A study on somatic association and its relevance to meiotic pairing using haploids of barley (Hordeum vulgare, n = x = 7)

1984 ◽  
Vol 26 (3) ◽  
pp. 302-307
Author(s):  
R. N. Bhambhani ◽  
J. Kuspira ◽  
J. Kenny ◽  
R. S. Sadasivaiah
Keyword(s):  
Hordeum Vulgare ◽  
Meiotic Prophase ◽  
Random Distribution ◽  
Somatic Cells ◽  
Spatial Distributions ◽  
Meiotic Pairing

The spatial distributions of three readily identifiable chromosomes in somatic cells of monoploid barley (Hordeum vulgare, n = x = 7), as determined by the measurements of distances between them, were compared with the theoretical random distribution. None of the three distributions were found to be significantly different from the theoretical. It was therefore concluded that the three nonhomologous chromosomes in barley do not exhibit the propensity for somatic association. The implications of these results to nonhomologous pairing observed during meiotic prophase of barley monoploids are also discussed.Key words: Hordeum, barley, somatic associations, meiotic pairing, chromosome positions.

scholarly journals Statistical analysis of chromosome distribution to the poles in interspecific hybrids with variable chromosome pairing

1963 ◽  
Vol 4 (2) ◽  
pp. 266-275 ◽  
Author(s):  
A. G. Sficas
Keyword(s):  
Statistical Analysis ◽  
Interspecific Hybrids ◽  
Random Distribution ◽  
The Other ◽  
Meiotic Pairing ◽  
Variable Amount ◽  
Short Discussion ◽  
Equal Distribution ◽  
Chromosome Separation ◽  
Opposite Tendency

A probability distribution of chromosome separation to the poles was developed to test the randomness of movement of univalents in asynaptic material where a variable amount of meiotic pairing occurs. Two tables were calculated, one for 24 chromosomes which can be used for any even number equal or less than 24, and the other for 19 chromosomes which can be used for any odd number equal or less than 19.Three Nicotiana hybrids, namely N. glutinosa × N. otophora, N. glutinosa, N. sylvestris, and N. tabacum × N. glutinosa, and one polyhaploid were investigated. All hybrids had a tendency towards an equal distribution of unpaired chromosomes to the poles. The polyhaploid N. tabacum (with a substituted N. plumbaginifolia chromosome) had an opposite tendency, i.e. towards a flatter distribution than expected from random distribution of univalents. A short discussion of the problem is given.

The genome sizes of Hordeum species show considerable variation

Genome ◽  
1996 ◽  
Vol 39 (4) ◽  
pp. 730-735 ◽  
Author(s):  
Juha Kankanpää ◽  
Alan H. Schulman ◽  
Leena Mannonen
Keyword(s):  
Flow Cytometry ◽  
Hordeum Vulgare ◽  
Genome Size ◽  
Nuclear Dna ◽  
Size Variation ◽  
Nuclear Dna Content ◽  
Meiotic Pairing ◽  
Genome Size Variation ◽  
Dapi Staining ◽  
Hordeum Vulgare Ssp

Hordeum, distributed worldwide in temperate zones, is the second largest genus in the tribe Triticeae and includes diploid, tetraploid, and hexaploid species. We determined, by DAPI staining and flow cytometry, the nuclear DNA content for 35 accessions of the genus Hordeum, from a total of 19 species, including specimens of 2 cultivars and 2 landraces of Hordeum vulgare ssp. vulgare as well as samples of 12 Hordeum vulgare ssp. spontaneum populations. Genome sizes ranged from 5.69 to 9.41 pg for the G1 nuclei of the diploids, and from 13.13 to 18.36 pg for those of the tetraploids. This constitutes a 1.7-fold variation for the diploids, contrasting with a 4% variation previously reported. For H. vulgare ssp. vulgare (barley), the accessions examined differed by 18%. These variations in genome size cannot be correlated with meiotic pairing groups (I, H, X, Y) or with proposed phylogenetic relationships within the genus. Genome size variation between barley accessions cannot be related to status as cultivated or wild, or to climatic or geological gradients. We suggest these data may indicate rapid but sporadic changes in genome size within the genus. Key words : barley, Hordeum, Triticeae, genome size, flow cytometry.

