Brown Algal Species Research Articles

Thermal priming of Saccharina latissima: a promising strategy to improve seaweed production and restoration in future climates

Saccharina latissima is a brown algal kelp species of ecological and economic importance. As the rise in sea surface temperature will threaten not only wild populations of S. latissima but also the productivity of kelp farms, crop enhancement techniques will become crucial to mitigate this threat. Priming is a common strategy in crop plants, in which seeds are pre-exposed to moderate stress to improve the performance and tolerance of plants when exposed to harsher conditions. We investigated the potential of thermal priming to improve growth and tolerance of S. latissima. Kelp gametophytes primed at 20°C for 2, 4 and 6 wk and then re-transferred to 5°C were compared to a naïve treatment maintained at 5°C. Gametophyte priming increased growth of subsequently formed sporophytes by up to 30% (for 4 wk priming) compared to the naïve treatment. Female gametophyte growth in the priming environment was positively correlated to offspring sporophyte growth, indicating a maternal effect. Sporophytes were exposed to heat stress of 20°, 22°, 23° and 24°C for 2 wk. Sporophytes from 4 and 6 wk primed gametophytes exhibited 11 d longer tolerance at 22°C, 7 d longer tolerance at 23°C and 1°C higher thermal tolerance over 7 d compared to naïve sporophytes and sporophytes from 2 wk priming. A priming time of 4 wk was optimal for both sporophyte growth and thermal tolerance. Our results suggest that priming is a promising crop enhancement technique that could improve yield for seaweed farmers and restoration of kelp forests threatened by warming climates.

Grow with the flow: Is phenotypic plasticity across hydrodynamic gradients common in seaweeds?

Seaweeds are widely assumed to be phenotypically plastic across hydrodynamic gradients, yet while many marine macroalgae exhibit intraspecific phenotypic variation that correlates with flow, researchers often fail to test whether such variation is due to plasticity or another mechanism, such as local adaptation. In this minireview, we considered mechanisms for sensing flow in seaweeds that could facilitate adaptive phenotypic plasticity across hydrodynamic gradients. We then reviewed the literature from 1900 to 2024 to see how often phenotypic variation and plasticity across hydrodynamic gradients had been observed and demonstrated in different groups of seaweeds. In the last 124 years, phenotypic variation and plasticity in response to flow have been well documented in brown algae but scarcely documented in red and green algae. This could suggest that brown algae are better able to sense and respond to flow than red and green algae, perhaps due to the intercalary meristem of many brown algae, including most kelps. However, this skewed distribution could also be the result of publication bias, as most studies involving flow have been conducted on brown algae. Only 30% of 141 papers specifically investigated if observations of phenotypic variation along hydrodynamic gradients were due to plasticity. To date, phenotypic plasticity in response to flow has been demonstrated in 20 brown algal species, five red algal species, and two green algal species. Thus, the assumption that phenotypic plasticity to flow is common across seaweeds is not particularly well supported by the literature. Mechanisms underlying plasticity to flow are poorly understood and remain a critical avenue for future research.

Evaluation of cryptic invasion in Japanese Undaria populations based on mitochondrial haplotypic analysis

Abstract To improve the quality and quantity of seaweed mariculture harvests, seedlings are frequently introduced from regions geographically apart from cultivation sites. The effects of such introduction have been insufficiently studied, despite increasing demands on seaweed cultivation as a measure against global warming. We here evaluated the degree of cryptic invasion occurring through mariculture using a brown algal species, Undaria pinnatifida. Cultivated materials used in the Seto Inland Sea, Japan, were introduced from northern Japan in the 1970s. Based on the clear genetic structure among Japanese Undaria populations, we compared mitochondrial haplotypes between wild populations and cultivated materials in the Seto Inland Sea. All cultivated materials analyzed had haplogroups native to northern Japan. Multiple haplogroups were observed in the wild populations, especially those in the eastern Seto Inland Sea, which is exceptional considering the reported genetic structure. Some northern Japan haplotypes were observed both in cultivated materials and wild individuals. A northern Japan haplogroup was predominant at several sites near Undaria-cultivation sites. These results strongly suggested that cryptic invasion through Undaria mariculture occurred here, although its ecological impact remains unclear. There is a clear risk of invasion by mariculture seedlings from other regions, even when native conspecific populations are present.

