Sulfated Galactans Research Articles

Mechanical and Barrier Properties of Semi Refined Kappa Carrageenan-based Composite Edible Film and Its Application on Minimally Processed Chicken Breast Fillet

Kappa-carrageenan (KC) is one of the most interesting biopolymers that is composed of a linear chain of sulfated galactans and extracted from red seaweed, Kappaphycus alvarezii. It shows good potential for development as a source of biodegradable or edible films. However, KC films do not have good water vapor barrier properties, as they are intrinsically hydrophilic. Palmitic acid (PA) as hydrophobic material was incorporated into semi-refined kappa-carrageenan (SRKC) edible films in order to improve water vapor barrier properties. In this study, composite films based on SRKC incorporating PA were prepared and their applications on minimally processed chicken breast fillet were evaluated. Composite SRKC-based films with varying concentrations of PA (5%, 10%, and 15% w/w) were obtained by a solvent casting method. Their mechanical and barrier properties were investigated. Results showed that the incorporation of PA in films caused an increase in thickness, but decrease in water vapor transmission rate (WVTR) as the concentration of PA increased (from 5% to 15% w/w). Composite SRKC-based edible film incorporating 15% w/w of PA presented better water vapor barrier properties as compared to other films with 5% and 10% w/w PA incorporation. Thus, formulation containing 15% w/w PA was used as a wrapping material for film application on minimally processed chicken breast fillet. The application results showed that the incorporation of PA in film caused an effect (p < 0.05) on preventing of weight loss significantly compare to control (non-wrapping), however it did not significantly (p >0.05) change the color of minimally processed chicken breast fillet.

Biological and therapeutic properties of the seaweed polysaccharides

Seaweed polysaccharides isolated from the cell walls of various species of algae, possess immunomodulatory, anti-inflammatory, antiviral, antitumor, antithrombotic, anticoagulant and antioxidant bioactivities. Within the group of polysaccharides extracted from algae there are the phycocolloids. Colloids are extracted compounds that form colloidal solutions, an intermediate state between a solution and a suspension; they can be used commercially as thickeners, gelling agents and stabilizers for suspensions and emulsions. Hydrocolloids are carbohydrates that when dissolved in water form viscous solutions. Sulfated galactans (e.g. agars, carrageenans, porphyrans) can be obtained from red algae, (e.g. ulvans) from green algae, alginates and other sulfated polysaccharides (e.g. ascophyllan, laminaran and fucoidan) are obtained from selected brown algae. The historic origin of the main phycocolloids and other seaweed polysaccharides (e.g. agar, carrageenan, alginic acid - alginates), their chemistry, uses and bioactivities are described in this review.

Isolation, characterization and bioactive potential of sulfated galactans from Spyridia hypnoides (Bory) Papenfuss

The sulfated galactans (SG) of mass 16 kDa was purified from S.hypnoides through anion exchange and gel permeation chromatography. The biochemical properties of SG including carbohydrate, 3,6 anhydrogalactose, sulfate, uronic acid, moisture, ash, carbon, hydrogen, nitrogen contents were estimated. In the purified SG, the presence of major sugars such as galactose and glucose were identified through HPLC and it was further structurally characterised through FT-IR and NMR spectroscopy. Anticoagulant activity of SG was estimated as 25.36 & 2.46 IU at 25 μg/ml (aPTT & PT). SG also showed potential dose dependent antioxidant activity against free radicals such as DPPH (56.41% at 2 mg/ml), hydroxyl radicals (65.58% at 3 mg/ml) and superoxide radicals (73.12% at 0.6 mg/ml). The maximum metal chelating and total antioxidant property (76.42%, 66.81%) was exhibited at 1 mg/ml. The results indicate that the SG from red seaweed represents a good source of polysaccharide with significant anticoagulant and antioxidant properties.

