Review of Allelopathy in Green Tides: The Case of Ulva prolifera in the South Yellow Sea.

The proliferation of large green macroalgae in marine environments has led to the occurrence of green tides, particularly in the South Yellow Sea region of China, where Ulva prolifera has been identified as the primary species responsible for the world's largest green tide events. Allelopathy among plants is a critical factor influencing the dynamics of green tides. This review synthesizes previous research on allelopathic interactions within green tides, categorizing four extensively studied allelochemicals: fatty acids, aldehydes, phenols, and terpenes. The mechanisms by which these compounds regulate the physiological processes of green tide algae are examined in depth. Additionally, recent advancements in the rapid detection of allelochemicals are summarized, and their potential applications in monitoring green tide events are discussed. The integration of advanced monitoring technologies, such as satellite observation and environmental DNA (eDNA) analysis, with allelopathic substance detection is also explored. This combined approach addresses gaps in understanding the dynamic processes of green tide formation and provides a more comprehensive insight into the mechanisms driving these phenomena. The findings and new perspectives presented in this review aim to offer valuable insights and inspiration for researchers and policymakers.

Spatio-temporal distribution of micropropagules of green algae along the Jiangsu coast.

We conducted continuous monitoring at 13 stations along the Jiangsu coast to study the spatiotemporal distribution, population succession of micropropagules of green algae, and their impact on the outbreak of Southern Yellow Sea green tide. The study discovered that: 1) Green algae micropropagules had obvious temporal and spatial distribution and population changes along the Jiangsu coast. The monthly average abundance of micropropagules of green algae at station BH1, which was the high-value area, was 1230 inds/L. Station XS2 had the second-highest value area. Green algae micropropagules had an average monthly abundance of 836 inds/L. Between stations XS2 and BH1, the amount of green algae micropropagules steadily declined in comparison to other stations. The abundance was greatest from spring to early summer, and Ulva prolifera micropropagules predominated; 2) Compared with salinity, temperature had a more obvious effect on the micropropagules of green algae along the Jiangsu coast; 3) Green algae micropropagules on the Jiangsu coast could be a potential additional source on the outbreak of Southern Yellow Sea green tide. More data are needed to corroborate this conclusion. For the purpose of preventing and managing green tide, it is crucial to investigate the Southern Yellow Sea's potential supplementary source. This study analyzes the spatiotemporal distribution and population changes of green algae micropropagules along the Jiangsu coast, as well as their impact on green tide outbreaks, providing scientific data support for the prevention and control of green tides in the Southern Yellow Sea.

Mixed acid treatment for removal of green macroalgae from Neopyropia aquaculture nets: Field experiment in the Subei Shoal, China.

To develop an effective method to eliminate green macroalgae attached to Neopyropia aquaculture nets, we explored the influence of mixed acid solution on the photosynthetic fluorescence characteristics of Ulva spp. (green macroalgae) and Neopyropia yezoensis (red macroalgae) from Dafeng and Rudong aquaculture areas in Jiangsu Province, China. Treatment with mixed acid solution (0.0475 % hydrochloric acid:citric acid (pH 2.0) at a ratio of 4:3) for 60 s caused death of Ulva spp., but did not affect N. yezoensis. Additionally, a mixed acid solution effectively eliminated green macroalgae from Neopyropia aquaculture rafts and the marine environment remained unaffected. Hence, the application of mixed acid solution treatment has demonstrated significant efficacy in eradicating green macroalgae adhered to Neopyropia aquaculture rafts, thus presenting a promising strategy for mitigating green macroalgae proliferation in Neopyropia aquaculture areas and curbing their contribution to green tides.

Overwintering and summer survival of Ulva prolifera in sediments: Indoor simulation of temperature impacts.

Green tides, a globally prevalent marine ecological anomaly observed in coastal regions, have received substantial attention. However, there is limited research on the burial of Ulva prolifera in sediments during the late stages of green tide outbreaks. This study investigates the effect of temperature on U. prolifera buried in sediment over 30 days. The measurements included the length, biomass, relative growth rate, chlorophyll composition and maximum quantum yield (Fv/Fm) of PS II at different stages. The results indicate that at -20 °C, numerous seedlings emerged after 14 days of recovery culture, suggesting the release of spores or gametes; survival was possible from -2 °C to 15 °C; but at 20 °C and 30 °C, all U. prolifera died. The U. prolifera buried in sediment during the late stage of green tide outbreaks may serve as one of the sources for the subsequent year's green tide eruption. This research provides insights into the origins of green tide outbreaks in the southern Yellow Sea.

