Developmental Biology Commons^™

Study Of Rest As A Negative Regulator Of P16ink4a, Monica B. Gireud

Dissertations and Theses (Open Access)

STUDY OF REST AS A NEGATIVE REGULATOR OF P16^INK4A

Monica Gireud, B.S.

Thesis Advisor: Vidya Gopalakrishnan, Ph.D.

The RE1 Silencing Transcription Factor (REST) is a negative regulator of neuronal differentiation. It is expressed ubiquitously in early embryos, but downregulated in neural progenitors concomitant with onset of neuronal differentiation in these cells. REST has been widely studied as a negative regulator of neuronal differentiation genes. Our recent work identified a novel role for REST in control of cell proliferation. However, the underlying molecular mechanism(s) are not known and is a focus of the current thesis project. Here, we provide evidence …

Rho Kinase Regulates Basement Membrane Dynamics To Coordinate Salivary Gland Branching Morphogenesis And Tissue Organization, William Patrick Daley

Legacy Theses & Dissertations (2009 - 2024)

Branching morphogenesis is a developmental mechanism utilized by many organs, including the salivary gland, lung, kidney, and mammary gland, to increase the epithelial surface area for secretion or absorption. The embryonic submandibular salivary gland (SMG) is a classic model for studying tissue morphogenesis in three dimensions ex vivo. Salivary gland development requires distinct but overlapping processes: morphogenesis, the actual physical rearrangement of cells into complex three dimensional structures, and cytodifferentiation, the process by which these cells begin to take on their own specialized function. Polarization, or the organization of cells into a cohesive tissue structure, also occurs concurrently during organ …

Repression Of Wnt Signaling By A Fer-Type Nonreceptor Tyrosine Kinase, Aaron P. Putzke

Biology Faculty Scholarship

The Wnt signaling pathway must be properly modulated to ensure an appropriate output: pathological conditions result from either insufficient or excessive levels of Wnt signal. For example, hyperactivation of the Wnt pathway is associated with various cancers and subnormal Wnt signaling can lead to increased invasiveness of tumor cells. We found that the Caenorhabditis elegans ortholog of the Fer nonreceptor tyrosine kinase, FRK-1, limits Wnt signaling by preventing the adhesion complex-associated β-catenin, HMP-2, from participating in Wnt-dependent specification of the endoderm during embryogenesis. Removal of FRK-1 function results in relocalization of HMP-2 to the nucleus of epidermal cells, and allows …

Assessing The Phylogenetic Utility Of Dna Barcoding Using The New Zealand Cicada Genus Kikihia, Megan Ribak

Honors Scholar Theses

DNA Barcoding (Hebert et al. 2003) has the potential to revolutionize the process of identifying and cataloguing biodiversity; however, significant controversy surrounds some of the proposed applications. In the seven years since DNA barcoding was introduced, the Web of Science records more than 600 studies that have weighed the pros and cons of this procedure. Unfortunately, the scientific community has been unable to come to any consensus on what threshold to use to differentiate species or even whether the barcoding region provides enough information to serve as an accurate species identification tool. The purpose of my thesis is to analyze …

The Consequences Of Disrupting The Mdm2-P53 Balance In Hematopoiesis, Hussein A. Abbas

Dissertations and Theses (Open Access)

The bone marrow accommodates hematopoietic stem cells and progenitors. These cells provide an indispensible resource for replenishing the blood constituents throughout an organism’s life. A tissue with such a high turn-over rate mandates intact cycling checkpoint and apoptotic pathways to avoid inappropriate cell proliferation and ultimately the development of leukemias. p53, a major tumor suppressor, is a transcription factor that regulates cell cycle, and induces apoptosis and senescence. Mice inheriting a hypomorphic p53 allele in the absence of Mdm2, a p53 inhibitor, have elevated p53 cell cycle activity and die by postnatal day 13 due to hematopoietic failure. Hematopoiesis progresses …