Assessment of mutagenic activity of phlorotannin-enriched extracts of three brown algal species

BACKGROUND: Phlorotannins are unique phenolic compounds produced by brown algae. Due to their considerable biological activity these metabolites are extensively studied in the context of medicinal applications. However, to date, no studies addressed potential genotoxicity of phlorotannins.
 AIM: The objective of this research is an assessment of mutagenic activity of intracellular and cell wall (CW) bound phlorotannins of three brown algal species.
 MATERIALS AND METHODS: Mutagenicity of phlorotannin extracts of Desmarestia aculeata, Fucus serratus, and Ectocarpus siliculosus was assessed by the Ames test, carried out using three tester strains of Salmonella typhimurium (TA97, TA98, and TA100) with and without metabolic activation.
 RESULTS: Intracellular phlorotannin extracts of all tested algae showed relatively low values of minimum inhibitory concentration against S. typhimurium (20–30 μg/ml), with extract of D. aculeata being the most toxic. Intracellular phlorotannins of F. serratus and CW-bound polyphenols of E. siliculosus demonstrated moderate mutagenic activity in the Ames test inducing frameshift mutations with the number of His+ revertants more than twice higher compared to the control. The phlorotannin extracts of D. aculeata showed no mutagenic activity.
 CONCLUSIONS: The brown alga D. aculeata may be regarded as a promising source of phlorotannins for medical applications, as its phlorotannin-enriched extracts have high antibiotic activity and are not mutagenic.

18S rDNA gene metabarcoding of microeukaryotes and epi-endophytes in the holobiome of seven species of large brown algae.

Brown algae (Phaeophyceae) are habitat-forming species in coastal ecosystems and include kelp forests and seaweed beds that support a wide diversity of marine life. Host-associated microbial communities are an integral part of phaeophyte biology, and whereas the bacterial microbial partners have received considerable attention, the microbial eukaryotes associated with brown algae have hardly been studied. Here, we used broadly targeted "pan-eukaryotic" primers (metabarcoding) to investigate brown algal-associated eukaryotes (the eukaryome). Using this approach, we aimed to investigate the eukaryome of seven large brown algae that are important and common species in coastal ecosystems. We also aimed to assess whether these macroalgae harbor novel eukaryotic diversity and to ascribe putative functional roles to the host-associated eukaryome based on taxonomic affiliation and phylogenetic placement. We detected a significant diversity of microeukaryotic and algal lineages associated with the brown algal species investigated. The operational taxonomic units (OTUs) were taxonomically assigned to 10 of the eukaryotic major supergroups, including taxonomic groups known to be associated with seaweeds as epibionts, endobionts, parasites, and commensals. Additionally, we revealed previously unrecorded sequence types, including novel phaeophyte OTUs, particularly in the Fucus spp. samples, that may represent fucoid genomic variants, sequencing artifacts, or undescribed epi-/endophytes. Our results provide baseline data and technical insights that will be useful for more comprehensive seaweed eukaryome studies investigating the evidently lineage-rich and functionally diverse symbionts of brown algae.

The role of the epidermal physode layer in UV protection of Fucus species

Phlorotannins are believed to provide UV protection in brown algae. In Fucus species, phlorotannin-rich vesicles (“physodes”) form an “epidermal physode layer”, which might represent the anatomical structure responsible for UV protection. However, this layer has been neglected so far; instead, phlorotannin contents of entire thalli were studied in UV exposure experiments.We employed fluorometric methods to investigate in which wavelength region and to which degree the epidermal physode layer of two Fucus species reduces the transmittance of UV radiation. For comparison, we also studied Saccharina latissima, a brown algal species without epidermal physode layer.We could show that the epidermal physode layer absorbs throughout the entire UV wavelength range and reduces the epidermal UV-B transmittance into the thallus strongly (15% transmitted in F. vesiculosus vs. 80–100% in S. latissima). UV-B transmittances varied with growth depth and the variations correlated with photosystem II (PSII) stress responses upon artificial UV-B illumination. We found that the UV-B protection is more than sufficient for natural UV-B levels and of rather constitutive nature.In conclusion, the epidermal physode layer appears to be the anatomical feature exerting UV protection by phlorotannins in Fucus species and might thus be a core adaptation that enables Fucales the colonization of the intertidal habitat.

