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The number of newly described species has increased since the addition of molecular data to taxonomic studies, revealing that species considered widely distributed by morphological and anatomical studies are often comprised of complexes of several distinct species. This study reports on a new turf-forming species of Digenea from the Greater Caribbean (South Florida and eastern Cuba), previously identified as D. simplex based on morpho-anatomical characters, but shown through DNA sequences to be a distinct species. Digenea nana sp. nov. is characterized by its small brush appearance, small dimensions (2.5 cm high and 0.6 mm wide), long determinate branches reaching 15 mm in length (its most striking feature) and 11–12 pericentral cells. Digenea nana is distinct from all its congeners, showing sequence divergences of 3.5–5.0% in COI-5P and 1.7–2.7% in rbcL. The species resolved as sister to D. rafaelii (genetic distance of about 3.5% and 1.7% in COI-5P and rbcL respectively) from Pacific Mexico, and can be easily distinguished by morpho-anatomical characters. Digenea nana is the seventh species in the genus worldwide. Given the presumed wide distribution of D. simplex, based solely on morpho-anatomy, and the number of cryptic and pseudo-cryptic species recently described, further integrative molecular and morpho-anatomical studies are likely to reveal new taxa. [ABSTRACT FROM AUTHOR]

Specimens of Hildenbrandia bearing conceptacles that contained small, bead-shaped reproductive cells, only 3–4 µm wide, features diagnostic of Hildenbrandia sanjuanensis, were collected from the high intertidal zone at the type locality of the species. Examination of conceptacle contents by transmission electron microscopy was used to detail the differentiation of the catenate reproductive cells, and it revealed that these cells were joined by pit connections. Tetraspores are the only known reproductive cells in the Hildenbrandiales, but the process of cleaving tetrasporangia to form tetraspores has never been found to include the deposition of pit plugs in any red alga. An alternative interpretation of the nature of the reproductive cells of H. sanjuanensis is that they are spermatia or carpospores. The features of small size, sparse chloroplasts with few thylakoids, and near absence of starch contents in the reproductive cells favours the view that these cells are spermatia. If this interpretation is correct, it represents the first evidence of spermatia in any member of the Hildenbrandiophycidae, and it indicates that the possibility of a sexual life history in members of this order should be re-examined. [ABSTRACT FROM AUTHOR]

In current study, proximate compositions (ash, lipid and protein) of seven Red macroalgae (Laurencia obtusa, Liagora viscida, Liagora ceranoides, Gracilaria bursa-pastoris, Carradoriella elongata, Halopithys incurva and Tricleocarpa fragilis) collected from Turkey (Çanakkale and Antalya) were determined. The differences observed between biochemical compositions such as ash, lipid and protein of seven red macroalgae species were statistically significant (p<0.05). The lowest and highest ash, lipid and protein values of seven red macroalgae were 38.86±0.15% (Gracilaria bursa-pastoris)- 85.61±0.22% (Tricleocarpa fragilis), 0.23±0.02% (Tricleocarpa fragilis)- 1.87±0.08% (Carradoriella elongata), 2.79±0.02% (Liagora ceranoides)- 9.72±0.35% (Halopithys incurva), respectively. Gracilaria bursa-pastoris (38.86±0.15%), Carradoriella elongata (42.89±0.06%) and Halopithys incurva (42.28±0.44%) were similar each other (p>0.05). The lipid (Liagora viscida (0.44±0.07%), Liagora ceranoides (0.42±0.07%), Gracilaria bursa-pastoris (0.43±0.04%)) and protein (Tricleocarpa fragilis (2.93±0.39%), Liagora ceranoides (2.79±0.02%)) amounts of red macroalgae tested in study were similar each other (p>0.05) but the different from other red macroalgae (p<0.05). In conclusion, the information of the proximate compositions of seven red macroalgae are important for the evaluation of potential sources for commercial and human consumption. In addition, proximate compositions of tested macroalgae could make important contributions to feed formulations and functional foods in future. [ABSTRACT FROM AUTHOR]

In Kongsfjorden (Spitsbergen), we quantified the zonation of visually dominant macroalgal taxa and of detached macroalgae from underwater videos taken in summer 2009 at six transects between 2 and 138 m water depth. For the first time, we provide information on the occurrence of deep water red algae below the kelp forest and of detached macroalgae at water depth > 30 m. The presence and depth distribution of visually dominant red algae were especially pronounced at the outer fjord, decreased with proximity to the glacial front and they were absent at the innermost locations. Deepest crustose coralline red algae and foliose red algae were observed at 72 and 68 m, respectively. Brown algae were distributed along the entire fjord axis at 2–32 m. Green algae were only present at the middle to inner fjord and at areas influenced by physical disturbance at water depths of 2–26 m. With proximity to the inner fjord the depth distribution of all macroalgae became shallower and only extended to 18 m depth at the innermost location. Major recipients of detached macroalgae were sites at the shallower inner fjord and at the middle fjord below the photic zone at depths to 138 m. They may either fuel deep water secondary production, decompose or support carbon sequestration. Univariate and community analyses of macroalgal classes including detached macroalgae across transects and over depths reveal a considerable difference in community structure between the outermost sites, the central part and the inner fjord areas, reflecting the strong environmental gradients along glacial fjords. [ABSTRACT FROM AUTHOR]

Sulfated polysaccharides (SPs) from seaweeds are potential bioactive natural compounds, but their DNA protective activity is poorly explored. This article aimed to evaluate the genotoxic/antigenotoxic potentials of a sulfated heterofucan from brown seaweed Spatoglossum schröederi (Fucan A – FA) and a sulfated galactan from green seaweed Codium isthomocladum (3G4S) using in vitro Comet assay (alkaline and oxidative versions) with HepG2 cells. The antioxidant activity of these SPs was evaluated by total antioxidant capacity, radical scavenging, metal chelating, and antioxidant enzyme activity assays. Both SPs were not genotoxic. FA and 3G4S displayed strong antigenotoxic activity against oxidizing chemical (H 2 O 2) but not against alkylating chemical (MMS). The DNA damage reduction after a pre-treatment of 72 h with these SPs was 81.42% to FA and 81.38% to 3G4S. In simultaneous exposure to FA or 3G4S with H 2 O 2 , HepG2 cells presented 48.04% and 55.41% of DNA damage reduction compared with the control, respectively. The antigenotoxicity of these SPs relates to direct antioxidant activity by blockage of the initiation step of the oxidative chain reaction. Therefore, we conclude that FA and 3G4S could be explored as functional natural compounds with antigenotoxic activity due to their great protection against oxidative DNA damage. [ABSTRACT FROM AUTHOR]

Seaweeds are considered natural sources of chemical compounds with notable potent antioxidant and antidiabetic activities. The study aims to know the total polyphenolic content (TPC) and assess the antioxidant and antidiabetic activities of Sargassum polycystum for potential pharmacological use. The seaweed has a TPC of 1.149 ± 0.22 mg GAE/g. Antioxidant activity of S. polycystum is characterized by having potent scavenging activity against ABTS+ radical and high copper reduction capacity with IC50 value of 49.50 μg GAE/ml and 20.40 μg GAE/ml, respectively, more effective than ascorbic acid (control). Assessment of the antidiabetic properties of S. polycystum was done in vitro via α-amylase and α-glucosidase inhibition assay. Results of the analysis proved that S. polycystum has potent α-amylase (IC50 of 0.264 μg/ml) and α- glucosidase (IC50 of 120 μg/ml) inhibition activities in collation to that of acarbose (antidiabetic drug) with IC50 values of 4.81μg/ml and 6771 μg/ml, respectively. This study is a pioneering research investigation in the Philippines describing the bioactive properties of S. polycystum as renewable source of bioactive substances for inhibition of important carbohydrate degrading enzymes. [ABSTRACT FROM AUTHOR]

