Articles in 2007

MicroRNAs (miRNAs) can regulate gene expression is by preventing translation of a target mRNA.

This is because a complex involved in processing miRNAs, RISC, associates with the 60S ribosome subunit and the eIF6 translation initiation factor. As the eIF6 can prevent the 60S subunit from assembling into a mature 80S ribosome, interaction of eIF6 with RISC may block ribosome recycling or initiation.

The genome of the grey short-tailed opossum Monodelphis domestica has been sequenced and analyzed, giving a first peek at a marsupial's genetic code. Of particular interest are the genetics of the immune system, which has been studied as a model for humans, and of the X chromosome for historical reasons.

A Sup35 chimaera that traverses the transmission barrier between two yeast species possesses the critical sequence elements from both. This chimaera is used to show that the influence of environment and mutations on the formation of species-specific strains is driven by selective recognition of either sequence element. Thus, critical aspects of prion conversion are enciphered by subtle differences between small, highly specific recognition elements.

The X-ray crystal structure of plant photosystem I is solved to 3.4 Å resolution, revealing 17 protein subunits. This structure provides a picture of 11 out of 12 protein subunits of the reaction centre, 168 chlorophylls, two phylloquinones, three Fe₄S₄ clusters, and five carotenoids.

Degenerative diseases such as Alzheimer's or Parkinson's are associated with the misfolding of many diverse proteins, yet the amyloid fibrils formed by all these proteins are similar. David Eisenberg and colleagues have now identified 30 short fibril-forming peptides implicated in a range of amyloid diseases and have solved 13 of their atomic structures, revealing variations in one common feature — the 'steric zipper'.

In transgenic mice with temporally and spatially restricted neurodegeneration, fear memories formed before induction of neuronal loss can be restored by environmental enrichment, even though the degeneration does not recover. Histone deacetylase inhibitors mimic the effects of environmental enrichment .

Over 50 years ago, von Neumann derived an exact formula for the growth rate of a cell in a two-dimensional cellular structure. Now the extension of this result into three (and higher) dimensions has been found. The formula could lead to predictive models for various industrial and commercial processing scenarios, such as controlling the head on a pint of beer.

Several neurodegenerative diseases are caused by expansion of CAG triplet repeats, and, using a mouse model of human Huntington's disease, this study shows that this expansion occurs in mid-life and continues throughout life; furthermore, the expansion occurs in terminally differentiated cells. This is associated with oxidative damage, and deficiency in OGG1, a DNA repair enzyme, attenuates age-dependent repeat expansion — thus it seems that aberrant repair of oxidative damage is the basis for this disease.

According to Bell's theorem, any theory that is based on the joint assumption of realism and locality is at variance with certain quantum predictions. Here, theory and experiment agree that a class of such non-local realistic theories is incompatible with experimentally observable quantum correlations, suggesting that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned.

Previous studies identified genes involved in tissue-specific metastasis of breast cancer cells to the lung. New work now shows how four of these genes cooperate to remodel the vasculature and thereby both tumour cell intravasation into the circulation and extravasation of blood vessels in the lung to form metastases.

A time-resolved observation of electron tunnelling and the short-lived electronic states that subsequently appear is useful as a new approach to obtain insights in multi-electron dynamics inside atoms and molecules. This technique of 'attosecond tunnelling' is applied to study the cascade of electronic transitions that occur in xenon atoms as a result of their ionization.

Study of the crystal structures of three different auxin compounds in complex with the receptor transport inhibitor response 1, as well as an Aux/IAA peptide, reveals that auxin acts as 'molecular glue' to promote interactions between the receptor and protein substrates targeted for degradation.

A light-activated chloride pump that occurs naturally in bacteria can be transfected into neurons, thereby permitting inhibition of neural activity on a millisecond timescale. This complements an existing tool for activating neurons through a photoactivatable algal channel.

A massive compliation of molecular data to shows that not only did mammalian evolution have deep roots, but that the extant Orders of mammals did not become established until many millions of years after the dinosaurs had headed for their last round-up. In other words, the great end-Creatceous mass extinction had relatively little effect on mammal evolution.

Members of the hapalindole, fischerindole, welwitindolinone and ambiguine families were synthesized, each constructed without the use of a single protecting group. As a consequence, molecules that have previously required 20 or more steps to synthesize racemically in milligram amounts can now be procured as single enantiomers in significant quantities in 10 steps or less.