Red Algae Research Articles

Investigating the role of endocytosis in the uptake of photoassimilates in Gracilariopsis lemaneiformis (Rhodophyta)

BackgroundThe translocation of photoassimilates is a critical process that links the source and sink in plants, playing an irreplaceable role in maintaining source-sink balance, ensuring plant growth and development, and the formation of yield. Nevertheless, the mechanisms underlying the translocation of photosynthetic products in macroalgae are yet to be fully understood. The purpose of this study is to reveal the role of endocytosis in the translocation of photosynthetic products in the marine red alga Gracilariopsis lemaneiformis by investigating the uptake of photosynthetic products by endocytosis and the impact of endocytic activity on cellular ultrastructure, photosynthesis, and growth.ResultsThis study discovered that the endocytic activity in non-epidermal cells (NEC, sink cells) of G. lemaneiformis is significantly higher than that in epidermal cells (EC, source cells). NEC is capable of internalizing a greater amount of extracellular carbohydrates, such as sucrose, via endocytosis compared to EC. Further inhibition of endocytic activity in G. lemaneiformis using EIPA resulted in a significant reduction in the content of floridean starch within NEC, whereas the decrease in floridean starch content in EC was not statistically significant. Inhibition of endocytic activity led to an initial decline in photosynthetic efficiency of algal thalli within a few hours, which was followed by an increase as inhibition duration extended, yet the growth rate of the thalli remained substantially suppressed.ConclusionsThese findings indicate that endocytosis in G. lemaneiformis plays a role in regulating the cellular uptake of extracellular photoassimilates, which in turn influences the storage substances in sink cells and the overall growth and development of the algae. This study sheds new light on the regulatory mechanisms governing photoassimilate translocation in macroalgae.

Marine natural products.

Covering: January to the end of December 2023This review covers the literature published in 2023 for marine natural products (MNPs), with 582 citations (541 for the period January to December 2023) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1220 in 340 papers for 2023), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of the progress in the study of prokaryote involvement in macro-invertebrate MNP production is discussed.

The Development of Rapid Test Strips for Alexandrum tamarense

Among algae that synthesize paralytic shellfish toxins (PSTs), Alexandrium tamarense is a widely distributed and highly dangerous species with significant impacts on the marine environment and human health. Therefore, establishing fast and reliable monitoring technology for Alexandrium tamarense is crucial. Developing effective detection and early warning systems for toxic red tides is of paramount importance. Conventional detection methods, such as microscopy and molecular biology, are complex and time-consuming, requiring specialized personnel and equipment, which makes them unsuitable for on-site rapid testing. In this study, we successfully developed polyclonal and monoclonal antibodies targeting Alexandrium tamarense using colloidal gold immunochromatography technology. Based on these antibodies, we created colloidal gold test strips capable of detecting Alexandrium tamarense in water samples. These test strips enable rapid detection of the target algae in aquatic environments and semi-quantitative estimation of algal concentrations using a colorimetric card. They can quickly determine whether the concentration of red tide algae has reached a critical level, allowing for timely preventive measures. This innovation holds significant practical value and broad application potential.

Navigating uncertainty in environmental DNA detection of a nuisance marine macroalga.

Early detection of nuisance species is crucial for managing threatened ecosystems and preventing widespread establishment. Environmental DNA (eDNA) data can increase the sensitivity of biomonitoring programs, often at minimal cost and effort. However, eDNA analyses are prone to errors that can complicate their use in management frameworks. To address this, eDNA studies must consider imperfect detections and estimate error rates. Detecting nuisance species at low abundances with minimal uncertainty is vital for successful containment and eradication. We developed a novel eDNA assay to detect a nuisance marine macroalga across its colonization front using surface seawater samples from Papahānaumokuākea Marine National Monument (PMNM), one of the world's largest marine reserves. Chondria tumulosa is a cryptogenic red alga with invasive traits, forming dense mats that overgrow coral reefs and smother native flora and fauna in PMNM. We verified the eDNA assay using site-occupancy detection modeling from quantitative polymerase chain reaction (qPCR) data, calibrated with visual estimates of benthic cover of C. tumulosa that ranged from < 1% to 95%. Results were subsequently validated with high-throughput sequencing of amplified eDNA and negative control samples. Overall, the probability of detecting C. tumulosa at occupied sites was at least 92% when multiple qPCR replicates were positive. False-positive rates were 3% or less and false-negative errors were 11% or less. The assay proved effective for routine monitoring at shallow sites (less than 10 m), even when C. tumulosa abundance was below 1%. Successful implementation of eDNA tools in conservation decision-making requires balancing uncertainties in both visual and molecular detection methods. Our results and modeling demonstrated the assay's high sensitivity to C. tumulosa, and we outline steps to infer ecological presence-absence from molecular data. This reliable, cost-effective tool enhances the detection of low-abundance species, and supports timely management interventions.

