Autoradiography of Soluble [2-14C]Thymidine Derivatives During Meiosis And Microsporogenesis in Lilium Anthers

1967 ◽  
Vol 2 (3) ◽  
pp. 387-400 ◽  
Author(s):  
J. HESLOP-HARRISON ◽  
A. MACKENZIE
Keyword(s):  
Meiotic Prophase ◽  
Trichloroacetic Acid ◽  
Thymidine Incorporation ◽  
Callose Wall ◽  
Autoradiographic Method ◽  
Tapetal Cells ◽  
Mother Cells

A dry autoradiographic method suitable for locating soluble tracers has been used to follow the fate of [2-14C]thymidine supplied to detached buds and inflorescences of Lilium henryi and a related cultivar. During the interval from the archesporial phase until pachytene, the derivative (or derivatives) reaching the anther loculi moved freely into the meiocytes. Subsequently, the tracer was excluded from the mother cells until the dissolution of the tetrads. The young spores readily took up tracer in the thecal fluid upon their release, and yielded strongly localized autoradiographs. These observations are interpreted as indicating that access of materials to the meiocytes is related to the formation of cytoplasmic links between mother cells in the early meiotic prophase, and the later severance of these links through the growth of the isolating callose wall which comes to invest the tetrads. Judged from the tracer retained in preparations extracted with trichloroacetic acid, thymidine incorporation occurs mostly in the premeiotic and early leptotene period, although there is some slight evidence of incorporation later in prophase. In the tapetal cells, incorporation occurred in most of the stages tested, but there was no indication of a transfer of labelled materials from tapetum to spores in the post-meiotic period.

scholarly journals Nuclear dispositions of subtelomeric and pericentromeric chromosomal domains during meiosis in asynaptic mutants of rye (Secale cereale L.)

2001 ◽  
Vol 114 (10) ◽  
pp. 1875-1882 ◽  
Author(s):  
E.I. Mikhailova ◽  
S.P. Sosnikhina ◽  
G.A. Kirillova ◽  
O.A. Tikholiz ◽  
V.G. Smirnov ◽  
...  
Keyword(s):  
Secale Cereale ◽  
Meiotic Prophase ◽  
Male Meiosis ◽  
Subsequent Stage ◽  
Centromeric Sequence ◽  
Tapetal Cells ◽  
Secale Cereale L ◽  
Mother Cells ◽  
Subtelomeric Regions

The nuclear dispositions of subtelomeric and pericentromeric domains in pollen mother cells (PMCs) were tracked during meiosis in wildtype and two asynaptic mutants of rye (Secale cereale L.) by means of fluorescence in situ hybridization (FISH). Homozygotes for sy1 and sy9 non-allelic mutations form axial elements during leptotene of male meiosis, but fail to form synaptonemal complexes. Consequently, recombination is severely impaired, and high univalency is observed at metaphase I. Simultaneous FISH with pSc200 subtelomeric tandem repeat and CCS1 centromeric sequence revealed that at pre-meiotic interphase the two domains are in a bipolar Rabl orientation in both the PMCs and tapetal cells. At the onset of meiotic prophase, the subtelomeric regions in PMCs of wildtype and sy9 cluster into a typical bouquet conformation. The timing of this event in rye is comparable with that in wheat, and is earlier than that observed in other organisms, such as maize, yeast and mammals. This arrangement is retained until later in leptotene and zygotene when the pericentromeric domains disperse and the subtelomeric clusters fragment. The mutant phenotype of sy9 manifests itself during leptotene to zygotene, when the pericentromeric regions become distinctly more distended than in wildtype, and largely fail to pair during zygotene. This indicates that difference in the nature or timing of chromosome condensation in this region is the cause or consequence of asynapsis. By contrast, sy1 fails to form comparable aggregates of subtelomeric regions at leptotene in only half of the nuclei studied. Instead, two to five aggregates are formed that fail to disperse at later stages of meiotic prophase. In addition, the pericentromeric regions disperse prematurely at leptotene and do not associate in pairs at any subsequent stage. It is supposed that the sy1 mutation could disrupt the nuclear disposition of centromeres and telomeres at the end of pre-meiotic interphase, which could cause, or contribute to, its asynaptic phenotype.

