While phytoplankton are a major component of coastal ecosystems and experience a wide range of oxygen conditions, the survival and physiological responses of common phytoplankton species under hypoxia remain insufficiently understood. To explore these effects, cell densities of the two dinoflagellate species Prorocentrum triestinum and Amphidinium carterae, and the two diatom species Cylindrotheca closterium and Chaetoceros curvisetus-isolated from waters with a dissolved oxygen (DO) concentration of 1.5 mg O-2 L-1-were measured under target DO concentrations of 0.5, 1.0, 1.5, 4.0, and >7.0 mg O-2 L-1. Using these data, the growth rate, net photosynthesis rate, and dark respiration rate of each species were determined. While A. carterae, Cy. closterium, and Ch. curvisetus survived at all tested DO concentrations, P. triestinum survived only at >= 1.0 mg O-2 L-1. The two dinoflagellate species examined here, which possess active swimming ability, exhibited the highest growth rates at >7.0 mg O-2 L-1, whereas the two diatom species examined here showed peak growth rate at 1.5 mg O-2 L-1. Net photosynthesis rates of all four species peaked at 1.5 mg O-2 L-1, while dark respiration rates were highest at >7.0 mg O-2 L-1. These findings suggest that although these phytoplankton species can grow under hypoxic conditions, dinoflagellate species achieve maximal growth at higher oxygen concentrations, possibly due to the energetic demands of motility. This study provides a useful basis for understanding species-specific responses of phytoplankton to varying oxygen conditions in coastal environments.
Prasiola japonica is a freshwater green alga distributed in Northeast Asia. This study investigated the effects of 70% ethanol extract of P. japonica (Pj-EE) under testosterone-induced hair loss conditions using C57BL/6 mice and human dermal papilla (HDP) cells. Topical application of Pj-EE promoted hair regrowth, increased hair length, and enhanced follicular density and activity in vivo. Pj-EE treatment also partially restored hair type distribution by reducing the proportion of zigzag hairs and increasing guard and awl hairs. Although these effects were less pronounced than those observed with minoxidil, consistent improvements were detected across multiple parameters. Mechanistic studies showed that Pj-EE inhibited 5 alpha-reductase activity and reduced dihydrotestosterone (DHT) production in HDP cells, accompanied by downregulation of androgen receptor expression. Additionally, Pj-EE decreased proapoptotic Bax levels while increasing proliferation-associated markers (Ki67 and proliferating cell nuclear antigen) and the anti-apoptotic protein Bcl-2 in a dose-dependent manner. Functionally, Pj-EE enhanced HDP cell proliferation and migration and attenuated testosterone-induced apoptotic responses, indicating improved follicular cell viability under androgen-stimulated conditions. High-performance liquid chromatography analysis based on comparison with an authentic phytol standard identified phytol as a representative constituent of Pj-EE, and its high abundance was associated with 5 alpha-reductase inhibitory activity. Collectively, these findings suggest that Pj-EE may attenuate androgen-responsive hair loss conditions by modulating 5 alpha-reductase/DHT signaling and supporting follicular cell proliferation and survival in a testosterone-induced model.
While gamma-aminobutyric acid (GABA) promotes nutrient accumulation in green microalgae, its effects on marine diatoms-critical aquaculture feed-remain understudied. Understanding the physiological response of diatoms to exogenous GABA is vital for optimizing high-quality feed production. In this study, we investigated the impact of GABA on diatom growth, photosynthetic performance, proximate composition (lipids, proteins, carbohydrates, and fatty acids), and oxidative stress markers of two commonly used feed diatoms Phaeodactylum tricornutum and Chaetoceros muelleri. GABA effects were species-specific: low doses (0.2-1.0 pmol cell-1) inhibited P. tricornutum at the exponential onset, while C. muelleri remained resilient to higher doses (1.5-16.2 pmol cell-1). Notably, this resilience in C. muelleri shifted to growth promotion when GABA was applied at the late stage, demonstrating clear stagedependency. In P. tricornutum, supplementation with 0.2-1.0 pmol cell-1 GABA triggered a significant accumulation of cellular carbohydrates, proteins, and lipids accompanied by a broad-spectrum increase in various cellular fatty acid concentrations including polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid and docosahexaenoic acid, important PUFAs. Notably, 1.0 pmol cell-1 GABA induced a three-fold increase in carbohydrate and lipid levels over the control. GABA triggered significant oxidative stress and photosynthetic inhibition in P. tricornutum in a dose-dependent manner, while C. muelleri exhibited high physiological tolerance with no marked changes in reactive oxygen species and superoxide dismutase or photosynthetic efficiency. A two-stage cultivation strategy involving initial biomass maximization and subsequent GABA-induced nutrient enrichment can be effectively utilized to biofortify P. tricornutum for use as aquaculture feed.
