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Software Defined Pulse Processing (SDPP) for Radiation Detection

Radiation detectors are typically instrumented with low noise preamplifiers that generate voltage pulses in response to energy deposits from particles (x-rays, gamma-rays, neutrons, protons, muons, etc.). This preamplifier signal must be further processed in order to improve the signal to noise ratio, and then subsequently estimate various properties of the pulse such as the pulse amplitude, timing, and shape. Historically, this “pulse processing” was carried out with complex, purpose-built analog electronics. With the advent of digital computing and fast analog to digital converters, this type of processing can be carried out in the digital domain.There are a number of commercial products that perform “hardware” digital pulse processing. The common element among these offerings is that the pulse processing algorithms are implemented in hardware (typically an FPGA or high performance DSP chip). However this hardware approach is expensive, and it's hard to tailor for a specific detector and application.To address these issues, researchers at UC Berkeley developed a solution that performs the pulse processing in software on a general purpose computer, using digital signal processing techniques. The only required hardware is a general purpose, high speed analog to digital converter that's capable of streaming the digitized detector preamplifier signal into computer memory without gaps. The Berkeley approach is agnostic to the hardware, and is implemented in such a way as to accommodate various hardware front-ends. For example, a Berkeley implementation uses the PicoScope 3000 and 5000 series USB3 oscilloscopes as the hardware front-end. That setup has been used to process the signal from a number of semiconductor and scintillator detectors, with results that are comparable to analog and hardware digital pulse processors.In comparison to current hardware solutions, this new software solution is much less expensive, and much more easily configurable. More specifically, the properties of the digital pulse shaping filter, trigger criteria, methods for estimating the pulse parameters, and formatting/filtering of the output data can be adjusted and tuned by writing simple C/C++ code.

Composition and Methods of a Nuclease Chain Reaction for Nucleic Acid Detection

This invention leverages the nuclease activity of CRISPR proteins for the direct, sensitive detection of specific nucleic acid sequences. This all-in-one detection modality includes an internal Nuclease Chain Reaction (NCR), which possesses an amplifying, feed-forward loop to generate an exponential signal upon detection of a target nucleic acid.Cas13 or Cas12 enzymes can be programmed with a guide RNA that recognizes a desired target sequence, activating a non-specific RNase or DNase activity. This can be used to release a detectable label. On its own, this approach is inherently limited in sensitivity and current methods require an amplification of genetic material before CRISPR-base detection. 

COMPOSITIONS AND METHODS FOR IDENTIFYING HOST CELL TARGET PROTEINS FOR TREATING RNA VIRUS INFECTIONS

Viral infection is a multistep process involving complex interplay between viral life cycle and host immunity. One defense mechanism that hosts use to protect cells against the virus are nucleic-acid-mediated surveillance systems, such as RNA interference-driven gene silencing and CRISPR-Cas mediated gene editing. Another important stage for host cells to combat virus replication is translational regulation, which is particular important for the life cycle of RNA viruses, such as Hepatitis C virus and Coronavirus.  While efforts to characterize structural features of viral RNA have led to a better understanding of translational regulation, no systematical approaches to identify important host genes for controlling viral translation have been developed and little is known about how to regulate host-virus translational interaction to prevent and treat infections caused by RNA viruses.   UC Berkeley researchers have developed a high-throughput platform using CRISPR-based target interrogation to identify new therapeutics targets or repurposed drug targets for blocking viral RNA translation.  The new kits can also be used to identify important domains within target proteins that are required for regulating (viral RNA translation) and can inform drug design and development for treating RNA viruses.

Chimeric Cas9 Variants With Novel Engineered Enzymatic Activities

In this invention, the HNH domain of a Cas9 is replaced by a domain that could have diverse enzymatic activities. This invention enables engineering of Cas9 chimeras that possess novel, conformation-sensitive enzymatic activity to perform specific genome editing in vitro, in vivo, and ex vivo.Prior to this invention, all of the strategies to engineer Cas9 fusion proteins and provide Cas9 with non-natural enzymatic activity for genome manipulations were engineered by fusing specific domains to the N- or C-terminus of Cas9 via long and flexible linkers, or through domain insertion approach. The disadvantages of these synthetic Cas9 chimeras are that the attached domain is on the long flexible linker, and it is very dynamic. Thus, these fusions have a broad activity window and they are large, which makes it difficult to deliver them to the cells. 

