Fusarium udum as a mycoparasite ofMortierella subtilissima

Summary Fusarium udum was found to be a mycoparasite ofMortierella subtilissima which is a new record. Formation of chlamydospores byF. udum insideM. subtilissima was observed as a result of mycoparasitism.     

Change in striation density and systematics ofCocconeis scutellum var.Ornata (Bacillariophyceae)

Cocconeis scutellum var.ornata Grun. from three localities of Japan was studied. The striation density in 10 μm showed a marked tendency to increase with the decrease of the valve length in both raphe and rapheless valves, and this tendency did not vary with locality or environmental condition. The striation densities of rapheless valves were 4–6 in 10 μm for a valve length of 40μm, 4–6.5 for 30 μm, 6–9 for 20μm and 6.5–11 for 15μm. Those of raphe valves were 10–11 in 10μm for a valve length of 40μm, 10–12 for 30μm, 11–14.5 for 20μm and 12.5–17 for 15μm. According to the range of changing value in striation density obtained by the present study,C. scutellum var.schmidti Frenguelli andC. japonica Schmidt are identical withC. scutellum var.ornata. Dedicated to Prof. Munenao Kurogi on the occasion of his academic retirement. Culture experiment in the present study was undertaken at the Institute of Algological Research, Faculty of Science, Hokkaido University at Muroran.     

Observations on Cymbella mexicana (Ehrenb.) Cleve var. mexicana (Bacillariophyceae) with special reference to the band structure

Cymbella mexicana (Ehrenb.) Cleve var. mexicana was collected from Tama-gawa (Tama River), Tokyo. The fine structure of the species was examined by scanning electron microscopy (SEM), with special reference to colony formation and band morphology. A mature cingulum of this species is usually composed of four open bands. The correlation between the position of the second band (B2) of the cingulum and the attaching pole of the frustule is discussed.     

Heterologous expression, refolding and functional characterization of two antifreeze proteins from Fragilariopsis cylindrus (Bacillariophyceae)

Antifreeze proteins (AFPs) provide protection for organisms subjected to the presence of ice crystals. The psychrophilic diatom Fragilariopsis cylindrus which is frequently found in polar sea ice carries a multitude of AFP isoforms. In this study we report the heterologous expression of two antifreeze protein isoforms from F. cylindrus in Escherichia coli. Refolding from inclusion bodies produced proteins functionally active with respect to crystal deformation, recrystallization inhibition and thermal hysteresis. We observed a reduction of activity in the presence of the pelB leader peptide in comparison with the GS-linked SUMO-tag. Activity was positively correlated to protein concentration and buffer salinity. Thermal hysteresis and crystal deformation habit suggest the affiliation of the proteins to the hyperactive group of AFPs. One isoform, carrying a signal peptide for secretion, produced a thermal hysteresis up to 1.53 °C ± 0.53 °C and ice crystals of hexagonal bipyramidal shape. The second isoform, which has a long preceding N-terminal sequence of unknown function, produced thermal hysteresis of up to 2.34 °C ± 0.25 °C. Ice crystals grew in form of a hexagonal column in presence of this protein. The different sequences preceding the ice binding domain point to distinct localizations of the proteins inside or outside the cell. We thus propose that AFPs have different functions in vivo, also reflected in their specific TH capability.     

Photosynthetic oscillation in individual cells of the marine diatom <Emphasis Type="Italic">Coscinodiscus wailesii</Emphasis> (Bacillariophyceae) revealed by microsensor measurements

Oscillations with a period of 1–2 min in the rate of photosynthesis have been found in leaves of C₃ and C₄ land plants under invariant, saturating, light and carbon dioxide. This article reports the occurrence of similar oscillations with a period of 2–2.5 min in individual cells of the marine diatom Coscinodiscus wailesii. These oscillations were determined by measurements of both oxygen (oxygen microelectrode) and carbon dioxide (pH microelectrode) just outside the plasmalemma. These oscillations were found in less than 1% of the cells examined. The occurrence of oscillations in unicelluar diatoms rules out for these organisms hypotheses as to the origin of oscillations in land plant leaves that are based on cell–cell interactions.     

Resting spore formation ofLeptocylindrus danicus (Bacillariophyceae) during short time-scale upwelling and its significance as predicted by a simple model

Resting spore formation during short time-scale upwelling and its significance were investigated in the field and by a simple theoretical model. Field observations of spore formation ofLeptocylindrus danicus were made off Izu Peninsula, Japan. A rapid increase in ratio of resting spore to vegetative cell numbers indicated thatL. danicus formed resting spores quickly as a response to nutrient depletion in the upwelled water, although only a very low number of resting spores was found in the upwelling. A simple model was constructed to investigate the possible advantages of spore formation during short time-scale upwelling. This showed that there is a critical time-scale for resting spore formation to be advantageous. The nutrient depletion period of the upwelling off Izu was shorter than the critical time-scale determined by the model. Rapid-sinking of resting spores may increase further the critical time-scale, unless spores return with upwelling water. For short time-scale upwelling, the vegetative cell may be better suited than the resting spore for enduring a short period of nutrient depletion. Contribution from Shimoda Marine Research Center, University of Tsukuba, No. 475.     

