Chromosome segregation from cell hybrids. IV. Movement and position of segregant set chromosomes in early-phase interspecific cell hybrids

1988 ◽  
Vol 89 (1) ◽  
pp. 49-56
Author(s):  
P.A. Zelesco ◽  
J.A. Graves
Keyword(s):  
Chromosome Segregation ◽  
Early Phase ◽  
Metaphase Plate ◽  
Central Position ◽  
Chromosome Loss ◽  
Human Chromosomes ◽  
Hybrid Cells ◽  
Multipolar Mitosis ◽  
Cell Hybrids ◽  
G 11

We searched for evidence of aberrant movement or position of segregant set chromosomes in C-banded and G-11-banded early-phase hamster-mouse and hamster-human cell hybrids that had been prepared with minimal disruption. No evidence was obtained for an increased frequency of multipolar mitosis, delayed or precocious metaphase congression or anaphase segregation, or for exclusion of chromosomes from the daughter nuclei. However, in hamster-human hybrids, segregant set (human) chromosomes were observed to assume a central position within a ring of hamster chromosomes on the metaphase plate. Such non-random positioning may imply that the centromeres of segregant chromosomes make aberrant, or simply less efficient, attachments to the spindle in hybrid cells. This aberrant position may perhaps result indirectly in chromosome loss by interfering with the normal processes of replication, repair or transcription.

Chromosome segregation from cell hybrids. VII. Reverse segregation from karyoplast hybrids suggests control by cytoplasmic factors

Genome ◽  
1992 ◽  
Vol 35 (3) ◽  
pp. 537-540 ◽  
Author(s):  
Jennifer A. Marshall Graves ◽  
Iole Barbieri
Keyword(s):  
Chromosome Segregation ◽  
Human Cell ◽  
Chinese Hamster ◽  
Segregation Pattern ◽  
Chromosome Loss ◽  
Human Chromosomes ◽  
Cell Hybrids ◽  
Cytoplasmic Factors

Using human and Chinese hamster established lines as cell parents, we constructed hamster–human cell hybrids and human cell – hamster karyoplast hybrids. The cell hybrids retained one or two sets of hamster chromosomes and lost most of the human chromosomes. The karyoplast hybrids, however, retained a full set of human chromosomes and lost most of the Chinese hamster chromosomes. This reverse segregation pattern implies that cytoplasmic factors are major determinants of the direction of chromosome segregation.Key words: cell hybrids, chromosome loss, cytoplasmic factors, reverse segregation.

Chromosome segregation from cell hybrids. V. Does segregation result from asynchronous centromere separation?

Genome ◽  
1988 ◽  
Vol 30 (2) ◽  
pp. 124-128 ◽  
Author(s):  
Jennifer A. Marshall Graves ◽  
Paula A. Zelesco
Keyword(s):  
Cell Lines ◽  
Chromosome Segregation ◽  
Hybrid Cell ◽  
Human Chromosomes ◽  
Specific Difference ◽  
Cell Hybrids ◽  
G 11 ◽  
Species Specific ◽  
Separation Cell ◽  
Hybrid Cell Lines

Hamster–mouse and hamster–human hybrid cell lines were used to test the hypothesis that a species-specific difference in the timing of centromere separation is the basis for preferential chromosome segregation from interspecific cell hybrids. Colcemid-treated preparations were C-banded to differentiate hamster and mouse chromosomes or G-11 banded to differentiate hamster and human chromosomes. Metaphase spreads showing at least some centromere separation were photographed and the extent of separation, and the species of origin, was determined for each chromosome. There was no evidence that centromere separation of segregant chromosomes was consistently premature or delayed.Key words: chromosome segregation, centromere separation, cell hybrids.

Chromosome segregation from cell hybrids.II. Do differences in parental cell growth rates and phase times determine direction of loss?

