Algal Species Research Articles

Responses to phytoplankton community succession and expression of key functional genes in plateau lakes under 17β-estradiol interference

Steroid estrogens (SEs) have garnered global attention because of their potential hazards to human health and aquatic organisms at low concentrations (ng/L). The ecosystems of plateau freshwater lakes are fragile, the water lag time is long, and pollutants easily accumulate, making them more vulnerable to the impact of SEs. However, the knowledge of the impact of SEs on the growth and decomposition of phytoplankton communities in plateau lakes and the eutrophication process is limited. This study investigated the effects and mechanisms of SEs exposure on dominant algal communities and the expression of typical algal functional genes in Erhai Lake using indoor simulations and molecular biological methods. The results showed that phytoplankton were sensitive to 17β-estradiol (E2β) pollution, with a concentration of 50, and 100 ng/L E2β exposure promoting the growth of cyanophyta and chlorophyta in the short term; this poses an ecological risk of inducing algal blooms. E2β of 1000 ng/L exposure led to cross-effects of estrogenic effects and toxicity, with most phytoplankton being inhibited. However, small filamentous cyanobacteria and diatoms exhibited greater tolerance; Melosira sp. even exhibited "low inhibition, high promotion" behavior. Exposure to E2β reduced the Shannon-Wiener diversity index (H'), Pielou index (J), and the number of dominant algal species (S) in phytoplankton communities, leading to instability in community succession. E2β of 50 ng/L enhanced the expression levels of relevant functional genes, such as ftsH, psaB, atpB, and prx, related to Microcystis aeruginosa. E2β of 50 ng/L and 5 mg/L can promote the transcription of Microcystis toxins (MC) related genes (mcyA), leading to more MC production by algal cells.

Physico-chemical characterisation of irrigation basin waters and inventory study of their algal communities.

To cope with the water shortage in Sous Massa region of Morocco, agricultural producers in the region have resorted to different types of water supply basins, known as "irrigation basins" but the phenomenon of eutrophication has hindered the continuity of agricultural productivity by altering the quality of the water used for irrigation on the one hand, and causing economic damage to agricultural producers due to the clogging of the water pumping network on the other. We began by characterising the physico-chemical quality of the water to determine the causes of its high nutrient content, then we determined the taxonomy of the algal species in the irrigation basins to which we had access. A qualitative study of the water in the irrigation basins in order to better explain the inventory obtained from the taxonomic identification of the algal biomass collected, which proved the existence of new species, not previously identified, characterising the freshwaters of the Moroccan region, is under the scope of this work. The species studied belong mainly to the following groups: green algae (11 genera of Chlorophyta and 7 genera of Charophyta), blue algae (7 genera of Cyanobacteria), brown algae (7 genera of Diatoms), and one genus of Euglenophyta.

Morphological insights into the three-dimensional complexity of rhodolith beds

The ecological importance of rhodolith beds stems from their role as structurally complex three-dimensional habitat formed by free-living red calcareous algae. Their structural singularity is due to the great variety of complex and branching morphologies exhibited by rhodoliths that create interstitial spaces and increase their surface area. This increases the ecological niches for cryptofauna and provide refuge for a high number of organisms, which is why rhodolith beds are considered biodiversity hotspots. In this work, we studied a rhodolith bed located in the Menorca Channel, formed by several species of red calcareous algae that exhibit a great variety of morphologies and form an extensive and heterogeneous habitat. This study explored the morphological diversity of the rhodolith bed, comparing the ‘Core Habitat’ (within the center of the bed with the highest densities of rhodoliths) with the boundaries or ‘Adjacent Habitat’ where rhodolith density was lower. Our results show that all rhodolith growth forms (branched, pralines and boxwork) in the Core Habitat had higher interstitial space and were larger than the ones from adjacent zones. Moreover, we explored the three-dimensional techniques to study the morphological characteristics that have historically been studied in two dimensions. This study contributes to the knowledge of morphological diversity in well-preserved rhodolith beds from continental shelves in the western Mediterranean Sea and reinforces the use of three-dimensional measurements, specifically the interstitial space of branched rhodoliths, to provide more accurate data on habitat complexity.

