Integrated transcriptome and metabolome analysis revealed that HaMYB1 modulates anthocyanin accumulation to deepen sunflower flower color.

KEY MESSAGE: HanMYB1 was found to play positive roles in the modulation of anthocyanins metabolism based on the integrative analysis of different color cultivars and the related molecular genetic analyses. As a high value ornamental and edible crop with various colors, sunflowers (Helianthus annuus L.) provide an ideal system to understand the formation of flower color. Anthocyanins are major pigments in higher plants, which is associated with development of flower colors and ability of oxidation resistance. Here, we performed an integrative analysis of the transcriptome and flavonoid metabolome in five sunflower cultivars with different flower colors. According to differentially expressed genes and differentially accumulated flavonoids, these cultivars could be grouped into yellow and red. The results showed that more anthocyanins were accumulated in the red group flowers, especially the chrysanthemin. Some anthocyanins biosynthesis-related genes like UFGT (UDP-glycose flavonoid glycosyltransferase) also expressed more in the red group flowers. A MYB transcriptional factor, HanMYB1, was found to play vital positive roles in the modulation of anthocyanins metabolism by the integrative analysis. Overexpressed HanMYB1 in tobacco could deepen the flower color, increase the accumulation of anthocyanins and directly active the express of UFGT genes. Our findings indicated that the MYB transcriptional factors provide new insight into the dynamic regulation of the anthocyanin biosynthesis in facilitating sunflower color formation and anthocyanin accumulation.

Mechanism of Notch Signal Regulating Alveolar Epithelial Cell Autophagy after Infection with Klebsiella Pneumoniae.

BACKGROUND: The Notch signaling pathway regulates various cellular processes, including cell growth, inflammation response, and autophagy, thereby participating in the occurrence and development of various diseases. The present study aimed to investigate the molecular mechanism of Notch signaling in regulating alveolar type II epithelial cell viability and autophagy after Klebsiella pneumonia (KPN) infection. METHODS: KPN-infected human alveolar type II epithelial cells A549 (ACEII) were constructed. The autophagy inhibitor 3-methyladenine (3-MA) and Notch1 signaling inhibitor (DAPT) were used to pretreat A549 cells for 24 hours, 48 hours, and 72 hours before KPN infection. Real-time fluorescent quantitative PCR (qRT-PCR) and western blot assays were applied to detect the mRNA and protein expressions of LC3 and Notch1, respectively. ELISA was used to detect the levels of INF-γ, TNF-α, and IL-1ß in the cell supernatants. RESULTS: The results showed that KPN-infected A549 cells presented significantly upregulated Notch1 and autophagy-related protein LC3 levels, along with increased IL-1ß, TNF-α, INF-γ levels in a time-dependent manner. Autophagy inhibitor 3-methyladenine (3-MA) counteracted the promotive effects of LC3 and inflammatory cytokine levels in KPN-infected A549 cells; however, 3-MA did not influence Notch1 level. Notch1 inhibitor DAPT could suppress Notch1 and LC3 levels, thereby inhibiting inflammation response in KPN-treated A549 cells in a time-dependent way. CONCLUSIONS: KPN infection can activate the Notch signaling pathway and induce autophagy in type Ⅱ alveolar epithelial cells. Inhibiting the Notch signaling pathway may restrain KPN-induced A549 cell autophagy and inflammation response, shedding new insights for the treatment of pneumonia.

Lethal, behavioral, growth and developmental toxicities of alkyl-PAHs and non-alkyl PAHs to early-life stage of brine shrimp, Artemia parthenogenetica.