Decorating Chromatin for Precise Genome Editing Using CRISPR

A novel fusion construct that fuses Cas9 to a truncated version of human PRDM9 with the purpose of improving precise genome editing via homologous direceted repair (HDR). PRDM9 is a protein that deposits histone marks H3K4me3 and H3K36me3 simultaneously during meiosis to mark recombination hot spots where crossover occurs and is resolved by homologous recombination. H3K36me3 has also been demonstrated to be required upstream of homologous recombination repair after double stranded breaks (DSBs) and during V(D)J recombination for adaptive immunity. Recent evidence suggests PRDM9 acts as a pioneer factor opening closed chromatin. The newly engineered PRDM9C-Cas9 fusion construct shows increased HDR and decreased non-homologous end joining mediated insertions and deletions (indels).

Single Conjugative Vector for Genome Editing by RNA-guided Transposition

The inventors have constructed conjugative plasmids for intra- and inter-species delivery and expression of RNA-guided CRISPR-Cas transposases for organism- and site-specific genome editing by targeted transposon insertion. This invention enables integration of large, customizable DNA segments (encoded within a transposon) into prokaryotic genomes at specific locations and with low rates of off-target integration.

Temporal Control over DNA-Patterned Signaling Ligands In Vitro Using Sequence-Targeting Nucleases

UC Berkeley researchers have created a new technique that can rapidly “print” two-dimensional arrays of cells and proteins that mimic a wide variety of cellular environments in the body, be it the brain tissue surrounding a neural stem cell, the lining of the intestine or liver or the cellular configuration inside a tumor.  In the new technique, each cell or protein is tethered to a substrate with a short string of DNA. While similar methods have been developed that attach tethered cells or proteins one by one.  By repeating the process, up to 10 different kinds of cells or proteins can be tethered to the surface in an arbitrary pattern. This technique could help scientists develop a better understanding of the complex cell-to-cell messaging that dictates a cell’s final fate, from neural stem cell differentiating into a brain cell to a tumor cell with the potential to metastasize to an embryonic stem cell becoming an organ cell.

Cellular Potassium Imaging Using A Ratiometric Fluorescent Sensor

The inventors developed a ratiometric fluorescent small molecule probe for potassium ion detection composed of a duo-fluorophore system (KR-1). UV-vis detector and fluorometer measurement support ratiometric response of the probe towards potassium ion concentration. The probe was further applied to cellular potassium level detection using confocal microscope imaging technique. KR-1 enables simple determination of potassium levels in various cancer or non-cancer cell lines.

DEVICES AND METHODS FOR GENERATING OLIGODENDROCYTE PROGENITOR CELLS

The emergence of several cell based therapy candidates in the clinic is an encouraging sign for human diseases/disorders that currently have no effective small molecule or biologic based therapy. Stem cells – including adult and pluripotent subtypes – offer tremendous clinical promise for the treatment of a variety of degenerative diseases, as these cells have the capacity to self-renew indefinitely and to mature into functional cell types and thereby serve as a source of cell replacement therapies (CRTs) and pluripotent stem cells (hPSCs) are of increasing interest for the development of CRTs because of their capacity to differentiate into all cell types in an adult, for which adult tissue-specific stem cells may in some cases not even exist. One potential CRT enabled by hPSCs is oligodendrocyte progenitor cells (OPCs) for the treatment of spinal cord injury (SCI). Such hPSC-OPCs have recently advanced to a Phase II clinical trial and are even being considered for additional diseases in the central nervous system (CNS), such as multiple sclerosis (MS), or injury from radiation.   UC researchers have developed a microscale 3D culture screening and analysis methodology that is relevant to the production of several up and coming cell replacement therapy candidates for which derivation from a precursor cell type requires searching through a large in vitro design space of doses, durations, dynamics, and combinations of signaling cues over several weeks of culture, such as oligodendrocyte progenitor cells (OPCs) and midbrain dopaminergic neurons (mDA neurons) derived from human pluripotent stem cells. 

