Pairing competition between identical and homologous chromosomes in diploid and tetraploid cells of rye telotrisomic plants

1986 ◽  
Vol 28 (4) ◽  
pp. 568-573 ◽  
Author(s):  
E. Benavente ◽  
J. Orellana
Keyword(s):  
Secale Cereale ◽  
Homologous Chromosomes ◽  
Diploid Cells

Pairing competition between identical and homologous chromosomes 1R has been directly analyzed in diploid–tetraploid chimeras of telotrisomic plants of rye Secale cereale by using C-bands as cytological markers. The results have shown pairing preferences either in diploid cells, with three doses of 1RS, and in tetraploid cells, with six doses. In both cases, the preferences found could be explained by differential pairing affinities between chromosomes.Key words: telotrisomic, rye, chimeras, banding (C), pairing.

scholarly journals PAIRING COMPETITION BETWEEN IDENTICAL AND HOMOLOGOUS CHROMOSOMES IN AUTOTETRAPLOID RYE. I. SUBMETACENTRIC CHROMOSOMES

Genetics ◽  
1985 ◽  
Vol 111 (4) ◽  
pp. 933-944
Author(s):  
J Orellana ◽  
J L Santos
Keyword(s):  
Genetic Control ◽  
Secale Cereale ◽  
Inbred Lines ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Partner Exchange ◽  
Pairing Behavior ◽  
Chromosome 1R ◽  
Heterochromatin Content

ABSTRACT Meiotic pairing preferences between identical and homologous but not identical chromosomes were analyzed in ten induced tetraploid/diploid chimaeral rye plants (Secale cereale) heterozygous for telomeric heerochromatin C-bands in both arms of chromosome 1R. These plants were the progeny of two crosses between only one plant of cv. Petkus, used as male, and two plants of the inbred lines E and R, respectively. Different pairing preferences for chromosome 1R were found: (1) between plants, (2) between chromosome arms within the same plant and (3) between bivalents and multivalents within the same plant. The possible influence in the preferences of several factors such as differences in C-heterochromatin content in the chromosomes analyzed, specific genetic control and independence in pairing behavior between both arms and partner exchange is discussed.

scholarly journals PAIRING COMPETITION BETWEEN IDENTICAL AND HOMOLOGOUS CHROMOSOMES IN RYE AND GRASSHOPPERS

Genetics ◽  
1983 ◽  
Vol 104 (4) ◽  
pp. 677-684
Author(s):  
J L Santos ◽  
J Orellana ◽  
R Giraldez
Keyword(s):  
Secale Cereale ◽  
Banding Pattern ◽  
Chromosome Pair ◽  
Meiotic Pairing ◽  
Homologous Pairing ◽  
Eyprepocnemis Plorans ◽  
Homologous Chromosomes ◽  
Random Pairing ◽  
Structural Differences ◽  
Telomeric Heterochromatin

ABSTRACT Meiotic pairing preferences between identical and homologous but not identical chromosomes were analyzed in spontaneous tetraploid/diploid chimeras of three male grasshoppers (Eyprepocnemis plorans) whose chromosome pair 11 were heterozygous for C-banding pattern and in four induced tetraploid/diploid chimaeral rye plants (Secale cereale) heterozygous for telomeric heterochromatin C-bands in chromosomes 1R and 2R. In the grasshoppers, a preference for identical over homologous pairing was observed, whereas in rye both a preference for homologous rather than identical pairing and random pairing between the four chromosomes of the set was found. From the results in rye, it can be deduced that pairing preferences do not depend exclusively on the similarities between chromosomes involved. It is suggested that genotypic or cryptic structural differences between the homologous chromosomes of each pair analyzed might be responsible for the pairing preferences found. This hypothesis can also explain the results obtained in grasshoppers, although the possibility of premeiotic association cannot be excluded in this material.

Polysomaty and somatic reduction in Phaseolus coccineus L.

