We narrowed to 858 results for: CAL;

...connections to that population. Limitations of common genetically encoded neuronal tracers Neuronal tracers such...neurons. As compared to epitopes tags, FPs are intrinsically fluorescent and can therefore be used in live...tolerated by cells. They can be used for protein localization, isolation, and tracking experiments (Rizzo,.... Thus they have created antigenic protein tags called “spaghetti monster” fluorescent proteins (smFPs.... Indeed, to create the smFPs Looger’s team strategically inserted 10 to 15 copies of single epitope tags...darkened chromophores. These probes are both intrinsically fluorescent and can be detected with highly ...postsynaptic cell adhesion protein that plays a critical role in neural development. It belongs to a huge...

...of Various Motifs is Critical for Initiation of Replication. Journal of Biological Chemistry, 273(14), ... replication machinery. For instance, the ori typically contains iterons that serve as recognition sites...Acinetobacter spp., Aeromonas spp., Agrobacterium spp., Alcaligenes spp., Aliivibrio salmonicida, Anabaena spp., ...Gram-negative and Gram-positive  Acinetobacter calcoaceticus, Actinobacillus pleuropneumoniae, Actinomyces...Aeromonas hydrophila, Agrobacterium tumefaciens, Alcaligenes eutrophus, Azotobacter vinelandii, Brevibacterium...pSa, pR388 Gram-negative  Acinetobacter calcoaceticus, Aeromonas liquefaciens, A. salmonicida, Agrobacterium...Agrobacterium tumefaciens, A. rhizogenes, Alcaligenes eutrophus, Enterobacter sp., Erwinia amylovora, E...

...tricks By Ashley Waldron While IHC protocols typically call for thin sections of tissue, the Wu Lab is ...therapy, Feng Zhang’s lab has developed a system called DIRECTED (Delivery to Intended REcipient Cells ...promising approach for experimental therapies and medical applications.  Find DIRECTED plasmids here! Strebinger...labeling can identify protein interactions or map a local proteome, but some applications have been challenging...control over when and where the enzyme is active, drastically reducing background labeling caused by the biotin...proximity labeling enzymes, TurboID and APEX2, are localized to different cellular compartments. They showed...of a cell. Lin et al. generated a fusion protein called iPAK4 that assembles into a slow-growing protein...

... general public. Chemical Society in University College Dublin, Ireland The Chemical Society was founded...way up to professors. Oxford Biological Society, England The Biological Society based at the University...idea of the Freshers Fair and some of the great biological societies that Addgene has had the opportunity...at Freshers Fairs in the past year. Cambridge Biological Society, England Since 1996, Cambridge Biosoc...Biosoc’s goal has been to promote interest in the biological sciences amongst the student community at the...At Addgene, we’re incredibly glad to see these biological societies engaging with young scholars. We believe... to keep up the good work! What scientific or biological societies were you a part of in undergrad or ...

...graduate students and postdocs to think analytically and critically. Passion fuels the drive to continue ... Connie Cepko (Harvard Medical School) , and Dr. George Church (Harvard Medical School) for taking the...people (especially you!) care about. Have you critically evaluated your plan? Have you read the relevant...write a grant for this project, what would be your critical experiments and why? What techniques and skills...help move your project forward? Most projects typically require a diverse set of skills. It is important...direction of the project? What is your timeline? A typical research project can take several years to complete...time to generate new ideas and think about them critically before diving in. Research projects are designed...

...transcriptase (RT), MarathonRT. Reverse transcriptases are critical tools for many fields of biology and enable the...Nanobodies are single domain antibody fragments typically engineered from heavy-chain only antibodies found... with specific genomic loci. He made use of catalytically inactive dCas9 by fusing it to an engineered...isolated and analysed. In this work, the authors specifically investigated protein binding at the TERT gene...his group from the University of Massachusetts Medical School have developed a group of plasmids (here...only 1 min. Using these lentiviral plasmids, catalytically inactive Cas9 (dSpyCas9) fused to APEX2 is expressed...by mass spectrometry allowing a researcher to specifically identify proteins that are enriched in the 20...

