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dictyNews Volume 41 Number 11
dictyNews
Electronic Edition
Volume 41, number 11
May 29, 2015
Please submit abstracts of your papers as soon as they have been
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Abstracts
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A deep coverage Dictyostelium discoideum genomic DNA library
replicates stably in E. coli
Rafael D. Rosengarten, Pamela R. Beltran and Gad Shaulsky
Department of Molecular and Human Genetics Baylor College
of Medicine, Houston, TX
Genomics, accepted for publication
The natural history of the amoeba Dictyostelium discoideum
has inspired scientific inquiry for seventy-five years. A
genetically tractable haploid eukaryote, D. discoideum appeals
as a laboratory model as well. However, certain rote molecular
genetic tasks, such as PCR and cloning, are difficult due to
the AT-richness and low complexity of its genome. Here we
report on the construction of a ~20 fold coverage D. discoideum
genomic library in E. coli, cloning 4 Ð 10 kilobase partial
restriction fragments into a linear vector. End-sequencing
indicates that most clones map to the six chromosomes in an
unbiased distribution. Over 70% of these clones contain at
least one complete open reading frame. We demonstrate that
individual clones and library composition are stable over
multiple replication cycles. Our library will enable numerous
molecular biological applications and the completion of
additional speciesÕ genome sequences, and suggests a path
towards the long-elusive goal of genetic complementation.
Submitted by Gad Shaulsky [gadi@bcm.edu]
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Secreted cyclic-di-GMP induces stalk cell differentiation in the
eukaryote Dictyostelium discoideum
Minireview
Zhi-hui Chen and Pauline Schaap#
College of Life Sciences, University of Dundee, Dundee DD15EH, UK
J. Bacteriol., in press
Cyclic-di-GMP is currently recognized as the most widely used
intracellular signal molecule in prokaryotes, but roles in
eukaryotes were only recently discovered. In the social amoeba
Dictyostelium discoideum, c-di-GMP, produced by a prokaryote-type
diguanylate cyclase, induces the differentiation of stalk cells,
thereby enabling the formation of spore- bearing fruiting bodies.
In this review, we summarize the currently known mechanisms that
control the major life cycle transitions of Dictyostelium and focus
particularly on the role of c-di-GMP in stalk formation. Stalk cell
differentiation has characteristics of autophagic cell death, a
process that also occurs in higher eukaryotes. We discuss the
respective roles of c-di-GMP and of another signal molecule, DIF,
in autophagic cell death in vitro and in stalk formation in vivo.
Submitted by Pauline Schaap [p.schaap@dundee.ac.uk]
----------------------------------------------------------------------
Temporal regulation of kin recognition maintains recognition-cue
diversity and suppresses cheating
Hsing-I Ho and Gad Shaulsky
Department of Molecular and Human Genetics, Baylor College of
Medicine, Houston, TX
Nature Communications, in press
Kin recognition, the ability to distinguish kin from non-kin, can
facilitate cooperation between relatives. Evolutionary theory predicts
that polymorphism in recognition cues, which is essential for effective
recognition, would be unstable. Individuals carrying rare recognition
cues would benefit less from social interactions than individuals with
common cues, leading to loss of the genetic cue-diversity. We test
this evolutionary hypothesis in Dictyostelium discoideum, which forms
multicellular fruiting bodies by aggregation and utilizes two
polymorphic membrane proteins to facilitate preferential cooperation.
Surprisingly, we find that rare recognition variants are tolerated and
maintain their frequencies among incompatible majority during
development. Although the rare variants are initially excluded from the
aggregates, they subsequently rejoin the aggregate and produce spores.
Social cheating is also refrained in late development, thus limiting
the cost of chimerism. Our results suggest a potential mechanism to
sustain the evolutionary stability of kin recognition genes and to
suppress cheating.
Submitted by Gad Shaulsky [gadi@bcm.edu]
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[End dictyNews, volume 41, number 11]
