This document describes a novel gene targeting approach called aptamer-guided gene targeting (AGT) that uses DNA aptamers selected through capillary electrophoresis systematic evolution of ligands by exponential enrichment to bind site-specific DNA binding proteins and guide donor DNA to specific genetic loci for correction. The approach was shown to increase gene targeting efficiency up to 32-fold in yeast and 16-fold in human cells. It also discusses the potential to develop aptamers for other genome editing tools like CRISPR/Cas9.
The CRISPR/Cas9 system has emerged as one of the leading tools for modifying the genomes of organisms ranging from E. coli to humans. In this presentation, we discuss various methods for generating the crRNA and tracrRNA components that are required for guiding the Cas9 endonuclease to genomic targets. You will also learn how to optimize a new 2-part CRISPR RNA system from IDT that offers multiple benefits over other technologies.
The CRISPR/Cas9 system has emerged as one of the leading tools for modifying the genomes of organisms ranging from E. coli to humans. In this presentation, we discuss various methods for generating the crRNA and tracrRNA components that are required for guiding the Cas9 endonuclease to genomic targets. You will also learn how to optimize a new 2-part CRISPR RNA system from IDT that offers multiple benefits over other technologies.
CRISPR has become an increasingly popular tool for genome editing, in part because it is highly flexible and relatively easy to implement compared to other technologies. However, for scientists beginning to work with this method, the wide range of products and variety of editing approaches can be overwhelming. In this presentation, Justin Barr provides a simple explanation of the steps for planning your experiment, including guide RNA design, an overview of delivery methods, and options for measuring editing results. He also discusses how to generate specific mutations in the genome using homology-directed repair (HDR).
Have you considered that protein over-expression or inefficient mRNA knockdown may be masking physiological effects in your assays? Increasingly scientists are moving to endogenous gene-editing to characterise the function of their genes of interest.
Dr Chris Thorne from Cambridge Biotech Horizon Discovery discusses the ground breaking gene-editing technology CRISPR. The simplicity of experimental design has led to rapid adoption of the technology across the scientific community. However, challenges remain.
This Slidedeck focuses specifically on implementing CRISPR experiments, and explore a number of key considerations crucial to maximising chances of targeting success, whether your goal is to generate a knock-out or a knock-in. Chris also takes a look at some of the alternative uses of CRISPR, including sgRNA genome wide synthetic lethality screens.
The slides aim to support those researchers either planning to or already using CRISPR gene-editing in their lab. Horizon Discovery have also recently launched a program aimed specifically at academic cell biologists to promote the adoption of CRISPR by offering FREE CRISPR Reagents for knock-out cell line generation - more information available here. http://www.horizondiscovery.com/what-we-do/discovery-toolbox/genassist-crispr--raav-genome-editing-tools
Recent advances in CRISPR-CAS9 technology: an alternative to transgenic breedingJyoti Prakash Sahoo
These are the part of the Bacterial immune system which detects and recognize the foreign DNA and cleaves it.
THE CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loci
Cas (CRISPR- associated) proteins can target and cleave invading DNA in a sequence – specific manner.
CRISPR array is composed of a series of repeats interspaced by spacer sequences acquired from invading genomes.
Next generation-sequencing.ppt-convertedShweta Tiwari
The advance version, sequences the whole genome efficiently with high speed and high throughput sequencing at reduce cost is termed as Next Generation Sequencing (NGS) or massively parallel sequencing (MPS).
Bioo Scientific - Reduced Bias Small RNA Library Prep with Gel-Free or Low-In...Bioo Scientific
microRNAs (miRNAs) may provide useful markers for the development of disease diagnostic and prognostic assays. NGS brings sensitivity, specificity, and the ability to maximize data acquisition and minimize costs of miRNA sequencing by using multiplex strategies to allow many samples to be sequenced simultaneously with small RNA analysis. However, small RNA sequencing has typically suffered from three major drawbacks: severe bias, such that sequencing data does not reflect original miRNA abundances, the need to gel purify final libraries, and lack of low-input protocols. The NEXTflex™ Small RNA-Seq Kit v3 addresses these drawbacks by using two strategies: randomized adapters to reduce ligation-associated bias, and a dual approach to adapter-dimer reduction, thereby allowing gel-free or low-input small RNA library preparation.