The red seaweed, Grateloupia gibbesii, was recently reported as an introduced species in the Mediterranean Sea. Being non-indigenous species with limited distribution, where it was recorded only in Egypt, it was assumed that it has developed several defensive mechanisms to adapt to the new environment through the production of various biological active metabolites. This species was distinguished by its high lipid content in comparison to other seaweeds; accordingly, spectroscopic screening was performed for the chemical characterization of different extracts of G. gibbesii using UV–Vis spectrophotometer and FTIR spectroscopy. In addition, the lipids and fatty acid profile of chloroform extract were characterized using GC-MS. About 45 molecular species were reported in crude and esterified lipid extracts. Among these chemical species, important volatile organic compounds were identified which have many applications in pharmaceutical and chemical industries. The nutritional quality indices of lipids such as ω6/ω3, P/S, IA, IT, and HH were found to be comparable to or higher than those reported for commercial fish species. In addition to the high nutritional value of G. gibbesii, the long-chain UFAs are valuable constituents for cosmetic production, where they play an important role in maintaining healthy skin by regaining the elasticity level and resisting the harmful effects of UV radiation as indicated in UV–visible spectroscopic analysis. On the other hand, the distinct level of TL (12%), TFA to TL (72.1 %), and SFAs to TFA (44.4%) makes G. gibbesii suitable for the production of biodiesel. Pilot-scale production of this seaweed species for sustainable production of pharmaceuticals or biofuel is highly recommended. [ABSTRACT FROM AUTHOR]

Gracilariales is a clade of florideophycean red macroalgae known for being the main source of agar. We present a de novo genome assembly and annotation of Gracilaria domingensis, an agarophyte alga with flattened thallus widely distributed along Central and South American Atlantic intertidal zones. In addition to structural analysis, an organizational comparison was done with other Rhodophyta genomes. The nuclear genome has 78 Mbp, with 11,437 predicted coding genes, 4,075 of which did not have hits in sequence databases. We also predicted 1,567 noncoding RNAs, distributed in 14 classes. The plastid and mitochondrion genome structures were also obtained. Genes related to agar synthesis were identified. Genes for type II galactose sulfurylases could not be found. Genes related to ascorbate synthesis were found. These results suggest an intricate connection of cell wall polysaccharide synthesis and the redox systems through the use of L‐galactose in Rhodophyta. The genome of G. domingensis should be valuable to phycological and aquacultural research, as it is the first tropical and Western Atlantic red macroalgal genome to be sequenced. [ABSTRACT FROM AUTHOR]

Three new species of the red algal genus Asteromenia (Hymenocladiaceae, Rhodophyta) are described based on morphological and molecular analyses. DNA analyses of recent collections of topotype specimens of A. examinans from the Houtman Abrolhos Islands (Western Australia) have revealed that the specimens used in earlier studies were misidentified and represent an undescribed species, herein described as A. juliannae. Two additional new species, A. crenulata and A. praetermissa are described from the Cocos (Keeling) Islands, and Norfolk Island, respectively. For the most part, the new species showed morphological overlap and could not be discriminated based on morphology alone; DNA sequencing is therefore considered essential for accurate species recognition. The potential for misidentification of morphologically similar specimens highlights the need for sequence analyses and reference barcoding to be based on type or topotype specimens. The adoption of molecular methods in alpha taxonomy has led to the recognition of considerable diversity in the Rhodymeniales and it is envisaged that further collecting will add even more taxa to Australia's rich algal flora. [ABSTRACT FROM AUTHOR]

Genetic diversity and distribution patterns of marine macroalgae are increasingly being documented in Southeast Asia. These studies show that there can be significant levels of genetic diversity and isolation between populations on either side of the Thai-Malay Peninsula. Bostrychia tenellla is a common filamentous red seaweed in the region and the entity is represented by at least two cryptic species. Despite being highly diverse and widespread, genetic variation and population structure of this species complex remains understudied, especially around the Thai-Malay Peninsula. We analyzed genetic diversity and inferred the phylogeographic pattern of specimens identified as B. tenella using the plastid RuBisCo spacer from samples from the Andaman Sea and the Gulf of Thailand. Our genetic analysis confirmed the occurrence of the two cryptic B. tenella species (B and C) along both coasts. Cryptic species B was more common in the area and displayed higher genetic diversity than species C. Historical demographic analyses indicated a stable population for species B, but more recent population expansion for species C. Our analyses also revealed that both cryptic species from the Andaman Sea possessed higher genetic diversity than those of the Gulf of Thailand. We also detected moderate to high levels of gene flow and weak phylogeographic structure of cryptic species B between the two coasts. In contrast, phylogeographic analysis showed genetic differences between populations of both cryptic species within the Andaman Sea. Overall, these results suggest that cryptic B. tenella species around Thai-Malay Peninsula may have undergone different demography histories, and their patterns of genetic diversity and phylogeography were likely caused by geological history and regional sea surface current circulation in the area. [ABSTRACT FROM AUTHOR]

Sargassum fusiforme is often adversely affected by epiphytic algae during its cultivation. However, the biological differences between S. fusiforme and the epiphytic algae have not yet been elucidated detrimental to the management of S. fusiforme culture. In this study, we sampled S. fusiforme and main epiphytic algae Ulva lactuca in a marine culture cycle and compared their biological characteristics. It indicated that, except during low‐temperature months (January and March), the photosynthetic electron activity of U. lactuca were generally higher than S. fusiforme. The nitrogen uptake rates of S. fusiforme and U. lactuca were all significantly higher in the earlier growth stage than other stages. In most cases, the nitrogen uptake and utilization of U. lactuca was higher than those of S. fusiforme. Although S. fusiforme absorbed more trace elements, U. lactuca had relatively strong photosynthesis and nutrient absorption performance; thus, the latter accumulated more soluble carbohydrate and protein and may have stress effect on S. fusiforme. This study will be helpful for understanding the differences in the biological characteristics of economic seaweed and its epiphytic macroalgae and provides a reference for the friendly management and healthy development of seaweed cultivation. [ABSTRACT FROM AUTHOR]

The aim of this study was to extract the polyphenols from three major seaweed species such as Sargassum miyabei, Undaria pinnatifida suringar, and Sargassum thunbergii, which are found in the coastal province (Guangdong), a longest coastal line in China. It was found that the Sargassum thunbergii produced more polyphenols (34.99 mg) as compared to Sargassum miyabei (23.26 mg) and Undaria pinnatifida suringar (25.34 mg), respectively. The orthogonal method was used for the extraction of phenolic compounds and extraction condition of each seaweed species was optimized. The antioxidant activity of extracted polyphenols from all three species stated that the polyphenols extracted from Undaria pinnatifida suringar demonstrated the highest antioxidative activity. Furthermore, gas chromatography–mass spectrometry (GC‐MS) was used for qualitative analysis of polyphenols, which revealed that the major components of polyphenols extracted from Undaria pinnatifida suringar were gallic acid and arbutin followed by syringate in Sargassum miyabei and phloretin in Sargassum thunbergii. [ABSTRACT FROM AUTHOR]

Algae biomass could be one of the most important economic values in near future. For this reason, we determined the biochemical compositions and molecular weight profiles (MWPs) of eight macroalgae; Green Algae (Codium fragile, Ulva intestinalis, Chaetomorpha linum, and Codium bursa), Red Algae ( Ellisolandia elongata, Jania rubens, and Amphiroa rigida), Brown Algae (Padina pavonica) collected from different regions in Turkey. The differences measured between biochemical compositions such as ash, lipid, and protein of macroalgae species were statistically significant (P<0.05). The lowest and highest ash, lipid, and protein values of eight macroalgae tested were 30.599 ± 2.739 % (Ulva intestinalis) -81.231 ± 0.527 % (Amphiroa rigida), 0.190 ± 0.063 % (Ellisolandia elongata) -1.764 ± 0.090 % (Chaetomorpha linum), and 2.057 ± 0.093 (Amphiroa rigida) -15.280 ± 0.621 (Chaetomorpha linum). The highest levels of MWP of macroalgae tested were determined in 2532 Da ≥. The lowest levels of MWP belonging to the macroalgae was observed in 2532-13000 Da except for Ulva intestinalis and Padina pavonica belonging to 67000 Da ≤. The values observed 2532 Da ≥ were similar to each other except for Ulva intestinalis. The 13700 - 67000 Da and 2532-13000 Da levels belonging to Ulva intestinalis were higher than those of other tested macroalgae. However, level of Ulva intestinalis (67000 Da ≤) was lower than those of tested macroalgae species, followed by Padina pavonica. In conclusion, biochemical compositions of tested macroalgae can make important contributions to feed formulations and functional foods. In addition, based on our biochemical composition analysis the specific macroalgae species are the most promising algal content for use in different industrial areas such as cosmetics, drugs, and functional foods. [ABSTRACT FROM AUTHOR]

