Since light-sensitive holoproteins are formed in the phytochrome-PIF interaction from apo-PhyB and PCB (Arabidopsis thaliana), and such interactions depends on reversibily conformational changes induced by red and infrared light, reversible protein movements into cells were obtained as exemplified by the light-induced translocation of a YFP-tagged PIF domain to a PhyB-mCherry localized in the plasma membrane. (Nature 2009, 461:997)

Also combining the FKF1 and GIGANTEA (GI) proteins of A. thaliana it is possible to induce protein-protein interaction in live cells using light. The trick is exploited to create a light-activated transcription factor. (Nature Biotechnology 2009, 27:941)

Following brainbow lesson, a new binary 16 color-coding system using 4 fluorescent reporters labels distinct cell populations in developing mouse and follows them with time-lapse movies during development. (Genesis 2009, 47:708)

A protocol for non-invasively monitoring miRNAs exploits miRNA124a-dependent decrease of Gaussia luciferase reporter activity during neurogenesis and differentiation. (Nature Protocols 2009, 4:1663)

A new text-mining web database was released to collect info about the characterization or use of mouse strains that express Cre recombinase as well as papers that describe or analyze mouse lines that carry conditional (floxed) alleles or Site-Specific Recombinases activated transgenes/knockins. Textpresso SSR.

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This blog represents only some of my lazy academic opinions and does not feed any subtle commercial goal. In the past, there was some ads in the sidebar. This was done with the major aim to offer contextual interesting content to the readers. However, in the last six months, my sharp editorial cut failed to find ANY relevant Advertisement. As a process of natural evolution, today Reportergene became Ad-free. Characters providing better performance are fixed in nature. In this context, ads were NOT giving any performance to the site, and were lost. Ads remain only in the search-box and are automatically generated by google: if you are looking for something specific, maybe you want explore also current commercial solutions.

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A new Nature letter has the potential to abnormally extend (until extinction) the whole spectrum of reporter genes. So far, "reporters" were those genes coding for an easily detectable product (i.e., those coding for fluorescent or luminescent proteins). Wei Min and other Harvard's colleagues introduced a new technique, namely stimulated emission microscopy, that seems able to turn into mini-lasers any non-fluorescent light-absorbing molecule. It means that several chromophores, such as haemoglobin and cytochromes, can now be directly detected through a new contrast mechanism for optical microscopy which is orders of magnitude more sensitive than absorption, is not subject to interference from other chromophores in the sample, and is amenable to three-dimensional sectioning. This open the race to the intelligent design of new chromo-reporters able to produce images of unlabelled, non-fluorescent molecules at sub-diffraction (nanoscale) resolution. Seeing is believing. The potential to kill the field of reporters is easily explained: who ever need a "reporter" when you can spy in a cell the whole bunch of molecular processes with resolutions at googlemeter per googlesecond?

Min, W., Lu, S., Chong, S., Roy, R., Holtom, G., & Xie, X. (2009). Imaging chromophores with undetectable fluorescence by stimulated emission microscopy Nature, 461 (7267), 1105-1109 DOI: 10.1038/nature08438

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The 2005 Burbelo's method to reverse profile antibody responses to single or multiple antigens (LIPS, Luciferase Immunoprecipitation Systems) is now available as a video protocol on Jove. The overall approach involves expressing chimeric genes encoding probe antigens fused to Renilla luciferase (RLuc). Crude RLuc-antigen extracts are then mixed with sera in examen and A/G beads to quantify and profile interacting antibodies present in sera: when the RLuc-antigen fusion become immobilized on the A/G beads, antigen-specific antibody is quantitated by washing the beads and adding coelenterazine lucifease substrate and measuring light production. Luciferase il like parsley: you can add it in most recipes.

Btw, does anyone has ever got a luciferase antibody that really works?