Alkyl-PAHs are the predominant form of PAHs in crude oils which are supposed to demonstrate different toxicities compared to non-alkyl PAHs. Little information is available about the toxicity of alkyl-PAHs on marine Artemia. This study addressed and compared the lethal, behavioral, growth and developmental toxicities of three alkyl-PAHs, namely 3-methyl phenanthrene (3-mPhe), retene (Ret) and 2-methyl anthracene (2-mAnt), to their non-alkyl forms, phenanthrene (Phe) and anthracene (Ant) using Artemia parthenogenetica (nauplii, <24 h) as test organism following a 48 h and a 7 d of exposure, respectively. Benzo-a-pyrene (Bap) was selected as a reference toxicant for the comparison with the above alkyl-PAHs and non-alkyl PAHs. Results showed that for all tested endpoints, A. parthenogenetica nauplii had the highest sensitivity to Bap while Ant had no significant effect on nauplii survival or development within given concentrations. Considering the aqueous freely dissolved PAH concentrations, the 48 h-LC50 (survival), 48 h-EC50 (immobility) and 7 d-LC10 (survival) of Bap were calculated as 0.321, 0.285 and 0.027 µg/L, respectively, which were twofold to fivefold lower than those of Phe, 3-mPhe, Ret, Ant and 2-mAnt. A higher acute toxicity of alkyl-PAHs (3-mPhe and 2-mAnt) than their non-alkyl forms (Phe and Ant) was observed. Not limited to Phe, the common non-polar narcotic mode of action was also observed for Bap, 3-mPhe, Ret and 2-mAnt, which was evident by the inhibited mobility of nauplii. The decreased body lengths were found for all PAH treatments compared to the solvent control, whereas instar retardations were only found in nauplii exposed to Bap, Phe and Ret. Our findings emphasized the sensitivity differences of A. parthenogenetica nauplii to selected alkyl PAHs and non-alkyl PAHs and confirmed the application of lethal, behavioral and growth indicators in the toxicity evaluation of selected PAHs other than Ant. However, the distinct toxicities of these PAHs suggested other toxic modes of action may play more important roles apart from narcotic mode of action and need to be elucidated in future studies. In addition, a strong correlation between the body length and the instar of A. parthenogenetica nauplii was observed for each PAH exposure, suggesting that body length can be representative for both growth and developmental indicators during biological monitoring of PAH pollution in marine environment.

Vertical distributions of mercury in marine sediment cores from central and southern part of Bohai Sea, China.

In past decades, China has experienced substantial economic growth and industrialization. However, the effects of vast development of China on Hg input to the nearby oceans are still unclear. In this study, four representative 210Pb-dated sediment cores were collected in the central and southern part of Bohai sea to investigate vertical changes of Hg contents and explore the relationship between the Hg deposition and pollution history in this region utilizing a large amount of information available. The results indicated that Hg median concentrations of sediment core B62, B66, JQ17 and HZ24 were 0.043 mg/kg, 0.054 mg/kg, 0.033 mg/kg and 0.018 mg/kg respectively, among which, B66 in Yellow river estuary and B62 in central part of Bohai Sea had higher concentrations and HZ24 in Bohai Strait had a lower concentration. 210Pb profile appeared as a three segments model in the core B62, but as many steps of decay with depth in B66. For HZ24, 210Pb activity only fluctuated with depth without any discernible trend. Sedimentary rates of these cores decreased as follows: B66＞B62＞JQ17＞HZ24. Vertical distributions of Hg concentrations in sediment cores were totally different from each other. Hg concentrations in sediment core B62 experienced an initial fluctuation followed by a decreasing trend, while sediment core HZ24 almost showed the uniform decreasing trends from the surface to the bottom. There were three segments of variation in sediment cores JQ17: initial fluctuation followed by an obviously decreasing tendency and then a converted variation from surface to bottom. Hg contents changes in core B62 might reflect the additive effects from atmospheric deposition at a larger scale and the river-delivered sediment accumulation, while Hg vertical changes in B66 mainly had a close relationship with the input of Yellow river. The converted variation at the bottom section in sediment cores JQ17 was inferred to have some relationship with the Chengbei platform construction in the corresponding periods.

The NAC gene family in the halophyte Limonium bicolor: Identification, expression analysis, and regulation of abiotic stress tolerance.

NAC transcription factors regulate plant growth, development, and stress responses. However, the number, types, and biological functions of Limonium bicolor LbNAC genes have remained elusive. L. bicolor secretes excessive salt ions through salt glands on its stems and leaves to reduce salt-induced damage. Here, we identified 63 NAC members (LbNAC1-63) in L. bicolor, which were unevenly distributed across eight chromosomes. Cis-elements in the LbNAC promoters were related to growth and development, stress responses, and phytohormone responses. We observed strong colinearity between LbNACs and GmNACs from soybean (Glycine max). Thus, LbNAC genes may share similar functions with GmNAC genes. Expression analysis indicated that 16 LbNAC genes are highly expressed in roots, stems, leaves, and flowers, whereas 17 LbNAC genes were highly expressed throughout salt gland development, suggesting that they may regulate this developmental stage. Silencing LbNAC54 in L. bicolor decreased salt gland density, salt secretion from leaves, and overall salt tolerance. In agreement, genes related to salt gland development were significantly downregulated in LbNAC54-silenced lines. Our findings shed light on LbNAC genes and help elucidate salt gland development and salt secretion in L. bicolor. Our data also provide insight into NAC functions in halophytes.

