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Molecular Biology

2011

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Articles 31 - 60 of 285

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

Investigating A Conformational Change In The Enzyme Neurolysin, Fei Xiong Nov 2011

Investigating A Conformational Change In The Enzyme Neurolysin, Fei Xiong

Kaleidoscope

No abstract provided.


Investigating Calmodulin-Long Qt Syndrome Restorative Interactions Through Combinatorial Approaches, Michael Bricken Nov 2011

Investigating Calmodulin-Long Qt Syndrome Restorative Interactions Through Combinatorial Approaches, Michael Bricken

Kaleidoscope

No abstract provided.


Differential Il-21 Signaling In Apcs Leads To Disparate Th17 Differentiation In Diabetes-Susceptible Nod And Diabetes-Resistant Nod.Idd3 Mice., Sue M. Liu, David H. Lee, Jenna M. Sullivan, Denise Chung, Anneli Jäger, Bennett O V. Shum, Nora E. Sarvetnick, Ana C. Anderson, Vijay K. Kuchroo Nov 2011

Differential Il-21 Signaling In Apcs Leads To Disparate Th17 Differentiation In Diabetes-Susceptible Nod And Diabetes-Resistant Nod.Idd3 Mice., Sue M. Liu, David H. Lee, Jenna M. Sullivan, Denise Chung, Anneli Jäger, Bennett O V. Shum, Nora E. Sarvetnick, Ana C. Anderson, Vijay K. Kuchroo

Journal Articles: Regenerative Medicine

Type 1 diabetes (T1D) is an autoimmune disease that shows familial aggregation in humans and likely has genetic determinants. Disease linkage studies have revealed many susceptibility loci for T1D in mice and humans. The mouse T1D susceptibility locus insulin-dependent diabetes susceptibility 3 (Idd3), which has a homologous genetic interval in humans, encodes cytokine genes Il2 and Il21 and regulates diabetes and other autoimmune diseases; however, the cellular and molecular mechanisms of this regulation are still being elucidated. Here we show that T cells from NOD mice produce more Il21 and less Il2 and exhibit enhanced Th17 cell generation compared with ...


Mlk3 Regulates Bone Development Downstream Of The Faciogenital Dysplasia Protein Fgd1 In Mice, Weiguo Zou, Matthew B. Greenblatt, Jae-Hyuck Shim, Shashi Kant, Bo Zhai, Sutada Lotinun, Nicholas Brady, Dorothy Zhang Hu, Steven P. Gygi, Roland Baron, Roger J. Davis, Dallas Jones, Laurie H. Glimcher Nov 2011

Mlk3 Regulates Bone Development Downstream Of The Faciogenital Dysplasia Protein Fgd1 In Mice, Weiguo Zou, Matthew B. Greenblatt, Jae-Hyuck Shim, Shashi Kant, Bo Zhai, Sutada Lotinun, Nicholas Brady, Dorothy Zhang Hu, Steven P. Gygi, Roland Baron, Roger J. Davis, Dallas Jones, Laurie H. Glimcher

Davis Lab Publications

Mutations in human FYVE, RhoGEF, and PH domain-containing 1 (FGD1) cause faciogenital dysplasia (FGDY; also known as Aarskog syndrome), an X-linked disorder that affects multiple skeletal structures. FGD1 encodes a guanine nucleotide exchange factor (GEF) that specifically activates the Rho GTPase CDC42. However, the mechanisms by which mutations in FGD1 affect skeletal development are unknown. Here, we describe what we believe to be a novel signaling pathway in osteoblasts initiated by FGD1 that involves the MAP3K mixed-lineage kinase 3 (MLK3). We observed that MLK3 functions downstream of FGD1 to regulate ERK and p38 MAPK, which in turn phosphorylate and activate ...