Flavour characterization of twelve species of edible algae

Integration of algae as ingredients in food products may contribute to the flavour characteristics, on top of providing nutritional requirements. In this study, characterization of the volatile and non-volatile flavour compounds was performed on 12 species of macroalgae and microalgae representing various groups of algae. Nine macroalgae species from three divisions were selected, namely Phaeophyta (brown alga): Laminaria japonica, Undaria pinnatifida, Sargassum fusiforme and Fucus vesiculosus; Rhodophyta (red alga): Porphyra haitanensis, Porphyra yezoensis, Palmaria palmata and Gelidium amansii, and Chlorophyta (green alga): Ulva lactuca. In addition, three microalgae species include Arthrospira platensis, Chlorella vulgaris and Dunaliella salina. Volatile compounds were analysed by solid-phase microextraction (SPME) and gas chromatography–mass spectrometry-flame ionization detector (GC–MS/FID). Amino acids and nucleotides were analysed using amino acid analyser and high-performance liquid chromatography (HPLC) respectively. Based on the identified volatile and non-volatile compounds, no obvious trend was found within each group of algae. However, some algae variants have been found to contain a unique aroma profile of selected volatile and non-volatile compounds. D. salina was found to be high in volatile aldehydes, ketones, and alcohols, primarily products of carotenoid degradation. U. lactuca contains the highest volatile sulfur content, while F. vesiculosus was found to be high in aldehyde and alcohol compounds, which are potentially fishy odours. C. vulgaris was found to have the highest value of equivalent umami concentration (EUC) followed by roasted P. haitanensis, indicating that both algae have the highest umami potential. Lastly, microalgae species A. platensis and C. vulgaris contained the highest amounts of sulfurous tasting amino acids cysteine and methionine respectively.

Diverse fates of ancient horizontal gene transfers in extremophilic red algae.

Horizontal genetic transfer (HGT) is a common phenomenon in eukaryotic genomes. However, the mechanisms by which HGT-derived genes persist and integrate into other pathways remain unclear. This topic is of significant interest because, over time, the stressors that initially favoured the fixation of HGT may diminish or disappear. Despite this, the foreign genes may continue to exist if they become part of a broader stress response or other pathways. The conventional model suggests that the acquisition of HGT equates to adaptation. However, this model may evolve into more complex interactions between gene products, a concept we refer to as the 'Integrated HGT Model' (IHM). To explore this concept further, we studied specialized HGT-derived genes that encode heavy metal detoxification functions. The recruitment of these genes into other pathways could provide clear examples of IHM. In our study, we exposed two anciently diverged species of polyextremophilic red algae from the Galdieria genus to arsenic and mercury stress in laboratory cultures. We then analysed the transcriptome data using differential and coexpression analysis. Our findings revealed that mercury detoxification follows a 'one gene-one function' model, resulting in an indivisible response. In contrast, the arsH gene in the arsenite response pathway demonstrated a complex pattern of duplication, divergence and potential neofunctionalization, consistent with the IHM. Our research sheds light on the fate and integration of ancient HGTs, providing a novel perspective on the ecology of extremophiles.

Detecting Margalefidinium polykrikoides through high-frequency imagery: Example of a bloom formation, environmental conditions, and phytoplankton community composition changes