Gastropods are an important component of subtidal Antarctic communities including in common association with macroalgae. Nonetheless, limited data exist detailing their abundance and distribution on macroalgal species. This study documents the abundance and species composition of gastropod assemblages on the two largest, blade-forming Antarctic macroalgae, Himantothallus grandifolius and Sarcopeltis antarctica, sampled across two depths (9 and 18 m) at four sites for each species off Anvers Island, Antarctica. Gastropods were also enumerated on Desmarestia anceps, Desmarestia antarctica and Plocamium sp. but were not included in the main analyses because of small sample sizes. There were major differences between the gastropod assemblages on deep vs shallow H. grandifolius and S. antarctica with much higher numbers of individuals and also greater numbers of gastropod species at the greater depth. Differences between the gastropod assemblages on H. grandifolius and S. antarctica across sampling sites were apparent in non-parametric, multivariate analyses, although depth contributed more than site to these differences. Within common sites, assemblages on H. grandifolius were significantly different from those on S. antarctica at 18 m depth but not at 9 m depth, indicating that the host species can be but is not always more important than site in influencing the gastropod assemblages. [ABSTRACT FROM AUTHOR]

In this study, the new record of the non-indigenous Rhodophyta Antithamnionella spirographidis (Schiffner) Wollaston (1968) has been reported from the Marmara Sea that the connection area between the Mediterranean Sea and the Black Sea. The species, originally described from Trieste (Northern Adriatic Sea), is currently known throughout the Central and Western Mediterranean Sea. Our finding is the easternmost record of this tiny filamentous alga in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Copper (Cu) is a crucial element that plays a vital role in facilitating proper biological activities in living organisms. In this study, copper oxide nanoparticles (CuO NPs) were synthesized using a straightforward precipitation chemical method from a copper nitrate precursor at a temperature of 85 °C. Subsequently, these NPs were coated with the aqueous extract of Sargassum angustifolium algae. The size, morphology, and coating of the NPs were analyzed through various methods, revealing dimensions of approximately 50 nm, a multidimensional shaped structure, and successful algae coating. The antibacterial activity of both coated and uncoated CuO NPs against Vibrio harveyi , a significant pathogen in Litopenaeus vannamei , was investigated. Results indicated that the minimum inhibitory concentration (MIC) for uncoated CuO NPs was 1000 μg/mL, whereas for coated CuO NPs, it was 500 μg/mL. Moreover, the antioxidant activity of the synthesized NPs was assessed. Interestingly, uncoated CuO NPs exhibited superior antioxidant activity (IC50 ≥ 16 μg/mL). The study also explored the cytotoxicity of different concentrations (10–100 μg/mL) of both coated and uncoated CuO NPs. Following 48 h of incubation, cell viability assays on shrimp hemocytes and human lymphocytes were conducted. The findings indicated that CuO NPs coated with alga extract at a concentration of 10 μg/mL increased shrimp hemocyte viability. In contrast, uncoated CuO NPs at a concentration of 25 μg/mL and higher, as well as CuO NPs at a concentration of 50 μg/mL and higher, led to a decrease in shrimp hemocyte survival. Notably, this study represents the first quantitative assessment of the toxicity of CuO NPs on shrimp cells, allowing for a comparative analysis with human cells. [Display omitted] • Enhanced antibacterial activity of CuO NPs against Vibrio harveyi. • Coated NPs enhance shrimp hemocyte viability, highlighting potential benefits. • First-ever study comparing CuO NPs toxicity in shrimp and human cells. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effect of adding liquid extract of algae (Hypnea musciformis, Grateloupia acuminata, and Sargassum muticum) (HGS) and Magnesium oxide nanoparticles (MgO NPs) using this extract to rear water of Oreochromis niloticus, on improving culture water indices, growth performance, digestive enzyme, hemato-biochemical characters, immune, antioxidative responses, and resistance after challenged by Aeromonas hydrophila with specific refer to the potential role of the mixture in vitro as resistance against three strains bacteria (Aeromonas sobria, Pseudomonas fluorescens, P. aeruginosa) and one parasite (Cichlidogyrus tilapia). The first group represented control, HGS0, whereas the other group, HGS5, HGS10, and HGS15 mL−1 of liquid extract, as well as all groups with 7.5 μg mL−1 MgO-NPs added to culture water of O. niloticus, for 60 days. Data showed that increasing levels at HGS 10 and HGS15 mL−1 in to-culture water significantly enhanced growth-stimulating digestive enzyme activity and a significantly improved survival rate of O. niloticus after being challenged with A. hydrophila than in the control group. The total viability, coliform, fecal coliform count, and heavy metal in muscle partially decreased at HGS 10 and HGS15 mL−1 than in the control group. Correspondingly, the highest positive effect on hemato-biochemical indices was noticed at levels HGS 10 and HGS15 mL−1. Fish noticed an improvement in immune and antioxidant indices compared to control groups partially at HGS 10 and HGS15 mL−1. Interestingly, fish cultured in rearing water with the mixture provided downregulated the related inflammatory genes (HSP70, TNF, IL-1β, and IL-8) partially at HGS15 mL−1. In vitro, the mixture showed positive efficiency as an antibacterial and partially antiparasitic at HGS 10 and HGS15 mL−1. This study proposes utilizing a mixture of (HGS) and (MgO-NPs) with optimum levels of 10–15 mL-1 in cultured water to improve water indices, growth, health status, and increased resistance of O. niloticus against bacterial and parasitic infection. • Seaweed mixture extract (HGS) and (MgO-NPs) synthesis (HGS) was added to cultured water as a natural agent of Nile tilapia. • Including blend improves growth, health status, and resistance against pathogenic. • Immune response and antioxidant activities were significantly improved with increasing blend levels. • Blend controlled the inflammatory and stress-associated genes of tilapia. • (HGS) and (MgO-NPs) with optimum 10 - 15 mL-1 levels in cultured water improve water indices. [ABSTRACT FROM AUTHOR]

Macroalgae play crucial roles as major habitat-forming organisms in marine ecosystems, having significant impacts on coral recruitment and reef recovery. However, the interactions between marine macroalgae and coral larvae remain poorly understood. Furthermore, little is known whether differences in bacterial assemblages associated with macroalgae may play roles in this process. Here, we comprehensively investigated the impacts of different macroalgae and their associated microbiomes on larval settlement and survival of coral Pocillopora damicornis. The results revealed significant variations in larval settlement and survival rates when exposed to different macroalgal species. The highest settlement rate, reaching 90%, was observed in the presence of the red alga Hypnea pannosa , followed by green algae Caulerpa serrulata , C. racemosa , and brown algae Turbinaria gracilis , Sargassum polycystum. Correspondingly, similarities in bacterial compositions were observed between H. pannosa and C. racemosa , as well as between T. gracilis and S. polycystum , implying associated bacterial may be related with the algal functions. Furthermore, macroalgae that facilitate larval settlement exhibited higher abundances of amplicon sequence variants (ASVs) associated with the metabolism of dimethylsulfoniopropionate or the antagonism of known coral pathogens. However, the brown alga Padina boryana failed to induce larval settlement with survival rate of zero after 120 h. The algal species harbored more abundances of ASVs related to Rhizobiaceae. These findings highlight the significant impact of macroalgae and their associated microbiomes on coral recruitment, as they influence both larval settlement and survival rates. [Display omitted] • The effect of macroalgae on Po. damicornis larvae was species-specific. • Hypnea pannosa , Caulerpa serrulate and C. racemosa significantly promoted the settlement of coral larvae. • The survival rate of coral larvae was influenced negatively by Pa. boryana and T. gracilis. • Algal species that facilitate larval settlement had similar bacterial compositions. • Bacterial assemblages associated with macroalgae may play roles in coral recruitment. [ABSTRACT FROM AUTHOR]

Green macroalgae of the Ulva genus have gained interest as a source of protein, due to the high production potential and high proportion of essential amino acids. This review gives an overview of Ulva protein, including extraction and evaluation of protein quality in terms of nutritional value, functionality, and sensory properties with preliminary suggestions to reach the market. Available literature on protein extraction from Ulva was reviewed along with studies investigating the nutritional quality of Ulva protein and functional properties including aroma and flavor characteristics. Opportunities, challenges, and knowledge gaps are presented. A range of studies are investigating protein extraction, but only a few studies have dealt with protein digestibility, and food protein products. The digestibility of protein in crude Ulva biomass is low compared to conventional protein sources but increase with protein extraction. Sensory and functionality studies on Ulva protein are yet absent, but the whole biomass has been investigated, indicating the potential. The lack of consisting studies calls for more investigations related to food quality of Ulva protein. Upscaling and biorefinery models need to be explored to unfold the true potential of Ulva as a source of food protein. • The green macroalgae Ulva is gaining interest as an alternative protein source. • Protein extraction increases the protein digestibility of Ulva. • Ulva provides a promising amino acid profile, which should be exploited. • Research is needed on the functional and sensory properties of Ulva protein. • A biorefinery model is needed to make Ulva protein economical feasible. [ABSTRACT FROM AUTHOR]

