Articles in 2007

This paper reports the ability to isolate human donor biopsies and use transcription factors to derive induced Pluripotent Stem (iPS) cells from fetal, neonatal, and adult human primary cells, including dermal fibroblasts isolated from a skin biopsy of a healthy adult volunteer. The human iPS cells resembled embryonic stem cells in their morphology and gene expression. These data establish a method to isolate iPS cells from patients, suggesting that it may be possible to use this procedure to isolate patient-specific cells in culture.

Use of neuronal imaging and photoactivation techniques on hippocampal pyramidal dendrites has shown that after long-term potentiation induction at individual synapses, neighbouring synapses become more easily potentiated, and across a broader time window. These results offer a new scale of information integration available for those modelling the cellular processes underlying brain function.

The crystal structure of the part of yeast topoisomerase II that binds DNA and catalyses breakage formation in complex with a gate DNA is solved. The enzyme sharply bends the DNA, which brings the DNA near the catalytic site and breaks a dimer interface of the protein, thereby opening a protein gate.

A transposon surveillance and genome organization mechanism is described in fission yeast. CENP-B proteins bind to Tf2 retrotransposons and mediate their silencing by recruiting histone deacetylases. CENP-B proteins are also required for the clustering of Tf2 retrotransposons into network-like structures in the nucleus.

In plants and fungi, cellular ion homeostasis is powered by the proton pump, a member of the P-type ATPase family. The first X-ray structure of the H⁺-ATPase is presented, and insight into the mechanism by which protons are transported against an electrochemical gradient is provided

The halo of the Milky Way is clearly divisible into two broadly overlapping structural components, an inner and an outer halo. While the inner halo has a modest net prograde rotation, the outer halo exhibits a net retrograde rotation and a peak metallicity one third that of the inner.

Relatively little is known about the mechanisms that underlie the active transport of ions by Na⁺,K⁺-ATPase. A 3.5 Å X-ray structure of this fundamental protein is presented, revealing the two binding sites for potassium.

How the Sec translocon recognises transmembrane α-helices in newly synthesised proteins is revealed by the analysis of a large number of hydrophobic segments and presentation of a quantitative analysis of the position-dependent contribution of efficiency of membrane insertion for all amino acids. The results support the idea that recognition of transmembrane helices by the Sec translocon is a lipid-partitioning process.

The yeast chromatin remodelling complex Isw2 repositions nucleosomes that are adjacent to promoter regions and enforces directionality on transcription by preventing inappropriate transcription initiation from cryptic sites.

A receptor for the Drosophila melanogaster sex peptide (SP), the primary trigger of post-mating responses, is identified. Females lacking the sex peptide receptor (either entirely or only in the nervous system) fail to respond to SP and continue to show virgin behaviours, even after mating.

Cryo-electron tomography of vitreous section from human skin is used to investigate the architecture of cadherin molecules in desmosomes under near native conditions. Three-dimensional reconstructions and fitting of existing X-ray crystallography data reveal a regular array of molecules in desmosomes, that is consistent with data derived previously using different methods.

Tumours promote Bv8 expression in myeloid cells in the bone marrow. Bv8 acts on endothelial cells to directly promote tumour angiogenesis as well as to promote the recruitment of CD11b⁺Gr1⁺ myeloid cells from the bone to tumours.

A model study of the coupled evolution of the carbon cycle and the climate system during the Neoproterozoic is presented. This finds that more oxygen is taken up by a cooling ocean, which converts organic into inorganic carbon more efficiently, creating a negative feedback loop that stabilises low carbon dioxide levels and prevents total glaciation.

Tachycardia can be prevented by engrafting embryonic cardiomyocytes into mice. A protein resident at 'gap junctions', connexin 43, is also identified as being important for this protection. Expression of this protein in skeletal myoblasts achieves similar levels of protection. These results suggest a new approach to cell-based therapy for cardiac dysfunction.

A combination of genetics and electrophysiology is used to tease apart synchronous and asynchronous releases of neurotransmitter at nerve terminals, and the existence of independent calcium sensors is proposed. The first quantitative model to account for the full range of calcium-dependence of synaptic transmission is also provided.

A study of endocytosis of Shigella toxin shows that it enters cells via narrow tubular membrane invaginations, with similar properties on cell and model membranes. The toxin induces membrane reorganisation before the formation of tubular invaginations.

The ciliate Oxytricha trifallax cuts up and removes most of its nuclear DNA during one developmental stage, stitching 5% of its chromosomes back together at specific points. This paper demonstrates that maternal RNA remaining in the new cell could serve as a template for the chromosomal rearrangements, as shown by the disruption of proper assembly when several RNAs are removed from the cell.