Red Alga Gracilaria Vermiculophylla Research Articles

Laboratory‐scale preparation of prostaglandins using acetone powder of the red alga Gracilaria vermiculophylla

SummaryThe red alga Gracilaria vermiculophylla is a prostaglandin (PG)‐producing macroalga. The alga is rich in polyunsaturated fatty acids with 20 carbon atoms, mainly arachidonic acid (AA), which is a precursor of PGs. The purpose of the present study was to analyze the ability of the red alga to produce PGs using acetone powder as the crude enzyme prepared from the alga. The acetone powder (250 mg) was incubated with different amounts of exogenous AA (0.1–4 mg). For the determination of PG contents, 5 μL of a sample solution (5 mL in water) consisting of acetone powder and AA was injected into the HPLC column. For PG analysis, an HPLC system connected with a mass spectrometer was used. Results of the study showed that the released PGs from incubation of acetone powder and AA consisted of PGE2, 15‐keto‐PGE2, 15‐hydroperoxy‐PGE2, PGA2, and PGF2α. The capability of the crude enzyme prepared from the red alga to produce PGs was affected by available oxygen and AA concentrations. The crude enzyme (250 mg) was capable of producing 164 and 141 μg of PGE2 and 15‐keto‐PGE2, respectively, from incubation with 250 μg of AA. This in vitro method could be a simple way to provide PGs in the laboratory.

Non-native red alga Gracilaria vermiculophylla compensates for seagrass loss as blue crab nursery habitat in the emerging Chesapeake Bay ecosystem.

Non-native species can become deleterious or potentially beneficial as components of novel ecosystems. The non-native red macroalga Gracilaria vermiculophylla may provide nursery habitat where eelgrass Zostera marina has been extirpated in Chesapeake Bay. A mensurative experiment was conducted monthly May–October 2013 and 2014 in the York River, Chesapeake Bay, to evaluate hypotheses that Gracilaria (1) can compensate for the loss of seagrass nurseries by colonizing habitats where seagrass has been eliminated by environmental stress, and (2) is utilized by juvenile blue crabs (Callinectes sapidus) as nursery habitat. We quantified Gracilaria presence, percent cover, and biomass as a function of region (upriver, midriver, and downriver) and seagrass presence or absence using stratified random sampling, 20-m transects, and 0.0625-m2 quadrats. Gracilaria volume was measured and converted to dry weight. Effects of the factors and covariates temperature, salinity, dissolved oxygen, month, and year were analyzed using generalized linear models. Juvenile blue crab density was quantified in summer 2013 using suction sampling in Gracilaria and seagrass. A model with the collective effect of region and seagrass presence or absence (downriver seagrass, downriver unvegetated bottom, midriver unvegetated bottom) best predicted Gracilaria abundance. Gracilaria presence, percent cover, and biomass were highest in downriver seagrass, followed by downriver unvegetated bottom, and then midriver unvegetated bottom, where seagrass has been extirpated, supporting hypothesis (1). Gracilaria did not occur upriver, likely due to a lack of recruitment. Seagrass and Gracilaria housed similar densities of juvenile blue crabs, supporting hypothesis (2). We estimated that a single 40-ha cove system with Gracilaria could house 200,000 juvenile crabs as would a single 2.4-ha seagrass bed. Consequently, the numerous midriver and downriver cove systems in the York River could support millions of young juvenile blue crabs and thereby compensate for the loss of seagrass in the river and in other areas of Chesapeake Bay. At present, Gracilaria has no widespread negative impacts on seagrass in the York River or most regions of Chesapeake Bay, likely because percent cover and biomass are not excessively high at present. We posit that Gracilaria has become an important alternative nursery habitat for the blue crab in Chesapeake Bay and can potentially mitigate impacts of climate change on seagrass nursery habitats.