Genome editing is a process where an organism's genetic code is changed. In these slides, Zinc Finger proteins and TALENs proteins classification and their application are presented in brief.
CRISPR/Cas9 gene editing is based on a microbial restriction system, that has been harnessed for genome targeting using only a short sequence of RNA as a guide.
The beauty of the system is that unlike protein binding based technologies such as Zinc Fingers and TALENs which require complex protein engineering, the design rules are very simple, and it is this fact that is allowing CRISPR to take genome engineering from a relatively niche persuit to the mainstream scientific community.
The principle of the system is that a short guide RNA, homologous to the target site recruits a nuclease – Cas9
This then cuts the dsDNA, triggering repair by either the low fidelity NHEJ pathway, or by HDR in the presence of an exogenous donor sequence.
High Efficiencies for both knockouts and knock-ins have been reported and whilst there are understandable concerns about specificity, new methodologies to address these are now being developed
The system itself is comprised of three key components
the Cas9 protein, which cuts/cleaves the DNA and
Two RNAs - a crispr RNA contains the sequence homologous to the target site and a trans-activating crisprRNA (or TracrRNA) which recruits the nuclease/crispr complex
For genome editing, the crisperRNA and TraceRNA are generally now constructed together into a single guideRNA or sgRNA
Genome editing is elicited through hybridization of the sgRNA with its matching genomic sequence, and the recruitment of the Cas9, which cleaves at the target site.
Handout available at
https://drive.google.com/open?id=0B52D4j3rC4WDN2hRV25CaW9kb0E
Define DNA sequencing.
Describe the history of DNA sequencing.
Describe the steps of Sanger sequencing.
Define next generation sequencing.
Describe the steps of next generation DNA sequencing.
Describe use of DNA sequencing.
i explained about basics of genome engineering and crispr system.
CRISPR will change the world and it is just the beginning, are you ready to meet the future? you think its great and beautiful or.....?
please give your feedback to my email
pooyanaghshbandi@yahoo.com
i am starting to write a critical and fantastic review article about CRISPR, if you are interested to join please contact me.
This presentation highlights the basics and application of genome editing strategies in plants, strategies to reduce off-target mutation, identification of mutant analysis etc.
CRISPR has become an increasingly popular tool for genome editing, in part because it is highly flexible and relatively easy to implement compared to other technologies. However, for scientists beginning to work with this method, the wide range of products and variety of editing approaches can be overwhelming. In this presentation, Justin Barr provides a simple explanation of the steps for planning your experiment, including guide RNA design, an overview of delivery methods, and options for measuring editing results. He also discusses how to generate specific mutations in the genome using homology-directed repair (HDR).
Have you considered that protein over-expression or inefficient mRNA knockdown may be masking physiological effects in your assays? Increasingly scientists are moving to endogenous gene-editing to characterise the function of their genes of interest.
Dr Chris Thorne from Cambridge Biotech Horizon Discovery discusses the ground breaking gene-editing technology CRISPR. The simplicity of experimental design has led to rapid adoption of the technology across the scientific community. However, challenges remain.
This Slidedeck focuses specifically on implementing CRISPR experiments, and explore a number of key considerations crucial to maximising chances of targeting success, whether your goal is to generate a knock-out or a knock-in. Chris also takes a look at some of the alternative uses of CRISPR, including sgRNA genome wide synthetic lethality screens.
The slides aim to support those researchers either planning to or already using CRISPR gene-editing in their lab. Horizon Discovery have also recently launched a program aimed specifically at academic cell biologists to promote the adoption of CRISPR by offering FREE CRISPR Reagents for knock-out cell line generation - more information available here. http://www.horizondiscovery.com/what-we-do/discovery-toolbox/genassist-crispr--raav-genome-editing-tools
Recent advances in CRISPR-CAS9 technology: an alternative to transgenic breedingJyoti Prakash Sahoo
These are the part of the Bacterial immune system which detects and recognize the foreign DNA and cleaves it.
THE CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) loci
Cas (CRISPR- associated) proteins can target and cleave invading DNA in a sequence – specific manner.
