A key step in ionosphere modeling is to convert slant total electron content (STEC) to vertical total electron content (VTEC) using an appropriate ionospheric mapping function (MF). This makes the accuracy of the applied MF a major factor affecting the performance of the built ionospheric model. Thus, this study evaluates ionospheric models constructed with three commonly used MFs, i.e., single-layer mapping function (SLM MF), modified single-layer mapping function (MSLM MF), and Klobuchar MF, from different aspects. Results show that the performance of the ionospheric model estimated with MSLM MF is the best, followed by SLM MF and Klobuchar MF, respectively. Compared with global ionosphere maps provided by the international Global Navigation Satellite System (IGSG), the MSLM MF-based ionospheric model achieves the best accuracy and consistency. During high solar activity, the SLM MF-based ionospheric model shows the largest discrepancies, which is up to about 40 TEC unit (TECU), while those of the MSLM MF-based model reduce to 10-15 TECU. Under low solar activity, the differences decrease, with the MSLM MF-based model maintaining the smallest bias and root mean square (RMS), which are -1.43 TECU and 2.48 TECU, respectively. The largest errors appear in equatorial regions (+/- 15 degrees latitude), where strong ionospheric gradients exist. Over oceanic regions, the MSLM MF-based ionospheric model still performs best, keeping bias smaller than 5 TECU and RMS smaller than 6 TECU, while the errors of the SLM MF-based ionospheric model can reach 15 TECU. Self-consistency assessments further confirm the stability of the MSLM MF-based ionospheric model, with bias and RMS below 1.0 TECU and 2.0 TECU, significantly outperforming those of the SLM MF-based and Klobuchar MF-based ionospheric models. Furthermore, the single-frequency precise point positioning tests also indicate that MSLM MF-based ionospheric corrections yield the best positioning accuracy, with horizontal and vertical errors typically ranging from 0.2-0.7 m and 0.4-1.0 m, respectively. Overall, the MSLM MF demonstrates the most reliable and consistent performance in ionospheric modeling under varied solar conditions, across diverse regions, and according to multiple metrics.

Zostera japonica beds have declined substantially along the coast of China, highlighting the need for targeted and effective restoration planning. This study develops a restoration roadmap that supports China’s carbon neutrality goals by addressing three key questions: where restoration should occur, when it should be implemented, and which methods should be used. Field surveys, satellite remote sensing, genetic data, and species distribution modelling were integrated to identify restoration opportunities under current and future climate conditions. The results indicate that northern China, particularly the Bohai Sea region, contains the largest extent of suitable and persistent habitat, whereas several southern populations have experienced substantial bed degradation. A rule-based restoration decision framework combined seagrass bed decline and genetic diversity to recommend region-specific restoration strategies across the species range. The phased framework prioritizes areas suitable under current and 2050s conditions, particularly those projected to remain suitable by the 2100s, while treating areas becoming suitable mainly by the 2100s as long-term adaptive reserves. By the 2100s, approximately 103,371 ha of potential suitable habitat is projected, corresponding to an estimated potential carbon stock of 10.86 Tg C. These findings provide a spatially explicit framework for improving Z. japonica restoration planning and evaluating its potential long-term carbon benefits in China.

Amidst global climate change, the escalating atmospheric CO2 levels have intensified ocean acidification (OA), significantly impacting the structure and function of marine ecosystems. Seagrass beds, representative nearshore ecosystems, play a pivotal role in carbon sequestration, biodiversity preservation, and nearshore environmental equilibrium. Rhizosphere microorganisms within seagrass beds, essential components of the ecosystem, drive material cycling and energy flow. Their community structure and functions demonstrate heightened sensitivity to environmental variations. While previous studies have primarily focused on the effects of ocean acidification on seagrass hosts, limited attention has been given to the rhizosphere. Therefore, this study selected Zostera japonica as the focal species and systematically evaluated changes in the structure and function of the rhizosphere bacterial community across varying acidification levels (400 ppm, 1,000 ppm, 2,000 ppm CO2) within an ocean acidification context. The results revealed a significant decline in the richness and diversity of the rhizosphere bacterial community under acidification, accompanied by shifts in community composition characterized by an increase in the relative abundance of Bacteroidota and Tenacibaculum with escalating acidification levels. In high acidification conditions, bacterial network interactions exhibited a trend toward simplification; yet the number of key taxonomic units increases, and there was a shift in community assembly from stochastic to deterministic processes. Functional predictions indicated the enhancement of microbial carbon sequestration and nitrogen fixation under acidification, while denitrification and specific sulfur metabolism pathways were inhibited. This implies that in acidified environments, the rhizosphere bacterial community may enhance carbon and nitrogen fixation to uphold nutrient supply. IMPORTANCE:Against the background of escalating global climate change and ocean acidification, seagrass beds, as crucial blue carbon sink ecosystems, face formidable challenges to their ecological functions and stability. Rhizosphere microorganisms of seagrasses, serving as the "second genome" of the seagrass host, play a central role in material cycling, nutrient supply, and system stability within seagrass beds. They are a key biological component that supports seagrass adaptation to environmental changes. Therefore, investigating the response and adaptation mechanisms of seagrass rhizosphere bacterial communities under ocean acidification is essential for deepening our understanding of the stability and resilience of seagrass bed ecosystems.