Morphogenetic processes inAttheya decora (Bacillariophyceae,Biddulphiineae)

The valva of the diatomAttheya decora is formed within a silica deposition vesicle which enlarges centrifugally by the fusion of small vesicles. The silica deposition vesicle can already be seen when the spindle has not yet disappeared completely. Valva formation seems to begin with the shaping of an organic matrix within a silica deposition vesicle. Later, this material silicifies. The complicated shape of the labiate process is preformed by the silica deposition vesicle, the inner membrane of which is associated with electron dense material on both faces. The horns are formed when the expanding silica deposition vesicle has reached the cell corners. They are elaborated without participation of microtubules. Swelling of local depositions of polysaccharides seems to provide the forces that spread the silicified horns during daughter cell separation and to cause the local spontaneous plasmolyses under the valva and along the cell flanks in the region of the intercalary bands. The inner organic wall layers and the organic continuations of the intercalary bands are formed on the surface of the plasmalemma; each of the continuations is produced simultaneously with the intercalary band belonging to it and becomes attached to the latter when the silica deposition vesicle opens.     

Field observations in the Oosterschelde (The Netherlands) onCoscinodiscus concinnus andCoscinodiscus granii (Bacillariophyceae) infected by the marine fungusLagenisma coscinodisci (Oomycetes)

During 1985–1990Coscinodiscus concinnus andCoscinodiscus granii from the Oosterschelde were infected by the marine fungusLagenisma coscinodisci, although not every year with the same intensity. Infected cells were only observed during the period July–October at water temperatures between 13.2 and 20.2°C. In 1986 and 1987 the course of the infection withL. coscinodisci inC. concinnus andC. granii, was recorded at three stations. The highest infection percentages varied between 22.2 and 58.3% inC. concinnus and between 7.1 and 41.9% inC. granii. It is concluded that the water temperature may play an important role in the appearance ofL. coscinodisci inC. concinnus andC. granii and that silicate limitation is of minor importance. Finally it is discussed that the infection was not of great importance for the phytoplankton community in the Oosterschelde.     

Plastid inheritance in the planktonic raphid pennate diatom Pseudo-nitzschia delicatissima (Bacillariophyceae)

Plastid inheritance was followed during sexual reproduction in the raphid pennate diatom Pseudo-nitzschia delicatissima, using rbcL haplotypes as plastid identification tools. Pseudo-nitzschia species are dioecious and show functional anisogamy with 'male' mating type+(PNd(+)) cells and 'female' PNd(-) cells. Vegetative cells possess two plastids. In P. delicatissima, meiosis results in two gametes that both contribute two plastids to the zygote. The latter initially contains four plastids, but during auxospore development two of these four seem to disappear, and the initial cell emerging from the auxospore appears to contain only two. Here we assessed if the plastids are inherited strictly unipaternally, strictly biparentally, or randomly. We traced the source of the plastids in the F(1) generation by using PNd(+) and PNd(-) parental strains with different rbcL genotypes, here denoted AA (homoplastidial, with two plastids of rbcL haplotype A) and BB (homoplastidial; two plastids of haplotype B). Results showed that 16 out of 96 strains raised each from single F(1) cells had retained two paternal (PNd(+)) plastids, 20 had two maternal (PNd(-)) plastids and the remaining 60 had one maternal and one paternal plastid. This pattern is in accordance with the hypothesis that either two of the four plastids are eliminated during auxospore formation, or that all plastids are retained in the auxospore and segregate in pairs joining at random during the first mitotic division of the initial cell. Heteroplastidic F(1)-strains retained the AB genotype throughout the vegetative phase of their life cycle. The finding that 60 out of 96 F(1) strains were heteroplastidial contrasts with an absence of such genotypes in our strains raised from single cells sampled in the Gulf of Naples.     

Preliminary studies on the colonial form of Cylindrotheca sp. (Bacillariophyceae)

From a stock culture of Cylindrotheca sp., non-motile colony-forming cells were observed and isolated. Colony-forming cells produced both single cells and colony-forming cells in liquid media, the rate of single cell production varied among clones. The single cells derived from colony-forming cells were also isolated, which were able to produce both colony-forming cells and single cells in liquid media. The cells derived from colony-forming cells never moved on the agar surface.     

Die Lage des Chromatophors in Beziehung zur Systematik vonCymbella-Arten (Bacillariophyceae)

InCymbella the position of the chromatophore corresponds to the taxonomic differentiation into sections. The pyrenoid always shows the same right hand — left hand inclination.