Mitochondrial Dna Analysis By Denaturing High-Performance Liquid Chromatography For The Characterization And Separation Of Mixtures In Forensic Samples, Richard Kristinsson Nov 2011

Mitochondrial Dna Analysis By Denaturing High-Performance Liquid Chromatography For The Characterization And Separation Of Mixtures In Forensic Samples, Richard Kristinsson

Electronic Theses and Dissertations

A mixture of different mtDNA molecules in a single sample is a significant obstacle to the successful use of standard methods of mtDNA analysis (i.e., dideoxy dye-terminator sequencing). Forensic analysts often encounter either naturally occurring mixtures (e.g., heteroplasmy) or situational mixtures typically arising from a combination of body fluids from separate individuals. The ability to accurately resolve and interpret these types of samples in a timely and cost efficient manner would substantially increase the power of mtDNA analysis and potentially provide valuable investigative information by allowing its use in cases where the current approach is limited or fails ...


Investigating The Roles Of Ndj1 And Tid1 In Crossover Assurance In Saccharomyces Cerevisiae, Rianna Knowles Nov 2011

Investigating The Roles Of Ndj1 And Tid1 In Crossover Assurance In Saccharomyces Cerevisiae, Rianna Knowles

Master's Theses and Project Reports

Meiosis is the specialized process of cell division utilized during gametogenesis in all sexually reproducing eukaryotes, which consists of one round of DNA replication followed by two rounds of chromosome segregation and results in four haploid cells. Crossovers between homologous chromosomes promote proper alignment and segregation of chromosomes during meiosis.

Crossover interference is a genetic phenomenon in which crossovers are non-randomly placed along chromosomes. Crossover assurance ensures that every homologous chromosome pair obtains at least one crossover during Prophase I. Crossovers physically connect homologous pairs, allowing spindle fibers to attach and separate homologs properly. However, some organisms have shown an ...


Modulation Of Cyanobacterial Photosystem I Deposition Properties On Alkanethiolate Au Substrate By Various Experimental Conditions, Dibyendu Mukherjee, Michael Vaughn, Bamin Khomami, Barry Bruce Oct 2011

Modulation Of Cyanobacterial Photosystem I Deposition Properties On Alkanethiolate Au Substrate By Various Experimental Conditions, Dibyendu Mukherjee, Michael Vaughn, Bamin Khomami, Barry Bruce

Barry D. Bruce

We present results from atomic force microscopy (AFM) images indicating various experimental conditions, which alter the morphological characteristics of self-assembled cyanobacterial PS I on hydroxyl-terminated self-assembled alkanethiolate monolayers (SAM/Au) substrates. AFM topographical images of SAM/Au substrates incubated in solutions containing different PS I concentrations solubilized with Triton X-100 as the detergent reveal large columnar aggregates (∼100 nm and hence, much taller than a single PS I trimer) at high PS I concentrations. Depositions from dilute PS I suspensions reveal fewer aggregates and relatively uniform surface topography (∼10 nm). Confocal fluorescence microscopy analysis of fluorescently tagged PS I deposited ...


Arabidopsis And Tobacco Superman Regulate Hormone Signalling And Mediate Cell Proliferation And Differentiation, C. Nibau, V. S. Di Stilio, H. M. Wu, Alice Cheung Oct 2011

Arabidopsis And Tobacco Superman Regulate Hormone Signalling And Mediate Cell Proliferation And Differentiation, C. Nibau, V. S. Di Stilio, H. M. Wu, Alice Cheung

Alice Cheung

Arabidopsis thaliana superman (SUP) plays an important role during flower development by maintaining the boundary between stamens and carpels in the inner two whorls. It was proposed that SUP maintains this boundary by regulating cell proliferation in both whorls, as loss-of-function superman mutants produce more stamens at the expense of carpels. However, the cellular mechanism that underlies SUP function remains unknown. Here Arabidopsis or tobacco (Nicotiana tabacum) SUP was overexpressed in tobacco plants to substantiate SUP's role as a regulator of cell proliferation and boundary definition and provide evidence that its biological role may be mediated via hormonal changes ...