Zostera japonica mainly lives in the intertidal zone and is susceptible to fluctuations in abiotic stresses, making it an excellent natural model for studying plant response mechanisms in intertidal environments. Aquaporins (AQPs) play important roles in water uptake, growth and development, and stress regulation. However, studies on the functions of the AQPs of Z. japonica (ZjAQPs) in response to intertidal environments have not been reported. In this study, we identified 22 AQPs in Z. japonica. Phylogenetic analysis revealed that ZjAQPs can be divided into four subfamilies: PIP, TIP, NIP and SIP. Analysis of the cis-acting elements suggested that ZjAQPs may be responsive to stresses. The subcellular localisation of ZjAQPs in tobacco revealed that they functioned predominantly in the membrane system. Transcript expression revealed that ZjAQPs were specifically expressed in various tissues and presented complex responses to environmental variables. Furthermore, transgenic Overexpression in yeast and Arabidopsis revealed that ZjNIP2-1, ZjSIP2-3, ZjPIP1-3, and ZjTIP1-3 play pivotal roles in adaptation to drought and salinity stress. Unlike the AQP subfamily of other higher plants, NIPs and SIPs may play important roles in Z. japonica. The information provided here will help to understand the precise role of AQP in Z. japonica adaptation to intertidal environments.

Microbial community assembly and interactions are pivotal research areas within microbial ecology, yet relevant studies in seagrass rhizospheres and phyllosphere remain relatively scarce. In this study, we utilized high-throughput sequencing technology to investigate the microbial communities in different periods and microhabitats (rhizosphere and phyllosphere) of two seagrass species (Zostera marina and Phyllospadix iwatensis). Our findings suggest that microhabitats have a more pronounced impact on the composition of seagrass-associated microbial communities compared to periods and species. Further investigations reveal that the phyllosphere microbial community exhibits a more intricate co-occurrence network and interactions than the rhizosphere microbial community. Keystone taxa show distinct functional roles in different microhabitats of seagrasses. Additionally, we observed that differences in seagrass microhabitats influence community assembly, with the rhizosphere microbial community being more influenced by deterministic processes (heterogeneous selection) compared to the phyllosphere. These findings contribute to our understanding of the intricate interactions between seagrasses and their associated microbial communities, providing valuable insights into their distribution patterns and microhabitat preferences.IMPORTANCEStudying the community structure and assembly of different microhabitats in seagrass beds contributes to revealing the complexity and dynamic processes of seagrass ecosystems. In the rhizosphere microhabitat of seagrasses, microbial communities may assist in disease resistance or enhance nutrient uptake efficiency in seagrasses. On the other hand, in the microhabitat on the surface of seagrass blades, microorganisms may be closely associated with the physiological functions and nutrient cycling of seagrass blades. Therefore, understanding the structure and assembly mechanisms of rhizosphere and phyllosphere microbial communities is crucial for exploring the interactions between seagrass and microbial communities, as well as for enhancing our comprehension of the stability and resilience of seagrass bed ecosystems.

