Life Sciences Commons^™

Essential Genes For Astroglial Development And Axon Pathfinding During Zebrafish Embryogenesis, Michael J.F. Barresi, Sean Burton, Kristina Dipietrantonio, Adam Amsterdam, Nancy Hopkins, Rolf O. Karlstrom

Rolf O Karlstrom

The formation of the central nervous system depends on the coordinated development of neural and glial cell types that arise from a common precursor. Using an existing group of zebrafish mutants generated by viral insertion, we performed a “shelf-screen” to identify genes necessary for astroglial development and axon scaffold formation. We screened 274 of 315 viral insertion lines using antibodies that label axons (anti-Acetylated Tubulin) and astroglia (anti-Gfap) and identified 25 mutants with defects in gliogenesis, glial patterning, neurogenesis, and axon guidance. We also identified a novel class of mutants affecting radial glial cell numbers. Defects in astroglial patterning were …

Genomic Patterns Of Nucleotide Diversity In Divergent Populations Of U.S. Weedy Rice, Michael Reagon, Carrie Thurber, Brian Gross, Kenneth Olsen, Yulin Jia, Ana Caicedo

Biology Department Faculty Publication Series

Background: Weedy rice (red rice), a conspecific weed of cultivated rice (Oryza sativa L.), is a significant problem throughout the world and an emerging threat in regions where it was previously absent. Despite belonging to the same species complex as domesticated rice and its wild relatives, the evolutionary origins of weedy rice remain unclear. We use genome-wide patterns of single nucleotide polymorphism (SNP) variation in a broad geographic sample of weedy, domesticated, and wild Oryza samples to infer the origin and demographic processes influencing U.S. weedy rice evolution. Results: We find greater population structure than has been previously reported for …

Genomic Patterns Of Nucleotide Diversity In Divergent Populations Of U.S. Weedy Rice, Michael Reagon, Carrie S. Thurber, Brian L. Gross, Kenneth M. Olsen, Yulin Jia, Ana Lucia Caicedo

Ana Lucia Caicedo

Background: Weedy rice (red rice), a conspecific weed of cultivated rice (Oryza sativa L.), is a significant problem throughout the world and an emerging threat in regions where it was previously absent. Despite belonging to the same species complex as domesticated rice and its wild relatives, the evolutionary origins of weedy rice remain unclear. We use genome-wide patterns of single nucleotide polymorphism (SNP) variation in a broad geographic sample of weedy, domesticated, and wild Oryza samples to infer the origin and demographic processes influencing U.S. weedy rice evolution. Results: We find greater population structure than has been previously reported for …

Gravitropism Of Arabidopsis Thaliana Roots Requires The Polarization Of Pin2 Toward The Root Tip In Meristematic Cortical Cells, Abidur Rahman, Maho Takahashi, Kyohei Shibasaki, Shuang Wu, Takehito Inaba, Seiji Tsurumi, Tobias Baskin

Tobias Baskin

In the root, the transport of auxin from the tip to the elongation zone, referred to here as shootward, governs gravitropic bending. Shootward polar auxin transport, and hence gravitropism, depends on the polar deployment of the PIN-FORMED auxin efflux carrier PIN2. In Arabidopsis thaliana, PIN2 has the expected shootward localization in epidermis and lateral root cap; however, this carrier is localized toward the root tip (rootward) in cortical cells of the meristem, a deployment whose function is enigmatic. We use pharmacological and genetic tools to cause a shootward relocation of PIN2 in meristematic cortical cells without detectably altering PIN2 polarization …

The Transcriptional Repressor Rest/Nrsf Modulates Hedgehog Signaling, Keith P. Gates, Laura Mentzer, Rolf O. Karlstrom, Howard I. Sirotkin

Rolf O Karlstrom

The spatial and temporal control of gene expression is key to generation of specific cellular fates during development. Studies of the transcriptional repressor REST/NRSF (RE1 Silencing Transcription Factor or Neural Restrictive Silencing Factor) have provided important insight into the role that epigenetic modifications play in differential gene expression. However, the precise function of REST during embryonic development is not well understood. We have discovered a novel interaction between zebrafish Rest and the Hedgehog (Hh) signaling pathway. We observed that Rest knockdown enhances or represses Hh signaling in a context-dependant manner. In wild-type embryos and embryos with elevated Hh signaling, Rest …

Treatment Of Batch In The Detection, Calibration, And Quantification Of Immunoassays In Large-Scale Epidemiologic Studies, Brian W. Whitcomb, Neil J. Perkins, Paul S. Alpert, Enrique F. Schisterman

Biology Department Faculty Publication Series

No abstract provided.

