Abstracts - Society for Developmental Biology

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generated nine mAbs that are specific to various cell types including the epidermis, musclefibers, protonephridia, and
multiple neural populations. We have also characterized the staining patterns of these mAbs in regenerating planarians and
found that a subset distinctly label cells within the regeneration blastema. We are currently co-staining planarians with the
mAbs and other well-characterized tissue markers to further characterize the specific cell populations they label. To track
cell differentiation, we are using these mAbs in conjunction with a new bromodeoxyuridine (BrdU) soaking protocol to
track differentiation of mAb positive cells from neoblasts. We have optimized BrdU penetrance and yield a higher BrdU
labeling success rate compared to currently published feeding protocols when intact worms were evaluated shortly after
pulsing. Our work has produced novel markers to visualize planariant issues and a new method for introducing BrdU to
quantify their differentiation. These tools will improve our understanding of how the neoblasts reconstitute different tissues
during regeneration and aid in phenotypic screenings of gene knockdown experiments in planarians. This work was
supported by CIRM GrantRN2-00940-1 to RMZ.
Program/Abstract # 188
Blastemal growth in regenerating Giraradia tigrina is inhibited by xenoestrogens
Minicozzi, Michael R.; Ridgeway, Corinna; Anandan, Anna; Gallagher, Heather; Mass, Spencer, Department of Biology,
SUNY New Paltz, New Paltz, United States
Xenoestrogens are chemicals that mimic estrogen by direct binding to estrogen receptors. Many of these chemicals are
industrial enviromental pollutants such as bisphenol A (BPA) and 4-octylphenol (4-OP). Prior work in our lab has shown
that regeneration is disrupted by exposure to BPA and 4-OP in several species of planarians. In this work we use a
quantitative method to measure blastemal growth in planarian regeneration and analyze the results with a logistic growth
model. Using the model we show that xenoestrogens affect not only the rate of regeneration but also the size of the
resulting blastema in a dose dependent manner.
Program/Abstract # 189
Elucidating the mechanism of proximal tubule regeneration in the pronephros Xenopus laevis tadpoles
Caine, Shoshoni T., Tufts University Biology, Medford, United States
While the renal system is critical for maintaining homeostatic equilibrium within the body, it is also susceptible to various
kinds of damage. Tubule dysfunction in particular contributes to acute renal failure and chronic kidney disease in millions
of patients worldwide. Since current treatments are highly invasive and often unavailable, we are exploring the
regenerative capacity of renal structures, specifically focusing on tubule restoration. Previously we have shown that
Xenopus laevis tadpoles have this capacity to regenerate proximal tubules following partial nephrectomy. We have also
validated the renal identity of the regenerate and demonstrated its ability to functional normally, providing the first
evidence of renal regeneration in an amphibian system. We are now investigating the mechanism by which this
regenerative event occurs, focusing our studies on the three week period following damage. An increase in the active form
of caspase 3 was observed shortly after injury suggesting a role for apoptosis during the initial wound healing phase. This
phenomenon has also been observed in the mammalian metanephric repair model, and thus appears to be a conserved
aspect of the renal regeneration process. We are currently conducting inhibitor studies to assess whether this apoptotic
event is critical for successful regeneration. Additionally, we are interested in the role that matrix metalloproteinase 9
(Xmmp-9) plays in this regenerative process. While Xmmp-9 hasbeen found to be essential for proper renal development,
its role in renal repair has never been examined. Previously we have observed a biphasic pattern of Xmmp-9 up-regulation
during renal regeneration, first during the initial wound healing process, and again later during tubule restoration. We are
now investigating the roles that this protease may be playing during these two independent phases. Preliminary evidence
suggests that Xmmp-9 may have an inhibitory effect on renewal of proximal tubule tissue.
Program/Abstract # 190
Calcium-mediated electrical activity manifests in regenerating tissues and is required for appropriate muscle
regeneration
Tu, Michelle, University of California, Davis, Sacramento, United States
Xenopus laevis tadpole can regenerate its tail after amputation with complete recovery of muscle, notochord and spinal
cord. The cellular and molecular mechanisms underlying this phenomenon are still unclear. The goal of this study is to
elucidate the mechanisms underlying muscle regeneration. We hypothesize that Ca2+- mediated electrical activity
manifests in regenerating tissues and that this activity is necessary for proper muscle regeneration. Ca2+ imaging
experiments show that cells in the regenerating tail exhibit spontaneous Ca2+ transients as early as 2 h post amputation
(hpa). The level of activity appears to be temporally regulated and ceases by 30 hpa. Ca2+ transients last for 5-70 s with
amplitudes in the range of 200-270% above baseline, have a rise time of 5-23 s and a frequency of 3-24/h per active cell.