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Full-Text Articles in Cell Biology

The Central Role Of The Tail In Switching Off 10s Myosin Ii Activity, Shixin Yang, Kyounghwan Lee, John L. Woodhead, Osamu Sato, Mitsuo Ikebe, Roger Craig Sep 2019

The Central Role Of The Tail In Switching Off 10s Myosin Ii Activity, Shixin Yang, Kyounghwan Lee, John L. Woodhead, Osamu Sato, Mitsuo Ikebe, Roger Craig

Radiology Publications and Presentations

Myosin II is a motor protein with two heads and an extended tail that plays an essential role in cell motility. Its active form is a polymer (myosin filament) that pulls on actin to generate motion. Its inactive form is a monomer with a compact structure (10S sedimentation coefficient), in which the tail is folded and the two heads interact with each other, inhibiting activity. This conformation is thought to function in cells as an energy-conserving form of the molecule suitable for storage as well as transport to sites of filament assembly. The mechanism of inhibition of the compact molecule ...


Biophysical Properties Of Cellular Membranes In Gram-Positive Bacterial Pathogens And Their Impact On Major Physiological Attributes And Virulence Determinants, Suranjana Sen Sep 2015

Biophysical Properties Of Cellular Membranes In Gram-Positive Bacterial Pathogens And Their Impact On Major Physiological Attributes And Virulence Determinants, Suranjana Sen

Theses and Dissertations

The cytoplasmic membrane of bacterial cells, forming an essential barrier from the surroundings, is a critical component of cellular physiology ensuring proper survival and maintenance of major cellular functions. The integrity of the membrane is an important feature that plays an essential role in the transport of solutes and nutrients through active and passive pathways, functions of membrane-associated proteins, electron transport and ATP synthesis, maintaining turgor pressure and combating environmental stresses, and thus is a crucial factor of a majority of cellular adaptations. The various biophysical properties affecting the integrity of this membrane are mainly determined by the composition and ...


Human Anatomy And Physiology Preparatory Course, Carlos Liachovitzky Jan 2015

Human Anatomy And Physiology Preparatory Course, Carlos Liachovitzky

Open Educational Resources

The overall purpose of this preparatory course textbook is to help students familiarize with some terms and some basic concepts they will find later in the Human Anatomy and Physiology I course.

The organization and functioning of the human organism generally is discussed in terms of different levels of increasing complexity, from the smallest building blocks to the entire body. This Anatomy and Physiology preparatory course covers the foundations on the chemical level, and a basic introduction to cellular level, organ level, and organ system levels. There is also an introduction to homeostasis at the beginning.


Characterization Of Calbindin Positive Interneurons Within The Ventral Horn Of The Mouse Spinal Cord, Taylor L. Floyd, David R. Ladle Jan 2015

Characterization Of Calbindin Positive Interneurons Within The Ventral Horn Of The Mouse Spinal Cord, Taylor L. Floyd, David R. Ladle

Browse All Celebration of Research, Scholarship, and Creative Activities Materials

Sensory-motor circuits in the spinal cord integrate sensory feedback from muscles and modulate locomotor behavior. Although we know how the sensory-motor system generally works, the main issue lies in identifying all neurons involved and understanding their interrelationships. Many interneurons contribute to sensory-motor circuits and have been well studied. For example, Renshaw cells (RC) are inhibitory interneurons that prevent motor neurons from over-activity. A distinguishing feature of RCs is that they are the only interneurons within the ventral-most region of the spinal cord expressing the calcium binding protein calbindin (CB). Recent studies have found other subpopulations of ventral horn interneurons outside ...


