Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Cell and Developmental Biology." Includes bibliographical references (p. 108-125).

Thesis (Ph. D.)--Rutgers University, 2008. / "Graduate Program in Cell and Developmental Biology." Includes bibliographical references (p. 102-115).

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 79-82). Also available in electronic version.

Placental dysfunction affects approximately 1 in 10 pregnant women in both the developed and developing worlds. Most commonly, it is manifested as preeclampsia or fetal growth restriction. Over the past two decades, an increasing body of research into the developmental biology of the placenta has been amassed, which points to defects in the differentiation of the trophoblast cell lineage as a key player in the pathophysiology of placental dysfunction. A number of clinical parameters are known to be associated with an elevated risk of placental dysfunction. These include maternal risk factors (such as chronic hypertension, renal disease, and lupus), history of placental dysfunction in a prior pregnancy, abnormalities in the levels of certain proteins in the maternal blood that are commonly used to estimate the risk of fetal genetic defects, and abnormalities in uterine artery Doppler waveforms. These current methods have significant drawbacks, including low specificity and sensitivity, high cost, lack of widespread availability, and lack of validity early in pregnancy. In order to provide a more cost-effective and reliable method to detect an elevated risk for placental dysfunction early in pregnancy, we explored the potential for extracellular RNAs (exRNA) in the maternal serum to be used as biomarkers. In our study, we used next generation sequencing technologies to compare extracellular microRNA (miRNA) levels in serum samples of pregnant women of different gestational ages, nonpregnant women, and placental tissue samples. We discovered that the large majority of microRNAs that were present at higher levels in pregnant serum samples than nonpregnant serum samples and were likely of placental origin. We also found that these pregnancy-specific miRNAs were enriched for miRNAs encoded on chromosomes (Chr) 14 and 19, with changes in the relative expression of these two groups of miRNAs throughout pregnancy. Moreover, the miRNA signatures of late gestational pregnant samples correlated more closely with placental tissue samples than those of early pregnant samples, which could be related to the increasing impact of a larger placenta on the maternal serum exRNA profile. Our results demonstrate the potential utility of next generation sequencing technologies in regards to differentiating between different conditions using clinical samples.

Life histories unfold within the ecological context of an organism's environment, and thus are intimately linked to organismal fitness. The evolution of alternate life history strategies, either within or between taxa, can profoundly affect ontogeny, ecology, and population dynamics. Many cnidarians (sea anemones, corals, jellyfish, etc.) exhibit complex life histories involving sexual reproduction and multiple modes of asexual reproduction. Sea anemones of the family Edwardsiidae exemplify this complexity, and are therefore an attractive system for studying the developmental and ecological ramifications of life history evolution. I used intra- and interspecific comparisons of two Edwardsiid anemones, Edwardsiella lineata, and Nematostella vectensis to investigate alternative life histories using a multifaceted approach that included field-based ecological surveys, functional genetics, transcriptomics, and phylogenetics. Both anemones are capable of sexual and asexual reproduction. N. vectensis produces a rapidly maturing direct developing larva. By contrast, E. lineata has evolved a new larval stage that parasitizes the ctenophore, Mnemiopsis leidyi. Through fieldwork surveys and laboratory culture, I documented several life history traits, such as a previously un-characterized, pre-parasitic larval stage, and the developmental dynamics of early-stage parasitic infections, that augmented gaps in our knowledge of E. lineata's life history. To better understand how and when E. lineata evolved its novel, parasitic life history, I worked with collaborators in the Finnerty lab to sequence, assemble and annotate the transcriptome. Through a multigene molecular clock approach, enabled by the E. lineata transcriptome assembly, I estimated the divergence date for these two anemones between 215-364 million years ago, thereby establishing an upper bound for the innovation of E. lineata's derived, parasitic life history. Testing a hypothesis that Wnt signaling, which patterns the oral-aboral (OA) axis during embryogenesis, also patterns the OA axis during regeneration, I demonstrated that canonical Wnt signaling is sufficient for oral tissue fate across alternate life histories (embryogenesis and regeneration) of N. vectensis. Taken together, these dissertation research activities constitute an integrative approach to investigating the evolution of life histories, and are a step towards establishing E. lineata and N. vectensis as models for studying the evolutionary developmental mechanisms of parasitism and regeneration.