Zeaxanthin epoxidase (ZEP) plays a central role in carotenoid metabolism, but its evolution and function in red algae remain unclear. Here, we comprehensively identified ZEP homologs across red algal lineages through phylogenetic reconstruction, conserved motif analysis, structural comparison, and branch-specific selection pressure analyses to uncover adaptive evolutionary patterns. The ZEP homolog from Pyropia haitanensis (PhZEP) was selected for functional characterization, including promoter cis-element analysis, heterologous expression, in vitro enzymatic assays, and expression profiling under high light and desiccation-rehydration stress. Thirteen ZEP homologs were identified and clustered into three clades, indicating early divergence and a cyanobacterial origin. Lineage-specific structural divergence and purifying selection with relaxed constraints in Bangiophyceae were observed. Recombinant PhZEP specifically converted zeaxanthin to antheraxanthin, but not further to violaxanthin. PhZEP expression was moderately induced by high light and strongly upregulated during desiccation, peaking at 9.52-fold at 4.8% relative water content. These results demonstrate that PhZEP exhibits specific zeaxanthin epoxidase activity and may be associated with abiotic stress responses, providing insights into carotenoid pathway evolution and photoprotection strategies in red algae.
Dinoflagellate harbors diverse associated bacterial communities (ABCs) that play crucial roles in host physiology and ecological interactions. Coolia malayensis is a benthic dinoflagellate distributed from temperate to tropical regions. Despite growing knowledge about the morphology, distribution, and toxicity of C. malayensis, little is known about its associated bacteria, particularly under changing environmental conditions. Given that climate change alters microbial interactions through temperature shifts, this study investigated the composition, diversity, and dynamics of ABCs across four C. malayensis strains, under varying temperatures and growth time. Despite differences in strain origin, a stable core microbiome, comprising Alteromonas, Marinobacter, Muricauda, and Ruegeria, was consistently observed, suggesting these taxa are functionally important members of the ABC. However, strain-specific differences and temperature-driven shifts were also detected, especially among low-abundance bacterial taxa. Negative interactions among abundant amplicon sequence variants, such as those between Ruegeria and Muricauda, and between Alteromonas and Marinobacter, were conserved across conditions, suggesting stable patterns of co-occurrence. Functional predictions and Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested potential involvement of ABCs in chemoheterotrophy, fermentation, hydrocarbon degradation, energy metabolism, and the metabolism of cofactors and vitamins, implying potential diverse metabolic exchanges between the bacteria and C. malayensis. These findings highlight both the ecological stability and environmental sensitivity of C. malayensis culture-associated microbiomes, with important implications for host health and ecosystem dynamics under climate change.
