Nanoplastics impair growth and nitrogen fixation of marine nitrogen-fixing cyanobacteria.

Nanoplastics pollution is a growing environmental problem worldwide. Recent research has demonstrated the toxic effects of nanoplastics on various marine organisms. However, the influences of nanoplastics on marine nitrogen-fixing cyanobacteria, a critical nitrogen source in the ocean, remained unknown. Here, we report that nanoplastics exposure significantly reduced growth, photosynthetic, and nitrogen fixation rates of Crocosphaera watsonii (a major marine nitrogen-fixing cyanobacterium). Transcriptomic analysis revealed that nanoplastics might harm C. watsonii via downregulation of photosynthetic pathways and DNA damage repair genes, while genes for respiration, cell damage, nitrogen limitation, and iron (and phosphorus) scavenging were upregulated. The number and size of starch grains and electron-dense vacuoles increased significantly after nanoplastics exposure, suggesting that C. watsonii allocated more resources to storage instead of growth under stress. We propose that nanoplastics can damage the cell (e.g., DNA, cell membrane, and membrane-bound transporters), inhibit nitrogen and carbon fixation, and hence lead to nutrient limitation and impaired growth. Our findings suggest the possibility that nanoplastics pollution could reduce the new nitrogen input and hence affect the productivity in the ocean. The impact of nanoplastics on marine nitrogen fixation and productivity should be considered when predicting the ecosystem response and biogeochemical cycling in the changing ocean.

Understanding the variable metal concentrations in estuarine oysters Crassostrea hongkongensis: A biokinetic analysis.

Understanding the metal concentrations in oysters is important because of its relevance to human health and biomonitoring. However, metal concentrations in oysters are highly variable in nature and not well explained by metal exposure. This study examined the metal contamination in farm oysters Crassostrea hongkongensis grown in Qinzhou Bay, south China. Cadmium (Cd), zinc (Zn), nickel (Ni), and copper (Cu) concentrations in the oysters varied between 7.9 and 72.2, 282-17003, 0.37-47.7 and 37-4012 µg g-1, respectively, showing large metal variability among different individuals. Oyster metal concentrations decreased with increasing body size and significantly higher levels were observed in wet season. Low salinity and slower oyster growth due to inferior growth conditions could be responsible for the elevated metal concentrations in the wet season. Biokinetic modeling showed that the coupling of ingestion rate and growth can cause 2.8-4.2 folds differences in the oyster Cd and Zn concentrations, respectively, suggesting the significant role of oyster bioenergetics in contributing to the metal variability. Modeling data revealed that Cd and Zn concentrations in oyster tissues reach maximum levels when oysters have their lowest growth efficiency. This suggests that any factors influencing the energy budget in oysters could simultaneously alter their metal concentrations, which might be the reason why oyster metal concentrations are so variable in the natural environment.

Surface-Charge-Driven Ferroptosis and Mitochondrial Dysfunction Is Involved in Toxicity Diversity in the Marine Bivalve Exposed to Nanoplastics.

Nanoplastics (NPs) pervade daily life, posing serious threats to marine ecosystems. Despite the crucial role that surface charge plays in NP effects, there is a substantial gap in our understanding of how surface charge influences NP toxicity. Herein, by exposing Ruditapes philippinarum (R. philippinarum) to both positively charged NPs (p-NPs) and negatively charged NPs (n-NPs) at environmentally relevant particle number levels for a duration of 35 days, we unequivocally demonstrate that both types of NPs had discernible impacts on the clams depending on their surface charge. Through transcriptomic and proteomic analyses, we unveiled the primary mechanisms behind p-NP toxicity, which stem from induced mitochondrial dysfunction and ferroptosis. In contrast, n-NPs predominantly stimulated innate immune responses, influencing salivary secretion and modulating the complement and coagulation cascades. Furthermore, in vitro tests on clam immune cells confirmed that internalized p-NPs triggered alterations in mitochondrial morphology, a decrease in membrane potential, and the initiation of ferroptosis. Conversely, n-NPs, to a certain extent, moderated the expression of genes related to immune responses, thus mitigating their adverse effects. Taken together, these findings indicate that the differential surface-charge-driven ferroptosis and mitochondrial dysfunction in clams play a critical role in the toxicity profile of NPs, providing an insightful reference for assessing the ecological toxicity associated with NPs.