Production and meiotic pairing behaviour of new hybrids of winter wheat (Triticum aestivum) × winter barley (Hordeum vulgare)

Genome ◽  
2000 ◽  
Vol 43 (6) ◽  
pp. 1045-1054 ◽  
Author(s):  
M Molnár-Láng ◽  
G Linc ◽  
A Logojan ◽  
J Sutka
Keyword(s):  
Triticum Aestivum ◽  
Hordeum Vulgare ◽  
Winter Wheat ◽  
Chromosome Pairing ◽  
Winter Barley ◽  
Barley Chromosome ◽  
Meiotic Pairing ◽  
Meiotic Analysis ◽  
Chromosome Arm

New winter wheat (Triticum aestivum L.) × winter barley (Hordeum vulgare L.) hybrids produced using cultivated varieties (wheat 'Martonvásári 9 kr1'(Mv9 kr1) × barley 'Igri', Mv9 kr1 × 'Osnova', 'Asakazekomugi' × 'Manas') were multiplied in tissue culture because of the high degree of sterility and then pollinated with wheat to obtain backcross progenies. Meiotic analysis of the hybrids Mv9 kr1 × 'Igri' and 'Asakazekomugi' × 'Manas' and their in vitro regenerated progenies with the Feulgen method revealed 1.59 chromosome arm associations per cell in both initial hybrids. The number of chromosome arm associations increased after in vitro culture to 4.72 and 2.67, respectively, in the two combinations. According to the genomic in situ hybridization (GISH) analysis, wheat-barley chromosome arm associations made up 3.6% of the total in the initial Mv9 kr1 × 'Igri' hybrid and 6.6% and 16.5% of the total in in vitro regenerated progenies of the 'Asakazekomugi' × 'Manas' and Mv9 kr1 × 'Igri' hybrids, respectively. The demonstration by GISH of wheat-barley chromosome pairing in the hybrids and especially in their in vitro regenerated progenies proves the possibility of producing recombinants between these two genera, and thus of transferring useful characters from barley into wheat. In vitro conditions caused an increase in chromosome arm association frequency in both combinations and in fertility in some regenerants.Key words: wheat, barley, intergeneric hybridization, meiotic chromosome pairing, GISH.

scholarly journals X chromosome activity in female germ cells of mice heterozygous for Searle's translocation T(X;16)16H

1981 ◽  
Vol 37 (3) ◽  
pp. 317-322 ◽  
Author(s):  
P. G. Johnston
Keyword(s):  
X Chromosome ◽  
Germ Cells ◽  
Meiotic Prophase ◽  
Somatic Cells ◽  
Phosphoglycerate Kinase ◽  
Inactive X Chromosome ◽  
Faint Band

SUMMARYThe expression of X-linked phosphoglycerate kinase (PGK-1) in germ cells from embryos heterozygous for both PGK-1 and Searle's translocation T(X; 16) 16H was examined to investigate X chromosome activity during oogenesis. The Pgk-lb allele on the translocated X chromosome was the only allele active in somatic cells of all embryos and in germ cells from 12·5 d.p.c. embryos. However, an additional faint band representing Pgk-la activity was observed in germ cells from older embryos (13·5–18·5 d.p.c.) and neonates (1–2 d.p.p.). It is concluded that there is a period when only one X chromosome is active in early female germ cells and that reactivation of the inactive X chromosome takes place just prior to meiotic prophase.

scholarly journals The zinc-finger transcription factor LSL-1 is a major regulator of the germline transcriptional program in C. elegans

2021 ◽  
Author(s):  
David Rodriguez-Crespo ◽  
Magali Nanchen ◽  
Shweta Rajopadhye ◽  
Chantal Wicky
Keyword(s):  
Meiotic Prophase ◽  
Genome Stability ◽  
Primordial Germ Cell ◽  
Somatic Cells ◽  
Specific Gene ◽  
Loss Of Function ◽  
Transcriptional Program ◽  
Germline Development ◽  
C Elegans ◽  
Germline Genes

Specific gene transcriptional programs are required to ensure proper proliferation and differentiation processes underlying the production of specialized cells during development. Gene activity is mainly regulated by the concerted action of transcription factors and chromatin proteins. In the nematode C. elegans, mechanisms that silence improper transcriptional programs in germline and somatic cells have been well studied, however, how are tissue specific sets of genes turned on is less known. LSL-1 is herein defined as a novel crucial transcriptional regulator of germline genes in C. elegans. LSL-1 is first detected in the P4 blastomere and remains present at all stages of germline development, from primordial germ cell proliferation to the end of meiotic prophase. lsl-1 loss-of-function mutants exhibit many defects including meiotic prophase progression delay, a high level of germline apoptosis, and production of almost no functional gametes. Transcriptomic analysis and ChIP-seq data show that LSL-1 binds to promoters and acts as a transcriptional activator of germline genes involved in various processes, including homologous chromosome pairing, recombination, and genome stability. Furthermore, we show that LSL-1 functions by antagonizing the action of the heterochromatin proteins HPL-2/HP1 and LET-418/Mi2 known to be involved in the repression of germline genes in somatic cells. Based on our results, we propose LSL-1 to be a major regulator of the germline transcriptional program during development.

