σ‐Lewis base‐catalyzed regio‐ and enantioselective aza‐Morita–Baylis–Hillman (MBH) reaction of α,β,γ,δ‐unsaturated systems remains a challenge due to the intrinsic covalent activation mode. Here we ...demonstrate that a Pd0 complex can mediate the dehydrogenative reaction of γ,δ‐unsaturated compounds to give corresponding electron‐poor dienes, which further undergo δ‐regioselective umpolung Friedel–Crafts‐type addition to imines via auto‐tandem Pd0‐π‐Lewis base catalysis. After β‐H elimination of in situ formed PdII‐complexes, unprecedented and chemically inverse aza‐MBH‐type adducts are finally furnished with fair to outstanding enantioselectivity, and a diversity of functional groups and both ketimine and aldimine acceptors can be well tolerated. Moreover, switchable α‐regioselective normal aza‐MBH‐type reaction also can be realized by tuning catalytic conditions, whereas moderate to good enantioselectivity with low to excellent Z/E‐selectivity is attained.
A Pd0 complex can mediate dehydrogenative formation of 2,4‐diene systems from γ,δ‐unsaturated carbonyls in the presence of 2,6‐DMBQ (2,6‐dimethyl‐1,4‐benzoquinone), which undergo vinylogous addition to imines via auto‐tandem Pd0‐π‐Lewis base catalysis. Both chemically inverse δ‐regioselective aza‐Morita–Baylis–Hillman adducts and α‐regioselective normal ones are obtained switchably and stereoselectively by tuning catalytic conditions.
Moderate heat stress and fluctuating light are typical conditions in summer in tropical and subtropical regions. This type of stress can cause photodamage to photosystems I and II (PSI and PSII). ...However, photosynthetic responses to the combination of heat and fluctuating light in young leaves are little known. In this study, we investigated chlorophyll fluorescence and P700 redox state under fluctuating light at 25 °C and 42 °C in young leaves of tobacco. Our results indicated that fluctuating light caused selective photodamage to PSI in the young leaves at 25 °C and 42 °C. Furthermore, the moderate heat stress significantly accelerated photoinhibition of PSI under fluctuating light. Within the first 10 s after transition from low to high light, cyclic electron flow (CEF) around PSI was highly stimulated at 25 °C but was slightly activated at 42 °C. Such depression of CEF activation at moderate heat stress were unable to maintain energy balance under high light. As a result, electron flow from PSI to NADP
+
was restricted, leading to the over-reduction of PSI electron carriers. These results indicated that moderate heat stress altered the CEF performance under fluctuating light and thus accelerated PSI photoinhibition in tobacco young leaves.
Demand side management (DSM) is one of the important functions in a smart grid that allows customers to make informed decisions regarding their energy consumption, and helps the energy providers ...reduce the peak load demand and reshape the load profile. This results in increased sustainability of the smart grid, as well as reduced overall operational cost and carbon emission levels. Most of the existing demand side management strategies used in traditional energy management systems employ system specific techniques and algorithms. In addition, the existing strategies handle only a limited number of controllable loads of limited types. This paper presents a demand side management strategy based on load shifting technique for demand side management of future smart grids with a large number of devices of several types. The day-ahead load shifting technique proposed in this paper is mathematically formulated as a minimization problem. A heuristic-based Evolutionary Algorithm (EA) that easily adapts heuristics in the problem was developed for solving this minimization problem. Simulations were carried out on a smart grid which contains a variety of loads in three service areas, one with residential customers, another with commercial customers, and the third one with industrial customers. The simulation results show that the proposed demand side management strategy achieves substantial savings, while reducing the peak load demand of the smart grid.
•We compared photosynthetic regulation in tobacco grown at different light regimes.•HL-plants down-regulate ΔpH to increase light use efficiency by enhancing gH+.•LL-plants decrease gH+ to ...up-regulate ΔpH and to favor photoprotection.•CEF mainly contributes to ATP synthesis in HL-plants but favors ΔpH in LL-plants.•The relationship between ΔpH and photoprotection is altered by primary metabolism.
