Amino acid sequence of myoglobin from the mollusc Dolabella auricularia

The complete amino acid sequence of the myoglobin from Dolabella auricularia, a common gastropodic mollusc on the Japanese coast, has been determined. The myoglobin is composed of 146 amino acid residues, is acetylated at the NH2 terminus, and contains a single histidine residue at position 95 which most likely corresponds to the heme-binding proximal histidine. The sequence of Dolabella myoglobin shows strong homology (72-77%) with those of Aplysia myoglobins. The autoxidation rate of Dolabella oxymyoglobin (MbO2) was examined in 0.1 M buffer at 25 degrees C over pH range 4.8-12. Dolabella MbO2 was extremely unstable between pH 7 and 11, and the pH dependence of the stability was quite different from that of sperm whale MbO2. This property may be partly due to the absence of a distal (E7) histidine in Dolabella myoglobin.     

Unexpected fine-scale population structure in a broadcast-spawning Antarctic marine mollusc

Several recent empirical studies have challenged the prevailing dogma that broadcast-spawning species exhibit little or no population genetic structure by documenting genetic discontinuities associated with large-scale oceanographic features. However, relatively few studies have explored patterns of genetic differentiation over fine spatial scales. Consequently, we used a hierarchical sampling design to investigate the basis of a weak but significant genetic difference previously reported between Antarctic limpets (Nacella concinna) sampled from Adelaide and Galindez Islands near the base of the Antarctic Peninsula. Three sites within Ryder Bay, Adelaide Island (Rothera Point, Leonie and Anchorage Islands) were each sub-sampled three times, yielding a total of 405 samples that were genotyped at 155 informative Amplified Fragment Length Polymorphisms (AFLPs). Contrary to our initial expectations, limpets from Anchorage Island were found to be subtly, but significantly distinct from those sampled from the other sites. This suggests that local processes may play an important role in generating fine-scale population structure even in species with excellent dispersal capabilities, and highlights the importance of sampling at multiple spatial scales in population genetic surveys.     

Biology of a problematic marine fungus,dermocystidium sp.

Summary The life cycle of a nonfilamentous marine phycomycete, Dermocystidium sp., is described from its growth in axenic culture under controlled conditions. Reproduction occurs by vegetative means involving a process of cell enlargement and ecdysis modifiable by the methods of cultivation. Zoospores and sexuality were not observed. The results of inoculation studies with algae, phanerogam debris, and molluscs suggest that the fungus may be a free-living saprophyte in coastal waters.     

Enzymatic syntheses and selective hydrolysis of O-beta-D-galactopyranosides using a marine mollusc beta-galactosidase

The use of crude extract of the hepatopancreas of Aplysia fasciata, a large mollusc belonging to the order Anaspidea containing a beta-galactosidase activity, was reported for the synthesis of different galactosides. Good yields with polar acceptors and the uncommon beta-1-3 selectivity in the transgalactosylation reactions with most of the acceptors were observed. A beta-1-2 selectivity in the hydrolytic conditions was also observed and discussed.     

Enkephalins increase dopamine levels in the CNS of a marine mollusc.

Intracardiac administration of methionine enkephalin and leucine enkephalin increased dopamine but not serotonin levels in the CNS of the marine mollusc $\text{Mytilus}$$\text{edulis}$. Naloxone blocked the effects of the enkephalins. These responses displayed a time dependent desensitization to methionine enkephalin. The study suggests the presence of an opiate receptor mechanism in this invertebrate species.     

Macrolactin W, a new antibacterial macrolide from a marine Bacillus sp

Bioactivity-guided isolation for the new/novel metabolites from the EtOAc extract obtained from the culture broth of a marine Bacillus sp. 09ID194 followed by chromatographic fractionations and subsequently HPLC purifications led to the isolation of two known macrolides, macrolactins A (1) and Q (2), together with a new glycosylated marcrolide, macrolactin W (3). The chemical structures of compounds 1-3 were assigned based on extensive MS and NMR spectral data analysis and literature review. Compound 3 showed potent antibacterial activity against both Gram-positive and Gram-negative pathogenic bacteria.     

Isolation and structure of a cytotoxic epoxy sterol from the marine mollusc Planaxis sulcatus

A novel epoxy sterol isolated from the marine mollusc Planaxis sulcatus has been identified as 9 alpha,11 alpha-epoxycholest-7-ene-3 beta,5 alpha,6 beta-triol by spectrometric methods.     

Production of RNA by a marine photosynthetic bacterium, Rhodovulum sp.

The marine photosynthetic bacterium, Rhodovulum sp. PS88, produces RNA not only in cells but also as an extracellular polymeric substance during aerobic continuous cultivation in the dark. At a dilution rate of 0.32–0.5 h^–1, the maximum RNA production was 460 mg RNA l^–1 broth (200 mg RNA g^–1 suspended solids) which is a value about 2–3 times more than that of yeast cells.     

