Photosynthetic organisms have the ability to adapt to changes in light quality by readjusting the cross sections of the lightharvesting systems of photosystem II (PSII) and photosystem I (PSI). This ...process, called state transitions, maintains the redox poise of the photosynthetic electron transfer chain and ensures a high photosynthetic yield when light is limiting. It is mediated by the Stt7/STN7 protein kinase, which is activated through the cytochrome b₆ f complex upon reduction of the plastoquinone pool. Its probable major substrate, the light-harvesting complex of PSII, once phosphorylated, dissociates from PSII and docks to PSI, thereby restoring the balance of absorbed light excitation energy between the two photosystems. Although the kinase is known to be inactivated under high-light intensities, the molecular mechanisms governing its regulation remain unknown. In this study we monitored the redox state of a conserved and essential Cys pair of the Stt7/STN7 kinase and show that it forms a disulfide bridge. We could not detect any change in the redox state of these Cys during state transitions and high-light treatment. It is only after prolonged anaerobiosis that this disulfide bridge is reduced. It is likely to be mainly intramolecular, although kinase activation may involve a transient covalently linked kinase dimer with two intermolecular disulfide bonds. Using the yeast two-hybrid system, we have mapped one interaction site of the kinase on the Rieske protein of the cytochrome b₆ f complex.
Summary
High‐temperature bioconversion of lignocellulose into fermentable sugars has drawn attention for efficient production of renewable chemicals and biofuels, because competing microbial ...activities are inhibited at elevated temperatures and thermostable cell wall degrading enzymes are superior to mesophilic enzymes. Here, we report on the development of a platform to produce four different thermostable cell wall degrading enzymes in the chloroplast of Chlamydomonas reinhardtii. The enzyme blend was composed of the cellobiohydrolase CBM3GH5 from C. saccharolyticus, the β‐glucosidase celB from P. furiosus, the endoglucanase B and the endoxylanase XynA from T. neapolitana. In addition, transplastomic microalgae were engineered for the expression of phosphite dehydrogenase D from Pseudomonas stutzeri, allowing for growth in non‐axenic media by selective phosphite nutrition. The cellulolytic blend composed of the glycoside hydrolase (GH) domain GH12/GH5/GH1 allowed the conversion of alkaline‐treated lignocellulose into glucose with efficiencies ranging from 14% to 17% upon 48h of reaction and an enzyme loading of 0.05% (w/w). Hydrolysates from treated cellulosic materials with extracts of transgenic microalgae boosted both the biogas production by methanogenic bacteria and the mixotrophic growth of the oleaginous microalga Chlorella vulgaris. Notably, microalgal treatment suppressed the detrimental effect of inhibitory by‐products released from the alkaline treatment of biomass, thus allowing for efficient assimilation of lignocellulose‐derived sugars by C. vulgaris under mixotrophic growth.
The N-terminal domain of the Stt7/STN7 protein kinase is essential for its activity and interacts directly with the Rieske protein of the cytochrome b
6
f complex.
Photosynthetic organisms have the ...ability to adapt to changes in light quality by readjusting the cross sections of the light-harvesting systems of photosystem II (
PSII
) and photosystem I (
PSI
). This process, called state transitions, maintains the redox poise of the photosynthetic electron transfer chain and ensures a high photosynthetic yield when light is limiting. It is mediated by the Stt7/STN7 protein kinase, which is activated through the cytochrome
b
6
f
complex upon reduction of the plastoquinone pool. Its probable major substrate, the light-harvesting complex of
PSII
, once phosphorylated, dissociates from
PSII
and docks to PSI, thereby restoring the balance of absorbed light excitation energy between the two photosystems. Although the kinase is known to be inactivated under high-light intensities, the molecular mechanisms governing its regulation remain unknown. In this study we monitored the redox state of a conserved and essential Cys pair of the Stt7/STN7 kinase and show that it forms a disulfide bridge. We could not detect any change in the redox state of these Cys during state transitions and high-light treatment. It is only after prolonged anaerobiosis that this disulfide bridge is reduced. It is likely to be mainly intramolecular, although kinase activation may involve a transient covalently linked kinase dimer with two intermolecular disulfide bonds. Using the yeast two-hybrid system, we have mapped one interaction site of the kinase on the Rieske protein of the cytochrome
b
6
f
complex.
