A5030709873- Microtubule and mitosis dynamics
- Photosynthetic Processes and Mechanisms
- Protist diversity and phylogeny
- Genetic and Kidney Cyst Diseases
- Advanced Electron Microscopy Techniques and Applications
- Cellular transport and secretion
- Micro and Nano Robotics
- Fungal and yeast genetics research
- Genomics and Chromatin Dynamics
- Chromosomal and Genetic Variations
- Electron and X-Ray Spectroscopy Techniques
- Genetics, Aging, and Longevity in Model Organisms
- Nuclear Structure and Function
- Lipid Membrane Structure and Behavior
- Plant nutrient uptake and metabolism
- Blood properties and coagulation
- Mitochondrial Function and Pathology
- RNA Research and Splicing
- Cellular Mechanics and Interactions
- Neuroscience and Neuropharmacology Research
- Photoreceptor and optogenetics research
- Platelet Disorders and Treatments
- Algal biology and biofuel production
- Erythrocyte Function and Pathophysiology
- Prenatal Screening and Diagnostics
University of Colorado System
2005-2025
University of Colorado Boulder
2015-2024
Trinity College Dublin
2014-2018
Institut thématique Génétique, génomique et bioinformatique
2015
Washington University in St. Louis
2013
Yale University
2007
Cornell University
2007
SUNY Upstate Medical University
2004
Max Planck Society
2003
Harvard University
1999
Dynamin 1 is a neuron-specific guanosine triphosphatase thought to be critically required for the fission reaction of synaptic vesicle endocytosis. Unexpectedly, mice lacking dynamin were able form functional synapses, even though their postnatal viability was limited. However, during spontaneous network activity, branched, tubular plasma membrane invaginations accumulated, capped by clathrin-coated pits, in synapses 1–knockout mice. Synaptic endocytosis severely impaired strong exogenous...
The three dimensional organization of microtubules in mitotic spindles the yeast Saccharomyces cerevisiae has been determined by computer-aided reconstruction from electron micrographs serially cross-sectioned spindles. Fifteen ranging length 0.6-9.4 microns have analyzed. Ordered microtubule packing is absent up to 0.8 micron, but total number sufficient allow one per kinetochore with a few additional that may form an interpolar spindle. An obvious bundle about eight was found 1.3-1.6 long,...
Nucleus-vacuole (NV) junctions in Saccharomyces cerevisiae are formed through specific interactions between Vac8p on the vacuole membrane and Nvj1p nuclear envelope. Herein, we report that NV yeast promotepiecemeal microautophagy of thenucleus (PMN). During PMN, teardrop-like blebs pinched from nucleus, released into lumen, degraded by soluble hydrolases. PMN occurs rapidly dividing cells but is induced to higher levels carbon nitrogen starvation under control Tor kinase nutrient-sensing...
Researchers have used transmission electron microscopy (TEM) to make contributions cell biology for well over 50 years, and TEM continues be an important technology in our field. We briefly present the neophyte components of a TEM-based study, beginning with sample preparation through imaging samples. point out limitations issues considered during experimental design. Advanced techniques are listed as well. Finally, we potential new users resources help launch their project.
Electrophysiological studies of excitable organs usually focus on action potential (AP)-generating cells, whereas nonexcitable cells are generally considered as barriers to electrical conduction. Whether may modulate cell function or even contribute AP conduction via direct electrotonic coupling AP-generating is unresolved in the heart: such present vitro, but conclusive evidence situ lacking. We used genetically encoded voltage-sensitive fluorescent protein 2.3 (VSFP2.3) monitor...
We used electron tomography to examine microtubules (MTs) growing from pure tubulin in vitro as well two classes of MTs cells six species. The tips all these display bent protofilaments (PFs) that curve away the MT axis, contrast with previously reported whose are either blunt or sheetlike. Neither high pressure nor freezing is responsible for PF curvatures we see. PFs on and shortening similar; most curved at their tips, suggesting guanosine triphosphate–tubulin solution must straighten be...