Helicobacter pylori vacA affects the expression of COX-2 in the duodenal mucosa of patients with duodenitis.

Duodenitis refers to inflammation that occurs in the duodenum. Helicobacter pylori (Hp) is a known risk factor for duodenitis. This paper attempted to analyze the correlation between Hp virulence genotypes and the initiation and development of duodenal bulbar inflammation (DBI) to lay the foundation for the management of duodenitis induced by Hp infection. Total RNA was extracted from duodenal samples of 156 Hp-positive patients [70 with DBI and 86 with duodenal bulbar ulcer (DBU)] and 80 Hp-free DBI patients, followed by RT-qPCR detection of COX-2 mRNA expression and the presence of virulence factors. The cagA positive (62.2%), vacAs1 (21.79%), vacAm2 (23.72%), vacAs1m2 (19.87%) and iceA1 (55.80%) genotypes were dominant in 156 Hp-positive samples. Statistical difference was observed in vacAs and vacA mixtures between DBI and DBU patients. Gastric metaplasia had an association with vacA allelotypes, and its occurrence had strong correlations with vacAs1 and vacAs1m2 genotypes. The vacAs1 and vacAs1m2 genotypes were correlated with gastric metaplasia occurrence (all p<0.05). There were significant correlations between vacAs and vacA mixtures with cagA genotypes, and between iceA genotypes with vacA mixtures (all p<0.05). COX-2 was strongly expressed in Hp-infected duodenal mucosa and showed correlations with vacA genotype. COX-2 was differentially expressed in vacAs1- and vacAs2-positive patients. COX-2 was more highly upregulated in vacAs1m1- and vacAs1m2-positive patients than vacAs2m2-positive patients. Overall, Hp virulence genotype vacA was correlated with DBI and DBU initiation and development.

Mechanisms underlying the alleviated cadmium toxicity in marine diatoms adapted to ocean acidification.

Anthropogenic activities have significantly increased the influx of carbon dioxide and metals into the marine environment. Combining ocean acidification (OA) and metal pollution may lead to unforeseen biological and ecological consequences. Several studies have shown that OA reduces cadmium (Cd) toxicity in marine diatoms. Although these studies have shed light on the physiological and transcriptomic responses of diatoms exposed to Cd, many aspects of the mechanisms underlying the reduced metal accumulation in diatoms remain unknown. This study aims to address this unresolved question by comparing Cd subcellular distribution, antioxidant enzyme activity, relative expression of metal transporters, surface potential, surface composition, and transmembrane potential in the diatom Phaeodactylum tricornutum grown under ambient and 1200 µatm pCO2 conditions. Our findings reveal that diatoms grown in acidified seawater exhibit higher surface potential and higher plasma membrane depolarization. These changes and the competing effects of increased H+ concentration result in a blunted response of P. tricornutum to the Cd challenge. Consequently, this study offers a new explanation for mitigating Cd toxicity by marine diatoms adapted to OA.

Ocean acidification affects physiology of coccolithophore Emiliania huxleyi and weakens its mechanical resistance to copepods.

The effects of ocean acidification (OA) on coccolithophore's photosynthesis, calcification rates, and growth have been extensively studied. However, how the intracellular Ca2+, mechanical properties and chemical composition of the coccoliths are affected by OA have not yet been investigated. This study tries to fill these gaps using Emiliania huxleyi as a model coccolithophore. When the seawater pCO2 increased from 400 µatm to 1200 µatm, the intracellular Ca2+ and coccolith area were reduced by 66% and 36%, respectively. Single-cell mapping by atomic force microscopy revealed that the modulus and hardness of coccolith decreased from 23.6 ± 0.2 GPa to 12.0 ± 5.5 GPa and from 0.53 ± 0.15 GPa to 0.20 ± 0.06 GPa, respectively. Additionally, the proportional organic matter and silicon in the coccolith surfaces increased with pCO2. The copepods Acartia pacifica fed on more E. huxleyi grown at higher pCO2. Our study implies that OA could change coccolithophore's competitive interactions with other phytoplankton and ultimately influence carbon export to the deep ocean.

Impact of facemask debris on marine diatoms: Physiology, surface properties, sinking rate, and copepod ingestion.