High density cultivation and CO2 uptake by panel arrays of the macrophytic red alga Gracilaria vermiculophylla in a 100 L raceway pond

New approaches are needed for land-based cultivation of macrophytic red algae that reduce costly aeration requirements for biomass suspension and enable high-density cultivation. The goal of this study was to demonstrate the high-density cultivation of the carbohydrate-rich macrophytic red alga Gracilaria vermiculophylla on vertical arrays of panels deployed in an open channel raceway configuration similar to those developed for mass cultivation of microalgae. A clonal culture of G. vermiculophylla, consisting of branched, cylindrical thallus tissues of 8–10 cm length, was mechanically blended using a Waring blender into 2–3 cm fragments and then fluidically injected onto a 3 mm polypropylene mesh support. Immobilized G. vermiculophylla mesh panels were spaced 6.5 cm apart and aligned parallel to flowing seawater medium at nominal bulk velocity of 20 cm s−1 in a 100 L raceway pond of 20 cm liquid depth. This raceway was equipped with real-time measurement of CO2 concentration in the inlet and outlet gas for determination of CO2 uptake dynamics. Specific rates for CO2 uptake became saturated at 8000 ppm CO2. To match CO2 demand by the biomass under nutrient-replete conditions at 21 °C, the inlet gas CO2 was increased from 1000 to 4000 ppm (day 7–14), and then to 8000 ppm (day 14–23) at 0.010 L gas L−1 liquid min−1 gas flow. Over the 23 day cultivation, biomass on the panel increased by a factor of 48, with final biomass loading exceeding 10 kg FW m−2 panel area, and cumulative CO2 capture of 65%. The cumulative average areal productivity within the panel zone of the raceway exceeded 60 g AFDW m−2 day−1, and final biomass density nearing 7.2 g AFDW L−1 (47 g FW L−1) was achieved after 23 days. Overall, these outcomes demonstrate the potential for land-based raceway cultivation of clonal red macroalgae of present and future commercial significance.

Native tube-building polychaete prefers to anchor non-native alga over other macrophytes.

Novel facultative mutualisms that develop between native and non-native ecosystem engineers can lead to the retention of the non-native partner. In some cases, behavior plays an additional, but less understood, role in the development and persistence of mutualisms. In soft-sediment marine habitats along the western Atlantic, the native decorator worm Diopatra cuprea anchors the non-native red alga Gracilaria vermiculophylla to its tube cap in a mutualism. To understand whether the worm's usage of G. vermiculophylla could represent a preference, we first surveyed the species composition of macrophytes affixed to worm tube caps at three sites in coastal Virginia, USA using transect and quadrat sampling. These unmanipulated field surveys supported previous work revealing variable, but often high frequencies (31-98%) of D. cuprea decoration with G. vermiculophylla. We next used field manipulations and controlled laboratory experiments to test the consistency of individual D. cuprea decoration with G. vermiculophylla versus three common macrophytes (Ulva sp., Agardhiella sp., and Spartina alterniflora) found in our field surveys. Twenty-four hours after removing the worm's tube cap in the field, D. cuprea decoration was dominated by both G. vermiculophylla (39.6%) and S. alterniflora (25.9%). When provided a choice of macrophytes in the laboratory, individual D. cuprea consistently decorated with G. vermiculophylla (58.7%) over the other macrophytes, showing a preference for the non-native macrophyte. Our study suggests that preference can drive strong and steadfast interactions between native and non-native organisms, facilitating the latter's persistence and spread, change available habitat, and alter community interactions.

Immobilization and growth of clonal tissue fragments from the macrophytic red alga Gracilaria vermiculophylla on porous mesh panels

New approaches are needed to automate and intensify the cultivation of commercially important red macroalgae. For example, cultivation of Gracilaria vermiculophylla on vertically stacked panels, deployed in raceway circulation tanks or in the open ocean, may enable process intensification. A scalable process for panel inoculation is a first step toward this end. Clonal plantlets of G. vermiculophylla were mechanically blended (1000 rpm, 5 s) into tissue fragments of 2 cm nominal size, deposited on a 3-mm polypropylene mesh sheet, and then sprayed with a pressurized water jet at 4.5 bar in 0.1 s bursts with average velocity of 13 m s−1. The force of the water jet pushed the 1 mm diameter thallus tissue fragments into the mesh openings, securing the plantlet to the mesh support. Gracilaria vermiculophylla test panels (7 cm per side) were placed in an upright orientation, with rising air bubbles providing fluid motion over the panel surface. During cultivation at saturation light intensity in nutrient-replete medium, near-exponential growth was sustained over 42 days at a specific growth rate of 8–9% per day, identical to the freely suspended thallus tissues. The tissue fragments proliferated over the panel surface and extended outward from the panel surface, ultimately creating a loose mat of tissue nearly 8–10 cm in thickness and biomass loadings exceeding 3000 g FW per m2 of panel surface. The steps used to prepare the G. vermiculophylla panels can be automated, and dense arrays of stationary G. vermiculophylla panels cultivated under defined current flow offer future potential for process intensification.