New record of Sporochnus dotyi (Sporochnales, Phaeophyceae) from Kii Peninsula, Japan

SUMMARYThe subtidal brown algal species Sporochnus dotyi Brostoff (Sporochnales, Phaeophyceae), which has been regarded as a Hawaiian endemic, is reported from Kushimoto, Kii Peninsula, Pacific coast of central Honshu, Japan, for the first time outside Hawai'i. The species grew on subtidal rocks ca. 5–20 m deep attached by a small conical holdfast. The erect thalli were 5–30 cm high, terete, robust and alternately branched in 1–2 orders. When mature, pedicellate receptacles developed on the branches, and formed elliptical sori 1 mm long with a pedicel 3–5 mm long. The apical parts of the thalli and the receptacles were terminated with a tuft of simple assimilatory filaments of up to 4 mm long and showed prominent green to yellow underwater iridescence. Reproductive filaments (paraphyses) were densely packed, simple, up to 200 μm long and bore 4–6 mostly unilateral unilocular zoidangia 20–22 μm long and 5–6 m in diameter. In the genetic analyses, the Sporochnus alga from Kushimoto had partial rbcL sequence identical to S. dotyi from Hawai'i. The cox3 phylogeny revealed that this alga formed a fully supported clade with S. dotyi. Therefore, we identified the alga from Kushimoto as S. dotyi. This finding of S. dotyi from Japan, together with the recent reports of the mesophotic macroalgae Ryuguphycus kuaweuweu (=Umbraulva kuaweuweu), Ulva iliohaha and Newhousia imbricata from various localities in the Pacific Ocean including Japan, suggest closer biogeographical connections of subtidal/mesophotic macroalgae in the Pacific than previously recognized.

Evolutionary dynamics of sex-biased gene expression in a young XY system: insights from the brown alga genus Fucus.

Sex-biased gene expression is considered to be an underlying cause of sexually dimorphic traits. Although the nature and degree of sex-biased expression have been well documented in several animal and plant systems, far less is known about the evolution of sex-biased genes in more distant eukaryotic groups. Here, we investigate sex-biased gene expression in two brown algal dioecious species, Fucus serratus and Fucus vesiculosus, where male heterogamety (XX/XY) has recently emerged. We find that in contrast to evolutionary distant plant and animal lineages, male-biased genes do not experience high turnover rates, but instead reveal remarkable conservation of bias and expression levels between the two species, suggesting their importance in sexual differentiation. Genes with consistent male bias were enriched in functions related to gamete production, along with sperm competition and include three flagellar proteins under positive selection. We present one of the first reports, outside of the animal kingdom, showing that male-biased genes display accelerated rates of coding sequence evolution compared with female-biased or unbiased genes. Our results imply that evolutionary forces affect male and female sex-biased genes differently on structural and regulatory levels, resulting in unique properties of differentially expressed transcripts during reproductive development in Fucus algae.

An assessment of physical and chemical conditions in alginate extraction from two cultivated brown algal species in Norway: Alaria esculenta and Saccharina latissima

