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Even though seaweeds have been recognized as key players in the ocean-to-atmosphere transfer of iodine in other parts of the world, there is a complete lack of knowledge about iodine accumulation in seaweeds of the Arabian Gulf. Similarly, very little is known about fluorine in seaweeds, anywhere in the world. Given that the Arabian Gulf is of particular interest due to being an extreme environment, featuring some of the highest temperatures and salinities observed in any marine water body worldwide, this study endeavoured to conduct a preliminary survey of iodine and fluorine levels in 11 of the most common seaweed species in the region, supported by morphological and molecular (DNA barcode)-based identification. Iodine was determined by inductively-coupled plasma-mass spectrometry, while ion chromatography was employed for analysis of fluoride. Species surveyed included Iyengaria stellata, Padina boergesenii, Chondria sp.Dictyota dichotoma, Colpomenia sinuosa, Feldmannia indica,Codium papillatum, Sargassum ilicifolium, S. ilicifolium var. acaraeocarpum, Sargassum asperifolium and Sargassum aquifolium. The findings of S. ilicifolium and S. ilicifolium var. acaraeocarpum reported here are new records both for Kuwait and the Arabian Gulf. P. boergesenii and D. dichotoma are new records for Kuwait. [ABSTRACT FROM AUTHOR]

This review article explores the state of DNA barcoding of macroalgae in the Mediterranean Sea. Data from the Barcode of Life Data System (BOLD) were utilised in conjunction with a thorough bibliographic review. Our findings indicate that from around 1124 records of algae in the Mediterranean Sea, only 114 species have been barcoded. We thus conclude that there are insufficient macroalgal genetic data from the Mediterranean and that this area would greatly benefit from studies involving DNA barcoding. Such research would contribute to resolving numerous questions about macroalgal systematics in the area and address queries related to biogeography, especially those concerned with non-indigenous species. It could also possibly result in the development and application of better, cost-effective biodiversity monitoring programmes emanating from UN conventions and EU Directives. One possible way of achieving this is to construct DNA libraries via sequencing and barcoding, subsequently enabling better cost-effective biodiversity monitoring through environmental DNA metabarcoding. [ABSTRACT FROM AUTHOR]

Iodine exists as a trace element in seawater, with total iodine being generally constant at about 0.45-0.55 µM. Almost all of this iodine occurs in two main forms: iodate and iodide. Iodate is the thermodynamically stable form under normal seawater conditions, and thus should be the only iodine-containing species in the water column. However, iodate concentrations are found to vary considerably, being generally greater at depth and lower at the surface, while iodide concentrations follow the reverse pattern, being anomalously accumulated in the euphotic zone and decreasing with depth. The fact that iodide concentrations follow a depth dependence corresponding to the euphotic zone suggests that biological activity is the source of the reduced iodine. Nonetheless, the nature and source of iodate reduction activity remains controversial. Here, using a combination of field and laboratory studies, we examine some of the questions raised in our and other previous studies, and seek further correlations between changes in iodine speciation and the presence of marine macro- and microalgae. The present results indicate that microalgal growth per se does not seem to be responsible for the reduction of iodate to iodide. However, there is some support for the hypothesis that iodate reduction can occur due to release of cellular reducing agents that accompany cell senescence during phytoplankton bloom declines. In addition, support is given to the concept that macroalgal species such as giant kelp (Macrocystis pyrifera) can take up both iodide and iodate from seawater (albeit on a slower time scale). We propose a mechanism whereby iodate is reduced to iodide at the cell surface by cell surface reductases and is taken up directly as such without reentering the bulk solution. [ABSTRACT FROM AUTHOR]

Culture isolates of the genus Hypoglossum (Delesseriaceae, Rhodophyta) were obtained and their development and morphological structure over many years were followed in the laboratory. Molecular data (rbcL, large subunit ribosomal DNA, and cytochrome c oxidase subunit I) were obtained from these strains and evidence presented to recognize the new species: Hypoglossum sabahense from Sabah, Malaysia. Because various aspects of morphology in culture specimens differ significantly from types based on field specimens we have to rely mainly on the molecular criteria in ascribing a new taxonomic name here. This also is complicated by the major lack of molecular phylogenetic evidence for Hypoglossum and other Delesseriaceae. The 'Germling Emergence Method' and 'serendipity' are proving valuable in discovering significant new taxa from laboratory cultures which otherwise might never be known. [ABSTRACT FROM AUTHOR]