Intensifying stratification in marginal seas is transforming planktonic ecosystems, yet the interaction between taxonomic composition, functional traits, and biomass remains poorly quantified. Here, we analyze eukaryotic protist communities at three depth layers across three seasonal cruises (May, July, and October 2023) in the northern East China Sea (nECS). We combined small-organelle enriched metagenomics (SoEM) with high-performance liquid chromatography (HPLC) pigment chemotaxonomy to separate two complementary signals: the richness and composition of detected operational taxonomic units (OTUs), derived from SoEM, and the size-fractionated chlorophyll-a biomass, derived from diagnostic pigments. A total of 602 eukaryotic OTUs were recovered from 61 samples. OTU richness, Faith's phylogenetic diversity (PD), and mean nearest-taxon distance-based clustering (Nearest Taxon Index [NTI]) revealed pronounced seasonal restructuring: richness and PD tripled from May and July to October, whereas all three seasons showed positive Net Relatedness Index values, indicating that environmental filtering on community assembly operated throughout the year rather than being a summer-only phenomenon. NTI was nevertheless on average lower in October than in July, consistent with autumn mixing relaxing the fine-scale co-occurrence of closest relatives. In terms of composition, nanoplankton (2-20 mu m) accounted for the largest share of OTUs under stratified surface conditions, while microplankton (>20 mu m), mostly diatoms, increased in the deep layer. Mixotrophic protists reached similar to 30% of OTUs at stratified summer surfaces, and heterotrophs expanded in October. In parallel, pigment-based size-fractionated chlorophyll-a showed that microphytoplankton biomass persisted at and below the deep-chlorophyll maximum year-round, whereas nanophytoplankton biomass dominated surface layers in May and July. Because SoEM quantifies the presence of taxa rather than their abundance, while HPLC integrates standing stock, the combined framework disentangles who is present from who dominates the biomass pool. Our findings highlight that cell size, trophic plasticity, and vertical niche partitioning, mediated by seasonal hydrography, jointly shape the assembly and biogeochemical function of protist communities in the nECS. As climate change intensifies stratification and suppresses seasonal mixing, trait-and size-based models will be essential for predicting future carbon dynamics in warming marginal seas.
This study explores the dynamics of protist communities in the northeastern East China Sea (ECS) focusing on their responses to changing water masses and oceanographic conditions during spring, summer, and autumn in 2023. Water masses were classified using K-means clustering based on physico-chemical parameters, revealing significant seasonal variation. Protist community spatial, temporal, and vertical distributions were analyzed using 18S rRNA gene amplicon sequencing and morphological identification along the 33 degrees N latitude, a region characterized by the confluence of multiple water masses, including Kuroshio surface (KSW) and sub-surface (KSSW) waters, Yellow Sea water (YSW), Changjiang diluted water (CDW), and ECS Shelf water. Protist diversity, community structure, and cell abundance exhibited pronounced seasonal variations influenced by temperature, salinity, and nutrient availability. In spring, YSW, characterized by phosphate deficiencies and, consequently, increased N : P ratios, exhibited a prevalence of dinoflagellates, whose phagotrophic capabilities likely conferred a competitive advantage in such nutrientfluctuating environments. During summer, diatoms were prevalent in the ECS Shelf water, underscoring the role this water plays in shaping seasonal community structure. In contrast, CDW exhibited low species diversities, likely due to unstable salinity. In autumn, water column mixing increased overall diversity and cell abundance, particularly in YSW, where Chaetoceros socialis and other diatoms thrived. Potential phosphorus limitation, especially in the western waters, may have further influenced the spatial structuring of communities across seasons. These findings highlight complex interactions between oceanographic factors and protistan communities in the northeastern ECS, contributing to a deeper understanding of their distributions and responses to environmental changes.
Lobophora (Dictyotales, Phaeophyceae) is an ecologically important seaweed genus in tropical and subtropical marine ecosystems. This alga exhibits cryptic diversity and morphological plasticity, which require taxonomic delineations that primarily depend on DNA analyses, complemented by morphological and ecological data. Species diversity and distribution within Southeast Asia remain understudied compared to well-documented regions such as the Caribbean and the western Pacific. This study provides a comprehensive assessment of the genus Lobophora along the east coast of Thailand, integrating DNA-based surveys with morphological analyses. Extensive sampling across the Gulf of Thailand revealed 14 well-supported monophyletic clades of Lobophora. Among these, we described four new species (L. lewmanomontiae sp. nov., L. ogawae sp. nov., L. thiemmedhii sp. nov., and L. velasquezii sp. nov.) and reported three new national records (L. abscondita, L. henae, and L. quangtriensis), thereby bringing the Thai total to 21 species. When combined with previous records, 30 species have now been recorded from Southeast Asia, with 12 of which are endemic to the region. This study also emphasizes the importance of extensive sampling across broader areas, which enhances our understanding of biogeographic distributions and their implications for coastal ecosystem management.