Alginates are linear anionic polysaccharides originating from brown algae. Their properties target several application areas in in food-, technical- and pharmaceutical industries, and thus they are highly valued. Norway is currently the largest producer of cultivated seaweed in Europe, where the predominant species are Alaria esculenta and Saccharina latissima. So far, the utilisation of these two species have mainly been targeting food and feed applications. However, utilisation of these species for much broader application areas, including biopolymer and biomaterial markets, is of great interest. Both species are interesting candidates for future alginate production, but protocols for efficient extraction of high-quality alginate are lacking. In the present study, protocols for alginate extraction from fresh A. esculenta and S. latissima have been established. This has been accomplished by the identification and variation of key parameters in the extraction protocol, including pH, temperature and incubation times, and study of their effects on alginate quality and purity. Optimal conditions in the present study were found to be pH 9 in the alkaline extraction, and short extraction time (1–5 hours). The alginates extracted at pH 9 had a yield of 185 ± 7 and 229 ± 12 mg/g dry weight seaweed, and a weight average molecular weight (Mw) of 537 ± 12 and 503 ± 24 kDa in A. esculenta and S. latissima, respectively. The purity of the extracted alginates was evaluated based on the content of coextracted impurities and was found to be comparable with high-quality commercial alginates.

Seaweed-Derived Phlorotannins: A Review of Multiple Biological Roles and Action Mechanisms.

Phlorotannins are a group of phenolic secondary metabolites isolated from a variety of brown algal species belonging to the Fucaceae, Sargassaceae, and Alariaceae families. The isolation of phlorotannins from various algal species has received a lot of interest owing to the fact that they have a range of biological features and are very biocompatible in their applications. Phlorotannins have a wide range of therapeutic biological actions, including antimicrobial, antidiabetic, antioxidant, anticancer, anti-inflammatory, anti-adipogenesis, and numerous other biomedical applications. The current review has extensively addressed the application of phlorotannins, which have been extensively investigated for the above-mentioned biological action and the underlying mechanism of action. Furthermore, the current review offers many ways to use phlorotannins to avoid certain downsides, such as low stability. This review article will assist the scientific community in investigating the greater biological significance of phlorotannins and developing innovative techniques for treating both infectious and non-infectious diseases in humans.

Effects of seawater temperature and seasonal irradiance on growth, reproduction, and survival of the endemic Antarctic brown alga Desmarestia menziesii (Phaeophyceae)

Endemic Antarctic macroalgae are especially adapted to live in extreme Antarctic conditions. Their potential biogeographic distribution niche is primarily controlled by the photoperiodic regime and seawater temperatures, since these parameters regulate growth, reproduction, and survival during the entire life cycle. Here we analyzed the upper survival temperature (UST) of juvenile sporophytes and the temperature range for sporophyte formation from gametophytes of Desmarestia menziesii, one of the dominant endemic Antarctic brown algal species. This process is a missing link to better evaluate the full biogeographical niche of this species. Two laboratory experiments were conducted. First, growth and maximum quantum yield of juvenile sporophytes were analyzed under a temperature gradient (0, 5, 10, 12, 13, 14, 15, and 16 °C) in a 16:8 h light:dark (LD) regime (Antarctic spring condition) for 2 weeks. Second, the formation of sporophytes from gametophytes (as a proxy of gametophyte reproduction) was evaluated during a 7 weeks period under a temperature gradient (0, 4, 8, 12, and 16 °C), and two different photoperiods: 6:18 h LD regime simulating winter conditions and a light regime simulating the Antarctic shift from winter to spring by gradually increasing the light period from 7.5:16.5 h LD (late winter) to 18.5:5.5 h LD (late spring). Sporophytes of D. menziesii were able to grow and survive up to 14 °C for 2 weeks without visible signs of morphological damage. Thus, this species shows the highest UST of all endemic Antarctic Desmarestiales species. In turn, gametophyte reproduction solely took place at 0 °C but not at 4–8 °C. The number of emerging sporophytes was six times higher under the light regime simulating the transition from winter to spring than under constant short day winter conditions. There was a negative relationship between the number of sporophytes formed and the gametophyte density at the beginning of the experiment, which provides evidence that gametophyte density exerts some control upon reproduction in D. menziesii. Results strongly indicate that although sporophytes and gametophytes may survive in warmer temperatures, the northernmost distribution limit of D. menziesii in South Georgia Islands is set by the low temperature requirements for gametophyte reproduction. Hence, global warming could have an impact on the distribution of this and other Antarctic species, by influencing their growth and reproduction.

