Ordering
| Item | Catalog # | Description | Quantity | Price (USD) | ||
|---|---|---|---|---|---|---|
| Plasmid | 44361 | Standard format: Plasmid sent in bacteria as agar stab | 1 | $75 | Add to Cart | |
| AAV1 | 44361-AAV1 | Virus (100 µL at titer ≥ 7×10¹² vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV2 | 44361-AAV2 | Limited Stock Available, 1 unit leftVirus (100 µL at titer ≥6×10¹² vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV5 | 44361-AAV5 | Virus (100 µL at titer ≥ 7×10¹² vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV8 | 44361-AAV8 | Virus (100 µL at titer ≥ 4×10¹² vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV9 | 44361-AAV9 | Virus (100 µL at titer ≥ 1×10¹³ vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV Retrograde | 44361-AAVrg | Virus (100 µL at titer ≥ 7×10¹² vg/mL)and Plasmid.More Information | Add to Cart | |||
| AAV PHP.eB | 44361-PHPeB | Virus (100 µL at titer ≥ 1×10¹³ vg/mL)and Plasmid.More Information | Add to Cart | |||
This material is available to academics and nonprofits only.
Backbone
- Vector backbonepAAV(Search Vector Database)
- Backbone sizew/o insert(bp)4824
- Total vector size (bp)7326
- Vector typeAAV ; Adeno Associated Viral Vector
Growth in Bacteria
- Bacterial Resistance(s)Ampicillin
- Growth Temperature37°C
- Growth Strain(s)NEB Stable
- Copy numberLow Copy
Gene/Insert
- Gene/Insert namehM3D(Gq)-mCherry
- SpeciesH. sapiens (human)
- Insert Size (bp)2502
- Promoterhuman Synapsin 1
- Tag/ Fusion Protein
- mCherry (C terminal on insert)
Cloning Information
- Cloning methodRestriction Enzyme
- 5′ cloning siteAsc I(not destroyed)
- 3′ cloning siteNhe I(not destroyed)
- 5′ sequencing primertcgtgtcgtgcctgagagcg
- 3′ sequencing primerGCATTAAAGCAGCGTATCCACATAGC (Common Sequencing Primers)
Resource Information
- Terms and Licenses
- UBMTA
- genOway Notice of RIghts
- Takara Bio Limited Use Label License (formerly Clontech)
- Industry Terms
- Not Available to Industry
- Articles Citing this Plasmid
- 44 References
Information for AAV1 (Catalog # 44361-AAV1)(Back to top)
Purpose
Ready-to-use AAV1 particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 7×10¹² vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV1 cap gene
- BufferPBS + 0.001% Pluronic F-68 + 200 mM NaCl
- SerotypeAAV1
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Ancillary Agreement for Penn Vectors
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Information for AAV2 (Catalog # 44361-AAV2)(Back to top)
Purpose
Ready-to-use AAV2 particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 6×10¹² vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV2 cap gene
- BufferPBS + 0.001% Pluronic F-68
- SerotypeAAV2
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Data submitted about 44361-AAV2 by requesting scientist(s):
- Data 1: Mouse, Retina
- Data 2: Rat, Brain parenchyma
Information for AAV5 (Catalog # 44361-AAV5)(Back to top)
Purpose
Ready-to-use AAV5 particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 7×10¹² vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV5 cap gene
- BufferPBS + 0.001% Pluronic F-68
- SerotypeAAV5
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Data submitted about 44361-AAV5 by requesting scientist(s):
- Data 1: Mouse, Brain parenchyma
Information for AAV8 (Catalog # 44361-AAV8)(Back to top)
Purpose
Ready-to-use AAV8 particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 4×10¹² vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV8 cap gene
- EnvelopeAAV8 cap gene
- BufferPBS + 0.001% Pluronic F-68
- SerotypeAAV8
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Ancillary Agreement for Penn Vectors
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Data submitted about 44361-AAV8 by requesting scientist(s):
- Data 1: Mouse, Brain parenchyma
- Data 2: Mouse, Brain parenchyma
- Data 3: Mouse, Brain parenchyma
- Data 4: Mouse, Brain parenchyma
- Data 5: Rat, Brain parenchyma
- Data 6: Mouse, Brain parenchyma
Information for AAV9 (Catalog # 44361-AAV9)(Back to top)
Purpose
Ready-to-use AAV9 particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 1×10¹³ vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV9 cap gene
- BufferPBS + 0.001% Pluronic F-68
- SerotypeAAV9
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Ancillary Agreement for Penn Vectors
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Information for AAV Retrograde (Catalog # 44361-AAVrg)(Back to top)
Purpose
Ready-to-use AAV Retrograde particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV were produced with a retrograde serotype, which permits retrograde access to projection neurons. These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 7×10¹² vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, AAV retrograde cap gene from rAAV2-retro helper (plasmid #81070)
- BufferPBS + 0.001% Pluronic F-68 + 200 mM NaCl
- SerotypeAAV retrograde (AAVrg)
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Retrograde functionality is dependent on high viral titers. Addgene recommends not diluting your AAV preps prior to use.Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Data submitted about 44361-AAVrg by requesting scientist(s):
- Data 1: Mouse, Brain parenchyma
Information for AAV PHP.eB (Catalog # 44361-PHPeB)(Back to top)
Purpose
Ready-to-use AAV PHP.eB particles produced from pAAV-hSyn-DIO-hM3D(Gq)-mCherry (#44361). In addition to the viral particles, you will also receive purified pAAV-hSyn-DIO-hM3D(Gq)-mCherry plasmid DNA.