To assess the pharmacological treatment and the control of major modifiable cardiovascular risk factors in everyday practice according to the patients' cardiovascular risk level.
In a cross-sectional ...study general practitioners (GPs) had to identify a random sample of their patients with cardiovascular risk factors or diseases and collect essential data on the pharmacological treatment and control of hypertension, hyperlipidemia, and diabetes according to the patients' cardiovascular risk level and history of cardiovascular disease. Participants were subjects of both sexes, aged 40-80 years, with at least one known cardiovascular risk factor or a history of cardiovascular diseases.
From June to December 2000, 162 Italian GPs enrolled 3120 of their patients (2470 hypertensives, 1373 hyperlipidemics, and 604 diabetics). Despite the positive association between the perceived level of global cardiovascular risk and lipid-lowering drug prescriptions in hyperlipidemic subjects (from 26% for lowest risk to 56% for highest risk p < 0.0001) or the prescription of combination therapy in hypertensives (from 41% to 70%, p < 0.0001) and diabetics (from 24% to 43%, p = 0.057), control was still inadequate in 48% of diabetics, 77% of hypertensives, and 85% of hyperlipidemics, with no increase in patients at highest risk. Trends for treatment and control were similar in patients with cardiovascular diseases.
Even in high-risk patients, despite a tendency towards more intensive treatment, pharmacological therapy is still under used and the degree of control of blood pressure, cholesterol level and diabetes is largely unsatisfactory.
In the recent years, the studies concerning the cultivation of
Neochloris oleoabundans
for biofuel purposes have increased, in relation to its capability to accumulate lipids when grown under ...nutrient starvation. Unfortunately, this cultivation mode does not allow to reach high biomass densities, which are required to improve the feasibility of the process. Increasing knowledge of the microalgal physiology is necessary to obtain new useful information for the improvement of culture performance in the perspective of large-scale cultivation. In this work, the mixotrophic cultivation of
N
.
oleoabundans
in a brackish medium added with different glucose concentrations has been tested under shaking, with the aim of stimulating growth alongside lipid accumulation inside cells. Cell morphology, glucose consumption, photosynthetic pigment content and photosynthetic efficiency were also investigated. Among all tested glucose concentrations (0–30 g L
−1
), it was observed that 2.5 g L
−1
was the optimal concentration, allowing to obtain the best compromise between glucose supplement, biomass production and lipid accumulation. Growth was highly enhanced in mixotrophic cultures, linked to the release of cells from sporocysts. A unique feature characterising mixotrophy in
N
.
oleoabundans
was the promotion of the maximum quantum yield of Photosystem II. Moreover, when mixotrophic cells entered the stationary phase, high lipid accumulation was induced. This study shows that the addition of glucose to
N
.
oleoabundans
remarkably increases the production of biomass enriched in lipids and represents an advancement for the cultivation of this microalga for applied purposes.
Differential phosphorylation of the Lhcb1 and Lhcb2 subunits of Light Harvesting Complex II plays contrasting roles in photosynthetic light acclimation and supercomplex assembly.
Light-harvesting ...complex II (LHCII) is a crucial component of the photosynthetic machinery, with central roles in light capture and acclimation to changing light. The association of an LHCII trimer with PSI in the PSI-LHCII supercomplex is strictly dependent on LHCII phosphorylation mediated by the kinase STATE TRANSITION7, and is directly related to the light acclimation process called state transitions. In Arabidopsis (
Arabidopsis thaliana
), the LHCII trimers contain isoforms that belong to three classes: Lhcb1, Lhcb2, and Lhcb3. Only Lhcb1 and Lhcb2 can be phosphorylated in the N-terminal region. Here, we present an improved Phos-tag-based method to determine the absolute extent of phosphorylation of Lhcb1 and Lhcb2. Both classes show very similar phosphorylation kinetics during state transition. Nevertheless, only Lhcb2 is extensively phosphorylated (>98%) in PSI-LHCII, whereas phosphorylated Lhcb1 is largely excluded from this supercomplex. Both isoforms are phosphorylated to different extents in other photosystem supercomplexes and in different domains of the thylakoid membranes. The data imply that, despite their high sequence similarity, differential phosphorylation of Lhcb1 and Lhcb2 plays contrasting roles in light acclimation of photosynthesis.