University Scholar Series: Brandon White, Brandon White Oct 2011

University Scholar Series: Brandon White, Brandon White

University Scholar Series

On October 26, 2011, Dr. Brandon White spoke in the University Scholar Series hosted by Provost Gerry Selter at the Dr. Martin Luther King, Jr. Library. Brandon White is an Assistant Professor in Biological Sciences at SJSU, teaching courses in molecular biology, molecular biological techniques, and cell biology. His research focuses on Notch signaling and identification, and characterization of natural products involved in cell death of cancer cells. In this seminar, Dr. Brandon White discusses the use and applications of HeLa cells in science and biotechnology.


Characterization Of The Activities Of The Cpey, Cpez, And Cpes Bilin Lyases In Phycoerythrin Biosynthesis In Fremyella Diplosiphon Strain Utex 481*, Wendy Schluchter Oct 2011

Characterization Of The Activities Of The Cpey, Cpez, And Cpes Bilin Lyases In Phycoerythrin Biosynthesis In Fremyella Diplosiphon Strain Utex 481*, Wendy Schluchter

Wendy M Schluchter

When grown in green light, Fremyella diplosiphon strain UTEX481 produces the red-colored protein phycoerythrin (PE) to maximize photosynthetic light harvesting. PE is composed of two subunits, CpeA and CpeB, which carry two and three phycoerythrobilin (PEB) chromophores, respectively, that are attached to specific Cys residues via thioether linkages. Specific bilin lyases are hypothesized to catalyze each PEB ligation. Using a heterologous, coexpression system in Escherichia coli, the PEB ligation activities of putative lyase subunits CpeY, CpeZ, and CpeS were tested on the CpeA and CpeB subunits from F. diplosiphon. Purified His6-tagged CpeA, obtained by coexpressing cpeA, cpeYZ, and the genes ...


Phenolic Compounds And Antioxidant Activities In Some Fruits And Vegetables From Burkina Faso, Romaric G. Bayili Msc., Fatoumata Abdou-Latif Msc., Oumou H. Kone Msc., Mamouna Diao Msc., Mamoudou H. Dicko Prof. Oct 2011

Phenolic Compounds And Antioxidant Activities In Some Fruits And Vegetables From Burkina Faso, Romaric G. Bayili Msc., Fatoumata Abdou-Latif Msc., Oumou H. Kone Msc., Mamouna Diao Msc., Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

Levels of total phenolic compounds (TPC), proanthocyanidins (PAs) and antioxidant activities among sixteen fruits and vegetables commonly consumed in Burkina Faso were determined. Levels of TPC ranged from 0.21 to 3.33 mg of gallic acid equivalent per gram of fresh matter. The highest contents in TPC were found in hot chili pepper, okra, lemon, spinach, onion, while the highest contents in PAs were found in spinach (3.52 mg), onion (2.35 mg), okra (1.27 mg), hot chili pepper (1.11 mg), tomato (0.54 mg) and garlic (0.46 mg). Antioxidant activities ranged from 0 to ...


Electrosensory Ampullary Organs Are Derived From Lateral Line Placodes In Bony Fishes, Melissa S. Modrell, William E. Benis, R. Glenn Northcutt, Marcus C. Davis, Clare V.H. Baker Oct 2011

Electrosensory Ampullary Organs Are Derived From Lateral Line Placodes In Bony Fishes, Melissa S. Modrell, William E. Benis, R. Glenn Northcutt, Marcus C. Davis, Clare V.H. Baker

Faculty Publications

Electroreception is an ancient subdivision of the lateral line sensory system, found in all major vertebrate groups (though lost in frogs, amniotes and most ray-finned fishes). Electroreception is mediated by 'hair cells' in ampullary organs, distributed in fields flanking lines of mechanosensory hair cell-containing neuromasts that detect local water movement. Neuromasts, and afferent neurons for both neuromasts and ampullary organs, develop from lateral line placodes. Although ampullary organs in the axolotl (a representative of the lobe-finned clade of bony fishes) are lateral line placode-derived, non-placodal origins have been proposed for electroreceptors in other taxa. Here we show morphological and molecular ...


