Complete meiotic pairing of crested newt chromosomes

Genome ◽  
1995 ◽  
Vol 38 (6) ◽  
pp. 1105-1111 ◽  
Author(s):  
H. Wallace ◽  
B. M. N. Wallace
Keyword(s):  
Synaptonemal Complex ◽  
Genome Size ◽  
Chromosome Pairing ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Direct Observations ◽  
Crested Newt ◽  
The Individual ◽  
Complex Length ◽  
Complex Genome

The longest chromosome (number 1) of Trituturus cristatus carries a heteromorphic segment, a heterozygosity perpetuated by a balanced lethal system. The heteromorphic segment is regarded as achiasmate and has been claimed to be asynaptic. Direct observations of chromosome pairing in spermatocytes and oocytes yield some cases where all homologous chromosomes appear to be completely paired, but the individual bivalents could not be identified as pachytene is not particularly clear in this species. The long arms of bivalent 1 usually remain attached by a terminal chiasma in spermatocytes of T. c. cristatus but the corresponding chiasma is only rarely present in T. c. carnifex spermatocytes. Synaptonemal complexes have been measured in both spermatocytes and oocytes of T. c. cristatus. A karyotype constructed from these measurements matches the main features of somatic and lampbrush chromosome karyotypes, indicating that all chromosomes must be completely paired and proportionately represented as synaptonemal complex. The total length of synaptonemal complex is much the same in spermatocytes and oocytes and is similar to the length in spermatocytes of Xenopus laevis. These two amphibian examples supplement a recent survey of other vertebrate classes to reinforce its conclusion that synaptonemal complex length is not related to genome size in vertebrates.Key words: chromosome pairing, synaptonemal complex, genome size, amphibia.

The initiation of meiotic chromosome pairing: the cytological view

Genome ◽  
1990 ◽  
Vol 33 (6) ◽  
pp. 759-778 ◽  
Author(s):  
Josef Loidl
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Meiotic Chromosome ◽  
Meiotic Pairing ◽  
Cytological Evidence ◽  
Homologous Chromosomes ◽  
Synaptonemal Complex Formation ◽  
Meiotic Synapsis ◽  
The One ◽  
First Contact

Opposing views are held with respect to the time when and the mechanisms whereby homologous chromosomes find each other for meiotic synapsis. On the one hand, some evidence has been presented for somatic homologous associations or some other kind of relationship between chromosomes in somatic cells as a preliminary to meiotic pairing. On the other hand, it is argued by many that homologous contacts are first established at meiotic prophase prior to, or in the course of, synaptonemal complex formation. The present paper reviews the controversial cytological evidence, hypotheses, and ideas on how the first contact between homologous chromosomes comes about.Key words: synapsis, meiosis, presynaptic alignment, homologous recognition, synaptonemal complex, chromosome pairing.

Inferences from genetical evidence on the course of meiotic chromosome pairing in plants

1977 ◽  
Vol 277 (955) ◽  
pp. 313-326 ◽  
Keyword(s):  
Chromosome Pairing ◽  
Developmental Stages ◽  
Meiotic Chromosome ◽  
Critical Assessment ◽  
Gene Control ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Meiotic Chromosome Pairing ◽  
Combined Use ◽  
Or Gene

Meiotic chromosome pairing is a process that is amenable to genetic and experimental analysis. The combined use of these two approaches allows for the process to be dissected into several finite periods of time in which the developmental stages of pairing can be precisely located. Evidence is now available, in particular in plants, that shows that the pairing of homologous chromosomes, as observed at metaphase I, is affected by events occurring as early as the last premeiotic mitosis; and that the maintenance of this early determined state is subsequently maintained by constituents (presumably proteins) that are sensitive to either colchicine, temperature or gene control. A critical assessment of this evidence in wheat and a comparison of the process of pairing in wheat with the course of meiotic pairing in other plants and animals is presented.

The relationship between synaptonemal complex length and genome size in four vertebrate classes (Osteicthyes, Reptilia, Aves, Mammalia)

1994 ◽  
Vol 2 (2) ◽  
pp. 153-162 ◽  
Author(s):  
Daniel G. Peterson ◽  
Stephen M. Stack ◽  
Joseph L. Healy ◽  
Bryon S. Donohoe ◽  
Lorinda K. Anderson
Keyword(s):  
Synaptonemal Complex ◽  
Genome Size ◽  
The Relationship ◽  
Complex Length

Meiotic pairing in wheat–rye addition and substitution lines

1984 ◽  
Vol 26 (1) ◽  
pp. 25-33 ◽  
Author(s):  
J. Orellana ◽  
M. C. Cermeño ◽  
J. R. Lacadena
Keyword(s):  
Chromosome Pairing ◽  
Chinese Spring ◽  
Constitutive Heterochromatin ◽  
Banding Technique ◽  
Addition Line ◽  
Meiotic Pairing ◽  
Addition Lines ◽  
Substitution Lines ◽  
Homologous Chromosomes ◽  
Complex Process

