Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sen...Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sensitive male sterile line (Peiai 64S) of rice were studied using immunofluorescence confocal microscopy. In IR36, from pre-meiotic interphase to metaphase I, the pattern of microtubule distribution in the meiocytes underwent a series of changes. Some new organizational patterns of microtubules (that have not been described before) were observed during microsporogenesis, including the existence of a broad band of perinuclear microtubules at the diakinesis stage of development. The pattern of microtubule distribution in the meiocytes of the male sterile line, Peiai 64S, was quite different front that seen in IR36. In Peiai 64S, the microtubules showed abnormal patterns of distribution from pre-meiotic interphase to metaphase I. For example the broad band of perinuclear microtubules seen at diakinesis in IR36 was much disorganized and loosened in Peiai 64S. The spindles formed were also very abnormal and different from the normal spindle. The appearance of abnormal microtubule distribution in the early stages of microsporogenesis may contribute to the malformation and ultimate abortion of pollen in Peiai 64S.展开更多
Changes in the patterns of microtubular distributions and organization in various stages of development of the embryo sac in rice ( Oryza saliva L.) were different. In the megasporocyte, most microtubules were radiall...Changes in the patterns of microtubular distributions and organization in various stages of development of the embryo sac in rice ( Oryza saliva L.) were different. In the megasporocyte, most microtubules were radially distributed but some were longitudinally oriented. Similar distributional patterns were seen in the dyad cells and the functional megaspore. Microtubules in the uni-nucleate embryo sac were mostly randomly distributed, although some radiated type was also present. The pattern of distribution of the microtubules in the two and four-nucleate embryo sac was quite similar and the microtubules were mainly of the perinuclear type. Microtubules in the cells of the eight-nucleate embryo sac were more complex. In the egg cell, the microtubules were mostly randomly distributed whereas in the synergids they were predominantly in longitudinal alignment. Those in the central cell were transversely aligned. The antipodal mass had very few microtubules and few longitudinally aligned ones were present in the cytoplasm.展开更多
Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, ...Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, A005-G-T-1-2. Observations were made on pollen at four major developmental stages, viz. I. uni-nucleate microspore stage; II. early bi-cellular pollen stage; III. late bi-cellular pollen stage; and IV. tri-cellular pollen stage. At each of these developmental stages vegetative nucleus, generative nucleus/ cell, and sperm cells were seen undergoing continuous and coordinated motion and migration. These movements seemed to be influenced by associated microfilament networks existing in the pollen. Based on these observations we propose that it is the interaction between the microfilament networks (usually one existing in the central cytoplasm and another in the cortex) that controls the dynamic movement of the vegetative nucleus, generative nucleus/cell and sperm cells. Furthermore, we have also observed that there is an array of microfilaments (oriented mostly parallel to the long axis of the cell) existing in the generative and sperm cells. As far as we are aware, this is the first report showing the existence of microfilaments in living generative and sperm cells of rice pollen. The implication and significance of the existence of microfilaments in generative and sperm cells in rendering self-propelled motion of these cells in relation to their passage and movement in the pollen tube and embryo sac for fertilization were discussed.展开更多
Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could b...Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could be visualized only in the late_developmental stage of the immature pollen. During this developmental stage, microfilaments, initially composed of very short fibrils, develop into a very complex and novel network that sometimes totally and sometimes partially encloses the vegetative nucleus and the spherical shaped generative cell in the central cytoplasm of the immature pollen. The behavior of the actin microfilamentous structure throughout the late_developmental stage of the immature pollen is extremely dynamic, and the likelihood of this structure in generating forces for vegetative nucleus and generative cell movement in the immature pollen has been discussed. No actin filaments were visualized in the spherical generative cells.展开更多
Changes in the pattern of microtubule distribution and organization during megagametogenesis in the embryo sac of rice (Oryza sativa L. cv. IR36) were re-examined using a modified polyethylene glycol sectioning techni...Changes in the pattern of microtubule distribution and organization during megagametogenesis in the embryo sac of rice (Oryza sativa L. cv. IR36) were re-examined using a modified polyethylene glycol sectioning technique before immuno-fluorescence staining of microtubules. In the sectioned materials the pattern of distribution and structural organization of the microtubule cytoskeleton were quite well preserved. Fine details of the patterns of structural changes and re-organization of the microtubule cytoskeleton in the major stages of development during embryo sac megagametogenesis (viz. functional megaspore, uni-nucleate, 2-nucleate, 4-nucleate, 8-nucleate and mature stage) could be clearly observed and easily followed. Some new organizational patterns of microtubules associated with the probable movement and positioning of the polar nuclei were observed.展开更多
文摘Changes in the pattern of organization of microtubules in the meiotic stages of development of pollen (i.e. from pre-meiotic interphase to more or less metaphase I) of a normal (IR36) and a temperature/photoperiod sensitive male sterile line (Peiai 64S) of rice were studied using immunofluorescence confocal microscopy. In IR36, from pre-meiotic interphase to metaphase I, the pattern of microtubule distribution in the meiocytes underwent a series of changes. Some new organizational patterns of microtubules (that have not been described before) were observed during microsporogenesis, including the existence of a broad band of perinuclear microtubules at the diakinesis stage of development. The pattern of microtubule distribution in the meiocytes of the male sterile line, Peiai 64S, was quite different front that seen in IR36. In Peiai 64S, the microtubules showed abnormal patterns of distribution from pre-meiotic interphase to metaphase I. For example the broad band of perinuclear microtubules seen at diakinesis in IR36 was much disorganized and loosened in Peiai 64S. The spindles formed were also very abnormal and different from the normal spindle. The appearance of abnormal microtubule distribution in the early stages of microsporogenesis may contribute to the malformation and ultimate abortion of pollen in Peiai 64S.