Exploring the Antineoplastic Properties of the Lebanese Jania rubens Against Colorectal Cancer

Background/Objective: Colon cancer poses a significant health burden, with current treatments often associated with severe side effects and limited effectiveness for some patients. Natural products are gaining interest as adjuvant therapies, potentially reducing side effects and improving responses to conventional treatments. We previously highlighted the potent antineoplastic effects of organic extracts derived from the Lebanese red algae Jania rubens. This study, investigated the anticancer activities of polysaccharide, protein, and lipid extracts from J. rubens, which may serve as adjuvant therapies to enhance conventional treatments. Methods: we employed colorimetric assays, wound healing assays, and cell cycle analysis to evaluate the anticancer activities of the extracts. The polysaccharide extract was characterized for sulfate content and structure using barium chloride-gelatin and FT-IR methods. Results: All J. rubens extracts exhibited significant anticancer effects, with the polysaccharide extract showing particularly strong cytotoxicity, apoptosis induction, and antiproliferative and anti-migratory activities. Conclusion: These findings confirm that J. rubens is a source of bioactive compounds with anticancer potential. Further investigations are needed to elucidate the molecular pathways targeted by J. rubens extracts in cancer cells.

Anticancer Activity and GC-MS Profiling of Bioactive Constituents in the Methanolic Extracts of Spatoglossum variabile and Gracilaria corticata

Background: Marine algae stand out as repositories of bioactive metabolites, widely harnessed in treating diverse diseases. Given the often-challenging side effects associated with conventional cancer treatments, researchers are increasingly turning their attention to marine algae as a promising source for discovering novel and potent anticancer compounds. In this study, we meticulously explored the potential anticancer activity of Spatoglossum variabile and Gracilaria corticata sourced from the Indian Ocean. Materials and Methods: The secondary metabolites were extracted using methanol solvent according to the standard protocol. The extract was subjected to GC-MS analysis and evaluated for its short- and long-term cytotoxicity and anti-proliferative ability in the HCT116 cell line using MTT, clonogenic, and trypan blue dye exclusion assays, respectively. Results and Discussion: The methanolic extract of Spatoglossum variabile contained 21 unique anticancer compounds, except for the other bioactive compounds. The results indicate that increasing the concentration of algal extracts decreased the cell viability significantly, with an IC50 of 51.49 μg/mL and 37.50 μg /mL in the HCT116 cell line. The results showed a significant reduction in colorectal cancer colony formation and a gradual reduction in cell proliferation. These results underscore the potential for targeted, low-toxicity biomedicines due to their selective cytotoxicity against cancer cells. Conclusion: Our findings show that Spatoglosuum variabile &amp; Gracilaria corticata extracts contain various bioactive compounds, display long-term and short-term cytotoxicity and antiproliferative effects, which indicates that their constituent compounds might be further refined into effective anti-colorectal cancer medications.

Ancient frameworks as modern templates: exploring reef rubble consolidation in an ancient reef system.

Both natural and human-induced stressors cause reef erosion, resulting in reef rubble formation. When consolidated, the rubble can facilitate reef recovery, sparking interest in artificial rubble stabilization as a method for reef restoration. However, our understanding of the natural processes governing coral reef regeneration within rubble beds is limited. This study examines the regeneration processes within ancient rubble frameworks in a Late Triassic carbonate platform. Results show that Late Triassic rubble environments exhibit successional trajectories similar to contemporary rubble environments. Key organisms such as sponges, calcareous red algae, bryozoans, microbes and scleractinian corals, which are instrumental in the consolidation of modern reef rubble, appear to have played comparable roles during the Late Triassic. The similarities between Late Triassic and modern reef rubble consolidation highlight enduring ecological mechanisms important for reef regeneration. This study deepens our understanding of reef dynamics and offers valuable insights for improving current reef restoration strategies, grounded in time-tested natural processes.