Spatiotemporal dynamics of bacterioplankton communities in the estuaries of two differently contaminated coastal areas: Composition, driving factors and ecological process.

Seasonal variations of environmental parameters usually lead to considerable changes in microbial communities. Nevertheless, the specific response patterns of these communities in coastal areas subjected to different levels of contamination remain unclear. Our results revealed notable fluctuations in the bacterioplankton community both seasonally and spatially, with seasonal variations being particularly significant. The diversity and composition of bacterioplankton communities in the estuaries varied significantly across seasons and between seas. Some bacterial phyla that were highly abundant in the dry season (e.g., Patescibacteria and Epsilonbacteraeota) were almost absent in the wet season. Furthermore, the network analysis revealed that the bacterioplankton networks were more complex during the wet season than in the dry season. In the wet season, the estuarine bacterioplankton network in the Yellow Sea region was more complex and stable, while the opposite was true in the dry season. According to the neutral community model, stochastic processes played a more significant role in the formation of bacterioplankton communities during the wet season than during the dry season. Estuarine bacterioplankton communities in the Yellow Sea region were more affected by stochastic processes compared to those in the Bohai Sea. In summary, in the estuaries of two differently contaminated coastal areas, the seasonal increase in nutrient levels enhanced the deterministic processes and network complexity of the bacterioplankton communities.

Mechanisms of harmful effects of Microcystis aeruginosa on a brackish water organism Moina mongolica based on physiological and transcriptomic responses.

To investigate the detrimental impacts of cyanobacterial bloom, specifically Microcystis aeruginosa, on brackish water ecosystems, the study used Moina mongolica, a cladoceran species, as the test organism. In a chronic toxicology experiment, the survival and reproductive rates of M. mongolica were assessed under M. aeruginosa stress. It was observed that the survival rate of M. mongolica fed with M. aeruginosa significantly decreased with time and their reproduction rate dropped to zero, while the control group remained maintained stable and normal reproduction. To further explore the underlying molecular mechanisms of the effects of M. aeruginosa on M. mongolica, we conducted a transcriptomic analysis on newly hatched M. mongolica cultured under different food conditions for 24 h. The results revealed significant expression differences in 572 genes, with 233 genes significantly up-regulated and 339 genes significantly down-regulated. Functional analysis of these differentially expressed genes identified six categories of physiological functional changes, including nutrition and metabolism, oxidative phosphorylation, neuroimmunology, cuticle and molting, reproduction, and programmed cell death. Based on these findings, we outlined the basic mechanisms of microcystin toxicity. The discovery provides critical insights into the mechanisms of Microcystis toxicity on organisms and explores the response mechanisms of cladocerans under the stress of Microcystis.

Revolutionizing early-stage green tide monitoring: eDNA metabarcoding insights into Ulva prolifera and microecology in the South Yellow Sea.

Green tides, characterized by excessive Ulva prolifera blooms, pose significant ecological and economic challenges, especially in the South Yellow Sea. We successfully employed 18S environmental DNA (eDNA) metabarcoding to detect Ulva prolifera micropropagules, confirming the technique's reliability and introducing a rapid green tide monitoring method. Our investigation revealed notable disparities in the eukaryotic microbial community composition within Ulva prolifera habitats across different regions. Particularly, during the early stages of the South Yellow Sea green tide outbreak, potential interactions emerged between Ulva prolifera micropropagules and certain previously undocumented microorganisms from neighboring waters. These findings enhance our comprehension of early-stage green tide ecosystem dynamics, underscoring the value of merging advanced molecular techniques with conventional ecological methods to gain a comprehensive understanding of the impact of green tide on the local ecosystem. Overall, our study advances our understanding of green tide dynamics, offering novel avenues for control, ecological restoration, and essential scientific support for sustainable marine conservation and management.

Responses of photosynthesis-related genes in Sargassum horneri to high temperature stress.