In August 2018, the harmful algae species Margalefidinium polykrikoides bloomed to levels previously unobserved in the open waters of Narragansett Bay, Rhode Island, in a transient but intense bloom. Detected by an Imaging FlowCytobot providing hourly data, it is characterized by a time span of less than a week and patchiness with sub-daily oscillations in concentration. The highest concentrations are recorded at lower salinity and higher temperature, suggesting the bloom may have developed in the upper bay and was transported south. The proportion of chains increased during the height of the bloom, and many of the images contained 4-cells per chain. The development of the bloom was favored by optimal temperature and salinity conditions as well as increased nitrogen coincident with greater precipitation and river flow. The period preceding bloom formation also saw a sharp decrease in the dominating large chain-forming diatom Eucampia sp. and highly abundant Skeletonema spp., thus reducing competition over resources for the slow-growing M. polykrikoides. The height of the bloom was reached during the lowest tidal range of the month when the turbulence and water displacement were lower. This time series highlights an out-of-the-ordinary bloom's environmental and biological conditions and the importance of frequent sampling during known favorable conditions.

Isochrysis Crisis

Isochrysis galbana, a brown algae, was trialed to grow at the CFK aquaculture lab but failed until we tried comparing different tank salts to create a wellbalanced base. Our objective was to demonstrate and compare the different saltwater mixes that can be used in cultivating brown algae. Isochrysis galbana and other green algae that are grown at the CFK lab play a very important part in the aquaculture system. Algae is used as a good source of food and nutrients for many primary producers. Algae are one of the most important animals on earth. They create most of the oxygen that we breathe, and they filter every part of the water around the world. Brown algae is known around Florida because of certain species, like sargassum. We are currently having an issue with sargassum, so learning about different brown algae species can benefit everyone around the world. If Isochrysis sp. is kept at a stable salinity of 35ppt then it will easily and successfully grow. The samples were grown according to the standard measures but with different salt bases one was raw salt water, live aquaria and REEF salt. The raw seawater sample grew over a 1–2-day period with salinity that usually stayed around 40. The samples mixed into each artificial reef salt took about a week or more to grow color and cultivate the algae.

A new species of marine algae from the Mexican Atlantic based on morphology and molecular data: Gelidium rodrigueziae sp. nov. (Gelidiaceae, Rhodophyta)

Abstract The algae of the genus Gelidium can be found as frequent and abundant inhabitants in the rocky intertidal zone of the Mexican Atlantic. Six species of this genus have been reported in this region, but only Gelidium americanum has been confirmed with morphological and molecular tools, despite how important both tools have proven to be for the group. This research aimed to evaluate the Mexican specimens previously identified as Gelidium through morphological and molecular approaches, using rbcL and COI-5P markers. This study examined 20 specimens found living attached to the shell of a gastropod Stramonita rustica in the mid-high intertidal zone of the Mexican Atlantic and ten specimens found living on rocks. Phylogenetic analyses resolved these specimens to be an independent species closely related to G. gonzalezii, G. yangmeikengense, and G. indonesianum. Genetic distances and morphological information confirmed this. Gelidium rodrigueziae sp. nov. is described as a new species. It is distinguished from its related species by having a simpler branching pattern, a smaller number and size of medullary cells, and the smaller quantity and distribution of restricted internal rhizoid filaments around the medulla.

The Effect of Cloride Acid Concentration to The Phenolic Compound and The Antioxidant Activity in Methanol Extract of Sargassum oligocystum

Sargassum oligocystum is a species of brown algae that has many biological activities. The aim of this research is to analyze the polyphenol compound and antioxidant activity with methanol solvent at varying acid concentrations. Addition of hydrochloric acid in methanol solvent at various concentrations of 0.1 N; 0.2 N, 0.3 N in Sargassum oligocystum showed an increase in polyphenol compound, 2.82 mg GEA/g; 3.27 mg GEA/g and 3.88 mg GAE/g, respectively. The increase in polyphenol compound is proportional to the increase in antioxidant activity, 0.92 mg; 0.55 mg and 0.29 mg, respectively. The results showed that methanol extraction with variations of hydrochloric acid in Sargassum oligocystum contained polyphenols and antioxidant activity which increased with increasing acid concentration. Keywords: Antioxidant activity; cloride acid; methanolic extract; phenolic compound; Sargassum oligocystum

Influence of Biogenic Material Content on the Biodegradability of Styrene-Butadiene Composites with Incorporated Chlorella vulgaris Biomass.