Discarded surgical masks have become a new source of plastic waste in seawater capable of releasing numerous micro and nano plastic fragments. However, little information is available about how this waste impacts the ecological state of marine phytoplankton. Here, we exposed two model marine diatoms (Phaeodactylum tricornutum and Thalassiosira weissflogii) to mask-released debris (MD) that is characterized by various differently-charged functional groups. Although MD could only bind loosely to diatoms, it still inhibited their growth and significantly altered cell surface physicochemical properties. At the nanoscale, MD-exposed cell walls showed enhanced roughness and modulus, besides declined electrical potential, adhesion, and proportion of oxygen-containing compounds. As a result, diatom ingestion by copepods was reduced, and the sinking rate of the carbon pool consisting of MD plus diatoms decreased as well. Our study indicated that MD effects on diatoms have the potential to slow down carbon export from surface seawater to the deep sea. Since oxidation and generation of functional groups are common during the aging process of microplastics (MPs) in nature, the interactions between the diatom cell surface and MD have important environmental significance.

Coupling isotopic signatures and partial extraction method to examine lead pollution in mangrove sediments.

Elevated lead (Pb) has been widely observed in mangrove sediments due to human activities, yet understanding the sources of Pb in these sediments and the factors influencing Pb accumulation is challenging. Here, we combined Pb isotopes with partial extraction methods to study Pb contamination levels in mangrove sediments from the eastern and western parts of the Maowei Sea, China. Our results showed that the Pb in the leachate and residual fraction was mainly from anthropogenic and natural sources, respectively. The use of 204Pb isotope analysis can reveal some overlooked differences between anthropogenic and natural sources. Calculation by Bayesian mixing model showed no significant difference in the total anthropogenic contribution between the two sites, but the relative contribution of each end member differed. The contribution of Pb/Zn ores was much higher in the eastern sites (30.9 ± 5.1%) than in the west (18.4 ± 5.5%), while that of agricultural activities was much lower in the east (5.2 ± 3.1%) than in the west (13.5 ± 4.6%). The elevated anthropogenic Pb accumulation in mangrove sediments was ascribed to organic matter. This study provides more data on Pb isotopic composition and new insights into Pb biogeochemistry in the mangrove environment.

Expression of m6A RNA Methylation Regulators and Their Clinical Predictive Value in Intrahepatic Cholangiocarcinoma.

BACKGROUND: N6-methyladenosine (m6A) RNA methylation regulators have been implicated in the carcinogenesis and progress of a variety of cancers. Until now, the effects of them on intrahepatic cholangiocarcinoma (ICC) have been poorly understood. METHODS: We used the GEO databases to systematically evaluate the expression profiles of 36 m6A RNA methylation regulators in ICC patients and produced a signature to assess its prognostic values. In vitro experiments were implemented to confirm the expression level. RESULTS: Compared to normal intrahepatic bile duct tissues, more than half of these 36 genes showed different levels of expression in ICC tissues. Two groups emerged from the consensus cluster analysis of these 36 genes. The two cluster of patients had significantly different clinical outcomes. In addition, we created a m6A-related prognostic signature that performed exceptionally well in the prognostic categorization of ICC patients, based on the ROC curves, Kaplan-Meier curves, and univariate and multivariate Cox regression analyses. Further research showed that there was a significant association between the m6A-related signature and the manifestations of tumor immune microenvironment in ICC. The expression level and biological effect of METTL16, one of the two m6A RNA methylation regulators incorporated in the signature, were confirmed and explored by using in vitro experiments. CONCLUSIONS: This analysis revealed the predictive roles of m6A RNA methylation regulators in ICC.

Metal leaching from plastics in the marine environment: An ignored role of biofilm.

A large quantity of metal compounds in plastics are released into the marine environment every year. However, our understanding of the extent and mechanism by which polymer-bound metals leach into seawater is still limited. In this study, a comprehensive survey was conducted to measure the metal concentrations in commonly used plastics and evaluate the effects of environmental factors (temperature, radiation, and salinity) and the physiochemical properties (surface roughness, specific surface area, hydrophobicity, and crystallinity) of the plastics on their metal leaching into seawater. In particular, we observed the metal loss from six plastics submerged in coastal seawater for eight months and studied the role of biofilm in controlling the leaching of Sb, Sn, Pb, Ba, and Cr. Our results indicate that increased temperature enhanced the release of these metals, while exposure to ultraviolet radiation significantly increased the leaching of Sn from polylactide (PLA). High salinity facilitated the leaching of Sn from PLA and Pb from polyvinylchloride ball, however inhibited the leaching of Ba from PE wrap. The leaching rate was primarily determined by the inherent property of crystallinity. Metal loss from the plastics in the field was apparent during the first three weeks, but then was hindered by the development of biofilm. Our study provides the mechanisms underlying metal leaching from physical, chemical, and biological perspectives, which is useful for understanding the environmental risk of the plastic-containing metals.