Chromosome pairing was examined in wheat–rye addition and substitution lines using the C-banding technique. It was found that both rye and wheat chromosomes affect each other's homologous pairing. The strongest diminution of wheat pairing (measured as bound arms per cell) was produced by chromosome 5R of rye (7.5 and 7.2% in 'Chinese Spring' – 'Imperial' and 'Holdfast' – 'King II' addition lines, respectively). The weakest diminution of wheat pairing was produced by chromosome 3R in the 'Chinese Spring' – 'Imperial' addition line (1.1%). The diminution of rye chromosome pairing produced by wheat chromosomes ranges from 6.9 to 48.4% ('Chinese Spring' – 'Imperial' and 'Holdfast' – 'King II' addition lines, respectively). When put into a wheat background, the rye chromosomes suffer a worse fate than the wheat chromosomes. For example, chromosome 6R reduces the wheat complement pairing in the 'Holdfast' – 'King II' addition line by 3.8% but its own pairing is reduced by 41.4%. The decrease in pairing of both wheat and rye homologous chromosomes in addition and substitution lines is a complex process in which factors such as genes controlling meiotic pairing, constitutive heterochromatin, and cryptic wheat–rye interactions can play important roles.

Synaptonemal complex analysis of hybrid cattle. III. Meiotic pairing mechanisms in F1 Brahman × Hereford hybrids

Genome ◽  
1991 ◽  
Vol 34 (2) ◽  
pp. 228-235 ◽  
Author(s):  
A. E. Dollin ◽  
J. D. Murray ◽  
C. B. Gillies
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Complex Analysis ◽  
Bos Taurus ◽  
Bos Indicus ◽  
Meiotic Pairing ◽  
Homoeologous Chromosome ◽  
Homoeologous Chromosome Pairing ◽  
Synaptonemal Complex Analysis ◽  
Complex Hybrid

The mechanisms of homoeologous chromosome pairing were studied in synaptonemal complex (SC) spreads of F1 Brahman (Bos indicus) × Hereford (Bos taurus) cattle. The most common SC abnormalities were bivalents with partial pairing failure and interlocks. While C-band polymorphisms could underlie most of the SC abnormalities observed in the full-blood cattle, other causes seem also to be contributing in the hybrids. The pattern of the abnormalities indicates that genie differences between the species were probably involved. Pachytene substaging data suggest that in some spreads, early pachytene bivalents with partial pairing failure may achieve complete synapsis or may be converted to interlocks by late pachytene.Key words: synaptonemal complex, hybrid cattle, interlocks.

Ultrastructure of meiotic pairing in B chromosomes of Crepis capillaris. I. One-B and two-B pollen mother cells

Genome ◽  
1989 ◽  
Vol 32 (4) ◽  
pp. 611-621 ◽  
Author(s):  
G. H. Jones ◽  
J. A. F. Whitehorn ◽  
S. M. Albini
Keyword(s):  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Complex Surface ◽  
B Chromosome ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Pollen Mother Cells ◽  
Crepis Capillaris ◽  
Axis Length ◽  
Mother Cells

Chromosome pairing of a small metacentric B chromosome in Crepis capillaris has been studied by synaptonemal complex surface spreading of pollen mother cells containing either one or two B chromosomes. The B-chromosome axis, on average, represents about 8.7% of the axis length of the standard A-chromosome set, which is less than the corresponding values for DNA content (10.6%) and mitotic chromosome volume (13.6%). Single B chromosomes commonly undergo fold-back pairing to give a symmetrical hairpin loop, which supports earlier suggestions that this B chromosome is an isochromosome. Two B chromosomes may show interarm pairing, exclusively, or interchromosome pairing, exclusively, or combinations of the two. Near the centromeres pairing occurs preferentially between arms of the same chromosome, but chromosome ends show random association. Some B chromosomes show anomalous pairing configurations, which may reflect further orders of reverse repeats within arms or, alternatively, nonhomologous pairing. The period of B-chromosome pairing is confined almost exclusively to zygotene, when the standard A chromosomes are pairing, but within this period their pairing is delayed relative to the A set. Individual B chromosomes at zygotene contain from one to three separate synaptonemal complex segments. These are widely distributed within the chromosomes, mainly in distal and interstitial regions; pairing is delayed around the centromere.Key words: B chromosomes, isochromosomes, synaptonemal complex.

