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At least 19 recordsLinked to original sources
PubMed1988

Qualitative and quantitative determination of pheromone secretion in female gametes of Ectocarpus siliculosus (Phaeophyceae).

Pheromone secretion in living female gametes of Ectocarpus siliculosus was examined by closed-loop extraction and gas chromatography. The pheromone (ectocarpene) recovery efficiency was calibrated with synthetic ectocarpene and was found to depend strongly on the volume of the closed-loop system. Maximum extraction efficiency of ectocarpene (17.4%) was obtained with a small-volume system. In addition to the main compound ectocarpene, the pheromone bouquet of E. siliculosus contained minor amounts of hormosirene, multifidene and dictyotene, which until now are known only as sperm-attractants in other brown algae. The pheromone bouquet was identical in 4 clones of different geographic origins. Settled female gametes of Ectocarpus siliculosus continued to secrete pheromone and to attract male gametes for up to 7 h after their release with an ectocarpene secretion rate of 1 x 10(5) molecules s-1 cell-1.

Chromatography, Gas↗
PubMed1990

Rubisco genes indicate a close phylogenetic relation between the plastids of Chromophyta and Rhodophyta.

The genes for both subunits of Rubisco (rbcL, rbcS) are located on the plastome of the brown alga Ectocarpus siliculosus (Chromophyta, Phaeophyceae). The organization of these genes in the form of an operon was similar to that found in rhodoplasts, cyanobacteria and the plastids of Cryptomonas phi. Sequence analysis of the complete operon revealed a high degree of homology and great structural similarities to corresponding genes from two red algae. In contrast, sequence homology to Rubisco genes from chloroplasts and cyanobacteria was much lower. This clearly indicated a close phylogenetic relationship between the plastids of Rhodophyta and Chromophyta which seem to have evolved independently from the chloroplasts (polyphyletic origin). Our data suggest that the plastids of Chromophyta and Cryptophyta have originated from endosymbiotic unicellular red algae. Surprisingly, red and brown algal Rubiscos show a significantly higher degree of homology to that from a hydrogen bacterium than to those from cyanobacteria.

Amino Acid Sequence↗
PubMed1976

Cyclic condensed metaphosphates and linear polyphosphates in brown and red algae.

The occurrence of linear condensed polyphosphates and cyclic condensed metaphosphates was studied by means of pulse-labeling with 32P-orthophosphate (3--5h) in a number of Phaeophyceae species: Pylaiella litoralis, Ilea fascia, Ectocarpus siliculosus and also Rhodophyceae species: Ceramiumdeslongchampsii, C. rubrum, Rhodomela confervoides, Porphyridium purpureum and P. aerugineum. Two-dimensional cellulose thin layer chromatography revealed that in all species studied 32P-radioactivity was generally present in all oligopolyphosphates containing 2 to 7 phosphate residues, in cyclic metaphosphates (tri-, tetra-, penta- and hexametaphosphates) and in high-molecular-weight condensed phosphates which remained at the starting point. Among the low-molecular-weight condensed inorganic phosphates the trimetaphosphate had a significantly higher specific activity than the other oligophosphates which were separated on the chromatography plates as measured by the direct scanning with a Geiger-Muller counter. The phosphate uptake strongly depends on the internal pool of reserve phosphates of the algae cells. The 32P-orthophosphate incorporation of the cells is low and sluggish when growning in a synthetic medium or in sea water. Accordingly 32P appeared preferentially in the low-molecular-weight fractions of condensed phosphates since the storage phosphates were not yet used. After previous incubation in a P-free culture medium of the algae the 32P was rather rapidly incorporated and was found mostly in the high-molecular-weight condensed phosphates. During MAK-chromatography the high-molecular-weight fractions were eluted together with the nucleic acids (tRNA and DNA) while most of the low-molecular-weight fractions left the column immediately on elution.

Eukaryota↗
PubMed1985

Biosynthesis of algal pheromones. A model study with the composite Senecio isatideus.

