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  • Maternal inheritance  (4)
  • Actin  (2)
  • Anisogamous alga  (2)
  • Biparental inheritance  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Cytoplasmic DNA apportionment and plastid differentiation during male gametophyte development in Pelargonium zonale (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 51-56 
    Details
    ISSN: 1432-2145
    Keywords: Cytoplasmic DNA apportionment ; Biparental inheritance ; Plastid differentiation ; Male gametophyte ; Pelargonium zonale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the male gametophyte of Pelargonium zonale, generative and sperm cells contain cytoplasmic DNA in high density compared to vegetative cells. Cytoplasmic DNA was examined using the DNA fluorochrome DAPI (4'6-diamidino-2-phenylindole) and observed with epifluorescence and electron microscopy. The microspore cell contains a prominent central vacuole before mitosis; mitochondria and plastids are randomly distributed throughout the cytoplasm. Following the first pollen grain mitosis, neither the vegetative cell nor the early generative cell display a distributional difference in cytoplasmic DNA, nor is there in organelle content at this stage. During the maturation of the male gametophyte, however, a significant discrepancy in plastid abundance develops. Plastids in the generative cell return to proplastids and do not contain large starch grains, while those in the vegetative cell develop starch grains and differentiate into large amyloplasts. Plastid nucleoids in generative and sperm cells in a mature male gametophyte are easily discriminated after DAPI staining due to their compactness, while those in vegetative cells stained only weakly. The utility of the hydrophilic, non-autofluorescent resin Technovit 7100 in observing DAPI fluorescence is also demonstrated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00241887
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  • 2
    Electronic Resource
    Electronic Resource
    A possible role for actin dots in the formation of the contractile ring in the ultra-micro algaCyanidium caldarium RK-1 (1998)
    Springer
    Protoplasma 202 (1998), S. 91-104 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Contractile ring ; Cyanidium caldarium RK-1 ; Cytokinesis ; Immunoelectron microscopy ; Indirect immunofluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the primitive red algaCyanidium caldarium RK-1, cytokinesis is controlled by a simple contractile ring, as in animal cells. To clarify the mechanism of formation of the contractile ring, we isolated actin genes and performed an immunocytological study.C. caldarium RK-1 has two actin genes encoding proteins with the same sequence of 377 amino acids. The primary structure indicated that the actin molecules ofC. caldarium RK-1 are typical, despite the fact that the organism is considered to be phylogenetically primitive. We prepared antiserum against aC. caldarium RK-1 actin fusion protein and indirect immunofluorescence staining was performed. In interphase cells, many actin dots were observed in the cytoplasm but none at the future cleavage plane. Prior to cytokinesis, some of these dots appeared and became aligned along the equatorial plane. At the same time, a thin “immature” contractile ring was observed to appear to be formed by connection of the aligned actin dots. This immature contractile ring thickened to nearly its maximum size by the time cytokinesis began. The formation of the contractile ring seemed to be a result of de novo assembly of actin monomers, rather than a result of the accumulation and bundling of pre-existing actin filaments. During the constriction of the contractile ring, no actin dots were observed in the cytoplasm. These observations suggest that actin dots are responsible for the formation of the contractile ring, but are not necessary for its disintegration. Furthermore, immunogold localization specific for actin revealed at electron microscopy level that fine filaments running just beneath the cleavage furrow are, in fact, actin filaments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280878
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  • 3
    Electronic Resource
    Electronic Resource
    Preferential digestion of male chloroplast nuclei and mitochondrial nuclei during gametogenesis ofBryopsis maxima Okamura (1986)
    Springer
    Protoplasma 133 (1986), S. 85-87 
    Details
    ISSN: 1615-6102
    Keywords: Maternal inheritance ; Bryopis maxima ; Anisogamous alga ; Gametogenesis ; Preferential digestion ; DNA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01293191
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  • 4
    Electronic Resource
    Electronic Resource
    Preferential degradation of plastid DNA with preservation of mitochondrial DNA in the sperm cells ofPelargonium zonale during pollen development (1997)
    Springer
    Protoplasma 197 (1997), S. 217-229 
    Details
    ISSN: 1615-6102
