abstract: Physical Karyotyping

Klaas.Swart at FUNGEN.EL.WAU.NL Klaas.Swart at FUNGEN.EL.WAU.NL
Thu Sep 1 04:04:41 EST 1994

Physical Karyotyping : genetic and taxonomic applications in Aspergilli.

K. Swart, AJM. Debets, EF. Holub, CJ. Bos and RF. Hoekstra

Department of Genetics, Agricultural University, Dreijenlaan 2,
NL-6703 HA Wageningen, The Netherlands

In: The genus Aspergillus, from taxonomy and genetics to industrial 
applications, eds Keith A. Powell, Annabel Renwick and John F. Peberdy,
Plenum Press, New York and London, 1994, pp 233 - 240.
(FEMS symposium No 69)

reprints available at authors address

Pulsed field gel electrophoresis is a useful method to separa-
te chromosomes of Aspergilli and to describe a physical karyo-
type of these fungi. Once a karyotype has been established it
can be used to map genes to linkage groups if (i) probes of
these genes are available and, (ii) the relationship of chro-
mosomal bands and linkage groups is known. This approach is
also advantageous to map transformed genes. The method is not
fully adequate if two or more chromosomes comigrate in one
band. However, this is occasionally solved by using trans-
location strains with altered banding patterns. In the case of
transformed strains, a shift of the recipient chromosome may
occur due to multiple copy insertion of the transformed gene.
The latter can be used to estimate the copy number of the
transforming sequences and the stability of these insertions.
Chromosome separation has provided an elegant method to prepa-
re chromosome specific gene libraries of Aspergillus nidulans
DNA. Physical karyotyping is applied as well to analyze chro-
mosome length polymorphisms between members of presumably the
same species. Extensive variation was found in asexual 'spec-
ies' (A.niger, A.flavus, and A.parasiticus), whereas the
variation in the sexual species A.nidulans seems to be much

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