Brown algae constitute key primary producers in cold and temperate coastal ecosystems, and face various stresses including pathogen infection. Yet the molecular mechanisms underlying their pathogen defence responses remain poorly understood. Here, we investigated the cell wall remodelling processes that define basal immunity in brown algae by comparing Ectocarpus strains with contrasting resistance levels to the biotrophic oomycete pathogen Eurychasma dicksonii. Using transmission electron microscopy, biochemical analyses, single-molecule fluorescent in situ hybridization (smFISH) and RNA sequencing, we demonstrate that infection triggers extensive extracellular matrix reorganization across all strain combinations. Resistant strains exhibited constitutively higher phlorotannin levels and increased physode abundance, while susceptible strains showed significant cell wall thickening and a less enhanced cell wall-bound phlorotannin accumulation following infection. Single-molecule FISH analysis demonstrated spatial recruitment of phlorotannin biosynthesis (polyketide synthase) and crosslinking (vanadium-dependent bromoperoxidase) transcripts to infection sites, forming characteristic ring-like patterns around infection areas. Transcriptomic analysis revealed extensive remodelling of cell wall biosynthetic pathways, with particular emphasis on genes encoding carbohydrate-active enzymes and Wall Sensing Component (WSC) domain proteins. These findings establish a molecular and biochemical framework of brown algal basal immunity, highlighting extracellular matrix remodelling as a conserved defence strategy against biotrophic oomycetes.
Cyanobacterial pigments are complex mixtures of water-soluble and lipophilic compounds with diverse properties and biological roles. There is a growing interest in investigating these pigments due to their potential applications in biotechnology, food production and various industrial sectors. Additionally, they serve as important markers in ecological studies, phylogenetic analyses and ecotoxicology research. Low-pressure liquid chromatography (LPLC), thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) are commonly used laboratory techniques for the fractionation and separation of pigments, with spectrophotometry being the preferred detection method. However, to date, no single study has combined all these techniques for the comprehensive analysis of cyanobacterial photosynthetic pigments. This paper presents the application of these accessible and straightforward techniques for the separation and characterization of cyanobacterial lipophilic pigments. The extraction was performed on two unicellular species, Synechocystis salina and Microcystis aeruginosa, and three filamentous cyanobacteria, Aphanizomenon flos-aquae, Nodularia spumigena and Anabaena cylindrica. The study highlights the capabilities and limitations of spectrophotometric detection of carotenoids and chlorophylls in in vivo cultures and extracts, as well as the challenges related to chlorophyll stability. Experimental work is supplemented with relevant literature and provides practical guidance on the use and interpretation of results from widely available techniques, making it a valuable resource for researchers across various fields.
This study investigates the effects of sustained nutrient stress caused by reduced concentrations of trace elements (Fe, Mn, Zn, Cu, Co, Mo at 25%, 50% and 75% of standard levels in Guillard's f/2 medium) on the biomass and nutritional and antioxidant properties of the unicellular green alga Dunaliella salina. Over a 12-day cultivation period under controlled photoautotrophic conditions, significant variations were observed. Biomass productivity remained stable in the control (p > 0.05) and at 75% trace element levels. beta-carotene synthesis peaked at 1.90 mg g(-1) day(-1) in Mn 50% compared to other treatments (p < 0.05). Lipid content reached a maximum of 58.78% in Fe 25%, significantly higher than in other treatments (p < 0.05), with triacylglycerol (TAG) content increasing to 68.1% in Fe 50% (p < 0.05), indicating enhanced lipid accumulation under 50% iron limitation. Fatty acid profiles revealed elevated C16:1 and C18:1 in Fe 75% (p < 0.05), while Co 75% exhibited the highest C18:2n6cis (6.82 +/- 0.32%) (p < 0.05). Antioxidant activity peaked at 97.09% in Fe 25% at 40 mg ml(-1) of DPPH radical scavenging (p < 0.05), with a strong correlation (r = 0.974-0.986, p < 0.001) between beta-carotene content and antioxidant capacity. Bioactive compounds, including lutein (2.05 & micro;g mg(-1)) and phenolics (4.05 mg GAE g(-1)) in Fe 25% (p < 0.05), and trace element uptake patterns further elucidated nutrient dynamics. Principal component analysis (PCA) of all variance explained 81.0% of variance, linking PC1 to bioproduct yields and PC2 to trace element retention. These findings demonstrate that reduced trace element levels (25-50%) optimize lipid, beta-carotene and antioxidant yields, offering a viable strategy for enhancing the biotechnological potential of D. salina for biofuel, nutraceutical and bioremediation applications.
