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PubMed1977

The occurrence and seasonal variation of gigartinine and L-citrullinyl-L-arginine in Chondrus crispus Stackh.

Gigartinine, 5-(3-amidinoureido)-2-aminovaleric acid, and L-citrullinyl-L-arginine were islated from aqueous extracts of Chondrus crispus (Rhodophyceae). Their identifications were confirmed by chemical procedures, and 1H and 13C nuclear magnetic resonance and infrared spectroscopic methods. Citrullinylarginine, gigartinine, taurine, citrulline, and glutamic acid were the predominant free amino compounds. Citrullinylarginine showed the most pronounced change in concentration. This occurred during the winter months when it reached a maximum (in March) of 58 mumol/g fresh weight, a value 10 times greater than that of any of the free amino acids and equal to 50% of the total organic nitrogen in the plant; All of these compounds were depleted to a minimum of about 1 mumol/g fresh weight in October. Both gigartinine and citrullinylarginine were detected in Ahnfeltia plicata, Gracilaria sp. Petrocelis middendorfii, Polyides rotundus, Polysiphonia lanosa, and Rhodomela confervoides.

Amino Acids↗

PubMed1978

The immunochemistry of lambda-type carrageenans from certain red algae.

An antibody preparation directed against a structural feature associated with 6-sulphate groups was used to probe structural relations among certain lambda-type carrageenans. Immunochemical and chemical differences are described between the KC1-soluble carrageenans from tetrasporic algal plants of Gigartina corymbifera, Gigartina sp. from San Francisco Bay, Petrocelis middendorfii, Iridaea cordata, Rhodoglossum californicum, and Chondrus crispus. The differences in immunochemical reactivity of the Gigartina and Petrocelis carrageenans relative to the homologous antigen (Chondrus crispus lambda-carrageenan) are attributed to the lower content of 6-sulphate groups on the 4-linked residues in the former carrageenans. Both the immunochemical and chemical data suggest that the Gigartina and Petrocelis carrageenans are largely xi-like in structure but do contain lambda-like features. The i.r. spectrum of the Petrocelis carrageenan differs from that of the Gigartina carrageenans. The carrageenans from I. cordata and R. californicum differ to a lesser degree from Chondrus crispus lambda-type carrageenan. These differences cannot be accounted for by differences in the levels of 6-sulphate groups. Some other structural feature, as yet unidentified, is responsible for the discrepancy in the immunochemical reactivity of these carrageenans to the anti-lambda-carrageenan.

Animals↗

PubMed2026

The multilayered cuticle underlying structural coloration in red algae shares features with the metazoan extracellular matrix.

Structural coloration, a physical phenomenon observed in many living organisms, may arise from the interference of light with highly organized surface nanostructures. In some seaweeds, these nanostructures consist of cuticular lamellae in the outer part of the extracellular matrix (ECM) of the epidermis. However, the chemical composition of seaweed cuticles is poorly understood and the molecular components of lamellae remain unidentified. Here, we use integrated genomic, transcriptomic, proteomic, and metabolomic approaches together with analytical profiling of carbohydrates to determine the composition of the multilayered cuticle in the red alga Chondrus crispus and assess its evolutionary conservation. The structural assembly reveals common features with the ECM of animals. The carbohydrate fraction includes a complex mixture of carrageenans and glycosaminoglycan-like compositions. A major von Willebrand factor A domain protein, Lamellae Cohesive Protein, plays a critical role in protein-protein interactions and binding to sulfated polysaccharides. We have further identified the major proteins of the algal cuticle, providing a framework for addressing the evolutionary origins of the cuticle and raising important questions regarding its role, particularly across the red algal life cycle marked by major structural differences in its ECM.

Extracellular Matrix↗

PubMed1979

Quantitative X-ray microanalysis of halogen elements in biological specimens.

Standards were prepared for quantitative X-ray microanalysis of the halogen elements Cl, Br and I in sections of resin embedded biological specimens. Halogenated aromatic compounds were dissolved in resin, which subsequently was polymerized. Homogeneity and stability of the standards were determined and found to be satisfactory. A general procedure of calculation of elemental concentrations according to the continuum method is given for the case that the specimen contains appreciable concentrations of one or more rather heavy elements. It is shown that use of approximations may lead to unacceptable errors, even in the concentration ranges occurring in biological specimens. As a practical application, the concentration of bromine in the chloroplasts of the red alga Chondrus crispus was determined quantitatively. The inner cells contained more bromine than the epidermal cells: in the chloroplasts of the inner cells bromine concentrations of about 6% could be demonstrated.

Bromine↗

PubMed1979

Glycosulphatase from Pseudomonas carrageenovora. Purification and some properties.

A glycosulphatase present in the soluble fraction of disrupted Pseudomonas carrageenovora has been purified 500-fold by gel filtration on Sephacryl S-200 and ion-exchange chromatography on DEAE-Sepharose CL-6B. By dodecylsulphate/polyacrylamide gel electrophoresis the enzyme is practically homogeneous and has a molecular weight of 55 000. Conditions of optimal sodium chloride concentration and pH at 25 degrees C were 0.25--0.50 mol dm-3 and pH 7.0 respectively. The purified enzyme was inhibited by inorganic phosphate. Preparation is described of neocarrabiose 4-O-[35S]sulphate and neocarratetraose 4-O-[35S]sulphate from labelled Chondrus crispus. The purified glycosulphatase is active against both these substrates although only one of the two sulphate esters in the tetrasaccharide is hydrolysed. Analysis of the reaction products was by gel filtration, electrophoresis and 13C nuclear magnetic resonance spectroscopy. The results are consistent with the products of desulphation being respectively neocarrabiose and neocarratetraose 4-O-monosulphate with the sulphate ester proximal to the reducing end [3,6-anhydro-alpha-D-galactopyranosyl-(1 leads to 3)-beta-D-galactopyranosyl-(1 leads to 4)-3,6-anhydro-alpha-D-galactopyranosyl-(1 leads to 3)-D-galactose 4-O-sulphate].

Glycosides↗