Highlights
- Fast: 80 - 90% of E.coli are lysed in only 10 minutes after harvesting.
- DE3 Lysogen: Encodes the T7 polymerase for expressing recombinant proteins under the control of the T7 promoter.
- Versatile: Fully compatible with a wide range of buffers for protein purification and other physical methods of lysis.
Description
| Autolysis | XJb lysis efficiency is 10-20 % lower than XJa. For optimal lysis, more care needs to be taken when selecting the lysis buffer. However, even very low concentrations of detergent may improve lysis significantly. |
|---|---|
| Cell Growth | A very robust strain, reaching higher OD’s than E. coli K-strains. |
| DNA Extraction | XJb is not optimal for DNA extraction. |
| DNA Stability | This strain is RecA positive. |
| Genotype | F- ompT hsdSB(rB - mB -) gal dcm ΔaraB::λR, cat (CmR), λ(DE3) |
| Processing Time | 10 minutes |
| Product Storage | -70°C to -80°C |
| Protein Expression | XJb is ideal for recombinant protein expression. It lacks Lon and OmpT proteases, leading to higher protein yields. |
Q1: Is a starter culture necessary?
For best results, cells should not be growing actively prior to arabinose induction. This is achieved by using an overnight starter, where cells are already in the stationary growth phase, as stated in the protocol. If a fresher starter needs to be used, include arabinose already in the starter culture.
Q2: What buffer should the cell pellet be resuspended in?
Resuspend the cell pellet in water with or without 0.01% - 0.1% Triton X-100. For His-tag purification, resuspend in the His-Binding Buffer of the His-spin Protein Miniprep kit (Zymo Research product # P2001 or P2002). Acidic buffers and buffers containing higher concentrations of Mg2+ (>1 mM), and related metals that stabilize cell walls, inhibit lysis reaction to a various extent. If possible, add magnesium to the buffer after cells are lysed.
Q3: How do you improve lysis efficiency?
If the results obtained are not satisfactory, lysis can be significantly improved by incubating the cells at higher temperatures (25 - 37°C) or for longer time (10 or 20 minutes) after thawing (step 5).
Q4: What if the lysate is extremely viscous?
Depending on the amount of material used, the lysed material may become viscous, preventing efficient manipulation. However, for most applications it is not necessary to use a large amount of cell material. If necessary, vortexing vigorously for 30 seconds will decrease viscosity in most cases. Alternatively, a nuclease treatment (e.g. DNAse I) can be used to reduce viscosity. Diluting the cell lysate with additional buffer will also reduce viscosity issues.
Q5: Can glycerol be present during the freeze-thaw cycle?
Do not perform the freeze and thaw cycle in a buffer containing glycerol. Glycerol protects the E.coli from forming ice crystals which are essential to the lysis of the cells.
Q6: Can glucose be added to the growth media?
When glucose is added to the growth media, it inhibits the induction of the autolysis genes when it is present in the media. As the cells grow, they consume the glucose as a carbon source. Once the glucose has been consumed autolysis begins.
Q7: Will chitin be degraded?
Non-λ lysozyme usually is able to degrade chitin. However, the λ lysozyme expressed in these cells is not able to degrade chitin. λ lysozyme is a transglycosylase.
Q8: Are competent cells GMOs?
All our competent cells are classified into Biosafety level 1 and are not genetic modified organisms. Only when transformed with a plasmid they become GMOs.
Q9: Which is the recommended DNA concentration and volume for transformation?
There really is no maximum or minimum recommended DNA concentration, but we use 10 pg for quality control. However, the volume of DNA added should not exceed 5% of the cells total volume; the efficiency can decrease several fold as the volume of DNA used increases. If the DNA sample is too diluted, use our DNA Clean & Concentrator.
Q10: Which Plasmid Size can be used for transformation?
For Zymo 5α and Zymo 10B up to 20kb. However, transformation efficiency decreases proportionally from 10-20kb. Above 20kb, cells are difficult to transform. JM109, HB101, XJa, XJa (DE3), XJb, XJb (DE3) and TG1 can handle constructs up to 10kb.
Q11: Which antibiotics can be used with the Mix & Go! procedure?
No outgrowth is necessary when using Ampicillin or Carbenicillin for selection. However, an outgrowth step is required when using Chloramphenicol, Kanamycin, and Tetracycline because of the mode of action of the antibiotic itself. We recommend the following procedure for the outgrowth step:1. Incubate cells on ice for 5-10 min after addition of plasmid. 2. Add 4 volumes of SOC media.3. Incubate at 37°C for 60 min with gentle shaking at 200-300 rpm.4. Spread on a pre-warmed culture plate containing the appropriate antibiotic.