Haploidentical hematopoietic stem cell transplantation provides an option for patients with advanced hematologic malignancies lacking a compatible donor. In this prospective phase 1/2 trial, we ...evaluated the role of reduced-intensity conditioning (RIC) followed by early add-backs of CD8-depleted donor lymphocyte infusions (DLIs). The RIC regimen consisted of thiotepa, fludarabine, cyclophosphamide, and 2 Gy total body irradiation. Twenty-eight patients with advanced lymphoproliferative diseases (n = 24) or acute myeloid leukemia (n = 4) were enrolled. Ex vivo and in vivo T-cell depletion was carried out by CD34+ cell selection and alemtuzumab treatment. The 2-year cumulative incidence of nonrelapse mortality was 26% and the 2-year overall survival (OS) was 44%, with a better outcome for patients with chemosensitive disease (OS, 75%). Overall, 54 CD8-depleted DLIs were administered to 23 patients (82%) at 3 different dose levels without loss of engraftment or acute toxicities. Overall, 6 of 23 patients (26%) developed grade II-IV graft-versus-host disease, mainly at dose level 2. In conclusion, our RIC regimen allowed a stable engraftment with a rather low nonrelapse mortality in poor-risk patients; OS is encouraging with some long-term remissions in lymphoid malignancies. CD8-depleted DLIs are feasible and promote the immune reconstitution.
This work focuses on the development of a molecular tool for purification of Photosystem II (PSII) from Nicotiana tabacum (L.). To this end, the chloroplast psbB gene encoding the CP47 PSII subunit ...was replaced with an engineered version of the same gene containing a C-terminal His-tag. Molecular analyses assessed the effective integration of the recombinant gene and its expression. Despite not exhibiting any obvious phenotype, the transplastomic plants remained heteroplasmic even after three rounds of regeneration under antibiotic selection. However, the recombinant His-tagged CP47 protein associated in vivo to the other PSII subunits allowing the isolation of a functional PSII core complex, although with low yield of extraction. These results will open up possible perspectives for further spectroscopic and structural studies.
•Generation of tobacco transplastomic plants engineered to express His-tagged CP47.•Isolation of a functional PSII core complex from C-term His-tag CP47 mutants.•Applicability of a one-step purification method for structural-functional studies.
Although high cardiovascular risk patients should be the main target of preventive strategies, modifiable risk factors are often inadequately controlled.
To assess feasibility and results of a ...comprehensive personalized method for cardiovascular prevention in high risk patients followed by their general practitioner.
Between 2004 and 2007, 12,513 patients (mean age 64.0 ± 9.5 years; 61.5% males) with multiple cardiovascular risk factors or history of atherosclerotic disease were identified and followed for five years. If control of major modifiable cardiovascular risk factors (hypertension, hypercholesterolaemia, diabetes, obesity, smoking, unhealthy diet, physical inactivity) was sub-optimal, at baseline and yearly thereafter general practitioners planned with patients, with the help of a brief checklist, preventive interventions to improve the global risk profile. Main outcome was the control of the seven major modifiable cardiovascular risk factors during follow-up. Secondary outcome was the incidence of cardiovascular deaths and hospitalization for cardiovascular reasons according to the improvement in global cardiovascular risk profile during the first year.
Control of all major modifiable risk factors except physical inactivity improved gradually and significantly (p < 0.0001) during follow-up.The improvement in the global cardiovascular risk profile during the first year was independently and significantly associated with a lower rate of major cardiovascular events in the following years (hazard ratio 0.939; 95% confidence interval 0.887-0.994, p = 0.03).
Our comprehensive, personalized method for cardiovascular risk prevention in people at high risk appears feasible in general practice. The improvement in the global cardiovascular risk profile was associated with a better prognosis.
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