Splice Variant–Specific Cellular Function Of The Formin Inf2 In Maintenance Of Golgi Architecture, Vinay Ramabhadran, Farida Korobova, Gilbert J. Rahme, Henry N. Higgs Oct 2011

Splice Variant–Specific Cellular Function Of The Formin Inf2 In Maintenance Of Golgi Architecture, Vinay Ramabhadran, Farida Korobova, Gilbert J. Rahme, Henry N. Higgs

Open Dartmouth: Faculty Open Access Scholarship

INF2 is a unique formin that can both polymerize and depolymerize actin filaments. Mutations in INF2 cause the kidney disease focal and segmental glomerulosclerosis. INF2 can be expressed as two C-terminal splice variants: CAAX and non-CAAX. The CAAX isoform contains a C-terminal prenyl group and is tightly bound to endoplasmic reticulum (ER). The localization pattern and cellular function of the non-CAAX isoform have not been studied. Here we find that the two isoforms are expressed in a cell type-dependent manner, with CAAX predominant in 3T3 fibroblasts and non-CAAX predominant in U2OS, HeLa, and Jurkat cells. Although INF2-CAAX is ER localized ...


Dopamine Regulation Of Cone-Cone Gap Junctions In Ground Squirrel Retina, Xiaoyu Li '12, Steven Devries Oct 2011

Dopamine Regulation Of Cone-Cone Gap Junctions In Ground Squirrel Retina, Xiaoyu Li '12, Steven Devries

Student Publications & Research

Cone photoreceptors are electrically coupled such that when the electrical potential in one cell changes, it also changes in adjacent, coupled cells. Phosphorylation of the cone gap junction protein, connexin 36 (Cx36), determines whether a coupling channel is “open” or “closed”. Cx36- containing gap junctions are phosphorylated in the open state and dephosphorylated in the closed state. Cone-cone gap junction modulation has not been extensively studied, however, the presence of rod-cone gap junction modulation raises the possibility that the same is true for cone pairs. Pieces of thirteen-lined ground squirrel retina were removed from the eye and the tissue was ...


Tnf-Stimulated Map Kinase Activation Mediated By A Rho Family Gtpase Signaling Pathway, Shashi Kant, Wojciech Swat, Sheng Zhang, Zhong-Yin Zhang, Benjamin G. Neel, Richard A. Flavell, Roger J. Davis Oct 2011

Tnf-Stimulated Map Kinase Activation Mediated By A Rho Family Gtpase Signaling Pathway, Shashi Kant, Wojciech Swat, Sheng Zhang, Zhong-Yin Zhang, Benjamin G. Neel, Richard A. Flavell, Roger J. Davis

Davis Lab Publications

The biological response to tumor necrosis factor (TNF) involves activation of MAP kinases. Here we report a mechanism of MAP kinase activation by TNF that is mediated by the Rho GTPase family members Rac/Cdc42. This signaling pathway requires Src-dependent activation of the guanosine nucleotide exchange factor Vav, activation of Rac/Cdc42, and the engagement of the Rac/Cdc42 interaction site (CRIB motif) on mixed-lineage protein kinases (MLKs). We show that this pathway is essential for full MAP kinase activation during the response to TNF. Moreover, this MLK pathway contributes to inflammation in vivo.


A Brain-Derived Mecp2 Complex Supports A Role For Mecp2 In Rna Processing, Steven W. Long, Jenny Y. Y. Ooi, Peter M. Yau, Peter L. Jones Oct 2011

A Brain-Derived Mecp2 Complex Supports A Role For Mecp2 In Rna Processing, Steven W. Long, Jenny Y. Y. Ooi, Peter M. Yau, Peter L. Jones

Peter Jones Lab Publications

Mutations in MECP2 (methyl-CpG-binding protein 2) are linked to the severe postnatal neurodevelopmental disorder RTT (Rett syndrome). MeCP2 was originally characterized as a transcriptional repressor that preferentially bound methylated DNA; however, recent results indicate MeCP2 is a multifunctional protein. MeCP2 binding is now associated with certain expressed genes and involved in nuclear organization as well, indicating that its gene regulatory function is context-dependent. In addition, MeCP2 is proposed to regulate mRNA splicing and a mouse model for RTT shows aberrant mRNA splicing. To further understand MeCP2 and potential roles in RTT pathogenesis, we have employed a biochemical approach to identify ...