CRISPR-CAS EFFECTOR POLYPEPTIDES AND METHODS OF USE THEREOF

The CRISPR-Cas system is now understood to confer bacteria and archaea with acquired immunity against phage and viruses. CRISPR-Cas systems consist of Cas proteins, which are involved in acquisition, targeting and cleavage of foreign DNA or RNA, and a CRISPR array, which includes direct repeats flanking short spacer sequences that guide Cas proteins to their targets.  Class 2 CRISPR-Cas are streamlined versions in which a single Cas protein bound to RNA is responsible for binding to and cleavage of a targeted sequence. The programmable nature of these minimal systems has facilitated their use as a versatile technology that is revolutionizing the field of genome manipulation.  Current CRISPR Cas technologies are based on systems from cultured bacteria, leaving untapped the vast majority of organisms that have not been isolated.  There is a need in the art for additional Class 2 CRISPR/Cas systems (e.g., Cas protein plus guide RNA combinations).     UC Berkeley researchers discovered a new type of Cas 12 protein.  Site-specific binding and/or cleavage of a target nucleic acid (e.g., genomic DNA, ds DNA, RNA, etc.) can occur at locations (e.g., target sequence of a target locus) determined by base-pairing complementarity between the Cas12 guide RNA (the guide sequence of the Cas12 guide RNA) and the target nucleic acid.  Similar to CRISPR Cas9, Cas12 enzymes are expected to have a wide variety of applications in genome editing and nucleic acid manipulation.    

Multiplex Charge Detection Mass Spectrometry

Native mass spectrometry (MS), in which electrospray ionization (ESI) is used to transfer large macromolecules and macromolecular complexes directly from solution into the gas phase, is a powerful tool in structural biology.  However, charge-state distributions of individual components in mixtures of macromolecular complexes or synthetic polymers are often unresolved making it impossible to obtain mass information directly from an ESI mass spectrum. Other conventional methods can provide accurate masses of individual ions, but often at the expense of analysis time.     Weighing ions individually with charge detection mass spectrometry (CDMS) has the advantage that fast measurements are possible depending on the accuracy and sensitivity required. However, a limitation of trapping CDMS technology is the need to weigh single ions individually in order to eliminate potential interferences between the signals of multiple ions or ion-ion interactions that can potentially interfere with these measurements. UC researchers have created multiplex charge detection mass spectroscopy, particularly for high throughput single ion analysis of large molecules and measuring the masses of large molecules, macromolecular complexes and synthetic polymers that are too large or heterogeneous for conventional mass spectrometry measurements.  The new multiplexing method makes it possible to measure the masses of many ions simultaneously.  

Illumination Device for Dynamic Spatiotemporal Control of Photostimulation

A programmable LED device that illuminates multiple spatial locations (termed wells) with user-defined light patterns whose intensity can be modulated as a function of space and time. The devices are used for optogenetic stimulation of tissue culture plates (24-well and 96-well) kept in a heated and humidified tissue culture incubator, as well as photopatterning of hydrogels. In brief, light from LEDs passes through optical elements that ensure uniform illumination of each well. Parameters of the optical system, such as LED configuration, optical diffuser elements, materials, and geometry, were modeled and optimized using the optical ray tracing software Zemax OpticStudio. An electronics subsystem allows programmed control of illumination intensity and temporal sequences, with independent control of each well. Spatial precision is conveyed through a photomask attached to the culture plate. The hardware design also includes a cooling system and vibration isolation to reduce heating and damage to the sample. Lastly, a graphical user interface (GUI) was used to wirelessly program the illumination intensity and temporal sequences for each well. The devices can thus illuminate 24 independent channels with visible, NIR, or UV light with intensity ranges of 0 to 20-100 microwatts per millimeter-squared with 16-bit intensity resolution, and a temporal resolution of 1 millisecond and spatial resolution of 100 microns. In summary, the device allows uniform illumination of multiple wells for multiplexed photoactivation or photopolymerization of various substrates (light-responsive bacterial or mammalian cells grown in tissue culture, hydrogels, dyes, etc) with user-defined patterns. The device can be combined with a robotic handler, microscope, spectrometer, etc, to enable high-throughput illumination and simultaneous recording of the sample.