Pyropia yezoensis, a red macroalga distributed in the intertidal zone, serves as an important model organism for studying the adaptive mechanisms of intertidal seaweeds in response to abiotic stressors. Additionally, it is a significant economic seaweed due to its high nutrient content and is widely cultivated in China, Japan, and Korea. Despite its importance, existing molecular tools for genetic transformation remain limited and require further development to enhance our understanding of P. yezoensis biology. To address this limitation, based on previous studies, we firstly evaluated the expression of eight fluorescent proteins (FPs) in P. yezoensis. Our findings confirmed that PyZsYellow, PyZsGFP, and PysGFP can be detected successfully their specific fluorescent signals within the cells of P. yezoensis thalli. Notably, PyZsGFP demonstrated effectiveness in sporophytic filaments. 2 & times;SV40 and PyNP may function as nuclear localization signal sequences, effectively directing the FP to localize within the nucleus of cells in P. yezoensis. T2A linker can mediate protein cleavage, to express the multiple genes in one construct, enabling them to function independently in P. yezoensis. Furthermore, we identified that the RZ line exhibited the highest transformation potential, while the middle region of thalli showed the superior transformation efficiency. A significant correlation between cell size and transformation efficiency. These findings will contribute to developing a systematic toolkit for conducting genetic transformations and elucidating gene functions in P. yezoensis.
The green macroalgal genus Ulva is widely distributed, ecologically important, and serves as a versatile bioresource. In South Korea, where Ulva species are utilized as edible seaweeds, challenges such as low production and the impact of green tides on aquaculture and marine ecosystems are evident. Recognizing the limitations of morphology-based taxonomy, there has been a shift towards the integration of DNA-based methods for species delimitation and identification. This study addresses the gaps in understanding Ulva diversity in Korean coastal areas by analysing species based on three genetic markers (tufA, rbcL, and ITS) alongside detailed morphological analyses. Our findings unveiled 14 Ulva species through sampling, including first records of U. arago & euml;nsis, U. iliohaha, U. lacinulata, and U. partita. When combined with one previously published DNA-confirmed species, our findings bring the total number of Ulva species confirmed by molecular data in Korea to 15, thereby refining and expanding current knowledge of Ulva diversity in the region. Wide morphological variation was observed within some Ulva species, such as U. conglobata and U. australis, as well as overlapping morphological traits that blurred the boundaries between several species having a rosette-like form, revealing intriguing patterns of form variation. This study establishes a molecular taxonomic baseline for Ulva in Korea and provides new insights into the morphological plasticity of the genus across environmental gradients.
To clarify an unidentified marine sand-dwelling dinoflagellate isolated from samples collected at a sandy beach of Geoje Island, Korea, its morphology and molecular phylogeny based on the small and partial large subunit rRNA gene sequences were examined. In addition, growth responses and fatty acid content of the isolate under different temperature conditions were investigated to assess its physiological traits and aquaculture potential. Cells were 26.3-41.5 pm long (34.8 +/- 3.6 pm) and 19.8-40.8 pm deep (28.9 +/- 4.8 pm), and a nucleus located in the dorsal half of the cell and pyrenoid surrounded by a starch sheath were observed. Scanning electron microscope observations revealed that the cells were characterized by a lack of precingular plates, scattered thecal pores, a single flagellar pore and a shallow anterior cingulum. One or two pores were present on the plate 3p, and one pore was consistently observed on plate 4p. The phylogenetic analyses revealed that the Korean isolate can be identified as Pseudadenoides kofoidii that has not previously been described in Korean coastal area. In the growth experiments, the isolate appeared to prefer moderate temperatures (15 and 20 degrees C) rather than higher temperature (25 degrees C). Although this species exhibited temperature-dependent variation in docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) production, P. kofoidii maintained remarkably high levels of DHA and EPA in its fatty acid composition (>42% of total fatty acids), highlighting its potential as a promising marine source of fatty acids for aquaculture applications.