Gravitropism Of Arabidopsis Thaliana Roots Requires The Polarization Of Pin2 Toward The Root Tip In Meristematic Cortical Cells, A Rahman, M Takahashi, K Shibasaki, Sa Wu, T Inaba, S Tsurumi, Ti Baskin

Biology Department Faculty Publication Series

In the root, the transport of auxin from the tip to the elongation zone, referred to here as shootward, governs gravitropic bending. Shootward polar auxin transport, and hence gravitropism, depends on the polar deployment of the PIN-FORMED auxin efflux carrier PIN2. In Arabidopsis thaliana, PIN2 has the expected shootward localization in epidermis and lateral root cap; however, this carrier is localized toward the root tip (rootward) in cortical cells of the meristem, a deployment whose function is enigmatic. We use pharmacological and genetic tools to cause a shootward relocation of PIN2 in meristematic cortical cells without detectably altering PIN2 polarization …

Bone Density And The Lightweight Skeletons Of Birds, Elizabeth R. Dumont

Biology Department Faculty Publication Series

The skeletons of birds are universally described as lightweight as a result of selection for minimizing the energy required for flight. From a functional perspective, the weight (mass) of an animal relative to its lift-generating surfaces is a key determinant of the metabolic cost of flight. The evolution of birds has been characterized by many weight-saving adaptations that are reflected in bone shape, many of which strengthen and stiffen the skeleton. Although largely unstudied in birds, the material properties of bone tissue can also contribute to bone strength and stiffness. In this study, I calculated the density of the cranium, …

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Emeritus Faculty Author Gallery

No abstract provided.

Multiple Domains In The Crumbs Homolog 2a (Crb2a) Protein Are Required For Regulating Rod Photoreceptor Size, Abigail Jensen, Ya-Chu Hsu

Biochemistry & Molecular Biology Department Faculty Publication Series

Background Vertebrate retinal photoreceptors are morphologically complex cells that have two apical regions, the inner segment and the outer segment. The outer segment is a modified cilium and is continuously regenerated throughout life. The molecular and cellular mechanisms that underlie vertebrate photoreceptor morphogenesis and the maintenance of the outer segment are largely unknown. The Crumbs (Crb) complex is a key regulator of apical membrane identity and size in epithelia and in Drosophila photoreceptors. Mutations in the human gene CRUMBS HOMOLOG 1 (CRB1) are associated with early and severe vision loss. Drosophila Crumbs and vertebrate Crb1 and Crumbs homolog 2 (Crb2) …

Examination Of Promotor Hypermethylation Patterns In Magnetically Enriched Exfoliated Breast Milk Epithelial Cells, Chung M. Wong

Masters Theses 1911 - February 2014

Suppression of genes involved in DNA repair, tumor suppression and detoxification through epigenetic modifications has been implicated in the etiology of cancer. As such analysis of promoter methylation patterns in genes frequently down regulated in breast cancer in non-cancerous subjects may serve as an indicator of breast cancer risk. CpG-island hypermethylation of single genes has been detected in cells isolated from nipple aspirate and ductal lavage, yet both isolation methods yield insufficient cells to complete an extensive analysis on any one donor sample.

As an alternative we have turned to magnetic separation of human mammary epithelial cells from breast milk. …

Behavior And Habitat Use Of Roseate Terns (Sterna Dougallii) Before And After Construction Of An Erosion Control Revetment, Corey Grinnell

Masters Theses 1911 - February 2014

An erosion control revetment was constructed at the Falkner Island Unit of the Stewart B. McKinney National Wildlife Refuge, Connecticut during the winter of 2000–2001. At the time, Falkner Island was the fifth largest breeding colony site for the federally endangered Roseate Tern. This study measures and describes some baseline information regarding Roseate Tern nesting, behavior, and habitat use at Falkner Island during the three breeding seasons prior to revetment construction (1998–2000). This baseline information is then compared to similar information from the first breeding season following revetment construction (2001).