Targeted Ionophore-Based Metal Supplementation

Metal deficiency is implicated in a variety of genetic, neurological, cardiovascular, and metabolic diseases. Current approaches for addressing metal deficiency rely on generic metal ion supplementation, which can potentially lead to detrimental off-target metal accumulation in unwanted tissues and subsequently trigger oxidative stress and damage cascades. The inventors have developed a new modular platform for delivering metal ions in a tissue-specific manner and demonstrate liver-targeted copper supplementation as a proof of concept of this strategy. Specifically, the inventors designed and synthesized a N-acetylgalactosamine-functionalized ionophore, Gal-Cu(gtsm), to serve as a copper-carrying “Trojan Horse” that targets liver-localized asialoglycoprotein receptors (ASGPRs) and releases copper only after being taken up by cells, where the reducing intracellular environment triggers copper release from the ionophore. The inventors utilized a combination of bioluminescence imaging and inductively-coupled plasma mass spectrometry assays to establish ASGPR-dependent copper accumulation with this reagent in both liver cell culture and mouse models with minimal toxicity. The modular nature of this synthetic approach presages that this platform can be expanded to deliver a broader range of metals to specific cells, tissues, and organs in a more directed manner to treat metal deficiency in disease. This patent broadly covers directed metal delivery to select organs, tissues, and organelles.

Simultaneous Detection Of Protein Isoforms And Nucleic Acids From Low Starting Cell Numbers

Embryo-specific nucleic acid modifications, including retrotransposon activity-derived genomic modifications and alternative splicing of mRNA, is crucial for the development of mammalian embryos. However, determining if all genomic modifications and mRNA isoforms translate to protein variations remain intriguing questions due to difficulty in measuring protein isoforms and nucleic acids from small starting cell numbers.    UC Researchers have developed a system for performing dual nucleic acid and protein isoform measurements on low starting cell numbers equivalent to the number of blastomeres composing early embryonic development stages (morula and blastocysts).  The system integrates fractionation polyacrylamide gel electrophoresis (fPAGE) with off-chip analysis of nucleic acids in the nuclei. An additional method can be used to remove nuclei for off-chip analysis. The system can measure expression of protein isoforms from the cytoplasmic fraction of 1-100 cells while achieving analysis of either DNA or mRNA retained in the nuclei. The researchers have demonstrated signal from immunoprobed protein correlates strongly with protein expression prior to lysis in TurboGFP-expressing cells and that mRNA levels correlate with protein abundance in TurboGFP-expressing cells.

A Protein Inhibitor Of Cas9

  Clustered Regularly Interspaced Short Palindromic Repeat (CRISPR)/Cas9 nucleases, when complexed with a guide RNA, effect genome editing in a sequence-specific manner. RNA-guided Cas9 has proven to be a versatile tool for genome engineering in multiple cell types and organisms.  There is a need in the art for additional compositions and methods for controlling genome editing activity of CRISPR/Cas9.   UC Berkeley researchers have discovered a new protein that is able to inhibit the Cas9 protein from Staphyloccocus aureus (SauCas9). SauCas9 is smaller than the frequently used Cas9 from Streptococcus pyogenes, which has a number of benefits for delivery. The inhibitor is a small protein from a phage and is capable of strongly inhibiting gene editing in human cells.

