| 1. |
|
|
| 2. |
- Datry, T., et al.
(författare)
-
A global analysis of terrestrial plant litter dynamics in non-perennial waterways
- 2018
-
Ingår i: Nature Geoscience. - : Nature Publishing Group. - 1752-0894 .- 1752-0908. ; 11:7, s. 497-503
-
Tidskriftsartikel (refereegranskat)abstract
- Perennial rivers and streams make a disproportionate contribution to global carbon (C) cycling. However, the contribution of intermittent rivers and ephemeral streams (IRES), which sometimes cease to flow and can dry completely, is largely ignored although they represent over half the global river network. Substantial amounts of terrestrial plant litter (TPL) accumulate in dry riverbeds and, upon rewetting, this material can undergo rapid microbial processing. We present the results of a global research collaboration that collected and analysed TPL from 212 dry riverbeds across major environmental gradients and climate zones. We assessed litter decomposability by quantifying the litter carbon-to-nitrogen ratio and oxygen (O2) consumption in standardized assays and estimated the potential short-term CO2 emissions during rewetting events. Aridity, cover of riparian vegetation, channel width and dry-phase duration explained most variability in the quantity and decomposability of plant litter in IRES. Our estimates indicate that a single pulse of CO2 emission upon litter rewetting contributes up to 10% of the daily CO2 emission from perennial rivers and stream, particularly in temperate climates. This indicates that the contributions of IRES should be included in global C-cycling assessments.
|
|
| 3. |
- von Schiller, D., et al.
(författare)
-
Sediment Respiration Pulses in Intermittent Rivers and Ephemeral Streams
- 2019
-
Ingår i: Global Biogeochemical Cycles. - : American Geophysical Union (AGU). - 0886-6236 .- 1944-9224. ; 33:10, s. 1251-1263
-
Tidskriftsartikel (refereegranskat)abstract
- Intermittent rivers and ephemeral streams (IRES) may represent over half the global stream network, but their contribution to respiration and carbon dioxide (CO2) emissions is largely undetermined. In particular, little is known about the variability and drivers of respiration in IRES sediments upon rewetting, which could result in large pulses of CO2. We present a global study examining sediments from 200 dry IRES reaches spanning multiple biomes. Results from standardized assays show that mean respiration increased 32-fold to 66-fold upon sediment rewetting. Structural equation modeling indicates that this response was driven by sediment texture and organic matter quantity and quality, which, in turn, were influenced by climate, land use, and riparian plant cover. Our estimates suggest that respiration pulses resulting from rewetting of IRES sediments could contribute significantly to annual CO2 emissions from the global stream network, with a single respiration pulse potentially increasing emission by 0.2-0.7%. As the spatial and temporal extent of IRES increases globally, our results highlight the importance of recognizing the influence of wetting-drying cycles on respiration and CO2 emissions in stream networks.
|
|
| 4. |
- Bhattacharya, S. K., et al.
(författare)
-
5 year efficacy of a bivalent killed whole-cell oral cholera vaccine in Kolkata, India: A cluster-randomised, double-blind, placebo-controlled trial
- 2013
-
Ingår i: Lancet. Infectious Diseases. - 1473-3099 .- 1474-4457. ; 13:12, s. 1050-1056
-
Tidskriftsartikel (refereegranskat)abstract
- Background: Efficacy and safety of a two-dose regimen of bivalent killed whole-cell oral cholera vaccine (Shantha Biotechnics, Hyderabad, India) to 3 years is established, but long-term efficacy is not. We aimed to assess protective efficacy up to 5 years in a slum area of Kolkata, India. Methods: In our double-blind, cluster-randomised, placebo-controlled trial, we assessed incidence of cholera in non-pregnant individuals older than 1 year residing in 3933 dwellings (clusters) in Kolkata, India. We randomly allocated participants, by dwelling, to receive two oral doses of modified killed bivalent whole-cell cholera vaccine or heat-killed Escherichia coli K12 placebo, 14 days apart. Randomisation was done by use of a computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for patients to seek treatment in a health-care facility. We identified culture-confirmed cholera cases among participants seeking treatment for diarrhoea at a study clinic or government hospital between 14 days and 1825 days after receipt of the second dose. We assessed vaccine protection in a per-protocol population of participants who had completely ingested two doses of assigned study treatment. Findings: 69 of 31932 recipients of vaccine and 219 of 34968 recipients of placebo developed cholera during 5 year follow-up (incidence 2·2 per 1000 in the vaccine group and 6·3 per 1000 in the placebo group). Cumulative protective efficacy of the vaccine at 5 years was 65% (95% CI 52-74; p<0·0001), and point estimates by year of follow-up suggested no evidence of decline in protective efficacy. Interpretation: Sustained protection for 5 years at the level we reported has not been noted previously with other oral cholera vaccines. Established long-term efficacy of this vaccine could assist policy makers formulate rational vaccination strategies to reduce overall cholera burden in endemic settings. Funding: Bill & Melinda Gates Foundation and the governments of South Korea and Sweden. © 2013 Elsevier Ltd.
|
|
| 5. |
- Malnoë, Alizée, et al.