.... Factor Xa loves calcium, but metal-chelate matrices, not so much. Maybe a calcium-independent proteinase...This allows washing away of unbound material to calculate the amount of bound ligand (after subtracting ...subtracting out non-specific binding). Historically, glutathione-S-transferase (GST) fusion proteins have been immobilized...derivatives streptavidin and neutravidin) is for all practical purposes covalent. Therefore, protein immobilization... four biotin-binding sites per molecule so, theoretically, saturated avidin could form tetramers of biotinylated...well-controlled. The lack of site selectivity typically diminishes the apparent affinity for the ligand...However, large amounts of the target protein are typically required due to the relatively low efficiency ...

...The good news is that viruses are very valuable biological tools, and with the right safety considerations...infiltration into a cell. The twist is that the typical genetic cargo — the viral genome — is swapped, ...vector containing the cargo of interest is then typically transfected along with viral packaging plasmids...risk management when working with viral vectors. Typically, one day after transfection into the production...expression or integration resulting from transduction typically plateaus within a few days to a few weeks, depending...context you are targeting? Second, what is the biological outcome you want to achieve? For example, do ...swap out your virus type to achieve different biological outcomes. For example, some viruses integrate...

...humanistic and philosophical implications. As an example, a group at Caltech used an optical fiber together...Optogenetics is a toolset that lets you turn the electrical activity of neurons on or off using pulses of...photosynthetic or photosensory molecules that come from basically every branch on the tree of life. Our most recent...some of these mysteries. Another application is clinical; can we find ways to treat patients? Over a quarter...implant already. If we can use light to more specifically activate a set of neurons, maybe we could treat...modulate electricity. If you could selectively let in calcium or some other specific ion that would be interesting...Addgene Alerts box. References: Independent Optical Excitation of Distinct Neural Populations. Nathan...

...situation in cells. Therefore, the localization of critical fusions (e.g. tubulin or connexin) has been...needed for Golgi localization, is occluded and therefore this protein is mislocalized. The APT1-mVenus... from Aequorea victoria and its variants are genetically encoded fluorescent probes. One of the limitations...ultracentrifugation or gel filtration is the most common analytical method. However, these may not reflect the situation... the POI. For example, the APT1-mVenus fusion localizes at the Golgi, whereas the mVenus-APT1 fusion does...function of the native protein that is tagged. The localization of the fusion protein can be verified and it...fluorescent protein fusion may never be able to act identical to the untagged protein, the benefits of being...

...Lajoie, M. J., et al. (2013). Genomically recoded organisms expand biological functions. Science, 342(6156...head-to-head comparisons of these proteins in identical conditions. Find mScarlet3-S2 and mScarlet3-H ...produced higher yields than previous versions — typically double or triple (Figure 2). Based on these results...preserves the present for study in the future. Specifically, the present transcriptome. The system, developed....-K., Wu, M., Gong, Q., & Chen, F. (2026). A genetically encoded device for transcriptome storage in mammalian...! Grome, M. W., et al. (2025). Engineering a genomically recoded organism with one stop codon. Nature,...only the most efficient and specific guides. Specifically, the design process utilizes Rule Set 3, a prediction...

..., you’ll first need to learn a little bit of theoretical background on the different parameters that your...and W describe the shape of a histogram, which graphically represents the time and intensity of the cell...Live/Dead gate to focus your analysis on what’s biologically active. After that, the next gates fully depend...depend on your individual experiment. Practical example: lymphocytes in a mouse tumor sample You made ...made it! So much about the theoretical background. Let’s dive into the praxis of gating strategies. As an... would work just as fine (Figure 4). As H and A scale in proportion (while H and W do not; see Figure ...presented with a trend of two populations with basically a smear in between. Again, it can depend on the...

...hybridoma monoclonals, we anticipate that our chemically identical hybridoma-derived antibodies will also work...specific ligand-binding functions, all key to basic biomedical research and drug development. Integrin structure...long legs that protrude from the cell membrane, physically connecting the extracellular environment and ...signal cascades, and allowing agile responses to mechanical forces in the cell’s microenvironment. The actin...and (C) extended-open. When a ligand binds, it typically shifts the integrin from its closed to its open...resulting in cells that elongated and morphed asymmetrically (Jo et al., 2022). By contrast, LVDP-binding...conferred less force, leading cells to spread into symmetrical circles. While elucidating the role of tension...

