Morphology of the Toxin-Producing Diatom Nitzschia pungens Grunow forma multiseries Hasle

1992 ◽  
Vol 49 (2) ◽  
pp. 303-311 ◽  
Author(s):  
Daniel J. MacPhee ◽  
Louis A. Hanic ◽  
Dianne L. Friesen ◽  
David E. Sims
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Cell Motility ◽  
Prince Edward Island ◽  
Domoic Acid ◽  
Light And Electron Microscopy ◽  
Cell Ultrastructure ◽  
Field Samples ◽  
Toxic Blooms ◽  
Nitzschia Pungens

The toxin-producing diatom Nitzschia pungens Grunow forma multiseries Hasle from three toxic blooms in two Prince Edward Island estuaries, spanning 1987–89, was studied using light and electron microscopy. Cell ultrastructure of N. pungens is, in general, similar to that of other species of Nitzschia and other diatoms. Important features include prominent peripheral, polarized nucleoli (numbering one or two) and imperforate poroids, present on inner valves and girdle bands. Cell division is usually synchronous for all cells in a filament with respect to polarity and time. Postdivisional elongation of the filament appears to involve a "slide-by" process whereby sibling cells slide by each other along their opposed valve faces and then stop, becoming fused by their overlapping tips. The raphe is probably involved in this, as well as in filament and cell motility. Observations of particle motion along the cell raphe suggest the existence of a motility apparatus such as microcilia which would facilitate locomotion, intercellular coordination, and the postdivisional slide-by process. No bacteria or other organisms were observed associated with field samples of toxic N. pungens f. multiseries. This supports a view that domoic acid production is autonomous.

A comparison of soft X-ray contact microscopy with light and electron microscopy for the study of algal cell ultrastructure

1988 ◽  
Vol 149 (3) ◽  
pp. 207-216 ◽  
Author(s):  
A. D. Stead ◽  
T. W. Ford ◽  
W. J. Myring ◽  
D. T. Clarke
Keyword(s):  
Electron Microscopy ◽  
Algal Cell ◽  
Light And Electron Microscopy ◽  
Cell Ultrastructure ◽  
X Ray

Pennate Diatom Nitzschia pungens as the Primary Source of Domoic Acid, a Toxin in Shellfish from Eastern Prince Edward Island, Canada

1989 ◽  
Vol 46 (7) ◽  
pp. 1203-1215 ◽  
Author(s):  
S. S. Bates ◽  
C J. Bird ◽  
A. S. W. de Freitas ◽  
R. Foxall ◽  
M. Gilgan ◽  
...  
Keyword(s):  
Prince Edward Island ◽  
Domoic Acid ◽  
Food Poisoning ◽  
Primary Source ◽  
Pennate Diatom ◽  
Closely Related Species ◽  
Plankton Bloom ◽  
Amphora Coffeaeformis ◽  
Human Poisoning ◽  
Nitzschia Pungens

An outbreak of food poisoning in Canada during autumn 1987 was traced to cultured blue mussels (Mytilus edulis) from the Cardigan Bay region of eastern Prince Edward Island (P.E.I.). The toxin, identified as domoic acid, had not previously been found in any shellfish and this outbreak represents the first known occurrence of human poisoning by this neurotoxin. A plankton bloom at the time of the outbreak consisted almost entirely of the pennate diatom, Nitzschia pungens f. multiseries, and a positive correlation was found between the number of N. pungens cells and the concentration of domoic acid in the plankton. Nitzschia pungens f. multiseries isolated from Cardigan Bay produced domoic acid in culture at levels (1 to 20 pg∙cell−1) comparable with values estimated for N. pungens in the plankton samples. Isolates of several Cardigan Bay phytoplankton, including the closely related species Nitzschia seriata, failed to produce domoic acid. Other Nitzschia spp. and two Amphora coffeaeformis isolates also failed to produce domoic acid. We conclude that N. pungens was the major source of the domoic acid in toxic mussels in eastern P.E.I. The recurrence, in November 1988, of a monospecific bloom of N. pungens and the presence of domoic acid in plankton and mussels reinforced this conclusion.

scholarly journals The Effect of 5-Fluorouracil on the Growth and Nucleolus of Wheat Coleoptiles

1970 ◽  
Vol 23 (3) ◽  
pp. 561 ◽  
Author(s):  
RJ Rose ◽  
Jeanette Gregory ◽  
FV Mercer
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Cell Elongation ◽  
Normal Cell ◽  
Light And Electron Microscopy ◽  
Wheat Coleoptile ◽  
Ribosome Synthesis ◽  
Cell Division Inhibition

Intact etiolated wheat coleoptiles grown from the beginning of imbibition III 5-fluorouracil (5-FU) show normal cell elongation, but division is inhibited. 5-FU-treated coleoptiles, 48 hr after imbibition, have enlarged nucleoli (165% increase in volume) in which the RNA is mostly confined to the periphery. Untreated and treated nucleoli were studied by light and electron microscopy. The 5-FU effects on the nucleolus, which occur at the time cell division usually occurs if 5-FU is not present, are of interest in relation to ribosome synthesis. Uracil or thymidine did not reverse the nucleolar effects, but uracil further inhibited growth, while thymidine partly reversed the cell division inhibition. Results with 5-FU and thymidine suggest that the coleoptile cells can divide at least once when they have abnormal nucleoli, but normal nucleolar metabolism is essential for the complete growth of the etiolated wheat coleoptile.

