Hydrolysis of phospholipid monolayers by phospholipase A2 revealed by heterodyne-detected sum frequency generation (HD-SFG) spectroscopy.

Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 acyl ester linkage in phospholipid, producing lysophospholipid and fatty acid in the presence of Ca2+. The hydrolysis mediated by PLA2 has attracted much interest in various fields, such as pharmacy and biotechnology. It is recognized that PLA2 cannot hydrolyze phospholipid monolayers at high surface coverage. However, the origin of different PLA2 activities is not fully understood yet. The present study investigated the interaction between DPPC (16:0 PC) monolayer and PLA2 using heterodyne-detected sum frequency generation spectroscopy, which is interface-specific spectroscopy and highly sensitive to molecular symmetry based on a second-order nonlinear optical process. It was revealed that PLA2 adsorbs to the DPPC monolayer on the aqueous solution surface only when the surface coverage is low. The adsorption at the low surface coverage significantly changes the interfacial structures of PLA2 and the hydration, which are stabilized by the presence of Ca2+. Therefore, the restriction of the hydrolysis of phospholipid monolayers at high surface coverage can be rationalized by the inhabitation of the PLA2 adsorption. The present study deepens our molecular-level understanding of the hydrolysis of phospholipids by PLA2.

Habitat for Coilia nasus in southern Zhejiang Province, China, based on a maximum entropy model.

As an important fishery resource and endangered species, studying the habitat of Coilia nasus (C. nasus) is highly significant. This study used fishery survey data from southern Zhejiang coastal waters from 2016 to 2020, employing a maximum entropy model (MaxEnt) to map the habitat distribution of C. nasus. Model performance was evaluated using two metrics: the area under the curve (AUC) of the receiver operating characteristic curve for the training and test sets and true skill statistics (TSS). This study aimed to predict the habitat distribution of C. nasus and explore how environmental variables influence habitat suitability. The results indicated that the models for each season had strong predictive performance, with AUC values above 0.8 and TSS values exceeding 0.6, indicating that they could accurately predict the presence of C. nasus. In the study area, C. nasus was primarily found in brackish or marine waters near bays and coastal islands. Among all environmental factors, salinity (S) and bottom temperature (BOT) had the highest correlations with habitat distribution, although these correlations varied across seasons. The findings of this study provide empirical evidence and a reference for the conservation and management of C. nasus and for the designation of its protected areas.

Access to the Antenna System of Photosystem I via Single-Molecule Excitation-Emission Spectroscopy.

In the development of single-molecule spectroscopy, the simultaneous detection of the excitation and emission spectra has been limited. The fluorescence excitation spectrum based on background-free signals is compatible with the fluorescence-emission-based detection of single molecules and can provide insight into the variations in the input energy of the different terminal emitters. Here, we implement single-molecule excitation-emission spectroscopy (SMEES) for photosystem I (PSI) via a cryogenic optical microscope. To this end, we extended our line-focus-based excitation-spectral microscope system to the cryogenic temperature-compatible version. PSI is one of the two photosystems embedded in the thylakoid membrane in oxygen-free photosynthetic organisms. PSI plays an essential role in electron transfer in the photosynthesis reaction. PSIs of many organisms contain a few red-shifted chlorophylls (Chls) with much lower excitation energies than ordinary antenna Chls. The fluorescence emission spectrum originates primarily from the red-shifted Chls, whereas the excitation spectrum is sensitive to the antenna Chls that are upstream of red-shifted Chls. Using SMEES, we obtained the inclining two-dimensional excitation-emission matrix (2D-EEM) of PSI particles isolated from a cyanobacterium, Thermosynechococcus vestitus (equivalent to elongatus), at about 80 K. Interestingly, by decomposing the inclining 2D-EEMs within time course observation, we found prominent variations in the excitation spectra of the red-shifted Chl pools with different emission wavelengths, strongly indicating the variable excitation energy transfer (EET) pathway from the antenna to the terminal emitting pools. SMEES helps us to directly gain information about the antenna system, which is fundamental to depicting the EET within pigment-protein complexes.