Protoplast isolation from Dictyopteris pacifica and Scytosiphon lomentaria, using a simple commercial enzyme preparation

BackgroundProtoplasts (i.e., naked plant cells) can be used for in vitro manipulations and genetic improvement in cultivars with economic value. During the last decade, protoplast research in economic brown algae has been scarce, and it is usually hampered by the use of non-commercial enzymes or crude extracts for isolating protoplasts. Dictyopteris pacifica is part of a brown algal genus well known by its wide chemical diversity and biological properties. Scytosiphon lomentaria is an edible brown seaweed with antioxidant, antitumor, and antiviral properties. So far, there are no protoplast isolation protocols using commercial enzymes for these two economic brown algae. In this study, we obtained protoplasts from cultured samples of D. pacifica and S. lomentaria using commercially available enzymes. Additionally, we investigated the effects of Driselase inclusion and Ca-chelation pre-treatment on protoplast yields in order to optimize the conditions for protoplast preparations. ResultsProtoplasts were isolated from Dictyopteris pacifica and Scytosiphon lomentaria using the commercially available Cellulase Onozuka RS (1%) and Alginate lyase (4 U mL−1), and short incubation time (4 h). Driselase did not show significant effects on protoplast production in both species. Ca-chelation pre-treatment only increased the number of protoplasts in D. pacifica. Under optimal conditions, the protoplast yields from D. pacifica and S. lomentaria were 4.83 ± 2.08 and 74.64 ± 32.49 × 106 protoplasts g−1 fresh weight, respectively. The values obtained for S. lomentaria were 2–3 orders of magnitude higher than previously reported. ConclusionsOur results show that high protoplast yields can be obtained from D. pacifica and S. lomentaria using a simple mixture of commercial enzymes (Cellulase RS and Alginate lyase) and short incubation time (4 h). This work also represents the first report of protoplast isolation in D. pacifica. The method proposed here can help to expand protoplast technology in more brown algal species.

Targeted CRISPR-Cas9-based gene knockouts in the model brown alga Ectocarpus.

Brown algae are an important group of multicellular eukaryotes, phylogenetically distinct from both the animal and land plant lineages. Ectocarpus has emerged as a model organism to study diverse aspects of brown algal biology, but this system currently lacks an effective reverse genetics methodology to analyse the functions of selected target genes. Here, we report that mutations at specific target sites are generated following the introduction of CRISPR-Cas9 ribonucleoproteins into Ectocarpus cells, using either biolistics or microinjection as the delivery method. Individuals with mutations affecting the ADENINE PHOSPHORIBOSYL TRANSFERASE (APT) gene were isolated following treatment with 2-fluoroadenine, and this selection system was used to isolate individuals in which mutations had been introduced simultaneously at APT and at a second gene. This double mutation approach could potentially be used to isolate mutants affecting any Ectocarpus gene, providing an effective reverse genetics tool for this model organism. The availability of this tool will significantly enhance the utility of Ectocarpus as a model organism for this ecologically and economically important group of marine organisms. Moreover, the methodology described here should be readily transferable to other brown algal species.

Sargassum, Padina and Turbinaria as bioindicators of cadmium in Bais Bay, Negros Oriental

Marine pollution is becoming one of the global environmental problems around the world. Heavy metal concentrations in the environment is 100-1,000 folds higher than those in the Earth’s crust due to anthropogenic sources. The use of algae as bioindicators of metal pollution and the effective removal of toxic metal ions has received increasing attention. Brown algae is thought to be excellent in the sequestration of metal. In this study, cadmium (Cd) concentration in the thalli of Sargassum sp., Padina sp. and Turbinaria sp. from North Bais Bay, Negros Oriental was determined using Atomic Absorption Spectrophotometer (AAS). The concentration of cadmium in the sediment of North Bais Bay was also determined because environmental pollutants could also accumulate in the sediment. Results of this study showed the cadmium contamination in Bais Bay, wherein Sargassum sp., Padina sp., and Turbinaria sp. absorbed these cadmium ions. Sargassum sp. had the highest concentration of cadmium which ranged from 2.14 to 4.45 mg kg-1 . The concentration of cadmium in Padina sp. and Turbinaria sp. ranged from 2.2 to 3.4 mg kg-1 and 2.36 to 2.76 mg kg-1 , respectively. The concentration of cadmium in the sediment ranged from 3.72 to 5.53 mg kg-1 dry weight. This indicates that these brown algal species could be utilized as bioindicators of cadmium contamination in marine waters and possible phytoremediation of cadmium in wastewater.

