocean acidification (OA) has not, until recently, been considered a direct threat. New studies have been evaluating the potential effects of end-of-century elevated CO2 levels on sharks and their relatives' early development, physiology and behaviour. Here, we review those findings and use a meta-analysis approach to quantify the overall direction and magnitude of biological responses to OA in the species of sharks that have been investigated to date. While embryo survival and development time are mostly unaffected by elevated CO2, there are clear effects on body condition, growth, aerobic potential and behaviour (e.g. lateralization, hunting and prey detection). Furthermore, studies to date suggest that the effects of OA could be as substantial as those due to warming in some species. A major limitation is that all past studies have involved relatively sedentary, benthic sharks that are capable of buccal ventilation-no studies have investigated pelagic sharks that depend on ram ventilation. Future research should focus on species with different life strategies (e.g. pelagic, ram ventilators), climate zones (e.g. polar regions), habitats (e.g. open ocean), and distinct phases of ontogeny in order to fully predict how OA and climate change will impact higher-order predators and therefore marine ecosystem dynamics.

  20. Extracellular RNA in aging.

    PubMed

    Dluzen, Douglas F; Noren Hooten, Nicole; Evans, Michele K

    2017-03-01

    Since the discovery of extracellular RNA (exRNA) in circulation and other bodily fluids, there has been considerable effort to catalog and assess whether exRNAs can be used as markers for health and disease. A variety of exRNA species have been identified including messenger RNA and noncoding RNA such as microRNA (miRNA), small nucleolar RNA, transfer RNA, and long noncoding RNA. Age-related changes in exRNA abundance have been observed, and it is likely that some of these transcripts play a role in aging. In this review, we summarize the current state of exRNA profiling in various body fluids and discuss age-related changes in exRNA abundance that have been identified in humans and other model organisms. miRNAs, in particular, are a major focus of current research and we will highlight and discuss the potential role that specific miRNAs might play in age-related phenotypes and disease. We will also review challenges facing this emerging field and various strategies that can be used for the validation and future use of exRNAs as markers of aging and age-related disease. WIREs RNA 2017, 8:e1385. doi: 10.1002/wrna.1385 For further resources related to this article, please visit the WIREs website.

  1. Acidification of the HUMEX lake; effects on epilimnetic pools and fluxes of carbon

    SciTech Connect

    Hessen, D.O. )

    1992-01-01

    The paper presents data on carbon budgets during the first year of acidification of one half of humic lake Skjervatjern. Dissolved organic carbon (DOC), mainly allochthonous humus, ranged from 2 to 12 mg C L[sup [minus]1], with an average of 6 to 7 mg C for both the acidified and the reference basin. The minimum values occurred during winter when ground temperature fell below zero. Average dissolved inorganic carbon (DIC) was near 500 [mu]g C L[sup [minus]1] in the surface layers, but increased to more than 2 mg close to the bottom. Epilimnetic particulate organic carbon (POC) was also close to 500 [mu]g C L[sup [minus]1], of which more than 3/4 was detritus, while bacteria, phyto-, and macrozooplankton made up approximately 100, 50, and 20-40 [mu]g C L[sup [minus]1], respectively. Major flows were sedimentation, respiration, and discharge. Acidification gave no clearcut effects on the major pools and fluxes of carbon, which were mainly governed by climatic and hydrological events. There were, however, pronounced differences in biotic pools and biologically mediated carbon fluxes, with more unstable conditions in the acidified basin. Primary production and phytoplankton biomass increased in the acidified basin relative to the control. Zooplankton biomass had a strong midsummer peak, followed by a sudden collapse of the dominant species, Holopedium gibberum, in the acidified part. As a consequence, zooplankton community grazing also dropped. Grazing did, however, not exert an efficient control with phytoplankton biomass. Preliminary data indicated decreased respiration and increased sedimentation in the acidified part. A closer follow-up of these processes will be performed during the two upcoming years in order to separate transitional and more permanent changes in carbon metabolism. 19 refs., 6 figs., 1 tab.

  2. The Effect of Exertion on Heart Rate and Rating of Perceived Exertion in Acutely Concussed Individuals

    PubMed Central

    Hinds, Andrea; Leddy, John; Freitas, Michael; Czuczman, Natalie; Willer, Barry

    2016-01-01

    Objective Research suggests that one physiological effect of concussion is a disruption in regulation of autonomic nervous system control that affects the balance between parasympathetic and sympathetic output. While changes in heart rate after concussion have been observed, the nature of the heart rate change during progressive exercise has not been well evaluated in acutely symptomatic patients. Additionally, little is known about the relationship between HR and RPE in this population. Methods We compared changes in heart rate and perceived effort during graded treadmill exertion in recently concussed patients to elucidate the effect of brain injury on cardiovascular response to exercise. Resting HR, HR on exercise initiation, and changes in HR and RPE during the Buffalo Concussion Treadmill Test (BCTT) were compared on two test visits: When patients were symptomatic (acute) and after recovery. Results were compared with the test-retest results obtained from a control group consisting of healthy, non-concussed individuals. Results Patients had a significantly lower HR at onset of exercise when acutely concussed as compared to when recovered and reported greater perceived exertion at every exercise intensity level when symptomatic, despite exercising at lower workloads, than when recovered. Sympathetic response to increased exertion was not affected by concussion - HR increased in response to exercise at a comparable rate in both tests. These differences observed in response to exercise between the first BCTT and follow-up evaluation in initially concussed patients were not present in non-concussed individuals. Conclusion Our results suggest that during the acute phase after concussion, acutely concussed patients demonstrated an impaired ability to shift from parasympathetic to sympathetic control over heart rate at the onset of exercise. Changes in the autonomic nervous system after concussion may be more complex than previously reported. Continued evaluation of

  3. Physiological impacts of elevated carbon dioxide and ocean acidification on fish.

    PubMed

    Heuer, Rachael M; Grosell, Martin

    2014-11-01

    Most fish studied to date efficiently compensate for a hypercapnic acid-base disturbance; however, many recent studies examining the effects of ocean acidification on fish have documented impacts at CO2 levels predicted to occur before the end of this century. Notable impacts on neurosensory and behavioral endpoints, otolith growth, mitochondrial function, and metabolic rate demonstrate an unexpected sensitivity to current-day and near-future CO2 levels. Most explanations for these effects seem to center on increases in Pco2 and HCO3- that occur in the body during pH compensation for acid-base balance; however, few studies have measured these parameters at environmentally relevant CO2 levels or directly related them to reported negative endpoints. This compensatory response is well documented, but noted variation in dynamic regulation of acid-base transport pathways across species, exposure levels, and exposure duration suggests that multiple strategies may be utilized to cope with hypercapnia. Understanding this regulation and changes in ion gradients in extracellular and intracellular compartments during CO2 exposure could provide a basis for predicting sensitivity and explaining interspecies variation. Based on analysis of the existing literature, the present review presents a clear message that ocean acidification may cause significant effects on fish across multiple physiological systems, suggesting that pH compensation does not necessarily confer tolerance as downstream consequences and tradeoffs occur. It remains difficult to assess if acclimation responses during abrupt CO2 exposures will translate to fitness impacts over longer timescales. Nonetheless, identifying mechanisms and processes that may be subject to selective pressure could be one of many important components of assessing adaptive capacity.

  4. Combined ocean acidification and low temperature stressors cause coral mortality

    NASA Astrophysics Data System (ADS)

    Kavousi, Javid; Parkinson, John Everett; Nakamura, Takashi

    2016-09-01

    Oceans are predicted to become more acidic and experience more temperature variability—both hot and cold—as climate changes. Ocean acidification negatively impacts reef-building corals, especially when interacting with other stressors such as elevated temperature. However, the effects of combined acidification and low temperature stress have yet to be assessed. Here, we exposed nubbins of the scleractinian coral Montipora digitata to ecologically relevant acidic, cold, or combined stress for 2 weeks. Coral nubbins exhibited 100% survival in isolated acidic and cold treatments, but ~30% mortality under combined conditions. These results provide further evidence that coupled stressors have an interactive effect on coral physiology, and reveal that corals in colder environments are also susceptible to the deleterious impacts of coupled ocean acidification and thermal stress.

  5. Pirla 2 project: Regional assessment of lake acidification trends

    SciTech Connect

    Charles, D.F.; Smol, J.P.

    1990-01-01

    PIRLA II (Paleoecological Investigation of Recent Lake Acidification) is the first paleolimnological study designed to make statistically based regional population estimates of lake acidification. It is also the first project in which only tops and bottoms of cores are analyzed so that a large number of lakes can be studied. The PIRLA II project consists of several components that are designed to address specific questions and are integrally related to several other projects. PIRLA II builds on the foundation laid by PIRLA I; together they make up one of the largest paleolimnological projects in terms of number of lakes investigated (over 120 lakes analyzed stratigraphically). PIRLA has made and will continue to make important contributions to the understanding of lake acidification and to the development of the field of paleolimnology.

  6. Digestion in sea urchin larvae impaired under ocean acidification

    NASA Astrophysics Data System (ADS)

    Stumpp, Meike; Hu, Marian; Casties, Isabel; Saborowski, Reinhard; Bleich, Markus; Melzner, Frank; Dupont, Sam

    2013-12-01

    Larval stages are considered as the weakest link when a species is exposed to challenging environmental changes. Reduced rates of growth and development in larval stages of calcifying invertebrates in response to ocean acidification might be caused by energetic limitations. So far no information exists on how ocean acidification affects digestive processes in marine larval stages. Here we reveal alkaline (~pH 9.5) conditions in the stomach of sea urchin larvae. Larvae exposed to decreased seawater pH suffer from a drop in gastric pH, which directly translates into decreased digestive efficiencies and triggers compensatory feeding. These results suggest that larval digestion represents a critical process in the context of ocean acidification, which has been overlooked so far.

  7. Ocean acidification and the Permo-Triassic mass extinction

    NASA Astrophysics Data System (ADS)

    Clarkson, M. O.; Kasemann, S. A.; Wood, R. A.; Lenton, T. M.; Daines, S. J.; Richoz, S.; Ohnemueller, F.; Meixner, A.; Poulton, S. W.; Tipper, E. T.

    2015-04-01

    Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

  8. Ocean acidification and the Permo-Triassic mass extinction.

    PubMed

    Clarkson, M O; Kasemann, S A; Wood, R A; Lenton, T M; Daines, S J; Richoz, S; Ohnemueller, F; Meixner, A; Poulton, S W; Tipper, E T

    2015-04-10

    Ocean acidification triggered by Siberian Trap volcanism was a possible kill mechanism for the Permo-Triassic Boundary mass extinction, but direct evidence for an acidification event is lacking. We present a high-resolution seawater pH record across this interval, using boron isotope data combined with a quantitative modeling approach. In the latest Permian, increased ocean alkalinity primed the Earth system with a low level of atmospheric CO2 and a high ocean buffering capacity. The first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota.

  9. Challenges in assessing biological recovery from acidification in Swedish lakes.

    PubMed

    Holmgren, Kerstin

    2014-01-01

    Since the 1980s, Swedish lakes have in general become less acidified. Assessment of biological recovery is, however, hampered by poor pre-acidification data, confounding effects of climate change, and few lakes with annual sampling of fish and other organisms. Only three critically acidified, but non-limed, lakes had two decades of fish monitoring. The lakes had not yet recovered to pre-industrial chemical targets. Fish had low species richness compared to other organism groups. Roach (Rutilus rutilus) and/or European perch (Perca fluviatilis) were the dominant fish species, and the acid-sensitive roach had been lost from one of the lakes. Calcium decreased, possibly approaching pre-acidification concentrations, but exceeded minimum levels needed to sustain some Daphnia species. High or increasing levels of total organic carbon, likely due to reduced acidification and climate change, might influence the biological communities in unexpected ways, for example, facilitating more frequent occurrence of the invasive algae Gonyostomum semen.

  10. Acidification of Earth: An assessment across mechanisms and scales

    USGS Publications Warehouse

    Rice, Karen; Herman, Janet S.

    2012-01-01

    In this review article, anthropogenic activities that cause acidification of Earth’s air, waters, and soils are examined. Although there are many mechanisms of acidification, the focus is on the major ones, including emissions from combustion of fossil fuels and smelting of ores, mining of coal and metal ores, and application of nitrogen fertilizer to soils, by elucidating the underlying biogeochemical reactions as well as assessing the magnitude of the effects. These widespread activities have resulted in (1) increased CO2concentration in the atmosphere that acidifies the oceans; (2) acidic atmospheric deposition that acidifies soils and bodies of freshwater; (3) acid mine drainage that acidifies bodies of freshwater and groundwaters; and (4) nitrification that acidifies soils. Although natural geochemical reactions of mineral weathering and ion exchange work to buffer acidification, the slow reaction rates or the limited abundance of reactant phases are overwhelmed by the onslaught of anthropogenic acid loading. Relatively recent modifications of resource extraction and usage in some regions of the world have begun to ameliorate local acidification, but expanding use of resources in other regions is causing environmental acidification in previously unnoticed places. World maps of coal consumption, Cu mining and smelting, and N fertilizer application are presented to demonstrate the complex spatial heterogeneity of resource consumption as well as the overlap in acidifying potential derived from distinctly different phenomena. Projected population increase by country over the next four decades indicates areas with the highest potential for acidification, so enabling anticipation and planning to offset or mitigate the deleterious environmental effects associated with these global shifts in the consumption of energy, mineral, and food resources.

  11. Effects of seawater acidification on a coral reef meiofauna community

    NASA Astrophysics Data System (ADS)

    Sarmento, V. C.; Souza, T. P.; Esteves, A. M.; Santos, P. J. P.

    2015-09-01

    Despite the increasing risk that ocean acidification will modify benthic communities, great uncertainty remains about how this impact will affect the lower trophic levels, such as members of the meiofauna. A mesocosm experiment was conducted to investigate the effects of water acidification on a phytal meiofauna community from a coral reef. Community samples collected from the coral reef subtidal zone (Recife de Fora Municipal Marine Park, Porto Seguro, Bahia, Brazil), using artificial substrate units, were exposed to a control pH (ambient seawater) and to three levels of seawater acidification (pH reductions of 0.3, 0.6, and 0.9 units below ambient) and collected after 15 and 30 d. After 30 d of exposure, major changes in the structure of the meiofauna community were observed in response to reduced pH. The major meiofauna groups showed divergent responses to acidification. Harpacticoida and Polychaeta densities did not show significant differences due to pH. Nematoda, Ostracoda, Turbellaria, and Tardigrada exhibited their highest densities in low-pH treatments (especially at the pH reduction of 0.6 units, pH 7.5), while harpacticoid nauplii were strongly negatively affected by low pH. This community-based mesocosm study supports previous suggestions that ocean acidification induces important changes in the structure of marine benthic communities. Considering the importance of meiofauna in the food web of coral reef ecosystems, the results presented here demonstrate that the trophic functioning of coral reefs is seriously threatened by ocean acidification.

  12. Experimental ocean acidification alters the allocation of metabolic energy

    PubMed Central

    Pan, T.-C. Francis; Applebaum, Scott L.; Manahan, Donal T.

    2015-01-01

    Energy is required to maintain physiological homeostasis in response to environmental change. Although responses to environmental stressors frequently are assumed to involve high metabolic costs, the biochemical bases of actual energy demands are rarely quantified. We studied the impact of a near-future scenario of ocean acidification [800 µatm partial pressure of CO2 (pCO2)] during the development and growth of an important model organism in developmental and environmental biology, the sea urchin Strongylocentrotus purpuratus. Size, metabolic rate, biochemical content, and gene expression were not different in larvae growing under control and seawater acidification treatments. Measurements limited to those levels of biological analysis did not reveal the biochemical mechanisms of response to ocean acidification that occurred at the cellular level. In vivo rates of protein synthesis and ion transport increased ∼50% under acidification. Importantly, the in vivo physiological increases in ion transport were not predicted from total enzyme activity or gene expression. Under acidification, the increased rates of protein synthesis and ion transport that were sustained in growing larvae collectively accounted for the majority of available ATP (84%). In contrast, embryos and prefeeding and unfed larvae in control treatments allocated on average only 40% of ATP to these same two processes. Understanding the biochemical strategies for accommodating increases in metabolic energy demand and their biological limitations can serve as a quantitative basis for assessing sublethal effects of global change. Variation in the ability to allocate ATP differentially among essential functions may be a key basis of resilience to ocean acidification and other compounding environmental stressors. PMID:25825763

  13. Coral Calcification Across a Natural Gradient in Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Cohen, A. L.; Brainard, R. E.; Young, C.; Shamberger, K. E.; McCorkle, D. C.; Feely, R. A.; Mcleod, E.; Cantin, N.; Rose, K.; Lohmann, G. P.

    2011-12-01

    Much of our understanding of the impact of ocean acidification on coral calcification comes from laboratory manipulation experiments in which corals are reared under a range of seawater pH and aragonite saturation states (μar) equivalent to those projected for the next hundred years. In general, experiments show a consistently negative impact of acidification on coral calcification, leading to predictions of mass coral reef extinctions by dissolution as natural rates of carbonate erosion exceed the rates at which corals and other reef calcifiers can replace it. The tropical oceans provide a natural laboratory within which to test hypotheses about the longer term impact and adaptive potential of corals to acidification of the reef environment. Here we report results of a study in which 3-D CT scan and imaging techniques were used to quantify annual rates of calcification by conspecifics at 12 reefs sites spanning a natural gradient in ocean acidification. In situ μar calculated from alkalinity and DIC measurements of reef seawater ranged from less than 2.7 on an eastern Pacific Reef to greater than 4.0 in the central Red Sea. No correlation between μar and calcification was observed across this range. Corals living on low μar reefs appear to be calcifying as fast, sometimes faster than conspecifics living on high μar reefs. We used total lipid and tissue thickness to index the energetic status of colonies collected at each of our study sites. Our results support the hypothesis that energetics plays a key role in the coral calcification response to ocean acidification. Indeed, the true impact of acidification on coral reefs will likely be felt as temperatures rise and the ocean becomes more stratified, depleting coral energetic reserves through bleaching and reduced nutrient delivery to oceanic reefs.

  14. Experimental ocean acidification alters the allocation of metabolic energy.

    PubMed

    Pan, T-C Francis; Applebaum, Scott L; Manahan, Donal T

    2015-04-14

    Energy is required to maintain physiological homeostasis in response to environmental change. Although responses to environmental stressors frequently are assumed to involve high metabolic costs, the biochemical bases of actual energy demands are rarely quantified. We studied the impact of a near-future scenario of ocean acidification [800 µatm partial pressure of CO2 (pCO2)] during the development and growth of an important model organism in developmental and environmental biology, the sea urchin Strongylocentrotus purpuratus. Size, metabolic rate, biochemical content, and gene expression were not different in larvae growing under control and seawater acidification treatments. Measurements limited to those levels of biological analysis did not reveal the biochemical mechanisms of response to ocean acidification that occurred at the cellular level. In vivo rates of protein synthesis and ion transport increased ∼50% under acidification. Importantly, the in vivo physiological increases in ion transport were not predicted from total enzyme activity or gene expression. Under acidification, the increased rates of protein synthesis and ion transport that were sustained in growing larvae collectively accounted for the majority of available ATP (84%). In contrast, embryos and prefeeding and unfed larvae in control treatments allocated on average only 40% of ATP to these same two processes. Understanding the biochemical strategies for accommodating increases in metabolic energy demand and their biological limitations can serve as a quantitative basis for assessing sublethal effects of global change. Variation in the ability to allocate ATP differentially among essential functions may be a key basis of resilience to ocean acidification and other compounding environmental stressors.

  15. Extracellular DNA and histones: double-edged swords in immunothrombosis.

    PubMed

    Gould, T J; Lysov, Z; Liaw, P C

    2015-06-01

    The existence of extracellular DNA in human plasma, also known as cell-free DNA (cfDNA), was first described in the 1940s. In recent years, there has been a resurgence of interest in the functional significance of cfDNA, particularly in the context of neutrophil extracellular traps (NETs). cfDNA and histones are key components of NETs that aid in the host response to infection and inflammation. However, cfDNA and histones may also exert harmful effects by triggering coagulation, inflammation, and cell death and by impairing fibrinolysis. In this article, we will review the pathologic nature of cfDNA and histones in macrovascular and microvascular thrombosis, including venous thromboembolism, cancer, sepsis, and trauma. We will also discuss the prognostic value of cfDNA and histones in these disease states. Understanding the molecular and cellular pathways regulated by cfDNA and histones may provide novel insights to prevent pathological thrombus formation and vascular occlusion.

  16. Nitrogen deposition contributes to soil acidification in tropical ecosystems.

    PubMed

    Lu, Xiankai; Mao, Qinggong; Gilliam, Frank S; Luo, Yiqi; Mo, Jiangming

    2014-12-01

    Elevated anthropogenic nitrogen (N) deposition has greatly altered terrestrial ecosystem functioning, threatening ecosystem health via acidification and eutrophication in temperate and boreal forests across the northern hemisphere. However, response of forest soil acidification to N deposition has been less studied in humid tropics compared to other forest types. This study was designed to explore impacts of long-term N deposition on soil acidification processes in tropical forests. We have established a long-term N-deposition experiment in an N-rich lowland tropical forest of Southern China since 2002 with N addition as NH4 NO3 of 0, 50, 100 and 150 kg N ha(-1)  yr(-1) . We measured soil acidification status and element leaching in soil drainage solution after 6-year N addition. Results showed that our study site has been experiencing serious soil acidification and was quite acid-sensitive showing high acidification (pH(H2O) <4.0), negative water-extracted acid neutralizing capacity (ANC) and low base saturation (BS,< 8%) throughout soil profiles. Long-term N addition significantly accelerated soil acidification, leading to depleted base cations and decreased BS, and further lowered ANC. However, N addition did not alter exchangeable Al(3+) , but increased cation exchange capacity (CEC). Nitrogen addition-induced increase in SOC is suggested to contribute to both higher CEC and lower pH. We further found that increased N addition greatly decreased soil solution pH at 20 cm depth, but not at 40 cm. Furthermore, there was no evidence that Al(3+) was leaching out from the deeper soils. These unique responses in tropical climate likely resulted from: exchangeable H(+) dominating changes of soil cation pool, an exhausted base cation pool, N-addition stimulating SOC production, and N saturation. Our results suggest that long-term N addition can contribute measurably to soil acidification, and that shortage of Ca and Mg should receive more attention than soil

  17. Another dimension to calcium signaling: a look at extracellular calcium.

    PubMed

    Hofer, Aldebaran M

    2005-03-01

    Cell biologists know the calcium ion best as a vital intracellular second messenger that governs countless cellular functions. However, the recent identification of cell-surface detectors for extracellular Ca(2+) has prompted consideration of whether Ca(2+) also functions as a signaling molecule in the extracellular milieu. The cast of Ca(2+) sensors includes the well-characterized extracellular-Ca(2+)-sensing receptor, a G-protein-coupled receptor originally isolated from the parathyroid gland. In addition, other receptors, channels and membrane proteins, such as gap junction hemichannels, metabotropic glutamate receptors, HERG K(+) channels and the receptor Notch, are all sensitive to external [Ca(2+)] fluctuations. A recently cloned Ca(2+) sensor (CAS) in Arabidopsis extends this concept to the plant kingdom. Emerging evidence indicates that [Ca(2+)] in the local microenvironment outside the cell undergoes alterations potentially sufficient to exert biological actions through these sensor proteins. The extracellular space might therefore constitute a much more dynamic Ca(2+) signaling compartment than previously appreciated.

  18. Ciliary Extracellular Vesicles: Txt Msg Organelles.

    PubMed

    Wang, Juan; Barr, Maureen M

    2016-04-01

    Cilia are sensory organelles that protrude from cell surfaces to monitor the surrounding environment. In addition to its role as sensory receiver, the cilium also releases extracellular vesicles (EVs). The release of sub-micron sized EVs is a conserved form of intercellular communication used by all three kingdoms of life. These extracellular organelles play important roles in both short and long range signaling between donor and target cells and may coordinate systemic responses within an organism in normal and diseased states. EV shedding from ciliated cells and EV-cilia interactions are evolutionarily conserved phenomena, yet remarkably little is known about the relationship between the cilia and EVs and the fundamental biology of EVs. Studies in the model organisms Chlamydomonas and Caenorhabditis elegans have begun to shed light on ciliary EVs. Chlamydomonas EVs are shed from tips of flagella and are bioactive. Caenorhabditis elegans EVs are shed and released by ciliated sensory neurons in an intraflagellar transport-dependent manner. Caenorhabditis elegans EVs play a role in modulating animal-to-animal communication, and this EV bioactivity is dependent on EV cargo content. Some ciliary pathologies, or ciliopathies, are associated with abnormal EV shedding or with abnormal cilia-EV interactions. Until the 21st century, both cilia and EVs were ignored as vestigial or cellular junk. As research interest in these two organelles continues to gain momentum, we envision a new field of cell biology emerging. Here, we propose that the cilium is a dedicated organelle for EV biogenesis and EV reception. We will also discuss possible mechanisms by which EVs exert bioactivity and explain how what is learned in model organisms regarding EV biogenesis and function may provide insight to human ciliopathies.

  19. Ciliary extracellular vesicles: Txt msg orgnlls

    PubMed Central

    Wang, Juan; Barr, Maureen M.

    2016-01-01

    Cilia are sensory organelles that protrude from cell surfaces to monitor the surrounding environment. In addition to its role as sensory receiver, the cilium also releases extracellular vesicles (EVs). The release of sub-micron sized EVs is a conserved form of intercellular communication used by all three kingdoms of life. These extracellular organelles play important roles in both short and long range signaling between donor and target cells and may coordinate systemic responses within an organism in normal and diseased states. EV shedding from ciliated cells and EV-cilia interactions are evolutionarily conserved phenomena, yet remarkably little is known about the relationship between the cilia and EVs and the fundamental biology of EVs. Studies in the model organisms Chlamydomonas and C. elegans have begun to shed light on ciliary EVs. Chlamydomonas EVs are shed from tips of flagella and are bioactive. C. elegans EVs are shed and released by ciliated sensory neurons in an intraflagellar transport (IFT)-dependent manner. C. elegans EVs play a role in modulating animal-to-animal communication, and this EV bioactivity is dependent on EV cargo content. Some ciliary pathologies, or ciliopathies, are associated with abnormal EV shedding or with abnormal cilia-EV interactions, suggest the cilium may be an important organelle as an EV donor or as an EV target. Until the past few decades, both cilia and EVs were ignored as vestigial or cellular junk. As research interest in these two organelles continues to gain momentum, we envision a new field of cell biology emerging. Here, we propose that the cilium is a dedicated organelle for EV biogenesis and EV reception. We will also discuss possible mechanisms by which EVs exert bioactivity and explain how what is learned in model organisms regarding EV biogenesis and function may provide insight to human ciliopathies. PMID:26983828

  20. Extracellular matrix and wound healing.

    PubMed

    Maquart, F X; Monboisse, J C

    2014-04-01

    Extracellular matrix has been known for a long time as an architectural support for the tissues. Many recent data, however, have shown that extracellular matrix macromolecules (collagens, elastin, glycosaminoglycans, proteoglycans and connective tissue glycoproteins) are able to regulate many important cell functions, such as proliferation, migration, protein synthesis or degradation, apoptosis, etc., making them able to play an important role in the wound repair process. Not only the intact macromolecules but some of their specific domains, that we called "Matrikines", are also able to regulate many cell activities. In this article, we will summarize main findings showing the effects of extracellular matrix macromolecules and matrikines on connective tissue and epithelial cells, particularly in skin, and their potential implication in the wound healing process. These examples show that extracellular matrix macromolecules or some of their specific domains may play a major role in wound healing. Better knowledge of these interactions may suggest new therapeutic targets in wound healing defects.

  1. Effects of hyperglycemia on lonidamine-induced acidification and de-energization of human melanoma xenografts and sensitization to melphalan

    PubMed Central

    Nath, Kavindra; Nelson, David S.; Heitjan, Daniel F.; Zhou, Rong; Leeper, Dennis B.; Glickson, Jerry D.

    2015-01-01

    We seek to exploit the natural tendency of melanomas and other tumors to convert glucose to lactate as a method for selective intracellular acidification of cancer cells and for potentiating the activity of N-mustard antineoplastic agents. We performed this study to evaluate whether induction of hyperglycemia (26 mM) could enhance the effects of lonidamine (LND, 100 mg/kg; i.p.) on inducing intracellular acidification, bioenergetic decline and potentiation of the activity of melphalan (LPAM) against DB-1 melanoma xenografts in mice. Intracellular pH (pHi), extracellular pH (pHe) and bioenergetics (βNTP/Pi) were reduced by 0.7 units (p<0.001), 0.3 units (p>0.05) and 51.4% (p<0.05), respectively. Therapeutic response to LPAM (7.5 mg/kg; i.v.) + LND (100 mg/kg; i.p.) was reduced by about a factor of 3 under hyperglycemic conditions compared to normoglycemia, producing a growth delay of 7.76 d (tumor doubling time = 5.31 d, cell kill = 64%) compared to LND alone of 1.70 d and LPAM alone of 0.29 d. Under normoglycemic conditions LND plus LPAM produced a growth delay of 17.75 d, corresponding to a cell kill of 90 % at the same doses for each of these agents. The decrease in tumor cell kill under hyperglycemic conditions correlates with an increase in tumor ATP levels resulting from increased glycolytic activity. However, hyperglycemia substantially increases lactic acid production in tumors by a factor of ~6 (p<0.05), but hyperglycemia did not increase the effects of LND on acidification of the tumor most likely because of the strong buffering action of carbon dioxide (the pKa of carbonic acid is 6.4). Therefore, this study demonstrates that addition of glucose during treatment with LND diminishes the activity of this agent. PMID:25702942

  2. Protective mechanism of sodium molybdate against the acute toxicity of cadmium in rats. II. Prevention of cytoplasmic acidification.

    PubMed

    Koizumi, T; Yokota, T; Fukuchi, M; Tatsumoto, H; Yamane, Y

    1991-10-01

    In order to clarify the protective mechanism of sodium molybdate against the acute toxicity of cadmium chloride in rat, the effect of in vivo sodium molybdate pretreatment on the cytotoxic action of cadmium in isolated hepatocytes was studied. The cytosolic pH of hepatocytes isolated from untreated rats immediately decreased with incubation in either neutral Hank's balanced salt solution (HBS), pH 7.4, containing 5 microM cadmium chloride minimum or acidic HBS (pH 7.1, 6.8, 6.5, and 6.2). The presence of 5 microM cadmium in HBS adjusted to pH 7.1 aggravated cytosolic acidification induced by the acidic medium alone. Cell viability of hepatocytes incubated in HBS at pH 6.2 was significantly reduced as compared to that of control cells in HBS at pH 7.4, but the presence of cadmium in the acidic HBS had no aggravating action against such a toxic action of the acidic medium although cellular uptake of the metal in the medium increased, as compared to that in HBS at pH 7.4. Molybdenum pretreatment alleviated cytoplasmic acidification induced by the treatment with HBS at pH 7.4 or 7.1 containing cadmium or by extracellular acid load without cadmium. This pretreatment also prevented the loss of cell viability induced by the treatment with HBS at pH 6.2 but could not attenuate that when cadmium was present in the medium. These facts suggest that molybdenum pretreatment alleviated the acute toxicity of cadmium in rat by preventing cytoplasmic acidification caused by the harmful metal.

  3. Using Ratings of Perceived Exertion in Physical Education

    ERIC Educational Resources Information Center

    Lagally, Kristen M.

    2013-01-01

    Ratings of perceived exertion have been shown to be a valid method of monitoring physical activity intensity for both adults and children. As such, this subjective method may serve as an alternative to objective measurements for assessing students' performance on national standards 2 and 4. The OMNI-Child perceived exertion scales were…

  4. Exertional Rhabdomyolysis: What Is It and Why Should We Care?

    ERIC Educational Resources Information Center

    Thomas, David Q.; Carlson, Kelli A.; Marzano, Amy; Garrahy, Deborah

    2012-01-01

    Exertional rhabdomyolysis gained increased attention recently when 13 football players from the University of Iowa developed this condition after an especially demanding practice session and were hospitalized. Exertional rhabdomyolysis may lead to severe kidney stress, kidney failure, and even sudden death. Anyone who does physical exercise at a…

  5. 20 CFR 220.135 - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... limitations. (a) General. The claimant's impairment(s) and related symptoms, such as pain, may cause... as pain, are exertional, nonexertional, or a combination of both. (b) Exertional limitations. When... pain, affect only the claimant's ability to meet the strength demands of jobs (sitting,...

  6. 20 CFR 220.135 - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... limitations. (a) General. The claimant's impairment(s) and related symptoms, such as pain, may cause... as pain, are exertional, nonexertional, or a combination of both. (b) Exertional limitations. When... pain, affect only the claimant's ability to meet the strength demands of jobs (sitting,...

  7. 20 CFR 220.135 - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... limitations. (a) General. The claimant's impairment(s) and related symptoms, such as pain, may cause... as pain, are exertional, nonexertional, or a combination of both. (b) Exertional limitations. When... pain, affect only the claimant's ability to meet the strength demands of jobs (sitting,...

  8. 20 CFR 220.135 - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... limitations. (a) General. The claimant's impairment(s) and related symptoms, such as pain, may cause... as pain, are exertional, nonexertional, or a combination of both. (b) Exertional limitations. When... pain, affect only the claimant's ability to meet the strength demands of jobs (sitting,...

  9. Force Exertion Capacity Measurements in Haptic Virtual Environments

    ERIC Educational Resources Information Center

    Munih, Marko; Bardorfer, Ales; Ceru, Bojan; Bajd, Tadej; Zupan, Anton

    2010-01-01

    An objective test for evaluating functional status of the upper limbs (ULs) in patients with muscular distrophy (MD) is presented. The method allows for quantitative assessment of the UL functional state with an emphasis on force exertion capacity. The experimental measurement setup and the methodology for the assessment of maximal exertable force…

  10. Effects of near-future ocean acidification, fishing, and marine protection on a temperate coastal ecosystem.

    PubMed

    Cornwall, Christopher E; Eddy, Tyler D

    2015-02-01

    Understanding ecosystem responses to global and local anthropogenic impacts is paramount to predicting future ecosystem states. We used an ecosystem modeling approach to investigate the independent and cumulative effects of fishing, marine protection, and ocean acidification on a coastal ecosystem. To quantify the effects of ocean acidification at the ecosystem level, we used information from the peer-reviewed literature on the effects of ocean acidification. Using an Ecopath with Ecosim ecosystem model for the Wellington south coast, including the Taputeranga Marine Reserve (MR), New Zealand, we predicted ecosystem responses under 4 scenarios: ocean acidification + fishing; ocean acidification + MR (no fishing); no ocean acidification + fishing; no ocean acidification + MR for the year 2050. Fishing had a larger effect on trophic group biomasses and trophic structure than ocean acidification, whereas the effects of ocean acidification were only large in the absence of fishing. Mortality by fishing had large, negative effects on trophic group biomasses. These effects were similar regardless of the presence of ocean acidification. Ocean acidification was predicted to indirectly benefit certain species in the MR scenario. This was because lobster (Jasus edwardsii) only recovered to 58% of the MR biomass in the ocean acidification + MR scenario, a situation that benefited the trophic groups lobsters prey on. Most trophic groups responded antagonistically to the interactive effects of ocean acidification and marine protection (46%; reduced response); however, many groups responded synergistically (33%; amplified response). Conservation and fisheries management strategies need to account for the reduced recovery potential of some exploited species under ocean acidification, nonadditive interactions of multiple factors, and indirect responses of species to ocean acidification caused by declines in calcareous predators.

  11. Exertional myopathy in whooping cranes (Grus americana) with prognostic guidelines.

    PubMed

    Hanley, Christopher S; Thomas, Nancy J; Paul-Murphy, Joanne; Hartup, Barry K

    2005-09-01

    Exertional myopathy developed in three whooping cranes (Grus americana) secondary to routine capture, handling, and trauma. Presumptive diagnosis of exertional myopathy was based on history of recent capture or trauma, clinical signs, and elevation of aspartate aminotransferase, alanine aminotransferase, creatine kinase, lactate dehydrogenase, and serum potassium. Treatments were attempted in each case, but ultimately were not successful. Gross and microscopic lesions at necropsy confirmed the diagnosis in each case, with the leg musculature most severely affected. Guidelines for determining prognosis of exertional myopathy in cranes have been included based on the analysis of these cases and others in the literature. As treatment is largely unrewarding, prevention remains the key in controlling exertional myopathy. Identification of predisposing factors and proper handling, immobilization, and transportation techniques can help prevent development of exertional myopathy in cranes.

  12. Exertional myopathy in whooping cranes (Grus americana) with prognostic guidlelines

    USGS Publications Warehouse

    Hanley, C.S.; Thomas, N.J.; Paul-Murphy, P.; Hartup, B.K.

    2005-01-01

    Exertional myopathy developed in three whooping cranes (Grus americana) secondary to routine capture, handling, and trauma. Presumptive diagnosis of exertional myopathy was based on history of recent capture or trauma, clinical signs, and elevation of aspartate aminotransferase, alanine aminotransferase, creatine kinase, lactate dehydrogenase, and serum potassium. Treatments were attempted in each case, but ultimately were not successful. Gross and microscopic lesions at necropsy confirmed the diagnosis in each case, with the leg musculature most severely affected. Guidelines for determining prognosis of exertional myopathy in cranes have been included based on the analysis of these cases and others in the literature. As treatment is largely unrewarding, prevention remains the key in controlling exertional myopathy. Identification of predisposing factors and proper handling, immobilization, and transportation techniques can help prevent development of exertional myopathy in cranes.

  13. Acute exertional anterior compartment syndrome in an adolescent female.

    PubMed

    Fehlandt, A; Micheli, L

    1995-01-01

    Acute compartment syndromes usually occur as a complication of major trauma. While the chronic exertional anterior tibial compartment syndrome is well described in the sports medicine literature, reports of acute tibial compartment syndromes due to physical exertion, or repetitive microtrauma, are rare. The case of an adolescent female who developed an acute anterior compartment syndrome from running in a soccer game is described in this report. Failure to recognize the onset of an acute exertional compartment syndrome may lead to treatment delay and serious complications. Whereas the chronic exertional anterior compartment syndrome is characterized by pain that diminishes with the cessation of exercise, the onset of the acute exertional anterior compartment syndrome is heralded by pain that continues, or increases, after exercise has stopped. Compartment pressure measurement confirms the clinical diagnosis and helps guide treatment. True compartment syndromes require urgent fasciotomy.

  14. Urbanization in China drives soil acidification of Pinus massoniana forests.

    PubMed

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-09-24

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10 cm (for ammonium N(NH4+(-N)), P < 0.05; for nitrate N(NO3-(-N)), P < 0.01) and 10-20 cm (for NO3-(-N), P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0-10 cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment.

  15. Acidification of subsurface coastal waters enhanced by eutrophication

    EPA Science Inventory

    Uptake of fossil-fuel carbon dioxide (CO2) from the atmosphere has acidified the surface ocean by ~0.1 pH units and driven down the carbonate saturation state. Ocean acidification is a threat to marine ecosystems and may alter key biogeochemical cycles. Coastal oceans have also b...

  16. Ocean acidification: One potential driver of phosphorus eutrophication.

    PubMed

    Ge, Changzi; Chai, Yanchao; Wang, Haiqing; Kan, Manman

    2017-02-15

    Harmful algal blooms which may be limited by phosphorus outbreak increases currently and ocean acidification worsens presently, which implies that ocean acidification might lead to phosphorus eutrophication. To verify the hypothesis, oxic sediments were exposed to seawater with different pH 30days. If pH was 8.1 and 7.7, the total phosphorus (TP) content in sediments was 1.52±0.50 and 1.29±0.40mg/g. The inorganic phosphorus (IP) content in sediments exposed to seawater with pH8.1 and 7.7 was 1.39±0.10 and 1.06±0.20mg/g, respectively. The exchangeable phosphorus (Ex-P) content in sediments was 4.40±0.45 and 2.82±0.15μg/g, if seawater pH was 8.1 and 7.7. Ex-P and IP contents in oxic sediments were reduced by ocean acidification significantly (p<5%). The reduced phosphorus in sediments diffused into water, which implied that ocean acidification was one potential facilitator of phosphorus eutrophication in oxic conditions.

  17. Urbanization in China drives soil acidification of Pinus massoniana forests

    NASA Astrophysics Data System (ADS)

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-09-01

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0-10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0-10 cm (for ammonium N (-N), P < 0.05 for nitrate N (-N), P < 0.01) and 10-20 cm (for -N, P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0-10 cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment.

  18. Seagrass ecophysiological performance under ocean warming and acidification.

    PubMed

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R; Rosa, Inês C; Grilo, Tiago F; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  19. Millennial-scale ocean acidification and late Quaternary

    SciTech Connect

    Riding, Dr Robert E; Liang, Liyuan; Braga, Dr Juan Carlos

    2014-01-01

    Ocean acidification by atmospheric carbon dioxide has increased almost continuously since the last glacial maximum (LGM), 21 000 years ago. It is expected to impair tropical reef development, but effects on reefs at the present day and in the recent past have proved difficult to evaluate. We present evidence that acidification has already significantly reduced the formation of calcified bacterial crusts in tropical reefs. Unlike major reef builders such as coralline algae and corals that more closely control their calcification, bacterial calcification is very sensitive to ambient changes in carbonate chemistry. Bacterial crusts in reef cavities have declined in thickness over the past 14 000 years with largest reduction occurring 12 000 10 000 years ago. We interpret this as an early effect of deglacial ocean acidification on reef calcification and infer that similar crusts were likely to have been thicker when seawater carbonate saturation was increased during earlier glacial intervals, and thinner during interglacials. These changes in crust thickness could have substantially affected reef development over glacial cycles, as rigid crusts significantly strengthen framework and their reduction would have increased the susceptibility of reefs to biological and physical erosion. Bacterial crust decline reveals previously unrecognized millennial-scale acidification effects on tropical reefs. This directs attention to the role of crusts in reef formation and the ability of bioinduced calcification to reflect changes in seawater chemistry. It also provides a long-term context for assessing anticipated anthropogenic effects.

  20. Ocean acidification alters predator behaviour and reduces predation rate.

    PubMed

    Watson, Sue-Ann; Fields, Jennifer B; Munday, Philip L

    2017-02-01

    Ocean acidification poses a range of threats to marine invertebrates; however, the emerging and likely widespread effects of rising carbon dioxide (CO2) levels on marine invertebrate behaviour are still little understood. Here, we show that ocean acidification alters and impairs key ecological behaviours of the predatory cone snail Conus marmoreus Projected near-future seawater CO2 levels (975 µatm) increased activity in this coral reef molluscivore more than threefold (from less than 4 to more than 12 mm min(-1)) and decreased the time spent buried to less than one-third when compared with the present-day control conditions (390 µatm). Despite increasing activity, elevated CO2 reduced predation rate during predator-prey interactions with control-treated humpbacked conch, Gibberulus gibberulus gibbosus; 60% of control predators successfully captured and consumed their prey, compared with only 10% of elevated CO2 predators. The alteration of key ecological behaviours of predatory invertebrates by near-future ocean acidification could have potentially far-reaching implications for predator-prey interactions and trophic dynamics in marine ecosystems. Combined evidence that the behaviours of both species in this predator-prey relationship are altered by elevated CO2 suggests food web interactions and ecosystem structure will become increasingly difficult to predict as ocean acidification advances over coming decades.

  1. Adaptive evolution of a key phytoplankton species to ocean acidification

    NASA Astrophysics Data System (ADS)

    Lohbeck, Kai T.; Riebesell, Ulf; Reusch, Thorsten B. H.

    2012-05-01

    Ocean acidification, the drop in seawater pH associated with the ongoing enrichment of marine waters with carbon dioxide from fossil fuel burning, may seriously impair marine calcifying organisms. Our present understanding of the sensitivity of marine life to ocean acidification is based primarily on short-term experiments, in which organisms are exposed to increased concentrations of CO2. However, phytoplankton species with short generation times, in particular, may be able to respond to environmental alterations through adaptive evolution. Here, we examine the ability of the world's single most important calcifying organism, the coccolithophore Emiliania huxleyi, to evolve in response to ocean acidification in two 500-generation selection experiments. Specifically, we exposed E. huxleyi populations founded by single or multiple clones to increased concentrations of CO2. Around 500 asexual generations later we assessed their fitness. Compared with populations kept at ambient CO2 partial pressure, those selected at increased partial pressure exhibited higher growth rates, in both the single- and multiclone experiment, when tested under ocean acidification conditions. Calcification was partly restored: rates were lower under increased CO2 conditions in all cultures, but were up to 50% higher in adapted compared with non-adapted cultures. We suggest that contemporary evolution could help to maintain the functionality of microbial processes at the base of marine food webs in the face of global change.

  2. Cephalopod Susceptibility to Asphyxiation via Ocean Incalescence, Deoxygenation, and Acidification.

    PubMed

    Seibel, Brad A

    2016-11-01

    Squids are powerful swimmers with high metabolic rates despite constrained oxygen uptake and transport. They have evolved novel physiological strategies for survival in extreme environments that provide insight into their susceptibility to asphyxiation under anthropogenic ocean incalescence (warming), deoxygenation, and acidification. Plasticity of ecological and physiological traits, in conjunction with vertical and latitudinal mobility, may explain their evolutionary persistence and ensure their future survival.

  3. Predicting Effects of Coastal Acidification on Marine Bivalve Populations

    EPA Science Inventory

    The partial pressure of carbon dioxide (pCO2) is increasing in the oceans and causing changes in seawater pH commonly described as ocean or coastal acidification. It is now well-established that, when reproduced in laboratory experiments, these increases in pCO2 can reduce survi...

  4. Ocean acidification alters fish populations indirectly through habitat modification

    NASA Astrophysics Data System (ADS)

    Nagelkerken, Ivan; Russell, Bayden D.; Gillanders, Bronwyn M.; Connell, Sean D.

    2016-01-01

    Ocean ecosystems are predicted to lose biodiversity and productivity from increasing ocean acidification. Although laboratory experiments reveal negative effects of acidification on the behaviour and performance of species, more comprehensive predictions have been hampered by a lack of in situ studies that incorporate the complexity of interactions between species and their environment. We studied CO2 vents from both Northern and Southern hemispheres, using such natural laboratories to investigate the effect of ocean acidification on plant-animal associations embedded within all their natural complexity. Although we substantiate simple direct effects of reduced predator-avoidance behaviour by fishes, as observed in laboratory experiments, we here show that this negative effect is naturally dampened when fish reside in shelter-rich habitats. Importantly, elevated CO2 drove strong increases in the abundance of some fish species through major habitat shifts, associated increases in resources such as habitat and prey availability, and reduced predator abundances. The indirect effects of acidification via resource and predator alterations may have far-reaching consequences for population abundances, and its study provides a framework for a more comprehensive understanding of increasing CO2 emissions as a driver of ecological change.

  5. Multivariate analysis of parameters related to lake acidification in Quebec

    SciTech Connect

    Bobee, B.; Lachance, M.

    1984-08-01

    Physico-chemical data from 234 lakes were collected during the spring and summer of 1980 by the Quebec Ministry of the Environment, the Quebec Ministry of Recreation, Hunting and Fishing and the Canadian Wildlife Service. A statistical method, based on the joint use of factorial correspondence analysis and cluster analysis, was applied to these data to obtain a general picture of the spatial variability of a member of physico-chemical parameters related to the sensitivity or acidification of lakewaters. This method was first applied to the entire Quebec territory, and showed that the part of Quebec lying on the Canadian shield is especially vulnerable to acidification. The method also showed that the southwestern portion of this area of Quebec was more substantially affected by acid fallout. A detailed study of spatial variability over the shield area revealed the existence of greater spatial heterogeneity. More precisely, it was possible to pinpoint zones which are highly vulnerable to acid precipitation and zones whose lakes show clear signs of acidification resulting from such precipitation. These two statistical analyses led to a first general diagnosis on lake acidification in Quebec. They contribute to the rationalization of data acquisition in Quebec by delimitating zones where network density needs to be increased.

  6. Seagrass ecophysiological performance under ocean warming and acidification

    PubMed Central

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-01-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming. PMID:28145531

  7. Urbanization in China drives soil acidification of Pinus massoniana forests

    PubMed Central

    Huang, Juan; Zhang, Wei; Mo, Jiangming; Wang, Shizhong; Liu, Juxiu; Chen, Hao

    2015-01-01

    Soil acidification instead of alkalization has become a new environmental issue caused by urbanization. However, it remains unclear the characters and main contributors of this acidification. We investigated the effects of an urbanization gradient on soil acidity of Pinus massoniana forests in Pearl River Delta, South China. The soil pH of pine forests at 20-cm depth had significantly positive linear correlations with the distance from the urban core of Guangzhou. Soil pH reduced by 0.44 unit at the 0–10 cm layer in urbanized areas compared to that in non-urbanized areas. Nitrogen deposition, mean annual temperature and mean annual precipitation were key factors influencing soil acidification based on a principal component analysis. Nitrogen deposition showed significant linear relationships with soil pH at the 0–10 cm (for ammonium N (-N), P < 0.05; for nitrate N (-N), P < 0.01) and 10–20 cm (for -N, P < 0.05) layers. However, there was no significant loss of exchangeable non-acidic cations along the urbanization gradient, instead their levels were higher in urban than in urban/suburban area at the 0–10 cm layer. Our results suggested N deposition particularly under the climate of high temperature and rainfall, greatly contributed to a significant soil acidification occurred in the urbanized environment. PMID:26400019

  8. Responses of pink salmon to CO2-induced aquatic acidification

    NASA Astrophysics Data System (ADS)

    Ou, Michelle; Hamilton, Trevor J.; Eom, Junho; Lyall, Emily M.; Gallup, Joshua; Jiang, Amy; Lee, Jason; Close, David A.; Yun, Sang-Seon; Brauner, Colin J.

