Evidence for numerous analogs of yessotoxin in Protoceratium reticulatum

A solid-phase extract from Protoceratium reticulatum was partitioned between water and butanol and the two fractions purified on an alumina column. Fractionation was monitored by ELISA and LC–MS. Results indicate that while almost all yessotoxin (1) was extracted into butanol, large amounts of yessotoxin analogs remained in the aqueous extract along with lesser amounts in the butanolic extract. NMR analysis of selected fractions from reverse-phase chromatography of the extracts confirmed the presence of yessotoxin analogs, although structure determinations were not possible due to the complexity of the mixtures. Analysis of fractions with LC–MS³ and neutral-loss LC–MS/MS indicated the presence of more than 90 yessotoxin analogs, although structures for most of these have not yet been determined. These analogs provide a mechanism to rationalise the discrepancy between ELISA and LC–MS analyses of algae and shellfish.     

Mathematical description of yessotoxin production by Protoceratium reticulatum in culture

The production dynamics of yessotoxin (YTX) by Protoceratium reticulatum and phosphate uptake in culture were investigated in relation to cell growth. The equations used were: the reparametrized logistic for cell production, Luedeking–Piret model for yessotoxin production and maintenance energy model for phosphate consumption. Thus, the YTX formation rate was proportional to producer biomass at the end of the asymptotic phase of culture as a secondary metabolite. Moreover, the equations proposed showed a high accuracy to predict these bioproductions in different experimental conditions and culture scales.     

Effects of Protoceratium reticulatum yessotoxin on feeding rates of Acartia hudsonica: A bioassay using artificial particles coated with purified toxin

Paralytic shellfish toxins produced by dinoflagellates are known to deter copepod grazing. Dinoflagellate species, including Protoceratium reticulatum, also produce disulfated polyether yessotoxins that were previously referred to as diarrheic shellfish toxins. However, the role of yessotoxins in predator–prey relationships is not yet clear. In the present study, the effects of purified yessotoxin (YTX) on feeding activities of Acartia hudsonica (Copepoda, Calanoida) were experimentally investigated. Polystyrene fluorescent microspheres (10 μm in diameter) colored bright blue or yellow-green were coated with cell extracts of P. reticulatum that do not produce yessotoxins. The bright blue microspheres were further coated with YTX, and the yellow-green microspheres were used as the reference. The microspheres were then given to the copepods separately or in combination to measure clearance rates and feeding selectivity. A. hudsonica was found to feed on the yellow-green microspheres without YTX at twice the rate of the bright blue microspheres with YTX. We also confirmed that microsphere color per se did not affect the feeding rates. The bright blue microspheres adsorbed 1.8–43.3 pg of YTX per microsphere, which is similar to the cell-specific yessotoxin content of toxic P. reticulatum found in natural environments. These results suggest that production of yessotoxin is advantageous for P. reticulatum by deterring predation by copepods.     

Yessotoxin detected in mussel (Mytilus californicus) and phytoplankton samples from the U.S. west coast

Yessotoxin (YTX) was detected in an algal sample and two mussel samples (0.07–0.10 μg g⁻¹) collected from Scripps Pier in La Jolla, California during a bloom of Lingulodinium polyedrum. Mussel samples collected from Monterey Bay, California also contained measurable YTX (levels up to 0.06 μg g⁻¹) in samples obtained during a 6-month (weekly) sampling period. Gonyaulax spinifera and L. polyedrum were identified in background concentrations in Monterey Bay during the time of contamination. An algal sample from Washington coastal waters collected during non-bloom conditions also contained YTX, possibly originating from Protoceratium reticulatum.Three strains of L. polyedrum (CCMP1931, CCMP1936, 104A) isolated from southern California coastal waters and one strain of G. spinifera (CCMP409) isolated from Maine were tested for YTX production using two methods, competitive ELISA and liquid chromatography–mass spectrometry (LC–MS). The ELISA method detected YTX in the particulate phase in two of three L. polyedrum strains. The LC–MS method did not detect YTX in the particulate or dissolved phase of any of the strains.To our knowledge, this is the first study to test and confirm YTX in environmental samples from California and Washington coastal waters. It is highly likely that L. polyedrum was responsible for the YTX contamination in the southern California samples. Future research needs to conclusively determine the biological origin(s) of YTX contamination in central California and Washington coastal waters.     