Different responses of marine microalgae Phaeodactylum tricornutum upon exposures to WAF and CEWAF of crude oil: A case study coupled with stable isotopic signatures.

Increasing use of chemical dispersants for oil spills highlights the need to understand their adverse effects on marine microalgae and nutrient assimilation because the toxic components of crude oil can be more bioavailable. We employed the crude oil water-accommodated fraction (WAF) and chemically enhanced WAF (CEWAF) to compare different responses in marine microalgae (Phaeodactylum tricornutum) coupled with stable isotopic signatures. The concentration and proportion of high-molecular-weight polycyclic aromatic hydrocarbons (HMW PAHs), which are key toxic components in crude oil, increased after dispersant addition. CEWAF exposure caused higher percent growth inhibition and a lower chlorophyll-a level of microalgae than those after WAF exposure. Compared with WAF exposure, CEWAF led to an enhancement in the self-defense mechanism of P. tricornutum, accompanied by an increased content of extracellular polymeric substances. 13C-depletion and carbon assimilation were altered in P. tricornutum, suggesting more HMW PAHs could be utilized as carbon sources by microalgae under CEWAF. CEWAF had no significant effects on the isotopic fractionation or assimilation of nitrogen in P. tricornutum. Our study unveiled the impact on the growth, physiological response, and nutrient assimilation of microalgae upon WAF and CEWAF exposures. Our data provide new insights into the ecological effects of dispersant applications for coastal oil spills.

Occurrence and potential risks of pharmaceutical contamination in global Estuaries: A critical review and analysis.

Input of pollutants to estuaries is one of the major threats to marine biodiversity and fishery resources, and pharmaceuticals are one of the most important contaminants of emerging concern in aquatic ecosystems. To synthesize pharmaceutical pollution levels in estuaries over the past 20 years from a global perspective, this review identified 3229 individual environmental occurrence data for 239 pharmaceuticals across 91 global estuaries distributed in 26 countries. The highest cumulative weighted average concentration level (WACL) of all detected pharmaceuticals in estuarine water was observed in Africa (145,461.86 ng/L), with 30 pharmaceuticals reported. North America (24,316.39 ng/L) was ranked second in terms of WACL, followed by South America (20,784.13 ng/L), Asia (5958.38 ng/L), Europe (4691.23 ng/L), and Oceania (2916.32 ng/L). Carbamazepine, diclofenac, and paracetamol were detected in all continents. A total of 41 functional categories of pharmaceuticals were identified, and analgesics, antibiotics, and stimulants were amongst the most ubiquitous groups in estuaries worldwide. Although many pharmaceuticals were observed to present lower than or equal to moderate ecological risk, 34 pharmaceuticals were identified with high or very high ecological risks in at least one continent. Pharmaceutical pollution in estuaries was positively correlated with regional unemployment and poverty ratios, but negatively correlated with life expectancy and GDP per capita. There are some limitations that may affect this synthesis, such as comparability of the sampling and pretreatment methodology, differences in the target pharmaceuticals for monitoring, and potentially limited number and diversity of estuaries covered, which prompt us to standardize methods for monitoring these pharmaceutical contaminants in future global studies.

Nutrient changes in the Bohai Sea over the past two decades.

With the growing problem of eutrophication in the Bohai Sea, actions have been taken to reduce nutrient inputs, but it remains to be seen whether nutrient levels and structure have been ameliorated. In this study, the nutrient trends in the Bohai Sea are re-examined based on observations from 2000 to 2019. The results suggest that dissolved inorganic nitrogen (DIN) concentrations and DIN/DIP (dissolved inorganic phosphate) ratios gradually increased from 2000 to 2013 but dramatically decreased from 2013 to 2019. The increase and decrease rates of DIN concentrations decreased with increasing water depth, indicating that DIN concentrations in nearshore waters responded more rapidly to changes in human activities. However, DIP concentrations responded weakly to nutrient inputs, with their trends uncoupled. The DIN/DIP ratios have declined close to and in some seasons even below the canonical Redfield ratio in areas with water depths >20 m recently, implying that relative nutrient limitation in these areas may be shifting from relative phosphorus (P) limitation to absence of relative nutrient limitation or relative nitrogen (N) limitation. Atmospheric deposition, wastewater discharge, and riverine input were responsible for 66 %, 21 %, and 13 % of the variance in the decline of DIN concentration, respectively. Several environmental indicators responded positively to the decrease in DIN concentrations and DIN/DIP ratios, with varying degrees of recovery recently. Our study proves the phased success of various nutrient reduction measures taken by the Chinese government to improve the environment of the Bohai Sea over the past decade.

