Abstracts - Society for Developmental Biology

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with fork retarding Replication Slow Zones RSZs/Fragile sites and cis suppressors of viral Oris. Systematization of
chromosome biology by scoring lesions/microarray analysis in combinations of Collaborative Cross Strain genomes and Y
chromosomes represents an unbiased integrative approach taking advantage of the breadth of evolutionarily selected dysregulation.
Program/Abstract # 432
Mechanisms of ROS mediated longevity in C. elegans
Yee, Callista; Yang, Wen; Hekimi, Siegfried, McGill University, Montreal, Canada
Aging is a natural process that occurs in most species and despite years of research, is a process which is still poorly
understood. Previous research using model organisms has identified three pathways which can affect aging: caloric
restriction, insulin/IGF-1 signalling, and mitochondrial signalling. In C. elegans, two mutations that affect mitochondrial
electron transport chain subunits result in increased production of reactive oxygen species (ROS). Animals carrying these
mutations have a significantly enhanced lifespan relative to the wild type. It has also been shown that treatment with prooxidants
such as paraquat (PQ) can significantly increase wild type lifespan but has no effect on the lifespan of these
mitochondrial mutants. Furthermore, treatment with anti-oxidants such as N-acetyl-cysteine (NAC) and Vitamin C can
decrease the longevity of these mutants to the wild-type level. These and other results suggest that increased levels of ROS
act as a signal to extend lifespan in C. elegans. In order to determine the mechanisms involved in ROS signalling,
microarrays were performed on long-lived mitochondrial mutants and wild type animals treated with PQ. Between the two
mitochondrial mutants tested, an 80% overlap of the genes that were upregulated was detected. Most significantly, 50% of
the genes found in this overlap were also upregulated in the wild type animals treated with PQ. This pattern was also
observed for downregulated genes. This suggests that the genes that were upregulated by both the mitochondrial mutations
and by PQ (~500) are likely to be involved in ROS mediated longevity. An RNAi screen of the genes found to be
commonly upregulated is currently being performed in the mutant backgrounds.
Program/Abstract # 433
Characterising the role of a regulator of G protein signalling in cranial sensory ganglia formation
Fleenor, Stephen; Begbie, Jo, University of Oxford, Oxford, United Kingdom
The cranial sensory ganglia, which are responsible for relaying a variety of sensations in the head, form in part by
migration of neuroblasts delaminating from specialised thickenings of surface ectoderm called placodes. Here we
investigate the molecular mechanisms governing neuroblast generation and migration from the placode in the developing
chick embryo by characterising the role of a regulator of G protein signalling, RGS3. We initially identified RGS3 in a
microarray screening for molecules upregulated during neuroblast migration. We show it to be specifically expressed in
cranial sensory neuroblasts during ganglia formation. In addition, knockdown of RGS3 expression via short-hairpin RNA
results unexpectedly in precocious extension of axon projections and neuroblast migration. Future work elucidating this
function will include differential analysis of naturally-occurring isoforms of RGS3, as well as the broader role RGS3 may
play in G protein signalling.
Program/Abstract # 434
The role of NFAT/calcium pathway during kidney development and polycystic kidney disease
Saban, Jeremy; Miller, Michelle; Corsini, Rachel; Iglesias, Diana; Goodyer, Paul (MCHRI, Westmount, Canada)
In 2005, Simons et al. proposed that during kidney development there is a switch from canonical to non-canonical Wnt
signalling. Failure to do so could result in a cystic kidney phenotype. Our lab described that canonical Wnt signalling is
high during normal kidney development and is down regulated once nephrogenesis is completed. This is also the case in
two mouse models of polycystic kidney disease (PKD). We hypothesize that non-canonical Wnt signalling could be
abnormally regulated in PKD. We studied the role of the NFAT/calcium non canonical pathway during kidney
development and explored a potential role in PKD. We employed an NFAT-luciferase reporter mouse, where NFAT is the
primary downstream signaling molecule of the Wnt-calcium pathway. We found that Wnt/calcium signaling peaks from
embryonic day E13-E16 in wild type embryonic mouse kidneys. This reporter was responsive to non-canonical Wnts such
as Wnt5a and Wnt11, and the effect of the Wnts could be abrogated by cyclosporin-A, a specific inhibitor of the pathway.
To study the functional role of this pathway in the developing kidney, we examined Wnt-calcium signaling in different
kidney cell lines, finding that turning on the Wnt-calcium pathway restricts cell motility, without affecting cell proliferation
or apoptosis. In addition, in situ hybridization showed that Wnt-calcium signaling is located in the nephrogenic zone;
however, preliminary data shows that activity seems to be located in the ureteric bud (UB) cells. This may indicate Wntcalcium
signaling is active at the UB tips and could be involved in branching morphogenesis. Preliminary data indicates
that the pathway may be down regulated in a polycystic kidney disease mouse model.