A Fap46 Mutant Provides New Insights Into The Function And Assembly Of The C1d Complex Of The Ciliary Central Apparatus, Jason M. Brown, Christen G. Dipetrillo, Elizabeth F. Smith, George B. Witman Apr 2012

A Fap46 Mutant Provides New Insights Into The Function And Assembly Of The C1d Complex Of The Ciliary Central Apparatus, Jason M. Brown, Christen G. Dipetrillo, Elizabeth F. Smith, George B. Witman

Open Dartmouth: Faculty Open Access Scholarship

Virtually all motile eukaryotic cilia and flagella have a '9+2' axoneme in which nine doublet microtubules surround two singlet microtubules. Associated with the central pair of microtubules are protein complexes that form at least seven biochemically and structurally distinct central pair projections. Analysis of mutants lacking specific projections has indicated that each may play a unique role in the control of flagellar motility. One of these is the C1d projection previously shown to contain the proteins FAP54, FAP46, FAP74 and FAP221/Pcdp1, which exhibits Ca(2+)-sensitive calmodulin binding. Here we report the isolation and characterization of a Chlamydomonas ...


Heterogeneity In Mitochondrial Morphology And Membrane Potential Is Independent Of The Nuclear Division Cycle In Multinucleate Fungal Cells, John P. Gerstenberger, Patricia Occhipinti, Amy S. Gladfelter Jan 2012

Heterogeneity In Mitochondrial Morphology And Membrane Potential Is Independent Of The Nuclear Division Cycle In Multinucleate Fungal Cells, John P. Gerstenberger, Patricia Occhipinti, Amy S. Gladfelter

Open Dartmouth: Faculty Open Access Scholarship

In the multinucleate filamentous fungus Ashbya gossypii, nuclei divide asynchronously in a common cytoplasm. We hypothesize that the division cycle machinery has a limited zone of influence in the cytoplasm to promote nuclear autonomy. Mitochondria in cultured mammalian cells undergo cell cycle-specific changes in morphology and membrane potential and therefore can serve as a reporter of the cell cycle state of the cytoplasm. To evaluate if the cell cycle state of nuclei in A. gossypii can influ


Axl2 Integrates Polarity Establishment, Maintenance, And Environmental Stress Response In The Filamentous Fungus Ashbya Gossypii, Jonathan F. Anker, Amy S. Gladfelter Oct 2011

Axl2 Integrates Polarity Establishment, Maintenance, And Environmental Stress Response In The Filamentous Fungus Ashbya Gossypii, Jonathan F. Anker, Amy S. Gladfelter

Open Dartmouth: Faculty Open Access Scholarship

In budding yeast, new sites of polarity are chosen with each cell cycle and polarization is transient. In filamentous fungi, sites of polarity persist for extended periods of growth and new polarity sites can be established while existing sites are maintained. How the polarity establishment machinery functions in these distinct growth forms found in fungi is still not well understood. We have examined the function of Axl2, a transmembrane bud site selection protein discovered in Saccharomyces cerevisiae, in the filamentous fungus Ashbya gossypii. A. gossypii does not divide by budding and instead exhibits persistent highly polarized growth, and multiple axes ...


A Conserved Cam- And Radial Spoke–Associated Complex Mediates Regulation Of Flagellar Dynein Activity, Erin E. Dymek, Elizabeth F. Smith Nov 2007

A Conserved Cam- And Radial Spoke–Associated Complex Mediates Regulation Of Flagellar Dynein Activity, Erin E. Dymek, Elizabeth F. Smith

Open Dartmouth: Faculty Open Access Scholarship

For virtually all cilia and eukaryotic flagella, the second messengers calcium and cyclic adenosine monophosphate are implicated in modulating dynein- driven microtubule sliding to regulate beating. Calmodulin (CaM) localizes to the axoneme and is a key calcium sensor involved in regulating motility. Using immunoprecipitation and mass spectrometry, we identify members of a CaM-containing complex that are involved in regulating dynein activity. This complex includes flagellar-associated protein 91 (FAP91), which shares considerable sequence similarity to AAT-1, a protein originally identified in testis as an A-kinase anchor protein (AKAP)- binding protein. FAP91 directly interacts with radial spoke protein 3 (an AKAP), which ...