...or macromolecule. Biotin can be added enzymatically or chemically. Enzymatic biotinylation occurs naturally...Avidin is a glycoprotein that consists of four identical subunits that can each bind one molecule of biotin... Scientists have developed several methods to chemically biotinylate macromolecules of interest both in...acid functional groups in vivo via specialized chemicals (biotinylation reagents). There are a variety ...the specificity of the E.coli BPL, BirA. If you recall, BirA biotinylates only one lysine in the entire...using a biotinylated primer. Biotin can also be enzymatically incorporated during PCR using a biotin labelled...modification of exceptional specificity.” Trends in Biochemical Sciences, 24.9 (1999b): 359–363. PubMed PMID:...

... Biosensor AAV (calcium sensors and GABA sensors) Calcium sensors The latest calcium sensors from Janelia...include: EGFP-expressing AAV for serotype testing Calcium sensors and GABA sensors Optogenetics Recombinases...for monitoring neuronal activity in the form of calcium dynamics. (For more details on this technology,...technology, see our blog post Overview of AAV Encoded Calcium Sensors). We are expanding the inventory of these... publication (Chettih & Harvey, 2019), “this localization should improve the specificity of influence ...Recombinase AAV Targeting and manipulating specific, genetically-defined neuronal populations with intersectional...pAAV EF1a Nuc-flox(mCherry)-EGFP (112677-AAV5) Calcium Sensors pGP-AAV-syn-jGCaMP7b-WPRE (104489-AAVrg...

...protein based research. This year, we put out another call for applications. We had an overwhelming response... variants one at a time is time consuming and unscalable.  Melissa Chiasson, a graduate student in Douglas...of sequence variants on abundance simultaneously called VAMP-seq, for Variant Abundance by Massively Parallel...epoxide reductase (VKOR) variants. VKOR is an enzyme critical for activating clotting factors and is the target...instrumental in interpreting human variation at large scales and making personalized medicine a reality,” Chiasson... Lin Tian’s lab at UC Davis is to generate a genetically encoded fluorescent sensor for serotonin. According...replicate current knowledge, but the sensor can also kinetically outperform current methods. Unger plans to use...

...To our surprise, we measured identical dissociation rates for catalytically inactive dCas9 molecules. We...these editing reactions is low. Understanding the biological cause of this repair bias is a fascinating (and...(Richardson et al 2016) revealed some of the biophysical parameters that can influence the HDR/NHEJ decision...key scientific principle: that understanding a biological process in detail often suggests new strategies... dissociation rates and discovered that the catalytically active form of the nuclease dissociates very...Our in vitro results also demonstrated that catalytically inactive dCas9 produced a “bubble” structure...this publication were performed using a technique called nucleofection, which introduces functional Cas9...

...which let the team detect its co-localization with a membrane-localized mCherry or GFP protein. With this...it co-localizes with its target at the cell membrane and when the OptoNB can’t bind, it localizes to the...The opening and closing of the AsLOV2 domain allosterically alters the shape and binding ability of its...unmodified proteins. Affinity purification methods typically require a protein to be tagged, which limits these...provides greater spatiotemporal resolution than pharmacological or genetic manipulation of the signaling pathway...and differentiation.  Since Ras is a membrane localized GTPase, the team fused a mCherry OptoNB to the...fusion protein in cells that expressed membrane-localized mCherry. With darkness, SOS binds Ras and initiates...

...tools from across the biological spectrum to learn more about the brain and neurological disease. I was surprised...and, like many biological fields the number potential of experiments enabled by physical, software, and...brain functions and vice versa. Even within the biological sciences, there’s plenty of interaction between... microbial DNA they all seem to require some mathematical know-how for analysis. If you’re looking to ...presentation area, I honed in on projects using biological tools. In addition to the researcher using sequencing...but are afraid you don’t have the right kind of biological expertise to get into the field, there’s likely...genes to many different cell types with minimal immunological effects. AAVs are used in experiments targeting...