Macrocystis pyrifera and Lessonia spicata are economically and ecologically relevant brown seaweeds that recently have been classified as members of two separated families within Laminariales (kelps). Here we describe for the first time the Macrocystis pyrifera x Lessonia spicata hybridization in the wild (Chiloe Island, Southeastern Pacific), where populations of the two parents exist sympatrically. Externally, this hybrid exhibited typical features of its parents M. pyrifera (cylindrical and flexible distal stipes, serrate frond margins and presence of sporophylls) and L. spicata (rigid and flat main stipe and first bifurcation), as well as intermediate features between them (thick unfused haptera in the holdfast). Histological sections revealed the prevalence of mucilage ducts within stipes and fronds (absent in Lessonia) and fully developed unilocular sporangia in the sporophylls. Molecular analyses confirmed the presence of the two parental genotypes for ITS1 nrDNA and the M. pyrifera genotype for two predominantly maternally inherited cytoplasmic markers (COI and rbcLS spacer) in the tissue of the hybrid. A metabolome-wide approach revealed that this hybrid is more chemically reminiscent to M. pyrifera. Nevertheless, several hits were identified as Lessonia exclusive or more remarkably, not present in any of the parent. Meiospores developed into apparently fertile gametophytes, which gave rise to F1 sporophytes that reached several millimeters before suddenly dying. In-vitro reciprocal crossing of Mar Brava gametophytes from both species revealed that although it is rare, interfamilial hybridization between the two species is possible but mostly overcome by pseudogamy of female gametophytes. [ABSTRACT FROM AUTHOR]

Very little is known about the marine macroalgae of artificial reefs—especially in the North Atlantic—despite the growing number and extent of man-made structures in the sea, and even though seaweed communities have paramount importance as primary producers, but also as feeding, reproductive and nursery grounds in coastal ecosystems. This paper explores the macroalgal diversity of a large system of artificial reefs in Loch Linnhe, on the west coast of Scotland, in a quantitative and qualitative study based on diving surveys and correlates the observations with the prevalent abiotic factors. The study was conducted in order to test the hypothesis that artificial reefs can enhance seaweed habitats—in particular, for kelps—and that there is a clear correlation with substrate type. While the reef is home to a large range of biota and abundance of early-successional species of turf and bushy macroalgae, totalling 56 taxa and with Delesseria sanguinea as the dominant species, canopy-forming perennial kelp species are conspicuously relatively rare. Macroalgal vegetation is explored in correlation with reef geometry/geography and depth. Statistical analysis shows benthic communities were strongly affected by substrate type, with turf algae and invertebrates dominating the artificial reefs, while bushy algae dominate the natural ones. Common macroinvertebrates associated with the phytobenthic communities are assessed qualitatively. [ABSTRACT FROM AUTHOR]

Despite its paramount role in the functioning of coastal ecosystems, relatively little is known about halogen metabolism in giant kelp ( Macrocystis pyrifera ). This is an important shortcoming given the potential implications for marine and atmospheric chemical processes in the wide distribution range of Macrocystis . The work presented here constitutes the first in depth investigation of the uptake, efflux, and of the physiological function of iodide in this important kelp species. Iodide uptake and efflux rates were measured in adult sporophytes of Macrocystis under normal and stressed (exogenous hydrogen peroxide and an elicitor-triggered oxidative burst) conditions. Kelp tissue took up iodide according to Michaelis-Menten type kinetics when incubated in seawater enriched with various concentrations of iodide. Upon the addition of exogenous hydrogen peroxide, simulating oxidative stress, a marked efflux of iodide occurred. In situ generation of hydrogen peroxide was elicited in Macrocystis upon the addition of oligomeric degradation products of alginate as well as arachidonic acid and methyl jasmonate constituting a defensive oxidative burst that could be linked to iodine accumulation. H 2 O 2 was detected at the single cell level using dichlorohydrofluorescein diacetate, a fluorogenic probe capable of detecting intracellular H 2 O 2 . When assayed for vanadium haloperoxidase activity, several bromoperoxidase isoforms were detected as well as a single iodoperoxidase. Altogether, the results of this study show that Macrocystis has an elaborate iodine metabolism, which is likely significant for impacting iodine speciation in seawater around kelp beds and for volatile halogen emissions into the coastal atmosphere. [ABSTRACT FROM AUTHOR]