Marine algae-based drug discovery has recently received a lot of attention. This study was conducted to extract laminarin-enriched solvent extracts from Padina tetrastromatica and Sargassum cinereum and to evaluate their anticancer activity against the HeLa cell line in vitro (MTT assay). Furthermore, their toxicity was determined through a zebra fish model study. P. tetrastromatica and S. cinereum biomasses have a higher concentration of essential biomolecules such as carbohydrates, protein, and crude fiber, as well as essential minerals (Na, Mg, K, Ca, and Fe) and secondary metabolites. Methanol extracts, in particular, contain a higher concentration of vital phytochemicals than other solvent extracts. The laminarin quantification assay states that methanol extracts of P. tetrastromatica and S. cinereum are rich in laminarin, which is primarily confirmed by FTIR analysis. In an anticancer study, laminarin-MeE from P. tetrastromatica and S. cinereum at concentrations of 750 and 1000 μg mL−1 demonstrated 100% activity against HeLa cells. The Zebra fish model-based toxicity study revealed that the laminarin-enriched MeE of P. tetrastromatica and S. cinereum is non-toxic. These findings revealed that the laminarin-enriched MeE of P. tetrastromatica and S. cinereum has significant anticancer activity without causing toxicity. • P. tetrastromatica and S. cinereum biomass contain more biomolecules. • Methanol extract of P. tetrastromatica & S. cinereum have more metabolites. • P. tetrastromatica & S. cinereum methanol extract enriched with laminarin. • FT-IR analysis revealed that these brown algae enriched with laminarin. • 750–1000 μg mL−1 dosage of laminarin-MeE of these algae showed anticancer activity. [ABSTRACT FROM AUTHOR]

• One-pot LA synthesis from macroalgae by ionic resin-catalyzed hydrothermal conversion. • 30.3 % LA yielded at 200 °C and 90 min with 12.5 % biomass and 50 % catalyst/biomass. • The use of Purolite CT269DR presents significant potential for the synthesis of LA. • The relationship between CS and LA synthesis was matched to the sigmoidal equation. Gracilaria verrucosa is red algae (Rhodophyta) that is particularly significant because of its potential for bioenergy production as a sustainable and environmentally friendly marine bioresource. This study focuses on the production of levulinic acid from G. verrucosa using hydrothermal conversion with an ionic resin Purolite CT269DR as the catalyst. By optimization of the conversion condition, a 30.3 % (22.58 g/L) yield of levulinic acid (LA) (based on carbohydrate content) was obtained at 200 °C for 90 min with 12.5 % biomass and 50 % catalyst loading of biomass quantity. Simultaneously, formic acid yielded 14.0 % (10.42 g/L). The LA yield increased with increasing combined severity (CS) levels under tested ranges. Furthermore, the relationship between CS and LA synthesis was effectively fitted to the nonlinear sigmoidal equation. However, as the yield of sugar decreased, LA yield was linearly increased. Thus, the use of ionic resin as a heterogeneous catalyst presents significant potential for the manufacture of platform chemicals, specifically LA, through the conversion of renewable marine macroalgae. [ABSTRACT FROM AUTHOR]

Naturally inspired biosorbent from macro algae species are favored because of its excellent biosorptive capability and low cost. The present investigation reports the potential of red macro-alga , E. spinosum as a biosorbent to remove both anionic and cationic azo dyes, namely Acid Yellow 17 (AY17) and Methylene Blue (MB) from aqueous solution. A resolution V fractional factorial design (2 v 5-1 ) analysis was employed to study the main effects and interaction of variables on the biosorption process. Factorial matrix with five variables; pH (2–12), dosage (0.4–2 g/L), initial concentration (50–200 mg/L), contact time (5–120 min) and temperature (30-50 °C) at two levels were conducted in batch study. Pareto charts and ANOVA (within 95% confidence level) were applied to examine the relationship and significance between independent variables and their interactions. A regression model with R2 AY17 = 0.9998 and R2 MB = 0.9995 was implemented to fit the experimental data. The results obtained indicated that the most significant variables that affected biosorption process were initial concentration and the dosage of the dyes. Experimental screenings are crucial in optimization studies. The remarkable performance of E. spinosum as biosorbent to absorb both dyes shows a great potential to be implemented for local marine macro alga as an alternative. Resource for biosorption process. • Operating variables of AY17 and MB biosorption were screened using Resolution V fractional factorial design (2v 5-1). • ANOVA and pareto chart confirm the most significant variables are initial concentration and dosage. • Biosorption of AY17 and MB using Euchema Spinosum is a promising way. [ABSTRACT FROM AUTHOR]

Foods that contain natural antioxidants can improve people's health and performance and make them more resistant to environmental stressors like diseases, lousy living conditions, and heat stress. Marine algae are well known for their function as an antioxidant. Colaconema formosanum is a new rhodophyte discovered in Taiwan and its bioactive activities are rarely studied. This work aims to prepare the protein hydrolysate fraction with antioxidant properties in C. formosanum using single enzyme or complex enzyme hydrolysis. Afterward, a 3 kDa molecular weight cut-off (MWCO) was used for centrifugation, and then fractionation was carried out using Strong Cation Exchange (SCX) Chromatography. The quantification of antioxidant activity was performed using the DPPH test. The results showed that the thermolysin hydrolysate (IC 50 1.48 ± 0.92 mg/mL) and the combination of trypsin-thermolysin hydrolysates (IC 50 1.37 ± 0.84 mg/mL) had the highest antioxidant activity. The fractionation procedure with strong cation exchange (SCX) yielded fraction C from thermolysin hydrolysates, which exhibited the most significant antioxidant activity with an IC 50 value of 0.47 ± 0.02 mg/mL. The fraction 4 derived from trypsin-thermolysin hydrolysates exhibited the most potent antioxidant activity (IC 50 : 0.34 ± 0.002 mg/mL). No previous reports have been made about the antioxidant properties of the hydrolysate fractions derived from C. formosanum proteins. Consequently, these findings could serve as a foundation for exploring peptides that have potential therapeutic sources for reducing oxidative stress. • The antioxidant activity of seaweed's protein fractions was evaluated • Colaconema formosanum , new species of Rhodophyta, can be an alternative antioxidant protein • The hydrolysates of alga were prepared by a two-step enzymatic method • Protein fraction of C. formosanum had an IC 50 of 0.34 ± 0.002 mg/mL on DPPH radical • MWCO and SCX-offline chromatography can enhance the potency of bioactive peptide [ABSTRACT FROM AUTHOR]

Ulva prolifera marine seaweed was tested for its capacity to eliminate reactive orange 16 (RO16) from aqueous solutions. Algae has recently been regarded as one of the most environmental friendly wastewater treatment methods and resources. The batch study used variations in solution pH, sorbent dosage, initial dye concentration, and temperature. The biochar was characterized using Fourier transform infrared (FT-IR) spectroscopy, an elemental analyser, proximate analysis, and a BET analyser. The adsorption mechanism was further investigated using adsorption isotherm and kinetic models. The thermodynamic analysis was performed by varying temperatures at different dye concentrations and calculating thermodynamic parameters such as Gibbs free energy, enthalpy, and entropy. The study was performed to evaluate the sorbent's performance in real-time wastewater treatment, a variety of chemicals, solid-liquid ratios, and regeneration cycles that were used to determine desorption efficiency. [ABSTRACT FROM AUTHOR]

