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 Cytological Analyses in ‘Niagara Branca’ Grape and in Its Somatic Mutant ‘Niagara Rosada’

2014 ◽  
Vol 42 (2) ◽  
pp. 460-465 ◽  
Author(s):  
Neiva Izabel PIEROZZI ◽  
Mara Fernandes MOURA
Keyword(s):  
Chromosome Number ◽  
Somatic Cells ◽  
Pollen Grain ◽  
Breeding Programs ◽  
Stomatal Size ◽  
Mean Values ◽  
Gene Level ◽  
The Mean ◽  
The Difference ◽  
Somatic Mutant

An investigation in the microsporogenesis of two cultivars of grapes (Vitis L.), were carried out on ‘Niagara Branca’ and on its somatic mutant ‘Niagara Rosada’, aiming at ascertaining the normality of the microsporogenesis. Some possible changes have been checked on chromosome number in somatic cells, pollen size and fertility, stomatal size and frequency, which related to the somatic mutant ‘Niagara Rosada’, thus increasing the information already obtained regarding ‘Niagara’ grapevines. The microsporogenesis occurred normally in both cultivars and cytomixis observed only among pachytene cells. A low percentage of precocious chromosome segregation was noticed in metaphase I and II, as well as a very low percentage of laggard and stickiness chromosomes in anaphase I and II. Less than 1% of tetrads showed microspore alterations. The mean values of the meiotic index and pollen grain fertility were high. However, no association were observed between the occurrences of chromosome abnormalities and the variation in the anther number (five to seven) seen among flower buds. The cultivars showed the same chromosome number, n=19 at diakinesis and 2n=38 in somatic cells, and did not differ in regards to stomatal size and frequency. It seems that the difference between the cultivars lied at gene level. Due to the very low percentage of abnormalities and to high pollen grain fertility, the plants analyzed could be very well employed in breeding programs for the grapevines.

The Chromosome Numbers and Nuclear Cytology of Some Common British Serpulids

1960 ◽  
Vol s3-101 (56) ◽  
pp. 395-400
Author(s):  
S. DASGUPTA ◽  
A. P. AUSTIN
Keyword(s):  
Chromosome Number ◽  
Chromosome Numbers ◽  
Somatic Cells ◽  
Diploid Chromosome Number ◽  
Iron Alum ◽  
Artificial Fertilization ◽  
Nuclear Cytology

The chromosome numbers of Hydroides norvegica, Mercierella enigmatica, and Pomatoceros triqueter were determined from squashes of somatic cells in young embryos obtained by artificial fertilization, and stained with iron-alum/aceto-carmine. All had a diploid count of zn = 26 chromosomes. Mitotic and meiotic divisions in the 5 species of Spirorbis examined, and in Filograna implexa, all revealed a diploid chromosome number of 2n = 20. A diploid chromosome number of 14 is suggested for the ancestral serpulid.

Dosage dependence of maternal contribution to somatic cell division in Drosophila melanogaster

Development ◽  
1991 ◽  
Vol 113 (4) ◽  
pp. 1357-1364 ◽  
Author(s):  
M. Carmena ◽  
C. Gonzalez ◽  
J. Casal ◽  
P. Ripoll
Keyword(s):  
Drosophila Melanogaster ◽  
Cell Division ◽  
Somatic Cell ◽  
Early Development ◽  
Normal Cell ◽  
Chromosome Behaviour ◽  
Wild Type ◽  
Maternal Contribution ◽  
Different Doses ◽  
Chromosome Nondisjunction

Most mitotic mutants in Drosophila do not lead to lethality in early development despite the highly abnormal chromosome behaviour that they elicit. This has been explained as being the effect of maternally provided wild-type products. We have tested this hypothesis by studying cuticular clones derived from cells in which there has been loss of a marked Y chromosome due to chromosome nondisjunction in individuals homozygous for the mutation abnormal spindle who are progeny of heterozygous mothers. We have found that the size and frequency of these clones are higher than in control flies. Furthermore, by analysing flies whose female parents have different doses of the asp+ gene, we have found that there is a correlation between the amount of maternally contributed asp+ product and the frequency and size of cuticular clones. We have also estimated the time in development when the first mitotic mistakes take place, i.e. the time when maternal products are no longer sufficient to carry out normal cell division.

