Architecture of symbiotic dinoflagellate photosystem I-light-harvesting supercomplex in Symbiodinium.

Symbiodinium are the photosynthetic endosymbionts for corals and play a vital role in supplying their coral hosts with photosynthetic products, forming the nutritional foundation for high-yield coral reef ecosystems. Here, we determine the cryo-electron microscopy structure of Symbiodinium photosystem I (PSI) supercomplex with a PSI core composed of 13 subunits including 2 previously unidentified subunits, PsaT and PsaU, as well as 13 peridinin-Chl a/c-binding light-harvesting antenna proteins (AcpPCIs). The PSI-AcpPCI supercomplex exhibits distinctive structural features compared to their red lineage counterparts, including extended termini of PsaD/E/I/J/L/M/R and AcpPCI-1/3/5/7/8/11 subunits, conformational changes in the surface loops of PsaA and PsaB subunits, facilitating the association between the PSI core and peripheral antennae. Structural analysis and computational calculation of excitation energy transfer rates unravel specific pigment networks in Symbiodinium PSI-AcpPCI for efficient excitation energy transfer. Overall, this study provides a structural basis for deciphering the mechanisms governing light harvesting and energy transfer in Symbiodinium PSI-AcpPCI supercomplexes adapted to their symbiotic ecosystem, as well as insights into the evolutionary diversity of PSI-LHCI among various photosynthetic organisms.

Semi-supervised learning methods for weed detection in turf.

BACKGROUND: Accurate weed detection is a prerequisite for precise automatic precision herbicide application. Previous research has adopted the laborious and time-consuming approach of manually labeling and processing large image data sets to develop deep neural networks for weed detection. This research introduces a novel semi-supervised learning (SSL) approach for detecting weeds in turf. The performance of SSL was compared with that of ResNet50, a fully supervised learning (FSL) method, in detecting and differentiating sub-images containing weeds from those containing only turfgrass. RESULTS: Compared with ResNet50, the evaluated SSL methods, Π-model, Mean Teacher, and FixMatch, increased the classification accuracy by 2.8%, 0.7%, and 3.9%, respectively, when only 100 labeled images per class were utilized. FixMatch was the most efficient and reliable model, as it exhibited higher accuracy (≥0.9530) and F1 scores (≥0.951) with fewer labeled data (50 per class) in the validation and testing data sets than the other neural networks evaluated. CONCLUSION: These results reveal that the SSL deep neural networks are capable of being highly accurate while requiring fewer labeled training images, thus being more time- and labor-efficient than the FSL method. © 2024 Society of Chemical Industry.

Structural basis and evolution of the photosystem I-light-harvesting supercomplex of cryptophyte algae.

Cryptophyte plastids originated from a red algal ancestor through secondary endosymbiosis. Cryptophyte photosystem I (PSI) associates with transmembrane alloxanthin-chlorophyll a/c proteins (ACPIs) as light-harvesting complexes (LHCs). Here, we report the structure of the photosynthetic PSI-ACPI supercomplex from the cryptophyte Chroomonas placoidea at 2.7-Å resolution obtained by crygenic electron microscopy. Cryptophyte PSI-ACPI represents a unique PSI-LHCI intermediate in the evolution from red algal to diatom PSI-LHCI. The PSI-ACPI supercomplex is composed of a monomeric PSI core containing 14 subunits, 12 of which originated in red algae, 1 diatom PsaR homolog, and an additional peptide. The PSI core is surrounded by 14 ACPI subunits that form 2 antenna layers: an inner layer with 11 ACPIs surrounding the PSI core and an outer layer containing 3 ACPIs. A pigment-binding subunit that is not present in any other previously characterized PSI-LHCI complexes, ACPI-S, mediates the association and energy transfer between the outer and inner ACPIs. The extensive pigment network of PSI-ACPI ensures efficient light harvesting, energy transfer, and dissipation. Overall, the PSI-LHCI structure identified in this study provides a framework for delineating the mechanisms of energy transfer in cryptophyte PSI-LHCI and for understanding the evolution of photosynthesis in the red lineage, which occurred via secondary endosymbiosis.