Molecular phylogenetic studies show Omphalina giovanellae represents a new section of Clitopilus (Agaricomycetes)

After reconsidering the specific characters of Omphalia giovanellae and applying data from the sequences of the D1–D2 domain of the 28S rRNA gene and the ITS region of material collected in Italy and Spain, the species is ascribed to the genus Clitopilus. Considering the rather peculiar characters, especially the smooth spores, C. giovanellae is ascribed to the new section Omphaloidei sect. nov. The species is illustrated with drawings of fresh basidiomata observed in situ, as well as with SEM micrographs of the spores. Also based on DNA sequence data, O. farinolens, recently described from Spain, is shown to be a synonym of C. giovanellae.     

Antitumor agents 269. Non-aromatic ring-A neotanshinlactone analog, TNO, as a new class of potent antitumor agents

Tetrahydroneotanshinlactone (TNT) and tetrahydronaphthalene-1-ol (TNO) derivatives were designed, synthesized, and evaluated for cytotoxic activity. The TNO derivatives were found to be a promising novel class of in vitro antitumor agents. The cyclohexene ring-A could dramatically affect the antitumor activity and selectivity. Compound 20 showed the highest potency with ED₅₀ values of 0.7 and 1.7 μM against SK-BR-3 and ZR-75-1 breast cancer cell lines, respectively.     

Cesariella, a new genus of Laboulbeniales

Cesariella graeca gen. sp. nov. is described to accommodate a new species of the Laboulbeniales (Fungi, Ascomycota) parasitic on the endogean ground beetles Reicheadella aetolica and R. bischoffi (Coleoptera, Carabidae) from Greece. Cesariella is distinguished from the allied genus Laboulbenia by the presence of two cells borne on the inner side of cell III, and by the presence of a conspicuous remnant of the spore apex protruding laterally near the base of the appendage.     

Inactivation of SSM4, a new Saccharomyces cerevisiae gene, suppresses mRNA instability due to rna14 mutations

Decay rates of mRNAs depend on many elements and among these, the role of the poly(A) tail is now well established. In the yeast Saccharomyces cerevisiae, thermosensitive mutations in two genes, RNA14 and RNA15, result in mRNAs having shorter poly(A) tails and reduced half-life. To identify other components interacting in the same process, we have used a genetic approach to isolate mutations that suppress the thermosensitivity of an rna14 mutant strain. Mutations in a single locus, named SSM4, not only suppress the cell growth phenotype but also the mRNA instability and extend the short mRNA poly(A) tails. The frequency of appearance and the recessive nature of these mutations suggested that the suppressor effect was probably due to a loss of function. We failed to clone the SSM4 gene directly by complementation, owing to its absence from gene banks; it later emerged that the gene is toxic to Escherichia coli, but we have nevertheless been able to clone the SSM4 sequence by Ty element transposition tagging. Disruption of the SSM4 gene does not affect cell viability and suppresses the rna14 mutant phenotypes. The protein encoded by the SSM4 gene has a calculated molecular mass of 151 kDa and does not contain any known motif or show homology with known proteins. The toxicity of the SSM4 gene in E. coli suggests that a direct biochemical activity is associated with the corresponding protein.     