Expression of Concern: "Investigation of bionano additives in red algae Cyanidioschyzon merolae ultrasonified MgO/MWCNT catalyzed biodiesel in optimized engine performance" [Environ. Res., 258 (2024) 119352

Expression of Concern: "Investigation of bionano additives in red algae Cyanidioschyzon merolae ultrasonified MgO/MWCNT catalyzed biodiesel in optimized engine performance" [Environ. Res., 258 (2024) 119352

Exploring the multifaceted bioactivities of silver nanoparticles synthesized from red algae Hypnea pannosa: Antimicrobial, antibiofilm, and insecticidal potentials

Exploring the multifaceted bioactivities of silver nanoparticles synthesized from red algae Hypnea pannosa: Antimicrobial, antibiofilm, and insecticidal potentials

Mechanisms of nutrient absorption and transport of digestion and fermentation metabolites in fish balls with red algae polysaccharides

Mechanisms of nutrient absorption and transport of digestion and fermentation metabolites in fish balls with red algae polysaccharides

Biomimetic gaseous plastron for blocking fouling-associated biological colonization

Biomimetic gaseous plastron for blocking fouling-associated biological colonization

FILMES BIODEGRADÁVEIS ELABORADOS A PARTIR DE AMIDO DE MANDIOCA: UMA ANÁLISE DAS INOVAÇÕES SUSTENTÁVEIS

The search for alternatives to the use of plastic as packaging has been driving the adoption of new materials, has motivated the use of materials from renewable sources and biodegradables. The objective of this work was to carry out a descriptive bibliographic survey on research that focused on the use of cassava starch in the production of biodegradable films. The survey was carried out by consulting four data platforms: Web of Science, ScienceDirect, Pub med and Scopus. Having as search keywords the English terms "Cassava starch and biodegradable film". Articles published in the years 2018 to 2024 were selected, in journals with Qualis A1 classification with CAPES, with open access to the articles and the survey was carried out until the nineteenth day of November 2024. After consulting the platforms, 15 published studies with relevance to the theme developed were selected. They individually report the incorporation into the film made with cassava starch in different concentrations of materials such as yerba mate extract, cassava peel and bagasse, corn and cassava starch, bagasse from the production of blueberry juice, kappa caragenin (red algae extract), metakaolin, lignocellulose nanoparticles from cassava bagasse, nightshade extract, application of nanocompounds of metals such as zinc and cerium, Ocimum tenuiflorum and propolis by-product. And that after being tested and characterized by different techniques, such materials proved to be interesting as a way to promote the improvement of cassava starch films in relation to applicability as biodegradable packaging.

Molecular and functional convergences associated with complex multicellularity in Eukarya.

A key trait of Eukarya is the independent evolution of complex multicellular (CM) in animals, plants, fungi, brown algae and red algae. This phenotype is characterized by the initial exaptation of cell-cell adhesion genes followed by the emergence of mechanisms for cell-cell communication, together with the expansion of transcription factor gene families responsible for cell and tissue identity. The number of cell types (NCT) is commonly used as a quantitative proxy for biological complexity in comparative genomics studies. While expansions of individual gene families have been associated with NCT variation within individual CM lineages, the molecular and functional roles responsible for the independent evolution of CM across Eukarya remain poorly understood. We employed a phylogeny-aware strategy to conduct a genomic-scale search for associations between NCT and the abundance of genomic components across a phylogenetically diverse set of 81 eukaryotic species, including species from all CM lineages. Our annotation schemas represent two complimentary aspects of genomic information: homology - represented by conserved sequences - and function - represented by Gene Ontology (GO) terms. We found many gene families sharing common biological themes that define CM to be independently expanded in two or more CM lineages, such as components of the extracellular matrix, cell-cell communication mechanisms, and developmental pathways. Additionally, we describe many previously unknown associations of biological themes and biological complexity, such as mechanisms for wound response, immunity, cell migration, regulatory processes, and response to natural rhythms. Together, our findings unveil a set of functional and molecular convergences independently expanded in CM lineages likely due to the common selective pressures in their lifestyles.