Biochemical study of attached macroalgae from the Madeira Archipelago and beach-cast macroalgae from the Canary Islands: multivariate analysis to determine bioresource potential

AbstractFifteen attached macroalgae from the Madeira Archipelago, comprising three green, three red and nine brown algal species, as well as two beach-cast macroalgal samples, collected along the north shore of Gran Canaria, were assessed for their biochemical properties. The analysis included the determination of total minerals, total carbohydrates, protein, lipids, chlorophylla, total carotenoids, total phenolic content, fucoxanthin and phycobilins (allophycocyanin, phycocyanin and phycoerythrin). The results showed a high variability of biochemical composition, allowing for the targetting of specific bioresources for particular purposes, including functional foods. This work provides the foundation for a biorefinery strategy implementation plan, for which specific macroalgae may be targeted for valuable and beneficial compounds.

Flagellar motility during sperm chemotaxis and phototaxis in fucalean algae

ABSTRACT The swimming of male gametes of brown algae is controlled by two heterokont flagella, regardless of reproductive system, but the patterns of flagellar movement can vary. We investigated sperm chemotaxis and phototaxis in four oogamous Australasian fucalean species. Sperm morphology was similar to that of male gametes of isogamous and anisogamous species but their chemotactic behaviours were much closer to those of other oogamous species than those of isogamous and anisogamous species. Moreover, unlike anisogamous species, sperm chemotaxis of the oogamous species, Hormosira banksii, was not inhibited by a phosphodiesterase inhibitor, theophylline, suggesting variability in regulatory mechanisms of sperm chemotaxis amongst brown algae. In our previous work, lower extracellular Ca2+, supernatant of female gametes and theophylline induced the reversal of phototactic signs in anisogamous male gametes. In contrast, lower extracellular Ca2+ and theophylline did not significantly affect phototaxis in sperm of the oogamous H. banksii. Moreover, high extracellular Ca2+ and supernatant of eggs disrupted the negative phototaxis but did not reverse their phototactic sign. These results suggest that the regulation of phototaxis also varies amongst brown algal gametes. Further investigation of brown algal species is warranted to assess the generality of these patterns of chemotaxis and phototaxis among anisogamous and oogamous gametes.

Photoprotection properties of marine photosynthetic organisms grown in high ultraviolet exposure areas: Cosmeceutical applications

Seaweeds have been identified as promising sources of bioactive substances for the cosmeceutical industry, especially by their photoprotection capacity. Accordingly, this study aimed to evaluate the photoprotective properties of extracts from macroalgae and one marine lichen. Samples of 22 species of macroalgae and one marine lichen, were collected along the southern Iberian Peninsula. Hydroethanolic extracts were prepared from algal and marine lichen lyophilized biomass. Ultraviolet (UV) and visible absorption spectra, polyphenol content, antioxidant activity, mycosporine-like amino acid content and composition were analyzed. In order to quantify the photoprotection capacity of the extracts against different biological effects, two new indices were used, i.e., effective solar absorption radiation (%ESAR) and extract photoprotection index (EPI), considering the radiation absorbed and transmitted by the extract, respectively. In the ultraviolet spectrum, Porphyra umbilicalis and Pyropia elongata presented the highest absorbance values at 330 nm, while Ulva lactuca showed a prominent peak at 290 nm. In the visible spectrum, a fucoxanthin peak (450 nm) was strongly evident in extracts from the brown algal species, while green algal extracts presented characteristic chlorophyll a and b peaks at 447, 620 and 664 nm. Polyphenol content and antioxidant activity were much higher in Sargassum vulgare, Carpodesmia tamariscifolia, P. umbilicalis and Lichina pygmaea in comparison to the other species. P. umbilicalis and Bangia atropurpurea showed the highest amount of mycosporine-like amino acids. S. vulgare and P. umbilicalis extracts presented the highest values of potential photoprotection against all analyzed biological response according to the different action spectra. S. vulgare and P. umbilicalis showed an increase in %ESAR values associated with an increase in the concentration of their extracts. Considering the analyzed species, our results suggest that S. vulgare and P. umbilicalis could be potential sources of photoprotective extracts. The potential use of these species in cosmeceutical products is discussed.