Development of the Quadripolar Meiotic Cytoskeleton in Spore Mother Cells of the Moss Funaria Hygrometrica

1988 ◽  
Vol 91 (1) ◽  
pp. 127-137
Author(s):  
C. H. BUSBY ◽  
B.E. S. GUNNING
Keyword(s):  
Meiotic Prophase ◽  
Metaphase Plate ◽  
Plant Cells ◽  
Preprophase Band ◽  
The Other ◽  
Higher Plant ◽  
Funaria Hygrometrica ◽  
Condensed Form ◽  
Prophase Nucleus ◽  
Mother Cells

Evidence presented in the accompanying paper that plastids function as microtubule (MT)-organizing centres for development of the quadripolar cytoskeleton of pre-meiotic spore mother cells (SMCs) in the moss Funaria hygrometrica is complemented here by observations on the MT system in these cells. Early in meiotic prophase numerous MTs align progressively along the two plastids as they elongate. Concomitant with (and perhaps causal for) plastid rotation, new MT arrays grow from each tip of each plastid to both tips of the other plastid. The ‘along-plastid’ and ‘between-plastid’ arrays ultimately form the edges of a tetrahedron, enclosing the prophase nucleus. MT breakdown at the centre of each edge leaves four cones of MTs, one emanating from each vertex, located at the plastid tips. These partially fuse in between-plastid pairs to give a twisted spindle with broad knife-edge poles oriented at right angles to one another, i.e. a condensed form of the quadripolar precursor. The twist causes the metaphase plate and the subsequent phragmoplast and organelle band to be saddle-shaped, and the daughter nuclei to be elongated perpendicular to one another along the two knife edges. The tetrahedral array returns during interkinesis and again breaks down into four cones of MTs centred on the plastid tips; these, however, now become individual half spindles for the two perpendicularly arranged second division spindles. When meiosis is completed the four haploid nuclei thus come to lie at the vertices of a tetrahedron that was established by MT-mediated plastid positioning during meiotic prophase. The tetrahedral cage of MTs precedes meiosis yet predicts the planes of division, and in these two respects it is the meiotic counterpart of the preprophase band of MTs, which develops before mitosis in most higher plant cells.

scholarly journals THE EFFECT OF X-RAYS ON CHROMOSOMES IN DIFFERENT STAGES OF MEIOSIS

1935 ◽  
Vol 19 (1) ◽  
pp. 179-198 ◽  
Author(s):  
A. Marshak
Keyword(s):  
Linear Relationship ◽  
Meiotic Prophase ◽  
Sensitive Volume ◽  
X Rays ◽  
Homologous Pairing ◽  
Linkage Mechanism ◽  
Pollen Mother Cells ◽  
X Ray ◽  
Protein Molecules ◽  
Mother Cells

1. Pollen mother cells exposed to low dosages of x-rays at various stages show different frequencies of chromosome abnormalities in the first meiotic anaphase. 2. Maximum frequencies of abnormalities were obtained in buds irradiated in the pachytene stage of the meiotic prophase and in the preceding mitosis. 3. These results are taken to indicate that the x-ray-sensitive portions of the chromonemata are closely approximated in pairs in pachytene and in the early mitotic prophase. The significance of this in relation to non-homologous pairing is indicated. 4. From the nature of the chromosome configurations observed it is concluded that chromonemata are two-parted when they synapse and that a chromonematic division occurs between pachytene and anaphase and during the mitotic prophase. 5. The frequencies of abnormalities show a linear relationship to dosage. 6. The diameter of the sensitive volume of the chromonema is calculated and found to approximate the diameter of some known protein molecules. 7. The linkage mechanism is found to make up about 90 per cent of the total sensitive volume which corresponds with the approximate reduction in length of the chromonema from pachytene to anaphase. 8. The relation of these sensitive volumes to the gene is discussed.

scholarly journals Development of the pollen in the antarctic flowering plant Colobanthus quitensis (Kunth) Bartl.

2012 ◽  
Vol 60 (2) ◽  
pp. 3-8 ◽  
Author(s):  
Irena Giełwanowska ◽  
Anna Bochenek ◽  
Ewa Szczuka
Keyword(s):  
Osmotic Stress ◽  
Flowering Plant ◽  
Natural Conditions ◽  
Callose Wall ◽  
Colobanthus Quitensis ◽  
Mother Cells ◽  
The Antarctic

<i>Colobanthus quitensis</i> (Kunth) Bartl. produced two types very small bisexual fl owers. In the Antarctic natural conditions chasmogamic and cleistogamic fl owers most often form fi ve stamina with short fi laments. Two microsporangia with a three-layer wall form in the anther. Microspore mother cells, which develop into microspores after meiosis, form inside the microsporangium. Microsporocytes of <i>Colobanthus quitensis</i> are surrounded with a thick callose layer, the special wall. After meiosis, the callose wall is dissolved and microspores are released from the tetrad. The production of proorbicules, orbicules and peritapetal membrane, and the construction of a complex sporoderm with numerous apertural sites were observed. When microspore and pollen protoplasts underwent necrosis, probably as a result of temperature and osmotic stress, sporoderm layers formed around microspores, and the cell tapetum did not disintegrate. However, woody wall layers did not accumulate in endothecium cells.

scholarly journals The Organization and Polarity of Pollen Mother Cells of Triticum Aestivum

1972 ◽  
Vol 11 (3) ◽  
pp. 699-711
Author(s):  
G. A. DOVER
Keyword(s):  
Triticum Aestivum ◽  
Ploidy Levels ◽  
Pollen Mother Cells ◽  
Time Of Application ◽  
Naturally Occurring ◽  
Aegilops Sharonensis ◽  
Pollen Types ◽  
Tapetal Cells ◽  
Meiotic Spindles ◽  
Mother Cells