Identifying topology of distribution substation in power Internet of Things using dynamic voltage load fluctuation flow analysis.

At present, the reconfiguration, maintenance, and review of power lines play a pivotal role in maintaining the stability of electrical grid operations and ensuring the accuracy of electrical energy measurements. These essential tasks not only guarantee the uninterrupted functioning of the power system, thereby improving the reliability of the electricity supply but also facilitate precise electricity consumption measurement. In view of these considerations, this article endeavors to address the challenges posed by power line restructuring, maintenance, and inspections on the stability of power grid operations and the accuracy of energy metering. To accomplish this goal, this article introduces an enhanced methodology based on the hidden Markov model (HMM) for identifying the topology of distribution substations. This approach involves a thorough analysis of the characteristic topology structures found in low-voltage distribution network (LVDN) substations. A topology identification model is also developed for LVDN substations by leveraging time series data of electricity consumption measurements and adhering to the principles of energy conservation. The HMM is employed to streamline the dimensionality of the electricity consumption data matrix, thereby transforming the topology identification challenge of LVDN substations into a solvable convex optimization problem. Experimental results substantiate the effectiveness of the proposed model, with convergence to minimal error achieved after a mere 50 iterations for long time series data. Notably, the method attains an impressive discriminative accuracy of 0.9 while incurring only a modest increase in computational time, requiring a mere 35.1 milliseconds. By comparison, the full-day data analysis method exhibits the shortest computational time at 16.1 milliseconds but falls short of achieving the desired accuracy level of 0.9. Meanwhile, the sliding time window analysis method achieves the highest accuracy of 0.95 but at the cost of a 50-fold increase in computational time compared to the proposed method. Furthermore, the algorithm reported here excels in terms of energy efficiency (0.89) and load balancing (0.85). In summary, the proposed methodology outperforms alternative approaches across a spectrum of performance metrics. This article delivers valuable insights to the industry by fortifying the stability of power grid operations and elevating the precision of energy metering. The proposed approach serves as an effective solution to the challenges entailed by power line restructuring, maintenance, and inspections.

Ticagrelor alleviates pyroptosis of myocardial ischemia reperfusion-induced acute lung injury in rats: a preliminary study.

Pulmonary infection is highly prevalent in patients with acute myocardial infarction undergoing percutaneous coronary intervention. However, the potential mechanism is not well characterized. Myocardial ischemia-reperfusion injury (MIRI) induces acute lung injury (ALI) related to pulmonary infection and inflammation. Recent studies have shown that pyroptosis mediates ALI in several human respiratory diseases. It is not known whether MIRI induces pyroptosis in the lungs. Furthermore, ticagrelor is a clinically approved anti-platelet drug that reduces ALI and inhibits the expression levels of several pyroptosis-associated proteins, but the effects of ticagrelor on MIRI-induced ALI have not been reported. Therefore, we investigated whether ticagrelor alleviated ALI in the rat MIRI model, and its effects on pyroptosis in the lungs. Sprague-Dawley rats were randomly divided into four groups: control, MIRI, MIRI plus low ticagrelor (30 mg/kg), and MIRI plus high ticagrelor (100 mg/kg). Hematoxylin and Eosin (HE) staining was performed on the lung sections, and the HE scores were calculated to determine the extent of lung pathology. The wet-to-dry ratio of the lung tissues were also determined. The expression levels of pyroptosis-related proteins such as NLRP3, ASC, and Cleaved caspase-1 were estimated in the lung tissues using the western blot. ELISA was used to estimate the IL-1ß levels in the lungs. Immunohistochemistry was performed to determine the levels of MPO-positive neutrophils as well as the total NLRP3-positive and Cleaved caspase-1-positive areas in the lung tissues. The lung tissues from the MIRI group rats showed significantly higher HE score, wet-to-dry ratio, and the MPO-positive area compared to the control group, but these effects were attenuated by pre-treatment with ticagrelor. Furthermore, lung tissues of the MIRI group rats showed significantly higher expression levels of pyroptosis-associated proteins, including NLRP3 (2.1-fold, P < 0.05), ASC (3.0-fold, P < 0.01), and Cleaved caspase-1 (9.0-fold, P < 0.01). Pre-treatment with the high-dose of ticagrelor suppressed MIRI-induced upregulation of NLRP3 (0.46-fold, P < 0.05), ASC (0.64-fold, P < 0.01), and Cleaved caspase-1 (0.80-fold, P < 0.01). Immunohistochemistry results also confirmed that pre-treatment with ticagrelor suppressed MIRI-induced upregulation of pyroptosis in the lungs. In summary, our data demonstrated that MIRI induced ALI and upregulated pyroptosis in the rat lung tissues. Pre-treatment with ticagrelor attenuated these effects.