Isotopic signatures unveil the lead sources and migration in surface mangrove sediments.

Mangrove sediments act as both sinks and secondary sources for lead (Pb), yet the sources, migration, and transformations of Pb in mangrove environments are poorly understood. In this study, Pb concentration in three mangrove sediments adjacent to different land-use types was evaluated. The Pb sources were quantitatively identified using Pb isotopes. Our data indicated minor Pb contamination in the mangrove sediments, possibly due to the relative lack of developed industry in this region. The Pb isotopic ratios suggested, on average, natural sources, coal combustion, agricultural activities, and traffic-related emissions respectively contributed approximately 61.4 %, 18.8 %, 14.0 %, and 5.8 % of the Pb accumulation in the mangrove sediments, suggesting that coal combustion and agriculture were important anthropogenic Pb sources. Significant relationships were observed between the 206Pb/207Pb ratios and total organic content (TOC) in mangrove sediments, which implied contrasting Pb cycling in two mangrove environments. We further suggested that organic matter and sulfur content significantly reduced Pb mobility and bioavailability in mangrove sediments. Our study provides isotopic method to investigate the Pb sources and migration in the mangrove environment.

Comparison between discarded facemask and common plastic waste on microbial colonization and physiochemical properties during aging in seawater.

Facemasks are indispensable for preventing the spread of COVID-19. However, improper disposal of discarded facemasks has led to their contamination in the marine environment. To understand the environmental risk of this emerging plastic pollution, it's important to clarify the features that distinguish discarded facemasks from common plastic waste during aging. This study compared the microbial colonization, degradation-related enzymes, and physicochemical properties among surgical masks, polystyrene cups, polycarbonate bottles, and polyethylene terephthalate bottles in their aging processes in natural seawater. Compared to the other plastic wastes, surgical masks were colonized by the most diverse microorganisms, reaching 1521 unique prokaryotic OTUs after 21-day exposure in seawater. Moreover, the activity of eukaryotic enzymes associated with plastic degradation was 80-fold higher than that in seawater, indicating that the colonized eukaryotes would be the major microorganisms degrading the surgical masks. Meanwhile, the nano-sized defects (depth between 8 and 61 nm) would evolve into cracks of bigger sizes and result in the breakage of the microfibers and releasing microplastics into the ocean. Overall, our study demonstrated a distinctive plastisphere occurred in surgical masks from both microbial and physiochemical aspects. This work provides new insights for assessing the potential risk of plastic pollution caused by the COVID-19 pandemic.

A review of metal contamination in seagrasses with an emphasis on metal kinetics and detoxification.

Seagrasses are important foundation species in coastal ecosystems, and they provide food and habitat that supports high biodiversity. However, seagrasses are increasingly subjected to anthropogenic disturbances such as metal pollution, which has been implicated as a significant factor driving seagrass losses. There have been several reviews synthesizing the metal concentrations in seagrasses and evaluating their utility as biomonitors for metal pollution in the coastal environment at the local scale. However, the interpretation of metal data in seagrass biomonitors requires a more mechanistic understanding of the processes governing metal bioaccumulation and detoxification. In this review, the progress and trends in metal studies in seagrasses between 1973 and 2022 were analyzed to identify frontier topics in this field. In addition, we tried to (1) analyze and assess the current status of metal contamination in seagrasses on a global scale by incorporating more metal data from tropical and Indo-Pacific seagrasses, (2) summarize the geochemical and biological factors governing metal uptake and loss in seagrasses, and (3) provide an up-to-date understanding of metals' effects on seagrasses and their physiological responses to metal challenges. This review improves our understanding of the highly variable metal concentrations observed in the field.

The Metabolic Landscape of Breast Cancer and Its Therapeutic Implications.