    2015-10-01

    Ocean acidification negatively affects many marine species and is predicted to cause widespread changes to marine ecosystems. Similarly, freshwater ecosystems may potentially be affected by climate-change-related acidification; however, this has received far less attention. Freshwater fish represent 40% of all fishes, and salmon, which rear and spawn in freshwater, are of immense ecosystem, economical and cultural importance. In this study, we investigate the impacts of CO2-induced acidification during the development of pink salmon, in freshwater and following early seawater entry. At this critical and sensitive life stage, we show dose-dependent reductions in growth, yolk-to-tissue conversion and maximal O2 uptake capacity; as well as significant alterations in olfactory responses, anti-predator behaviour and anxiety under projected future increases in CO2 levels. These data indicate that future populations of pink salmon may be at risk without mitigation and highlight the need for further studies on the impact of CO2-induced acidification on freshwater systems.

  9. Seagrass ecophysiological performance under ocean warming and acidification

    NASA Astrophysics Data System (ADS)

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  10. Mitigating Local Causes of Ocean Acidification with Existing Laws

    EPA Science Inventory

    The oceans continue to absorb CO2 in step with the increasing atmospheric concentration of CO2. The dissolved CO2 reacts with seawater to form carbonic acid (H2CO3) and liberate hydrogen ions, causing the pH of the oceans to decrease. Ocean acidification is thus an inevitable a...

  11. Lysosome acidification by photoactivated nanoparticles restores autophagy under lipotoxicity

    PubMed Central

    Trudeau, Kyle M.; Colby, Aaron H.; Zeng, Jialiu; Las, Guy; Feng, Jiazuo H.; Shirihai, Orian S.

    2016-01-01

    In pancreatic β-cells, liver hepatocytes, and cardiomyocytes, chronic exposure to high levels of fatty acids (lipotoxicity) inhibits autophagic flux and concomitantly decreases lysosomal acidity. Whether impaired lysosomal acidification is causally inhibiting autophagic flux and cellular functions could not, up to the present, be determined because of the lack of an approach to modify lysosomal acidity. To address this question, lysosome-localizing nanoparticles are described that, upon UV photoactivation, enable controlled acidification of impaired lysosomes. The photoactivatable, acidifying nanoparticles (paNPs) demonstrate lysosomal uptake in INS1 and mouse β-cells. Photoactivation of paNPs in fatty acid–treated INS1 cells enhances lysosomal acidity and function while decreasing p62 and LC3-II levels, indicating rescue of autophagic flux upon acute lysosomal acidification. Furthermore, paNPs improve glucose-stimulated insulin secretion that is reduced under lipotoxicity in INS1 cells and mouse islets. These results establish a causative role for impaired lysosomal acidification in the deregulation of autophagy and β-cell function under lipotoxicity. PMID:27377248

  12. Cellular acidification as a new approach to cancer treatment and to the understanding and therapeutics of neurodegenerative diseases.

    PubMed

    Harguindey, Salvador; Stanciu, Daniel; Devesa, Jesús; Alfarouk, Khalid; Cardone, Rosa Angela; Polo Orozco, Julian David; Devesa, Pablo; Rauch, Cyril; Orive, Gorka; Anitua, Eduardo; Roger, Sébastien; Reshkin, Stephan J

    2017-02-11

    During the last few years, the understanding of the dysregulated hydrogen ion dynamics and reversed proton gradient of cancer cells has resulted in a new and integral pH-centric paradigm in oncology, a translational model embracing from cancer etiopathogenesis to treatment. The abnormalities of intracellular alkalinization along with extracellular acidification of all types of solid tumors and leukemic cells have never been described in any other disease and now appear to be a specific hallmark of malignancy. As a consequence of this intracellular acid-base homeostatic failure, the attempt to induce cellular acidification using proton transport inhibitors and other intracellular acidifiers of different origins is becoming a new therapeutic concept and selective target of cancer treatment, both as a metabolic mediator of apoptosis and in the overcoming of multiple drug resistance (MDR). Importantly, there is increasing data showing that different ion channels contribute to mediate significant aspects of cancer pH regulation and etiopathogenesis. Finally, we discuss the extension of this new pH-centric oncological paradigm into the opposite metabolic and homeostatic acid-base situation found in human neurodegenerative diseases (HNDDs), which opens novel concepts in the prevention and treatment of HNDDs through the utilization of a cohort of neural and non-neural derived hormones and human growth factors.

  13. Acute Acidification of Stratum Corneum Membrane Domains Using Polyhydroxyl Acids Improves Lipid Processing and Inhibits Degradation of Corneodesmosomes

    PubMed Central

    Hachem, Jean-Pierre; Roelandt, Truus; Schürer, Nanna; Pu, Xu; Fluhr, Joachim; Giddelo, Christina; Man, Mao-Qiang; Crumrine, Debra; Roseeuw, Diane; Feingold, Kenneth R.; Mauro, Theodora; Elias, Peter M.

    2010-01-01

    Neutralization of the normally acidic stratum corneum (SC) has deleterious consequences for permeability barrier homeostasis and SC integrity/cohesion attributable to serine proteases (SPs) activation leading to deactivation/degradation of lipid-processing enzymes and corneodesmosomes (CD). As an elevated pH compromises SC structure and function, we asked here whether SC hyperacidification would improve the structure and function. We lowered the pH of mouse SC using two polyhydroxyl acids (PHA), lactobionic acid (LBA), or gluconolactone (GL). Applications of the PHA reduced the pH at all levels of SC of hairless mouse, with further selective acidification of SC membrane domains, as shown by fluorescence lifetime imaging. Hyperacidification improved permeability barrier homeostasis, attributable to increased activities of two key membrane-localized, ceramide-generating hydrolytic enzymes (β-glucocerebrosidase and acidic sphingomyelinase), which correlated with accelerated extracellular maturation of SC lamellar membranes. Hyperacidification generated “supernormal” SC integrity/cohesion, attributable to an SP-dependent decreased degradation of desmoglein-1 (DSG1) and the induction of DSG3 expression in lower SC. As SC hyperacidification improves the structure and function, even of normal epidermis, these studies lay the groundwork for an assessment of the potential utility of SC acidification as a therapeutic strategy for inflammatory dermatoses, characterized by abnormalities in barrier function, cohesion, and surface pH. PMID:19741713

  14. Acid soils of western Serbia and their further acidification

    NASA Astrophysics Data System (ADS)

    Mrvic, Vesna

    2010-05-01

    Acid soils cause many unfavorable soil characteristics from the plant nutrition point of view. Because of increased soil acidity the violation of buffering soil properties due to leaching of Ca and Mg ions is taking place that also can cause soil physical degradation via peptization of colloids. Together with increasing of soil acidity the content of mobile Al increases that can be toxic for plants. Easily available nutritive elements transforms into hardly avaialble froms. The process of deactivation is especially expressed for phosphorous that under such conditions forms non-soluble compounds with sesqui-oxides. From the other hand the higher solubility of some microelements (Zn and B) can cause their accelerated leaching from root zone and therefore, result in their deficiency for plant nutrition. Dangerous and toxic matters transforms into easly-available forms for plants, especially, Cd and Ni under the lower soil pH. The studied soil occupies 36675 hectare in the municipality of Krupan in Serbia, and are characterized with very unfavorable chemical properties: 26% of the territory belongs to the cathegory of very acidic, and 44 % belongs to the cathegory of acidic. The results showed that the soil of the territory of Krupan is limited for agricultural land use due to their high acidity. Beside the statement of negative soil properties determined by acidity, there is a necessity for determination of soil sensitivity for acidification processes toward soil protection from ecological aspect and its prevention from further acidification. Based on such data and categorization of soils it is possible to undertake proper measures for soil protection and melioration of the most endangered soil cover, where the economic aspect of these measures is very important. One of the methods of soil classification based on sensitivity for acidification classification the determination of soil categories is based on the values of soil CEC and pH in water. By combination of these

  15. Ocean acidification alters temperature and salinity preferences in larval fish.

    PubMed

    Pistevos, Jennifer C A; Nagelkerken, Ivan; Rossi, Tullio; Connell, Sean D

    2017-02-01

    Ocean acidification alters the way in which animals perceive and respond to their world by affecting a variety of senses such as audition, olfaction, vision and pH sensing. Marine species rely on other senses as well, but we know little of how these might be affected by ocean acidification. We tested whether ocean acidification can alter the preference for physicochemical cues used for dispersal between ocean and estuarine environments. We experimentally assessed the behavioural response of a larval fish (Lates calcarifer) to elevated temperature and reduced salinity, including estuarine water of multiple cues for detecting settlement habitat. Larval fish raised under elevated CO2 concentrations were attracted by warmer water, but temperature had no effect on fish raised in contemporary CO2 concentrations. In contrast, contemporary larvae were deterred by lower salinity water, where CO2-treated fish showed no such response. Natural estuarine water-of higher temperature, lower salinity, and containing estuarine olfactory cues-was only preferred by fish treated under forecasted high CO2 conditions. We show for the first time that attraction by larval fish towards physicochemical cues can be altered by ocean acidification. Such alterations to perception and evaluation of environmental cues during the critical process of dispersal can potentially have implications for ensuing recruitment and population replenishment. Our study not only shows that freshwater species that spend part of their life cycle in the ocean might also be affected by ocean acidification, but that behavioural responses towards key physicochemical cues can also be negated through elevated CO2 from human emissions.

  16. Acidification of the Mediterranean Sea from anthropogenic carbon penetration

    NASA Astrophysics Data System (ADS)

    Hassoun, Abed El Rahman; Gemayel, Elissar; Krasakopoulou, Evangelia; Goyet, Catherine; Abboud-Abi Saab, Marie; Guglielmi, Véronique; Touratier, Franck; Falco, Cédric

    2015-08-01

    This study presents an estimation of the anthropogenic CO2 (CANT) concentrations and acidification (ΔpH=pH2013-pHpre-industrial) in the Mediterranean Sea, based upon hydrographic and carbonate chemistry data collected during the May 2013 MedSeA cruise. The concentrations of CANT were calculated using the composite tracer TrOCA. The CANT distribution shows that the most invaded waters (>60 μmol kg-1) are those of the intermediate and deep layers in the Alboran, Liguro- and Algero-Provencal Sub-basins in the Western basin, and in the Adriatic Sub-basin in the Eastern basin. Whereas the areas containing the lowest CANT concentrations are the deep layers of the Eastern basin, especially those of the Ionian Sub-basin, and those of the northern Tyrrhenian Sub-basin in the Western basin. The acidification level in the Mediterranean Sea reflects the excessive increase of atmospheric CO2 and therefore the invasion of the sea by CANT. This acidification varies between -0.055 and -0.156 pH unit and it indicates that all Mediterranean Sea waters are already acidified, especially those of the Western basin where ΔpH is rarely less than -0.1 pH unit. Both CANT concentrations and acidification levels are closely linked to the presence and history of the different water masses in the intermediate and deep layers of the Mediterranean basins. Despite the high acidification levels, both Mediterranean basins are still highly supersaturated in calcium carbonate minerals.

  17. Soil acidification in China: is controlling SO2 emissions enough?

    PubMed

    Zhao, Yu; Duan, Lei; Xing, Jia; Larssen, Thorjorn; Nielsen, Chris P; Hao, Jiming

    2009-11-01

    Facing challenges of increased energy consumption and related regional air pollution, China has been aggressively implementing flue gas desulfurization (FGD) and phasing out small inefficient units in the power sector in order to achieve the national goal of 10% reduction in sulfur dioxide (SO(2)) emissions from 2005 to 2010. In this paper, the effect of these measures on soil acidification is explored. An integrated methodology is used, combining emission inventory data, emission forecasts, air quality modeling, and ecological sensitivities indicated by critical load. National emissions of SO(2), oxides of nitrogen (NO(X)), particulate matter (PM), and ammonia (NH(3)) in 2005 were estimated to be 30.7, 19.6, 31.3, and 16.6 Mt, respectively. Implementation of existing policy will lead to reductions in SO(2) and PM emissions, while those of NO(X) and NH(3) will continue to rise, even under tentatively proposed control measures. In 2005, the critical load for soil acidification caused by sulfur (S) deposition was exceeded in 28% of the country's territory, mainly in eastern and south-central China. The area in exceedance will decrease to 26% and 20% in 2010 and 2020, respectively, given implementation of current plans for emission reductions. However, the exceedance of the critical load for nitrogen (N, combining effects of eutrophication and acidification) will double from 2005 to 2020 due to increased NO(X) and NH(3) emissions. Combining the acidification effects of S and N, the benefits of SO(2) reductions during 2005-2010 will almost be negated by increased N emissions. Therefore abatement of N emissions (NO(X) and NH(3)) and deposition will be a major challenge to China, requiring policy development and technology investments. To mitigate acidification in the future, China needs a multipollutant control strategy that integrates measures to reduce S, N, and PM.

  18. Reversal of ocean acidification enhances net coral reef calcification.

    PubMed

    Albright, Rebecca; Caldeira, Lilian; Hosfelt, Jessica; Kwiatkowski, Lester; Maclaren, Jana K; Mason, Benjamin M; Nebuchina, Yana; Ninokawa, Aaron; Pongratz, Julia; Ricke, Katharine L; Rivlin, Tanya; Schneider, Kenneth; Sesboüé, Marine; Shamberger, Kathryn; Silverman, Jacob; Wolfe, Kennedy; Zhu, Kai; Caldeira, Ken

    2016-03-17

    Approximately one-quarter of the anthropogenic carbon dioxide released into the atmosphere each year is absorbed by the global oceans, causing measurable declines in surface ocean pH, carbonate ion concentration ([CO3(2-)]), and saturation state of carbonate minerals (Ω). This process, referred to as ocean acidification, represents a major threat to marine ecosystems, in particular marine calcifiers such as oysters, crabs, and corals. Laboratory and field studies have shown that calcification rates of many organisms decrease with declining pH, [CO3(2-)], and Ω. Coral reefs are widely regarded as one of the most vulnerable marine ecosystems to ocean acidification, in part because the very architecture of the ecosystem is reliant on carbonate-secreting organisms. Acidification-induced reductions in calcification are projected to shift coral reefs from a state of net accretion to one of net dissolution this century. While retrospective studies show large-scale declines in coral, and community, calcification over recent decades, determining the contribution of ocean acidification to these changes is difficult, if not impossible, owing to the confounding effects of other environmental factors such as temperature. Here we quantify the net calcification response of a coral reef flat to alkalinity enrichment, and show that, when ocean chemistry is restored closer to pre-industrial conditions, net community calcification increases. In providing results from the first seawater chemistry manipulation experiment of a natural coral reef community, we provide evidence that net community calcification is depressed compared with values expected for pre-industrial conditions, indicating that ocean acidification may already be impairing coral reef growth.

  19. Reversal of ocean acidification enhances net coral reef calcification

    NASA Astrophysics Data System (ADS)

    Albright, Rebecca; Caldeira, Lilian; Hosfelt, Jessica; Kwiatkowski, Lester; MacLaren, Jana K.; Mason, Benjamin M.; Nebuchina, Yana; Ninokawa, Aaron; Pongratz, Julia; Ricke, Katharine L.; Rivlin, Tanya; Schneider, Kenneth; Sesboüé, Marine; Shamberger, Kathryn; Silverman, Jacob; Wolfe, Kennedy; Zhu, Kai; Caldeira, Ken

    2016-03-01

    Approximately one-quarter of the anthropogenic carbon dioxide released into the atmosphere each year is absorbed by the global oceans, causing measurable declines in surface ocean pH, carbonate ion concentration ([CO32-]), and saturation state of carbonate minerals (Ω). This process, referred to as ocean acidification, represents a major threat to marine ecosystems, in particular marine calcifiers such as oysters, crabs, and corals. Laboratory and field studies have shown that calcification rates of many organisms decrease with declining pH, [CO32-], and Ω. Coral reefs are widely regarded as one of the most vulnerable marine ecosystems to ocean acidification, in part because the very architecture of the ecosystem is reliant on carbonate-secreting organisms. Acidification-induced reductions in calcification are projected to shift coral reefs from a state of net accretion to one of net dissolution this century. While retrospective studies show large-scale declines in coral, and community, calcification over recent decades, determining the contribution of ocean acidification to these changes is difficult, if not impossible, owing to the confounding effects of other environmental factors such as temperature. Here we quantify the net calcification response of a coral reef flat to alkalinity enrichment, and show that, when ocean chemistry is restored closer to pre-industrial conditions, net community calcification increases. In providing results from the first seawater chemistry manipulation experiment of a natural coral reef community, we provide evidence that net community calcification is depressed compared with values expected for pre-industrial conditions, indicating that ocean acidification may already be impairing coral reef growth.

  20. Extracellular Matrix, a Hard Player in Angiogenesis

    PubMed Central

    Mongiat, Maurizio; Andreuzzi, Eva; Tarticchio, Giulia; Paulitti, Alice

    2016-01-01

    The extracellular matrix (ECM) is a complex network of proteins, glycoproteins, proteoglycans, and polysaccharides. Through multiple interactions with each other and the cell surface receptors, not only the ECM determines the physical and mechanical properties of the tissues, but also profoundly influences cell behavior and many physiological and pathological processes. One of the functions that have been extensively explored is its impingement on angiogenesis. The strong impact of the ECM in this context is both direct and indirect by virtue of its ability to interact and/or store several growth factors and cytokines. The aim of this review is to provide some examples of the complex molecular mechanisms that are elicited by these molecules in promoting or weakening the angiogenic processes. The scenario is intricate, since matrix remodeling often generates fragments displaying opposite effects compared to those exerted by the whole molecules. Thus, the balance will tilt towards angiogenesis or angiostasis depending on the relative expression of pro- or anti-angiogenetic molecules/fragments composing the matrix of a given tissue. One of the vital aspects of this field of research is that, for its endogenous nature, the ECM can be viewed as a reservoir to draw from for the development of new more efficacious therapies to treat angiogenesis-dependent pathologies. PMID:27809279

  1. Relevance of extracellular DNA in rhizosphere

    NASA Astrophysics Data System (ADS)

    Pietramellara, Giacomo; Ascher, Judith; Baraniya, Divyashri; Arfaioli, Paola; Ceccherini, Maria Teresa; Hawes, Martha

    2013-04-01

    One of the most promising areas for future development is the manipulation of the rhizosphere to produce sustainable and efficient agriculture production systems. Using Omics approaches, to define the distinctive features of eDNA systems and structures, will facilitate progress in rhizo-enforcement and biocontrol studies. The relevance of these studies results clear when we consider the plethora of ecological functions in which eDNA is involved. This fraction can be actively extruded by living cells or discharged during cellular lysis and may exert a key role in the stability and variability of the soil bacterial genome, resulting also a source of nitrogen and phosphorus for plants due to the root's capacity to directly uptake short DNA fragments. The adhesive properties of the DNA molecule confer to eDNA the capacity to inhibit or kill pathogenic bacteria by cation limitation induction, and to facilitate formation of biofilm and extracellular traps (ETs), that may protect microorganisms inhabiting biofilm and plant roots against pathogens and allelopathic substances. The ETs are actively extruded by root border cells when they are dispersed in the rhizosphere, conferring to plants the capacity to extend an endogenous pathogen defence system outside the organism. Moreover, eDNA could be involved in rhizoremediation in heavy metal polluted soil acting as a bioflotation reagent.

  2. Extracellular DNA Acidifies Biofilms and Induces Aminoglycoside Resistance in Pseudomonas aeruginosa.

    PubMed

    Wilton, Mike; Charron-Mazenod, Laetitia; Moore, Richard; Lewenza, Shawn

    2015-11-09

    Biofilms consist of surface-adhered bacterial communities encased in an extracellular matrix composed of DNA, exopolysaccharides, and proteins. Extracellular DNA (eDNA) has a structural role in the formation of biofilms, can bind and shield biofilms from aminoglycosides, and induces antimicrobial peptide resistance mechanisms. Here, we provide evidence that eDNA is responsible for the acidification of Pseudomonas aeruginosa planktonic cultures and biofilms. Further, we show that acidic pH and acidification via eDNA constitute a signal that is perceived by P. aeruginosa to induce the expression of genes regulated by the PhoPQ and PmrAB two-component regulatory systems. Planktonic P. aeruginosa cultured in exogenous 0.2% DNA or under acidic conditions demonstrates a 2- to 8-fold increase in aminoglycoside resistance. This resistance phenotype requires the aminoarabinose modification of lipid A and the production of spermidine on the bacterial outer membrane, which likely reduce the entry of aminoglycosides. Interestingly, the additions of the basic amino acid L-arginine and sodium bicarbonate neutralize the pH and restore P. aeruginosa susceptibility to aminoglycosides, even in the presence of eDNA. These data illustrate that the accumulation of eDNA in biofilms and infection sites can acidify the local environment and that acidic pH promotes the P. aeruginosa antibiotic resistance phenotype.

  3. Prior Acute Mental Exertion in Exercise and Sport

    PubMed Central

    Silva-Júnior, Fernando Lopes e; Emanuel, Patrick; Sousa, Jordan; Silva, Matheus; Teixeira, Silmar; Pires, Flávio; Machado, Sérgio; Arias-Carrion, Oscar

    2016-01-01

    Introduction: Mental exertion is a psychophysiological state caused by sustained and prolonged cognitive activity. The understanding of the possible effects of acute mental exertion on physical performance, and their physiological and psychological responses are of great importance for the performance of different occupations, such as military, construction workers, athletes (professional or recreational) or simply practicing regular exercise, since these occupations often combine physical and mental tasks while performing their activities. However, the effects of implementation of a cognitive task on responses to aerobic exercise and sports are poorly understood. Our narrative review aims to provide information on the current research related to the effects of prior acute mental fatigue on physical performance and their physiological and psychological responses associated with exercise and sports. Methods: The literature search was conducted using the databases PubMed, ISI Web of Knowledge and PsycInfo using the following terms and their combinations: “mental exertion”, “mental fatigue”, “mental fatigue and performance”, “mental exertion and sports” “mental exertion and exercise”. Results: We concluded that prior acute mental exertion affects effectively the physiological and psychophysiological responses during the cognitive task, and performance in exercise. Conclusion: Additional studies involving prior acute mental exertion, exercise/sports and physical performance still need to be carried out in order to analyze the physiological, psychophysiological and neurophysiological responses subsequently to acute mental exertion in order to identify cardiovascular factors, psychological, neuropsychological associates. PMID:27867415

  4. Ocean acidification in the Meso- vs. Cenozoic: lessons from modeling about the geological expression of paleo-ocean acidification

    NASA Astrophysics Data System (ADS)

    Greene, S. E.; Ridgwell, A.; Kirtland Turner, S.

    2015-12-01

    Rapid climatic and biotic events putatively associated with ocean acidification are scattered throughout the Meso-Cenozoic. Many of these rapid perturbations, variably referred to as hyperthermals (Paleogene) and oceanic anoxic events or mass extinction events (Mesozoic), share a number of characteristic features, including some combination of negative carbon isotopic excursion, global warming, and a rise in atmospheric CO2 concentration. Comparisons between ocean acidification events over the last ~250 Ma are, however, problematic because the types of marine geological archives and carbon reservoirs that can be interrogated are fundamentally different for early Mesozoic vs. late Mesozoic-Cenozoic events. Many Mesozoic events are known primarily or exclusively from geological outcrops of relatively shallow water deposits, whereas the more recent Paleogene hyperthermal events have been chiefly identified from deep sea records. In addition, these earlier events are superimposed on an ocean with a fundamentally different carbonate buffering capacity, as calcifying plankton (which created the deep-sea carbonate sink) originate in the mid-Mesozoic. Here, we use both Earth system modeling and reaction transport sediment modeling to explore the ways in which comparable ocean acidification-inducing climate perturbations might manifest in the Mesozoic vs. the Cenozoic geological record. We examine the role of the deep-sea carbonate sink in the expression of ocean acidification, as well as the spatial heterogeneity of surface ocean pH and carbonate saturation state. These results critically inform interpretations of ocean acidification prior to the mid-Mesozoic advent of calcifying plankton and expectations about the recording of these events in geological outcrop.

  5. A FRET-Based DNA Biosensor Tracks OmpR-Dependent Acidification of Salmonella during Macrophage Infection

    PubMed Central

    Chakraborty, Smarajit; Mizusaki, Hideaki; Kenney, Linda J.

    2015-01-01

    In bacteria, one paradigm for signal transduction is the two-component regulatory system, consisting of a sensor kinase (usually a membrane protein) and a response regulator (usually a DNA binding protein). The EnvZ/OmpR two-component system responds to osmotic stress and regulates expression of outer membrane proteins. In Salmonella, EnvZ/OmpR also controls expression of another two-component system SsrA/B, which is located on Salmonella Pathogenicity Island (SPI) 2. SPI-2 encodes a type III secretion system, which functions as a nanomachine to inject bacterial effector proteins into eukaryotic cells. During the intracellular phase of infection, Salmonella switches from assembling type III secretion system structural components to secreting effectors into the macrophage cytoplasm, enabling Salmonella to replicate in the phagocytic vacuole. Major questions remain regarding how bacteria survive the acidified vacuole and how acidification affects bacterial secretion. We previously reported that EnvZ sensed cytoplasmic signals rather than extracellular ones, as intracellular osmolytes altered the dynamics of a 17-amino-acid region flanking the phosphorylated histidine. We reasoned that the Salmonella cytoplasm might acidify in the macrophage vacuole to activate OmpR-dependent transcription of SPI-2 genes. To address these questions, we employed a DNA-based FRET biosensor (“I-switch”) to measure bacterial cytoplasmic pH and immunofluorescence to monitor effector secretion during infection. Surprisingly, we observed a rapid drop in bacterial cytoplasmic pH upon phagocytosis that was not predicted by current models. Cytoplasmic acidification was completely dependent on the OmpR response regulator, but did not require known OmpR-regulated genes such as ompC, ompF, or ssaC (SPI-2). Microarray analysis highlighted the cadC/BA operon, and additional experiments confirmed that it was repressed by OmpR. Acidification was blocked in the ompR null background in a Cad

  6. A FRET-based DNA biosensor tracks OmpR-dependent acidification of Salmonella during macrophage infection.

    PubMed

    Chakraborty, Smarajit; Mizusaki, Hideaki; Kenney, Linda J

    2015-04-01

    In bacteria, one paradigm for signal transduction is the two-component regulatory system, consisting of a sensor kinase (usually a membrane protein) and a response regulator (usually a DNA binding protein). The EnvZ/OmpR two-component system responds to osmotic stress and regulates expression of outer membrane proteins. In Salmonella, EnvZ/OmpR also controls expression of another two-component system SsrA/B, which is located on Salmonella Pathogenicity Island (SPI) 2. SPI-2 encodes a type III secretion system, which functions as a nanomachine to inject bacterial effector proteins into eukaryotic cells. During the intracellular phase of infection, Salmonella switches from assembling type III secretion system structural components to secreting effectors into the macrophage cytoplasm, enabling Salmonella to replicate in the phagocytic vacuole. Major questions remain regarding how bacteria survive the acidified vacuole and how acidification affects bacterial secretion. We previously reported that EnvZ sensed cytoplasmic signals rather than extracellular ones, as intracellular osmolytes altered the dynamics of a 17-amino-acid region flanking the phosphorylated histidine. We reasoned that the Salmonella cytoplasm might acidify in the macrophage vacuole to activate OmpR-dependent transcription of SPI-2 genes. To address these questions, we employed a DNA-based FRET biosensor ("I-switch") to measure bacterial cytoplasmic pH and immunofluorescence to monitor effector secretion during infection. Surprisingly, we observed a rapid drop in bacterial cytoplasmic pH upon phagocytosis that was not predicted by current models. Cytoplasmic acidification was completely dependent on the OmpR response regulator, but did not require known OmpR-regulated genes such as ompC, ompF, or ssaC (SPI-2). Microarray analysis highlighted the cadC/BA operon, and additional experiments confirmed that it was repressed by OmpR. Acidification was blocked in the ompR null background in a Cad

  7. Ocean acidification and its impacts: an expert survey

    NASA Astrophysics Data System (ADS)

    Gattuso, J.; Mach, K.; Morgan, M. G.

    2011-12-01

    The number of scientists investigating ocean acidification as well as the number of papers published on this issue have increased considerably in the past few years. On the one hand, the advances are welcome for the assessment of ocean acidification and its impacts. On the other hand, the volume and rapidity of the scientific developments as well as some contradictory results have created challenges for assessing the current state of knowledge and informing policy makers. Two tools are being used to synthesize the current information: meta-analysis and expert survey. In January this year, Working Groups I and II of the IPCC organized an expert meeting on ocean acidification in Okinawa. Following this meeting, we built a set of 22 statements, in consultation with several of the meeting participants. An expert survey was then conducted. It involved 52 experts who provided a considerable amount of information. The statements covered a broad array of research fields and were grouped in 3 categories: chemical aspects, biological and biogeochemical responses, and policy and socio-economic aspects. The survey results indicate a relatively strong consensus for most statements related to the past, present and future chemical aspects. Examples of consensual issues are: non-anthropogenic ocean acidification events have occurred in the geological past, anthropogenic CO2 emissions is the main (but not the only) mechanism generating the current ocean acidification event, and ocean acidification will be felt for centuries. The experts generally agreed that there will be impacts on biological and ecological processes and biogeochemical feedbacks, but for such statements, the levels of agreement were lower overall, with more variability across responses. Levels of agreements among experts surveyed were comparatively higher for statements regarding calcification, primary production and nitrogen fixation, as compared to impacts on food-webs. The levels of agreement for statements

  8. Magnolol Enhances Hippocampal Neurogenesis and Exerts Antidepressant-Like Effects in Olfactory Bulbectomized Mice.

    PubMed

    Matsui, Nobuaki; Akae, Haruka; Hirashima, Nana; Kido, Yuki; Tanabe, Satoshi; Koseki, Mayumi; Fukuyama, Yoshiyasu; Akagi, Masaaki

    2016-11-01

    Magnolol is the main constituent of Magnolia bark and has been reported to exhibit antidepressant effects in rodent models. Hippocampal neurogenesis and neurotrophins such as brain-derived neurotrophic factor are integrally involved in the action of conventional antidepressants. Here, we investigated the effects of magnolol on depressive behaviours, impaired hippocampal neurogenesis and neurotrophin-related signal transduction in an olfactory bulbectomy (OBX) mouse model of depression. Mice were submitted to OBX to induce depressive behaviour, which was evaluated in the tail suspension test. Magnolol was administered orally by gavage needle. Neurogenesis was assessed by analysis of cells expressing NeuN, a neuronal marker, and 5-bromo-2'-deoxyuridine (BrdU) uptake. Phosphorylation levels of protein kinase B (Akt), extracellular signal-regulated kinase and cyclic AMP-responsive element-binding protein were evaluated by Western blot. Fourteen day treatment with magnolol (50 or 100 mg/kg/day) significantly improved OBX-induced depressive behaviour in tail suspension test. In agreement, magnolol significantly rescued impairments of hippocampal neurogenesis. Moreover, single treatments with magnolol (50 mg/kg) significantly increased phosphorylation of Akt, extracellular signal-regulated kinase and cyclic AMP-responsive element-binding protein after 3 h. The present data indicate that magnolol exerts antidepressant-like effects on behaviours by enhancing hippocampal neurogenesis and neurotrophin-related intracellular signalling in OBX mice. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Netrin-1 exerts oncogenic activities through enhancing Yes-associated protein stability.

    PubMed

    Qi, Qi; Li, Dean Y; Luo, Hongbo R; Guan, Kun-Liang; Ye, Keqiang

    2015-06-09

    Yes-associated protein (YAP), a transcription coactivator, is the major downstream effector of the Hippo pathway, which plays a critical role in organ size control and cancer development. However, how YAP is regulated by extracellular stimuli in tumorigenesis remains incompletely understood. Netrin-1, a laminin-related secreted protein, displays proto-oncogenic activity in cancers. Nonetheless, the downstream signaling mediating its oncogenic effects is not well defined. Here we show that netrin-1 via its transmembrane receptors, deleted in colorectal cancer and uncoordinated-5 homolog, up-regulates YAP expression, escalating YAP levels in the nucleus and promoting cancer cell proliferation and migration. Inactivating netrin-1, deleted in colorectal cancer, or uncoordinated-5 homolog B (UNC5B) decreases YAP protein levels, abrogating cancer cell progression by netrin-1, whereas knockdown of mammalian STE20-like protein kinase 1/2 (MST1/2) or large tumor suppressor kinase 1/2 (Lats1/2), two sets of upstream core kinases of the Hippo pathway, has no effect in blocking netrin-1-induced up-regulation of YAP. Netrin-1 stimulates phosphatase 1A to dephosphorylate YAP, which leads to decreased ubiquitination and degradation, enhancing YAP accumulation and signaling. Hence, our findings support that netrin-1 exerts oncogenic activity through YAP signaling, providing a mechanism coupling extracellular signals to the nuclear YAP oncogene.

  10. Musical agency reduces perceived exertion during strenuous physical performance

    PubMed Central

    Fritz, Thomas Hans; Hardikar, Samyogita; Demoucron, Matthias; Niessen, Margot; Demey, Michiel; Giot, Olivier; Li, Yongming; Haynes, John-Dylan; Villringer, Arno; Leman, Marc

    2013-01-01

    Music is known to be capable of reducing perceived exertion during strenuous physical activity. The current interpretation of this modulating effect of music is that music may be perceived as a diversion from unpleasant proprioceptive sensations that go along with exhaustion. Here we investigated the effects of music on perceived exertion during a physically strenuous task, varying musical agency, a task that relies on the experience of body proprioception, rather than simply diverting from it. For this we measured psychologically indicated exertion during physical workout with and without musical agency while simultaneously acquiring metabolic values with spirometry. Results showed that musical agency significantly decreased perceived exertion during workout, indicating that musical agency may actually facilitate physically strenuous activities. This indicates that the positive effect of music on perceived exertion cannot always be explained by an effect of diversion from proprioceptive feedback. Furthermore, this finding suggests that the down-modulating effect of musical agency on perceived exertion may be a previously unacknowledged driving force for the development of music in humans: making music makes strenuous physical activities less exhausting. PMID:24127588

  11. Red coral extinction risk enhanced by ocean acidification.

    PubMed

    Cerrano, Carlo; Cardini, Ulisse; Bianchelli, Silvia; Corinaldesi, Cinzia; Pusceddu, Antonio; Danovaro, Roberto

    2013-01-01

    The red coral Corallium rubrum is a habitat-forming species with a prominent and structural role in mesophotic habitats, which sustains biodiversity hotspots. This precious coral is threatened by both over-exploitation and temperature driven mass mortality events. We report here that biocalcification, growth rates and polyps' (feeding) activity of Corallium rubrum are significantly reduced at pCO2 scenarios predicted for the end of this century (0.2 pH decrease). Since C. rubrum is a long-living species (>200 years), our results suggest that ocean acidification predicted for 2100 will significantly increases the risk of extinction of present populations. Given the functional role of these corals in the mesophotic zone, we predict that ocean acidification might have cascading effects on the functioning of these habitats worldwide.

  12. Red coral extinction risk enhanced by ocean acidification

    PubMed Central

    Cerrano, Carlo; Cardini, Ulisse; Bianchelli, Silvia; Corinaldesi, Cinzia; Pusceddu, Antonio; Danovaro, Roberto

    2013-01-01

    The red coral Corallium rubrum is a habitat-forming species with a prominent and structural role in mesophotic habitats, which sustains biodiversity hotspots. This precious coral is threatened by both over-exploitation and temperature driven mass mortality events. We report here that biocalcification, growth rates and polyps' (feeding) activity of Corallium rubrum are significantly reduced at pCO2 scenarios predicted for the end of this century (0.2 pH decrease). Since C. rubrum is a long-living species (>200 years), our results suggest that ocean acidification predicted for 2100 will significantly increases the risk of extinction of present populations. Given the functional role of these corals in the mesophotic zone, we predict that ocean acidification might have cascading effects on the functioning of these habitats worldwide. PMID:23492780

  13. Food supply confers calcifiers resistance to ocean acidification.

    PubMed

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K; Blicher, Martin E; Lagos, Nelson A; Olsen, Ylva S; Duarte, Carlos M

    2016-01-18

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

  14. Food supply confers calcifiers resistance to ocean acidification

    PubMed Central

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E.; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K.; Blicher, Martin E.; Lagos, Nelson A.; Olsen, Ylva S.; Duarte, Carlos M.

    2016-01-01

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification. PMID:26778520

  15. Food supply confers calcifiers resistance to ocean acidification

    NASA Astrophysics Data System (ADS)

    Ramajo, Laura; Pérez-León, Elia; Hendriks, Iris E.; Marbà, Núria; Krause-Jensen, Dorte; Sejr, Mikael K.; Blicher, Martin E.; Lagos, Nelson A.; Olsen, Ylva S.; Duarte, Carlos M.

    2016-01-01

    Invasion of ocean surface waters by anthropogenic CO2 emitted to the atmosphere is expected to reduce surface seawater pH to 7.8 by the end of this century compromising marine calcifiers. A broad range of biological and mineralogical mechanisms allow marine calcifiers to cope with ocean acidification, however these mechanisms are energetically demanding which affect other biological processes (trade-offs) with important implications for the resilience of the organisms against stressful conditions. Hence, food availability may play a critical role in determining the resistance of calcifiers to OA. Here we show, based on a meta-analysis of existing experimental results assessing the role of food supply in the response of organisms to OA, that food supply consistently confers calcifiers resistance to ocean acidification.

  16. Phytoplankton succession during acidification with and without increasing aluminum levels.

    PubMed

    Havens, K E; Heath, R T

    1990-01-01

    An in situ mesocosm experiment was performed to investigate the role of aluminum in controlling phytoplankton community succession during lake acidification. Large (2000 liter) mesocosms were suspended in mesotrophic East Twin Lake, Ohio, USA. Duplicates were either untreated controls (pH 8.8), acidified to pH 4.5 over 23 days, or acidified and spiked with 200 microg/liter Al in incremental additions. Filamentous blue greens, diatoms and other chrysophytes became extinct in both acid treatments, but declined most rapidly where Al levels were also increased. The large desmid Closterium and the filamentous chlorophyte Mougoetia became dominant in the Acid treatment. In the Acid + Al treatment, these algae also became dominant, but the species with greatest biomass was the dinoflagellate Peridinium inconspicuum. Acidification (with or without added Al) also resulted in a significant shift in the algal size spectrum to larger (> 20 microm) cells.

  17. Progress in Controlled In Situ Ocean Acidification Experiments

    NASA Astrophysics Data System (ADS)

    Brewer, Peter; Kirkwood, William; Gattuso, Jean-Pierre

    2013-04-01

    Ocean acidification is widely recognized as a significant climate-related oceanic threat, not only independently but also in connection with other oceanic stressors, including warming and deoxygenation. Recent work shows that ocean acidification will negatively affect processes such as calcification of most species, including reef-building corals, and could also cause diminished fish sensory ability and respiratory stress. However, almost all of these findings result from short-term experiments on organisms in laboratory aquaria. But how can scientists perform long-term in situ experiments that may confirm, or modify, conclusions drawn from laboratory experiments? With funding from the BNP Paribas Foundation, the xFOCE workshop brought together a group of 20 scientists and engineers to examine this.

  18. Projecting coral reef futures under global warming and ocean acidification.

    PubMed

    Pandolfi, John M; Connolly, Sean R; Marshall, Dustin J; Cohen, Anne L

    2011-07-22

    Many physiological responses in present-day coral reefs to climate change are interpreted as consistent with the imminent disappearance of modern reefs globally because of annual mass bleaching events, carbonate dissolution, and insufficient time for substantial evolutionary responses. Emerging evidence for variability in the coral calcification response to acidification, geographical variation in bleaching susceptibility and recovery, responses to past climate change, and potential rates of adaptation to rapid warming supports an alternative scenario in which reef degradation occurs with greater temporal and spatial heterogeneity than current projections suggest. Reducing uncertainty in projecting coral reef futures requires improved understanding of past responses to rapid climate change; physiological responses to interacting factors, such as temperature, acidification, and nutrients; and the costs and constraints imposed by acclimation and adaptation.

  19. Rapid progression of ocean acidification in the California Current System.

    PubMed

    Gruber, Nicolas; Hauri, Claudine; Lachkar, Zouhair; Loher, Damian; Frölicher, Thomas L; Plattner, Gian-Kasper

    2012-07-13

    Nearshore waters of the California Current System (California CS) already have a low carbonate saturation state, making them particularly susceptible to ocean acidification. We used eddy-resolving model simulations to study the potential development of ocean acidification in this system up to the year 2050 under the Special Report on Emissions Scenarios A2 and B1 scenarios. In both scenarios, the saturation state of aragonite Ω(arag) is projected to drop rapidly, with much of the nearshore region developing summer-long undersaturation in the top 60 meters within the next 30 years. By 2050, waters with Ω(arag) above 1.5 will have largely disappeared, and more than half of the waters will be undersaturated year-round. Habitats along the sea floor will become exposed to year-round undersaturation within the next 20 to 30 years. These projected events have potentially major implications for the rich and diverse ecosystem that characterizes the California CS.

  20. Modelling coral polyp calcification in relation to ocean acidification

    NASA Astrophysics Data System (ADS)

    Hohn, S.; Merico, A.

    2012-11-01

    Rising atmospheric CO2 concentrations due to anthropogenic emissions induce changes in the carbonate chemistry of the oceans and, ultimately, a drop in ocean pH. This acidification process can harm calcifying organisms like coccolithophores, molluscs, echinoderms, and corals. It is expected that ocean acidification in combination with other anthropogenic stressors will cause a severe decline in coral abundance by the end of this century, with associated disastrous effects on reef ecosystems. Despite the growing importance of the topic, little progress has been made with respect to modelling the impact of acidification on coral calcification. Here we present a model for a coral polyp that simulates the carbonate system in four different compartments: the seawater, the polyp tissue, the coelenteron, and the calcifying fluid. Precipitation of calcium carbonate takes place in the metabolically controlled calcifying fluid beneath the polyp tissue. The model is adjusted to a state of activity as observed by direct microsensor measurements in the calcifying fluid. We find that a transport mechanism for bicarbonate is required to supplement carbon into the calcifying fluid because CO2 diffusion alone is not sufficient to sustain the observed calcification rates. Simulated CO2 perturbation experiments reveal decreasing calcification rates under elevated pCO2 despite the strong metabolic control of the calcifying fluid. Diffusion of CO2 through the tissue into the calcifying fluid increases with increasing seawater pCO2, leading to decreased aragonite saturation in the calcifying fluid. Our modelling study provides important insights into the complexity of the calcification process at the organism level and helps to quantify the effect of ocean acidification on corals.

  1. Responses of coccolithophores to ocean acidification: a meta-analysis

    NASA Astrophysics Data System (ADS)

    Meyer, J.; Riebesell, U.

    2014-10-01

    Concerning their sensitivity to ocean acidification, coccolithophores, a group of calcifying single-celled phytoplankton, are one of the best-studied groups of marine organisms. However, in spite of the large number of studies investigating coccolithophore physiological responses to ocean acidification, uncertainties still remain due to variable and partly contradictory results. In the present study we have used all existing data in a meta-analysis to estimate the effect size of future pCO2 changes on the rates of calcification and photosynthesis and the ratio of particulate inorganic to organic carbon (PIC/POC) in different coccolithophore species. Our results indicate that ocean acidification has a negative effect on calcification and the cellular PIC/POC ratio in the most abundant coccolithophore species Emiliania huxleyi and Gephyrocapsa oceanica. In contrast the more heavily calcified species Coccolithus braarudii did not show a distinct response when exposed to elevated pCO2/reduced pH. Photosynthesis in Gephyrocapsa oceanica was positively affected by high CO2, while no effect was observed for the other coccolithophore species. There was no indication that the method of carbonate chemistry manipulation was responsible for the inconsistent results regarding observed responses in calcification and the PIC/POC ratio. The perturbation method, however, appears to affect photosynthesis, as responses varied significantly between total alkalinity (TA) and dissolved inorganic carbon (DIC) manipulations. These results emphasize that coccolithophore species respond differently to ocean acidification, both in terms of calcification and photosynthesis. Where negative effects occur, they become evident at CO2 levels in the range projected for this century in case of unabated CO2 emissions. As the data sets used in this meta-analysis do not account for adaptive responses and ecological fitness, the questions remains how these physiological responses play out in the natural

  2. Cascading Effects of Ocean Acidification in a Rocky Subtidal Community

    PubMed Central

    Asnaghi, Valentina; Chiantore, Mariachiara; Mangialajo, Luisa; Gazeau, Frédéric; Francour, Patrice; Alliouane, Samir; Gattuso, Jean-Pierre

    2013-01-01

    Temperate marine rocky habitats may be alternatively characterized by well vegetated macroalgal assemblages or barren grounds, as a consequence of direct and indirect human impacts (e.g. overfishing) and grazing pressure by herbivorous organisms. In future scenarios of ocean acidification, calcifying organisms are expected to be less competitive: among these two key elements of the rocky subtidal food web, coralline algae and sea urchins. In order to highlight how the effects of increased pCO2 on individual calcifying species will be exacerbated by interactions with other trophic levels, we performed an experiment simultaneously testing ocean acidification effects on primary producers (calcifying and non-calcifying algae) and their grazers (sea urchins). Artificial communities, composed by juveniles of the sea urchin Paracentrotus lividus and calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea var stricta, Dictyota dichotoma) macroalgae, were subjected to pCO2 levels of 390, 550, 750 and 1000 µatm in the laboratory. Our study highlighted a direct pCO2 effect on coralline algae and on sea urchin defense from predation (test robustness). There was no direct effect on the non-calcifying macroalgae. More interestingly, we highlighted diet-mediated effects on test robustness and on the Aristotle's lantern size. In a future scenario of ocean acidification a decrease of sea urchins' density is expected, due to lower defense from predation, as a direct consequence of pH decrease, and to a reduced availability of calcifying macroalgae, important component of urchins' diet. The effects of ocean acidification may therefore be contrasting on well vegetated macroalgal assemblages and barren grounds: in the absence of other human impacts, a decrease of biodiversity can be predicted in vegetated macroalgal assemblages, whereas a lower density of sea urchin could help the recovery of shallow subtidal rocky areas affected by overfishing from barren grounds to

  3. Cascading effects of ocean acidification in a rocky subtidal community.

    PubMed

    Asnaghi, Valentina; Chiantore, Mariachiara; Mangialajo, Luisa; Gazeau, Frédéric; Francour, Patrice; Alliouane, Samir; Gattuso, Jean-Pierre

    2013-01-01

    Temperate marine rocky habitats may be alternatively characterized by well vegetated macroalgal assemblages or barren grounds, as a consequence of direct and indirect human impacts (e.g. overfishing) and grazing pressure by herbivorous organisms. In future scenarios of ocean acidification, calcifying organisms are expected to be less competitive: among these two key elements of the rocky subtidal food web, coralline algae and sea urchins. In order to highlight how the effects of increased pCO2 on individual calcifying species will be exacerbated by interactions with other trophic levels, we performed an experiment simultaneously testing ocean acidification effects on primary producers (calcifying and non-calcifying algae) and their grazers (sea urchins). Artificial communities, composed by juveniles of the sea urchin Paracentrotus lividus and calcifying (Corallina elongata) and non-calcifying (Cystoseira amentacea var stricta, Dictyota dichotoma) macroalgae, were subjected to pCO2 levels of 390, 550, 750 and 1000 µatm in the laboratory. Our study highlighted a direct pCO2 effect on coralline algae and on sea urchin defense from predation (test robustness). There was no direct effect on the non-calcifying macroalgae. More interestingly, we highlighted diet-mediated effects on test robustness and on the Aristotle's lantern size. In a future scenario of ocean acidification a decrease of sea urchins' density is expected, due to lower defense from predation, as a direct consequence of pH decrease, and to a reduced availability of calcifying macroalgae, important component of urchins' diet. The effects of ocean acidification may therefore be contrasting on well vegetated macroalgal assemblages and barren grounds: in the absence of other human impacts, a decrease of biodiversity can be predicted in vegetated macroalgal assemblages, whereas a lower density of sea urchin could help the recovery of shallow subtidal rocky areas affected by overfishing from barren grounds to

  4. Decoupled response of ocean acidification to variations in climate sensitivity

    NASA Astrophysics Data System (ADS)

    Matsumoto, K.; McNeil, B.