Increased ultraviolet-B (UVB) radiation due to human activities poses a considerable threat to all exposed organisms. While sex-related differences in stress responses have been observed in many plant species, little is known about whether such differences exist in macroalgae. In this study, we investigated the physiological, transcriptomic, and metabolomic responses of male and female Neoporphyra haitanensis under UVB stress and subsequent recovery. The physiological results indicated that UVB stress strongly inhibited the photosynthetic pigment content and activity in females compared to those in males. Consequently, females exhibited higher levels of reactive oxygen species (ROS) and malondialdehyde (MDA) production under UVB stress and recovery. In contrast, males exhibited stronger antioxidant enzyme activity to alleviate the oxidative stress under UVB stress. Transcriptomic analysis revealed that UVB caused a greater downregulation of genes related to pigment synthesis, photosystems, and carbon fixation in females, including genes encoding magnesium protoporphyrin IX methyltransferase (ChlM), phycoerythrin (PE), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Furthermore, males possessed a stronger photosynthetic recovery capacity, as a greater number of photosynthesis-related genes were significantly upregulated in males after recovery. Under UVB stress, the expression of genes encoding key enzymes involved in glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle was higher in males than in females, indicating a stronger energy metabolism capacity in males. Metabolomic data emphasized the protective role of nonenzymatic antioxidants, particularly flavonoids, with females accumulating more methylated flavonoids and flavonoid glycosides after recovery than males. Overall, these findings highlight sex-related differences in photosynthesis, energy metabolism, and antioxidant regulation in N. haitanensis under UVB stress and recovery. These results contribute to our understanding of how sex differences in macroalgae influence their population survival under increased UVB radiation and provide insights into their potential adaptive responses to ongoing climate change.

Global climate change has led to increased ultraviolet-B (UVB) radiation, which is now a major global environmental issue that poses significant threats to ecosystems. Zostera japonica, a higher plant inhabiting the intertidal zone, is particularly impacted by this increase in UVB radiation. Furthermore, its unique evolutionary history has endowed Z. japonica with distinct characteristics that differentiate its response to environmental changes from those of other marine and terrestrial plants. However, the specific response mechanisms of Z. japonica to elevated levels of UVB radiation are not fully understood. Therefore, we investigated the response mechanism of Z. japonica to varying doses of increased UVB radiation by integrating the physiological responses with transcriptomic and metabolomic analyses. The results revealed that excessive reactive oxygen species (ROS) were key substances induced by increased UVB radiation and that photosynthesis was significantly inhibited. To mitigate these adverse effects, the expression levels of genes related to antioxidants and UV-absorbing compounds, including flavonoids (PAL, 4CL, CHS, CHI, F3H) and antioxidant enzymes (DHAR, MDHAR, APX), were upregulated. The increased synthesis of these compounds serves to scavenge accumulated ROS and absorb UV radiation. Notably, flavonoids are the preferred compounds synthesized by Z. japonica, in contrast to other plant species. In addition, the weighted gene coexpression network analysis (WGCNA) method was employed to identify genes that may play important roles in the response of Z. japonica to increased UVB radiation. The results of this study provide new insights into the potential mechanisms of the response of Z. japonica to increased UVB radiation and serve as important references for elucidating the environmental adaptation mechanisms of intertidal seagrasses.

In single-frequency precise point positioning (SF-PPP), the ionospheric delays provided by global ionosphere maps (GIMs) are in the vertical direction. Therefore, an ionospheric mapping function is applied to convert the vertical direction to the slant one. However, the performance of mapping functions (MF) applied in SF-PPP under different solar activities is unknown. Meanwhile, understanding their performance can help us better improve the accuracy of the ionospheric mapping function. For this purpose, three traditional ionospheric mapping functions, such as the standard single-layer model mapping function (SLM MF), the modified single-layer model mapping function (MSLM MF), and the Klobuchar MF, are evaluated. Additionally, the mapping function named SGG MF, which considers the effect of ionospheric gradients, is also assessed. The positioning results indicate that the SGG MF has an improvement of (50.3 %, 37.3 %), (31.7 %, 23.4 %), and (16.8 %, 13.3 %) compared with Klobuchar MF, SLM MF, and MSLM MF during the year (2014, 2021), respectively. The mean positioning errors of SLM MF, MSLM MF, and SGG MF are about (0.20 m, 0.05 m), (0.25 m, 0.10 m), and (0.30 m, 0.10 m) smaller than that of Klobuchar MF over high-/mid- latitude during the year (2014, 2021), while the values are (0.25 m, 0.20 m), (0.40 m, 0.35 m), and (0.55 m, 0.50 m) over low-latitude region. Furthermore, the correlation coefficients between positioning results and solar activities are (0.114, 0.354), (0.058, 0.324), (0.098, 0.295), and (0.235, 0.271) for Klobucahr MF, SLM MF, MSLM MF, and SGG MF during corresponding year. (c) 2024 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Exosomes, released from diverse cells as nanoscale lipid bilayer vesicles, mediate intercellular communication and participate in various physiological and pathological processes. Thereinto, tumor-derived exosomes (T-EXOs) with molecular cargoes of parent tumor cells act as attractive biomarkers for tumor liquid biopsy. The amount of T-EXOs and their levels of contained specific proteins and nucleic acids are closely associated with cancer burden and classification. Nevertheless, the nanoscale size and relatively low abundance of exosomes, as well as complex body liquid matrix pose daunting challenges for efficient isolation and sensitive detection of T-EXOs. Biosensing as fast, convenient and accurate method, has been widely employed for the detection of biomarkers over the past decades. Among them, electrochemical sensors can sensitively detect biomarkers by measuring of the change of electrical signal caused by oxidation or reduction at the working electrode surface. This review aims to summarize the recent advance in electrochemical biosensors for quantification, and protein and RNA analysis of exosomes. Further, challenges and future perspectives for exosome-based liquid biopsy have been discussed.