Temporal Regulation Of The Muscle Gene Cascade By Macho1 And Tbx6 Transcription Factors In Ciona Intestinalis, Jamie E. Kugler, Stefan Gazdoiu, Izumi Oda-Ishii, Yale J. Passamaneck, Albert J. Erives, Anna Di Gregorio

Dartmouth Scholarship

For over a century, muscle formation in the ascidian embryo has been representative of 'mosaic' development. The molecular basis of muscle-fate predetermination has been partly elucidated with the discovery of Macho1, a maternal zinc-finger transcription factor necessary and sufficient for primary muscle development, and of its transcriptional intermediaries Tbx6b and Tbx6c. However, the molecular mechanisms by which the maternal information is decoded by cis-regulatory modules (CRMs) associated with muscle transcription factor and structural genes, and the ways by which a seamless transition from maternal to zygotic transcription is ensured, are still mostly unclear. By combining misexpression assays with CRM analyses, …

Dissolved Organic Matter Influences The Timing Of Embryonic Development Of The Purple Sea Urchin, Strongylocentrotus Purpuratus., Corbin J. Hodges

Master's Theses

Marine dissolved organic matter (DOM) comprises one of the largest carbon reservoirs on earth and has long been considered a potential energy source for marine invertebrates. The importance of DOM transport has been adequately demonstrated for unicellular organisms, where DOM can meet 100% of an organisms energy needs, but the effects of DOM uptake for marine metazoans are less well understood. In this study, three general areas involving the influence of DOM transport to marine invertebrates were explored. First, we assessed the effects of using seawater exposed to high intensity ultraviolet radiation (UVR) on the study organism; embryos of the …

Phylogeography Of The Frog Leptodactylus Validus (Amphibia: Anura): Patterns And Timing Of Colonization Events In The Lesser Antilles, Arley Camargo, W. Ronald Heyer, Rafael O. De Sá

Biology Faculty Publications

The frog Leptodactylus validus occurs in northern South America, Trinidad and Tobago, and the southern Lesser Antilles (Grenada and St. Vincent). Mitochondrial DNA sequences were used to perform a nested clade phylogeographic analysis (NCPA), to date colonization events, and to analyze colonization patterns using on a relaxed molecular clock and coalescent simulations. L. validus originated on the mainland and first colonized Trinidad with subsequent independent colonizations of Tobago and the Lesser Antilles from Trinidad. The NCPA suggests a historical vicariant event between populations in Trinidad and Tobago from those in the Lesser Antilles. The colonization of Trinidad occurred 1 million …

In Vivo Analysis Of The Notch Receptor S1 Cleavage, Robert J. Lake, Lisa M. Grimm, Alexey Veraksa, Spyros Artavanis-Tsakonas

Biology Faculty Publication Series

A ligand-independent cleavage (S1) in the extracellular domain of the mammalian Notch receptor results in what is considered to be the canonical heterodimeric form of Notch on the cell surface. The in vivo consequences and significance of this cleavage on Drosophila Notch signaling remain unclear and contradictory. We determined the cleavage site in Drosophila and examined its in vivo function by a transgenic analysis of receptors that cannot be cleaved. Our results demonstrate a correlation between loss of cleavage and loss of in vivo function of the Notch receptor, supporting the notion that S1 cleavage is an in vivo mechanism …

Exposure To Ultraviolet Radiation Causes Proteomic Changes In Embryos Of The Purple Sea Urchin, Strongylocentrotus Purpuratus, Joseph Paul Campanale

Master's Theses

The amount of solar ultraviolet radiation (UVR, 290-400 nm) reaching Earth’s surface is increasing due to ozone depletion and global climate change. Embryos of the purple sea urchin, Strongylocentrotus purpuratus, provide an ideal system for examining how UVR affects developing marine organisms and cells in general. To model the protein-mediated cell cycle response to UV-irradiation, six batches of S. purpuratus embryos were exposed to UVR, monitored for delays in the first mitotic division and examined for global proteomic changes. Embryos from each batch were exposed to or protected from artificial UVR for 25 or 60 min. Embryos treated with …

Is The Amphibian Tree Of Life Really Fatally Flawed?, Darrel R. Frost, Taran Grant, Julian Faivovich, Raoul H. Bain, Alexander Haas, Celio F.B. Haddad, Rafael O. De Sá, Et Al.

