Local and chemical distribution of phlorotannins in brown algae

The local and chemical distribution of phlorotannins among the Japanese Laminariaceae, Eisenia bicyclis, Ecklonia cava and Ecklonia kurome, was investigated. As a result of light microscopy observations with vanillin-HCl staining, phlorotannins were found to be accumulated within the vegetative cells of the outer cortical layer of the thalli, regardless of the species, stage of growth or organ. Crude phlorotannins comprised about 3.0% of the algal powder for each of the algae. High-performance liquid chromatography (HPLC) showed that the phlorotannins of E. bicyclis were composed of phloroglucinol (0.9%), phloroglucinol tetramer (4.4%), eckol (7.5%), phlorofucofuroeckol A (21.9%), dieckol (23.4%), and 8,8'-bieckol (24.6%), plus some other unknown phenolic compounds (17.3%). The composition of the phlorotannins differed little among the Laminariaceae, except for a significantly larger amount of the tetramer, MW 478, in E. bicyclis.     

Screening test for deodorizing substances from marine algae and identification of phlorotannins as the effective ingredients in Eisenia bicyclis

Aqueous extracts from 33 species of marine algae were assessed for their methyl mercaptan-trapping activity by gas chromatography to search for novel natural oral deodorants. Brown algae belonging to the Laminariales such as Eisenia bicyclis, Ecklonia cava and Ecklonia kurome were found to show remarkable deodorizing action against methyl mercaptan. The effective components in Eisenia bicyclis were identified as a phlorotannin, a group of molecules which are characteristic components of Laminariales. In addition phlorotannins extracted from E. bicyclis were more effective at reducing methyl mercaptan than conventional natural deodorants such as chlorophyll and sodium copper chlorophyllin.Author for Correspondence     

Host-virus interactions in marine brown algae

Ectocarpus-like marine brown algae are frequently parasitized by polyhedric DNA viruses. Infected hosts have been studied in unialgal and axenic cultures, and the present state of knowledge is summarized in regard to stage-specific virus expression, discharge and survival time of virus particles, infection mechanism, association with host's nuclear genome, passage of the virus genome through mitosis and meiosis of the host, suppression of symptoms and spontaneous recovery of infected plants, host specificity and intergeneric transmission, vitality of infected plants, pandemic occurrence of virus infections, molecular data on Ectocarpus and Feldmannia viruses, and algal DNA-viruses as potential vectors for gene transfer. A scheme for the nomenclature of brown algal viruses is proposed.     

Isolation of water-soluble alginate from brown algae

Summary Water-soluble alginate was obtained from an aqueous extract of Kjellmaniella crassifolia by precipitation with HCl, calcium acetate or 20% ethanol in the presence of 0.05 M MgCl₂ Of these precipitation procedures, MgCl₂-ethanol gave the purest alginate preparation as judged by electrophoresis. The thin-layer and gas-liquid chromatography of its acid hydrolysate, and the IR spectra analysis of the whole alginate, suggested that the water-soluble alginate is similar to ordinary water-insoluble and alkali-soluble alginate such as Kelco alginate.However, the alginate obtained in the present work contained a great excess of mannuronic acid residues, giving an M:G ratio of about 13. Its molecular weight distribution was rather broad as with Kelco alginate, but the molecular weight of its major component was estimated to be 500 000 amu, whereas that Kelco alginate measured on the same column under the same condition was 1 700 000 amu. This suggests that water-soluble alginate was far smaller in average molecular size than Kelco alginate.     

Differential sensitivity of green algae to allelopathic substances from Chara

Three short-term laboratory experiments were conducted to investigate allelopathic effects of a mixture of Chara globularis var. globularis Thuillier and Chara contraria var. contraria A. Braun ex Kützing on three different green algae. Single phytoplankton species were exposed to filtered water originating from charophyte cultures. Phytoplankton growth was monitored by determination of chlorophyll concentrations in batch cultures. The change in chlorophyll concentration during the experiments was analysed with a logistic growth model, resulting in an estimate of the exponential growth rate and the duration of the lag phase of the single green algae. The results indicate allelopathic effects of Chara on the growth of the green algae Selenastrum capricornutum Printz and Chlorella minutissima Fott et Nováková, whereas Scenedesmus obliquus (Turpin) Kützing did not seem to be affected. The exponential growth rate of S. capricornutum decreased 7% in the presence of water from a charophyte culture, while the growth rate of C. minutissima decreased with 3%. The allelopathic effect of Chara did not increase when the green alga C. minutissima was P-limited. The effect of Chara was different when young sprouts were used. With young sprouts the duration of the lag phase of C. minutissima was extended (25%), whilst for old plants the growth rate of this green alga decreased. Although the inhibiting effect of charophytes on specific phytoplankton species is rather small, the differential sensitivity of the species to Chara might influence the composition and biomass of phytoplankton communities in the field.     

