Ultrastructural features of the life cycle ofAcetabularia mediterranea

Woodcock, Christopher L.; Miller, G. J.

doi:10.1007/bf01276767

Cited by 28 publications

(6 citation statements)

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“…Only few ultrastructural studies have been undertaken on motile cells of siphonalean green algae (Crawley, 1966;Burr & West, 1970;Woodcock & Miller, 1973;Moestrup & Hoffman, 1975;Hori, 1977;Hori & Enomoto, 1978;Roberts, 1980;Roberts et al, 1980;Roberts et al, 1981, in prep. ) and these have not yet led to self-explanatory results.…”

Section: Introductionmentioning

confidence: 99%

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

Melkonian

1981

Helgoländer Meeresunters

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The ultrastructure of the flagetlar apparatus in the biflagellate female gametes of the green alga Bryopsis lyngbyei has been studied in detail. In the flagellum and basal body, microtubule septations occur in some of the B-tubules. The transition region of the flagellum is extremely long (260-290 nm), exhibits a stellate pattern in cross section but lacks the transverse diaphragm. The two basal bodies form an angle of 180 ° and overlap at their proximal ends. They are connected by a compound non-striated capping plate. Terminal caps associated with the capping plate partially close the proximal end of each basal body. A cruciate flagellar root system with three different types of microtubular roots is present, i. e. the flagellar apparatus does not show 180 ° rotational symmetry. One root type contains 2 microtubules which are connected to an elaborate cylindrical structure, presumably a mating structure. The opposite root exhibits 3 microtubules over its entire length and is not associated with a cylindrical structure. In their proximal parts both roots are linked to an underlying crescent body. The other two microtubular roots are probably identical and consist of 4 (or 5) microtubules which show configurational changes. These two identical roots insert into the capping plate and link to the inner side (i. e. the side adjacent to the other basal body) of each basal body, whereas the other two roots attach to the outer sides of each basal body. System I striated fibres are probably associated with each of the four roots, while system II fibres have not been observed. The flagellar apparatus of female gametes of B. 1yngbyei shows many unique features but in some aspects resembles that of ulvatean algae. Functional and phylogenetic aspects of cruciate flagellar root systems in green algae are discussed,

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Section: Introductionmentioning

confidence: 99%

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

Melkonian

1981

Helgoländer Meeresunters

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“…Gametogenesis of green algae has been investigated by both ultrastructural and light microscopic observations. These studies have focused mainly on nuclear division (mitosis), formation of flagellar apparatus and cleavage furrows in isogamous algae; Acetabularia mediterranea (Woodcock and Miller 1973), Chlamydomonas reinhardii (Cavalier‐Smith 1975) and Dictyosphaeria cavernosa (Hori and Enomoto 1978), anisogamous algae; Caulerpa (Hori 1981), Bryopsis hypnoides (Burr and West 1970) and Pseudobryopsis hainanensis (Okuda 1989), and oogamous algae; Oedogonium cardiacum (Coss and Pickett‐Heaps 1973, 1974). Ogawa (1988) observed chloroplast degeneration and the behavior of chloroplast DNA during male gamete formation in a coenocytic green alga, Bryopsis plumosa .…”

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confidence: 99%

LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS OF PREFERENTIAL DESTRUCTION OF CHLOROPLAST AND MITOCHONDRIAL DNA AT EARLY MALE GAMETOGENESIS OF THE ANISOGAMOUS GREEN ALGADERBESIA TENUISSIMA(CHLOROPHYTA)¹

Lee

Motomura

Ichimura

2002

Journal of Phycology

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Gametogenesis in male and female gametophytes was studied by light microscopy and EM in the dioecious multinucleate green alga Derbesia tenuissima (Moris & De Notaris) P. Crouan & H. Crouan, where male and female gametes differ in size. Gametogenesis was divided into five stages: 32 h (stage 1), 24 h (stage 2), 16 h (stage 3), 8 h (stage 4), and 0.5 h (stage 5) before gamete release. At stage 1, the first sign of gametogenesis observed was the aggregation of gametophyte protoplasm to form putative gametangia. At stage 2, gametangia were separated from the vegetative protoplasm of gametophytes. Morphological changes of nuclei and organelles occurred at this early stage of male gametogenesis, and organelle DNA degenerated. At stage 3, male organelle DNA had completely degenerated, whereas in female gametangia, organelle DNA continued to exist in both chloroplasts and mitochondria. Gametogenesis was almost completed at stage 4 and fully at stage 5. Small male gametes had a DNA‐containing nucleus and a large mitochondrion and one or several degenerated chloroplasts. The mitochondria and plastids were devoid of DNA. The large female gametes had a nucleus and multiple organelles, all of which contained their own DNA. Thus, degeneration of chloroplast DNA along with morphological changes of organelles occurred at male gametogenesis in anisogamous green algae (Bryopsis and D. tenuissima), in contrast with previous studies in isogamous green algae (Chlamydomonas, Acetabularia caliculus, and Dictyosphaeria cavernosa) in which degeneration of chloroplast DNA occurred after zygote formation.