Interactive effects of co-occurring anthropogenic stressors on the seagrass, Zostera noltei

Abstract Coastal ecosystems are subjected to multiple co-occurring anthropogenic stressors which potentially interact to produce complex impacts on the structure and functioning of biological communities. Seagrass meadows are among the most rapidly declining coastal habitats on Earth. In particular, high nutrient loadings, enhanced sedimentation and competition from blooming seaweeds, like the invasive red alga Gracilaria vermiculophylla, are claimed to be associated with this decline. In this study, we tested for individual and potential interactive impacts on the intertidal seagrass Zostera noltei of these three stressors using a factorial field experiment. We measured seagrass shoots density and biomass (both above and below ground seagrass biomass) as proxies of seagrass physical condition. We also examined changes in fauna assemblages. The study suggested that sediment loading had the most detrimental impacts on health of the seagrass meadows. The effect of seaweed addition was negative and denso-dependent. Deleterious effects of nutrient enrichment were less evident. Non-additive interactions were also noticeable for some of the structural traits measured. Particularly, nutrient enrichment changed the effect of the other stressors for some of the responses measured. The effect of the treatments was also perceptible in the associated fauna assemblages. The ubiquitous grazer Peringia ulvae was more abundant in treatments with sediment loading, but those sediment effects in the density of the small grazer were modulated by nutrient and seaweed addition levels. Finally, we suggest that more studies should test for synergistic effects of co-occurring stressors to better understand the direction and intensity of changes triggered by human activities in natural ecosystems.

Sulfurated diketopiperazines from an algicolous isolate of Trichoderma virens

Two new naturally occurring sulfurated diketopiperazines, dehydroxymethylbis(dethio)bis(methylthio)gliotoxin (1) and (3S,6R)-6-(para-hydroxybenzyl)-1,4-dimethyl-3,6-bis(methylthio)piperazine-2,5-dione (2), along with three known analogues (3–5) were isolated from the culture extract of Trichoderma virens Y13-3, obtained from the surface of the marine red alga Gracilaria vermiculophylla. The structures and relative configurations of 1 and 2 were determined by extensive 1D/2D NMR, MS, and IR spectroscopic data, and their absolute configurations were established by analysis of ECD spectra aided by quantum chemical calculations. Compounds 1–5 were evaluated for the inhibition of some marine-derived organisms.

Trichorenins A-C, Algicidal Tetracyclic Metabolites from the Marine-Alga-Epiphytic Fungus Trichoderma virens Y13-3.

Three novel polyketide-like metabolites, trichorenins A-C (1-3), with a unique tetracyclic carbon skeleton were obtained from the culture of Trichoderma virens Y13-3, an epiphyte of the marine red alga Gracilaria vermiculophylla. Their structures and relative configurations were established by analysis of 1D/2D NMR and MS data, and their absolute configurations were unequivocally assigned by X-ray diffraction and ECD spectra aided by quantum chemical calculations. Compounds 1-3 exhibited potent inhibition against two marine phytoplankton species, Chattonella marina and Karlodinium veneficum.

In situ common garden assays demonstrate increased defense against natural fouling in non-native populations of the red seaweed Gracilaria vermiculophylla

The susceptibility of native and non-native populations of the red alga Gracilaria vermiculophylla to fouling was compared in common garden experiments. Native and non-native algae were enclosed into dialysis membrane tubes, and the tubes were exposed to natural fouling. Fouling on the outside of the tubes was mediated by chemical compounds excreted by G. vermiculophylla that diffused through the membranes. Fouling pressure was significantly higher in the Kiel Fjord (non-native range) than in Akkeshi Bay (native range), but, at both sites, tubes containing non-native G. vermiculophylla were less fouled than those with native conspecifics. This is the first in situ evidence that susceptibility to fouling differs between native and non-native populations of an aquatic organism. The technique of enclosing organisms into dialysis tubes represents a simple, efficient and accurate way to test chemical antifouling defenses and could possibly be applied to other organisms.