Isolation and characterization of a new gene, sre , which encodes a GATA-type regulatory protein that controls iron transport in Neurospora crassa

Multiple GATA factors – regulatory proteins with consensus zinc finger motifs that bind to DNA elements containing a GATA core sequence – exist in the filamentous fungus Neurospora crassa. One GATA factor, NIT2, controls nitrogen metabolism, whereas two others, WC-1 and WC-2, regulate genes responsive to blue light induction. A gene encoding a new GATA factor, named SRE, was isolated from Neurospora using a PCR-mediated method. Sequence analysis of the new GATA factor gene revealed an ORF specifying 587 amino acids, which is interrupted by two small introns. Unlike all previously known Neurospora GATA factors, which possess a single zinc-finger DNA-binding motif, SRE contains two GATA-type zinc fingers. The deduced amino acid sequence of SRE shows significant similarity to URBS1 of Ustilago and SREP of Penicillium. A loss-of-function mutation was created by the RIP procedure. Analysis of sre ⁺ and sre ⁻ strains revealed that SRE acts as a negative regulator of iron uptake in Neurospora by controlling the synthesis of siderophores. Siderophore biosynthesis is repressed by high iron concentrations in the wild-type strain but not in sre ⁻ mutant cells. The sre promoter contains a number of GATA sequences; however, expression of sre mRNA occurs in a constitutive fashion and is not regulated by the concentration of iron available to the cells. Received: 20 January 1998 / Accepted: 23 April 1998     

Vasicol,a new alkaloid from Adhatoda vasica

A novel alkaloid isolated from the roots of Adhatoda vasica has been characterized as 1,2,3,4,9,11 hexahydro pyrrolo (2,1-b) quinazolin-3,11 diol by chemical and spectroscopic methods. Vasicinone has also been isolated from the roots of this plant.     

Malonichrome,a new iron chelate from Fusarium roseum

The predominant iron chelates, or siderochromes, produced by the fungus, Fusarium roseum during culture periods up to seven days are the ester type fusarinine compounds. During longer periods of incubation, the fusarinine compounds completely disappear from the culture medium and are replaced by a new siderochrome. The new compound has been isolated, purified, and its structure determined. It is a cyclic hexapeptide containing one residue of l-alanine, two residues of glycine and three residues of δ-N-hydroxyornithine. The hydroxylamino groups of the ornithine residues are acylated with 3 mol of malonic acid to form a negatively charged ferrichrome type chelate. The circular dichroism spectrum indicates that the stereochemistry about the iron is Λ-cis. This compound, which we name malonichrome, is not an efficient iron donor to F. roseum nor does it show growth factor activity towards Arthrobacter flavescens.     

ATP:AMP phosphotransferase activity, a new characteristic of Catharanthus roseus tonoplasts

The ATPase activity of Catharanthus roseus tonoplasts was examined using HPLC separation and quantification of adenine nucleotides. ATP seemed to be degraded into ADP and AMP by tonoplast vesicles. When ADP was the initial substrate, the appearance of AMP and concomitant ATP synthesis were observed; these reactions were inhibited by Ap⁵A. The apparent degradation of ATP into AMP was also inhibited by Ap⁵A. These results indicated that AMP arose from an ATP:AMP phosphotransferase activity and excluded the possibility of the hydrolysis of ADP into AMP by the tonoplast ATPase. AMP was degraded by the microsomal fraction from protoplasts or by the cytosol while the tonoplast vesicles did not hydrolyze it. This observation was used to assess the purity of tonoplasts.     

Enantioselective hydrolysis of (R,S)-naproxen 2,2,2-trifluoroethyl ester in water-saturated solvents via lipases from Carica pentagona Heilborn and Carica papaya

A crude lipase prepared from Carica pentagona Heilborn latex was explored as an effective enantioselective biocatalyst for the hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl ester in water-saturated organic solvents. Comparisons of the enzyme performance with that from Carica papaya lipase indicated that both lipases showed low tolerance to the hydrophilic solvent and were inhibited by (S)-naproxen and 2,2,2-trifluoroethanol. Improvements on the enzyme activity and enantioselectivty were demonstrated when both lipases in partially purified forms were employed. By using the thermodynamic analysis, the enantiomeric discrimination was mainly driven by the difference of activation enthalpy for all reaction systems except for employing Carica papaya lipase as the biocatalyst for (R,S)-fenoprofen 2,2,2-trifluoroethyl thioester.