Sulfated galactans from the red seaweed Gracilaria fisheri exerts anti-migration effect on cholangiocarcinoma cells

BackgroundSeaweeds have a long history of use in Asian countries as functional foods, medicinal herbs, and the treatment of cancer. Polysaccharides from various seaweeds have shown anti-tumor activity. Cholangiocarcinoma (CCA), often with metastatic disease, is highly prevalent in Thailand as a consequence of liver fluke infection. Recently, we extracted sulfated galactans (SG) from Gracilaria fisheri (G. fisheri), a south east Asian seaweed, and found it exhibited anti-proliferation effect on CCA cells. PurposeIn the present study, we evaluated the anti-migration activity of SG on CCA cells and its underlined mechanism. MethodsCCA cells were treated with SG alone or drugs targeting to epidermal growth factor (EGF) receptor (EGFR) or pretreated with SG prior to incubation with EGF. Anti-migration activity was determined using a scratch wound-healing assay and zymography. Immunofluorescence staining and western blotting were used to investigate EGFR signaling mediators. ResultsUnder basal condition, SG reduced the migration rate of CCA, which was correlated with a decrease in the active-form of matrix metalloproteinases-9. SG decreased expression of phosphorylated focal adhesion kinase (FAK), but increased expression of E-cadherin to promote cells stasis. Moreover, phosphorylation of EGFR and extracellular signal-regulated kinases (ERK), known to stimulate growth of cancer cells, was blocked in a comparable way to EGFR inhibitors Cetuximab and Erlotinib. Pretreatment cells with SG attenuated EGF induced phosphorylation of EGFR, ERK and FAK. ConclusionThis study reveals that SG from G. fisheri retards migration of CCA cells, and its mechanism of inhibition is mediated, to some extent, by inhibitory effects on MAPK/ERK signal transduction pathway. Our findings suggest that there may be a therapeutic potential of SG in CCA treatment.

Structural analysis of a sulfated galactan from the tunic of the ascidian Microcosmus exasperatus and its inhibitory effect of the intrinsic coagulation pathway

Several bioactive sulfated galactans have been isolated from the tunic of different species of ascidians. The biological activity of this kind of polysaccharides has been related with the presence and position of sulfate groups, and by the chemical composition of this kind of polysaccharides. A sulfated galactan (1000RS) was isolated from the tunic of the Brazilian ascidia Microcosmus exasperatus through proteolytic digestion, ethanol precipitation, dialysis and freeze-thaw cycles. Homogeneity and molecular weight were estimated by using size exclusion chromatography. Monosaccharide composition and type of linkage were assessed by Gas chromatography coupled to mass spectrometry and the sulfate content was quantified through gelatin/BaCl2 method. These experiments along with NMR and FTIR analysis allowed to claim that the galactan backbone is mainly composed of 4-linked α-l-Galp units. In addition, they permitted to establish that some of the galactose residues are sulfated at the 3-position. This sulfated polysaccharide, which has an average molecular mass of 439.5kDa, presents anticoagulant effect in a dose-dependent manner through the inhibition of the intrinsic coagulation pathway.

Effect of sulfated galactan from Porphyra haitanensis on H2O2-induced premature senescence in WI-38 cells

Porphyran sulfated galactan extracted from red algae Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent activities. In the present study, WI-38 cells were treated with H2O2 to induce premature senescence and then the protection of porphyran against aging in vitro and associated molecular mechanisms were investigated. The protection occurred in a dose-dependent manner, offering an optimal efficacy starting at 10μg/mL. The proportion of SA-β-gal positive cells in porphyran group decreases from 53% to 23% in the cultures at 30 PDs. Porphyran has been detected specifically reducing SAHF-like foci formation in senescent cells. In addition, porphyran significantly affected the p53-p21 pathways in H2O2-treated WI-38 cells. Our data suggest the promising role of porphyran as an attractive and bio-safe agent with the potential to retard senescence and attenuate senescence-related diseases.

The Sea as a Rich Source of Structurally Unique Glycosaminoglycans and Mimetics.

Glycosaminoglycans (GAGs) are sulfated glycans capable of regulating various biological and medical functions. Heparin, heparan sulfate, chondroitin sulfate, dermatan sulfate, keratan sulfate and hyaluronan are the principal classes of GAGs found in animals. Although GAGs are all composed of disaccharide repeating building blocks, the sulfation patterns and the composing alternating monosaccharides vary among classes. Interestingly, GAGs from marine organisms can present structures clearly distinct from terrestrial animals even considering the same class of GAG. The holothurian fucosylated chondroitin sulfate, the dermatan sulfates with distinct sulfation patterns extracted from ascidian species, the sulfated glucuronic acid-containing heparan sulfate isolated from the gastropode Nodipecten nodosum, and the hybrid heparin/heparan sulfate molecule obtained from the shrimp Litopenaeus vannamei are some typical examples. Besides being a rich source of structurally unique GAGs, the sea is also a wealthy environment of GAG-resembling sulfated glycans. Examples of these mimetics are the sulfated fucans and sulfated galactans found in brown, red and green algae, sea urchins and sea cucumbers. For adequate visualization, representations of all discussed molecules are given in both Haworth projections and 3D models.

