Chromosome rearrangements in Xanthophylomyces dendrorhous
.
Claudio Martínez (1), Germán Hermosilla (2), Valenzuela Juan
Carlos (1), Pinto Ximena (1), Retamales Patricio (3), Cifuentes Víctor
(3)
(1) DCYTA and CECTA, Universidad de Santiago, Alameda 3363, Santiago,
7254758, Chile;
(2) ICBM, Universidad de Chile;
(3) Departamento de Ciencias Ecológicas, Universidad de Chile
X. dendrorhous is a yeast that shows a high degree of length
chromosome polymorphism (CLP) among wild strains. The mechanisms
involved are not well known, however, some researchers postulate that
homologous recombination could play a main role. To test this
hypothesis, we have set ourselves to search for DNA sequences that show
evidence of changes and, furthermore, have correlation with CLP
generated in the laboratory. For this, the genome of a wild type strain
and several karyotype mutants produced by treatment with mitotic
recombination inducer agents were characterized. Differential RAPDs
analysis between the wild type and its mutants permitted us to obtain a
1 kb DNA sequence that contains a GTPase gene. Hybridization experiments
showed that this sequence is present in two chromosome size
electrophoresis bands, 2.05 and 1.7 Mb, and PFGE analyses of meiotic
products suggest that these chromosomes are not homologous. On the other
hand, this sequence is present in two chromosomes generated in the atx6
karyotype mutant, a large band of 3.7-4.0 Mb and a small band of 0.78
Mb, and similarly in another mutant obtained independently. Analysis of
chromosome stability showed that the small chromosomes are unstable. Our
results suggest that the chromosomal organization in X.
dendrorhous is stable but complex, with several CLP and the
existence of low repeated sequences distributed in its genome that could
be blanks for recombination. Financed by Fondecyt 1990040 and DICYT-USACH
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