Correlative light and electron microscopy for the analysis of cell division

2013 ◽  
Vol 251 (2) ◽  
pp. 109-112 ◽  
Author(s):  
STEFANIE REDEMANN ◽  
THOMAS MÜLLER-REICHERT
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Light And Electron Microscopy

Controls on Domoic Acid Production by the Diatom Nitzschia pungens f. multiseries in Culture: Nutrients and Irradïance

1991 ◽  
Vol 48 (7) ◽  
pp. 1136-1144 ◽  
Author(s):  
S. S. Bates ◽  
A. S. W. de Freitas ◽  
J. E. Milley ◽  
R. Pocklington ◽  
M. A. Quilliam ◽  
...  
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Exponential Growth ◽  
Domoic Acid ◽  
Culture Medium ◽  
Dark Period ◽  
Growth Conditions ◽  
Dark Cycle ◽  
Division Rate ◽  
Nitzschia Pungens

Nitzschia pungens f. multiseries (clone NPARL) was grown in nonaxenic batch culture under a range of growth conditions. Domoic acid (DA) was not detected during exponential growth, but production promptly started at a rate of approximately 1 pg DA∙cell−1∙d−1 at the onset of the stationary phase, in this case induced by silicate limitation. Cellular DA reached a maximum of 7 pg∙cell−1; thereafter, DA production continued at the same rate, with cellular levels remaining relatively constant due to concurrent release of DA into the culture medium. DA production ceased in the absence of nitrogen during the stationary phase, but resumed when nitrate was added back to the medium. Low irradiance slowed the division rate and consequently delayed the attainment of the stationary phase, but DA production rates were comparable with the control once stationary phase was reached. Cells during the dark period of a light–dark cycle, or placed into darkness, or in the presence of the photosynthetic inhibitor DCMU promptly ceased DA production. We conclude that at least three conditions are required for DA production by clone NPARL: cessation of cell division, availability of nitrogen during the stationary phase, and the presence of light. Growth in medium f/2 fulfils these requirements.

Correlated light and electron microscopy of cell division in large marine oocytes, eggs, and embryos

2018 ◽  
pp. 293-313 ◽  
Author(s):  
Mariia Burdyniuk ◽  
Natalia Wesolowska ◽  
Michal Fleszar ◽  
Matthia A. Karreman ◽  
Pedro Machado ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Light And Electron Microscopy

Domoic Acid—A Neurotoxic Amino Acid Produced by the Marine Diatom Nitzschia pungens in Culture

1988 ◽  
Vol 45 (12) ◽  
pp. 2076-2079 ◽  
Author(s):  
D. V. Subba Rao ◽  
M. A. Quilliam ◽  
R. Pocklington
Keyword(s):  
Amino Acid ◽  
Chemical Analysis ◽  
River Water ◽  
Prince Edward Island ◽  
Domoic Acid ◽  
Culture Medium ◽  
Marine Diatom ◽  
Eastern Canada ◽  
Blue Mussels ◽  
Nitzschia Pungens

During late 1987, an outbreak of poisoning resulting from the ingestion of cultivated blue mussels (Mytilus edulis) from a localized area in eastern Canada (Cardigan Bay, Prince Edward Island) was associated with massive blooms of Nitzschia pungens, a widely distributed diatom not previously known to produce toxins; human fatalities resulted. Here we provide proof that the causative agent, domoic acid, is indeed produced by this diatom. Although no domoic acid could be detected (<2 ng∙mL−1) in culture medium (FE) prepared from Cardigan River water, it was found in cultures of Nitzschia pungens grown in this medium at concentrations ranging from 0.03 to 0.8 pg∙cell−1 in various separate cultures harvested for chemical analysis 7–68 d after inoculation.

Production of Domoic Acid, a Neurotoxic Amino Acid, by an Axenic Culture of the Marine Diatom Nitzschia pungens f. multiseries Hasle

1992 ◽  
Vol 49 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Donald J. Douglas ◽  
Stephen S. Bates
Keyword(s):  
Cell Division ◽  
Stationary Phase ◽  
Domoic Acid ◽  
Stationary Phases ◽  
Axenic Culture ◽  
Marine Diatom ◽  
Epifluorescence Microscopy ◽  
Division Rate ◽  
Growth Production ◽  
Nitzschia Pungens

A microbially contaminated culture of Nitzschia pungens f. multiseries (clone TKA-2) was treated with gentamicin followed by a combination of penicillin and streptomycin. An axenic culture was successfully isolated as evidenced by sterility tests using four different nutrient enrichment media and examination by epifluorescence microscopy. The isolate had a specific division rate (0.65∙d−1) comparable with that reported for nonaxenic cultures. The axenic culture produced domoic acid (DA) during the lag and stationary phases, when cell division rates were low or zero, but not during exponential growth. Production of DA resumed within 1 d after cell division ceased and reached 0.5 pg DA∙cell−1∙d−1 2–3 d after the onset of the stationary phase. A maximum concentration of 2.0 pg DA∙cell−1 was reached after 6 d in stationary phase. Our results provide the first evidence that N. pungens f. multiseries produces DA in the absence of other microorganisms.

