GFP strikes again.

Is there simply no end to what "GFP" can be made to do? The Russian group lead by Lukyanov have publshed another important paper in this field; this time they have made a mutant of DsRed which they call "Killer Red" (cool name!) that can be used for genetically targeted CALI. They find one set of mutants in their screening that micraculously produces a good deal of singlet oxygen. They tested many other RFPs and only KillerRed had this useful property. Probably the best expt they did was tad a PH domain with eGFP and KillerRed (or DsRed). The effects of irradiation of both constructs was strikingly different: only the former inactivated the PH domain, as shown by dissociation of the eGFP signal from the plasma membrane, and concomitant increase of cytosolic fluorescence.

(Nature Biotechnology (2006) 24: 95-99; doi:10.1038/nbt1175)

Bush, global warming and scientific censorship.

According to The New York Times and The Washington Post, the Bush administration told NASA to remove their posting on global temperature rise:
http://data.giss.nasa.gov/gistemp/2005/
Didn't the Catholic Church's Inquisition tell Galileo that the earth did not move, and Hilter's "scientists" try to use phrenology to define their so-called master race?

Faculty of a 1000 rated our Nature Methods papers "must read"!

Micheal Pirrung evaluated our paper on 23 Jan 2006: "This article provides the first new chromophore useful for the caging of bioactive molecules in quite some time. The NDBF group has a very high absorptivity and an excellent quantum yield, which make its photochemical deprotection one of the most efficient known. The NDBF group also has a reasonable two-photon cross section that enables it to be used in two-photon uncaging, giving high spatial control and minimal damage to living systems."
http://www.f1000biology.com/article/16369551/evaluation

Pirrung is chemist who is a pioneer in the development of caged compounds. His most imporant work is probably the development of the original photoaddressable organic-synthesis-on-a-chip technique with Fodor and Stryer that formed the basis of the technology used by Affymetrix (Science (1991) 251:767).

UV versus 2-photon uncaging.

At the last Annual Meeting of the Society for Neuroscience there was a “MINI-symposium” entitled: “Flashy science: controlling neural function with light.” A report of the talks has been published in J. Neurosci. (2005) 25: 10358-10365 (DOI:10.1523/JNEUROSCI.3515-05.2005). Scott Thompson is the communicating author of this report and writes about his own work (Science (2001) 293: 2272–2275) on UV uncaging of CNB-glu or Nmoc-glu in comparison to the work we have done using 2-photon uncaging of MNI-glu (Nature Neuroscience (2001) 4: 1086-1092). Thompson says that the Mill Hill group lead by David Ogden found that the 2-photon cross-section of MNI-glu is “low (Kiskin et al., 2002), so that it requires high intensities or extend illumination (Carter and Sabatini, 2004) to achieve millimolar concentrations . The power levels necessary can induce photodamage (Kiskin et al., 2002).”

There are several serious errors of fact in these statements.

Firstly, The Mill Hill group did not measure the 2-photon cross-section of MNI-glu in the 2002 paper (they did not even use MNI-glu in their work), we did in our 2001 paper.

Secondly, the duration of uncaging by Carter & Sabatini was 200-500 microseconds, most would not characterise this period as “extended”, though it is 10-times longer than UV uncaging used by Thompson.

Thirdly, the photodamage that the Mill Hill group found from 2-photon excitation came about at 640 nm not 720 nm-there is a huge difference in photoxicity between these two wavelengths, so Thompson is tarring us with brush that does not apply. Equally significantly, the toxicity found by the Mill Hill group was using 500-1000 uncaging events at a single point at power levels greater than 7 mW-a power dosage we do not even come close to in our work.

Thus, Thompson’s comparison of his own UV uncaging with our 2-photon work is disingenuous.

Carter AG, Sabatini BL (2004) State-dependent calcium signaling in dendritic spines of striatal medium spiny neurons. Neuron 44: 483–493.

Kiskin NI, Chillingworth R, McCray JA, Piston D, Ogden D (2002) The efficiency of two-photon photolysis of a “caged” fluorophore, o-1-(2nitrophenyl)ethylpyranine, in relation to photodamage of synaptic terminals. Eur Biophys J 30: 588–604.