Program/Abstract # 325 An analysis of aminopeptidase N genes in the sea urchin genome Eric Ingersoll Department of Biology, Penn State Abington, Abington, PA, USA For several years now, my lab has been studying the expression of aminopeptidase N (APN) during sea urchin development. The recent completion of the sea urchin genome has enabled us to scan the entire Strongylocentrotus purpuratus genome for aminopeptidase N genes. Our preliminary analysis has indicated that there are approximately seven complete APN genes in the sea urchin genome as well as a number of gene fragments that are similar to APN. Most of the sea urchin APN genes share the greatest similarity with human APN and most also contain domains that are highly conserved in APN proteins. These include a trans- membrane domain, conserved cysteine residues, and a zinc binding domain in the active site. Further analysis of one of these APN genes indicates a dynamic temporal and spatial expression pattern throughout development. We present here a detailed analysis of the sea urchin APN genes as well as expression data for all genes where it is available. doi:10.1016/j.ydbio.2008.05.348 Program/Abstract # 326 Quantitative RT-PCR analysis of Dll-B misexpression in the ascidian chordate Ciona intestinalis Matthew D. Blanchette a , Frank W. Smith a,b , Michael A. Zompa a , Steven Q. Irvine a a Department of Biological Sciences, University of Rhode Island, Kingston RI, USA b Current address: Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs CT, USA The Dll-B homeobox transcription factor in the simple chordate Ciona intestinalis is expressed in the entire animal hemisphere, fated to produce the ectoderm, in blastula and gastrula stages. We used a transgenic misexpression strategy to express CiDll-B ectopically in endoderm, notochord, and mesenchyme. Transgenic CiDll-B embryos exhibit a dosage dependent range of phenotypes, from a shortened tail to embryos with severely abnormal trunk and tail morphology. We are further investigating the effects of this misexpression through quantitative RT-PCR analysis of molecular markers for ectoderm, endoderm, and muscle. doi:10.1016/j.ydbio.2008.05.349 Program/Abstract # 327 Regulators affecting miRNA function in the worm heterochronic pathway Bhaskar Vadla , Kevin Kemper, Eric G. Moss Department of Molecular Biology, UMDNJ, Stratford, NJ, USA In most cases we do not understand how miRNAs interact with other regulators to control a particular outcome. The heterochronic pathway of C. elegans contains multiple microRNAs and governs the timing cell fate decisions during larval stages. Three let-7-family miRNAs, mir-48, -84 and mir-241, repress the gene hbl-1 to control L2- specific fates. Additional protein factors influence this regulation. Specifically, lin-28 and lin-46 oppose each other to control the same cell fates. We found that LIN-28, a cytoplasmic mRNA binding protein, positively regulates hbl-1 through its 3′-UTR. Our genetic analysis revealed that a negative factor other than these three miRNAs acts on hbl-1. This other factor does not appear to be puf-9, and may be another miRNA, like let-7, lin-4 or mir-237. It acts with or downstream of lin-46, since a lin-46 mutant enhances the retarded development phenotype of deletion of the three let-7 sisters. We also found that lin- 46, which encodes a putative scaffolding protein, is periodically expressed and can form cytoplasmic foci resembling P-bodies. lin-46 mutant greatly enhances the retarded phenotype of an ain-1 mutant. AIN-1 (ALG-1-interacting protein) resembles GW182, a human protein involved in the miRNA pathway. In addition, hbl-1(RNAi) is epistatic to the lin-46; ain-1 double mutant. Therefore, lin-46 may aid microRNAs in repressing hbl-1. We are currently attempting to define the regions of the 3′ UTR through which lin-28 and lin-46 act. Yeast two-hybrid assays are being used to examine LIN-46 physical interactions. doi:10.1016/j.ydbio.2008.05.350 Program/Abstract # 328 HIM-8 and ZIM zinc-finger proteins globally affect transcription factor activity Kang Zhou , Hongliu Sun, Wendy Hanna-Rose Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA, USA HIM-8 is a C2H2 zinc-finger protein encoded together with a family of zinc-finger proteins, ZIM-1, ZIM-2 and ZIM-3 in an operon. HIM-8 and ZIM proteins are required for homologous synapsis during meiosis (Phillips and Dernburg). In addition to their meiotic function, our previous studies demonstrated that HIM-8 and ZIM proteins also function outside the gonad to regulate the activities of transcription factors. For example, him-8 mutations can suppress the uterine–vulva connection and egg-laying defects caused by Sox family gene egl-13 mutants. Besides egl-13, him-8 mutations can suppress phenotypes of a broad range of transcription factor mutants, including HMG box, zinc-finger and Hox family genes. Meanwhile, mutations in zim genes can suppress egl-13 mutant phenotypes as well. Only non-null alleles of these transcription factors can be suppressed by him-8 alleles with a mutation in zinc-finger domain, indicating transcriptional regulation of the suppression. We propose that HIM-8 and its related ZIM proteins are expressed in somatic tissues and can antagonize functions of a broad range of transcription factors. We are using a GFP reporter driven by the him-8 promoter and immunofluorescent staining to investigate its somatic expression. We are also using transgenes to investigate the function of somatic HIM-8 expression by expressing wild type HIM-8 outside of the gonad to revert the rescue by him-8. We found the histone H3 methylation is upregulated in him-8 mutants, suggesting that HIM-8 possibly regulates gene expression by altering chromatin structure, allowing it to have broad effects on a variety of factors. doi:10.1016/j.ydbio.2008.05.351 Program/Abstract # 329 SMA-9/Schnurri function and its target genes Jianghua Yin, Ling Yu, Cathy Savage-Dunn Biology Department, Queens College at CUNY, Flushing, NY, USA BMP/TGFβ signaling regulates many aspects of development and differentiation in both vertebrates and invertebrates. One way that different outcomes are fulfilled is by different transcription cofactors recruited by Smad complexes. In Drosophila Dpp signaling, the Mad/Med 566 ABSTRACTS / Developmental Biology 319 (2008) 565–575