For Roseate Tern adults, this study examined changes in pre-nesting …

Use Of Short-Term Floods As An Additional Management Strategy For Controlling Dodder (Cuscuta Gronovii Willd.) In Commercial Cranberry Production, James M. O'Connell

Masters Theses 1911 - February 2014

Dodder (Cuscuta gronovii Willd.) is a weed of serious concern to cranberry (Vaccinium macrocarpon Ait.) growers. It develops vigorously and has a long-lived seed bank. Cranberries are a perennial crop and therefore strategies available to growers of annual crops are not practical. Herbicides, the primary management tool for dodder, although effective, have a narrow window of application and extended seedling emergence after applications can result in escapes. This project examined the effect of water temperature on dodder seed germination and the use of short-term floods (less than 72 hr) for dodder management.

Experiments investigated the effect of water temperature on …

Regulation Of Crbp1 In Mammary Epithelial Cells, Stacy L. Pease

Masters Theses 1911 - February 2014

Breast cancer is the second leading cause of death of women in the United States, warranting further investigation into preventative therapies. It has been well documented that early pregnancy results in a lifetime decreased risk of breast cancer in humans and mounting evidence suggests that the retinoic acid pathway may play an important role in this protective effect. Cellular retinol binding protein-1 (CRBP1) is an essential component of the retinoic acid pathway and we propose that it plays an important role in pregnancy-induced protection against breast cancer. In order to investigate the role of CRBP1 in parity-induced protection against breast …

Identification Of A Cellulose Synthase-Associated Protein Required For Cellulose Biosynthesis, Y Gu, N Kaplinsky, M Bringmann, A Cobb, A Carroll, A Sampathkumar, Ti Baskin, S Persson, Cr Somerville

Biology Department Faculty Publication Series

Cellulose synthase-interactive protein 1 (CSI1) was identified in a two-hybrid screen for proteins that interact with cellulose synthase (CESA) isoforms involved in primary plant cell wall synthesis. CSI1 encodes a 2,150-amino acid protein that contains 10 predicted Armadillo repeats and a C2 domain. Mutations in CSI1 cause defective cell elongation in hypocotyls and roots and reduce cellulose content. CSI1 is associated with CESA complexes, and csi1 mutants affect the distribution and movement of CESA complexes in the plasma membrane.

Myosin Xi Is Essential For Tip Growth In Physcomitrella Patens, L Vidali, Gm Burkart, Rc Augustine, E Kerdavid, E Tuzel, M Bezanilla

Biology Department Faculty Publication Series

Class XI myosins are plant specific and responsible for cytoplasmic streaming. Because of the large number of myosin XI genes in angiosperms, it has been difficult to determine their precise role, particularly with respect to tip growth. The moss Physcomitrella patens provides an ideal system to study myosin XI function. P. patens has only two myosin XI genes, and these genes encode proteins that are 94% identical to each other. To determine their role in tip growth, we used RNA interference to specifically silence each myosin XI gene using 59 untranslated region sequences. We discovered that the two myosin XI …

Predicting Bite Force In Mammals: Two-Dimensional Versus Three-Dimensional Lever Models, Jl Davis, Se Santana, Er Dumont, Ir Grosse

Biology Department Faculty Publication Series

Bite force is a measure of whole-organism performance that is often used to investigate the relationships between performance, morphology and fitness. When in vivo measurements of bite force are unavailable, researchers often turn to lever models to predict bite forces. This study demonstrates that bite force predictions based on two-dimensional (2-D) lever models can be improved by including three-dimensional (3-D) geometry and realistic physiological cross-sectional areas derived from dissections. Widely used, the 2-D method does a reasonable job of predicting bite force. However, it does so by over predicting physiological cross-sectional areas for the masseter and pterygoid muscles and under …

Microanatomical Assessment Of Nasomaxillary Suture Patency, Timothy D. Smith, Anne M. Burrows, Elizabeth R. Dumont

Biology Department Faculty Publication Series

No abstract provided.