Seasonal distribution of microplastics in the surface waters of the Yellow Sea, China.

Different studies are filling the gaps in the distribution map of global marine microplastics. However, the data on the seasonal variation is relatively limited, which may lead to overestimation or underestimation of the distribution level of microplastics. To understand baseline data and seasonal variations of the microplastics in the surface seawater of the Yellow Sea, a survey over four seasons was conducted during 2017-2018. Microplastics were collected using a 330 µm manta net. It was found that the abundance of microplastics was 0.63 ± 0.57 particles/m3. The seasonal abundance variation was spring > summer ≈ winter > autumn. The main categories were foam, line, and fragments, accounting for 32 %, 19 %, and 19 % of the total amount, respectively, and the dominant components were polypropylene, polyethylene, and polyethylene terephthalate, accounting for 38 %, 22 %, and 22 % of particles, respectively. The factors affecting the variation included wind-induced mixing, river input, and environmental topography.

Contrasting effects of temperature and biological processes on aragonite saturation state at the A4HDYD station in the North Yellow Sea.

To explore the effects of seawater temperature and biological processes on aragonite saturation state (Ωarag), eight field surveys were conducted from December 2014 to November 2015 at A4HDYD station in the North Yellow Sea (NYS). Low regional yearly initial values of seawater Ωarag (1.26-1.76) were obtained in winter due to low seawater temperature. During spring to early autumn, surface-water Ωarag increased from 2.02 to 3.47 for the increasing seawater temperature and biological production, whereas bottom-water Ωarag remained as low as 1.44-1.79 due to low seawater temperature, net community respiration and the influence of the North Yellow Sea Cold Water Mass (NYSCWM). Following the collapse of stratification in late autumn, the seawater was well-mixed with an average Ωarag of 2.17. The annual cycle of seawater temperature dominated the seasonal variations of Ωarag, counteracted by biological production increasing Ωarag of 0.49 in surface water in March and strengthened by net community respiration decreasing Ωarag of 0.11-0.41 below the pycnocline during summer and autumn. It is, therefore, mid-to-high latitude coastal areas impacted by human activities are likely subject to ocean acidification due to the combined effects of low seawater temperature and net community respiration.

Polystyrene microplastics alleviate adverse effects of benzo[a]pyrene on tissues and cells of the marine mussel, Mytilus galloprovincialis.

As two major ubiquitous pollutants, microplastics (MPs) and polycyclic aromatic hydrocarbons (PAHs) coexist in the marine environment. However, the role of MPs in altering the toxicity of PAHs to marine organisms is poorly understood. We therefore investigated the accumulation and toxicity of benzo[a]pyrene (B[a]P, 0.4 nM), in the marine mussel Mytilus galloprovincialis over a 4-day of exposure with or without the presence of 10 µm polystyrene microplastics (PS MPs) (10 particles/mL). The presence of PS MPs significantly decreased B[a]P accumulation in soft tissues of M. galloprovincialis by approximately 6.7%. Single exposure of PS MPs or B[a]P decreased the mean epithelial thickness (MET) of digestive tubules and enhanced reactive oxygen species (ROS) levels in haemolymph, while upon co-exposure the adverse impacts were alleviated. Real-time q-PCR results showed that most selected genes involved in stress response (FKBP, HSP90), immune (MyD88a, NF-κB) and detoxification (CYP4Y1) were induced for both single exposure and co-exposure. The co-presence of PS MPs down-regulated the mRNA expression of NF-κB in gills compared with of B[a]P alone. The uptake and toxicity reductions of B[a]P might result from the decrease of its bioavailable concentrations caused by the adsorption of B[a]P by PS MPs and the strong affinity of B[a]P to PS MPs. Adverse outcomes for the co-existence of marine emerging pollutants under long-term conditions remain to be further validated.