    2013-12-01

    It is now well understood that the global surface ocean, whose pH has been reduced by ~0.1 in response to rising atmospheric CO2 since industrialization, will continue to become more acidic as fossil fuel CO2 emissions escalate. However, it is unclear how uncertainties in climate sensitivity to future CO2 emissions will alter the manifestation of ocean acidification. Using an earth system model of intermediate complexity, we perform a set of simulations that varies equilibrium climate sensitivity by 1.0 to 4.5°C for a given CO2 emissions scenario and find two unexpected and decoupled responses. Firstly, the greater the climate sensitivity, the larger the surface mixed layer acidification signal but the smaller the subsurface acidification. However, taken throughout the ocean, highest climate sensitivity will paradoxically cause greater global warming while buffering whole-ocean pH by up to 24% on centennial time-scales. Secondly, we find a large decoupling between pH and carbonate ion concentration in surface waters whereby these chemical properties show opposite effects under variable climate sensitivity. For every 1°C increase in climate sensitivity, the surface ocean pH reduction grows by 4%, while surface ocean carbonate ion reduction shrinks by 2%. The chemical and spatial decoupling found here highlights the importance of distinguishing the biological impacts of pH and aragonite saturation and understanding the spatial extent of important calcifying biomes so as to truly understand the long-term impacts of ocean acidification.

  5. Including high-frequency variability in coastal ocean acidification projections

    NASA Astrophysics Data System (ADS)

    Takeshita, Y.; Frieder, C. A.; Martz, T. R.; Ballard, J. R.; Feely, R. A.; Kram, S.; Nam, S.; Navarro, M. O.; Price, N. N.; Smith, J. E.

    2015-10-01

    Assessing the impacts of anthropogenic ocean acidification requires knowledge of present-day and future environmental conditions. Here, we present a simple model for upwelling margins that projects anthropogenic acidification trajectories by combining high-temporal-resolution sensor data, hydrographic surveys for source water characterization, empirical relationships of the CO2 system, and the atmospheric CO2 record. This model characterizes CO2 variability on timescales ranging from hours (e.g., tidal) to months (e.g., seasonal), bridging a critical knowledge gap in ocean acidification research. The amount of anthropogenic carbon in a given water mass is dependent on the age; therefore a density-age relationship was derived for the study region and then combined with the 2013 Intergovernmental Panel on Climate Change CO2 emission scenarios to add density-dependent anthropogenic carbon to the sensor time series. The model was applied to time series from autonomous pH sensors deployed in the surf zone, kelp forest, submarine canyon edge, and shelf break in the upper 100 m of the Southern California Bight. All habitats were within 5 km of one another, and exhibited unique, habitat-specific CO2 variability signatures and acidification trajectories, demonstrating the importance of making projections in the context of habitat-specific CO2 signatures. In general, both the mean and range of pCO2 increase in the future, with the greatest increase in both magnitude and range occurring in the deeper habitats due to reduced buffering capacity. On the other hand, the saturation state of aragonite (ΩAr) decreased in both magnitude and range. This approach can be applied to the entire California Current System, and upwelling margins in general, where sensor and complementary hydrographic data are available.

  6. Physiological, toxicological, and population responses of smallmouth bass to acidification

    SciTech Connect

    Marcus, M.D.; Gulley, D.D.; Christensen, S.W.; McDonald, D.G.; Van Winkle, W.; Mount, D.R.; Wood, C.M.; Bergman, H.L. . Dept. of Zoology and Physiology)

    1992-08-01

    The Lake Acidification and Fisheries (LAF) project examined effects of acidic water chemistries on four fish species. This report presents an overview of investigations on smallmouth bass (Micropterus dolomieui). Experiments conducted with this species included as many as 84 exposure combinations of acid, aluminum, and low calcium. In egg, fry, and juvenile stages of smallmouth bass, increased acid and aluminum concentrations increased mortality and decreased growth, while increased calcium concentrations often improved survival. Relative to the juvenile life stages of smallmouth bass tested, yolksac and swim-up fry were clearly more sensitive to stressful exposure conditions. While eggs appeared to be the most sensitive life stage, this conclusion was compromised by heavy mortalities of eggs due to fungal infestations during experimental exposures. As found in our earlier studies with brook and rainbow trout, acid-aluminum stressed smallmouth bass exhibited net losses of electrolytes across gills and increased accumulation of aluminum on gill tissues. Overall, our results indicated that smallmouth bass were generally more sensitive to increased exposure concentrations of aluminum than to increased acidities. Compared to toxicology results from earlier LAF project studies, smallmouth bass were more sensitive than brook trout and slightly less sensitive than rainbow trout when exposed to water quality conditions associated with acidification.An example application of the LAF modeling framework shows how different liming scenarios can improve survival probabilities for smallmouth bass in a set of lakes sensitive to acidification.

  7. Ocean warming and acidification synergistically increase coral mortality.

    PubMed

    Prada, F; Caroselli, E; Mengoli, S; Brizi, L; Fantazzini, P; Capaccioni, B; Pasquini, L; Fabricius, K E; Dubinsky, Z; Falini, G; Goffredo, S

    2017-01-19

    Organisms that accumulate calcium carbonate structures are particularly vulnerable to ocean warming (OW) and ocean acidification (OA), potentially reducing the socioeconomic benefits of ecosystems reliant on these taxa. Since rising atmospheric CO2 is responsible for global warming and increasing ocean acidity, to correctly predict how OW and OA will affect marine organisms, their possible interactive effects must be assessed. Here we investigate, in the field, the combined temperature (range: 16-26 °C) and acidification (range: pHTS 8.1-7.4) effects on mortality and growth of Mediterranean coral species transplanted, in different seasonal periods, along a natural pH gradient generated by a CO2 vent. We show a synergistic adverse effect on mortality rates (up to 60%), for solitary and colonial, symbiotic and asymbiotic corals, suggesting that high seawater temperatures may have increased their metabolic rates which, in conjunction with decreasing pH, could have led to rapid deterioration of cellular processes and performance. The net calcification rate of the symbiotic species was not affected by decreasing pH, regardless of temperature, while in the two asymbiotic species it was negatively affected by increasing acidification and temperature, suggesting that symbiotic corals may be more tolerant to increasing warming and acidifying conditions compared to asymbiotic ones.

  8. Ocean warming and acidification synergistically increase coral mortality

    NASA Astrophysics Data System (ADS)

    Prada, F.; Caroselli, E.; Mengoli, S.; Brizi, L.; Fantazzini, P.; Capaccioni, B.; Pasquini, L.; Fabricius, K. E.; Dubinsky, Z.; Falini, G.; Goffredo, S.

    2017-01-01

    Organisms that accumulate calcium carbonate structures are particularly vulnerable to ocean warming (OW) and ocean acidification (OA), potentially reducing the socioeconomic benefits of ecosystems reliant on these taxa. Since rising atmospheric CO2 is responsible for global warming and increasing ocean acidity, to correctly predict how OW and OA will affect marine organisms, their possible interactive effects must be assessed. Here we investigate, in the field, the combined temperature (range: 16–26 °C) and acidification (range: pHTS 8.1–7.4) effects on mortality and growth of Mediterranean coral species transplanted, in different seasonal periods, along a natural pH gradient generated by a CO2 vent. We show a synergistic adverse effect on mortality rates (up to 60%), for solitary and colonial, symbiotic and asymbiotic corals, suggesting that high seawater temperatures may have increased their metabolic rates which, in conjunction with decreasing pH, could have led to rapid deterioration of cellular processes and performance. The net calcification rate of the symbiotic species was not affected by decreasing pH, regardless of temperature, while in the two asymbiotic species it was negatively affected by increasing acidification and temperature, suggesting that symbiotic corals may be more tolerant to increasing warming and acidifying conditions compared to asymbiotic ones.

  9. The response of marine picoplankton to ocean acidification.

    PubMed

    Newbold, Lindsay K; Oliver, Anna E; Booth, Tim; Tiwari, Bela; Desantis, Todd; Maguire, Michael; Andersen, Gary; van der Gast, Christopher J; Whiteley, Andrew S

    2012-09-01

    Since industrialization global CO(2) emissions have increased, and as a consequence oceanic pH is predicted to drop by 0.3-0.4 units before the end of the century - a process coined 'ocean acidification'. Consequently, there is significant interest in how pH changes will affect the ocean's biota and integral processes. We investigated marine picoplankton (0.2-2 µm diameter) community response to predicted end of century CO(2) concentrations, via a 'high-CO(2) ' (∼ 750 ppm) large-volume (11 000 l) contained seawater mesocosm approach. We found little evidence of changes occurring in bacterial abundance or community composition due to elevated CO(2) under both phytoplankton pre-bloom/bloom and post-bloom conditions. In contrast, significant differences were observed between treatments for a number of key picoeukaryote community members. These data suggested a key outcome of ocean acidification is a more rapid exploitation of elevated CO(2) levels by photosynthetic picoeukaryotes. Thus, our study indicates the need for a more thorough understanding of picoeukaryote-mediated carbon flow within ocean acidification experiments, both in relation to picoplankton carbon sources, sinks and transfer to higher trophic levels.

  10. Hydrolysis and acidification of grass silage in leaching bed reactors.

    PubMed

    Xie, S; Lawlor, P G; Frost, J P; Wu, G; Zhan, X

    2012-06-01

    Hydrolysis and acidification of grass silage (GS) was examined in leaching bed reactors (LBRs) under organic loading rates (OLRs) of 0.5, 0.8 and 1.0 kg volatile solids (VS)/m(3)/day. The LBRs were run in duplicate over five consecutive batch tests (Batch tests 1-5) to examine the effects of pH, leachate dilution and addition of inoculum on the process of hydrolysis and acidification. The highest GS hydrolysis yields of 52-58%, acidification yields of 57-60% and VS removals of 62-66% were obtained in Batch test 4. Increasing OLRs affected the hydrolysis yield negatively. In Batch test 4, the reduction of lignocellulosic materials was up to 74.4% of hemicellulose, 30.1% of cellulose and 9.3% of lignin within 32 days. Cellulase activity can be used as an indicator for the hydrolysis process. Methane production from the LBRs only accounted for 10.0-13.8% of the biological methane potential of GS.

  11. Risk maps for Antarctic krill under projected Southern Ocean acidification

    NASA Astrophysics Data System (ADS)

    Kawaguchi, S.; Ishida, A.; King, R.; Raymond, B.; Waller, N.; Constable, A.; Nicol, S.; Wakita, M.; Ishimatsu, A.

    2013-09-01

    Marine ecosystems of the Southern Ocean are particularly vulnerable to ocean acidification. Antarctic krill (Euphausia superba; hereafter krill) is the key pelagic species of the region and its largest fishery resource. There is therefore concern about the combined effects of climate change, ocean acidification and an expanding fishery on krill and ultimately, their dependent predators--whales, seals and penguins. However, little is known about the sensitivity of krill to ocean acidification. Juvenile and adult krill are already exposed to variable seawater carbonate chemistry because they occupy a range of habitats and migrate both vertically and horizontally on a daily and seasonal basis. Moreover, krill eggs sink from the surface to hatch at 700-1,000m (ref. ), where the carbon dioxide partial pressure (pCO2) in sea water is already greater than it is in the atmosphere. Krill eggs sink passively and so cannot avoid these conditions. Here we describe the sensitivity of krill egg hatch rates to increased CO2, and present a circumpolar risk map of krill hatching success under projected pCO2 levels. We find that important krill habitats of the Weddell Sea and the Haakon VII Sea to the east are likely to become high-risk areas for krill recruitment within a century. Furthermore, unless CO2 emissions are mitigated, the Southern Ocean krill population could collapse by 2300 with dire consequences for the entire ecosystem.

  12. Quantifying Rates of Evolutionary Adaptation in Response to Ocean Acidification

    PubMed Central

    Sunday, Jennifer M.; Crim, Ryan N.; Harley, Christopher D. G.; Hart, Michael W.

    2011-01-01

    The global acidification of the earth's oceans is predicted to impact biodiversity via physiological effects impacting growth, survival, reproduction, and immunology, leading to changes in species abundances and global distributions. However, the degree to which these changes will play out critically depends on the evolutionary rate at which populations will respond to natural selection imposed by ocean acidification, which remains largely unquantified. Here we measure the potential for an evolutionary response to ocean acidification in larval development rate in two coastal invertebrates using a full-factorial breeding design. We show that the sea urchin species Strongylocentrotus franciscanus has vastly greater levels of phenotypic and genetic variation for larval size in future CO2 conditions compared to the mussel species Mytilus trossulus. Using these measures we demonstrate that S. franciscanus may have faster evolutionary responses within 50 years of the onset of predicted year-2100 CO2 conditions despite having lower population turnover rates. Our comparisons suggest that information on genetic variation, phenotypic variation, and key demographic parameters, may lend valuable insight into relative evolutionary potentials across a large number of species. PMID:21857962

  13. Inferred effects of lake acidification on Daphnia galeata mendotae

    SciTech Connect

    Keller, W. ); Yan, N.D.; Holtze, K.E. ); Pitblado, J.R. )

    1990-08-01

    Large numbers of Canadian Shield lakes have been acidified by the atmospheric deposition of anthropogenic sulfur. Biological damage attributable to acidification occurs at all levels of aquatic food webs; however, documentation of this damage has largely been confined to areas near large point sources of air pollutants, to small numbers of study lakes, or to experimentally acidified lakes. Demonstrations of widespread biological effects of acidification have been greatly hampered by the general absence of observations of the occurrence or abundance of important, ubiquitous species in large numbers of lakes ranging widely in acidity, coupled with laboratory determinations of lethal acid thresholds for these species. In consequence, it has been necessary to estimate rather than to document the regional extent of biological damage in North America. In this report the authors couple determination of the lethal acid threshold of Daphnia galeata mendotae Birge, a large, ubiquitous, planktonic crustacean, with results of extensive lake surveys, to examine if the acidification of lakes in Ontario has resulted in widespread losses of this important member of the zooplankton.

  14. Transgenerational acclimation of fishes to climate change and ocean acidification.

    PubMed

    Munday, Philip L

    2014-01-01

    There is growing concern about the impacts of climate change and ocean acidification on marine organisms and ecosystems, yet the potential for acclimation and adaptation to these threats is poorly understood. Whereas many short-term experiments report negative biological effects of ocean warming and acidification, new studies show that some marine species have the capacity to acclimate to warmer and more acidic environments across generations. Consequently, transgenerational plasticity may be a powerful mechanism by which populations of some species will be able to adjust to projected climate change. Here, I review recent advances in understanding transgenerational acclimation in fishes. Research over the past 2 to 3 years shows that transgenerational acclimation can partially or fully ameliorate negative effects of warming, acidification, and hypoxia in a range of different species. The molecular and cellular pathways underpinning transgenerational acclimation are currently unknown, but modern genetic methods provide the tools to explore these mechanisms. Despite the potential benefits of transgenerational acclimation, there could be limitations to the phenotypic traits that respond transgenerationally, and trade-offs between life stages, that need to be investigated. Future studies should also test the potential interactions between transgenerational plasticity and genetic evolution to determine how these two processes will shape adaptive responses to environmental change over coming decades.

  15. Ocean warming and acidification synergistically increase coral mortality

    PubMed Central

    Prada, F.; Caroselli, E.; Mengoli, S.; Brizi, L.; Fantazzini, P.; Capaccioni, B.; Pasquini, L.; Fabricius, K. E.; Dubinsky, Z.; Falini, G.; Goffredo, S.

    2017-01-01

    Organisms that accumulate calcium carbonate structures are particularly vulnerable to ocean warming (OW) and ocean acidification (OA), potentially reducing the socioeconomic benefits of ecosystems reliant on these taxa. Since rising atmospheric CO2 is responsible for global warming and increasing ocean acidity, to correctly predict how OW and OA will affect marine organisms, their possible interactive effects must be assessed. Here we investigate, in the field, the combined temperature (range: 16–26 °C) and acidification (range: pHTS 8.1–7.4) effects on mortality and growth of Mediterranean coral species transplanted, in different seasonal periods, along a natural pH gradient generated by a CO2 vent. We show a synergistic adverse effect on mortality rates (up to 60%), for solitary and colonial, symbiotic and asymbiotic corals, suggesting that high seawater temperatures may have increased their metabolic rates which, in conjunction with decreasing pH, could have led to rapid deterioration of cellular processes and performance. The net calcification rate of the symbiotic species was not affected by decreasing pH, regardless of temperature, while in the two asymbiotic species it was negatively affected by increasing acidification and temperature, suggesting that symbiotic corals may be more tolerant to increasing warming and acidifying conditions compared to asymbiotic ones. PMID:28102293

  16. Marine oxygen holes as a consequence of oceanic acidification

    NASA Astrophysics Data System (ADS)

    Hofmann, M.; Schellnhuber, H.-J.

    2009-04-01

    An increase of atmospheric CO2 levels will not only drive future global mean temperatures towards values unprecedented during the whole Quaternary, but will also lead to an acidification of sea water which could harm the marine biota. Here we assess possible impacts of elevated atmospheric CO2 concentrations on the marine biological carbon pump by utilizing a business-as-usual emission scenario of anthropogenic CO2. A corresponding release of 4075 Petagrams of Carbon in total has been applied to simulate the current millennium by employing an Earth System Model of Intermediate Complexity (EMIC). This work is focused on studying the implications of reduced biogenic calcification caused by an increasing degree of oceanic acidification on the marine biological carbon pump. The attenuation of biogenic calcification imposes a small negative feedback on rising atmospheric pCO2 levels, tending to stabilize the Earth's climate. Since mineral ballast, notably particulate CaCO3, plays a dominant role in carrying organic matter through the water column, a reduction of its export fluxes weakens the strength of the biological carbon pump. There is, however, a dramatic effect discovered in our model world with severe consequences: since organic matter is oxidized in shallow waters when mineral-ballast fluxes weaken, oxygen holes (hypoxic zones) start to expand considerably in the oceans with potentially harmful impacts on a variety of marine ecosystems. Our study indicates that unbridled ocean acidification would exacerbate the observed hypoxia trends due to various environmental factors as reported in recent empirical studies.

  17. Anticipating ocean acidification's economic consequences for commercial fisheries

    NASA Astrophysics Data System (ADS)

    Cooley, Sarah R.; Doney, Scott C.

    2009-06-01

    Ocean acidification, a consequence of rising anthropogenic CO2 emissions, is poised to change marine ecosystems profoundly by increasing dissolved CO2 and decreasing ocean pH, carbonate ion concentration, and calcium carbonate mineral saturation state worldwide. These conditions hinder growth of calcium carbonate shells and skeletons by many marine plants and animals. The first direct impact on humans may be through declining harvests and fishery revenues from shellfish, their predators, and coral reef habitats. In a case study of US commercial fishery revenues, we begin to constrain the economic effects of ocean acidification over the next 50 years using atmospheric CO2 trajectories and laboratory studies of its effects, focusing especially on mollusks. In 2007, the 3.8 billion US annual domestic ex-vessel commercial harvest ultimately contributed 34 billion to the US gross national product. Mollusks contributed 19%, or 748 million, of the ex-vessel revenues that year. Substantial revenue declines, job losses, and indirect economic costs may occur if ocean acidification broadly damages marine habitats, alters marine resource availability, and disrupts other ecosystem services. We review the implications for marine resource management and propose possible adaptation strategies designed to support fisheries and marine-resource-dependent communities, many of which already possess little economic resilience.

  18. Progranulin regulates lysosomal function and biogenesis through acidification of lysosomes.

    PubMed

    Tanaka, Yoshinori; Suzuki, Genjiro; Matsuwaki, Takashi; Hosokawa, Masato; Serrano, Geidy; Beach, Thomas G; Yamanouchi, Keitaro; Hasegawa, Masato; Nishihara, Masugi

    2017-01-10

    Progranulin (PGRN) haploinsufficiency resulting from loss-of-function mutations in the PGRN gene causes frontotemporal lobar degeneration accompanied by TDP-43 accumulation, and patients with homozygous mutations in the PGRN gene present with neuronal ceroid lipofuscinosis. Although it remains unknown why PGRN deficiency causes neurodegenerative diseases, there is increasing evidence that PGRN is implicated in lysosomal functions. Here, we show PGRN is a secretory lysosomal protein that regulates lysosomal function and biogenesis by controlling the acidification of lysosomes. PGRN gene expression and protein levels increased concomitantly with the increase of lysosomal biogenesis induced by lysosome alkalizers or serum starvation. Down-regulation or insufficiency of PGRN led to the increased lysosomal gene expression and protein levels, while PGRN overexpression led to the decreased lysosomal gene expression and protein levels. In particular, the level of mature cathepsin D (CTSDmat) dramatically changed depending upon PGRN levels. The acidification of lysosomes was facilitated in cells transfected with PGRN. Then, this caused degradation of CTSDmat by cathepsin B. Secreted PGRN is incorporated into cells via sortilin or cation-independent mannose 6-phosphate receptor, and facilitated the acidification of lysosomes and degradation of CTSDmat Moreover, the change of PGRN levels led to a cell-type-specific increase of insoluble TDP-43. In the brain tissue of FTLD-TDP patients with PGRN deficiency, CTSD and phosphorylated TDP-43 accumulated in neurons. Our study provides new insights into the physiological function of PGRN and the role of PGRN insufficiency in the pathogenesis of neurodegenerative diseases.

  19. Decreased abundance of crustose coralline algae due to ocean acidification

    USGS Publications Warehouse

    Kuffner, Ilsa B.; Andersson, Andreas J; Jokiel, Paul L.; Rodgers, Ku'ulei S.; Mackenzie, Fred T.

    2008-01-01

    Owing to anthropogenic emissions, atmospheric concentrations of carbon dioxide could almost double between 2006 and 2100 according to business-as-usual carbon dioxide emission scenarios1. Because the ocean absorbs carbon dioxide from the atmosphere2, 3, 4, increasing atmospheric carbon dioxide concentrations will lead to increasing dissolved inorganic carbon and carbon dioxide in surface ocean waters, and hence acidification and lower carbonate saturation states2, 5. As a consequence, it has been suggested that marine calcifying organisms, for example corals, coralline algae, molluscs and foraminifera, will have difficulties producing their skeletons and shells at current rates6, 7, with potentially severe implications for marine ecosystems, including coral reefs6, 8, 9, 10, 11. Here we report a seven-week experiment exploring the effects of ocean acidification on crustose coralline algae, a cosmopolitan group of calcifying algae that is ecologically important in most shallow-water habitats12, 13, 14. Six outdoor mesocosms were continuously supplied with sea water from the adjacent reef and manipulated to simulate conditions of either ambient or elevated seawater carbon dioxide concentrations. The recruitment rate and growth of crustose coralline algae were severely inhibited in the elevated carbon dioxide mesocosms. Our findings suggest that ocean acidification due to human activities could cause significant change to benthic community structure in shallow-warm-water carbonate ecosystems.

  20. Sensitivities of extant animal taxa to ocean acidification

    NASA Astrophysics Data System (ADS)

    Wittmann, Astrid C.; Pörtner, Hans-O.

    2013-11-01

    Anthropogenic CO2 emitted to the atmosphere is absorbed by the oceans, causing a progressive increase in ocean inorganic carbon concentrations and resulting in decreased water pH and calcium carbonate saturation. This phenomenon, called ocean acidification, is in addition to the warming effects of CO2 emissions. Ocean acidification has been reported to affect ocean biota, but the severity of this threat to ocean ecosystems (and humans depending on these ecosystems) is poorly understood. Here we evaluate the scale of this threat in the context of widely used representative concentration pathways (RCPs) by analysing the sensitivities of five animal taxa (corals, echinoderms, molluscs, crustaceans and fishes) to a wide range of CO2 concentrations. Corals, echinoderms and molluscs are more sensitive to RCP8.5 (936 ppm in 2100) than are crustaceans. Larval fishes may be even more sensitive than the lower invertebrates, but taxon sensitivity on evolutionary timescales remains obscure. The variety of responses within and between taxa, together with observations in mesocosms and palaeo-analogues, suggest that ocean acidification is a driver for substantial change in ocean ecosystems this century, potentially leading to long-term shifts in species composition.

  1. Coral calcifying fluid pH dictates response to ocean acidification

    PubMed Central

    Holcomb, M.; Venn, A. A.; Tambutté, E.; Tambutté, S.; Allemand, D.; Trotter, J.; McCulloch, M.

    2014-01-01

    Ocean acidification driven by rising levels of CO2 impairs calcification, threatening coral reef growth. Predicting how corals respond to CO2 requires a better understanding of how calcification is controlled. Here we show how spatial variations in the pH of the internal calcifying fluid (pHcf) in coral (Stylophora pistillata) colonies correlates with differential sensitivity of calcification to acidification. Coral apexes had the highest pHcf and experienced the smallest changes in pHcf in response to acidification. Lateral growth was associated with lower pHcf and greater changes with acidification. Calcification showed a pattern similar to pHcf, with lateral growth being more strongly affected by acidification than apical. Regulation of pHcf is therefore spatially variable within a coral and critical to determining the sensitivity of calcification to ocean acidification. PMID:24903088

  2. Effects of CO2-driven sediment acidification on infaunal marine bivalves: A synthesis.

    PubMed

    Clements, Jeff C; Hunt, Heather L

    2017-04-15

    While ocean acidification (OA) effects on marine organisms are well documented, impacts of sediment acidification on infaunal organisms are relatively understudied. Here we synthesize CO2-driven sediment acidification effects on infaunal marine bivalves. While sediment carbonate system conditions can already exceed near-future OA projections, sediments can become even more acidic as overlying seawater pH decreases. Evidence suggests that infaunal bivalves experience shell dissolution, more lesions, and increased mortality in more acidic sediments; effects on heavy metal accumulation appear complex and uncertain. Infaunal bivalves can avoid negative functional consequences of sediment acidification by reducing burrowing and increasing dispersal in more acidic sediments, irrespective of species or life stage; elevated temperature may compromise this avoidance behaviour. The combined effects of sediment acidification and other environmental stressors are virtually unknown. While it is evident that sediment acidification can impact infaunal marine bivalves, more research is needed to confidently predict effects under future ocean conditions.

  3. Exertional rhabdomyolysis: physiological response or manifestation of an underlying myopathy?

    PubMed Central

    Scalco, Renata S; Snoeck, Marc; Quinlivan, Ros; Treves, Susan; Laforét, Pascal; Jungbluth, Heinz; Voermans, Nicol C

    2016-01-01

    Exertional rhabdomyolysis is characterised by muscle breakdown associated with strenuous exercise or normal exercise under extreme circumstances. Key features are severe muscle pain and sudden transient elevation of serum creatine kinase (CK) levels with or without associated myoglobinuria. Mild cases may remain unnoticed or undiagnosed. Exertional rhabdomyolysis is well described among athletes and military personnel, but may occur in anybody exposed to unaccustomed exercise. In contrast, exertional rhabdomyolysis may be the first manifestation of a genetic muscle disease that lowers the exercise threshold for developing muscle breakdown. Repeated episodes of exertional rhabdomyolysis should raise the suspicion of such an underlying disorder, in particular in individuals in whom the severity of the rhabdomyolysis episodes exceeds the expected response to the exercise performed. The present review aims to provide a practical guideline for the acute management and postepisode counselling of patients with exertional rhabdomyolysis, with a particular emphasis on when to suspect an underlying genetic disorder. The pathophysiology and its clinical features are reviewed, emphasising four main stepwise approaches: (1) the clinical significance of an acute episode, (2) risks of renal impairment, (3) clinical indicators of an underlying genetic disorders and (4) when and how to recommence sport activity following an acute episode of rhabdomyolysis. Genetic backgrounds that appear to be associated with both enhanced athletic performance and increased rhabdomyolysis risk are briefly reviewed. PMID:27900193

  4. Extraction of Carbon Dioxide from Seawater by an Electrochemical Acidification Cell. Part 2 - Laboratory Scaling Studies

    DTIC Science & Technology

    2011-04-11

    Acidification Cell Part II—Laboratory Scaling Studies HeatHer D. Willauer Navy Technology Center for Safety and Survivability Chemistry Division Felice...an Electrochemical Acidification Cell Part II—Laboratory Scaling Studies Heather D. Willauer, Felice DiMascio,* Dennis R. Hardy, M. Kathleen Lewis...Unclassified Unclassified Unclassified UL 18 Heather D. Willauer (202) 767-2673 Electrochemical acidification cell Seawater pH Carbon dioxide An

  5. Ocean acidification increases copper toxicity differentially in two key marine invertebrates with distinct acid-base responses

    PubMed Central

    Lewis, Ceri; Ellis, Robert P.; Vernon, Emily; Elliot, Katie; Newbatt, Sam; Wilson, Rod W.

    2016-01-01

    Ocean acidification (OA) is expected to indirectly impact biota living in contaminated coastal environments by altering the bioavailability and potentially toxicity of many pH-sensitive metals. Here, we show that OA (pH 7.71; pCO2 1480 μatm) significantly increases the toxicity responses to a global coastal contaminant (copper ~0.1 μM) in two keystone benthic species; mussels (Mytilus edulis) and purple sea urchins (Paracentrotus lividus). Mussels showed an extracellular acidosis in response to OA and copper individually which was enhanced during combined exposure. In contrast, urchins maintained extracellular fluid pH under OA by accumulating bicarbonate but exhibited a slight alkalosis in response to copper either alone or with OA. Importantly, copper-induced damage to DNA and lipids was significantly greater under OA compared to control conditions (pH 8.14; pCO2 470 μatm) for both species. However, this increase in DNA-damage was four times lower in urchins than mussels, suggesting that internal acid-base regulation in urchins may substantially moderate the magnitude of this OA-induced copper toxicity effect. Thus, changes in metal toxicity under OA may not purely be driven by metal speciation in seawater and may be far more diverse than either single-stressor or single-species studies indicate. This has important implications for future environmental management strategies. PMID:26899803

  6. Extracellular enzyme kinetics scale with resource availability

    EPA Science Inventory

    Microbial community metabolism relies on external digestion, mediated by extracellular enzymes that break down complex organic matter into molecules small enough for cells to assimilate. We analyzed the kinetics of 40 extracellular enzymes that mediate the degradation and assimi...

  7. A case of mitochondrial cytopathy with exertion induced dystonia

    PubMed Central

    Chandra, Sadanandavalli Retnaswami; Issac, Thomas Gregor

    2015-01-01

    Paroxysmal dystonias are a group of relatively benign hyperkinetic childhood movement disorders of varied etiology. Mitochondrial diseases are well known to produce persistent dystonias as sequelae, but paroxysmal exertion induced dystonia has been reported in only one case to the best of our knowledge. Two siblings born to consanguineous parents presented with early-onset exertion induced dystonia, which was unresponsive to diphenylhydantoin and carbamazepine. A trial with valproate in one of the siblings turned fatal within 24 h. Based on this clue, the second child was investigated and found to suffer from complex I deficiency with a paternally inherited dominant nuclear DNA mutation, which is responsive to the mitochondrial cocktail. Exertion induced dystonia can be a rare manifestation of complex I deficiency. PMID:26557169

  8. Neutrophil Extracellular Traps and Microcrystals

    PubMed Central

    2017-01-01

    Neutrophil extracellular traps represent a fascinating mechanism by which PMNs entrap extracellular microbes. The primary purpose of this innate immune mechanism is thought to localize the infection at an early stage. Interestingly, the ability of different microcrystals to induce NET formation has been recently described. Microcrystals are insoluble crystals with a size of 1–100 micrometers that have different composition and shape. Microcrystals have it in common that they irritate phagocytes including PMNs and typically trigger an inflammatory response. This review is the first to summarize observations with regard to PMN activation and NET release induced by microcrystals. Gout-causing monosodium urate crystals, pseudogout-causing calcium pyrophosphate dehydrate crystals, cholesterol crystals associated with atherosclerosis, silicosis-causing silica crystals, and adjuvant alum crystals are discussed. PMID:28373994

  9. Analysis of Yeast Extracellular Vesicles.

    PubMed

    Rodrigues, Marcio L; Oliveira, Debora L; Vargas, Gabriele; Girard-Dias, Wendell; Franzen, Anderson J; Frasés, Susana; Miranda, Kildare; Nimrichter, Leonardo

    2016-01-01

    Extracellular vesicles (EV) are important carriers of biologically active components in a number of organisms, including fungal cells. Experimental characterization of fungal EVs suggested that these membranous compartments are likely involved in the regulation of several biological events. In fungal pathogens, these events include mechanisms of disease progression and/or control, suggesting potential targets for therapeutic intervention or disease prophylaxis. In this manuscript we describe methods that have been used in the last 10 years for the characterization of EVs produced by yeast forms of several fungal species. Experimental approaches detailed in this chapter include ultracentrifugation methods for EV fractionation, chromatographic approaches for analysis of EV lipids, microscopy techniques for analysis of both intracellular and extracellular vesicular compartments, interaction of EVs with host cells, and physical chemical analysis of EVs by dynamic light scattering.

  10. Extracellular secretion of recombinant proteins

    DOEpatents

    Linger, Jeffrey G.; Darzins, Aldis

    2014-07-22

    Nucleic acids encoding secretion signals, expression vectors containing the nucleic acids, and host cells containing the expression vectors are disclosed. Also disclosed are polypeptides that contain the secretion signals and methods of producing polypeptides, including methods of directing the extracellular secretion of the polypeptides. Exemplary embodiments include cellulase proteins fused to secretion signals, methods to produce and isolate these polypeptides, and methods to degrade lignocellulosic biomass.

  11. Diffusion in Brain Extracellular Space

    PubMed Central

    Syková, Eva; Nicholson, Charles

    2009-01-01

    Diffusion in the extracellular space (ECS) of the brain is constrained by the volume fraction and the tortuosity and a modified diffusion equation represents the transport behavior of many molecules in the brain. Deviations from the equation reveal loss of molecules across the blood-brain barrier, through cellular uptake, binding or other mechanisms. Early diffusion measurements used radiolabeled sucrose and other tracers. Presently, the real-time iontophoresis (RTI) method is employed for small ions and the integrative optical imaging (IOI) method for fluorescent macromolecules, including dextrans or proteins. Theoretical models and simulations of the ECS have explored the influence of ECS geometry, effects of dead-space microdomains, extracellular matrix and interaction of macromolecules with ECS channels. Extensive experimental studies with the RTI method employing the cation tetramethylammonium (TMA) in normal brain tissue show that the volume fraction of the ECS typically is about 20% and the tortuosity about 1.6 (i.e. free diffusion coefficient of TMA is reduced by 2.6), although there are regional variations. These parameters change during development and aging. Diffusion properties have been characterized in several interventions, including brain stimulation, osmotic challenge and knockout of extracellular matrix components. Measurements have also been made during ischemia, in models of Alzheimer's and Parkinson's diseases and in human gliomas. Overall, these studies improve our conception of ECS structure and the roles of glia and extracellular matrix in modulating the ECS microenvironment. Knowledge of ECS diffusion properties are valuable in contexts ranging from understanding extrasynaptic volume transmission to the development of paradigms for drug delivery to the brain. PMID:18923183

  12. A Technique for Establishing True Levels of Muscle Strength Exertion

    DTIC Science & Technology

    1980-01-01

    performed -"aximal or submaximal isometric strength exertions. The exertions tested were elbow flexion, finger flexion, knee flexion and knee...190.1 167.11 17.3350 Buttock-Knee Length (cm) 54.1 66.7 59.29 3.2106 Knee Height, sitting (cm) 46.5 58.7 52.91 2.8737 Shoulder- Elbow Length (cm) 29.3...propped the elbow of the right arm on the arm rest, extended the fore- arm directly forward so that the cuff was exactly above the load cell, with

  13. Microbial acidification and pH effects on trace element release from sewage sludge.

    PubMed

    Qureshi, Shabnam; Richards, Brian K; Steenhuis, Tammo S; McBride, Murray B; Baveye, Philippe; Dousset, Sylvie

    2004-11-01

    Leaching of sludge-borne trace elements has been observed in experimental and field studies. The role of microbial processes in the mobilization of trace elements from wastewater sludge is poorly defined. Our objectives were to determine trace element mobilization from sludge subjected to treatments representing microbial acidification, direct chemical acidification and no acidification, and to determine the readsorption potential of mobilized elements using calcareous sand. Triplicate columns (10-cm diameter) for incubation and leaching of sludge had a top layer of digested dewatered sludge (either untreated, acidified with H2SO4, or limed with CaCO3; all mixed with glass beads to prevent ponding) and a lower glass bead support bed. Glass beads in the sludge layer, support layer or both were replaced by calcareous sand in four treatments used for testing the readsorption potential of mobilized elements. Eight sequential 8-day incubation and leaching cycles were operated, each consisting of 7.6 d of incubation at 28 degrees C followed by 8 h of leaching with synthetic acid rain applied at 0.25 cm/h. Leachates were analyzed for trace elements, nitrate and pH, and sludge layer microbial respiration was measured. The largest trace element, nitrate and S losses occurred in treatments with the greatest pH depression and greatest microbial respiration rates. Cumulative leaching losses from both microbial acidification and direct acidification treatments were > 90% of Zn and 64-80% of Cu and Ni. Preventing acidification with sludge layer lime or sand restricted leaching for all trace elements except Mo. Results suggested that the primary microbial role in the rapid leaching of trace elements was acidification, with results from direct acidification being nearly identical to microbial acidification. Microbial activity in the presence of materials that prevented acidification mobilized far lower concentrations of trace elements, with the exception of Mo. Trace elements

  14. 20 CFR 404.1567 - Physical exertion requirements.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Physical exertion requirements. 404.1567 Section 404.1567 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  15. 20 CFR 404.1567 - Physical exertion requirements.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Physical exertion requirements. 404.1567 Section 404.1567 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  16. 20 CFR 404.1569a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 2 2011-04-01 2011-04-01 false Exertional and nonexertional limitations. 404.1569a Section 404.1569a Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  17. 20 CFR 404.1567 - Physical exertion requirements.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 2 2012-04-01 2012-04-01 false Physical exertion requirements. 404.1567 Section 404.1567 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  18. 20 CFR 404.1569a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 2 2014-04-01 2014-04-01 false Exertional and nonexertional limitations. 404.1569a Section 404.1569a Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  19. 20 CFR 404.1567 - Physical exertion requirements.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 2 2013-04-01 2013-04-01 false Physical exertion requirements. 404.1567 Section 404.1567 Employees' Benefits SOCIAL SECURITY ADMINISTRATION FEDERAL OLD-AGE, SURVIVORS AND DISABILITY INSURANCE (1950- ) Determining Disability and Blindness Vocational Considerations §...

  20. Perceived Exertion: An Old Exercise Tool Finds New Applications.

    ERIC Educational Resources Information Center

    Monahan, Terry

    1988-01-01

    Perceived exertion scales, based on subjective perception of energy output, are gaining respect as prescribing and monitoring tools for individual exercise programs. A review of recent literature indicates growing research interest in applications for individuals who are elderly, inactive, or subject to medical conditions such as angina. (IAH)

  1. 20 CFR 416.969a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... or restrictions imposed by your impairment(s) and related symptoms, such as pain, are exertional... imposed by your impairment(s) and related symptoms, such as pain, affect only your ability to meet...

  2. 20 CFR 404.1569a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... impairment(s) and related symptoms, such as pain, are exertional, nonexertional, or a combination of both. (b... symptoms, such as pain, affect only your ability to meet the strength demands of jobs (sitting,...

  3. 20 CFR 416.969a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... or restrictions imposed by your impairment(s) and related symptoms, such as pain, are exertional... imposed by your impairment(s) and related symptoms, such as pain, affect only your ability to meet...

  4. 20 CFR 404.1569a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... impairment(s) and related symptoms, such as pain, are exertional, nonexertional, or a combination of both. (b... symptoms, such as pain, affect only your ability to meet the strength demands of jobs (sitting,...

  5. 20 CFR 416.969a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... or restrictions imposed by your impairment(s) and related symptoms, such as pain, are exertional... imposed by your impairment(s) and related symptoms, such as pain, affect only your ability to meet...

  6. 20 CFR 404.1569a - Exertional and nonexertional limitations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ..., such as pain, may cause limitations of function or restrictions which limit your ability to meet... impairment(s) and related symptoms, such as pain, are exertional, nonexertional, or a combination of both. (b... symptoms, such as pain, affect only your ability to meet the strength demands of jobs (sitting,...

  7. Are the Measurements of Attention Allocation and Perceived Exertion Trustworthy?

    ERIC Educational Resources Information Center

    Meir, Gily; Hutchinson, Jasmin C.; Habeeb, Christine M.; Boiangin, Nataniel M.; Shaffer, Cory; Basevitch, Itay; Tenenbaum, Gershon

    2015-01-01

    Two studies examined the trustworthiness of commonly used measurement scales for ratings of perceived exertion (RPE) and state attentional focus (SAF) during exercise. In Study 1, participants (N = 24, 14 female) performed a treadmill graded-exercise test. The order of scale presentation during the task was manipulated (i.e., RPE followed by SAF…

  8. Perception of Forces Exerted by Objects in Collision Events

    ERIC Educational Resources Information Center

    White, Peter A.

    2009-01-01

    Impressions of force are commonplace in the visual perception of objects interacting. It is proposed that these impressions have their source in haptically mediated experiences of exertion of force in actions on objects. Visual impressions of force in interactions between objects occur by a kind of generalization of the proprioceptive impression…

  9. The impact of extracellular syntaxin4 on HaCaT keratinocyte behavior

    SciTech Connect

    Kadono, Nanako; Miyazaki, Takafumi; Okugawa, Yoji; Nakajima, Kiichiro; Hirai, Yohei

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer A subpopulation of syntaxin4 localizes extracellularly in the keratinocytes. Black-Right-Pointing-Pointer Epimorphin and syntaxin4 confer the resistance to the oxidative stress. Black-Right-Pointing-Pointer Epimorphin suppresses and syntaxin4 accelerates the CCE formation. Black-Right-Pointing-Pointer The antagonistic peptide to syntaxin4 blocks the syntaxin4-dependent CCE formation. -- Abstract: Syntaxin4 belongs to t-SNARE protein family and functions as a vesicular fusion mediator in the plasma membrane in a wide variety of cell types. This protein resembles another family member, epimorphin, a subpopulation of which has been shown to be secreted extracellularly in order to exert signaling functions. Here, we demonstrate the secretion of syntaxin4 via a non-classical pathway and its extracellular functions by using the functionally normal keratinocyte HaCaT. Extracellularly presented syntaxin4 appeared to elicit many cell responses similar to epimorphin with an important exception: it clearly facilitated keratinocyte cornification. The circularized peptide ST4n1 was synthesized from the putative functional core of syntaxin4 (a.a. 103-108), which is equivalent to the previously generated antagonist of epimorphin, and neutralized this contradictory effect. Intriguingly, an epimorphin mutant (EP4M) in which the functional core was replaced by that of syntaxin4 behaved like epimorphin, which was again antagonized by ST4n1. Electrophoresis-based analyses demonstrated the distinct structure of syntaxin4 compared to epimorphin or EP4M. These results revealed, for the first time, the extracellular role of syntaxin4 and shed light on the division of the extracellular effects exerted by epimorphin and syntaxin4 on keratinocyte cornification.

  10. Essential Role for Vacuolar Acidification in Candida albicans Virulence*

    PubMed Central

    Patenaude, Cassandra; Zhang, Yongqiang; Cormack, Brendan; Köhler, Julia; Rao, Rajini

    2013-01-01

    Fungal infections are on the rise, with mortality above 30% in patients with septic Candida infections. Mutants lacking V-ATPase activity are avirulent and fail to acidify endomembrane compartments, exhibiting pleiotropic defects in secretory, endosomal, and vacuolar pathways. However, the individual contribution of organellar acidification to virulence and its associated traits is not known. To dissect their separate roles in Candida albicans pathogenicity we generated knock-out strains for the V0 subunit a genes VPH1 and STV1, which target the vacuole and secretory pathway, respectively. While the two subunits were redundant in many vma phenotypes, such as alkaline pH sensitivity, calcium homeostasis, respiratory defects, and cell wall integrity, we observed a unique contribution of VPH1. Specifically, vph1Δ was defective in acidification of the vacuole and its dependent functions, such as metal ion sequestration as evidenced by hypersensitivity to Zn2+ toxicity, whereas stv1Δ resembled wild type. In growth conditions that elicit morphogenic switching, vph1Δ was defective in forming hyphae whereas stv1Δ was normal or only modestly impaired. Host cell interactions were evaluated in vitro using the Caco-2 model of intestinal epithelial cells, and murine macrophages. Like wild type, stv1Δ was able to inflict cellular damage in Caco-2 and macrophage cells, as assayed by LDH release, and escape by filamentation. In contrast, vph1Δ resembled a vma7Δ mutant, with significant attenuation in host cell damage. Finally, we show that VPH1 is required for fungal virulence in a murine model of systemic infection. Our results suggest that vacuolar acidification has an essential function in the ability of C. albicans to form hyphae and establish infection. PMID:23884420

  11. Hydrodynamic Regimes Affect Coral Reef Resilience to Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Teneva, L. T.; Dunbar, R. B.; Koseff, J. R.; Fleischfresser, J. D.; Koweek, D.

    2013-05-01

    Caribbean reefs hold tremendous value as sources of food, income, coastal protection, in addition to their cultural significance. Recently, studies showed that Caribbean reef growth has been surpassed in places by excessive rates of erosion due to climate change. The rates of coral reef response to ocean pH changes and warming and the implications for ecosystem resilience remain largely unknown. One way to investigate the potential structural resilience of reefs to climate change is to measure the physical oceanographic conditions in the area. Determining the hydrodynamic regimes and residence time of water in a particular reef environment is crucial to understanding the rates of future warming and acidification a reef site would experience. Our work on Pacific Islands' hydrodynamics - Central Equatorial Pacific, Great Barrier Reef, and Western Pacific -- would be of interest to Caribbean physical oceanographers and coral reef scientists. We use a combination of Acoustic Doppler Current Profilers, Acoustic Doppler Velocimeters, temperature and salinity sensors, and pressure sensors to characterize reef hydrodynamic regimes. Our work indicates that shallower, more protected reef habitats are characterized by longer residence times, their biological signals are strongly tidally modulated, essentially subjecting such habitats to higher rates of warming and acidification in the future. Reef crest environments and fore reef habitats, on the other hand, are well-mixed with open-ocean water. The hydrodynamic regimes there condition such reef sites to more attenuated temperature and pH ranges, conditions more typical of the open ocean. Our work suggests that investigating the geomorphology and resulting localized hydrodynamics in a reef area can provide insights into the relative rates at which a reef could resist or succumb to impacts of ocean acidification. Such information for different reef islands, in the Pacific or Caribbean basins, could provide helpful insights

  12. Early detection of ocean acidification effects on marine calcification

    SciTech Connect

    Ilyina, T.; Zeebe, R. E.; E. Maier-Reimer; C. Heinze

    2009-02-19

    Ocean acidification is likely to impact calcification rates in many pelagic organisms, which may in turn cause significant changes in marine ecosystem structure. We examine effects of changes in marine CaCO3 production on total alkalinity (TA) in the ocean using the global biogeochemical ocean model HAMOCC. We test a variety of future calcification scenarios because experimental studies with different organisms have revealed a wide range of calcification sensitivities to CaCO3 saturation state. The model integrations start at a preindustrial steady state in the year 1800 and run until the year 2300 forced with anthropogenic CO2 emissions. Calculated trends in TA are evaluated taking into account the natural variability in ocean carbonate chemistry, as derived from repeat hydrographic transects. We conclude that the data currently available does not allow discerning significant trends in TA due to changes in pelagic calcification caused by ocean acidification. Given different calcification scenarios, our model calculations indicate that the TA increase over time will start being detectable by the year 2040, increasing by 5–30 umol/kg compared to the present-day values. In a scenario of extreme reductions in calcification, large TA changes relative to preindustrial conditions would have occurred at present, which we consider very unlikely. However, the time interval of reliable TA observations is too short to disregard this scenario. The largest increase in surface ocean TA is predicted for the tropical and subtropical regions. In order to monitor and quantify possible early signs of acidification effects, we suggest to specifically target those regions during future ocean chemistry surveys.

  13. Ocean acidification reduces the crystallographic control in juvenile mussel shells.

    PubMed

    Fitzer, Susan C; Cusack, Maggie; Phoenix, Vernon R; Kamenos, Nicholas A

    2014-10-01

    Global climate change threatens the oceans as anthropogenic carbon dioxide causes ocean acidification and reduced carbonate saturation. Future projections indicate under saturation of aragonite, and potentially calcite, in the oceans by 2100. Calcifying organisms are those most at risk from such ocean acidification, as carbonate is vital in the biomineralisation of their calcium carbonate protective shells. This study highlights the importance of multi-generational studies to investigate how marine organisms can potentially adapt to future projected global climate change. Mytilus edulis is an economically important marine calcifier vulnerable to decreasing carbonate saturation as their shells comprise two calcium carbonate polymorphs: aragonite and calcite. M. edulis specimens were cultured under current and projected pCO2 (380, 550, 750 and 1000μatm), following 6months of experimental culture, adults produced second generation juvenile mussels. Juvenile mussel shells were examined for structural and crystallographic orientation of aragonite and calcite. At 1000μatm pCO2, juvenile mussels spawned and grown under this high pCO2 do not produce aragonite which is more vulnerable to carbonate under-saturation than calcite. Calcite and aragonite were produced at 380, 550 and 750μatm pCO2. Electron back scatter diffraction analyses reveal less constraint in crystallographic orientation with increased pCO2. Shell formation is maintained, although the nacre crystals appear corroded and crystals are not so closely layered together. The differences in ultrastructure and crystallography in shells formed by juveniles spawned from adults in high pCO2 conditions may prove instrumental in their ability to survive ocean acidification.