The Yeast Integral Membrane Protein Apq12 Potentially Links Membrane Dynamics To Assembly Of Nuclear Pore Complexes, John J. Scarcelli, Christin A. Hodge, Charles N. Cole Aug 2007

The Yeast Integral Membrane Protein Apq12 Potentially Links Membrane Dynamics To Assembly Of Nuclear Pore Complexes, John J. Scarcelli, Christin A. Hodge, Charles N. Cole

Open Dartmouth: Faculty Open Access Scholarship

Although the structure and function of components of the nuclear pore complex (NPC) have been the focus of many studies, relatively little is known about NPC biogenesis. In this study, we report that Apq12 is required for efficient NPC biogenesis in Saccharomyces cerevisiae. Apq12 is an integral membrane protein of the nuclear envelope (NE) and endoplasmic reticulum. Cells lacking Apq12 are cold sensitive for growth, and a subset of their nucleoporins (Nups), those that are primarily components of the cytoplasmic fibrils of the NPC, mislocalize to the cytoplasm. APQ12 deletion also causes defects in NE morphology. In the absence of ...


Regulation Of Meiotic Cohesion And Chromosome Core Morphogenesis During Pachytene In Drosophila Oocytes, Radhika S. Khetani, Sharon E. Bickel Jul 2007

Regulation Of Meiotic Cohesion And Chromosome Core Morphogenesis During Pachytene In Drosophila Oocytes, Radhika S. Khetani, Sharon E. Bickel

Open Dartmouth: Faculty Open Access Scholarship

During meiosis, cohesion between sister chromatids is required for normal levels of homologous recombination, maintenance of chiasmata and accurate chromosome segregation during both divisions. In Drosophila, null mutations in the ord gene abolish meiotic cohesion, although how ORD protein promotes cohesion has remained elusive. We show that SMC subunits of the cohesin complex colocalize with ORD at centromeres of ovarian germ-line cells. In addition, cohesin SMCs and ORD are visible along the length of meiotic chromosomes during pachytene and remain associated with chromosome cores following DNase I digestion. In flies lacking ORD activity, cohesin SMCs fail to accumulate at oocyte ...


The Yeast Orthologue Of Grasp65 Forms A Complex With A Coiled-Coil Protein That Contributes To Er To Golgi Traffic, Rudy Behnia, Francis A. Barr, John J. Flanagan, Charles Barlowe, Sean Munro Jan 2007

The Yeast Orthologue Of Grasp65 Forms A Complex With A Coiled-Coil Protein That Contributes To Er To Golgi Traffic, Rudy Behnia, Francis A. Barr, John J. Flanagan, Charles Barlowe, Sean Munro

Open Dartmouth: Faculty Open Access Scholarship

The mammalian Golgi protein GRASP65 is required in assays that reconstitute cisternal stacking and vesicle tethering. Attached to membranes by an N-terminal myristoyl group, it recruits the coiled-coil protein GM130. The relevance of this system to budding yeasts has been unclear, as they lack an obvious orthologue of GM130, and their only GRASP65 relative (Grh1) lacks a myristoylation site and has even been suggested to act in a mitotic checkpoint. In this study, we show that Grh1 has an N-terminal amphipathic helix that is N-terminally acetylated and mediates association with the cis-Golgi. We find that Grh1 forms a complex with ...


