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Robertson's Mutator transposable elements in maize undergo cycles of activity and then inactivity that correlate with changes in cytosine methylation. Mutator-like elements are present in the Arabidopsis genome but are heavily methylated and inactive. These elements become demethylated and active in the chromatin-remodeling mutant ddm1 (Decrease in DNA(More)
The higher plant Arabidopsis thaliana (Arabidopsis) is an important model for identifying plant genes and determining their function. To assist biological investigations and to define chromosome structure, a coordinated effort to sequence the Arabidopsis genome was initiated in late 1996. Here we report one of the first milestones of this project, the(More)
The genomes of higher plants and animals are highly differentiated, and are composed of a relatively small number of genes and a large fraction of repetitive DNA. The bulk of this repetitive DNA constitutes transposable, and especially retrotransposable, elements. It has been hypothesized that most of these elements are heavily methylated relative to genes,(More)
PROLIFERA (PRL) encodes a homologue of the DNA replication licensing factor Mcm7, a highly conserved protein found in all eukaryotes. Insertions in the PROLIFERA gene are lethal, resulting in decreased transmission through the female gametophyte, and homozygous embryonic lethality. We show here that PROLIFERA is specifically expressed in populations of(More)
The involution of presumptive mesoderm that occurs during amphibian gastrulation is a complex process requiring the coordinated action of a diverse range of cells. We show that cells with distinct morphologies, resembling each of those normally found in the involuting tissue of the Xenopus embryo, are induced in dispersed animal pole cells by different(More)
In situ hybridization analysis of Xenopus laevis embryos reveals that mRNA encoding the platelet-derived growth factor alpha receptor (PDGFR alpha) is expressed in cephalic neural crest masses prior to migration from the future neural tube and during their migration into the visceral arches. The analysis of fluorescently labeled neural crest tissue(More)
We have cloned the Xenopus PDGF alpha receptor cDNA and have used this clone, along with cDNA encoding PDGF A, to examine their expression pattern in Xenopus embryos and to determine the factors responsible for lineage specificity. Recombinant Xenopus alpha receptor expressed in COS cells exhibits PDGF-A-dependent tyrosine kinase activity. We find that(More)
Secreted and membrane-spanning proteins play fundamental roles in plant development but pose challenges for genetic identification and characterization. We describe a "secretion trap" screen for gene trap insertions in genes encoding proteins routed through the secretory pathway. The gene trap transposon encodes a beta-glucuronidase reporter enzyme that is(More)
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