Arcane Secrets Of The Umass Libraries, Maxine G. Schmidt Sep 2011

Arcane Secrets Of The Umass Libraries, Maxine G. Schmidt

Maxine G Schmidt

No abstract provided.


Differential Interactions Of The Formins Inf2, Mdia1, And Mdia2 With Microtubules, Jeremie Gaillard, Bvinay Ramabhadran, Emmanuelle Neumanne, Pinar Gurel, Laurent Blanchoin, Marylin Vantard, Henry N. Higgs Sep 2011

Differential Interactions Of The Formins Inf2, Mdia1, And Mdia2 With Microtubules, Jeremie Gaillard, Bvinay Ramabhadran, Emmanuelle Neumanne, Pinar Gurel, Laurent Blanchoin, Marylin Vantard, Henry N. Higgs

Open Dartmouth: Faculty Open Access Scholarship

A number of cellular processes use both microtubules and actin filaments, but the molecular machinery linking these two cytoskeletal elements remains to be elucidated in detail. Formins are actin-binding proteins that have multiple effects on actin dynamics, and one formin, mDia2, has been shown to bind and stabilize microtubules through its formin homology 2 (FH2) domain. Here we show that three formins, INF2, mDia1, and mDia2, display important differences in their interactions with microtubules and actin. Constructs containing FH1, FH2, and C-terminal domains of all three formins bind microtubules with high affinity (K(d) < 100 nM). However, only mDia2 binds microtubules at 1:1 stoichiometry, with INF2 and mDia1 showing saturating binding at approximately 1:3 (formin dimer:tubulin dimer). INF2-FH1FH2C is a potent microtubule-bundling protein, an effect that results in a large reduction in catastrophe rate. In contrast, neither mDia1 nor mDia2 is a potent microtubule bundler. The C-termini of mDia2 and INF2 have different functions in microtubule interaction, with mDia2's C-terminus required for high-affinity binding and INF2's C-terminus required for bundling. mDia2's C-terminus directly binds microtubules with submicromolar affinity. These formins also differ in their abilities to bind actin and microtubules simultaneously. Microtubules strongly inhibit actin polymerization by mDia2, whereas they moderately inhibit mDia1 and have no effect on INF2. Conversely, actin monomers inhibit microtubule binding/bundling by INF2 but do not affect mDia1 or mDia2. These differences in interactions with microtubules and actin suggest differential function in cellular processes requiring both cytoskeletal elements.


The Pcdp1 Complex Coordinates The Activity Of Dynein Isoforms To Produce Wild-Type Ciliary Motility, Christen G. Dipetrillo, Elizabeth F. Smith Sep 2011

The Pcdp1 Complex Coordinates The Activity Of Dynein Isoforms To Produce Wild-Type Ciliary Motility, Christen G. Dipetrillo, Elizabeth F. Smith

Open Dartmouth: Faculty Open Access Scholarship

Generating the complex waveforms characteristic of beating cilia requires the coordinated activity of multiple dynein isoforms anchored to the axoneme. We previously identified a complex associated with the C1d projection of the central apparatus that includes primary ciliary dyskinesia protein 1 (Pcdp1). Reduced expression of complex members results in severe motility defects, indicating that C1d is essential for wild-type ciliary beating. To define a mechanism for Pcdp1/C1d regulation of motility, we took a functional and structural approach combined with mutants lacking C1d and distinct subsets of dynein arms. Unlike mutants completely lacking the central apparatus, dynein-driven microtubule sliding velocities ...