Antioxidative sulphated polygalactans from marine macroalgae as angiotensin-I converting enzyme inhibitors

Antioxidant and antihypertensive potential of the sulphated polygalactans isolated from the marine macroalgae Kappaphycus alvarezii and Gracilaria opuntia were assessed by utilising different in vitro systems. The galactans isolated from K. alvarezii possessed significantly greater antioxidative properties as determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH IC90 0.97 mg/mL) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS.+ IC90 0.72 mg/mL) scavenging activities than those isolated from G. opuntia (DPPH IC90 1.2 mg/mL and ABTS 0.86 mg/mL). The sulphated polygalactan →4)-4-O-sulphonato-(2-O-methyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-methyl)-α-D-galactopyranan from K. alvarezii showed greater angiotensin-I-converting enzyme (ACE) inhibitory activity (IC50 0.02 μg/mL) than →3)-4-O-sulphonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulphonato)-α-D-galactopyranosyl-(1→3)-4-O-sulphonato-(6-O-acetyl)-β-D-xylosyl-(1→3)-4-O-sulphonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulphonato)-α-D-galactopyranan motif extracted from G. opuntia (IC50 0.70 μg/mL). Structure activity correlation studies displayed that the ACE inhibitory properties of titled polygalactans were directly proportional to their electronic properties and inversely with the steric and hydrophobic characteristics. Putative ACE inhibitory mechanism of action of sulphated galactans from marine macroalgae corroborated the structure bioactivity correlation analysis.

Polysaccharides of algae 69. Monosaccharide composition of polysaccharides of several Pacific red algae studied by reductive hydrolysis of biomass

Polysaccharide composition of 23 species of red algae collected from the coastal waters of Kamchatka and Commander Islands has been determined. Total acid hydrolysis of biomass was carried out in the presence of borane-4-methylmorpholine complex under the conditions where 3,6-anhydrogalactose liberating from sulfated galactans was protected from the acid degradation due to reduction into 3,6-anhydrogalactitol. Partial hydrolysis of biomass in the presence of the same reducing agent gave rise to diastereomeric agarobiitol or carrabiitol (3,6-anhydro-4-O-β-d-galactopyranosyl-l-or -d-galactitol, respectively). Identification of these fragments made it possible to attribute the algal galactans to agars or carrageenans. The data obtained was used to confirm the correlations between the taxonomic status and polysac-charide composition of the red algae.

A sulfated galactans supplemented diet enhances the expression of immune genes and protects against Vibrio parahaemolyticus infection in shrimp

A sulfated galactans (SG) supplemented diet was evaluated for the potential to stimulate immune activity in shrimp Penaeus vannamei (P. vannamei). Shrimp given the SG supplemented diet (0.5, 1 and 2% w/w) for 7 days showed enhanced expression of the downstream signaling mediator of lipopolysaccharide and β-1,3-glucan binding protein (LGBP) and immune related genes including p-NF-κB, IMD, IKKβ and IKKε, antimicrobial peptide PEN-4, proPO-I and II. Following immersion with Vibrio parahaemolyticus (V. parahaemolyticus) for 14 days, the shrimp given the SG supplemented diet (1 and 2% w/w) showed a decrease in bacterial colonies and bacterial toxin gene expression, compared to shrimp given a normal diet, and they reached 50% mortality at day 14. However, shrimp given the normal diet and challenged with the bacteria reached 100% mortality at day 6. SG-fed shrimp increased expression of immune genes related to LGBP signaling at day 1 after the bacterial immersion compared to control (no immersion), which later decreased to control levels. Shrimp on the normal diet also increased expression of immune related genes at day 1 after immersion which however decreased below control levels by day 3. Taken together, the results indicate the efficacy of the SG supplemented diet to enhance the immune activity in shrimp which could offer protection from V. parahaemolyticus infection.