Bio-fillers are intensively studied for advanced polymer composite circular design and production. In this context, the algal biomass may be considered an important and relatively low-cost resource, when harvested as a by-product from wastewater treatment plants. The biomass of the algal species Chlorella vulgaris is frequently used in this type of environmental process, and its macro constituents' composition ranges from around 15-25% carbohydrates, 10-20% lipids, and 50-60% proteins. Poly (styrene-butadiene-styrene) (SBS) copolymers have a matrix composed of glassy polystyrene domains connected by flexible polybutadiene segments. Although the physical-mechanical properties of SBS copolymers recommend them for many industrial applications, they have the drawback of low biodegradability. This study aimed to assess the aerobic biodegradability of polymer composites by integrating biomass from Chlorella vulgaris at varying mass percentages of 5, 10, and 20% into SBS copolymer composites. Biodegradation tests were conducted under industrial composting conditions (58 °C and 50% relative humidity) for 180 days. The biodegradability of materials was evaluated by measuring the CO2 produced in each vessel during the study period. Potential correlations between the amount of carbon dioxide released and the percentage of biomass added to the polymer matrix were examined. Structural and morphological changes were assessed using Fourier Transform infrared spectroscopy (FTIR), thermal analysis (DSC), and scanning electron microscopy (SEM). Physical and chemical testing revealed a decrease in sample density after the industrial composting test, along with noticeable changes in melt flow index (MFI). The observed physical and chemical changes, coupled with FTIR, SEM, and DSC data, indicate increased cross-linking and higher porosity in biodegraded polymer structures with higher biomass content. This behavior is likely due to the formation of cross-linked connections between polymer chains and polypeptide chains resulting from protein degradation, enhancing connections between polystyrene units facilitated by peptide bonds with the benzene units of the styrene blocks within the polymer matrix.

Snacks from the sea: a cross-national comparison of consumer acceptance for crackers added with algae

One of the main priorities of current food systems is to develop new and healthy foods to overcome food shortages considering consumer’s expectations. Algae are receiving increasing attention as nutritious and sustainable food, though studies are limited mainly to Arthrospira and Chlorella species and cross-national research is scant. This study aims to investigate European consumers’ liking and perception of crackers added with powders from Arthrospira platensis (green Spirulina), isolated proteins from Arthrospira platensis (blue Spirulina), Palmaria palmata, Saccharina latissima, Lithothamnium calcareum and a control cracker. Belgian, German, Italian, and Swedish participants (n = 413, 18–69 years, 59.8% females) evaluated cracker liking and perceived sensory attributes using the check-all-that-apply (CATA) task. Food neophobia, familiarity towards, and consumption of algae were also collected. Partial Least Squares Regression (PLSR) analyses showed that across all countries, Lithothamnium calcareum, blue Spirulina and the control samples were perceived as similar and were liked more than the other crackers. “Sweet”, “toasted bread”, and “bland” attributes were significant contributors to liking, while “off-flavor”, “fishy flavor”, “umami” and “speckled” contributed negatively. PLSR performed by country provided similar results except for Italians who liked the green Spirulina sample equally as the samples added with Lithothamnium calcareum, blue Spirulina, and the control. These cross-national differences can be ascribed to Italians’ lower food neophobia level. The present results suggest that Lithothamnium calcareum is the most promising algal species to be exploited in food formulations and that the use of isolated proteins from Spirulina (blue Spirulina) significantly reduces off-flavors, consequently improving consumers’ acceptance.