Karenia selliformis is a toxin-producing athecate dinoflagellate found worldwide. This species can form extensive harmful algal blooms (HABs) that have been associated with the mass mortality of marine fauna. On 24 August 2020, a dinoflagellate bloom was recorded in Bah & iacute;a Todos Santos (BTS), Baja California, Mexico. During this high-biomass phytoplankton event, in which K. selliformis was detected and confirmed morphologically and by molecular methods, temperature 23.68 degrees C, chlorophyll a > 10 mg m(-3), and cell densities of 200-900 cells l(-1) were recorded. A total of 44 sequences (620 bp) of the ribosomal large subunit (LSU) and 37 sequences (570 bp) of the internal transcribed spacer (ITS1 + 5.8S + ITS2) region of rDNA, obtained from GenBank and generated in this study, were analysed. In total, 15 sites of the LSU were informative while 605 sites were invariant. Fifteen polymorphisms and eight ribotypes were identified, with a haplotypic diversity (Hd) of 0.647 and a nucleotide diversity (pi) of 0.00558. In addition, 21 sites of the ITS were informative while 549 sites were invariant. For these 21 polymorphic sites, five ribotypes were identified, with an Hd value of 0.611 and pi value of 0.01330. Our results demonstrate distinct ribotypes within K. selliformis and provide molecular evidence for a cryptic species complex across biogeographic provinces. This study highlights the need to reassess species boundaries within Karenia using integrative approaches.
Conventional monitoring of toxic phytoplankton is time consuming, requires large sample volumes and depends on expert taxonomic identification, highlighting the need for faster, more sensitive and widely accessible methods. The globally distributed dinoflagellate Prorocentrum cordatum contributes to harmful algal blooms, posing serious risks to marine ecosystems and coastal economies. This study presents a sample-to-result molecular assay for the detection of P. cordatum using the polymerase chain reaction (PCR) and loop-mediated isothermal amplification (LAMP) targeting the ITS and psbA genes. Analyses were performed on small volumes of water (5-50 ml), from Santa Catarina Island, southern Brazil, which were concentrated with syringe filters and membranes. Sensitivity was evaluated through 10-fold serial dilutions of P. cordatum DNA, and specificity tested against three other potentially harmful dinoflagellates, P. lima, P. hoffmannianum and Takayama acrotrocha. Detection limits were 5.3 & times; 10(2) cells l(-1) for ITS-PCR and 5.3 & times; 10(3) cells l(-1) for psbA-PCR; and 5.3 & times; 10(5) and 5.3 & times; 10(6) cells l(-1) for ITS-LAMP and psbA-LAMP, respectively. In field tests (n = 48, all <10(6) cells l(-1)), P. cordatum was detected in 32 samples by ITS-PCR and 29 by psbA-PCR. In contrast, ITS-LAMP detected the species in only three samples, and psbA-LAMP in none. Overall, PCR proved highly sensitive and specific for detecting low cell densities, while LAMP, although less sensitive, offers a possible portable option for field monitoring during moderate-to-high bloom conditions.
