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142 invariance of the BMP signaling domain in the D. melanogaster embryo. Additionally, we have found two Drosophila species which lack the early activity of these components and have consequently variable patterning. We hypothesize that this circuitry buffers against the inherent noise of the early embryonic patterning mechanism and genetic perturbations. Furthermore, the existence of species lacking such circuitry suggests evolutionary trajectories which can allow for relaxation of this buffering activity. Program/Abstract # 430 Gastrulation in Drosophila melanogaster and Drosophila pseudoobscura: a comparison of folded gastrulation and T48 expression profiles. Hoang, Rachel; Arnold, Frederick J.; Dao, Kimberly; Garrett, William; Geratowski, Jill D.; Sohail, Faraz, Haverford College Dept of Biology, Haverford, PA, United States During gastrulation prospective mesodermal cells must be brought onto the inside of the embryo. In Drosophila melanogaster this requires precise spatial and temporal regulation of folded gastrulation (fog) and T48 gene expression. The fog and T48 gene products then activate Rho mediated cell signaling pathways. This in turn leads to constriction of the apical side of the cells, thereby initiating the internalization of the prospective mesoderm. This process of apical constriction and many of the molecular components involved are conserved in other morphogenetic events and in other species (including neural tube formation in vertebrates). However, direct homologs of fog and T48 in vertebrates have not been identified. We are interested in understanding the evolution of this morphogenesis pathway and have begun by identifying fog and T48 homologs in other dipterans. Sequence analysis of the identified fog homologs shows fog to be a rapidly evolving gene while T48 is evolving less rapidly (55 and 89% sequence similarity between D. melanogaster and D. pseudoobscura respectively). We have also analyzed the expression of fog and T48 in D. pseudoobscura embryos. Initial results show T48 expression to be conserved in the prospective mesoderm of both species at the onset of gastrulation. The temporal and spatial expression of fog is also conserved. However, the level of fog expression appears to be lower in D. pseudoobscura than in D. melanogaster. We are currently confirming these observations using Q-PCR and examining possible morphological consequences of lower fog expression. Ultimately we hope these studies will provide insight into the evolutionary processes that shape the developmental pathways of morphogenesis. Program/Abstract # 431 Dissecting physiologically and developmentally relevant genetic regulation of mammalian chromosome biology with murine interspecific backcrosses, Y chromosomes, unstable inverted repeat (IR) Sry loci, sex reversal phenotypes, viral Oris and HJ-replication restart complexes: A synopsis Ferez S., Rutgers Univ,Piscataway, United States; Tracey, Martin L. (Florida International University, Miami, United States); Felder-Gibbions, Regina (UMDNJ/Robert Wood Johnson Medical School, Piscataway, United States); Guo, Z. Sheng (University of Pittsburgh Cancer Institute, Pittsburgh, United States); Whitney, III, J. Barry (Department of Cell and Molecular Biology, Augusta, GA, United States); Dewey, Michael J. (University of South Carolina, Columbia, United States); Ceci, Jeffrey D. (University of Buffalo, Buffalo, United States); Han, In-Seob (University of Ulsan, Republic of Korea); DeLisio, Robert (Roche Institute of Molecular Biology, Nutley, United States); Woodbury, Dale (UMDNJ- RWJMS, Piscataway, United States); Schein, Lee Ann (UMDNJ/Robert Wood Johnson Medical School, Piscataway, United States) Regulation of chromosome biology is conserved, chromosome/locus specific, with 875 genes modulating genomic stability in yeast (S. cerevisiae). Interspecific combinations of genomes and Y chromosomes result in rearrangements and uncoupling of Y linkage including in the sex determining ~200 kb Sxr-region spanning the 34 kb IR Sry locus/gene. Although Sry is required for testis determination between d10-d12.5, chimeric adult males (>90% XX somatic/testicular tissues) confirm its dispensability at this stage. Using this and 3 methods we have shown that high frequency instability of Sry, in all tissues, germlines, fertile males of all strains, is genetically modulated. As predicted by IR replication, a spectrum of deletion products/amplicons from the HMG cds/flanks is detected. A putative retrotransposon fusion ORF of SRY-HMG with (Cpa6) LINE-1 ORF1 (transposase-22) domains at a cryptic splice site joint and a partial ORF-2 (RT) has also been identified. Spectra of rearranged products at Sry and yeast IR are similar with those in S.c. being sites of meiotic/mitotic DSBs rarely processed into double Holliday Junctions (dHJ) recombination intermediates and their products. Dissolution or resolution of mitotic dHJ in S.c. is determined by the interactions of Sgs1 helicase/Top3 topoisomerase/Rmi1 heteromer with Rad51 - orthologous to mammalian complexes. EMSAs and ‘Pull-Down’ assays showed that Rmi1 and Top3/Rmi1 preferentially bind HJs over 10 structures representing recombinational or replicational intermediates with the dimer also stimulating Sgs-1 N domain/HJs complexes. Our data suggest a distinction between helicase and dHJ dissolution/resolution activities of Sgs1 imposed by DNA structure at stalled forks with the unloading of Sgs1 from dHJ followed by its dimer promoted reloading. Sxr instability is also consistent with its structural similarities
143 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.
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1 Program/Abstract # 1 Role of the
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3 Program/Abstract # 7 Forward gene
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5 Program/Abstract # 13 Evolution a
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7 Program/Abstract # 19 Lethal gian
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9 Program/Abstract # 26 On the comb
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11 Program/Abstract # 32 Imaging in
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13 and electron microscopy studies
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15 paracellular space, and interact
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17 the proximal to distal axis of t
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19 Dominguez-Castellano, Maria; Gar
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21 We are interested in the role of
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23 more likely than students who di
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25 was a significant loss of cells
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27 Fgfr3 expression in the limb cho
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29 division, but rapidly loses its
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31 and migration (ADAM13). They act
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33 Program/Abstract # 101 The influ
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35 Program/Abstract # 107 Shroom3-d
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37 Program/Abstract # 113 Requireme
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39 (Queens College, Flushing, Unite
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41 these data imply that Dynamin is
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43 Congenital renal malformations a
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45 Elevated nuclear translocation o
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47 progenitor cells that cover the
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49 abnormally dilated capillaries i
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51 malformations in murine limb bud
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53 Yuqing (Mouse Imaging Centre, To
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55 in the villi at E14. At E11, the
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57 Program/Abstract # 173 The role
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59 Boldt, Clayton, UT Southwestern,
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61 examine stem cell-based CNS rege
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63 Incubation of regenerating cells
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65 learn which dynamic behaviors oc
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67 cell proliferation and for norma
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69 Program/Abstract # 209 Drosophil
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71 cranial neural crest cells, as t
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73 experimental analysis. The jerbo
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75 The through-gut, consisting of s
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77 thereby increasing the chance of
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79 into the role snx5 playsin the N
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81 Lee, Hu-Hui, National Chiayi ers
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83 understood. Here, we have establ
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85 assays, chromatin immunoprecipit
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87 approach. A similar strategy was
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89 verify the functional specificit
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Abstracts - Society for Developmental Biology

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