AbstractThis study applies the zero‐differenced integer ambiguity method, named PPP‐Fixed, to extract real‐time ionospheric data and eliminate the latencies of rapid/final Global Ionosphere Maps (GIMs). The PPP‐Fixed method is also used to derive ionospheric data for post‐processed GIM generation, named SGG Post‐GIM, combined with low earth orbit satellite data. The obtained hardware delays are applied to revise real‐time ionospheric data. Meanwhile, the estimated multi‐source ionospheric model is regarded as historical data to estimate an ionospheric prediction model for constraint using the semi‐parameter model. Then, the Kalman filter is employed to estimate the parameters to generate real‐time GIM. Finally, the accuracy of estimated real‐time GIM, named SGG RT‐GIM, and SGG Post‐GIM is assessed. During the experimental period, the mean differences of SGG Post‐GIM and SGG RT‐GIM relative to GIMs provided by the international Global Navigation Satellite System service, named IGSG, are −0.46 and −0.57 Total Electron Content Unit (TECU), respectively. The corresponding Root Mean Square (RMS) values are 1.64 and 3.08 TECU. Over the test period, the mean positioning errors of the single‐frequency precise point positioning corrected by IGSG, SGG Post‐GIM, SGG RT‐GIM, and Klobuchar model are 0.14, 0.19, 0.21, and 0.25 m in the horizontal direction, respectively, while the corresponding errors are 0.36, 0.33, 0.38, and 0.64 m in the up direction. Further, the mean biases of experimental days for the self‐consistency assessment are 0.06, −0.01, and −0.07 TECU for IGSG, SGG Post‐GIM, and SGG RT‐GIM, respectively. The corresponding RMS values are 1.19, 1.15, and 1.57 TECU.

Ocean acidification is one of the major global environmental problems facing humankind today, and it has far-reaching impacts on marine organisms and the entire marine ecosystem. Zostera japonica, an important supporting species of intertidal seagrass beds, exhibits high photosynthetic productivity and plays an important role in the carbon cycle of nearshore waters. However, little is known about the characteristics, processes, and mechanisms of its response to ocean acidification. In this study, we conducted a 120-day acidification experiment in Z. japonica; here, plants underwent four leaf regeneration cycles to reveal the response mechanism of Z. japonica to ocean acidification (OA). We found that acidification significantly affected the seedling stage of Z. japonica, impacting leaf regeneration cycles by altering physiological and molecular responses. In one leaf regeneration cycle, the short-term exposure to CO2 affected the seagrass parameters, such as the regulation of inorganic carbon uptake modes and the regulation of photosynthesis between the dark and light reactions, with the potential to affect the carbon sinks of the marine organisms. The long-term effects on the regulation of antioxidant enzymes and antioxidant metabolites, caused an improvement in the marine life adaptation to OA. In a comparison of the different leaf regeneration cycles, the response pattern of Z. japonica showed an offset of the acidification during the short cycles and an adaption to the acidification during the long cycles. This study revealed the response mechanism of Z. japonica to OA at different time scales and could provide a theoretical basis for accurately assessing the impact of OA on seagrass and the entire seagrass bed ecosystem.