Golden tide outbreak threatened the marine ecological environment. Sargassum horneri is a single dominant species of the Yellow Sea golden tide, which growth and development are affected by changes in sea water temperature. This study investigated the photosynthetic physiology of copper algae and found that the growth rate, chlorophyll a content, carotenoid content, Fv/Fm, and maximum electron transfer efficiency were significantly reduced, indicating that Sargassum horneri was under stress under high temperature. In this study, high-throughput sequencing was used to analyze the response mechanisms of photosynthesis-related genes in S. horneri under high temperature stress. The results showed that most of the photosynthesis-related genes in S. horneri were downregulated and photosynthesis was inhibited under high temperature stress. However, the expression levels of ferredoxin, ferredoxin-NADP reductase, light-harvesting protein complexes, and oxygen-evolving complex genes were significantly upregulated (P ≤ 0.05) after five days of high temperature treatment. This study found that photosynthesis related genes play a crucial role in regulating the photosynthetic response of S. horneri to high temperature stress.

Efficacy of different durations of antifungal prophylaxis with nebulized amphotericin B after lung transplantation: a retrospective cohort study.

Background: Nebulized amphotericin B (NAB) is recommended for preventing invasive fungal diseases (IFDs) after lung transplantation. However, the optimal duration of NAB treatment is still unknown. This study aimed to compare the effectiveness of three different durations of antifungal prophylaxis with NAB after lung transplantation: a prolonged course beyond post-transplant 3 months, a medium course of 2 weeks to 3 months, and a short course of less than 2 weeks. Methods: This a single-center retrospective cohort study analyzed 333 patients who underwent lung or heart-lung transplantation between January 2015 and November 2021. Results: A prolonged course of NAB treatment was associated with a significantly lower incidence of IFDs (12.6%) at 1 year post-transplant compared with a short (50.9%) or a medium course (28.0%) (P<0.001). There was no significant difference in the rates of adverse effects among the three durations of NAB treatment (P>0.05). A prolonged course of NAB treatment was associated with a significantly higher 1-year survival rate (94.7%) compared with a short (36.8%) or a medium course (72.0%) (P<0.001). Conclusions: A prolonged course of NAB treatment provided better protection against IFDs than a short or medium course after lung transplantation. Prolonged use of NAB did not significantly increase the incidence of adverse effects.

Use of citric acid-activated chlorine dioxide to control Ulva prolifera.

Since 2007, green tides have occurred almost every year in the Yellow Sea, and a method to prevent them and to control levels of attached Ulva prolifera is urgently needed. In this study, we measured the effects of different concentrations of citric acid-activated chlorine dioxide solution (0, 50, 100, 150, 200, and 250 mg/L of chlorine dioxide) on the morphology (macrostructure and microstructure), chlorophyll a content, chlorophyll b content, carotenoid content, and chlorophyll fluorescence parameters (Fv/Fm, Y (II), NPQ, and ETRmax) of U. prolifera. Micropropagules in the treatment filtrate were cultured to determine whether the solution reduced the number of micropropagules released during the treatment process. The results showed that citric acid-activated chlorine dioxide at the appropriate concentration can be applied to remove U. prolifera from Neopyropia cultivation rafts. Because U. prolifera and its micropropagules died in the 250 mg/L chlorine dioxide group, we recommend that the appropriate concentration of chlorine dioxide for removing green macroalgae is ≥250 mg/L. Our results provide a scientific basis for convenient collection of accurate data for the U. prolifera prevention trial organized by the Ministry of Natural Resources of the People's Republic of China.

Attached Ulva meridionalis on nearshore dikes may pose a new ecological risk in the Yellow Sea.

Green tides have been reported to occur in many sea areas worldwide. In China, most of them are caused by Ulva spp., such as Ulva prolifera and Ulva meridionalis. Green tide algae shed are frequently the initial biomass for the formation of green tide. Human activities and seawater eutrophication are the fundamental causes of the formation of the green tides in the Bohai Sea, Yellow Sea, and South China Sea, but other environmental factors may also have an impact on the shedding of green tide algae, such as typhoons and currents. Algae shedding is divided into artificial shedding and natural shedding. However, few studies have explored the relationship between algal natural shedding and environmental factors. pH, sea surface temperature, and salinity are critical environmental factors affecting the physiological state of algae. Therefore, based on field observations of the shedding of attached green macroalgae in Binhai Harbor, this study assessed the correlation between the shedding rate and environmental factors (pH, sea surface temperature, and salinity). The green algae that shed from Binhai Harbor in August 2022 were all identified as U. meridionalis. The shedding rate range was 0.88% ± 0.11% d-1 to 4.78% ± 1.76% d-1, and was not correlated with pH, sea surface temperature, or salinity; however, the environmental conditions were very suitable for the proliferation of U. meridionalis. This study provided a reference for the shedding mechanism of green tide algae and revealed that with the frequent human activities along the coast, U. meridionalis may pose a new ecological risk in the Yellow Sea.