(författare)
-
The Plastid Lipocalin LCNP is Required for Sustained Photoprotective Energy Dissipation in Arabidopsis
- 2018
-
Ingår i: The Plant Cell. - : Oxford University Press. - 1040-4651 .- 1532-298X. ; 30:1, s. 196-208
-
Tidskriftsartikel (refereegranskat)abstract
- Light utilization is finely tuned in photosynthetic organisms to prevent cellular damage. The dissipation of excess absorbed light energy, a process termed NPQ, plays an important role in photoprotection. Little is known about the sustained or slowly reversible form(s) of NPQ and whether they are photoprotective, in part due to the lack of mutants. The Arabidopsis thaliana suppressor of quenching1 (soq1) mutant exhibits enhanced sustained NPQ, which we term qH. To identify molecular players involved in qH, we screened for suppressors of soq1 and isolated mutants affecting either chlorophyllide a oxygenase (CAO) or the chloroplastic lipocalin (CHL), now renamed plastid lipocalin (LCNP). Analysis of the mutants confirmed that qH is localized to the peripheral antenna (LHCII) of photosystem II and demonstrated that LCNP is required for qH, either directly (by forming NPQ sites) or indirectly (by modifying the LHCII membrane environment). qH operates under stress conditions such as cold and high light and is photoprotective, as it reduces lipid peroxidation levels. We propose that, under stress conditions, LCNP protects the thylakoid membrane by enabling sustained NPQ in LHCII, thereby preventing singlet oxygen stress.
|
|
| 6. |
- Sur, Dipika, et al.
(författare)
-
Efficacy and safety of a modified killed-whole-cell oral cholera vaccine in India: an interim analysis of a cluster-randomised, double-blind, placebo-controlled trial.
- 2009
-
Ingår i: Lancet. - 1474-547X. ; 374:9702, s. 1694-702
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Oral cholera vaccines consisting of killed whole cells have been available for many years, but they have not been used extensively in populations with endemic disease. An inexpensive, locally produced oral killed-whole-cell vaccine has been used in high-risk areas in Vietnam. To expand the use of this vaccine, it was modified to comply with WHO standards. We assessed the efficacy and safety of this modified vaccine in a population with endemic cholera. METHODS: In this double-blind trial, 107 774 non-pregnant residents of Kolkata, India, aged 1 year or older, were cluster-randomised by dwelling to receive two doses of either modified killed-whole-cell cholera vaccine (n=52 212; 1966 clusters) or heat-killed Escherichia coli K12 placebo (n=55 562; 1967 clusters), both delivered orally. Randomisation was done by computer-generated sequence in blocks of four. The primary endpoint was prevention of episodes of culture-confirmed Vibrio cholerae O1 diarrhoea severe enough for the patient to seek treatment in a health-care facility. We undertook an interim, per-protocol analysis at 2 years of follow-up that included individuals who received two completely ingested doses of vaccine or placebo. We assessed first episodes of cholera that occurred between 14 days and 730 days after receipt of the second dose. This study is registered with ClinicalTrials.gov, number NCT00289224. FINDINGS: 31 932 participants assigned to vaccine (1721 clusters) and 34 968 assigned to placebo (1757 clusters) received two doses of study treatment. There were 20 episodes of cholera in the vaccine group and 68 episodes in the placebo group (protective efficacy 67%; one-tailed 99% CI, lower bound 35%, p<0.0001). The vaccine protected individuals in age-groups 1.0-4.9 years, 5.0-14.9 years, and 15 years and older, and protective efficacy did not differ significantly between age-groups (p=0.28). We recorded no vaccine-related serious adverse events. INTERPRETATION: This modified killed-whole-cell oral vaccine, compliant with WHO standards, is safe, provides protection against clinically significant cholera in an endemic setting, and can be used in children aged 1.0-4.9 years, who are at highest risk of developing cholera in endemic settings. FUNDING: Bill & Melinda Gates Foundation, Swedish International Development Cooperation Agency, Governments of South Korea, Sweden, and Kuwait.
|
|
| 7. |
- Sylak-Glassman, E. J., et al.
(författare)
-
Distinct roles of the photosystem II protein PsbS and zeaxanthin in the regulation of light harvesting in plants revealed by fluorescence lifetime snapshots
- 2014
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 111:49, s. 17498-17503
-
Tidskriftsartikel (refereegranskat)abstract
- The photosystem II (PSII) protein PsbS and the enzyme violaxanthin deepoxidase (VDE) are known to influence the dynamics of energy-dependent quenching (qE), the component of nonphotochemical quenching (NPQ) that allows plants to respond to fast fluctuations in light intensity. Although the absence of PsbS and VDE has been shown to change the amount of quenching, there have not been any measurements that can detect whether the presence of these proteins alters the type of quenching that occurs. The chlorophyll fluorescence lifetime probes the excited-state chlorophyll relaxation dynamics and can be used to determine the amount of quenching as well as whether two different genotypes with the same amount of NPQ have similar dynamics of excited-state chlorophyll relaxation. We measured the fluorescence lifetimes on whole leaves of Arabidopsis thaliana throughout the induction and relaxation of NPQ for wild type and the qE mutants, npq4, which lacks PsbS; npq1, which lacks VDE and cannot convert violaxanthin to zeaxanthin; and npq1 npq4, which lacks both VDE and PsbS. These measurements show that although PsbS changes the amount of quenching and the rate at which quenching turns on, it does not affect the relaxation dynamics of excited chlorophyll during quenching. In addition, the data suggest that PsbS responds not only to DeltapH but also to the Deltapsi across the thylakoid membrane. In contrast, the presence of VDE, which is necessary for the accumulation of zeaxanthin, affects the excited-state chlorophyll relaxation dynamics.
|
|