Several cyclic and alicyclic C11 hydrocarbons have been shown to act as gamete releasing and/or attracting pheromones during sexual reproduction of brown algae (Phaeophyceae). The same compounds are also found in the essential oils of various plants, of which the occurrence of the cycloheptadiene-pheromone ectocarpene in Senecio isatideus (Compositae) is noteworthy. Administration of [3H]dodeca-3,6,9-trienoic acid to cuttings of this plant leads to incorporation of radioactivity into ectocarpene. Double-bond-deuterated nona-3,6-dienoic acid is converted to fucoserratene, the pheromone of several Fucales, which is certainly not present among the hydrocarbons of Senecio. This proves that the pool of medium-chain, multiply unsaturated fatty acids includes precursors of all types of highly unsaturated hydrocarbons. Appropriately labelled (deuterium markers) fatty acid homologues were synthesized and applied to Senecio plantlets to unravel the mechanistic aspects. The results strongly suggest radical initiation of the pheromone biosynthesis by abstraction of a single hydrogen from a 1,4-pentadienyl segment of the fatty acid followed by oxidation to the corresponding cation. This causes fragmentation of the reactive intermediate into an olefine and carbon dioxide by neighbouring-group participation of the flanking double bonds. A tentative biosynthetic scheme is deduced from the experimental results which also sets the stereochemistry of the algal pheromones into a uniform mechanistic concept.

Animals↗
PubMed1975

Polysaccharide production and the possible occurrence of GDP-D-mannose dehydrogenase in Azotobacter vinelandii.

During the growth of Azotobacter vinelandii in batch culture in Burk's 2% glucose medium supplemented with 50 mg EDTA per litre, water-insoluble capsular polysaccaride material accumulated in cultures prior to the appearance of water-soluble polysaccharide in the culture medium. On isolation, hydrolysis and chromatography, both these polysaccharides were observed to be composed of carbohydrate monomers having the same chromatographic mobilities as glucose, rhamnos, guluronic acid and mannuronic acid. The activity of GDP-D-mannose dehydrogenase recorded in crude cell-free extracts from Azotobacter vinelandii, when these polysaccharides were produced, may indicate a close similarity between the biosynthetic pathway of alginate synthesis in marine Phaeophyceae and this soil microorganism.

Alcohol Oxidoreductases↗
PubMed1979

The route of entry of cytoplasmically synthesized proteins into chloroplasts of algae possessing chloroplast ER.

In 8 classes of algae, namely the Cryptophyceae, Raphidophyceae, Haptophyceae, Chrysophyceae, Bacillariophyceae, Xanthophyceae, Eustigmatophyceae and Phaeophyceae, the chloroplasts, in addition to being surrounded by a double-membraned chloroplast envelope, are also enclosed by a cisterna of endoplasmic reticulum called the chloroplast ER. Often this ER cisterna is continuous with the outher membrane of the nuclear envelope in such a manner that the nuclear envelope forms a part of the ER sac enclosing the chloroplast. In all these classes of algae except the Cryptophyceae, a regular network of tubules and vesicles, named the periplastidal reticulum, is present at a specific location between the chloroplast envelope and the chloroplast ER. In the Cryptophyceae, scattered vesicles are found between the chloroplast envelope and the chloroplast ER. Ribosomes which have been shown to be arranged to polysomes are found on the outer membrane of the chloroplast ER. It is proposed that nuclear-coded proteins which are destined for the chloroplast are synthesized on these polysomes, passing during synthesis into the lumen of the ER cisterna. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles containing these proteins then pinch off the chloroplast ER and form the periplastidal reticulum. Vesicles then fuse with the outer membrane of the chloroplast envelope thereby delivering their contents to the lumen of the chloroplast envelope. Proteins then cross the inner membrane of the chloroplast envelope in an as yet unknown manner. Experimental evidence for this hypothesis comes from studies on Ochromonas danica using chloramphenicol and spectinomycin, which inhibit protein synthesis on plastid ribosomes, and cycloheximide, which inhibits protein synthesis on cytoplasmic ribosomes. In cells of Ochromonas exposed to chloramphenicol or spectinomycin, the periplastidal reticulum proliferates markedly becoming several layers thick. Presumably this build up of periplastidal reticulum occurs because the transport of cytoplasmically synthesized plastid proteins is slowed down when protein synthesis in the chloroplast is inhibited. Conversely, when cells of Ochromonas are treated with cycloheximide, there is a reduction in the amount of periplastidal reticulum presumably because there are no cytoplasmically synthesized proteins to be transported into the chloroplast.

Biological Transport↗
PubMedDate not supplied

Chlorophyll-protein complexes of brown algae: P700 reaction centre and light-harvesting complexes.