Q12: Is it possible to dilute the competent cells?
We do not recommend diluting the competent cells. We recommend using less DNA to transform cells, or aliquot cells in smaller volumes before transformation. If absolutely necessary, cold 1X Competent Buffer (Mix & Go Transformation Kit, T3001 & T3002) should be used in the dilution.
Q13: How to reduce satellite colonies on agar plates?
– Prepare fresh agar plates – Use more antibiotics in plates – Incubate plates for a shorter time after plating cells
Q14: How will a heat-shock affect my Transformation Efficiency?
Heat shock is not necessary, however sometimes it can be beneficiary when preparing libraries or transforming XJb Autolysis E. coli strains.We recommend the following protocol for Heat Shock with Outgrowth: 1. Incubate cells on ice for 5-10 min after addition of plasmid. 2. Incubate cells at 42°C for 45 seconds.3. Add 450 ml of SOC to the cells.4. Incubate at 37°C for 60 min with gentle shaking at 200-300 rpm.5. Spread on a pre-warmed culture plate containing the appropriate antibiotic.
Q15: Do the Mix & Go! strains methylate DNA?
Yes
Q16: Are the Mix & Go! strains dam+ and dcm+?
Most cloning strains will be dam+/dcm+ unless specifically noted in the genotype.
Q17: What are some tips to improve transformation efficiency?
1. Thaw cells on ice, not room temperature.2. Incubate cells and DNA mixture on ice, not at room temperature. However, do not incubate longer then 1 hour.3. Ensure cells are still frozen when received.4. Pre-warm the culture plates at 37°C for at least 30 minutes.5. Prepare fresh LB agar plates containing the appropriate antibiotic. 6. Prepare a new DNA sample.7. Store the cells at -80°C (not 4°C or -20°C). If the freezer breaks, the cells should be OK as long as the temp does not go higher than -50°C.8. Avoid freeze/thaw cycles.
Q18: Which strains are equivalent to the Zymo strains?
DH5α is equivalent to Zymo 5α. DH10B, Top10, and One Shot Top10 are equivalent to Zymo 10B.For XL-21 Blue, JM109 is the closest match and for Stbl3, HB101 is the closest match.
To clone new GFP-like fluorescent proteins from Obelia medusa, the authors identified the potential genes using expression libraries and cloned the genes into a vector. Expression of the proteins was facilitated by using XJb Autolysis E. coli cells from Zymo Research. The authors were able to purify three proteins from Obelia medusa that fluoresce in three different colors: cyan, green, and yellow.