Following Temperature Stress, Export Of Heat Shock Mrna Occurs Efficiently In Cells With Mutations In Genes Normally Important For Mrna Export, Christiane Rollenhagen, Christine A. Hodge, Charles N. Cole Jan 2007

Following Temperature Stress, Export Of Heat Shock Mrna Occurs Efficiently In Cells With Mutations In Genes Normally Important For Mrna Export, Christiane Rollenhagen, Christine A. Hodge, Charles N. Cole

Open Dartmouth: Faculty Open Access Scholarship

Heat shock leads to accumulation of polyadenylated RNA in nuclei of Saccharomyces cerevisiae cells, transcriptional induction of heat shock genes, and efficient export of polyadenylated heat shock mRNAs. These studies were conducted to examine the requirements for export of mRNA following heat shock. We used in situ hybridization to detect SSA4 mRNA (encoding Hsp70) and flow cytometry to measure the amount of Ssa4p-green fluorescent protein (GFP) produced following heat shock. Npl3p and Yra1p are mRNA-binding proteins recruited to nascent mRNAs and are essential for proper mRNA biogenesis and export. Heat shock mRNA was exported efficiently in temperature-sensitive npl3, yra1, and ...


Self-Consistent Analyses For Potential Conduction Block In Nerves By An Ultrashort High-Intensity Electric Pulse, R. P. Joshi, A. Mishra, Q. Hu, K. H. Schoenbach, A. Pakhomov Jan 2007

Self-Consistent Analyses For Potential Conduction Block In Nerves By An Ultrashort High-Intensity Electric Pulse, R. P. Joshi, A. Mishra, Q. Hu, K. H. Schoenbach, A. Pakhomov

Bioelectrics Publications

Simulation studies are presented that probe the possibility of using high-field (>100kV ∕ cm), short-duration (∼50ns) electrical pulses for nonthermal and reversible cessation of biological electrical signaling pathways. This would have obvious applications in neurophysiology, clinical research, neuromuscular stimulation therapies, and even nonlethal bioweapons development. The concept is based on the creation of a sufficiently high density of pores on the nerve membrane by an electric pulse. This modulates membrane conductance and presents an effective "electrical short" to an incident voltage wave traveling across a nerve. Net blocking of action potential propagation can then result. A continuum approach based on the ...


Limited Functional Redundancy And Oscillation Of Cyclins In Multinucleated Ashbya Gossypii Fungal Cells, A. Katrin Hungerbuehler, Peter Philippsen, Amy S. Gladfelter Nov 2006

Limited Functional Redundancy And Oscillation Of Cyclins In Multinucleated Ashbya Gossypii Fungal Cells, A. Katrin Hungerbuehler, Peter Philippsen, Amy S. Gladfelter

Open Dartmouth: Faculty Open Access Scholarship

Cyclin protein behavior has not been systematically investigated in multinucleated cells with asynchronous mitoses. Cyclins are canonical oscillating cell cycle proteins, but it is unclear how fluctuating protein gradients can be established in multinucleated cells where nuclei in different stages of the division cycle share the cytoplasm. Previous work in A. gossypii, a filamentous fungus in which nuclei divide asynchronously in a common cytoplasm, demonstrated that one G1 and one B-type cyclin do not fluctuate in abundance across the division cycle. We have undertaken a comprehensive analysis of all G1 and B-type cyclins in A. gossypii to determine whether any ...


Talking To Themselves: Autoregulation And Quorum Sensing In Fungi, Deborah A. Hogan Apr 2006

Talking To Themselves: Autoregulation And Quorum Sensing In Fungi, Deborah A. Hogan

Open Dartmouth: Faculty Open Access Scholarship

Extracellular autoinducing compounds in the supernatants of microbial cultures were first recognized for their roles in the induction of genetic competence in gram-positive bacteria and in the regulation of light production in marine vibrios. In 1994, this form of population-level regulation in microbes was dubbed “quorum sensing” since it enabled bacterial cells to chemically measure the density of the surrounding population. Subsequently, many examples of cell density-dependent regulation by extracellular factors have been found in diverse microorganisms. The widespread incidence of diverse quorum-sensing systems strongly suggests that regulation in accordance with cell density is important for the success of microbes ...