A Novel Labda-7,13e-Dien-15-Ol-Producing Bifunctional Diterpene Synthase From Selaginella Moellendorffii, Sibongile Mafu, Matthew L. Hillwig, Reuben J. Peters Sep 2011

A Novel Labda-7,13e-Dien-15-Ol-Producing Bifunctional Diterpene Synthase From Selaginella Moellendorffii, Sibongile Mafu, Matthew L. Hillwig, Reuben J. Peters

Biochemistry, Biophysics and Molecular Biology Publications

Vascular plants invariably contain a class II diterpene cyclase (EC 5.5.1.x), as an ent-copalyl diphosphate synthase is required for gibberellin phytohormone biosynthesis. This has provided the basis for evolution of a functionally diverse enzymatic family.[1] These biocatalysts fold their substrate, the general diterpenoid precursor (E,E,E)-geranylgeranyl diphosphate (GGPP), to bring the terminal three carbon-carbon double bonds into proximity with each other, and then carry out bicyclization via a protonation-initiated carbocation cascade reaction. The resulting labda-15-en-8-yl+ diphosphate intermediate is most commonly quenched by deprotonation at an exocyclic methyl, as in the production of labdadienyl/copalyl ...


Drosophila Iap1-Mediated Ubiquitylation Controls Activation Of The Initiator Caspase Dronc Independent Of Protein Degradation, Tom V. Lee, Yun Fan, Shiuan Wang, Mayank Srivastava, Meike Broemer, Pascal Meier, Andreas Bergmann Sep 2011

Drosophila Iap1-Mediated Ubiquitylation Controls Activation Of The Initiator Caspase Dronc Independent Of Protein Degradation, Tom V. Lee, Yun Fan, Shiuan Wang, Mayank Srivastava, Meike Broemer, Pascal Meier, Andreas Bergmann

Molecular, Cell and Cancer Biology Publications

Ubiquitylation targets proteins for proteasome-mediated degradation and plays important roles in many biological processes including apoptosis. However, non-proteolytic functions of ubiquitylation are also known. In Drosophila, the inhibitor of apoptosis protein 1 (DIAP1) is known to ubiquitylate the initiator caspase DRONC in vitro. Because DRONC protein accumulates in diap1 mutant cells that are kept alive by caspase inhibition ("undead" cells), it is thought that DIAP1-mediated ubiquitylation causes proteasomal degradation of DRONC, protecting cells from apoptosis. However, contrary to this model, we show here that DIAP1-mediated ubiquitylation does not trigger proteasomal degradation of full-length DRONC, but serves a non-proteolytic function. Our ...


Optimization Of Photosynthetic Hydrogen Yield From Platinized Photosystem I Complexes Using Response Surface Methodology, Ifeyinwa Iwuchukwu, Ernest Iwuchukwu, Rosemary Le, Caitlin Paquet, Rapinder Sawhney, Barry Bruce, Paul Frymier Aug 2011

Optimization Of Photosynthetic Hydrogen Yield From Platinized Photosystem I Complexes Using Response Surface Methodology, Ifeyinwa Iwuchukwu, Ernest Iwuchukwu, Rosemary Le, Caitlin Paquet, Rapinder Sawhney, Barry Bruce, Paul Frymier

Barry D. Bruce

Light-dependent hydrogen production by platinized Photosystem I isolated from the cyanobacterium Thermosynechococcus elongatus BP-1 was optimized using response surface methodology (RSM). The process parameters studied included temperature, light intensity and wavelength, and platinum salt concentration. Application of RSM generated a model that agrees well with the data for H2 yield (R2 = 0.99 and p < 0.001). Significant effects on the total H2 yield were seen when the platinum salt concentration and temperature were varied during platinization. However, light intensity during platinization had a minimal effect on the total H2 yield within the region studied. The values of the parameters used during the platinization that optimized the production of H2 were light intensity of 240 μE m−2 s−1, platinum salt concentration of 636 μM and temperature of 31 °C. A subsequent validation experiment at the predicted conditions for optimal process yield gave the maximum H2 yield measured in the study, which was 8.02 μmol H2 per mg chlorophyll.