Aglyamova, G.V. et al. (2011) Multi-colored homologs of the green fluorescent protein from hydromedusa Obelia sp. Photochem Photobiol Sci (8):1303-9.ebiomall.com
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其突变性状可用生化的方法鉴别，与可见的形态突变型迥然有别。代表性的例子如与氨基酸、维生素、核酸碱基等合成代谢有关的酶失活的营养突变型，以及呼吸突变型、抗药突变型等。它们不仅广泛用于遗传学分析，而且还用于活体内代谢途径的研究和物质的生物测定等。还有许多未知用途。
基因突变可以是自发的也可以是诱发的。自发产生的基因突变型和诱发产生的基因突变型之间没有本质上的不同，基因突变诱变剂的作用也只是提高了基因的突变率。
按照表型效应，突变型可以区分为形态突变型、生化突变型以及致死突变型等。这样的区分并不涉及突变的本质，而且也不严格。因为形态的突变和致死的突变必然有它们的生物化学基础，所以严格地讲一切突变型都是生物化学突变型。根据碱基变化的情况，基因突变一般可分为碱基置换突变（base substitution和移码突变（frameshift mutation）两大类。
本人最近在对家族性遗传性高钙血症（FHH）的家族进行了多个可疑致病基因进行测序，测序公司已经给出了DNA的测序峰图及突变位点，但不知道这个突变是否是致病突变？还有如何才能知道该突变是否影响了氨基酸序列呢？本人在这方面零基础，麻烦稍微讲详细点，在这里先谢谢各位哥哥姐姐了，不胜感激！！！
1.形态突变：结构镰刀型细胞贫血症；体水平红眼突变白眼
2.化突变：镰刀型细胞贫血症血红蛋白结构突变原理
3.致死突变：比隐性纯合致死
P因子随机插入会导致基因发生突变，产生突变体，请问怎么用PCR来鉴定是哪个基因发生突变?求告知讲解，非常感谢！
肠杆菌其细菌: 基座命名统用斜体用三英文缩写字母表示表型第字母写用体基型三字母都写用斜体肩符号用表示野型、突变型、抗性或敏性Gal＋表示表型半乳糖野型或原养型Gal－或Gal表示表型半乳糖突变型或缺陷型；gal＋表示基型半乳糖野型gal－或gal表示基型半乳糖突变型；AmpR表示表型氨基苄青霉素抗性AmpS表示表型氨基苄青霉素敏性ampR表示基型氨基苄青霉素抗性ampS表示基型氨基苄青霉素敏性基位点基座位名称用写写字母表示同位点lac Z于特定突变型离前顺序编号表示编号要写gal K32
酵母: 三字母表明基功能数字表示同基座啤酒酵母基GAL4 CDC28; 蛋白质：GAL4, CDC28非洲粟酒酵母基 gal4, cdc2; 蛋白质：Gal4, Cdc2
线虫: 用三写字母表示突变表型存基座用连字符接数字表示例基unc-86, ced-9; 蛋白UNC-86; CCED-9
蝇: 突变表型描述由1-4字母表示例基white(w ), tailless ( tll ), hedgehog ( hh ); 蛋白White, Tailless, Hedgehog
植物: 虽没惯用适用于所植物数用1-3写字母表示Arabidopsis基用蝇命名需要用写字母例基AGAMOUS(AG)蛋白 AGAMOUS
脊椎物: 般1-4写字母数字表示其基功能例基sey, myc, 蛋白 Sey, Myc
类: 脊椎物需写例基 MYC、ENO1蛋白MYC、ENO1于基产物命名前没统规定现基本都统用体或全部写或第字母写Gal或GAL
2) 克隆技术使用使倾向于量繁殖现种群利用价值体按自规律促进整种群优胜劣汰意义说克隆技术干扰自进化程.
3) 克隆技术种昂贵技术需要量金钱物专业士参与失败率非高莉277实验唯虽现发展更先进技术功率能达2-3%
4) 转基物提高疾病传染风险例产药物牛奶牛染病毒种病毒能通牛奶染病
5) 克隆技术应用于体导致代遗传性状工控制克隆技术引起争论核能否允许发育初期类胚胎进行遗传操作伦理家所能接受
6) 克隆技术用创造超或拥健壮体格却智力低且克隆技术能够类效运用男性失遗传意义
7) 克隆技术家庭关系带影响巨由父亲DNA克隆孩看作父亲双胞胎兄弟延迟几十已难设想发现自另外完全复制品（或）受
１．向性 任何基座（locus）基都能独立发同突变形其新等位基基突变向性譬同条件位于染色体某基座基A突变其等位基a1；突变a2或者a3、a4．．．．．．an等等其等位基形式形所谓复等位基（multiple alleles）遗传群体存于同基座决定同类相性状经由突变且具３种或３种同形式等位基互称复等位基家所熟知类ABO血型系统由位于9q34区域同基座IA、IBi三种等位基形式所构组复等位基所决定
２．重复性 基突变重复性指：已经发突变基定条件能再独立发突变形其另外种新等位基形式亦即于任何基位点说其突变并非仅囿于某或某几发定频率反复发例：某基座基A突变其等位基a；基a能独立发突变形其新等位基a1；同a1能再发突变形其另外等位基a2；a2能突变a3．．．．．．其终群体遗传效应言基重复突变与基向突变结相似群体复等位基存主要
