The encystment of a freshwater dinoflagellate: A light and electron-microscopical study

Bibby, B. T.; Dodge, John D.

doi:10.1080/00071617200650111

Cited by 60 publications

(36 citation statements)

References 24 publications

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“…Indeed, some organelles may not be broken down during encystment at all. This notion is supported in part by the findings of Bibby & Dodge (1972) who figured a persistent nucleus, accumulation body and chloroplasts in variously aged cysts of Woloszynskia tylota (Mapletoft et al) Bibby & Dodge. Similar consistency of structure was noted by Chapman et al (1981) in cysts of C. hirundinella.…”

Section: Discussionmentioning

confidence: 70%

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A study of newly excysted cells ofGonyaulax polyedra(Dinophyceae) by electron microscopy

Lewis¹,

Burton

1988

British Phycological Journal

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Section: Discussionmentioning

confidence: 70%

“…These were variable in size and distribution, and seemed to resemble the "accumulation bodies" of W. tylota (Bibby & Dodge, 1972). It should be noted, however, that these structures appear quite distinct from the accumulation bodies described by Taylor (1968), but resemble one of the bodies described by Chapman et al (1981 Fig.…”

Section: Discussionmentioning

confidence: 87%

A study of newly excysted cells ofGonyaulax polyedra(Dinophyceae) by electron microscopy

Lewis¹,

Burton

1988

British Phycological Journal

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“…Other possible mechanisms for increasing density include a decrease in cellular water content (as is often the case with other dormant cell forms: Sussman and Halvorson 1966;Warth 1978) or the accumulation of relatively dense starch that overcomes the buoyant effect of lipids. Both lipid and starch accumulate in cells before encystment (Bibby and Dodge 1972;Anderson and Wall 1978;Durr 1979;Chapman et al 1982). If we assume an initial cytoplasmic density for a vegetative cell near that of seawater (1.025 g cm-3) and a 1 -pmthick cyst wall, the cytoplasmic density would have to increase 16% to 1.18 g cmB3 to yield an overall cyst density of 1.24 g cm-3.…”

Section: Discussionmentioning

confidence: 99%

“…Many cysts have a thick, multilayered wall composed of cellulose or of sporopollenin, a poorly defined, highly resistant organic polymer (Bibby and Dodge 1972;Durr 1979;Chapman et al 1982). The combined thickness of these walls is generally 0.5-1.5 pm, although TEM measurements are scarce due to problems with fixation and resin penetration.…”

Section: Discussionmentioning

confidence: 99%

Sinking characteristics of dinoflagellate cysts1

Anderson

Lively

Reardon

et al. 1985

Limnology & Oceanography

112

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This study reports the first direct measurements of the density and sinking rates of marine dinoflagellate cysts. Gyrodinium uncatenum, Gonyaulax tamarensis, and Scrippsiella trochoidea cysts had densities of 1.14, 1.24, and 1.32 g cm-3. No significant difference between cultured and natural cyst density was observed. Measured settling velocities ranged from 0.008 to 0.0 13 cm s-1 (6-l 1 m d-l). Settling rates calculated using the measured densities and reasonable assumptions about shape and orientation during descent were within lO-20% of measured sinking rates, confirming that cyst sinking can be described by a modification of Stokes' law for nonspherical particles in a viscous medium. The three types of cysts examined are more dense and fall faster than most vegetative phytoplankton cells. Removal of an outer layer of short calcite spines from S. trochoidea cysts reduced both cell density and radius by 7% and the sinking rate by 37%. The faster settling velocity of the spiny cyst is not considered a general effect common to all ornamented cysts but presumably applies only to those with numerous short spines or processes. Morphological features can thus markedly affect the rate of cyst deposition, but the adaptive significance of surface ornamentation remains unknown.

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“…Algae which are walled in their vegetative state usually produce naked gametes if the gametes (or at least the male gannete of oogamous species) are motile by means of flagella. This production of motile, naked cells for sexual (and, frequently, asexual) reproduction may be regarded as the converse of the production of walled cysts as dormant/dispersal stages of the naked vegetative cells of many planktonic algae; these cysts may result from sexual or non-sexual events (see Brown et al, 1968;Bibby and Dodge, 1972;Lewis et al, 1974;Sheath, Hellebust and Sawa, 1975;Hibberd, 1977).…”

Section: Introductionmentioning

confidence: 99%

The Energetics of Freshwater Algae; Energy Requirements for Biosynthesis and Volume Regulation

Raven

1982

New Phytologist

110

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SUMMARYFreshwater algae have an intracellular osmolarity in excess of that of the medium. The tendency for water to enter the cells is resisted, in cells with a mechanically functional cell wall, by the ability of the wall to withstand a turgor pressure equivalent to the intracellular osmolarit^^; in cells lacking such a mechanically functional wall the water which enters is expelled by a contractile vacuole (or its functional equivalent). A comparison of the energy costs of cell volume regulation by these two mechanisois has been carried out making energy costings based on the minimum thermodynamic requirement and on plausible mechanisms for the two processes (wall synthesis and contractile vacuoie function). This analysis yielded the following conclusions.(1) Wall synthesis is a 'growth' process, while contractile vacuole operation is a 'maintenance' process; other things being equal, a cell wall is a preferable mechanism of volume regulation in non-growing cells.(2) For a 5 ftm radius cell with a specific growth rate of 8 x 10"" s~' and a 10 /an radius cell with a rate of 4 x 10~* s~^ the energy input rate for contractile vacuole operation is considerably lower than for wall synthesis on the basis of minimum thermodynamic requirement; the plausible mechanism approach makes the two energy costs quite similar. Decreased growth rates favours the wall over the contractile vacuole mechanism.(3) Increased cell size (10 jwm radius rather than 5 /^na) has similar effects on the energy costs of both volume regulation mechanisms, provided a (cell organic weight)""'^' dependence of intrinsic growth rate is incorporated into the computations, (4) Increased intracellular osmolarity (at constant extracellular osmolarity) causes a directly proportional increase in energy input rate for the cell wall mechanism, and a more than proportional increase in energy cost for the contractile vacuole mechanism.(5) A non-spherical shape increases the energy cost (at constant cell volume) for both the cell wall and the contractile vacuole mechanisms.These conclusions may be used in the interpretation of such phenomena as the lower osmolarity of wall-less than walled cells and the tendency for the resting stages of normally wall-less and flagellate cells to have walls. It appears that the majority of freshwater algae have genetic capabilities to produce both walls and contractile vacuoles for cell volume regulation (e.g, the production of walled cysts by organisms which are normally flagellate, and the production of wall-less motile spores and gametes by normially walled organisms).

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The encystment of a freshwater dinoflagellate: A light and electron-microscopical study

Cited by 60 publications

References 24 publications

A study of newly excysted cells ofGonyaulax polyedra(Dinophyceae) by electron microscopy

A study of newly excysted cells ofGonyaulax polyedra(Dinophyceae) by electron microscopy

Sinking characteristics of dinoflagellate cysts1

The Energetics of Freshwater Algae; Energy Requirements for Biosynthesis and Volume Regulation

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