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@PHDTHESIS{Schotthfer:816099,
author = {Schotthöfer, Susanne Katharina},
othercontributors = {Bohrmann, Johannes and Spehr, Marc},
title = {{U}ntersuchungen zur elektrochemischen {R}egulation der
{M}usterbildung im {O}var von {D}rosophila melanogaster},
school = {RWTH Aachen University},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2021-02963},
pages = {1 Online-Ressource : Illustrationen, Diagramme},
year = {2021},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, RWTH Aachen University, 2021},
abstract = {Several developmental and regenerative processes are known
to be controlled by bioelectrical signals. Transcellular
changes in membrane potential (Vmem)- and intracellular pH
(pHi)-patterns, like electrochemical gradients, affect
cytoskeletal organisation and planar cell polarity. The main
focus of the present study was the identification of
ion-transport mechanisms and signalling pathways that form
the basis of this electrochemical regulation, and the
evaluation of earlier results using genetic methods. Axis
formation is one of several developmental processes for
which electrochemical regulation has been demonstrated, and
connections between bioelectrical polarity and cytoskeletal
polarity are therefore assumed. The present study clearly
indicates that bioelectrical polarity and cytoskeletal
polarity are closely linked to axial polarity in Drosophila
wild-type and gurken (grk) mutant follicles during the
course of oogenesis. Corresponding to a disturbed
morphological anterior-posterior (a-p) polarity in grk, the
follicular epithelium (FE) showed, in stage 9, a
significantly reduced a-p Vmem-gradient compared to wild
type and changes in cytoskeletal organisation. The most
striking differences were visible during stage 10B when
dorsal-ventral (d-v) polarity is established. Concurrent
with morphological d-v polarity, significant d-v
electrochemical gradients and characteristic stage-specific
basal microfilament and microtubule patterns emerged in the
wild type. In grk, however, comparable transversal
electrochemical gradients, characteristic cytoskeletal
patterns and a morphological d-v polarity were absent.
Presumably, missing Grk-EGFR signalling acts influence on
the asymmetric distribution or activation of ion-transport
mechanisms and gap junctions. Consequently, electrochemical
gradients are influenced, alterations in cytoskeletal
organisation fail to occur, and the morphology of the FE
changes. Previously identified ion-transport mechanisms in
the FE were reevaluated using the genetically-encoded
Vmem-sensor ArcLight and the pHi-sensor pHluorin-Moesin in
combination with specific inhibitors. The inhibition
experiments using the genetically-encoded sensors confirm
that the targeted ion-transport mechanisms play important
roles in generating bioelectrical signals in the FE. We
detected significant Vmem- and pHi-changes which are
comparable to previously described changes using the
voltage- and pH-sensitive fluorescent dyes DiBAC and CFDA.
In a RNAi-knockdown screen, five genes of ion-transport
mechanisms and gap-junction subunits were identified
excerting influence on ovary development and/or oogenesis.
Complete loss of ovaries or small ovaries were observed as
results of soma knockdowns of the innexins inx1 and inx3,
and of the DEG/ENaC family member ripped pocket (rpk), as
well as of germline knockdown of rpk. Soma knockdown of the
V-ATPase-subunit vha55 caused size-reduced ovaries with
degenerating follicles from stage 10B onward. The highly
penetrant knockdown phenotypes suggest that the induced
electrochemical dysregulation has massive impact on
cytoskeletal organisation. Accordingly, differentiation of
somatic stem cells as well as ovary morphology or the
development of follicles are disturbed.Comparable to changes
in cytoskeletal properties in grk, soma knockdown of the
open rectifier K+ channel 1 (ork1) resulted in altered basal
microfilament and microtubule patterns. ork1-follicles show
a characteristic round-egg phenotype, resembling the
phenotype of known round-egg-mutants. Round-egg mutants have
been associated with the Fat2 planar cell-polarity pathway
in the FE. In summary, the results of this study provide
further evidence for electrochemical regulation of
developmental processes via the control of signalling
pathways and cytoskeletal elements. As the analysis of
RNAi-knockdowns and the mutant grk indicate, electrochemical
dysregulation affects essential functions during Drosophila
ovary development and oogenesis. Changes in bioelectrical
properties cause alterations in the organisation of the
cytoskeleton, which finally result in altered morphology of
the FE and the whole follicle.},
cin = {162020 / 160000},
ddc = {570},
cid = {$I:(DE-82)162020_20140620$ / $I:(DE-82)160000_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2021-02963},
url = {https://publications.rwth-aachen.de/record/816099},
}
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