In this study, we have compared photosynthetic regulation in tobacco leaves (Nicotiana tabacum L.) grown under high light (HL) and low light (LL) by measuring chlorophyll fluorescence, P700 redox state and electrochromic shift signals. Under high light, HL-plants had much higher linear electron flow and cyclic electron flow (CEF) around photosystem I (PSI) than LL-plants. Meanwhile, HL-plants showed significantly lower proton gradient (ΔpH) across the thylakoid membranes, owing to the increased activity of chloroplast ATP synthase. The relationships between ΔpH, non-photochemical quenching (NPQ) and PSI donor side limitation Y(ND) differed between HL- and LL-plants. At a given ΔpH, HL-plants displayed higher NPQ and Y(ND). Furthermore, at a given CEF, LL-plants showed higher ΔpH and Y(ND). These results indicate that HL-plants down-regulate ΔpH to increase light use efficiency by enhancing the activity of chloroplast ATP synthase. In contrast, LL-plants decrease the activity of chloroplast ATP synthase to up-regulate ΔpH and to favor photoprotection. Our findings suggest that the coordination of CEF and chloroplast ATP synthase balances light use efficiency and photoprotection at different growth light conditions.
•We examine photosynthetic performance in FL at 25 °C and 4 °C in D. offocinale.•A rapid re-oxidation of P700 is observed at 25 °C but disappears at 4 °C.•The water-water cycle regulates PSI redox ...state in FL at 25 °C in D. offocinale.•The water-water cycle is not a major alternative electron flow in FL at 4 °C.•Regulation of PSI redox state by WWC is dependent on temperature.
The water-water cycle (WWC) has the potential to alleviate photoinhibition of photosystem I (PSI) in fluctuating light (FL) at room temperature and moderate heat stress. However, it is unclear whether WWC can function as a safety valve for PSI in FL at chilling temperature. In this study, we measured P700 redox state and chlorophyll fluorescence in FL at 25 °C and 4 °C in the high WWC activity plant Dendrobium officinale. At 25 °C, the operation of WWC contributed to the rapid re-oxidation of P700 upon dark-to-light transition. However, such rapid re-oxidation of P700 was not observed at 4 °C. Upon a sudden increase in light intensity, WWC rapidly consumed excess electrons in PSI and thus avoided an over-reduction of PSI at 25 °C. On the contrary, PSI was highly reduced within the first seconds after transition from low to high light at 4 °C. Therefore, in opposite to 25 °C, the WWC is not a major alternative sink in FL at chilling temperature. Upon transition from low to high light, cyclic electron transport was highly stimulated at 4 °C when compared with 25 °C. These results indicate that D. officinale enhances cyclic electron transport to partially compensate for the inactivation of WWC in FL at 4 °C.
Abstract
Mining minerals plays a fundamental role in promoting social-economic progress. Intensive mining operations. However, it also brings huge ecological risks, and may lead to significant ...changes in land use/land cover (LULC), further affecting the urban landscape and ecological environment. Based on changes in LULC from 2000 to 2020 in the Jiawang district, a resource-based city, this study uses an ecological risk assessment as the theoretical basis for evaluating regional landscape ecological risk. The results show that: (1) From 2000 to 2020 significant changes in LULC were the increase the areas of built-up land and those covered with water, and decreases occurred in the cultivated, industrial, and mining land areas. The conversion of industrial and mining lands to areas of water is a noteworthy ecological compensation area. (2) Over the past two decades, the average ecological risk in the study area was 0.19, 0.21, and 0.14, in 2000, 2010 and 2020, respectively, first increasing and then decreasing. The area ratio of the lowest-risk ecological risk areas dropped from 31.60% to 4.00%. (3) The global Moran's I values in 2000, 2010, and 2020 were 0.6047, 0.6280, and 0.6392, respectively. The positive values indicate that the autocorrelation and spatial aggregation of ecological risks in Jiawang district gradually increased. This study can provide a basis for other resource-based cities to rationally allocate land resources and manage urban ecological risks.
•Photosynthetic responses to heat and fluctuating light were investigated in tobacco.•Heat induces the stimulation of CEF in high light phases under fluctuating light.•The stimulation of CEF ...facilitates the electron sink via photorespiration.•Photoinhibition under fluctuating light was unaffected by moderate heat stress.•Coordination of CEF and photorespiration favors photoprotection under heat stress.
Moderate heat stress is usually accompanied with fluctuating light in summer. Although either heat stress or fluctuating light can cause photoinhibition of photosystems I and II (PSI and PSII), it is unclear whether moderate heat stress accelerate photoinhibition under fluctuating light. Here, we measured chlorophyll fluorescence, P700 redox state and the electrochromic shift signal under fluctuating light at 25 °C and 42 °C for tobacco leaves. We found that (1) the thylakoid proton conductance was significantly enhanced at 42 °C, leading to a decline in trans-thylakoid proton gradient (ΔpH); (2) this low ΔpH at 42 °C did not decrease donor-side limitation of PSI and thermal energy dissipation in PSII; (3) the activation of cyclic electron flow (CEF) around PSI was elevated at 42 °C; and (4) the moderate heat stress did not accelerate photoinhibition of PSI and PSII under fluctuating light. These results strongly indicate that under moderate heat stress the stimulation of CEF protects PSI under fluctuating light in tobacco leaves.
