Gene transfer to plants by diverse species of bacteria

Agrobacterium is widely considered to be the only bacterial genus capable of transferring genes to plants. When suitably modified, Agrobacterium has become the most effective vector for gene transfer in plant biotechnology. However, the complexity of the patent landscape has created both real and perceived obstacles to the effective use of this technology for agricultural improvements by many public and private organizations worldwide. Here we show that several species of bacteria outside the Agrobacterium genus can be modified to mediate gene transfer to a number of diverse plants. These plant-associated symbiotic bacteria were made competent for gene transfer by acquisition of both a disarmed Ti plasmid and a suitable binary vector. This alternative to Agrobacterium-mediated technology for crop improvement, in addition to affording a versatile 'open source' platform for plant biotechnology, may lead to new uses of natural bacteria-plant interactions to achieve plant transformation.     

Evolutionary genetics: Ambiguous role of CCR5 in Y. pestis infection

Mecsas and colleagues suggest that a deficiency in the chemokine receptor CCR5 in humans is unlikely to confer protection against plague, based on their study of Yersinia pestis infection in Ccr5-deficient mice. They were testing the hypothesis that a mutation in the CCR5 gene, frequently found in Caucasians, may have been selected for in the past because it provided protection against (bubonic) plague; the mutation, called CCR5Delta32, is characterized by a 32-base-pair deletion. We have also tested this hypothesis by using Y. pestis infection in mice and, in addition, we have done phagocytosis experiments with macrophages from wild-type and Ccr5-deficient mice. Although, like Mecsas et al., we did not see any difference in the survival of the two groups of mice, we did find that there was a significantly reduced uptake of Y. pestis by Ccr5-deficient macrophages in vitro. Our results indicate that the role of Ccr5 in Y. pestis infection may therefore be more complex than previously thought.     

A three-dimensional optical photonic crystal with designed point defects

Photonic crystals offer unprecedented opportunities for miniaturization and integration of optical devices. They also exhibit a variety of new physical phenomena, including suppression or enhancement of spontaneous emission, low-threshold lasing, and quantum information processing. Various techniques for the fabrication of three-dimensional (3D) photonic crystals--such as silicon micromachining, wafer fusion bonding, holographic lithography, self-assembly, angled-etching, micromanipulation, glancing-angle deposition and auto-cloning--have been proposed and demonstrated with different levels of success. However, a critical step towards the fabrication of functional 3D devices, that is, the incorporation of microcavities or waveguides in a controllable way, has not been achieved at optical wavelengths. Here we present the fabrication of 3D photonic crystals that are particularly suited for optical device integration using a lithographic layer-by-layer approach. Point-defect microcavities are introduced during the fabrication process and optical measurements show they have resonant signatures around telecommunications wavelengths (1.3-1.5 microm). Measurements of reflectance and transmittance at near-infrared are in good agreement with numerical simulations.     

Unexpectedly recent dates for human remains from Vogelherd

The human skeletal remains from the Vogelherd cave in the Swabian Jura of southwestern Germany are at present seen as the best evidence that modern humans produced the artefacts of the early Aurignacian. Radiocarbon measurements from all the key fossils from Vogelherd show that these human remains actually date to the late Neolithic, between 3,900 and 5,000 radiocarbon years before present (bp). Although many questions remain unresolved, these results weaken the arguments for the Danube Corridor hypothesis--that there was an early migration of modern humans into the Upper Danube drainage--and strengthen the view that Neanderthals may have contributed significantly to the development of Upper Palaeolithic cultural traits independent of the arrival of modern humans.     

Lung cancer: intragenic ERBB2 kinase mutations in tumours

The protein-kinase family is the most frequently mutated gene family found in human cancer and faulty kinase enzymes are being investigated as promising targets for the design of antitumour therapies. We have sequenced the gene encoding the transmembrane protein tyrosine kinase ERBB2 (also known as HER2 or Neu) from 120 primary lung tumours and identified 4% that have mutations within the kinase domain; in the adenocarcinoma subtype of lung cancer, 10% of cases had mutations. ERBB2 inhibitors, which have so far proved to be ineffective in treating lung cancer, should now be clinically re-evaluated in the specific subset of patients with lung cancer whose tumours carry ERBB2 mutations.     

What’s new in the renin-angiotensin system?

The type 1 angiotensin receptor (AT(1)) activates an array of intracellular signalling pathways that control cell and tissue responses to the peptide hormone angiotensin II (AngII). The capacity of AT(1) receptors to initiate and maintain such signals has typically been explained on the basis of conventional heterotrimeric guanine nucleotide binding protein (G protein) activation, specifically G(q/11). Accumulating evidence from studies utilising a variety of AT(1) receptor mutants and AngII analogues indicates that some important downstream effects of AT(1) receptors are independent of classical G protein coupling. Importantly, AT(1) receptor-mediated endocytosis, tyrosine phosphorylation signalling and mitogen-activated protein kinase activation as well as transactivation of the epidermal growth factor receptor can occur in G(q/11)-uncoupled receptor mutants. These observations point to a functional partitioning of AT(1) receptor signals that permits separation of short-term AngII actions (e.g., vasoconstriction) from more extended events, such as pathological cell growth in heart and blood vessels, and may open up new avenues for selective antagonism.     

Light echoes from ancient supernovae in the Large Magellanic Cloud

The light from historical supernovae could in principle still be visible as scattered-light echoes centuries after the explosion. The detection of light echoes could allow us to pinpoint the supernova event both in position and age and, most importantly, permit the acquisition of spectra to determine the 'type' of the supernova centuries after the direct light from the explosion first reached Earth. Although echoes have been discovered around some nearby extragalactic supernovae, targeted searches have not found any echoes in the regions of historical Galactic supernovae. Here we report three faint variable-surface-brightness complexes with high apparent proper motions pointing back to three of the six smallest (and probably youngest) previously catalogued supernova remnants in the Large Magellanic Cloud, which are believed to have been thermonuclear (type Ia) supernovae. Using the distance and apparent proper motions of these echo arcs, we estimate ages of 610 and 410 years for two of them.