  14. Ocean acidification and warming scenarios increase microbioerosion of coral skeletons.

    PubMed

    Reyes-Nivia, Catalina; Diaz-Pulido, Guillermo; Kline, David; Guldberg, Ove-Hoegh; Dove, Sophie

    2013-06-01

    Biological mediation of carbonate dissolution represents a fundamental component of the destructive forces acting on coral reef ecosystems. Whereas ocean acidification can increase dissolution of carbonate substrates, the combined impact of ocean acidification and warming on the microbioerosion of coral skeletons remains unknown. Here, we exposed skeletons of the reef-building corals, Porites cylindrica and Isopora cuneata, to present-day (Control: 400 μatm - 24 °C) and future pCO2 -temperature scenarios projected for the end of the century (Medium: +230 μatm - +2 °C; High: +610 μatm - +4 °C). Skeletons were also subjected to permanent darkness with initial sodium hypochlorite incubation, and natural light without sodium hypochlorite incubation to isolate the environmental effect of acidic seawater (i.e., Ωaragonite <1) from the biological effect of photosynthetic microborers. Our results indicated that skeletal dissolution is predominantly driven by photosynthetic microborers, as samples held in the dark did not decalcify. In contrast, dissolution of skeletons exposed to light increased under elevated pCO2 -temperature scenarios, with P. cylindrica experiencing higher dissolution rates per month (89%) than I. cuneata (46%) in the high treatment relative to control. The effects of future pCO2 -temperature scenarios on the structure of endolithic communities were only identified in P. cylindrica and were mostly associated with a higher abundance of the green algae Ostreobium spp. Enhanced skeletal dissolution was also associated with increased endolithic biomass and respiration under elevated pCO2 -temperature scenarios. Our results suggest that future projections of ocean acidification and warming will lead to increased rates of microbioerosion. However, the magnitude of bioerosion responses may depend on the structural properties of coral skeletons, with a range of implications for reef carbonate losses under warmer and more acidic oceans.

  15. Predicting soil and water acidification: proceedings of a workshop

    SciTech Connect

    Johnson, D.W.

    1985-01-01

    A three-day workshop was held at the Hilton Hotel in Knoxville, Tennessee on March 27-29, 1984, preceded by a one-day tour of sites at or near ORNL. Funding for the workshop was provided by the National Acid Precipitation Assessment Program by the US Environmental Protection Agency. One of the goals of this workshop was to develop a consensus among the participant as to sensitivity criteria for acid deposition effects on both soils and surface waters. As the meeting evolved, the workshop participants spent most of their time in a very productive discussion of important processes and hypotheses regarding soil and water acidification, primarily from the theoretical standpoint, using empirical data to illustrate specific points. Only in the afternoon of the last day were sensitivity criteria as such as discussed, but all of the preceding discussions clearly related to this issue as well. The workshop discussions, including sensitivity criteria, are summarized in this document. A major highlight of this workshop was a meeting of minds among aquatic and terrestrial scientists as to important mechanisms for surface water acidification. This paved the way for assessment activities, probably is association with modeling efforts. No such consensus or knowledge is available for forest effects, however, because the important mechanisms of forest effects are not known. A concensus was reached as to appropriate sensitivity criteria for soil acidification and aluminum mobilization but there was no consensus as to whether these processes in themselves are responsible for reported widespread forest dieback and decline. Thus, assigning forest effects sensitivity criteria at this time would be premature. Two major areas of research were identified as most in need of further research: nitrogen cycling and soil weathering.

  16. Effect of acidification on metal uptake of Picea abies seedlings

    SciTech Connect

    Paeivaerinta, J.; Lodenius, M. )

    1994-03-01

    The effects of air pollutants on forest ecosystems are based on complex interactions where no single dominating factor has been found. The reasons for forest die-back are extremely difficult to determine because of the lack of long-term data and the difficulties in determining the [open quotes]normal[close quotes] state of the forest ecosystems. The forest die-back in central Europe has been interpreted by many different theories. According to the stress hypothesis all stress factors are summed together so that the limits of biological stress tolerance of different organisms can be exceeded. One potential stress factor is soil acidification. Anthropogenic pollutants increase soil acidification, which is known to increase the solubility of many metals. This has raised the question whether metals could be one potential stress factor to forest organisms. Root growth and the uptake of nutrients and water are in some cases sensible parameters of metal toxicity. Although metals are not the main factor in forest decline, it is important to understand the role of metals as a stress factor on forest ecosystems. Metal uptake by different plant species, especially trees, is unclear. For example the synergistic and antagonistic effects of different metals in plant tissues and the availability of organic metal complexes are still unknown. Plant roots also play an important active role in mobilizing metals from soil particles by producing organic compounds that are effective in releasing substances bound to soil particles. It is important to study the quantities of metals taken up by forest plants because plants are one way for soil metals to enter forest food chains. It is also important to know whether metals can accumulate into plants in concentrations harmful to the plant itself. This study was designed to determine whether metal uptake by Norway spruce is dependent on acidification or humus content of the soil. 20 refs., 6 figs., 2 tabs.

  17. Ocean warming-acidification synergism undermines dissolved organic matter assembly.

    PubMed

    Chen, Chi-Shuo; Anaya, Jesse M; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors--warming and acidification--threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow--even hinder--the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming-acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected.

  18. Voltage-dependent and -independent titration of specific residues accounts for complex gating of a ClC chloride channel by extracellular protons

    PubMed Central

    Niemeyer, María Isabel; Cid, L Pablo; Yusef, Yamil R; Briones, Rodolfo; Sepúlveda, Francisco V

    2009-01-01

    The ClC transport protein family comprises both Cl− ion channel and H+/Cl− and H+/NO3− exchanger members. Structural studies on a bacterial ClC transporter reveal a pore obstructed at its external opening by a glutamate side-chain which acts as a gate for Cl− passage and in addition serves as a staging post for H+ exchange. This same conserved glutamate acts as a gate to regulate Cl− flow in ClC channels. The activity of ClC-2, a genuine Cl− channel, has a biphasic response to extracellular pH with activation by moderate acidification followed by abrupt channel closure at pH values lower than ∼7. We have now investigated the molecular basis of this complex gating behaviour. First, we identify a sensor that couples extracellular acidification to complete closure of the channel. This is extracellularly-facing histidine 532 at the N-terminus of transmembrane helix Q whose neutralisation leads to channel closure in a cooperative manner. We go on to show that acidification-dependent activation of ClC-2 is voltage dependent and probably mediated by protonation of pore gate glutamate 207. Intracellular Cl− acts as a voltage-independent modulator, as though regulating the pKa of the protonatable residue. Our results suggest that voltage dependence of ClC-2 is given by hyperpolarisation-dependent penetration of protons from the extracellular side to neutralise the glutamate gate deep within the channel, which allows Cl− efflux. This is reminiscent of a partial exchanger cycle, suggesting that the ClC-2 channel evolved from its transporter counterparts. PMID:19153159

  19. Toxicity of Eosinophil MBP Is Repressed by Intracellular Crystallization and Promoted by Extracellular Aggregation

    PubMed Central

    Soragni, Alice; Yousefi, Shida; Stoeckle, Christina; Soriaga, Angela B.; Sawaya, Michael R.; Kozlowski, Evelyne; Schmid, Inès; Radonjic-Hoesli, Susanne; Boutet, Sebastien; Williams, Garth J.; Messerschmidt, Marc; Seibert, M. Marvin; Cascio, Duilio; Zatsepin, Nadia A.; Burghammer, Manfred; Riekel, Christian; Colletier, Jacques-Philippe; Riek, Roland; Eisenberg, David; Simon, Hans-Uwe

    2016-01-01

    SUMMARY Eosinophils are white blood cells that function in innate immunity and participate in the pathogenesis of various inflammatory and neoplastic disorders. Their secretory granules contain four cytotoxic proteins, including the eosinophil major basic protein (MBP-1). How MBP-1 toxicity is controlled within the eosinophil itself and activated upon extracellular release is unknown. Here we show how intragranular MBP-1 nanocrystals restrain toxicity, enabling its safe storage, and characterize them with an X-ray-free electron laser. Following eosinophil activation, MBP-1 toxicity is triggered by granule acidification, followed by extracellular aggregation, which mediates the damage to pathogens and host cells. Larger non-toxic amyloid plaques are also present in tissues of eosinophilic patients in a feedback mechanism that likely limits tissue damage under pathological conditions of MBP-1 oversecretion. Our results suggest that MBP-1 aggregation is important for innate immunity and immunopathology mediated by eosinophils and clarify how its polymorphic self-association pathways regulate toxicity intra- and extracellularly. PMID:25728769

  20. Rates of Ocean Acidification: Decoupling of Planktic and Benthic Extinctions?

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Alegret, L.

    2012-12-01

    Deep-sea benthic organisms derive food from export of organic matter produced in the photic zone, so that pelagic and benthic productivity are coupled, suggesting that severe extinction of plankton and benthos in the geological past should have been coupled. An asteroid impact at the Cretaceous/Paleogene (K/Pg) boundary (~65 Ma), however, caused mass extinction of calcifying plankton (foraminifera and nannoplankton), whereas benthic calcifyers (foraminifera) did not suffer significant extinction. Also, pelagic calcifyers did not suffer severe extinction during the carbon-cycle perturbation and global warming at the Paleocene-Eocene (P/E) boundary 10 myr later, when deep-sea benthic foraminifera did. The K/Pg extinction has been interpreted as darkness-caused collapse of productivity, but this is not supported by the lack of benthic extinction. To evaluate extinction mechanisms, we compared benthic foraminiferal and stable isotope records at ODP sites in the Pacific, SE Atlantic and Southern Oceans. Across the K/Pg boundary, the decrease in export productivity was moderate, regionally variable, and insufficient to explain the mass extinction at higher levels of the food chain. Across the P/E boundary, productivity increased in epicontinental seas and on continental margins, whereas pelagic productivity may have declined (increased trophic resource continuum). We thus found no evidence that the different benthic and pelagic extinction patterns at K/Pg and P/E were linked to changes in (export) productivity. Instead, the difference between planktic and benthic extinction patterns may have been caused by the occurrence of ocean acidification at different rates. Very rapid (faster than present anthropogenic) surface ocean acidification at the K/Pg boundary may have been due to influx of impact-generated nitric acid, followed by rapid oceanic buffering. This may have been a factor in the massive extinction of pelagic calcifyers, ammonites and top-level predators such as

  1. Episodic acidification of a coastal plain stream in Virginia

    USGS Publications Warehouse

    O'Brien, A. K.; Eshleman, K.N.

    1996-01-01

    This study investigates the episodic acidification of Reedy Creek, a wetland-influenced coastal plain stream near Richmond, Virginia. Primary objectives of the study were to quantify the episodic variability of acid- base chemistry in Reedy Creek, to examine the seasonal variability in episodic response and to explain the hydrological and geochemical factors that contribute to episodic acidification. Chemical response was similar in each of the seven storms examined, however, the ranges in concentrations observed were commonly greater in summer/fall storms than in winter/spring storms. An increase in SO4/2- concentration with discharge was observed during all storms and peak concentration occurred at or near peak flow. Small increases in Mg2+, Ca2+, K+ concentrations and dissolved organic carbon (DOC) were observed during most storms. At the same time, ANC, Na+ and Cl- concentrations usually decreased with increasing discharge. In summer/fall storms, the absolute increase in SO4/2- concentration was one-third to 15 times the increase observed in winter/spring storms; the decrease in ANC during summer/fall storms was usually within the range of the decrease observed in winter/spring storms. In contrast, the decrease in Na+ and Cl- concentrations during winter/spring storms was much greater than that observed during summer/fall storms. Data show that while base flow anion deficit was higher in summer/fall than in winter/spring, anion deficit decreased during most summer/fall storms. In contrast, base flow anion deficit was lower in spring and winter, but increased during winter/spring storms. Increased SO4/2- concentration was the main cause of episodic acidification during storms at Reedy Creek, but increased anion deficit indicates organic acids may contribute to episodic acidification during winter/spring storms. Changes in SO4/2- concentration coincident with the hydrograph rise indicate quick routing of water through the watershed. Saturation overland flow

  2. Effects of Seawater Acidification on the Life Cycle and fitness of Opossum Shrimp Populations

    EPA Science Inventory

    Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known ph...

  3. Climate impacts on ocean acidification in the North Sea and Baltic Sea: a modelling study

    NASA Astrophysics Data System (ADS)

    Daewel, Ute; Schrum, Corinna; Pushpadas, Dhanya

    2013-04-01

    CO2 increase in the atmosphere does not only potentially change the overall climate, but also increase the dissolved inorganic carbon (DIC) content in the ocean by ocean-atmosphere gas exchange leading to a decrease in oceanic ph (acidification). Hence, it has both direct (via acidification) and indirect (via changes in atmospheric fields) implications for marine ecosystems and their productivity. On the other hand, changes in primary production would likewise impact the DIC content and could potentially alter the process of acidification on different temporal scales (seasonal, inter-annual, and decadal). Here, we extended the 3d coupled ecosystem model ECOSMO II by formulations for carbon chemistry and applied the model system to the North Sea and Baltic Sea in order to investigate ocean acidification in that specific region. We specifically aim in disentangling direct and indirect impacts of changes in atmospheric CO2 on acidification. Therefore we will first, present results from a multi-decadal model hind cast (1948-2008) to describe the dynamics in ocean acidification with respect to the different time scales. Secondly, we apply downscaled products from General Circulation Models to project future climate impacts (2070-2100) on acidification. And thirdly, we will present results from cross-experiments, where we investigate the influence of future CO2 increase under present day atmospheric condition and vice versa. These scenarios allow disentangling the direct and indirect impacts on the process of acidification comparative in the North Sea and Baltic Sea.

  4. Effects of Seawater Acidification on the Liffe Cycle and Fitness of Opossum Shrimp Population

    EPA Science Inventory

    Much of the current concern about ecological effects of ocean acidification focuses on molluscs and coccolithophores because of their importance in the global calcium cycle. However, many other marine organisms are likely to be affected by acidification because of their known se...

  5. Dynamics of transparent exopolymeric particles and their precursors during a mesocosm experiment: Impact of ocean acidification

    NASA Astrophysics Data System (ADS)

    Bourdin, Guillaume; Gazeau, Frédéric; Kerros, Marie-Emmanuelle; Marro, Sophie; Pedrotti, Maria Luiza

    2017-02-01

    The dissolution of anthropogenic atmospheric CO2 in seawater is suspected to exert a strong pressure on biological processes as well as on carbon and nutrient cycles. Transparent exopolymeric particles (TEP) are polysaccharide particles, formed by aggregation of polymers exuded by phytoplankton and strongly involved in organic matter sedimentation. A mesocosm experiment was performed from February to March 2013 in the coastal waters of the Northwestern Mediterranean Sea, a region characterised by low-nutrient low-chlorophyll (LNLC) levels. We aimed to determine the effect of ocean acidification on the organic carbon pool of TEP produced by a natural phytoplankton community. The experiment was conducted in nine mesocosms of 50 m3 deployed for 12 days, and subjected to seven partial pressures of CO2 (pCO2) levels: one control level in triplicate and six elevated levels between 450 and 1250 μatm. The use of different analytical methods allowed the assessment of TEP density, volume concentration and size distribution as well as both TEP and TEP precursors carbon content. TEP contributed vastly to the particulate organic carbon pool (∼62%), and were mainly produced by small-sized phytoplankton such as pico- and nanophytoplankton. TEP precursors carbon content represented three times the carbon content of particulate TEP, showing that this pool has to be considered in experiments focused on the environmental control of TEP production. There was no evidence that TEP and TEP precursors were dependent on pCO2. These parameters exhibited clear temporal dynamics, with tight links to community composition, nutrient availability and other environmental parameters.

  6. Mechanotransduction and extracellular matrix homeostasis

    PubMed Central

    Humphrey, Jay D.; Dufresne, Eric R.; Schwartz, Martin A.

    2015-01-01

    Preface Soft connective tissues at steady state are yet dynamic; resident cells continually read environmental cues and respond to promote homeostasis, including maintenance of the mechanical properties of the extracellular matrix that are fundamental to cellular and tissue health. The mechanosensing process involves assessment of the mechanics of the matrix by the cells through integrins and the actomyosin cytoskeleton, and is followed by a mechano-regulation process that includes the deposition, rearrangement, or removal of matrix to maintain overall form and function. Progress toward understanding the molecular, cellular, and tissue scale effects that promote mechanical homeostasis has helped identify key questions for future research. PMID:25355505

  7. Effects of hyperglycemia on lonidamine-induced acidification and de-energization of human melanoma xenografts and sensitization to melphalan.

    PubMed

    Nath, Kavindra; Nelson, David S; Heitjan, Daniel F; Zhou, Rong; Leeper, Dennis B; Glickson, Jerry D

    2015-03-01

    We seek to exploit the natural tendency of melanomas and other tumors to convert glucose to lactate as a method for the selective intracellular acidification of cancer cells and for the potentiation of the activity of nitrogen-mustard antineoplastic agents. We performed this study to evaluate whether the induction of hyperglycemia (26 mM) could enhance the effects of lonidamine (LND, 100 mg/kg; intraperitoneally) on the induction of intracellular acidification, bioenergetic decline and potentiation of the activity of melphalan (LPAM) against DB-1 melanoma xenografts in mice. Intracellular pH (pHi ), extracellular pH (pHe ) and bioenergetics (β-nucleoside triphosphate to inorganic phosphate ratio, β-NTP/Pi) were reduced by 0.7 units (p < 0.001), 0.3 units (p > 0.05) and 51.4% (p < 0.05), respectively. The therapeutic response to LPAM (7.5 mg/kg; intravenously) + LND (100 mg/kg; intraperitoneally) was reduced by about a factor of three under hyperglycemic conditions relative to normoglycemia, producing a growth delay of 7.76 days (tumor doubling time, 5.31 days; cell kill, 64%) compared with LND alone of 1.70 days and LPAM alone of 0.29 days. Under normoglycemic conditions, LND plus LPAM produced a growth delay of 17.75 days, corresponding to a cell kill of 90% at the same dose for each of these agents. The decrease in tumor cell kill under hyperglycemic conditions correlates with an increase in tumor ATP levels resulting from increased glycolytic activity. However, hyperglycemia substantially increases lactic acid production in tumors by a factor of approximately six (p < 0.05), but hyperglycemia did not increase the effects of LND on acidification of the tumor, most probably because of the strong buffering action of carbon dioxide (the pKa of carbonic acid is 6.4). Therefore, this study demonstrates that the addition of glucose during treatment with LND diminishes the activity of this agent.

  8. Plasma and lymphocyte Hsp72 responses to exercise in athletes with prior exertional heat illness.

    PubMed

    Ruell, Patricia A; Simar, David; Périard, Julien D; Best, Stuart; Caillaud, Corinne; Thompson, Martin W

    2014-06-01

    We investigated the effect of exercise in the heat on both intracellular and extracellular Hsp72 in athletes with a prior history of exertional heat illness (EHI). Two groups of runners, one consisting of athletes who had a previous history of EHI, and a control group (CON) of similar age (29.7 ± 1.2 and 29.1 ± 2 years CON vs. EHI) and fitness [maximal oxygen consumption [Formula: see text] 65.7 ± 2 and 64.5 ± 3 ml kg(-1) min(-1) CON vs. EHI] were recruited. Seven subjects in each group ran on a treadmill for 1 h at 72 % [Formula: see text] in warm conditions (30 °C, 40 % RH) reaching rectal temperatures of ~39.3 (CON) and ~39.2 °C (EHI). Blood was collected every 10 min during exercise and plasma was analysed for extracellular Hsp72. Intracellular Hsp72 levels were measured in both monocytes and lymphocytes before and immediately after the 60-min run, and then after 1 h recovery at an ambient temperature of 24 °C. Plasma Hsp72 increased from 1.18 ± 0.14 and 0.86 ± 0.08 ng/ml (CON vs. EHI) at rest to 4.56 ± 0.63 and 4.04 ± 0.45 ng/ml (CON vs. EHI, respectively) at the end of exercise (p < 0.001), with no difference between groups. Lymphocyte Hsp72 was lower in the EHI group at 60 min of exercise (p < 0.05), while monocyte Hsp72 was not different between groups. The results of the present study suggest that the plasma Hsp72 response to exercise in athletes with a prior history of EHI remained similar to that of the CON group, while the lymphocyte Hsp72 response was reduced.

  9. Extracellular protons acidify osteoclasts, reduce cytosolic calcium, and promote expression of cell-matrix attachment structures.

    PubMed Central

    Teti, A; Blair, H C; Schlesinger, P; Grano, M; Zambonin-Zallone, A; Kahn, A J; Teitelbaum, S L; Hruska, K A

    1989-01-01

    Because metabolic acids stimulate bone resorption in vitro and in vivo, we focused on the cellular events produced by acidosis that might be associated with stimulation of bone remodeling. To this end, we exposed isolated chicken osteoclasts to a metabolic (butyric) acid and observed a fall in both intracellular pH and cytosolic calcium [( Ca2+]i). These phenomena were recapitulated when bone resorptive cells, alkalinized by HCO3 loading, were transferred to a bicarbonate-free environment. The acid-induced decline in osteoclast [Ca2+]i was blocked by either NaCN or Na3VO4, in a Na+-independent fashion, despite the failure of each inhibitor to alter stimulated intracellular acidification. Moreover, K+-induced membrane depolarization also reduced cytosolic calcium in a manner additive to the effect of protons. These findings suggest that osteoclasts adherent to bone lack functional voltage-operated Ca2+ channels, and they reduced [Ca2+]i in response to protons via a membrane residing Ca-ATPase. Most importantly, acidosis enhances formation of podosomes, the contact areas of the osteoclast clear zone, indicating increased adhesion to substrate, an early step in bone resorption. Thus, extracellular acidification of osteoclasts leads to decrements in intracellular pH and calcium, and appears to promote cell-matrix attachment. Images PMID:2547838

  10. Extracellular electrical recording of pH-triggered bursts in C6 glioma cell populations

    PubMed Central

    Rocha, Paulo R. F.; Medeiros, Maria C. R.; Kintzel, Ulrike; Vogt, Johannes; Araújo, Inês M.; Mestre, Ana L. G.; Mailänder, Volker; Schlett, Paul; Dröge, Melanie; Schneider, Leonid; Biscarini, Fabio; de Leeuw, Dago M.; Gomes, Henrique L.

    2016-01-01

    Glioma patients often suffer from epileptic seizures because of the tumor’s impact on the brain physiology. Using the rat glioma cell line C6 as a model system, we performed long-term live recordings of the electrical activity of glioma populations in an ultrasensitive detection method. The transducer exploits large-area electrodes that maximize double-layer capacitance, thus increasing the sensitivity. This strategy allowed us to record glioma electrical activity. We show that although glioma cells are nonelectrogenic, they display a remarkable electrical burst activity in time. The low-frequency current noise after cell adhesion is dominated by the flow of Na+ ions through voltage-gated ion channels. However, after an incubation period of many hours, the current noise markedly increased. This electric bursting phenomenon was not associated with apoptosis because the cells were viable and proliferative during the period of increased electric activity. We detected a rapid cell culture medium acidification accompanying this event. By using specific inhibitors, we showed that the electrical bursting activity was prompted by extracellular pH changes, which enhanced Na+ ion flux through the psalmotoxin 1–sensitive acid-sensing ion channels. Our model of pH-triggered bursting was unambiguously supported by deliberate, external acidification of the cell culture medium. This unexpected, acidosis-driven electrical activity is likely to directly perturb, in vivo, the functionality of the healthy neuronal network in the vicinity of the tumor bulk and may contribute to seizures in glioma patients. PMID:28028533

  11. Persistence of Positive Carryover Effects in the Oyster, Saccostrea glomerata, following Transgenerational Exposure to Ocean Acidification.

    PubMed

    Parker, Laura M; O'Connor, Wayne A; Raftos, David A; Pörtner, Hans-Otto; Ross, Pauline M

    2015-01-01

    Ocean acidification (OA) is predicted to have widespread implications for marine organisms, yet the capacity for species to acclimate or adapt over this century remains unknown. Recent transgenerational studies have shown that for some marine species, exposure of adults to OA can facilitate positive carryover effects to their larval and juvenile offspring that help them to survive in acidifying oceanic conditions. But whether these positive carryover effects can persist into adulthood or the next generation is unknown. Here we tested whether positive carryover effects found in larvae of the oyster, Saccostrea glomerata following transgenerational exposure to elevated CO2, could persist into adulthood and whether subsequent transgenerational exposure of adults to elevated CO2 would facilitate similar adaptive responses in the next generation of larvae and juveniles. Following our previous transgenerational exposure of parental adults and first generation (F1) larvae to ambient (385 μatm) and elevated (856 μatm) CO2, newly settled F1 juveniles were transferred to the field at ambient CO2 for 14 months, until they reached reproductive maturity. At this time, the F1 adults were returned to the laboratory and the previous transgenerational CO2 exposure was repeated to produce F2 offspring. We found that the capacity of adults to regulate extracellular pH at elevated CO2 was improved if they had a prior history of transgenerational exposure to elevated CO2. In addition, subsequent transgenerational exposure of these adults led to an increase in the resilience of their larval and juvenile offspring. Offspring with a history of transgenerational exposure to elevated CO2 had a lower percentage abnormality, faster development rate, faster shell growth and increased heart rate at elevated CO2 compared with F2 offspring with no prior history of exposure to elevated CO2. Our results suggest that positive carryover effects originating during parental and larval exposure will

  12. Next-century ocean acidification and warming both reduce calcification rate, but only acidification alters skeletal morphology of reef-building coral Siderastrea siderea

    PubMed Central

    Horvath, Kimmaree M.; Castillo, Karl D.; Armstrong, Pualani; Westfield, Isaac T.; Courtney, Travis; Ries, Justin B.

    2016-01-01

    Atmospheric pCO2 is predicted to rise from 400 to 900 ppm by year 2100, causing seawater temperature to increase by 1–4 °C and pH to decrease by 0.1–0.3. Sixty-day experiments were conducted to investigate the independent and combined impacts of acidification (pCO2 = 424–426, 888–940 ppm-v) and warming (T = 28, 32 °C) on calcification rate and skeletal morphology of the abundant and widespread Caribbean reef-building scleractinian coral Siderastrea siderea. Hierarchical linear mixed-effects modelling reveals that coral calcification rate was negatively impacted by both warming and acidification, with their combined effects yielding the most deleterious impact. Negative effects of warming (32 °C/424 ppm-v) and high-temperature acidification (32 °C/940 ppm-v) on calcification rate were apparent across both 30-day intervals of the experiment, while effects of low-temperature acidification (28 °C/888 ppm-v) were not apparent until the second 30-day interval—indicating delayed onset of acidification effects at lower temperatures. Notably, two measures of coral skeletal morphology–corallite height and corallite infilling–were negatively impacted by next-century acidification, but not by next-century warming. Therefore, while next-century ocean acidification and warming will reduce the rate at which corals build their skeletons, next-century acidification will also modify the morphology and, potentially, function of coral skeletons. PMID:27470426

  13. Next-century ocean acidification and warming both reduce calcification rate, but only acidification alters skeletal morphology of reef-building coral Siderastrea siderea.

    PubMed

    Horvath, Kimmaree M; Castillo, Karl D; Armstrong, Pualani; Westfield, Isaac T; Courtney, Travis; Ries, Justin B

    2016-07-29

    Atmospheric pCO2 is predicted to rise from 400 to 900 ppm by year 2100, causing seawater temperature to increase by 1-4 °C and pH to decrease by 0.1-0.3. Sixty-day experiments were conducted to investigate the independent and combined impacts of acidification (pCO2 = 424-426, 888-940 ppm-v) and warming (T = 28, 32 °C) on calcification rate and skeletal morphology of the abundant and widespread Caribbean reef-building scleractinian coral Siderastrea siderea. Hierarchical linear mixed-effects modelling reveals that coral calcification rate was negatively impacted by both warming and acidification, with their combined effects yielding the most deleterious impact. Negative effects of warming (32 °C/424 ppm-v) and high-temperature acidification (32 °C/940 ppm-v) on calcification rate were apparent across both 30-day intervals of the experiment, while effects of low-temperature acidification (28 °C/888 ppm-v) were not apparent until the second 30-day interval-indicating delayed onset of acidification effects at lower temperatures. Notably, two measures of coral skeletal morphology-corallite height and corallite infilling-were negatively impacted by next-century acidification, but not by next-century warming. Therefore, while next-century ocean acidification and warming will reduce the rate at which corals build their skeletons, next-century acidification will also modify the morphology and, potentially, function of coral skeletons.

  14. Next-century ocean acidification and warming both reduce calcification rate, but only acidification alters skeletal morphology of reef-building coral Siderastrea siderea

    NASA Astrophysics Data System (ADS)

    Horvath, Kimmaree M.; Castillo, Karl D.; Armstrong, Pualani; Westfield, Isaac T.; Courtney, Travis; Ries, Justin B.

    2016-07-01

    Atmospheric pCO2 is predicted to rise from 400 to 900 ppm by year 2100, causing seawater temperature to increase by 1–4 °C and pH to decrease by 0.1–0.3. Sixty-day experiments were conducted to investigate the independent and combined impacts of acidification (pCO2 = 424–426, 888–940 ppm-v) and warming (T = 28, 32 °C) on calcification rate and skeletal morphology of the abundant and widespread Caribbean reef-building scleractinian coral Siderastrea siderea. Hierarchical linear mixed-effects modelling reveals that coral calcification rate was negatively impacted by both warming and acidification, with their combined effects yielding the most deleterious impact. Negative effects of warming (32 °C/424 ppm-v) and high-temperature acidification (32 °C/940 ppm-v) on calcification rate were apparent across both 30-day intervals of the experiment, while effects of low-temperature acidification (28 °C/888 ppm-v) were not apparent until the second 30-day interval—indicating delayed onset of acidification effects at lower temperatures. Notably, two measures of coral skeletal morphology–corallite height and corallite infilling–were negatively impacted by next-century acidification, but not by next-century warming. Therefore, while next-century ocean acidification and warming will reduce the rate at which corals build their skeletons, next-century acidification will also modify the morphology and, potentially, function of coral skeletons.

  15. Extracellular ATP metabolism on vascular endothelial cells: A pathway with pro-thrombotic and anti-thrombotic molecules.

    PubMed

    Fuentes, Eduardo; Palomo, Iván

    2015-12-01

    Vascular endothelial contributes to the metabolism and interconversion of extracellular adenine nucleotides via ecto-ATPase/ADPase (CD39) and ecto-5'nucleotidase (CD73) activities. These enzymes collectively dephosphorylate ATP, ADP, and AMP with the production of additional adenosine. In the vascular system, adenine nucleotides (ATP and ADP) and nucleoside adenosine represent an important class of extracellular molecules involved in modulating the processes linked to vascular thrombosis exerting various effects in platelets. Yet, the mechanisms by which the extracellular ATP metabolism in the local environment trigger pro-thrombotic and anti-thrombotic states are yet to be fully elucidated. In this article, the relative contribution of extracellular ATP metabolism in platelet regulation is explored.

  16. Differential Effects of Ocean Acidification on Coral Calcification: Insights from Geochemistry.

    NASA Astrophysics Data System (ADS)

    Holcomb, M.; Decarlo, T. M.; Venn, A.; Tambutte, E.; Gaetani, G. A.; Tambutte, S.; Allemand, D.; McCulloch, M. T.

    2014-12-01

    Although ocean acidification is expected to negatively impact calcifying animals due to the formation of CaCO3 becoming less favorable, experimental evidence is mixed. Corals have received considerable attention in this regard; laboratory culture experiments show there to be a wide array of calcification responses to acidification. Here we will show how relationships for the incorporation of various trace elements and boron isotopes into synthetic aragonite can be used to reconstruct carbonate chemistry at the site of calcification. In turn the chemistry at the site of calcification can be determined under different ocean acidification scenarios and differences in the chemistry at the site of calcification linked to different calcification responses to acidification. Importantly we will show that the pH of the calcifying fluid alone is insufficient to estimate calcification responses, thus a multi-proxy approach using multiple trace elements and isotopes is required to understand how the site of calcification is affected by ocean acidification.

  17. The evolution of extracellular matrix.

    PubMed

    Ozbek, Suat; Balasubramanian, Prakash G; Chiquet-Ehrismann, Ruth; Tucker, Richard P; Adams, Josephine C

    2010-12-01

    We present a perspective on the molecular evolution of the extracellular matrix (ECM) in metazoa that draws on research publications and data from sequenced genomes and expressed sequence tag libraries. ECM components do not function in isolation, and the biological ECM system or "adhesome" also depends on posttranslational processing enzymes, cell surface receptors, and extracellular proteases. We focus principally on the adhesome of internal tissues and discuss its origins at the dawn of the metazoa and the expansion of complexity that occurred in the chordate lineage. The analyses demonstrate very high conservation of a core adhesome that apparently evolved in a major wave of innovation in conjunction with the origin of metazoa. Integrin, CD36, and certain domains predate the metazoa, and some ECM-related proteins are identified in choanoflagellates as predicted sequences. Modern deuterostomes and vertebrates have many novelties and elaborations of ECM as a result of domain shuffling, domain innovations and gene family expansions. Knowledge of the evolution of metazoan ECM is important for understanding how it is built as a system, its roles in normal tissues and disease processes, and has relevance for tissue engineering, the development of artificial organs, and the goals of synthetic biology.

  18. Extracellular nucleotide signaling in plants

    SciTech Connect

    Stacey, Gary

    2016-09-08

    Over the life of this funded project, our research group identified and characterized two key receptor proteins in plants; one mediating the innate immunity response to chitin and the other elucidating the key receptor for extracellular ATP. In the case of chitin recognition, we recently described the quaternary structure of this receptor, shedding light on how the receptor functions. Perhaps more importantly, we demonstrated that all plants have the ability to recognize both chitin oligomers and lipochitooligosacchardes, fundamentally changing how the community views the evolution of these systems and strategies that might be used, for example, to extend symbiotic nitrogen fixation to non-legumes. Our discovery of DORN1 opens a new chapter in plant physiology documenting conclusively that eATP is an important extracellular signal in plants, as it is in animals. At this point, we cannot predict just how far reaching this discovery may prove to be but we are convinced that eATP signaling is fundamental to plant growth and development and, hence, we believe that the future will be very exciting for the study of DORN1 and its overall function in plants.

  19. Enhanced weathering strategies for stabilizing climate and averting ocean acidification

    NASA Astrophysics Data System (ADS)

    Taylor, Lyla L.; Quirk, Joe; Thorley, Rachel M. S.; Kharecha, Pushker A.; Hansen, James; Ridgwell, Andy; Lomas, Mark R.; Banwart, Steve A.; Beerling, David J.

    2016-04-01

    Chemical breakdown of rocks, weathering, is an important but very slow part of the carbon cycle that ultimately leads to CO2 being locked up in carbonates on the ocean floor. Artificial acceleration of this carbon sink via distribution of pulverized silicate rocks across terrestrial landscapes may help offset anthropogenic CO2 emissions. We show that idealized enhanced weathering scenarios over less than a third of tropical land could cause significant drawdown of atmospheric CO2 and ameliorate ocean acidification by 2100. Global carbon cycle modelling driven by ensemble Representative Concentration Pathway (RCP) projections of twenty-first-century climate change (RCP8.5, business-as-usual; RCP4.5, medium-level mitigation) indicates that enhanced weathering could lower atmospheric CO2 by 30-300 ppm by 2100, depending mainly on silicate rock application rate (1 kg or 5 kg m-2 yr-1) and composition. At the higher application rate, end-of-century ocean acidification is reversed under RCP4.5 and reduced by about two-thirds under RCP8.5. Additionally, surface ocean aragonite saturation state, a key control on coral calcification rates, is maintained above 3.5 throughout the low latitudes, thereby helping maintain the viability of tropical coral reef ecosystems. However, we highlight major issues of cost, social acceptability, and potential unanticipated consequences that will limit utilization and emphasize the need for urgent efforts to phase down fossil fuel emissions.

  20. Deducing acidification rates based on short-term time series

    PubMed Central

    Lui, Hon-Kit; Arthur Chen, Chen-Tung

    2015-01-01

    We show that, statistically, the simple linear regression (SLR)-determined rate of temporal change in seawater pH (βpH), the so-called acidification rate, can be expressed as a linear combination of a constant (the estimated rate of temporal change in pH) and SLR-determined rates of temporal changes in other variables (deviation largely due to various sampling distributions), despite complications due to different observation durations and temporal sampling distributions. Observations show that five time series data sets worldwide, with observation times from 9 to 23 years, have yielded βpH values that vary from 1.61 × 10−3 to −2.5 × 10−3 pH unit yr−1. After correcting for the deviation, these data now all yield an acidification rate similar to what is expected under the air-sea CO2 equilibrium (−1.6 × 10−3 ~ −1.8 × 10−3 pH unit yr−1). Although long-term time series stations may have evenly distributed datasets, shorter time series may suffer large errors which are correctable by this method. PMID:26143749

  1. Effects of episodic acidification on Atlantic salmon (Salmo salar) smolts

    USGS Publications Warehouse

    Magee, J.A.; Obedzinski, M.; McCormick, S.D.; Kocik, J.F.

    2003-01-01

    The effect of episodic acidification on Atlantic salmon (Salmo salar) smolt physiology and survival in fresh water (FW) and seawater (SW) was investigated. Smolts were held in either ambient (control, pH 6.0-6.6), acidified (chronic, pH 4.4-6.1), or episodically acidified (episodic, pH reduction from control levels to pH ???5.2 for 48 h once weekly) river water for 31 days and then transferred to 34??? SW. Smolts fed little while in acidified conditions and chronic smolts did not grow in length or weight. In FW, chronic smolts experienced increases in hematocrit and plasma potassium and reductions in plasma sodium and chloride. Upon transfer to SW, chronic and episodic smolts experienced reductions in hematocrit, increases in plasma sodium, chloride, and potassium levels, and suffered mortalities. Gill Na+,K+-ATPase and citrate synthase activities were reduced by exposure to acid. For most parameters, the effect of episodic acid exposure was less than that of chronic acidification. Exposure to acidic conditions, even when short in duration and followed by a 30-h recovery period in suitable water (pH 6.5), led to a 35% mortality of smolts upon transfer to SW. This study highlights the importance of measuring and assessing sublethal stresses in FW and their ultimate effects in marine ecosystems.

  2. Effects of acidification on algal assemblages in temporary ponds

    SciTech Connect

    Glackin, M.E.; Pratt, J.R.

    1994-12-31

    Atmospheric deposition monitoring in Pennsylvania has characterized a steep gradient of acidic ion depositions across the north-central portion of the state. This study evaluated acidification effects on the composition of algal assemblages in temporary ponds in two forested areas exposed to atmospheric deposition that varied in degree of acidity. Artificial substrates were used to sample and compare the algal assemblages in the two areas. Colonized communities were also transplanted to lower pH ponds to observe changes in species composition. A laboratory microcosm experiment manipulating pH was conducted to reduce the variables that differed between the two areas. Fewer algal taxa were present in lower pH ponds, on colonized substrates after transplant to lower pH ponds, and in lower pH laboratory treatments. Species composition was altered in the lower pH conditions. Most taxa that were excluded from the lower pH ponds naturally also did not survive when experimentally introduced to those conditions. These results suggest that acidification of temporary ponds can alter the structure of algal communities. There is interest in a possible link between acid deposition and reports of worldwide declines in amphibian populations. Algae are an important food source for larval amphibians, such as the wood frog, which require temporary ponds to breed. Changes in algal species composition could potentially impact the temporary pond and forest ecosystem.

  3. Ocean acidification causes structural deformities in juvenile coral skeletons.

    PubMed

    Foster, Taryn; Falter, James L; McCulloch, Malcolm T; Clode, Peta L

    2016-02-01

    Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a "business-as-usual" emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100.

  4. Sensitivity of coccolithophores to carbonate chemistry and ocean acidification.

    PubMed

    Beaufort, L; Probert, I; de Garidel-Thoron, T; Bendif, E M; Ruiz-Pino, D; Metzl, N; Goyet, C; Buchet, N; Coupel, P; Grelaud, M; Rost, B; Rickaby, R E M; de Vargas, C

    2011-08-03

    About one-third of the carbon dioxide (CO(2)) released into the atmosphere as a result of human activity has been absorbed by the oceans, where it partitions into the constituent ions of carbonic acid. This leads to ocean acidification, one of the major threats to marine ecosystems and particularly to calcifying organisms such as corals, foraminifera and coccolithophores. Coccolithophores are abundant phytoplankton that are responsible for a large part of modern oceanic carbonate production. Culture experiments investigating the physiological response of coccolithophore calcification to increased CO(2) have yielded contradictory results between and even within species. Here we quantified the calcite mass of dominant coccolithophores in the present ocean and over the past forty thousand years, and found a marked pattern of decreasing calcification with increasing partial pressure of CO(2) and concomitant decreasing concentrations of CO(3)(2-). Our analyses revealed that differentially calcified species and morphotypes are distributed in the ocean according to carbonate chemistry. A substantial impact on the marine carbon cycle might be expected upon extrapolation of this correlation to predicted ocean acidification in the future. However, our discovery of a heavily calcified Emiliania huxleyi morphotype in modern waters with low pH highlights the complexity of assemblage-level responses to environmental forcing factors.

  5. Responses of freshwater plants and invertebrates to acidification

    SciTech Connect

    Hendrey, G.R.; Yan, N.D.; Baumgartner, K.J.

    1980-01-01

    Acidic, oligotrophic, clear waters often have strong similarities among their biota. In the phytoplankton, Dinophyceae, and to a lesser extent Chrysophyceae tend to dominate. Production of 25 Canadian Shield lakes (pH 6.1-7.1) ranged from 25 to 240 mg C m/sup -2/ d/sup -1/. Both biomass and production appear to be controlled by the supply and bio-availability of phosphorus rather than pH per se. We found little evidence of possible C limitation in acidified lakes. There does not appear to be a direct relationship between (H/sup +/) and biomass density in lakes, as illustrated by whole-lake manipulations of (H/sup +/) and total phosphorus (TP). These studies, however, do not examine effects of acidification on the whole lake-watershed system. It is suggested that watershed acidification processes such as leaching of Al may reduce TP loading to lakes. Zooplankton community biomass appears to be reduced at low pH and small-bodied forms may dominate. Among the zoobenthos, biomass does appear to be reduced in some lakes but not others. Various studies found shredders; collectors and scrapers to be reduced more than raptorial species. We hypothesize that removal of fish predation on benthos allows a relative increase in the invertebrate predators, reduction of herbivores (chironomids are relatively abundant) and the subsequent increase in benthic algae observed in many waters.

  6. Conservation of acid waterlogged shipwrecks: nanotechnologies for de-acidification

    NASA Astrophysics Data System (ADS)

    Giorgi, R.; Chelazzi, D.; Baglioni, P.

    2006-06-01

    Preservation of waterlogged wooden artifacts, and in particular ancient wrecks, is a challenge in cultural heritage conservation. Samples, from the Swedish warship Vasa, are under investigation in order to develop innovative methods for wood de-acidification and preservation. The Vasa represents a unique case in the study of ancient wrecks. In the past four years the problem of the acidity of wood emerged as a strong threat to its conservation. The production of sulphuric acid inside the ship wood might be the cause of both chemical damage through the acid hydrolysis of cellulose, and of physical damage of the wood’s pore structure, due to the crystallization of sulphate minerals in the wood pores. In this paper we show that wood acidity can be neutralized by the application of nanoparticles of alkaline-earth carbonates and/or hydroxides. The treatment provides an alkaline reservoir inside the wood. Nanoparticles absorbed in the wood from an alcoholic dispersion adhere to the wood wall and release hydroxyl ions leading to the wood neutralization. Oak and pine samples from the Vasa wreck were characterized and treated with alkaline magnesium or calcium nanoparticle dispersions in non-aqueous solvents. De-acidification was monitored by pH changes and thermal analysis, and all the treated samples were submitted to thermal artificial ageing in order to demonstrate the efficacy of the method. The results obtained opened a new perspective in wood conservation.

  7. Ocean acidification causes structural deformities in juvenile coral skeletons

    PubMed Central

    Foster, Taryn; Falter, James L.; McCulloch, Malcolm T.; Clode, Peta L.

    2016-01-01

    Rising atmospheric CO2 is causing the oceans to both warm and acidify, which could reduce the calcification rates of corals globally. Successful coral recruitment and high rates of juvenile calcification are critical to the replenishment and ultimate viability of coral reef ecosystems. Although elevated Pco2 (partial pressure of CO2) has been shown to reduce the skeletal weight of coral recruits, the structural changes caused by acidification during initial skeletal deposition are unknown. We show, using high-resolution three-dimensional x-ray microscopy, that ocean acidification (Pco2 ~900 μatm, pH ~7.7) not only causes reduced overall mineral deposition but also a deformed and porous skeletal structure in newly settled coral recruits. In contrast, elevated temperature (+3°C) had little effect on skeletal formation except to partially mitigate the effects of elevated Pco2. The striking structural deformities we observed show that new recruits are at significant risk, being unable to effectively build their skeletons in the Pco2 conditions predicted to occur for open ocean surface waters under a “business-as-usual” emissions scenario [RCP (representative concentration pathway) 8.5] by the year 2100. PMID:26989776

  8. Organelle acidification negatively regulates vacuole membrane fusion in vivo

    PubMed Central

    Desfougères, Yann; Vavassori, Stefano; Rompf, Maria; Gerasimaite, Ruta; Mayer, Andreas

    2016-01-01

    The V-ATPase is a proton pump consisting of a membrane-integral V0 sector and a peripheral V1 sector, which carries the ATPase activity. In vitro studies of yeast vacuole fusion and evidence from worms, flies, zebrafish and mice suggested that V0 interacts with the SNARE machinery for membrane fusion, that it promotes the induction of hemifusion and that this activity requires physical presence of V0 rather than its proton pump activity. A recent in vivo study in yeast has challenged these interpretations, concluding that fusion required solely lumenal acidification but not the V0 sector itself. Here, we identify the reasons for this discrepancy and reconcile it. We find that acute pharmacological or physiological inhibition of V-ATPase pump activity de-acidifies the vacuole lumen in living yeast cells within minutes. Time-lapse microscopy revealed that de-acidification induces vacuole fusion rather than inhibiting it. Cells expressing mutated V0 subunits that maintain vacuolar acidity were blocked in this fusion. Thus, proton pump activity of the V-ATPase negatively regulates vacuole fusion in vivo. Vacuole fusion in vivo does, however, require physical presence of a fusion-competent V0 sector. PMID:27363625

  9. Ocean acidification can mediate biodiversity shifts by changing biogenic habitat

    NASA Astrophysics Data System (ADS)

    Sunday, Jennifer M.; Fabricius, Katharina E.; Kroeker, Kristy J.; Anderson, Kathryn M.; Brown, Norah E.; Barry, James P.; Connell, Sean D.; Dupont, Sam; Gaylord, Brian; Hall-Spencer, Jason M.; Klinger, Terrie; Milazzo, Marco; Munday, Philip L.; Russell, Bayden D.; Sanford, Eric; Thiyagarajan, Vengatesen; Vaughan, Megan L. H.; Widdicombe, Stephen; Harley, Christopher D. G.

    2017-01-01

    The effects of ocean acidification (OA) on the structure and complexity of coastal marine biogenic habitat have been broadly overlooked. Here we explore how declining pH and carbonate saturation may affect the structural complexity of four major biogenic habitats. Our analyses predict that indirect effects driven by OA on habitat-forming organisms could lead to lower species diversity in coral reefs, mussel beds and some macroalgal habitats, but increases in seagrass and other macroalgal habitats. Available in situ data support the prediction of decreased biodiversity in coral reefs, but not the prediction of seagrass bed gains. Thus, OA-driven habitat loss may exacerbate the direct negative effects of OA on coastal biodiversity; however, we lack evidence of the predicted biodiversity increase in systems where habitat-forming species could benefit from acidification. Overall, a combination of direct effects and community-mediated indirect effects will drive changes in the extent and structural complexity of biogenic habitat, which will have important ecosystem effects.

  10. Ocean Acidification: Euphausia Pacifica's Response to Decreasing pH

    NASA Astrophysics Data System (ADS)

    Weber, H. N.; Cooper, H.

