Research articles

It is shown that if individuals vary in their degree of cooperativeness, and if they can decide whether or not to continue interacting with each other on the basis of their respective levels of cooperativeness, then cooperation can gradually evolve from an uncooperative state. These results highlight the importance of individual behavioural differences in fostering the evolution of cooperation.

The location of microearthquakes beneath a hydrothermal vent field on the East Pacific Rise has been mapped to shed light on hydrothermal pathways at this location. The earthquake locations indicate that a hydrothermal down-flow zone is located on the ridge axis and that hydrothermal flow is oriented along the ridge axis, arguing that models that suggest hydrothermal cells are orientated across-axis, with off-axis recharge zones, may not apply to the East Pacific Rise.

The wafer-scale electrochemical synthesis of arrays of rough silicon nanowires is reported, as is their substantially reduced thermal conductivity, which improves their potential for thermoelectric applications.

Widespread sense-antisense transcripts have been identified in mammalian cells. Many tumour suppressor genes have nearby antisense RNAs, and an antisense RNA to the cyclin-dependent kinase inhibitor p15 can silence the p15 gene by inducing heterochromatin formation.

A new machaeridian from the Early Ordovician of Morocco with preserved soft parts is reported, showing that machaeridians are the calcareous plates carried on the back of a hitherto unknown form of segmented worm, resolving a 150-year-old mystery.

Chronic granulomatous disease is associated with lack of NADPH activity in phagocytes and characterized by recurrent bacterial and fungal infections as well as exagerated inflammation. This paper shows that the excessive inflammation can be attributed to the lack of NAPPH-derived reactive oxygen which is required for the conversion of tryptophan to kynurenine.

The microRNAs miR-126 and miR-335 have an important role in breast cancer tumourigenesis and metastasis. Loss of miR-335 expression promotes breast cancer cell invasion by targeting SOX4 and tenascin C. In breast cancer patients, loss of miR-126 and miR-335 expression is indicative of a poor prognosis.

The basis of regulation of proliferation of pluripotent embryonic stem cells has been unclear. It is found that endogenous GABA receptor signalling controls proliferation of embryonic stem cells and other tissue-specific stem cell types via a mechanism that involves cell cycle proteins previously associated with cellular DNA damage responses.

It is argued that a quiescence state in nematodes, 'lethargus', presents many similarities with sleep as defined in mammals and flies. cGMP signalling is also identified as a new pathway involved in sleep control in both Caenorhabditis elegans and Drosophila. As lethargus is associated with the worm's larval molts, they suggest that sleep may have evolved to allow for developmental changes.

Reducing agents can activate different members of the transient receptor potential (TRP) superfamily of ion channels (TRPC1 and TRPC5) by breaking a disulphide bridge in the extracellular loop adjacent to the ion permation pore. A high concentration of the endogenous reducing agent, thioredoxin, is present in rheumatoid arthritis and may reduce secretion of matrix metalloproteinases by its inhibition of TRPC1 and TRPC5.

A novel poly(ADP-ribose)-binding zinc finger (PBZ) motif is identified. This motif is found in several eukaryotic checkpoint and DNA repair proteins, such as CHFR and APLF. Mutations in the PBZ of CHFR affect its function in checkpoint regulation, suggesting that both the poly (ADP-ribosyl)ation of proteins, and the interaction of this modification with other factors, is important for the DNA damage response.

There is a general consensus that planets form within disks of dust and gas around newly born stars. However, the timescale of planet formation remains unclear. The detection of a planet of mass 9.8 ± 3.3 M_Jupiter around TW Hydrae, a nearby young star with an age of only 8–10 Myr, orbiting with a period of 3.56 days is reported. This demonstrates that planets can form within 10Myr, before the disk has been dissipated by stellar winds and radiation.

People with Down's syndrome seem to have a decreased incidence of solid tumours. This paper reports a mouse model for intestinal tumours in which trisomy for a subset of mouse orthologues of chromosome 21 genes reduces tumour incidence, whereas monosomy of the same genes increases the number of tumours. This dosage-dependent effect can to a large extent be attributed to the transcription factor Ets2.

A metabolic engineering approach is used to re-engineer Escherichia coli so that it could produce higher alcohols from glucose, a renewable energy source. The strategy involves diverting intermediates in the amino acid biosynthetic pathway to synthesize the desired alcohol and may facilitate the large-scale production of biofuels via microbial fermentation.

The structure of truncated Neurospora crassa mitochondrial tyrosyl-tRNA synthetase (CYT-18) with the intron ribozyme T wort orf142-I2 is solved. The interaction surface is different than that used by CYT-18 to bind tRNATyr when it is functioning as a tyrosyl-tRNA synthetase. The protein serves as a scaffold that extends the intron, facilitating its splicing function.