The first records of the red algal genus Incendia are reported from five Micronesian islands. The distribution range of Incendia crenata is expanded to include the islands of Kosrae and Pohnpei in Micronesia. Additionally, eight new species are described based on morphological and molecular analyses: Incendia chamoruensis sp. nov., I. dixonii sp. nov., I. fragilis sp. nov., I. orotensis sp. nov., I. gordonii sp. nov., I. lobbanii sp. nov., I. micronesica sp. nov., and I. tsudae sp. nov. While each of the newly described species exhibits the diagnostic features of the genus Incendia, they are distinguished from their congeners by a combination of unique anatomical characters and pronounced genetic divergence. The description of eight new species represents an 80% increase in the global species richness of Incendia. These additions bring the total number of species in the Tropical Northwestern Pacific to 14 out of the 18 known globally. This provisionally establishes this marine province as the primary diversity hotspot for the genus and suggests that peyssonnelioid biodiversity remains substantially underestimated, particularly in tropical regions.
Ethyl gallate (EG), a phenolic ester derivative of gallic acid previously identified from the freshwater green alga Spirogyra sp., was investigated in this study as a bioactive constituent contributing to the anti-inflammatory potential of this underutilized algal resource. The anti-inflammatory activity of EG was systematically evaluated using both in vitro and in vivo models. In lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages, EG significantly suppressed nitric oxide (NO) production without inducing cytotoxicity at concentrations ranging from 6.25 to 25 mu M. In addition, EG markedly reduced the secretion of major pro-inflammatory mediators, including prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-6, and IL-1 beta. Mechanistic investigations revealed that EG downregulated the expression of inducible nitric oxide synthase and cyclooxygenase-2, accompanied by inhibition of I kappa B alpha phosphorylation and nuclear translocation of nuclear factor-kappa B (NF-kappa B) p65 and p50 subunits, indicating suppression of NF-kappa B signaling. In the zebrafish larvae model, the in vivo results supported protective effects of EG against LPSassociated oxidative and inflammatory phenotypes, where EG significantly improved survival rates and attenuated inflammation-associated markers, including NO accumulation and cellular damage. Collectively, these findings suggest the potential of Spirogyra sp. as a source of anti-inflammatory constituents, while the quantitative contribution of EG to the overall bioactivity of the crude extract requires further validation.
The taxonomy of filamentous Bangiales was challenging due to its plastic and simple morphology. Molecular approaches play a significant role in revealing cryptic biodiversity and resolving phylogenetic relationships. Nonetheless, the biodiversity of filamentous Bangiales in many regions, including China, has not been thoroughly investigated yet using updated methods. In this study, we investigated the biodiversity of filamentous Bangiales in China, employing a more comprehensive and detailed sampling approach. The rbcL and 18S gene sequences (partial or complete) of 49 specimens collected from 37 sites were obtained. Phylogenetic analysis resolved these specimens into four clades, including Bangia, 'Bangia' 1, 'Bangia' 2, and Pseudoganglia. Seven putative species were delineated (GMYC), and Bayesian Poisson tree processes (bPTP), as well as genealogical analysis. Among them, four were species previously reported, two were cryptic species, and the other was a new record in China. The distribution of these molecularly delineated species was mapped along China's coastline. Similar to the bladed Bangiales, antitropical, transoceanic, and thermal-gradient distribution patterns were also observed for filamentous Bangiales on a global scale. The ancestral region was retraced by incorporating species data from China into existing datasets using BioGeoBEARS with BAYAREALIKE + J as the best-supported model. Under this model, East Asia shows the highest marginal probability as the ancestral area for the crown clade, though uncertainty remains across alternative regions. A most parsimonious expansion scenario of Bangiales from east Gondwana to other regions of the world was proposed.