The increase in UV-B radiation at the Earth’s surface due to the depletion of the stratospheric ozone layer is a notable facet of contemporary climate change patterns. The macroalgae inhabiting the intertidal zone exhibit a diverse array of adaptive strategies to cope with dramatic environmental changes. In this study, we integrated physiological, transcriptomic and metabolomic data from energy metabolism perspective to elucidate the responses and recovery mechanism of N. haitanensis to UV-B radiation exposure. UV-B radiation has a harmful impact on the photosynthetic performance of N. haitanensis. However, an increase in photosynthetic performance and upregulated expression of genes related to photosynthesis were observed during recovery, suggesting that the effect of UV-B on N. haitanensis was dynamic photoinhibition. Recovery experiments revealed that most genes and metabolites related to glycolysis were significantly upregulated, suggesting that glycolysis was activated to promote energy production. In addition, the TCA cycle was also activated, as evidenced by the increase in key substances and the upregulated expression of key enzyme-encoding genes during recovery. Correspondingly, ATP was also abundantly accumulated. These results suggested that the TCA cycle provided ATP for N. haitanensis to repair UV-B damage. Meanwhile, amino acid metabolism was enhanced during recovery as a source of intermediates for the TCA cycle. Therefore, photosynthesis, glycolysis, the TCA cycle, and amino acid metabolism synergistically cooperate to provide material and energy for recovery after UV-B radiation. This study is important for understanding the adaptive strategies of intertidal macroalgae in response to UV-B radiation.

Endophytic bacteria have a complex coevolutionary relationship with their host macroalgae. Dioecious macroalgae are important producers in marine ecosystems, but there is still a lack of research on how sex influences their endophytic bacteria. In this study, the endophytic bacterial communities in male and female S. thunbergii and their reproductive tissues (receptacles) were compared using culture methods and high-throughput sequencing. The endophytic bacterial communities detected by the two methods were different. Among the 78 isolated strains, the dominant phylum, genus, and species were Bacillota, Alkalihalobacillus, and Alkalihalobacillus algicola, respectively, in the algal bodies, while in the receptacles, they were Bacillota, Vibrio, and Vibrio alginolyticus. However, 24 phyla and 349 genera of endophytic bacteria were identified by high-throughput sequencing, and the dominant phylum and genus were Pseudomonadota and Sva0996_ Marine_ Group, respectively, in both the algal body and the receptacles. The two methods showed similar compositions of endophytic bacterial communities between the samples of different sexes, but the relative abundances of dominant and specific taxa were different. The high-throughput sequencing results showed more clearly that the sex of the host alga had an effect on its endophyte community assembly and a greater effect on the endophytic bacterial community in the receptacles. Moreover, most specific bacteria and predicted functional genes that differed between the samples from the males and females were related to metabolism, suggesting that metabolic differences are the main causes of sex differences in the endophytic bacterial community. Our research is the first to show that host sex contributes to the composition of endophytic bacterial communities in dioecious marine macroalgae. The results enrich the database of endophytic bacteria of dioecious marine macroalgae and pave the way for better understanding the assembly mechanism of the endophytic bacterial community of algae.

Breast cancer is a malignant tumor, with various subtypes showing different behaviors. Endogenous H2O2 is an important marker of tumor progression, which makes it important to study the relationship between breast cancer subtypes and H2O2 for pathogenesis and treatment strategies, but this has rarely been reported so far. In this work, we constructed a three-dimensional (3D) electrochemiluminescence (ECL) sensing platform for the detection of H2O2 released from two typical subtypes of breast cancer cells (MCF-7 cells for luminal A-type and MDA-MB-231 cells for three negative breast cancers, TNBCs). To adequately replicate the tumor microenvironment, the peptide hydrogel was introduced as a scaffold for 3D cell culture. The titanium foam (TF) was used as a 3D electrode to better match the 3D culture substrate. N-(4-Aminobutyl)-N-ethylisoluminol (ABEI) was selected as the ECL emitter and assembled into the peptide hydrogel by hydrogen bonding and π-stacking, which resulted in a stable and homogeneous distribution of ABEI along the hydrogel fibers. Furthermore, basic amino acids were introduced to provide alkaline microenvironment for ABEI. Therefore, ABEI exhibited high ECL efficiency, resulting in a high sensitivity with an ultralow detection limit of 0.023 nM (S/N = 3) for H2O2 of the proposed ECL biosensor. MCF-7 and MDA-MB-231 cells were cultured in a 3D peptide hydrogel/ABEI/TF electrode, respectively, and endogenous H2O2 was successfully monitored. A notably significant difference of H2O2 released between MDA-MB-231 cells and MCF-7 cells without stimulation but similar extra release with stimulation were observed. These findings may help understand the physiological mechanisms behind the various subtypes and reactive oxygen species (ROS)-related treatment for breast cancer.