Production of heparin and λ-carrageenan anti-heparanase derivatives using a combination of physicochemical depolymerization and glycol splitting

Strongly associated with tumor angiogenesis and metastasis, the enzyme heparanase is an endo-β-d-glucuronidase which is overexpressed in the tumor microenvironment. Its inhibition could be one of the most promising anti-angiogenic approaches to date. Although heparin is known as a good heparanase inhibitor, it also possesses major anticoagulant properties that may be incompatible with its use as an anti-angiogenic agent, hence the considerable interest for other sources of sulfated polysaccharides. Recent investigations point to λ-carrageenans, highly sulfated galactans with a tremendous potential that are found in red algae.This study describes the production of low-molecular-weight (LMW) heparins and λ-carrageenans, using a combination of glycol splitting and ultrasonically-assisted radical hydrolysis using hydrogen-peroxide. The structural characteristics, as well as the anticoagulant and antiheparanase activities of the resulting products were assessed. The best candidate was a LMW glycol-split λ-carrageenan that displayed major anti-heparanase properties, with an IC50 of 7.32ng/mL and a close-to-zero anticoagulant activity.

Sulfated Galactans from Red Seaweed Gracilaria fisheri Target EGFR and Inhibit Cholangiocarcinoma Cell Proliferation

Cholangiocarcinoma (CCA) is increasing in incidence worldwide and is resistant to chemotherapeutic agents, making treatment of CCA a major challenge. Previous studies reported that natural sulfated polysaccharides (SPs) disrupted growth factor receptor activation in cancer cells. The present study, therefore, aimed at investigating the antiproliferation effect of sulfated galactans (SG) isolated from the red seaweed Gracilaria fisheri (G.fisheri) on CCA cell lines. Direct binding activity of SG to CCA cells, epidermal growth factor (EGF) and epidermal growth factor receptor (EGFR) were determined. The effect of SG on proliferation of CCA cells was investigated. Cell cycle analyses and expression of signaling molecules associated with proliferation were also determined. The results demonstrated that SG bound directly to EGFR. SG inhibited proliferation of various CCA cell lines by inhibiting EGFR and extracellular signal-regulated kinases (ERK) phosphorylation, and inhibited EGF-induced increased cell proliferation. Cell cycle analyses showed that SG induced cell cycle arrest at the G0/G1 phase, down-regulated cell cycle genes and proteins (cyclin-D, cyclin-E, cdk-4, cdk-2), and up-regulated the tumor suppressor protein P53 and the cyclin-dependent kinase inhibitor P21. Taken together, these data demonstrate that SG from G.fisheri inhibited proliferation of CCA cells, and its mechanism of inhibition is mediated, to some extent, by inhibitory effects on EGFR activation and EGFR/ERK signaling pathway. SG presents a potential EGFR targeted molecule, which may be further clinically developed in a combination therapy for CCA treatment.

Dietary supplementation with sulfated galactans from Gracilaria fisheri enhances immunity and protects against Vibrio parahaemolyticus infection in shrimp

Dietary supplementation with sulfated galactans from Gracilaria fisheri enhances immunity and protects against Vibrio parahaemolyticus infection in shrimp

Antimicrobial Sulfated Glycans: Structure and Function.

Owing to their inherent structural features, certain sulfated glycans isolated from terrestrial or marine mammals or invertebrates, can exert therapeutic properties against infections caused by pathogenic microorganisms like bacteria, virus, fungus, and protozoan parasites. These sulfated glycans belong to a variety of classes including glycosaminoglycans (GAGs) like chondroitin sulfate, fucosylated chondroitin sulfate, dermatan sulfate, unfractionated heparin, low-molecular-weight heparin, and acharan sulfate; and the less-famous algal polysaccharides known as sulfated fucans (including fucoidans), sulfated galactans (agarans and carrageenans), and sulfated heteropolysaccharides. Administration at certain concentrations of the antimicrobial sulfated glycans, especially those containing the higher amounts of the bioactive structural requirements, can lead to the interruption or disruption of the pathogen protein-host GAG complex formation, leading thus to the decrease or impairment of the microbial binding onto host cells. This report aims at presenting the current background concerning the therapeutic effects of the above-mentioned sulfated glycans as new antimicrobial agents. When sufficient data are available, discussion regarding structure-activity relationship is provided.