The Transcriptional Repressor Rest/Nrsf Modulates Hedgehog Signaling, Keith P. Gates, Laura Mentzer, Rolf O. Karlstrom, Howard I. Sirotkin

Biology Department Faculty Publication Series

The spatial and temporal control of gene expression is key to generation of specific cellular fates during development. Studies of the transcriptional repressor REST/NRSF (RE1 Silencing Transcription Factor or Neural Restrictive Silencing Factor) have provided important insight into the role that epigenetic modifications play in differential gene expression. However, the precise function of REST during embryonic development is not well understood. We have discovered a novel interaction between zebrafish Rest and the Hedgehog (Hh) signaling pathway. We observed that Rest knockdown enhances or represses Hh signaling in a context-dependant manner. In wild-type embryos and embryos with elevated Hh signaling, Rest …

Polymer Microlenses For Quantifying Cell Sheet Mechanics, Guillaume Miquelard-Garnier, Jessica A. Zimberlin, Christian B. Sikora, Patricia Wadsworth, Alfred Crosby

Biology Department Faculty Publication Series

Mechanical interactions between individual cells and their substrate have been studied extensively over the past decade; however, understanding how these interactions change as cells interact with neighboring cells in the development of a cell sheet, or early stage tissue, is less developed. We use a recently developed experimental technique for quantifying the mechanics of confluent cell sheets. Living cells are cultured on a thin film of polystyrene [PS], which is attached to a patterned substrate of crosslinked poly(dimethyl siloxane) [PDMS] microwells. As cells attach to the substrate and begin to form a sheet, they apply sufficient contractile force to buckle …

Environmental Chemicals Targeting Thyroid, Thomas R. Zoeller

Biology Department Faculty Publication Series

Thyroid hormones (THs) are required for normal brain and somatic development and for the proper regulation of physiology in both children and adults. Thyroid function is controlled by the dynamic interrelationships between the hypothalamus, the pituitary and the thyroid. These dynamic relationships maintain circulating levels of THs within a narrow range under normal conditions. Normally, there is likely to be a tight relationship between changes in circulating levels of THs and changes in TH action in various target tissues. This relationship is maintained by tissue-level mechanisms that include TH metabolism and transport. Environmental chemicals that interfere with TH signaling mechanisms …

Aluminium Reduces Sugar Uptake In Tobacco Cell Cultures: A Potential Cause Of Inhibited Elongation But Not Of Toxicity, R Abdel-Basset, S Ozuka, T Demiral, T Furuichi, I Sawatani, Ti Baskin, H Matsumoto, Y Yamamoto

Biology Department Faculty Publication Series

Aluminium is well known to inhibit plant elongation, but the role in this inhibition played by water relations remains unclear. To investigate this, tobacco (Nicotiana tabacum L.) suspension-cultured cells (line SL) was used, treating them with aluminium (50 mM) in a medium containing calcium, sucrose, and MES (pH 5.0). Over an 18 h treatment period, aluminium inhibited the increase in fresh weight almost completely and decreased cellular osmolality and internal soluble sugar content substantially; however, aluminium did not affect the concentrations of major inorganic ions. In aluminium-treated cultures, fresh weight, soluble sugar content, and osmolality decreased over the first 6 …

A Conditional Mutation In Arabidopsis Thaliana Separase Induces Chromosome Non-Disjunction, Aberrant Morphogenesis And Cyclin B1;1 Stability, S Wu, Wr Scheible, D Schindelasch, H Van Den Daele, L De Veylder, Ti Baskin

Biology Department Faculty Publication Series

The caspase family protease, separase, is required at anaphase onset to cleave the cohesin complex, which joins sister chromatids. However, among eukaryotes, separases have acquired novel functions. Here, we show that Arabidopsis thaliana radially swollen 4 (rsw4), a temperature-sensitive mutant isolated previously on the basis of root swelling, harbors a mutation in At4g22970, the A. thaliana separase. Loss of separase function in rsw4 at the restrictive temperature is indicated by the widespread failure of replicated chromosomes to disjoin. Surprisingly, rsw4 has neither pronounced cell cycle arrest nor anomalous spindle formation, which occur in other eukaryotes upon loss of separase activity. …

Molecular Pedomorphism Underlies Craniofacial Skeletal Evolution In Antarctic Notothenioid Fishes, R. Craig Albertson, Y-L Yan, T. A. Titus, E. Pisano, M. Vacchi, P. C. Yelick, W. H. Detrich, J. H. Postlethwait

R. Craig Albertson

Background

Pedomorphism is the retention of ancestrally juvenile traits by adults in a descendant taxon. Despite its importance for evolutionary change, there are few examples of a molecular basis for this phenomenon. Notothenioids represent one of the best described species flocks among marine fishes, but their diversity is currently threatened by the rapidly changing Antarctic climate. Notothenioid evolutionary history is characterized by parallel radiations from a benthic ancestor to pelagic predators, which was accompanied by the appearance of several pedomorphic traits, including the reduction of skeletal mineralization that resulted in increased buoyancy. Results