Genome ◽  
1988 ◽  
Vol 30 (5) ◽  
pp. 671-676 ◽  
Author(s):  
A. Cavallini ◽  
R. Cremonini ◽  
G. Cionini ◽  
P. G. Cionini
Keyword(s):  
De Novo ◽  
Root Apex ◽  
Phaseolus Coccineus ◽  
Homologous Chromosomes ◽  
Chromosome Endoreduplication ◽  
Early Embryos ◽  
Pertinent Data ◽  
Polyploid Cells ◽  
Diploid Cells ◽  
Shoot Meristems

By means of karyological, cytophotometric, and autoradiographic analyses it has been shown that, owing to alterations in the DNA synthesis – mitosis sequence, cells with different nuclear conditions are continuously formed de novo and proliferate in Phaseolus coccineus meristems. Besides diploid cells, the following also occur: (i) polyploid cells as the result of chromosome endoreduplication followed by mitosis; (ii) haploid cells as the result of the separation of the two groups of homologous chromosomes in cells that have omitted DNA reduplication; and (iii) since haploid cells undergo chromosome endoreduplication and divide, isogenic cells can be produced. Diploid mitoses alone are present in the meristems of early embryos; haploid mitoses first appear in both root and shoot meristems with increasing embryo development, followed later by cells undergoing chromosome endoreduplication. The study of the root apex has shown that neither polyploid nor reduced cells occur with the same frequency in its various portions. These results are discussed in relation to pertinent data in the literature and the mechanisms responsible for the occurrence of polysomaty and somatic reduction are suggested.Key words: isogenic cells, Phaseolus coccineus, polysomaty, somatic reduction.

scholarly journals (CA/GT)n microsatellites affect homologous recombination during yeast meiosis

2000 ◽  
Vol 14 (10) ◽  
pp. 1261-1268
Author(s):  
Christiane-Gabrielle Gendrel ◽  
Annick Boulet ◽  
Marie Dutreix
Keyword(s):  
Repetitive Sequence ◽  
Strand Break ◽  
Repeat Sequence ◽  
Strand Exchange ◽  
Homologous Chromosomes ◽  
Yeast Meiosis ◽  
Diploid Cells ◽  
Multiple Crossovers ◽  
Combined Data

One of the most common microsatellites in eukaryotes consists of tandem arrays of the dinucleotide GT. Although the study of the instability of such repetitive DNA has been extremely fruitful over the last decade, no biological function has been demonstrated for these sequences. We investigated the genetic behavior of a region of the yeast Saccharomyces cerevisiae genome containing a 39-CA/GT dinucleotide repeat sequence. When the microsatellite sequence was present at the ARG4 locus on homologous chromosomes, diploid cells undergoing meiosis generated an excess of tetrads containing a conversion of the region restricted to the region of the microsatellite close to the recombination-initiation double-strand break. Moreover, whereas the repetitive sequence had no effect on the frequency of single crossover, its presence strongly stimulated the formation of multiple crossovers. The combined data strongly suggest that numerous recombination events are restricted to the initiation side of the microsatellite as though progression of the strand exchange initiated at the ARG4 promoter locus was impaired by the repetitive sequence. This observation corroborates in vitro experiments that demonstrated that RecA-promoted strand exchange is inhibited by CA/GT dinucleotide tracts. Surprisingly, meiotic instability of the microsatellite was very high (>0.1 alterations per tetrad) in all the spores with parental and recombinant chromosomes.

scholarly journals Imputation-free reconstructions of three-dimensional chromosome architectures in human diploid single-cells using allele-specified contacts

2021 ◽  
Author(s):  
Yoshito Hirata ◽  
Arisa H. Oda ◽  
Chie Motono ◽  
Masanori Shiro ◽  
Kunihiro Ohta
Keyword(s):  
Chromosome Structure ◽  
Single Cells ◽  
Three Dimensional ◽  
Recurrence Plot ◽  
Human Chromosomes ◽  
Fractal Structures ◽  
Homologous Chromosomes ◽  
Allele Specific ◽  
Human Diploid Cells ◽  
Diploid Cells

AbstractThe sparseness of chromosomal contact information and the presence of homologous chromosomes with very similar nucleotide sequences make Hi-C analysis difficult. We propose a new algorithm using allele-specific single-nucleotide variations (SNVs) to reconstruct the three-dimensional (3D) chromosomal architectures from the Hi-C dataset of single diploid cells. Our algorithm has a function to discriminate SNVs specifically found between homologous chromosomes to our “recurrence plot”-based algorithm to estimate the 3D chromosome structure, which does not require imputation for ambiguous segment information. The new algorithm can efficiently reconstruct 3D chromosomal structures in single human diploid cells by employing only Hi-C segment pairs containing allele-specific SNVs. The datasets of the remaining pairs of segments without allele-specific SNVs are used to validate the estimated chromosome structure. This approach was used to reconstruct the 3D structures of human chromosomes in single diploid cells at a 1-Mb resolution. Introducing a subsequent mathematical measure further improved the resolution to 40-kb or 100-kb. The reconstruction data reveals that human chromosomes form chromosomal territories and take fractal structures where the mean dimension is a non-integer value. We also validate our approach by estimating 3D protein/polymer structures.

Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I

1987 ◽  
Vol 7 (4) ◽  
pp. 1425-1435
Author(s):  
H T Wang ◽  
S Frackman ◽  
J Kowalisyn ◽  
R E Esposito ◽  
R Elder
Keyword(s):  
Genetic Recombination ◽  
Developmental Regulation ◽  
Maximum Level ◽  
Mitotic Cell ◽  
Sporulation Medium ◽  
Developmentally Regulated ◽  
Type Locus ◽  
Homologous Chromosomes ◽  
Diploid Cells ◽  
Meiosis I

Previous studies have demonstrated that the SPO13 gene is required for chromosome separation during meiosis I in Saccharomyces cerevisiae. In the presence of the spo13-1 nonsense mutation, MATa/MAT alpha diploid cells complete a number of events typical of meiosis I including premeiotic DNA synthesis, genetic recombination, and spindle formation. Disjunction of homologous chromosomes, however, fails to occur. Instead, cells proceed through a single meiosis II-like division and form two diploid spores. In this paper, we report the cloning of this essential meiotic gene and an analysis of its transcription during vegetative growth and sporulation. Disruptions of SPO13 in haploid and diploid cells show that it is dispensible for mitotic cell division. Diploids homozygous for the disruptions behave similarly to spo13-1 mutants; they sporulate at wild-type levels and produce two-spored asci. The DNA region complementing spo13-1 encodes two overlapping transcripts, which have the same 3' end but different 5' ends. The major transcript is 400 bases shorter than the larger, less abundant one. The shorter RNA is sufficient to complement the spo13-1 mutation. While both transcripts are undetectable or just barely detectable in vegetative cultures, they each undergo a greater than 70-fold induction early during sporulation, reaching a maximum level about the time of the first meiotic division. In synchronously sporulating populations, the transcripts nearly disappear before the completion of ascus formation. Nonsporulating cells homozygous for the mating-type locus show a small increase in abundance (less than 5% of the increase in sporulating cells) of both transcripts in sporulation medium. These results indicate that expression of the SPO13 gene is developmentally regulated and starvation alone, independent of the genotype at MAT, can trigger initial induction.

TELOMERIC ASSOCIATIONS OF GAMETIC AND SOMATIC CHROMOSOMES IN DIPLOID AND AUTOTETRAPLOID ORNITHOGALUM VIRENS

1974 ◽  
Vol 16 (1) ◽  
pp. 61-76 ◽  
Author(s):  
Terry Ashley ◽  
E. B. Wagenaar
Keyword(s):  
Meiotic Prophase ◽  
Pollen Grain ◽  
Root Tip ◽  
Open Chain ◽  
Homologous Chromosomes ◽  
End To End ◽  
A Chain ◽  
Diploid Cells ◽  
Ornithogalum Virens ◽  
Haploid Pollen

In acetocarmine root-tip squashes, diploid cells of Ornithogalum virens in prophase exhibit configurations resulting from end-to-end associations of the six chromosomes. Homologues lie opposite one another in a ring. Prophase chromosomes of the autotretraploid cells likewise associate end-to-end; however, four homogues instead of two generally lie adjacent to one another and four (or eight) ends are often connected instead of the two (or four) found in diploid cells. Prophase chromosomes in a haploid pollen grain of a diploid form an open chain of three chromosomes, whereas in pollen from the autotetraploid balanced gametes form a configuration in which homologous pairs lie adjacent to one another and are attached end-to-end to other homologous pairs of nonhomologous chromosomes to form a chain. These observations are discussed in terms of the role telomeric associations may play in recognition and pairing of homologous chromosomes during meiotic prophase. This recognition of homologues may occur as early as syngamy.

scholarly journals Developmental regulation of SPO13, a gene required for separation of homologous chromosomes at meiosis I.