Oogenesis in adult prosimians

Development ◽  
1967 ◽  
Vol 17 (1) ◽  
pp. 139-145
Author(s):  
J. M. Ioannou
Keyword(s):  
Germ Cells ◽  
Meiotic Prophase ◽  
Somatic Cells ◽  
Germinal Epithelium ◽  
Mammalian Development ◽  
Direct Transformation ◽  
Early Stages ◽  
Daubentonia Madagascariensis ◽  
Galago Senegalensis ◽  
Loris Tardigradus

It is widely accepted that oogenesis normally stops early in mammalian development (see Brambell, 1956; Franchi, Mandl & Zuckerman, 1962). Nevertheless, it has been claimed that mitotically active oogonia, and oocytes in early stages of meiotic prophase occur in mature specimens of Galago senegalensis (Gérard, 1920, 1932; Gérard & Herlant, 1953; Herlant, 1961; Petter-Rousseaux, 1962; Butler, 1964), G. crassicaudatus (Gérard & Herlant, 1953), G. demidoffi (Gérard, 1932; Gérard & Herlant, 1953; Petter-Rousseaux, 1962), Perodicticus potto (Gérard & Herlant, 1953), Loris tardigradus lydekkerianus (Rao, 1927; Brambell, 1930), and Daubentonia madagascariensis (Petter-Rousseaux & Bourlière, 1965). The latter is a lemuroid prosimian, while all the others are lorisoids (Hill, 1953). It has also been asserted that new germ cells are formed by direct transformation from the somatic cells of the ovarian germinal epithelium (Gérard, 1920, 1932; Rao, 1927; Gérard & Herlant, 1953).

scholarly journals Spatial constraints on chromosomes are instrumental to meiotic pairing

2020 ◽  
Vol 133 (22) ◽  
pp. jcs253724
Author(s):  
Miao Tian ◽  
Christiane Agreiter ◽  
Josef Loidl
Keyword(s):  
Meiotic Prophase ◽  
Tetrahymena Thermophila ◽  
Sequence Similarity ◽  
Meiotic Pairing ◽  
Homologous Pairing ◽  
Spatial Constraints ◽  
Homologous Chromosomes ◽  
Chromosome Arrangement ◽  
Associated Proteins ◽  
Prophase Nucleus

ABSTRACTIn most eukaryotes, the meiotic chromosomal bouquet (comprising clustered chromosome ends) provides an ordered chromosome arrangement that facilitates pairing and recombination between homologous chromosomes. In the protist Tetrahymena thermophila, the meiotic prophase nucleus stretches enormously, and chromosomes assume a bouquet-like arrangement in which telomeres and centromeres are attached to opposite poles of the nucleus. We have identified and characterized three meiosis-specific genes [meiotic nuclear elongation 1-3 (MELG1-3)] that control nuclear elongation, and centromere and telomere clustering. The Melg proteins interact with cytoskeletal and telomere-associated proteins, and probably repurpose them for reorganizing the meiotic prophase nucleus. A lack of sequence similarity between the Tetrahymena proteins responsible for telomere clustering and bouquet proteins of other organisms suggests that the Tetrahymena bouquet is analogous, rather than homologous, to the conserved eukaryotic bouquet. We also report that centromere clustering is more important than telomere clustering for homologous pairing. Therefore, we speculate that centromere clustering may have been the primordial mechanism for chromosome pairing in early eukaryotes.

END-TO-END ATTACHMENT OF HAPLOID CHROMOSOMES OF ORNITHOGALUM VIRENS

1972 ◽  
Vol 14 (3) ◽  
pp. 716-717 ◽  
Author(s):  
Terry Ashley ◽  
E. B. Wagenaar
Keyword(s):  
Meiotic Prophase ◽  
General Property ◽  
Somatic Cells ◽  
Open Chain ◽  
Haploid Nucleus ◽  
Homologous Chromosomes ◽  
Plant Chromosomes ◽  
Ring Configuration ◽  
End To End ◽  
Ornithogalum Virens

The three prophase chromosomes in the haploid nucleus of Ornithogalum virens pollen are attached end-to-end in an open chain. This lends support to the suggestion that the ring configuration, in which homologous chromosomes lie opposite one another in somatic cells, is involved in recognition and pairing of homologues during meiotic prophase. It is also suggested that affinity of ends may be a general property of plant chromosomes.

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