1986 ◽  
Vol 28 (5) ◽  
pp. 735-743 ◽  
Author(s):  
Jennifer A. Marshall Graves ◽  
Jaclyn M. Wrigley
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Chinese Hamster ◽  
Parental Cell ◽  
S Phase ◽  
Chromosome Loss ◽  
Parent Cell ◽  
Cycle Times ◽  
Cell Hybrids ◽  
The One

The hypothesis that the direction of chromosome segregation in cell hybrids is determined by the interaction of parent cell cycles, or S-phase times, predicts that the segregant parent will always be the one with the longer cycle, or the longer S phase, and that late replicating chromosomes will be more frequently lost. We have tested this hypothesis by studying cell cycle parameters of mouse, Chinese hamster, and platypus parent cells and by observing chromosome loss and replication patterns in hybrids between them. Two types of hybrids have been studied: mouse–hamster hybrids showed gradual segregation, in one or other direction, of 10–60% chromosomes, while rodent–platypus hybrids (which could be selected under conditions optimal for either parent cell) showed rapid and extreme segregation of platypus chromosomes. We found no correlation between the direction of segregation and the relative lengths of parental cycle times, or phase times, nor between sequence of replication and frequency with which segregant chromosomes are lost. We therefore conclude that the direction and extent of segregation is not directly determined by the interaction of parental cycle or phase times.Key words: cell hybrids, chromosome loss, cell cycle, S phase.

Chromosome segregation from cell hybrids. I. The effect of parent cell ploidy on segregation from mouse – Chinese hamster hybrids

1984 ◽  
Vol 26 (5) ◽  
pp. 557-563 ◽  
Author(s):  
Jennifer A. Marshall Graves
Keyword(s):  
Chromosome Number ◽  
Chromosome Segregation ◽  
Chinese Hamster ◽  
Chromosome Loss ◽  
Parent Cell ◽  
Cell Hybrids ◽  
Parental Factor ◽  
Species Combination ◽  
Mouse Cells ◽  
Input Ratio

To determine whether the dosage of some parental factor influences the direction and extent of chromosome segregation, I have constructed hybrids between polyploid series of mouse and Chinese hamster lines. The input ratio of mouse: hamster chromosomes varied from 3.3 (in hybrids between diploid hamster and polyploid mouse cells) and 0.9 (in hybrids between polyploid hamster and near-diploid mouse cells). Mouse chromosomes were retained and hamster chromosomes were lost from all hybrids with input ratios ≥ 1.3; the extent of hamster chromosome loss increased from 25 to 60% as the proportion of mouse chromosomes was increased. Reverse segregation was observed in hybrids in which the ratio was 0.9; hybrids between polyploid hamster and diploid mouse cells retained most hamster chromosomes and lost 52% of mouse chromosomes. I conclude that the direction and extent of chromosome segregation from these hybrids depends on the dosage of some factor contained in the parent cells; because the volumes of polyploid cells are proportional to chromosome number, this factor could be chromosomal, nuclear, or cytoplasmic. Dosage differences should therefore be considered when comparing chromosome segregation from hybrids with cells of the same species combination, but which might differ in chromosome number (e.g., diploid lines and established lines), or cell volume (e.g., cells from different tissues).Key words: cell hybrids, mouse – hamster, segregation, chromosome loss, ploidy.

Extent and rate of chromosome segregation in two intraspecific mouse cell hybrids: A9 × diploid foetal erythrocyte and A9 × B82

1979 ◽  
Vol 36 (1) ◽  
pp. 215-221
Author(s):  
M.H. Russell ◽  
B.J. McGee ◽  
E. Engel
Keyword(s):  
Chromosome Segregation ◽  
Wild Type Mouse ◽  
Mouse Cell ◽  
Chromosome Loss ◽  
Wild Type ◽  
Banding Patterns ◽  
Chromosomal Segregation ◽  
Cell Hybrids ◽  
Telocentric Chromosomes ◽  
Hybrid Lines

Patterns of chromosome segregation were studied in 2 different intraspecific mouse cell hybrids: (1) A9 × B82, formed by fusing 2 cell lines of heteroploid fibroblasts, and (2) UWE, originating from the fusion of A9 cells with euploid foetal erythrocytes. Detailed analyses of Giemsa (G)-banded chromosomes and chromosome arms of both parental and hybrid cells were made for each hybrid type, in order to determine the specificity of the losses and to assess the influence of ploidy and cell differentiation. Unlike the A9 × B82 hybrids, which revealed a significant chromosome loss under selective tissue culture pressures only after 9 months, the UWE hybrids showed a sharp reduction in the total chromosome number during the initial 2 months under similar pressures. However, with no additional cloning, UWE remained karyotypically stable after that time. This rapid chromosomal segregation in UWE hybrids may be caused by properties of the parental foetal erythrocytes. In UWE cells, the majority of the chromosome arms were retained or duplicated. Less than a quarter of the total number of chromosome arms were segregated or lost, and these were all chromosome arms with abnormal mouse G-banding patterns, present only in the heteroploid A9 parental cells. In two of the four A9 × B82 hybrid lines, there was marked segregation of chromosome arms whose banding patterns were identical to those of wild type mouse telocentric chromosomes. For both types of intraspecific cell hybrids, two thirds or more of the chromosome arms had banding patterns which were the same as those of the wild type genome.