Unraveling the solvent stability on the cathode surface of Li-O2 batteries by using in situ vibrational spectroscopies.

In aprotic lithium-oxygen (Li-O2) batteries, solvent properties are crucial in the charge/discharge processes. Therefore, a thorough understanding of the solvent stability at the cathode surface during the oxygen reduction/evolution reactions (ORR/OER) is essential for the rational design of high-performance electrolytes. In this study, the stability of typical solvents, a series of glyme solvents with different chain lengths, has been investigated during the ORR/OER by in situ vibrational spectroscopy measurements of sum frequency generation (SFG) spectroscopy and infrared reflection absorption spectroscopy (IRRAS). The structural evolution and decomposition mechanism of the solvents during ORR/OER have been discussed based on the observations. Our results demonstrate that superoxide (O2-) generated during the ORR plays a critical role in the stability of the solvents.

[Community Composition, Symbiotic Patterns, and Influencing Factors of Planktonic Fungi in Urban Lakes of Nanchang].

To investigate the characteristics of planktonic fungal communities in Nanchang lakes and the mechanism of environmental stress on planktonic fungal communities, surface water samples were collected from seven major urban lakes evenly distributed in different county-level districts of Nanchang in the dry (February and December), normal (April and October), and wet (June and August) seasons, respectively. The environmental stressors such as WT, DO, NH4+-N, and NO3--N were measured; the characteristics of planktonic fungal communities were studied using high-throughput sequencing; the symbiotic patterns of planktonic fungal communities were elucidated using network analysis and other methods; and the environmental stressors affecting the structure and symbiotic patterns of planktonic fungal communities were revealed. The results showed that ① the planktonic fungal community composition in lakes of Nanchang varied significantly among seasons but not significantly among the lakes. WT, DO, pH, and NH4+-N were the significant environmental stressors affecting the planktonic fungal community composition. ② The dominant phyla of the planktonic fungal community were Chytridiomycota (9.55%-33.14%), Basidiomycota (0.48%-4.25%), and Ascomycota (1.29%-3.19%), and the sizes of the dominant phyla were in the following order:wet season>normal season>dry season. The relative abundance of Chytridiomycota was significantly higher in the wet season than that in the normal season and the dry season, the relative abundance of Basidiomycota was significantly lower in the dry season than that in the normal and wet seasons, and the difference in Ascomycota among seasons was not significant. ③ The stability size of the planktonic fungal community symbiosis network in lakes of Nanchang was in the following order:wet season>normal season>dry season. WT was the best environmental stressor affecting the planktonic fungal community symbiosis pattern. The study can provide theoretical basis for the comprehensive evaluation and management study of the lake and provide guidance for protecting the lake ecosystem in the middle and lower reaches of the Yangtze River.

Estimation of life history traits and stock status for Scomber japonicus based on data-limited method.