... finding new factors in your biological system of interest, the so-called “fishing expedition.” Your first...population (typically cells or small organisms) and then assaying for a functional or phenotypical outcome...that both attempt to identify new players in a biological process. Players can be proteins, genes, enzymes...obligatory growth advantage – that is, you are not specifically looking at cells that can survive. Instead, ..., the entirety of the small molecule realm is typically not feasible to test in any given screening experiment...selection process. Non-functional traits will be automatically eliminated, unlike in screens. Selections begin...the answer that much faster? In reality, many biological questions are not conducive to selections and...

...experimental RNA. To solve this problem, gRNAs can be chemically modified to resist degradation while still effectively...purchasing your gRNA. Pro tip: modifications are typically incorporated at the termini of the crRNA molecule...oligonucleotides. Some of these synthetic modifications, specifically ones which do not contain a 5’ triphosphate ...or immunity itself is being studied.   Chemical RNA modifications to improve stability.   ...targeted editing events. Both technologies utilize chemical modifications to the RNA to control the entire...visualize transfection efficiency and even track localization in cellular experiments. There are many suitable...References Hendel, A., Bak, R., Clark, J. et al. Chemically modified guide RNAs enhance CRISPR-Cas genome...

...with biological protocols and revolutionary physical approaches. However, with each new technical achievement...aim to make microscopy as a tool accessible to practically everyone.     Fig. 1: Open source hardware...modify and optimize the code, find and fix security-critical bugs, and contribute to constant updates of the... OpenFlexure microscope or open-source modular optical toolbox openUC2 are trying to overcome this hurdle...reproduction of the structure in a similar way to the biological protocol, and assembly designs based around the...towards more open research. The EU, for example, is calling for the opening of sources within the next few ...relying on tailored image processing and low-cost optical setups. References Joel T. Collins, Joe Knapper...

...have such epitopes. These classical 'undruggable' targets are often intrinsically disordered and structurally...suppressors to growth factors, some of the most clinically-relevant proteins are also the hardest to study... detection of proteins without the challenges typically occurring with a fluorescence-based approach. ...species that can lead to phototoxicity, perturb biological processes, and compromise cell viability (Laissue...complementary validation of protein expression and localization. HiBiT-tagged targets in translational research...ubiquitin ligases in the degradation of CFTR, specifically UBE3C. Degradation of CFTR was measured through...luminescence signal, associated with endosomal localization of EGFR. This method offered kinetic, non-invasive...

...these types of bigger picture problems systematically and logically is as useful for finishing your thesis... but this skill is not just about reacting to technical issues. This skill also comes into play while ...defining problem solving skills as: One’s ability to logically think through a problem/task/situation, come up...Problem-solving overlaps heavily with other skills such as critical thinking, decision making, creativity, or data... really are, while also practicing systematic, logical thinking.  If you are already a lab veteran at ... to troubleshoot; you probably did not just automatically come to a solution. Consider the thoughts that...solutions. Ultimately, problem solving is less about technical know-how and more about how you approach new challenges...

...Stanford University. Sex and gender are critical components of biological research that are often forgotten ...the past decade. For more practical help, there are numerous methodological articles to consider—we have... that of human clinical trials. And, as Janine Clayton points out, late-stage clinical studies that draw...effects of using all female cells and tissues, specifically in stem cell therapies. Let’s go back to why... disease being treated, and other hormonal, immunological, and environmental factors. How to include sex... (NIH) now requires that sex be included as a biological variable in all NIH-funded research. Janine Clayton...

...generation of iPSCs is relatively simple in concept: ectopically express a cocktail of stem cell reprogramming...clones. Retroviruses are not considered safe for clinical applications.     Lentiviral: Lentiviral vectors...lentiviral delivery is not considered safe for clinical applications. Excisable Cre-lox lentiviral vectors...diluted faster when cells are actively dividing. The typical drawbacks of using transfection will still exist...DNA-silencing mechanisms. While minicircles are typically smaller than traditional plasmids, Jia et al generated...determine how stem cell-like they behave. iPSCs are typically tested with molecular-based assays first. These...molecular hallmarks of reprogramming, then they are typically assessed with more rigorous functional tests. ...