Breast cancer is the most common malignant tumor globally as of 2020 and remains the second leading cause of cancer-related death among female individuals worldwide. Metabolic reprogramming is well recognized as a hallmark of malignancy owing to the rewiring of multiple biological processes, notably, glycolysis, oxidative phosphorylation, pentose phosphate pathway, as well as lipid metabolism, which support the demands for the relentless growth of tumor cells and allows distant metastasis of cancer cells. Breast cancer cells are well documented to reprogram their metabolism via mutations or inactivation of intrinsic factors such as c-Myc, TP53, hypoxia-inducible factor, and the PI3K/AKT/mTOR pathway or crosstalk with the surrounding tumor microenvironments, including hypoxia, extracellular acidification and interaction with immune cells, cancer-associated fibroblasts, and adipocytes. Furthermore, altered metabolism contributes to acquired or inherent therapeutic resistance. Therefore, there is an urgent need to understand the metabolic plasticity underlying breast cancer progression as well as to dictate metabolic reprogramming that accounts for the resistance to standard of care. This review aims to illustrate the altered metabolism in breast cancer and its underlying mechanisms, as well as metabolic interventions in breast cancer treatment, with the intention to provide strategies for developing novel therapeutic treatments for breast cancer.

Role of miRNA-99a-5p in Modulating the Function of Hepatocellular Carcinoma Cells: Bioinformatics Analysis and In Vitro Assay.

AIM: This study aimed to investigate the biological functions of miRNAs in hepatobiliary tumors as the focus of targeted therapy research. BACKGROUND: Hepatobiliary tumors are among the leading causes of cancer-related deaths worldwide. Many microRNAs (miRNAs) play an important regulatory role in tumor progression. Our study aims to explore some biologically functional miRNAs from different datasets of hepatobiliary tumors for disease diagnosis or treatment. OBJECTIVE: In this study, we tried to filter out differentially expressed miRNAs in different tumor datasets from the GEO database. METHODS: In this study, we first perform analyses in different GEO data sets. After taking the intersection, the initial scope is limited to several differential RNAs. Then, combined with the existing research results from Kaplan-Meier survival analysis and literature, the candidate molecule was finally identified to be studied. Furthermore, the biological characteristics analysis of the candidate molecule was performed on the basis of Cancermirnome online tool, including expression levels in tumors, KEGG and GO analysis, ROC analysis, and target gene prediction. Furthermore, the effect of the candidate molecule on the biological functions of liver cancer was verified by In Vitro assay. RESULTS: The preliminary analysis of bioinformatics shows that 16 differentially expressed miRNAs may play an important role in HCC or ICC. Ultimately, we identified miRNA-99a-5p as the only molecule to study. The results showed that miRNA-99a-5p is abnormally expressed in many tumors, and in liver cancer, its level of expression in tumor tissue is significantly lower than that in normal tissue. Then, the KEGG and GO analysis found that it functions in multiple pathways. At the same time, the ROC analysis found that it showed great potential for prognostic prediction in HCC and we also predicted that RUNDC3B is the most likely target to which it binds. Finally, the experimental results of overexpression and knockdown confirmed that miRNA-99a-5p could inhibit cell proliferation in HCC, which also suggested that it may be an important tumor suppressor in HCC. CONCLUSION: MiRNA-99a-5p was negatively correlated with HCC progression and could act as a novel therapeutic target for HCC.

Native Amino Group Directed Site-Selective ε-C(sp2)-H Iodination of Primary Amines.

Selective remote C-H activating amines using unmodified NH2 as a native directing group demonstrate compelling synthetic utilities. The 3-arylpropan-1-amine moiety is present in many drugs and candidates in clinical trials. Selective iodination of 3-arylpropan-1-amines on remote aryl rings gives valuable intermediates for modifying bioactive molecules and synthesizing quinolones. Here we report the first palladium-catalyzed selective ε-C(sp2)-H iodination of free 3-arylpropan-1-amines via a seven-membered palladacycle.

Silicon Limitation Impairs the Tolerance of Marine Diatoms to Pristine Microplastics.

