Baptista F, Machado M F, Castro-Prado M A
Department of Cell Biology and Genetics, State University of Maringá, 87020-900, Maringá, PR, Brazil.
Folia Microbiol (Praha). 2003;48(5):597-604. doi: 10.1007/BF02993465.
Recombinant haploid segregants were recovered in filamentous fungus Aspergillus nidulans (Eidam) G. Winter directly from the heterokaryons instead of diploid segregants (process described earlier as parameiosis). In spite of the reproductive complexity of A. nidulans, parameiosis has only now been observed in this fungus. Since parameiosis was characterized by the occurrence of genetic recombination inside heterokaryotic hyphae, master strains (uvs+) and uvs mutants with high rate of both mitotic exchanges or chromosome nondisjunction were used to form heterokaryons. Two groups of mitotic segregants were recovered directly from heterokaryons--aneuploids and stable haploids. Heterokaryons formed with uvs mutants produced a higher number of parameiotic segregants compared to the heterokaryons formed with uvs+ strains. Segregants were analyzed by nutritional markers, acriflavine resistance and conidial color. Normal meiotic behavior of haploid recombinants was observed.
重组单倍体分离子是直接从丝状真菌构巢曲霉（Eidam）G. Winter的异核体中获得的，而不是从二倍体分离子中获得（该过程先前被描述为准性减数分裂）。尽管构巢曲霉的生殖过程复杂，但准性减数分裂直到现在才在这种真菌中被观察到。由于准性减数分裂的特征是在异核菌丝内发生基因重组，因此使用主菌株（uvs+）和有丝分裂交换或染色体不分离发生率高的uvs突变体来形成异核体。直接从异核体中获得了两组有丝分裂分离子——非整倍体和稳定单倍体。与用uvs+菌株形成的异核体相比，用uvs突变体形成的异核体产生了更多的准性减数分裂分离子。通过营养标记、吖啶黄素抗性和分生孢子颜色对分离子进行分析。观察到单倍体重组体的正常减数分裂行为。