    2014-12-01

    The increasing rate of CO2 accumulating in Earth's oceans creates a threat to organisms that can lead to disturbances in their reproduction, survival and growth. Euphausia pacifica is the dominant species of krill in Monterey Bay, CA, and a keystone species in the bay's food web. Previous work on the effects of ocean acidification on the survival, growth and molting of E. pacifica have shown they are fairly tolerant to increased CO2 concentrations. However, less is known about energy costs associated with maintaining their internal pH levels which could affect food consumption, swimming behavior or growth activity. We hypothesized that krill exposed to high CO2 will increase their feeding rate on local species of phytoplankton to account for increased energy costs of pH buffering activity. We exposed experimental E. pacifica to waters of pH 7.6 (the expected pH surface waters in year 2100), and pH 8.0 (control) periods.test for acclimation or longer term stress. Feeding rates were calculated as changes in phytoplankton counts over 24 hours of feeding using Frost's equations (Frost 1972). Understanding the way E. pacifica is affected by ocean acidification is important because of the role they play as the primary food source for a variety of predators necessary to maintain the Pacific's ecology.

  11. Predicting Effects of Coastal Acidification on Marine Bivalve ...

    EPA Pesticide Factsheets

    The partial pressure of carbon dioxide (pCO2) is increasing in the oceans and causing changes in seawater pH commonly described as ocean or coastal acidification. It is now well-established that, when reproduced in laboratory experiments, these increases in pCO2 can reduce survival and growth of early life stage bivalves. However, the effects that these impairments would have on whole populations of bivalves are unknown. In this study, these laboratory responses were incorporated into field-parameterized population models to assess population-level sensitivities to acidification for two northeast bivalve species with different life histories: Mercenaria mercenaria (hard clam) and Argopecten irradians (bay scallop). The resulting models permitted translation of laboratory pCO2 response functions into population-level responses to examine population sensitivity to future pCO2 changes. Preliminary results from our models indicate that if the current M. mercenaria negative population growth rate was attributed to the effects of pCO2 on early life stages, the population would decline at a rate of 50% per ten years at 420 microatmospheres (µatm) pCO2. If the current population growth rate was attributed to other additive factors (e.g., harvest, harmful algal blooms), M. mercenaria populations were predicted to decline at a rate of 50% per ten years at the preliminary estimate of 1010 µatm pCO2. The estimated population growth rate was positive for A. irradians,

  12. Ocean acidification erodes crucial auditory behaviour in a marine fish.

    PubMed

    Simpson, Stephen D; Munday, Philip L; Wittenrich, Matthew L; Manassa, Rachel; Dixson, Danielle L; Gagliano, Monica; Yan, Hong Y

    2011-12-23

    Ocean acidification is predicted to affect marine ecosystems in many ways, including modification of fish behaviour. Previous studies have identified effects of CO(2)-enriched conditions on the sensory behaviour of fishes, including the loss of natural responses to odours resulting in ecologically deleterious decisions. Many fishes also rely on hearing for orientation, habitat selection, predator avoidance and communication. We used an auditory choice chamber to study the influence of CO(2)-enriched conditions on directional responses of juvenile clownfish (Amphiprion percula) to daytime reef noise. Rearing and test conditions were based on Intergovernmental Panel on Climate Change predictions for the twenty-first century: current-day ambient, 600, 700 and 900 µatm pCO(2). Juveniles from ambient CO(2)-conditions significantly avoided the reef noise, as expected, but this behaviour was absent in juveniles from CO(2)-enriched conditions. This study provides, to our knowledge, the first evidence that ocean acidification affects the auditory response of fishes, with potentially detrimental impacts on early survival.

  13. Enhanced Weathering Strategies for Stabilizing Climate and Averting Ocean Acidification

    NASA Technical Reports Server (NTRS)

    Taylor, Lyla L.; Quirk, Joe; Thorley, Rachel M. S.; Kharecha, Pushker A.; Hansen, James; Ridgwell, Andy; Lomas, Mark R.; Banwart, Steve A.; Beerling, David J.

    2015-01-01

    Chemical breakdown of rocks, weathering, is an important but very slow part of the carbon cycle that ultimately leads to CO2 being locked up in carbonates on the ocean floor. Artificial acceleration of this carbon sink via distribution of pulverized silicate rocks across terrestrial landscapes may help offset anthropogenic CO2 emissions. We show that idealized enhanced weathering scenarios over less than a third of tropical land could cause significant drawdown of atmospheric CO2 and ameliorate ocean acidification by 2100. Global carbon cycle modelling driven by ensemble Representative Concentration Pathway (RCP) projections of twenty-first-century climate change (RCP8.5, business-as-usual; RCP4.5, medium-level mitigation) indicates that enhanced weathering could lower atmospheric CO2 by 30-300 ppm by 2100, depending mainly on silicate rock application rate (1 kg or 5 kg m(exp -2) yr (exp -1)) and composition. At the higher application rate, end-of-century ocean acidification is reversed under RCP4.5 and reduced by about two-thirds under RCP8.5. Additionally, surface ocean aragonite saturation state, a key control on coral calcification rates, is maintained above 3.5 throughout the low latitudes, thereby helping maintain the viability of tropical coral reef ecosystems. However, we highlight major issues of cost, social acceptability, and potential unanticipated consequences that will limit utilization and emphasize the need for urgent efforts to phase down fossil fuel emissions.

  14. Renal acidification responses to respiratory acid-base disorders.

    PubMed

    Madias, Nicolaos E

    2010-01-01

    Respiratory acid-base disorders are those abnormalities in acid-base equilibrium that are expressed as primary changes in the arterial carbon dioxide tension (PaCO2). An increase in PaCO2 (hypercapnia) acidifies body fluids and initiates the acid-base disturbance known as respiratory acidosis. By contrast, a decrease in PaCO2 (hypocapnia) alkalinizes body fluids and initiates the acid-base disturbance known as respiratory alkalosis. The impact on systemic acidity of these primary changes in PaCO2 is ameliorated by secondary, directional changes in plasma [HCO3¯] that occur in 2 stages. Acutely, hypercapnia or hypocapnia yields relatively small changes in plasma [HCO3¯] that originate virtually exclusively from titration of the body's nonbicarbonate buffers. During sustained hypercapnia or hypocapnia, much larger changes in plasma [HCO3¯] occur that reflect adjustments in renal acidification mechanisms. Consequently, the deviation of systemic acidity from normal is smaller in the chronic forms of these disorders. Here we provide an overview of the renal acidification responses to respiratory acid-base disorders. We also identify gaps in knowledge that require further research.

  15. Evolutionary potential of marine phytoplankton under ocean acidification

    PubMed Central

    Collins, Sinéad; Rost, Björn; Rynearson, Tatiana A

    2014-01-01

    Marine phytoplankton have many obvious characters, such as rapid cell division rates and large population sizes, that give them the capacity to evolve in response to global change on timescales of weeks, months or decades. However, few studies directly investigate if this adaptive potential is likely to be realized. Because of this, evidence of to whether and how marine phytoplankton may evolve in response to global change is sparse. Here, we review studies that help predict evolutionary responses to global change in marine phytoplankton. We find limited support from experimental evolution that some taxa of marine phytoplankton may adapt to ocean acidification, and strong indications from studies of variation and structure in natural populations that selection on standing genetic variation is likely. Furthermore, we highlight the large body of literature on plastic responses to ocean acidification available, and evolutionary theory that may be used to link plastic and evolutionary responses. Because of the taxonomic breadth spanned by marine phytoplankton, and the diversity of roles they fill in ocean ecosystems and biogeochemical cycles, we stress the necessity of treating taxa or functional groups individually. PMID:24454553

  16. The exposure of the Great Barrier Reef to ocean acidification.

    PubMed

    Mongin, Mathieu; Baird, Mark E; Tilbrook, Bronte; Matear, Richard J; Lenton, Andrew; Herzfeld, Mike; Wild-Allen, Karen; Skerratt, Jenny; Margvelashvili, Nugzar; Robson, Barbara J; Duarte, Carlos M; Gustafsson, Malin S M; Ralph, Peter J; Steven, Andrew D L

    2016-02-23

    The Great Barrier Reef (GBR) is founded on reef-building corals. Corals build their exoskeleton with aragonite, but ocean acidification is lowering the aragonite saturation state of seawater (Ωa). The downscaling of ocean acidification projections from global to GBR scales requires the set of regional drivers controlling Ωa to be resolved. Here we use a regional coupled circulation-biogeochemical model and observations to estimate the Ωa experienced by the 3,581 reefs of the GBR, and to apportion the contributions of the hydrological cycle, regional hydrodynamics and metabolism on Ωa variability. We find more detail, and a greater range (1.43), than previously compiled coarse maps of Ωa of the region (0.4), or in observations (1.0). Most of the variability in Ωa is due to processes upstream of the reef in question. As a result, future decline in Ωa is likely to be steeper on the GBR than currently projected by the IPCC assessment report.

  17. The exposure of the Great Barrier Reef to ocean acidification

    PubMed Central

    Mongin, Mathieu; Baird, Mark E.; Tilbrook, Bronte; Matear, Richard J.; Lenton, Andrew; Herzfeld, Mike; Wild-Allen, Karen; Skerratt, Jenny; Margvelashvili, Nugzar; Robson, Barbara J.; Duarte, Carlos M.; Gustafsson, Malin S. M.; Ralph, Peter J.; Steven, Andrew D. L.

    2016-01-01

    The Great Barrier Reef (GBR) is founded on reef-building corals. Corals build their exoskeleton with aragonite, but ocean acidification is lowering the aragonite saturation state of seawater (Ωa). The downscaling of ocean acidification projections from global to GBR scales requires the set of regional drivers controlling Ωa to be resolved. Here we use a regional coupled circulation–biogeochemical model and observations to estimate the Ωa experienced by the 3,581 reefs of the GBR, and to apportion the contributions of the hydrological cycle, regional hydrodynamics and metabolism on Ωa variability. We find more detail, and a greater range (1.43), than previously compiled coarse maps of Ωa of the region (0.4), or in observations (1.0). Most of the variability in Ωa is due to processes upstream of the reef in question. As a result, future decline in Ωa is likely to be steeper on the GBR than currently projected by the IPCC assessment report. PMID:26907171

  18. Dolomite limits acidification of a biofilter degrading dimethyl sulphide

    PubMed

    Smet; Van Langenhove H; Philips

    1999-01-01

    The applicability of dolomite particles to control acidification in a Hyphomicrobium MS3 inoculated biofilter removing dimethyl sulphide (Me2S) was studied. While direct inoculation of the dolomite particles with the liquid microbial culture was not successful, start-up of Me2S-degradation in the biofilter was observed when the dolomite particles were mixed with 33% (wt/wt) of Hyphomicrobium MS3-inoculated compost or wood bark material. Under optimal conditions, an elimination capacity (EC) of 1680 g Me2S m(-3) d(-1) was obtained for the compost/dolomite biofilter. Contrary to a wood bark or compost biofilter, no reduction in activity due to acidification was observed in these biofilters over a 235 day period because of the micro environment neutralisation of the microbial metabolite H2SO4 with the carbonate in the dolomite material. However, performance of the biofilter decreased when the moisture content of the mixed compost/dolomite material dropped below 15%. Next to this, nutrient limitation resulted in a gradual decrease of the EC and supplementation of a nitrogen source was a prerequisite to obtain a long-term high EC (> 250 g Me2S m(-3) d(-1)) for Me2S. In relation to this nitrogen supplementation, it was observed that stable ECs for Me2S were obtained when this nutrient was dosed to the biofilter at a Me2S-C/NH4Cl-N ratio of about 10.

  19. Endoscopic Thermal Fasciotomy for Chronic Exertional Compartment Syndrome

    PubMed Central

    Voleti, Pramod B.; Lebrun, Drake G.; Roth, Cameron A.; Kelly, John D.

    2015-01-01

    Chronic exertional compartment syndrome is an activity-induced condition that occurs when intracompartmental pressures within an osteofascial envelope increase during exercise, leading to reversible ischemic symptoms such as pain, cramping, numbness, or weakness. Nonoperative treatment options for this condition have shown limited success and are often undesirable for the patient given the requirement for activity modification. Traditional surgical treatment options involving open or subcutaneous fasciotomies have more favorable results, but these techniques are associated with significant morbidity. Endoscopically assisted fasciotomy techniques afford the advantages of being minimally invasive, providing excellent visualization, and allowing accelerated rehabilitation. The purpose of this article is to describe a technique for performing endoscopically assisted fasciotomies for chronic exertional compartment syndrome of the lower leg using an entirely endoscopic thermal ablating device. The endoscopic thermal fasciotomy technique is associated with minimal morbidity, ensures excellent hemostasis, and affords an early return to sports. PMID:26900549

  20. Exertional dyspnea as a symptom of infrarenal aortic occlusive disease.

    PubMed

    Schott, Stacey L; Carreiro, Fernanda Porto; Harkness, James R; Malas, Mahmoud B; Sozio, Stephen M; Zakaria, Sammy

    2014-06-01

    Advanced atherosclerosis of the aorta can cause severe ischemia in the kidneys, refractory hypertension, and claudication. However, no previous reports have clearly associated infrarenal aortic stenosis with shortness of breath. A 77-year-old woman with hypertension and hyperlipidemia presented with exertional dyspnea. Despite extensive testing and observation, no apparent cause for this patient's dyspnea was found. Images revealed severe infrarenal aortic stenosis. After the patient underwent stenting of the aortic occlusion, she had immediate symptomatic improvement and complete resolution of her dyspnea within one month. Twelve months after vascular intervention, the patient remained asymptomatic. In view of the distinct and lasting elimination of dyspnea after angioplasty and stenting of a nearly occluded infrarenal aortic lesion, we hypothesize that infrarenal aortic stenosis might be a treatable cause of exertional dyspnea. Clinicians should consider infrarenal aortic stenosis as a possible cause of dyspnea. Treatment of the stenosis might relieve symptoms.

  1. Wall pressure exerted by hydrogenation of sodium aluminum hydride.

    SciTech Connect

    Perras, Yon E.; Dedrick, Daniel E.; Zimmerman, Mark D.

    2009-06-01

    Wall pressure exerted by the bulk expansion of a sodium aluminum hydride bed was measured as a function of hydrogen content. A custom apparatus was designed and loaded with sodium alanates at densities of 1.0, 1.1, and 1.16 g/cc. Four complete cycles were performed to identify variations in measured pressure. Results indicated poor correlation between exerted pressure and hydrogen capacity of the sodium alanate beds. Mechanical pressure due to the hydrogenation of sodium alanates does not influence full-scale system designs as it falls within common design factors of safety. Gas pressure gradients within the porous solid were identified and may limit reaction rates, especially for high aspect ratio beds.

  2. A Virtual Rat for Simulating Environmental and Exertional Heat Stress

    DTIC Science & Technology

    2014-10-02

    A virtual rat for simulating environmental and exertional heat stress Vineet Rakesh,1 X Jonathan D. Stallings,2 and Jaques Reifman1 1Department of...Health Research, Fort Detrick, Maryland Submitted 8 July 2014; accepted in final form 18 September 2014 Rakesh V, Stallings JD, Reifman J. A virtual rat ...different heat-stress conditions. To this end, we used our previously published virtual rat , which is capable of computing the spatiotemporal

  3. A Macrophage Subversion Factor Is Shared by Intracellular and Extracellular Pathogens.

    PubMed

    Belon, Claudine; Soscia, Chantal; Bernut, Audrey; Laubier, Aurélie; Bleves, Sophie; Blanc-Potard, Anne-Béatrice

    2015-06-01

    Pathogenic bacteria have developed strategies to adapt to host environment and resist host immune response. Several intracellular bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis, share the horizontally-acquired MgtC virulence factor that is important for multiplication inside macrophages. MgtC is also found in pathogenic Pseudomonas species. Here we investigate for the first time the role of MgtC in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in the systemic infection model of zebrafish embryos, and strikingly, the attenuated phenotype is dependent on the presence of macrophages. In ex vivo experiments, the P. aeruginosa mgtC mutant is more sensitive to macrophage killing than the wild-type strain. However, wild-type and mutant strains behave similarly toward macrophage killing when macrophages are treated with an inhibitor of the vacuolar proton ATPase. Importantly, P. aeruginosa mgtC gene expression is strongly induced within macrophages and phagosome acidification contributes to an optimal expression of the gene. Thus, our results support the implication of a macrophage intracellular stage during P. aeruginosa acute infection and suggest that Pseudomonas MgtC requires phagosome acidification to play its intracellular role. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC shares a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to host immune response in relation to the different bacterial lifestyles. In addition, the phenotypes observed with the mgtC mutant in infection models can be mimicked in wild-type P. aeruginosa strain by producing a MgtC antagonistic peptide, thus

  4. Failing phrenics: an obscure cause of exertional dyspnea

    PubMed Central

    Rafiq, Arsalan; Ijaz, Mohsin; Tariq, Hassan; Vakde, Trupti; Duncalf, Richard

    2016-01-01

    Abstract Introduction: Idiopathic phrenic nerve palsy is a rare cause of exertional dyspnea. We present a case of a patient presenting with worsening dyspnea of an unknown etiology found to be related to bilateral phrenic nerve palsy. Discussion: Forty-two-year-old man presented to our emergency department with exertional dyspnea, orthopnea, and a left lower lobe consolidation treated initially as bronchitis by his primary physician as an outpatient, then subsequently as pneumonia at another institution, with no improvement in symptomatology. After admission to our hospital, CT chest demonstrated only supradiaphragmatic atelectatic changes. Echocardiography was normal. Bronchoscopy was contemplated however the patient could not lie flat. A fluoroscopic sniff test demonstrated diaphragmatic dysfunction and pulmonary function tests revealed restrictive pulmonary disease with evidence of neuromuscular etiology. Nerve conduction studies confirmed bilateral phrenic neuropathy. He was referred to a specialized neuromuscular disease center where subsequent workup did not demonstrate any specific etiology. A sleep study confirmed sleep disordered breathing suggestive of diaphragmatic paralysis and he was discharged on bi-level positive pressure ventilation. Conclusion: This is a unique case of exertional dyspnea and orthopnea from diaphragmatic paresis caused by bilateral phrenic nerve palsy where the initial workup for pulmonary and cardiovascular etiologies was essentially unremarkable. Shortness of breath and orthopnea caused by phrenic neuropathy is a rare condition, yet has a variety of etiologies. Our case suggests a template to the diagnostic approach, management, and follow up of bilateral phrenic nerve palsy. PMID:27442657

  5. Exercise, physical activity, and exertion over the business cycle.

    PubMed

    Colman, Gregory; Dave, Dhaval

    2013-09-01

    Shifts in time and income constraints over economic expansions and contractions would be expected to affect individuals' behaviors. We explore the impact of the business cycle on individuals' exercise, time use, and total physical exertion, utilizing information on 112,000 individual records from the 2003-2010 American Time Use Surveys. In doing so, we test a key causal link that has been hypothesized in the relation between unemployment and health, but not heretofore assessed. Using more precise measures of exercise (and other activities) than previous studies, we find that as work-time decreases during a recession, recreational exercise, TV-watching, sleeping, childcare, and housework increase. This, however, does not compensate for the decrease in work-related exertion due to job-loss, and total physical exertion declines. These effects are strongest among low-educated men, which is validating given that employment in the Great Recession has declined most within manufacturing, mining, and construction. We also find evidence of intra-household spillover effects, wherein individuals respond to shifts in spousal employment conditional on their own labor supply. The decrease in total physical activity during recessions is especially problematic for vulnerable populations concentrated in boom-and-bust industries, and may have longer-term effects on obesity and related health outcomes.

  6. Could the acid-base status of Antarctic sea urchins indicate a better-than-expected resilience to near-future ocean acidification?

    PubMed

    Collard, Marie; De Ridder, Chantal; David, Bruno; Dehairs, Frank; Dubois, Philippe

    2015-02-01

    Increasing atmospheric carbon dioxide concentration alters the chemistry of the oceans towards more acidic conditions. Polar oceans are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the oceans' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to ocean acidification in metazoans is first linked to acid-base regulation capacities of the extracellular fluids. No information on this is available to date for Antarctic echinoderms and inference from temperate and tropical studies needs support. In this study, we investigated the acid-base status of 9 species of sea urchins (3 cidaroids, 2 regular euechinoids and 4 irregular echinoids). It appears that Antarctic regular euechinoids seem equipped with similar acid-base regulation systems as tropical and temperate regular euechinoids but could rely on more passive ion transfer systems, minimizing energy requirements. Cidaroids have an acid-base status similar to that of tropical cidaroids. Therefore Antarctic cidaroids will most probably not be affected by decreasing seawater pH, the pH drop linked to ocean acidification being negligible in comparison of the naturally low pH of the coelomic fluid. Irregular echinoids might not suffer from reduced seawater pH if acidosis of the coelomic fluid pH does not occur but more data on their acid-base regulation are needed. Combining these results with the resilience of Antarctic sea urchin larvae strongly suggests that these organisms might not be the expected victims of ocean acidification. However, data on the impact of other global stressors such as temperature and of the combination of the different stressors needs to be acquired to assess the sensitivity of these organisms to global

  7. Acid-base physiology response to ocean acidification of two ecologically and economically important holothuroids from contrasting habitats, Holothuria scabra and Holothuria parva.

    PubMed

    Collard, Marie; Eeckhaut, Igor; Dehairs, Frank; Dubois, Philippe

    2014-12-01

    Sea cucumbers are dominant invertebrates in several ecosystems such as coral reefs, seagrass meadows and mangroves. As bioturbators, they have an important ecological role in making available calcium carbonate and nutrients to the rest of the community. However, due to their commercial value, they face overexploitation in the natural environment. On top of that, occurring ocean acidification could impact these organisms, considered sensitive as echinoderms are osmoconformers, high-magnesium calcite producers and have a low metabolism. As a first investigation of the impact of ocean acidification on sea cucumbers, we tested the impact of short-term (6 to 12 days) exposure to ocean acidification (seawater pH 7.7 and 7.4) on two sea cucumbers collected in SW Madagascar, Holothuria scabra, a high commercial value species living in the seagrass meadows, and H. parva, inhabiting the mangroves. The former lives in a habitat with moderate fluctuations of seawater chemistry (driven by day-night differences) while the second lives in a highly variable intertidal environment. In both species, pH of the coelomic fluid was significantly negatively affected by reduced seawater pH, with a pronounced extracellular acidosis in individuals maintained at pH 7.7 and 7.4. This acidosis was due to an increased dissolved inorganic carbon content and pCO2 of the coelomic fluid, indicating a limited diffusion of the CO2 towards the external medium. However, respiration and ammonium excretion rates were not affected. No evidence of accumulation of bicarbonate was observed to buffer the coelomic fluid pH. If this acidosis stays uncompensated for when facing long-term exposure, other processes could be affected in both species, eventually leading to impacts on their ecological role.

  8. Vascular CD39/ENTPD1 Directly Promotes Tumor Cell Growth by Scavenging Extracellular Adenosine Triphosphate12

    PubMed Central

    Feng, Lili; Sun, Xiaofeng; Csizmadia, Eva; Han, Lihui; Bian, Shu; Murakami, Takashi; Wang, Xin; Robson, Simon C; Wu, Yan

    2011-01-01

    Extracellular adenosine triphosphate (ATP) is known to boost immune responses in the tumor microenvironment but might also contribute directly to cancer cell death. CD39/ENTPD1 is the dominant ectonucleotidase expressed by endothelial cells and regulatory T cells and catalyzes the sequential hydrolysis of ATP to AMP that is further degraded to adenosine by CD73/ecto-5′-nucleotidase. We have previously shown that deletion of Cd39 results in decreased growth of transplanted tumors in mice, as a result of both defective angiogenesis and heightened innate immune responses (secondary to loss of adenosinergic immune suppression). Whether alterations in local extracellular ATP and adenosine levels as a result of CD39 bioactivity directly affect tumor growth and cytotoxicity has not been investigated to date. We show here that extracellular ATP exerts antitumor activity by directly inhibiting cell proliferation and promoting cancer cell death. ATP-induced antiproliferative effects and cell death are, in large part, mediated through P2X7 receptor signaling. Tumors in Cd39 null mice exhibit increased necrosis in association with P2X7 expression. We further demonstrate that exogenous soluble NTPDase, or CD39 expression by cocultured liver sinusoidal endothelial cells, stimulates tumor cell proliferation and limits cell death triggered by extracellular ATP. Collectively, our findings indicate that local expression of CD39 directly promotes tumor cell growth by scavenging extracellular ATP. Pharmacological or targeted inhibition of CD39 enzymatic activity may find utility as an adjunct therapy in cancer management. PMID:21390184

  9. Theranostic Nucleic Acid Binding Nanoprobe Exerts Anti-inflammatory and Cytoprotective Effects in Ischemic Injury

    PubMed Central

    Chen, Howard H.; Yuan, Hushan; Cho, Hoonsung; Feng, Yan; Ngoy, Soeun; Kumar, Anand T. N.; Liao, Ronglih; Chao, Wei; Josephson, Lee; Sosnovik, David E.

    2017-01-01

    Extracellular nucleic acids are proinflammatory molecules that have been implicated in a diverse range of diseases. We report here the development of a multivalent nucleic acid scavenging nanoprobe, where the fluorochrome thiazole orange (TO) is conjugated to a polymeric 40 kDa dextran carrier. Dextran-TO (Dex-TO) has nanomolar affinity for mammalian and bacterial nucleic acids and attenuates the production of inflammatory cytokines from activated macrophages exposed to DNA and RNA. Mice with myocardial ischemia reperfusion that were treated with Dex-TO showed a decrease in myocardial macrophage infiltration at 24 hours (p<0.05) and a decrease in infarct size (18% ± 9%, p<0.01) on day 7. Dex-TO allows sites of injury to be identified with fluorescence imaging, while simultaneously exerting an anti-inflammatory and cytoprotective effect. Dex-TO could be of significant diagnostic and therapeutic (theranostic) utility in a broad range of conditions including ischemia, trauma, burns, sepsis and autoimmune disease. PMID:28382156

  10. Dimethylsulfoniopropionate Promotes Process Outgrowth in Neural Cells and Exerts Protective Effects against Tropodithietic Acid

    PubMed Central

    Wichmann, Heidi; Brinkhoff, Thorsten; Simon, Meinhard; Richter-Landsberg, Christiane

    2016-01-01

    The marine environment harbors a plethora of bioactive substances, including drug candidates of potential value in the field of neuroscience. The present study was undertaken to investigate the effects of dimethylsulfoniopropionate (DMSP), produced by several algae, corals and higher plants, on cells of the mammalian nervous system, i.e., neuronal N2a and OLN-93 cells as model system for nerve cells and glia, respectively. Additionally, the protective capabilities of DMSP were assessed in cells treated with tropodithietic acid (TDA), a marine metabolite produced by several Roseobacter clade bacteria. Both cell lines, N2a and OLN-93, have previously been shown to be a sensitive target for the action of TDA, and cytotoxic effects of TDA have been connected to the induction of oxidative stress. Our data shows that DMSP promotes process outgrowth and microtubule reorganization and bundling, accompanied by an increase in alpha-tubulin acetylation. Furthermore, DMSP was able to prevent the cytotoxic effects exerted by TDA, including the breakdown of the mitochondrial membrane potential, upregulation of heat shock protein Hsp32 and activation of the extracellular signal-regulated kinases 1/2 (ERK1/2). Our study points to the conclusion that DMSP provides an antioxidant defense, not only in algae but also in mammalian neural cells. PMID:27164116

  11. [Extracellular ribonuclease from Bacillus thuringiensis].

    PubMed

    Chepurnova, N K; Liakhov, D L; Rechinskiĭ, V O; Karpeĭskiĭ, M Ia

    1988-04-01

    The ability of the strain Bacillus thuringiensis var. subtoxicus to produce extracellular ribonuclease (ribonuclease Bt) was studied. It was found that the culture medium possesses a RNA-depolymerizing activity whose maximum is observed 4-5 hours after the beginning of the linear growth phase. A three-step chromatography of the culture extract on phosphocellulose resulted in a homogeneous enzyme with a molecular mass of 12000 Da. The enzyme showed the maximum activity towards RNA at pH 8.5, catalyzed the hydrolysis of polyribonucleotides and guanosine-2',3'-cyclophosphate. Hence, the enzyme can be related to base-nonspecific cyclizing ribonucleases showing the guanylic specificity towards nucleoside-2',3'-cyclophosphates.

  12. Acidification of floodplains due to river level decline during drought

    NASA Astrophysics Data System (ADS)

    Mosley, Luke M.; Palmer, David; Leyden, Emily; Cook, Freeman; Zammit, Benjamin; Shand, Paul; Baker, Andrew; W. Fitzpatrick, Rob

    2014-06-01

    A severe drought from 2007 to 2010 resulted in the lowest river levels (1.75 m decline from average) in over 90 years of records at the end of the Murray-Darling Basin in South Australia. Due to the low river level and inability to apply irrigation, the groundwater depth on the adjacent agricultural flood plain also declined substantially (1-1.5 m) and the alluvial clay subsoils dried and cracked. Sulfidic material (pH > 4, predominantly in the form of pyrite, FeS2) in these subsoils oxidised to form sulfuric material (pH < 4) over an estimated 3300 ha on 13 floodplains. Much of the acidity in the deeply cracked contaminated soil layers was in available form (in pore water and on cation exchange sites), with some layers having retained acidity (iron oxyhydroxysulfate mineral jarosite). Post drought, the rapid raising of surface and ground water levels mobilised acidity in acid sulfate soil profiles to the floodplain drainage channels and this was transported back to the river via pumping. The drainage water exhibited low pH (2-5) with high soluble metal (Al, Co, Mn, Fe, Mn, Ni, and Zn) concentrations, in exceedance of guidelines for ecosystem protection. Irrigation increased the short-term transport of acidity, however loads were generally greater in the non-irrigation (winter) season when rainfall is highest (0.0026 tonnes acidity/ha/day) than in the irrigation (spring-summer) season (0.0013 tonnes acidity/ha/day). Measured reductions in groundwater acidity and increases in pH have been observed over time but severe acidification persisted in floodplain sediments and waters for over two years post-drought. Results from 2-dimensional modelling of the river-floodplain hydrological processes were consistent with field measurements during the drying phase and illustrated how the declining river levels led to floodplain acidification. A modelled management scenario demonstrated how river level stabilisation and limited irrigation could have prevented, or greatly

  13. Acidification of floodplains due to river level decline during drought.

    PubMed

    Mosley, Luke M; Palmer, David; Leyden, Emily; Cook, Freeman; Zammit, Benjamin; Shand, Paul; Baker, Andrew; W Fitzpatrick, Rob

    2014-06-01

    A severe drought from 2007 to 2010 resulted in the lowest river levels (1.75 m decline from average) in over 90 years of records at the end of the Murray-Darling Basin in South Australia. Due to the low river level and inability to apply irrigation, the groundwater depth on the adjacent agricultural flood plain also declined substantially (1-1.5 m) and the alluvial clay subsoils dried and cracked. Sulfidic material (pH>4, predominantly in the form of pyrite, FeS2) in these subsoils oxidised to form sulfuric material (pH<4) over an estimated 3300 ha on 13 floodplains. Much of the acidity in the deeply cracked contaminated soil layers was in available form (in pore water and on cation exchange sites), with some layers having retained acidity (iron oxyhydroxysulfate mineral jarosite). Post drought, the rapid raising of surface and ground water levels mobilised acidity in acid sulfate soil profiles to the floodplain drainage channels and this was transported back to the river via pumping. The drainage water exhibited low pH (2-5) with high soluble metal (Al, Co, Mn, Fe, Mn, Ni, and Zn) concentrations, in exceedance of guidelines for ecosystem protection. Irrigation increased the short-term transport of acidity, however loads were generally greater in the non-irrigation (winter) season when rainfall is highest (0.0026 tonnes acidity/ha/day) than in the irrigation (spring-summer) season (0.0013 tonnes acidity/ha/day). Measured reductions in groundwater acidity and increases in pH have been observed over time but severe acidification persisted in floodplain sediments and waters for over two years post-drought. Results from 2-dimensional modelling of the river-floodplain hydrological processes were consistent with field measurements during the drying phase and illustrated how the declining river levels led to floodplain acidification. A modelled management scenario demonstrated how river level stabilisation and limited irrigation could have prevented, or greatly lessened

  14. Assessing physiological tipping points in response to ocean acidification

    NASA Astrophysics Data System (ADS)

    Dupont, S. T.; Dorey, N.; Lançon, P.; Thorndyke, M. S.

    2011-12-01

    Impact of near-future ocean acidification on marine invertebrates was mostly assessed in single-species perturbation experiment. Moreover, most of these experiments are short-term, only consider one life-history stage and one or few parameters. They do not take into account important processes such as natural variability and acclimation and evolutionary processes. In many studies published so far, there is a clear lack between the observed effects and individual fitness, most of the deviation from the control being considered as potentially negative for the tested species. However, individuals are living in a fluctuating world and changes can also be interpreted as phenotypic plasticity and may not translate into negative impact on fitness. For example, a vent mussel can survive for decades in very acidic waters despite a significantly reduced calcification compare to control (Tunnicliffe et al. 2009). This is possible thanks to the absence of predatory crabs as a result of acidic conditions that may also inhibit carapace formation. This illustrates the importance to take into account ecological interactions when interpreting single-species experiments and to consider the relative fitness between interacting species. To understand the potential consequence of ocean acidification on any given ecosystem, it is then critical to consider the relative impact on fitness for every interactive species and taking into account the natural fluctuation in environment (e.g. pH, temperature, food concentration, abundance) and discriminate between plasticity with no direct impact on fitness and teratology with direct consequence on survival. In this presentation, we will introduce the concept of "physiological tipping point" in the context of ocean acidification. This will be illustrated by some work done on sea urchin development. Embryos and larvae of the sea urchin Strongylocentrotus droebachiensis were exposed to a range of pH from 8.1 to 6.5. When exposed to low pH, growth

  15. Co-transfection of decorin and interleukin-10 modulates pro-fibrotic extracellular matrix gene expression in human tenocyte culture

    NASA Astrophysics Data System (ADS)

    Abbah, Sunny A.; Thomas, Dilip; Browne, Shane; O’Brien, Timothy; Pandit, Abhay; Zeugolis, Dimitrios I.

    2016-02-01

    Extracellular matrix synthesis and remodelling are driven by increased activity of transforming growth factor beta 1 (TGF-β1). In tendon tissue repair, increased activity of TGF-β1 leads to progressive fibrosis. Decorin (DCN) and interleukin 10 (IL-10) antagonise pathological collagen synthesis by exerting a neutralising effect via downregulation of TGF-β1. Herein, we report that the delivery of DCN and IL-10 transgenes from a collagen hydrogel system supresses the constitutive expression of TGF-β1 and a range of pro-fibrotic extracellular matrix genes.

  16. Divergent ecosystem responses within a benthic marine community to ocean acidification.

    PubMed

    Kroeker, Kristy J; Micheli, Fiorenza; Gambi, Maria Cristina; Martz, Todd R

    2011-08-30

    Ocean acidification is predicted to impact all areas of the oceans and affect a diversity of marine organisms. However, the diversity of responses among species prevents clear predictions about the impact of acidification at the ecosystem level. Here, we used shallow water CO(2) vents in the Mediterranean Sea as a model system to examine emergent ecosystem responses to ocean acidification in rocky reef communities. We assessed in situ benthic invertebrate communities in three distinct pH zones (ambient, low, and extreme low), which differed in both the mean and variability of seawater pH along a continuous gradient. We found fewer taxa, reduced taxonomic evenness, and lower biomass in the extreme low pH zones. However, the number of individuals did not differ among pH zones, suggesting that there is density compensation through population blooms of small acidification-tolerant taxa. Furthermore, the trophic structure of the invertebrate community shifted to fewer trophic groups and dominance by generalists in extreme low pH, suggesting that there may be a simplification of food webs with ocean acidification. Despite high variation in individual species' responses, our findings indicate that ocean acidification decreases the diversity, biomass, and trophic complexity of benthic marine communities. These results suggest that a loss of biodiversity and ecosystem function is expected under extreme acidification scenarios.

  17. Divergent ecosystem responses within a benthic marine community to ocean acidification

    PubMed Central

    Kroeker, Kristy J.; Micheli, Fiorenza; Gambi, Maria Cristina; Martz, Todd R.

    2011-01-01

    Ocean acidification is predicted to impact all areas of the oceans and affect a diversity of marine organisms. However, the diversity of responses among species prevents clear predictions about the impact of acidification at the ecosystem level. Here, we used shallow water CO2 vents in the Mediterranean Sea as a model system to examine emergent ecosystem responses to ocean acidification in rocky reef communities. We assessed in situ benthic invertebrate communities in three distinct pH zones (ambient, low, and extreme low), which differed in both the mean and variability of seawater pH along a continuous gradient. We found fewer taxa, reduced taxonomic evenness, and lower biomass in the extreme low pH zones. However, the number of individuals did not differ among pH zones, suggesting that there is density compensation through population blooms of small acidification-tolerant taxa. Furthermore, the trophic structure of the invertebrate community shifted to fewer trophic groups and dominance by generalists in extreme low pH, suggesting that there may be a simplification of food webs with ocean acidification. Despite high variation in individual species’ responses, our findings indicate that ocean acidification decreases the diversity, biomass, and trophic complexity of benthic marine communities. These results suggest that a loss of biodiversity and ecosystem function is expected under extreme acidification scenarios. PMID:21844331

  18. Focus on Extracellular Vesicles: Therapeutic Potential of Stem Cell-Derived Extracellular Vesicles.

    PubMed

    Zhang, Bin; Yeo, Ronne Wee Yeh; Tan, Kok Hian; Lim, Sai Kiang

    2016-02-06

    The intense research focus on stem and progenitor cells could be attributed to their differentiation potential to generate new cells to replace diseased or lost cells in many highly intractable degenerative diseases, such as Alzheimer disease, multiple sclerosis, and heart diseases. However, experimental and clinical studies have increasingly attributed the therapeutic efficacy of these cells to their secretion. While stem and progenitor cells secreted many therapeutic molecules, none of these molecules singly or in combination could recapitulate the functional effects of stem cell transplantations. Recently, it was reported that extracellular vesicles (EVs) could recapitulate the therapeutic effects of stem cell transplantation. Based on the observations reported thus far, the prevailing hypothesis is that stem cell EVs exert their therapeutic effects by transferring biologically active molecules such as proteins, lipids, mRNA, and microRNA from the stem cells to injured or diseased cells. In this respect, stem cell EVs are similar to EVs from other cell types. They are both primarily vehicles for intercellular communication. Therefore, the differentiating factor is likely due to the composition of their cargo. The cargo of EVs from different cell types are known to include a common set of proteins and also proteins that reflect the cell source of the EVs and the physiological or pathological state of the cell source. Hence, elucidation of the stem cell EV cargo would provide an insight into the multiple physiological or biochemical changes necessary to affect the many reported stem cell-based therapeutic outcomes in a variety of experimental models and clinical trials.

  19. Matriptase activation and shedding through PDGF-D-mediated extracellular acidosis

    PubMed Central

    Najy, Abdo J.; Dyson, Gregory; Jena, Bhanu P.; Lin, Chen-Yong

    2015-01-01

    Activation of β-platelet-derived growth factor receptor (β-PDGFR) is associated with prostate cancer (PCa) progression and recurrence after prostatectomy. Analysis of the β-PDGFR ligands in PCa revealed association between PDGF-D expression and Gleason score as well as tumor stage. During the course of studying the functional consequences of PDGF ligand-specific β-PDGFR signaling in PCa, we discovered a novel function of PDGF-D for activation/shedding of the serine protease matriptase leading to cell invasion, migration, and tumorigenesis. The present study showed that PDGF-D, not PDGF-B, induces extracellular acidification, which correlates with increased matriptase activation. A cDNA microarray analysis revealed that PDGF-D/β-PDGFR signaling upregulates expression of the acidosis regulator carbonic anhydrase IX (CAIX), a classic target of the transcriptional factor hypoxia-inducible factor-1α (HIF-1α). Cellular fractionation displayed a strong HIF-1α nuclear localization in PDGF-D-expressing cells. Treatment of vector control or PDGF-B-expressing cells with the HIF-1α activator CoCl2 led to increased CAIX expression accompanied by extracellular acidosis and matriptase activation. Furthermore, the analysis of the CAFTD cell lines, variants of the BPH-1 transformation model, showed that increased PDGF-D expression is associated with enhanced HIF-1α activity, CAIX induction, cellular acidosis, and matriptase shedding. Importantly, shRNA-mediated knockdown of CAIX expression effectively reversed extracellular acidosis and matriptase activation in PDGF-D-transfected BPH-1 cells and in CAFTD variants that express endogenous PDGF-D at a high level. Taken together, these novel findings reveal a new paradigm in matriptase activation involving PDGF-D-specific signal transduction leading to extracellular acidosis. PMID:26157007

  20. Matriptase activation and shedding through PDGF-D-mediated extracellular acidosis.

    PubMed

    Najy, Abdo J; Dyson, Gregory; Jena, Bhanu P; Lin, Chen-Yong; Kim, Hyeong-Reh C

    2016-02-15

    Activation of β-platelet-derived growth factor receptor (β-PDGFR) is associated with prostate cancer (PCa) progression and recurrence after prostatectomy. Analysis of the β-PDGFR ligands in PCa revealed association between PDGF-D expression and Gleason score as well as tumor stage. During the course of studying the functional consequences of PDGF ligand-specific β-PDGFR signaling in PCa, we discovered a novel function of PDGF-D for activation/shedding of the serine protease matriptase leading to cell invasion, migration, and tumorigenesis. The present study showed that PDGF-D, not PDGF-B, induces extracellular acidification, which correlates with increased matriptase activation. A cDNA microarray analysis revealed that PDGF-D/β-PDGFR signaling upregulates expression of the acidosis regulator carbonic anhydrase IX (CAIX), a classic target of the transcriptional factor hypoxia-inducible factor-1α (HIF-1α). Cellular fractionation displayed a strong HIF-1α nuclear localization in PDGF-D-expressing cells. Treatment of vector control or PDGF-B-expressing cells with the HIF-1α activator CoCl2 led to increased CAIX expression accompanied by extracellular acidosis and matriptase activation. Furthermore, the analysis of the CAFTD cell lines, variants of the BPH-1 transformation model, showed that increased PDGF-D expression is associated with enhanced HIF-1α activity, CAIX induction, cellular acidosis, and matriptase shedding. Importantly, shRNA-mediated knockdown of CAIX expression effectively reversed extracellular acidosis and matriptase activation in PDGF-D-transfected BPH-1 cells and in CAFTD variants that express endogenous PDGF-D at a high level. Taken together, these novel findings reveal a new paradigm in matriptase activation involving PDGF-D-specific signal transduction leading to extracellular acidosis.

  1. Coccolithophore calcification response to past ocean acidification and climate change.

    PubMed

    O'Dea, Sarah A; Gibbs, Samantha J; Bown, Paul R; Young, Jeremy R; Poulton, Alex J; Newsam, Cherry; Wilson, Paul A

    2014-11-17

    Anthropogenic carbon dioxide emissions are forcing rapid ocean chemistry changes and causing ocean acidification (OA), which is of particular significance for calcifying organisms, including planktonic coccolithophores. Detailed analysis of coccolithophore skeletons enables comparison of calcite production in modern and fossil cells in order to investigate biomineralization response of ancient coccolithophores to climate change. Here we show that the two dominant coccolithophore taxa across the Paleocene-Eocene Thermal Maximum (PETM) OA global warming event (~56 million years ago) exhibited morphological response to environmental change and both showed reduced calcification rates. However, only Coccolithus pelagicus exhibits a transient thinning of coccoliths, immediately before the PETM, that may have been OA-induced. Changing coccolith thickness may affect calcite production more significantly in the dominant modern species Emiliania huxleyi, but, overall, these PETM records indicate that the environmental factors that govern taxonomic composition and growth rate will most strongly influence coccolithophore calcification response to anthropogenic change.

  2. Understanding ocean acidification impacts on organismal to ecological scales

    USGS Publications Warehouse

    Andersson, Andreas J; Kline, David I; Edmunds, Peter J; Archer, Stephen D; Bednaršek, Nina; Carpenter, Robert C; Chadsey, Meg; Goldstein, Philip; Grottoli, Andrea G.; Hurst, Thomas P; King, Andrew L; Kübler, Janet E.; Kuffner, Ilsa B.; Mackey, Katherine R M; Menge, Bruce A.; Paytan, Adina; Riebesell, Ulf; Schnetzer, Astrid; Warner, Mark E; Zimmerman, Richard C

    2015-01-01

    Ocean acidification (OA) research seeks to understand how marine ecosystems and global elemental cycles will respond to changes in seawater carbonate chemistry in combination with other environmental perturbations such as warming, eutrophication, and deoxygenation. Here, we discuss the effectiveness and limitations of current research approaches used to address this goal. A diverse combination of approaches is essential to decipher the consequences of OA to marine organisms, communities, and ecosystems. Consequently, the benefits and limitations of each approach must be considered carefully. Major research challenges involve experimentally addressing the effects of OA in the context of large natural variability in seawater carbonate system parameters and other interactive variables, integrating the results from different research approaches, and scaling results across different temporal and spatial scales.

  3. Effect of acidification on carrot (Daucus carota) juice cloud stability.

    PubMed

    Schultz, Alison K; Barrett, Diane M; Dungan, Stephanie R

    2014-11-26

    Effects of acidity on cloud stability in pasteurized carrot juice were examined over the pH range of 3.5-6.2. Cloud sedimentation, particle diameter, and ζ potential were measured at each pH condition to quantify juice cloud stability and clarification during 3 days of storage. Acidification below pH 4.9 resulted in a less negative ζ potential, an increased particle size, and an unstable cloud, leading to juice clarification. As the acidity increased, clarification occurred more rapidly and to a greater extent. Only a weak effect of ionic strength was observed when sodium salts were added to the juice, but the addition of calcium salts significantly reduced the cloud stability.

  4. Will krill fare well under Southern Ocean acidification?

    PubMed

    Kawaguchi, So; Kurihara, Haruko; King, Robert; Hale, Lillian; Berli, Thomas; Robinson, James P; Ishida, Akio; Wakita, Masahide; Virtue, Patti; Nicol, Stephen; Ishimatsu, Atsushi

    2011-04-23

    Antarctic krill embryos and larvae were experimentally exposed to 380 (control), 1000 and 2000 µatm pCO₂ in order to assess the possible impact of ocean acidification on early development of krill. No significant effects were detected on embryonic development or larval behaviour at 1000 µatm pCO₂; however, at 2000 µatm pCO₂ development was disrupted before gastrulation in 90 per cent of embryos, and no larvae hatched successfully. Our model projections demonstrated that Southern Ocean sea water pCO₂ could rise up to 1400 µatm in krill's depth range under the IPCC IS92a scenario by the year 2100 (atmospheric pCO₂ 788 µatm). These results point out the urgent need for understanding the pCO₂-response relationship for krill developmental and later stages, in order to predict the possible fate of this key species in the Southern Ocean.

  5. Ecological impacts of ocean acidification in coastal marine environments (Invited)

    NASA Astrophysics Data System (ADS)

    Harley, C.; Crim, R.; Gooding, R.; Nienhuis, S.; Tang, E.

    2010-12-01

    Rising atmospheric carbon dioxide concentrations are driving rapid and potentially unprecedented reductions in pH and carbonate ion availability in coastal marine environments. This process, known as ocean acidification (OA), has far-reaching implications for the performance and survival of marine organisms, particularly those with calcified shells and skeletons. Here, we highlight the ways in which OA impacts plants and animals in a coastal benthic food web, with an emphasis on what we know and what we don’t know about the ways in which the responses of individual organisms will scale up to long-term changes in community structure. Our system of interest is the rocky shore benthic community that is broadly represented from Alaska through California. Ecologically important species include producers (micro- and macro-algae), grazers (urchins and gastropods), filter feeders (mussels), and predators (sea stars). Although the direct effects of OA on coastal phytoplankton and kelps remain poorly understood, it appears as though elevated CO2 will increase the doubling rate of benthic diatoms. Small changes in food supply, however, may pale in comparison to the direct effects of OA on heavily calcified grazers and filter feeders. Sea urchin and mussel growth are both reduced by increased CO2 in the lab, and decadal-scale reductions in pH are associated with reduced turban snail growth in the field. Although adult abalone growth appears to be unaffected by CO2, larval development is impaired and larval survival is significantly reduced in acidified conditions. In contrast to the negative effects of OA on heavily calcified herbivores and filter feeders, lightly calcified sea stars actually grow faster when CO2 is experimentally increased. The acidification-induced changes described here are likely to result in substantial shifts in the benthic ecosystem. Increasing predation pressure may further reduce the abundance of grazers and filter feeders that are already suffering

  6. Regional adaptation defines sensitivity to future ocean acidification

    PubMed Central

    Calosi, Piero; Melatunan, Sedercor; Turner, Lucy M.; Artioli, Yuri; Davidson, Robert L.; Byrne, Jonathan J.; Viant, Mark R.; Widdicombe, Stephen; Rundle, Simon D.