Cadmium uptake by non-viable biomass from a marine brown algaEcklonia radiata turn

Biomass of non-viable and dried brown marine algaeEcklonia radiata Turn. was used to examine its cadmium uptake capability. Twelve different pretreatments on the algal biomass were prepared. Among these pretreatments, the algal biomass, which treated with 0.1 M NaOH and kept in water bath (100°C, 18 h) followed by washing with distilled water and squeezing, showed the highest amount of cadmium uptake as 1634±195 mg/g dry biomass at pH 4.0 and 50°C. Adsorption temperatures and pH levels played some important role in cadmium uptake. However, cadmium uptake decreased dramatically at a lower pH than 4.0. Freundlich adsorption isotherm showed potent cadmium uptake capacity of the non-viable biomass. Pretreatments on the nonviable algal biomass shown in this study may enhance the cadmium removal in the industrial wastewater.     

Association between exudates of brown algae and polychlorinated biphenyls

Exudates from the brown algaeCaepidium antarcticum andDesmarestia sp. were investigated for their ability to associate with hydrophobic pollutants such as polychlorinated biphenyls (PCB s). The percentage of PCB associated with algal exudates ranged from 79% for decachlorobiphenyl to 23% for the pentachlorobiphenyl congener No. 95. Exudates from the tested brown algae may therefore alter the bioavailability of PCBs in natural or artificial ecosystems.     

Inhibitory effects of brown algal phlorotannins on secretory phospholipase A2s, lipoxygenases and cyclooxygenases

The inhibitory effects of brown algal phlorotannins on secretory phospholipase A₂s (sPLA₂s), lipoxygenases (LOXs) and cyclooxygenases (COXs) were determined with an in vitro assay. Oligomers of phloroglucinol; eckol (a trimer), phlorofucofuroeckol A (a pentamer), dieckol (a hexamer) and 8,8-bieckol (a hexamer) isolated from the brown alga Eisenia bicyclis had pronounced inhibitory effects on sPLA₂ from porcine pancreas and bee venom (IC₅₀ 100–200 M). The phlorotannins inhibited LOX activity more effectively than the well-known LOX inhibitors; resveratrol and epigallocatechin gallate. 8,8-Bieckol, the strongest LOX inhibitor in this study, inhibited soybean LOX and 5-LOX with IC₅₀ values of 38 and 24 M, respectively. Negligible or very weak effects of the phlorotannins on COX-1 and COX-2 were found, except for an inhibitory effect of dieckol on COX-1 (74.7%) and of eckol on COX-2 (43.2%) at 100 M.     

Molecular and biochemical studies of virus infections in two filamentous brown algae

The filamentous marine brown algae Ectocarpus siliculosus and Feldmannia simplex are infected by host specific DNA-viruses. Under Percoll isolation, Ectocarpus siliculosus-virus (EsV)-particles maintained their infective potential.The EsV has a circular genome of dsDNA with a size of 320 kb. A restriction map has been established. The gene of a major coat protein (gp1) was detected in a genomic library and partly sequenced. Using gpl- sequences for polymerase chain reaction (PCR) amplification analysis, EsV specific sequences could be detected in various symptom-free, clonal cultures of Ectocarpus. The PCR was also used to follow the passage of the virus genome during the meiosis of hosts. A monospecific antibody against recombinant gpl was used for immunostaining and infection experiments.The Feldmannia simplex-virus (FlexV-1) has a circular genome with a size of 220 kb and a 43% G+C content. FsV-DNA contains methylated bases. 5-methylcytosine (5 mC) makes up 12% of the total cytosines.     

