Full text in pdf format

Duplicate gene inactivation affects ascospore viability in Aspergillus nidulans

M.A.A. Castro-Prado^I; J.S. Gebara^I; C.B. Querol^I; O.L.A.D. Zucchi^II; T. M. A. D. Zucchi^III

^IDepartamento de Biologia Celular e Genética, Universidade Estadual de Maringá, Av. Colombo 3690, 87020-900 Maringá, PR, Brasil
^IIDepartamento de Física e QUímica, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, Via do Café s/n, 14049-970 Ribeirão Preto, SP, Brasil
^IIIDepartamento de Parasitologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Prof. Lineu Prestes 1374, 05508-900 São Paulo, SP, Brasil. Send correspondence to T.M.A.D.Z.

ABSTRACT

A gene inactivation system (GIS) alters duplicated genes in the Aspergillus nidulans genome. GIS activity only occurs in the sexual cycle of the strain bearing the Dp(II-I) duplication. A reduction of the number of ascospores per cleistothecium and of their viability was observed in meiotic crosses, heterozygous for the Dp(II-I) duplication. In the present work a gene inactivation system that acts in the A. nidulans genome is characterized. It influences ascospore viability among the meiotic segregants of the first and second generations (F1. and F2) and reincidence of the process after 5-azacytidine treatment of the segregants.

Keywords: gene inactivation; ascospore; Aspergillus nidulans.

REFERENCES

Bull, J.H. and Wooton, J.C. (1984). Heavily methylated amplified DNA in transformants of Neurospora crassa. Nature 310: 701-704.

Bull, J.H., Smith, D.J. and Turner, G. (1988). Transformation of Penicillium chrysogenum with a dominance of selectable marker. Curr. Genet. 13: 377-382.

Cambareri, E.B., Jensen, B.C., Schabtach, E. and Selker, E.U. (1989). Repeat induced G-C to A-T mutations in Neurospora. Science 244: 1571-1575.

Cambareri, E.B., Singer, M.J. and Selker, E.U. (1991). Recurrence of repeat-induced point mutation (RIP) in Neurospora crassa. Genetics 127: 699-710.

Castro-Prado, M.A.A. and Zucchi, T.M.A.D. (1991). Meiotic segregation of a recessive gene (wA2) included in a Dp(II-I) of Aspergillus nidulans. Braz. J. Genet. 14: 249-260.

Castro-Prado, M.A.A. and Zucchi, T.M.A.D. (1993). Inactivation of DNA sequences in Aspergillus nidulans involving non-linked duplication. Braz. J. Genet. 16: 211-217.

Castro-Prado, M.A.A. and Zucchi, T.M.A.D. (1996). A gene inactivation system (GIS) acting in meiosis of a duplicated strain of Aspergillus nidulans. Braz. J. Genet. 19: 17-25.

Cedar, H. (1988). DNA methylation and gene activity. Cell 70: 5-8.

Debuchy, R., Coppin-Raynal, E., Le Coze, D. and Brygoo, Y. (1988). Chromosome walking towards a centromere in the filamentous fungus Podospora anserina: cloning of a sequence lethal at a two-copy state. Curr. Genet. 13: 105-111.

Doerfler, W. (1983). DNA methylation and gene activity. Ann. Rev. Biochem. 52: 93-124.

Faugeron, G., Rhounim, L. and Rossignol, J. (1990). How does the cell count the number of ectopic copies of a gene in the premeiotic inactivation process acting in Ascobolus immerses? Genetics 124: 585-591.

Fincham, J.R. (1989). Transformation in fungi. Microbiol. Rev. 53: 148-170.

Foss, H.M. and Selker, E.U. (1991). Efficient DNA pairing in Neurospora mutant defective in chromosome pairing. Mol. Gen. Genet. 231: 49-52.

Glass, N.L. and Lee, L. (1992). Isolation of Neurospora crassa A mating type mutants by Repeat Induced Point Mutation (RIP). Genetics 132: 125-133.

Goyon, C. and Faugeron, G. (1989). Targeted transformation of Ascobolus immerses and methylation of the resulting duplicated DNA sequences. Mol. Cell. Biol. 9: 2818-2827.

Holliday, R. (1987). The inheritance of epigenetic defects. Science 238: 163-170.

Kricker, M.C., Drake, J.W. and Radman, M. (1992). Duplication-targeted DNA methylation and mutagenesis in the evolution of eukariotic chromosomes. Proc. Natl. Acad. Sci. USA 89: 1075-1079.

Okamoto, P.M., Garrett, R.H. and Marzluf, G.A. (1993). Molecular characterization of conventional and new repeat-induced mutants of nit-3, the structural gene that encodes nitrate reductase in Neurospora crassa. Mol. Gen. Genet. 238: 81-90.

Pontecorvo, G., Roper, J.A., Hemmons, L.M., McDonald, K.D. and Bufton, A.W.J. (1953). The genetics of Aspergillus nidulans. Adv. Genet. 5: 141-238.

Rand, D.M. (1992). RIPping and RAPping at Berkeley. Genetics 132: 1223-1224.

Razin, A. and Cedar, H. (1991). DNA methylation and gene expression. Microbiol. Rev. 55: 451-458.

Selker, E.U. (1990). Premeiotic instability of repeated sequences in Neurospora crassa. Ann. Rev. Genet. 24: 579-613.

Selker, E.U., Cambareri, E.B. and Jensen, B.C. (1987). Rearrangement of duplicated DNA specialized cells of Neurospora. Cell 51: 741-752.

Tilburn, J., Roussel, F. and Scazzocchio, C. (1990). Insertional inactivation and cloning of the wA gene of Aspergillus nidulans. Genetics 126: 81-90.

Van de Vate, C. and Jansen, G.J.O. (1978). Meiotic recombination in a duplication strain of Aspergillus nidulans. Genet. Res. 31: 29-52.

Zucchi, T.M.A.D. (1990). Isolation of putative recombination mutants of Aspergillus nidulans. Braz. J. Genet. 13: 404-424.