Ultrastructure of meiotic pairing in B chromosomes of Crepis capillaris

Chromosoma ◽  
1991 ◽  
Vol 100 (3) ◽  
pp. 193-202 ◽  
Author(s):  
G. H. Jones ◽  
S. M. Albini ◽  
J. A. F. Whitehorn
Keyword(s):  
B Chromosomes ◽  
Meiotic Pairing ◽  
Crepis Capillaris

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.

Structural hybridity and supernumerary chromosomes in a diploid Tradescantia hirsuticaulis

1975 ◽  
Vol 53 (5) ◽  
pp. 456-465 ◽  
Author(s):  
C. C. Chinnappa
Keyword(s):  
Reciprocal Translocation ◽  
Cytological Study ◽  
B Chromosomes ◽  
The Other ◽  
Meiotic Pairing ◽  
Structural Hybridity ◽  
Supernumerary Chromosomes

Cytological study of a diploid (2n = 12) population of Tradescantia hirsuticaulis Small from Stone Mountain, Georgia, revealed striking variation in four plants growing in a cluster, indicating that they constitute different genotypes. The occurrence of B chromosomes, fragments, and aneusomaty in the plants is associated with structural hybridity in the chromosomes. Two plants were homozygotes with simple meiotic pairing, one was heterozygous for a reciprocal translocation, and the other was a heterozygote for two interchanges as well as for inversions. The behavior and the origin of B chromosomes, fragments, and structural hybridity are discussed.

Characterisation of repeated sequences from microdissected B chromosomes of Crepis capillaris

Chromosoma ◽  
1995 ◽  
Vol 104 (2) ◽  
pp. 113-120 ◽  
Author(s):  
M. Jamilena ◽  
M. Garrido-Ramos ◽  
M. Ruiz Rej�n ◽  
C. Ruiz Rej�n ◽  
J. S. Parker
Keyword(s):  
B Chromosomes ◽  
Repeated Sequences ◽  
Crepis Capillaris

scholarly journals The population cytogenetics of Crepis capillaris IV. The distribution of B-chromosomes in British populations

Heredity ◽  
1991 ◽  
Vol 66 (2) ◽  
pp. 211-218 ◽  
Author(s):  
J S Parker ◽  
G H Jones ◽  
L A Edgar ◽  
C Whitehouse
Keyword(s):  
B Chromosomes ◽  
Crepis Capillaris

scholarly journals Molecular relationship between the A and B chromosomes of Crepis capillaris

Heredity ◽  
1994 ◽  
Vol 73 (5) ◽  
pp. 527-531 ◽  
Author(s):  
M Jamilena ◽  
M Garrido-Ramos ◽  
C Ruiz Rejón ◽  
M Ruiz Rejón
Keyword(s):  
B Chromosomes ◽  
Crepis Capillaris

scholarly journals Influence of the Presence of B Chromosomes on DNA Damage in Crepis capillaris

PLoS ONE ◽  
2014 ◽  
Vol 9 (1) ◽  
pp. e87337 ◽  
Author(s):  
Jolanta Kwasniewska ◽  
Agnieszka Mikolajczyk
Keyword(s):  
Dna Damage ◽  
B Chromosomes ◽  
Crepis Capillaris

scholarly journals The population cytogenetics of Crepis capillaris. II. The stability and inheritance of B-chromosomes

Heredity ◽  
1989 ◽  
Vol 63 (1) ◽  
pp. 19-27 ◽  
Author(s):  
J S Parker ◽  
G H Jones ◽  
L Edgar ◽  
C Whitehouse
Keyword(s):  
B Chromosomes ◽  
Crepis Capillaris ◽  
The Stability

Enhanced meiotic chromosome pairing in intergeneric hybrids between Triticum aestivum and diploid Inner Mongolian Agropyron

Genome ◽  
1992 ◽  
Vol 35 (1) ◽  
pp. 98-102 ◽  
Author(s):  
Qin Chen ◽  
Joseph Jahier ◽  
Yvonne Cauderon
Keyword(s):  
Triticum Aestivum ◽  
Chromosome Pairing ◽  
Inner Mongolia ◽  
Meiotic Chromosome ◽  
Embryo Rescue ◽  
Genetic System ◽  
Intergeneric Hybrids ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Reciprocal Hybrids

Triticum aestivum cv. Chinese Spring (2n = 6x = 42, ABD genomes) was crossed with diploid Inner Mongolian Agropyron Gaertn. species A. cristatum and A. mongolicum and reciprocal hybrids between them (2n = 2x = 14, P genome, with or without B chromosomes). Intergeneric hybrids with 2n = 27, 28, 32, and 33 chromosomes were produced by the aid of embryo rescue. The extra chromosomes in two hybrids were assumed to be B chromosomes transmitted by the male Agropyron parent. Average meiotic pairing in the euploid hybrid with 28 chromosomes was 14.38 univalents + 4.92 bivalents + 1.26 trivalents. This level of pairing higher than expected was likely due to homeologous associations between wheat chromosomes. This data indicates that the P genome of diploid as well as tetraploid Agropyron originating from Inner Mongolia possess a genetic system interfering with 5B homoeologous restricting system of wheat.Key words: intergeneric hybrids, Triticum aestivum, diploid Agropyron species, chromosome pairing.

Factors affecting the meiotic pairing behaviour of B chromosomes in the grasshopper Eyprepocnemis plorans

1984 ◽  
Vol 26 (6) ◽  
pp. 664-668 ◽  
Author(s):  
N. Henriques-Gil ◽  
P. Arana ◽  
J. L. Santos
Keyword(s):  
Chiasma Frequency ◽  
Chiasma Formation ◽  
B Chromosome ◽  
B Chromosomes ◽  
Meiotic Pairing ◽  
Eyprepocnemis Plorans ◽  
Factors Affecting ◽  
Chiasma Localization ◽  
A Site ◽  
Pairing Behaviour

A study of the meiotic behaviour of different B-chromosome variants in the acridid grasshopper Eyprepocnemis plorans demonstrates that pairing and chiasma formation in these supernumerary chromosomes depend both on genotypic factors and on the structure of the B chromosomes themselves. Genotypic effects are evidenced by the differences in chiasma frequency which the same B-chromosome combinations show in different individuals. Structural effects can be inferred from the fact that 9 of the 14 known known B variants carry a unique site to which interstitial chiasmata are confined, whereas such a site is lacking in the other five variants.Key words: B chromosomes, C-bands, chiasma frequency, chiasma localization.

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