Chytridiomycota, often referred to as chytrids, can be virulent parasites with the potential to inflict mass mortalities on hosts, causing e.g. changes in phytoplankton size distributions and succession, and the delay or suppression of bloom events. Molecular environmental surveys have revealed an unexpectedly large diversity of chytrids across a wide range of aquatic ecosystems worldwide. As a result, scientific interest towards fungal parasites of phytoplankton has been gaining momentum in the past few years. Yet, we still know little about the ecology of chytrids, their life cycles, phylogeny, host specificity and range. Information on the contribution of chytrids to trophic interactions, as well as co-evolutionary feedbacks of fungal parasitism on host populations is also limited. This paper synthesizes ideas stressing the multifaceted biological relevance of phytoplankton chytridiomycosis, resulting from discussions among an international team of chytrid researchers. It presents our view on the most pressing research needs for promoting the integration of chytrid fungi into aquatic ecology. [ABSTRACT FROM AUTHOR]

The heteronemertine Parborlasia corrugatus contains a cytolytic protein, parborlysin, which after extensive purification was found by Edman sequencing to be a mixture of several homologues. To investigate this microheterogeneity and enable the analysis of single toxins, we have obtained seven parborlysin isoform genes from P. corrugatus collected in Antarctica. Total RNA was isolated from the homogenized head region and parborlysin genes were identified from a cDNA library using degenerate primers. The translated sequences reveal that the isoforms are ∼10 kDa basic (pI∼10) proteins of which all but one harbour six cysteine residues. We generated a model of the three dimensional structure of parborlysins, which suggests that they are composed of five alpha-helical segments that include large, exposed hydrophobic surfaces. Finally, we constructed plasmids and inserted them into Escherichia coli to obtain overexpressed amino- or carboxy-terminal polyhistidine-tagged parborlysin isoforms fused to the third domain of the E. coli periplasmic-protein TolA to facilitate toxin isolation. One of the isoforms adversely affected growth in the E. coli expressing it. Although we succeeded in isolating one of the recombinant parborlysin constructs, it lacked haemolytic activity. [ABSTRACT FROM AUTHOR]

To identify cryptic stages of marine brown macroalgae present in the 'bank of microscopic forms', we incubated natural substrata of different geographical origins and isolated emerging Phaeophyceae into clonal cultures. A total of 431 clones were subsequently identified by barcoding using 5′-COI. A proportion of 98% of the isolates belonged to the Ectocarpales. The distribution of pairwise genetic distances revealed a K2P divergence of 1.8% as species-level cut-off. Using this threshold, the samples were ascribed to 83 different species, 39 (47%) of which were identified through reference sequences or morphology. In the Ectocarpaceae, 16 lineages of Ectocarpus fulfilled the barcode criterion for different species, while three putative new species were detected. In the Chordariaceae, numerous microthalli were microstages of known macroscopic taxa. A separate cluster contained Hecatonema maculans and other microscopic species. Taxa traditionally classified in Acinetosporaceae were split in two species-rich groups containing Pylaiella and Hincksia in one and Acinetospora in the other. Feldmannia species were present in both clusters. The present study shows that the germling emergence method is suited to reveal the diversity of hidden life-history stages, albeit with a bias towards early successional species. [ABSTRACT FROM AUTHOR]

Although the iron uptake and storage mechanisms of terrestrial/higher plants have been well studied, the corresponding systems in marine algae have received far less attention. Studies have shown that while some species of unicellular algae utilize unique mechanisms of iron uptake, many acquire iron through the same general mechanisms as higher plants. In contrast, the iron acquisition strategies of the multicellular macroalgae remain largely unknown. This is especially surprising since many of these organisms represent important ecological and evolutionary niches in the coastal marine environment. It has been well established in both laboratory and environmentally derived samples, that a large amount of iron can be ‘non-specifically’ adsorbed to the surface of marine algae. While this phenomenon is widely recognized and has prompted the development of experimental protocols to eliminate its contribution to iron uptake studies, its potential biological significance as a concentrated iron source for marine algae is only now being recognized. This study used an interdisciplinary array of techniques to explore the nature of the extensive and powerful iron binding on the surface of both laboratory and environmental samples of the marine brown alga Ectocarpus siliculosus and shows that some of this surface-bound iron is eventually internalized. It is proposed that the surface-binding properties of E. siliculosus allow it to function as a quasibiological metal ion ‘buffer’, allowing iron uptake under the widely varying external iron concentrations found in coastal marine environments. [ABSTRACT FROM PUBLISHER]

Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood, with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins, while strategy II plants utilize high-affinity, iron-specific, binding compounds called phytosiderophores. In contrast, little is known about the corresponding systems in marine, plant-like lineages, particularly those of multicellular algae (seaweeds). Herein the first study of the iron uptake and storage mechanisms in the brown alga Ectocarpus siliculosus is reported. Genomic data suggest that Ectocarpus may use a strategy I approach. Short-term radio-iron uptake studies verified that iron is taken up by Ectocarpus in a time- and concentration-dependent manner consistent with an active transport process. Upon long-term exposure to 57Fe, two metabolites have been identified using a combination of Mössbauer and X-ray absorption spectroscopies. These include an iron–sulphur cluster accounting for ∼26% of the total intracellular iron pool and a second component with spectra typical of a polymeric (Fe3+O6) system with parameters similar to the amorphous phosphorus-rich mineral core of bacterial and plant ferritins. This iron metabolite accounts for ∼74% of the cellular iron pool and suggests that Ectocarpus contains a non-ferritin but mineral-based iron storage pool. [ABSTRACT FROM AUTHOR]

Background: DNA barcoding offers an efficient way to determine species identification and to measure biodiversity. For dinoflagellates, an ancient alveolate group of about 2000 described extant species, DNA barcoding studies have revealed large amounts of unrecognized species diversity, most of which is not represented in culture collections. To date, two mitochondrial gene markers, Cytochrome Oxidase I (COI) and Cytochrome b oxidase (COB), have been used to assess DNA barcoding in dinoflagellates, and both failed to amplify all taxa and suffered from low resolution. Nevertheless, both genes yielded many examples of morphospecies showing cryptic speciation and morphologically distinct named species being genetically similar, highlighting the need for a common marker. For example, a large number of cultured Symbiodinium strains have neither taxonomic identification, nor a common measure of diversity that can be used to compare this genus to other dinoflagellates. Methodology/Principal Findings: The purpose of this study was to evaluate the Internal Transcribed Spacer units 1 and 2 (ITS) of the rDNA operon, as a high resolution marker for distinguishing species dinoflagellates in culture. In our study, from 78 different species, the ITS barcode clearly differentiated species from genera and could identify 96% of strains to a known species or sub-genus grouping. 8.3% showed evidence of being cryptic species. A quarter of strains identified had no previous species identification. The greatest levels of hidden biodiversity came from Scrippsiella and the Pfiesteriaceae family, whilst Heterocapsa strains showed a high level of mismatch to their given species name. Conclusions/Significance: The ITS marker was successful in confirming species, revealing hidden diversity in culture collections. This marker, however, may have limited use for environmental barcoding due to paralogues, the potential for unidentifiable chimaeras and priming across taxa. In these cases ITS would serve well in combination with other markers or for specific taxon studies. [ABSTRACT FROM AUTHOR]

Background: Dinoflagellates are an ecologically important group of protists with important functions as primary producers, coral symbionts and in toxic red tides. Although widely studied, the natural diversity of dinoflagellates is not well known. DNA barcoding has been utilized successfully for many protist groups. We used this approach to systematically sample known "species", as a reference to measure the natural diversity in three marine environments. Methodology/Principal Findings: In this study, we assembled a large cytochrome c oxidase 1 (COI) barcode database from 8 public algal culture collections plus 3 private collections worldwide resulting in 336 individual barcodes linked to specific cultures. We demonstrate that COI can identify to the species level in 15 dinoflagellate genera, generally in agreement with existing species names. Exceptions were found in species belonging to genera that were generally already known to be taxonomically challenging, such as Alexandrium or Symbiodinium. Using this barcode database as a baseline for cultured dinoflagellate diversity, we investigated the natural diversity in three diverse marine environments (Northeast Pacific, Northwest Atlantic, and Caribbean), including an evaluation of single-cell barcoding to identify uncultivated groups. From all three environments, the great majority of barcodes were not represented by any known cultured dinoflagellate, and we also observed an explosion in the diversity of genera that previously contained a modest number of known species, belonging to Kareniaceae. In total, 91.5% of non-identical environmental barcodes represent distinct species, but only 51 out of 603 unique environmental barcodes could be linked to cultured species using a conservative cut-off based on distances between cultured species. Conclusions/Significance: COI barcoding was successful in identifying species from 70% of cultured genera. When applied to environmental samples, it revealed a massive amount of natural diversity in dinoflagellates. This highlights the extent to which we underestimate microbial diversity in the environment. [ABSTRACT FROM AUTHOR]