Predicting understorey structure from the presence and composition of canopies: an assembly rule for marine algae

Assembly rules provide a useful framework for predicting patterns of community assembly under defined environmental conditions. Habitat created by canopy-forming algae (such as kelps) provides a promising system for identifying assembly rules because canopies typically have a large and predictable influence on understorey communities. Across >1,000 km of subtidal South Australian coastline, we identified natural associations between assemblages of understorey algae and (1) monospecific canopies of Ecklonia radiata, (2) canopies comprised of E. radiata mixed with Fucales (Cystophora spp. and Sargassum spp.), and (3) gaps among canopies of algae. We were able to recreate these associations with experimental tests that quantified the assembly of understorey algae among these three habitat types. We propose the assembly rule that understorey communities on subtidal rocky coast in South Australia will be (1) monopolised by encrusting coralline algae beneath monospecific canopies of E. radiata, (2) comprised of encrusting corallines, encrusting non-corallines, and sparse covers of articulated corallines, beneath mixed E. radiata-Fucales canopies, and (3) comprised of extensive covers of articulated corallines and filamentous turfs, as well as sparse covers of foliose algae and juvenile canopy-formers, within gaps. Consistencies between natural patterns and experimental effects demonstrate how algal canopies can act as a filter to limit the subsets of species from the locally available pool that are able to assemble beneath them. Moreover, the subsets of species that assemble to subtidal rocky substrata in South Australia appear to be predictable, given knowledge of the presence and composition of canopies incorporating E. radiata.     

Variation in phlorotannin content within two species of brown macroalgae (Desmarestia anceps and D. menziesii) from the Western Antarctic Peninsula

Phlorotannins are metabolites found only in the Phaeophyceae (brown algae) and have a variety of metabolic roles, including both primary (e.g. cell wall construction) and secondary (e.g. herbivore defence and UV protection). This study aimed to establish the level of variation of phlorotannins in two species of dominant Antarctic macroalgae (Desmarestia anceps and D. menziesii). Thirteen samples were taken from specific locations throughout the thallus of multiple individuals at two depths at three locations near Anvers Island, Antarctica. Overall average concentrations were 0.117±0.003 g g^–1dwt in D. anceps and 0.052±0.002 g g^–1dwt in D. menziesii. Concentrations varied greatly at the 13 sampling locations in each individual, but not in any consistent manner. Significant variation occurred between locations in both species and between depths in D. anceps.     

Cytokinesis in brown algae: studies of asymmetric division in fucoid zygotes

Summary. The mechanism of cytokinesis was investigated during the first asymmetric division in fucoid zygotes. A plate of actin assembled midway between daughter nuclei where microtubules interdigitated and defined the cytokinetic plane. A membrane was then deposited in islands throughout the cytokinetic plane; the islands eventually fused into a continuous partition membrane and cell plate material was deposited in the intermembrane space. All of these structures matured from the center of the cell outward (centrifugal maturation). Pharmacological agents were used to investigate the roles of microtubules, actin, and secretion in cytokinesis. The findings indicate a mechanism of cytokinesis that may be unique to the brown algae.Correspondence and reprints: Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840, U.S.A.     

The cell content and secretion of water-soluble vitamins by several freshwater algae

Three green algae, Chlamydomonas reinhardii, Chlorella vulgaris and Scenedesmus obliquus, and one blue-green alga, Anabaena cyclindrica, were grown in chemically defined media. All the algac examined contained folates, -carotene and vitamins C and E; several of the B-vitamins and vitamin A were found in varying amounts in some but not in all the algae examined. All the green algae secreted significant amounts of folate and biotin and all but Scenedesmus secreted pantothenate into their growth medium; Anabaena secreted folate and pantothenate.This work was done with the support of grant BMS 74-08918 from the National Science Foundation     

Combination and positional distribution of fatty acids in lipids from blue-green algae

The main glycerolipids (monogalactosyl-, digalactosyl-, sulphoquinovosyl diacylglycerol, phosphatidylglycerol) from five blue-green algae (Microcystis, Anabaena, Nostoc, Oscillatoria, Tolypothrix) were analyzed for fatty acid composition, occurrence of diglyceride species and positional distribution of fatty acids between thesn-1- andsn-2-position of glycerol. In contrast to eucaryotic plants biosynthetically closely related lipids (monogalactosyl-, digalactosyl-, trigalactosyl diacylglycerol) show nearly identical diglyceride moieties, whereas sulphoquinovosyl diacylglycerol and phosphatidylglycerol are separated from galactolipids by composition as well as occurrence of fatty acids. On the other hand the positional distribution of fatty acids in all lipids is controlled exclusively by chain length and not by degree of unsaturation with C₁₈-fatty acids at thesn-1- and C₁₆-fatty acids at thesn-2-position. These results show that in procaryotic organisms the diversity in diglyceride portions of lipids is reduced as compared to eucaryotic organisms, but nevertheless does exist.Abbreviations MGD, DGD, TGD, SQD monogalactosyl-, digalactosyl-, trigalactosyl-, sulphoquinovosyl diacylglycerol - PG phosphatidyl glycerol     