Root morphological and physiological traits and arbuscular mycorrhizal fungi shape phosphorus-acquisition strategies of 12 vegetable species.

Trait plasticity and integration mediate vegetable adaptive strategies. However, it is unclear how patterns of vegetables in root traits influence vegetable adaptation to different phosphorus (P) levels. Nine root traits and six shoot traits were investigated in 12 vegetable species cultivated in a greenhouse with low and high P supplies to identify distinct adaptive mechanisms in relation to P acquisition (40 and 200 P mg kg-1 as KH2PO4). At the low P level, a series of negative correlations among root morphology, exudates and mycorrhizal colonization, and different types of root functional properties (root morphology, exudates and mycorrhizal colonization) respond differently to soil P levels among vegetable species. non-mycorrhizal plants showed relatively stable root traits as compared to solanaceae plants that showed more altered root morphologies and structural traits. At the low P level, the correlation between root traits of vegetable crops was enhanced. It was also found in vegetables that low P supply enhances the correlation of morphological structure while high P supply enhances the root exudation and the correlation between mycorrhizal colonization and root traits. Root exudation combined with root morphology and mycorrhizal symbiosis to observe P acquisition strategies in different root functions. Vegetables respond highly under different P conditions by enhancing the correlation of root traits. Low P supply could significantly improve the direct and indirect ways of mycorrhizal vegetable crops' root traits axis on shoot biomass, and enhance the direct way of non-mycorrhizal vegetable crops' root traits axis and reduce the indirect way of root exudates.

Morphological ECG subtraction method for removing ECG artifacts from diaphragm EMG.

BACKGROUND: Diaphragmatic electromyographic (EMGdi) is a helpful method to reflect the respiratory center's activity visually. However, the electrocardiogram (ECG) severely affected its weakness, limiting its use. OBJECTIVE: To remove the ECG artifact from the EMGdi, we designed a Morphological ECG subtraction method (MES) based on three steps: 1) ECG localization, 2) morphological tracking, and 3) ECG subtractor. METHODS: We evaluated the MES method against the wavelet-based dual-threshold and stationary wavelet filters using visual and frequency-domain characteristics (median frequency and power ratio). RESULTS: The results show that the MES method can preserve the features of the original diaphragm signal for both surface diaphragm signal (SEMGdi) and clinical collection of diaphragm signal (EMGdi_clinic), and it is more effective than the wavelet-based dual-threshold and stationary wavelet filtering methods. CONCLUSION: The MES method is more effective than other methods. This technique may improve respiratory monitoring and assisted ventilation in patients with respiratory diseases.

Clinical characteristics and treatment strategy of nocardiosis in lung transplant recipients: A single-center experience.

Objective: Nocardia are infrequent pathogens that disproportionately afflict organ transplant recipients. The present study aimed to summarize the clinical manifestations, diagnostic approaches, and treatment strategies of nocardiosis in lung transplant recipients. Methods: This retrospective study reviewed the clinical data of adult lung transplant recipients who were complicated with nocardiosis between January 2018 and December 2021 at the largest lung transplant center in South China. Results: The incidence of nocardiosis was 4.2% (13/316), including 9 cases of pulmonary nocardiosis and 4 disseminated nocardiosis (blood, pulmonary and intracranial). The accuracy in diagnosing nocardiosis was 77.8% by culture and 100% by metagenomic next-generation sequencing (mNGS). Nocardia farcinica was the most common causative pathogen. Trimethoprim-sulfamethoxazole-based combination therapy was administered initially, followed by a single antibiotic as the maintained therapy, lasting for 4-8 months. Conclusions: mNGS is more accurate than culture in diagnosing nocardiosis. Most patients responded well to the antibiotic therapy with combined antibiotics at the initial stage followed by a single antibiotic treatment.

Removable carbon and storage carbon of golden tides.

Due to ever-increasing global warming, ocean acidification, and inshore eutrophication, the outbreak of golden tides with Sargassum horneri has increased in the Yellow sea, where the biomass carbon enters three main carbon pathways: a. Removal of carbon from seawater by salvage, known as removable carbon; b. Biomass carbon is deposited to the seafloor through POC and RDOC through Biological Carbon Pump and Microbial Carbon Pump; c. Re-entering the carbon cycle through the food chain or re-entering the atmosphere through the action of microbes. Estimating carbon fixation (removable carbon) and storage (particulate organic carbon (POC) and refractory dissolved organic carbon (RDOC)) is vital in studying the global carbon cycle. In this research, it was observed that the C content of S. horneri was high, and the utilization rate of dissolved organic carbon (DOC), RDOC, and POC was also high in the eutrophication environment, where only 2.71 % of algal biomass carbon was converted to RDOC, and only 0.20 % converted to POC. The C + N + P combination has a restart effect on the seasonal accumulation of RDOC in relevant sea areas. It is suggested that the salvage and resource utilization should be strengthened to effectively control the golden tide and reduce the substantial economic losses to realize the win-win situation of carbon sink and environmental restoration.

Advances in the research on micropropagules and their role in green tide outbreaks in the Southern Yellow Sea.

The green tide event that occurred in the Southern Yellow Sea in 2007 lasted for 16 years, causing serious economic losses and ecological damage to coastal cities. To address this problem, a series of studies were conducted. However, the contribution of micropropagules to green tide outbreaks remains poorly understood, and the relationship between micropropagules and green algae that are settled nearshore or floating at sea also needs to be further explored. The present study focuses on the identification of these micropropagules in the Southern Yellow Sea and uses the Citespace tool to quantitatively analyze current research hotspots, frontier trends, and development trends. In addition, it examines the micropropagules' life cycle and how it directly affects the green algal biomass and clarifies the temporal and spatial distribution of micropropagules in the entire Southern Yellow Sea. The study also discusses unresolved scientific problems and limitations in the current research on algal micropropagules and provides an outlook on future research directions. We expect to further analyze the contribution of micropropagules to green tide outbreaks and provide data to support comprehensive green tide management.

A review of volatile compounds in edible macroalgae.

Seaweeds (green algae, red algae and brown algae) are rich in nutrients, and incorporating algae into the human diet can provide important health benefits. However, consumer acceptance of food is closely related to its flavor, and in this respect, volatile compounds are key factors. This article reviews the extraction methods and composition of volatile compounds from Ulva prolifera, Ulva lactuca, Sargassum spp. and economically valuable cultured seaweeds such as Undaria pinnatifida, Laminaria japonica, Neopyropia haitanensis and Neopyropia yezoensis. Research found that the volatile compounds of the above seaweeds were composed mainly of aldehydes, ketones, alcohols, hydrocarbons, esters, acids, sulfur compounds, furans and small amounts of other compounds. Volatile compounds such as benzaldehyde, 2-octenal, octanal, ß-ionone and 8-heptadecene have been identified in several macroalgae. This review argues that more research on the volatile flavor compounds of edible macroalgae is required. Such research could aid new product development or widen applications of these seaweeds in the food or beverage sectors.

Temperature and high nutrients enhance hypo-salinity tolerance of the bloom forming green alga, Ulva prolifera.