Biology Faculty Publications

Wiens (2007, Q. Rev. Biol. 82, 55–56) recently published a severe critique of Frost et al.'s (2006, Bull. Am. Mus. Nat. Hist. 297, 1–370) monographic study of amphibian systematics, concluding that it is “a disaster” and recommending that readers “simply ignore this study”. Beyond the hyperbole, Wiens raised four general objections that he regarded as “fatal flaws”: (1) the sampling design was insufficient for the generic changes made and taxonomic changes were made without including all type species; (2) the nuclear gene most commonly used in amphibian phylogenetics, RAG-1, was not included, nor were the morphological characters that had justified …

Effects Of Calcium Availability On The Reproductive Output Of Insectivorous Bats, Christina M. Booher

All-Inclusive List of Electronic Theses and Dissertations

Reproduction is a period of high calcium demand in vertebrates, and calcium deficiency can limit reproductive output in mammals. Insects are a poor calcium source, suggesting that insectivorous species are more likely to be calcium deficient. Pregnant big brown bats (Eptesicus fuscus) consume 10 times less calcium than they are estimated to require. To accommodate calcium demand during pregnancy, many mammals mobilize more calcium from the skeleton, and extensive bone loss has been observed in some bats during pregnancy. A conflict may arise between the female and developing embryo over allocation of limited calcium supplies, which could limit reproductive output …

Stoichiometric Controls Of Mercury Dilution By Growth, Roxanne Karimi, Celia Y. Chen, Paul C. Pickhardt, Nicholas S. Fisher, Carol L. Folt

Dartmouth Scholarship

Rapid growth could significantly reduce methylmercury (MeHg) concentrations in aquatic organisms by causing a greater than proportional gain in biomass relative to MeHg (somatic growth dilution). We hypothesized that rapid growth from the consumption of high-quality algae, defined by algal nutrient stoichiometry, reduces MeHg concentrations in zooplankton, a major source of MeHg for lake fish. Using a MeHg radiotracer, we measured changes in MeHg concentrations, growth and ingestion rates in juvenile Daphnia pulex fed either high (C:P = 139) or low-quality (C:P = 1317) algae (Ankistrodesmus falcatus) for 5 d. We estimated Daphnia steady-state MeHg concentrations, using a …

Rapid Assimilation Of Yolk Enhances Growth And Development Of Lizard Embryos From A Cold Environment, Melissa Ann Blake

All-Inclusive List of Electronic Theses and Dissertations

Selection for rapid growth in cold environments results in a geographic pattern known as countergradient variation. The eastern fence lizard, Sceloporus undulatus, exhibits countergradient variation in growth rate across latitudinal clines. In a common-garden experiment, S. undulatus embryos from cold environments grew more efficiently than embryos warm environments, even when the energetic contents of eggs were equalized. To examine the physiological mechanisms of higher growth efficiency, I measured the energetics of embryos during the first 49 days of incubation. Specifically, I recorded body mass, residual yolk, total respiration, and developmental stage for embyos from two populations (Virginia and South Carolina). …

Phylogenetic Analyses Of Mtdna Sequences Reveal Three Cryptic Lineages In The Widespread Neotropical Frog Leptodactylus Fuscus (Schneider, 1799) (Anura, Leptodactylidae), Arley Camargo, Rafael O. De Sá, W. Ronald Heyer

