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dictyNews Volume 23 Number 03
Dicty News
Electronic Edition
Volume 23, number 3
July 23, 2004
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 Dicty-News, the Dicty Reference database and other
useful information is available at dictyBase - http://dictybase.org.
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Abstracts
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Cloning, sequencing and expression of the genomic DNA encoding the protein
phosphatase cdc25 in Dictyostelium discoideum
Taira Mayanagi, Yasuo Maeda, Shigenori Hirose, Tohru Arakane, Tsuyoshi Araki
and Aiko Amagai
Department of Developmental Biology and Neurosciences, Graduate School of
Life Sciences, Tohoku University, Aoba, Sendai 980-8578, Japan
Dev. Genes Evol., in press
A genomic DNA (Dd-cdc25) encoding the protein phosphatase cdc25 was
isolated from the cellular slime mold Dictyostelium discoideum. TheDd-cdc25
DNA sequence with a length of 2,958bp encodes a protein consisting of 986
amino acid residues. The sequence shares significant identities with cdc25
from human, mouse, Xenopus, Drosophila and Shizosaccharomyces pombe,
particularly at the C-terminal region including the catalytic site for
phosphatase activity. The deduced Dictyostelium cdc25 protein (Dd-cdc25)
has the highest molecular mass (109.9 kDa) in several cdc25 species so far
reported and contains four regions consisting of unusually long
asparagine-repeats (22-31 N) in the sequence. Unexpectedly, however,
Western analyses using a specific antibody raised against the C-terminus
(aa 892-986) of Dd-cdc25 have demonstrated that a short form (56 kDa),
which has the C-terminal active site of phosphatase, differently arises
during the course of Dictyostelium development. The Western analysis also
revealed marked changes in the phosphorylated state of the Dd-cdc25,
coupling with cellular development.
Submitted by: Taira Mayanagi [taira@biology.tohoku.ac.jp]
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Pleiotropy as a mechanism to stabilise cooperation
Kevin R. Foster *º, Gad Shaulsky½, Joan E. Strassmann*, David C. Queller* &
Chris R.L. Thompson½¤º
* Ecology and Evolution, Rice University, Houston, Texas 77005. ½Department
of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza,
Houston, Texas 77030. ¤ School of Biological Sciences, University of
Manchester, Manchester, M13 9PT, UK.
ºThese authors contributed equally to the work.
Nature, in press
Most genes affect many traits. This phenomenon, known as pleiotropy,
is a major constraint on evolution because adaptive change in one trait
may be compromised by others. Here we show that pleiotropy can have
the opposite effect and benefit one of the most enigmatic of adaptations -
cooperation. A spectacular act of cooperation occurs in the social amoeba
Dictyostelium discoideum, in which some cells die to form a stalk that
holds the others aloft as reproductive spores5,6,. We have identified a
gene, dimA7, in D. discoideum that has two contrasting effects. It is
required to receive the signalling molecule DIF-1 that causes
differentiation into prestalk cells. Ignoring DIF-1 and avoiding becoming
prestalk should allow cells to cheat by reducing allocation to the stalk.
However, we find that dimA is also needed for successful spore formation
in competition with the wild type. This pleiotropic linkage of stalk and
spore formation limits the potential for cheating in D. discoideum because
defecting on prestalk cell production results in an even greater reduction
in spores. We propose that the evolution of pleiotropic links between
cheating and personal costs can stabilise cooperative adaptations.
Submitted by: Chris Thompson [christopher.thompson@man.ac.uk]
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[End Dicty News, volume 23, number 3]