Camp-Dependent Protein Kinase A Selects The Excited State Of The Membrane Substrate Phospholamban, Larry R. Masterson Aug 2011

Camp-Dependent Protein Kinase A Selects The Excited State Of The Membrane Substrate Phospholamban, Larry R. Masterson

Larry Masterson

Phosphorylation of membrane proteins is a central regulatory and signaling mechanism across cell compartments. However, the recognition process and phosphorylation mechanism of membrane-bound substrates by kinases are virtually unknown. cAMP-dependent protein kinase A (PKA) is a ubiquitous enzyme that phosphorylates several soluble and membrane-bound substrates. In cardiomyocytes, PKA targets phospholamban (PLN), a membrane protein that inhibits the sarcoplasmic reticulum Ca2+-ATPase (SERCA). In the unphosphorylated state, PLN binds SERCA, reducing the calcium uptake and generating muscle contraction. PKA phosphorylation of PLN at S16 in the cytoplasmic helix relieves SERCA inhibition, initiating muscle relaxation. Using steady-state kinetic assays, NMR spectroscopy ...


The Filament-Forming Protein Pil1 Assembles Linear Eisosomes In Fission Yeast, Ruth Kabeche, Suzanne Baldissard, John Hammond, Louisa Howard, James B. Moseley Aug 2011

The Filament-Forming Protein Pil1 Assembles Linear Eisosomes In Fission Yeast, Ruth Kabeche, Suzanne Baldissard, John Hammond, Louisa Howard, James B. Moseley

Open Dartmouth: Faculty Open Access Scholarship

The cortical cytoskeleton mediates a range of cellular activities such as endocytosis, cell motility, and the maintenance of cell rigidity. Traditional polymers, including actin, microtubules, and septins, contribute to the cortical cytoskeleton, but additional filament systems may also exist. In yeast cells, cortical structures called eisosomes generate specialized domains termed MCCs to cluster specific proteins at sites of membrane invaginations. Here we show that the core eisosome protein Pil1 forms linear cortical filaments in fission yeast cells and that purified Pil1 assembles into filaments in vitro. In cells, Pil1 cortical filaments are excluded from regions of cell growth and are ...


Investigating Trna Release From The Bacterial Ribosome, Ian S. Farrell Aug 2011

Investigating Trna Release From The Bacterial Ribosome, Ian S. Farrell

Publicly Accessible Penn Dissertations

Translation of mRNA into proteins is integral in all living organisms, and takes place on the ribosome. In recent years, the X-ray crystal structures of biologically relevant ribosome complexes came into light, and the advance of kinetic studies was soon to follow, leading to a better understanding of the general ribosomal mechanism. However, there still remains some ambiguity in certain ribosome functions.

Ribosomal protein L1 initially became relevant in the early 1980s when it was determined that ribosomes lacking L1 showed a decreased capacity for in vitro protein synthesis. Later, it was shown that the L1-stalk is a highly mobile ...


Mechanism Of Cyclin D1-Dependent Genomic Instability And Neoplastic Transformation, Laura Pontano Vaites Aug 2011

Mechanism Of Cyclin D1-Dependent Genomic Instability And Neoplastic Transformation, Laura Pontano Vaites

Publicly Accessible Penn Dissertations

Regulation of cyclin D1-dependent kinase activity is essential for cell cycle progression and DNA replication fidelity. Critically, impaired cyclin D1 phosphorylation and ubiquitin-mediated proteolysis following the G1/S transition drives neoplastic growth, suggesting that posttranslational regulation is required for cell homeostasis. Elucidation of mechanisms facilitating S-phase cyclin D1 accumulation and novel functions of nuclear cyclin D1/CDK4 kinase is critical for understanding the role of cyclin D1 in tumorigenesis. The work presented herein demonstrates that accelerated, Fbx4-dependent cyclin D1 degradation following S-phase DNA damage is essential to maintain genome stability. Furthermore, Fbx4 functions as a bona fide tumor suppressor, as ...