Elucidating the molecular events that integrate the patterning, morphogenesis, and differentiation of epithelial progenitor cells into complex tissues is a primary focus of epithelial developmental biology research. Expansion and maintenance of epithelial progenitor populations is crucial for developmental events, but growth must be tightly coupled to consequent cellular differentiation and specialization. The Hippo pathway has surfaced as an important regulator of epithelial progenitor identity: nuclear activity of the Hippo effector Yap maintains epithelial progenitor status while Hippo-mediated nuclear exclusion of Yap by the Lats1/2 kinases induces differentiation. Extending this general theme into an additional organ system, the submandibular gland (SMG), as well as identifying upstream regulators of Yap and Lats1/2 in the developing lung was the goal of this work. Here, we describe important roles for Yap in the morphogenesis and patterning of lung and SMG epithelium, both of which are composed of highly organized branched structures. Epithelial-specific genetic ablation of Yap as well as its upstream negative regulators Lats1/2 was used to interrogate loss- and gain-of-function phenotypes, whereby Lats1/2 ablation is known to result in unrestricted nuclear Yap activity. Loss of Yap in the SMG resulted in a striking deficiency of Krt5/Krt14-positive epithelial progenitor populations accompanied by impaired branching morphogenesis. Deletion of Lats1/2 in the SMG resulted in a massive expansion of Krt5/Krt14-positive epithelial progenitor populations that failed to terminally differentiate. As epithelial progenitors in the lung and SMG begin to differentiate, they also acquire distinct morphologies. In both the lung and the SMG, Krt5-positive basal cells lie beneath a layer of Krt8/Krt19-positive luminal cells. We observed that luminal cells exhibited a columnar morphology while basal cells retained a cuboidal morphology, and that this difference correlated with the expression of the polarity protein Crb3. After ablating Crb3 in the developing lung epithelium, luminal cells were unable to polarize, exhibited aberrant nuclear Yap activity, and remained in a progenitor state. Crb3 functions to initiate Lats1/2 activity, promoting Yap phosphorylation and its consequent nuclear exclusion, which drives differentiation. Taken together, this work identifies essential roles for polarity/Hippo pathway-mediated control of Yap activity in epithelial progenitor expansion and differentiation. / 2018-07-09T00:00:00Z

BACKGROUND: Orthodontists rely heavily on cephalometric analysis to assess growth potential and direction. Geometric morphometrics examines shape and can help the clinician reach more accurate diagnoses and predict future growth. PURPOSE: The aims of this study are: 1) Determine principle components describing craniofacial shape changes; 2) Assess shape changes in growing subjects; 3) Develop a model for craniofacial growth prediction using geometric morphometrics. RESEARCH DESIGN: The Cranial base, maxilla and mandible were digitized on 330 lateral cephalograms from ages 6-16 (n=33). Generalized Procrustes analysis was performed on the longitudinal data sample. Principle Component, Discriminant Function and Two-Block Partial Least Squares analysis were assessed against changes in individual structures to determine if changes in the maxillary, mandibular or cranial base are related to changes in shape of the overall craniofacial form. RESULTS: PCA shows that the first six principle components account for 67.7 – 77.0% of the observed shape variance in each region and 56.0% of the whole form. Multivariate regression analysis predicts the shape of the entire craniofacial complex at 16 years old based on the shape observed at 6 years old with 94% certainty. An intraclass correlation coefficient of 0.98 confirms reliability. CONCLUSION: Morphometric analyses indicate that changes in maxillofacial morphology during skeletal maturation are linear. The shape of the craniofacial complex does not change significantly and growth pattern is maintained. Our model can predict the craniofacial shape at 16 years of age based on the shape observed at 6 years of age.