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“…tomy) of multinucleate cell systems is especially valuable since they represent stages in which large areas of cell surface appear, usually within a rather short time, such as in the formation of spores, cysts, "spherules," and gametes (for references, see 2,3,14,29,31). The fine structural organization of the (polyenergid) coenoblast of cyst-forming caps of Acetabularia has been described in detail in various articles (e.g., references 1, 13,34,35). The onset of cyst formation is most typically recognized at the stage "WeiBer Fleck" ("pale spot"; for detailed descriptions, see references 28,29,33).…”

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confidence: 99%

“…The fine structural organization of the (polyenergid) coenoblast of cyst-forming caps of Acetabularia has been described in detail in various articles (e.g., references 1,13,34,35). The onset of cyst formation is most typically recognized at the stage "WeiBer Fleck" ("pale spot"; for detailed descriptions, see references 28,29,33).…”

mentioning

confidence: 99%

“…The onset of cyst formation is most typically recognized at the stage "WeiBer Fleck" ("pale spot"; for detailed descriptions, see references 28,29,33). This stage is characterized by a rather regular pattern of plastid-free patches, each of which contains a secondary nucleus and a portion of perinuclear cytoplasm, including basophilic "heavy bodies" and many microtubules (1,13,34,35). Thereafter, the mononucleate (monoenergid) portions are dissected out by a sequence of coenocytotomic cleavages within less than 24 h (28).…”

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confidence: 99%

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Involvement of bristle coat structures in surface membrane formations and membrane interactions during coenocytotomic cleavage in caps of Acetabularia mediterranea.

Franke¹,

Kartenbeck

Spring

1976

The Journal of Cell Biology

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In the multinucleate cap rays of the green alga Acetabularia mediterranea the cell surface increases dramatically within a short time period during the final stages of coenocytotomic cleavage. In early stages of cyst formation the cytoplast is traversed by numerous large and prolate cleavage vesicles which are characterized by typical columellar or spinous coat structures. The cleavage vesicles are closely associated with the surface of plastids and, to a lesser degree, of mitochondria. This intimate association seems to be mediated by regularly spaced, densely stained intermembranous cross-bridge structures and is maintained throughout cleavage. These cleavage vesicles contain a finely fibrillar material structurally similar to the hyaline layer of mucilage that fills the space between the plasma membrane and cell wall. They line up with invaginations of the plasmalemma and vacuole membranes and, together with smaller vesicles interspersed, constitute preformed "perforation lines" for the final separation of the coenoblast portions. Equidistantly spaced plaques of attachment of such vesicles with surface membrane are described. We hypothesize (a) that the cleavage vesicle membrane is the immediate precursor to the new postcoenocytotomic surface membrane, (b) that the cleavage vesicle coat structures are integrated into the subsurface coat of the plasma membrane, (c) that growth of the laterally attached cleavage vesicles by intussusception of small fuzzy-coated vesicles is confined to their "free ends," (d) that the intermembranous cross-bridge elements are related to bristle coat structures and play a role in the establishment of the cleavage lines, and (e) that the coenocytotomic cleavage process is organized so that adjacent plastids are separated in a way that guarantees the inclusion of several plastids in each cyst.Current concepts and hypotheses on the mechanisms of cell surface membrane formation provide a series of arguments for and against the incorporation and transformation of intracellular merebranes into plasma membrane (for references, see 9,12,21,23). It is obvious that in this discussion on the modes of surface membrane formation the study of the cytoplasmic cleavages (coenocyto-196

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Ultrastructural features of the life cycle ofAcetabularia mediterranea

Cited by 28 publications

References 10 publications

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS OF PREFERENTIAL DESTRUCTION OF CHLOROPLAST AND MITOCHONDRIAL DNA AT EARLY MALE GAMETOGENESIS OF THE ANISOGAMOUS GREEN ALGADERBESIA TENUISSIMA(CHLOROPHYTA)¹

Involvement of bristle coat structures in surface membrane formations and membrane interactions during coenocytotomic cleavage in caps of Acetabularia mediterranea.

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Ultrastructural features of the life cycle ofAcetabularia mediterranea

Cited by 28 publications

References 10 publications

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

Structure and significance of cruciate flagellar root systems in green algae: Female gametes ofBryopsis lyngbyei (Bryopsidales)

LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS OF PREFERENTIAL DESTRUCTION OF CHLOROPLAST AND MITOCHONDRIAL DNA AT EARLY MALE GAMETOGENESIS OF THE ANISOGAMOUS GREEN ALGADERBESIA TENUISSIMA(CHLOROPHYTA)1

Involvement of bristle coat structures in surface membrane formations and membrane interactions during coenocytotomic cleavage in caps of Acetabularia mediterranea.

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LIGHT AND ELECTRON MICROSCOPIC OBSERVATIONS OF PREFERENTIAL DESTRUCTION OF CHLOROPLAST AND MITOCHONDRIAL DNA AT EARLY MALE GAMETOGENESIS OF THE ANISOGAMOUS GREEN ALGADERBESIA TENUISSIMA(CHLOROPHYTA)¹