Decision letter: Large domains of heterochromatin direct the formation of short mitotic chromosome loops

Abstract The presence of the tRNA ochre suppressors SUP11 and SUP5 is found to induce meiosis I nondisjunction in the yeast Saccharomyces cerevisiae. The induction increases with increasing dosage of the suppressor and decreases in the presence of an antisuppressor. The effect is independent of the chromosomal location of SUP11. Each of five different chromosomes monitored exhibited nondisjunction at frequencies of 0.1%-1.1% of random spores, which is a 16-160-fold increase over wild-type levels. Increased nondisjunction is reflected by a marked increase in tetrads with two and zero viable spores. In the case of chromosome III, for which a 50-cM map interval was monitored, the resulting disomes are all in the parental nonrecombinant configuration. Recombination along chromosome III appears normal both in meioses that have no nondisjunction and in meioses for which there was nondisjunction of another chromosome. We propose that a proportion of one or more proteins involved in chromosome pairing, recombination or segregation are aberrant due to translational read-through of the normal ochre stop codon. Hygromycin B, an antibiotic that can suppress nonsense mutations via translational read-through, also induces nonrecombinant meiosis I nondisjunction. Increases in mistranslation, therefore, increase the production of aneuploids during meiosis. There was no observable effect of SUP11 on mitotic chromosome nondisjunction; however some disomes caused SUP11 ade2-ochre strains to appear white or red, instead of pink.

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Correction to: Contribution of advanced fluorescence nano microscopy towards revealing mitotic chromosome structure

Chromosome Research ◽

10.1007/s10577-021-09662-5 ◽

2021 ◽

Author(s):

S. W. Botchway ◽

S. Farooq ◽

A. Sajid ◽

I. K. Robinson ◽

M. Yusuf

Keyword(s):

Mitotic Chromosome ◽

Chromosome Structure

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Identification of Chromosome Inheritance Modifiers in Drosophila melanogaster

Genetics ◽

10.1093/genetics/157.4.1623 ◽

2001 ◽

Vol 157 (4) ◽

pp. 1623-1637 ◽

Cited By ~ 7

Author(s):

Kenneth W Dobie ◽

Cameron D Kennedy ◽

Vivienne M Velasco ◽

Tory L McGrath ◽

Juliani Weko ◽

...

Keyword(s):

Drosophila Melanogaster ◽

Biological Activity ◽

Cancer Progression ◽

Birth Defects ◽

Mitotic Chromosome ◽

P Element ◽

Inverse Pcr ◽

Gtpase Activating Protein ◽

New Genes ◽

Genomic Analyses

Abstract Faithful chromosome inheritance is a fundamental biological activity and errors contribute to birth defects and cancer progression. We have performed a P-element screen in Drosophila melanogaster with the aim of identifying novel candidate genes involved in inheritance. We used a “sensitized” minichromosome substrate (J21A) to screen ∼3,000 new P-element lines for dominant effects on chromosome inheritance and recovered 78 Sensitized chromosome inheritance modifiers (Scim). Of these, 69 decreased minichromosome inheritance while 9 increased minichromosome inheritance. Fourteen mutations are lethal or semilethal when homozygous and all exhibit dramatic mitotic defects. Inverse PCR combined with genomic analyses identified P insertions within or close to genes with previously described inheritance functions, including wings apart-like (wapl), centrosomin (cnn), and pavarotti (pav). Further, lethal insertions in replication factor complex 4 (rfc4) and GTPase-activating protein 1 (Gap1) exhibit specific mitotic chromosome defects, discovering previously unknown roles for these proteins in chromosome inheritance. The majority of the lines represent mutations in previously uncharacterized loci, many of which have human homologs, and we anticipate that this collection will provide a rich source of mutations in new genes required for chromosome inheritance in metazoans.

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ALTERED FIDELITY OF MITOTIC CHROMOSOME TRANSMISSION IN CELL CYCLE MUTANTS OF S. CEREVISIAE

Genetics ◽

10.1093/genetics/110.3.381 ◽

1985 ◽

Vol 110 (3) ◽

pp. 381-395

Author(s):

Leland H Hartwell ◽

David Smith

Keyword(s):

Cell Cycle ◽

Gene Product ◽

Mitotic Chromosome ◽

Mitotic Recombination ◽

Chromosome Loss ◽

Temperature Sensitive ◽

Repair Pathway ◽

Dna Metabolism ◽

Temperature Sensitive Mutants ◽

Chromosome Transmission

ABSTRACT Thirteen of 14 temperature-sensitive mutants deficient in successive steps of mitotic chromosome transmission (cdc2, 4, 5, 6, 7, 8, 9, 13, 14, 15, 16, 17 and 20) from spindle pole body separation to a late stage of nuclear division exhibited a dramatic increase in the frequency of chromosome loss and/or mitotic recombination when they were grown at their maximum permissive temperatures. The increase in chromosome loss and/or recombination is likely to be due to the deficiency of functional gene product rather than to an aberrant function of the mutant gene product since the mutant alleles are, with one exception, recessive to the wild-type allele for this phenotype. The generality of this result suggests that a delay in almost any stage of chromosome replication or segregation leads to a decrease in the fidelity of mitotic chromosome transmission. In contrast, temperature-sensitive mutants defective in the control step of the cell cycle (cdc28), in cytokinesis (cdc3) or in protein synthesis (ils1) did not exhibit increased recombination or chromosome loss.—Based upon previous results with mutants and DNA-damaging agents in a variety of organisms, we suggest that the induction of mitotic recombination in certain mutants is due to the action of a repair pathway upon nicks or gaps left in the DNA. This interpretation is supported by the fact that the induced recombination is dependent upon the RAD52 gene product, an essential component in the recombinogenic DNA repair pathway. Gene products whose deficiency leads to induced recombination are, therefore, strong candidates for proteins that function in DNA metabolism. Among the mutants that induce recombination are those known to be defective in some aspect of DNA replication (cdc2, 6, 8, 9) as well as some mutants defective in the G2 (cdc13 and 17) and M (cdc5 and 14) phases of the mitotic cycle. We suggest that special aspects of DNA metabolism may be occurring in G2 and M in order to prepare the chromosomes for proper segregation.

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