Successful mammalian development to term requires that embryonic and extra-embryonic tissues communicate and grow in coordination, to form the body. After implanting into the uterus, the mouse embryo is comprised of three cell lineages: first, the embryonic epiblast (EPI) that forms the embryo proper, second, the extra-embryonic ectoderm (ExE) which contributes to the foetal portion of the placenta, and third, the visceral endoderm (VE) that contributes to the yolk sac. These three tissues form a characteristic ‘egg-cylinder’ structure, which allows signals to be exchanged between them and sets the stage for body axis establishment and subsequent tissue patterning. The mechanisms underlying this process are difficult to study in vivo because a different genetically manipulated mouse line must be generated to investigate each factor involved. This difficulty has prompted efforts to model mammalian embryogenesis in vitro, using cell lines, which are more amenable to genetic manipulation. The pluripotent state of the EPI can be captured in vitro as mammalian embryonic stem cells (ESCs). Although mouse ESCs have been shown to contribute to all adult tissues in chimeric embryos, they cannot undertake embryogenesis when allowed to differentiate in culture. Previous studies have shown that ESCs formed into three-dimensional (3D) aggregates, called embryoid bodies, can become patterned and express genes associated with early tissue differentiation. However, embryoid bodies cannot recapitulate embryonic architecture and therefore may not accurately reflect what happens in the embryo. In this study, a new technique was developed to model early mouse development which is more faithful to the embryo. ESCs were co-cultured with stem cells derived from the ExE, termed trophoblast stem cells (TSCs), embedded within extracellular matrix (ECM). These culture conditions lead to the self-assembly of embryo-like structures with similar architecture to the mouse egg cylinder. They were comprised of an embryonic compartment derived from ESCs abutting an extra-embryonic compartment derived from TSCs, and hence were named ‘ETS-embryos’. These structures developed a continuous cavity at their centre, which formed via a similar sequence of events to those that lead to pro-amniotic cavity formation in the mouse embryo, and required active Nodal/Activin signalling. After cavitation, ‘ETS-embryos’ developed regionalised mesodermal tissue and primordial germ cell-like cells originating at the boundary between embryonic and extra-embryonic compartments. Inhibitor studies revealed that this occurred in response to endogenous Wnt and BMP signalling, pathways which also govern these tissue specification events in the early mouse embryo. To demonstrate that ‘ETS-embryos’ were comparable to mouse embryos at the global transcriptional level, RNA-sequencing was then performed on different tissue regions of ‘ETS-embryos’ and the resulting transcriptomes were compared to datasets from mouse embryos. These data showed that ‘ETS-embryos’ were highly similar to mouse embryos at post-implantation stages in their overall gene expression patterns. Taken together, these results indicate that ‘ETS-embryos’ are an accurate in vitro model of mammalian embryogenesis, which can be used to complement studies undertaken in vivo to investigate early development.

abstract: Skeletal muscles arise from the myotome compartment of the somites that form during vertebrate embryonic development. Somites are transient structures serve as the anlagen for the axial skeleton, skeletal muscle, tendons, and dermis, as well as imposing the metameric patterning of the axial musculoskeletal system, peripheral nerves, and vasculature. Classic studies have described the role of Notch, Wnt, and FGF signaling pathways in controlling somite formation and muscle formation. However, little is known about the transformation of myotome compartments into identifiable post-natal muscle groups. Using a mouse model, I have undertaken an evaluation of morphological events, including hypertrophy and hyperplasia, related to the formation of several muscles positioned along the dorsal surface of the vertebrae and ribs. Lunatic fringe (Lfng) deficient embryos and neonates were also examined to further understand the role of the Notch pathway in these processes as it is a modulator of the Notch receptor and plays an important role in defining somite borders and anterior-posterior patterning in many vertebrates. Lunatic fringe deficient embryos showed defects in muscle fiber hyperplasia and hypertrophy in the iliocostalis and longissimus muscles of the erector spinae group. This novel data suggests an additional role for Lfng and the Notch signaling pathway in embryonic and fetal muscle development. / Dissertation/Thesis / M.S. Biology 2012

viii, 54 leaves : ill. ; 28 cm Notes Typescript Thesis (M.S.)--University of Oregon, 1985 Includes vita and abstract Bibliography: leaves 52-54 Another copy on microfilm is located in Archives