    2017-01-01

    Physiological responses to temperature are known to be a major determinant of species distributions and can dictate the sensitivity of populations to global warming. In contrast, little is known about how other major global change drivers, such as ocean acidification (OA), will shape species distributions in the future. Here, by integrating population genetics with experimental data for growth and mineralization, physiology and metabolomics, we demonstrate that the sensitivity of populations of the gastropod Littorina littorea to future OA is shaped by regional adaptation. Individuals from populations towards the edges of the natural latitudinal range in the Northeast Atlantic exhibit greater shell dissolution and the inability to upregulate their metabolism when exposed to low pH, thus appearing most sensitive to low seawater pH. Our results suggest that future levels of OA could mediate temperature-driven shifts in species distributions, thereby influencing future biogeography and the functioning of marine ecosystems. PMID:28067268

  7. Regional adaptation defines sensitivity to future ocean acidification.

    PubMed

    Calosi, Piero; Melatunan, Sedercor; Turner, Lucy M; Artioli, Yuri; Davidson, Robert L; Byrne, Jonathan J; Viant, Mark R; Widdicombe, Stephen; Rundle, Simon D

    2017-01-09

    Physiological responses to temperature are known to be a major determinant of species distributions and can dictate the sensitivity of populations to global warming. In contrast, little is known about how other major global change drivers, such as ocean acidification (OA), will shape species distributions in the future. Here, by integrating population genetics with experimental data for growth and mineralization, physiology and metabolomics, we demonstrate that the sensitivity of populations of the gastropod Littorina littorea to future OA is shaped by regional adaptation. Individuals from populations towards the edges of the natural latitudinal range in the Northeast Atlantic exhibit greater shell dissolution and the inability to upregulate their metabolism when exposed to low pH, thus appearing most sensitive to low seawater pH. Our results suggest that future levels of OA could mediate temperature-driven shifts in species distributions, thereby influencing future biogeography and the functioning of marine ecosystems.

  8. A virtual rat for simulating environmental and exertional heat stress.

    PubMed

    Rakesh, Vineet; Stallings, Jonathan D; Reifman, Jaques

    2014-12-01

    Severe cases of environmental or exertional heat stress can lead to varying degrees of organ dysfunction. To understand heat-injury progression and develop efficient management and mitigation strategies, it is critical to determine the thermal response in susceptible organs under different heat-stress conditions. To this end, we used our previously published virtual rat, which is capable of computing the spatiotemporal temperature distribution in the animal, and extended it to simulate various heat-stress scenarios, including 1) different environmental conditions, 2) exertional heat stress, 3) circadian rhythm effect on the thermal response, and 4) whole body cooling. Our predictions were consistent with published in vivo temperature measurements for all cases, validating our simulations. We observed a differential thermal response in the organs, with the liver experiencing the highest temperatures for all environmental and exertional heat-stress cases. For every 3°C rise in the external temperature from 40 to 46°C, core and organ temperatures increased by ∼0.8°C. Core temperatures increased by 2.6 and 4.1°C for increases in exercise intensity from rest to 75 and 100% of maximal O2 consumption, respectively. We also found differences as large as 0.8°C in organ temperatures for the same heat stress induced at different times during the day. Even after whole body cooling at a relatively low external temperature (1°C for 20 min), average organ temperatures were still elevated by 2.3 to 2.5°C compared with normothermia. These results can be used to optimize experimental protocol designs, reduce the amount of animal experimentation, and design and test improved heat-stress prevention and management strategies.

  9. Pressure garment design tool to monitor exerted pressures.

    PubMed

    Macintyre, Lisa; Ferguson, Rhona

    2013-09-01

    Pressure garments are used in the treatment of hypertrophic scarring following serious burns. The use of pressure garments is believed to hasten the maturation process, reduce pruritus associated with immature hypertrophic scars and prevent the formation of contractures over flexor joints. Pressure garments are normally made to measure for individual patients from elastic fabrics and are worn continuously for up to 2 years or until scar maturation. There are 2 methods of constructing pressure garments. The most common method, called the Reduction Factor method, involves reducing the patient's circumferential measurements by a certain percentage. The second method uses the Laplace Law to calculate the dimensions of pressure garments based on the circumferential measurements of the patient and the tension profile of the fabric. The Laplace Law method is complicated to utilise manually and no design tool is currently available to aid this process. This paper presents the development and suggested use of 2 new pressure garment design tools that will aid pressure garment design using the Reduction Factor and Laplace Law methods. Both tools calculate the pressure garment dimensions and the mean pressure that will be exerted around the body at each measurement point. Monitoring the pressures exerted by pressure garments and noting the clinical outcome would enable clinicians to build an understanding of the implications of particular pressures on scar outcome, maturation times and patient compliance rates. Once the optimum pressure for particular treatments is known, the Laplace Law method described in this paper can be used to deliver those average pressures to all patients. This paper also presents the results of a small scale audit of measurements taken for the fabrication of pressure garments in two UK hospitals. This audit highlights the wide range of pressures that are exerted using the Reduction Factor method and that manual pattern 'smoothing' can dramatically

  10. Developmental genetics of secretory vesicle acidification during Caenorhabditis elegans spermatogenesis.

    PubMed

    Gleason, Elizabeth J; Hartley, Paul D; Henderson, Melissa; Hill-Harfe, Katherine L; Price, Paul W; Weimer, Robby M; Kroft, Tim L; Zhu, Guang-Dan; Cordovado, Suzanne; L'Hernault, Steven W

    2012-06-01

    Secretory vesicles are used during spermatogenesis to deliver proteins to the cell surface. In Caenorhabditis elegans, secretory membranous organelles (MO) fuse with the plasma membrane to transform spermatids into fertilization-competent spermatozoa. We show that, like the acrosomal vesicle of mammalian sperm, MOs undergo acidification during development. Treatment of spermatids with the V-ATPase inhibitor bafilomycin blocks both MO acidification and formation of functional spermatozoa. There are several spermatogenesis-defective mutants that cause defects in MO morphogenesis, including spe-5. We determined that spe-5, which is on chromosome I, encodes one of two V-ATPase B paralogous subunits. The spe-5 null mutant is viable but sterile because it forms arrested, multi-nucleate spermatocytes. Immunofluorescence with a SPE-5-specific monoclonal antibody shows that SPE-5 expression begins in spermatocytes and is found in all subsequent stages of spermatogenesis. Most SPE-5 is discarded into the residual body during spermatid budding, but a small amount remains in budded spermatids where it localizes to MOs as a discrete dot. The other V-ATPase B subunit is encoded by vha-12, which is located on the X chromosome. Usually, spe-5 mutants are self-sterile in a wild-type vha-12 background. However, an extrachromosomal transgene containing wild-type vha-12 driven by its own promoter allows spe-5 mutant hermaphrodites to produce progeny, indicating that VHA-12 can at least partially substitute for SPE-5. Others have shown that the X chromosome is transcriptionally silent in the male germline, so expression of the autosomally located spe-5 gene ensures that a V-ATPase B subunit is present during spermatogenesis.

  11. Impact of near-future ocean acidification on echinoderms.

    PubMed

    Dupont, S; Ortega-Martínez, O; Thorndyke, M

    2010-03-01

    As a consequence of increasing atmospheric CO(2), the world's oceans are warming and slowly becoming more acidic (ocean acidification, OA) and profound changes in marine ecosystems are certain. Calcification is one of the primary targets for studies of the impact of CO(2)-driven climate change in the oceans and one of the key marine groups most likely to be impacted by predicted climate change events are the echinoderms. Echinoderms are a vital component of the marine environment with representatives in virtually every ecosystem, where they are often keystone ecosystem engineers. This paper reviews and analyses what is known about the impact of near-future ocean acidification on echinoderms. A global analysis of the literature reveals that echinoderms are surprisingly robust to OA and that important differences in sensitivity to OA are observed between populations and species. However, this is modulated by parameters such as (1) exposure time with rare longer term experiments revealing negative impacts that are hidden in short or midterm ones; (2) bottlenecks in physiological processes and life-cycle such as stage-specific developmental phenomena that may drive the whole species responses; (3) ecological feedback transforming small scale sub lethal effects into important negative effects on fitness. We hypothesize that populations/species naturally exposed to variable environmental pH conditions may be pre-adapted to future OA highlighting the importance to understand and monitor environmental variations in order to be able to to predict sensitivity to future climate changes. More stress ecology research is needed at the frontier between ecotoxicology and ecology, going beyond standardized tests using model species in order to address multiple water quality factors (e.g. pH, temperature, toxicants) and organism health. However, available data allow us to conclude that near-future OA will have negative impact on echinoderm taxa with likely significant consequences

  12. Ocean acidification decreases plankton respiration: evidence from a mesocosm experiment

    NASA Astrophysics Data System (ADS)

    Spilling, Kristian; Paul, Allanah J.; Virkkala, Niklas; Hastings, Tom; Lischka, Silke; Stuhr, Annegret; Bermúdez, Rafael; Czerny, Jan; Boxhammer, Tim; Schulz, Kai G.; Ludwig, Andrea; Riebesell, Ulf

    2016-08-01

    Anthropogenic carbon dioxide (CO2) emissions are reducing the pH in the world's oceans. The plankton community is a key component driving biogeochemical fluxes, and the effect of increased CO2 on plankton is critical for understanding the ramifications of ocean acidification on global carbon fluxes. We determined the plankton community composition and measured primary production, respiration rates and carbon export (defined here as carbon sinking out of a shallow, coastal area) during an ocean acidification experiment. Mesocosms ( ˜ 55 m3) were set up in the Baltic Sea with a gradient of CO2 levels initially ranging from ambient ( ˜ 240 µatm), used as control, to high CO2 (up to ˜ 1330 µatm). The phytoplankton community was dominated by dinoflagellates, diatoms, cyanobacteria and chlorophytes, and the zooplankton community by protozoans, heterotrophic dinoflagellates and cladocerans. The plankton community composition was relatively homogenous between treatments. Community respiration rates were lower at high CO2 levels. The carbon-normalized respiration was approximately 40 % lower in the high-CO2 environment compared with the controls during the latter phase of the experiment. We did not, however, detect any effect of increased CO2 on primary production. This could be due to measurement uncertainty, as the measured total particular carbon (TPC) and combined results presented in this special issue suggest that the reduced respiration rate translated into higher net carbon fixation. The percent carbon derived from microscopy counts (both phyto- and zooplankton), of the measured total particular carbon (TPC), decreased from ˜ 26 % at t0 to ˜ 8 % at t31, probably driven by a shift towards smaller plankton (< 4 µm) not enumerated by microscopy. Our results suggest that reduced respiration leads to increased net carbon fixation at high CO2. However, the increased primary production did not translate into increased carbon export, and consequently did not work as

  13. Ocean Acidification: Coccolithophore's Light Controlled Effect on Alkalinity

    NASA Astrophysics Data System (ADS)

    Dobbins, W.

    2015-12-01

    Coccolithophorids, which play a significant role in the flux of calcite and organic carbon from the photic region to deeper pelagic and benthic zones, are potentially far more useful than siliceous phytoplankton for ocean fertilization projects designed to sequester CO2. However, the production of H+ ions during calcification (HCO3 + Ca+ —> CaCO3 + H+) has resulted in localized acidification around coccolithophore blooms. It has been hypothesized that under the correct light conditions photosynthesis could proceed at a rate such that CO2 is removed in amounts equimolar or greater than the H+ produced by calcification, allowing stable or increasing alkalinity despite ongoing calcification. Previously, this effect had not been demonstrated under laboratory conditions. Fifteen Emiliania huxleyi cultures were separated into equal groups with each receiving: 0, 6, 12, 18, or 24 hours of light each day for 24 days. Daily pH, cell density, and temperature measurements revealed a strong positive correlation between light exposure and pH, and no significant decline in pH in any of the cultures. Alkalinity increases were temperature independent and not strongly correlated with cell density, implying photosynthetic removal of carbon dioxide as the root cause. The average pH across living cultures increased from 7.9 to 8.3 over the first week and changed little for the reminder of the 24-day period. The results demonstrate coccolithophorids can increase alkalinity across a broad range of cell densities, despite the acidification inherent to the calcification process. If the light-alkalinity effect reported here proves scalable to larger cultures, Emiliania huxleyi are a strong candidate for carbon sequestration via targeted ocean fertilization.

  14. Responses of subepilimnetic primary producers to experimental lake acidification

    SciTech Connect

    Moffett, M.F.

    1991-01-01

    Subepilimnetic phytoplankton communities were found to increase in abundance during experimental acidification with sulfuric acid of two Canadian Shield lakes, Lake 223 and Lake 302S, at the Experimental Lakes Area (ELA) in northwestern Ontario. As epilimnetic pH declined in Lake 223, small, edible species of phytoplankton increased more than larger, less edible taxa. Species diversity ultimately decreased when epilimnetic acidity reached the target pH 5.0. In Lake 302S algal populations, Chrysochromulina spp. and Chlamydomonas sp., reached [open quotes]bloom[close quotes] conditions below the epilimnion in the third and fourth summers, respectively, of sulfuric acid additions as pH declined from above pH 6 to pH 5.6 and 5.4. Meta- and hypolimnetic waters of these lakes did not experience similar declines in pH. All responses in Lake 223 and Lake 302S were in contrast to communities in 5-10 ELA lakes not undergoing acidification. Vertical depth profiles of chlorophyll fluorescence were used to follow trends in subepilimnetic communities during the first four years of sulfuric acid additions to Lake 302S. Fluorescence was found to reliably predict chlorophyll a concentrations (r[sup 2] = 0.80-0.94). Characteristics of subepilimnetic communities and the habitats in which they were located were studied at the ELA. Many were mixed with photosynthetic bacteria. Fluorometric techniques with DCMU (3-(3,4-dichlorophenyl-1,1-dimethyl urea)) were used to determine which fluorescence maxima contained viable algal populations. In situ inorganic carbon uptake rates for the algal-dominated communities below the epilimnion were similar to rates by epilimnetic communities. Enclosure experiments demonstrated that growth and inorganic carbon uptake rates of subepilimnetic algal populations were light-limited.

  15. Contrasting effects of ocean acidification on reproduction in reef fishes

    NASA Astrophysics Data System (ADS)

    Welch, Megan J.; Munday, Philip L.

    2016-06-01

    Differences in the sensitivity of marine species to ocean acidification will influence the structure of marine communities in the future. Reproduction is critical for individual and population success, yet is energetically expensive and could be adversely affected by rising CO2 levels in the ocean. We investigated the effects of projected future CO2 levels on reproductive output of two species of coral reef damselfish, Amphiprion percula and Acanthochromis polyacanthus. Adult breeding pairs were maintained at current-day control (446 μatm), moderate (652 μatm) or high CO2 (912 μatm) for a 9-month period that included the summer breeding season. The elevated CO2 treatments were consistent with CO2 levels projected by 2100 under moderate (RCP6) and high (RCP8) emission scenarios. Reproductive output increased in A. percula, with 45-75 % more egg clutches produced and a 47-56 % increase in the number of eggs per clutch in the two elevated CO2 treatments. In contrast, reproductive output decreased at high CO2 in Ac. polyacanthus, with approximately one-third as many clutches produced compared with controls. Egg survival was not affected by CO2 for A. percula, but was greater in elevated CO2 for Ac. polyacanthus. Hatching success was also greater for Ac. polyacanthus at elevated CO2, but there was no effect of CO2 treatments on offspring size. Despite the variation in reproductive output, body condition of adults did not differ between control and CO2 treatments in either species. Our results demonstrate different effects of high CO2 on fish reproduction, even among species within the same family. A greater understanding of the variation in effects of ocean acidification on reproductive performance is required to predict the consequences for future populations of marine organisms.

  16. Ocean acidification risk assessment for Alaska's fishery sector

    NASA Astrophysics Data System (ADS)

    Mathis, J. T.; Cooley, S. R.; Lucey, N.; Colt, S.; Ekstrom, J.; Hurst, T.; Hauri, C.; Evans, W.; Cross, J. N.; Feely, R. A.

    2015-08-01

    The highly productive fisheries of Alaska are located in seas projected to experience strong global change, including rapid transitions in temperature and ocean acidification-driven changes in pH and other chemical parameters. Many of the marine organisms that are most intensely affected by ocean acidification (OA) contribute substantially to the state's commercial fisheries and traditional subsistence way of life. Prior studies of OA's potential impacts on human communities have focused only on possible direct economic losses from specific scenarios of human dependence on commercial harvests and damages to marine species. However, other economic and social impacts, such as changes in food security or livelihoods, are also likely to result from climate change. This study evaluates patterns of dependence on marine resources within Alaska that could be negatively impacted by OA and current community characteristics to assess the potential risk to the fishery sector from OA. Here, we used a risk assessment framework based on one developed by the Intergovernmental Panel on Climate Change to analyze earth-system global ocean model hindcasts and projections of ocean chemistry, fisheries harvest data, and demographic information. The fisheries examined were: shellfish, salmon and other finfish. The final index incorporates all of these data to compare overall risk among Alaska's federally designated census areas. The analysis showed that regions in southeast and southwest Alaska that are highly reliant on fishery harvests and have relatively lower incomes and employment alternatives likely face the highest risk from OA. Although this study is an intermediate step toward our full understanding, the results presented here show that OA merits consideration in policy planning, as it may represent another challenge to Alaskan communities, some of which are already under acute socio-economic strains.

  17. Ocean Warming–Acidification Synergism Undermines Dissolved Organic Matter Assembly

    PubMed Central

    Chen, Chi-Shuo; Anaya, Jesse M.; Chen, Eric Y-T; Farr, Erik; Chin, Wei-Chun

    2015-01-01

    Understanding the influence of synergisms on natural processes is a critical step toward determining the full-extent of anthropogenic stressors. As carbon emissions continue unabated, two major stressors—warming and acidification—threaten marine systems on several scales. Here, we report that a moderate temperature increase (from 30°C to 32°C) is sufficient to slow— even hinder—the ability of dissolved organic matter, a major carbon pool, to self-assemble to form marine microgels, which contribute to the particulate organic matter pool. Moreover, acidification lowers the temperature threshold at which we observe our results. These findings carry implications for the marine carbon cycle, as self-assembled marine microgels generate an estimated global seawater budget of ~1016 g C. We used laser scattering spectroscopy to test the influence of temperature and pH on spontaneous marine gel assembly. The results of independent experiments revealed that at a particular point, both pH and temperature block microgel formation (32°C, pH 8.2), and disperse existing gels (35°C). We then tested the hypothesis that temperature and pH have a synergistic influence on marine gel dispersion. We found that the dispersion temperature decreases concurrently with pH: from 32°C at pH 8.2, to 28°C at pH 7.5. If our laboratory observations can be extrapolated to complex marine environments, our results suggest that a warming–acidification synergism can decrease carbon and nutrient fluxes, disturbing marine trophic and trace element cycles, at rates faster than projected. PMID:25714090

  18. Historical reconstruction of ocean acidification in the Australian region

    NASA Astrophysics Data System (ADS)

    Lenton, Andrew; Tilbrook, Bronte; Matear, Richard J.; Sasse, Tristan P.; Nojiri, Yukihiro

    2016-03-01

    The ocean has become more acidic over the last 200 years in response increasing atmospheric carbon dioxide (CO2) levels. Documenting how the ocean has changed is critical for assessing how these changes impact marine ecosystems and for the management of marine resources. Here we use present-day ocean carbon observations, from shelf and offshore waters around Australia, combined with neural network mapping of CO2, sea surface temperature, and salinity to estimate the current seasonal and regional distributions of carbonate chemistry (pH and aragonite saturation state). The observed changes in atmospheric CO2 and sea surface temperature (SST) and climatological salinity are then used to reconstruct pH and aragonite saturation state changes over the last 140 years (1870-2013). The comparison with data collected at Integrated Marine Observing System National Reference Station sites located on the shelf around Australia shows that both the mean state and seasonality in the present day are well represented, with the exception of sites such as the Great Barrier Reef. Our reconstruction predicts that since 1870 decrease in aragonite saturation state of 0.48 and of 0.09 in pH has occurred in response to increasing oceanic uptake of atmospheric CO2. Large seasonal variability in pH and aragonite saturation state occur in southwestern Australia driven by ocean dynamics (mixing) and in the Tasman Sea by seasonal warming (in the case of the aragonite saturation state). The seasonal and historical changes in aragonite saturation state and pH have different spatial patterns and suggest that the biological responses to ocean acidification are likely to be non-uniform depending on the relative sensitivity of organisms to shifts in pH and saturation state. This new historical reconstruction provides an important link to biological observations that will help to elucidate the consequences of ocean acidification.

  19. Historical reconstruction of ocean acidification in the Australian region

    NASA Astrophysics Data System (ADS)

    Lenton, A.; Tilbrook, B.; Matear, R. J.; Sasse, T.; Nojiri, Y.

    2015-06-01

    The increase in atmospheric greenhouse gases over the last 200 years has caused an increase in ocean acidity levels. Documenting how the ocean has changed is critical for assessing how these changes could impact marine ecosystems and for the management of marine resources. We use present day ocean carbon observations from shelf and offshore waters around Australia, combined with neural network mapping of CO2, to estimate the current seasonal and regional distributions of carbonate chemistry (pH and aragonite saturation state). These predicted changes in carbonate chemistry are combined with atmospheric CO2 concentration changes since to reconstruct pH and aragonite saturation state changes over the last 140 years (1870-2013). The comparison with data collected at Integrated Marine Observing System National Reference Station sites located on the shelf around Australia shows both the mean state and seasonality for the present day is well represented by our reconstruction, with the exception of sites such as the Great Barrier Reef. Our reconstruction predicts that since 1870 an average decrease in aragonite saturation state of 0.48 and of 0.09 in pH has occurred in response to increasing oceanic uptake of atmospheric CO2. Our reconstruction shows that seasonality is the dominant mode of variability, with only small interannual variability present. Large seasonal variability in pH and aragonite saturation state occur in Southwestern Australia driven by ocean dynamics (mixing) and in the Tasman Sea by seasonal warming (in the case of aragonite saturation state). The seasonal and historical changes in aragonite saturation state and pH have different spatial patterns and suggest that the biological responses to ocean acidification are likely to be non-uniform depending on the relative sensitivity of organisms to shifts in pH and saturation state. This new historical reconstruction provides an important to link to biological observations to help elucidate the consequences

  20. A gender bias in the calcification response to ocean acidification

    NASA Astrophysics Data System (ADS)

    Holcomb, M.; Cohen, A. L.; McCorkle, D. C.

    2011-08-01

    The effects of nutrients and pCO2 on zooxanthellate and azooxanthellate colonies of the temperate scleractinian coral Astrangia poculata (Ellis and Solander, 1786) were investigated at two different temperatures (16 °C and 24 °C). Corals exposed to elevated pCO2 tended to have lower relative calcification rates, as estimated from changes in buoyant weights. No nutrient effect was observed. At 16 °C, gamete release was not observed, and no gender differences in calcification rate were observed. However, corals grown at 24 °C spawned repeatedly and male and female corals exhibited two different growth rate patterns. Female corals grown at 24 °C and exposed to CO2 had calcification rates 39 % lower than females grown at ambient CO2, while males showed only a 5 % decline in calcification under elevated CO2. At 16 °C, female and male corals showed similar reductions in calcification rates in response to elevated CO2 (15 % and 19 % respectively). At 24 °C, corals spawned repeatedly, while no spawning was observed at 16 °C. The increased sensitivity of females to elevated pCO2 may reflect a greater investment of energy in reproduction (egg production) relative to males (sperm production). These results suggest that both gender and spawning are important factors in determining the sensitivity of corals to ocean acidification and their inclusion in future research may be critical to predicting how the population structures of marine calcifiers will change in response to ocean acidification.

  1. Ocean acidification refugia of the Florida Reef Tract.

    PubMed

    Manzello, Derek P; Enochs, Ian C; Melo, Nelson; Gledhill, Dwight K; Johns, Elizabeth M

    2012-01-01

    Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO(2), alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO(2) (TCO(2)) which increases aragonite saturation state (Ω(arag)) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ω(arag) than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error) Ω(arag)-values in spring = 4.69 (±0.101). Conversely, Ω(arag)-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO(2) mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA.

  2. CO2-Induced Acidification of the Laurentian Great Lakes

    NASA Astrophysics Data System (ADS)

    McKinley, G. A.; Phillips, J.; Bennington, V.; Bootsma, H. A.; Pilcher, D.; Sterner, R.; Urban, N. R.

    2013-12-01

    A number of studies indicate that air-water equilibration is the dominant control on pCO2 in several Great Lakes at annual timescales or longer. Assuming this is the case across all lakes at present and into the future, we show that pH will decline by 0.3-0.4 units through 2100 under a business-as-usual CO2 emission scenario. In a survey of the Great Lakes scientific community, 87% of respondents indicate that CO2-driven acidification is likely. The available pH data do not support these predicted trends, but limited sampling in an environment characterized by significant spatio-temporal variability, as well as significant measurement uncertainty, cast doubt on the ability of the historical pH record to resolve the predicted trends. Evaluation of the current sampling strategy using eddy-resolving numerical models of Lake Superior and Lake Michigan are key evidence that the current monitoring strategy is inadequate. In order to track long-term pH change and assess whether atmospheric CO2 will affect the Great Lakes like the oceans, a new approach to Great Lakes pH monitoring is required. Ecological impacts of CO2 acidification have not been studied for the Great Lakes, but potential effects can be gleaned from the literature. In addition, our qualitative and quantitative survey results suggest that processes such as fish recruitment, dreissenid mussel growth, and nutrient cycling may be sensitive to pH, but there is lack of consensus about the magnitude and overall significance of these effects.

  3. Mass extinctions and ocean acidification: biological constraints on geological dilemmas

    NASA Astrophysics Data System (ADS)

    Veron, J. E. N.

    2008-09-01

    The five mass extinction events that the earth has so far experienced have impacted coral reefs as much or more than any other major ecosystem. Each has left the Earth without living reefs for at least four million years, intervals so great that they are commonly referred to as ‘reef gaps’ (geological intervals where there are no remnants of what might have been living reefs). The causes attributed to each mass extinction are reviewed and summarised. When these causes and the reef gaps that follow them are examined in the light of the biology of extant corals and their Pleistocene history, most can be discarded. Causes are divided into (1) those which are independent of the carbon cycle: direct physical destruction from bolides, ‘nuclear winters’ induced by dust clouds, sea-level changes, loss of area during sea-level regressions, loss of biodiversity, low and high temperatures, salinity, diseases and toxins and extraterrestrial events and (2) those linked to the carbon cycle: acid rain, hydrogen sulphide, oxygen and anoxia, methane, carbon dioxide, changes in ocean chemistry and pH. By process of elimination, primary causes of mass extinctions are linked in various ways to the carbon cycle in general and ocean chemistry in particular with clear association with atmospheric carbon dioxide levels. The prospect of ocean acidification is potentially the most serious of all predicted outcomes of anthropogenic carbon dioxide increase. This study concludes that acidification has the potential to trigger a sixth mass extinction event and to do so independently of anthropogenic extinctions that are currently taking place.

  4. Response of Halimeda to ocean acidification: Field and laboratory evidence

    USGS Publications Warehouse

    Robbins, L.L.; Knorr, P.O.; Hallock, P.

    2009-01-01

    Rising atmospheric pCO2 levels are changing ocean chemistry more dramatically now than in the last 20 million years. In fact, pHvalues of the open ocean have decreased by 0.1 since the 1800s and are predicted to decrease 0.1-0.4 globally in the next 90 years. Ocean acidification will affect fundamental geochemical and biological processes including calcification and carbonate sediment production. The west Florida shelf is a natural laboratory to examine the effects of ocean acidification on aragonite production by calcareous green algae. Scanning electron microscopy (SEM) of crystal morphology of calcifying organisms reveals ultrastructural details of calcification that occurred at different saturation states. Comparison of archived and recent specimens of calcareous green alga Halimeda spp. from the west Florida shelf, demonstrates crystal changes in shape and abundance over a 40+ year time span. Halimeda crystal data from apical sections indicate that increases in crystal concentration and decreases in crystal width occurred over the last 40+ years. Laboratory experiments using living specimens of Halimeda grown in environments with known pH values were used to constrain historical observations. Percentages of organic and inorganic carbon per sample weight of pooled species did not significantly change. However, individual species showed decreased inorganic carbon and increased organic carbon in more recent samples, although the sample sizes were limited. These results indicate that the effect of increased pCO 2 and decreased pH on calcification is reflected in the crystal morphology of this organism. More data are needed to confirm the observed changes in mass of crystal and organic carbon. ?? Author(s) 2009.

  5. [Exertion syncope disclosing supravalvular mitral stenosis in an infant].

    PubMed

    Buyse, G; Kuchler, H; Crittin, J; Sekarski, N; Hurni, M; Cotting, J; Payot, M

    1993-05-01

    An infant with frequent upper airways infections presented syncopes during meals and weeping since the age of eleven months. Cardiac examination was always normal. At 14 months of age, an echocardiogram with colour Doppler demonstrated a severely stenotic isolated supramitral membrane with severe pulmonary hypertension. The membrane was immediately excised curing the malformation and suppressing definitively the syncopes, probably due to decreased cerebral blood flow during exertion. An echocardiogram should always be performed when syncopes remain unexplained in small children. It allows early diagnosis and treatment of congenital heart defects which do not have auscultatory findings especially those resulting in severe pulmonary venous obstruction.

  6. Ganoderma lucidum polysaccharide exerts anti-tumor activity via MAPK pathways in HL-60 acute leukemia cells.

    PubMed

    Yang, Guohua; Yang, Lei; Zhuang, Yun; Qian, Xifeng; Shen, Yunfeng

    2016-01-01

    In this study, we investigated the anti-tumor activity both in vitro and in vivo of a polysaccharide obtained from Ganoderma lucidum on HL-60 acute myeloid leukemia cells, and focused on its targeting effect on mitogen-activated protein kinase (MAPK) pathways. It was found by the methods such as western blot and flow cytometry (FCM), that G. lucidum polysaccharide (GLP) blocked the extracellular signal-regulated kinase/MAPK signaling pathway, simultaneously activated p38 and JNK MAPK pathways, and therefore regulated their downstream genes and proteins, including p53, c-myc, c-fos, c-jun, Bcl-2, Bax, cleaved caspase-3 and cyclin D1. As a result, cycle arrest and apoptosis of HL-60 cells were induced. Therefore, GLP exerted anti-tumor activity via MAPK pathways in HL-60 acute leukemia cells.

  7. Extracellular adenosine triphosphate and adenosine in cancer.

    PubMed

    Stagg, J; Smyth, M J

    2010-09-30

    Adenosine triphosphate (ATP) is actively released in the extracellular environment in response to tissue damage and cellular stress. Through the activation of P2X and P2Y receptors, extracellular ATP enhances tissue repair, promotes the recruitment of immune phagocytes and dendritic cells, and acts as a co-activator of NLR family, pyrin domain-containing 3 (NLRP3) inflammasomes. The conversion of extracellular ATP to adenosine, in contrast, essentially through the enzymatic activity of the ecto-nucleotidases CD39 and CD73, acts as a negative-feedback mechanism to prevent excessive immune responses. Here we review the effects of extracellular ATP and adenosine on tumorigenesis. First, we summarize the functions of extracellular ATP and adenosine in the context of tumor immunity. Second, we present an overview of the immunosuppressive and pro-angiogenic effects of extracellular adenosine. Third, we present experimental evidence that extracellular ATP and adenosine receptors are expressed by tumor cells and enhance tumor growth. Finally, we discuss recent studies, including our own work, which suggest that therapeutic approaches that promote ATP-mediated activation of inflammasomes, or inhibit the accumulation of tumor-derived extracellular adenosine, may constitute effective new means to induce anticancer activity.

  8. Participation of intracellular and extracellular pH changes in photosynthetic response development induced by variation potential in pumpkin seedlings.

    PubMed

    Sherstneva, O N; Vodeneev, V A; Katicheva, L A; Surova, L M; Sukhov, V S

    2015-06-01

    Electrical signals presented in plants by action potential and by variation potential (VP) can induce a reversible inactivation of photosynthesis. Changes in the intracellular and extracellular pH during VP generation are a potential mechanism of photosynthetic response induction; however, this hypothesis requires additional experimental investigation. The purpose of the present work was to analyze the influence of pH changes on induction of the photosynthetic response in pumpkin. It was shown that a burning of the cotyledon induced VP propagation into true leaves of pumpkin seedlings inducing a decrease in the photosynthetic CO2 assimilation and an increase in non-photochemical quenching of fluorescence, whereas respiration was activated insignificantly. The photosynthetic response magnitude depended linearly on the VP amplitude. The intracellular and extracellular concentrations of protons were analyzed using pH-sensitive fluorescent probes, and the VP generation was shown to be accompanied by apoplast alkalization (0.4 pH unit) and cytoplasm acidification (0.3 pH unit). The influence of changes in the incubation medium pH on the non-photochemical quenching of fluorescence of isolated chloroplasts was also investigated. It was found that acidification of the medium stimulated the non-photochemical quenching, and the magnitude of this increase depended on the decrease in pH. Our results confirm the contribution of changes in intracellular and extracellular pH to induction of the photosynthetic response caused by VP. Possible mechanisms of the influence of pH changes on photosynthesis are discussed.

  9. Acoustic purification of extracellular microvesicles.

    PubMed

    Lee, Kyungheon; Shao, Huilin; Weissleder, Ralph; Lee, Hakho

    2015-03-24

    Microvesicles (MVs) are an increasingly important source for biomarker discovery and clinical diagnostics. The small size of MVs and their presence in complex biological environment, however, pose technical challenges in sample preparation, particularly when sample volumes are small. We herein present an acoustic nanofilter system that size-specifically separates MVs in a continuous and contact-free manner. The separation uses ultrasound standing waves to exert differential acoustic force on MVs according to their size and density. By optimizing the design of the ultrasound transducers and underlying electronics, we were able to achieve a high separation yield and resolution. The "filter size-cutoff" can be controlled electronically in situ, which enables versatile MV-size selection. We applied the acoustic nanofilter to isolate nanoscale (<200 nm) vesicles from cell culture media as well as MVs in stored red blood cell products. With the capacity for rapid and contact-free MV isolation, the developed system could become a versatile preparatory tool for MV analyses.

  10. Caffeine ingestion, affect and perceived exertion during prolonged cycling.

    PubMed

    Backhouse, Susan H; Biddle, Stuart J H; Bishop, Nicolette C; Williams, Clyde

    2011-08-01

    Caffeine's metabolic and performance effects have been widely reported. However, caffeine's effects on affective states during prolonged exercise are unknown. Therefore, this was examined in the present study. Following an overnight fast and in a randomised, double-blind, counterbalanced design, twelve endurance trained male cyclists performed 90 min of exercise at 70% VO(₂ max) 1h after ingesting 6 mg kg⁻¹ BM of caffeine (CAF) or placebo (PLA). Dimensions of affect and perceived exertion were assessed at regular intervals. During exercise, pleasure ratings were better maintained (F(₃,₃₈)=4.99, P < 0.05) in the CAF trial compared to the PLA trial with significantly higher ratings at 15, 30 and 75 min (all P < 0.05). Perceived exertion increased (F(₃,₃₈) = 19.86, P < 0.01) throughout exercise and values, overall, were significantly lower (F(₁,₁₁) = 9.26, P < 0.05) in the CAF trial compared to the PLA trial. Perceived arousal was elevated during exercise but did not differ between trials. Overall, the results suggest that a moderate dose of CAF ingested 1h prior to exercise maintains a more positive subjective experience during prolonged cycling. This observation may partially explain caffeine's ergogenic effects.

  11. National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses

    PubMed Central

    Casa, Douglas J.; DeMartini, Julie K.; Bergeron, Michael F.; Csillan, Dave; Eichner, E. Randy; Lopez, Rebecca M.; Ferrara, Michael S.; Miller, Kevin C.; O'Connor, Francis; Sawka, Michael N.; Yeargin, Susan W.

    2015-01-01

    Objective  To present best-practice recommendations for the prevention, recognition, and treatment of exertional heat illnesses (EHIs) and to describe the relevant physiology of thermoregulation. Background  Certified athletic trainers recognize and treat athletes with EHIs, often in high-risk environments. Although the proper recognition and successful treatment strategies are well documented, EHIs continue to plague athletes, and exertional heat stroke remains one of the leading causes of sudden death during sport. The recommendations presented in this document provide athletic trainers and allied health providers with an integrated scientific and clinically applicable approach to the prevention, recognition, treatment of, and return-to-activity guidelines for EHIs. These recommendations are given so that proper recognition and treatment can be accomplished in order to maximize the safety and performance of athletes. Recommendations  Athletic trainers and other allied health care professionals should use these recommendations to establish onsite emergency action plans for their venues and athletes. The primary goal of athlete safety is addressed through the appropriate prevention strategies, proper recognition tactics, and effective treatment plans for EHIs. Athletic trainers and other allied health care professionals must be properly educated and prepared to respond in an expedient manner to alleviate symptoms and minimize the morbidity and mortality associated with these illnesses. PMID:26381473

  12. Designing pressure garments capable of exerting specific pressures on limbs.

    PubMed

    Macintyre, Lisa

    2007-08-01

    Pressure garments have been used prophylactically and to treat hypertrophic scars, resulting from serious burns, since the early 1970s. They are custom-made from elastic fabrics by commercial producers and hospital staff. However, no clear scientifically established method has ever been published for their design and manufacture. Previous work [2] identified the most commonly used fabrics and construction methods for the production of pressure garments by hospital staff in UK burn units. These methods were evaluated by measuring pressures delivered to both cylinder models and to human limbs using I-scan pressure sensors. A new calibration method was developed for the I-scan system to enable measurement of low interface pressures to an accuracy of +/-2.5 mmHg. The effects of cylinder/limb circumference and pressure garment design on the pressures exerted were established. These measurements confirm the limitations of current pressure garment construction methods used in UK hospitals. A new method for designing pressure garments that will exert specific known pressures is proposed and evaluated for human thighs. Evaluation of the proposed design method is ongoing for other body parts.

  13. Development of the color scale of perceived exertion: preliminary validation.

    PubMed

    Serafim, Thais H S; Tognato, Andrea C; Nakamura, Priscila M; Queiroga, Marcos R; Nakamura, Fábio Y; Pereira, Gleber; Kokubun, Eduardo

    2014-12-01

    This study developed a Color Scale of Perceived Exertion (RPE-color scale) and assessed its concurrent and construct validity in adult women. One hundred participants (18-77 years), who were habitual exercisers, associated colors with verbal anchors of the Borg RPE scale (RPE-Borg scale) for RPE-color scale development. For RPE-color scale validation, 12 Young (M = 21.7 yr., SD = 1.5) and 10 Older (M = 60.3 yr., SD = 3.5) adult women performed a maximal graded exercise test on a treadmill and reported perceived exertion in both RPE-color and RPE-Borg scales. In the Young group, the RPE-color scale was significantly associated with heart rate and oxygen consumption, having strong correlations with the RPE-Borg scale. In the Older group, the RPE-color scale was significantly associated with heart rate, having moderate to high correlations with the RPE-Borg scale. The RPE-color scale demonstrated concurrent and construct validity in the Young women, as well as construct validity in Older adults.

  14. Neutrophil Extracellular Traps Go Viral

    PubMed Central

    Schönrich, Günther; Raftery, Martin J.

    2016-01-01

    Neutrophils are the most numerous immune cells. Their importance as the first line of defense against bacterial and fungal pathogens is well described. In contrast, the role of neutrophils in controlling viral infections is less clear. Bacterial and fungal pathogens can stimulate neutrophils extracellular traps (NETs) in a process called NETosis. Although NETosis has previously been described as a special form of programmed cell death, there are forms of NET production that do not end with the demise of neutrophils. As an end result of NETosis, genomic DNA complexed with microbicidal proteins is expelled from neutrophils. These structures can kill pathogens or at least prevent their local spread within host tissue. On the other hand, disproportionate NET formation can cause local or systemic damage. Only recently, it was recognized that viruses can also induce NETosis. In this review, we discuss the mechanisms by which NETs are produced in the context of viral infection and how this may contribute to both antiviral immunity and immunopathology. Finally, we shed light on viral immune evasion mechanisms targeting NETs. PMID:27698656

  15. Extracellular Matrix and Liver Disease

    PubMed Central

    Arriazu, Elena; Ruiz de Galarreta, Marina; Cubero, Francisco Javier; Varela-Rey, Marta; Pérez de Obanos, María Pilar; Leung, Tung Ming; Lopategi, Aritz; Benedicto, Aitor; Abraham-Enachescu, Ioana

    2014-01-01

    Abstract Significance: The extracellular matrix (ECM) is a dynamic microenvironment that undergoes continuous remodeling, particularly during injury and wound healing. Chronic liver injury of many different etiologies such as viral hepatitis, alcohol abuse, drug-induced liver injury, obesity and insulin resistance, metabolic disorders, and autoimmune disease is characterized by excessive deposition of ECM proteins in response to persistent liver damage. Critical Issues: This review describes the main collagenous and noncollagenous components from the ECM that play a significant role in pathological matrix deposition during liver disease. We define how increased myofibroblasts (MF) from different origins are at the forefront of liver fibrosis and how liver cell-specific regulation of the complex scarring process occurs. Recent Advances: Particular attention is paid to the role of cytokines, growth factors, reactive oxygen species, and newly identified matricellular proteins in the regulation of fibrillar type I collagen, a field to which our laboratory has significantly contributed over the years. We compile data from recent literature on the potential mechanisms driving fibrosis resolution such as MF’ apoptosis, senescence, and reversal to quiescence. Future Directions: We conclude with a brief description of how epigenetics, an evolving field, can regulate the behavior of MF and of how new “omics” tools may advance our understanding of the mechanisms by which the fibrogenic response to liver injury occurs. Antioxid. Redox Signal. 21, 1078–1097. PMID:24219114

  16. Extracellular Control of Limb Regeneration

    NASA Astrophysics Data System (ADS)

    Calve, S.; Simon, H.-G.

    Adult newts possess the ability to completely regenerate organs and appendages. Immediately after limb loss, the extracellular matrix (ECM) undergoes dramatic changes that may provide mechanical and biochemical cues to guide the formation of the blastema, which is comprised of uncommitted stem-like cells that proliferate to replace the lost structure. Skeletal muscle is a known reservoir for blastema cells but the mechanism by which it contributes progenitor cells is still unclear. To create physiologically relevant culture conditions for the testing of primary newt muscle cells in vitro, the spatio-temporal distribution of ECM components and the mechanical properties of newt muscle were analyzed. Tenascin-C and hyaluronic acid (HA) were found to be dramatically upregulated in the amputated limb and were co-expressed around regenerating skeletal muscle. The transverse stiffness of muscle measured in situ was used as a guide to generate silicone-based substrates of physiological stiffness. Culturing newt muscle cells under different conditions revealed that the cells are sensitive to both matrix coating and substrate stiffness: Myoblasts on HA-coated soft substrates display a rounded morphology and become more elongated as the stiffness of the substrate increases. Coating of soft substrates with matrigel or fibronectin enhanced cell spreading and eventual cell fusion.

  17. Extracellular vesicles in parasitic diseases

    PubMed Central

    Marcilla, Antonio; Martin-Jaular, Lorena; Trelis, Maria; de Menezes-Neto, Armando; Osuna, Antonio; Bernal, Dolores; Fernandez-Becerra, Carmen; Almeida, Igor C.; del Portillo, Hernando A.

    2014-01-01

    Parasitic diseases affect billions of people and are considered a major public health issue. Close to 400 species are estimated to parasitize humans, of which around 90 are responsible for great clinical burden and mortality rates. Unfortunately, they are largely neglected as they are mainly endemic to poor regions. Of relevance to this review, there is accumulating evidence of the release of extracellular vesicles (EVs) in parasitic diseases, acting both in parasite–parasite inter-communication as well as in parasite–host interactions. EVs participate in the dissemination of the pathogen and play a role in the regulation of the host immune systems. Production of EVs from parasites or parasitized cells has been described for a number of parasitic infections. In this review, we provide the most relevant findings of the involvement of EVs in intercellular communication, modulation of immune responses, involvement in pathology, and their potential as new diagnostic tools and therapeutic agents in some of the major human parasitic pathogens. PMID:25536932

  18. Nighttime dissolution in a temperate coastal ocean ecosystem increases under acidification.

    PubMed

    Kwiatkowski, Lester; Gaylord, Brian; Hill, Tessa; Hosfelt, Jessica; Kroeker, Kristy J; Nebuchina, Yana; Ninokawa, Aaron; Russell, Ann D; Rivest, Emily B; Sesboüé, Marine; Caldeira, Ken

    2016-03-18

    Anthropogenic emissions of carbon dioxide (CO2) are causing ocean acidification, lowering seawater aragonite (CaCO3) saturation state (Ω arag), with potentially substantial impacts on marine ecosystems over the 21(st) Century. Calcifying organisms have exhibited reduced calcification under lower saturation state conditions in aquaria. However, the in situ sensitivity of calcifying ecosystems to future ocean acidification remains unknown. Here we assess the community level sensitivity of calcification to local CO2-induced acidification caused by natural respiration in an unperturbed, biodiverse, temperate intertidal ecosystem. We find that on hourly timescales nighttime community calcification is strongly influenced by Ω arag, with greater net calcium carbonate dissolution under more acidic conditions. Daytime calcification however, is not detectably affected by Ω arag. If the short-term sensitivity of community calcification to Ω arag is representative of the long-term sensitivity to ocean acidification, nighttime dissolution in these intertidal ecosystems could more than double by 2050, with significant ecological and economic consequences.

  19. Ocean Acidification: A Major Driver of Coral Bleaching in the 21st Century?

    NASA Astrophysics Data System (ADS)

    Anthony, K.; Eakin, M. C.; Cao, L.; Caldeira, K.; Hoegh-Guldberg, O.

    2009-05-01

    Heat stress long been known to drive patterns of coral bleaching. Recently, however, it was discovered that ocean acidification can drive coral bleaching independently of temperature. This raises the question: how important will acidification be in driving coral bleaching under climate change? Here, we develop and apply a model that accounts for both thermal stress and ocean acidification in the coral bleaching response. Our analyses, which combine experimental bleaching data under manipulated ocean chemistry and warming with projections of CO2 and SST based on global circulation models, show that ocean acidification will become a key driver of future mass bleaching events within a few decades. Our findings, based on highly conservative assumptions, reveal that coral bleaching alert systems based on warming alone could underestimate coral bleaching by up to 50% during the 21st century. This is a striking result that will affect coral reef management strategies worldwide and has policy implications relating to global efforts to reduce greenhouse gas emissions.

  20. A Demonstration of Acid Rain and Lake Acidification: Wet Deposition of Sulfur Dioxide.

    ERIC Educational Resources Information Center

    Goss, Lisa M.

    2003-01-01

    Introduces a science demonstration on the dissolution of sulfuric oxide emphasizing the concept of acid rain which is an environmental problem. Demonstrates the acidification from acid rain on two lake environments, limestone and granite. Includes safety information. (YDS)

  1. The peculiarities of water acidification in European Russia and Western Siberia

    NASA Astrophysics Data System (ADS)

    Moiseenko, T. I.; Gashkina, N. A.; Dinu, M. I.; Kremleva, T. A.

    2015-06-01

    Studies have proven the anthropogenic acidification of waters developing over the spacious territories of European Russia and West Siberia. The acidification is exhibited by the waters of small lakes characterized by bedrock consisting of granite and quartz formations. The acidified lakes of high water transparency, pH values below 6, and the prevalence of strong acids in the anion composition account for 4.4% of 201 lakes of European Russia and 8.2% of 166 explored lakes in the taiga and tundra regions of western Siberia. The main factor causing the development of acidification over the European Russia is the emission of technogenic sulfur by metallurgical smelteries. As for western Siberia, this is the combustion of associated gas at oil-producing enterprises. These processes combined with natural factors determine the complicated mechanism of anthropogenic acidification of waters.

  2. EPA Issues November 15, 2010 Memorandum: Integrated Reporting and Listing Decisions Related to Ocean Acidification

    EPA Pesticide Factsheets

    The memorandum provides information to assist regions and states in preparing and reviewing Integrated Reports related to ocean acidification (OA) impacts under Sections 303(d), 305(b) and 314 of the Clean Water Act (CWA).

  3. Ocean acidification and temperature increase impact mussel shell shape and thickness: problematic for protection?

    PubMed

    Fitzer, Susan C; Vittert, Liberty; Bowman, Adrian; Kamenos, Nicholas A; Phoenix, Vernon R; Cusack, Maggie

    2015-11-01

    Ocean acidification threatens organisms that produce calcium carbonate shells by potentially generating an under-saturated carbonate environment. Resultant reduced calcification and growth, and subsequent dissolution of exoskeletons, would raise concerns over the ability of the shell to provide protection for the marine organism under ocean acidification and increased temperatures. We examined the impact of combined ocean acidification and temperature increase on shell formation of the economically important edible mussel Mytilus edulis. Shell growth and thickness along with a shell thickness index and shape analysis were determined. The ability of M. edulis to produce a functional protective shell after 9 months of experimental culture under ocean acidification and increasing temperatures (380, 550, 750, 1000 μatm pCO 2, and 750, 1000 μatm pCO 2 + 2°C) was assessed. Mussel shells grown under ocean acidification conditions displayed significant reductions in shell aragonite thickness, shell thickness index, and changes to shell shape (750, 1000 μatm pCO 2) compared to those shells grown under ambient conditions (380 μatm pCO 2). Ocean acidification resulted in rounder, flatter mussel shells with thinner aragonite layers likely to be more vulnerable to fracture under changing environments and predation. The changes in shape presented here could present a compensatory mechanism to enhance protection against predators and changing environments under ocean acidification when mussels are unable to grow thicker shells. Here, we present the first assessment of mussel shell shape to determine implications for functional protection under ocean acidification.

