Copy Link
Add to Bookmark
Report
dictyNews Volume 26 Number 05
dictyNews
Electronic Edition
Volume 26, number 5
February 17, 2006
Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to dicty@northwestern.edu
or by using the form at
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.
Back issues of dictyNews, the Dicty Reference database and other
useful information is available at dictyBase - http://dictybase.org.
=============
Abstracts
=============
Analysis of a gene that is a potential target for the Dictyostelium STAT
protein Dd-STATa and that encodes a protein homologous to the adducin head
domain
Ryota Aoshima1, 2, Rieko Hiraoka1, 2, Nao Shimada1, 2 and Takefumi Kawata1, 3
1 Department of Biology, Faculty of Science, Toho University, 2-2-1 Miyama,
Funabashi, Chiba 274-8510, Japan
2These authors contributed equally to this work.
3 Corresponding author
Int. J. Dev. Biol., in press.
A Dd-STATa-null mutant, which is defective in expression of a Dictyostelium
homologue of the metazoan STAT (signal transducer and activators of
transcription) proteins, fails to culminate and this phenotype correlates
with the loss of expression of various prestalk (pst) genes. An EST clone,
SSK395, encodes a close homologue of the adducin amino-terminal head domain
and harbors a putative actin-binding domain. We fused promoter fragments of
the cognate gene, ahhA (adducin head homologue A), to a lacZ reporter and
determined their expression pattern. The proximal promoter region is
necessary for the expression of ahhA at an early (pre-aggregative) stage
of development and this expression is Dd-STATa independent. The distal
promoter region is necessary for expression at later stages of development
in pstA cells, of the slug, and in upper cup and pstAB cells during
culmination. The distal region is partly Dd-STATa-dependent. The ahhA-null
mutant develops almost normally until culmination, but it forms slanting
culminants that tend to collapse on to the substratum. The mutant also
occasionally forms fruiting bodies with swollen papillae and with
constrictions in the prestalk region. The AhhA protein localizes to the
stalk tube entrance and also to the upper cup cells and in cells at or near
to the constricted region where an F-actin ring is localized. These
findings suggest that Dd-STATa regulates culmination and may be necessary
for straight downward elongation of the stalk, via the putative
actin-binding protein AhhA.
Submitted by: Takefumi Kawata [tkawata@bio.sci.toho-u.ac.jp]
-----------------------------------------------------------------------------
Regulation of Dictyostelium prestalk-specific gene expression by a SHAQKY
family MYB transcription factor
Masashi Fukuzawa, Natasha V. Zhukovskaya, Yoko Yamada, Tsuyoshi Araki and
Jeffrey G. Williams+
University of Dundee
MSI/WTB Complex
Dow Street
Dundee DD1 5EH
UK
Development, in press
PstA and pstO cells are the two major populations in the prestalk region of
the Dictyostelium slug and DIF-1 is a low molecular weight signalling
molecule that selectively induces pstO cell-specific gene expression. The
two cell types are defined by their differential utilisation of spatially
separated regions of the ecmA promoter. Additionally, there are
anterior-like cells (ALC) scattered throughout the rear, prespore region
of the slug. They, like the pstO cells, utilise a cap-site distal ecmA
promoter segment termed the ecmO region. When multimerised, a 22nucleotide
sub-segment of the ecmO region directs expression in pstA cells, pstO cells
and ALC. It also directs DIF-inducible gene expression. The 22-mer was
used to purify MybE, a protein with a single MYB DNA binding domain of a
type previously found only in a large family of plant transcription factors.
Slugs of a mybE null (mybE-) strain express an ecmAO:lacZ fusion gene
(i.e. a reporter construct containing the ecmA and ecmO promoter regions)
in pstA cells but there is little or no expression in pstO cells and ALC.
The ecmA gene is not induced by DIF-1 in a mybE- strain. Thus MybE is
necessary for DIF-1 responsiveness and for the correct differentiation of
pstO cells and ALC.
Submitted by: Jeff Williams [j.g.williams@dundee.ac.uk]
==============================================================================
[End dictyNews, volume 26, number 5] 