Despite being one of the most consequential events in the evolutionary history of diatoms, the emergence of pennates remains poorly understood both in terms of its timing and their ancestry. Here, we re-examined several Late Cretaceous (Campanian) diatom-rich samples from the Alpha Ridge in the Central Arctic Ocean using scanning electron microscopy with a focus on pennate taxa. Greater than anticipated species richness was recovered, increasing known Cretaceous araphid diatom flora by 25%. No raphid pennates were encountered. The majority of taxa found have heteropolar valves, with either field pores, ocelli and/or ocellulimbi, simple pores making up striae, and one rimoportula. Only one species found was previously known to science. One new genus (Cesaria) and three species (Cesaria palaiospennata, Kannoa archaea and K. simswilliamsorum) are formally proposed. For six others, the considered taxonomic affinity ranges from species to family and remains tentative. The plasticity of the structural characters of Cesaria frustules may serve as an example of a valve design that could have been advantageous among the earliest araphid pennates. Extinct Kannoa species show overall structural similarity to extant Asteroplanus and Asterionellopsis. Our unnamed species show some affinity to the genera Sceptroneis, Lancineis, Neodelphineis, and possibly other broadly defined Rhaphoneidaceae. All our diatoms are relatively small and delicate and can easily go unnoticed among the abundance of accompanying large and heavily silicified polar and non-polar centrics. If our assumptions regarding their taxonomic affinity based on morphological similarities are correct, the molecular phylogenies place them all among the earliest divergences of the pennates.
Inorganic N and P were introduced into municipal wastewater from anaerobic ponds to manipulate the N:P ratio thereby promoting the growth of exogenously inoculated green algae (Chlorella sp.) that outcompeted blue-green algae (Microcystis sp.). Alternate nutrient limitation and enrichment were used to manipulate the N:P ratio. An N:P of 1:60 was used to culture both green algae and cyanobacteria either separately or in combination. These ratios were then reversed to compare growth in order to develop effective N:P manipulation. The correlation between phosphate concentration and Chlorella sp. abundance showed that both Chlorella sp. and mixed algal culture can grow well within the range of 0.05-0.45 mg l(-1) of phosphate with N:P = 1:60. However, the relationship between growth of Chlorella sp. and nitrate-N indicated that green algae were almost independent of water nitrate-N. But the overall relationship between N:P and Chlorella sp. showed that more input of phosphorus than nitrogen in the N:P = 1:60 treatment was conducive to growth of Chlorella sp. This relative N:P manipulation will help to outcompete blue-green algae which generally grow even at low levels of nitrate-N with the help of their attached microbiome. Therefore, simple inorganic phosphate fertilizer addition to anaerobic wastewater with high ammonium-N, can prove to be a less challenging, cost-effective wastewater nutrient management and re-use strategy using a bio-circular economy approach for culture of benign green algae in the aquatic food chain as well as for aquaculture production.
Optimizing biomass yield and biochemical composition in sea-based cultivation of Ulva fenestrata requires balancing environmental conditions with cultivation timing. This study examined how outplant and harvest timing influence growth and biochemical traits in a temperate sea-based aquaculture system. Outplant timing had a pronounced effect on biomass yield, while biochemical composition was more strongly influenced by harvest timing and associated environmental factors. Seedlings deployed in autumn (September-November) achieved up to eight-fold higher biomass than those outplanted in late winter or spring (February-March). Despite low temperature and light during early winter, autumn outplants maintained slow but steady growth, indicating physiological resilience and effective nutrient utilization under suboptimal conditions. Biochemical composition - including crude protein, chlorophyll, carotenoids and total fatty acids - peaked during late winter to early spring harvests when ambient nitrate levels were highest. As temperature and light increased in spring, tissue nitrogen and polyunsaturated fatty acid contents declined, reflecting nitrogen limitation and temperature-driven lipid remodelling. This trade-off between maximizing biomass under warmer conditions and maintaining nutritional quality during cooler, nutrient-rich periods highlights the need for strategic cultivation management. We conclude that optimal production of U. fenestrata in temperate waters is achieved by autumn outplanting and harvest before the spring nutrient decline when aimed at food purposes. Continuous environmental monitoring, adaptive harvest timing and strain selection could further enhance both biomass yield and quality, supporting sustainable and high-value Ulva cultivation. HIGHLIGHTS circle Autumn outplanting significantly enhances biomass accumulation in Ulva fenestrata. circle Harvest timing exerts stronger control on biochemical composition than deployment: peak protein, pigment and fatty acid levels coincide with high ambient nitrate while elevated temperature and irradiance reduce tissue nitrogen and PUFA content. circle Optimized production requires autumn seeding and pre-spring nutrient decline harvest.