The spindle pole body (SPB) is the major microtubule-organizing center of budding yeast and functional equivalent centrosome in higher eukaryotic cells. We used fast-frozen, freeze-substituted cells conjunction with high-voltage electron tomography to study fine structure SPB events early formation. Individual structures were imaged at 5-10 nm resolution three dimensions, significantly better than can be achieved by serial section microscopy. organized distinct but coupled layers, two which...
Microtubule dynamics vary during the cell cycle, and microtubules appear to be more dynamic in vivo than vitro. Proteins that promote instability are therefore central microtubule behavior living cells. Here, we report a yeast protein of highly conserved EB1 family, Bim1p, promotes cytoplasmic specifically G1. During G1, cells lacking BIM1 showed reduced dynamicity due slower shrinkage rate, fewer rescues catastrophes, time spent an attenuated/paused state. Human was identified as...
β-Catenin plays important roles in cell adhesion and gene transcription, has been shown recently to be essential for the establishment of a bipolar mitotic spindle. Here we show that β-catenin is component interphase centrosomes stabilization β-catenin, mimicking mutations found cancers, induces centrosome splitting. Centrosomes are held together by dynamic linker regulated Nek2 kinase its substrates C-Nap1 (centrosomal Nek2-associated protein 1) Rootletin. We binds phosphorylated Nek2,...
We have analyzed the fine structure of 10 chromosomal fibers from mitotic spindles PtK1 cells in metaphase and anaphase, using electron microscopy serial thin sections computer image processing to follow trajectories component microtubules (MTs) three dimensions. Most kinetochore MTs ran their vicinity pole, retaining a clustered arrangement over entire length. This MT bundle was invaded by large numbers other that were not associated with kinetochores. The invading frequently came close...
We have used computer averaging of electron micrographs from longitudinal and cross-sections wild-type mutant axonemes to determine the arrangement inner dynein arms in Chlamydomonas reinhardtii. Based on biochemical morphological data, previously been described as consisting three distinct subspecies, I1, I2, I3. Our averages revealed 10 distinguishable lobes density per 96-nm repeating unit row arms. These occurred predominantly but not exclusively two parallel rows. analyzed strains that...
Mice lacking expression of dynamin 1, a GTPase implicated in the fission reaction synaptic vesicle endocytosis, fail to thrive and exhibit severe activity-dependent endocytic defects at their synapses. Here, we have used electron tomography investigate massive increase clathrin-coated pit abundance that is selectively observed subset synapses 1 KO primary neuron cultures under conditions spontaneous network activity. This increase, leading branched tubular plasma membrane invaginations...
The exocytosis of synaptic vesicles (SVs) elicited by potent stimulation is rapidly compensated bulk endocytosis SV membranes leading to large endocytic vacuoles ('bulk' endosomes). Subsequently, these disappear in parallel with the reappearance new SVs. We have used synapses dynamin 1 and 3 double knock-out neurons, where clathrin-mediated (CME) dramatically impaired, gain insight into poorly understood mechanisms underlying this process. Massive formation endosomes was not defective, but...
The formation of a functional spindle requires microtubule (MT) nucleation from within the spindle, which depends on augmin. How augmin contributes to MT and organization is not known because augmin-dependent MTs have never been specifically visualized. In this paper, we identify their connections other by electron tomography 3D modeling. metaphase spindles human cells, minus ends were located both around centriole in body spindle. When was knocked down, latter population significantly...
Previous studies of flagellar mutants have identified six axonemal polypeptides as components a "dynein regulatory complex" (DRC). The DRC is though to coordinate the activity multiple dyneins, but its location within axoneme has been unknown (Huang et al., 1982; Piperno 1992). We used improved chromatographic procedures (Kagami and Kamiya, 1992) computer averaging EM images (Mastronarde analyze relationship between dynein arms. Our results suggest that some are located at base second radial...