Seaweed Competition: Ulva Sp. has the Potential to Produce the Betaine Lipid Diacylglyceryl-O-4'-(N,N,N,-Trimethyl) Homoserine (DGTS) in Order to Replace Phosphatidylcholine (PC) Under Phosphate-Limiting Conditions in the P-Limited Dutch Wadden Sea and Outcompete an Aggressive Non-Indigenous Gracilaria vermiculophylla Red Drift Algae Out of this Unique Unesco World Heritage Coastal Area

The present study tested in the Western Dutch Wadden Sea (WDW) UNESCO World Heritage Site why an on a global scale the aggressive non-indigenous red drift alga Gracilaria vermiculophylla didn’t succeed to overgrow the WDC. In such a multifaceted complex ecosystem like the dynamic WDC it seems like unraveling a Gordian knob in order to describe the inextricable relationship between this seaweed invader suppression and its (a) biotic environment. However, we succeeded at the molecular level to give a convincing reasoning at first grounded in the awareness of a since 1987 river Rhine-North-Sea-WDC severely Phosphorus (P) restricted ecosystem. Our ecological datasets gave via final DCA (Detrended Correspondence Analysis) awareness of the very compelling interaction between Ulva sp. and G.vermiculophylla. Based on LCMS-techniques we discovered that Ulva sp. have the advantage to use the biochemical pathway solely rarely observed in some euckaryotes- to have the potential to produce the betaine lipid diacylglyceryl-O-4’-(N,N,N,-trimethyl)homoserine (DGTS) which replaces the plant/seaweed cell wall structure phosphatidylcholine (PC) “lecithine” under phosphate-limiting growth conditions. Also we hope this lipidomics based compound DGTS can serve as an ecological biomarker in order to protect vulnerable ecosystems like the Wadden Sea (UNESCO World Heritage).

Anti‐epiphyte defences in the red seaweed Gracilaria vermiculophylla: non‐native algae are better defended than their native conspecifics

Summary Epibiosis in the marine environment is a stressor that may determine invasion success in introduced species. Previous comparisons showed resistance to epibionts can be higher in non‐native than in resident seaweed species, but we do not know whether it is an intrinsic trait of the non‐natives or it has been acquired during the invasion process. To elucidate this question, a comparison between native and non‐native populations of the same species is needed. Resistance against two groups of epiphytes was assessed in living thalli and in artificial substrata coated with surface extracts, both gained from four Asian (native) and four European (non‐native) populations of the red alga Gracilaria vermiculophylla. Two diatom species and two filamentous macroalgae were used as micro‐ and macro‐epiphytes, and one of each type was collected in Asia, while the other came from Europe. Laboratory assays were done in both distributional ranges of G. vermiculophylla and in different seasons. We used G. vermiculophylla from four populations in each range and used a fully crossed design with the factors (i) ‘Origin of Gracilaria’, (ii) ‘Origin of epiphytes’, (iii) ‘Season’ and (iv) ‘Solvent used for extraction’. Both groups of epiphytes, regardless of their origin, attached less to living thalli and to surface extracts from non‐native G. vermiculophylla. Fewer diatoms attached to hexane‐based extracts, while fewer Ceramium filaments settled on extracts gained with dichloromethane. Synthesis. Our results show for the first time that non‐native individuals of a marine organism are better defended against epiphytes than native conspecifics. Furthermore, we found evidence that at least a part of the defence is based on extractable secondary metabolites. We discuss several mechanisms that could explain the increased resistance to epiphytes in non‐native individuals, including the release from enemies in the non‐native range, which could lead to an increase in algal performance during the invasion process. We suggest that an enhanced defence against epiphytes after introduction is one reason for G. vermiculophylla's invasion success. Our observation may also apply to other basibiont–epibiont and host–enemy systems, including plant–plant, plant–animal and animal–animal interactions, in aquatic environments and could be a key feature of bioinvasions.