Molecular phylogeny of Punctaria mageshimensis reveals evidence for its transfer to Spatoglossum as S. mageshimense (Dictyotales, Phaeophyceae)

SUMMARYTaxonomy of the little‐studied brown algal species Punctaria mageshimensis (Ectocarpales s.l.) was reexamined by molecular phylogeny and morphology. In the genetic analyses of newly collected specimens using plastid rbcL and psaA gene sequences, the specimens morphologically referable to P. mageshimensis were phylogenetically distant from Ectocarpales s.l. and were included in the clade of Spatoglossum (Dictyotales). Morphological reexamination of the type specimen and newly collected specimens confirmed its systematic position in Dictyotales: Branched thallus; cushion‐shaped rhizoidal holdfast occasionally forming secondary holdfast at the bottom of the thallus; many discoidal plastids without pyrenoid per cell; tetrasporangium‐like reproductive structures with dark, homogeneous cell content; occurrence of hair tufts. Genetically P. mageshimensis was most related to a reported sequence of Spatoglossum asperum, but P. mageshimensis was considerably different from S. asperum as well as other known Spatoglossum species in the deep habitat and in having scarcely‐branched lanceolate and considerably thickened thallus. In conclusion, we propose the transfer of P. mageshimensis to Spatoglossum as S. mageshimense comb. nov.

ФЛОРА ВОДОРОСЛЕЙ-МАКРОФИТОВ КОМАНДОРСКИХ ОСТРОВОВ: РЕВИЗИЯ-2020. I. CHLOROPHYTA И OCHROPHYTA

In Commander Islands, the peculiar geographic location, hydrology and geomorphology contributed to de-velopment of a very peculiar algal floristic complex. First scientific information on species composition in this region appeared in XIX century. In this revision, we analyzed scientific publications containing algal floristic information from this region and composed list of species recorded during 1889–2020. We provided information about 52 green and 55 brown algal species recorded from the Commander Islands. The infor-mation concerning representatives of Laminariales is discussed in details, as they form basis of the underwa-ter vegetation. Our species list includes citations of references containing records from the Commander Is-lands and brief description of their biological and morphological characteristics. As we noted, in Russian Far East, Commander Islands belong to one of the few regions with highly examined algal flora.

Initial evaluation of six different brown algae species as source for crude bioactive fucoidans

The fucose-containing sulfated polysaccharides (syn. fucoidans) from brown seaweeds exhibit multiple biological activities. The aim of the present study was to evaluate the suitability of crude fucoidans from six different brown algal species for further research and development. For this, fucoidans were extracted from Fucus vesiculosus (F.v.), F. serratus (F.s.), F. evanescens (F.e.), Dictyosiphon foeniculaceus (D.f.), Laminaria digitata (L.d.), and Saccharina latissima (S.l.) and compared concerning their yields, their basic characteristics, degree of sulfation (DS), molecular mass, monosaccharide composition, their contents of polyphenols, laminarin and protein as well as their radical-scavenging capacity, three exemplary bioactivities and their fluorescence intensity (FI) increasing effect on the sulfated glycan sensor Polymer-H. The activities positively correlated with the DS, fucose content and the FI of Polymer H, whereas the antioxidant capacity correlated with the coextracted polyphenols. The best predictive power for the activities showed to have the combination of FI of Polymer-H and DS, which can thus be used for an initial screening of algae extracts. D.f. turned out to be unsuitable as fucoidan source, as the extract had only a low DS (0.14) and fucose content (38.7%) as well as the weakest bioactivities. The fucoidans from S.l. and F.e., which had the fucose content, highest DS, purity and yield, exhibited the best activities and thus proved to be the fucoidans most suitable for further investigations.