The genus Raphidocelis, a common member of the freshwater phytoplankton, comprises several morphological species. It is a small coccoid green alga with an autosporic life cycle and a remarkable crescent-shaped morphology. Although these species have not yet been sequenced, previous studies have shown that the same morphotype is distributed across 10 different clades within the family Selenastraceae. Here, we propose the description of Raphidocelis angusta sp. nov. a new crescent-shaped species, based on the study of three strains using light, scanning and transmission electron microscopy, as well as 18S rDNA and rbcL phylogenies and ITS2 secondary structure. The phylogenetic analyses by 18S rDNA and rbcL show that the closest relative to our new lineage is Raphidocelis subcapitata, the model organism extensively employed in bioassays worldwide. This study contributes to clarifying the phylogeny and taxonomy of Raphidocelis, adding reference sequences of overlooked phytoplankton to GenBank, including strains from Brazil and Germany.
A new benthic unarmoured dinoflagellate, Paramphidinium jejuensis sp. nov. was isolated from Pyoseon Beach, Jeju Island, Korea, and is described here. The cells were observed using light, scanning and transmission electron microscopy. Phylogenetic analyses were conducted using partial SSU and LSU rDNA sequences. The species exhibits two forms, motile and sessile. Motile cells are oval, 26-35 & micro;m in length & times; 18-24 & micro;m in width, whereas sessile cells are larger, 35-38 & micro;m long & times; 27-30 & micro;m wide, with a round and broad shape. The episome is much smaller than the hyposome and becomes embedded within it in the non-motile (sessile) state. A distinct ventral pit occurs at the posterior end of the episome, and a small, shallow sulcus is located below the episome near the cell centre. The nucleus is spherical, located in the centre of the hyposome. The morphological features are most similar to Amphidinium mootonorum, but P. jejuensis can be distinguished by the shape of the nucleus, sulcus position and the shape of the episome when in a sessile state. The phylogenetic analyses of rDNA showed that P. jejuensis clearly differed from A. mootonorum and formed a clade with A. mootonorum separate from the Amphidinium sensu stricto group. This clade is significantly divergent from the other genera which belong to the Amphidiniales, Gymnodiniales and Ptychodiscales. These morphological and phylogenetic results allow us to establish a new genus Paramphidinium with Paramphidinium mootonorum (Sh.Murray & D.J.Patterson) comb. nov. as the type species and to describe Paramphidinium jejuensis gen. et sp. nov.https://zoobank.org/urn:lsid:zoobank.org:pub:9D521B2E-36A4-4902-887F-4F8C31427EF6
This study investigated the effects of different partial harvest frequencies on the cultivation of the green macroalga Ulva ohnoi using water from whiteleg shrimp Penaeus vannamei biofloc systems over 6 weeks. Specimens of U. ohnoi reproduced in the laboratory were stocked at 1 g of fresh weight (FW) l(-1) in 50 l tanks. Four experimental groups were evaluated: three partial harvest frequencies (every 7, 14 and 21 days), where biomass exceeding the initial stocking of 1 g FW l(-1) was removed from the tanks, and full harvest at 42 days, at which point the partial harvest treatments were also fully harvested. Each group had six replicates for a total of 24 experimental units. Weekly, water from a shrimp biofloc tank was filtered with a 20 & micro;m bag filter and used to fill the algae tanks, whose previous water was discarded. Weighing the algae after removing water with a manual centrifuge was performed weekly. Standing biomass was highest in the 42-day group from week 4 onwards (p < 0.05), while growth rates showed significant differences primarily in weeks 2 and 3, with the 7 day partial harvest frequency showing higher rates (p < 0.05). Final yield and nitrogen and carbon removals did not differ between treatments (p > 0.05), whereas phosphorus removal was significantly higher in the 42-day harvest group (p < 0.05). This indicates that cumulative biomass production was similar among harvest regimes, supporting the feasibility of a single 42-day harvest. In conclusion, a 42-day harvest interval can simplify operational management by reducing frequent harvests while maintaining yield and improving nutrient removal in U. ohnoi cultivation within a decoupled biofloc-based integrated system with shrimp compared with different partial harvest regimes.
We determined the nuclear DNA content in five common marine brown macroalgae from the Norwegian coast, comprising three representatives of Ectocarpales (Dictyosiphon foeniculaceus, Leathesia marina, Asperococcus bullosus), one representative of Chordales (Chorda filum) and one representative of Laminariales (Alaria esculenta). This study provides the first nuclear DNA content estimates for four of these taxa, thereby expanding the Kew database of unreplicated gametic nuclear DNA content. The three Ectocarpales species exhibited remarkably consistent 1C values of approximately 0.2 pg, independent of thallus morphology (globose, filiform and branched, or irregularly inflated and tubular), while the representatives of Chordales and Laminariales demonstrated significantly higher values of 0.64 pg and 0.62-0.75 pg, respectively. We constructed a phylogenetic tree relating the studied brown algae species to their respective C-values. This suggests that phylogeny, rather than thallus morphology, is the primary determinant of nuclear DNA content. The relationship between age/cell size and nuclear DNA content warrants further investigation, particularly in Laminariales. Brown algae typically exhibit a life cycle that alternates between haploid and diploid phases, which can manifest in varying morphology and size. Additionally, they employ diverse sexual or asexual reproduction strategies and often generate environmentally resistant resting stages. Consequently, the same species may display variations in nuclear content and ploidy throughout its life cycle. Recently, ploidy manipulation in brown algae has gained attention among breeders and cultivators for its potential application in aquaculture, like its established use in terrestrial plants. However, our understanding of ploidy dynamics within different brown algal lineages remains limited.
Target of rapamycin (TOR) is a conserved eukaryotic kinase that regulates cell growth and metabolism in coordination with the energy and nutrient status. Although the role of TOR signalling in starch and triacylglycerol accumulation has been established in microalgae, whether TOR also regulates the production of hydrocarbons in photosynthetic organisms is largely unknown. Colonial green microalgae of the genus Botryococcus have been studied due to their ability to produce large amounts of liquid hydrocarbons, suitable for use as biofuel feedstocks. Here, we studied TOR signalling in B. alkenealis (formerly A race), a fatty acid-derived hydrocarbons producer, and B. braunii (formerly B race), a triterpene hydrocarbons producer, by using the selective TOR inhibitor AZD-8055, with/without glucose supplementation. Although AZD-8055 treatment effectively reduced Botryococcus biomass production in both cultures, it did not significantly affect B. braunii hydrocarbon production under photoautotrophic and mixotrophic conditions. However, B. alkenealis cultures treated with AZD-8055 showed an increase in extracellular hydrocarbon accumulation in a dose-dependent manner. Chemical TOR inhibition downregulated the expression of Ba- and BbTOR and a core cell-cycle gene, Ba- and BbCYCD, but their expression levels were upregulated upon glucose addition. Our results indicate that TOR modulates fatty acid-derived hydrocarbon production from B. alkenealis in response to nutrient availability, but not triterpene hydrocarbons from B. braunii.
Diatoms are one of the most species-rich and environmentally significant protist groups on Earth, playing important roles in the biogeochemical cycles and food webs of many (semi)aquatic ecosystems. However, much of their species-level diversity lies beyond the resolution of traditional microscopy-based methods that are routinely, and sometimes exclusively, utilized in diatom taxonomy. One such cryptic species complex is Pinnularia acidicola, which was recently shown to consist of at least three different species-level lineages inhabiting remote southern hemisphere islands. Here, we (1) compare the P. acidicola complex to its closest relatives from P. subcapitata and P. sinistra using both published and newly established strains, (2) integrate all currently available evidence - including from light and scanning electron microscopy, conventional and geometric morphometrics, molecular phylogenetics, eDNA-based biogeography and ecology - and (3) formally resolve the three species. The P. acidicola name is reserved for the type population found on Ile de la Possession and Marion Island, while the population found on R & eacute;union is described as P. acidireunionensis. The population sampled on Ile Amsterdam is newly recognized as the already described P. vixconspicua, and epitypes including DNA sequences are designated. The three species are genetically distinct, exhibit non-overlapping geographic distributions and are morphologically differentiated by subtle, yet significant morphometric differences in valve dimensions, fascia and striation. Despite this, all three species appear to share an ecological preference for acidic soils, ponds or streams. Altogether, our comprehensive analysis of the P. acidicola species complex highlights the importance of combining both morphological and genetic approaches in uncovering diatom species diversity.
Cyanobacteria are an ancient and diverse group of oxyphototrophic bacteria found across a wide range of environments. The taxonomic diversity of terrestrial cyanobacteria inhabiting rock surfaces remains poorly studied despite their key role as pioneering species in ecological succession. We isolated two phycoerythrin-rich strains resembling the genus Leptolyngbya in a survey of filamentous cyanobacteria from previously unstudied epilithic habitats on the Suomenlinna Fortress (UNESCO World Heritage site) in Finland. We employed a comprehensive polyphasic approach to characterize these isolates to account for the known polyphyletic nature of Leptolyngbya and the presence of cryptic taxa. Our analyses revealed that the two strains form a distinct and well-supported clade within the family Leptolyngbyaceae. Therefore, we propose a new monospecific genus, Sivoneniella, following the International Code of Nomenclature for Algae, Fungi, and Plants. Secondary structures of conserved 16S-23S ITS regions (D1-D1', box B and V3 helices), ITS per cent dissimilarity, multi-locus phylogenies (16S rRNA, rbcLX, rpoC1), and genome-based phylogenomic analyses all support the recognition of this novel cryptic genus. Genome mining and LC-MS analyses revealed the absence of known cyanotoxins in both strains (UHCC 1019T and UHCC 1020), and their cell extracts exhibited no inhibitory effects on the growth of relevant pathogenic bacteria and fungi. These findings advance our understanding of cyanobacterial diversity in terrestrial ecosystems, support the establishment of Sivoneniella as a new genus within the order Leptolyngbyales and explore the biotechnological potential of phycoerythrin-rich strains of S. epilithica.
During revision of the algal culture collection of the Institute of Botany (IBASU-A), Ukraine, some interesting strains of cyanobacteria were discovered, potentially representing new phylogenetic lineages at the genus rank. A polyphasic approach combining 16S rRNA gene phylogeny, percentage identity of 16S rRNA, 16S-23S ITS secondary structures, morphological and ultrastructural analyses was used to describe (according to the International Code of Nomenclature for algae, fungi and plants) two new taxa: Carminoleptolyngbya arenaria gen. et sp. nov. (Leptolyngbyales, Leptolyngbyaceae) and Kondratevia charkoviensis gen. et sp. nov. (Oscillatoriales, Microcoleaceae). These cultures had been obtained from terrestrial habitats of Germany (Baltic sand dunes) and Ukraine (cretaceous outcrops of Kharkiv region) respectively. C. arenaria has a Leptolyngbya-like morphology: thin, tortuous, greyish-pinkish trichomes, constricted and granulated at the cross-walls, with elongated cells and delicate sheaths, forming a film of carmine (=crimson-red) colour on the agar surface. TEM showed parietal parallel thylakoids typical of Leptolyngbyales and Oculatellales. This strain forms a well-supported lineage within Leptolyngbyales together with several strains identified as Leptolyngbya and Pseudanabaena from freshwater and terrestrial habitats of Europe and Asia, that might represent other unknown species of Carminoleptolyngbya. Phylogenetic analysis placed this taxon within Leptolyngbyaceae with Stenomitos as closest relative. K. charkoviensis has a Microcoleus- or Phormidium-like morphology: trichomes straight, cylindrical, slightly constricted at the cross-walls, tapered and curved at the ends, sheath firm, hyaline or yellowish, with elongated, conical-rounded and bent terminal cells. This strain forms a well-supported lineage within Oscillatoriales, Microcoleaceae with Kamptonema, Tychonema, Microcoleus and Microcoleusiopsis as closest relatives. TEM showed waved parallel thylakoids located near cell walls and within the cell which is typical for Oscillatoriales. Our data confirm that many undiscovered cyanobacteria still exist not only in terrestrial habitats, but also in algal culture collections.
Green synthesis of nanoparticles is a potentially valuable technique for the pharmaceutical industry. The purpose of our research was to assess the in vitro antimicrobial and antidiabetic activity of silver nanoparticles synthesized using an aqueous extract of Sargassum tenerrimum. We confirmed that the aqueous extract of S. tenerrimum can fabricate silver nanoparticles. The nanoparticles were characterized using UV-Visible spectroscopy, Fourier Transform Infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM), EDAX (Electron Dispersive Spectroscopy) and X-ray diffraction. The dark brown silver nanoparticles showed absorbance at 440 nm confirming nano-formulation. The FTIR spectrum identified the functional groups and absorption peaks, while the nanoparticles in SEM were 19.0 +/- 5.4 nm in size with a smooth surface. The nanoparticles showed antimicrobial effects against pathogenic microorganisms (Gram-negative Pseudomonas aeruginosa and Escherichia coli and Gram-positive Bacillus cereus and Staphylococcus aureus) with Minimum Inhibitory Concentrations (MIC) of 72.2, 72.2, 64.6 and 57 mu g, respectively. The nanoparticles were biocompatible and non-toxic and exhibited a dose-dependent glucose uptake in L6 myoblast cells, with 2.94 mu g ml-1 resulting in >50% uptake. The nanoparticles increased the expression of GLUT4 at low concentrations. Thus, silver nanoparticles synthesized from S. tenerrimum aqueous extract should be studied in vivo to explore their potential as a pharmaceutical agent.
This study evaluates the diversity and distribution of species of the genus Halosaccion along the Russian Pacific coast using morphological data and molecular analyses. Halosaccion minjaii was found to be genetically distant from other species in the genus; this and its unique morphological features - namely the development of tetrasporangia in elevated sori between long sterile filaments (which are much longer than tetrasporangia) and the mode of spermatangia formation - led to the proposal of a new genus, Nothohalosaccion, with a single species N. minjaii. Data on species distribution in the north-western Pacific were refined. Halosaccion americanum was recorded for the first time in the Okhotsk Sea. This extended the species range north-westward. In contrast, the distribution of Halosaccion microsporum was restricted to northern and western parts of the Okhotsk Sea, the eastern Kamchatka coast and western Bering Sea. The distribution patterns of species of the genera Halosaccion and Nothohalosaccion are discussed in relation to the oceanography of the region. Types of the names H. microsporum, Dumontia hydrophora (equivalent to Halosaccion hydrophorum) and Ulva glandiformis (equivalent to Halosaccion glandiforme) are designated to guarantee their unambiguous use and to stabilize the nomenclature.
Since the late 19th century, studies of the genus Porphyra sensu lato (Bangiales, Rhodophyta) have revealed a broad spectrum of life history strategies and reproductive modes. These variations are often interpreted as adaptive responses to the selective pressures imposed by spatially and temporally heterogeneous environments. However, the dynamics and prevalence of sexual versus asexual reproduction in natural populations remain poorly understood and insufficiently documented. In this study, we investigated the spatio-temporal variation in reproductive strategies of Porphyra umbilicalis, an emerging target species for aquaculture in the Northeast Atlantic, across a broad European range. Through microscopic examination and tracking the germination of spores released from fertile individuals in multiple populations, four main patterns were identified: (1) clear geographic structuring of reproductive strategies, with asexual reproduction prevailing in the Southern Bight of the North Sea and English Channel, and sexual populations more common in the South European Atlantic Shelf and Celtic Seas; (2) persistent dominance of asexual reproduction in populations with mixed reproductive modes, with a seasonal increase in the frequency of sexually reproductive individuals during winter; (3) microhabitat partitioning within the high intertidal zone, with asexual individuals occupying uppermost elevations and sexual individuals concentrated below, indicating ecologically driven niche differentiation; and (4) no consistent link between thallus size and reproductive mode, although sexual individuals were significantly larger during winter and spring. Collectively, these findings illustrate how environmental gradients shape reproductive strategies in P. umbilicalis, and suggest that asexuality may confer adaptive advantages in marginal intertidal zones.