３．随机性 基突变仅物界普遍存种遗传事件且于任何种物任何体任何细胞乃至任何基说突变发都随机同物种、同体、同细胞或者基其各自发基突变频率能并完全相同已基突变频率简称突变率（mutation rate）基种等位形式某世代突变其另外等位形式概率
４．稀性 尽管基突变物界普遍存种遗传事件却种非频发稀事件自状况各种物突变率都低据测算般高等物基突变率约平均：10-8～10-5／殖细胞／位点／代；类基突变率约仅仅：10-6～10-4／殖细胞／位点／代
５．逆性 基突变逆任何种野型基都能够通突变形其等位突变型基；反突变型基突变其相应野型基前者称作向突变（forward mutation）者谓曰复突变（reverse mutation）般情况向突变率总远远高于复突变率
６．害性 般言物遗传性状形期进化程与其赖存自环境相互适应结自选择产物些性状具决定性意义基旦发突变通都物存带消极或利影响即害性殖细胞或受精卵基突变绝数类遗传病发根本原；体细胞突变则肿瘤发病理遗传基础基突变害性往往相条件；并非所基突变都物存及其种群繁衍带利或者害影响事实些突变往往引起非功能性DNA序列组改变却并造核酸蛋白质功能损害
靶向药物目前先进用于治疗癌症药物靶向药物针肿瘤细胞特基发能够高度特异性识别杀灭肿瘤细胞具效、副作用较特点尤其适合体质较差肺癌患者
靶向治疗肺癌治疗前需要做基突变检查根据基情况决定否适合该种治疗肺癌基突变检查目前主要针
EGFR、KRASALK等靶标明确肿瘤药物敏性检查结助于相应靶向治疗药物选择药效异
基突变检查结阴性患者适合采用靶向治疗说明肺癌由基突变造能外界原所致辐射、防腐剂、免疫力低等等
基突变检查阴性肺癌患者没服用易瑞沙特罗凯必要且易瑞沙特罗凯目前际公认针非细胞性肺癌靶向药物没同类药物替代种情况应酌情考虑化疗
分类：
基因突变可以是自发的也可以是诱发的。自发产生的基因突变型和诱发产生的基因突变型之间没有本质上的不同，基因突变诱变剂的作用也只是提高了基因的突变率。 按照表型效应，突变型可以区分为形态突变型、生化突变型以及致死突变型等。这样的区分并不涉及突变的本质，而且也不严格。因为形态的突变和致死的突变必然有它们的生物化学基础，所以严格地讲一切突变型都是生物化学突变型。根据碱基变化的情况，基因突变一般可分为碱基置换突变（base substitution和移码突变（frameshift mutation）两大类。
碱基置换突变(subsititution) 指DNA分子中一个碱基对被另一个不同的碱基对取代所引起的突变，也称为点突变（point mutation）。点突变分转换和颠换两种形式。如果一种嘌呤被另一种嘌呤取代或一种嘧啶被另一种嘧啶取代则称为转换（transition）。嘌呤取代嘧啶或嘧啶取代嘌呤的突变则称为颠换（transversion）。由于DNA分子中有四种碱基，故可能出现4种转换和8种颠换（见上图）。在自然发生的突变中，转换多于颠换。 碱基对的转换可由碱基类似物的掺入造成。例如，5-溴尿嘧啶(5-bromouracil，BU）是一种与胸腺嘧啶类似的化合物，具有酮式和烯醇式两种结构，且两者可以互变，一般酮式较易变为烯醇式。当DNA复制 时，酮式BU代替了T，使A-T碱基对变为A-BU；第二次复制时，烯醇式BU能和G配对，故出现G-BU碱基对；第三次复制时，G和C配对，从而出现G-C碱基对，这样，原来的A-T碱基对就变成G-C碱基对（见下图）。向左转|向右转 碱基对的转换也可由一些化学诱变剂诱变所致。例如，亚硝酸类能使胞嘧啶（C）氧化脱氨变成尿嘧啶（U），在下一 次复制中，U不与G配对，而与A配对；复制结果C-G变为T-A（见右图）。又如，烷化剂中的芥子气和硫酸二乙酯可使G发生乙基化，成为烷基化鸟嘌呤（mG），结果，mG不与C配对，而与T配对，经过复制，G-C变为A-T。
移码突变（translocation） 指DNA片段中某一位点插入或丢失一个或几个（非3或3的倍数）碱基对时，造成插入或丢失位点以后的一系列编码顺序发生错位的一种突变。它可引起该位点以后的遗传信息都出现异常。发生了移码突变的基因在表达时可使组成多肽链的氨基酸序列发生改变，从而严重影响蛋白质或酶的结构与功能。吖啶类诱变剂如原黄素、吖黄素、吖啶橙等由于分子比较扁平，能插入到DNA分子的相邻碱基对之间。如在DNA复制前插入，会造成1个碱基对的插入；若在复制过程中插入，则会造成1个碱基对的缺失，两者的结果都引起移码突变。
缺失突变(deletion) 基因也可以因为较长片段的DNA的缺失而发生突变。缺失的范围如果包括两个基因，那么就好象两个基因同时发生突变，因此又称为多位点突变。由缺失造成的突变不会发生回复突变。所以严格地讲，缺失应属于染色体畸变。
插入突变(insertion) 一个基因的DNA中如果插入一段外来的DNA，那么它的结构便被破坏而导致突变。大肠杆菌的噬菌体Mu-1和一些插入顺序（IS）以及转座子（见转座因子）都是能够转移位置的遗传因子，当它们转移到某一基因中时，便使这一基因发生突变。许多转座子上带有抗药性基因，当它们转移到某一基因中时，一方面引起突变，另一方面使这一位置上出现一个抗药性基因。插入的DNA分子可以通过切离而失去，准确的切离可以使突变基因回复成为野生型基因。这一事件的出现频率并不由于诱变剂的处理而提高。