Biology Faculty Publications

Leptodactylus fuscus is a neotropical frog ranging from Panamá to Argentina, to the east of the Andes mountains, and also inhabiting Margarita, Trinidad, and the Tobago islands. We performed phylogenetic analyses of 12S rRNA, 16S rRNA, tRNA-Leu, and ND1 mitochondrial (mt) DNA sequences from specimens collected across the geographic distribution of L. fuscus to examine two alternative hypotheses: (i) L. fuscus is a single, widely distributed species, or (ii) L. fuscus is a species complex. We tested statistically for geographic association and partitioning of genetic variation among mtDNA clades. The mtDNA data supported the hypothesis of several cryptic species within …

Skeletal Myosin Heavy Chain Function In Cultured Lung Myofibroblasts, Nancy A. Rice, Leslie A. Leinwand

Biology Faculty Publications

Myofibroblasts are unique contractile cells with both muscle and nonmuscle properties. Typically myofibroblasts are identified by the expression of smooth muscle actin (ASMA); however some myofibroblasts also express sarcomeric proteins. In this study, we show that pulmonary myofibroblasts express three of the eight known sarcomeric myosin heavy chains (MyHCs) (IIa, IId, and embryonic) and that skeletal muscle myosin enzymatic activity is required for pulmonary myofibroblast contractility. Furthermore, inhibition of skeletal myosin activity and myofibroblast contraction results in a decrease in both ASMA and skeletal MyHC promoter activity and ASMA protein expression, suggesting a potential coupling of skeletal myosin activity and …

In Vivo Effect Of Leukemia Inhibitory Factor (Lif) And An Anti-Lif Polyclonal Antibody On Murine Embryo And Fetal Development Following Exposure At The Time Of Transcervical Blastocyst Transfer, Michael H. Mitchell, R. James Swanson, Sergio Oehninger

Biological Sciences Faculty Publications

Leukemia inhibitory factor (LIF) enhances in vitro murine preimplantation development in a time- and dose-dependent fashion. Knockout experiments have demonstrated that endometrial LIF is essential for in vivo murine implantation. We assessed the impact of LIF and an anti-LIF polyclonal antibody (pab) on in vivo development and developed a novel and successful nonsurgical method of embryo transfer for this species, a transcervical blastocyst transfer technique. The objectives of this study were to evaluate the effects of LIF and the anti-LIF pab on 1) implantation, resorption, pregnancy, and viability rates and 2) the overall structural and skeletal development. Two-cell embryos were …

The Wings Of Bombyx Mori Develop From Larval Discs Exhibiting An Early Differentiated State: A Preliminary Report, Madhuri Kango-Singh, Amit Singh, K. P. Gopinathan

Biology Faculty Publications

Lepidopteran insects present a complex organization of appendages which develop by various mechanisms. In the mulberry silkworm, Bombyx mori, a pair of meso- and meta-thoracic discs located on either side in the larvae gives rise to the corresponding fore- and hind-wings of the adult. These discs do not experience massive cell rearrangements during metamorphosis and display the adult wing vein pattern. We have analysed wing development in B. mori by two approaches, viz., expression of patterning genes in larval wing discs, and regulatory capacities of larval discs following explantation or perturbation. Expression of Nubbin is seen all over the presumptive …

Analysis Of E. Coli Dna From Selected Source(S) Using Pulsed-Field Gel Electrophoresis, Sheema Doshi

Theses, Dissertations and Capstones

The presence of fecal coliforms in surface waters is a public health issue throughout the United States and Canada. The presence of Escherichia coli (E. coli) indicates recent fecal contamination from either animal or human sources. To solve this growing problem one must identify the source(s) of such contamination by creating a database of DNA profiles of£. coli isolates. Hence, tracking the source(s) of E. coli can help link water contamination to animal source(s) of contamination. In this study, pulsed field gel electrophoresis (PFGE) was used to analyze DNA from E. coli isolates from known animals. For PFGE, the bacterial …

Factors Influencing Spatial Variability In Soil Nitrogen (N) Dynamics In N-Treated And Untreated Watersheds Of The Fernow Experimental Forest, West Virginia, Nikki Lenore Lyttle