Summary Plants rely on solar energy to synthesize ATP and NADPH for photosynthetic carbon fixation and all cellular need. Mitochondrial respiration is essential in plants, but this may be due to ...heterotrophic bottlenecks during plant development or because it is also necessary in photosynthetically active cells. In this study, we examined in vivo changes of cytosolic ATP concentration in response to light, employing a biosensing strategy in the moss Physcomitrium patens and revealing increased cytosolic ATP concentration caused by photosynthetic activity. Plants depleted of respiratory Complex I showed decreased cytosolic ATP accumulation, highlighting a critical role of mitochondrial respiration in light‐dependent ATP supply of the cytosol. Consistently, targeting mitochondrial ATP production directly, through the construction of mutants deficient in mitochondrial ATPase (complex V), led to drastic growth reduction, despite only minor alterations in photosynthetic electron transport activity. Since P. patens is photoautotrophic throughout its development, we conclude that heterotrophic bottlenecks cannot account for the indispensable role of mitochondrial respiration in plants. Instead, our results support that mitochondrial respiration is essential for ATP provision to the cytosol in photosynthesizing cells. Mitochondrial respiration provides metabolic integration, ensuring supply of cytosolic ATP essential for supporting plant growth and development.
We provide the first multi‐locus molecular phylogeny of the lichen moth genus Barsine Walker and related genera, focussing on the recently revised Ammatho Walker and Ovipennis Hampson. One ...mitochondrial (cytochromec oxidase subunit I) and three nuclear (EF‐1α, RpS5 and Wg) genes were sequenced for 114 taxa representing most of the known members from these genera, sourced mainly from continental East Asia. Phylogenetic topologies obtained from maximum likelihood and Bayesian inference were generally congruent. Based on these results, we propose the four genus‐groups: the Melanaema, Asuridia, Miltochrista and Asura groups. The following genera are described: Longarsine gen.n., Callidarsine gen.n., Fangclia gen.n. and Micrarsine gen.n. The following subgenera are raised to genera: Ammathella stat.n., Striatella stat.n., Conicornuta stat.n., Delineatia stat.n., Composine stat.n., Barsipennis stat.n., Coccinigripennis stat.n. and Processine stat.n. The following genera and combinations are restored: Idopterum stat.rev., Nebulene stat.rev. and Ovipennis postalba comb.rev. The genus Hampsonascia is synonymized with Sesapa (Sesapa).
First multi‐locus molecular phylogeny of the lichen moth genus Barsine Walker and other related genera, focusing especially on the recently revised Ammatho Walker and Ovipennis Hampson.
Subdivide these genera into four genus‐groups: the Melanaema, Asuridia, Miltochrista and Asura groups.
Primarily elucidated the polyphyly of Ammatho Walker and Ovipennis Hampson with description of new genera, upgrading of subgenera, restoring of genera and specific combination.
•D. officinale shows a rapid oxidation of P700 upon dark-to-light transition.•D. officinale shows a rapid oxidation of PSI upon an increase in illumination.•Water-water cycle leads to the rapid ...oxidation of PSI in D. officinale.•WWC is more effective in protecting PSI under fluctuating light than CET.•Sensitivity of PSI to fluctuating light can be altered by WWC activity.
Fluctuating light can cause selective photoinhibition of photosystem I (PSI) in angiosperms. However, the strategies for photosynthetic regulation under fluctuating light in wild epiphytic plants are little known. We here compared PSI and PSII performances under fluctuating light in the epiphytic orchid Dendrobium officinale and the terrestrial orchid Bletilla striata. Upon dark-to-light transition, D. officinale showed a rapid re-oxidation of P700, but this rapid re-oxidation of P700 was not observed in B. striata. Within the first 40 s after transition from dark to actinic light, B. striata showed much higher activation of cyclic electron transport (CET) than D. officinale. However, this strong activation of CET could not prevent the over-reduction of PSI. Therefore, the rapid re-oxidation of P700 in D. officinale was attributed to pseudo-cyclic electron transport (water-water cycle). Within the first 60 s after transition from low to high light, PSI was highly oxidized in D. officinale but was highly reduced in B. striata. Concomitantly, B. striata showed much higher stimulation of CET. These results indicate that water-water cycle significantly regulates PSI redox state under fluctuating light in the epiphytic orchid D. officinale. By comparison, the terrestrial orchid B. striata employs CET to cope with fluctuating light, similar to the phenotype of Arabidopsis thaliana. Taking together, these two orchids used different strategies for photosynthetic regulation to cope with fluctuating light.