Impact of the Biostimulants Algevit and Razormin on the Salinity Tolerance of Two Tomato Cultivars

The global water crisis and the expansion of saline soils present significant challenges to agricultural sustainability. To address these issues, innovative solutions are needed to harness seawater and adapt plants to high-salinity conditions. Biostimulants represent an innovative strategy for mitigating the adverse effects of salinity on crops. This study examined the impact of two biostimulants, Algevit (based on marine algae) and Razormin (based on plant extracts), on the salinity tolerance of two Romanian tomato varieties, Buzau 4 and Buzau 22. The research was conducted under greenhouse conditions and assessed parameters such as plant height, flower and fruit counts, photosynthetic fluorescence, chlorophyll content, stomatal conductance, and proline concentration. The results showed that Algevit had a more significant impact compared to Razormin, enhancing plant growth, maintaining higher chlorophyll levels (in the Algevit variants, values ranged from 27.43 to 44.99 SPAD units, while in the Razormin variants, they ranged from 24.23 to 41.63 SPAD units), and improving photosynthetic efficiency. Both tomato varieties responded positively to the treatments, with Buzau 4 demonstrating greater salinity tolerance, especially when treated with Algevit. These findings suggest that integrating biostimulants into crop management can effectively reduce the negative effects of salinity and support sustainable agriculture in salt-affected regions. The study highlights the importance of applying biostimulants in managing soil salinity and freshwater scarcity in the context of climate change.

Macrobenthic red algae and their hydrocarbon generation in the Paleogene deep-water source rocks, Qiongdongnan Basin

To solve the contradiction between the discovery of natural gas field in the deep water area of Qiongdongnan Basin under the background of low organic matter abundance of Paleogene (Oligocene) source rocks and the current recognition of higher plants as the main source material, selects four exploration wells in the study area for the first time with the help of “mild” maceration kerogen identification technology and scanning electron microscopy observation, and finds that the source materials are mainly marine macrobenthic red algae with high abundance rather than the before thought higher plants. The marine macrobenthic red algae have the characteristics of early oil generation and late gas generation, especially in the high to over mature stage, which has a good gas prospect. It is the first time to find the source rocks with carpospores and the disk-shaped hard pads as the main source materials in China and abroad, which indicates that macrobenthic red algae are a kind of source materials that should not be ignored, which provides a possible explanation for the formation of large gas fields in the deep water area of Qiongdongnan Basin under the background of low organic matter abundance of source rocks.

Biochemical evidence for the diversity of LHCI proteins in PSI-LHCI from the red alga Galdieria sulphuraria NIES-3638.

Red algae are photosynthetic eukaryotes whose light-harvesting complexes (LHCs) associate with photosystem I (PSI). In this study, we examined characteristics of PSI-LHCI, PSI, and LHCI isolated from the red alga Galdieria sulphuraria NIES-3638. The PSI-LHCI supercomplexes were purified using anion-exchange chromatography followed by hydrophobic-interaction chromatography, and finally by trehalose density gradient centrifugation. PSI and LHCI were similarly prepared following the dissociation of PSI-LHCI with Anzergent 3-16. Polypeptide analysis of PSI-LHCI revealed the presence of PSI and LHC proteins, along with red-lineage chlorophyll a/b-binding-like protein (RedCAP), which is distinct from LHC proteins within the LHC protein superfamily. RedCAP, rather than LHC proteins, exhibited tight binding to PSI. Carotenoid analysis of LHCI identified zeaxanthin, β-cryptoxanthin, and β-carotene, with zeaxanthin particularly enriched, which is consistent with other red algal LHCIs. A Qy peak of chlorophyll a in the LHCI absorption spectrum was blue-shifted compared with those of PSI-LHCI and PSI, and a fluorescence emission peak was similarly shifted to shorter wavelengths. Based on these results, we discuss the diversity of LHC proteins and RedCAP in red algal PSI-LHCI supercomplexes.

Ecosystem changes after Early Cretaceous seawater intrusion into the proto-South Atlantic Ocean

The early evolution of the South Atlantic Ocean following the Cretaceous break-up of Gondwana is extensively recorded in rift basins along the conjugate margins of Africa and Brazil. For the Brazil side, divergent views of the source and pathway of the initial seawater incursion persist due to a paucity of recognized transitional sequences that document marine transgressive deposits over the continental interior. To address this, we conducted a high-resolution sedimentological and geochemical study through a core in the Campos Basin that encompasses the key lithologic switch from lacustrine carbonate to marine evaporite settings. Steroid lipid biomarkers, derived from pelagophyte marine algae, make a striking appearance in concert with a pronounced negative shift of 87Sr/86Sr ratios and coincident with the appearance of anhydrite. Importantly, the sulfur-sequestered biomarkers reveal a dynamic system where redox-stratified and anoxic conditions were amplified along with a deepening chemocline through the marine transition.