CRISPR array is composed of a series of repeats interspaced by spacer sequences acquired from invading genomes.
Next generation-sequencing.ppt-convertedShweta Tiwari
The advance version, sequences the whole genome efficiently with high speed and high throughput sequencing at reduce cost is termed as Next Generation Sequencing (NGS) or massively parallel sequencing (MPS).
Bioo Scientific - Reduced Bias Small RNA Library Prep with Gel-Free or Low-In...Bioo Scientific
microRNAs (miRNAs) may provide useful markers for the development of disease diagnostic and prognostic assays. NGS brings sensitivity, specificity, and the ability to maximize data acquisition and minimize costs of miRNA sequencing by using multiplex strategies to allow many samples to be sequenced simultaneously with small RNA analysis. However, small RNA sequencing has typically suffered from three major drawbacks: severe bias, such that sequencing data does not reflect original miRNA abundances, the need to gel purify final libraries, and lack of low-input protocols. The NEXTflex™ Small RNA-Seq Kit v3 addresses these drawbacks by using two strategies: randomized adapters to reduce ligation-associated bias, and a dual approach to adapter-dimer reduction, thereby allowing gel-free or low-input small RNA library preparation.
Genome editing is a process where an organism's genetic code is changed. In these slides, Zinc Finger proteins and TALENs proteins classification and their application are presented in brief.
CRISPR/Cas9 gene editing is based on a microbial restriction system, that has been harnessed for genome targeting using only a short sequence of RNA as a guide.
The beauty of the system is that unlike protein binding based technologies such as Zinc Fingers and TALENs which require complex protein engineering, the design rules are very simple, and it is this fact that is allowing CRISPR to take genome engineering from a relatively niche persuit to the mainstream scientific community.
The principle of the system is that a short guide RNA, homologous to the target site recruits a nuclease – Cas9
This then cuts the dsDNA, triggering repair by either the low fidelity NHEJ pathway, or by HDR in the presence of an exogenous donor sequence.
High Efficiencies for both knockouts and knock-ins have been reported and whilst there are understandable concerns about specificity, new methodologies to address these are now being developed
The system itself is comprised of three key components
the Cas9 protein, which cuts/cleaves the DNA and
Two RNAs - a crispr RNA contains the sequence homologous to the target site and a trans-activating crisprRNA (or TracrRNA) which recruits the nuclease/crispr complex
For genome editing, the crisperRNA and TraceRNA are generally now constructed together into a single guideRNA or sgRNA
Genome editing is elicited through hybridization of the sgRNA with its matching genomic sequence, and the recruitment of the Cas9, which cleaves at the target site.
Handout available at
https://drive.google.com/open?id=0B52D4j3rC4WDN2hRV25CaW9kb0E
Define DNA sequencing.
Describe the history of DNA sequencing.
Describe the steps of Sanger sequencing.
Define next generation sequencing.
Describe the steps of next generation DNA sequencing.
Describe use of DNA sequencing.
i explained about basics of genome engineering and crispr system.
CRISPR will change the world and it is just the beginning, are you ready to meet the future? you think its great and beautiful or.....?
please give your feedback to my email
pooyanaghshbandi@yahoo.com
i am starting to write a critical and fantastic review article about CRISPR, if you are interested to join please contact me.
This presentation highlights the basics and application of genome editing strategies in plants, strategies to reduce off-target mutation, identification of mutant analysis etc.
Lecture ON Polymerase Chain Reaction.
The polymerase chain reaction (PCR) is a powerful core molecular biology technique - Sometimes called "molecular photocopying. • Developed by Kary Mullis in 1985.
• It is an efficient and rapid in vitro method for enzymatic amplification of specific DNA or RNA sequences from nucleic acids of various sources. •
It generates microgram (µg) quantities of DNA copies (up to billion copies) of the desired DNA (or RNA) segment.