Marine microalgae support world fisheries production and influence climate through various mechanisms. They are also responsible for harmful blooms that adversely impact coastal ecosystems and economies. Optimal growth and survival of many bloom-forming microalgae, including climatically important dinoflagellates and coccolithophores, requires the close association of specific bacterial species, but the reasons for these associations are unknown. Here, we report that several clades of Marinobacter ubiquitously found in close association with dinoflagellates and coccolithophores produce an unusual lower-affinity dicitrate siderophore, vibrioferrin (VF). Fe-VF chelates undergo photolysis at rates that are 10-20 times higher than siderophores produced by free-living marine bacteria, and unlike the latter, the VF photoproduct has no measurable affinity for iron. While both an algal-associated bacterium and a representative dinoflagellate partner, ScrippsielIa trochoidea, used iron from Fe-VF chelates in the dark, in situ photolysis of the chelates in the presence of attenuated sunlight increased bacterial iron uptake by 70% and algal uptake by >20-fold. These results suggest that the bacteria promote algal assimilation of iron by facilitating photochemical redox cycling of this critical nutrient. Also, binary culture experiments and genomic evidence suggest that the algal cells release organic molecules that are used by the bacteria for growth. Such mutualistic sharing of iron and fixed carbon has important implications toward our understanding of the close beneficial interactions between marine bacteria and phytoplankton, and the effect of these interactions on algal blooms and climate. [ABSTRACT FROM AUTHOR]

The targets of heavy metal (here Cu2+ and Zn2+ ) attack on the photosynthetic apparatus of algae belonging to different phyla were investigated. Experiments with the green alga Scenedesmus quadricauda confirmed previous findings that according to the irradiance level two different phenomena occur, which were further characterized by specific changes in several photosynthetic parameters. The reaction occurring under low irradiance (shade reaction ) is characterized by heavy metal substitution of Mg2+ in chl molecules bound predominantly in the light harvesting complex II of Chlorophyta (LHC II). Under high irradiance (sun reaction ) the LHC II chls are inaccessible to substitution and the damage occurs in the PSII reaction center instead. Algae with antenna proteins other than the LHC II did not show the two types of heavy metal attack at different irradiances. In red algae (Antithamnion plumula) , low Cu2+ concentrations induced the sun reaction even at very low irradiance. In brown algae (Ectocarpus siliculosus ) the shade reaction occurred even in saturating irradiance. These results also indicate that despite some similarity in their features, the primary step of the sun reaction and photoinhibition is different. [ABSTRACT FROM AUTHOR]

Kelp (Laminaria digitata) uses iodide as a unique inorganic antioxidant to protect its surface and apoplastic space against reactive oxygen species such as ozone, hydrogen peroxide and superoxide, with implications for atmospheric and marine chemistry as well as regional climatic processes. If kelp is covered by seawater, this results in iodide leaching into surrounding sea water. In this study, the influence of the kelps Laminaria digitata , L. hyperborea , L. ochroleuca and Saccharina latissima on iodine speciation chemistry was explored at two sites in Oban (Argyll, Scotland) and Roscoff (Brittany, France) based on diver-operated in situ sampling. Seawater samples were subsequently analysed voltammetrically, accompanied by determination of extractable iodine concentrations in the tissues of the thalli surveyed by ICP-MS. The main result is that iodide concentrations in the vicinity of kelp thalli are strongly enhanced, especially at low tide, while iodate concentrations are decreased in comparison to open coastal water and open ocean concentrations. Using diver-operated in situ sampling with seawater samples subsequently analysed voltammetrically, this study finds that iodide levels in the vicinity of kelp thalli are strongly enhanced, especially at low tide, while iodate levels are decreased in comparison to open coastal water and open ocean concentrations. [Display omitted] • This study uses a new diver-operated in situ syringe sampling technique. • Samples analysed voltammetrically. • Iodide levels around kelp thalli are strongly enhanced, especially at low tide. • In contrast, iodate levels are decreased in comparison to open waters. [ABSTRACT FROM AUTHOR]