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Plants contain proteins subjected to conformational changes in direct response to light irradiation. Moieties of those proteins, like the LOV2 domain from the Avena sativa Phototropin1 can be used to introduce light-operated switches onto other functional proteins. In a recent letter to Nature, Yi Wu and colleagues (Carolina University) poked at the Stratagene Quickchange kit to obtain a constitutive active Rac protein that was coupled to the vegetable LOV2 light switch using an overlapping PCR approach. The result of such a cut and paste was genetically encoded into HeLa, HEK93 and MEF/3T3 cell lines. Then, by irradiating whole cells or even localized micro-spot on the cell surface, PA-Rac1 was sufficiently photo-activated to generate polarized cell movements. In other words, light was controlling the motility of living cells via photoactivable Rac. Structural studies indicate that the Rac-LOV2 interface can be engineered to cage other proteins. Engineering and Biology are getting married. If you are a kick ass engineer, consider hacking biology at Ginkgo BioWorks, they are hiring.

Wu, Y., Frey, D., Lungu, O., Jaehrig, A., Schlichting, I., Kuhlman, B., & Hahn, K. (2009). A genetically encoded photoactivatable Rac controls the motility of living cells Nature, 461 (7260), 104-108 DOI: 10.1038/nature08241

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A new theory from Prof-like Substance states that everyting is cutting-edge with the "-omics" ending and funny with the "-opotamus" one. Since it sounded funny to me reading "metabolomics", with "metabolopotamus" I got seizures. Try your own distorsion.

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hidden life of GPCR receptors unveiled with reporter approaches

Two recent studies exploited reporter genes to unveil hidden secrets of GPCR signaling which is apparently harder to die than expected. From the cell surface, G-Protein Coupled Receptors are activated by the intended ligand. According to the current feed-back dogma, excessive stimulation results in de-activation (de-sensitization) of the receptor and subsequent internalization.

• With a genetically-encoded FRET sensor, Païkan Marcaggi and colleagues noted on PNAS that prolonged exposure to a ligand (glutamate) actually increases the sensitivity of the receptor (mGluR) to its ligand, in marked contrast to the desensitization typically observed in such receptors. The group is prototyping a model for receptor activity in which mGluR1 signaling behavior relates primarily to overall duration of glutamate release rather than fluctuations in local neurotransmitter concentration.
• Following down the feed-back dogma, once internalized, GPCRs are supposed to stop signaling. Davide Calebiro and colleagues recently shared on PLOS Biology the results obtained with a transgenic mouse expressing a fluorescent sensor for GPCRs signaling. By analysing second messengers dynamics, they showed that a GPCR continues to stimulate second messenger production in a sustained manner after internalization.

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Gaussia luciferase (GLuc) holds the promise to became a great reporter. In the native form, GLuc is secreted. This feature gives additional advantages, but markedly attenuates its application for in vivo imaging. At MSKCC.org, Elmer Santos and colleagues recently described on Nature Medicine a membrane anchored external GLuc (termed extGluc) genetically engineered through the addition of a CD8 transmembrane domain to the carboxy terminus of the enzyme. The strategy to put the reporter outside the cell should be advantageous: the substrate luciferin do not need to enter the cell and variability previously inferred to drug-resistant genes should be avoided. In effect, the new reporter was enough sensitive to monitor in vivo T cells by means of classical bioluminescence imaging on a IVIS workstation.


Santos, E., Yeh, R., Lee, J., Nikhamin, Y., Punzalan, B., Punzalan, B., Perle, K., Larson, S., Sadelain, M., & Brentjens, R. (2009). Sensitive in vivo imaging of T cells using a membrane-bound Gaussia princeps luciferase Nature Medicine, 15 (3), 338-344 DOI: 10.1038/nm.1930

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A Science letter by Robert Stevenson focused my attention on the eventual patentability of new "automated" discoveries. This is of course a letter in response to the "automation of science" previously reviewed. Apparently, it should be legally difficult to patent any invention made by a robot: the American patent law strictly refer to the inventor as "a person", while the European law seems more broad. Thus, supposing a brilliant robot scientist is ever build, no man might protect/deserve those inventions for its proprietary benefit. Legacy is not considered: A invents robot/algorythm B, B invents drug C, but C is not patentable. Honestly, once developed such a robot, it should take no longer to develop a second robot mimicking human creativity (i.e., writing good and bad dates and results on a paper lab-book). Are we so close to Singularity? Interestingly, in a previous Science paper, Debra Meloso from the italian Bocconi University has modeled the patent system and proposed a better way to promote intellectual discovery (maybe including generation of robot-scientists) that should be based on a sort of 2.0 trading of discoveries. Might a machine sell a product? Ask to lawyer Crawford.

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