Calmodulin And Pf6 Are Components Of A Complex That Localizes To The C1 Microtubule Of The Flagellar Central Apparatus, Matthew J. Wargo, Erin E. Dymek, Elizabeth F. Smith Jul 2005

Calmodulin And Pf6 Are Components Of A Complex That Localizes To The C1 Microtubule Of The Flagellar Central Apparatus, Matthew J. Wargo, Erin E. Dymek, Elizabeth F. Smith

Open Dartmouth: Faculty Open Access Scholarship

Studies of flagellar motility in Chlamydomonas mutants lacking specific central apparatus components have supported the hypothesis that the inherent asymmetry of this structure provides important spatial cues for asymmetric regulation of dynein activity. These studies have also suggested that specific projections associated with the C1 and C2 central tubules make unique contributions to modulating motility; yet, we still do not know the identities of most polypeptides associated with the central tubules. To identify components of the C1a projection, we took an immunoprecipitation approach using antibodies generated against PF6. The pf6 mutant lacks the C1a projection and possesses flagella that only ...


Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor Mar 2003

Minus-End Capture Of Preformed Kinetochore Fibers Contributes To Spindle Morphogenesis, Alexey Khodjakov, Lily Copenagle, Michael B. Gordon, Duane A. Compton, Tarun M. Kapoor

Open Dartmouth: Faculty Open Access Scholarship

Near-simultaneous three-dimensional fluorescence/differential interference contrast microscopy was used to follow the behavior of microtubules and chromosomes in living alpha-tubulin/GFP-expressing cells after inhibition of the mitotic kinesin Eg5 with monastrol. Kinetochore fibers (K-fibers) were frequently observed forming in association with chromosomes both during monastrol treatment and after monastrol removal. Surprisingly, these K-fibers were oriented away from, and not directly connected to, centrosomes and incorporated into the spindle by the sliding of their distal ends toward centrosomes via a NuMA-dependent mechanism. Similar preformed K-fibers were also observed during spindle formation in untreated cells. In addition, upon monastrol removal, centrosomes established ...


Asymmetry Of The Central Apparatus Defines The Location Of Active Microtubule Sliding In Chlamydomonas Flagella, Matthew J. Wargo, Elizabeth F. Smith Jan 2003

Asymmetry Of The Central Apparatus Defines The Location Of Active Microtubule Sliding In Chlamydomonas Flagella, Matthew J. Wargo, Elizabeth F. Smith

Open Dartmouth: Faculty Open Access Scholarship

Regulation of ciliary and flagellar motility requires spatial control of dynein-driven microtubule sliding. However, the mechanism for regulating the location and symmetry of dynein activity is not understood. One hypothesis is that the asymmetrically organized central apparatus, through interactions with the radial spokes, transmits a signal to regulate dynein-driven microtubule sliding between subsets of doublet microtubules. Based on this model, we hypothesized that the orientation of the central apparatus defines positions of active microtubule sliding required to control bending in the axoneme. To test this, we induced microtubule sliding in axonemes isolated from wild-type and mutant Chlamydomonas cells, and then ...


Improved Energy Model For Membrane Electroporation In Biological Cells Subjected To Electrical Pulses, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson Jan 2002

Improved Energy Model For Membrane Electroporation In Biological Cells Subjected To Electrical Pulses, R. P. Joshi, Q. Hu, K. H. Schoenbach, H. P. Hjalmarson

Bioelectrics Publications

A self-consistent model analysis of electroporation in biological cells has been carried out based on an improved energy model. The simple energy model used in the literature is somewhat incorrect and unphysical for a variety of reasons. Our model for the pore formation energy E(r) includes a dependence on pore population and density. It also allows for variable surface tension, incorporates the effects of finite conductivity on the electrostatic correction term, and is dynamic in nature. Self-consistent calculations, based on a coupled scheme involving the Smoluchowski equation and the improved energy model, are presented. It is shown that E ...