Iron-chelating siderophores such as aerobactin and petrobactin are produced by marine bacteria to sequester iron under low iron stress. Those that contain a citrate moiety undergo light-catalyzed ligand-to-metal charge transfer, inducing decarboxylation and formation of photoproducts. In this work, we employed density functional theory to obtain the optimized geometries and determine the relative energies and geometric parameters of different configurations of Fe(III)-coordinated aerobactin, petrobactin, and their photoproducts. Time-dependent density functional theory was then used to compute the UV-Vis absorption spectra of these species, and the comparison against experimental spectra further elucidated the structural configurations most likely to be adopted by these compounds. Frequency calculations provided Fe-O force constants on the same order as other siderophores. The relative energies and predicted spectra support the cis-cis C-fac configuration for ferric aerobactin and the cis-trans C-mer configuration for its photoproduct, while only mild support is found for specific configurations of the ferric petrobactin structures (meta-mer and meta-fac for the precursor, cis-cis para-fac for the photoproduct). The predicted ferric petrobactin spectra are found to be fairly insensitive to the configuration of the ferric complex., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Iron is accumulated symplastically in kelp in a non-ferritin core that seems to be a general feature of brown algae. Microprobe studies show that Fe binding depends on tissue type. The sea is generally an iron-poor environment and brown algae were recognized in recent years for having a unique, ferritin-free iron storage system. Kelp (Laminaria digitata) and the filamentous brown alga Ectocarpus siliculosus were investigated using X-ray microprobe imaging and nanoprobe X-ray fluorescence tomography to explore the localization of iron, arsenic, strontium, and zinc, and micro-X-ray absorption near-edge structure (μXANES) to study Fe binding. Fe distribution in frozen hydrated environmental samples of both algae shows higher accumulation in the cortex with symplastic subcellular localization. This should be seen in the context of recent ultrastructural insight by cryofixation-freeze substitution that found a new type of cisternae that may have a storage function but differs from the apoplastic Fe accumulation found by conventional chemical fixation. Zn distribution co-localizes with Fe in E. siliculosus, whereas it is chiefly located in the L. digitata medulla, which is similar to As and Sr. Both As and Sr are mostly found at the cell wall of both algae. XANES spectra indicate that Fe in L. digitata is stored in a mineral non-ferritin core, due to the lack of ferritin-encoding genes. We show that the L. digitata cortex contains mostly a ferritin-like mineral, while the meristoderm may include an additional component., (© The Author(s) 2023. Published by Oxford University Press.)

This study explores key features of bromine and iodine metabolism in the filamentous brown alga and genomics model Ectocarpus siliculosus. Both elements are accumulated in Ectocarpus, albeit at much lower concentration factors (2-3 orders of magnitude for iodine, and < 1 order of magnitude for bromine) than e.g. in the kelp Laminaria digitata. Iodide competitively reduces the accumulation of bromide. Both iodide and bromide are accumulated in the cell wall (apoplast) of Ectocarpus, with minor amounts of bromine also detectable in the cytosol. Ectocarpus emits a range of volatile halogenated compounds, the most prominent of which by far is methyl iodide. Interestingly, biosynthesis of this compound cannot be accounted for by vanadium haloperoxidase since the latter have not been found to catalyze direct halogenation of an unactivated methyl group or hydrocarbon so a methyl halide transferase-type production mechanism is proposed.

Deep-water kelps are little-known large brown algae occurring close to the lower limit of photosynthetic life in the sea. This study compares historical and recent records of the deep-water Mediterranean kelp Laminaria rodriguezii in the Adriatic Sea. Historical records include data from herbarium collections and trawling fishery expeditions in the mid-twentieth century, while recent data comprise records of the last 17 years from MEDITS expeditions, ROV surveys of historical kelp locations, benthic surveys and records by fishermen. Altogether, these findings demonstrate that the Adriatic population of L. rodriguezii has suffered a decline of more than 85 % of its historical range and is now present only around the small offshore island of Palagruža. Bottom trawling activities are presumably responsible for the disappearance elsewhere. We propose to classify L. rodriguezii as "Endangered" in the Adriatic Sea under IUCN criteria B1ab(i,iii,iv), ver 3.1. Oceanographic characteristics of the habitat suggest that besides high water transparency, presence of North Adriatic Dense Water with both strong currents and stable low temperatures of around 14 °C are essential oceanographic factors for the development of L. rodriguezii in the Central Adriatic. The origin of cold water thus differs from that at upwelling sites permitting populations of tropical deep-water kelps. The phylogenetic position of L. rodriguezii is so far unknown. DNA sequences from nuclear and cytoplasmic markers of two thalli from Croatia and the western Mediterranean confirmed that L. rodriguezii is a member of the Laminariaceae and most closely related to L. ochroleuca , L. pallida and the Brazilian deep-water kelp L.   abyssalis .

A new geographic record of the oomycete Olpidiopsis feldmanni infecting the tetrasporophytic stage of the red alga Asparagopsis sp. from the Adriatic Sea, confirmed through morphological identification, allowed us to expand previous observations of this organism. Ultrastructural investigations of environmental material showed a large central vacuole and a cell wall thicker than previously reported from other basal oomycete pathogens of algae. Phylogenetic analysis closely associates O. feldmanni to O. bostrychiae concurrent with structural observations. This constitutes the first genetic characterisation of an Olpidiopsis species that was initially described before 1960, adding to the genetic data of 3 other marine Olpidiopsis species established and genetically characterised in the last 2 decades. The paper discusses concurrences of the ultrastructural observations made here and in previous studies of the marine Olpidiopsis species with those made on the freshwater species.

