263 research outputs found
Increasing Utilization of Otago Fall Prevention Program by Nevada Physical Therapists: A Service-Learning Project
Otago is an evidence-based program that is designed to reduce falls in community dwelling older adults by individualizing an exercise program with three key components: strength, balance, and a walking program. Unfortunately, Nevada clinicians do not utilize the program frequently or entirely with patients in outpatient and/or home health physical therapy. Evidence shows it reduces fall risk, but it has barriers to implementation in the United States. The barriers to integration are primarily due to the plan of care that stems from a 12-month timeframe and several phone call appointments which does not fit well in the American healthcare system. In correspondence to the confusion of placing patients in a fall risk level through three screening measures and providing professional judgement for exercise progression. Our project aimed to break down barriers that hinder the use of Otago Exercise Program (OEP) in clinical practice in Nevada. Specifically, use the reduced program of 6 months versus 12 months, utilizing telehealth for the phone calls, added more descriptive terminology to the exercise manual, and provided case examples to increase confidence with exercise prescription and progression as well as provide an opportunity for professional development and education on three University of Nevada, Las Vegas (UNLV) physical therapy students
Amyloid prions in fungi
ABSTRACT
Prions are infectious protein polymers that have been found to cause fatal diseases in mammals. Prions have also been identified in fungi (yeast and filamentous fungi), where they behave as cytoplasmic non-Mendelian genetic elements. Fungal prions correspond in most cases to fibrillary Ξ²-sheet-rich protein aggregates termed amyloids. Fungal prion models and, in particular, yeast prions were instrumental in the description of fundamental aspects of prion structure and propagation. These models established the βprotein-onlyβ nature of prions, the physical basis of strain variation, and the role of a variety of chaperones in prion propagation and amyloid aggregate handling. Yeast and fungal prions do not necessarily correspond to harmful entities but can have adaptive roles in these organisms.</jats:p
Reinitiated viral RNA-dependent RNA polymerase resumes replication at a reduced rate
RNA-dependent RNA polymerases (RdRP) form an important class of enzymes that is responsible for genome replication and transcription in RNA viruses and involved in the regulation of RNA interference in plants and fungi. The RdRP kinetics have been extensively studied, but pausing, an important regulatory mechanism for RNA polymerases that has also been implicated in RNA recombination, has not been considered. Here, we report that RdRP experience a dramatic, long-lived decrease in its elongation rate when it is reinitiated following stalling. The rate decrease has an intriguingly weak temperature dependence, is independent of both the nucleotide concentration during stalling and the length of the RNA transcribed prior to stalling; however it is sensitive to RNA structure. This allows us to delineate the potential factors underlying this irreversible conversion of the elongation complex to a less active mode
Escherichia coli RNA polymerase-associated SWI/SNF protein RapA: evidence for RNA-directed binding and remodeling activity
Helicase-like SWI/SNF proteins are present in organisms belonging to distant kingdoms from bacteria to humans, indicating that they perform a very basic and ubiquitous form of nucleic acid management; current studies associate the activity of SWI/SNF proteins with remodeling of DNA and DNAβprotein complexes. The bacterial SWI/SNF homolog RapAβan integral part of the Escherichia coli RNA polymerase complexβhas been implicated in remodeling post-termination DNAβRNA polymeraseβRNA ternary complexes (PTC), however its explicit nucleic acid substrates and mechanism remain elusive. Our work presents evidence indicating that RNA is a key substrate of RapA. Specifically, the formation of stable RapAβRNA intermediates in transcription and other, independent lines of evidence presented herein indicate that RapA binds and remodels RNA during transcription. Our results are consistent with RapA promoting RNA release from DNAβRNA polymeraseβRNA ternary complexes; this process may be accompanied by the destabilization of non-canonical DNAβRNA complexes (putative DNAβRNA triplexes). Taken together, our data indicate a novel RNA remodeling activity for RapA, a representative of the SWI/SNF protein superfamily
Systematic In Vivo Analysis of the Intrinsic Determinants of Amyloid Ξ² Pathogenicity
Protein aggregation into amyloid fibrils and protofibrillar aggregates is associated with a number of the most common neurodegenerative diseases. We have established, using a computational approach, that knowledge of the primary sequences of proteins is sufficient to predict their in vitro aggregation propensities. Here we demonstrate, using rational mutagenesis of the AΞ²42 peptide based on such computational predictions of aggregation propensity, the existence of a strong correlation between the propensity of AΞ²42 to form protofibrils and its effect on neuronal dysfunction and degeneration in a Drosophila model of Alzheimer disease. Our findings provide a quantitative description of the molecular basis for the pathogenicity of AΞ² and link directly and systematically the intrinsic properties of biomolecules, predicted in silico and confirmed in vitro, to pathogenic events taking place in a living organism