Meiotic chromosome behaviour in Cenchrus ciliaris

Bothalia ◽  
1998 ◽  
Vol 28 (1) ◽  
pp. 83-90 ◽  
Author(s):  
N. C. Visser ◽  
J. J. Spies
Keyword(s):  
Chromosome Number ◽  
Meiotic Chromosome ◽  
Basic Chromosome Number ◽  
Chromosome Behaviour ◽  
Meiotic Abnormalities ◽  
Single Specimen ◽  
Cenchrus Ciliaris ◽  
Basic Chromosome ◽  
Single Genome ◽  
Meiotic Irregularities

A basic chromosome number of x = 9 has been confirmed for Cenchrus ciliaris L. Polyploidy is common and levels vary from tetraploid to hexaploid. Aneuploidv is reported for a single specimen, where two chromosomes of a single genome were lost. Various meiotic irregularities were observed. The highest incidence of meiotic abnormalities was observed in the pentaploid specimens. This was attributed to their uneven polyploid level All specimens varied from segmental alloploid to alloploid.

High frequency of alterations in DNA methylation in adenocarcinoma of the prostate

The Prostate ◽  
1999 ◽  
Vol 39 (3) ◽  
pp. 166-174 ◽  
Author(s):  
Simon Santourlidis ◽  
Andrea Florl ◽  
Rolf Ackermann ◽  
Hans-Christian Wirtz ◽  
Wolfgang A. Schulz
Keyword(s):  
Dna Methylation ◽  
High Frequency ◽  
Adenocarcinoma Of The Prostate

B-chromosome Systems in the Greater Glider (Petauroides volans volans) (Marsupialia : Petauridae). I. B-chromosome Distribution

1985 ◽  
Vol 38 (1) ◽  
pp. 189 ◽  
Author(s):  
Leon R McQuade
Keyword(s):  
Bone Marrow ◽  
Chromosome Number ◽  
Y Chromosome ◽  
Stable Equilibrium ◽  
Bone Marrow Cells ◽  
B Chromosome ◽  
B Chromosomes ◽  
Diploid Chromosome Number ◽  
Body Tissues ◽  
Distinct Distribution

Variations in diploid chromosome number, due to the presence of B chromosomes, are found within the distribution of P. v. volans. B chromosomes vary in number between one and eight per animal, are mitotically stable in various body tissues and, unlike the Y chromosome in male P. v. volans, are not eliminated from bone marrow cells. Animals possessing B chromosomes have a distinct distribution, and it appears that a stable equilibrium between the forces of B chromosome accumulation or elimination is operating in those populations possessing these chromosomes.

scholarly journals Distinct DNA methylation patterns associated with active and inactive centromeres of the maize B chromosome

2011 ◽  
Vol 21 (6) ◽  
pp. 908-914 ◽  
Author(s):  
D.-H. Koo ◽  
F. Han ◽  
J. A. Birchler ◽  
J. Jiang
Keyword(s):  
Dna Methylation ◽  
B Chromosome ◽  
Methylation Patterns

scholarly journals Changes in DNA methylation during development in the B chromosome NOR of the grasshopper Eyprepocnemis plorans

Heredity ◽  
1995 ◽  
Vol 74 (3) ◽  
pp. 296-302 ◽  
Author(s):  
M D López-León ◽  
J Cabrero ◽  
J P M Camacho
Keyword(s):  
Dna Methylation ◽  
B Chromosome ◽  
Eyprepocnemis Plorans

scholarly journals B CHROMOSOME NONDISJUNCTION IN CORN: CONTROL BY FACTORS NEAR THE CENTROMERE

Genetics ◽  
1981 ◽  
Vol 97 (2) ◽  
pp. 379-389
Author(s):  
Wayne R Carlson ◽  
Tau-San Chou
Keyword(s):  
B Chromosome ◽  
B Chromosomes ◽  
Translocation Chromosome ◽  
Pollen Mitosis ◽  
Second Pollen Mitosis ◽  
Chromosome Nondisjunction

ABSTRACT B chromosomes of corn are stable at all mitotic and meiotic divisions of the plant except the second pollen mitosis. In the latter division, B chromosomes undego mitotic nondisjunction at rates as high as 98%. Studies by several workers on B-A translocation chromosomes have provided evidence for the existence of four factors on the B chromosome that control nondisjunction and are separable from the centromere. Two of these factors, referred to here as factors 3 and 4, flank the B chromosome centromere. Factor 3 is the centromere-adjacent heterochromatin in the long arm of the B chromosome; factor 4 is located in the minute short arm. Evidence is presented here supporting the existence of factors 3 and 4. Deficiencies that include each factor were identified following centromeric misdivision events, with breaks at or near the centromere of a B-translocation chromosome. B chromosomes lacking factors 3 or 4 show much less nondisjunction than do chromosomes containing them. The possible function of factor 4 in nondisjuntion is also discussed.

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