B-chromosome behaviour in Phaulacridium vittatum

Chromosoma ◽  
1974 ◽  
Vol 46 (2) ◽  
pp. 181-195 ◽  
Author(s):  
Bernard John ◽  
Michael Freeman
Keyword(s):  
B Chromosome ◽  
Chromosome Behaviour

Influence of DNA methylation on rye B-chromosome nondisjunction

Genome ◽  
1992 ◽  
Vol 35 (4) ◽  
pp. 650-652 ◽  
Author(s):  
N. Neves ◽  
A. Barāo ◽  
A. Castilho ◽  
M. Silva ◽  
L. Morais ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Chromosome Number ◽  
High Frequency ◽  
Somatic Cells ◽  
B Chromosome ◽  
Pollen Grain ◽  
Chromosome Behaviour ◽  
Root Cells ◽  
Control Root ◽  
Chromosome Nondisjunction

Regulation of nondisjunction of the rye B chromosome was investigated using the cytidine analog 5-azacytidine, which affects DNA methylation. The B chromosome of rye normally undergoes nondisjunction at first pollen grain mitosis and is stable at all other mitotic nuclear divisions. Observations on mitosis in the control root cells showed normal chromosome behaviour, whereas the treated roots were characterized by a high frequency of anaphases with lagging chromosomes showing evidence of failure of chromatid separation. The occurrence of nondisjunction was confirmed by the presence of variable numbers of B chromosomes between cells within roots, whereas the A-chromosome number remained constant. These results suggest that the epigenetic process by which somatic cells maintain the inactivity of the gene(s) responsible for B chromosome nondisjunction, between fertilization and meiosis, is mediated through DNA methylation.Key words: B chromosome, DNA methylation, meiotic reprogramming, 5-azacytidine, rye.

scholarly journals Repetitive DNA landscape in essential A and supernumerary B chromosomes of Festuca pratensis Huds

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Rahman Ebrahimzadegan ◽  
Andreas Houben ◽  
Ghader Mirzaghaderi
Keyword(s):  
Repetitive Sequences ◽  
Nuclear Genome ◽  
B Chromosome ◽  
B Chromosomes ◽  
Festuca Pratensis ◽  
Ltr Retrotransposons ◽  
Chromosome Identification ◽  
Satellite Repeats ◽  
Low Pass ◽  
Illumina Sequence

AbstractHere, we characterized the basic properties of repetitive sequences in essential A and supernumerary B chromosomes of Festuca pratensis Huds. This was performed by comparative analysis of low-pass Illumina sequence reads of B chromosome lacking (−B) and B chromosome containing (+B) individuals of F. pratensis. 61% of the nuclear genome is composed of repetitive sequences. 43.1% of the genome are transposons of which DNA transposons and retrotransposons made up 2.3% and 40.8%, respectively. LTR retrotransposons are the most abundant mobile elements and contribute to 40.7% of the genome and divided into Ty3-gypsy and Ty1-copia super families with 32.97% and 7.78% of the genome, respectively. Eighteen different satellite repeats were identified making up 3.9% of the genome. Five satellite repeats were used as cytological markers for chromosome identification and genome analysis in the genus Festuca. Four satellite repeats were identified on B chromosomes among which Fp-Sat48 and Fp-Sat253 were specific to the B chromosome of F. pratensis.

B chromosome in a rice aneuploid variation

2000 ◽  
Vol 101 (4) ◽  
pp. 564-568 ◽  
Author(s):  
Z. K. Cheng ◽  
H. X. Yu ◽  
H. H. Yan ◽  
M. H. Gu ◽  
L. H. Zhu
Keyword(s):  
B Chromosome

MEIOSIS IN THE GRASSHOPPER. II. THE PRELEPTOTENE SPIRAL STAGE DURING OOGENESIS AND SPERMATOGENESIS IN MELANOPLUS FEMUR-RUBRUM

1972 ◽  
Vol 14 (2) ◽  
pp. 397-401 ◽  
Author(s):  
Kathleen Church
Keyword(s):  
Dna Synthesis ◽  
Crossing Over ◽  
Chromosome Behaviour ◽  
Homologous Chromosomes ◽  
Diploid Complement

Chromosome behaviour occurring from premeiotic DNA synthesis to leptotene of meiosis is described for both males (spermatogenesis) and females (oogenesis) in the grasshopper Melanoplus femur-rubrum. These events include a period of chromosome spiralization and contraction following premeiotic DNA synthesis and prior to leptotene. The diploid complement of chromosomes becomes visible in both sexes. No pairing between homologous chromosomes or chiasmata are observed in either sex. The results suggest that synapsis and crossing over must occur following preleptotene spiralization during spermatogenesis and oogenesis in this grasshopper.

scholarly journals Spatial organization of fibroblast and spermatocyte nuclei with different B-chromosome content in Korean field mouse, Apodemus peninsulae (Rodentia, Muridae)

Genome ◽  
2017 ◽  
Vol 60 (10) ◽  
pp. 815-824 ◽  
Author(s):  
Tatyana V. Karamysheva ◽  
Anna A. Torgasheva ◽  
Yaroslav R. Yefremov ◽  
Anton G. Bogomolov ◽  
Thomas Liehr ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Spatial Organization ◽  
Constitutive Heterochromatin ◽  
B Chromosome ◽  
B Chromosomes ◽  
Laser Scanning Microscopy ◽  
Field Mouse ◽  
Apodemus Peninsulae ◽  
Basic Set ◽  
Korean Field Mouse

Korean field mouse (Apodemus peninsulae) shows a wide variation in the number of B chromosomes composed of constitutive heterochromatin. For this reason, it provides a good model to study the influence of the number of centromeres and amount of heterochromatin on spatial organization of interphase nuclei. We analyzed the three-dimensional organization of fibroblast and spermatocyte nuclei of the field mice carrying a different number of B chromosomes using laser scanning microscopy and 3D fluorescence in situ hybridization. We detected a co-localization of the B chromosomes with constitutive heterochromatin of the chromosomes of the basic set. We showed a non-random distribution of B chromosomes in the spermatocyte nuclei. Unpaired B chromosomes showed a tendency to occur in the compartment formed by the unpaired part of the XY bivalent.

scholarly journals Maternal imprinting effect on B chromosome transmission in rye

Heredity ◽  
1990 ◽  
Vol 64 (2) ◽  
pp. 197-204 ◽  
Author(s):  
M J Puertas ◽  
M M Jiménez ◽  
F Romera ◽  
J M Vega ◽  
M Díez
Keyword(s):  
B Chromosome ◽  
Chromosome Transmission ◽  
Maternal Imprinting
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