NANOPORE MEMBRANE DEVICE AND METHODS OF USE THEREOF

Several chemical, physical, and biological techniques have been used for delivering macromolecules into living cells. Delivery of biomolecules into living cells is essential for biomedical research and drug development as well as genome editing. However, conventional methods of delivery of biomolecules such as viral vectors, cell penetrating peptides, cationic lipids, positive charged polymers, bulk electroporation, and microinjection pose several challenges. Such challenges include safety concerns, toxicity, damage to the cells, limited loading capacity, low delivery efficiencies, low cell viabilities, low cell throughput, high cellular perturbation, and high costs.  Thus, there is a need for delivery devices and methods that allow for permeabilization of the cell membrane to facilitate delivery of biomolecules into cells.   UC Berkeley researchers have developed a universal delivery electroporation system that makes cell transfection very simple for all of types of cells. The technology can be used to replace conventional cellular delivery methods such as cationic lipid, positive charged polymer and bulk electroporation as well as microinjection.  The system can deliver biomolecules (e.g., DNA, RNA, proteins, nucleic acid-protein complexes (e.g., RNPs)) or other reagents into all cell types, including T-cells, which cannot be efficiently transfected with conventional approaches.  

Cas12-mediated DNA Detection Reporter Molecules

Class 2 CRISPR-Cas systems are streamlined versions in which a single Cas protein (an effector protein, e.g., a type V Cas effector protein such as Cpf1) bound to RNA is responsible for binding to and cleavage of a targeted sequence. The programmable nature of these minimal systems has facilitated their use as a versatile technology that continues to revolutionize the field of genome manipulation.    Cas12 is an RNA-guided protein that binds and cuts any matching DNA sequence. Binding of the Cas12-CRISPR RNA (crRNA) complex to a matching single-stranded DNA (ssDNA) or double-stranded DNA (dsDNA) molecule activates the protein to non-specifically degrade any ssDNA in trans. Cas12a-dependent target binding can be coupled to a reporter molecule to provide a direct readout for DNA detection within a sample.  UC Berkeley researchers have developed compositions, systems, and kits having labeled single stranded reporter DNA molecules that provide a sensitive readout for detection of a target DNA. 

CRISPR-based Graphene Biosensor for Digital Detection of DNA Mutations

UC Berkeley and Keck Institute researchers have reported the development and testing of a graphene-based field-effect transistor that uses CRISPR technology to enable the digital detection of a target sequence within intact genomic material. Termed CRISPR–Chip, the biosensor uses the gene-targeting capacity of catalytically deactivated Cas9 complexed with a specific single-guide RNA and immobilized on the transistor to yield a label-free nucleic-acid-testing device whose output signal can be measured with a simple handheld reader.  

Tissue Projection Electrophoretic Separation Of Protein

A range of related immunoblotting methods have enabled the identification and semi-quantitative characterization of e.g., DNA (Southern blot), RNA (northern blot), proteins (Western blot), and protein-protein interactions (far-western blot); by coupling biomolecule separations and assays.  However, there are a wide number of alternative splicing events, post-translational modifications, and co-translational modifications (e.g., phosphorylation, glycosylation, and protein cleavage) that give rise to proteoforms and protein complexes with distinct function and subsequent cell behavior that cannot be analyzed with conventional methods such as immunohistochemistry (IHC). Analytical variability (lack of isoform- or complex-specific antibody probes), biological variability (small cell subpopulations diluted in bulk analysis), and lack of multiplexing (measurement of multiple proteins from the same tissues) can all render proteoforms and protein complexes undetectable by current technologies.     UC Berkeley researchers have created electrophoretic separation platform that is capable of measuring proteoforms and protein complexes lacking specific antibodies alongside spatial information, at the cellular level.  This platform maintains the architecture of 2D tissue slices while projecting a protein separation in the 3rd dimension. The platform mitigates artifacts induced by tissue dissociation processes, as the intact tissue is lysed and subject to a protein separation. The platform is also compatible with differential detergent fractionation methods for further separation of proteins (e.g. separation by localization within the cell, by cell type, by protein complex formation, or by cellular vs. matrix proteins), opening the door for a novel, refined classification taxonomy using enhanced biomarker signatures for diagnostics and treatment selection in oncology among a wide range of additional future applications.  