Light and electron microscope observations of a meiotic mutant of Neurospora crassa

1978 ◽  
Vol 56 (21) ◽  
pp. 2694-2706 ◽  
Author(s):  
B.C. Lu ◽  
Donna R. Galeazzi
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Genetic Analysis ◽  
Neurospora Crassa ◽  
Synaptonemal Complex ◽  
Chromosome Pairing ◽  
Light And Electron Microscopy ◽  
Homologous Chromosomes ◽  
Synaptonemal Complexes ◽  
Nuclear Separation

Light and electron microscopy have revealed that the meiotic-1 (mei-1) mutant of Neurospora crassa is defective in chromosome pairing (asynaptic) although plenty of axial components of the synaptonemal complex are produced and occasional tripartite synaptonemal complexes can be formed. The mei-1 mutant is most probably defective in bringing the homologous chromosomes together for pairing and for assembly of the synaptonemal complex. The mei-1 mutant is also defective in nuclear separation which leads to a four-poled spindle at the subsequent division. The lack of chromosome pairing, the incomplete assembly of the synaptonemal complex, and the four-poled spindles account for absence of recombination and for the nondisjunction found in genetic analysis.

THE EFFECT OF GENES CONTROLLING DIFFERENT DEGREES OF HOMOEOLOGOUS PAIRING ON QUADRIVALENT FREQUENCY IN INDUCED AUTOTETRAPLOID LINES OF TRITICUM LONGISSIMUM

1976 ◽  
Vol 18 (2) ◽  
pp. 357-364 ◽  
Author(s):  
Lydia Avivi
Keyword(s):  
Chromosome Pairing ◽  
Chiasma Frequency ◽  
Spatial Separation ◽  
Meiotic Pairing ◽  
Homoeologous Pairing ◽  
Homologous Pairing ◽  
Homologous Chromosomes ◽  
Chromosomal Pairing ◽  
Per Se ◽  
Quadrivalent Frequency

Different genotypes of Triticum longissimum are known to either promote or suppress chromosome pairing in crosses with polyploid wheats. Lines that promote homoeologous pairing are here designated as intermediate pairing lines, while those which have no such effect or suppress pairing are known as low pairing lines. To determine a possible effect of these genotypes on homologous pairing, tetraploidy was induced in both lines and chromosomal pairing was studied at first metaphase of meiosis. While the two induced autotetraploids did not differ in chiasma frequency or in the number of paired chromosomal arms, they differed significantly in multivalent frequency; the intermediate-pairing autotetraploid exhibited the same multivalent frequency as that expected on the basis of two telomeric initiation sites, while the low pairing autotetraploid exhibited a significantly lower frequency. It is assumed that in the autotetraploid the low pairing genotype does not affect meiotic pairing per se, but modifies the pattern of homologous association in a similar manner to that known in polyploids and caused by diploidization genes. It is speculated that the tendency for bivalent pairing in the low pairing autotetraploid is due to spatial separation of the four homologous chromosomes in somatic and premeiotic cells into two groups of two.

scholarly journals HOP1: a yeast meiotic pairing gene.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 445-462 ◽  
Author(s):  
N M Hollingsworth ◽  
B Byers
Keyword(s):  
Synaptonemal Complex ◽  
Structural Basis ◽  
Recessive Mutation ◽  
Intragenic Recombination ◽  
Meiotic Pairing ◽  
Homologous Chromosomes ◽  
Homolog Pairing ◽  
Chromosomal Pairing ◽  
Chromosome Iii ◽  
Cloned Gene

Abstract The recessive mutation, hop1-1, was isolated by use of a screen designed to detect mutations defective in homologous chromosomal pairing during meiosis in Saccharomyces cerevisiae. Mutants in HOP1 displayed decreased levels of meiotic crossing over and intragenic recombination between markers on homologous chromosomes. In contrast, assays of the hop1-1 mutation in a spo13-1 haploid disomic for chromosome III demonstrated that intrachromosomal recombination between directly duplicated sequences was unaffected. The spores produced by SPO13 diploids homozygous for hop1 were largely inviable, as expected for a defect in interhomolog recombination that results in high levels of nondisjunction. HOP1 was cloned by complementation of the spore lethality phenotype and the cloned gene was used to map HOP1 to the LYS11-HIS6 interval on the left arm of chromosome IX. Electron microscopy revealed that diploids homozygous for hop1 fail to form synaptonemal complex, which normally provides the structural basis for homolog pairing. We propose that HOP1 acts in meiosis primarily to promote chromosomal pairing, perhaps by encoding a component of the synaptonemal complex.

The relationship between genome size and synaptonemal complex length in higher plants

1985 ◽  
Vol 156 (2) ◽  
pp. 367-378 ◽  
Author(s):  
L ANDERSON ◽  
S STACK ◽  
M FOX ◽  
Z CHUANSHAN
Keyword(s):  
Synaptonemal Complex ◽  
Genome Size ◽  
Higher Plants ◽  
The Relationship ◽  
Complex Length
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