dictyNews
Electronic Edition
Volume 46, number20
July 24, 2020
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Abstracts
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From environmental sensing to developmental control – cognitive
evolution in Dictyostelid social amoebas
Pauline Schaap
School of Life Sciences, University of Dundee, Dundee DD15EH, UK
Philosophical Transactions of the Royal Society B, in press
Dictyostelid social amoebas respond to starvation by self-organizing
into multicellular slugs that migrate towards light to construct spore-
bearing structures. These behaviours depend on excitable networks
that enable amoebas to produce propagating waves of the
chemoattractant cAMP, and to respond by directional movement.
cAMP additionally regulates cell differentiation throughout
development, with differentiation and cell movement being
coordinated by interaction of the stalk inducer c-di-GMP with the
adenylate cyclase that generates cAMP oscillations. Evolutionary
studies indicate how the manifold roles of cAMP in multicellular
development evolved from a role as intermediate for starvation-
induced encystation in the unicellular ancestor. A merger of this
stress response with the chemotaxis excitable networks yielded
the developmental complexity and cognitive capabilities of extant
Dictyostelia.
submitted by: Pauline Schaap [[log in to unmask]]
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Unusual occurrence of two bona-fide CCA-adding enzymes in
Dictyostelium discoideum
Erber, L., Hoffmann, A., Fallmann, J., Hagedorn, M., Hammann, C.,
Stadler, P., Betat, H., Prohaska, S., and Mörl, M.
International Journal of Molecular Sciences 2020, in press
https://www.mdpi.com/1422-0067/21/15/5210
Dictyostelium discoideum, the model organism for the evolutionary
supergroup of Amoebozoa, is a social amoeba that, upon starvation,
undergoes transition from a unicellular to a multicellular organism.
In its genome, we identified two genes encoding for tRNA
nucleotidyltransferases. Such pairs of tRNA nucleotidyltransferases
usually represent collaborating partial activities catalyzing CC- and
A-addition to the tRNA 3'-end, respectively. In D. discoideum,
however, both enzymes exhibit identical activities, representing
bona-fide CCA-adding enzymes. Detailed characterization of the
corresponding activities revealed that both enzymes seem to be
essential and are regulated inversely during different developmental
stages of D. discoideum. Intriguingly, this is the first description of
two functionally equivalent CCA-adding enzymes using the same set
of tRNAs and showing a similar distribution within the cell. This
situation seems to be a common feature in Dictyostelia, as other
members of this phylum carry similar pairs of tRNA
nucleotidyltransferase genes in their genome.
submitted by: Christian Hammann [[log in to unmask]]
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[End dictyNews, volume 46, number 20]
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