A simple PCR reaction consists of
i. A DNA preparation containing the desired segment to be amplified.
ii. A set of synthetic oligonucleotide primers that flank the target DNA
sequence, of about 20 bases long, specific, i.e., complementary.
iii. A thermostable DNA polymerase e.g., Taq isolated from the
bacterium Thermus acquaticus, Pfu – Pyrococcus furiosus and Vent
from Thermococcus litoralis. Pfu and Vent are more efficient than
Taq polymerase.
iv. Four deoxynucleoside triphosphate (dNTPs): TTP – thymidine
triphosphate, dCTP – deoxycyctidine triphosphate, dATP –
deoxyadenosine triphosphate and dGTP – deoxyguanosine
triphosphate
Techniques based on the principle of selectively amplifying a subset of restriction fragments from a complex mixture of DNA fragments obtained after digestion of genomic DNA with restriction endonucleases.
Cloning and expression of the Nodamura virus RNA-dependent RNA polymerase
Poster presentation at Society for the Advancement of Chicanos and Native Americans in Science (SACNAS) National Conference, October 2012, Seatltle, WA
The next generation of crispr–cas technologies and Applicationsiqraakbar8
The prokaryote-derived CRISPR–Cas genome editing systems have transformed our ability to manipulate, detect, image and annotate specific DNA and RNA sequences in living cells of diverse species. The ease of use and robustness of this technology have revolutionized genome editing for research ranging from fundamental science to translational medicine. Initial successes have inspired efforts to discover new systems for targeting and manipulating nucleic acids, including those from Cas9, Cas12, Cascade and Cas13 orthologues.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
How to Build a Module in Odoo 17 Using the Scaffold MethodCeline George
Odoo provides an option for creating a module by using a single line command. By using this command the user can make a whole structure of a module. It is very easy for a beginner to make a module. There is no need to make each file manually. This slide will show how to create a module using the scaffold method.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
Safalta Digital marketing institute in Noida, provide complete applications that encompass a huge range of virtual advertising and marketing additives, which includes search engine optimization, virtual communication advertising, pay-per-click on marketing, content material advertising, internet analytics, and greater. These university courses are designed for students who possess a comprehensive understanding of virtual marketing strategies and attributes.Safalta Digital Marketing Institute in Noida is a first choice for young individuals or students who are looking to start their careers in the field of digital advertising. The institute gives specialized courses designed and certification.
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it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
A Strategic Approach: GenAI in EducationPeter Windle
Artificial Intelligence (AI) technologies such as Generative AI, Image Generators and Large Language Models have had a dramatic impact on teaching, learning and assessment over the past 18 months. The most immediate threat AI posed was to Academic Integrity with Higher Education Institutes (HEIs) focusing their efforts on combating the use of GenAI in assessment. Guidelines were developed for staff and students, policies put in place too. Innovative educators have forged paths in the use of Generative AI for teaching, learning and assessments leading to pockets of transformation springing up across HEIs, often with little or no top-down guidance, support or direction.
This Gasta posits a strategic approach to integrating AI into HEIs to prepare staff, students and the curriculum for an evolving world and workplace. We will highlight the advantages of working with these technologies beyond the realm of teaching, learning and assessment by considering prompt engineering skills, industry impact, curriculum changes, and the need for staff upskilling. In contrast, not engaging strategically with Generative AI poses risks, including falling behind peers, missed opportunities and failing to ensure our graduates remain employable. The rapid evolution of AI technologies necessitates a proactive and strategic approach if we are to remain relevant.
Group Presentation 2 Economics.Ariana Buscigliopptx
Genome editing & targeting tools
1. Genome editing & targetting
tools
Presented by : S.Rasoulinejad
2015 - spring
2. Aptamer-guided gene targeting
• Here we have developed a novel gene targeting approach, in
which we bind a site-specific DNA binding protein by a DNA
aptamer to target a donor molecule to a specific genetic locus
for correction
(aptamer-guided gene targeting [AGT])
But what is DNA aptamer and how we can reach it?!
3. Goals:
• This work is designed as a proof-of-principle concept or
prototype to show that by binding a protein that guides the
correcting donor DNA into proximity to its genetic target via an
aptamer,
• AGT the efficiency of gene targeting increases
4. AGT?!
• The AGT approach increases the efficiency of gene targeting
by guiding the exogenous donor DNA into the vicinity of the
site targeted for genetic modification.