The age-structure data is usually unavailable for most traditional fishery species in the East China Sea. The data-limited method is thus particularly important to understand life history and population dynamics of commercial fishes. At the offshore waters of southern Zhejiang, Chub mackerel (Scomber japonicus) is one of the dominant economic species. Based on fork length data from 2016 to 2020, we estimated its life history traits with the data-limited method, including the growth parameters and mortality coefficients. We further evaluated the status of Chub mackerel by the yield per recruitment (YPR) model. The results showed that the relationship between fork length (L) and body weight (W) based on 1606 samples was estimated to be W=4.18×10-3L3.28(R2=0.96). The asymptotic fork length L∞ of Chub mackerel was 28.34 cm, the growth rate was 0.36 a-1, and the initial theoretical age was -0.40 a. The total mortality was estimated as 1.67 a-1, and the estimated natural mortality (M) was 0.85 a-1. The fishing mortality (F) was 0.82 a-1, and the development rate was 0.49. The current capture age was estimated to be 1.78 a, while the capture fork length was 15.44 cm. The YPR model results showed YPR value showed a trend of increasing and then decreasing with the increases of F. The values of biological reference points F0.1 and Fmax were 0.97 a-1 and 4.55 a-1, respectively, which were higher than the value of current F. The sensitivity analysis showed that the uncertainty of M greatly influenced the estimation results of YPR and biological reference points. A decrease in M significantly increased the YPR value, but F0.1 and Fmax decreased. The status of Chub mackerel stock at the offshore waters of southern Zhejiang is in good condition. However, the miniaturization of catch is intensifying. It is recommended to extend the capture fork length to 20 cm (the impact point age) to improve the quality of the catch, which would sustainably use the Chub mackerel resources.

Application of high-throughput sequencing to analyze the diet of black croaker (Atrobucca nibe) in southern coastal waters of Zhejiang.

This study investigated the feeding habits of black croaker (Atrobucca nibe) to fully understand its role in the food web in southern coastal waters of Zhejiang, China. In total, 225 black croakers were collected in a bottom trawl survey, of which 195 were used for the stomach contents analysis and 30 for high-throughput sequencing (HTS). Both approaches showed that the main prey was shrimp, with Alpheus japonicus being the most predominant. In addition, black croaker also fed on other benthic species, suggesting that it was a demersal predator. Feeding intensity also varied with black croaker body length, as did prey preference, from small-sized species to larger species with increases in fish size; in addition, prey species were more diverse in the large-bodied prey group. Canonical correspondence analysis indicated that the feeding habit of black croaker was most significantly correlated with temperature and dissolved oxygen. HTS was shown to be a feasible high precision semi-quantitative analytical approach, although it must be combined with morphological methods to obtain more complete feeding data; thus, it could provide an effective scientific basis for feeding ecology studies of marine organisms.

Development of Line-Detected UV-Vis Absorption Microscope and Its Application to Quantitative Evaluation of Lithium Surface Reactivity.

Electrochemical reactions in practical batteries occur in confined environments where anode and cathode electrodes are separated only by a thin separator. Therefore, their electrochemical behaviors may differ from those obtained in the conventional experimental cells, where the two electrodes (working and counter electrodes) are largely separated compared to the batteries. The spatial and temporal distributions of the chemical species in the vicinity of each electrode are highly expected to be determined for quantitatively understanding the phenomena in confined environments. In the present study, we developed a line-detected UV-vis absorption microscope that simultaneously measures space-resolved UV-vis absorption spectra. This novel technique has been successfully applied to evaluate the reactivities of the highly reactive lithium (Li) surfaces in organic electrolyte solutions under in situ conditions. The quantitative evaluations of the dissolution rate of Li and the diffusion constant of the product were successfully realized by analyzing the space- and time-resolved absorption spectra based on Fick's law of diffusion. The microscopic technique is expected to open the door to understanding the fundamental electrochemistry in batteries.

Comparative effectiveness of prophylactic strategies for preeclampsia: a network meta-analysis of randomized controlled trials.