scholarly journals The Role of Cdh1p in Maintaining Genomic Stability in Budding Yeast

Genetics ◽  
2003 ◽  
Vol 165 (2) ◽  
pp. 489-503 ◽  
Author(s):  
Karen E Ross ◽  
Orna Cohen-Fix
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Spindle Assembly Checkpoint ◽  
Chromosome Loss ◽  
Cyclin Dependent Kinase ◽  
Anaphase Promoting Complex ◽  
Growth Defects ◽  
Genes Encoding ◽  
Specificity Factor

Abstract Cdh1p, a substrate specificity factor for the cell cycle-regulated ubiquitin ligase, the anaphase-promoting complex/cyclosome (APC/C), promotes exit from mitosis by directing the degradation of a number of proteins, including the mitotic cyclins. Here we present evidence that Cdh1p activity at the M/G1 transition is important not only for mitotic exit but also for high-fidelity chromosome segregation in the subsequent cell cycle. CDH1 showed genetic interactions with MAD2 and PDS1, genes encoding components of the mitotic spindle assembly checkpoint that acts at metaphase to prevent premature chromosome segregation. Unlike cdh1Δ and mad2Δ single mutants, the mad2Δ cdh1Δ double mutant grew slowly and exhibited high rates of chromosome and plasmid loss. Simultaneous deletion of PDS1 and CDH1 caused extensive chromosome missegregation and cell death. Our data suggest that at least part of the chromosome loss can be attributed to kinetochore/spindle problems. Our data further suggest that Cdh1p and Sic1p, a Cdc28p/Clb inhibitor, have overlapping as well as nonoverlapping roles in ensuring proper chromosome segregation. The severe growth defects of both mad2Δ cdh1Δ and pds1Δ cdh1Δ strains were rescued by overexpressing Swe1p, a G2/M inhibitor of the cyclin-dependent kinase, Cdc28p/Clb. We propose that the failure to degrade cyclins at the end of mitosis leaves cdh1Δ mutant strains with abnormal Cdc28p/Clb activity that interferes with proper chromosome segregation.

scholarly journals Identification of a novel nucleolar protein complex required for mitotic chromosome segregation through centromeric accumulation of Aurora B

2020 ◽  
Vol 48 (12) ◽  
pp. 6583-6596
Author(s):  
Akiko Fujimura ◽  
Yuki Hayashi ◽  
Kazashi Kato ◽  
Yuichiro Kogure ◽  
Mutsuro Kameyama ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Protein Complex ◽  
Metaphase Plate ◽  
Nucleolar Protein ◽  
Aurora B ◽  
Mitotic Progression ◽  
Mitotic Chromosomes ◽  
Nucleolar Proteins ◽  
Chromatid Cohesion ◽  
Wd Repeat

Abstract The nucleolus is a membrane-less nuclear structure that disassembles when cells undergo mitosis. During mitosis, nucleolar factors are thus released from the nucleolus and dynamically change their subcellular localization; however, their functions remain largely uncharacterised. Here, we found that a nucleolar factor called nucleolar protein 11 (NOL11) forms a protein complex with two tryptophan-aspartic acid (WD) repeat proteins named WD-repeat protein 43 (WDR43) and Cirhin in mitotic cells. This complex, referred to here as the NWC (NOL11-WDR43-Cirhin) complex, exists in nucleoli during interphase and translocates to the periphery of mitotic chromosomes, i.e., perichromosomal regions. During mitotic progression, both the congression of chromosomes to the metaphase plate and sister chromatid cohesion are impaired in the absence of the NWC complex, as it is required for the centromeric enrichment of Aurora B and the associating phosphorylation of histone H3 at threonine 3. These results reveal the characteristics of a novel protein complex consisting of nucleolar proteins, which is required for regulating kinetochores and centromeres to ensure faithful chromosome segregation.