The genus Colaconema represents a significant group of filamentous red algae that commonly grow as epiphytes, endophytes, or epi-endophytes on a variety of economically important macroalgae, potentially affecting host health and aquaculture productivity. Although numerous Colaconema species have been described worldwide, few have been reported from China based on integrated morphological and molecular analyses. In this study, Colaconema specimens were collected from the red macroalgae Solieria sp. in Zhanjiang City, Guangdong Province, China, and identified through detailed morphological observations combined with rbcL and 5 ' region of cytochrome c oxidase subunit I (COI-5P) sequence analyses. Morphological examination revealed cylindrical cells (23-26 & times; 6-8 l tm), irregularly branched filaments, a single plastid with a single pyrenoid, and ovoid monosporangia (11-12 & times; 7-9 l tm) arranged in various patterns. Molecular analyses demonstrated sufficient sequence divergence from other Colaconema species (rbcL: 5.06-13.65%; COI-5P: 7.23-13.09%), supporting the recognition of these specimens as a new species. The findings expand the current understanding of species diversity within the genus.
Sargassum thunbergii is a large brown seaweed endemic to the Northwest of Pacific Ocean, widely distributed in the warm temperate coastal waters of South Korea, China, and Japan. It is abundant in resources and has a long history of application, widely used in food, medicine, and feed. In recent years, it has also been used to restore marine ecology. To date, only one review has been published on Sargassum thunbergii aquaculture. Therefore, by investigating the international definitive data repository (ScienceDirect, PubMed, Web of Science, ACS Publications, Springer, etc.) and collecting 92 kinds of literature closely related to phycology, chemistry, biological activity, and applications, herewith a comprehensive and systematic summary and exposition, enveloping the classification and distribution, botanical characteristics, and physiological and biochemical differences of Sargassum thunbergii ; involving 7 chemical classifications of 117 derivatives substances embracing 12 new and 6 first-isolated excluding polysaccharides; mainly including 11 types of pharmacology in vivo and in vitro; evaluating the potential applications related on medicine, healthcare, aquaculture, and marine restoration. This review is expected to provide forward-looking scientific perspectives and act as a valuable reference for future studies, development, and utilization of Sargassum thunbergii .
Coastal saline-alkaline soils in China's Yellow River Delta represent vital yet underutilized arable reserves, where crop productivity is severely constrained by dynamic salinity-alkalinity stress, compounded by the scarcity of native stress-adapted biological resources for sustainable remediation. This study addressed this critical gap through in situ isolation of a novel halo-alkaliphilic microalga from saline waters, identified as Desmodesmus sp. R1108 via morphological characterization (distinctive single/quad-cell palisade structures; 8 x 4-6 mu m cells) and molecular phylogeny. The strain exhibited unprecedented alkaliphilic traits, demonstrating 35% enhanced growth at 100 mM NaHCO3 while tolerating pH 10.0. Crucially, soil irrigation with live cells significantly boosted Sesbania cannabina resilience across multiple stress regimes: germination rates surged 47% under 200 mM NaCl, plant height increased 42% under 200 mM NaHCO3, and root biomass rose 56% under neutral salt stress-representing a novel application of a locally isolated, halo-alkaliphilic microalga via soil irrigation to leverage intrinsic stress-adaptation mechanisms for green-manure legume cultivation. This pot-scale study demonstrates a promising, eco-friendly bioinoculant approach that enhanced legume growth by 27-47% under controlled saline-alkaline conditions, highlighting its potential as a foundational strategy for the future development of scalable remediation techniques for marginal saline ecosystems.
The diatom Phaeodactylum tricornutum is known for its rapid growth and high fucoxanthin content (1-3% of dry weight), a photosynthetic pigment with considerable pharmaceutical and nutraceutical potential. Despite these advantages, the commercial biotechnological applications of this organism have not yet been realized, primarily due to challenges in scaling up photobioreactor (PBR) systems, as well as issues with the organism's robustness and production processes. In this study, we present a multifaceted approach to enhance fucoxanthin productivity by combining innovations in PBR design, strain improvement, and LED light recipes. Systematic evaluation of P. tricornutum in 700 mL column PBRs identified optimal light conditions (e.g., 660 nm red light at 50 mu mol photons m-2 s-1 with optimized light regimes), which were subsequently scaled up to novel 200 L and 10,000 L PBRs. Meanwhile, atmospheric and room temperature plasma mutagenesis, coupled with an adaptive evolution screening technique, generated superior mutant consortia exhibiting enhanced phenotypic characteristics, including higher fucoxanthin yield and long-term stability of cultivation. Comparative cultivation experiments in the 10,000 L PBR demonstrated the superiority of the mutant consortia, yielding 0.59 g L-1 biomass (an 18% increase) and 7.29 mg L-1 fucoxanthin (a 32.79% increase) compared to the wild type strain. Productivity was significantly improved, with biomass and fucoxanthin production rates reaching 0.12 g L-1 d-1 (a 33.33% increase) and 1.47 mg L-1 d-1 (a 54.74% increase) in the 10,000 L PBR, respectively. This work provides an optimized light recipe, superior mutant consortia, and scalable PBR design, effectively bridging laboratory-scale research with industrial application potential.