Role And Regulation Of Myosin Iia In Natural Killer Cell Cytotoxicity, Keri Sanborn Aug 2011

Role And Regulation Of Myosin Iia In Natural Killer Cell Cytotoxicity, Keri Sanborn

Publicly Accessible Penn Dissertations

Natural killer (NK) cells are lymphocytes of the innate immune system that provide defense by directing their cytotoxic activity against virally infected and tumorigenic cells. Target cell lysis requires directed secretion of lytic granule contents, including pore-forming perforin and apoptosis-inducing granzymes, at the contact site. During the formation of a mature immunological synapse (IS) with a target cell, an NK cell polymerizes filamentous actin (F-actin) at the contact site, which may serve as a barrier to secretion of lytic granules for cytotoxicity. An actin-based motor protein, nonmuscle myosin IIA, has been demonstrated to be required for NK cell cytotoxic activity ...


Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun Aug 2011

Serum- And Glucocorticoid-Induced Kinase 3 In Recycling Endosomes Mediates Acute Activation Of Na+/H+ Exchanger Nhe3 By Glucocorticoids, Peijian He, Sei-Jung Lee, Songbai Lin, Ursula Seidler, Florian Lang, Geza Fejes-Toth, Aniko Naray-Fejes-Toth, C. Chris Yun

Open Dartmouth: Faculty Open Access Scholarship

Na(+)/H(+) exchanger 3 (NHE3) is the major Na(+) transporter in the intestine. Serum- and glucocorticoid-induced kinase (SGK) 1 interacts with NHE regulatory factor 2 (NHERF2) and mediates activation of NHE3 by dexamethasone (Dex) in cultured epithelial cells. In this study, we compared short-term regulation of NHE3 by Dex in SGK1-null and NHERF2-null mice. In comparison to wild-type mice, loss of SGK1 or NHERF2 significantly attenuated regulation of NHE3 by Dex but did not completely obliterate the effect. We show that transfection of SGK2 or SGK3 in PS120 cells resulted in robust activation of NHE3 by Dex. However, unlike SGK1 ...


Investigating The Origin Of Coprolites From Three Great Basin Caves, Chelsey Vandrisse, Duane P. Moser, David Rhode Aug 2011

Investigating The Origin Of Coprolites From Three Great Basin Caves, Chelsey Vandrisse, Duane P. Moser, David Rhode

Undergraduate Research Opportunities Program (UROP)

The study of coprolites (mummified feces) is a relatively new endeavor, which enables investigations of the health and diet of ancient people and provides some of the oldest evidence to date for the human habitation in North America (2). In this project, 18 coprolites were examined from archeological digs at three Great Basin caves: the Bonneville Estates Rockshelter (UT), Hidden Cave (NV), and Top of the Terrace Rockshelter (UT). The main objectives were: 1) to verify human origin through the presence of mitochondrial DNA (mtDNA) and 2) assuming human origin, characterize intestinal microflora of Native Americans prior to European contact ...


Inactivation Of Spo0a Gene Increases Stationary Phase Mutagenesis In Bacillus Subtilis, Denisse Reyes, Amanda Prisbrey, Holly Martin, Eduardo Robleto Aug 2011

Inactivation Of Spo0a Gene Increases Stationary Phase Mutagenesis In Bacillus Subtilis, Denisse Reyes, Amanda Prisbrey, Holly Martin, Eduardo Robleto

Undergraduate Research Opportunities Program (UROP)

Stationary phase mutagenesis occurs when a population of cells acquires mutations conferring escape from nongrowing or stress conditions. This type of mutations is observed in nutritionally starved cells. Because the mutations occur after the onset of stress and in cells that are in non-replicative conditions, elucidating the underlying mechanisms contributes novel views to the process of evolution and apply to the formation of cancer in human cells and antibiotic resistance in microbial pathogens. Studies have shown that in Bacillus subtilis, the Mfd protein which is a transcription repair coupling factor is necessary for this phenomenon to occur. Here, we investigate ...