Adrenal tissue in the male African catfish,Clarias gariepinus: localization and steroid hormone secretion

Interrenal-like tissue in male African catfish is localized in paired organs, situated retroperitoneally anterior of the kidney. Histological and enzyme-histochemical (3-hydroxysteroid dehydrogenase) reactions were carried out on sections of these organs in order to localize steroid-producing cells. In vitro incubations were carried out to determine the steroidogenic capacity of the interrenal-like tissue. Twenty-one steroids could be identified and quantified in the incubation medium, by means of gas chromatography followed by mass spectrometry. Cortisol, 5-and 5-androstanedione and androstenedione together comprised about 80% of the total steroid content. In a previous study, twenty testicular steroids were detected in plasma after castration. In the present investigation we have shown that most of these steroids can be produced by the interrenal-like tissue, which thus can be considered as an extra-testicular source of gonadal steroids.     

Extracellular mannanases and galactanases from selected fungi

Summary Eight thermophilic fungi were tested for production of mannanases and galactanases. Highest mannanase activities were produced byTalaromyces byssochlamydoides andTalaromyces emersonii. Mannanases from all strains tested were induced by locust bean gum except in the case ofThermoascus aurantiacus, where mannose had a greater inducing effect. Locust bean gum was also the best inducer of -mannosidase and galactanase except in the case ofT. emersonii where galactose was a better inducer of both these enzymes. Highest mannanase activity was produced byTalaromyces species when peptone was used as nitrogen source whereas sodium nitrate promoted maximum production of this enzyme byThielavia terrestris andT. aurantiacus. The pH optima of mannanases from the thermophilic fungi were in the range 5.0–6.6 and contrasted with the low pH optimum (3.2) of the enzyme fromAspergillus niger. Galactanases had pH optima in the range 4.3–5.8. The mannanase fromT. emersonii and the galactanase fromT. terrestris were most thermostable, each retaining 100% activity for 3 h at 60°C.     

Detection of cholesteryl ester hydroperoxide isomers using gas chromatography-mass spectrometry combined with thin-layer chromatography blotting

Oxidative modification of low-density lipoprotein (LDL) has been implicated in the pathogenesis of atherosclerosis. During the oxidation of LDL, cholesteryl esters, the major lipid components in LDL, are oxidized to cholesteryl ester hydroperoxides (CEOOH). The isomers of CEOOH may reflect the reactive species that initiate the peroxidation reaction. In the current study, a novel analytical method for the determination of CEOOH isomers, especially cholesteryl linoleate hydroperoxide isomers, was developed using the combination of two chromatographic techniques: (i) thin-layer chromatography blotting with diphenyl-1-pyrenylphosphine (DPPP) fluorescent detection (DPPP-TLC blotting) and (ii) gas chromatography-electron ionization-mass spectrometry (GC-EI-MS). CEOOH was applied to DPPP-TLC blotting, the obtained DPPP-derived fluorescent spots containing cholesteryl ester hydroxides were extracted and derivatized (hydrogenation, transmethylation, and trimethylsilylation), and the formed methyl ester/trimethylsilylether derivatives of hydroxyoctadecenoic acid were then analyzed by GC-EI-MS. The CEOOH isomers were determined by selected ion monitoring of isomer-specific fragment ions originated from the alpha-cleavage of the trimethylsilyloxyl group. Using these two chromatographic techniques, we were able to detect isomeric CEOOH in the oxidized human LDL. Our results indicated that GC-EI-MS analysis combined with DPPP-TLC blot is a specific method for analyzing cholesteryl ester hydroperoxide isomers in biological samples such as oxidized LDL.     

Virus infections in three marine brown algae: Feldmannia irregularis,F. simplex,and Ectocarpus siliculosus

Culture studies with healthy and virus-infected isolates of Ectocarpus siliculosus, Feldmannia simplex and F. irregularis gave the following results: