**6. Glossary**

94 Bacterial Artificial Chromosomes

why prognosis for patients with malignant pancreatic tumors have not entirely improved over the past twenty years (Jemal, Siegel et al. 2006). Moore et al have discovered that the zebrafish develop pancreatic cancer after exposure to chemical mutagens (Moore, Rush et al. 2006). The studies have also shown that mammalian and zebrafish pancreas are significantly similar in anatomy and histology (Wallace and Pack 2003; Chen, Li et al. 2007). Therefore, the Zebrafish has emerged as an experimental model for study of human pancreatic cancer biology (Davison, Woo Park et al. 2008; Park, Davison et al. 2008). Another benefits of working with zebrafish model is their translucency, which greatly improves the visualization of fluorescent trangenes in both embryos and adult zebrafish (Davison, Woo Park et al. 2008). Park et al (Park, Davison et al. 2008) discovered that oncogenic Kras causes pancreatic cell expansion and malignant transformation in the zebrafish exocrine pancreas by utilizing eGFP-Kras BAC transgenes (160kb) under the regulation of Ptf1a regulatory elements. Ptf1a induces differentiation, growth and proliferation of pancreatic progenitor cells (Park, Davison et al. 2008). Briefly, they expressed either extended green fluorescent protein (eGFP) alone or eGFP fused to oncogenic Kras in developing zebrafish pancreas and continuously detected the expression of fluorescent transgenes transcutaneously during all stages of development including the adult zebrafish. They first generated polymerase chain reaction (PCR) products encoding the eGFP and eGFP-Kras transgenes flanked by sequences homologous to the CH211-142 BAC that spans the Pfta1 gene locus. Homologous recombination leads to accurate replacement of the Ptf1a coding sequences with the eGFP and eGFP-Kras transgene (Davison, Woo Park et al. 2008). Their results demonstrate that oncogenic Kras-expressed pancreatic progenitor cells fail to undergo characteristic exocrine differentiation although their initial specification and migration are observed to be normal (Davison, Woo Park et al. 2008; Park, Davison et al. 2008). Blocks of differentiation leads to abnormal accumulation of the undifferentiated progenitor cells, correlates with the formation of invasive pancreatic cancer. Besides similarity in anatomy and histology, Zebrafish pancreatic tumors share several activated signaling pathways with the human pancreatic tumors, including activation of ERK and AKTby phosphorylation, as well as abnormal Hedgehog pathway activation which was justified by the up-regulation of ptc1 mRNA and gli1 mRNA (Park, Davison et al. 2008). These findings provide a unique view of the tumor-initiating effects of oncogenic Kras in a living vertebrate organism, but more important it suggest that BACs transgene targeting other oncogenes or tumor suppressor genes in zebrafish pancreatic cancer may improve our understanding of the human disease.

**3.6 Studies on striatal signaling pathways in central nervous system (CNS) with BACs**  To understand the role of molecular signaling pathways involved in behavioral responses, it is necessary to delineate the molecular events that take place in neurons. This task has been hampered by the complexity of neuronal system. There are hundreds of distinct neuronal populations and these populations are very difficult to distinguish (Valjent, Bertran-Gonzalez et al. 2009). The development of BAC transgenic mice expressing various reporters, epitope tagged-proteins or Cre recombinase driven by specific promoters, greatly facilitates the research in this field. Generally speaking, transgene expression is influenced by copy numbers and site of insertions (positional effects). Large BAC transgenes (BACs contain large fragments 150-200kb of mouse genome) have usually a low copy number, are less likely influenced by positional effects, and are able to recapitulate the regulation of endogenous genes much better than shorter transgenes (Yang, Model et al. 1997). Over the past few years, the use of BAC EGFP transgenic mice have generated significant

aCGH: array-based comparative genomic hybridization BACs: bacterial artificial chromosome BHV-1: bovine herpesvirus Type 1 CGH: comparative genomic hybridization CHRM4: cholinergic receptor, muscarinic 4- receptor CMV: cytomegalovirus CNAs: copy number changes CNS: central nervous system

D1R: dopamine D1 receptor D2R: dopamine D2 receptor ECs: endothelial cells eGFP: extended green fluorescent protein EHV-1: Equine herpesvirus Type 1 FFPE: archival formalin-fixed, paraffin-embedded FHV-1: Feline herpesvirus FISH: fluorescence in situ hybridization F-plasmid: a fertility plasmid GPCMV: Guinea pig cytomegalovirus HCMV or HHV-5: human cytomegalovirus HFF: human foreskin fibroblasts HLA: human leukocyte antigen HSV-1: Herpes simples virus type 1 HSV-2: Herpes simples virus type 2 HUVECs: human umbilical vein endothelial cells HVS: herpesvirus saimiri HVT: Turkery herpesvirus HPV: herpesviruses Ifng: interferon-γ KHV: Koi herpesvirus KSHV or HHV-8: Kaposi's sarcoma-associated herpesvirus, LCV: lymphocryptovirus MDV: Marek's disease virus mECK36 cells: mouse bone marrow endothelial cells generated by transfection of with KSHVBac36 MSNs: medium spiny projection neurons VEGF: vascular endothelial growth factor vGPCR: viral G protein-coupled receptor VZV or HHV-3: varicella-zoster virus, KSHVBac36: KSHV bacterial artificial chromosome, mCMV: murine gammaherpesvirus MHV-68: Murine cytomegalovirus 68 ORFs: open reading frames PCR: polymerase chain reaction PrV: pseudorabies virus rhCMV: Rhesus cytomegalovirus RRV: rhesus rhadinovirus TMA: tissue microarray