Background Microorganisms play pivotal roles in seagrass ecosystems by facilitating material and elemental cycling as well as energy flux. However, our understanding of how seasonal factors and seagrass presence influence the assembly of bacterial communities in seagrass bed sediments is limited. Employing high-throughput sequencing techniques, this study investigates and characterizes bacterial communities in the rhizosphere of eelgrass (Zostera marina) and the bulk sediments across different seasons. The research elucidates information on the significance of seasonal variations and seagrass presence in impacting the microbial communities associated with Zostera marina. Results The results indicate that seasonal variations have a more significant impact on the bacterial community in seagrass bed sediments than the presence of seagrass. We observed that the assembly of bacterial communities in bulk sediments primarily occurs through stochastic processes. However, the presence of seagrass leading to a transition from stochastic to deterministic processes in bacterial community assembly. This shift further impacts the complexity and stability of the bacterial co-occurrence network. Through LEfSe analysis, different candidate biomarkers were identified in the bacterial communities of rhizosphere sediments in different seasons, indicating that seagrass may possess adaptive capabilities to the environment during different stages of growth and development. Conclusions Seasonal variations play a significant role in shaping these communities, while seagrass presence influences the assembly processes and stability of the bacterial community. These insights will provide valuable information for the ecological conservation of seagrass beds.

Multiple regulatory pathways of Zostera japonica to salt stress were identified through growth, physiological, transcriptomic and metabolomic analyses. Seagrasses are marine higher submerged plants that evolved from terrestrial monocotyledons and have fully adapted to the high saline seawater environment during the long evolutionary process. As one of the seagrasses growing in the intertidal zone, Zostera japonica not only has the ability to quickly adapt to short-term salt stress but can also survive at salinities ranging from the lower salinity of the Yellow River estuary to the higher salinity of the bay, making it a good natural model for studying the mechanism underlying the adaptation of plants to salt stress. In this work, we screened the growth, physiological, metabolomic, and transcriptomic changes of Z. japonica after a 5-day exposure to different salinities. We found that high salinity treatment impeded the growth of Z. japonica, hindered its photosynthesis, and elicited oxidative damage, while Z. japonica increased antioxidant enzyme activity. At the transcriptomic level, hypersaline stress greatly reduced the expression levels of photosynthesis-related genes while increasing the expression of genes associated with flavonoid biosynthesis. Meanwhile, the expression of candidate genes involved in ion transport and cell wall remodeling was dramatically changed under hypersaline stress. Moreover, transcription factors signaling pathways such as mitogen-activated protein kinase (MAPK) were also significantly influenced by salt stress. At the metabolomic level, Z. japonica displayed an accumulation of osmolytes and TCA mediators under hypersaline stress. In conclusion, our results revealed a complex regulatory mechanism in Z. japonica under salt stress, and the findings will provide important guidance for improving salt resistance in crops.

In ionosphere modeling, the single-layer height can influence the location of ionospheric pierce points (IPPs) and the mapping function errors, which is regarded as a constant ranging from 350 to 450 km. In this study, according to the relationship between the F2 layer peak height (hmF2) and the single-layer height, the obtained single-layer height was applied to generate global ionosphere maps (GIMs) using ground-based data, named WUHH. In addition, the generated GIMs were used to compare the GIMs provided by the international global navigation satellite system service, named IGSG, and those generated by ground-based data with a height of 450 km, named WUHG. Meanwhile, the single-frequency precise point positioning (SF-PPP) technique and difference of slant total electron content (dSTEC) method were applied for evaluation. Compared with IGSG, the mean bias was about -1.043 and -0.954 total electron content unit (TECU) for WUHG and WUHH, while their corresponding root mean square (RMS) was about 1.699 and 2.527 TECU. The mean 3-D error assessed by the SF-PPP technique was 0.636, 0.695, and 0.595 m for IGSG, WUHG, and WUHH. The positioning errors were reduced by about 6.4% and 14% for WUHH with respect to IGSG and WUHG. Finally, the self-consistency evaluation results showed that the mean bias was 0.107, 0.055, and 0.057 TECU for IGSG, WUHG, and WUHH, while the RMS was 1.609, 1.543, and 1.536 TECU for IGSG, WUHG, and WUHH.