Acute and Chronic Effects of Crude Oil Water-Accommodated Fractions on the Early Life Stages of Marine Medaka (Oryzias melastigma, McClelland, 1839).

Oil spill is a major marine environmental pollution issue. Research regarding the long-term effects of oil spills on the early life stage of marine fish is still limited. In this study, the potential adverse impact of crude oil from one oil spill accident which occurred in the Bohai Sea on the early life stages of marine medaka (Oryzias melastigma, McClelland, 1839) was evaluated. A 96-h acute test (larvae) and a 21-d chronic test (embryo-larvae) of water-accommodated fractions (WAFs) from crude oil were conducted, respectively. The results of the acute test showed that only the highest concentration of WAFs (100.00%) significantly affected the mortality of larvae (p < 0.01) and that the 96 h-LC50 was 68.92% (4.11 mg·L-1 expressed as total petroleum hydrocarbons (TPHs)). Larval heart demonstrated histopathological alterations in all WAF-exposed groups. The chronic test results showed that, except for larval mortality, the total hatching success (%)/hatching time of embryos in WAF treatments was not significantly different from those of the control group (p > 0.05), and no malformation was found in surviving larvae after 21 d of exposure. Nevertheless, the exposed embryos and larvae in the highest concentration of WAFs (60.00%) demonstrated significantly reduced heart rate (p < 0.05) and increased mortality (p < 0.01), respectively. Overall, our results indicated that both acute and chronic WAF exposures had adverse impacts on the survival of marine medaka. In the early life stages, the heart of the marine medaka was the most sensitive organ which showed both structural alteration and cardiac dysfunction.

Bisphenol A decreases the developmental toxicity and histopathological alterations caused by polystyrene nanoplastics in developing marine medaka Oryzias melastigma.

Nanoplastics (NPs) are emerging pollutants posing risks to marine biota and human health due to their small size and high bioavailability. However, there are still knowledge gaps regarding effects of co-existing pollutants on NPs toxicity to marine organisms at their respective environmentally relevant concentrations. Herein we investigated developmental toxicity and histopathological alterations caused by co-exposure of polystyrene nanoplastics (PS-NPs) and bisphenol A (BPA) to marine medaka, Oryzias melastigma. Embryos at 6 h post-fertilization were exposed to 50-nm PS-NPs (55 µg/L) or BPA (100 µg/L) or co-exposed to a combination of both. Results showed that PS-NPs exhibited decreased embryonic heart rate, larval body length, and embryonic survival as well as larval deformities such as hemorrhaging and craniofacial abnormality. When co-exposed, BPA mitigated all the adverse developmental effects caused by PS-NPs. PS-NPs also led to an increase in histopathological condition index of liver with early inflammatory responses, while co-exposure of BPA with PS-NPs did not. Our data suggest that the toxicity reduction of PS-NPs in the presence of BPA might result from the decreased bioaccumulation of PS-NPs caused by the interaction between BPA and PS-NPs. This study unveiled the impact of BPA on the toxicity of nanoplastics in marine fish during early developmental stages and highlight the need of more research on the long-term effects of complex mixtures in the marine environment by applying omics approaches to better understand the toxicity mechanism.

Heterologous overexpression of Apocynum venetum flavonoids synthetase genes improves Arabidopsis thaliana salt tolerance by activating the IAA and JA biosynthesis pathways.

Salt stress is a serious abiotic stress that primarily inhibits plant growth, resulting in severe yield losses. Our previous research found that flavonoids play important roles in A. venetum salt stress tolerance. In response to salt stress, we noted that the flavonoid content was depleted in A. venetum. However, the detailed mechanism is still not clear. In this study, the expression patterns of three flavonoids synthetase genes, AvF3H, AvF3'H, and AvFLS were systemically analyzed under salt stress in A. venetum seedlings. The salt tolerance of transgenic Arabidopsis plants was improved by heterologous overexpression of these synthetase genes. The NBT and DAB staining results as well as H2O2 and O2•- content analysis revealed that under salt stress, ROS molecules were reduced in transgenic plants compared to WT plants, which corresponded to the activation of the antioxidant enzyme system and an increase in total flavonoid content, particularly rutin, eriodictyol, and naringerin in transgenic plants. External application of flavonoids reduced ROS damage in WT plants just like what we observed in the transgenic plants (without the external application). Additionally, our transcriptome analysis demonstrated that auxin and jasmonic acid biosynthesis genes, as well as signaling transduction genes, were primarily activated in transgenic plants under salt stress, leading to activation of the cell wall biosynthesis or modification genes that promote plant growth. As a result, we investigated the mechanism through flavonoids enhance the salt tolerance, offering a theoretical foundation for enhancing salt tolerance in plants.

