ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00001.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00002.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00004.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00008.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00014.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe domoic acid‐producing diatomNitzschia pungensGrunow f.multiseriesHasle, which is responsible for amnesic shellfish poisonings in Prince Edward Island, Canada, underwent gametogenesis when senescent cells (i.e. in stationary growth phase for more than 290 days) were subcultured into fresh FE medium and light intensity was increased from 33 to 530 μE · m−2· s−1. The number of gametes produced varied with the salinity of the medium, with a maximum at 23.5‰. Cells in the exponential growth phase (0.8 div · d−1) did not produce gametes, nor did senescent cells when transferred without change in light intensity. Anisogamous gametes, probably haploid, were isolated by combining conventional microscopy with flow cytometry. Zygotes resulting from syngamy yielded cigar‐shaped naviculoid cells, morphologically different from parent cells (heteromorphism). These cells, with a division rate of 1.9 div · d−1, could serve as a seed population and explain the origin and rapid progression of the toxic blooms of red‐water proportions that have been a public health problem in Eastern Canada. Production of domoic acid by postexponential and moribund cells but not by gametes, zygotes, or immediately resulting cells, provides an insight into the dependence of toxicity on the developmental hi

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00021.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTRecently released spores of the kelpsMacrocystis pyrifera(L.) C. Ag.,Nereocystis luetkeana(Mert.) Post. and Rupr.,Laminaria farlowiiSetch., andPterygophora californicaRupr. had different levels of net photosynthesis. Spore‐specific photosynthesis–irradiance relationships were similar in many respects forM. pyrifera, N. luetkeana, andL. farlowiispores. All three species had low rates of net light‐saturated photosynthesis. In contrast, spores ofP. californicahad higher photosynthetic potential and overall net photosynthesis than the other three species. On a cell carbon basis, however, photosynthetic rates inN. luetkeanaspores were similar to those ofP. californicaspores and higher than those ofM. pyriferaspores. Chlorophyllacontent of spores varied 10‐fold among species. The rank order of significant differences in chlorophyllacontent wasP. californica>L. farlowii>N. luetkeana>M. pyrifera.As a result, chlorophyll‐specific measurements suggestM. pyriferaandN. luetkeanaspores had much higher quantum efficiency and photosynthetic potential than eitherP. californicaorL. farlowiispores. Maternal carbon and nitrogen investment significantly differed in spores ofM. pyrifera, N. luetkeana, andP. californicawithP. californica>M. pyrifera>N. luetkeana.Carbon content in spores of each of these three species increased by about 30% during 12 h of saturating irradiance. We suggest that the photosynthetic capabilities of and maternal investment in spores may be related to the spore as a unit of dispersal, to the reproductive ecology of the parental sporophytic stages, and to the growth and physiology of the germling gametophy

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00026.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTShort‐term (1–9 min) nitrate uptake kinetics were measured inThalassiosira pseudonana(Hust.) Hasle&Heimdal grown in nitrate‐limited, ammonium‐limited, and nitrate‐sufficient continuous cultures. For all cultures, maximal nitrate uptake rates did not develop until approximately 3 min after nitrate addition; thereafter, nitrate uptake rates remained constant or declined slightly. The Ksand Vmaxfor the nitrate‐limited cultures were higher at any growth rate than those for the ammonium‐limited or nitrate‐sufficient cultures. Thus, much higher nitrate concentrations would be required to saturate nitrate uptake in nitrate‐limitedThalassiosira pseudonanathan is usually considered necessary. The lack of data for other species grown under a range of environmental conditions makes it difficult to generalize about the effect of preconditioning on nitrat

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00035.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe new genusPycnococcusGuillard is based on several clones from the western North Atlantic and Gulf of Mexico. The type and only described species,Pycnococcus provasoliiGuillard, sp. nov., is typified by cloneΩ48‐23 from the North Atlantic. Cells ofPycnococcus provasoliiare solitary, spherical, 1.5–4.0 μm in diameter, have a resistant cell wall lacking sporopollenin, and have the ultrastructural characteristics of green algae. With the light microscope they are scarcely distinguishable from cells of other coccoid planktonic organisms. In pigmentationP. provasoliiresemblesMicromonas pusilla, Mantoniella squamata, andMamiella gilvain having chla, much chlb, Mg 2,4‐divinylphaeoporphyrin a5monomethyl ester (presumably), and prasinoxanthin as a major xanthophyll. The pyrenoid ofP. provasoliihas a cytoplasmic channel, which is unique among species closely related to it. Flagellates, occurring rarely in culture, are similar to but distinguishable from knownPedinomonasspecies by size and shape.Pycnococcus provasoliiis referred to the new family Pycnococcaceae Guillard, in the order Mamiellales of the class Micromonadophyceae (Chlorophyta). Clones ofPycnococcus provasoliiare oceanic in nutritional characteristics, require only vitamin B12in culture, and are well adapted to growth under blue or blue‐violet light of low

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00039.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTTo investigate the possible link between cell wall alginic acid composition and tissue mechanics, juveniles ofEgregia menziesii(Turn.) Aresch. were grown under controlled conditions in an outdoor flowing seawater system under three different force regimes. After 6–10 weeks of growth, tissue strength, breaking strain, modulus, toughness, work of fracture, and the percentage of polymannuronate, polyguluronate, and alternating sequences in the cell wall alginic acid were examined. The force regime had significant effects on all mechanical indices except toughness. Juveniles grown under high energy conditions (water velocity = 1.2 m · s−1) were about two times stronger, two times stiffer, and had a 1.5 times greater work of fracture than those from low energy conditions (<1 cm ·−1). Treatment effects on thallus strength and modulus were predicted from alginic acid composition data to test for the importance of this cell wall material in whole plant adaptation to hydrodynamic stress. However, the prediction that differences in alginic acid composition were responsible for differences in tissue mechanical properties was inconsistent with observations. Therefore, the hypothesis that alginates play a central role in structural adaptation could not be a

ISSN:0022-3646    

DOI:10.1111/j.0022-3646.1991.00047.x

出版商:Blackwell Science Inc    

年代:1991

数据来源: WILEY