Morphogenetic analysis of changing cell associations following release of 2-cell and 4-cell mouse embryos from cleavage arrest

Development ◽  
1981 ◽  
Vol 61 (1) ◽  
pp. 331-345
Author(s):  
S. J. Kimber ◽  
M. A. H. Surani
Keyword(s):  
Electron Microscopy ◽  
Cell Division ◽  
Light And Electron Microscopy ◽  
Cytochalasin D ◽  
Mouse Embryos ◽  
Fresh Medium ◽  
The Other ◽  
Similar Process ◽  
Serial Sections ◽  
Morphogenetic Analysis

Two-cell and four-cell mouse embryos were cultured in Cytochalasin D (CD) for 40–48 h. They were fixed for light and electron microscopy at various times after washing off the CD. Cleavage-arrested embiyos in CD had well separated blastomeres but by 1 h from washing the embryos had compacted, in most cases without undergoing cell division. By 2 h after release from arrest one blastomere of the 2-cell arrested embryos had become crescent shaped and at 4–5 h the crescent-shaped blastomere had started to spread over the surface of the other rounded blastomere. This process continued until by 16–24 h from explantation to fresh medium one blastomere had almost completely engulfed the other. A similar process occurred in 4-cell arrested and released embryos. At this stage the embryos had accumulated fluid and become blastocyst-like vesicles. In 20% of 2-cell and 4-cell embryos one or two blastomeres underwent one cell division after release from arrest. Serial sections of these embryos lead to the conclusion that one or both progeny of the first cell to divide tended to be engulfed by the later dividing or non-dividing cell(s). These results are discussed in relation to the differentiation of ICM and trophectoderm in blastocysts.

scholarly journals Partial Characterization of a Distinct Potyvirus Isolated from Watermelon in Florida

Plant Disease ◽  
1998 ◽  
Vol 82 (12) ◽  
pp. 1386-1390 ◽  
Author(s):  
D. E. Purcifull ◽  
E. Hiebert ◽  
M. A. Petersen ◽  
G. W. Simone ◽  
T. A. Kucharek ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mosaic Virus ◽  
Cucurbita Pepo ◽  
Citrullus Lanatus ◽  
Light And Electron Microscopy ◽  
Zucchini Yellow Mosaic Virus ◽  
South Florida ◽  
Yellow Mosaic Virus ◽  
Nuclear Inclusions ◽  
Field Samples

Conspicuous, unusual nuclear inclusions in stained epidermal strips of leaves implicated a virus (designated isolate 2932) as the cause of foliar mosaic in a watermelon plant (Citrullus lanatus) received for analysis from South Florida in 1990. In greenhouse tests, mechanically inoculated plants of Cucurbita pepo (Small Sugar pumpkin and Early Prolific Straightneck squash) and watermelon (Crimson Sweet) developed mosaic or mottle symptoms. Isolate 2932 caused foliar symptoms in 16 cultivars of Cucurbita pepo, including Freedom II and Prelude II, and in six cultivars of watermelon. None of five cultivars of melon (Cucumis melo) or 11 cultivars of cucumber (Cucumis sativus) developed consistent, distinctive symptoms, but all of these cultivars were systemically infected based on back-inoculations to squash. No systemic infection of mechanically inoculated plants of 25 species representing 13 noncucurbitaceous plant families was detected. Crystalline nuclear inclusions, cytoplasmic amorphous inclusions, and cytoplasmic cylindrical inclusions were detected by light and electron microscopy in leaf tissues of infected squash and watermelon. Electron microscopy of squash leaf extracts revealed filamentous particles, and 86% of 159 particles measured ranged from 800 to 890 nm in length. The virus was transmitted in a nonpersistent manner by Myzus persicae from squash to squash in two of three trials. Immunodiffusion tests with polyclonal antisera prepared to partially purified 2932 or its capsid protein showed that the isolate was antigenically different from papaya ringspot virus type W, watermelon mosaic virus 2, and zucchini yellow mosaic virus. In limited testing of field samples of squash and watermelon since 1990, no additional isolates of the 2932 type have been found. The characteristics of isolate 2932 obtained thus far indicate that it is a distinct potyvirus. It is tentatively named watermelon leaf mottle virus to distinguish it from other potyviruses commonly isolated from cucurbits in Florida.

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