OBJECTIVE: Preeclampsia is a common disease during pregnancy that leads to fetal and maternal adverse events. Few head-to-head clinical trials are currently comparing the effectiveness of prophylactic strategies for preeclampsia. In this network meta-analysis, we aimed to compare the efficacy of prophylactic strategies for preventing preeclampsia in pregnant women at risk. DATA SOURCES: Articles published in or before September 2021 from PubMed, Embase, Web of Science, Cochrane Library, and ClinicalTrials.gov, references of key articles, and previous meta-analyses were manually searched. STUDY ELIGIBILITY CRITERIA: Randomized controlled trials comparing prophylactic strategies preventing preeclampsia with each other or with negative controls were included. METHODS: Two reviewers independently extracted data, assessed the risk of bias, and assessed evidence certainty. The efficacy of prophylactic strategies was estimated by frequentist and Bayesian network meta-analysis models. The primary composite outcome was preeclampsia/ pregnancy-induced hypertension. RESULTS: In total, 130 trials with a total of 112,916 patients were included to assess 13 prophylactic strategies. Low-molecular-weight heparin (0.60; 95% confidence interval, 0.42-0.87), vitamin D supplementation (0.65; 95% confidence interval, 0.45-0.95), and exercise (0.68; 95% confidence interval, 0.50-0.92) were as efficacious as calcium supplementation (0.71; 95% confidence interval, 0.62-0.82) and aspirin (0.79; 95% confidence interval, 0.72-0.86) in preventing preeclampsia/pregnancy-induced hypertension, with a P score ranking of 85%, 79%, 76%, 74%, and 61%, respectively. In the head-to-head comparison, no differences were found between these effective prophylactic strategies for preventing preeclampsia and pregnancy-induced hypertension, except with regard to exercise, which tended to be superior to aspirin and calcium supplementation in preventing pregnancy-induced hypertension. Furthermore, the prophylactic effects of aspirin and calcium supplementation were robust across subgroups. However, the prophylactic effects of low-molecular-weight heparin, exercise, and vitamin D supplementation on preeclampsia and pregnancy-induced hypertension varied with different risk populations, dosages, areas, etc. The certainty of the evidence was moderate to very low. CONCLUSION: Low-molecular-weight heparin, vitamin D supplementation, exercise, calcium supplementation, and aspirin reduce the risk of preeclampsia/pregnancy-induced hypertension. No significant differences between effective prophylactic strategies were found in preventing preeclampsia. These findings raise the necessity to reevaluate the prophylactic effects of low-molecular-weight heparin, vitamin D supplementation, and exercise on preeclampsia.

Spatial-temporal heterogeneity and driving factors of PM2.5 in China: A natural and socioeconomic perspective.

Background: Fine particulate matter (PM2.5), one of the major atmospheric pollutants, has a significant impact on human health. However, the determinant power of natural and socioeconomic factors on the spatial-temporal variation of PM2.5 pollution is controversial in China. Methods: In this study, we explored spatial-temporal characteristics and driving factors of PM2.5 through 252 prefecture-level cities in China from 2015 to 2019, based on the spatial autocorrelation and geographically and temporally weighted regression model (GTWR). Results: PM2.5 concentrations showed a significant downward trend, with a decline rate of 3.58 µg m-3 a-1, and a 26.49% decrease in 2019 compared to 2015, Eastern and Central China were the two regions with the highest PM2.5 concentrations. The driving force of socioeconomic factors on PM2.5 concentrations was slightly higher than that of natural factors. Population density had a positive significant driving effect on PM2.5 concentrations, and precipitation was the negative main driving factor. The two main driving factors (population density and precipitation) showed that the driving capability in northern region was stronger than that in southern China. North China and Central China were the regions of largest decline, and the reason for the PM2.5 decline might be the transition from a high environmental pollution-based industrial economy to a resource-clean high-tech economy since the implementation the Air Pollution Prevention and Control Action Plan in 2013. Conclusion: We need to fully consider the coordinated development of population size and local environmental carrying capacity in terms of control of PM2.5 concentrations in the future. This research is helpful for policy-makers to understand the distribution characteristics of PM2.5 emission and put forward effective policy to alleviate haze pollution.

[Feeding ecology of Decapterus maruadsi in the southern coastal area of Zhejiang based on stomach contents and stable isotope analysis.] / åŸºäºŽèƒƒå«ç‰©å’Œç¢³ã€æ°®ç¨³å®šåŒä½ç´ ç ”ç©¶æµ™æ±Ÿå—éƒ¨è¿‘æµ·è“åœ†é²¹çš„æ‘„é£Ÿç”Ÿæ€.

