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<jats:p>Analysis of a recent climatological database for the North Atlantic has detailed an extensive large-scale recirculation system in the intermediate waters of the North Atlantic basin. The pressure fields that define this recirculation, coupled with the potential vorticity fields associated with the recirculating flow, provide observational evidence for basin-scale eddy-driven flow in the global ocean. The recirculations are intimately tied to the waters carried southward by the Deep Western Boundary Current and are therefore likely to affect the distribution of climatic anomalies in the North Atlantic.</jats:p>

<jats:p>Analysis of the global mean surface air temperature has shown that its increase is due, at least in part, to differential changes in daily maximum and minimum temperatures, resulting in a narrowing of the diurnal temperature range (DTR). The analysis, using station metadata and improved areal coverage for much of the Southern Hemisphere landmass, indicates that the DTR is continuing to decrease in most parts of the world, that urban effects on globally and hemispherically averaged time series are negligible, and that circulation variations in parts of the Northern Hemisphere appear to be related to the DTR. Atmospheric aerosol loading in the Southern Hemisphere is much less than that in the Northern Hemisphere, suggesting that there are likely a number of factors, such as increases in cloudiness, contributing to the decreases in DTR.</jats:p>

<jats:p>A genetic block was introduced in the first condensation step of the polyketide biosynthetic pathway that leads to the formation of 6-deoxyerythronolide B (6-dEB), the macrocyclic precursor of erythromycin. Exogenous addition of designed synthetic molecules to small-scale cultures of this null mutant resulted in highly selective multimilligram production of unnatural polyketides, including aromatic and ring-expanded variants of 6-dEB. Unexpected incorporation patterns were observed, illustrating the catalytic versatility of modular polyketide synthases. Further processing of some of these scaffolds by postpolyketide enzymes of the erythromycin pathway resulted in the generation of novel antibacterials with in vitro potency comparable to that of their natural counterparts.</jats:p>

<jats:p>Proteins of the Bcl-2 family are intracellular membrane-associated proteins that regulate programmed cell death (apoptosis) either positively or negatively by as yet unknown mechanisms. Bax, a pro-apoptotic member of the Bcl-2 family, was shown to form channels in lipid membranes. Bax triggered the release of liposome-encapsulated carboxyfluorescein at both neutral and acidic pH. At physiological pH, release could be blocked by Bcl-2. Bcl-2, in contrast, triggered carboxyfluorescein release at acidic pH only. In planar lipid bilayers, Bax formed pH- and voltage-dependent ion-conducting channels. Thus, the pro-apoptotic effects of Bax may be elicited through an intrinsic pore-forming activity that can be antagonized by Bcl-2.</jats:p>

<jats:p>Most cases of early-onset familial Alzheimer's disease (FAD) are caused by mutations in the genes encoding the presenilin 1 (PS1) and PS2 proteins, both of which undergo regulated endoproteolytic processing. During apoptosis, PS1 and PS2 were shown to be cleaved at sites distal to their normal cleavage sites by a caspase-3 family protease. In cells expressing PS2 containing the asparagine-141 FAD mutant, the ratio of alternative to normal PS2 cleavage fragments was increased relative to wild-type PS2-expressing cells, suggesting a potential role for apoptosis-associated cleavage of presenilins in the pathogenesis of Alzheimer's disease.</jats:p>

<jats:p>Global anterograde amnesia is described in three patients with brain injuries that occurred in one case at birth, in another by age 4, and in the third at age 9. Magnetic resonance techniques revealed bilateral hippocampal pathology in all three cases. Remarkably, despite their pronounced amnesia for the episodes of everyday life, all three patients attended mainstream schools and attained levels of speech and language competence, literacy, and factual knowledge that are within the low average to average range. The findings provide support for the view that the episodic and semantic components of cognitive memory are partly dissociable, with only the episodic component being fully dependent on the hippocampus.</jats:p>

<jats:p> The yeast cytoplasmically inherited genetic determinant [ <jats:italic>PSI</jats:italic> <jats:sup>+</jats:sup> ] is presumed to be a manifestation of the prion-like properties of the Sup35 protein (Sup35p). Here, cell-free conversion of Sup35p from [ <jats:italic>psi</jats:italic> <jats:sup>−</jats:sup> ] cells (Sup35p <jats:sup> <jats:italic>psi</jats:italic> </jats:sup> <jats:sup> <jats:italic>−</jats:italic> </jats:sup> ) to the prion-like [ <jats:italic>PSI</jats:italic> <jats:sup>+</jats:sup> ]-specific form (Sup35p <jats:sup> <jats:italic>PSI</jats:italic> </jats:sup> <jats:sup>+</jats:sup> ) was observed. The conversion reaction could be repeated for several consecutive cycles, thus modeling in vitro continuous [ <jats:italic>PSI</jats:italic> <jats:sup>+</jats:sup> ] propagation. Size fractionation of lysates of [ <jats:italic>PSI</jats:italic> <jats:sup>+</jats:sup> ] cells demonstrated that the converting activity was associated solely with Sup35p <jats:sup> <jats:italic>PSI</jats:italic> </jats:sup> <jats:sup>+</jats:sup> aggregates, which agrees with the nucleation model for [ <jats:italic>PSI</jats:italic> <jats:sup>+</jats:sup> ] propagation. Sup35p <jats:sup> <jats:italic>PSI</jats:italic> </jats:sup> <jats:sup>+</jats:sup> was purified and showed high conversion activity, thus confirming the prion hypothesis for Sup35p. </jats:p>

<jats:p> Cell divisions that produce progeny differing in their patterns of gene expression are key to the development of multicellular organisms. In the budding yeast <jats:italic>Saccharomyces cerevisiae</jats:italic> , mother cells but not daughter cells can switch mating type because they selectively express the <jats:italic>HO</jats:italic> endonuclease gene. This asymmetry is due to the preferential accumulation of an unstable transcriptional repressor protein, Ash1p, in daughter cell nuclei. Here it is shown that <jats:italic>ASH1</jats:italic> messenger RNA (mRNA) preferentially accumulates in daughter cells by a process that is dependent on actin and myosin. A cis-acting element in the 3′-untranslated region of <jats:italic>ASH1</jats:italic> mRNA is sufficient to localize a chimeric RNA to daughter cells. These results suggest that localization of mRNA may have been an early property of the eukaryotic lineage. </jats:p>