dictyNews
Electronic Edition
Volume 47, number 16
August 6, 2021
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Abstracts
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Hypoxia triggers collective aerotactic migration in Dictyostelium
discoideum
O. Cochet-Escartin, M. Demircigil, S. Hirose, B. Allais, P. Gonzalo,
I. Mikaelian, K. Funamoto, C. Anjard, V. Calvez, J.-P. Rieu
eLife, accepted
Using a self-generated hypoxic assay, we show that the amoeba
Dictyostelium discoideum displays a remarkable collective aerotactic
behavior. When a cell colony is covered, cells quickly consume the
available oxygen (O2) and form a dense ring moving outwards at
constant speed and density. To decipher this collective process, we
combined two technological developments: porphyrin-based O2
sensing films and microfluidic O2 gradient generators. We showed
that Dictyostelium cells exhibit aerotactic and aerokinetic response in
a low range of O2 concentration indicative of a very efficient
detection mechanism. Cell behaviors under self-generated or imposed
O2 gradients were modeled using an in silico cellular Potts model
built on experimental observations. This computational model was
complemented with a parsimonious ‘Go or Grow’ partial differential
equation (PDE) model. In both models, we found that the collective
migration of a dense ring can be explained by the interplay between
cell division and the modulation of aerotaxis.
submitted by: Christophe Anjard [[log in to unmask]]
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Dictyostelium discoideum: an alternative non-animal model for
developmental toxicity testing
Robert P. Baines1, Kathryn Wolton2, Christopher R. L. Thompson1*
1 Centre for Life's Origins and Evolution, Department of Genetics,
Evolution and Environment, University College London, Darwin
Building, Gower Street, London, WC1E 6BT, UK
2 Syngenta, Jealott’s Hill International Research Centre, Bracknell,
Berkshire, RG42 6EY
* Corresponding author
Toxicological Sciences, in press
A critical aspect of toxicity evaluation is developmental and
reproductive toxicity (DART) testing. Traditionally, DART testing
has been conducted in vivo in mammalian model systems. New
legislation aimed at reducing animal use and the prohibitive costs
associated with DART testing, together with a need to understand
the genetic pathways underlying developmental toxicity means there
is a growing demand for alternative model systems for toxicity
evaluation. Here we explore the potential of the eukaryotic social
amoeba Dictyostelium discoideum, which is already widely used as
a simple model system for cell and developmental biology, as a
potential non-animal model for DART testing. We developed assays
for high-throughput screening of toxicity during D. discoideum
growth and development. This allowed the toxicity of a broad range
of test compounds to be characterized, which revealed that
D. discoideum can broadly predict mammalian toxicity. In addition,
we show that this system can be used to perform functional genomic
screens to compare the molecular modes of action of different
compounds. For example, genome wide screens for mutations that
affect lithium and valproic acid (VPA) toxicity allowed common and
unique biological targets and molecular processes mediating their
toxicity to be identified. These studies illustrate that
D. discoideum could represent a predictive non-animal model for
DART testing due to its amenability to high throughput approaches
and molecular genetic tractability.
submitted by: Chris Thompson [[log in to unmask]]
———————————————————————————————————
Mutant resources for functional genomics in Dictyostelium
discoideum using REMI-seq technology
Nicole Gruenheit1*, Amy Baldwin2*, Balint Stewart1*, Sarah Jaques2,
Thomas Keller3, Katie Parkinson3, William Salvidge1, Robert Baines1,
Chris Brimson1, Jason B. Wolf4, Rex Chisholm5, Adrian J. Harwood2†
and Christopher R. L. Thompson1†
1 Centre for Life’s Origins and Evolution, Department of Genetics,
Evolution and Environment, University College London, Darwin
Building, Gower Street, London, WC1E 6BT, UK
2 Cardiff School of Biosciences, Hadyn Ellis Building, Maindy Road,
Cardiff University, Cardiff, UK, CF24 4HQ
3 Division of Developmental Biology and Medicine, Faculty of Biology,
Medicine and Health, The University of Manchester, Michael Smith
Building, Oxford Road, Manchester, M13 9PT, UK
4 Milner Centre for Evolution and Department of Biology and
Biochemistry, University of Bath, Claverton Down,
Bath, BA2 7AY, UK
5 Feinberg School of Medicine, Northwestern University, Chicago,
Illinois, USA, 60611
* These authors contributed equally to this work
† Authors for correspondence ([log in to unmask],
[log in to unmask],)
BMC Biology, in press
Background
Genomes can be sequenced with relative ease, but ascribing gene
function remains a major challenge. Genetically tractable model
systems are crucial to meet this challenge. One powerful model is
the social amoeba Dictyostelium discoideum, a eukaryotic microbe
widely used to study diverse questions in cell, developmental and
evolutionary biology.
Results
We describe REMI-seq, an adaptation of Tn-seq, which allows high
throughput, en masse and quantitative identification of the genomic
site of insertion of a drug resistance marker after restriction
enzyme mediated integration. We use REMI-seq to develop tools
which greatly enhance the efficiency with which the sequence,
transcriptome or proteome variation can be linked to phenotype in
D. discoideum. These comprise (1) a near genome-wide resource of
individual mutants (2) a defined pool of ‘barcoded’ mutants to
allow large-scale parallel phenotypic analyses. These resources are
freely available and easily accessible through the REMI-seq website
that also provides comprehensive guidance and pipelines for data
analysis. We demonstrate that integrating these resources allows
novel regulators of cell migration, phagocytosis and
macropinocytosis to be rapidly identified.
Conclusions
We present methods and resources, generated using REMI-seq, for
high throughput gene function analysis in a key model system.
submitted by: Chris Thompson [[log in to unmask]]
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