    Keywords: Biparental inheritance ; Fluorescence microscopy ; Immunoelectron microscopy ; Maternal inheritance ; Pelargonium zonale ; Pollen grains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the present study, we studied changes in organellar DNA in the sperm cells of maturing pollen ofPelargonium zonale, a plant typical to exhibit biparental inheritance, by fluorescence microscopy after staining with 4′,6-diamidino-2-phenylindole (DAPI) and by immunogold electron microscopy using anti-DNA antibody. Fluorescence intensities of DAPI-stained plastid nuclei in generative and sperm cells at various developmental stages were quantified with a video-intensified microscope photon counting system (VIMPCS). Results indicated that the amount of DNA per plastid in generative cells increased gradually during pollen development and reached a maximum value (about 70 T per plastid; 1 T represents the amount of DNA in a particle of T4 phage) in young sperm cells at 5 days before flowering. However, the DNA content of plastids was subsequently reduced to about 20% of the maximum value on the day of flowering. Moreover, the DNA content of the plastid further decreased to 4% of the maximum value when pollen grains were cultured for 6 h in germination medium. In contrast, the amount of DNA per mitochondrion did not decrease significantly around the flowering day. Similar results were also obtained by immunogold electron microscopy using anti-DNA antibody. The density of gold particles on plastids decreased during pollen maturation whereas labelling density on mitochondria remained relatively constant. The number of plastids and mitochondria per generative cell or per pair of sperm cells did not change significantly, indicating that the segregation of DNA by plastid division was not responsible for the decrease in the amount of DNA per plastid. These results indicate that the plastid DNA is preferentially degraded, but the mitochondrial DNA is preserved, in the sperm cells ofP. zonale. While the plastid DNA of the sperm cells decreased before fertilization, it was also suggested that the low DNA contents that remain in the plastids of the sperm cells are enough to account for the biparental inheritance of plastids inP. zonale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01288031
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  • 5
    Electronic Resource
    Electronic Resource
    Preferential digestion of chloroplast DNA in male gametangia during the late stage of gametogenesis in the anisogamous algaBryopsis maxima (1991)
    Springer
    Protoplasma 163 (1991), S. 102-113 
    Details
    ISSN: 1615-6102
    Keywords: Maternal inheritance ; Bryopsis maxima ; Anisogamous alga ; Gametogenesis ; Differential digestion ; Organelle nuclei (nucleoids)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The fate of chloroplast nuclei (cp-nuclei) and mitochondrial nuclei (mt-nuclei) was followed during gametogenesis in male and female coenocytic thalli in the anisogamous algaBryopsis maxima by epifluorescence microscopy, after staining with 4′,6-diamidino-2-phenylindole (DAPI), by quantification of chloroplast DNA (cp-DNA) by fluorimetry using a video-intensified, photon-counting system (VIMPICS), and by CsCl density gradient centrifugation. The male and female coenocytic thalli, 48 h before the release of gametes, contain a large number of chloroplasts, each of which is larger in size than the cell nucleus and the mitochondria and contains about 150 cp-nuclei. The size of each chloroplast in the female and male gametangia decreases markedly during gametogenesis as a result of continuous divisions till about 10 h before the release of gametes and, eventually, the numbers of cp-nuclei per chloroplast in the male and female gametangia fall to about 20 and 5, respectively. Two hours later, as the preferential digestion of cp-DNA in the male gametangium occurs, the number of cp-nuclei in the chloroplast of each male gamete falls to zero while the number of cp-nuclei in female gamete does not change, even after release of female gametes. Several mt-nuclei are observed in all of the female gametes. By contrast, the mt-nuclei in the bulk of the male gametes disappear but those in a few gametes remain. The profiles after CsCl density gradient centrifugation of DNAs extracted from male and female plants and gametes support the cytological data. The results suggest that the preferential digestion of cp-DNA in male plants occurs about 8 h before the release of gametes and that there is differential digestion of cp-DNA and mitochondrial DNA (mt-DNA).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323334
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  • 6
    Electronic Resource
    Electronic Resource
    Behavior of organelle nuclei (nucleoids) in generative and vegetative cells during maturation of pollen inLilium longiflorum andPelargonium zonale (1992)
    Springer
    Protoplasma 168 (1992), S. 73-81 
    Details
    ISSN: 1615-6102
    Keywords: Organelle nuclei ; Maternal inheritance ; Pollen-specific nuclease ; Lilium longiflorum ; Pelargonium zonale
