Hostname: page-component-848d4c4894-v5vhk Total loading time: 0 Render date: 2024-07-06T06:41:20.815Z Has data issue: false hasContentIssue false
  • English
  • Français

The cytology of Aspergillus nidulans

Published online by Cambridge University Press:  14 April 2009

Charles G. Elliott
Charles G. Elliott
Affiliation:
Genetics Department, University of Glasgow

Extract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In haploid strains of Aspergillus nidulans, asci arise from croziers. The two nuclei of the young ascus (the penultimate cell of the crozier) fuse, and the zygote nucleus immediately undergoes meiosis. At diakinesis and first metaphase eight bivalents are seen: three large (one, Chromosome 2, with a satellite), two medium sized (Chromosomes 4 and 5), two small (Chromosomes 6 and 7) and one very small (Chromosome 8). The perithecia of haploid strains are packed with asci and have very few sterile hyphae.

Diploid strains (heterozygotes made by Roper's technique) are very different from haploids in that the perithecia contain many sterile hyphae with little cytoplasm and coiled hyphae with dense cytoplasm made up mainly of uninucleate cells, and there are few asci in a perithecium. Croziers are absent: some of the cells of the coiled hyphae become asci. At diakinesis and first metaphase, the same chromosome configurations are seen as in a cross between the haploid strains from which the diploid was synthesized; the chromosomes are bivalents. The young ascus thus has a single (diploid) nucleus which undergoes meiosis, and asci develop apogamously. No evidence of nuclear fusion in the young ascus and of a tetraploid meiosis was obtained. Cultures from ascopores isolated by micro-manipulation from perithecia of diploids were all haploid. Meiosis appears to proceed normally to first metaphase, but typical later stages, and asci with spores, are rarely seen. First anaphase frequently fails to occur, and the chromosomes clump together.

In the strain ad2 y, obtained from a normal strain by X-irradiation, nine bivalents are present, one a very small fragment. In crosses between ad2 y and a normal strain, and in a diploid made from them, the fragment pairs with Chromosome 6. Asci in the cross between ad2 y and a normal haploid are highly irregular, often with less than the usual eight spores.

Type
Research Article
Information
Genetics Research , Volume 1 , Issue 3 , November 1960 , pp. 462 - 476
Copyright
Copyright © Cambridge University Press 1960

References

REFERENCES

Carr, A. J. H. & Olive, L. S. (1958). Genetics of Sordaria fimicola. II. Cytology. Amer. J. Bot. 45, 142–150.Google Scholar
Day, P. R., Boone, D. M. & Keitt, G. W. (1956). Venturia inaequalis (Cke.) Wint. XI. The chromosome number. Amer. J. Bot. 43, 835–838.Google Scholar
El-Ani, A. S. (1956). Ascus development and nuclear behaviour in Hypomyces solani f cucurbitae. Amer. J. Bot. 43, 769–778.CrossRefGoogle Scholar
El-Ani, A. S. (1959). Chromosome numbers in the Hypocreales. I. Nuclear division in the ascus of Nectria peziza. Amer. J. Bot. 46, 412–417.Google Scholar
Elliott, C. G. (1956). Chromosomes in micro-organisms. Symp. Soc. gen. Microbiol. 6, 279–295.Google Scholar
Käfer, E. (1957). Genetics of Aspergillus. Yearb. Carneg. Instn, 56, 376–378.Google Scholar
Käfer, E. (1958). An 8-chromosome map of Aspergillus nidulans. Advanc. Genet. 9, 105–145.Google Scholar
McClintock, B. (1945). Neurospora. I. Preliminary observations of the chromosomes of Neurospora crassa. Amer. J. Bot. 32, 671–678.CrossRefGoogle Scholar
Olive, L. S. (1950). A cytological study of ascus development in Patella melaloma (Alb. & Schw.) Seaver. Amer. J. Bot. 37, 757–763.Google Scholar
Olive, L. S. (1954). Cross-karyogamy and segregation in a homothallic fungus. Bull. Torrey bot. Cl. 81, 95–97.CrossRefGoogle Scholar
Pritchard, R. H. (1955). A genetic investigation of some adenine-requiring mutants of Aspergillus nidulans. Ph.D. thesis, University of Glasgow.Google Scholar
Pontecorvo, G. (1953). The genetics of Aspergillus nidulans. Advanc. Genet. 5, 141–238.CrossRefGoogle ScholarPubMed
Ontecorvo, G. (1954). Mitotic recombination in the genetic systems of filamentous fungi. Caryologia, 6 suppl., 192–200.Google Scholar
Pontecorvo, G., Tarr Gloor, E. & Forbes, E. (1954). Analysis of mitotic recombination in Aspergillus nidulans. J. Genet. 52, 226–237.CrossRefGoogle Scholar
Roper, J. A. (1952). Production of heterozygous diploids in filamentous fungi. Experientia, 8, 14.Google Scholar
Singleton, J. R. (1953). Chromosome morphology and the chromosome cycle in the ascus of Neurospora crassa. Amer. J. Bot. 40, 124–144.CrossRefGoogle Scholar
Strickland, W. N. (1956). Tetrad analysis in Aspergillus nidulans. Ph.D. thesis, University of Glasgow.Google Scholar
Wheeler, H. E., Olive, L. S., Ernest, C. T. & Edgerton, C. W. (1948). Genetics of Glomerella. V. Crozier and ascus development. Amer. J. Bot. 35, 722–728.CrossRefGoogle Scholar
Wilson, I. M. (1952). The ascogenous hyphae of Pyronema confluens. Ann. Bot., Lond., 16, 321–339.Google Scholar