Theses, Dissertations and Capstones

The central Appalachian region of the United States receives some of the highest inputs of nitrogen (N) due to acidic deposition in the nation. It is believed that these high could levels contribute to a decline in forest soils within the next 50 to 70 yrs. This study examines factors that influence spatial variability in N-treated and untreated watersheds of the Fernow Experimental Forest, Parsons, West Virginia. Within each of the two watersheds [WS4 untreated control, > 100 yr.; WS3 N-treated, acidified, clear cut, ~ 31 yr.], two 0.04 ha plots, one high N and one low N, were selected for …

Chondrocranium And Visceral Skeleton Of Atelopus Tricolor And Atelophryniscus Chrysophorus, E O. Lavilla, Rafael O. De Sá

Biology Faculty Publications

Atelopus tricolor and Atelophryniscus chrysophorus have gastromyzophorous tadpoles. Aside from specific differences, the larval chondrocrania and visceral skeletons show several shared character states, including an almost quadrangular, open chondrocranium , cornua trabeculae with expanded tips, cartilago suprarostralis as a single element, a posteriorly projected arcus subocularis quadrati, a closed muscular tunnel, and a simplified branchial basket, with only three pairs of ceratobranchiales. They are compared with diverse character states of suctorial larvae considering them as causally related to the stream life adaptations.

Do Timing And Pattern Of Myogenesis Correlate With Life History Mode In Anurans?, Matthew T. Smetanick, Rafael O. De Sá, Gary P. Radice

Biology Faculty Publications

The timing and pattern of myogenesis varies among anurans that have been studied and the different pat- terns may provide useful phylogenetic information. Specific myogenic markers have been described (Muntz, 1975; Kielbowna, 1981; Boudjelida & Muntz, 1987; Radice et al., 1989) and they can provide infor- mation on evolutionary changes for closely related lineages within a clade. For example, we previously com- pared first appearance of a muscle-specific protein, first twitch of axial muscle, onset of multinucleation within axial myotome, and first heartbeat in two pipid genera (Smetanick et al., 1999). We found that although the timing of myogenesis differed, …

The Life History Of The Cave Salamander, Eurycea Lucifuga Rafinesque, In West Virginia, Andrew James Longenecker

Theses, Dissertations and Capstones

In West Virginia, as throughout its range, there is limited information about the life history of the cave salamander (Eurycea lucifuga). The purpose of this study was to describe the natural history of this species in West Virginia. The objectives of this study were to determine habitat selection of the cave salamander, to ascertain its environmental characteristics, and to study its reproductive and non-reproductive biology. Three study caves were located in Greenbrier County, West Virginia. All sites were examined at least once each month from May 1999 through April 2000. Caves were divided into three zones: entrance, twilight, …

Ecology And Sympatric Relations Of Crevice Salamanders In Randolph County, West Virginia, Jayme Linn Waldron

Theses, Dissertations and Capstones

By implementing a mark-recapture study, I investigated the ecology of three species of sympatric plethodontid salamanders (Aneides aeneus, Desmognathus ochrophaeus, and Plethodon glutinosus) on rock outcrops in the Westvaco Wildlife and Ecosystem Research Forest, Randolph County, West Virginia. By examining activity patterns, vertical stratification, and habitat preference for A. aeneus, D. ochrophaeus, and P. glutinosus, I attempted to offer some insight into how these sympatric species avoid competition on small, isolated rock outcrops. Twenty-one surveys, both nocturnal and diurnal, were performed between 11 May and 17 October, 1999. During this time, 89 salamanders, encompassing five species ( …

Estructura Del Condrocráneo Y Esqueleto Visceral De Larvas De Pseudis Minuta (Anura, Pseudidae, E. O. Lavilla, Rafael O. De Sá

Biology Faculty Publications

The chondrocranium and visceral skeleton of Pseudis minuta tadpoles are described, based on a series of five larvae in stages 31 - 35 of Gosner (1960). Among their striking characters are the presence of peculiar articular surfaces between cornua trabeculae and suprarostral cartilage, the incomplete development of the orbital cartilage, the high fenestration of the floor of the cavum cranii, the fusion of posterior foramina, and the fusion of spicules 3 and 4 in the hyobranchial skeleton.