...regular part of basic biological research as well as clinical therapy. These biological tools are useful because...  When viruses were first being engineered as biological tools, thought was given on how to keep the replication...encoded in the transfer plasmid, the component that physically integrates into the host genome, the virus is...caution as they are integrating viruses – they physically deposit their cargo into the host’s DNA. These...should be thoroughly decontaminated after use, typically with bleach (plastic) or ethanol (other surfaces...Virus Many virus experiments involve needles or scalpels (sharps). Cuts and scrapes from sharp equipment...specific organization/department/lab’s policies – basically, you’ll need to get trained in each new place ...

...relies on “unmixing.” Unmixing uses a complex mathematical algorithm and single stained reference controls...spectral flow experiment and panel, there are a few critical factors to keep in mind in order to get the best...extraction Cells produce a low level of fluorescence called autofluorescence (you can see this in your unstained...controls). Spectral flow cytometers include a tool called “autofluorescence extraction” which allows the ...autofluorescence across various tissue types varies, it is critical to include an unstained sample for each tissue...detected. Cytek’s website has a convenient tool, called the similarity index, which allows the user to ...and a value of “1” indicating those markers are identical and completely indistinguishable. This tool is...

...methods. Since molecular, ecological, and reproductive confinement typically require very little effort...Development Fellow at the Wyss Institute and Harvard Medical School. Scientists making transgenic organisms ...the entire wild population with unpredictable ecological effects. Because the consequences of such a mistake... to implement and have been tested in yeast5. Ecological confinement involves performing experiments in...experiments attempting to build gene drives in tropical mosquito vectors of diseases such as malaria and...the laboratory. It varies by organism, but your local biosafety officer should be familiar with appropriate...they should not be relied on exclusively because historical studies of pathogen research have conclusively...

...used to calculate the concentration of the sample. This concentration can then be used to calculate the viral...viable lactic acid bacteria in faecal samples." Journal of microbiological methods 148 (2018): 64-73. PubMed... we have used quantitative PCR to evaluate the physical titer of our preps. We often repeat this assay...factor of 2. This means that if you set up two identical assays with the same sample, you could end up ...would be valid. This is why the AAV reference is critical. It allows you to determine if your titers are...adding your sample to a mastermix. At Addgene, we typically load 3 dilutions onto our ddPCR plate. As the ...Maintaining a high droplet count is important for calculating the concentration of your sample. Even if you...

...library! Now also available as a lentiviral prep. Calabrese: human CRISPRa sgRNA library In addition to inhibiting...lowly expressed genes or genes that are more drastically affected by gene activation rather than depletion... A and B. Sanson et al. demonstrated that the Calabrese library substantially identified more hits than...al., 2015). Root and Doench also compared the Calabrese library to screens performed with open reading...for resistance to MEK inhibition. Although both Calabrese and the ORF overexpression library identified ...in complement to study gene function. Find the Calabrese pooled library and lentiviral prep here! Applications...PMC4744125.  3. Gilbert, Luke A., et al. "Genome-scale CRISPR-mediated control of gene repression and activation...

...where you assume your technical skills define you and that the other not-so-technical skills you’ve built...industries and work environments. This is why they are called transferable skills. Why are transferable skills... individual with more going for you than your technical expertise in a specific field. While searching...under your belt from your last job. You knock the technical portion of the interview out of the park. It’s...hiring team will also want to examine not just technical skills, but also transferable skills, before offering... make hiring decisions. Though having all the technical skills certainly matters in the job market, it...you possessed. Think about your shining moments. Recall a few times you really felt great about your work...

...club occurs with a small technical team (single lab or team), a deep technical dive on single papers could...number of participants and the standard academic calendar. So you want to start a journal club? Here are...topic, there are a number of administrative and practical decisions to make. How often will you hold it?... the time recurrently carved out. This notice typically should include the paper, any supplemental data...repositories, or other information needed by someone to critically discuss the paper.  Before the first journal ...primary purpose is training graduate students in critical reading. If the aim of the journal club is to ...Addgene, we opted to start with one per month. When to call it a day The most ineffective type of meeting is...