Syn-driven, Cre-dependent, hM3D(Gq) receptor with an mCherry reporter for CNO-induced neuronal activation. These AAV were produced with the PHP.eB serotype, which permits efficient transduction of the central nervous system.These AAV preparations are suitable purity for injection into animals.Delivery
- Volume100 µL
- Titer≥ 1×10¹³ vg/mL
- Pricing$350 USD for preparation of 100 µL virus + $30 USD for plasmid.
- StorageStore at -80℃. Thaw just before use and keep on ice.
- ShipmentViral particles are shipped frozen on dry ice. Plasmid DNA (≥ 200ng) will also be included in the shipment.
Viral Production & Use
- Packaging Plasmidsencode adenoviral helper sequences and AAV rep gene, PHP.eB cap gene pUCmini-iCAP-PHP.eB (plasmid #103005)
- BufferPBS + 0.001% Pluronic F-68
- SerotypePHPeB (plasmid #103005)
- PurificationIodixanol gradient ultracentrifugation
- Reporter GenemCherry (Cre-dependent)
Biosafety
Requestor is responsible for compliance withtheir institution"s biosafety regulations.Lentivirus is generally considered BSL-2. AAV isgenerally considered BSL-1, but may requireBSL-2 handling depending on the insert.Biosafety Guide
Resource Information
- Terms and Licenses
- Ancillary Agreement for Penn Vectors
- Terms of Use for Viral Vectors
- Industry Terms
- Not Available to Industry
Viral Quality Control
- Addgene ensures high quality viral vectors by optimizing and standardizing production protocols and performing rigorous quality control (QC) (see a list of our QC assays). Thespecific QC assays performed varies for each viral lot. To learn which specific QC assays were performed on your lot, please contact us.
- Titer: the exact titer of your sample will be reported on the tube. The titer you see listed on this page is the guaranteed minimum titer. See how titers are measured.
Visit our viral production page for moreinformation.
Addgene Comments
Using FLEX vectors in vivo: LoxP sites in FLEX plasmids are known to recombine during DNA amplification and viral vector production, which may result in a minority of Cre-activated (i.e., "flipped") viral vectors. Addgene has measured this occurs in 0.01-0.03% of viral vectors in our typical production protocol. This can lead to a small number of cells exhibiting Cre-independent transgene expression in vivo. To address this, we recommend titrating to find the optimal AAV dosage required for Cre-dependent transgene expression and function in vivo. This may include reducing the viral vector dosage in order to reduce the likelihood of Cre-independent expression.
Citation Information: When using the PHP.eB serotype in future publications, please acknowledge Viviana Gradinaru and cite Chan et al., Nat Neurosci, 20(8):1172-1179. Pubmed.ebiomall.com