Algae as Crop Plants Being a Source of Bioactive Ingredients of Pharmaceutical and Dietary Importance

Algae are currently used in many areas, including dietetics, pharmacy, cosmetology and to increase the nutritional value of food and animal feed due to their chemical composition. They are a source of extremely valuable molecules, including polyunsaturated fatty acids and pigments. Algae are also a valuable source of protein and almost all essential vitamins. They are rich in pigments such as chlorophyll, carotenoids and phycobiliproteins. These substances have a wide range of commercial applications. Due to its very intensive use, the demand for this plant raw material is constantly growing. Therefore, the methods of growing and harvesting algae are constantly improved in order to maximize the cultivation effect while minimizing costs and energy inputs. Future research should focus on improving algae cultivation and harvesting systems, with an emphasis on the possibility of genetic modifications that would allow even more efficient algae cultivation. This review summarizes methods of micro- and macroalgae cultivation, the chemical composition of selected algae species, which are important from the pharmaceutical, dietary and cosmetic points of view and therapeutic and dietary applications of compounds derived from different algae species. The key conclusion drawn from this article is that algae are an extremely valuable raw material, rich in numerous macro- and micronutrients necessary for humans, the acquisition of which is part of the currently important strategy of ecological policy for obtaining raw materials for various industries.

Neuroprotective effect of acetoxypachydiol against oxidative stress through activation of the Keap1-Nrf2/HO-1 pathway

BackgroundExcessive oxidative stress in the brain is an important pathological factor in neurological diseases. Acetoxypachydiol (APHD) is a lipophilic germacrane-type diterpene extracted as a major component from different species of brown algae within the genus Dictyota. There have been no previous reports on the pharmacological activity of APHD. The present research aims to explore the potential neuroprotective properties of APHD and its underlying mechanisms.MethodsThe possible mechanism of APHD was predicted using a combination of molecular docking and network pharmacological analysis. PC12 cells were induced by H2O2 and oxygen–glucose deprivation/reoxygenation (OGD/R), respectively. Western blot, flow cytometry, immunofluorescence staining, and qRT-PCR were used to investigate the antioxidant activity of APHD. The HO-1 inhibitor ZnPP and Nrf2 gene silencing were employed to confirm the influence of APHD on the signaling cascade involving HO-1, Nrf2, and Keap1 in vitro.ResultsAPHD exhibited antioxidant activity in both PC12 cells subjected to H2O2 and OGD/R conditions by downregulating the release of LDH, the concentrations of MDA, and ROS, and upregulating SOD, GSH-Px, and GSH concentrations. APHD could potentially initiate the Keap1-Nrf2/HO-1 signaling cascade, according to the findings from network pharmacology evaluation and molecular docking. Furthermore, APHD was observed to increase Nrf2 and HO-1 expression at both mRNA and protein levels, while downregulating the protein concentrations of Keap1. Both Nrf2 silencing and treatment with ZnPP reversed the neuroprotective effects of APHD.ConclusionsAPHD activated antioxidant enzymes and downregulated the levels of LDH, MDA, and ROS in two cell models. The neuroprotective effect is presumably reliant on upregulation of the Keap1-Nrf2/HO-1 pathway. Taken together, APHD from brown algae of the genus Dictyota shows potential as a candidate for novel neuroprotective agents.

Process optimization of Cd2+ removal with Tetradesmus Obliquus-immobilized Algal Beads

In this study, calcium alginate-immobilized microalgae beads were utilized for treating Cd2+-containing wastewater by optimizing the algal species, the preparation conditions of immobilized beads, and the Cd2+ treatment conditions to enhance treatment efficiency. The results revealed that under optimal preparation conditions with a CaCl2 concentration of 3 % and a sodium alginate concentration of 2 %, the removal rate of Cd2+ reached 94.99 % after 3 h of adsorption when 4 g of immobilized Tetradesmus obliquus algal beads were added to a 20 mg/L Cd2+ solution. Additionally, under optimal removal conditions at pH=6, with immobilized Tetradesmus obliquus algal beads as the adsorbent and a dosage of 6 g of immobilized algal beads added to a solution with an initial Cd2+ concentration of 15 mg/L, the Cd2+ removal rate reached 99.85 % after 4 h of adsorption, surpassing that of suspended microalgae and blank algal beads. The adsorption process followed the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model. FTIR analysis indicated that functional groups such as O-H, CO, C-O, C-N, among others, might play a role in the adsorption process. After five adsorption-desorption cycles, the adsorption capacity decreased by only 10 %. This study demonstrated that immobilized Tetradesmus obliquus algal beads is an efficient and renewable and recyclable adsorbent.