... but this research is still in the pre-clinical/early clinical stages. Researchers are also working to... applications, and they’ve also had success in clinical gene therapy applications. Read on to learn more...gene therapy. In 2003, VIRxSYS began the first clinical trial with a lentiviral vector. CD4+ T-cells from...load and did not cause severe adverse reactions. Clinical benefits of lentiviral vectors have been observed...genome, they could promote oncogenesis by altering local gene expression. Self-inactivating (SIN) lentiviral...Patient monitoring and follow-up in lentiviral clinical trials. McGarrity GJ, Hoyah G, Winemiller A, Andre...gene therapy of human β-thalassaemia. Cavazzana-Calvo M, Payen E, Negre O, Wang G, Hehir K, Fusil F, Down...

...through mutagenesis in order to improve its physical and biochemical properties. In 1995, Roger Y. Tsien described...scientists to begin to study GFP and deduce its biochemical properties. Now GFP and its fluorescent derivatives...GFP is used in research across a vast array of biological disciplines and scientists employ GFP for a wide...tagging genes for elucidating their expression or localization profiles, acting as a biosensor or cell marker...living cells, enabling the study of dynamic, physiological processes. Re-engineering GFP to increase its...protein that undergoes conformational change. Typically, two fluorescent proteins with overlapping excitation...pH, using a range of strategies such as FRET, calmodulin, and others. Review Addgene's collection of fluorescent...

...Epitopes are between 5-8 amino acids long, with a typical length of 5 or 6 amino acids (Cruse et al., 2004... just as specific for their target antigen as canonical antibodies. They also have the advantage of being...recognize epitopes that full antibodies would not physically be able to reach. While a full antibody is ~150...of light that can pass through each well - the optical density (OD) - of the known and experimental wells...concentration of the known samples is used to calculate the concentration of protein in the experimental...surface of or inside whole cells. Antibodies - typically, primary antibodies that are conjugated to a fluorophore...the presence of specific proteins, but their localization within the cell or tissue as well. Similar to...

...analyzing your cells using flow cytometry, you are typically measuring the presence or absence of certain markers...free amines on and inside the cells and are thus typically used for distinguishing live from dead cells. ...atoms to a higher energy state. This process is called excitation. After a short period, the electrons...state, whereby a photon is emitted. This step is called emission. During excitation, some of the photon's... compared to APC. This happens due to a process called Fluorescence Resonance Energy Transfer (FRET). ...PE-CF594PE-Cy5PE-Cy7       Red (640 nm)   APCAlexa Fluor 647   Alexa Fluor 700APC-H7APC-Cy7 ...wavelength of 488 nm (Table 1), which is near a local maximum of PE's excitation spectrum (dotted line...

... a more-typical scale of tissue culture while still offering the potential for true biological insight...which to test the validity of your biological model and the technical performance of your assay. But, in...components, the model system and the assay are just as critical for success. Sometimes, you might have a few positive...involved. Or you don’t know how well your assay will scale. Or you don’t have enough cells to execute genome-wide...facilitating more rapid follow-up. We hope the biological community will find these reagents to be useful...

...position at Addgene, the skeptical applicant asked if she would partake in “critical thinking” in the position... away from calling non-academic careers and desk jobs “alternative careers.” Realistically, based on the...it. The opportunity to be creative and think critically. One of the very first times I interviewed a ...wish for a stretch of time that doesn’t involve critical thinking. Former Addgenie Jessica Welch says, ...aspect of their chosen career. You can confidently call yourself a Scientist. You work in a lab. You formulate...transferable skills. Transferable skills are the non-technical skills you pick up wherever you work, and you’... communicating. After years of focusing on my technical skills with cloning and lentivirus production,...

... that could bind very specifically to target molecules. Using a technique called systematic evolution ... high specificity and affinity, were eventually called aptamers, from the Latin aptus, meaning “to fit...essentially mimicking GFP.  Though the aptamer, called Spinach, required longer exposure time than its...group selected for a 49-nucleotide aptamer they called Broccoli. As a product of SELEX and FACS, Broccoli..., Akhtar and Marty, Jean L. “Aptamer based electrochemical sensors for emerging environmental pollutants...PMCID: PMC4923196. 8. Sassolas, Audrey, et al. “Optical detection systems using immobilized aptamers.” ...9. Song, Kyung-Mi, et al. “Aptamers and Their Biological Applications.” Sensors (Basel). 2012; 12(1): ...