Due to the fact that Pyropia haitanensis contains numerous nutritional and biofunctional compounds, its development prospects are very promising. However, asynchronous conchocelis development has limited the large-scale use of new varieties of P. haitanensis. In this study, we combined lipid metabolomic and transcriptomic data to analyze the free-living conchocelis of two P. haitanensis strains that vary regarding conchocelis maturation at specific time points to investigate the mechanism underlying conchocelis maturation. Phosphatidylcholine (PC) synthesis was found to be closely related to the initiation of the maturation process, and genes associated with triacylglycerol (TG) accumulation coincided with a relative decrease in polyunsaturated membrane lipids, consistent with a buffering/ energy-reserve role during maturation. PC abundance increased early in early-maturing strain (S1), and higher TG levels coincided with lower polyunsaturated membrane lipids, suggesting a potential buffering mechanism against environmental stimuli during maturation. The accumulated TG can be metabolized to produce energy to enhance the maturation of free-living conchocelis. Moreover, free-living conchocelis can increase the digalactosyldiglyceride/ monogalactosyldiglyceride ratio to adapt to maturation conditions. Additionally, differences between the S1 and latematuring strain (S2) during the conchocelis maturation process were clarified. For example, S1 initiates PC synthesis and metabolism earlier than S2, while also producing arachidonic acid relatively quickly to improve membrane fluidity. Furthermore, S1 metabolizes TG faster than S2 to provide energy and maintain lipid homeostasis, thereby promoting free-living conchocelis maturation. In summary, lipid metabolism, particularly phospholipid metabolism, plays a crucial role in initiating the conchocelis maturation process and facilitating the formation of conchosporangia.
Ischemic stroke (IS) has emerged as one of the leading causes of mortality and disability in adults worldwide. Hypoxia-inducible factor 1 alpha (HIF-1 alpha) signaling pathway plays a critical role in endogenous neuroprotective mechanisms following IS. Sargassum fusiforme is a significant marine algal resource. In previous research, we isolated bioactive fucoidan from acid-processed S. fusiforme, and demonstrated its anti-inflammatory and antioxidant efficacy. This study aimed to elucidate the role of S. fusiforme polysaccharides (SFPS) in promoting angiogenesis via the HIF1 alpha/vascular endothelial growth factor (VEGF) pathway following IS and to investigate the underlying mechanisms involved. In this study, we employed a hypoxia model in human cerebral microvascular endothelial cells (hCMECs/ D3) and a zebrafish IS model to elucidate the therapeutic mechanisms of SFPS in mitigating cerebral ischemic injury. Cellular assays confirmed the ability of fucoidan to prevent apoptosis and promote neovascularization in hCMEC/D3 cells under hypoxic stress. Furthermore, in a zebrafish IS model, fucoidan increased blood flow velocity and locomotor activity, while reducing neuronal apoptosis. Mechanistically, fucoidan activated the HIF-1 alpha/VEGF signaling pathway in both cellular and animal models, thereby ameliorating hypoxic injury and stimulating angiogenesis. Results demonstrated the angiogenic activity of fucoidan in both in vitro and in vivo models, and revealed its key targets and associated pathways underlying its anti-ischemic effects. Findings collectively highlight the prospective utility of fucoidan as a marine-derived therapeutic agent from traditional Chinese medicine for neurovascular repair.