The rapid detection method of brown tide algae concentration based on unthresholded recurrence plots and improved broad learning system

In recent years, there have been frequent outbreaks of harmful algal blooms (HAB) in coastal areas, which have caused serious economic losses to the local community. Therefore, accurate and rapid prediction of microalgal concentrations is necessary for early warning and countermeasures before the occurrence of HAB. This paper presents a model for predicting microalgae concentration based on unthresholded recurrence plots (UTRPs) combined with an improved broad learning system (BLS). Spectral data acquisition of algae species at different concentrations using l-induced fluorescence spectroscopy. Then, the 1D spectral data are dimensionally lifted by UTRPs transformation, recurrence plots (RPs) transformation can fully extract the internal information of 1D sequence data, and at the same time, UTRPs avoids the influence of artificially selected thresholds on the feature transformation results of traditional (RPs). Finally, a lightweight flat network BLS was used for microalgae concentration regression prediction, at the same time the BLS regularization method was improved. When comparing the two most commonly used deep learning regression models and integrated learning models, UTRPs and elastic net (UTRPs-ENBLS) achieves convincing results.

Toxicity of individual and mixture of organic compounds to P. Phosphoreum and S. Capricornutum using interpretable simple structural parameters

Human and environmental ecosystem beings are exposed to multicomponent compound mixtures but the toxicity nature of compound mixtures is not alike to the individual chemicals. This work introduces four models for the prediction of the negative logarithm of median effective concentration (pEC50) of individual chemicals to marine bacteria Photobacterium Phosphoreum (P. Phosphoreum) and algal test species Selenastrum Capricornutum (S. Capricornutum) as well as their mixtures to P. Phosphoreum, and S. Capricornutum. These models provide the simplest approaches for the forecast of pEC50 of some classes of organic compounds from their interpretable structural parameters. Due to the lack of adequate toxicity data for chemical mixtures, the largest available experimental data of individual chemicals (55 data) and their mixtures (99 data) are used to derive the new correlations. The models of individual chemicals are based on two simple structural parameters but chemical mixture models require further interaction terms. The new model's results are compared with the outputs of the best accessible quantitative structure–activity relationships (QSARs) models. Various statistical parameters are done on the new and comparative complex QSAR models, which confirm the higher reliability and simplicity of the new correlations.

Optimum conditions for growth and copper (II) removal from leachate by Chlorella vulgaris, Spirogyra ellipsospora and Ulva lactuca

This study examined the effectiveness of removing copper (Cu (II)) ions from leachate using three different live algae species (Chlorella vulgaris, Spirogyra ellipsospora, and Ulva lactuca), both individually and in combination. Various algal doses were tested to assess their impact on metal removal efficiency and algal growth. Five distinct masses (5, 10, 15, 20, and 25 g L−1) of each alga were grown in a batch experiment on leachate containing 3 mg L−1 of Cu (II) ions. It was found that the optimum algal dose is between 12.5 and 17.5 g L−1, and the optimum equilibrium duration was between 3 and 4.5 days for tested algal species. Under the optimum conditions of algal dose and contact time, the algae exhibited growth and Cu (II) ions removal efficiency in the order of Spirogyra ellipsospora > mixed algae > Chlorella vulgaris > Ulva lactuca. The study concludes that the selection of right algal species is crucial to optimize the growing environment for copper-contaminated leachate bioremediation.