• By tethering the exogenous donor DNA to the site-specific
homing endonuclease I-SceI, which recognizes an 18-bp
sequence and generates a DSB
DNA aptamers were selected for binding to the I-SceI protein
using a variant of capillary electrophoresis systematic
evolution of ligands by exponential enrichment (CE-SELEX)
called ‘Non-SELEX’
5. AGT?!
• By synthesizing a DNA oligonucleotide that contained :
the I-SceI aptamer sequence
as well as homology to repair the I-SceI DSB and
correct a target gene,
we were able to increase gene targeting frequencies up to 32-
fold in yeast, and up to 16-fold in human cells.
6. What has been done step by step:
74-mer oligonucleotides containing a central 36-nt variable region
Was loaded with I-SceI protein on CE with LIF.
Two rounds of selection were done to obtain DNA aptamers to I-
SceI
After sequencing the 11 strongest binding aptamers, these
candidate aptamers were further characterized using EMSA gels
to confirm their binding capacity to I-SceI.(showed consistent and
reproducible binding to I-SceI)
11. EMSA Gel ? Electrophoretic Mobility
Shift Assay
EMSA Gel ? is a common affinity electrophoresis technique
used to study protein–DNA or protein–RNA interactions.
• DNA moves through the gel faster when not bound to protein
• A reduction in electrophoretic mobility shows that a complex
is formed between DNA and protein
12. 5 basic steps are in conventional EMSA protocol
Preparation of
purified or crude
protein sample
Preparation of nucleic
acid
Binding reactions
Non-denaturing
gel
electrophoresis
Detection of the
outcome
14. Using EMSA to determine kd
I. A fixed concentration of DNA is titrated with
excess protein
II. Bound and free DNA are separated using
EMSA
III. Measure density of bands, Kd=protein
concentration when 50% of DNA is free
15. The I-SceI aptamer stimulates gene correction in
yeast
• using bifunctional single-stranded DNA oligonucleotides containing the
aptamer region I-SceI aptamer at one end
• the donor repairing sequence at the other end
• First, we determined on which end (5̒̒ or 3 ) the I-SceI aptamer should be
positioned in the bifunctional molecule to obtain more effective
stimulation of gene targeting.
bifunctional oligonucleotides (P1-A7-P2.TRP5.40 for the aptamer with
primers at the 5 end of the bifunctional oligonucleotide and TRP5.40.P1-
A7-P2 which contained 40 bases of homology to correct a disrupted TRP5
gene in yeast
17. Some results:
in both yeast (up to 32-fold) and human cells (up to 16-fold).
I-SceI aptamer in AGT, the donor molecule is brought in the
vicinity of its target site, and this may not only increase HR
with the desired locus but also potentially reduce the
likelihood of random integration
The novelty and uniqueness of our AGT system lay the
foundation for generating and exploiting other aptamers for
gene targeting.
18. It may be possible to obtain aptamers for other site-specific
homing endonucleases, or for more modular nucleases, like
zinc-finger nucleases (ZFNs)
transcription activator-like effector nucleases (TALENs) or the
Cas9 nuclease of the clustered regularly interspaced short
palindromic repeat (CRISPR) system
Furthermore, the potential aptamer targets to stimulate gene
correction in cells are not limited to endonucleases but could
be any protein that facilitates the targeting process, such as
transcription factors, HR proteins or even NHEJ proteins.
19. But what is CRISPR System?!
• Introduction:
• The clustered, regularly interspaced short palindromic repeat
(CRISPR)/CRISPR-associated (Cas) protein system is an
adaptive RNA-mediated immune system in approximately
40% of bacteria and ~ 90% of Achaea.
• The CRISPR/Cas system can be reprogrammed to reject
invading bacteriophages and conjugative plasmids.
It is classified into three types (I, II, and III) based on the
sequence and structure of the Cas protein
20. • The crRNA-guided surveillance complexes in types I and III
need multiple Cas subunits
• type II requires only Cas9
• The type II system as a reduced system has been studied
primarily in Streptococcus and Neisseria
• A protospacer within an N21GG (or N20NGG) format is widely
used for S. pyogenes Cas9 targeting. This protospacer contains
a 20-nt base-pairing region immediately followed by a PAM
(NGG).
