Related Experiment Video

Updated: Aug 10, 2026

Examination of Mitotic and Meiotic Fission Yeast Nuclear Dynamics by Fluorescence Live-cell Microscopy
12:04

Examination of Mitotic and Meiotic Fission Yeast Nuclear Dynamics by Fluorescence Live-cell Microscopy

Published on: June 24, 2019

Recombination and hydroxyurea inhibition of DNA synthesis in yeast meiosis

G Simchen, D Idar, Y Kassir

    Molecular & General Genetics : MGG
    |February 27, 1976
    PubMed

    Insights

    Hydroxyurea (HU) treatment during yeast premeiotic DNA replication delays meiosis and increases intragenic recombination. However, HU is toxic to cells treated late in meiosis.

    Area of Science:

    • Molecular Biology
    • Genetics
    • Cell Biology

    Background:

    • Meiosis is a fundamental process for sexual reproduction, involving DNA replication and recombination.
    • Hydroxyurea (HU) is a known inhibitor of DNA replication.

    Purpose of the Study:

    • To investigate the effects of short hydroxyurea (HU) treatments on meiotic DNA replication and recombination in yeast.
    • To determine the optimal timing for HU treatment to modulate meiotic events without causing toxicity.

    Main Methods:

    • Yeast cells were treated with hydroxyurea (HU) at different time points during the premeiotic S phase.
    • DNA replication rates, meiotic progression, and intragenic recombination frequencies were analyzed after HU removal.
    • Sensitivity of meiotic cells to HU at different stages was assessed.

    Main Results:

    • Short HU treatments during premeiotic replication delayed meiotic progression but allowed normal replication resumption upon drug removal.
    • Intragenic recombination frequencies increased significantly in some ade2 heteroalleles following HU treatment.
    • HU treatments late in meiosis (7-7.5 hrs) were toxic, causing cell death and DNA degradation.
    • No enhanced recombination was observed for high-recombination heteroalleles or in lys2 mutants.

    Conclusions:

    • Hydroxyurea (HU) can be used to transiently inhibit premeiotic DNA replication, leading to delayed meiosis and enhanced intragenic recombination.
    • The timing of HU treatment is critical, as late-stage treatments are detrimental to cell viability.
    • The observed recombination enhancement is allele-specific and dependent on the basal recombination rate.

    More Related Videos

    Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae07:55

    Detection of Homologous Recombination Intermediates via Proximity Ligation and Quantitative PCR in Saccharomyces cerevisiae

    Published on: September 11, 2022

    Preparation of Meiotic Chromosome Spreads from Mouse Oocytes for Assessment of Synapsis and Recombination09:24

    Preparation of Meiotic Chromosome Spreads from Mouse Oocytes for Assessment of Synapsis and Recombination

    Published on: July 18, 2025

    Related Concept Videos

    Crossing Over01:34

    Crossing Over

    Unlike mitosis, meiosis aims for genetic diversity in its creation of haploid gametes. Dividing germ cells first begin this process in prophase I, where each chromosome—replicated in S phase—is now composed of two sister chromatids (identical copies) joined centrally.
    The homologous pairs of sister chromosomes—one from the maternal and one from the paternal genome—then begin to align alongside each other lengthwise, matching corresponding DNA positions in a process called synapsis.
    In order to...
    Homologous Recombination02:31

    Homologous Recombination

    The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
    Gene Conversion02:08

    Gene Conversion

    Other than maintaining genome stability via DNA repair, homologous recombination plays an important role in diversifying the genome. In fact, the recombination of sequences forms the molecular basis of genomic evolution. Random and non-random permutations of genomic sequences create a library of new amalgamated sequences. These newly formed genomes can determine the fitness and survival of cells. In bacteria, homologous and non-homologous types of recombination lead to the evolution of new...
    Conservative Site-specific Recombination and Phase Variation02:53

    Conservative Site-specific Recombination and Phase Variation

    Because the DNA segments are cut and reorganized in a direction-specific manner, site-specific recombination has emerged as an efficient genetic engineering technique. Flippase and Cyclization recombinases or Flp and Cre, respectively, are two members of the tyrosine recombinase family derived from bacteriophages, that are used to mediate site-specific DNA insertions, deletions, and targeted expression of proteins in mammalian cell lines.
    The recognition sites for Cre recombinase called LoxP...
    Homologous Recombination02:31

    Homologous Recombination

    The basic reaction of homologous recombination (HR) involves two chromatids that contain DNA sequences sharing a significant stretch of identity. One of these sequences uses a strand from another as a template to synthesize DNA in an enzyme-catalyzed reaction. The final product is a novel amalgamation of the two substrates. To ensure an accurate recombination of sequences, HR is restricted to the S and G2 phases of the cell cycle. At these stages, the DNA has been replicated already and the...
    Crossing Over01:30

    Crossing Over

    Crossing over is the exchange of genetic information between homologous chromosomes during prophase I of meiosis I. Genetic recombination gives rise to allelic diversity in the newly formed daughter cells. In humans, crossing over produces genetically distinct haploid egg and sperm cells that undergo fertilization to produce unique offspring. Before cell division starts, the germ cell’s chromosome(s) undergo duplication in the S phase of the cell cycle. As the cells enter prophase I, duplicated...