Global Chemical Characterization of Sargassum spp. Seaweeds from Different Locations on Caribbean Islands: A Screening of Organic Compounds and Heavy Metals Contents

Large-scale strandings of Sargassum spp. seaweeds occur annually on the beaches of the Caribbean islands and cause major environmental, health, and economic problems. In order to support an approach of valorisation of algae, an exhaustive characterisation of the composition of these seaweeds has been performed by analysing the contents in alginates, structural carbohydrates (fucans and glucans), minerals, proteins, lipids, mannitol, polyphenols, and heavy metals. Nine batches were collected at different harvesting sites over the years 2021 and 2022, to estimate the spatial and temporal variation in Sargassum composition. A batch of floats was harvested and analysed to estimate the differences in composition between floats and whole algae. Samples collected during the same year (floats or entire plant, freshly collected or stored) showed no significant differences in composition. However, slight differences were observed between batches collected in the two years. Some samples showed significant amounts of heavy metals, especially arsenic. A detailed structural carbohydrates analysis was carried out and discussed with literature data. As the nitrogen content of algae is an interesting parameter for food or agronomic uses, protein analysis enabled us to calculate a new nitrogen–protein conversion factor, specific to these algae species.

Environmental evaluation of the Reloncaví estuary in southern Chile based on lipophilic shellfish toxins as related to harmful algal blooms

The Reloncaví estuary in southern Chile is famous for its aquaculture. However, recurring harmful algal blooms have adversely affected mussel production. Therefore, regular monitoring of algal toxins is urgently needed to better understand the contamination status of the estuary. In this study, we quantified 15 types of lipophilic shellfish toxins in Metri Bay in the Reloncaví estuary on a biweekly basis for 4 years. We identified algal species using microscopy and metabarcoding analysis. We also measured water temperature, salinity, chlorophyll-a, and dissolved oxygen to determine the potential relationships of these parameters with algal toxin production. Our results revealed the presence of a trace amount of pectenotoxin and the causal phytoplankton Dinophysis, as well as yessotoxin and the causal phytoplankton Protoceratium. Statistical analysis indicated that fluctuations in water temperature affected the detection of these toxins. Additionally, metabarcoding analysis detected the highly toxic phytoplankton Alexandrium spp. in some samples. Although our results suggest that the level of lipophilic shellfish toxins in Metri Bay during the study period was insignificantly low using our current LC-MS method, the confirmed presence of highly toxic algae in Metri Bay raises concerns, given that favorable environmental conditions could cause blooms.

Porphyran Attenuates Neuronal Loss in the Hippocampal CA1 Subregion Induced by Ischemia and Reperfusion in Gerbils by Inhibiting NLRP3 Inflammasome-Mediated Neuroinflammation

Porphyran, a sulfated polysaccharide found in various species of marine red algae, has been demonstrated to exhibit diverse bioactivities, including anti-inflammatory effects. However, the protective effects of porphyran against cerebral ischemia and reperfusion (IR) injury have not been investigated. The aim of this study was to examine the neuroprotective effects of porphyran against brain IR injury and its underlying mechanisms using a gerbil model of transient forebrain ischemia (IR in the forebrain), which results in pyramidal cell (principal neuron) loss in the cornu ammonis 1 (CA1) subregion of the hippocampus on day 4 after IR. Porphyran (25 and 50 mg/kg) was orally administered daily for one week prior to IR. Pretreatment with 50 mg/kg of porphyran, but not 25 mg/kg, significantly attenuated locomotor hyperactivity and protected pyramidal cells located in the CA1 area from IR injury. The pretreatment with 50 mg/kg of porphyran significantly suppressed the IR-induced activation and proliferation of microglia in the CA1 subregion. Additionally, the pretreatment significantly inhibited the overexpressions of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing protein-3 (NLRP3) inflammasome complex, and pro-inflammatory cytokines (interleukin 1 beta and interleukin 18) induced by IR in the CA1 subregion. Overall, our findings suggest that porphyran exerts neuroprotective effects against brain IR injury, potentially by reducing the reaction (activation) and proliferation of microglia and reducing NLRP3 inflammasome-mediated neuroinflammation.