Single-molecule experiments in biological physics: methods and applications
I review single-molecule experiments (SME) in biological physics. Recent
technological developments have provided the tools to design and build
scientific instruments of high enough sensitivity and precision to manipulate
and visualize individual molecules and measure microscopic forces. Using SME it
is possible to: manipulate molecules one at a time and measure distributions
describing molecular properties; characterize the kinetics of biomolecular
reactions and; detect molecular intermediates. SME provide the additional
information about thermodynamics and kinetics of biomolecular processes. This
complements information obtained in traditional bulk assays. In SME it is also
possible to measure small energies and detect large Brownian deviations in
biomolecular reactions, thereby offering new methods and systems to scrutinize
the basic foundations of statistical mechanics. This review is written at a
very introductory level emphasizing the importance of SME to scientists
interested in knowing the common playground of ideas and the interdisciplinary
topics accessible by these techniques. The review discusses SME from an
experimental perspective, first exposing the most common experimental
methodologies and later presenting various molecular systems where such
techniques have been applied. I briefly discuss experimental techniques such as
atomic-force microscopy (AFM), laser optical tweezers (LOT), magnetic tweezers
(MT), biomembrane force probe (BFP) and single-molecule fluorescence (SMF). I
then present several applications of SME to the study of nucleic acids (DNA,
RNA and DNA condensation), proteins (protein-protein interactions, protein
folding and molecular motors). Finally, I discuss applications of SME to the
study of the nonequilibrium thermodynamics of small systems and the
experimental verification of fluctuation theorems. I conclude with a discussion
of open questions and future perspectives.Comment: Latex, 60 pages, 12 figures, Topical Review for J. Phys. C (Cond.
Matt
A Hypermutable Insert in an Immunoglobulin Transgene Contains Hotspots of Somatic Mutation and Sequences Predicting Highly Stable Structures in the RNA Transcript
Optical Trapping with High Forces Reveals Unexpected Behaviors of Prion Fibrils
Amyloid fibrils are important in diverse cellular functions, feature in many human diseases and have potential applications in nanotechnology. Here we describe methods that combine optical trapping and fluorescent imaging to characterize the forces that govern the integrity of amyloid fibrils formed by a yeast prion protein. A crucial advance was to use the self-templating properties of amyloidogenic proteins to tether prion fibrils, enabling their manipulation in the optical trap. At normal pulling forces the fibrils were impervious to disruption. At much higher forces (up to 250 pN), discontinuities occurred in force-extension traces before fibril rupture. Experiments with selective amyloid-disrupting agents and mutations demonstrated that such discontinuities were caused by the unfolding of individual subdomains. Thus, our results reveal unusually strong noncovalent intermolecular contacts that maintain fibril integrity even when individual monomers partially unfold and extend fibril length.National Institutes of Health (U.S.) (Grant GM025874)National Science Foundation (U.S.). CAREER (Award 0643745
Identification of Spt5 Target Genes in Zebrafish Development Reveals Its Dual Activity In Vivo
Spt5 is a conserved essential protein that represses or stimulates transcription elongation in vitro. Immunolocalization studies on Drosophila polytene chromosomes suggest that Spt5 is associated with many loci throughout the genome. However, little is known about the prevalence and identity of Spt5 target genes in vivo during development. Here, we identify direct target genes of Spt5 using fogsk8 zebrafish mutant, which disrupts the foggy/spt5 gene. We identified that fogsk8 and their wildtype siblings differentially express less than 5% of genes examined. These genes participate in diverse biological processes from stress response to cell fate specification. Up-regulated genes exhibit shorter overall gene length compared to all genes examined. Through chromatin immunoprecipitation in zebrafish embryos, we identified a subset of developmentally critical genes that are bound by both Spt5 and RNA polymerase II. The protein occupancy patterns on these genes are characteristic of both repressive and stimulatory elongation regulation. Together our findings establish Spt5 as a dual regulator of transcription elongation in vivo and identify a small but diverse set of target genes critically dependent on Spt5 during development
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