Cellulases, hemicelluloses and auxin-stimulated growth: a possible relationship

The plant growth promoter, auxin, may loosen the primary cell wall by increasing the activity of extracellular cellulases – a group of enzymes that cleave hemicellulose chains in the walls of both monocotyledons and dicotyledons. Evidence is reviewed that suggests that these hemicellulose chains tether adjacent microfibrils, and that by cleaving such chains the cellulases facilitate cell expansion. On the basis of this structural arrangement a mechanism for elastic and plastic wall extension is proposed.     

Sequestration of dietary alkaloids by the spongivorous marine mollusc Tylodina perversa

Specimens of the spongivorous Mediterranean opisthobranch Tylodina perversa that had been collected while feeding on Aplysina acerophoba were shown to sequester the brominated isoxazoline alkaloids of their prey. Alkaloids were stored in the hepatopancreas, mantle tissues, and egg masses in an organ-specific manner. Surprisingly, the known sponge alkaloid aerothionin which is found only in A. cavernicola but not in A. aerophoba was also among the metabolites identified in wild caught specimens of T. perversa as well as in opisthobranchs with a documented feeding history on A. aerophoba. Mollusc derived aerothionin is postulated to be derived from a previous feeding encounter with A. cavernicola as T. perversa was found to freely feed on both Aplysina sponges in aquarium bioassays. The possible ecological significance of alkaloid sequestration by T. perversa is still unknown.     

Puupehanol,a sesquiterpene-dihydroquinone derivative from the marine sponge Hyrtios sp.

Puupehanol (1), a new sesquiterpene-dihydroquinone derivative, was isolated from the marine sponge Hyrtios sp., along with the known compounds puupehenone (2) and chloropuupehenone (3) that are responsible for the antifungal activity observed in the extract. The structure of 1 was established as (20R,21R)-21-hydroxy-20,21-dihydropuupehenone by extensive spectroscopic and computational methods. Compound 2 exhibited potent activity against Cryptococcus neoformans and Candida krusei with MFCs of 1.25 and 2.50 μg/mL, respectively.     

Fatty acid oxidizing activity in a red marine alga, Porphyra sp

A crude enzyme solution prepared from fronds of Porphyra sp. showed remarkable oxygen uptake activity when linoleic acid was added as a substrate. Fatty acid oxidizing activity was mainly present in the soluble fraction of the crude homogenate. The activity was purified 769-fold from mature fronds by ammonium sulfate fractionation, ion-exchange and hydrophobic chromatography. SDS-PAGE analysis of the purified proteins indicated that its subunit size was about 13 kDa. Gel filtration chromatography equipped with a photodiode array detector revealed that the activity was associated with a protein having a molecular weight of 12,500-13,000. It eluted with a chromophore having the maximum absorbance at 417 nm, thus, the protein was suggested to be a heme protein. The spectrophotometric property of the protein was highly similar to that of cytochrome c suggesting that it has heme c as a prosthetic group. The protein showed highest oxygenation activity against linoleic acid, and alpha-linolenic acid and arachidonic acid followed, but oleic acid could not be oxidized. From linoleic acid the protein formed 9- and 13-hydroperoxides to the same extent, and both were shown to be racemic. These results showed that the oxidizing activity is accountable to a cytochrome, but not to a typical lipoxygenase.     

Outdoor cultivation of a nitrogen-fixing marine cyanobacterium,Anabaena sp. ATCC 33047

Optimization of conditions for outdoor production of the nitrogen-fixing cyanobacterium Anabaena sp. ATCC 33047 has been pursued. In open ponds operated under semi-continuous regime biomass productivity values achieved ranged from 9 g (dry weight) m(-2) per day, in winter, to over 20 g m(-2) per day, in summer, provided that key operation parameters, including cell density, were optimized. Under these conditions the efficiency of solar energy conversion by the cells was fairly constant throughout the year, with photosynthetic efficiency values higher than 2%. The cyanobacterial biomass was rich in high-value phycobiliproteins, namely allophycocyanin and phycocyanin, for which open cultures of marine Anabaena represent a most interesting production system. The performance of Anabaena cultures operated under continuous regime in a closed tubular reactor has also been assessed outdoors, in winter. Biomass productivity values similar to those obtained in the ponds have been recorded for the closed system. Additionally, under these conditions, the cells excreted to the medium large amounts of a previously characterized exopolysaccharide, at production rates as high as 35 g m(-2) per day (1.4 g l(-1) per day). Properly operated closed cultures of this strain of Anabaena appear most suitable for outdoor mass production of valuable extracellular polysaccharides.