The response of seaweeds to environmental stressors can be population-specific, and be related to the regime of their habitats. To explore the growth and physiological responses of Ulva prolifera, two strains of this alga (Korean and Chinese strains) were studied under an interaction of temperature (20 and 25 °C), nutrients (low nutrients: 50 µM of nitrate and 5 µM of phosphate; high nutrients: 500 µM of nitrate and 50 µM of phosphate) and salinity (20, 30 and 40 psu). The lowest growth rates of both strains were observed at 40 psu of salinity, independent of temperature and nutrient levels. At 20 °C and low nutrients condition, the carbon: nitrogen (C: N) ratio and growth rate in the Chinese strain were increased by 31.1% and 21.1% at a salinity of 20 psu in comparison to the salinity of 30 psu, respectively. High nutrients decreased the ratio of C:N in both strains with increasing tissue N content. At the same time, high nutrients also increased soluble protein and pigments contents, as well as photosynthetic and growth rates in both strains at the same salinity levels at 20 °C. Under 20 °C and high nutrients conditions, the growth rates and C:N ratio of both strains were significantly decreased with increasing salinity. The pigment, soluble protein and tissue N showed an inverse trend with the growth rate at all conditions. Moreover, the higher temperature of 25 °C inhibited the growth in both strains regardless of nutrients levels. The temperature of 25 °C enhanced the contents of tissue N and pigments in the Chinese strain only at the low nutrients level. The interaction of high nutrients and 25 °C led to the accumulation of tissue N and pigment contents in both strains under all salinity conditions compared to the 20 °C and high nutrients level. The temperature of 25 °C and high nutrients decreased the growth rate in the Chinese strain at both salinities of 30 and 40 psu more than the 20 °C, and low nutrients level at the same salinity. These results suggest that the Ulva blooms caused by the Chinese strain were more impacted at hypo-salinity levels compared to the Korean strain. Eutrophic or high nutrients level enhanced the salinity tolerance in both strains of U. prolifera. There will be a decline of U. prolifera blooms of the Chinese strain at hyper-salinity levels.

Physiological responses of Ampithoe valida and its feeding potential on Ulva prolifera.

Large numbers of Amphipoda feed on floating green tide macroalgae in the Yellow Sea, among which Ampithoe valida has a high abundance in the stable and decline periods. Amphipoda preferentially feed on Ulva. Under different temperatures, salinities, and pH, the physiological responses of A. valida and its feeding potential on Ulva prolifera were investigated, along with its physiological responses during green tide blooms in the Southern Yellow Sea. Ampithoe valida could survive within a temperature range of 5-30 °C, salinity of 5-40, and pH of 4-10. Optimal environmental conditions for growth were temperature 15-25 °C, salinity 10-40, and pH 6-10. At temperatures of 5-30 °C, salinities of 5-35, and pH of 4-9, A. valida could effectively reduce U. prolifera biomass. The feeding ability of A. valida was greatest in 25-30 °C, 10-25 salinity, and neutral seawater, exceeding 5 mg·ind.-1·d-1. During green tide outbreaks in the Southern Yellow Sea from May to August, the monthly average sea surface temperature, salinity, and pH range is 17.5-27.3 °C, 23.8-29.6, and 7.87-8.17, respectively, within which A. valida showed well growth and could effectively reduce U. prolifera biomass. Finally, this study further discussed the possibility of A. valida as a biological method to control green tide.

Application of plasma donor-derived cell free DNA for lung allograft rejection diagnosis in lung transplant recipients.

BACKGROUND: Donor-derived cell-free DNA (dd-cfDNA) has been applied to monitor acute rejection (AR) in kidney and heart transplantation. This study was aimed to investigate the application of dd-cfDNA levels in the diagnosis of AR and chronic lung allograft dysfunction (CLAD) among the lung transplantation recipients (LTRs). METHODS: One hundred and seventy LTRs were enrolled at the First Affiliated Hospital of Guangzhou Medical University between 1 June 2015 and 30 March 2021. Patients were divided into 4 groups: stable group, AR group, infection group and CLAD group. The level of dd-cfDNA was analyzed using target region sequencing and the performance characteristics of dd-cfDNA for diagnosis of AR and CLAD were determined, respectively. RESULTS: Kruskal-Wallis test showed that there were some significant differences in the level of dd-cfDNA (%) among the 4 groups, with p < 0.001. Among them, the level of dd-cfDNA (%) was highest (median 2.17, IQR [1.40-3.82]) in AR group, and higher in CLAD group (median 1.07, IQR [0.98-1.31]), but lower in infection group (median 0.71, IQR [0.57-1.07]) and lowest in stable group (median 0.71, IQR [0.61-0.84]). AUC-ROC curve analysis showed that the threshold of dd-cfDNA for AR was 1.17%, with sensitivity being 89.19% and specificity being 86.47%, and the optimal threshold of 0.89% was determined of CLAD, with sensitivity being 95.00% and specificity of 76.99%. CONCLUSIONS: Plasma dd-cfDNA could be a useful tool for the assessment of lung allograft rejection, including AR and CLAD, and holds promise as a noninvasive biomarker for "allograft injury" in both acute and chronic rejection following lung transplantation.