Enzymatic desulfation of the red seaweeds agar by Marinomonas arylsulfatase

Agar and sulfated galactans were isolated from the red seaweeds Gracilariopsis lemaneiformis and Gelidium amansii. A previously purified arylsulfatase from Marinomonas sp. FW-1 was used to remove sulfate groups in agar and sulfated galactans. After enzymatic desulfation, the sulfate content decreased to about 0.16% and gel strength increased about two folds. Moreover, there was no difference between the DNA electrophoresis spectrum on the gel of the arylsulfatase-treated agar and that of the commercial agarose. In order to reveal the desulfation ratio and site, chemical and structural identification of sulfated galactan were carried out. G. amansii sulfated galactan with 7.4% sulfated content was composed of galactose and 3,6-anhydro-l-galactose. Meanwhile, G. lemaneiformis sulfated galactan with 8.5% sulfated content was composed of galactose, 3,6-anhydro-l-galactose, 2-O-methyl-3,6-anhydro-l-galactose and xylose. Data from 13C NMR, FT-IR, GC–MS provided evidence of sulfate groups at C-4 and C-6 of d-galactose and C-6 of l-galactose both in GRAP and GEAP. Data from GC–MS revealed that desulfation was carried out by the arylsulfatase at the sulfate bonds at C-4 and C-6 of d-galactose and C-6 of l-galactose, with a desulfation ratio of 83.4% and 86.0% against GEAP and GRAP, respectively.

Antidiabetic and anti-inflammatory potential of sulphated polygalactans from red seaweeds Kappaphycus alvarezii and Gracilaria opuntia

ABSTRACTAntidiabetic and anti-inflammatory potential of sulphated polygalactans isolated from the red seaweeds Kappaphycus alvarezii and Gracilaria opuntia were acquired by employing different in vitro systems. The sulphated galactopyran motif derived from G. opuntia possessed significant antidiabetic properties as identified by α-amylase (IC50 0.04 mg/mL), α-glucosidase (IC50 0.09 mg/mL) and dipeptidyl peptidase-4 (DPP-4, IC50 0.09 mg/mL) inhibitory activities. Based on the detailed nuclear magnetic resonance spectroscopy experiments the sulphated galactopyran motif of G. opuntia was designated as →3)-4-O-sulfonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulfonato)-α-D-galactopyranosyl-(1→3)-4-O-sulfonato-(6-O-acetyl)-β-D-xylosyl-(1→3)-4-O-sulfonato-(6-O-acetyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-sulfonato)-α-D-galactopyranan, while the one from K. alvarezii was demonstrated to be →4)-4-O-sulfonato-(2-O-methyl)-β-D-galactopyranosyl-(1→4)-3,6-anhydro-(2-O-methyl)-α-D-galactopyranan. The sulphated galactans from G. opuntia showed greater anti-inflammatory inhibitory activities as determined by cyclooxygenase-1 (COX-1, IC50 0.01 mg/mL), cyclooxygenase-2 (COX-2, IC50 0.03 mg/mL), and 5-lipoxygenase inhibitory activities (5-LOX, IC50 0.24 mg/mL). This study revealed that the sulfated polygalactan enriched concentrate from G. opuntia can be used as potential therapeutic candidate to suppress the hyperglycemic response in diabetic conditions and inflammatory activity. They can be used to develop functional food ingredient in nutraceutical products.

Sequence analysis of the pyruvylated galactan sulfate-derived oligosaccharides by negative-ion electrospray tandem mass spectrometry

Five sulfated oligosaccharide fragments, F1–F5, were prepared from a pyruvylated galactan sulfate from the green alga Codium divaricatum, by partial depolymerization using mild acid hydrolysis and purification with gel-permeation chromatography. Negative-ion electrospray tandem mass spectrometry with collision-induced dissociation (ES-CID-MS/MS) is attempted for sequence determination of the sulfated oligosaccharides. The sequence of F1 with homogeneous disaccharide composition was first characterized to be Galp-(4SO4)-(1 → 3)-Galp by detailed nuclear magnetic resonance spectroscopic analyses. The fragmentation pattern of F1 in the product ion spectra was established on the basis of negative-ion ES-CID MS/MS, which was then applied to sequence analysis of other sulfated oligosaccharides. The sequences of F2 and F3 were deduced to be Galp-(4SO4)-(1 → 3)-Galp-(1 → 3)-Galp-(1 → 3)-Galp and 3,4-O-(1-carboxyethylidene)-Galp-(6SO4)-(1 → 3)-Galp, respectively. The sequences of major fragments in F4 and F5 were also deduced. The investigation demonstrated that negative-ion ES-CID-MS/MS was an efficient method for the sequence analysis of the pyruvylated galactan sulfate-derived oligosaccharides which revealed the patterns of substitution and glycosidic linkages. The pyruvylated galactan sulfate-derived oligosaccharides were novel sulfated oligosaccharides different from other algal polysaccharide-derived oligosaccharides.