The Effect of Fermentation Time on the Chemical and Sensory Characteristics of Yoghurt Containing Eucheuma cottonii Seaweed

Eucheuma cottonii is a seaweed from the Rhodophyta group (red algae) which is widely used in the food industry, especially carrageenan. The fiber content in seaweed comes from cellulose and hemicellulose, carrageenan, agar, and alginate. Yogurt has an important role in the body, such as maintaining stomach health, preventing cancer, and improving the digestive tract. This study aims to determine the effect of fermentation time on the chemical and sensory characteristics of yogurt added with Eucheuma cottonii seaweed. The long fermentation treatment used consisted of P1 = 12 hours; P2= 14 hours; and P3 = 16 hours. The addition of E. Cottonii seaweed to yogurt with a 12-hour fermentation time showed the highest parameters by SNI yogurt compared to other treatments. These parameters consist of moisture content, fat content, and ash content. The fermentation time of 16 hours in yogurt containing E. Cottonii seaweed showed the highest effect on sensory characteristics compared to other treatments. Based on this, yogurt fermentation time can determine the chemical and sensory characteristics of the product.

Molecular glue for phycobilisome attachment to photosystem II in Synechococcus sp. PCC 7002

Phycobilisomes (PBS) are the major photosynthetic light-harvesting complexes in cyanobacteria and red algae. While the structures of PBS have been determined in atomic resolutions, how PBS are attached to the reaction centers of photosystems remains less clear. Here, we report that a linker protein (LcpA) is required for the attachment of PBS to photosystem II (PSII) in the cyanobacterium Synechococcus sp. PCC 7002. We also report that the PB-loop of PBS, which is located within the α-APC domain of ApcE, is required for the attachment of PBS to PSII. Deletion of either PB-loop or the gene A0913 led to a decreased rate of photoautotrophic growth under illumination of green light, which is preferentially absorbed by PBS. A double mutant lacking the PB-loop and A0913 (ΔPBL-0913) showed a complete inhibition of O2 evolution under the 590 nm light and could not grow under green light illumination. While assembled PBS could be isolated from ΔPBL-0913, the energy transfer from its PBS to PSII was blocked as measured by fluorescence induction. Photobleaching with intact cells showed that the PBS movement speed in ΔPBL-0913 was 2.5 times as fast as that of the wild type, suggesting that association of its PBS with thylakoids was weakened significantly. The pull-down and coimmunoprecipitation results showed that the LcpA interacts with the CP47 subunit of PSII through its N-terminal region and interacts with ApcB of PBS through its C-terminal α-helix motif. Our results provide insights into the molecular mechanism of PBS-PSII association and shed light on excitation energy transfer from PBS to PSII.

Functional and Bioactive Benefits of Selected Microalgal Hydrolysates Assessed In Silico and In Vitro

BIOPEP-UWM, a peptide database, contains 5128 peptides from a myriad of resources. Five listed peptides are Angiotensin-I-converting enzyme (ACE-1; EC3.4.15.1) inhibitory peptides derived from a red alga, while two from Chlorella vulgaris have anti-cancer and antioxidative bioactivities. Herein, we describe a process combining hydrolysis with two enzymes, Alcalase and Viscozyme, and filtration to generate protein-rich, bioactive peptide-containing hydrolysates from mixed species of Chlorella sp. and Scenedesmus sp. The potential of generated algal hydrolysates to act as food ingredients was determined by assessment of their techno-functional (foaming, emulsification, solubility, water holding, and oil holding capacity) properties. Bioactive screening of hydrolysates in vitro combined with mass spectrometry (MS) and in silico predictions identified bioactive and functional hydrolysates and six novel peptides. Peptides derived from Chlorella mix have the sequences YDYIGNNPAKGGLF and YIGNNPAKGGLF with predicted anti-inflammatory (medium confidence) and umami potential. Peptides from Scenedesmus mix have sequences IEWYGPDRPKFL, RSPTGEIIFGGETM, TVQIPGGERVPFLF, and IEWYGPDRPKFLGPF with predicted anti-inflammatory, anti-diabetic, and umami attributes. Such microalgal hydrolysates could provide essential amino acids to consumers as well as tertiary health benefits to improve human global health.