A Theory of Crossing-Over by Means of Hybrid Deoxyribonucleic Acid

Whitehouse, H. L. K.

doi:10.1038/1991034a0

Cited by 230 publications

(54 citation statements)

References 21 publications

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“…Current models of exchange postulate that homology is required to synapse two homologous sequences by the formation of heteroduplex DNA in which a double helix is formed from complementary strands of the participating homologs (7,17,27,30). Examination of exchange between sequences of limited homology should define the absolute length of DNA needed to effect gene conversion and to find whether homology must exist on both sides of a marker for it to be included in the conversion event. Previously (1,4) we have constructed plasmids which undergo intramolecular gene conversion and crossing over in S. cerevisiae between heteroallelic copies of the HIS3 gene * Corresponding author.…”

mentioning

confidence: 99%

Effect of limited homology on gene conversion in a Saccharomyces cerevisiae plasmid recombination system.

Ahn¹,

Dornfeld²,

Fagrelius³

et al. 1988

Mol. Cell. Biol.

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Plasmids containing heteroallelic copies of the Saccharomyces cerevisiae HIS3 gene undergo intramolecular gene conversion in mitotically dividing S. cerevisiae cells. We have used this plasmid system to determine the minimum amount of homology required for gene conversion, to examine how conversion tract lengths are affected by limited homology, and to analyze the role of flanking DNA sequences on the pattern of exchange. Plasmids with homologous sequences greater than 2 kilobases have mitotic exchange rates as high as 2 x 10-events per cell per generation. As the homology is reduced, the exchange rate decreases dramatically. A plasmid with 26 base pairs (bp) of homology undergoes gene conversion at a rate of approximately 1 x 10-10 events per cell per generation. These studies have also shown that an 8-bp insertion mutation 13 bp from a border between homologous and nonhomologous sequences undergoes conversion, but that a similar 8-bp insertion 5 bp from a border does not. Examination of independent conversion events which occurred in plasmids with heteroallelic copies of the HIS3 gene shows that markers within 280 bp of a border between homologous and nonhomologous sequences undergo conversion less frequently than the same markers within a more extensive homologous sequence. Thus, proximity to a border between homologous and nonhomologous sequences shortens the conversion tract length.Numerous examples of genetic exchange between repeated sequences along individual chromosomes or between such elements present on different chromosomes have been observed in eucaryotic organisms. Many of the observed exchanges have been gene conversions in which a sequence of the donor replaces the homologous sequence of the recipient without concomitant change in the donor (12). In Saccharomyces cerevisiae, for which detailed studies have been possible, some of the events include crossing over concomitant with the conversion event (8,9,14), whereas others are mostly limited to conversion alone (5, 6,11,24). These exchanges are effected by the homology which exists between the repeated sequences. Although studies of homology requirements for exchange have been made with Escherichia coli (21,23,29) and mammalian cells (3,15,20), no systematic study has been made with S. cerevisiae to determine the requirements for homology in effecting exchange, particularly conversion, between elements of limited homology.Because exchange of this nature is thought to mimic the normal chromosomal exchange which occurs between DNA molecules of lengthy homology, exchange between elements of limited homology offers an opportunity to examine fundamental questions which relate to the basic mechanism of exchange. Current models of exchange postulate that homology is required to synapse two homologous sequences by the formation of heteroduplex DNA in which a double helix is formed from complementary strands of the participating homologs (7,17,27,30). Examination of exchange between sequences of limited homology should define the absolute length of DNA ne...

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mentioning

confidence: 99%

Effect of limited homology on gene conversion in a Saccharomyces cerevisiae plasmid recombination system.

Ahn¹,

Dornfeld²,

Fagrelius³

et al. 1988

Mol. Cell. Biol.

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“…DNA synthesis during the meiotic prophase has been suggested to be a vital part of the repair mechanism that takes place after the exchange of chromosomal material during crossing over (Hotta et al 1966, Whitehouse 1963. As far as can be deter mined no reliable evidence of this phenomenon between human somatic chromosomes has been published thus far.…”

Section: Resultsmentioning

confidence: 92%

DNA Synthesis During Mitotic Prophase in Cultured Human Leukocytes

Mukherjee

Gardner

1971

CYTOLOGIA

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“…The ascus type "aberrant 4:4 segregation" is shown here as resulted by a combination of the mode "no correction" of DNA bases in both of the chromatids (chromatids 2 and 3) involved in the heteroduplex DNA formation. This figure itself is a modified version of the one appeared in Kitani and Olive (1967), but originally based on Whitehouse (1963Whitehouse ( , 1964 and Emerson (1965).…”

Section: Origin Of Aberrant 4:4 and Five Other Fundamental Ascusmentioning

confidence: 99%

Aberrant 4:4 Segregation

Kitani

1978

The Japanese journal of genetics

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A Theory of Crossing-Over by Means of Hybrid Deoxyribonucleic Acid

Cited by 230 publications

References 21 publications

Effect of limited homology on gene conversion in a Saccharomyces cerevisiae plasmid recombination system.

Effect of limited homology on gene conversion in a Saccharomyces cerevisiae plasmid recombination system.

DNA Synthesis During Mitotic Prophase in Cultured Human Leukocytes

Aberrant 4:4 Segregation

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