Decapterus maruadsi is an important economic pelagic fish in the southern coastal area of Zhejiang. According to the bottom trawl surveys conducted in May, August, November 2020 and January 2021, the feeding habits of D. maruadsi in the southern coastal area of Zhejiang were examined by both stable isotope (carbon, δ13C, and nitrogen, δ15N) and stomach content analyses. Results showed that the δ13C value of D. maruadsi ranged from -17.76‰ to -15.25‰, with a mean of (-16.55±0.60)‰, while the δ15N value ranged from 9.06‰ and 13.03‰, with a mean of (11.76±0.88)‰. There was a significant negative correlation between the δ13C values and fork length, and a positive relationship between the δ15N with fork length. Results from stomach content analysis showed that the main prey groups of D. maruadsi were fish, shrimp, crabs, Cephalopod, Polychaete, and small crustaceans. As for the stable isotope analysis, the nutritional contribution rate of shrimp was the highest (40%-84%) among all prey groups, followed by Polychaete, small crustaceans, crabs, Cephalopods and fish. Significant ontogenetic dietary changes were found for D. maruadsi. As the fork length of D. maruadsi increased, it tended to eat prey from higher trophic levels.

Accumulation of quenched LHCII around PSI in Chlamydomonas cells in state2 revealed by cryo-fluorescence lifetime imaging.

Fluorescence-spectral microscope observations of photosynthetic organisms at cryogenic temperatures have the ability to spectrally resolve the two photosystems (PSs) and thus provide a powerful tool to elucidate the functional analysis of photosynthesis in vivo. In the present study, a measurement channel of the fluorescence lifetime at 680 nm was added to the cryo-microscope system previously developed by the authors. This provides access to information on the functional state of the light-harvesting system in living cells during regulation by a mechanism called state transitions. The observations of state1-locked and state2-locked Chlamydomonas cells at 80 K enabled us to identify a component showing rapidly decaying fluorescence with a lifetime of ca. 3 ps and emitting at around 676 nm. The component was assigned to the light-harvesting complex II (LHCII) that is isolated from both PSs and in a quenched state, probably due to the formation of aggregates. Simultaneous spectral observations revealed the accumulation of this free LHCII in the photosystem I (PSI)-enriched region within each state2-locked cell. To the best of our knowledge, this is the first in-vivo observation which suggests the localization of the quenched LHCII aggregates.

State transition is quiet around pyrenoid and LHCII phosphorylation is not essential for thylakoid deformation in Chlamydomonas 137c.

Photosynthetic organisms have developed a regulation mechanism called state transition (ST) to rapidly adjust the excitation balance between the two photosystems by light-harvesting complex II (LHCII) movement. Though many researchers have assumed coupling of the dynamic transformations of the thylakoid membrane with ST, evidence of that remains elusive. To clarify the above-mentioned coupling in a model organism Chlamydomonas, here we used two advanced microscope techniques, the excitation-spectral microscope (ESM) developed recently by us and the superresolution imaging based on structured-illumination microscopy (SIM). The ESM observation revealed ST-dependent spectral changes upon repeated ST inductions. Surprisingly, it clarified a less significant ST occurrence in the region surrounding the pyrenoid, which is a subcellular compartment specialized for the carbon-fixation reaction, than that in the other domains. Further, we found a species dependence of this phenomenon: 137c strain showed the significant intracellular inhomogeneity of ST occurrence, whereas 4A+ strain hardly did. On the other hand, the SIM observation resolved partially irreversible fine thylakoid transformations caused by the ST-inducing illumination. This fine, irreversible thylakoid transformation was also observed in the STT7 kinase-lacking mutant. This result revealed that the fine thylakoid transformation is not induced solely by the LHCII phosphorylation, suggesting the highly susceptible nature of the thylakoid ultrastructure to the photosynthetic light reactions.