Electroacupuncture ameliorates peptic ulcer disease in association with gastroduodenal microbiota modulation in mice.

Peptic ulcer disease (PUD) is a common disease and frequently encountered in the clinic. Accumulating evidence suggests that PUD is associated with the gastrointestinal microbiota. Electroacupuncture (EA) is an improved version of acupuncture, which can improve the clinical effect by increasing the stimulation and delivering appropriate electrical pulses to needles. This method has been widely used in the treatment of peptic ulcer disease. However, its effect on gastrointestinal microbiota remains unclear. Therefore, in the present study, the ameliorative effect of EA was evaluated on the gastroduodenal mucosa, and the regulatory effect of the gastroduodenal microbiota was assessed in PUD mice. A total of 48 male Kun Ming mice were randomly divided into the following groups: normal control group (NC), PUD model group (PUD), Shousanli group (LI10), and Zusanli group (ST36) (n=12). The mice in groups LI10 and ST36 were treated with EA at LI10 and ST36, respectively. This intervention was continued for 7 days. Subsequently, we evaluated the morphological changes in the gastric and duodenal mucosa, and specific indices were measured, including the contents of serum dopamine (DA), the trefoil factor (TFF), and the vasoactive intestinal peptide (VIP). In addition, the gastric and duodenal microbiota were assessed via 16S ribosomal DNA sequencing. The results indicated that EA at LI10 or ST36 significantly reduced the injury of the gastroduodenal mucosa in PUD mice. The gastric microbial community structure of the groups LI10 and ST36 was similar to that of the NC group following comparison with the microbial community structure of the PUD model group. Moreover, the abundance of Firmicutes in the stomach was decreased, whereas that of Bacteroidetes was increased, and the abundance of Firmicutes in the duodenum was decreased. Furthermore, the microbial diversity and richness of the gastric microbiota in group LI10 were also significantly increased, and the serum dopamine and trefoil factor levels in group ST36 were significantly increased. Therefore, it is suggested that EA ameliorating PUD is in association with improving the levels of DA and TFF and regulating the relative abundances of Firmicutes and Bacteroidetes in the gastric microbiota.

Hirudin protects against isoproternol-induced myocardial infraction by alleviating oxidative via an Nrf2 dependent manner.

Oxidative stress plays a critical role in the progression of myocardial injury. Increasing evidence suggests that hiruidin can treat patients with cardio-injury. However, the mechanism of hirudin against myocardial infraction remains unknown. In the present study, we evaluated the potential role and mechanism of hirudin on both isoproterenol (ISO)-induced myocardial infraction (MI) in rats and Hypoxia-Reoxygenation model in H9C2 cells. Compared with the model group, hirudin apparently decreased the levels of myocardial Creatine Kinase Isoenzyme-MB (CK-MB), lactate dehydrogenase (LDH), and alleviated myocardial histopathological changes induced by ISO injection. The underlying mechanisms were revealed by the following observations: Hirudin exerted its cardioprotective effect via restoring super oxide dismutase (SOD), attenuating reactive oxygen species (ROS) and malondialdehyde (MDA). It induced the activation of Nuclear factor erythroid 2-related factor 2 (Nrf2) signal pathway through disrupting Keap1-Nrf2 complex, thus Nrf2 translocated from cytoplasm to nucleus to regulate Nrf2-dependent gene (HO-1, SOD) expressions. Furthermore, it should be noted that hirudin restored mitochondrial membrane potential in addition to cytochrome C-related apoptosis.

Field investigation of temporal variation of volatile organic compounds at a landfill in Hangzhou, China.