1987 ◽  
Vol 7 (4) ◽  
pp. 1425-1435 ◽  
Author(s):  
H T Wang ◽  
S Frackman ◽  
J Kowalisyn ◽  
R E Esposito ◽  
R Elder
Keyword(s):  
Genetic Recombination ◽  
Developmental Regulation ◽  
Maximum Level ◽  
Mitotic Cell ◽  
Sporulation Medium ◽  
Developmentally Regulated ◽  
Type Locus ◽  
Homologous Chromosomes ◽  
Diploid Cells ◽  
Meiosis I

Previous studies have demonstrated that the SPO13 gene is required for chromosome separation during meiosis I in Saccharomyces cerevisiae. In the presence of the spo13-1 nonsense mutation, MATa/MAT alpha diploid cells complete a number of events typical of meiosis I including premeiotic DNA synthesis, genetic recombination, and spindle formation. Disjunction of homologous chromosomes, however, fails to occur. Instead, cells proceed through a single meiosis II-like division and form two diploid spores. In this paper, we report the cloning of this essential meiotic gene and an analysis of its transcription during vegetative growth and sporulation. Disruptions of SPO13 in haploid and diploid cells show that it is dispensible for mitotic cell division. Diploids homozygous for the disruptions behave similarly to spo13-1 mutants; they sporulate at wild-type levels and produce two-spored asci. The DNA region complementing spo13-1 encodes two overlapping transcripts, which have the same 3' end but different 5' ends. The major transcript is 400 bases shorter than the larger, less abundant one. The shorter RNA is sufficient to complement the spo13-1 mutation. While both transcripts are undetectable or just barely detectable in vegetative cultures, they each undergo a greater than 70-fold induction early during sporulation, reaching a maximum level about the time of the first meiotic division. In synchronously sporulating populations, the transcripts nearly disappear before the completion of ascus formation. Nonsporulating cells homozygous for the mating-type locus show a small increase in abundance (less than 5% of the increase in sporulating cells) of both transcripts in sporulation medium. These results indicate that expression of the SPO13 gene is developmentally regulated and starvation alone, independent of the genotype at MAT, can trigger initial induction.

The ultrastructure of acinar cells in the external orbital gland of young and old male rats

1978 ◽  
Vol 36 (2) ◽  
pp. 276-277
Author(s):  
R. Carriere
Keyword(s):  
Young Adulthood ◽  
Acinar Cells ◽  
Cell Number ◽  
Male Rats ◽  
Polyploid Cell ◽  
Secretory Cells ◽  
Age Changes ◽  
Albino Rat ◽  
Golgi Membranes ◽  
Diploid Cells

The external orbital gland of the albino rat exhibits both sexual dimorphism and histological age changes. In males, many cells attain a remarkable degree of polyploidy and an increase of polyploid cell number constitutes the major age change until young adulthood. The acini of young adults have a small lumen and are composed of tall serous cells. Subsequently, many acini acquire a larger lumen with an irregular outline while numerous vacuoles accumulate throughout the secretory cells. At the same time, vesicular acini with a large lumen surrounded by pale-staining low cuboidal diploid cells begin to appear and their number increases throughout old age. The fine structure of external orbital glands from both sexes has been explored and in considering acinar cells from males, emphasis was given to the form of the Golgi membranes and to nuclear infoldings of cytoplasmic constituents.

Ultrastructure of primary spermatocyte in fish (Tilapia: Oreochromis niloticus): The synaptonemal complex

1986 ◽  
Vol 44 ◽  
pp. 288-289
Author(s):  
T. Guha ◽  
A. Q. Siddiqui ◽  
P. F. Prentis
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Synaptonemal Complex ◽  
Oreochromis Niloticus ◽  
Short Communication ◽  
Primary Spermatocyte ◽  
Mitotic Division ◽  
Meiotic Cell ◽  
Electron Microscope Level ◽  
Homologous Chromosomes

The Primary Spermatocytes represent a stage in spermatogenesis when the first meiotic cell division occurs. They are derived from Spermatogonium or Stem cell through mitotic division. At the zygotene phase of meiotic prophase the Synaptonemal complex appears in these cells in the space between the paired homologous chromosomes. Spermatogenesis and sperm structure in fish have been studied at the electron microscope level in a few species? However, no work has yet been reported on ultrastructure of tilapia, O. niloticus, spermatozoa and spermatogenetic process. In this short communication we are reporting the Ultrastructure of Primary Spermatocytes in tilapia, O. niloticus, and the fine structure of synaptonemal complexes seen in the spermatocyte nuclei.

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