Comparative assessment for efficiency of isolation of arachidonic acid (20:4n-6) from various sources

Methods of arachidonic acid (AA) isolation from animal and vegetal natural sources are considered. Traditional raw material as the lipids of beef liver and alternative source as the red alga Gracilaria vermiculophylla are tested. The AA was isolated by a sequence of known techniques for concentration of polyunsaturated fatty acids: sedimentation of saturated fatty acids in the form of their lithium salts, iodo-lactonization, and high performance liquid chromatography. All these techniques were applied for isolation of AA from the beef liver lipids, where the AA content did not exceed 7.7 % of total lipids, and the yield of AA with purity of 98.76 % was 50.8 %. The AA content in the algae lipids was significantly higher (> 35 %), while the amount of n-3 polyunsaturated fatty acids was insignificant, so two techniques only were applied (sedimentation of lithium salts and liquid chromatography), and the yield of AA with purity of 97.60 % was 68.3 %. Thus, high-purity arachidonic acid could be isolated from the algae G. vermiculophylla using simple and reproducible procedure. Taking into account the high yield of AA, this method is economically feasible and is proposed for biochemical and medical researches.

Genetic diversity of the habitat-forming red alga Gracilaria vermiculophylla along Chinese coasts

As a habitat-forming species, the red alga Gracilaria vermiculophylla has been noted to play an essential role in shaping coastal marine communities and maintaining intertidal ecosystems along Chinese coasts. However, few studies have been conducted that analyze the genetic structure of the population and the distribution patterns of genetic variation. In this study, we compiled partial mitochondrial DNA cytochrome c oxidase subunit I gene (cox1) of 19 G. vermiculophylla populations (461 individuals) and performed phylogenetic analysis and population genetic surveys. A total of 461 mt-DNA cox1 sequences were obtained and edited into 641 bp, which contained 21 polymorphic sites and yielded 15 haplotypes. Phylogenetic inferences, haplotype networking, and principal coordinate analysis consistently indicated that G. vermiculophylla populations diverged into two groups: the northern group is comprised of specimens from the Yellow-Bohai Sea and the Shengsi Islands, while the southern group is comprised of specimens from six locations south to Xiamen, Fujian Province. Analysis of the molecular variance and Nei’s genetic distances indicated low genetic differentiation between populations in each group while group-level genetic divergence is comparable to the degree of subspecies differentiation. •研究报告• 782 生 物 多 样 性 Biodiversity Science 第 24 卷

Lipid Classes, Fatty Acid Composition, and Glycerolipid Molecular Species of the Red Alga <i>Gracilaria vermiculophylla</i>, a Prostaglandin-Producing Seaweed

The red alga Gracilaria vermiculophylla is a well-known producer of prostaglandins, such as PGE2 and PGF2α. In this study, the characteristics of glycerolipids as substrates of prostaglandin production were clarified, and the lipid classes, fatty acid composition, and glycerolipid molecular species were investigated in detail. The major lipid classes were monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), and sulfoquinovosyldiacylglycerol (SQDG), as well as phosphatidylcholine (PC), which accounted for 43.0% of the total lipid profile. Arachidonic acid (20:4n-6), a prostaglandin precursor, and palmitic acid (16:0) were the predominant fatty acids in the total lipid profile. The 20:4n-6 content was significantly high in MGDG and PC (more than 60%), and the 16:0 content was significantly high in DGDG and SQDG (more than 50%). Chiral-phase high-performance liquid chromatography determined that fatty acids were esterified at the sn-1 and sn-2 positions of those lipids. The main glycerolipid molecular species were 20:4n-6/20:4n-6 (sn-1/sn-2) for MGDG (56.5%) and PC (40.0%), and 20:4n-6/16:0 for DGDG (75.4%) and SQDG (58.4%). Thus, it was considered that the glycerolipid molecular species containing one or two 20:4n-6 were the major substrates for prostaglandin production in G. vermiculophylla.

Wenyingzhuangia gracilariae sp. nov., a novel marine bacterium of the phylum Bacteroidetes isolated from the red alga Gracilaria vermiculophylla.

