SCI-TECH

Arising from: H. Müller, A. Peters & S. Chu Nature463, 926–929 (2010); Müller & Chu replyIn ref. 1 the authors present a re-interpretation of atom interferometry experiments published a decade ago. They now consider the atom interferometry experiments as a measurement of the gravitational redshift on the quantum clock operating at the Compton frequency ωC = mc2/ ≈ 2π × 3.0 × 1025 Hz, where m is the caesium (Cs) atom rest mass. They then argue that this redshift measurement compares favourably with existing as well as projected clock tests. Here we show that this interpretation is incorrect.

Replying to: P. Wolf et al.Nature doi:10.1038/nature09340 (2010)We stand by our result. The Comment revisits an interesting issue that has been known for decades. Because it applies to all experiments, classical redshift tests and atom interferometry redshift tests are equivalent for all aspects in question.

Arising from: S. K. Singh et al.Nature453, 223–227 (2008); Singh et al.replyThe contribution of REST to embryonic stem (ES) cell pluripotency has been uncertain. Two years ago, Singh et al. claimed that Rest+/− and REST knock-down ES cells expressed reduced levels of pluripotency markers, in contrast to a prior and subsequent reports. To understand the basis of this difference, we analysed the YHC334 (YHC) and RRC160 (RRC) gene-trap ES cell lines used by Singh et al., obtained directly from BayGenomics. Both REST mutant lines generated REST–βGeo fusion proteins, but expressed pluripotency genes at levels similar to appropriately matched parental wild ES cells, consistent with expression being REST–independent.

Replying to: H. F. Jørgensen & A. G. Fisher Nature 467, doi:10.1038/nature09305 (2010)Jørgensen and Fisher suggest that the discrepancy with our results could be attributable to our use of E14Tg2a (or its derivatives, such as OS25) rather than E14Tg2a.4 as the parental control line for the REST+/− cells (YHC and RRC). We have now reconfirmed our use of E14Tg2a.4 clonal cells as the control cells. Also, we have found that the YHC and RRC cells used in our experiments, originally purchased from Bay Genomics, differ from the YHC and RRC cells used by Jørgensen and Fisher with respect to pluripotency-based on alkaline phosphatase/self-renewal assays (N. Song and S.K.S., unpublished results). We are currently using other assays to confirm these observations.

Congress must act quickly to save US stem-cell research.

Earth scientists have explained why Canada and South Africa are still here.

Proc. Natl Acad. Sci. USA doi:10.1073/pnas.1005743107 (2010)Nets of DNA fibres and antimicrobial proteins in blood vessels ensnare and kill microbes during infection, and may also provide a scaffold for blood clots.The immune system relies on these meshes, known

Science doi:10.1126/science.1195778 (2010)Two planets roughly the size of Saturn have been discovered orbiting a star similar to the Sun 650 parsecs away. As they zip around their parent star in 19.2 and 38.9 days, respectively, the duo tug on

N. Engl. J. Med.363, 809–819 (2010) 10.1056/NEJMoa1002011A small clinical trial has shown promising results for a targeted therapy against one of the most aggressive and intractable forms of cancer: metastatic melanoma.The drug, named PLX4032, inhibits a

J. Neurosci.30, 11028–11031 (2010) 10.1523/JNEUROSCI.1317-10.2010The sea slug Aplysia californica (pictured) has for years been the subject of learning studies, which have shown that the creature retracts its head, gills and tail defensively much more quickly in

Sci. Transl. Med.2, 46ra61 (2010) 10.1126/scitranslmed.3001022Artificial corneal transplants improved the sight of more than 50% of patients with vision loss in a small two-year clinical trial.The cornea is the eye's outermost lens, vital for controlling and focusing light

Geophys. Res. Lett. doi:10.1029/2010GL043733 (2010)Severe storms that swept across Amazonia in January 2005 destroyed around half a billion trees, a loss estimated to equal 23% of the mean annual carbon accumulation in the Amazon's forests.Storms often topple trees

J. Neurosci.30, 11476–11485 (2010) 10.1523/JNEUROSCI.5252-09.2010People with psychiatric conditions could one day have the activity of their brain cells modified by low-level electrical stimulation, applied through electrodes on the scalp.According to György Buzsáki at Rutgers University in

Science329, 1053–1057 (2010) 10.1126/science.1190672A porous material that increases its pore size as it adsorbs certain molecules is the latest creation from researchers at the University of Liverpool, UK.Matthew Rosseinsky and his colleagues made the material by

Proc. R. Soc. B doi:10.1098/rspb.2010.1390 (2010)Female fruitflies are known to shun repeated sexual encounters when nutrients are scarce, a probable adaptation to a meagre environment in which offspring are less likely to survive. Signalling in the nutrient-sensing insulin pathway

Genome Res. doi:10.1101/gr.107987.110 (2010)In bowel diseases, the balance of the gut's microbial species, which number more than 1,000, can be thrown off. Researchers have speculated that transplanting a collection of microbes from the guts of healthy individuals into those

A materials scientist comments on two methods for three-dimensional nanofabrication.Methods for nanofabrication are crucially important to research in all areas of nanoscience and nanotechnology because they allow for the creation of functional structures — a key step towards useful applications and devices. Many techniques

The week in science.

US district-court ruling suspends federal funding for research involving human embryonic stem cells.

Review recommends better governance and transparency for the IPCC in the face of more public scrutiny.

Fishing industry threatens to destabilize stocks.

Confounding reports seed confusion over long-term effects of the spill.

Extreme weather wreaks havoc in the rivers.

The US National Nanotechnology Initiative has spent billions of dollars on submicroscopic science in its first 10 years. Corie Lok finds out where the money went and what the initiative plans to do next.

When oil stopped gushing into the Gulf of Mexico, the ecosystems under assault started on a long road to recovery. Amanda Mascarelli meets the researchers assessing their chances.