The metabolism of bromine in marine brown algae remains poorly understood. This contrasts with the recent finding that the accumulation of iodide in the brown alga Laminaria serves the provision of an inorganic antioxidant - the first case documented from a living system. The aim of this study was to use an interdisciplinary array of techniques to study the chemical speciation, transformation, and function of bromine in Laminaria and to investigate the link between bromine and iodine metabolism, in particular in the antioxidant context. First, bromine and iodine levels in different Laminaria tissues were compared by inductively coupled plasma MS. Using in vivo X-ray absorption spectroscopy, it was found that, similarly to iodine, bromine is predominantly present in this alga in the form of bromide, albeit at lower concentrations, and that it shows similar behaviour upon oxidative stress. However, from a thermodynamic and kinetic standpoint, supported by in vitro and reconstituted in vivo assays, bromide is less suitable than iodide as an antioxidant against most reactive oxygen species except superoxide, possibly explaining why kelps prefer to accumulate iodide. This constitutes the first-ever study exploring the potential antioxidant function of bromide in a living system and other potential physiological roles. Given the tissue-specific differences observed in the content and speciation of bromine, it is concluded that the bromide uptake mechanism is different from the vanadium iodoperoxidase-mediated uptake of iodide in L. digitata and that its function is likely to be complementary to the iodide antioxidant system for detoxifying superoxide.

For the Mediterranean Sea, and indeed most of the world's oceans, the biodiversity and biogeography of eukaryotic pathogens infecting marine macroalgae remains poorly known, yet their ecological impact is probably significant. Based on 2 sampling campaigns on the Greek island of Lesvos in 2009 and 1 in northern Greece in 2012, this study provides first records of 3 intracellular eukaryotic pathogens infecting filamentous brown algae at these locations: Eurychasma dicksonii, Anisolpidium sphacellarum, and A. ectocarpii. Field and microscopic observations of the 3 pathogens are complemented by the first E. dicksonii large subunit ribosomal RNA (LSU rRNA) gene sequence analyses of isolates from Lesvos and other parts of the world. The latter highlights the monophyly of E. dicksonii worldwide and confirms the basal position of this pathogen within the oomycete lineage (Peronosporomycotina). The results of this study strongly support the notion that the geographic distribution of the relatively few eukaryotic seaweed pathogens is probably much larger than previously thought and that many of the world's marine bioregions remain seriously undersampled and understudied in this respect.

Iodine was discovered as a novel element in 1811 during the Napoleonic Wars. To celebrate the bicentennial anniversary of this event we reflect on the history and highlight the many facets of iodine research that have evolved since its discovery. Iodine has an impact on many aspects of life on Earth as well as on human civilization. It is accumulated in high concentrations by marine algae, which are the origin of strong iodine fluxes into the coastal atmosphere which influence climatic processes, and dissolved iodine is considered a biophilic element in marine sediments. Iodine is central to thyroid function in vertebrates, with paramount implications for human health. Iodine can exist in a wide range of oxidation states and it features a diverse supramolecular chemistry. Iodine is amenable to several analytical techniques, and iodine compounds have found widespread use in organic synthesis. Elemental iodine is produced on an industrial scale and has found a wide range of applications in innovative materials, including semiconductors--in particular, in solar cells., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The amphibious water plant Crassula helmsii is an invasive copper (Cu)-tolerant neophyte in Europe. It now turned out to accumulate Cu up to more than 9,000 ppm in its shoots at 10 microm (=0.6 ppm) Cu(2+) in the nutrient solution, indicating that it is a Cu hyperaccumulator. We investigated uptake, binding environment, and toxicity of Cu in this plant under emerged and submerged conditions. Extended x-ray absorption fine structure measurements on frozen-hydrated samples revealed that Cu was bound almost exclusively by oxygen ligands, likely organic acids, and not any sulfur ligands. Despite significant differences in photosynthesis biochemistry and biophysics between emerged and submerged plants, no differences in Cu ligands were found. While measurements of tissue pH confirmed the diurnal acid cycle typical for Crassulacean acid metabolism, Delta(13)C measurements showed values typical for regular C3 photosynthesis. Cu-induced inhibition of photosynthesis mainly affected the photosystem II (PSII) reaction center, but with some unusual features. Most obviously, the degree of light saturation of electron transport increased during Cu stress, while maximal dark-adapted PSII quantum yield did not change and light-adapted quantum yield of PSII photochemistry decreased particularly in the first 50 s after onset of actinic irradiance. This combination of changes, which were strongest in submerged cultures, shows a decreasing number of functional reaction centers relative to the antenna in a system with high antenna connectivity. Nonphotochemical quenching, in contrast, was modified by Cu mainly in emerged cultures. Pigment concentrations in stressed plants strongly decreased, but no changes in their ratios occurred, indicating that cells either survived intact or died and bleached quickly.