     

A branched beta-D-(1-->3,1-->6)-glucan from the marine diatom Chaetoceros debilis (Bacillariophyceae) characterized by NMR

The chrysolaminaran from the marine diatom Chaetoceros debilis was isolated and characterized by NMR spectroscopy. Cells were harvested in the stationary phase of growth after the medium had been depleted of nitrate when the chrysolaminaran content was expected to be at its highest. The chrysolaminaran was isolated with an yield of 17.5 mg/L, which corresponds to 15.8 pg/cell. 1H NMR indicated that the structure was similar to that of a beta-(1-->3) main chain with beta-(1-->6)-linked side chains. The degree of polymerization was found to be 30, corresponding to a molecular weight of approximately 4900. Thirty-three percent of the residues were found to be beta-(1-->6)-linked branches. The characteristics of the beta-(1-->6) branching were examined by NOESY NMR, which suggested pustulan-like branches, being beta-(1-->6) linked chains connected to the main chain with few branch points. Confirmation of the 1H NMR data was done by 13C-DEPT, TOCSY, COSY and HMQC NMR spectroscopy. The assignment of the resonances of the main beta-(1-->3) and beta-(1-->6) chains is presented. The structure proposed from our analyses is compared against other chrysolaminaran structures.     

中国毛茛科翠雀属的分类学研究(八):短尾翠雀花的名实订正

发现近来根据云南西北部丽江标本描述的毛茛科短尾翠雀花(Delphinium brachyurum W. T. Wang)与此前根据该地标本描述的丽江翠雀花(D. likiangense Franch.)属于同一种植物,故将前者处理为后者的异名。     

中国毛茛科翠雀属的分类学研究(十三):狭序翠雀花的名实订正

发现根据甘肃南部标本描述的毛茛科狭序翠雀花（Delphinium angustipaniculatum W.T.Wang）与此前记载分布于甘肃南部和四川北部的松潘翠雀花（D.sutchuenense Franch.）属于同一种植物,故将前者处理为后者的异名。讨论了松潘翠雀花与其可能的近缘种秦岭翠雀花（D.giraldii Diels）和疏花翠雀花（D.sparsiflorum Maxim.）的形态区别。     

Zur Morphologie und Entwicklungsgeschichte vonEunotia-Arten (Bacillariophyceae)

After allogamous pairingEunotia tenella produces in each partner cell one gamete containing the two chromatophores of the mother cell and one abortive protoplast without chromatophores. This distribution results from a differential cytokinesis which exhibits the same constant orientation in regard to the epi- resp. hypotheka as in other species ofEunotia. Moreover inEu. tenella andEu. spec. the significant right hand—left hand dissymmetry during the growth of the daughter chromatophores in vegetative cytokinesis is the same as in other species. Both phenomena are significant for the genus and unique. In connection with the diminution of cell size in vegetative divisions the bending of the valvae increases to a certain degree.

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Zur Morphologie und Entwicklungsgeschichte vonEunotia-Arten (Bacillariophyceae)

     

中国毛茛科翠雀属的分类学研究(十二):竞生翠雀花的名实订正

通过标本室和野外观察,发现根据云南西北部中甸标本描述的毛茛科竞生翠雀花（Delphinium yangii W.T.Wang）与此前记载分布于该地及四川西南部（康定、小金、汶川）的宝兴翠雀花（D.smithianum Hand.-Mazz.）属于同一分类实体,故将前者处理为后者的异名。     

中国毛茛科翠雀属的分类学研究(四):五花翠雀花的名实订正

通过标本室和野外观察,发现根据云南中甸标本描述的毛茛科五花翠雀花(Delphinium quinqueflorum W.T.Wang)与当地颇为常见的澜沧翠雀花(D.thibeticum Finet&Gagnep.)没有本质区别,仅为其稍矮小的植株,故将前者处理为后者的异名。     

中国毛茛科翠雀属的分类学研究(十四):光序翠雀花二新异名

广布于中国-喜马拉雅地区的毛茛科光序翠雀花（Delphinium kamaonense Huth）在我国甘肃、青海、四川和西藏具有相当连续的分布区,在分布区内颇为常见,几为杂草。通过标本室和野外观察,发现根据西藏波密、察隅标本描述的展毛光序翠雀花[D. kamaonense var. glabrescens（W. T. Wang）W. T. Wang]和根据西藏类乌齐标本描述的倒心形翠雀花（D. obcordatilimbum W. T. Wang）与光序翠雀花没有本质区别,故将二者均处理为光序翠雀花的异名。     

中国毛茛科翠雀属的分类学研究(五):秋翠雀花二新异名

通过标本室和野外观察,发现根据四川西南部越西标本描述的毛茛科凉山翠雀花(Delphinium liangshanense W. T. Wang)和根据四川西南部木里标本描述的光轴翠雀花(D. leiostachyum W. T. Wang)只是此前记载分布于四川木里、盐源和云南西北部宁蒗一带的秋翠雀花(D. autumnale Hand.-Mazz.)植株较高的类型,故将二者均处理为秋翠雀花的异名.