Thylakoid membranes from several brown algae have been fragmented with the non-ionic detergent, Triton X-100. Three intrinsic chlorophyll-protein complexes with different pigment compositions have been isolated by sucrose density gradient centrifugation. Brown algae contain the photosystem 1 reaction-centre complex, a P700-chlorophyll a-protein which has similar spectroscopic and chemical properties to those of higher plants. This complex represents about 10--20% of the total chlorophyll in all species; the Acrocarpia paniculata complex has a chlorophyll/P700 ratio of 38. Two main light-harvesting complexes have also been isolated, which have properties unique to brown algae. The heavier of these, an orange fraction, is a fucoxanthin-chlorophyll a/c-protein; this complex contains most of the fucoxanthin and has only chlorophyll c2. The other, a green fraction, is a chlorophyll a/c-protein enriched in violaxanthin. Neither of these complexes possesses detectable photosystem 1 or photosystem 2 activities. Both of these complexes efficiently transfer light energy to chlorophyll a, indicating that the molecular arrangement of their pigments is similar to that in vivo. Differential extraction of thylakoid membranes indicates that the P700-chlorophyll a-protein is the complex most firmly embedded in the membrane, but the fucoxanthin-chlorophyll a/c-protein is the least firmly bound. We suggest that the fucoxanthin complex is the most variable component of the photosynthetic unit of brown algal chloroplasts.

Cell Membrane↗
PubMed1990

Native bromoperoxidases do not bind to nitrocellulose: use of DEAE-cellulose as an alternative in blotting.

Bromoperoxidases were investigated by protein blotting after polyacrylamide gel electrophoresis. While the denatured proteins bound to nitrocellulose, the native enzymes did not. Instead, they could be transferred successfully to DEAE-cellulose. Procedures for immunostaining and glycoprotein detection with concanavalin A on DEAE-cellulose are described. The results indicate that binding of native proteins to nitrocellulose can not necessarily be assumed. DEAE-cellulose is suitable both to investigate this phenomenon or as a substitute for nitrocellulose in blotting of native proteins.

Blotting, Western↗
PubMed1978

Clostridial sepsis after abortion with PGF2alpha and intracervical laminaria tents--a case report.

A case of clostridial endomyometritis and sepsis necessitating total abdominal hysterectomy which occurred 12 hours following abortion induced with intraamniotic administration of prostaglandin F2 alpha and laminaria tent insertion is discussed. Cultures from cervical, blood, and surgical specimens all yielded Clostridium perfringens. Intrauterine contamination with this microorganism most likely followed the insertion of laminaria tents through the cervical os, which was colonized with C. perfringens. Since C. perfringens may be present in the microflora of the lower female genital tract, great care must be taken to cleanse this area prior to intracervical laminaria tent insertion.

Abortion, Induced↗
PubMed1978

The potential reduction of medical complications from induced abortion.

Reducing medical complications resulting from induced abortion by identifying the safest and most appropriate procedures(s) for each gestational age is the purpose of this study. Data on all women who had induced abortions at all hospitals in the State of Hawaii where such procedures were performed between March 11, 1970, when the new abortion law went into effect, and June 30, 1974 were analyzed. Study findings show that if the abortion procedure with the least risk of complications at each length of gestation were selected a reduction in the complication rate of nearly 30% could result.

Abortion, Induced↗
PubMed1992

Nucleotide sequence and phylogenetic implication of the ATPase subunits beta and epsilon encoded in the chloroplast genome of the brown alga Dictyota dichotoma.

We have cloned and sequenced the genes atpB and atpE, coding for CF1 subunits beta and epsilon, respectively, of the chloroplast genome of the brown alga Dictyota dichotoma. Although the coding site of atpE cannot be demonstrated by heterologous Southern hybridizations, a 417 bp reading frame 3' to atpB was identified as the gene atpE by sequence similarities with atpE genes from other sources. A maximum sequence identity of 30% is found between the predicted amino acid sequence of the Dictyota subunit epsilon and the corresponding cyanobacterial subunits. Including conserved amino acid replacements, the Dictyota epsilon subunit exhibits about 70% sequence similarity with the cyanobacterial and land plant subunits. As in cyanobacteria, the atpE gene does not overlap the preceding gene atpB. The deduced amino acid sequence of atpB is 74-79% identical to the corresponding cyanobacterial and chloroplast subunits. Entirely conserved are regions referred to as the catalytic and/or regulatory sites of ATP formation, including interacting regions between subunits alpha and beta. A phylogram predicted from F1/CF1-beta subunits of eleven different organisms suggests a common evolutionary origin of plastids from chlorophytes and brown algae.

Amino Acid Sequence↗