On the occasion of the 200th anniversary of the discovery of boron, we review the oceanic biogeochemistry of boron as well as suitable analytical techniques for its determination. This overview includes aspects of biogeochemistry including geochemical stable isotope variations, uptake, transport, storage, nutritional value, toxicity, and distribution within biological materials, providing a framework for discussion of the role of boron in marine organisms, which remains largely enigmatic.

Brown algae of the Laminariales (kelps) are the strongest accumulators of iodine among living organisms. They represent a major pump in the global biogeochemical cycle of iodine and, in particular, the major source of iodocarbons in the coastal atmosphere. Nevertheless, the chemical state and biological significance of accumulated iodine have remained unknown to this date. Using x-ray absorption spectroscopy, we show that the accumulated form is iodide, which readily scavenges a variety of reactive oxygen species (ROS). We propose here that its biological role is that of an inorganic antioxidant, the first to be described in a living system. Upon oxidative stress, iodide is effluxed. On the thallus surface and in the apoplast, iodide detoxifies both aqueous oxidants and ozone, the latter resulting in the release of high levels of molecular iodine and the consequent formation of hygroscopic iodine oxides leading to particles, which are precursors to cloud condensation nuclei. In a complementary set of experiments using a heterologous system, iodide was found to effectively scavenge ROS in human blood cells.

The cyanobacterium Tychonema sp. produces the new cyclic hexapeptides brunsvicamide A-C (1-3). Brunsvicamide B (2) and C (3) selectively inhibit the Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB), a potential drug target for tuberculosis therapy for which no inhibitors are known to date. Brunsvicamide C contains an N-methylated N'-formylkynurenine moiety, a unique structural motif in cyclic peptides. The new peptides are related to the sponge-derived mozamides, supporting the suggestion that secondary metabolites of certain marine invertebrates are produced by associated microorganisms. Thus, microorganisms phylogenetically related to symbionts of marine invertebrates can be judged as a means to supply "marine-like" compounds for drug development.

This study provides evidence that bacterial lipopolysaccharides can be strong triggers of early events of defence reactions in the brown algal kelp Laminaria digitata, constituting the first report of a biological activity of this class of macromolecules in a marine alga. The early events include an oxidative burst, release of free saturated and unsaturated fatty acids (FFAs) and accumulation of oxylipins such as 13-hydroxyoctadecatrienoic acid and 15-hydroxyeicosapentaenoic acid. The formation of reactive oxygen species can be inhibited by diphenylene iodonium, suggesting that the source is an NAD(P)H oxidase and is similar to the oxidative burst in neutrophils and terrestrial plants. In addition and besides triggering an oxidative burst, the hypolipidemic drug clofibrate also induces the release of FFAs, to a lesser extent than lipopolysaccharides, but it does not induce oxylipin production. Other strong inducers of the oxidative burst in Laminaria such as oligoguluronates could not induce the release of FFAs nor oxylipin production. These results suggest that different signalling pathways are involved in the induction of the oxidative burst and oxylipin production.

Forty-five species of brown algae (Phaeophyceae) were surveyed for their capacity to respond by an oxidative burst to challenges with alginate oligosaccharides. Intertidal frondose brown algae (Fucales) constitutively released high quantities of peroxide. The capacity to recognize oligoguluronates and to react with an oxidative burst was confined to alginate-rich taxa with complex thallus morphology, epitomized by the sporophytes of Laminariales. When kelp sporophytes were impaired in their capacity to perform an oxidative burst by the NAD(P)H oxidase inhibitor diphenylene iodonium, they were readily degraded by their bacterial epiflora. Thus, in these algae, the oxidative response is an essential element of natural resistance. We also report on the establishment of a well-defined experimental system for investigations on kelp immunity, with Laminaria digitata as the host and its phaeophycean endophyte, Laminariocolax tomentosoides, as the pathogen. We found that an alginate-triggered oxidative burst significantly induces resistance in Laminaria digitata against infection. From these findings we infer that oligoalginate signals are important cues in the interaction between laminarialean kelps and potential pathogens.