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Recombination and DNA mismatch repair of an Aspergillus nidulans mutant

Edna Elizabeth S. Celere; Tânia M.A. Domingues Zucchi

Departamento de Parasitologia, Instituto de Ciências Biomédicas, USP, Av. Prof. Lineu Prestes, 1374, 05508 São Paulo, SP, Brasil. Send correspondence to T.M.A.D.Z.

ABSTRACT

After mutagenizing a strain of Aspergillus nidulans with 80 KR of y irradiation, the surviving conidia were individually crossed to a tester strain and the meiotic recombination frequencies, in a defined chromosomic interval, were determined through spot-testing (Zucchi, Rev. Bras. Gen. 13: 409-424, 1990). The EC mutant was selected mainly through the RF meth-w (25%) presented in the spot-test.
In a more complete genetic analysis it was observed that the EC mutant presents several alterations that vary II   um cross to cross and exhibited an abnormal meiotic pattern. The mutation in EC affects only meiosis since no alteration in vegetative growth or in mitotic stability was found. Among the selfed cleistothecia products we found a wide variation in the segregation pattern of the genetic markers. Some of the observed meiotic abnormalities can be attributed to the uvs mutation present in the EC mutant, which is more effective when in homozygosis than in heterozygosis.

Keywords: Recombination; DNA repair; Aspergillus nidulans.

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