Anticancer Activity of Sulfated Polysaccharides Isolated from the Antarctic Red Seaweed Iridaea cordata

This study aimed to isolate and characterize sulfated polysaccharides (SPs) from Iridaea cordata and evaluate their anticancer activity. SPs of the Antarctic red seaweed were obtained by CaCl₂ (SP1) and ethanol precipitations (SP2) following diluted acid extraction at room temperature. Yields of SP1 and SP2 were approximately 14% and 23%, respectively, of the dry weight of red seaweed. The average molecular mass of the SP1 and SP2 was estimated about 1.84 × 10³ and 1.42 × 10³ kDa, respectively, by size-fractionation High-Performance Liquid Chromatography (HPLC). From the High-Performance Anion-Exchange Chromatography-Pulsed Amperometric Detection (HPAEC-PAD) analysis, the main monosaccharide was galactose with glucose and fucose as minor components. The sulfate content of SP2 (40.4%) was slightly higher than that of SP1 (33.8%). The FT-IR spectra also showed characteristic band of carrageenan-like sulfated polysaccharides. Taken together the SPs are thought to be carrageenan-like sulfated galactan. The polysaccharides (SPs) from I. cordata exhibited weak antitumor activity against PC-3 (prostate cancer), HeLa (cervical cancer), and HT-29 (human colon adenocarcinoma). To our knowledge, this is the first data on biological activity of the Antarctic red seaweed I. cordata.

Bacterial carrageenases: an overview of production and biotechnological applications.

Carrageenan, one of the phycocolloids is a sulfated galactan made up of linear chains of galactose and 3,6-anhydrogalactose with alternating α-(1 → 3) and β-(1 → 4) linkages and further classified based on the number and the position of sulfated ester(s); κ-, ι- and λ-carrageenan. Enzymes which degrade carrageenans are called k-, ι-, and λ-carrageenases. They all are endohydrolases that cleave the internal β-(1–4) linkages of carrageenans yielding products of the oligo-carrageenans. These enzymes are produced only by bacteria specifically gram negative bacteria. Majority of the marine bacteria produce these enzymes extracellularly and their activity is in wide range of temperature. They have found potential applications in biomedical field, bioethanol production, textile industry, as a detergent additive and for isolation of protoplast of algae etc. A comprehensive information shall be helpful for the effective understanding and application of these enzymes. In this review exhaustive information of bacterial carrageenases reported till date has been done. All the aspects like sources, production conditions, characterization, cloning and- biotechnological applications are summarized.

The genome of the seagrass Zostera marina reveals angiosperm adaptation to the sea.

Seagrasses colonized the sea on at least three independent occasions to form the basis of one of the most productive and widespread coastal ecosystems on the planet. Here we report the genome of Zostera marina (L.), the first, to our knowledge, marine angiosperm to be fully sequenced. This reveals unique insights into the genomic losses and gains involved in achieving the structural and physiological adaptations required for its marine lifestyle, arguably the most severe habitat shift ever accomplished by flowering plants. Key angiosperm innovations that were lost include the entire repertoire of stomatal genes, genes involved in the synthesis of terpenoids and ethylene signalling, and genes for ultraviolet protection and phytochromes for far-red sensing. Seagrasses have also regained functions enabling them to adjust to full salinity. Their cell walls contain all of the polysaccharides typical of land plants, but also contain polyanionic, low-methylated pectins and sulfated galactans, a feature shared with the cell walls of all macroalgae and that is important for ion homoeostasis, nutrient uptake and O2/CO2 exchange through leaf epidermal cells. The Z. marina genome resource will markedly advance a wide range of functional ecological studies from adaptation of marine ecosystems under climate warming, to unravelling the mechanisms of osmoregulation under high salinities that may further inform our understanding of the evolution of salt tolerance in crop plants.