  4. Economic Vulnerability Assessment of U.S. Fishery Revenues to Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Cooley, S. R.; Doney, S. C.

    2008-12-01

    Ocean acidification, a predictable consequence of rising anthropogenic CO2 emissions, is poised to change marine ecosystems profoundly by decreasing average ocean pH and the carbonate mineral saturation state worldwide. These conditions slow or reverse marine plant and animal calcium carbonate shell growth, thereby harming economically valuable species. In 2006, shellfish and crustaceans provided 50% of the 4 billion U.S. domestic commercial harvest value; value added to commercial fishery products contributed 35 billion to the gross national product that year. Laboratory studies have shown that ocean acidification decreases shellfish calcification; ocean acidification--driven declines in commercial shellfish and crustacean harvests between now and 2060 could decrease nationwide time-integrated primary commercial revenues by 860 million to 14 billion (net present value, 2006 dollars), depending on CO2 emissions, discount rates, biological responses, and fishery structure. This estimate excludes losses from coral reef damage and possible fishery collapses if ocean acidification pushes ecosystems past ecological tipping points. Expanding job losses and indirect economic costs will follow harvest decreases as ocean acidification broadly damages marine habitats and alters marine resource availability. Losses will harm many regions already possessing little economic resilience. The only true solution to ocean acidification is reducing atmospheric CO2 emissions, but implementing regional adaptive responses now from an ecosystem-wide, fisheries perspective will help better preserve sustainable ecosystem function and economic yields. Comprehensive management strategies must include monitoring critical fisheries, explicitly accounting for ocean acidification in management models, reducing fishing pressure and environmental stresses, and supporting regional economies most sensitive to acidification's impacts.

  5. Extracellular vesicles in coronary artery disease.

    PubMed

    Boulanger, Chantal M; Loyer, Xavier; Rautou, Pierre-Emmanuel; Amabile, Nicolas

    2017-02-02

    Membrane vesicles released in the extracellular space are composed of a lipid bilayer enclosing soluble cytosolic material and nuclear components. Extracellular vesicles include apoptotic bodies, exosomes, and microvesicles (also known previously as microparticles). Originating from different subcellular compartments, the role of extracellular vesicles as regulators of transfer of biological information, acting locally and remotely, is now acknowledged. Circulating vesicles released from platelets, erythrocytes, leukocytes, and endothelial cells contain potential valuable biological information for biomarker discovery in primary and secondary prevention of coronary artery disease. Extracellular vesicles also accumulate in human atherosclerotic plaques, where they affect major biological pathways, including inflammation, proliferation, thrombosis, calcification, and vasoactive responses. Extracellular vesicles also recapitulate the beneficial effect of stem cells to treat cardiac consequences of acute myocardial infarction, and now emerge as an attractive alternative to cell therapy, opening new avenues to vectorize biological information to target tissues. Although interest in microvesicles in the cardiovascular field emerged about 2 decades ago, that for extracellular vesicles, in particular exosomes, started to unfold a decade ago, opening new research and therapeutic avenues. This Review summarizes current knowledge on the role of extracellular vesicles in coronary artery disease, and their emerging potential as biomarkers and therapeutic agents.

  6. Optimum polygenic profile to resist exertional rhabdomyolysis during a marathon

    PubMed Central

    Valero, Marjorie; Salinero, Juan José; Lara, Beatriz; Gallo-Salazar, César; Areces, Francisco

    2017-01-01

    Purpose Exertional rhabdomyolysis can occur in individuals performing various types of exercise but it is unclear why some individuals develop this condition while others do not. Previous investigations have determined the role of several single nucleotide polymorphisms (SNPs) to explain inter-individual variability of serum creatine kinase (CK) concentrations after exertional muscle damage. However, there has been no research about the interrelationship among these SNPs. The purpose of this investigation was to analyze seven SNPs that are candidates for explaining individual variations of CK response after a marathon competition (ACE = 287bp Ins/Del, ACTN3 = p.R577X, CKMM = NcoI, IGF2 = C13790G, IL6 = 174G>C, MLCK = C37885A, TNFα = 308G>A). Methods Using Williams and Folland’s model, we determined the total genotype score from the accumulated combination of these seven SNPs for marathoners with a low CK response (n = 36; serum CK <400 U·L-1) vs. marathoners with a high CK response (n = 31; serum CK ≥400 U·L-1). Results At the end of the race, low CK responders had lower serum CK (290±65 vs. 733±405 U·L-1; P<0.01) and myoglobin concentrations (443±328 vs. 1009±971 ng·mL-1, P<0.01) than high CK responders. Although the groups were similar in age, anthropometric characteristics, running experience and training habits, total genotype score was higher in low CK responders than in high CK responders (5.2±1.4 vs. 4.4±1.7 point, P = 0.02). Conclusion Marathoners with a lower CK response after the race had a more favorable polygenic profile than runners with high serum CK concentrations. This might suggest a significant role of genetic polymorphisms in the levels of exertional muscle damage and rhabdomyolysis. Yet other SNPs, in addition to exercise training, might also play a role in the values of CK after damaging exercise. PMID:28257486

  7. Proteomics of extracellular vesicles: Exosomes and ectosomes.

    PubMed

    Choi, Dong-Sic; Kim, Dae-Kyum; Kim, Yoon-Keun; Gho, Yong Song

    2015-01-01

    Almost all bacteria, archaea, and eukaryotic cells shed extracellular vesicles either constitutively or in a regulated manner. These nanosized membrane vesicles are spherical, bilayered proteolipids that harbor specific subsets of proteins, DNAs, RNAs, and lipids. Recent research has facilitated conceptual advancements in this emerging field that indicate that extracellular vesicles act as intercellular communicasomes by transferring signals to their target cell via surface ligands and delivering receptors and functional molecules. Recent progress in mass spectrometry-based proteomic analyses of mammalian extracellular vesicles derived from diverse cell types and body fluids has resulted in the identification of several thousand vesicular proteins that provide us with essential clues to the molecular mechanisms involved in vesicle cargo sorting and biogenesis. Furthermore, cell-type- or disease-specific vesicular proteins help us to understand the pathophysiological functions of extracellular vesicles and contribute to the discovery of diagnostic and therapeutic target proteins. This review focuses on the high-throughput mass spectrometry-based proteomic analyses of mammalian extracellular vesicles (i.e., exosomes and ectosomes), EVpedia (a free web-based integrated database of high-throughput data for systematic analyses of extracellular vesicles; http://evpedia.info), and the intravesicular protein-protein interaction network analyses of mammalian extracellular vesicles. The goal of this article is to encourage further studies to construct a comprehensive proteome database for extracellular vesicles that will help us to not only decode the biogenesis and cargo-sorting mechanisms during vesicle formation but also elucidate the pathophysiological roles of these complex extracellular organelles.

  8. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming

    PubMed Central

    Kroeker, Kristy J; Kordas, Rebecca L; Crim, Ryan; Hendriks, Iris E; Ramajo, Laura; Singh, Gerald S; Duarte, Carlos M; Gattuso, Jean-Pierre

    2013-01-01

    Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms' responses and corresponding levels of certainty is necessary to forecast the ecological effects. Here, we perform the most comprehensive meta-analysis to date by synthesizing the results of 228 studies examining biological responses to ocean acidification. The results reveal decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups, suggesting there is some predictable trait-based variation in sensitivity, despite the investigation of approximately 100 new species in recent research. The results also reveal an enhanced sensitivity of mollusk larvae, but suggest that an enhanced sensitivity of early life history stages is not universal across all taxonomic groups. In addition, the variability in species' responses is enhanced when they are exposed to acidification in multi-species assemblages, suggesting that it is important to consider indirect effects and exercise caution when forecasting abundance patterns from single-species laboratory experiments. Furthermore, the results suggest that other factors, such as nutritional status or source population, could cause substantial variation in organisms' responses. Last, the results highlight a trend towards enhanced sensitivity to acidification when taxa are concurrently exposed to elevated seawater temperature. PMID:23505245

  9. Consumers mediate the effects of experimental ocean acidification and warming on primary producers

    PubMed Central

    Alsterberg, Christian; Eklöf, Johan S.; Gamfeldt, Lars; Havenhand, Jonathan N.; Sundbäck, Kristina

    2013-01-01

    It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e.g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities. PMID:23630263

  10. Ocean acidification: Linking science to management solutions using the Great Barrier Reef as a case study.

    PubMed

    Albright, Rebecca; Anthony, Kenneth R N; Baird, Mark; Beeden, Roger; Byrne, Maria; Collier, Catherine; Dove, Sophie; Fabricius, Katharina; Hoegh-Guldberg, Ove; Kelly, Ryan P; Lough, Janice; Mongin, Mathieu; Munday, Philip L; Pears, Rachel J; Russell, Bayden D; Tilbrook, Bronte; Abal, Eva

    2016-11-01

    Coral reefs are one of the most vulnerable ecosystems to ocean acidification. While our understanding of the potential impacts of ocean acidification on coral reef ecosystems is growing, gaps remain that limit our ability to translate scientific knowledge into management action. To guide solution-based research, we review the current knowledge of ocean acidification impacts on coral reefs alongside management needs and priorities. We use the world's largest continuous reef system, Australia's Great Barrier Reef (GBR), as a case study. We integrate scientific knowledge gained from a variety of approaches (e.g., laboratory studies, field observations, and ecosystem modelling) and scales (e.g., cell, organism, ecosystem) that underpin a systems-level understanding of how ocean acidification is likely to impact the GBR and associated goods and services. We then discuss local and regional management options that may be effective to help mitigate the effects of ocean acidification on the GBR, with likely application to other coral reef systems. We develop a research framework for linking solution-based ocean acidification research to practical management options. The framework assists in identifying effective and cost-efficient options for supporting ecosystem resilience. The framework enables on-the-ground OA management to be the focus, while not losing sight of CO2 mitigation as the ultimate solution.

  11. Taking action against ocean acidification: a review of management and policy options.

    PubMed

    Billé, Raphaël; Kelly, Ryan; Biastoch, Arne; Harrould-Kolieb, Ellycia; Herr, Dorothée; Joos, Fortunat; Kroeker, Kristy; Laffoley, Dan; Oschlies, Andreas; Gattuso, Jean-Pierre

    2013-10-01

    Ocean acidification has emerged over the last two decades as one of the largest threats to marine organisms and ecosystems. However, most research efforts on ocean acidification have so far neglected management and related policy issues to focus instead on understanding its ecological and biogeochemical implications. This shortfall is addressed here with a systematic, international and critical review of management and policy options. In particular, we investigate the assumption that fighting acidification is mainly, but not only, about reducing CO2 emissions, and explore the leeway that this emerging problem may open in old environmental issues. We review nine types of management responses, initially grouped under four categories: preventing ocean acidification; strengthening ecosystem resilience; adapting human activities; and repairing damages. Connecting and comparing options leads to classifying them, in a qualitative way, according to their potential and feasibility. While reducing CO2 emissions is confirmed as the key action that must be taken against acidification, some of the other options appear to have the potential to buy time, e.g. by relieving the pressure of other stressors, and help marine life face unavoidable acidification. Although the existing legal basis to take action shows few gaps, policy challenges are significant: tackling them will mean succeeding in various areas of environmental management where we failed to a large extent so far.

  12. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming.

    PubMed

    Kroeker, Kristy J; Kordas, Rebecca L; Crim, Ryan; Hendriks, Iris E; Ramajo, Laura; Singh, Gerald S; Duarte, Carlos M; Gattuso, Jean-Pierre

    2013-06-01

    Ocean acidification represents a threat to marine species worldwide, and forecasting the ecological impacts of acidification is a high priority for science, management, and policy. As research on the topic expands at an exponential rate, a comprehensive understanding of the variability in organisms' responses and corresponding levels of certainty is necessary to forecast the ecological effects. Here, we perform the most comprehensive meta-analysis to date by synthesizing the results of 228 studies examining biological responses to ocean acidification. The results reveal decreased survival, calcification, growth, development and abundance in response to acidification when the broad range of marine organisms is pooled together. However, the magnitude of these responses varies among taxonomic groups, suggesting there is some predictable trait-based variation in sensitivity, despite the investigation of approximately 100 new species in recent research. The results also reveal an enhanced sensitivity of mollusk larvae, but suggest that an enhanced sensitivity of early life history stages is not universal across all taxonomic groups. In addition, the variability in species' responses is enhanced when they are exposed to acidification in multi-species assemblages, suggesting that it is important to consider indirect effects and exercise caution when forecasting abundance patterns from single-species laboratory experiments. Furthermore, the results suggest that other factors, such as nutritional status or source population, could cause substantial variation in organisms' responses. Last, the results highlight a trend towards enhanced sensitivity to acidification when taxa are concurrently exposed to elevated seawater temperature.

  13. Consumers mediate the effects of experimental ocean acidification and warming on primary producers.

    PubMed

    Alsterberg, Christian; Eklöf, Johan S; Gamfeldt, Lars; Havenhand, Jonathan N; Sundbäck, Kristina

    2013-05-21

    It is well known that ocean acidification can have profound impacts on marine organisms. However, we know little about the direct and indirect effects of ocean acidification and also how these effects interact with other features of environmental change such as warming and declining consumer pressure. In this study, we tested whether the presence of consumers (invertebrate mesograzers) influenced the interactive effects of ocean acidification and warming on benthic microalgae in a seagrass community mesocosm experiment. Net effects of acidification and warming on benthic microalgal biomass and production, as assessed by analysis of variance, were relatively weak regardless of grazer presence. However, partitioning these net effects into direct and indirect effects using structural equation modeling revealed several strong relationships. In the absence of grazers, benthic microalgae were negatively and indirectly affected by sediment-associated microalgal grazers and macroalgal shading, but directly and positively affected by acidification and warming. Combining indirect and direct effects yielded no or weak net effects. In the presence of grazers, almost all direct and indirect climate effects were nonsignificant. Our analyses highlight that (i) indirect effects of climate change may be at least as strong as direct effects, (ii) grazers are crucial in mediating these effects, and (iii) effects of ocean acidification may be apparent only through indirect effects and in combination with other variables (e.g., warming). These findings highlight the importance of experimental designs and statistical analyses that allow us to separate and quantify the direct and indirect effects of multiple climate variables on natural communities.

  14. Extracellular control of intracellular drug release for enhanced safety of anti-cancer chemotherapy

    NASA Astrophysics Data System (ADS)

    Zhu, Qian; Qi, Haixia; Long, Ziyan; Liu, Shang; Huang, Zhen; Zhang, Junfeng; Wang, Chunming; Dong, Lei

    2016-06-01

    The difficulty of controlling drug release at an intracellular level remains a key challenge for maximising drug safety and efficacy. We demonstrate herein a new, efficient and convenient approach to extracellularly control the intracellular release of doxorubicin (DOX), by designing a delivery system that harnesses the interactions between the system and a particular set of cellular machinery. By simply adding a small-molecule chemical into the cell medium, we could lower the release rate of DOX in the cytosol, and thereby increase its accumulation in the nuclei while decreasing its presence at mitochondria. Delivery of DOX with this system effectively prevented DOX-induced mitochondria damage that is the main mechanism of its toxicity, while exerting the maximum efficacy of this anti-cancer chemotherapeutic agent. The present study sheds light on the design of drug delivery systems for extracellular control of intracellular drug delivery, with immediate therapeutic implications.

  15. Acidification of the Mediterranean Sea during the 21st century

    NASA Astrophysics Data System (ADS)

    Le Vu, Briac; Palmieri, Julien; Orr, James C.; Dutay, Jean Claude; Sevault, Florence

    2014-05-01

    We modeled the carbon cycle in the Mediterranean Sea to study how its changes due to climate change and rising levels of atmospheric CO2 may differ from those typical of the global ocean. More specifically, we coupled offline an ocean biogeochemical model (PISCES) to a regional eddy-permitting model of the Mediterranean Sea (NEMO-MED8, 1/8° nominal horizonal resolution) using forcing from coupled regional climate model simulations of which the ocean circulation component was identical. Here we describe the simulated changes in pH and the associated carbonate system during the 21st century. Separate simulations were made with climate forcing for a hindcast (1965-2008) and for the future (2000-2100). For the former, climate and CO2 forcings were based on observations; for the latter, both climate and CO2 were driven by the IPCC SRES-A2 scenario. Our hindcast simulation over the period 1965-2008 allowed us to evaluate the model and assess recent variability of the carbonate system. In our future simulation, we used separate tracers to distinguish (1) the change due to climate change and the increase in atmospheric CO2 (from 370 to 800 ppm) and (2) the change due only to climate change (holding atmospheric CO2 to the year-2000 level of 370 ppm). By difference, we isolated the geochemical effect (anthropogenic CO2 perturbation). The hindcast simulation demonstrates that the model captures the amplitude and phase of the annual cycle of temperature, pCO2 and pH, in agreement with data from the DYFAMED station. That seasonal variability of surface pCO2 is everywhere driven by variations in temperature. These results lends support that the model is able to quantify the acidification of the Mediterranean Sea during the industrial period and for the future. However, they do not constrain the model's simulated effects of future climate change on ocean circulation and ocean biology, both of which in turn influence the carbon cycle. Similar to estimates for the global ocean

  16. Mitogenic properties of major extracellular proteins.

    PubMed

    Lévesque, J P; Hatzfeld, A; Hatzfeld, J

    1991-08-01

    The major plasma and extracellular matrix proteins are multifunctional molecules. Some, such as fibrinogen or C3, have one domain that binds adhesion receptors and another that specifically binds and activates a separate, mitogenic receptor. In this review, Jean-Pierre Lévesque, Antoinette Hatzfeld and Jacques Hatzfeld describe adhesion and mitogenic receptors that bind to distinct domains of the same extracellular matrix protein and discuss the possibility of common ancestral genes for cell adhesion molecules, extracellular matrix proteins, integrins, immunoglobulins, growth factors and their receptors.

  17. Exertional rhabdomyolysis and heat stroke: Beware of volatile anesthetic sedation

    PubMed Central

    Heytens, Karel; De Bleecker, Jan; Verbrugghe, Walter; Baets, Jonathan; Heytens, Luc

    2017-01-01

    In view of the enormous popularity of mass sporting events such as half-marathons, the number of patients with exertional rhabdomyolysis or exercise-induced heat stroke admitted to intensive care units (ICUs) has increased over the last decade. Because these patients have been reported to be at risk for malignant hyperthermia during general anesthesia, the intensive care community should bear in mind that the same risk of life-threatening rhabdomyolysis is present when these patients are admitted to an ICU, and volatile anesthetic sedation is chosen as the sedative technique. As illustrated by the three case studies we elaborate upon, a thorough diagnostic work-up is needed to clarify the subsequent risk of strenuous exercise, and the anesthetic exposure to volatile agents in these patients and their families. Other contraindications for the use of volatile intensive care sedation consist of known malignant hyperthermia susceptibility, congenital myopathies, Duchenne muscular dystrophy, and intracranial hypertension. PMID:28224104

  18. Reflections on the Institute of Medicine's systemic exertion intolerance disease.

    PubMed

    Jason, Leonard A; Sunnquist, Madison; Brown, Abigail; McManimen, Stephanie; Furst, Jacob

    2015-01-01

    The Institute of Medicine (IOM) in the United States has recently proposed that the term systemic exertion intolerance disease (SEID) replace chronic fatigue syndrome. In addition, the IOM proposed a new case definition for SEID, which includes substantial reductions or impairments in the ability to engage in pre‑illness activities, unrefreshing sleep, postexertional malaise, and either cognitive impairment or orthostatic intolerance. Unfortunately, these recommendations for a name change were not vetted with patient and professional audiences, and the new criteria were not evaluated with data sets of patients and controls. A recent poll suggests that the majority of patients reject this new name. In addition, studies have found that prevalence rates will dramatically increase with the new criteria, particularly due to the ambiguity revolving around exclusionary illnesses. Findings suggest that the new criteria select more patients who have less impairment and fewer symptoms than several other criteria. The implications of these findings are discussed in the current review.

  19. Phosphatidic acid formation is required for extracellular ATP-mediated nitric oxide production in suspension-cultured tomato cells.

    PubMed

    Sueldo, Daniela J; Foresi, Noelia P; Casalongué, Claudia A; Lamattina, Lorenzo; Laxalt, Ana M

    2010-03-01

    *In animals and plants, extracellular ATP exerts its effects by regulating the second messengers Ca(2+), nitric oxide (NO) and reactive oxygen species (ROS). In animals, phospholipid-derived molecules, such as diacylglycerol, phosphatidic acid (PA) and inositol phosphates, have been associated with the extracellular ATP signaling pathway. The involvement of phospholipids in extracellular ATP signaling in plants, as it is established in animals, is unknown. *In vivo phospholipid signaling upon extracellular ATP treatment was studied in (32)P(i)-labeled suspension-cultured tomato (Solanum lycopersicum) cells. *Here, we report that, in suspension-cultured tomato cells, extracellular ATP induces the formation of the signaling lipid phosphatidic acid. Exogenous ATP at doses of 0.1 and 1 mM induce the formation of phosphatidic acid within minutes. Studies on the enzymatic sources of phosphatidic acid revealed the participation of both phospholipase D and C in concerted action with diacylglycerol kinase. *Our results suggest that extracellular ATP-mediated nitric oxide production is downstream of phospholipase C/diacylglycerol kinase activation.

  20. Physiological responses and perceived exertion during cycling with superimposed electromyostimulation.

    PubMed

    Wahl, Patrick; Schaerk, Jonas; Achtzehn, Silvia; Kleinöder, Heinz; Bloch, Wilhelm; Mester, Joachim

    2012-09-01

    The goal of the study was to evaluate and to quantify the effects of local electromyostimulation (EMS) during cycling on the cardiorespiratory system, muscle metabolism, and perceived exertion compared with cycling with no EMS. Ten healthy men (age: 24.6 ± 3.2 years, V[Combining Dot Above]O2max: 54.1 ± 6.0 ml·min·kg) performed 3 incremental cycle ergometer step tests, 1 without and 2 with EMS (30 and 85 Hz) until volitional exhaustion. Lactate values and respiratory exchange ratio were significantly higher at intensities ≥75% peak power output (PPO) when EMS was applied. Bicarbonate concentration, base excess (BE), and Pco2 were significantly lower when EMS was applied compared with the control at intensities ≥75% PPO. Saliva cortisol levels increased because of the exercise but were unaffected by EMS. Furthermore, EMS showed greater effects on CK levels 24 hours postexercise than normal cycling did. Rating of perceived exertion was significantly higher at 100% PPO with EMS. No statistical differences were found for heart rate, pH, and Po2 between the tested cycling modes. The main findings of this study are greater metabolic changes (lactate, respiratory exchange ratio, BE, (Equation is included in full-text article.), Pco2) during cycling with EMS compared with normal cycling independent of frequency, mainly visible at higher work rates. Because metabolic alterations are important for the induction of cellular signaling cascades and adaptations, these results lead to the hypothesis that applied EMS stimulations during cycling exercise might be an enhancing stimulus for skeletal muscle metabolism and related adaptations. Thus, superimposed EMS application during cycling could be beneficial to aerobic performance enhancements in athletes and in patients who cannot perform high workloads. However, the higher demand on skeletal muscles involved must be considered.

  1. The use of subjective rating of exertion in Ergonomics.

    PubMed

    Capodaglio, P

    2002-01-01

    In Ergonomics, the use of psychophysical methods for subjectively evaluating work tasks and determining acceptable loads has become more common. Daily activities at the work site are studied not only with physiological methods but also with perceptual estimation and production methods. The psychophysical methods are of special interest in field studies of short-term work tasks for which valid physiological measurements are difficult to obtain. The perceived exertion, difficulty and fatigue that a person experiences in a certain work situation is an important sign of a real or objective load. Measurement of the physical load with physiological parameters is not sufficient since it does not take into consideration the particular difficulty of the performance or the capacity of the individual. It is often difficult from technical and biomechanical analyses to understand the seriousness of a difficulty that a person experiences. Physiological determinations give important information, but they may be insufficient due to the technical problems in obtaining relevant but simple measurements for short-term activities or activities involving special movement patterns. Perceptual estimations using Borg's scales give important information because the severity of a task's difficulty depends on the individual doing the work. Observation is the most simple and used means to assess job demands. Other evaluations integrating observation are the followings: indirect estimation of energy expenditure based on prediction equations or direct measurement of oxygen consumption; measurements of forces, angles and biomechanical parameters; measurements of physiological and neurophysiological parameters during tasks. It is recommended that determinations of performances of occupational activities assess rating of perceived exertion and integrate these measurements of intensity levels with those of activity's type, duration and frequency. A better estimate of the degree of physical activity

  2. Simultaneous Multiple Control Force Exertion Capabilities of Males and Females versus Helicopter Control Force Design Limits,

    DTIC Science & Technology

    1987-09-01

    percent) than for collective inputs ( typically 20-35 percent). Substantial proportions of the subjects (approximately 50 percent of the males and more ...nearly 86 percent of the females performed one or more exertions below the design limit. The exertions of 28.6 percent of the females were below the pedal...design limit for more than one-half of the 16 exertions they performed; 75 percent of the exertions by 6 of the 63 females were below design-limit

  3. Extracellular matrix proteins of dentine.

    PubMed

    Butler, W T; Ritchie, H H; Bronckers, A L

    1997-01-01

    Bone and dentine extracellular matrix proteins are similar, consisting primarily of type I collagen, acidic proteins and proteoglycans. Although collagen forms the lattice for deposition of calcium and phosphate for formation of carbonate apatite, the non-collagenous proteins are believed to control initiation and growth of the crystals. Despite this similarity, dentine contains three unique proteins apparently absent from bone and other tissue: dentine phosphophoryn (DPP), dentine matrix protein 1 (DMP1) and dentine sialoprotein (DSP). DPP and DMP1 are acidic phosphoproteins probably involved in the control of mineralization processes. DPP may localize in gap regions of collagen and initiate apatite crystal formation by binding large quantities of calcium in a conformation that promotes this process. Extensive studies have been conducted in our laboratory on the nature, biosynthesis, localization and gene structure of DSP. Immunolocalization studies showed that rat DSP, a 53 kDa sialic acid-rich glycoprotein, was synthesized by young and mature odontoblasts, and by dental pulp cells and pre-ameloblasts, but not by ameloblasts, osteoblasts, chondrocytes or other cell types. The cDNA sequence indicated that DSP was a 366-residue protein with several potential N-glycosylation sites, as well as phosphorylation sites, but that the amino acid sequence was dissimilar to that of other known proteins. Northern blot analysis detected several mRNA species near 4.6 and 1.5 kb, indicative of alternative splicing events. Evidence for two DSP genes was obtained, further complicating this picture. Recent in situ hybridization studies utilizing rat and mouse molars and incisors indicated that DSP mRNA was expressed by young odontoblasts and odontoblasts in animals of all ages. Transcripts were also observed in pre-ameloblasts. The expression of DSP mRNA ceased when these cells matured to become secretory ameloblasts. DSP transcripts were not detected in osteoblasts or other cell

  4. The extracellular RNA complement of Escherichia coli

    PubMed Central

    Ghosal, Anubrata; Upadhyaya, Bimal Babu; Fritz, Joëlle V; Heintz-Buschart, Anna; Desai, Mahesh S; Yusuf, Dilmurat; Huang, David; Baumuratov, Aidos; Wang, Kai; Galas, David; Wilmes, Paul

    2015-01-01

    The secretion of biomolecules into the extracellular milieu is a common and well-conserved phenomenon in biology. In bacteria, secreted biomolecules are not only involved in intra-species communication but they also play roles in inter-kingdom exchanges and pathogenicity. To date, released products, such as small molecules, DNA, peptides, and proteins, have been well studied in bacteria. However, the bacterial extracellular RNA complement has so far not been comprehensively characterized. Here, we have analyzed, using a combination of physical characterization and high-throughput sequencing, the extracellular RNA complement of both outer membrane vesicle (OMV)-associated and OMV-free RNA of the enteric Gram-negative model bacterium Escherichia coli K-12 substrain MG1655 and have compared it to its intracellular RNA complement. Our results demonstrate that a large part of the extracellular RNA complement is in the size range between 15 and 40 nucleotides and is derived from specific intracellular RNAs. Furthermore, RNA is associated with OMVs and the relative abundances of RNA biotypes in the intracellular, OMV and OMV-free fractions are distinct. Apart from rRNA fragments, a significant portion of the extracellular RNA complement is composed of specific cleavage products of functionally important structural noncoding RNAs, including tRNAs, 4.5S RNA, 6S RNA, and tmRNA. In addition, the extracellular RNA pool includes RNA biotypes from cryptic prophages, intergenic, and coding regions, of which some are so far uncharacterised, for example, transcripts mapping to the fimA-fimL and ves-spy intergenic regions. Our study provides the first detailed characterization of the extracellular RNA complement of the enteric model bacterium E. coli. Analogous to findings in eukaryotes, our results suggest the selective export of specific RNA biotypes by E. coli, which in turn indicates a potential role for extracellular bacterial RNAs in intercellular communication. PMID:25611733

  5. Securin and separase modulate membrane traffic by affecting endosomal acidification.

    PubMed

    Bacac, Marina; Fusco, Carlo; Planche, Anne; Santodomingo, Jaime; Demaurex, Nicolas; Leemann-Zakaryan, Ruzanna; Provero, Paolo; Stamenkovic, Ivan

    2011-05-01

    Securin and separase play a key role in sister chromatid separation during anaphase. However, a growing body of evidence suggests that in addition to regulating chromosome segregation, securin and separase display functions implicated in membrane traffic in Caenorhabditis elegans and Drosophila. Here we show that in mammalian cells both securin and separase associate with membranes and that depletion of either protein causes robust swelling of the trans-Golgi network (TGN) along with the appearance of large endocytic vesicles in the perinuclear region. These changes are accompanied by diminished constitutive protein secretion as well as impaired receptor recycling and degradation. Unexpectedly, cells depleted of securin or separase display defective acidification of early endosomes and increased membrane recruitment of vacuolar (V-) ATPase complexes, mimicking the effect of the specific V-ATPase inhibitor Bafilomycin A1. Taken together, our findings identify a new functional role of securin and separase in the modulation of membrane traffic and protein secretion that implicates regulation of V-ATPase assembly and function.

  6. Ocean acidification alters the material properties of Mytilus edulis shells

    PubMed Central

    Fitzer, Susan C.; Zhu, Wenzhong; Tanner, K. Elizabeth; Phoenix, Vernon R.; Kamenos, Nicholas A.; Cusack, Maggie

    2015-01-01

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature. PMID:25540244

  7. Ocean acidification increases fatty acids levels of larval fish.

    PubMed

    Díaz-Gil, Carlos; Catalán, Ignacio A; Palmer, Miquel; Faulk, Cynthia K; Fuiman, Lee A

    2015-07-01

    Rising levels of anthropogenic carbon dioxide in the atmosphere are acidifying the oceans and producing diverse and important effects on marine ecosystems, including the production of fatty acids (FAs) by primary producers and their transfer through food webs. FAs, particularly essential FAs, are necessary for normal structure and function in animals and influence composition and trophic structure of marine food webs. To test the effect of ocean acidification (OA) on the FA composition of fish, we conducted a replicated experiment in which larvae of the marine fish red drum (Sciaenops ocellatus) were reared under a climate change scenario of elevated CO2 levels (2100 µatm) and under current control levels (400 µatm). We found significantly higher whole-body levels of FAs, including nine of the 11 essential FAs, and altered relative proportions of FAs in the larvae reared under higher levels of CO2. Consequences of this effect of OA could include alterations in performance and survival of fish larvae and transfer of FAs through food webs.

  8. Ocean acidification increases fatty acids levels of larval fish

    PubMed Central

    Díaz-Gil, Carlos; Catalán, Ignacio A.; Palmer, Miquel; Faulk, Cynthia K.; Fuiman, Lee A.

    2015-01-01

    Rising levels of anthropogenic carbon dioxide in the atmosphere are acidifying the oceans and producing diverse and important effects on marine ecosystems, including the production of fatty acids (FAs) by primary producers and their transfer through food webs. FAs, particularly essential FAs, are necessary for normal structure and function in animals and influence composition and trophic structure of marine food webs. To test the effect of ocean acidification (OA) on the FA composition of fish, we conducted a replicated experiment in which larvae of the marine fish red drum (Sciaenops ocellatus) were reared under a climate change scenario of elevated CO2 levels (2100 µatm) and under current control levels (400 µatm). We found significantly higher whole-body levels of FAs, including nine of the 11 essential FAs, and altered relative proportions of FAs in the larvae reared under higher levels of CO2. Consequences of this effect of OA could include alterations in performance and survival of fish larvae and transfer of FAs through food webs. PMID:26179801

  9. Modeling future acidification and fish populations in Norwegian surface waters.

    PubMed

    Larssen, Thorjørn; Cosby, Bernard J; Lund, Espen; Wright, Richard F

    2010-07-15

    Despite great progress made in the past 25 years, acid deposition continues to cause widespread damage to the environment in Europe and eastern North America. Legislation to limit emissions of sulfur and nitrogen compounds in Europe is now under revision. The most recent protocol was based in part on the critical loads concept. The new protocol may also take into consideration the time delays between dose and response inherent in natural ecosystems. Policy decisions to reduce adverse effects on ecosystems entail a trade-off: quick response will require deeper cuts in emissions and thus higher costs, whereas lower costs with lesser cuts in emissions will give slower response. Acidification of lakes and damage to fish populations in Norway is used as an example. Under current legislation for emission reductions, surface waters will continue to slowly recover, but for many decades lakes in about 18% of Norway will continue to have water quality insufficient to support healthy populations of brown trout and other indicator organisms. Additional emission reductions can speed up the rate and degree of recovery.

  10. Biomineralization control related to population density under ocean acidification

    NASA Astrophysics Data System (ADS)

    Goffredo, Stefano; Prada, Fiorella; Caroselli, Erik; Capaccioni, Bruno; Zaccanti, Francesco; Pasquini, Luca; Fantazzini, Paola; Fermani, Simona; Reggi, Michela; Levy, Oren; Fabricius, Katharina E.; Dubinsky, Zvy; Falini, Giuseppe

    2014-07-01

    Anthropogenic CO2 is a major driver of present environmental change in most ecosystems, and the related ocean acidification is threatening marine biota. With increasing pCO2, calcification rates of several species decrease, although cases of upregulation are observed. Here, we show that biological control over mineralization relates to species abundance along a natural pH gradient. As pCO2 increased, the mineralogy of a scleractinian coral (Balanophyllia europaea) and a mollusc (Vermetus triqueter) did not change. In contrast, two calcifying algae (Padina pavonica and Acetabularia acetabulum) reduced and changed mineralization with increasing pCO2, from aragonite to the less soluble calcium sulphates and whewellite, respectively. As pCO2 increased, the coral and mollusc abundance was severely reduced, with both species disappearing at pH < 7.8. Conversely, the two calcifying and a non-calcifying algae (Lobophora variegata) showed less severe or no reductions with increasing pCO2, and were all found at the lowest pH site. The mineralization response to decreasing pH suggests a link with the degree of control over the biomineralization process by the organism, as only species with lower control managed to thrive in the lowest pH.

  11. Spatial competition dynamics between reef corals under ocean acidification.

    PubMed

    Horwitz, Rael; Hoogenboom, Mia O; Fine, Maoz

    2017-01-09

    Climate change, including ocean acidification (OA), represents a major threat to coral-reef ecosystems. Although previous experiments have shown that OA can negatively affect the fitness of reef corals, these have not included the long-term effects of competition for space on coral growth rates. Our multispecies year-long study subjected reef-building corals from the Gulf of Aqaba (Red Sea) to competitive interactions under present-day ocean pH (pH 8.1) and predicted end-of-century ocean pH (pH 7.6). Results showed coral growth is significantly impeded by OA under intraspecific competition for five out of six study species. Reduced growth from OA, however, is negligible when growth is already suppressed in the presence of interspecific competition. Using a spatial competition model, our analysis indicates shifts in the competitive hierarchy and a decrease in overall coral cover under lowered pH. Collectively, our case study demonstrates how modified competitive performance under increasing OA will in all likelihood change the composition, structure and functionality of reef coral communities.

  12. Coral Reefs Under Rapid Climate Change and Ocean Acidification

    NASA Astrophysics Data System (ADS)

    Hoegh-Guldberg, O.; Mumby, P. J.; Hooten, A. J.; Steneck, R. S.; Greenfield, P.; Gomez, E.; Harvell, C. D.; Sale, P. F.; Edwards, A. J.; Caldeira, K.; Knowlton, N.; Eakin, C. M.; Iglesias-Prieto, R.; Muthiga, N.; Bradbury, R. H.; Dubi, A.; Hatziolos, M. E.

    2007-12-01

    Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2°C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

  13. Key Arctic pelagic mollusc (Limacina helicina) threatened by ocean acidification

    NASA Astrophysics Data System (ADS)

    Comeau, S.; Gorsky, G.; Jeffree, R.; Teyssié, J.-L.; Gattuso, J.-P.

    2009-02-01

    Thecosome pteropods (shelled pelagic molluscs) can play an important role in the food web of various ecosystems and play a key role in the cycling of carbon and carbonate. Since they harbor an aragonitic shell, they could be very sensitive to ocean acidification driven by the increase of anthropogenic CO2 emissions. The impact of changes in the carbonate chemistry was investigated on Limacina helicina, a key species of Arctic ecosystems. Pteropods were kept in culture under controlled pH conditions corresponding to pCO2 levels of 350 and 760 μatm. Calcification was estimated using a fluorochrome and the radioisotope 45Ca. It exhibits a 28% decrease at the pH value expected for 2100 compared to the present pH value. This result supports the concern for the future of pteropods in a high-CO2 world, as well as of those species dependent upon them as a food resource. A decline of their populations would likely cause dramatic changes to the structure, function and services of polar ecosystems.

  14. Response of the Miliolid Archaias angulatus to simulated ocean acidification

    USGS Publications Warehouse

    Knorr, Paul O.; Robbins, Lisa L.; Harries, Peter J.; Hallock, Pamela; Wynn, Jonathan

    2015-01-01

    A common, but not universal, effect of ocean acidification on benthic foraminifera is a reduction in the growth rate. The miliolid Archaias angulatus is a high-Mg (>4 mole% MgCO3), symbiont-bearing, soritid benthic foraminifer that contributes to Caribbean reef carbonate sediments. A laboratory culture study assessed the effects of reduced pH on the growth of A. angulatus. We observed a statistically significant 50% reduction in the growth rate (p < 0.01), calculated from changes in maximum diameter, from 160 μm/28 days in the pH 8.0/pCO2air 480 ppm control group to 80 μm/28 days at a treatment level of pH 7.6/pCO2air 1328 ppm. Additionally, pseudopore area, δ18O values, and Mg/Ca ratio all increased, albeit slightly in the latter two variables. The reduction in growth rate indicates that under a high-CO2 setting, future A. angulatus populations will consist of smaller adults. A model using the results of this study estimates that at pH 7.6 A. angulatus carbonate production in the South Florida reef tract and Florida Bay decreases by 85%, from 0.27 Mt/yr to 0.04 Mt/yr, over an area of 9,000 km2.

  15. Public understanding in Great Britain of ocean acidification

    NASA Astrophysics Data System (ADS)

    Capstick, Stuart B.; Pidgeon, Nick F.; Corner, Adam J.; Spence, Elspeth M.; Pearson, Paul N.

    2016-08-01

    Public engagement with climate change is critical for maintaining the impetus for meaningful emissions cuts. Ocean acidification (OA) is increasingly recognized by marine scientists as an important, but often overlooked, consequence of anthropogenic emissions. Although substantial evidence now exists concerning people’s understanding of climate change more generally, very little is known about public perceptions of OA. Here, for the first time, we characterize in detail people’s understanding of this topic using survey data obtained in Great Britain (n = 2,501) during 2013 and 2014. We draw on theories of risk perception and consider how personal values influence attitudes towards OA. We find that public awareness of OA is very low compared to that of climate change, and was unaffected by the publication of the IPCC Fifth Assessment Report. Using an experimental approach, we show that providing basic information can heighten concern about OA, however, we find that attitude polarization along value-based lines may occur if the topic is explicitly associated with climate change. We discuss the implications of our findings for public engagement with OA, and the importance of learning lessons from communications research relating to climate change.

  16. Ocean acidification alters the material properties of Mytilus edulis shells.

    PubMed

    Fitzer, Susan C; Zhu, Wenzhong; Tanner, K Elizabeth; Phoenix, Vernon R; Kamenos, Nicholas A; Cusack, Maggie

    2015-02-06

    Ocean acidification (OA) and the resultant changing carbonate saturation states is threatening the formation of calcium carbonate shells and exoskeletons of marine organisms. The production of biominerals in such organisms relies on the availability of carbonate and the ability of the organism to biomineralize in changing environments. To understand how biomineralizers will respond to OA the common blue mussel, Mytilus edulis, was cultured at projected levels of pCO2 (380, 550, 750, 1000 µatm) and increased temperatures (ambient, ambient plus 2°C). Nanoindentation (a single mussel shell) and microhardness testing were used to assess the material properties of the shells. Young's modulus (E), hardness (H) and toughness (KIC) were measured in mussel shells grown in multiple stressor conditions. OA caused mussels to produce shell calcite that is stiffer (higher modulus of elasticity) and harder than shells grown in control conditions. The outer shell (calcite) is more brittle in OA conditions while the inner shell (aragonite) is softer and less stiff in shells grown under OA conditions. Combining increasing ocean pCO2 and temperatures as projected for future global ocean appears to reduce the impact of increasing pCO2 on the material properties of the mussel shell. OA may cause changes in shell material properties that could prove problematic under predation scenarios for the mussels; however, this may be partially mitigated by increasing temperature.

  17. Coral reefs under rapid climate change and ocean acidification.

    PubMed

    Hoegh-Guldberg, O; Mumby, P J; Hooten, A J; Steneck, R S; Greenfield, P; Gomez, E; Harvell, C D; Sale, P F; Edwards, A J; Caldeira, K; Knowlton, N; Eakin, C M; Iglesias-Prieto, R; Muthiga, N; Bradbury, R H; Dubi, A; Hatziolos, M E

    2007-12-14

    Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2 degrees C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.

  18. Spatial competition dynamics between reef corals under ocean acidification

    NASA Astrophysics Data System (ADS)

    Horwitz, Rael; Hoogenboom, Mia O.; Fine, Maoz

    2017-01-01

    Climate change, including ocean acidification (OA), represents a major threat to coral-reef ecosystems. Although previous experiments have shown that OA can negatively affect the fitness of reef corals, these have not included the long-term effects of competition for space on coral growth rates. Our multispecies year-long study subjected reef-building corals from the Gulf of Aqaba (Red Sea) to competitive interactions under present-day ocean pH (pH 8.1) and predicted end-of-century ocean pH (pH 7.6). Results showed coral growth is significantly impeded by OA under intraspecific competition for five out of six study species. Reduced growth from OA, however, is negligible when growth is already suppressed in the presence of interspecific competition. Using a spatial competition model, our analysis indicates shifts in the competitive hierarchy and a decrease in overall coral cover under lowered pH. Collectively, our case study demonstrates how modified competitive performance under increasing OA will in all likelihood change the composition, structure and functionality of reef coral communities.

  19. Framework of barrier reefs threatened by ocean acidification.

    PubMed

    Comeau, Steeve; Lantz, Coulson A; Edmunds, Peter J; Carpenter, Robert C

    2016-03-01

    To date, studies of ocean acidification (OA) on coral reefs have focused on organisms rather than communities, and the few community effects that have been addressed have focused on shallow back reef habitats. The effects of OA on outer barrier reefs, which are the most striking of coral reef habitats and are functionally and physically different from back reefs, are unknown. Using 5-m long outdoor flumes to create treatment conditions, we constructed coral reef communities comprised of calcified algae, corals, and reef pavement that were assembled to match the community structure at 17 m depth on the outer barrier reef of Moorea, French Polynesia. Communities were maintained under ambient and 1200 μatm pCO2 for 7 weeks, and net calcification rates were measured at different flow speeds. Community net calcification was significantly affected by OA, especially at night when net calcification was depressed ~78% compared to ambient pCO2 . Flow speed (2-14 cm s(-1) ) enhanced net calcification only at night under elevated pCO2 . Reef pavement also was affected by OA, with dissolution ~86% higher under elevated pCO2 compared to ambient pCO2 . These results suggest that net accretion of outer barrier reef communities will decline under OA conditions predicted within the next 100 years, largely because of increased dissolution of reef pavement. Such extensive dissolution poses a threat to the carbonate foundation of barrier reef communities.

  20. Spatial competition dynamics between reef corals under ocean acidification

    PubMed Central

    Horwitz, Rael; Hoogenboom, Mia O.; Fine, Maoz

    2017-01-01

    Climate change, including ocean acidification (OA), represents a major threat to coral-reef ecosystems. Although previous experiments have shown that OA can negatively affect the fitness of reef corals, these have not included the long-term effects of competition for space on coral growth rates. Our multispecies year-long study subjected reef-building corals from the Gulf of Aqaba (Red Sea) to competitive interactions under present-day ocean pH (pH 8.1) and predicted end-of-century ocean pH (pH 7.6). Results showed coral growth is significantly impeded by OA under intraspecific competition for five out of six study species. Reduced growth from OA, however, is negligible when growth is already suppressed in the presence of interspecific competition. Using a spatial competition model, our analysis indicates shifts in the competitive hierarchy and a decrease in overall coral cover under lowered pH. Collectively, our case study demonstrates how modified competitive performance under increasing OA will in all likelihood change the composition, structure and functionality of reef coral communities. PMID:28067281

  1. Extracellular protons reduce quantal content and prolong synaptic currents at the Drosophila larval neuromuscular junction.

    PubMed

    Sandstrom, David J

    2011-10-01

    Fluctuations in extracellular pH occur in the nervous system in response to a number of physiological and pathological processes, such as ischemia, hypercapnea, and high-frequency activity. Using the Drosophila larval neuromuscular junction, the author has examined acute effects of low and high pH on excitability and synaptic transmission. Acidification rapidly and reversibly reduces the size of electrically evoked excitatory junctional currents (EJCs) in a concentration-dependent manner, with transmission nearly abolished at pH 5.0. Conversely, raising pH to 7.8 increases EJC amplitude significantly. Further elevation to pH 8.5 causes an initial increase in amplitude, followed by profound, long-lasting depression of the synapse. Amplitudes of spontaneous miniature EJCs (mEJCs) are modestly, but significantly reduced at pH 5.0. It is therefore the number of quanta released per action potential, rather than the size of individual quanta, that is most strongly affected. Decay times of both EJCs and mEJCs are dramatically lengthened at low pH, suggesting that glutamate remains in the synaptic cleft for much longer than normal. Presynaptic excitability is also reduced, as indicated by increased latency between nerve shock and EJC onset. The response to low pH was not altered by mutations in genes encoding Transient Receptor Potential, Mucolipin subfamily (TRPML) and Slowpoke ion channels, which had previously been implicated as possible targets of extracellular protons. The author concludes that extracellular protons have strong effects on the release of glutamate and the time course of synaptic currents. These phenotypes can be exploited to study the mechanisms of acid-mediated changes in neuronal function, and to pursue the way in which pH modulates synaptic function in normal and pathophysiological conditions.

  2. Reciprocal regulation of two G protein-coupled receptors sensing extracellular concentrations of Ca2+ and H.

    PubMed

    Wei, Wei-Chun; Jacobs, Benjamin; Becker, Esther B E; Glitsch, Maike D

    2015-08-25

    G protein-coupled receptors (GPCRs) are cell surface receptors that detect a wide range of extracellular messengers and convey this information to the inside of cells. Extracellular calcium-sensing receptor (CaSR) and ovarian cancer gene receptor 1 (OGR1) are two GPCRs that sense extracellular Ca(2+) and H(+), respectively. These two ions are key components of the interstitial fluid, and their concentrations change in an activity-dependent manner. Importantly, the interstitial fluid forms part of the microenvironment that influences cell function in health and disease; however, the exact mechanisms through which changes in the microenvironment influence cell function remain largely unknown. We show that CaSR and OGR1 reciprocally inhibit signaling through each other in central neurons, and that this is lost in their transformed counterparts. Furthermore, strong intracellular acidification impairs CaSR function, but potentiates OGR1 function. Thus, CaSR and OGR1 activities can be regulated in a seesaw manner, whereby conditions promoting signaling through one receptor simultaneously inhibit signaling through the other receptor, potentiating the difference in their relative signaling activity. Our results provide insight into how small but consistent changes in the ionic microenvironment of cells can significantly alter the balance between two signaling pathways, which may contribute to disease progression.