Colchicine has been applied to young developing anthers of Triticum aestivum at varying stages of maturity from the last premeiotic mitoses of the archesporial and tapetal cells to the second meiotic divisions of the pollen mother cells. The developmental stage of the archesporium at which colchicine took effect was determined by cytological examination of the ploidy levels of the nuclei of the adjacent tapetal cells. The type of pollen abnormality induced depended on the time of application and the concentration of colchicine. Uninucleate monads with 4 randomly positioned pores and uninucleate monads without pores were obtained with 0.5% colchicine. Multipored polyads and multipored uninucleate monads were observed together in anthers treated with 0.01% colchicine. Naturally occurring aberrant pollen types in hybrids of Triticum aestivum x Aegilops mutica or T. aestivum x Aegilops sharonensis have revealed a constant relationship between the disposition of the meiotic spindles and the siting of the pollen pores. The colchicine-induced abnormalities have further clarified the nature of this relationship leading to the interpretation that both the positioning of the spindles and the siting of the pores are predetermined by events taking place in the premeiotic interphase at a time just after the last mitosis of the pollen mother cells and the penultimate mitosis of the tapetum. A reorganization of the archesporial cells (sensitive to colchicine) possibly occurs at this time. Various subsequent meiotic events are dependent on the reorganization. Two of these events - the organization of meiotic spindles and the establishment of pollen symmetry - are discussed.

Fine Structure of Meiotic Prophase Chromosomes in Lilium Longiflorum

1967 ◽  
Vol 25 ◽  
pp. 88-89
Author(s):  
Peter B. Moens
Keyword(s):  
Electron Microscopy ◽  
Drosophila Melanogaster ◽  
Meiotic Prophase ◽  
Lilium Longiflorum ◽  
Nurse Cells ◽  
Tomato Plants ◽  
Regional Conference ◽  
Mother Cells ◽  
European Regional ◽  
Dipteran Species

The presence of the tripartite ribbon within synapsed homologues has been reported for a large number of sexually reproducing organisms (over one hundred species, including fungi, plants, vertebrates and invertebrates). The absence of the ribbon in some species is associated with uncommon synaptic behaviour of meiotic prophase chromosomes (Drosophila melanogaster males, Drosophila melanogaster females homozygous for synapsis suppressing mutant C3G, and achiasmatic Dipteran species, reported by G. F. Meyer, 1964, Third European Regional Conference on Electron Microscopy). The tripartite ribbon, or synaptinemal complex, may therefore be assumed to be related to pairing of homologues at meiosis. The presence of the complexes and multi-complexes in non-meiotic cells such as insect obcyte nurse cells and spermatids suggests a somewhat broader function of the complexes. This is further supported by the occurrence of complexes in non-homologous paired chromosomes in the pollen mother cells of haploid tomato plants.

A light and electron microscopic study of microsporogenesis in Azolla microphylla

1985 ◽  
Vol 86 ◽  
pp. 53-58 ◽  
Author(s):  
Y. R. Herd ◽  
E. G. Cutter ◽  
I. Watanabe
Keyword(s):  
Dense Material ◽  
Electron Microscopic ◽  
Electron Dense Material ◽  
Azolla Microphylla ◽  
Dense Cytoplasm ◽  
Transmission Electron ◽  
Tapetal Cells ◽  
Electron Microscopes ◽  
Mother Cells ◽  
Membranous Material

SynopsisMicrosporogenesis in cultured material of Azolla microphylla was studied with the light and transmission electron microscopes. The first formed sporangium, a megasporangium, aborts and several microsporangia develop below. Initially, a single sporogenous cell is present, surrounded by a single layered tapetum and the microsporangial wall. Subsequently, several sporogenous cells are connected by plasmodesmata. The microspore mother cells are less densely cytoplasmic than the tapetal cells. Callose-like material is deposited around the microspore mother cells, but disappears before meiosis. The tetrads of microspores contain well defined organelles but less dense cytoplasm than the surrounding periplasmodium. Electron dense material deposited on the plasma membrane of the microspores eventually forms the endospore. The unornamented exospore develops by continued deposition of electron dense material. Degeneration of the periplasmodium gives rise to membranous material which appears to form a template for the massulae.

Developmental changes in DNA methylation of pollen mother cells of David lily during meiotic prophase I

2010 ◽  
Vol 44 (5) ◽  
pp. 754-759 ◽  
Author(s):  
Junjun Huang ◽  
Huahua Wang ◽  
Xiaojun Xie ◽  
Huanhuan Gao ◽  
Guangqin Guo
Keyword(s):  
Dna Methylation ◽  
Meiotic Prophase ◽  
Developmental Changes ◽  
Pollen Mother Cells ◽  
Prophase I ◽  
Meiotic Prophase I ◽  
Mother Cells
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