Activation and repression of a beta-globin gene in cell hybrids is accompanied by a shift in its temporal replication

1989 ◽  
Vol 9 (8) ◽  
pp. 3524-3532
Author(s):  
V Dhar ◽  
A I Skoultchi ◽  
C L Schildkraut
Keyword(s):  
Cell Line ◽  
Hybrid Cell ◽  
Globin Gene ◽  
Fibroblast Cell ◽  
Globin Genes ◽  
Fibroblast Cell Line ◽  
Beta Globin ◽  
Hybrid Cells ◽  
Beta Globin Gene ◽  
Cell Hybrids

To investigate whether a switch in the transcriptional activity of a gene is associated with a change in the timing of replication during the S phase, we examined the replication timing of the beta-globin genes in two different types of somatic cell hybrids. In mouse hepatoma (Hepa 1a) x mouse erythroleukemia (MEL) hybrid cells, the beta-globin gene from the MEL parent is transcriptionally inactivated and is later replicating than in the parental MEL cell line. In human fibroblast (GM3552) x MEL hybrid cells, the human beta-globin gene is transcriptionally activated, and all of the sequences within the human beta-globin domain (200 kilobases) we have examined appear to be earlier replicating than those in the parental fibroblast cell line. The chromatin configuration of the activated human beta-globin domain in the hybrids is relatively more sensitive to nucleases than that in the fibroblasts. Furthermore, major nuclease-hypersensitive sites that were absent in the chromatin flanking the distal 5' region of the human beta-globin gene cluster in the parental fibroblast cell line are present in the transcriptionally activated domain in the hybrid cell line. These results suggest that timing of replication of globin genes has been altered in these hybrid cells and thus is not fixed during the process of differentiation.

DBF8, an essential gene required for efficient chromosome segregation in Saccharomyces cerevisiae

1994 ◽  
Vol 14 (9) ◽  
pp. 6350-6360
Author(s):  
F Houman ◽  
C Holm
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Mutational Analysis ◽  
Essential Gene ◽  
Chromosome Loss ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Permissive Temperature ◽  
Nonsense Mutations ◽  
Carboxy Terminal

To investigate chromosome segregation in Saccharomyces cerevisiae, we examined a collection of temperature-sensitive mutants that arrest as large-budded cells at restrictive temperatures (L. H. Johnston and A. P. Thomas, Mol. Gen. Genet. 186:439-444, 1982). We characterized dbf8, a mutation that causes cells to arrest with a 2c DNA content and a short spindle. DBF8 maps to chromosome IX near the centromere, and it encodes a 36-kDa protein that is essential for viability at all temperatures. Mutational analysis reveals that three dbf8 alleles are nonsense mutations affecting the carboxy-terminal third of the encoded protein. Since all of these mutations confer temperature sensitivity, it appears that the carboxyl-terminal third of the protein is essential only at a restrictive temperature. In support of this conclusion, an insertion of URA3 at the same position also confers a temperature-sensitive phenotype. Although they show no evidence of DNA damage, dbf8 mutants exhibit increased rates of chromosome loss and nondisjunction even at a permissive temperature. Taken together, our data suggest that Dbf8p plays an essential role in chromosome segregation.

In vivo analysis of the Saccharomyces cerevisiae centromere CDEIII sequence: requirements for mitotic chromosome segregation

1991 ◽  
Vol 11 (10) ◽  
pp. 5212-5221
Author(s):  
B Jehn ◽  
R Niedenthal ◽  
J H Hegemann
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Segregation ◽  
Artificial Chromosome ◽  
Complete Information ◽  
Saturation Mutagenesis ◽  
Chromosome Loss ◽  
Single Mutation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Double Base

In the yeast Saccharomyces cerevisiae, the complete information needed in cis to specify a fully functional mitotic and meiotic centromere is contained within 120 bp arranged in the three conserved centromeric (CEN) DNA elements CDEI, -II, and -III. The 25-bp CDEIII is most important for faithful chromosome segregation. We have constructed single- and double-base substitutions in all highly conserved residues and one nonconserved residue of this element and analyzed the mitotic in vivo function of the mutated CEN DNAs, using an artificial chromosome. The effects of the mutations on chromosome segregation vary between wild-type-like activity (chromosome loss rate of 4.8 x 10(-4)) and a complete loss of CEN function. Data obtained by saturation mutagenesis of the palindromic core sequence suggest asymmetric involvement of the palindromic half-sites in mitotic CEN function. The poor CEN activity of certain single mutations could be improved by introducing an additional single mutation. These second-site suppressors can be found at conserved and nonconserved positions in CDEIII. Our suppression data are discussed in the context of natural CDEIII sequence variations found in the CEN sequences of different yeast chromosomes.

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