Rhizoid Differentiation in Fern Spores: Experimental Manipulation

Miller, John H.; Greany, Robin H.

doi:10.1126/science.193.4254.687

Cited by 23 publications

(2 citation statements)

References 8 publications

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“…If this movement was prevented, no differentiation of a rhizoid occurred during the subsequent mitosis (Miller and Greany, 1976). By contrast, the present study clearly showed that the nucleus remained in the corner of the tetrahedronshaped dormant spore of A. capillus-veneris (Fig.…”

Section: Discussion Premitotic Positioning Of the Nucleus In Fercontrasting

confidence: 45%

Control of Mitosis by Phytochrome and a Blue-Light Receptor in Fern Spores

et al. 1997

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The first mitosis in spores of the fern A. capillus-veneris was observed under a microscope equipped with Nomarski optics with irradiation from a safelight at 900 nm, and under a fluorescent microscope after staining with 4',6-diamidino-2-phenylindole. During imbibition the nucleus remained near one corner of each tetrahedron-shaped dormant spore, and asymmetric cell division occurred upon brief irradiation with red light. This red lightinduced mitosis was photoreversibly prevented by subsequent brief exposure to far-red light and was photo-irreversibly prevented by brief irradiation with blue light. However, neither farred nor blue light affected the germination rate when spores were irradiated after the first mitosis. Therefore, the first mitosis in the spores appears to be the crucial step for photoinduction of spore germination. Furthermore, experiments using a microbeam of red or blue light demonstrated that blue light was effective only when exposed to the nucleus, and no specific intracellular photoreceptive site for red light was found in the spores. Therefore, phytochrome in the far-red absorbing form induces the first mitosis in germinating spores but prevents the subsequent mitosis in protonemata, whereas a blue-light receptor prevents the former but induces the latter.

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Section: Discussion Premitotic Positioning Of the Nucleus In Fercontrasting

confidence: 45%

Control of Mitosis by Phytochrome and a Blue-Light Receptor in Fern Spores

et al. 1997

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“…The switch from division to differentiation in spermatids may be analogous to the switch to differentiation after asymmetric cell division in plants (Bunning, 1952;Miller and Greany, 1976). The nucleus in the new small cell with a very low ratio ofcytoplasm to nuclear volume begins to differentiate immediately.…”

Section: Discussion-division Phase -mentioning

confidence: 98%

Spermatogenesis in a Homosporous Fern, Onoclea Sensibilis

Kotenko

1990

American J of Botany

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A detailed study of spermatogenesis in a homosporous fern, Onoclea sensibilis L., is presented from the formation of the first spermatogenous cell to the release of the sperm. Two different walls are deposited around the developing spermatids at specific developmental stages as opposed to one wall reported for other species. Most ultrastructural changes that occur in Onoclea during spermatid differentiation resemble those described in previous studies on other fern species, with the following exceptions: 1) A previously undescribed structure appears during midspermatid stage. This dense layer of amorphous material with a row of evenly spaced light areas occurs between the anterior portion of the mitochondrion associated with the multilayered structure and the anterior plasmalemma of the spermatid. 2) An early stage in blepharoplast formation resembles that which occurs in the heterosporous fern Marsilea, in contrast to that which has been reported in Platyzoma, the only other homosporous fern studied at this stage. 3) The osmiophilic crest does not form as early as reported in other ferns. 4) The cap cell of Onoclea is removed intact, rather than collapsing or forming a pore during sperm release. Observations are reported on the number of sperm per antheridium, the time course of spermatogenous cell mitosis, and of differentiation of spermatids into sperm. In Onoclea, an antheridium may contain either 32 or 64 sperm. Regardless of the final number of sperm, each has approximately the same volume.

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Pre-mitotic nuclear migration in subsidiary mother cells ofTradescantia occurs in G1 of the cell cycle and requires F-actin

Kennard

Cleary

1997

Cell Motil. Cytoskeleton

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We have studied pre‐mitotic nuclear migration in living subsidiary mother cells (SMCs) of Tradescantia virginiana. Divisions in the four SMCs of each stomatal complex are asymmetrical and are preceded by the migration of nuclei from random locations in the cells to positions adjacent to the central guard mother cells (GMCs). In newly polarised SMCs, nuclei display erratic movements which gradually dampen over time. In older complexes, where nuclear migration occurred earlier in the ontogeny of the leaf, nuclei are stably positioned and change in morphology from spherical to dome‐shaped. Labelling with bromodeoxyuridine (BrdU) shows that SMCs polarise in G1 of the cell cycle and remain polarised for a minimum of 22 h before entering mitosis, while the inducing GMCs stay in G1. Centrifugation (1,320g, 15 min) of epidermal peels displaces the majority of nuclei to the centrifugal end of cells, including nuclei in polarised SMCs. After centrifugation, most SMC nuclei return towards the GMCs within 100 min in control and 5 μM oryzalin treated peels. However, nuclei are unable to reposition in the presence of cytochalasin B (5 μg/ml). Thus, the signal for SMC polarisation is issued very early in the ontogeny of the cells (G1), is apparently sustained for a prolonged period, and results in the actin‐dependent migration of nuclei towards the GMC. Cytological changes and nuclear migrations similar to those occurring in polarising SMCs can be induced by a local application of pressure to the surface of epidermal cells. Cell Motil. Cytoskeleton 36:55–67, 1997. © 1997 Wiley‐Liss, Inc.

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Rhizoid Differentiation in Fern Spores: Experimental Manipulation

Cited by 23 publications

References 8 publications

Control of Mitosis by Phytochrome and a Blue-Light Receptor in Fern Spores

Control of Mitosis by Phytochrome and a Blue-Light Receptor in Fern Spores

Spermatogenesis in a Homosporous Fern, Onoclea Sensibilis

Pre-mitotic nuclear migration in subsidiary mother cells ofTradescantia occurs in G1 of the cell cycle and requires F-actin

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