Letters in 2008

Synthetic biologists aim to apply well-known principles of gene regulation to build living systems with desired properties. This study has combined microfluidics, single-cell microscopy and computational modelling to develop a bacterial gene oscillator that is fast, robust, persistent and whose frequency can be tuned externally. The combination of experimental and theoretical work reveals a simplified oscillator design without the need for positive feedback.

This paper shows that insects possess a structure very similar, both anatomically and functionally, to the blood-filtering tissue of the vertebrate kidney, and raises the possibility that components of the vertebrate excretory system were inherited from their invertebrate ancestors. It is also shown that fly orthologues of the major constituents of the slit diaphragm of the kidney form a complex of interacting proteins similar to the vertebrate slit diaphragm complex.

Many neuromuscular conditions are characterized by an exaggerated exercise-induced fatigue response. This form of inactivity is a major determinant of disability. The mechanism underlying this type of fatigue remains unknown. It is shown in mice that such exaggerated fatigue is due to a lack of contraction-induced signalling from sarcolemma-localized nNOS. In addition, in patient biopsies from a large number of distinct myopathies, sarcolemmal nNOS is reduced—pointing towards a common mechanism of fatigue.

The polar transport of the plant hormone auxin is dependent on the localization of its efflux carriers called PINs, but the mechanism mediating polarity of PIN proteins within cells remains unclear. This study suggests a two-step mechanism generating PIN polarity. PINs are first targeted to the plasma membrane in a non-polar manner, and polarity is established in subsequent step involving internalization and recycling. Interference with endocytosis results in the loss of PIN polarity leading to a perturbation in auxin gradients.

Terminal oxo complexes of transition metals are important in biological and chemical processes, for example, the catalytic oxidation of organic molecules and the activation of dioxygen on metal surfaces are thought to involve oxo complexes. This paper explored the reactivity of a d⁶ Pt(IV) complex, a dⁿ (n > 5) terminal oxo complex that is not stabilized by an electron withdrawing ligand framework. The complex exhibits reactivity as an inter- and intra-molecular oxygen donor and as an electrophile.

A newly discovered F-box protein of Arabidopsis thaliana that promotes twin sperm cell production is identified. The protein, FBL17, targets KRP7, an Arabidopsis inhibitor of CDKA1, for proteasome-dependent degradation, allowing germ cell division and twin sperm cell production.

The transfer of information between processing entities and memory is crucial for quantum computation; it is challenging because the process must remain coherent at all times to preserve the quantum nature of the information. This paper demonstrates coherent storage and readout of information between electron-spin processing elements and memory elements based on a nuclear spin.

This paper reports that a sample of galaxies (first detected from neutral hydrogen emission) shows five independent correlations amongst six independent observables. This implies that the structure of such galaxies must be controlled by a single parameter, which cannot yet be identified. Such a degree of organization is at odds with hierarchical galaxy formation.

It is shown that the amount and geometry of seismic anisotropy measured in the forearc regions of subduction zones strongly depend on the preferred orientation of hydrated faults in the subducting oceanic plate. The anisotropy originates from the crystallographic preferred orientation of highly anisotropic hydrous minerals formed along steeply dipping faults and from the larger-scale vertical layering consisting of dry and hydrated crust–mantle sections, the spacing of which is several times smaller than teleseismic wavelengths.

This paper presents another chapter in the earliest history of birds, with the discovery of a feathered dinosaur from the Mid to Late Jurassic of China. Living a little earlier than the famous fossil bird Archaeopteryx, the newly discovered creature is birdlike in many ways including the presence of four very long tail feathers, but otherwise no sign of flight feathers of the kind seen in birdlike dinosaurs such as Microraptor.

Relative motion between two contacting surfaces can produce visible light, a process known as triboluminescence. Scientists now fully characterize the energy emissions from peeling sticky tape in a vacuum and show the generation of X-rays with sufficient intensity that they were used for X-ray imaging.

The oldest widely accepted evidence for oxygenic photosynthesis comes from hydrocarbon biomarkers extracted from 2.7-billion-year-old shales in the Pilbara Craton, Australia, thought to be evidence of eukaryotes and photosynthetic cyanobacteria. But evidence now shows that the organic biomarkers were not indigenous to the rocks containing them, and must have entered the rocks after ∼2.2 Gyr ago. The earliest unambiguous fossil evidence for eukaryotes and cyanobacteria thus reverts to 1.78–1.68 and 2.15 Gyr, respectively.

In a mouse model, it is found that the loss of the tumour suppressors p53 and Pten leads to the development of tumours resembling human primary glioblastomas, and both p53 and PTEN are frequently lost in the human cancer. Loss of these tumour suppressors impairs the differentiation of neural stem cells, due to upregulation of Myc by the concerted action of p53 and PTEN loss.

This study identifies the most abundant Cu²⁺- and Mn²⁺-containing proteins in the periplasm of a cyanobacterium and determines that the cellular compartment in which each of those proteins fold is responsible for the insertion of the correct metal ion into the metalloprotein.