Early star-forming galaxies and the reionization of the Universe

Star forming galaxies represent a valuable tracer of cosmic history. Recent observational progress with Hubble Space Telescope has led to the discovery and study of the earliest-known galaxies corresponding to a period when the Universe was only ~800 million years old. Intense ultraviolet radiation from these early galaxies probably induced a major event in cosmic history: the reionization of intergalactic hydrogen. New techniques are being developed to understand the properties of these most distant galaxies and determine their influence on the evolution of the universe.Comment: Review article appearing in Nature. This posting reflects a submitted version of the review formatted by the authors, in accordance with Nature publication policies. For the official, published version of the review, please see http://www.nature.com/nature/archive/index.htm

Galaxies in the first billion years: Implications for re-ionization and the star formation history at z>6

We discuss the selection of star-forming galaxies at z6 through the Lyman-break technique. Spitzer imaging implies many of these contain older stellar populations (>200Myr) which produce detectable Balmer breaks. The ages and stellar masses (1010M) imply that the star formation rate density at earlier epochs may have been significantly higher than at z6, and might have played a key role in re-ionizing the universe. © 2007 International Astronomical Union

Developmental vitamin D deficiency alters dopamine-mediated behaviors and dopamine transporter function in adult female rats

Developmental vitamin D (DVD) deficiency has been proposed as a risk factor for schizophrenia. DVD deficiency in neonatal rats is associated with alterations in cellular development, dopamine metabolism, and brain morphology. DVD-deficient adult rats show novelty-induced hyperlocomotion and an enhanced locomotor response to MK-801, which can be ameliorated by pretreatment with the antipsychotic drug haloperidol. In this study, we examined locomotor responses of male and female juvenile and adult rats to a dose range of amphetamine. We also measured dopamine receptor and monoamine transporter densities in adult brain. Female DVD-deficient adult rats displayed an enhanced sensitivity to amphetamine-induced locomotion, an increased dopamine transporter density in the caudate-putamen and increased affinity in the nucleus accumbens compared with control females. By contrast, there were no differences between control and DVD-deficient male rats. Taken together, this suggests an alteration in the development of the dopamine system and on dopamine-mediated behaviors in female DVD-deficient rats, and this may be relevant to the underlying neurobiology of schizophrenia

Instability, unfolding and aggregation of human lysozyme variants underlying amyloid fibrillogenesis.

Tissue deposition of soluble proteins as amyloid fibrils underlies a range of fatal diseases. The two naturally occurring human lysozyme variants are both amyloidogenic, and are shown here to be unstable. They aggregate to form amyloid fibrils with transformation of the mainly helical native fold, observed in crystal structures, to the amyloid fibril cross-beta fold. Biophysical studies suggest that partly folded intermediates are involved in fibrillogenesis, and this may be relevant to amyloidosis generally