We compared craniofacial skeletal development in two …

Bentho-Pelagic Divergence Of Cichlid Feeding Architecture Has Been Consistent And Prodigious During Multiple Adaptive Radiations Within African Rift-Lakes, R. Craig Albertson, W. J. Cooper, K. J. Parsons, A. M. Mcintyre, B. S. Kern, A. C. Mcgee-Moore

R. Craig Albertson

How particular changes in functional morphology can repeatedly promote ecological diversification is an active area of evolutionary investigation. The African rift-lake cichlids offer a calibrated time series of the most dramatic adaptive radiations of vertebrate trophic morphology yet described, and the replicate nature of these events provides a unique opportunity to test whether common changes in functional morphology have repeatedly facilitated their ecological success.

Fast Microtubule Dynamics In Meiotic Spindles Measured By Single Molecule Imaging: Evidence That The Spindle Environment Does Not Stabilize Microtubules, Thomas J. Maresca, D. J. Needleman, A. Groen, R. Ohi, L. Mirny, T. Mitchison

Thomas J. Maresca

Metaphase spindles are steady-state ensembles of microtubules that turn over rapidly and slide poleward in some systems. Since the discovery of dynamic instability in the mid-1980s, models for spindle morphogenesis have proposed that microtubules are stabilized by the spindle environment. We used single molecule imaging to measure tubulin turnover in spindles, and nonspindle assemblies, in Xenopus laevis egg extracts. We observed many events where tubulin molecules spend only a few seconds in polymer and thus are difficult to reconcile with standard models of polymerization dynamics. Our data can be quantitatively explained by a simple, phenomenological model—with only one adjustable parameter—in …

Evolution Of A Unique Predatory Feeding Apparatus: Functional Anatomy, Development And A Genetic Locus For Jaw Laterality In Lake Tanganyika Scale-Eating Cichlids, R. Craig Albertson, T. A. Stewart

R. Craig Albertson

Background While bilaterality is a defining characteristic of triploblastic animals, several assemblages have managed to break this symmetry in order to exploit the adaptive peaks garnered through the lateralization of behaviour or morphology. One striking example of an evolved asymmetry in vertebrates comes from a group of scale-eating cichlid fishes from Lake Tanganyika. Members of the Perissodini tribe of cichlid fishes have evolved dental and craniofacial asymmetries in order to more effectively remove scales from the left or right flanks of prey. Here we examine the evolution and development of craniofacial morphology and laterality among Lake Tanganyika scale-eating cichlids. Results …

Welcome To A New Kind Of Tension: Translating Kinetochore Mechanics Into A Wait-Anaphase Signal, Thomas J. Maresca, E. D. Salmon

Thomas J. Maresca

Recent high-resolution studies of kinetochore structure have transformed the way researchers think about this crucial macro-molecular complex, which is essential for ensuring chromosome segregation occurs faithfully during cell division. Kinetochores mediate the interaction between chromosomes and the plus-ends of dynamic spindle microtubules and control the timing of anaphase onset by regulating the spindle assembly checkpoint (SAC). There is much debate in the SAC research community as to whether mitotic cells sense only microtubule attachment at the kinetochore, or both attachment and tension, before committing to anaphase. In this Commentary, we present a brief history of the tension-versus-attachment debate, summarize recent …

Anhang: Auszüge Aus Dem Späteren Leben Von Professor Dr. Otto Vogl, Otto Vogl

Otto Vogl

No abstract provided.

Poleward Transport Of Tpx2 In The Mammalian Mitotic Spindle Requires Dynein, Eg5, And Microtubule Flux, Patricia Wadsworth, N. Ma, S. Tulu, N. Ferenz, C. Fagerstrom, A. Mogilner

Patricia Wadsworth

TPX2 is a Ran-regulated spindle assembly factor that is required for kinetochore fiber formation and activation of the mitotic kinase Aurora A. TPX2 is enriched near spindle poles and is required near kinetochores, suggesting that it undergoes dynamic relocalization throughout mitosis. Using photoactivation, we measured the movement of PA-GFP-TPX2 in the mitotic spindle. TPX2 moves poleward in the half-spindle and is static in the interzone and near spindle poles. Poleward transport of TPX2 is sensitive to inhibition of dynein or Eg5 and to suppression of microtubule flux with nocodazole or antibodies to Kif2a. Poleward transport requires the C terminus of …