• Other Cas9 orthologs requiring longer PAM sequences would
reduce our choices on targetable sites in a given gene or
genome.
21. • Protospacer-adjacent motifs= PAM
• protospacer-adjacent motifs(PAMs): are short
conserved nucleotide stretches next to the
protospacers, such as NGG, NGGNG, NAAR, and
NNAGAAW,are absolutely necessary for Cas9 binding
and cleavage.
22. • The native type II system requires at least three crucial
components:
• RNA-guided Cas9 nuclease, crRNA, and a partially
complementary trans-acting crRNA (tracrRNA)
• tracrRNA:is a non protein coading RNA for maturation and
subsequent DNA cleavage
23. Cas9 nuclease.
• Cas9 (formerly known as Csn1 or Csx12)
• is able to cleave double-stranded DNA (dsDNA) in a sequence
specific manner
• Cas9 is a large multidomain protein with two nuclease
domains
RuvC-like nuclease domain near the amino terminus
HNH (or McrA) nuclease domain in the middle
24. APPLICATION OF TYPE II CRISPR/Cas SYSTEM
• In general, current applications of type II systems
can be classified into three categories:
native Cas9-mediated genome editing,
Cas9 nickase mediated genome editing,
and inactivated Cas9-mediated transcriptional
control
25. Rate:
• Construction of a mammalian expression system with codon-
optimized Cas9 and gRNA generated targeting rates:
2 to 25% in various human cells
36 to 48% in mouse embryonic stem cells
Co-transformation of a gRNA plasmid and editing template DNA
into a yeast cell constitutively expressing Cas9 generated a near
100% donor DNA recombination frequency at the target loci
Co-injection of Cas9 mRNA and gRNA transcripts into mouse
zygotes generated mutants with an efficiency of 80%
26. Cas9 nickase-mediated genome editing
• gRNA-guided Cas9n with a RuvC or HNH mutation has the ability
to create a nick instead of a DSB at the target site
• Introduction of a double nick using a pair of gRNA-directed Cas9ns
targeting the opposite strands of the target site has been
successfully applied to generate DSBs and NHEJ-induced
mutations.*(non homologous end joining (NHEJ))
Interestingly, this paired nicking significantly reduced off-target
cleavages by 50- to 1,500-fold in human cells, but without
sacrificing on-target cleavage efficiency**
27. Cas9 nickase-mediated genome editing
• creating a pair of double nicks at two sites by four
customized gRNAs successfully deleted genomic
fragments of up to 6 kb in HEK 293FT cells
multiplex nicking created by Cas9n has the
ability to create high-precision genome
editing.
Editor's Notes
DNA aptamers are sequences of DNA
that are able to bind to a specific target with high affinity
because of their unique secondary structure
we achieved targeted delivery of
exogenous donor DNA to the site of the I-SceI DSB in
different genomic locations in yeast and human cells,
facilitating gene correction by the donor DNA.
The hypothesis is that by delivering targeting DNA
within proximity to the site of cleavage, gene targeting
frequencies can be increased
. (A) Bifunctional-targeting
oligonucleotides containing the A7 aptamer at the 50 end along
with a region of homology to restore the function of a defective gene of
interest are transformed/transfected into the cell. The I-SceI endonuclease
is produced from the chromosome (yeast) or from a transfected
expression vector (humans). (B) The A7 aptamer then binds to the
I-SceI protein, either in the cytoplasm (shown here) or in the nucleus C) I-SceI drives the bifunctional oligonucleotide to the targeted locus
containing the I-SceI site, and (D) generates a DSB at the I-SceI site.
(E) Resection of the 50 ends of the DSB gives rise to single-stranded 30
DNA tails. (F) The 30 tail of the bifunctional oligonucleotide anneals to
its complementary DNA sequence on the targeted DNA, and after the
non-homologous sequence is clipped, (G) DNA synthesis proceeds on
the template sequence. (H) After unwinding of the bifunctional oligonucleotide,
a second annealing step occurs between the extended 30 end
and the other 30 end generated from the DSB. (I) Further processing,
gap-filling DNA synthesis, and subsequent ligation complete repair and
modification of the target locus.