Insights into the Antifungal Properties of Myxobacteria Outer Membrane ß-1,6-Glucanase.

Fungal cell wall decomposition enzymes exhibit great potential for the development of efficient antifungal agents. However, their practical application is restricted due to incomplete understanding of the action mode. In our previous study, we identified that a novel outer membrane (OM) ß-1,6-glucanase GluM is deployed by predatory myxobacteria to feed on fungi. In this work, we provide deep insights into the antifungal mechanism of ß-1,6-glucanase and its potential in improving plant disease resistance. The fungal cell wall decomposition ability of GluM resulted in irregular hyphae morphology, changed chitin distribution, increased membrane permeability, and leakage of cell constituents in Magnaporthe oryzae Guy11. Under the attack pattern, the cell wall integrity pathway was activated by strain Guy11 for self-protection. GluM exhibited a distinct endo-model toward fungal cell wall; the favorite substrate of GluM toward fungal ß-1,6-glucan may give reason for its efficient antifungal activity compared with Trichoderma ß-1,6-glucanase. Moreover, released glucans from GluM hydrolysis of fungal cell wall functioned as an elicitor and induced rice immunity by means of jasmonic acid pathway. Based on the dual roles of antifungal properties, gluM transgenic plants conferred enhanced resistance against fungal infection.

Predation of oomycetes by myxobacteria via a specialized CAZyme system arising from adaptive evolution.

As social micropredators, myxobacteria are studied for their abilities to prey on bacteria and fungi. However, their predation of oomycetes has received little attention. Here, we show that Archangium sp. AC19 secretes a carbohydrate-active enzyme (CAZyme) cocktail during predation on oomycetes Phytophthora. These enzymes include three specialized ß-1,3-glucanases (AcGlu13.1, -13.2 and -13.3) that act as a cooperative consortium to target ß-1,3-glucans of Phytophthora. However, the CAZymes showed no hydrolytic effects on fungal cells, even though fungi contain ß-1,3-glucans. Heterologous expression of AcGlu13.1, -13.2 or -13.3 enzymes in Myxococcus xanthus DK1622, a model myxobacterium that antagonizes but does not predate on P. sojae, conferred a cooperative and mycophagous ability that stably maintains myxobacteria populations as a mixture of engineered strains. Comparative genomic analyses suggest that these CAZymes arose from adaptive evolution among Cystobacteriaceae myxobacteria for a specific prey killing behavior, whereby the presence of Phytophthora promotes growth of myxobacterial taxa by nutrient release and consumption. Our findings demonstrate that this lethal combination of CAZymes transforms a non-predatory myxobacterium into a predator with the ability to feed on Phytophthora, and provides new insights for understanding predator-prey interactions. In summary, our work extends the repertoire of myxobacteria predatory strategies and their evolution, and suggests that these CAZymes can be engineered as a functional consortium into strains for biocontrol of Phytophothora diseases and hence crop protection.

Empirical Analysis of Customer Risk and Corporate Financing Constraints Based on Supply Chain Networks.

A supply chain's risk spillover effect will affect the customer's risk on the financing constraints of suppliers. This paper builds on the evaluation of customer risk by fuzzy mathematics, combines with the A-share listed companies in Shanghai and Shenzhen from 2007 to 2019 as a study sample, and empirically inspects the influence of customer risk on the level of corporate financing constraints. According to the study, it shows that the customer risk is currently at a moderate level, which will notably impair the supplier's external financing ability. This phenomenon is more remarkable when the monetary policy is tightened with fierce competition in the industry. This paper unveils the economic consequences of customer risk spillovers from a supply chain, enriches the study of the generation mechanism of corporate financing constraints, and provides investors and regulators with empirical evidence to appreciate corporate financing constraints.

