FINE STRUCTURE OF CHROMOSOME COILING AT MEIOTIC PROPHASE IN RHOEO DISCOLOR

1972 ◽  
Vol 14 (4) ◽  
pp. 801-808 ◽  
Author(s):  
Peter B. Moens
Keyword(s):  
Fine Structure ◽  
Nuclear Envelope ◽  
Meiotic Prophase ◽  
Synaptonemal Complexes ◽  
Pollen Mother Cells ◽  
Mother Cells

Most, if not all of the ends of synaptonemal complexes in Rhoeo discolor pollen mother cells are attached to the nuclear envelope. At least the first 4 μm of complex adjacent to the nuclear envelope is tightly coiled. Since each of the lateral elements is associated with one chromosome it means that the two homologues of the bivalent are relationally coiled in the distal segments.

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.

Meiosis in triploid Lolium. I. Synaptonemal complex formation and chromosome configurations at metaphase I in aneuploid autotriploid L. multiflorum

Genome ◽  
1994 ◽  
Vol 37 (2) ◽  
pp. 181-189 ◽  
Author(s):  
Huw M. Thomas ◽  
Barry J. Thomas
Keyword(s):  
Complex Formation ◽  
Synaptonemal Complex ◽  
Lolium Multiflorum ◽  
Synaptonemal Complexes ◽  
Pollen Mother Cells ◽  
Partner Exchange ◽  
Synaptonemal Complex Formation ◽  
Mother Cells ◽  
Axial Element ◽  
Metaphase I

A spreading technique for synaptonemal complexes (SCs) was applied to pollen mother cells of two aneuploid genotypes of autotriploid Lolium multiflorum (2n = 3x + 1 = 22). In the earliest nuclei analyzed the axial elements are in six groups of 3 and one group of 4. Most groups have formed multivalents with from one to five pairing partner exchanges, but there are also groups that have formed bivalents and univalents. Some axial elements have formed triple associations, in one case for the length of the trivalent. Unsynapsed axial elements remain aligned with their homologous SCs into pachytene, but this alignment is abolished as these axes pair heterologously among themselves until the entire axial element complement is synapsed. At metaphase I most chromosomes are associated as trivalents and quadrivalents.Key words: Lolium, triploid, pairing partner exchange, chiasma, multivalent.

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

scholarly journals Cytoplasniic differentiation during microsporogenesis in higher plants

2014 ◽  
Vol 50 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
H. Dichinnson
Keyword(s):  
Meiotic Prophase ◽  
Messenger Rna ◽  
Higher Plants ◽  
Pollen Mother Cells ◽  
Cytoplasmic Rna ◽  
Low Levels ◽  
Mother Cells ◽  
New Generation

Conspicuous cytoplasmic dedifferentiation in the pollen mother cells takes place early in the meiotic prophase of many plants. This event involves the removal of much of the cytoplasmic RNA. and the differentiation of both plastids and mitochondria to approaching the sole expression of their genomes. Much of the RNA removed from the cytoplasm passes to the nucleoplasm where it is utilised in the construction of a new `generation' of ribusomes. These new ribosomes are incorporated into cytoplasmic `nuclewhich disintegrate in the post-meiotic cytoplasm, restoring its ribosomes to pre-prophase levels. These changes are interpreted as evidence of a process by which the cytoplasm is cleansed of sporophytic control elements, both for the expression of the new gametophytic genome, and in the female cells of higher plants, for transmission to the new generation. The absence of control elements (presumably long-term messenger RNA) from the cytoplasm would result in the dedifferentiation observed in the organelles, and the low levels of reserves in these cells presumably results in characteristically lengthy and unusual redifferentiation of both plastids and mitochondria, once information-carrying molecules again enter the cytosol.

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