Puromycin Activity-Based Sensing Probes For Molecular Imaging And Histochemistry

A novel class of puromycin activity-based sensing probes containing analyte-specific responsive triggers have been synthesized and utilized for molecular imaging and histochemistry. After specific reaction between the trigger on the probe and target analyte, free puromycin molecules will be released and incorporated into nascent peptides. These incorporated puromycin can be detected after immunostaining, thus offering a highly sensitive method for detection of target analytes due to no leakage problem (as found in some reported fluorescent probes) and high signal-to-noise level from immunostaining. The syntheses of the probes are highly versatile, and representative examples for detection of reactive oxygen species (ROS), reactive sulfur species (RSS), reactive carbonyl species (RCS), ROS scavengers, and redox active metal ions have been demonstrated. One exemplary probe is Peroxymycin-1, which contains H2O2-responsive aryl boronate conjugated to puromycin through carbamate linkage. Peroxymycin-1 shows robust performance on molecular imaging of H2O2 in cell culture and histochemical analysis of H2O2 level in tissue samples harvested from small animals. It has been further employed for detection of elevated H2O2 level in liver tissues from a murine model of non-alcoholic fatty liver disease (NAFLD), suggesting its potential for studying disease pathology associated with H2O2 as well as disease diagnosis and monitoring of treatment progress.

Enhanced Speed Polymerases For Sanger Sequencing

Sanger sequencing has remained a dominant DNA sequencing methodology for molecular biology research and development for many years.  The main commercially available DNA polymerase developed for Sanger sequencing has a slow extension speed and has difficulties sequencing secondary structures such as GC rich regions, hairpins, mono- and poly-nucleotide repeats.  While specialized plastics and reductions in reaction volumes to improve Sanger sequencing reaction times, any gains in sequencing assay performance (e.g., sequencing time or throughput) are offset by increased costs associated with a terminator reagent.  During the last two decades, further refinement and advancement of suitable DNA polymerases to improve polymerization speeds during Sanger sequencing have been limited.  Thus, there remains a need for improved DNA polymerases suitable for Sanger sequencing that possess enhanced elongation speeds, and the ability to sequence through secondary structures present in DNA templates.    A UC Berkeley researchers has discovered compositions and methods for preparing and using Taq DNA polymerases with improved Sanger sequencing elongation sequencing rates as compared to commercially available Sanger sequencing reagents.  

Stroboscopic Universal Structure-Energy Flow Correlation Scattering Microscopy

Flexible semiconductors are far less costly, resource and energy intensive than conventional silicon production. Yet, as an unintended consequence of semiconductor printing, the films produced contain structural heterogeneities, or defects, which can limit their capacity to shuttle energy, or, information, over device-relevant scales. To be able to fully embrace this new, greener process, it is essential to elucidate which physical material properties most influence energy flow and which defects are most deleterious to efficient energy transport so that they can be targeted for elimination at the materials processing stage. Although some rather complex approaches have recently been used to track energy flow, the applicability of each one depends on specifics of the semiconductor properties (bandgap, excitonic vs charge carrier form of excitation, strong absorption or emission). Existing techniques cannot therefore be applied to a broad range of materials, and often necessitate adapting samples to fit the specific requirements of the technique. A broadly applicable approach is therefore needed to non-invasively and simultaneously reveal and correlate material morphology and energy flow patterns across many scales.    Researchers at the University of California, Berkeley have developed a new high-sensitivity, non-invasive, label-free, time-resolved optical scattering microscope able to map the flow of energy in any semiconductor, and correlate it in situ to the semiconductor morphology. This device has been shown as a far simpler approach to spatio-temporally characterize the flow of energy in either charge or exciton form, irrespective of the electronic properties of the material, and with few-nm precision. Furthermore, built into this approach is the unprecedented capability to perform in situ correlation to the underlying physical structure of the material. 

