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Wild chromosomal variants in Aspergillus nidulans
D M Geiser1, M L Arnold, W E Timberlake
1Department of Genetics, University of Georgia, Athens, GA 30602, USA.
Current Genetics
|February 1, 1996
Summary
Researchers studied Aspergillus nidulans karyotypes globally, finding minimal variation except for a B-chromosome and a significant translocation. This translocation led to sterility in progeny due to chromosomal duplication, a novel finding in A. nidulans.
Area of Science:
- Genetics
- Molecular Biology
- Mycology
Background:
- Understanding chromosomal structure and variation is crucial for genetic studies.
- Aspergillus nidulans is a model organism for fungal genetics.
Purpose of the Study:
- To determine the karyotypic variation in wild-type Aspergillus nidulans isolates.
- To investigate the meiotic effects of chromosomal abnormalities, specifically a translocation.
Main Methods:
- Pulsed-field gel electrophoresis (PFGE) for karyotyping.
- Utilized chromosome-specific cosmid DNA libraries.
- Performed genetic crosses to analyze meiotic segregation and phenotypes.
Main Results:
- Identified minimal structural variation among global Aspergillus nidulans isolates.
- Discovered a non-essential B-chromosome (approx. 1.0 Mb) in one isolate.
- Documented a non-reciprocal translocation (approx. 1.6 Mb) of chromosome VI onto chromosome VIII in another isolate.
- Progeny from crosses involving the translocation isolate exhibited duplicated chromosomes, leading to a sterile, barren phenotype.
- Observed vegetative instability of the chromosomal duplication.
Conclusions:
- The study reveals limited karyotypic diversity in wild-type Aspergillus nidulans.
- A chromosomal translocation in A. nidulans is associated with partial disomy and sterility in progeny.
- This is the first reported instance linking chromosomal duplication to sterility in Aspergillus nidulans.