Skip to main content
PMC home page
Genetics logoLink to Genetics
. 1995 Jan;139(1):137–145. doi: 10.1093/genetics/139.1.137

Spontaneous Mutation during the Sexual Cycle of Neurospora Crassa

M K Watters 1, D R Stadler 1
PMCID: PMC1206313  PMID: 7705619

Abstract

The DNA sequences of 42 spontaneous mutations of the mtr gene in Neurospora crassa have been determined. The mutants were selected among sexual spores to represent mutations arising in the sexual cycle. Three sexual-cycle-specific mutational classes are described: hotspot mutants, spontaneous repeat-induced point mutation (RIPs) and mutations occurring during a mutagenic phase of the sexual cycle. Together, these three sexual-cycle-specific mutational classes account for 50% of the mutations in the sexual-cycle mutational spectrum. One third of all mutations occurred at one of two mutational hotspots that predominantly produced tandem duplications of varying lengths with short repeats at their end-points. Neither of the two hotspots are present in the vegetative spectrum, suggesting that sexual-cycle-specific mutational pathways are responsible for their presence in the spectrum. One mutant was observed that appeared to have been RIPed precociously. The usual prerequisite for RIP, a duplication of the affected region, was not present in the parent stocks and was not detected in this mutant. Finally, there is a phase early in the premeiotic sexual cycle that is overrepresented in the generation of mutations. This ``peak'' appears to represent a phase during which the mutation rate rises significantly. This phase produces a disproportionally high fraction of frame shift mutations (3/6). In divisions subsequent to this, the mutation rate appears to be constant.

Full Text

The Full Text of this article is available as a PDF (914.7 KB).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. BAUSUM H. T., WAGNER R. P. "SELFING" AND OTHER FORMS OF ABERRANT RECOMBINATION IN ISOLEUCINE-VALINE MUTANTS OF NEUROSPORA. Genetics. 1965 May;51:815–830. doi: 10.1093/genetics/51.5.815. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Butler D. K., Metzenberg R. L. Premeiotic change of nucleolus organizer size in Neurospora. Genetics. 1989 Aug;122(4):783–791. doi: 10.1093/genetics/122.4.783. [DOI] [PMC free article] [PubMed] [Google Scholar]
  3. Cambareri E. B., Jensen B. C., Schabtach E., Selker E. U. Repeat-induced G-C to A-T mutations in Neurospora. Science. 1989 Jun 30;244(4912):1571–1575. doi: 10.1126/science.2544994. [DOI] [PubMed] [Google Scholar]
  4. Demerec M. "SELFERS"-ATTRIBUTED TO UNEQUAL CROSSOVERS IN SALMONELLA. Proc Natl Acad Sci U S A. 1962 Oct;48(10):1696–1704. doi: 10.1073/pnas.48.10.1696. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Dillon D., Stadler D. Spontaneous mutation at the mtr locus in neurospora: the molecular spectrum in wild-type and a mutator strain. Genetics. 1994 Sep;138(1):61–74. doi: 10.1093/genetics/138.1.61. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Friis J., Flury F., Leupold U. Characterization of spontaneous mutations of mitotic and meiotic origin in the ad-I locus of Schizosaccharomyces pombe. Mutat Res. 1971 Apr;11(4):373–390. [PubMed] [Google Scholar]
  7. Kinsey J. A., Fincham J. R., Siddig M. A., Keighren M. New mutational variants of Neurospora NADP-specific glutamate dehydrogenase. Genetics. 1980 Jun;95(2):305–316. doi: 10.1093/genetics/95.2.305. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Kohler S. W., Provost G. S., Fieck A., Kretz P. L., Bullock W. O., Sorge J. A., Putman D. L., Short J. M. Spectra of spontaneous and mutagen-induced mutations in the lacI gene in transgenic mice. Proc Natl Acad Sci U S A. 1991 Sep 15;88(18):7958–7962. doi: 10.1073/pnas.88.18.7958. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Koltin V., Stamberg J., Ronen R. Melosis as a source of spontaneous mutations in Schizophyllum commune. Mutat Res. 1975 Mar;27(3):319–325. doi: 10.1016/0027-5107(75)90288-2. [DOI] [PubMed] [Google Scholar]
  10. MAGNI G. E. ORIGIN AND NATURE OF SPONTANEOUS MUTATIONS IN MEIOTIC ORGANISMS. J Cell Physiol. 1964 Oct;64:SUPPL 1–1:171. [PubMed] [Google Scholar]
  11. MAGNI G. E. THE ORIGIN OF SPONTANEOUS MUTATIONS DURING MEIOSIS. Proc Natl Acad Sci U S A. 1963 Nov;50:975–980. doi: 10.1073/pnas.50.5.975. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. PASZEWSKI A., SURZYCKI S. 'SELFERS' AND HIGH MUTATION RATE DURING MEIOSIS IN ASCOBOLUS IMMERSUS. Nature. 1964 Nov 21;204:809–809. doi: 10.1038/204809a0. [DOI] [PubMed] [Google Scholar]
  13. Rambosek J. A., Kinsey J. A. Fine Structure Mapping of the am (Gdh) Locus of Neurospora. Genetics. 1983 Oct;105(2):293–307. doi: 10.1093/genetics/105.2.293. [DOI] [PMC free article] [PubMed] [Google Scholar]
  14. Rhounim L., Rossignol J. L., Faugeron G. Epimutation of repeated genes in Ascobolus immersus. EMBO J. 1992 Dec;11(12):4451–4457. doi: 10.1002/j.1460-2075.1992.tb05546.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Schaaper R. M., Danforth B. N., Glickman B. W. Mechanisms of spontaneous mutagenesis: an analysis of the spectrum of spontaneous mutation in the Escherichia coli lacI gene. J Mol Biol. 1986 May 20;189(2):273–284. doi: 10.1016/0022-2836(86)90509-7. [DOI] [PubMed] [Google Scholar]
  17. Selker E. U., Cambareri E. B., Jensen B. C., Haack K. R. Rearrangement of duplicated DNA in specialized cells of Neurospora. Cell. 1987 Dec 4;51(5):741–752. doi: 10.1016/0092-8674(87)90097-3. [DOI] [PubMed] [Google Scholar]
  18. Selker E. U. Premeiotic instability of repeated sequences in Neurospora crassa. Annu Rev Genet. 1990;24:579–613. doi: 10.1146/annurev.ge.24.120190.003051. [DOI] [PubMed] [Google Scholar]
  19. Streisinger G., Okada Y., Emrich J., Newton J., Tsugita A., Terzaghi E., Inouye M. Frameshift mutations and the genetic code. This paper is dedicated to Professor Theodosius Dobzhansky on the occasion of his 66th birthday. Cold Spring Harb Symp Quant Biol. 1966;31:77–84. doi: 10.1101/sqb.1966.031.01.014. [DOI] [PubMed] [Google Scholar]
  20. Whelan W. L., Gocke E., Manney T. R. The CAN1 locus of Saccharomyces cerevisiae: fine-structure analysis and forward mutation rates. Genetics. 1979 Jan;91(1):35–51. doi: 10.1093/genetics/91.1.35. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Zolan M. E., Pukkila P. J. Inheritance of DNA methylation in Coprinus cinereus. Mol Cell Biol. 1986 Jan;6(1):195–200. doi: 10.1128/mcb.6.1.195. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Genetics are provided here courtesy of Oxford University Press

RESOURCES