Protein-Coated Microparticles For Protein Standardization In Single-Cell Assays

Single-cell analysis offers powerful capabilities of identification of rare sub-populations of cells, understanding heterogeneity of cancerous tumors, and tracking cell differentiation and reprogramming. Despite great potentials for uncovering new biological systems and targeting diseases with precision medicine, single-cell approaches are composed of complex device processes that can cause bias in measurement.  In deep sequencing, technical variation in single cell expression data occurs during capture and pre-amplification steps. Similarly, in single-cell protein assays, technical variability can obscure functionally relevant variance.    To better control protein measurement quality in single-cell assays, researchers at the University of California, Berkeley developed a novel method to loading and release protein standard. This method utilizes the surface of modified and functionalized microparticles as vehicles to capture target proteins with desired concentrations. Chelation-assisted click chemistry is applied to demonstrate that protein standards with different molecular masses can be loaded and bounded in a single-cell protein assay. Microparticles are introduced into single-cell devices by either passive gravity, magnetic attraction, or other physicochemical forces. These protein standards from microparticles provide a reference to measure protein mass sizes from individual cells and a quality control for any biases in device fabrication, cell lysis, protein solubility, protein capture, and protein readouts (i.e. antibody probing).   

Endoribonucleases For Rna Detection And Analysis

96 Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} Bacteria and archaea possess adaptive immune systems that rely on small RNAs for defense against invasive genetic elements. CRISPR (clustered regularly interspaced short palindromic repeats) genomic loci are transcribed as long precursor RNAs, which must be enzymatically cleaved to generate mature CRISPR-derived RNAs (crRNAs) that serve as guides for foreign nucleic acid targeting and degradation. This processing occurs within the repetitive sequence and is catalyzed by a dedicated CRISPR-associated (Cas) family member in many CRISPR systems.  Endoribonucleases that process CRISPR transcripts are bacterial or archaeal enzymes capable of catalyzing sequence- and structure- specific cleavage of a single- stranded RNA. These enzymes cleave a specific phosphodiester bond within a specific RNA sequence.  UC Berkeley researchers discovered variant Cas endoribonucleases, nucleic acids encoding the variant Cas endoribonucleases, and host cells genetically modified with the nucleic acids that can be used, potentially in conjunction with Cas9, to detect a specific sequence in a target polyribonucleotide and of regulating production of a target RNA in a eukaryotic cell.  For example, it was found that the variant Cas endoribonuclease has an amino acid substitution at a histidine residue such that is is enzymatically inactive in the absence of imidazole and is activatable in the presence of imidazole.  

Type V CRISPR/CAS Effector Proteins for Cleaving ssDNA and Detecting Target DNA

Normal 0 false false false EN-US X-NONE X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Calibri",sans-serif; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Class 2 CRISPR–Cas systems (e.g., type V CRISPR/Cas systems such as Cas12 family systems) are characterized by effector modules that include a single effector protein. For example, in a type V CRISPR/Cas system, the effector protein - a CRISPR/Cas endonuclease (e.g., a Cas12a protein) - interacts with (binds to) a corresponding guide RNA (e.g., a Cas12a guide RNA) to form a ribonucleoprotein (RNP) complex that is targeted to a particular site in a target nucleic acid via base pairing between the guide RNA and a target sequence within the target nucleic acid molecule.  Thus, like CRISPR-Cas9, Cas12 has been harnessed for genome editing based on its ability to generate targeted, double-stranded DNA (dsDNA) breaks.   UC Berkeley researchers have discovered that RNA-guided DNA binding unleashes indiscriminate single-stranded DNA (ssDNA) cleavage activity by Cas12a that completely degrades ssDNA molecules. The researchers found that target-activated, non-specific ssDNase cleavage is also a property of other type V CRISPR-Cas12 enzymes. By combining Cas12a ssDNase activation with isothermal amplification, the researchers were able to achieve attomolar sensitivity for DNA detection.  For example, rapid and specific detection of human papillomavirus in patient samples was achieved using these methods and compositions.   

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