Donald W. Renn

Seaweeds and biotechnology — inseparable companions

I may be going out on the proverbial limb by saying that most of the major advances in modern biotechnology would not have been possible without the availability of the polysaccharides from marine macroalgae, or seaweeds, but from my admittedly biased vantage point, this is a reality. A number of you who are participants in this XIIIth International Seaweed Symposium have made significant contributions, both directly and indirectly, to this effort.

Purified curdlan and its hydroxyalkyl derivatives: preparation, properties and applications

Abstract Curdlan, a β-1,3-glucan produced by fermentation of Alkaligenes faecalis , is a non-ionic gel-forming polysaccharide that is, along with its hydroxalkyl derivatives, a potentially important matrix for life science applications. The commercially available material contains residual nucleic acids, cellular debris and other contaminants that can interfere with electrophoretic separations and visualization procedures. Simple procedures have been developed for purification of the curdlan and coherent gel formation. Curdlan gels can be formed in a variety of chaotrope-containing, or chaotropic, solvents, including 40% formamide, 7 M urea. The chaotropes can be retained or subsequently removed by leaching. Heat treatment before or after leaching enables thermostable gel formation. Hydroxyethyl and glyceryl derivatives of curdlan have been prepared. Depending on the degree of substitution (DS), a whole spectrum of derivatives with a range of unique properties can be obtained. Lower DS hydroxyethyl derivatives form clear, elastic gels in 6 M urea, while the higher DS hydroxyethyl derivatives are soluble in hot water and gel on cooling to form clear, elastic, thermoreversible gels. Partial depolymerization of curdlan by γ-irradiation reduces the viscosity of subsequent preparations, enabling the preparation of higher concentration, more sieving gels. Use of selected preparations to form unique matrices for electrophoretic separations has been demonstrated.

β-carrageenan: Isolation and characterization

Abstract β-Carrageenan, essentially devoid of ester sulfate, was isolated from the hot aqueous extracts of alkali-modified Eucheuma gelatinae, Eucheuma speciosa, and Endocladia muricatum by precipitating the more anionic moieties with a quaternary ammonium salt, isolating the fractions that did not precipitate, then treating these with an anion-exchange cellulose. The β-carrageenan was characterized by chemical analysis, optical rotation, and NMR. Gelling was found to be ion-independent, with Tg = 31–33°C and Tm = 63–70°C. Specific optical rotations of the isolated β-carrageenan samples were more positive than the κ-, λ-, and ι-carrageenans with which they were compared, while agarose, its stereoisomer, exhibited a negative specific rotation. Electrophoresis gels made from β-carrageenan were used to separate DNA fragments which exhibited faster migration than on an agarose gel of comparable concentration, indicating that β-carrageenan has a less restrictive pore structure.

Use of heteropoly acids as immunological precipitin brighteners

Abstract Aqueous solutions of the heteropoly acids, phosphotungstic and phosphomolybdic, are excellent precipitin brighteners for analytical immunological reactions such as radial immunodiffusion and electroimmunodiffusion in agarose gel media. These substances not only enhance the immunoprecipitate, enabling distinct differentiation from background residual protein, but also enable subsequent removal of residual nonimmunoprecipitated protein by saline solution prior to staining.

Medical and Biotechnological Applications of Marine Macroalgal Polysaccharides

A considerable number of prescription drugs contain land-plant-derived ingredients. Although marine plants are not as evolutionarily advanced as land plants, when one considers the fact that over 3600 different varieties of marine macroalgae or seaweeds exist, it is not surprising that among these are some having pronounced pharmacological activities or other properties useful in the biomedical arena. What is surprising is that some of this pharmacological activity is attributed to the polysaccharides they contain, particularly those that are sulfated. Although the results of many studies ascribing different physiological properties to these sulfated polysaccharides can be found in the literature, few, if any, have ever reached commercial importance. Currently, their most important use is in biomedical research, where their inflammatory, immune-stimulating and -suppressing, thrombosis-causing, and other properties are used to induce a particular response in model systems for studying and/or screening materials for potential therapeutic value. Over the past 35 years, a number of papers, patents, and review articles have addressed these pharmacological properties in considerable detail. It is not the intent of this chapter to add another comprehensive review to the literature. Instead, in the first portion of this chapter, a description of the more important physiological properties will be addressed and a few leading references given.

Reagent-in-film (RIF): A simplified reagent delivery system

Abstract Water-soluble or dispersible reagents, including antigens, antibodies, enzymes, substrates, stains, antibioties, or nutrient media, can be incorporated into supported or unsupported hydrocolloid films, dried, and stored in this form until ready for use. The “reagent-in-film” can then be placed in contact with a water-containing medium such as agarose, agar, polyacrylamide, gelatin, cellulose acetate, or paper, whereupon the reagent and its hydrocolloid carrier are transferred rapidly and essentially quantitatively into the medium.