Effect Of The Presence Of The Mammary Gland On Periparturient Immunosuppression In Dairy Cows , Kayoko Kimura Jan 1999

Effect Of The Presence Of The Mammary Gland On Periparturient Immunosuppression In Dairy Cows , Kayoko Kimura

Retrospective Theses and Dissertations

Impaired neutrophil and lymphocyte function during the periparturient period is a contributing factor to the high incidence of infectious disease observed in the periparturient cow. Using 8 multiparous Jersey cows, we demonstrated that populations of T cells, especially T helper cells and gd T cells declined during the periparturient period coincident with reported losses of immune cell function;We hypothesized that milk production may be an important immunosuppressive factor. To test this hypothesis, we used 10 mastectomized and 8 intact multiparous Jersey cows and examined phenotype of peripheral blood mononuclear cells (PBMC), adhesion molecule expression and myeloperoxidase activity in neutrophils ...


Mechanisms Of Arginine Vasopressin-Induced Insulin Secretion In Rinm5f Cells , Ter-Hsin Chen Jan 1996

Mechanisms Of Arginine Vasopressin-Induced Insulin Secretion In Rinm5f Cells , Ter-Hsin Chen

Retrospective Theses and Dissertations

The present study was to investigate the mechanism by which AVP increases insulin secretion in RINm5F cells. A specific PLC inhibitor, U-73122, and a PLA2 inhibitor, N-(p-amylcinnamoyl)anthranilic acid (ACA) were used. U-73122 (2-8 [mu]M) inhibited the AVP-induced increases in the intracellular concentration of inositol 1,3,4-trisphosphate and (Ca2+]i dose-dependently. U-73122 (8 [mu]M) abolished the AVP's effect on IP3 and (Ca2+]i, but it only reduced the AVP-induced increase in insulin secretion by 35%. The discrepancy between the results of (Ca2+]i and insulin secretion may be due to the multiple signal transduction pathways ...


Biochemical Composition Of The Spermatozoal Plasma Membrane In Normal And Heat-Stressed Boars , Gary Carl Althouse Jan 1992

Biochemical Composition Of The Spermatozoal Plasma Membrane In Normal And Heat-Stressed Boars , Gary Carl Althouse

Retrospective Theses and Dissertations

The biochemical composition of ejaculated spermatozoal plasma membranes from normal-control (n = 4) and heat-stressed (n = 4) paired, sibling boars was assessed over a 9-week collection period. A total of 36 ejaculates were collected from the normal-control boars. Phospholipids (PL) accounted for 83.5% of the membrane lipid material, with sterols making up the remaining 16.5%. Phosphatidylcholine was the most abundant PL (56.6%), followed by sphingomyelin (16.6%), phosphatidylglycerides (11.0%), lysophosphatidylcholine (9.0%), phosphatidylethanolamine (5.8%), and phosphatidylinositol (1.0%). Cholesterol was the major sterol found in the sperm's plasma membrane (72.1%), with desmosterol being the ...


Atp-Dependent Formation And Motility Of Aster-Like Structures With Isolated Calf Brain Microtubule Proteins., Richard C. Weisenberg, Robert D. Allen, Shinya Inoue Mar 1986

Atp-Dependent Formation And Motility Of Aster-Like Structures With Isolated Calf Brain Microtubule Proteins., Richard C. Weisenberg, Robert D. Allen, Shinya Inoue

Open Dartmouth: Faculty Open Access Scholarship

Microtubule proteins isolated from calf brain will undergo gelation-contraction in the presence of ATP. We have now examined this process by video-enhanced contrast microscopy. After ATP addition to steady-state microtubules, slow (1-5 micron/min), linear movements of particles and microtubules toward aggregation centers occur. The resulting structures resemble mitotic spindle asters. During the time when gel contraction occurs, asters move (at 1-5 micron/min) toward other nearby asters. This is accompanied by the apparent shortening of the microtubules running between the asters. This is the first example of isolated microtubules undergoing a process that has similarities to half-spindle shortening during ...