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The behavior of organelle nuclei during maturation of the male gametes ofLilium longiflorum andPelargonium zonale was examined by fluorescence microscopy after staining with 4′,6-diamidino-2-phenylindole (DAPI) and Southern hybridization. The organelle nuclei in both generative and vegetative cells inL. longiflorum were preferentially degraded during the maturation of the male gametes. In the mature pollen grains ofL. longiflorum, there were absolutely no organelle nuclei visible in the cytoplasm of the generative cells. In the vegetative cells, almost all the organelle nuclei were degraded. However, in contrast to the situation in generative cells, the last vestiges of organelle nuclei in vegetative cells did not disappear completely. They remained in evidence in the vegetative cells during germination of the pollen tubes. InP. zonale, however, no evidence of degradation of organelle nuclei was ever observed. As a result, a very large number of organelle nuclei remained in the sperm cells during maturation of the pollen grains. When the total DNA isolated from the pollen or pollen tubes was analyzed by Southern hybridization with a probe that contained therbc L gene, for detection of the plastid DNA and a probe that contained thecox I gene, for detection of the mitochondrial DNA, the same results were obtained. Therefore, the maternal inheritance of the organelle genes inL. longiflorum is caused by the degradation of the organelle DNA in the generative cells while the biparental inheritance of the organelle genes inP. zonale is the result of the preservation of the organelle DNA in the generative and sperm cells. To characterize the degradation of the organelle nuclei, nucleolytic activities in mature pollen were analyzed by an in situ assay on an SDS-DNA-gel after electrophoresis. The results revealed that a 40kDa Ca2+-dependent nuclease and a 23 kDa Zn2+ -dependent nuclease were present specifically among the pollen proteins ofL. longiflorum. By contrast, no nucleolytic activity was detected in a similar analysis of pollen proteins ofP. zonale.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01332652
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  • 7
    Electronic Resource
    Electronic Resource
    Migration of the cell nucleus during the amoebo-flagellate transformation ofPhysarum polycephalum is mediated by an actin-generated force that acts on the centrosome (1991)
    Springer
    Protoplasma 163 (1991), S. 114-124 
    Details
    ISSN: 1615-6102
    Keywords: Physarum polycephalum ; DAPI ; Fluorescence microscopy ; Centrosome ; Comigration ; Centrosome migration ; Cell-nuclear migration ; Actin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The mechanism of cell-nuclear migration during the amoebo-flagellate transformation inPhysarum polycephalum was examined by fluorescence microscopy after staining with a tubulinspecific antibody, rhodamine-conjugated phalloidin and 4′,6-diamidino-2-phenylindole (DAPI). While the round amoeba cells changed to comma-shaped swarm cells within 20min after suspension in buffer, the cell nuclei moved from the central region of each cell to the periphery, each forming a sharp projection in the direction of movement. A centrosome also migrated from the center of the cell to the cell periphery. Since the centrosome was in close contact with the tip that protruded from the cell nucleus throughout the cellnuclear migration, the migration of the cell nucleus and the centrosome could be recognized as comigration. Then the flagella began to elongate from the centrosome and the cells became slender and polarized, adopting the so-called “comma-shape”. On the basis of these observations, the transformation process was classified into three steps: cell-nuclear migration, flagella formation and swarm maturation. The comigration of the cell nucleus and the centrosome was not inhibited by the anti-microtubule drug nocodazole (4 μM) but it was inhibited by the anti-microfilament drug cytochalasin A (4 μM), suggesting that the force of migration is generated by microfilaments. To investigate the role of the centrosome in this comigration in detail, we identified two aberrant strains, defective in swimming ability, from among various laboratory strains. The two strains, TM 4 and J, were found to have defects in cell-nuclear migration. Strain TM 4 had two types of irregular swarm cells: in one, only a part of the cell nucleus projected a thin filamentous structure; and in the other, no cell-nuclear migration occurred. Strain J had two centrosomes per cell and such swarm cells exhibited an attempt of cell-nuclear migration at two sites which corresponded to the position of the centrosome. The characteristics of these two strains indicate that the centrosome is essential for cell-nuclear migration. Our observations suggest that the cell-nuclear migration is mediated by actin-generated forces that act on the centrosome rather than on the cell nucleus itself.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323335
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