Variation of volatile organic compound (VOC) concentration and composition in an active landfill were monitored by a developed static chamber for 2 years. The landfill gas from 82 sampling points including 70 points on working face, 8 points on geomembrane (GMB), and 4 points on final cover were analyzed for VOCs by GC-MS. Twenty-eight types of VOCs were detected, including terpenes, sulfur compounds, aromatics, hydrocarbon, oxygenated compounds, aldehyde compounds, and halogenated compounds. Terpenes were the dominant VOCs recorded in the spring, autumn, and winter seasons, whereas sulfur compounds dominated in the summer season. Limonene, ethyl alcohol, and acetone were identified as the main VOCs emitted from the waste working face of the landfill. Limonene dominated the terpenes with a maximum concentration of 43.29 µg m-3 in the autumn season. Limonene was also the dominant VOC escaping from the defects of geomembrane temporary cover reaching an average concentration 38 µg m-3. The defects of geomembranes can be a great emission source of VOCs. Emission rate of limonene was 2.24 times higher than that on the working face. VOC concentrations on the final cover can be 166 times less than those obtained on the working face. VOC emitted from the landfill did not represent a health threat for human health. However, concentrations of methyl mercaptan and ethanethiol on the working face were 3.4-22.8 times greater than their odor threshold, which were the main compounds responsible for odor nuisance. Results obtained from CALPUFF model indicated that methyl mercaptan and ethanethiol would not be a nuisance for the residents around the landfill. However, these compounds are harmful to the workers on the landfill.

Methane hotspot localization and visualization at a large-scale Xi'an landfill in China: Effective tool for landfill gas management.

The variation characteristics and influence factors of methane emission at Jiangchungou landfill, one of the largest landfill in China, has been investigated by a one-year field monitoring campaign during 2015-2016. The methane concentration above the landfill surface varied widely from negligible to 33,975 ppm. At least 75% of the methane concentration values of the sampling points are lower than the allowed limit (500 ppm). More than 95% of the high concentration zones (>500 ppm) were located in the temporary cover area (TA). Several environmental factors were found to be related to the variation of the concentration values. A clear correlation was observed between barometric pressure and exceeding-standard areas with a correlation coefficient of -0.743 (p < 0.1). The concentration values in the final cover area (FA) were about one order of magnitude lower than those observed in the TA due to the fact that rapid methane production rate happened in the first 180 days after the high kitchen content wastes were landfilled. The percentages of the measured concentration values exceeding 500 ppm near the gas collection wells in TA zone were 71.5% in November, 2015 and 55.7% in January, 2016 due to the leakage from the sides of gas collection wells. The average methane concentration values on the HDPE geomembrane was higher than those observed on the loess cover due to the fact that the geomembrane was relatively thin (0.5 mm) and can be easily damaged by the operation vehicles. Thicker geomembranes (>1.5 mm) with a good construction quality control are expected to provide better performance at this site.

The apoptosis effect of hispolon from Phellinus linteus (Berkeley & Curtis) Teng on human epidermoid KB cells.

Phellinus linteus (Berkeley & Curtis) Teng, a well-known fungus of the genus Phellinus in the family of Hymenochaetaceae, is being increasingly used to treat a wide variety of disease processes such as oral ulcer, gastroenteric disorder, inflammation, lymphatic disease, and various cancers. However, the mechanism underlying its anti-oral cancer effect is poorly understood. In the present study, we prepared the ethanol extract of Phellinus linteus as a crude drug, and then obtained the active component hispolon by bioassay-guided isolation. Hispolon showed a dose-dependent inhibition of human epidermoid KB cell proliferation with IC50 of 4.62+/-0.16 microg/ml. Furthermore, it was revealed that hispolon could induce human epidermoid KB cell apoptosis with the characteristic of a DNA ladder, and with a significant increase of sub-G1. This process was accompanied by the collapse of mitochondrial membrane potential, the release of cytochrome c and the activation of Caspase-3. These results demonstrated that hispolon induced the death of KB cells through a mitochondria mediated apoptotic pathway. We propose that Phellinus linteus and its effective components could be used as an anti-oral cancer drug for future studies.