Reaction discovery enabled by DNA-templated synthesis and in vitro selection

Current approaches to reaction discovery focus on one particular transformation. Typically, researchers choose substrates based on their predicted ability to serve as precursors for the target structure, then evaluate reaction conditions for their ability to effect product formation. This approach is ideal for addressing specific reactivity problems, but its focused nature might leave many areas of chemical reactivity unexplored. Here we report a reaction discovery approach that uses DNA-templated organic synthesis and in vitro selection to simultaneously evaluate many combinations of different substrates for bond-forming reactions in a single solution. Watson-Crick base pairing controls the effective molarities of substrates tethered to DNA strands; bond-forming substrate combinations are then revealed using in vitro selection for bond formation, PCR amplification and DNA microarray analysis. Using this approach, we discovered an efficient and mild carbon-carbon bond-forming reaction that generates an enone from an alkyne and alkene using an inorganic palladium catalyst. Although this approach is restricted to conditions and catalysts that are at least partially compatible with DNA, we expect that its versatility and efficiency will enable the discovery of additional reactions between a wide range of substrates.     

C. elegans ORFeome version 1.1: experimental verification of the genome annotation and resource for proteome-scale protein expression

To verify the genome annotation and to create a resource to functionally characterize the proteome, we attempted to Gateway-clone all predicted protein-encoding open reading frames (ORFs), or the 'ORFeome,' of Caenorhabditis elegans. We successfully cloned approximately 12,000 ORFs (ORFeome 1.1), of which roughly 4,000 correspond to genes that are untouched by any cDNA or expressed-sequence tag (EST). More than 50% of predicted genes needed corrections in their intron-exon structures. Notably, approximately 11,000 C. elegans proteins can now be expressed under many conditions and characterized using various high-throughput strategies, including large-scale interactome mapping. We suggest that similar ORFeome projects will be valuable for other organisms, including humans.     

Quantal calcium release by purified reconstituted inositol 1,4,5-trisphosphate receptors.

Release of intracellular Ca2+ by inositol 1,4,5-trisphosphate (InsP3) occurs through specific receptor proteins which are ligand-activated Ca2+ channels. Changes in intracellular Ca2+ regulate many cellular functions. This Ca2+ release is a discontinuous quantal process in which successive increments of InsP3 transiently release precise amounts of Ca2+ (refs 4-6). Possible explanations of quantal Ca2+ release have included rapid degradation of InsP3, reciprocity of Ca2+ release and sequestration, desensitization of InsP3 receptors, or actions of InsP3 on discrete compartments of Ca2+ with variable sensitivity to InsP3 (ref. 4). We successfully reconstituted InsP3-induced Ca2+ flux in vesicles containing only purified InsP3 receptor protein. The reconstituted vesicles retain the regulatory features of the InsP3 receptor, including phosphorylation sites and modulation of Ca2+ release by adenine nucleotides. Using these reconstituted vesicles, we show here that quantal flux of Ca2+ elicited by InsP3 is a fundamental property of its receptor.     

Catecholamines in adult iron deficiency patients

Summary Patients with iron deficiency whether uncomplicated or associated with other types of anemias, had plasma catecholamine levels which were significantly increased above normal controls. Patients with a variety of other anemias had no significant increase in catecholamine levels. Plasma catecholamine levels in uncomplicated iron deficient patients approached normal values as early as 3 h following oral FeSO₄.Acknowledgment. Funded in part by an NIH grant No. R01 HL 19933.     

Chromosomes of the rock hyrax,Procavia capensis (Pallas), 1767

Zusammenfassung Es werden die Chromosomen eines weiblichen und zwei männlicher Felshyraxarten,Procavia capensis (Pallas), 1767 (Hyracoidea: Mammalia) beschrieben. Ihre diploide Chromosomenzahl ist 2n=54. Mit Ausnahme derX-Chromosomen sind keine eindeutigen Chromosomenkomplement-übereinstimmungen mit denjenigen von Elefanten sichtbar. Hingegen sind die allgemeinen Eigentümlichkeiten der Karyotypen und die Anzahl der Hauptarme der Chromosomen ähnlich und stimmen überdies mit taxonomischen Verbindungen, die zwischen den Hyracoidea und den Proboscidea angenommen werden, überein.     

The interaction of hypothalamic self-stimulation and temperature regulation

Résumé Placés dans un environnement froid, les rats qui avaient des électrodes implantés dans l'hypothalamus postérieur, préféraient la stimulation intracrannienne à un réchauffement de l'environnement; de ce fait, ils devenaient hypothermiques. Les rats qui avaient des électrodes implantés dans l'hypothalamus antérieur actionnaient alternativement les leviers de chauffage et ceux du courant électrique; ils évitaient ainsi de devenir hypothermiques.