Natural compounds isolated from macroalgae are promising, ecofriendly, and multifunctional bioinoculants, which have been tested and used in agriculture. Ulvans, for instance, one of the major polysaccharides present in Ulva spp. cell walls, have been tested for their plant growth-promoting properties as well as their ability to activate plant immune defense, on a large variety of crops. Recently, we have characterized for the first time an arabinogalactan protein-like (AGP-like) from Ulva lactuca , which exhibits several features associated to land plant AGPs. In land plant, AGPs were shown to play a role in several plant biological functions, including cell morphogenesis, reproduction, and plant-microbe interactions. Thus, isolated AGP-like proteins may be good candidates for either the plant growth-promoting properties or the activation of plant immune defense. Here, we have isolated an AGP-like enriched fraction from Ulva lactuca and we have evaluated its ability to (i) protect oilseed rape (Brassica napus) cotyledons against Leptosphaeria maculans , and (ii) its ability to activate immune responses. Preventive application of the Ulva AGP-like enriched fraction on oilseed rape, followed by cotyledon inoculation with the fungal hemibiotroph L. maculans , resulted in a major reduction of infection propagation. The noticed reduction correlated with an accumulation of H2O2 in treated cotyledons and with the activation of SA and ET signaling pathways in oilseed rape cotyledons. In parallel, an ulvan was also isolated from Ulva lactuca. Preventive application of ulvan also enhanced plant resistance against L. maculans. Surprisingly, reduction of infection severity was only observed at high concentration of ulvan. Here, no such significant changes in gene expression and H2O2 production were observed. Together, this study indicates that U. lactuca AGP-like glycoproteins exhibit promising elicitor activity and that plant eliciting properties of Ulva extract, might result not only from an ulvan-originated eliciting activities, but also AGP-like originated. [ABSTRACT FROM AUTHOR]

Marine algae have served as a treasure trove of structurally variable and biologically active metabolites. The present study emphasizes on UPLC–MS metabolites fingerprinting for the first systematic broad scale metabolites characterization of three different phyla of marine seaweeds; Ulva fasciata, Pterocladia capillacea and Sargassum hornschuchii along with Spirulina platensis harvested from the Mediterranean Sea. A total of 85 metabolites belonging to various classes including mostly fatty acids and their derivatives, terpenoids, amino acids and dipeptides with considerable amounts of polyphenolic compounds. OPLS-DA model offered a better overview of phylum-based discrimination rapidly uncovering the compositional heterogeneity in metabolite profiles of algae extracts. An OPLS model was constructed using the cytotoxic activities against PC3 and MDA-MB-231 tumor cells to succinctly screen cytotoxic discriminatory metabolites among the tested algae species. The coefficient plot revealed that unsaturated fatty acids as stearidonic acid and linolenic acid, terpenoids namely as rosmanol, campestanol, dipeptides primarily glutamylglycine, glycyltyrosine along with polyphenolic compounds being abundantly present in S. platensis and U. fasciata samples with relatively marked cytotoxic potential might be the significant contributors synergistically meditating their anti-proliferative activity against PC3 and MDA-MB-231 tumor cells. Such results serve as baseline for understanding the chemistry of these species and performing strict correlation between metabolite and activity where a lack of information in this regard is observed. [ABSTRACT FROM AUTHOR]

Extracts of Ascophyllum nodosum are commonly used as commercial biostimulants in crop production. To further understand the seaweed extract-induced phenomena in plants, a transcriptomic study was conducted. RNA-seq differential gene expression analysis of tomato plants treated with a commercial A. nodosum extract formulation (Stimplex) revealed the up-regulation of 635 and down-regulation of 456 genes. Ontology enrichment analysis showed three gene categories were augmented, including biological processes, cellular components, and molecular functions. KEGG pathway analysis revealed that the extract had a strong influence on the expression of genes involved in carbon fixation, secondary metabolism, MAPK-signalling, plant hormone signal transduction, glutathione metabolism, phenylpropanoid and stilbenoid metabolism, and plant-pathogen interactions. qRT-PCR validation analysis using 15 genes established a strong correlation with the RNA sequencing results. The activities of defence enzymes were also significantly enhanced by seaweed extract treatment. Furthermore, AN-SWE treated tomato plants had significantly higher chlorophyll and growth hormone content and showed improved plant growth parameters and nutrient profiles than the control. It is postulated that seaweed extract-induced gene regulation was responsible for favourable plant responses that enabled better growth and tolerance to stress conditions. This study provides evidence at the transcriptomic level for the positive effects of foliar application of the Ascophyllum nodosum extract (Stimplex) observed in treated tomato plants. [ABSTRACT FROM AUTHOR]

UAV remote sensing inversion is an efficient and accurate method for obtaining information on vegetation coverage, biomass and other parameters. It is widely used on forest, grassland and other terrestrial vegetation. However, it is rarely used on aquatic vegetation, especially in intertidal zones and other complex environments. Additionally, it is mainly used for inversion of coverage, and there have been few studies thus far on biomass assessment. In this paper, we applied multispectral UAV aerial photography data to evaluate the biomass of seaweed in an intertidal zone. During the ebb tide, UAV aerial photography and in situ sampling data were collected in the study area. After optimizing the spectral index and performing a multiple linearity test, the spectral parameters were selected as the input of the evaluation model. Combined with two machine learning algorithms, namely random forest (RF) and gradient boosting decision tree (GBDT), the biomasses of three species of seaweed (Ulva pertusa, Sargassum thunbergii and Sargassum fusiforme) in the intertidal zone were assessed. In addition, the input parameters of the machine learning algorithms were optimized by one-way ANOVA and Pearson's correlation analysis. We propose a method to assess the biomass of intertidal seaweed based on multispectral UAV data combined with statistics and machine learning. The results show that the two machine learning algorithms have different accuracies in terms of biomass evaluation using multispectral images; the gradient boosting decision tree can evaluate the biomass of seaweed in the intertidal zone more accurately. [ABSTRACT FROM AUTHOR]

In this study, biosorption processes performed with and without ultrasound-assisted were presented for the first time comparatively. For this purpose, the potential for use of Ulva lactuca Linnaeus 1753 (U. lactuca) which is a macroalgae, as an alternative biosorbent was investigated for Hg(II) removal from aqueous solutions. Both conventional univariate and multivariate methods were evaluated to optimise biosorption processes. Biosorption equilibrium time was determined as 60 min for without ultrasound-assisted method, while it was only 3 min for ultrasound-assisted method. Biosorption processes were optimised by Central Composite Design (CCD) and successfully described by quadratic polynomial models as a function both of R (%) and qe (mg/g). In optimum conditions (Co = 125 mg/L, m = 30 mg, pH = 4.0 for ultrasound-assisted method and pH = 2.0 for without ultrasound-assisted method), removal efficiencies were achieved experimentally as 95.8% ± 0.2 and 96.1% ± 0.7 (N = 2), respectively. Models with high regression coefficients (R2(adj) > 95%) obtained from Response Surface Methodology (RSM) were found to be applicable to the estimation of biosorption data. Biosorption equilibrium data was defined by Langmuir model. Langmuir's maximum sorption capacity was increased from 125.6 to 232.0 mg/g when ultrasound-assisted method was applied. According to the results of kinetics evaluation, both biosorption processes were thermodynamically possible, endothermic (ΔHº>0) and spontaneous reactions (ΔGº<0) controlled by chemisorption based on the pseudo-second-order kinetic models. Results showed that ultrasound-assistance to the biosorption process contributed positively to increasing the rate of reaction and allowing sorption to be completed in a shorter time by facilitating sorption mass transfer. [ABSTRACT FROM AUTHOR]

Molecular studies have revealed cryptic diversity and polyphyly in the genus Lithothamnion. In this study we aimed to investigate the diversity and phylogeny of specimens that are morphologically described as Lithothamnion based on extensive collections along the Brazilian coast and an integrative taxonomic approach. Our results led to the proposal of Roseolithon gen. nov. belonging to the subfamily Melobesioideae. This new genus is described from the tropical north-western Atlantic and warm temperate south-western Atlantic specimens, based on phylogenetic analyses of psbA, rbcL-3P, COI-5P and SSU rDNA molecular markers, species delimitation methods, genetic divergence and morpho-anatomical observations. The integrative approach led us to find a set of morphological features that characterize Roseolithon: (i) thallus organization monomerous with plumose hypothallus (non-coaxial); (ii) flared epithallial cells; (iii) subepithallial cells varying in size and may be shorter, approximately equal to or longer than those subtending them; (iv) cells of adjacent filaments linked by fusions; (v) tetra/bisporangial conceptacle chambers multiporate; and (vi) the presence of pore canals bordered by rosette cells in depressions giving the surface a pitted appearance. Depending on the species, this pitted appearance occurs due to the sunken or disintegrated rosette cell roofs. The grade of the degeneration of the rosette cell roofs characterizes the species of this genus. The new genus Roseolithon is composed of at least 18 species, of which we describe seven new species: Roseolithon tupii, R. tamoioi, R. tremembei, R. potiguarae, R. karaiborum, R. purii and R. goytacae. Highlights Phylogenetic analyses revealed Lithothamnion to be a polyFphyletic genus. Integrative taxonomy enabled the description of a new genus Roseolithon. Morpho-anatomy does not reflect molecular phylogeny of non-geniculate coralline algae. [ABSTRACT FROM AUTHOR]

