Genetic and Physical Mapping of Two Centromere-Proximal Regions of Chromosome IV in Aspergillus nidulans

Authors: Aleksenko A.¹; Nielsen M.L.¹; Clutterbuck A.J.²

Source: Fungal Genetics and Biology, Volume 32, Number 1, February 2001 , pp. 45-54(10)

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Abstract:

Chromosome IV is the smallest chromosome of Aspergillus nidulans. The centromere-proximal portion of the chromosome was mapped physically using overlapping clones of a cosmid genomic library. Two contiguous segments of a physical map, based on restriction mapping of cosmid clones, were generated, together covering more than 0.4 Mb DNA. A reverse genetic mapping approach was used to establish a correlation between physical and genetic maps; i.e., marker genes were integrated into physically mapped segments and subsequently mapped by mitotic and meiotic recombination. The resulting data, together with additional classical genetic mapping, lead to a substantial revision of the genetic map of the chromosome, including the position of the centromere. Comparison of physical and genetic maps indicates that meiotic recombination is low in subcentromeric DNA, its frequency being reduced from 1 crossover per 0.8 Mb to approximately 1 crossover per 5 Mb per meiosis. The portion of the chromosome containing the functional centromere was not mapped because repeat-rich regions hindered further chromosome walking. The size of the missing segment was estimated to be between 70 and 400 kb. Copyright 2001 Academic Press.

Keywords: AMA1; Aspergillus nidulans; centromere; chromosome walking; genetic map; physical map

Language: English

Document Type: Research article

Affiliations: 1: Center for Process Biotechnology, Technical University of Denmark, Lyngby, 2800, Denmark 2: Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, G11 6NU, United Kingdom

Publication date: 2001-02-01