Gene silencing and gene activation postdoctoral or technical

Craig Pikaard pikaard at
Wed Jan 19 14:25:08 EST 2000

Several postdoctoral or technical positions are available in the Pikaard
laboratory for individuals with training in genetics, molecular biology or
biochemistry to study mechanisms responsible for gene silencing and/or gene

1. Molecular genetics of nucleolar dominance in Arabidopsis and Brassica:
Nucleolar dominance is an epigenetic phenomena in which the hundreds, to
thousands, of ribosomal RNA genes inherited from one parent are active but
the equivalent genes inherited from the other parent are selectively
silenced (reviewed in Pikaard, 1999 Trends in Plant Sci. 4:478-482).
Multiple projects can be pursued according to the candidate's interests.
These include genetic and biochemical approaches to understand how
uniparental gene discrimination is accomplished, how dominance is
established, and how repressive chromatin modifications such as DNA
methylation and histone deacetylation are targeted (see Chen and Pikaard,
1997, Genes and Development 11:2124-2136).

2. Discovery of genes encoding proteins that repress transgenes in an organ
or cell-type specific manner:  This project involves the use of transgenic
Arabidopsis lines we have isolated in which the expression of reporter
transgenes is limited to specific cell types due to chromatin modifications
that repress their transcription in other cell types. EMS mutagenesis and
activation-tagging will be used to obtain mutants in genes involved in the
tissue-specific and developmentally-regulated gene silencing.

3. Molecular dissection of an RNA polymerase holoenzyme: We have purified
to apparent homogeneity a multi-protein complex that can specifically
recognize a ribosomal RNA gene promoter and initiate transcription in the
testtube (Saez-Vasquez and Pikaard, 1997, PNAS 94: 11869-11874; Albert et
al., 1999, Mol. Cell. Biol. 19: 796-806). The complex includes at least one
protein kinase that might mediate the tight regulation of transcription in
response to hormones and growth signals. The complex also includes at least
one histone acetyltransferase which might modify chromatin to maintain an
active state. Projects include determining the subunit composition of the
purified holoenzyme (facilitated by Arabidopsis genome sequence data), and
using molecular and immunological techniques to determine the function of
subunits in promoter recognition, transcription initiation, chromatin
modification and growth regulation.

Successful postdoctoral candidates will have a Ph.D. in a relevant
scientific discipline and a proven record of productivity including
first-authored publications in internationally-recognized journals.
Eligibility for fellowship support from government or private agencies will
be an important consideration. Technician candidates should have a minimum
of a bachelor's degree and relevant undergraduate and/or profesional
research experience. Candidates should send a detailed CV and the names,
telephone numbers and e-mail addresses of three individuals who can provide
letters of recommendation to:
Craig Pikaard
Washington University, Biology Department
Campus Box 1137, One Brookings Drive
St. Louis, MO 63122-5516.
More information about the lab and plant biology research at Washington
University can be obtained at the following websites:

Craig S. Pikaard
Associate Professor
Biology Department, Washington University
Campus Box 1137, One Brookings Drive
St. Louis, MO 63130
Ph: 314-935-7569, FAX:314-935-4432
e-mail: pikaard at


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