Marine diatoms are currently facing increasing threats from microplastic (MP) pollution that is intertwined with the disturbed nutrient stoichiometry in seawater. The effects of nutrient imbalances such as silicon (Si) limitation on the interactions between diatoms and MPs remain poorly understood. In contrast to previous studies which mainly focused on MP toxicity, this study emphasizes how Si availability affects nano-scale interactions between pristine polystyrene MPs and diatom surfaces. Results showed that Si-starved cells were less tolerant to MP toxicity than the Si-enriched counterparts. Si limitation significantly changed the configuration and chemical composition of the perforated frustules, forming less negatively charged, more adhesive, and mechanically weaker cells. All of these changes facilitated the adsorption and hetero-aggregation between the diatom cells and MPs and compromised the diatoms' resistance to MP attack. Our study provides novel insights into the effects of pristine MPs in the marine environment under the context of dynamic nutrient conditions.

Eukaryotic community succession on discarded face masks in the marine environment.

Wearing facemasks remains an essential strategy for combating the COVID-19 pandemic. However, used masks are becoming plastic wastes that are widespread in the oceans, which is raising concerns about the potential impacts of these novel plastic niches on marine organisms. To delve into this issue, we exposed surgical masks to coastal waters for 30 days. Valuable information was recorded weekly in regard to the succession of the eukaryotic community inhabiting the masks via high-throughput 18S rRNA gene sequencing. Generally, the community on masks was significantly distinct from that in the surrounding seawater. With 1150 different eukaryotic taxa identified, the diversity of the vigorous colonizers of masks peaked at the beginning and decreased over time. A hallmark of initial colonization was the aggregation of diatoms, which formed biofilms on masks, followed by dinoflagellates that acted as a turning point for subsequent development of calcified species and other predators. This study provides insight into the eukaryotic community dynamics on discarded masks in the marine environment and highlights that the potential mask-mediated harmful species clustering may threaten the marine ecosystem.

Adsorption of di (2-ethylhexyl) phthalate (DEHP) to microplastics in seawater: a comparison between pristine and aged particles.

Microplastics (MPs) are a widely distributed pollutant and have been attracting global attention. The increasing abundance of MPs in marine environments has raised concern about their adverse effects on marine organisms and influence on the fate of contaminants in seawater. In this study, we investigated the effects of natural aging on the adsorption of di (2-ethylhexyl) phthalate (DEHP), one of the most widely used phthalic acid esters (PAEs), in two types of MPs (polyethylene and polystyrene). Biofilm was observed on the surface of MPs after 3-month exposure in seawater. Atomic force microscopy revealed there were significant physical changes in the MPs after aging. Aging in coastal seawater for 3 months significantly reduced the MPs' surface roughness and adhesion, and increased the Young's modulus at the same time. Adsorption isotherms of DEHP indicated that aged MPs had stronger binding capacity of the organic contaminant than pristine MPs. Our data shed some light on the biogeochemical role of MPs in marine environments.

Current Advancements in Antitumor Properties and Mechanisms of Medicinal Components in Edible Mushrooms.

Edible and medicinal fungi, a group of eukaryotic organisms with numerous varieties, including Coriolus versicolor, Ganoderma lucidum, Cordyceps sinensis, Pleurotus ostreatus, and Grifola frondosa, have been demonstrated to possess a board range of pharmaceutical properties, including anti-virus, anti-inflammation, and neuroprotection. Moreover, edible and medicinal fungi have been traditionally consumed as food to provide multiple nutrients and as drugs owing to having the activities of invigorating blood circulation, reinforcing the healthy qi, clearing away heat, and eliminating stasis for thousands of years in China. Malignant tumors, well-known as the second leading cause of death globally, accounted for nearly 10 million deaths in 2020. Thus, in-depth exploration of strategies to prevent and treat cancer is extremely urgent. A variety of studies have reported that the main bioactive components of edible and medicinal fungi, mainly polysaccharides and triterpenoids, exhibit diverse anticancer activities via multiple mechanisms, including inhibition of cell proliferation and metastasis, induction of apoptosis and autophagy, reversing multidrug resistance, and regulation of immune responses, thus suggesting their substantial potential in the prevention and treatment of cancer. Our review summarizes the research progress on the anticancer properties of edible and medicinal fungi and the underlying molecular mechanism, which may offer a better understanding of this field. Additionally, few studies have reported the safety and efficacy of extracts from edible and medicinal fungi, which may limit their clinical application. In summary, there is a need to continue to explore the use of those extracts and to further validate their safety and efficacy.