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做黄单胞，在通过Tn5构建转化子库之后，通过致病力筛选、Tail-PCR获得侧翼序列、比对获得全基因之后，将几个可能与致病力相关的基因做了敲除，现在正在构建互补载体，已经做了敲除转化子的胞外酶活性测定、胞外多糖分泌测定、生长曲线、致病性测定等等，不过不知道将互补做完了之后还有什么可以做的。
目前，来自Streptococcus pyogenes 的CRISPR-Cas9系统应用最为广泛。Cas9 蛋白（含有两个核酸酶结构域，可以分别切割DNA 两条单链。Cas9首先与crRNA及tracrRNA结合成复合物，然后通过PAM序列结合并侵入DNA，形成RNA-DNA复合结构，进而对目的DNA双链进行切割，使DNA双链断裂。
由于PAM序列结构简单（5’-NGG-3’），几乎可以在所有的基因中找 到大量靶点，因此得到广泛的应用。CRISPR-Cas9系统已经成功应用于植物、细菌、酵母、鱼类及哺乳动物细胞，是目前最高效的基因组编辑系统[1]。
通过基因工程手段对crRNA和tracrRNA进行改造，将其连接在一起得到sgRNA（single guide RNA）。融合的RNA具有与野生型RNA类似的活力，但因为结构得到了简化更方便研究者使用。通过将表达sgRNA的原件与表达Cas9的原件相连接，得到可以同时表达两者的质粒，将其转染细胞，便能够对目的基因进行操作[2,3]。
目前常用的CAS9研究方法是通过普通质粒,质粒构建流程如下：
Cas9质粒构建
目前常见的CAS9普通质粒有（汉恒生物提供cas9质粒试剂盒）：
虽然普通质粒很多时候也能达到实验效果，但是质粒转染具有效率低，作用时间短暂性等缺点。病毒的出现解决了质粒这些问题，常用的病毒主要有慢病毒和腺病毒，慢病毒常用质粒见addgene（lentiCRISPR v2，lentiGuide-Puro，lentiCas9-Blast），慢病毒可以整合入宿主基因组中，长期稳定的表达（汉恒生物提供CRISPR/cas9 慢病毒包装），但是由于慢病毒克隆能力有限而CAS9本身分子量比较大（大于4kb），且长期插入可能导致乱切，脱靶等，同时慢病毒包装最终获得的滴度不高等原因，腺病毒更有优势，腺病毒克隆能力强，获得的病毒滴度也高。同时相对于普通质粒来说，作用是时间也比较长，可以达到更理想的敲除效果。
缺点：质粒仍然较大，转染难度相对较大。具有碱基识别偏好性，局限了基因编辑的运用范围，而且会导致不同基因位点编辑效率不同。筛选仍然需要较大工作量。
类，其中Ⅰ类和Ⅲ类需要多种CRISPR相关蛋白（Cas蛋白）共同发挥作用，而Ⅱ类系统
只需要一种Cas蛋白即可，这为其能够广泛应用提供了便利条件。
目前，来自Streptococcuspyogenes的CRISPR-Cas9系统应用最为广泛。Cas9蛋白（含
有两个核酸酶结构域，可以分别切割DNA两条单链。Cas9首先与crRNA及tracrRNA结合
成复合物，然后通过PAM序列结合并侵入DNA，形成RNA-DNA复合结构，进而对目的
DNA双链进行切割，使DNA双链断裂。
由于PAM序列结构简单（5’-NGG-3’），几乎可以在所有的基因中找到大量靶点，因此得到广泛的应用。CRISPR-Cas9系统已经成功应用于植物、细菌、酵母、鱼类及哺乳动物细胞，是目前最高效的基因组编辑系统。
http://www.addgene.org/crispr/guide/
一、CRISPR/Cas9系统的构成
CRISPR(clustered,regularly interspaced,short palindromic repeats)是一种来自细菌降解入侵的病毒DNA或其他外源DNA的免疫机制。在细菌及古细菌中，CRISPR系统共分成3类，其中Ⅰ类和Ⅲ类需要多种CRISPR相关蛋白（Cas蛋白）共同发挥作用，而Ⅱ类系统只需要一种Cas蛋白即可，这为其能够广泛应用提供了便利条件。目前，来自Streptococcus pyogenes的CRISPR/Cas9系统应用最为广泛。
Cas9蛋白（含有两个核酸酶结构域，可以分别切割DNA两条单链。Cas9首先与crRNA及tracrRNA结合成复合物，然后通过PAM序列结合并侵入DNA，形成RNA-DNA复合结构，进而对目的DNA双链进行切割，使DNA双链断裂。
研究人员为了将CRISPR/Cas9技术发展为高效的基因打靶工具，又进行了优化和改造。Cong, L.等人[1]在不影响系统效率的情况下，将crRNA和tracrRNA融合为一条RNA。通过这种简化，CRISPR/Cas9系统现仅包括两个元素：Cas9蛋白和sgRNA（single guide RNA）。因此现在人们将CRISPR/Cas9技术也称为Cas9/sgRNA技术。
二、CRISPR/Cas9技术的基因编辑机制
CRISPR/Cas9通过对预设的DNA位点进行切割，造成DNA双链断裂（DSB, double strand break）。这种DNA的损伤可以启动细胞内的修复机制，主要包括两种途径：
一是低保真性的非同源末端连接途径（NHEJ，Non-homologous end joining），此修复机制非常容易发生错误，导致修复后发生碱基的缺失或插入（Indel），从而造成移码突变，最终达到基因敲除的目的。NHEJ是细胞内主要的DNA断裂损伤修复机制。利用靶向核酸酶可以在受精卵水平高效的实现移码突变，从而制备基因敲除模式动物。CRISPR/Cas9技术的出现，使得无需再使用相应物种的ES细胞系就可以制备基因敲除模式生物，且已成功应用于小鼠[5]、大鼠[6]、猪[7]、灵长类[8]、果蝇[9]等等。
第二种DNA断裂修复途径为同源介导的修复（HR, homology-directedrepair），这种基于同源重组的修复机制保真性高，但是发生概率低。在提供外源修复模板的情况下，靶向核酸酶对DNA的切割可以将同源重组发生的概率提高约1000倍[10]。利用这种机制可以实现基因组的精确编辑，如：条件性基因敲除、基因敲进、基因替换、点突变等等。
CRISPR/Cas9技术以自己操作的便捷性，高效的基因编辑能力获得青睐，成为当下科研工作者的新宠儿。各大实验室纷纷加入开发CARISPR/Cas9技术的行列中，媒体也将之评为21世纪最有影响的十大技术之一。让我们跟随CRISPR/Cas9技术的脚步一起加强科研基础的建设，推动生物科研的进步！
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