The freshwater red algal genus Sheathia is one of the most species‐rich genera in the Batrachospermales, containing species with heterocortication (both bulbous and cylindrical cells covering the main axis) and homocortication (only cylindrical cells). The hidden diversity of homocorticated Sheathia species has gained research momentum. Recent studies have revised these taxa and described many new species. In this study, a new homocorticated Sheathia species is described and illustrated from Yunnan, China, based on phylogenetic analyses of DNA sequence data. Sheathia yunnanensis sp. nov is morphologically characterized by having homocortication, carpogonium with bent or slightly constricted lanceolate trichogyne, large carposporophyte and carposporangium. However, it is only distinguishable from other homocorticated species by DNA sequence data. Phylogenetic analyses based on rbcL, COI‐5P, psbA and concatenated rbcL + COI‐5P alignment indicated that Sheathia yunnanensis form an independent clade from other homocorticated Sheathia species with high interspecific divergence (rbcL: 3.9–4.9%/37–54 bp, COI‐5P: 6.1–6.6%/36–39 bp and psbA: 2.2–3.9%/18–32 bp). Sheathia yunnanensis, as the first gametophyte of Sheathia species reported in Yunnan, differs from other Sheathia species reported only as 'Chantransia' sporophyte stage. As a result of this study, the number of Sheathia species recognized in China increased to eight, including one heterocorticate and seven homocorticated including three only known from the 'Chantransia' sporophyte stage. The description of this new species expands the diversity of Sheathia in the world. [ABSTRACT FROM AUTHOR]

Gelidium rosulatum, a new species from the subtidal zone in eastern Korea, is described on the basis of morphological observations and molecular analyses. Phylogenies of plastid rbcL and mitochondrial cox1 markers revealed the distinctness of the new species, which was closely related to other East Asian species and G. chilense. Gelidium rosulatum is distinguished by a small thallus (up to 0.8 cm) that forms rosette turfs, leaf-like branchlets arising spirally along the erect axis, abundant rhizines in the medulla, cylindrical tetrasporangial sori without sterile margins, and rhomboid bilocular cystocarps borne on the apical parts of branchlets. The diversity of Korean Gelidium is now updated to 19 species, but further surveys of little explored areas and studies of dubious reports may reveal additional undescribed species. [ABSTRACT FROM AUTHOR]

Species discovery is facilitated by the application of molecular tools and the exploration of poorly studied habitats. Recent surveys in Bafa Lake, Turkey, which experienced a transition from oligo- to mesohaline conditions during the last 40 years, led to the finding of two species of the genera Lophosiphonia and Polysiphonia. Our molecular and morphological study showed that one of the species corresponded to L. obscura, while the other differs from previously described Polysiphonia species and is proposed as P. sukatarii sp. nov. The new species differs from related congeners by a rbcL sequence divergence ≥5.8% and is morphologically distinguished by having four pericentral cells and trichoblasts arranged several segments apart. Lophosiphonia obscura, and its closely related species L. hemisphaerica comb. nov. and L. boldii comb. nov., have been previously found in similar habitats in Europe and Atlantic North America. Along with its record from Bafa Lake, P. sukatarii sp. nov. has been discovered in open shore algal turfs from the Canary Islands, suggesting that it is a euryhaline species with probably a wide distribution. Our work highlights that poorly studied habitats still harbour undiscovered species and additional surveys are necessary to acquire a more comprehensive understanding of the macroalgal diversity. [ABSTRACT FROM AUTHOR]

Seaweeds contain a wide range of secondary metabolites which serve multiple functions, including chemical and ecological mediation with microorganisms. Moreover, owing to their diverse bioactivity, including their antibiotic properties, they show potential for human use. Nonetheless, the chemical ecology of seaweeds is not equally understood across different regions; for example, Antarctic seaweeds are among the lesser studied groups. With the aim of improving our current understanding of the chemical ecology and potential bioactivity of Antarctic seaweeds, we performed a screening of antibiotic activity using crude extracts from 22 Antarctic macroalgae species. Extractions were performed separating lipophilic and hydrophilic fractions at natural concentrations. Antimicrobial activity assays were performed using the disk diffusion method against seven Antarctic bacteria and seven human pathogenic surrogates. Our results showed that red seaweeds (especially Delisea pulchra) inhibited a larger number of microorganisms compared with brown seaweeds, and that lipophilic fractions were more active than hydrophilic ones. Both types of bacteria tested (Gram negative and Gram positive) were inhibited, especially by butanolic fractions, suggesting a trend of non-specific chemical defence. However, Gram-negative bacteria and one pathogenic fungus showed greater resistance. Our study contributes to the evidence of antimicrobial chemical interactions between Antarctic seaweeds and sympatric microorganisms, as well as the potential of seaweed extracts for pharmacological applications. [ABSTRACT FROM AUTHOR]

In order to understand how the environmental history (low‐light and low‐temperature history) influences the photosynthetic physiology and metabolism of Ulva spp., we cultured Ulva prolifera seedlings under low‐light (LL: 30–50 µmol m−2 s−1) and low‐temperature (LT: 10°C) conditions for 3 and 8 days firstly; then, both the LL‐ and LT‐ grown seedlings were transferred to optimal conditions (25°C; 120–130 µmol m−2 s−1) for 3 days. During the stress and recovery period, the seedlings grown under 25°C and 120–130 µmol m−2s−1 were set as the control treatment (noted as 25–25°C). The results showed that compared with the control treatment, U. prolifera exhibited pronounced over‐compensatory growth induced by low temperature, rather than the low light, but there were no significant differences between 3 and 8 days for low‐temperature pretreatments. Based on the results, we cultured this species under 10, 12, 15 and 10–12–15°C firstly and then transferred them to 25°C, in order to study the effects of the low temperature history. It was found that compared with 25–25°C, the growth of thalli was significantly increased by low temperature history, except for that pre‐acclimated to 15°C. The reasons for this increase varied, but not included the chlorophyll a (Chl a), water content, soluble sugar and soluble protein (SPs), because the Chl a content was significantly decreased by low temperature history, especially pre‐acclimated to 10°C and 10–12–15°C. There were no significant effects of low temperature history on the water content and soluble sugar, while compared with 25–25°C, lower temperature history decreased SPs content, except for pre‐acclimated to 10°C. Our results suggest that environmental history, especially low temperature history, plays an important role in the rapid growth of Ulva species. [ABSTRACT FROM AUTHOR]

This study analyzed the antimicrobial effect of aqueous extracts of flour obtained from red alga (Gelidium sp.) both in vitro, against most common food pathogenic and spoilage bacteria, and in a food model system during the chilled storage of Atlantic mackerel (Scomber scombrus). Results of in vitro assays allowed the conclusion that the aqueous flour extracts have antimicrobial activity against Gram-negative bacteria such as Enterobacteriaceae (Escherichia coli, Enterobacter aerogenes, and Klebsiella pneumoniae) and proteobacteria (Vibrio alginolyticus), and against Gram-positive bacteria such as Bacillus cereus and B. subtilis. In the food model study, different concentrations of the flour extract were present in the icing medium, microbial and chemical analyses being carried out in fish muscle at different storage times. An inhibitory effect (p < 0.05) on microbial growth (aerobes, psychrotrophs, Enterobacteriaceae, and proteolytic and lipolytic bacteria) and on chemical quality indices (pH, total volatile amines, and trimethylamine) was concluded. This effect was more pronounced when the flour extract concentration in the ice increased and at advanced storage times. This study provides a first approach to the beneficial use of flour of the alga Gelidium as a new preserving strategy for chilled fish. [ABSTRACT FROM AUTHOR]

The taxonomy of the genera Grateloupia, Phyllymenia, and Prionitis has been revised several times but remains controversial. The anatomy of female reproductive structures in combination with phylogenetic reconstructions is mostly used to define the genera. However, the architecture and behavior of the auxiliary cell ampullae before and after diploidization are not well documented for most species. To fill this knowledge gap, we examined the female reproductive structures of a new species (Prionitis taiwani‐borealis sp. nov.) from Taiwan and compared our observations to the species currently placed in the Phyllymenia/Prionitis complex. The female reproductive structures of the Phyllymenia/Prionitis complex are characterized by (1) 2‐celled carpogonial branches with the supporting cell being the basal cell of a third‐order ampullar filament; (2) auxiliary cell ampullae composed of three orders of unbranched ampullar filaments before diploidization; (3) cells of auxiliary cell ampullar filaments forming a cellular cluster after diploidization and surrounding the developing gonimoblasts; (4) gonimoblast initials produced from the diploidized auxiliary cells before fusing with them; and (5) branched auxiliary cell ampullar and secondary medullary filaments involved in early pericarp formation. A monophyletic relationship of species possessing female structures similar to those of Pr. taiwani‐borealis and related species was highly supported based on combined rbcL and LSU rDNA sequence analyses. The female reproductive structures of other species of Grateloupia sensu lato, phylogenetically closely related to the Prionitis and Phyllymenia assemblage, require reinvestigation as correct interpretations of pre‐ and post‐fertilization events have proven to be informative for resolving the systematics of the Halymeniaceae. [ABSTRACT FROM AUTHOR]