Two new seco-abietane type diterpenoids, named as isodonserra acid A and B (1-2), along with six known compounds, angustanoic acid A (3), epipalustric acid (4), raserrane (5), 7-methoxy coumarin (6), umbelliferone (7), and (-)-loliolide (8), were obtained from the leaves of Isodon serra. The new structures of compounds 1 and 2 were elucidated by analysing their 1D NMR, 2D NMR and HR-ESI-MS spectra. Compounds 1-8 showed moderate hepatoprotective activity against APAP-induced HepG2 cell injury with a cell survival rate from 50.4% to 78.7% at a concentration of 10 μM (p < .001, bicyclol as the positive drug, 71.7%).

Seed development is a crucial phase in the life cycle of seed-propagated plants. As the only group of angiosperms that evolved from terrestrial plants to complete their life cycle submerged in marine environments, the mechanisms underlying seed development in seagrasses are still largely unknown. In the present study, we attempted to combine transcriptomic, metabolomic, and physiological data to comprehensively analyze the molecular mechanism that regulates energy metabolism in Zostera marina seeds at the four major developmental stages. Our results demonstrated that seed metabolism was reprogrammed with significant alteration of starch and sucrose metabolism, glycolysis, the tricarboxylic acid cycle (TCA cycle), and the pentose phosphate pathway during the transition from seed formation to seedling establishment. The interconversion of starch and sugar provided energy storage substances in mature seeds and further acted as energy sources to support seed germination and seedling growth. The glycolysis pathway was active during Z. marina germination and seedling establishment, which provided pyruvate for TCA cycle by decomposing soluble sugar. Notably, the biological processes of glycolysis were severely inhibited during Z. marina seed maturation may have a positive effect on seed germination, maintaining a low level of metabolic activity during seed maturation to preserve seed viability. Increased acetyl-CoA and ATP contents were accompanied with the higher TCA cycle activity during seed germination and seedling establishment, indicating that the accumulations of precursor and intermediates metabolite that can strengthen the TCA cycle and facilitate energy supply for Z. marina seed germination and seedling growth. The large amount of oxidatively generated sugar phosphate promotes fructose 1,6-bisphosphate synthesis to feed back to glycolysis during seed germination, indicating that the pentose phosphate pathway not only provides energy for germination, but also complements the glycolytic pathway. Collectively, our findings suggest these energy metabolism pathways cooperate with each other in the process of seed transformation from maturity to seedling establishment, transforming seed from storage tissue to highly active metabolic tissue to meet the energy requirement seed development. These findings provide insights into the roles of the energy metabolism pathway in the complete developmental process of Z. marina seeds from different perspectives, which could facilitate habitat restoration of Z. marina meadows via seeds.

The formation of epiphytic bacterial communities on macroalgae is closely related to host identity, but the effects of tissue location and sex of the host alga on this process, especially the relative contributions of these two factors, have not been studied. Here, the epiphytic bacterial community on three different tissues (tip, receptacle and holdfast) of male and female Sargassum thunbergii in the intertidal zone of Qingdao was investigated using high-throughput sequencing, and the results revealed obvious tissue and sex specificity of the epiphytic bacteria and significant differences from seawater bacterial samples. The biodiversity indexes, specific bacteria, biomarkers, indicator taxa and predicted function of epiphytic bacteria differed significantly among tissues of S. thunbergii and between sexes for the same tissue, confirming that both algal tissue location and sex impacted epiphytic bacterial community assembly on S. thunbergii. Additionally, β-diversity analysis showed that tissue location contributed more than host sex to epiphytic bacterial community structure, and the contributions of these two factors varied among tissues. Sex contributed less to epiphytic bacteria on the holdfast than on the tip and receptacle. Furthermore, the tissue and sex specificity of epiphytic bacteria on S. thunbergii were likely related mainly to host metabolism but also to the interaction between bacteria and algae and adaptability to the environment. This study shed light on the drivers of macroalga-associated bacterial community structure and broaden our understanding of the relationship between macroalgae and their epiphytic bacteria.