A Gram-negative, strictly aerobic, beige-pigmented, non-motile, rod-shaped bacterial strain designated N5DB13-4(T) was isolated from the red alga Gracilaria vermiculophylla (Rhodophyta) collected at Sodegaura Beach, Chiba, Japan. Phylogenetic analyses based on the 16S rRNA gene sequence revealed that the novel isolate is affiliated with the family Flavobacteriaceae within the phylum Bacteroidetes and that it showed highest sequence similarity (97.3%) to Wenyingzhuangia heitensis H-MN17(T). The hybridization values for DNA-DNA relatedness between the strains N5DB13-4(T) and W. heitensis H-MN17(T) were 34.1±3.5%, which is below the threshold accepted for the phylogenetic definition of a novel prokaryotic species. The DNA G+C content of strain N5DB13-4(T) was determined to be 31.8mol%; MK-6 was identified as the major menaquinone; and the presence of iso-C15:0, iso-C15:0 3-OH and iso-C17:0 3-OH as the major (>10%) cellular fatty acids. A complex polar lipid profile was present consisting of phosphatidylethanolamine, two unidentified glycolipids and four unidentified lipids. From the distinct phylogenetic position and combination of genotypic and phenotypic characteristics, the strain is considered to represent a novel species of the genus Wenyingzhuangia for which the name Wenyingzhuangia gracilariae sp. nov. is proposed. The type strain of W. gracilariae sp. nov. is N5DB13-4(T) (=KCTC 42246 (T)=NBRC 110602(T)).

Extraction and Analysis of Oxylipins from Macroalgae Illustrated on the Example Gracilaria vermiculophylla.

Oxylipins are natural products that are derived by oxidative transformations of unsaturated fatty acids. These metabolites are found in a wide range of organisms from the animal kingdom to plants and algae. They represent an important class of signaling molecules, mediating intra- and intercellular processes such as development, inflammation, and other stress responses. In addition, these metabolites directly function as chemical defense against grazers and pathogens. In the red alga Gracilaria vermiculophylla, oxylipin production is initiated by mechanical tissue disruption and can also be induced in intact algae in response to external stress signals. The defense metabolites mostly result from the lipase- and lipoxygenase-mediated conversion of phospho- and galactolipids. Oxylipins can vary greatly in their size, degree of unsaturation, oxidation state, and functional groups. But also isomers with only subtle chemical differences are found. A variety of methods have been developed for separation, detection, and identification of oxylipins. This chapter focuses on the analysis of oxylipins in macroalgae and covers all aspects from sample preparation (including protocols for the investigation of oxylipins in wounded and intact algal tissue), extraction, purification, and subsequent analysis using liquid chromatography coupled to a UV detector or a mass spectrometer. The protocols developed for G. vermiculophylla can be readily adapted to the investigation of other macroalgae.

Effects of the invasive macroalgae Gracilaria vermiculophylla on two co-occurring foundation species and associated invertebrates

Non-native foundation species occasionally invade habitats occupied by native foundation species. Little is known, however, about reciprocal effects of native and non-native foundation species and cascading effects on organisms that depend on foundation species. In a 3factorial field experiment, we tested for: (1) reciprocal effects between the invasive red alga Gracilaria vermiculophylla and two native cooccurring foundation species, the mussel Mytilus edulis and the seagrass Zostera marina; and (2) effects on mobile macro-invertebrates associated with the three foundation species. We found a negative effect of G. vermiculophylla on the above-ground biomass of Z. marina and a positive effect of M. edulis on Z. marina below-ground biomass, but no other significant effects between the three foundation species. Both M. edulis and G. vermiculophylla had positive effects on invertebrate richness and diversity, but Gracilaria also had positive effects on densities of most invertebrate taxa. Additional correlation analyses showed that the abundance of invertebrates increased with the biomass of G. vermiculophylla, indicating density-mediated habitat cascades in invaded seagrass beds. The strong facilitation by G. vermiculophylla could be related to its complex morphology that creates a 3D mosaic of structures and interstitial spaces for different sizes of invertebrates to occupy. Although these results are constrained by the experimental design (one month duration, small plot size, embedded in seagrass meadow, relatively low invader density, invader physically attached with pegs) we suggest that our findings are typical when an invader is structurally complex and mainly occurs in localized patches.