The present study adds 19 species (15 Rhodophyta, one Chlorophyta and three Ochrophyta) to the Azorean marine macroalgal flora, increasing the current total of species recorded in this region to 521 (349 Rhodophyta, 76 Chlorophyta and 96 Ochrophyta), and showing that this isolated island group supports a relatively rich marine macroalgal flora. Some species fall within their known overall distributional range, whereas other found here represent a northern or southern extension to their known distribution in the Atlantic. Three species (Antithamnionella elegans, Gymnophycus hapsiphorus and Scytosiphon dotyi) are probable introductions to the Azores, whereas Melanothamnus pseudoforcipatus has an uncertain status. Six of the newly reported species were found as components of the intertidal algal turf samples, which justifies the need for continuing to examine turf samples as new discoveries can be anticipated. [ABSTRACT FROM AUTHOR]

SUMMARY: Zonation patterns and the structure of intertidal communities are controlled by tidal conditions. Algal diversity, abundance and succession were experimentally tested under different degrees of wave exposure, shore level, and season of clearing at the intertidal zone, Phuket, Thailand. Dead coral patches colonized by algae (20 cm × 20 cm) were cleared at upper, middle, and lower shore levels on sheltered and semi‐exposed shores during both the dry and rainy seasons. Of 17 algal species, including eight Rhodophyta, eight Chlorophyta, and one Phaeophyceae that were recruited on the cleared plots, three species were dominant: Ulva paradoxa, Padina in the Vaughaniella stage, and Polysiphonia sphaerocarpa. Algal diversity on the semi‐exposed shore was higher than on the sheltered shore. In the successional process, U. paradoxa extensively recruited and persisted longer on plots cleared at the middle shore level on the semi‐exposed shores than at the other. It showed a greater abundance in the plots cleared in the rainy season than those cleared in the dry season. Ulva paradoxa persisted for around 5 to 6 months after clearing and was then replaced by the two later species, Padina in the Vaughaniella stage and P. sphaerocarpa. Ulva paradoxa settled more easily and persisted longer at the cleared plots than other algal species because of its opportunistic characteristics and a special physiological adaptation to long periods of emersion. From this study, degree of wave exposure, shore level, and season of clearing likely play important roles in algal recruitment, abundance, and succession patterns. [ABSTRACT FROM AUTHOR]

Summary: A new red alga from Japan, Dasya japonovillosa, is described. This new species and D. enomotoi, both of which have elongated axes densely covered with numerous soft monosiphonous filaments, may have been misidentified as D. villosa by previous investigators in Japan. Dasya villosa differs from D. japonovillosa and D. enomotoi in the distinct five pericentral cells in transverse sections and palisade‐like tetrasporangial cover cells. The new species is distinguished from several similar species by the combination of the following: an elongated axis (to 65 cm), subdichotomously divided axes and polysiphonous branches, indistinct pericentral cells in transverse sections except near the apices, and the presence of enlarged, inner cortical cells, radially arranged numerous soft monosiphonous filaments, three‐celled carpogonial branches, four tetrasporangia in each fertile segment of the stichidia, and one (rarely two) tetrasporangial cover cell that is not elongated longitudinally and rarely divided transversely. [ABSTRACT FROM AUTHOR]

Photosynthetic organisms have evolved light-harvesting antennae over time. In cyanobacteria, external phycobilisomes (PBSs) are the dominant antennae, whereas in green algae and higher plants, PBSs have been replaced by proteins of the Lhc family that are integrated in the membrane. Red algae represent an evolutionary intermediate between these two systems, as they employ both PBSs and membrane LHCR proteins as light-harvesting units. Understanding how red algae cope with light is not only interesting for biotechnological applications, but is also of evolutionary interest. For example, energy-dependent quenching (qE) is an essential photoprotective mechanism widely used by species from cyanobacteria to higher plants to avoid light damage; however, the quenching mechanism in red algae remains largely unexplored. Here, we used both pulse amplitude-modulated (PAM) and time-resolved chlorophyll fluorescence to characterize qE kinetics in the red alga Porphyridium purpureum. PAM traces confirmed that qE in P. purpureum is activated by a decrease in the thylakoid lumen pH, whereas time-resolved fluorescence results further revealed the quenching site and ultrafast quenching kinetics. We found that quenching exclusively takes place in the photosystem II (PSII) complexes and preferentially occurs at PSII's core antenna rather than at its reaction center, with an overall quenching rate of 17.6 ± 3.0 ns-1. In conclusion, we propose that qE in red algae is not a reaction center type of quenching, and that there might be a membrane-bound protein that resembles PsbS of higher plants or LHCSR of green algae that senses low luminal pH and triggers qE in red algae. [ABSTRACT FROM AUTHOR]

Extreme climatic events can reshape the functional structure of ecological communities, potentially altering ecological interactions and ecosystem functioning. While these shifts have been widely documented, evidence of their persistence and potential flow‐on effects on ecosystem structure following relaxation of extreme events remains limited. Here, we investigate changes in the functional trait structure – encompassing dimensions of resource use, thermal affinity, and body size – of herbivorous fishes in a temperate reef system that experienced an extreme marine heatwave (MHW) and subsequent return to cool conditions. We quantify how changes in the trait structure modified the nature and intensity of herbivory‐related functions (macroalgae, turf, and sediment removal), and explored the potential flow‐on effects on the recovery dynamics of macroalgal foundation species. The trait structure of the herbivorous fish assemblage shifted as a result of the MHW, from dominance of cool‐water browsing species to increased evenness in the distribution of abundance among temperate and tropical guilds supporting novel herbivory roles (i.e. scraping, cropping, and sediment sucking). Despite the abundance of tropical herbivorous fishes and intensity of herbivory‐related functions declined following a period of cooling after the MHW, the underlying trait structure displayed limited recovery. Concomitantly, algal assemblages displayed a lack of recovery of the formerly dominant foundational species, the kelp Ecklonia radiata, transitioning to an alternative state dominated by turf and Sargassum spp. Our study demonstrates a legacy effect of an extreme MHW and exemplified the value of monitoring phenotypic (trait mediated) changes in the nature of core ecosystem processes to predict and adapt to the future configurations of changing reef ecosystems. [ABSTRACT FROM AUTHOR]

Intraspecific variation in morphology is widespread among seaweed species in different habitats. We examined the morphological variation in Sargassum thunbergii involving diverse environmental factors. We quantified 16 morphological characteristics on 15 rocky intertidal shores in Korea. A cluster analysis based on morphology identified three groups. Group M1 comprised populations on the northern part of the east coast, where the thalli was short and thick, with large leaf and air-vesicle. Group M3 consisted of populations on the west coast exclusively separated from other populations, with short, slender and sparsely branched thalli. Group M2 comprised populations on the southern part of the east coast and on the south coast (including Jeju Island), with longest thalli and lateral branches. Principal coordinate analyses showed that group M1 and M3 were mostly influenced by strong wave action and large tidal amplitudes, respectively. Group M2 were under the influence of warm temperatures and high irradiance. Biota-environment matching analysis showed that the morphology is affected by combinations of different local environmental factors and also that tidal condition is important as a single variable, suggesting that morphology of S. thunbergii reflects and adapts to local environmental conditions. [ABSTRACT FROM AUTHOR]