文摘Changes in the patterns of microtubular distributions and organization in various stages of development of the embryo sac in rice ( Oryza saliva L.) were different. In the megasporocyte, most microtubules were radially distributed but some were longitudinally oriented. Similar distributional patterns were seen in the dyad cells and the functional megaspore. Microtubules in the uni-nucleate embryo sac were mostly randomly distributed, although some radiated type was also present. The pattern of distribution of the microtubules in the two and four-nucleate embryo sac was quite similar and the microtubules were mainly of the perinuclear type. Microtubules in the cells of the eight-nucleate embryo sac were more complex. In the egg cell, the microtubules were mostly randomly distributed whereas in the synergids they were predominantly in longitudinal alignment. Those in the central cell were transversely aligned. The antipodal mass had very few microtubules and few longitudinally aligned ones were present in the cytoplasm.
文摘Green fluorescent protein (GFP) fused to the F-actin binding domain of mouse talin labels the actin cytoskeleton in the living generative and sperm cells of a third generation transgenic rice (Oryza sativa L.) plant, A005-G-T-1-2. Observations were made on pollen at four major developmental stages, viz. I. uni-nucleate microspore stage; II. early bi-cellular pollen stage; III. late bi-cellular pollen stage; and IV. tri-cellular pollen stage. At each of these developmental stages vegetative nucleus, generative nucleus/ cell, and sperm cells were seen undergoing continuous and coordinated motion and migration. These movements seemed to be influenced by associated microfilament networks existing in the pollen. Based on these observations we propose that it is the interaction between the microfilament networks (usually one existing in the central cytoplasm and another in the cortex) that controls the dynamic movement of the vegetative nucleus, generative nucleus/cell and sperm cells. Furthermore, we have also observed that there is an array of microfilaments (oriented mostly parallel to the long axis of the cell) existing in the generative and sperm cells. As far as we are aware, this is the first report showing the existence of microfilaments in living generative and sperm cells of rice pollen. The implication and significance of the existence of microfilaments in generative and sperm cells in rendering self-propelled motion of these cells in relation to their passage and movement in the pollen tube and embryo sac for fertilization were discussed.
文摘Green fluorescent protein (GFP) fused to the F_actin binding domain of mouse talin labels the actin cytoskeleton in the immature pollen of stable transformed rice (Oryza sativa L.) plants. Actin microfilaments could be visualized only in the late_developmental stage of the immature pollen. During this developmental stage, microfilaments, initially composed of very short fibrils, develop into a very complex and novel network that sometimes totally and sometimes partially encloses the vegetative nucleus and the spherical shaped generative cell in the central cytoplasm of the immature pollen. The behavior of the actin microfilamentous structure throughout the late_developmental stage of the immature pollen is extremely dynamic, and the likelihood of this structure in generating forces for vegetative nucleus and generative cell movement in the immature pollen has been discussed. No actin filaments were visualized in the spherical generative cells.
文摘Changes in the pattern of microtubule distribution and organization during megagametogenesis in the embryo sac of rice (Oryza sativa L. cv. IR36) were re-examined using a modified polyethylene glycol sectioning technique before immuno-fluorescence staining of microtubules. In the sectioned materials the pattern of distribution and structural organization of the microtubule cytoskeleton were quite well preserved. Fine details of the patterns of structural changes and re-organization of the microtubule cytoskeleton in the major stages of development during embryo sac megagametogenesis (viz. functional megaspore, uni-nucleate, 2-nucleate, 4-nucleate, 8-nucleate and mature stage) could be clearly observed and easily followed. Some new organizational patterns of microtubules associated with the probable movement and positioning of the polar nuclei were observed.