Development Of The Suprarostral Plate Of Pipoid Frogs, Rafael O. De Sá, Charles C. Swart

Biology Faculty Publications

The rostral region of nonpipoid tadpoles has two sets of cartilages, the cornua trabeculae and the suprarostral cartilages, whereas the rostral region in pipoid larvae is occupied by a single and continuous cartilage, the suprarostral plate. The homology of this region in pipoid and nonpipoids tadpoles has been controversial. We examined the early formation and development of the suprarostral plate using serially cross-sectioned specimens of Rhinophrynus, Xenopus, and Hymenochirus. We conclude that the cartilaginous structures present in the rostral area of pipoid and nonpipoid larvae are homologous. Furthermore, we found two different developmental patterns among pipoid larvae. The chondrocranium …

Clarification Of The Hybrid Origin Of Carex X Deamii Herm. (Cyperaceae) Based On Macro And Micro Morphological Characters, Paul B. Marcum

Theses, Dissertations and Capstones

The origin of Carex x deamii Herm. has been in question ever since it was named to science in 1938. Collections of the hybrid have always been associated with C. shortiana Dewey and either C. typhina Michx. or C. squarrosa L.. C. typhina and C. squarrosa are closely related taxa (Section Squarrosae) and often are morphologically similar. Because of this similarity, determining the correct parental species to the hybrid has been extremely difficult. It is known that the hybrid is sterile and only reproduces asexually. Pollen was analyzed to ascertain the viability of all four taxa. This study utilizes both …

The Biology Of Xenopus By R. C. Tinsley And H. C. Kobel, Rafael O. De Sá

Biology Faculty Publications

The Biology of Xenopus presents a summary of current knowledge about a single genus resulting from a symposium held at the Zoological Society of London in September 1992. This approach to summarizing available information has also been taken for other taxa, such as Atelopus (Lotters, 1996). However, the task of compiling data for Xenopus is enormous relative to any other amphibian group, because Xenopus laevis has become a model system for molecular and development research (Cannatella and de Sa, 1993). Unfortunately, most of our knowledge of Xenopus is biased toward this single species. There are about 20 recognized species of …

Chondrocranial Morphology Of Leptodactylus Larvae (Leptodactylidae: Leptodactylinae): Its Utility In Phylogenetic Reconstruction, Peter M. Larson, Rafael O. De Sá

Biology Faculty Publications

Chondrocranial morphology of leptodactylid frogs is scarcely known and has not been completely described for any species of Leptodactylus. We describe the diversity of chondrocranial morphology in the genus Leptodactylus based on the analysis of 22 species, representing the four species groups: the fuscus Group, ocellatus Group, melanonotus Group, and pentadactylus Group. Furthermore, 26 characters are identified and used in a phylogenetic analysis. The phylogenetic analysis using Physalaemus, Crossodactylus, and Hylodes as outgroups suggests two monophyletic clades within Leptodactylus: the melanonotus-ocellatus clade and the pentadactylusfuscus clade. However, it does not support the monophyly of the species groups as currently recognized …

The Tadpole Of Pseudis Minuta (Anura: Pseudidae), An Apparent Case Of Heterochrony, Rafael O. De Sá, Esteban O. Lavilla

Biology Faculty Publications

The external morphology, oral disc, and coloration pattern of the larva of Pseudis minuta are described. Tadpoles are mostly bottom dwellers that have a small, terminal oral disc with a labial tooth row formula 1(1-1)/(1-1)2. Internal oral anatomy is characterized using scanning electron microscopy, representing the only description available for the family Pseudidae. The coloration pattern of P. minuta tadpoles is compared with that of other pseudids. Pseudis minuta larvae do not exhibit the ontogenetic coloration change reported for P. paradoxa. Considering larval coloration, larval size, and reports of adult size, acceleration or hypermorphosis are suggested as possible heterochronic mechanisms …