RESUMEN
Cytoskeletal rearrangements were studied during meiotic telophase in a number of monocotyledonous plant species. Wild type and abnormal meiosis (in wide cereal hybrids, meiotic mutants and allolines) was analyzed. It was found that central spindle fibers that move centrifugally, along with newly-formed MTs, are the basis of phragmoplast formation and function in PMCs of monocotyledonous plant species with successive cytokinesis stages. A model for centrifugal movement of the meiotic phragmoplast is proposed; this model is a modification of the corresponding process during B-anaphase.
Asunto(s)
Citocinesis , Meiosis , Células Vegetales , Centrifugación , Microtúbulos/metabolismo , Plantas/metabolismo , Polen/citología , Células Madre/citología , TelofaseRESUMEN
The abnormal cytoskeleton cycle in meiosis in pollen mother cells of cereal wide hybrids F reveals the role of polar microtubules in phragmoplast formation during successive cytokinesis. The cytoskeletal rearrangements during successive and simultaneous cytokinesis in higher plant meiosis are compared.
Asunto(s)
Agropyron/citología , Citocinesis , Meiosis , Microtúbulos/ultraestructura , Triticum/citología , Agropyron/ultraestructura , Triticum/ultraestructuraRESUMEN
Intracellular morphological processes of successive cytokinesis in cereal pollen mother cells during normal and abnormal meiosis were studied. It was shown that the central spindle fiber system transforms into a phragmoplast at telophase. A model of centrifugal movement of the phragmoplast as a modification of B-anaphase has been proposed.
Asunto(s)
Citoesqueleto/metabolismo , Meiosis , Anafase , Citocinesis , Citoesqueleto/ultraestructura , Grano Comestible/fisiología , Polen/fisiología , Huso Acromático/metabolismo , Huso Acromático/ultraestructuraRESUMEN
The mechanism of restitution nuclei formation in male meoiosis of Triticum-Agropyrum F1 hybrid and monosomic wheat line Milturum 553 has been studied. Visualization of division spindle with Navashin's routine fixationle distribution method accompanied with acetocarmine-coloured squashed preparations revealed that a block in the kinetochore spindle thread formation, i.e. the absence of chromosome association with the division spindle, is the basic reason of restitution in these genotypes. On this background, the prometaphase spindle in abnormal meiosis of these lines demonstrates a number of vivid and inordinate aberrations revealing some regularities of spindle structure in the normal plant cell.
Asunto(s)
Núcleo Celular/ultraestructura , Cromosomas de las Plantas/ultraestructura , Huso Acromático/genética , Agropyron/genética , Agropyron/ultraestructura , Cinetocoros/ultraestructura , Meiosis , Metafase , Triticum/genética , Triticum/ultraestructuraRESUMEN
Monopolar spindles in pollen mother cells of cereal wide F1 hybrids are described; details of the formation of anastral spindles are discussed.
Asunto(s)
Grano Comestible/fisiología , Meiosis/fisiología , Huso Acromático/fisiología , Grano Comestible/genética , Hibridación Genética , Meiosis/genética , Microscopía Fluorescente , Especificidad de la EspecieRESUMEN
Analyses of correspondent meiotic abnormalities is a good tool for studying cytoskeletal rearrangements during plant cell division. The paper reports on the wheat x wheatgrass F1 hybrids, showing various abnormalities during organization of the prophase perinuclear band of microtubules (PNB) in male meiosis. Based on these data, it may be concluded that the perinuclear system of microtubules (MT) in higher plant meiosis is formed from fibrils of the radial system as a result of their translocation in the cell cytoplasm space. According to our data, at this stage the radial MT arrays pass through the following consequence of events: separating from the nuclear envelope, 2) approaching, 3) tangential orientation to the nuclear surface, 4) bending, 5) co-orientation, lateral interaction. As a result, a flat ring of well organized concentric bent MT bundles encircling the nucleus meridionally is organized.
Asunto(s)
Núcleo Celular/ultraestructura , Microtúbulos/ultraestructura , Triticum/ultraestructura , Meiosis , Huso Acromático/ultraestructuraRESUMEN
The early prometaphase and initial stages of meiotic spindle formation in higher plant PMCs were studied by means of a new approach worked out by the authors: a morphological dissection that consists in the analysis of various abnormalities of the process under study. Wide cereal hybrids F1 were used as a source of such abnormalities: phenotypes with C-, S-shaped and combined spindle, with spindles surrounded by microtubule (MT) ring and phenotypes with chaotic circular MT system in M1. Three stages of early prometaphase not described before (disintegration of perinuclear MT band, straightening of its bundles, and their translocation throughout the cytoplasm) were revealed.