Systematical insights into distribution and characteristics of microplastics in near-surface waters from the East Asian Seas to the Arctic Central Basin.

The spatial distribution and composition of microplastics in near-surface water (8 m) was investigated from the East Asian Seas to the Arctic Central Basin. Microplastics were detected in 93.9% of the sampling sites. Abundances ranged from 0.48 to 7.62 items/m3, with an average abundance of 2.91 ± 1.93 items/m3. The highest average abundance was observed in the Arctic Central Basin. Polyester (PET) was the dominant type, accounting for 71.3% of total microplastics, followed by rayon or cellophane and polytetrafluoroethylene (PTFE). Microplastics < 2 mm accounted for 81.9% of total particles. Its distribution peaked in the 1-2 mm size range. The 0.30-2 mm fibers were the most abundant. In the East Asian Seas, the abundance was significantly negatively correlated with longitude, whereas the accumulation of microplastics was not observed in the northeastern sector of Japan Sea. Abundances of microplastics at sites located in the sub-Arctic and Arctic Oceans showed a significant positive relationship with latitude, indicating that the Arctic Ocean is a potential accumulation zone of microplastics. The findings of this study will provide systematical insights into distribution of microplastics and basic information for understanding the accumulation mechanism of microplastics in near-surface waters from the East Asian Seas to the Arctic Central Basin.

Distribution characteristics of microplastics in surface and subsurface Antarctic seawater.

Microplastics have attracted worldwide attention due to their potential threat to the marine ecosystem, with such pollutants even detected in the polar seas. Although in-depth research on microplastics has increased in recent years, studies in Antarctic waters remain relatively scarce compared with coastal waters and open oceans. In this study, microplastics in surface and subsurface Antarctic waters were investigated. The average microplastic abundance in the surface water was 0.10 ± 0.14 items/m3, with highest abundance in the Ross Sea, and the average microplastic abundance in the subsurface water was 1.66 ± 1.20 items/m3, with highest abundance in the Dumont d'Urville Sea. Polyester was the main microplastic in the surface waters (87.3%), while polypropylene (33.1%), polyester (28.7%), and polyethylene (22.8%) were the dominant microplastics in the subsurface waters. Results indicate that microplastic pollution in Antarctic waters may come from the Antarctic continent as well as southward transport from the ocean at mid- and low latitudes.

Adenoviral Transduction of Dickkopf-1 Alleviates Silica-Induced Silicosis Development in Lungs of Mice.

Silicosis is an occupational disease caused by inhalation of silica dust, which is hallmarked by progressive pulmonary fibrosis associated with poor prognosis. Wnt/ß-catenin signaling is implicated in the development of fibrosis and is a therapeutic target for fibrotic diseases. Previous clinical studies of patients with pneumoconiosis, including silicosis, revealed an increased concentration of circulating WNT3A and DKK1 proteins and inflammatory cells in bronchoalveolar lavage compared with healthy subjects. The present study evaluated the effects of adenovirus-mediated transduction of Dickkopf-1 (Dkk1), a Wnt/ß-catenin signaling inhibitor, on the development of pulmonary silicosis in mice. Consistent with previous human clinical studies, our experimental studies in mice demonstrated an aberrant Wnt/ß-catenin signaling activity coinciding with increased Wnt3a and Dkk1 proteins and inflammation in lungs of silica-induced silicosis mice compared with controls. Intratracheal delivery of adenovirus expressing murine Dkk1 (AdDkk1) inhibited Wnt/ß-catenin activity in mouse lungs. The adenovirus-mediated Dkk1 gene transduction demonstrated the potential to prevent silicosis development and ameliorate silica-induced lung fibrogenesis in mice, accompanied by the reduced expression of epithelia--mesenchymal transition markers and deposition of extracellular matrix proteins compared with mice treated with "null" adenoviral vector. Mechanistically, AdDkk1 is able to attenuate the lung silicosis by inhibiting a silica-induced spike in TGF-ß/Smad signaling. In addition, the forced expression of Dkk1 suppressed silica-induced epithelial cell proliferation in polarized human bronchial epithelial cells. This study provides insight into the underlying role of Wnt/ß-catenin signaling in promoting the pathogenesis of silicosis and is proof-of-concept that targeting Wnt/ß-catenin signaling by Dkk1 gene transduction may be an alternative approach in the prevention and treatment of silicosis lung disease.