Marine red macroalgae has attracted researchers' consideration as a non-lignocellulosic feedstock for microbial growth to produce biofuels and biochemical products. Gelidium amansii is representative galactose-rich red macroalgae biomass but studies on its galactose utilization are currently scarce. Herein, we engineered Pseudomonas putida KT2440 as a functional chassis for assimilation of galactose in addition to glucose in G. amansii hydrolysate. P. putida KT2440 was confirmed owning high ability to oxidize galactose to galactonate by glucose dehydrogenase. Thereafter galactose-oxidation pathway was extended by introducing galactonate transport and metabolism modules from Pseudomonas rhodesiae NL2019. The recombinant strains NL910 and NL911 were able to grow on galactose with high cell densities and growth rates, and simultaneously upgrade all red macroalgae streams, which is essential to develop a sustainable and cost-effective bioprocess for valorization of red macroalgae. • Gelidium amansii was pretreated to galactose-rich hydrolysate with yield of 86%. • Pseudomonas putida KT2440 was engineered for galactose assimilation. • A simplified modification strategy for galactose utilization was proposed. • Engineered strains can simultaneously upgrade all red macroalgae streams. • This process realized the valorization of macroalgae biomass. [ABSTRACT FROM AUTHOR]

Finally, uptake of Si by macroalgae may help promote Si limitation in estuaries, especially if they are actively sequestering it, and therefore competing with diatoms for Si. Keywords: biogenic silica; C: Si molar ratios; estuary; macroalgae; Si cycle; Si limitation; silicon EN biogenic silica C: Si molar ratios estuary macroalgae Si cycle Si limitation silicon 2330 2336 7 02/21/22 20220315 NES 220315 Introduction Across the marine landscape, from estuaries to the open ocean, biota take up silicon (Si) as monosilicic acid and deposit it into their tissues as biogenic silica (BSi). Biogenic silica, C: Si molar ratios, estuary, macroalgae, Si cycle, silicon, Si limitation. [Extracted from the article]

The purpose of this study was to test the nematicidal activity of extracts of two marine algae (Colpomenia sinuosa and Corallina mediterranea) and their synthesized silver nanoparticles against root-knot nematodes (Meloidogyne incognita) that infest tomato plants. Scanning electron microscopy (SEM) revealed that nanoparticles had aggregated into anisotropic Ag particles, and transmission electron microscopy (TEM) revealed that the particle sizes were less than 40 nm. Fourier Transform Infrared Spectroscopy (FT-IR) analysis revealed that the obtained nanoparticles had a sharp absorbance between 440 and 4000 cm−1, with 13 distinct peaks ranging from 474 to 3915 cm−1. Methylene chloride extracts and nanoparticles synthesized from both algae species were used to treat M. incognita. C. sinuosa nanoparticles had the highest nematicidal activity of any treatment. Furthermore, and in contrast to other treatments, C. sinuosa nanoparticles reduced the number of nematode galls, egg-masses per root, and eggs/egg mass, while also improving plant growth parameters. C. sinuosa's methylene chloride extract was more active than C. mediterranea's, and the most effective eluent of this solvent was hexane: methylene chloride: ethyl acetate (1: 0.5: 0.5, v/v/v). When applied to M. incognita, the third fraction of this eluent was the most effective, resulting in 87.5% mortality after 12 h and 100% mortality after 24 and 72 h of exposure. The presence of seven bioactive constituents was discovered during the analysis of this fraction. In conclusion, the silver nanoparticles synthesized from C. sinuosa could be used as alternative chemical nematicides. [ABSTRACT FROM AUTHOR]

Intercellular nutrient and signal transduction are essential to sustaining multicellular organisms and maximizing the benefits of multicellularity. It has long been believed that red algal intercellular transport of macromolecules is prevented by the protein-rich pit plug within pit-connections, the only physical connection between cells. Fluorescein isothiocyanate-dextran and recombinant green fluorescence protein (rGFP) of various molecular sizes were injected into vegetative cells of Griffithsia monilis using a micromanipulator, and intercellular transport of the fluorescent probes was examined. Pit-connections were found to provide intercellular transport of tracers at rates comparable to plasmodesmata in other organisms. The time necessary for the transport to an adjacent cell was dependent on the molecular size and the direction of the transport. Fluorescent dextran of 3 kDa was transported to adjacent cells in 1-2 h after injection and migrated to all cells of the filament within 24 h, but fluorescent dextran of 10-20 kDa took 24 h to transfer to neighboring cells. The migration occurred faster towards adjacent reproductive cells and to apical cells than basally. Fluorescent tracers above 40 kDa and rGFP was not transported to neighboring cells, but accumulated near the pit plug. Our results suggest that pit-connections are conduit for macromolecules between neighboring cells and that these size-specific conduits allow intercellular communication between the vegetative cells of red algae. [ABSTRACT FROM AUTHOR]

Biosynthesis of gold nanoparticles (AuNPs) is emerging as a better alternative to traditional chemical based techniques. During this study, extracts of different marine algae species Ulva rigida (green algae), Cystoseira myrica (brown Algae), and Gracilaria foliifera (red Algae) were utilized as reducing and capping agents to synthesize AuNPs. AuNPs capped by U. rigida, C. myrica, and G. foliifera were confirmed by the appearance of surface plasmonic bands at 528, 540, and 543 nm, respectively. Transmission electron microscopy revealed mostly spherical shapes of AuNPs having a size of about 9 nm, 11 nm, and 13 nm for C. myrica, and G. foliifera extracts, respectively. Fourier transform-infrared spectroscopy (FTIR) illustrated the major chemical constituents of U. rigida, C. myrica, and G. foliifera. LC50 values of the biosynthesized AuNPs against Artemia salina nauplii were calculated at a range of concentrations (5-188 μg ml−1) after 16 to 24h. AuNPs concentration-dependent lethality was noted and U. rigida extracts-mediated AuNPs presented the lowest cytotoxicity. The biosynthesized AuNPs exhibited significant anticancer activity (86.83%) against MCF-7 cell lines (human breast adenocarcinoma cell lines) at 188 μg/ml concentration. G. foliifera demonstrated the highest anticancer value (92.13%) followed by C. myrica (89.82%), and U. rigida (86.83%), respectively. The AuNPs synthesized by different algal extracts showed variable antimicrobial activity against the tested pathogenic microorganisms. AuNPs of U. rigida extracts showed significant antimicrobial activity against dermatophytic fungi Trichosporon cataneum (30 mm) followed by Trichophyton mantigrophytes (25 mm). Furthermore, it also exhibited mild activity against Escherichia coli (17 mm), Cryptococcus neoformans (15 mm), Candida albicans (13 mm), and Staphylococcus aureus (11mm), respectively whereas no effects were observed against Bacillus cereus. To conclude, AuNPs can be effectively synthesized by marine algal species, and particularly U. rigida extracts could be effective reducing agents for the green AuNPs synthesis. These AuNPs could potentially serve as efficient alternative anticancer agents against human breast adenocarcinoma and anti-dermatophytes associated with skin infections. [ABSTRACT FROM AUTHOR]

Bioactive compounds from marine macroalgae are gaining immense attention for their application as natural ingredients in various nutraceuticals and food supplements. The present study evaluated the medicinal properties of the organic extracts of four each of brown and red marine macroalgal species, using various in vitro assays. Organic extracts of brown algae of Fucophycidan subclass, such as Sargassum plagiophyllum, Turbinaria decurrens, and red alga Hydropuntia edulis, displayed potential inhibitory properties against antioxidants (IC50 0.2–0.8 mg/mL) and carbolytic enzymes (IC50 0.2–0.9 mg/mL) compared to those exhibited by other studied algae. Noticeably, organic extracts of red alga H. edulis and brown alga T. decurrens could effectively attenuate pro-inflammatory 5-lipoxygenase (IC50 0.4–0.6 mg/mL), thereby demonstrating their potential application to dissuade inflammatory pathogenesis. This study demonstrated the predominantly available brown and red macroalgae as potential marine bioresources to develop functional food candidates. [ABSTRACT FROM AUTHOR]

Turf-forming Gelidiales frequently occur in tropical coral reef regions. It is challenging to identify species correctly due to their small size and simple morphology. In the present study, we combined morphological and molecular phylogenetics methods to study turf-forming species of the genus Pterocladiella from tropical coral reef areas in southern China. Both COI-5P and rbcL gene analyses revealed a novel species described here, Pterocladiella xiae sp. nov. The species was less than 1 cm in height, with a distinctive slender thallus, compressed percurrent axis with up to two orders of ribbon-like branches, and short warty-like branchlets which usually occurred irregularly on the upper thallus. Pterocladiella bartlettii was also recorded in China for the first time. Additional descriptions of reproductive structure in P. musciformis and P. beachiae were also documented. This study enriches our understanding of the biodiversity of Pterocladiella in China and reveals the potential diversity of small turf-forming species in tropical coral reefs. [ABSTRACT FROM AUTHOR]