Introduction ofGracilaria vermiculophylla(Rhodophyta, Gracilariales) to New England, USA: Estimated Arrival Times and Current Distribution

Abstract The invasive Asiatic red alga Gracilaria vermiculophylla has recently spread rapidly around the globe. In the Northwest Atlantic, it was first collected in Virginia during 1998; in New England, it was first recorded from Narragansett Bay, Rhode Island in 2007. Until now, the specific dates of its introduction and current distribution in New England have been poorly understood. We employed a combination of field collections, evaluations of historical herbarium specimens, and molecular investigations (including mt-CO1 gene sequencing) to document its present distribution and approximate dates of introduction within New England. We found G. vermiculophylla at 18 of 24 Northwest Atlantic sites growing with native Gracilaria populations. Presently, it is recorded from Stamford, CT to Greenland, NH, with no populations known from five Maine sites where the native G. tikvahiae grows. Molecular screening of historical specimens revealed that G. vermiculophylla was collected from five sites in Massachuset...

Structural and catalytic insights into the algal prostaglandin H synthase reveal atypical features of the first non-animal cyclooxygenase

Prostaglandin H synthases (PGHSs) have been identified in the majority of vertebrate and invertebrate animals, and most recently in the red alga Gracilaria vermiculophylla. Here we report on the cloning, expression and characterization of the algal PGHS, which shares only about 20% of the amino acid sequence identity with its animal counterparts, yet catalyzes the conversion of arachidonic acid into prostaglandin-endoperoxides, PGG2 and PGH2. The algal PGHS lacks structural elements identified in all known animal PGHSs, such as epidermal growth factor-like domain and helix B in the membrane binding domain. The key residues of animal PGHS, like catalytic Tyr-385 and heme liganding His-388 are conserved in the algal enzyme. However, the amino acid residues shown to be important for substrate binding and coordination, and the target residues for nonsteroidal anti-inflammatory drugs (Arg-120, Tyr-355, and Ser-530) are not found at the appropriate positions in the algal sequences. Differently from animal PGHSs the G. vermiculophylla PGHS easily expresses in Escherichia coli as a fully functional enzyme. The recombinant protein was identified as an oligomeric (evidently tetrameric) ferric heme protein. The preferred substrate for the algal PGHS is arachidonic acid with cyclooxygenase reaction rate remarkably higher than values reported for mammalian PGHS isoforms. Similarly to animal PGHS-2, the algal enzyme is capable of metabolizing ester and amide derivatives of arachidonic acid to corresponding prostaglandin products. Algal PGHS is not inhibited by non-steroidal anti-inflammatory drugs. A single copy of intron-free gene encoding for PGHS was identified in the red algae G. vermiculophylla and Coccotylus truncatus genomes.

The effect of temporal variability in salinity on the invasive red alga Gracilaria vermiculophylla

Non-native, invasive species are often characterized by being tolerant to environmental stressors, leaving them more fit relative to native species. The red alga Gracilaria vermiculophylla originates from the NW Pacific but has recently spread along the coastlines of Western Europe, where it has become abundant in many shallow, soft-bottom estuaries. Salinity is important for the local and regional distribution of algae. The distribution of G. vermiculophylla in Europe suggests that it thrives well in hyposaline environments and that it may be more fit than some native algae under such conditions. Little, however, is known about the ecophysiology of G. vermiculophylla and it is therefore difficult to predict its spread and future distribution. Laboratory experiments with G. vermiculophylla showed that steady-state salinity above 15 psu was optimal for growth and that the growth rate was reduced at salinities below 15 psu. Variable salinity reduced the growth rate and larger oscillations were more stressful than small ones. Exposure to very low salinity (0–5 psu) was stressful for the alga and algae exposed to these low levels for 2–4 days were unable to recover fully. Gracilaria vermiculophylla did not seem to perform better in hyposaline conditions than many native, estuarine species. The present distribution of G. vermiculophylla in Scandinavia can be explained well by its response to salinity, but this may not explain its present success relative to many naturally occurring algal species.