Abstracts - Society for Developmental Biology

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RNA-directed chromatin modulation. Proper centromere function is essential for chromosome segregation and its
misregulation leads to infertility, developmental defects and cancer. Thus, dissecting the mechanism of small RNAmediated
centromere modulation by D2096.8/NAP-1 and the CSR-1 pathway is likely to provide key insights into fertility
and oncogenesis.
Program/Abstract # 236
Investigating the roles of Argonaute proteins in C. elegans development
Wu, Monica, Toronto, Canada; Claycomb, Julie M. (Toronto, ON, Canada)
Argonaute (AGO) proteins are the key effector components of RNA interference (RNAi) and related endogenous small
RNA pathways. The nematode, Caenorhabditis elegans, possesses at least 26 AGO proteins that execute a variety of
functions throughout development. Although deletion mutant strains for each of the C. elegans AGOs have been generated,
the developmental roles of only a handful of these proteins are understood. Recent mRNA expression data collected by our
lab demonstrates that many AGOs share similar expression patterns, suggesting that they may function in overlapping
roles. I have focused my initial studies on two uncharacterized AGOs: C04F12.1 and T23D8.7. I have found that T23D8.7
mutants have a significantly reduced brood size and a low-penetrance embryonic chromosome segregation defect. I am
currently deep sequencing the small RNAs associated with T23D8.7 to gain further insight into its gene regulatory
functions in germline and embryonic development. I have established that C04F12.1 localizes to P-granules, consistent
with localization studies conducted on other RNAi-related factors, and I am currently working to determine whether there
are overlapping functions between C04F12.1 and the closely related essential AGO, CSR-1. Many of the C. elegans AGOs
are broadly conserved amongst different species of nematodes, implicating them in key, evolutionarily conserved
developmental roles. The AGOs that have been characterized thus far function in distinct gene-regulatory roles. Thus,
characterization of the remaining AGOs may lead to novel insights in small RNA mediated gene silencing functions
throughout development.
Program/Abstract # 237
Investigating Glial cell abnormalities in lpr-1 and let-4 mutants
Ayala, Jesus; Mancuso, Vincent P; Sundaram, Meera, Univ of Pennsylvania, Philadelphia, United States
Glial cells provide support to neuronal cells by covering their axons and aiding in processes such as oxygen and nutrient
transport. In the nematode Caenorhabditis elegans, sheath and socket glia form a tubular structure that serves as a channel
for phasmid sensory neuron axons to reach the outside environment. lpr-1 and let-4 genes are important to maintain lumen
integrity in unicellular tubes in the excretory (renal-like) system. The lipocalin LPR-1 is a secreted protein that is required
for luminal connectivity between two unicellular tubes in the worm’s excretory system. LET-4 is a transmembrane protein
that is required for maintenance of luminal connectivity. The lpr-1 and let-4 mutants that survive to the L4 stage show dye
filling defects in the phasmids. This dye filling defect could arise as a result of defects in the phasmid glia cells or the
neurons themselves due to the loss of one or both of these genes. Due to the similarities between excretory and phasmid
glia tubes, we hypothesize that their development may require some of the same genes. To address this problem, our
research is studying the expression of lpr-1 and let-4 genes in the sheath, socket and phasmid cells. Furthermore, different
stages will be studied to observe if the defect is present at birth or if it appears later in the developmental process. As part
of our methodology, L4 worms expressing let-4::GFP or lpr-1::GFP reporters were bathed in rhodamine-DiI to stain the
phasmid neurons and determine if our genes of interests were expressed in them.
Program/Abstract # 238
microRNA regulation of Notch signaling in zebrafish retinal and vascular development
Olena, Abigail F., Vanderbilt University, Nashville, United States; Thatcher, Elizabeth J. (University of Massachusetts
Medical School, Worcester, United States); Wittgrove, Carli M.; Patton, James G. (Vanderbilt University, Nashville,
United States)
microRNAs (miRNAs) are small, endogenous, non-coding RNAs that regulate gene expression by binding to target sites
within the 3’ untranslated regions of mRNAs. Precise regulation of the Notch signaling pathway is essential for normal
vertebrate development. Here, we sought to examine the relationship between miR-216a and its target, sorting nexin 5
(snx5),which is a binding partner of mind bomb (mib), a ubiquitin ligase required for efficient activation of Notch
signaling by Delta. Loss of function of miR-216a and gain of function of snx5 lead to obvious defects in both retinal and
vascular patterning, while snx5 loss of function and miR-216a overexpression yield larval zebrafish with striking defects in
vascular development. All of the observed phenotypes are consistent with disruption of Notch signaling. Because snx5
contains conserved membrane binding domains, we hypothesize that snx5 is a vital partner of mib in promoting
endocytosis of Delta, which is required for Notch signaling. The regulation of snx5 by miR-216a, as well as new insight