Project Details


DNA rearrangements have been found in both prokaryotic and eukaryotic
genomes, leading to the surprising conclusion that the genome is far more
dynamic that previously believed. While studying the 27kD zein locus in
maize, we discovered that it is susceptible to several different novel DNA
rearrangements. In inbred maize strains the locus exists either as a
single gene or as a tandem duplication of 12 kb that includes the 670 bp
coding region. In all cases examined thus far, the single gene was derived
irreversibly from the duplication by homologous intrachromosomal
recombination. Most of the recombinations occur somatically, leading to a
mosaic of cells, although some can be introduced into the gametes and be
inherited. In either case, the pattern rearrangement appears to be cell
and site specific. Therefore, the tandem duplication should contain
sequences that are recognized and regulated by specific recombinases.

We would like to study this process and its role using a combination of
molecular techniques and genetic approaches. In situ hybridization
techniques will be used to study these events on the cellular level.
Matings and backcrosses between several of the inbreds should allow us to
distinguish between the different cellular factors that play a role in
recombination, and whether all 27kD alleles can be affected. We have
already begun cloning and sequencing the recombined and unrecombined loci
isolated from different inbred strains, and from endosperm of the inbred
with high-frequency rearrangements. Recombination in different cell types
will be studied using a viral vector system, introduced into cell cultures
and plant tissues with a particle gun. The recombined vector will be
rescued in bacterial cells by a novel selection system that has proven
effective in a similar analysis of the V-(D)-J recombination system in
mammalian lymphocytes.
Effective start/end date1/1/9011/30/93


  • Genetics
  • Molecular Biology


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