  3. Ocean acidification causes bleaching and productivity loss in coral reef builders.

    PubMed

    Anthony, K R N; Kline, D I; Diaz-Pulido, G; Dove, S; Hoegh-Guldberg, O

    2008-11-11

    Ocean acidification represents a key threat to coral reefs by reducing the calcification rate of framework builders. In addition, acidification is likely to affect the relationship between corals and their symbiotic dinoflagellates and the productivity of this association. However, little is known about how acidification impacts on the physiology of reef builders and how acidification interacts with warming. Here, we report on an 8-week study that compared bleaching, productivity, and calcification responses of crustose coralline algae (CCA) and branching (Acropora) and massive (Porites) coral species in response to acidification and warming. Using a 30-tank experimental system, we manipulated CO(2) levels to simulate doubling and three- to fourfold increases [Intergovernmental Panel on Climate Change (IPCC) projection categories IV and VI] relative to present-day levels under cool and warm scenarios. Results indicated that high CO(2) is a bleaching agent for corals and CCA under high irradiance, acting synergistically with warming to lower thermal bleaching thresholds. We propose that CO(2) induces bleaching via its impact on photoprotective mechanisms of the photosystems. Overall, acidification impacted more strongly on bleaching and productivity than on calcification. Interestingly, the intermediate, warm CO(2) scenario led to a 30% increase in productivity in Acropora, whereas high CO(2) lead to zero productivity in both corals. CCA were most sensitive to acidification, with high CO(2) leading to negative productivity and high rates of net dissolution. Our findings suggest that sensitive reef-building species such as CCA may be pushed beyond their thresholds for growth and survival within the next few decades whereas corals will show delayed and mixed responses.

  4. Acidification of endocytic vesicles by an ATP-dependent proton pump

    PubMed Central

    1983-01-01

    One of the early events in the pathway of receptor-mediated endocytosis is the acidification of the newly formed endocytic vesicle. To examine the mechanism of acidification, we used fluorescein-labeled alpha 2- macroglobulin (F-alpha 2M) as a probe for endocytic vesicle pH. Changes in pH were determined from the change in fluorescein fluorescence at 490-nm excitation as measured with a microscope spectrofluorometer. After endocytosis of F-alpha 2M, mouse fibroblast cells were permeabilized by brief exposure to the detergent digitonin. Treatment with the ionophore monensin or the protonophore carbonyl cyanide p- trifluoromethoxyphenylhydrazone (FCCP) caused a rapid increase in the pH of the endocytic vesicle. Upon removal of the ionophore, the endocytic vesicle rapidly acidified only when MgATP or MgGTP was added. Neither ADP nor the nonhydrolyzable analog, adenosine 5'-(beta, gamma- imido)triphosphate (AMP-PNP) could support acidification. The ATP- dependent acidification did not require a specific cation or anion in the external media. Acidification was insensitive to vanadate and amiloride but was inhibited by Zn2+ and the anion transport inhibitor diisothiocyanostilbene disulfonic acid (DIDS). We also examined the acidification of lysosomes with the permeabilized cell system, using fluorescein isothiocyanate dextran as probe. DIDS inhibited the ATP- dependent reacidification of lysosomes, although at a lower concentration than that for inhibition of endocytic vesicle reacidification. These results demonstrate that endocytic vesicles contain an ATP-dependent acidification mechanism that shares similar characteristics with the previously described lysosomal proton pump. PMID:6224803

  5. Defective organellar acidification as a cause of cystic fibrosis lung disease: reexamination of a recurring hypothesis

    PubMed Central

    Haggie, Peter M.; Verkman, A. S.

    2009-01-01

    The cellular mechanisms by which loss-of-function mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel produce cystic fibrosis (CF) lung disease remain uncertain. Defective organellar function has been proposed as an important determinant in the pathogenesis of CF lung disease. According to one hypothesis, reduced CFTR chloride conductance in organelles in CF impairs their acidification by preventing chloride entry into the organelle lumen, which is needed to balance the positive charge produced by proton entry. According to a different hypothesis, CFTR mutation hyperacidifies organelles by an indirect mechanism involving unregulated sodium efflux through epithelial sodium channels. There are reports of defective Golgi, endosomal and lysosomal acidification in CF epithelial cells, defective phagolysosomal acidification in CF alveolar macrophages, and organellar hyperacidification in CF respiratory epithelial cells. The common theme relating too high or low organellar pH to cellular dysfunction and CF pathogenesis is impaired functioning of organellar enzymes, such as those involved in ceramide metabolism and protein processing in epithelial cells and antimicrobial activity in alveolar macrophages. We review here the evidence for defective organellar acidification in CF. Significant technical and conceptual concerns are discussed regarding the validity of data showing too high/low organellar pH in CF cells, and rigorous measurements of organellar pH in CF cells are reviewed that fail to support defective organellar acidification in CF. Indeed, there is an expanding body of evidence supporting the involvement of non-CFTR chloride channels in organellar acidification. We conclude that biologically significant involvement of CFTR in organellar acidification is unlikely. PMID:19329540

  6. National Athletic Trainers' Association Position Statement: Exertional Heat Illnesses

    PubMed Central

    Binkley, Helen M.; Beckett, Joseph; Casa, Douglas J.; Kleiner, Douglas M.; Plummer, Paul E.

    2002-01-01

    Objective: To present recommendations for the prevention, recognition, and treatment of exertional heat illnesses and to describe the relevant physiology of thermoregulation. Background: Certified athletic trainers evaluate and treat heat-related injuries during athletic activity in “safe” and high-risk environments. While the recognition of heat illness has improved, the subtle signs and symptoms associated with heat illness are often overlooked, resulting in more serious problems for affected athletes. The recommendations presented here provide athletic trainers and allied health providers with an integrated scientific and practical approach to the prevention, recognition, and treatment of heat illnesses. These recommendations can be modified based on the environmental conditions of the site, the specific sport, and individual considerations to maximize safety and performance. Recommendations: Certified athletic trainers and other allied health providers should use these recommendations to establish on-site emergency plans for their venues and athletes. The primary goal of athlete safety is addressed through the prevention and recognition of heat-related illnesses and a well-developed plan to evaluate and treat affected athletes. Even with a heat-illness prevention plan that includes medical screening, acclimatization, conditioning, environmental monitoring, and suitable practice adjustments, heat illness can and does occur. Athletic trainers and other allied health providers must be prepared to respond in an expedient manner to alleviate symptoms and minimize morbidity and mortality. PMID:12937591

  7. Multiple Mechanisms of Anti-Cancer Effects Exerted by Astaxanthin

    PubMed Central

    Zhang, Li; Wang, Handong

    2015-01-01

    Astaxanthin (ATX) is a xanthophyll carotenoid which has been approved by the United States Food and Drug Administration (USFDA) as food colorant in animal and fish feed. It is widely found in algae and aquatic animals and has powerful anti-oxidative activity. Previous studies have revealed that ATX, with its anti-oxidative property, is beneficial as a therapeutic agent for various diseases without any side effects or toxicity. In addition, ATX also shows preclinical anti-tumor efficacy both in vivo and in vitro in various cancer models. Several researches have deciphered that ATX exerts its anti-proliferative, anti-apoptosis and anti-invasion influence via different molecules and pathways including signal transducer and activator of transcription 3 (STAT3), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and peroxisome proliferator-activated receptor gamma (PPARγ). Hence, ATX shows great promise as chemotherapeutic agents in cancer. Here, we review the rapidly advancing field of ATX in cancer therapy as well as some molecular targets of ATX. PMID:26184238

  8. Respiratory and leg muscles perceived exertion during exercise at altitude.

    PubMed

    Aliverti, A; Kayser, B; Lo Mauro, A; Quaranta, M; Pompilio, P; Dellacà, R L; Ora, J; Biasco, L; Cavalleri, L; Pomidori, L; Cogo, A; Pellegrino, R; Miserocchi, G

    2011-07-31

    We compared the rate of perceived exertion for respiratory (RPE,resp) and leg (RPE,legs) muscles, using a 10-point Borg scale, to their specific power outputs in 10 healthy male subjects during incremental cycle exercise at sea level (SL) and high altitude (HA, 4559 m). Respiratory power output was calculated from breath-by-breath esophageal pressure and chest wall volume changes. At HA ventilation was increased at any leg power output by ∼ 54%. However, for any given ventilation, breathing pattern was unchanged in terms of tidal volume, respiratory rate and operational volumes of the different chest wall compartments. RPE,resp scaled uniquely with total respiratory power output, irrespectively of SL or HA, while RPE,legs for any leg power output was exacerbated at HA. With increasing respective power outputs, the rate of change of RPE,resp exponentially decreased, while that of RPE,legs increased. We conclude that RPE,resp uniquely relates to respiratory power output, while RPE,legs varies depending on muscle metabolic conditions.

  9. Resveratrol exerts pharmacological preconditioning by activating PGC-1alpha.

    PubMed

    Tan, Lan; Yu, Jin-Tai; Guan, Hua-Shi

    2008-11-01

    Resveratrol (RSV), a polyphenol phytoalexin abundantly found in grape skins and in wines, is currently the focus of intense research as a pharmacological preconditioning agent in kidney, heart, and brain from ischemic injury. However, the exact molecular mechanism of RSV preconditioning remains obscure. The data from current studies indicate that pharmacological preconditioning with RSV were attributed to its role as intracellular antioxidant, anti-inflammatory agent, its ability to induce nitric oxide synthase (NOS) expression, its ability to induce angiogenesis, and its ability to increases sirtuin 1 (SIRT1) activity. Peroxisome proliferators-activated receptor (PPAR) gamma co-activator-1alpha (PGC-1alpha) is a member of a family of transcription coactivators that owns mitochondrial biogenesis, antioxidation, growth factor signaling regulation, and angiogenesis activities. And, almost all the signaling pathways activated by RVS involve in PGC-1alpha activity. Moreover, it has been proofed that RVS could mediate an increase PGC-1alpha activity. These significant conditions support the hypothesis that RSV exerts pharmacological preconditioning by activating PGC-1alpha. Attempts to confirm this hypothesis will provide new directions in the study of pharmaceutical preconditioning and the development of new treatment approaches for reducing the extent of ischemia/reperfusion injury.

  10. Cannabidiol exerts sebostatic and antiinflammatory effects on human sebocytes

    PubMed Central

    Oláh, Attila; Tóth, Balázs I.; Borbíró, István; Sugawara, Koji; Szöllõsi, Attila G.; Czifra, Gabriella; Pál, Balázs; Ambrus, Lídia; Kloepper, Jennifer; Camera, Emanuela; Ludovici, Matteo; Picardo, Mauro; Voets, Thomas; Zouboulis, Christos C.; Paus, Ralf; Bíró, Tamás

    2014-01-01

    The endocannabinoid system (ECS) regulates multiple physiological processes, including cutaneous cell growth and differentiation. Here, we explored the effects of the major nonpsychotropic phytocannabinoid of Cannabis sativa, (-)-cannabidiol (CBD), on human sebaceous gland function and determined that CBD behaves as a highly effective sebostatic agent. Administration of CBD to cultured human sebocytes and human skin organ culture inhibited the lipogenic actions of various compounds, including arachidonic acid and a combination of linoleic acid and testosterone, and suppressed sebocyte proliferation via the activation of transient receptor potential vanilloid-4 (TRPV4) ion channels. Activation of TRPV4 interfered with the prolipogenic ERK1/2 MAPK pathway and resulted in the downregulation of nuclear receptor interacting protein-1 (NRIP1), which influences glucose and lipid metabolism, thereby inhibiting sebocyte lipogenesis. CBD also exerted complex antiinflammatory actions that were coupled to A2a adenosine receptor-dependent upregulation of tribbles homolog 3 (TRIB3) and inhibition of the NF-κB signaling. Collectively, our findings suggest that, due to the combined lipostatic, antiproliferative, and antiinflammatory effects, CBD has potential as a promising therapeutic agent for the treatment of acne vulgaris. PMID:25061872

  11. Cannabidiol exerts sebostatic and antiinflammatory effects on human sebocytes.

    PubMed

    Oláh, Attila; Tóth, Balázs I; Borbíró, István; Sugawara, Koji; Szöllõsi, Attila G; Czifra, Gabriella; Pál, Balázs; Ambrus, Lídia; Kloepper, Jennifer; Camera, Emanuela; Ludovici, Matteo; Picardo, Mauro; Voets, Thomas; Zouboulis, Christos C; Paus, Ralf; Bíró, Tamás

    2014-09-01

    The endocannabinoid system (ECS) regulates multiple physiological processes, including cutaneous cell growth and differentiation. Here, we explored the effects of the major nonpsychotropic phytocannabinoid of Cannabis sativa, (-)-cannabidiol (CBD), on human sebaceous gland function and determined that CBD behaves as a highly effective sebostatic agent. Administration of CBD to cultured human sebocytes and human skin organ culture inhibited the lipogenic actions of various compounds, including arachidonic acid and a combination of linoleic acid and testosterone, and suppressed sebocyte proliferation via the activation of transient receptor potential vanilloid-4 (TRPV4) ion channels. Activation of TRPV4 interfered with the prolipogenic ERK1/2 MAPK pathway and resulted in the downregulation of nuclear receptor interacting protein-1 (NRIP1), which influences glucose and lipid metabolism, thereby inhibiting sebocyte lipogenesis. CBD also exerted complex antiinflammatory actions that were coupled to A2a adenosine receptor-dependent upregulation of tribbles homolog 3 (TRIB3) and inhibition of the NF-κB signaling. Collectively, our findings suggest that, due to the combined lipostatic, antiproliferative, and antiinflammatory effects, CBD has potential as a promising therapeutic agent for the treatment of acne vulgaris.

  12. Matrix Metalloproteinase 9 Exerts Antiviral Activity against Respiratory Syncytial Virus

    PubMed Central

    Dabo, Abdoulaye J.; Cummins, Neville; Eden, Edward; Geraghty, Patrick

    2015-01-01

    Increased lung levels of matrix metalloproteinase 9 (MMP9) are frequently observed during respiratory syncytial virus (RSV) infection and elevated MMP9 concentrations are associated with severe disease. However little is known of the functional role of MMP9 during lung infection with RSV. To determine whether MMP9 exerted direct antiviral potential, active MMP9 was incubated with RSV, which showed that MMP9 directly prevented RSV infectivity to airway epithelial cells. Using knockout mice the effect of the loss of Mmp9 expression was examined during RSV infection to demonstrate MMP9’s role in viral clearance and disease progression. Seven days following RSV infection, Mmp9-/- mice displayed substantial weight loss, increased RSV-induced airway hyperresponsiveness (AHR) and reduced clearance of RSV from the lungs compared to wild type mice. Although total bronchoalveolar lavage fluid (BALF) cell counts were similar in both groups, neutrophil recruitment to the lungs during RSV infection was significantly reduced in Mmp9-/- mice. Reduced neutrophil recruitment coincided with diminished RANTES, IL-1β, SCF, G-CSF expression and p38 phosphorylation. Induction of p38 signaling was required for RANTES and G-CSF expression during RSV infection in airway epithelial cells. Therefore, MMP9 in RSV lung infection significantly enhances neutrophil recruitment, cytokine production and viral clearance while reducing AHR. PMID:26284919

  13. Extracellular pH in the isolated retina of the toad in darkness and during illumination.

    PubMed Central

    Oakley, B; Wen, R

    1989-01-01

    1. Extracellular pH (pHo) was measured in the isolated retina preparation of the toad, Bufo marinus, using H(+)-selective microelectrodes. During superfusion with phosphate-buffered solution (pH 7.8), which had a low buffering capacity, pHo in the inner retina was 7.0-7.2 and there was a pHo gradient throughout the distal retina and into the bathing solution. 2. The retinal acidity appears to be due in part to the combined reactions of glycolysis and ATP hydrolysis, since anoxia greatly increased the pHo gradient, while superfusion with either glucose-free pyruvate solution or strophanthidin decreased this gradient. 3. Maintained illumination evoked both an acidification in the proximal retina and an alkalinization in the distal retina. Blocking synaptic transmission to second-order neurones (1.0 mM-aspartate) decreased the acidification but had little effect on the alkalinization, consistent with the notion that the alkalinization is of receptoral origin, while the acidification is of post-receptoral origin. 4. Retinal neurones extrude a significant amount of acid via Na(+)-H+ exchange, since 2.0 mM-amiloride, a blocker of Na(+)-H+ exchange, caused a sustained alkalinization in darkness and decreased the light-evoked changes in pHo, while 1.0 mM-4-acetamido-4'-isothiocyanatostilbene-2.2'-disulphonic acid (SITS), a blocker of Cl(-)-HCO3- exchange, produced a much smaller alkalinization. 5. Switching to a bicarbonate-buffered solution having a 75 times greater buffering capacity than the phosphate-buffered solution caused retinal pHo to become less acidic and significantly decreased the amplitude of the light-evoked pHo changes. 6. Addition of 2.0 mM-acetazolamide, a carbonic anhydrase inhibitor, to the bicarbonate-buffered solution increased both the pHo gradient and the light-evoked changes in pHo. These data are consistent with the idea that carbonic anhydrase, which is concentrated in Müller (glial) cells and to a lesser extent in horizontal cells, increases

  14. Extracellular matrix: A dynamic microenvironment for stem cell niche☆

    PubMed Central

    Gattazzo, Francesca; Urciuolo, Anna; Bonaldo, Paolo

    2014-01-01

    Background Extracellular matrix (ECM) is a dynamic and complex environment characterized by biophysical, mechanical and biochemical properties specific for each tissue and able to regulate cell behavior. Stem cells have a key role in the maintenance and regeneration of tissues and they are located in a specific microenvironment, defined as niche. Scope of review We overview the progresses that have been made in elucidating stem cell niches and discuss the mechanisms by which ECM affects stem cell behavior. We also summarize the current tools and experimental models for studying ECM–stem cell interactions. Major conclusions ECM represents an essential player in stem cell niche, since it can directly or indirectly modulate the maintenance, proliferation, self-renewal and differentiation of stem cells. Several ECM molecules play regulatory functions for different types of stem cells, and based on its molecular composition the ECM can be deposited and finely tuned for providing the most appropriate niche for stem cells in the various tissues. Engineered biomaterials able to mimic the in vivo characteristics of stem cell niche provide suitable in vitro tools for dissecting the different roles exerted by the ECM and its molecular components on stem cell behavior. General significance ECM is a key component of stem cell niches and is involved in various aspects of stem cell behavior, thus having a major impact on tissue homeostasis and regeneration under physiological and pathological conditions. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties. PMID:24418517

  15. Extracellular-matrix tethering regulates stem-cell fate

    NASA Astrophysics Data System (ADS)

    Trappmann, Britta; Gautrot, Julien E.; Connelly, John T.; Strange, Daniel G. T.; Li, Yuan; Oyen, Michelle L.; Cohen Stuart, Martien A.; Boehm, Heike; Li, Bojun; Vogel, Viola; Spatz, Joachim P.; Watt, Fiona M.; Huck, Wilhelm T. S.

    2012-07-01

    To investigate how substrate properties influence stem-cell fate, we cultured single human epidermal stem cells on polydimethylsiloxane (PDMS) and polyacrylamide (PAAm) hydrogel surfaces, 0.1 kPa-2.3 MPa in stiffness, with a covalently attached collagen coating. Cell spreading and differentiation were unaffected by polydimethylsiloxane stiffness. However, cells on polyacrylamide of low elastic modulus (0.5 kPa) could not form stable focal adhesions and differentiated as a result of decreased activation of the extracellular-signal-related kinase (ERK)/mitogen-activated protein kinase (MAPK) signalling pathway. The differentiation of human mesenchymal stem cells was also unaffected by PDMS stiffness but regulated by the elastic modulus of PAAm. Dextran penetration measurements indicated that polyacrylamide substrates of low elastic modulus were more porous than stiff substrates, suggesting that the collagen anchoring points would be further apart. We then changed collagen crosslink concentration and used hydrogel-nanoparticle substrates to vary anchoring distance at constant substrate stiffness. Lower collagen anchoring density resulted in increased differentiation. We conclude that stem cells exert a mechanical force on collagen fibres and gauge the feedback to make cell-fate decisions.

  16. Platelets: New Bricks in the Building of Neutrophil Extracellular Traps

    PubMed Central

    Carestia, Agostina; Kaufman, Tomas; Schattner, Mirta

    2016-01-01

    In addition to being key elements in hemostasis and thrombosis, platelets have an important role in the inflammatory and innate immune response. This activity is associated with their capability to recognize pathogens through the expression of toll-like receptors, the secretion of various cytokines, chemokines, and growth factors stored within their granules, and the expression of cell adhesion molecules that allows interaction with other immune cells, mainly neutrophils and monocytes. As part of the first line of defense, neutrophils control invading pathogens by phagocytosis, the release of antimicrobial proteins during degranulation, or through the formation of web-like structures named neutrophil extracellular traps (NETs). NETs are formed by chromatin, proteases, and antimicrobial proteins, and their main function is to trap and kill bacteria, virus, and fungi, avoiding their dissemination. Besides microorganisms, NET formation is also triggered by proinflammatory molecules and platelets. The uncontrolled formation of NETs might exert tissue damage and has been involved in a pathogenic mechanism of autoimmune and prothrombotic clinical conditions. In this review, we discuss the role of platelets in NET generation highlighting the mediators, stimuli, and molecular mechanisms involved in this phenomenon, both in human and murine models. PMID:27458459

  17. Brain extracellular matrix retains connectivity in neuronal networks.

    PubMed

    Bikbaev, Arthur; Frischknecht, Renato; Heine, Martin

    2015-09-29

    The formation and maintenance of connectivity are critically important for the processing and storage of information in neuronal networks. The brain extracellular matrix (ECM) appears during postnatal development and surrounds most neurons in the adult mammalian brain. Importantly, the removal of the ECM was shown to improve plasticity and post-traumatic recovery in the CNS, but little is known about the mechanisms. Here, we investigated the role of the ECM in the regulation of the network activity in dissociated hippocampal cultures grown on microelectrode arrays (MEAs). We found that enzymatic removal of the ECM in mature cultures led to transient enhancement of neuronal activity, but prevented disinhibition-induced hyperexcitability that was evident in age-matched control cultures with intact ECM. Furthermore, the ECM degradation followed by disinhibition strongly affected the network interaction so that it strongly resembled the juvenile pattern seen in naïve developing cultures. Taken together, our results demonstrate that the ECM plays an important role in retention of existing connectivity in mature neuronal networks that can be exerted through synaptic confinement of glutamate. On the other hand, removal of the ECM can play a permissive role in modification of connectivity and adaptive exploration of novel network architecture.

  18. Environmental Conditions and the Occurrence of Exertional Heat Illnesses and Exertional Heat Stroke at the Falmouth Road Race

    PubMed Central

    DeMartini, Julie K.; Casa, Douglas J.; Belval, Luke N.; Crago, Arthur; Davis, Rob J.; Jardine, John J.; Stearns, Rebecca L.

    2014-01-01

    Context: The Falmouth Road Race is unique because of the environmental conditions and relatively short distance, which allow runners to maintain a high intensity for the duration of the event. Therefore, the occurrence of exertional heat illnesses (EHIs), especially exertional heat stroke (EHS), is 10 times higher than in other races. Objective: To summarize the occurrence and relationship of EHI and environmental conditions at the Falmouth Road Race. Design: Descriptive epidemiologic study. Setting: An 11.3-km (7-mile) road race in Falmouth, Massachusetts. Patients or Other Participants: Runners who sustained an EHI while participating in the Falmouth Road Race. Main Outcome Measure(s): We obtained 18 years of medical records and environmental conditions from the Falmouth Road Race and documented the incidence of EHI, specifically EHS, as related to ambient temperature (Tamb), relative humidity, and heat index (HI). Results: Average Tamb, relative humidity, and HI were 23.3 ± 2.5°C, 70 ± 16%, and 24 ± 3.5°C, respectively. Of the 393 total EHI cases observed, EHS accounted for 274 (70%). An average of 15.2 ± 13.0 EHS cases occurred each year; the incidence was 2.13 ± 1.62 cases per 1000 runners. Regression analysis revealed a relationship between the occurrence of both EHI and EHS and Tamb (R2 = 0.71, P = .001, and R2 = 0.65, P = .001, respectively) and HI (R2 = 0.76, P < .001, and R2 = 0.74, P < .001, respectively). Occurrences of EHS (24.2 ± 15.5 cases versus 9.3 ± 4.3 cases) and EHI (32.3 ± 16.3 versus 13.0 ± 4.9 cases) were higher when Tamb and HI were high compared with when Tamb and HI were low. Conclusions: Because of the environmental conditions and race duration, the Falmouth Road Race provides a unique setting for a high incidence of EHS. A clear relationship exists between environmental stress, especially as measured by Tamb and HI, and the occurrence of EHS or other EHI. Proper prevention and treatment strategies should be used during periods

  19. Influence of acidification and eutrophication on physiological functions of Conticribra weissflogii and Prorocentrum donghaiense.

    PubMed

    Zheng, Feng-Ying; Tu, Teng-Xiu; Liu, Feng-Jiao; Huang, Xu-Guang; Li, Shun-Xing

    2016-12-01

    Eutrophication and acidification have been the most concerned environmental problems in coastal ecosystem. However, their combined effect on coastal ecosystem function was unknown. Both diatom (Conticribra weissflogii) and dinoflagellate (Prorocentrum donghaiense) are used as coastal algal model. Seven parameters were determined for physiological function assessment, including cell density, chlorophyll a (Chl a), protein, malonaldehyde (MDA), superoxide dismutase, carbonic anhydrase (CA), and nitrate reductase (NR). The influence of nitrate (N) and phosphate (P) on MDA and CA in C. weissflogii was significant, and that on Chl a and protein in P. donghaiense were also significant. However, the influence of acidification on physiological functions was not significant. The effect of acidification could be intensified by coastal eutrophication. More importantly, the coexist influence of acidification and eutrophication on CA, NR and protein in C. weissflogii and MDA in P. donghaiense was significant. Both NR activity and Chl a content in P. donghaiense were positively correlated to N and P concentration when pH were 7.9 and 7.8, respectively. With simultaneous worsening of acidification and eutrophication, the cell growth of P. Donghaiense was accelerated more obviously than C. weissflogii, i.e., dinoflagellate was more adaptable than diatom, thus algal species distribution and abundance could be changed.

  20. Ocean acidification accelerates net calcium carbonate loss in a coral rubble community

    NASA Astrophysics Data System (ADS)

    Stubler, Amber D.; Peterson, Bradley J.

    2016-09-01

    Coral rubble communities are an important yet often overlooked component of a healthy reef ecosystem. The organisms inhabiting reef rubble are primarily bioeroders that contribute to the breakdown and dissolution of carbonate material. While the effects of ocean acidification on calcifying communities have been well studied, there are few studies investigating the response of bioeroding communities to future changes in pH and calcium carbonate saturation state. Using a flow-through pH-stat system, coral rubble pieces with a naturally occurring suite of organisms, along with bleached control rubble pieces, were subjected to three different levels of acidification over an 8-week period. Rates of net carbonate loss in bleached control rubble doubled in the acidification treatments (0.02 vs. 0.04% CaCO3 d-1 in ambient vs. moderate and high acidification), and living rubble communities experienced significantly increased rates of net carbonate loss from ambient to high acidification conditions (0.06 vs. 0.10% CaCO3 d-1, respectively). Although more experimentation is necessary to understand the long-term response and succession of coral rubble communities under projected conditions, these results suggest that rates of carbonate loss will increase in coral rubble as pH and calcium carbonate saturation states are reduced. This study demonstrates a need to thoroughly investigate the contribution of coral rubble to the overall carbonate budget, reef resilience, recovery, and function under future conditions.

  1. Gene expression changes in the coccolithophore Emiliania huxleyi after 500 generations of selection to ocean acidification.

    PubMed

    Lohbeck, Kai T; Riebesell, Ulf; Reusch, Thorsten B H

    2014-07-07

    Coccolithophores are unicellular marine algae that produce biogenic calcite scales and substantially contribute to marine primary production and carbon export to the deep ocean. Ongoing ocean acidification particularly impairs calcifying organisms, mostly resulting in decreased growth and calcification. Recent studies revealed that the immediate physiological response in the coccolithophore Emiliania huxleyi to ocean acidification may be partially compensated by evolutionary adaptation, yet the underlying molecular mechanisms are currently unknown. Here, we report on the expression levels of 10 candidate genes putatively relevant to pH regulation, carbon transport, calcification and photosynthesis in E. huxleyi populations short-term exposed to ocean acidification conditions after acclimation (physiological response) and after 500 generations of high CO2 adaptation (adaptive response). The physiological response revealed downregulation of candidate genes, well reflecting the concomitant decrease of growth and calcification. In the adaptive response, putative pH regulation and carbon transport genes were up-regulated, matching partial restoration of growth and calcification in high CO2-adapted populations. Adaptation to ocean acidification in E. huxleyi likely involved improved cellular pH regulation, presumably indirectly affecting calcification. Adaptive evolution may thus have the potential to partially restore cellular pH regulatory capacity and thereby mitigate adverse effects of ocean acidification.

  2. The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming

    PubMed Central

    Castillo, Karl D.; Ries, Justin B.; Bruno, John F.; Westfield, Isaac T.

    2014-01-01

    Anthropogenic increases in atmospheric CO2 over this century are predicted to cause global average surface ocean pH to decline by 0.1–0.3 pH units and sea surface temperature to increase by 1–4°C. We conducted controlled laboratory experiments to investigate the impacts of CO2-induced ocean acidification (pCO2 = 324, 477, 604, 2553 µatm) and warming (25, 28, 32°C) on the calcification rate of the zooxanthellate scleractinian coral Siderastrea siderea, a widespread, abundant and keystone reef-builder in the Caribbean Sea. We show that both acidification and warming cause a parabolic response in the calcification rate within this coral species. Moderate increases in pCO2 and warming, relative to near-present-day values, enhanced coral calcification, with calcification rates declining under the highest pCO2 and thermal conditions. Equivalent responses to acidification and warming were exhibited by colonies across reef zones and the parabolic nature of the corals' response to these stressors was evident across all three of the experiment's 30-day observational intervals. Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate—suggesting that ocean warming poses a more immediate threat than acidification for this important coral species. PMID:25377455

  3. Resilience of SAR11 bacteria to rapid acidification in the high-latitude open ocean.

    PubMed

    Hartmann, Manuela; Hill, Polly G; Tynan, Eithne; Achterberg, Eric P; Leakey, Raymond J G; Zubkov, Mikhail V

    2016-02-01

    Ubiquitous SAR11 Alphaproteobacteria numerically dominate marine planktonic communities. Because they are excruciatingly difficult to cultivate, there is comparatively little known about their physiology and metabolic responses to long- and short-term environmental changes. As surface oceans take up anthropogenic, atmospheric CO2, the consequential process of ocean acidification could affect the global biogeochemical significance of SAR11. Shipping accidents or inadvertent release of chemicals from industrial plants can have strong short-term local effects on oceanic SAR11. This study investigated the effect of 2.5-fold acidification of seawater on the metabolism of SAR11 and other heterotrophic bacterioplankton along a natural temperature gradient crossing the North Atlantic Ocean, Norwegian and Greenland Seas. Uptake rates of the amino acid leucine by SAR11 cells as well as other bacterioplankton remained similar to controls despite an instant ∼50% increase in leucine bioavailability upon acidification. This high physiological resilience to acidification even without acclimation, suggests that open ocean dominant bacterioplankton are able to cope even with sudden and therefore more likely with long-term acidification effects.

  4. Institutional misfit and environmental change: A systems approach to address ocean acidification.

    PubMed

    Ekstrom, Julia A; Crona, Beatrice I

    2017-01-15

    Emerging environmental threats often lack sufficient governance to address the full extent of the problem. An example is ocean acidification which is a growing concern in fishing and aquaculture economies worldwide, but has remained a footnote in environmental policy at all governance levels. However, existing legal jurisdictions do account for some aspects of the system relating to ocean acidification and these may be leveraged to support adapting to and mitigating ocean acidification. We refine and apply a methodological framework that helps objectively evaluate governance, from a social-ecological systems perspective. We assess how well a set of extant US institutions fits with the social-ecological interactions pertinent to ocean acidification. The assessment points to measured legal gaps, for which we evaluate the government authorities most appropriate to help fill these gaps. The analysis is conducted on United State federal statutes and regulations. Results show quantitative improvement of institutional fit over time (2006 to 2013), but a substantial number of measured legal gaps persist especially around acknowledging local sources of acidification and adaptation strategies to deal with or avoid impacts. We demonstrate the utility of this framework to evaluate the governance surrounding any emerging environmental threat as a first step to guiding the development of jurisdictionally realistic solutions.

  5. Acidification of the humic Lake Skjervatjern; effects on the volume and species composition of phytoplankton

    SciTech Connect

    Brettum, P. )

    1994-01-01

    This paper presents the effects of the experimental acidification on the volume and composition of phytoplankton from the investigations carried out in Lake Skjervatjern in connection with the HUMEX project. The results of the phytoplankton analysis are presented from Basin A, the acidified basin, and Basin B, the control, two years before the acidification started and two years during the acidification. In Basin B, the control basin, the succession of the main groups of phytoplankton throughout the growth season remained almost identical from year to year in the investigation period. The development of the phytoplankton was almost the same in the two basins before the acidification started. The results from the acidified Basin A in 1991 and 1992 show marked changes and an almost immediate response in the phytoplankton composition and percentage of the main algae groups, compared to the reference basin. The percentage of the green algae decreased, especially the species Oocystis submarina v. variabilis, while the dinoflagellate Peridinium inconspicuum and the cryptomonads increased in number and percentage of the total volume in the acidified basin. The total volume and the primary production measurements show an increase in Basin A compared to the control in the first year of acidification treatment (1991), but a decrease in the next year. 30 refs., 6 figs., 1 tab.

  6. Meta-analysis reveals negative yet variable effects of ocean acidification on marine organisms.

    PubMed

    Kroeker, Kristy J; Kordas, Rebecca L; Crim, Ryan N; Singh, Gerald G

    2010-11-01

    Ocean acidification is a pervasive stressor that could affect many marine organisms and cause profound ecological shifts. A variety of biological responses to ocean acidification have been measured across a range of taxa, but this information exists as case studies and has not been synthesized into meaningful comparisons amongst response variables and functional groups. We used meta-analytic techniques to explore the biological responses to ocean acidification, and found negative effects on survival, calcification, growth and reproduction. However, there was significant variation in the sensitivity of marine organisms. Calcifying organisms generally exhibited larger negative responses than non-calcifying organisms across numerous response variables, with the exception of crustaceans, which calcify but were not negatively affected. Calcification responses varied significantly amongst organisms using different mineral forms of calcium carbonate. Organisms using one of the more soluble forms of calcium carbonate (high-magnesium calcite) can be more resilient to ocean acidification than less soluble forms (calcite and aragonite). Additionally, there was variation in the sensitivities of different developmental stages, but this variation was dependent on the taxonomic group. Our analyses suggest that the biological effects of ocean acidification are generally large and negative, but the variation in sensitivity amongst organisms has important implications for ecosystem responses.

  7. Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

    NASA Astrophysics Data System (ADS)

    Mostofa, Khan M. G.; Liu, Cong-Qiang; Zhai, WeiDong; Minella, Marco; Vione, Davide; Gao, Kunshan; Minakata, Daisuke; Arakaki, Takemitsu; Yoshioka, Takahito; Hayakawa, Kazuhide; Konohira, Eiichi; Tanoue, Eiichiro; Akhand, Anirban; Chanda, Abhra; Wang, Baoli; Sakugawa, Hiroshi

    2016-03-01

    Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3-, and CO32-) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different timescales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

  8. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Best, M. H. P.; Neely, K.; Garley, R.; Dickson, A. G.; Johnson, R. J.

    2012-01-01

    Fossil fuel use, cement manufacture and land-use changes are the primary sources of anthropogenic carbon dioxide (CO2) to the atmosphere, with the ocean absorbing 30 %. Ocean uptake and chemical equilibration of anthropogenic CO2with seawater results in a gradual reduction in seawater pH and saturation states (Ω) for calcium carbonate (CaCO3) minerals in a process termed ocean acidification. Assessing the present and future impact of ocean acidification on marine ecosystems requires detection of the multi-decadal rate of change across ocean basins and at ocean time-series sites. Here, we show the longest continuous record of ocean CO2 changes and ocean acidification in the North Atlantic subtropical gyre near Bermuda from 1983-2011. Dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) increased in surface seawater by ~40 μmol kg-1 and ~50 μatm (~20 %), respectively. Increasing Revelle factor (β) values imply that the capacity of North Atlantic surface waters to absorb CO2 has also diminished. As indicators of ocean acidification, seawater pH decreased by ~0.05 (0.0017 yr-1) and Ω values by ~7-8 %. Such data provide critically needed multi-decadal information for assessing the North Atlantic Ocean CO2sink and the pH changes that determine marine ecosystem responses to ocean acidification.

  9. Detecting anthropogenic carbon dioxide uptake and ocean acidification in the North Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Best, M. H. P.; Neely, K.; Garley, R.; Dickson, A. G.; Johnson, R. J.

    2012-07-01

    Fossil fuel use, cement manufacture and land-use changes are the primary sources of anthropogenic carbon dioxide (CO2) to the atmosphere, with the ocean absorbing approximately 30% (Sabine et al., 2004). Ocean uptake and chemical equilibration of anthropogenic CO2 with seawater results in a gradual reduction in seawater pH and saturation states (Ω) for calcium carbonate (CaCO3) minerals in a process termed ocean acidification. Assessing the present and future impact of ocean acidification on marine ecosystems requires detection of the multi-decadal rate of change across ocean basins and at ocean time-series sites. Here, we show the longest continuous record of ocean CO2 changes and ocean acidification in the North Atlantic subtropical gyre near Bermuda from 1983-2011. Dissolved inorganic carbon (DIC) and partial pressure of CO2 (pCO2) increased in surface seawater by ~40 μmol kg-1 and ~50 μatm (~20%), respectively. Increasing Revelle factor (β) values imply that the capacity of North Atlantic surface waters to absorb CO2 has also diminished. As indicators of ocean acidification, seawater pH decreased by ~0.05 (0.0017 yr-1) and ω values by ~7-8%. Such data provide critically needed multi-decadal information for assessing the North Atlantic Ocean CO2 sink and the pH changes that determine marine ecosystem responses to ocean acidification.

  10. Reviews and Syntheses: Ocean acidification and its potential impacts on marine ecosystems

    NASA Astrophysics Data System (ADS)

    Mostofa, K. M. G.; Liu, C.-Q.; Zhai, W. D.; Minella, M.; Vione, D.; Gao, K.; Minakata, D.; Arakaki, T.; Yoshioka, T.; Hayakawa, K.; Konohira, E.; Tanoue, E.; Akhand, A.; Chanda, A.; Wang, B.; Sakugawa, H.

    2015-07-01

    Ocean acidification, a complex phenomenon that lowers seawater pH, is the net outcome of several contributions. They include the dissolution of increasing atmospheric CO2 that adds up with dissolved inorganic carbon (dissolved CO2, H2CO3, HCO3-, and CO32-) generated upon mineralization of primary producers (PP) and dissolved organic matter (DOM). The aquatic processes leading to inorganic carbon are substantially affected by increased DOM and nutrients via terrestrial runoff, acidic rainfall, increased PP and algal blooms, nitrification, denitrification, sulfate reduction, global warming (GW), and by atmospheric CO2 itself through enhanced photosynthesis. They are consecutively associated with enhanced ocean acidification, hypoxia in acidified deeper seawater, pathogens, algal toxins, oxidative stress by reactive oxygen species, and thermal stress caused by longer stratification periods as an effect of GW. We discuss the mechanistic insights into the aforementioned processes and pH changes, with particular focus on processes taking place with different time scales (including the diurnal one) in surface and subsurface seawater. This review also discusses these collective influences to assess their potential detrimental effects to marine organisms, and of ecosystem processes and services. Our review of the effects operating in synergy with ocean acidification will provide a broad insight into the potential impact of acidification itself on biological processes. The foreseen danger to marine organisms by acidification is in fact expected to be amplified by several concurrent and interacting phenomena.

  11. The reef-building coral Siderastrea siderea exhibits parabolic responses to ocean acidification and warming.

    PubMed

    Castillo, Karl D; Ries, Justin B; Bruno, John F; Westfield, Isaac T

    2014-12-22

    Anthropogenic increases in atmospheric CO2 over this century are predicted to cause global average surface ocean pH to decline by 0.1-0.3 pH units and sea surface temperature to increase by 1-4°C. We conducted controlled laboratory experiments to investigate the impacts of CO2-induced ocean acidification (pCO2 = 324, 477, 604, 2553 µatm) and warming (25, 28, 32°C) on the calcification rate of the zooxanthellate scleractinian coral Siderastrea siderea, a widespread, abundant and keystone reef-builder in the Caribbean Sea. We show that both acidification and warming cause a parabolic response in the calcification rate within this coral species. Moderate increases in pCO2 and warming, relative to near-present-day values, enhanced coral calcification, with calcification rates declining under the highest pCO2 and thermal conditions. Equivalent responses to acidification and warming were exhibited by colonies across reef zones and the parabolic nature of the corals' response to these stressors was evident across all three of the experiment's 30-day observational intervals. Furthermore, the warming projected by the Intergovernmental Panel on Climate Change for the end of the twenty-first century caused a fivefold decrease in the rate of coral calcification, while the acidification projected for the same interval had no statistically significant impact on the calcification rate-suggesting that ocean warming poses a more immediate threat than acidification for this important coral species.

  12. Biological mechanisms supporting adaptation to ocean acidification in coastal ecosystems

    NASA Astrophysics Data System (ADS)

    Hendriks, Iris E.; Duarte, Carlos M.; Olsen, Ylva S.; Steckbauer, Alexandra; Ramajo, Laura; Moore, Tommy S.; Trotter, Julie A.; McCulloch, Malcolm

    2015-01-01

    The direct influence of anthropogenic CO2 might play a limited role in pH regulation in coastal ecosystems as pH regulation in these areas can be complex. They experience large variability across a broad range of spatial and temporal scales, with complex external and internal drivers. Organisms influence pH at a patch scale, where community metabolic effects and hydrodynamic processes interact to produce broad ranges in pH, (∼0.3-0.5 pH units) over daily cycles and spatial scales (mm to m) particularly in shallow vegetated habitats and coral reefs where both respiration and photosynthetic activity are intense. Biological interactions at the ecosystem scale, linked to patchiness in habitat landscapes and seasonal changes in metabolic processes and temperature lead to changes of about 0.3-0.5 pH units throughout a year. Furthermore, on the scale of individual organisms, small-scale processes including changes at the Diffusive Boundary Layer (DBL), interactions with symbionts, and changes to the specific calcification environment, induce additional changes in excess of 0.5 pH units. In these highly variable pH environments calcifying organisms have developed the capacity to alter the pH of their calcifying environment, or specifically within critical tissues where calcification occurs, thus achieving a homeostasis. This capacity to control the conditions for calcification at the organism scale may therefore buffer the full impacts of ocean acidification on an organism scale, although this might be at a cost to the individual. Furthermore, in some areas, calcifiers may potentially benefit from changes to ambient seawater pH, where photosynthetic organisms drawdown CO2.

  13. Ocean acidification and calcifying reef organisms: A mesocosm investigation

    USGS Publications Warehouse

    Jokiel, P.L.; Rodgers, K.S.; Kuffner, I.B.; Andersson, A.J.; Cox, E.F.; MacKenzie, F.T.

    2008-01-01

    A long-term (10 months) controlled experiment was conducted to test the impact of increased partial pressure of carbon dioxide (pCO2) on common calcifying coral reef organisms. The experiment was conducted in replicate continuous flow coral reef mesocosms flushed with unfiltered sea water from Kaneohe Bay, Oahu, Hawaii. Mesocosms were located in full sunlight and experienced diurnal and seasonal fluctuations in temperature and sea water chemistry characteristic of the adjacent reef flat. Treatment mesocosms were manipulated to simulate an increase in pCO2 to levels expected in this century [midday pCO2 levels exceeding control mesocosms by 365 ?? 130 ??atm (mean ?? sd)]. Acidification had a profound impact on the development and growth of crustose coralline algae (CCA) populations. During the experiment, CCA developed 25% cover in the control mesocosms and only 4% in the acidified mesocosms, representing an 86% relative reduction. Free-living associations of CCA known as rhodoliths living in the control mesocosms grew at a rate of 0.6 g buoyant weight year-1 while those in the acidified experimental treatment decreased in weight at a rate of 0.9 g buoyant weight year-1, representing a 250% difference. CCA play an important role in the growth and stabilization of carbonate reefs, so future changes of this magnitude could greatly impact coral reefs throughout the world. Coral calcification decreased between 15% and 20% under acidified conditions. Linear extension decreased by 14% under acidified conditions in one experiment. Larvae of the coral Pocillopora damicornis were able to recruit under the acidified conditions. In addition, there was no significant difference in production of gametes by the coral Montipora capitata after 6 months of exposure to the treatments. ?? 2008 Springer-Verlag.

  14. Decadal acidification in the water masses of the Atlantic Ocean.

    PubMed

    Ríos, Aida F; Resplandy, Laure; García-Ibáñez, Maribel I; Fajar, Noelia M; Velo, Anton; Padin, Xose A; Wanninkhof, Rik; Steinfeldt, Reiner; Rosón, Gabriel; Pérez, Fiz F

    2015-08-11

    Global ocean acidification is caused primarily by the ocean's uptake of CO2 as a consequence of increasing atmospheric CO2 levels. We present observations of the oceanic decrease in pH at the basin scale (50 °S-36 °N) for the Atlantic Ocean over two decades (1993-2013). Changes in pH associated with the uptake of anthropogenic CO2 (ΔpHCant) and with variations caused by biological activity and ocean circulation (ΔpHNat) are evaluated for different water masses. Output from an Institut Pierre Simon Laplace climate model is used to place the results into a longer-term perspective and to elucidate the mechanisms responsible for pH change. The largest decreases in pH (∆pH) were observed in central, mode, and intermediate waters, with a maximum ΔpH value in South Atlantic Central Waters of -0.042 ± 0.003. The ΔpH trended toward zero in deep and bottom waters. Observations and model results show that pH changes generally are dominated by the anthropogenic component, which accounts for rates between -0.0015 and -0.0020/y in the central waters. The anthropogenic and natural components are of the same order of magnitude and reinforce one another in mode and intermediate waters over the time period. Large negative ΔpHNat values observed in mode and intermediate waters are driven primarily by changes in CO2 content and are consistent with (i) a poleward shift of the formation region during the positive phase of the Southern Annular Mode in the South Atlantic and (ii) an increase in the rate of the water mass formation in the North Atlantic.

  15. Ocean acidification-induced food quality deterioration constrains trophic transfer.

    PubMed

    Rossoll, Dennis; Bermúdez, Rafael; Hauss, Helena; Schulz, Kai G; Riebesell, Ulf; Sommer, Ulrich; Winder, Monika

    2012-01-01

    Our present understanding of ocean acidification (OA) impacts on marine organisms caused by rapidly rising atmospheric carbon dioxide (CO(2)) concentration is almost entirely limited to single species responses. OA consequences for food web interactions are, however, still unknown. Indirect OA effects can be expected for consumers by changing the nutritional quality of their prey. We used a laboratory experiment to test potential OA effects on algal fatty acid (FA) composition and resulting copepod growth. We show that elevated CO(2) significantly changed the FA concentration and composition of the diatom Thalassiosira pseudonana, which constrained growth and reproduction of the copepod Acartia tonsa. A significant decline in both total FAs (28.1 to 17.4 fg cell(-1)) and the ratio of long-chain polyunsaturated to saturated fatty acids (PUFA:SFA) of food algae cultured under elevated (750 µatm) compared to present day (380 µatm) pCO(2) was directly translated to copepods. The proportion of total essential FAs declined almost tenfold in copepods and the contribution of saturated fatty acids (SFAs) tripled at high CO(2). This rapid and reversible CO(2)-dependent shift in FA concentration and composition caused a decrease in both copepod somatic growth and egg production from 34 to 5 eggs female(-1) day(-1). Because the diatom-copepod link supports some of the most productive ecosystems in the world, our study demonstrates that OA can have far-reaching consequences for ocean food webs by changing the nutritional quality of essential macromolecules in primary producers that cascade up the food web.

  16. Sponge bioerosion accelerated by ocean acidification across species and latitudes?

    NASA Astrophysics Data System (ADS)

    Wisshak, M.; Schönberg, C. H. L.; Form, A.; Freiwald, A.

    2014-06-01

    In many marine biogeographic realms, bioeroding sponges dominate the internal bioerosion of calcareous substrates such as mollusc beds and coral reef framework. They biochemically dissolve part of the carbonate and liberate so-called sponge chips, a process that is expected to be facilitated and accelerated in a more acidic environment inherent to the present global change. The bioerosion capacity of the demosponge Cliona celata Grant, 1826 in subfossil oyster shells was assessed via alkalinity anomaly technique based on 4 days of experimental exposure to three different l