Physiological role of coronary constriction in the tortoise (Emys orbicularis L.)

Zusammenfassung Konstriktion der Herzkranzgefässe nach epicardialer Anwendung von Catecholaminen vermindert den O₂-Verbrauch des Schildkrötenherzens. Das Konstriktorsystem dieser Gefässe sichert eine rasche Anpassung des Herzstoffwechsels an den O₂-Mangel.     

Patterns of somatic mutation in human cancer genomes

Cancers arise owing to mutations in a subset of genes that confer growth advantage. The availability of the human genome sequence led us to propose that systematic resequencing of cancer genomes for mutations would lead to the discovery of many additional cancer genes. Here we report more than 1,000 somatic mutations found in 274 megabases (Mb) of DNA corresponding to the coding exons of 518 protein kinase genes in 210 diverse human cancers. There was substantial variation in the number and pattern of mutations in individual cancers reflecting different exposures, DNA repair defects and cellular origins. Most somatic mutations are likely to be 'passengers' that do not contribute to oncogenesis. However, there was evidence for 'driver' mutations contributing to the development of the cancers studied in approximately 120 genes. Systematic sequencing of cancer genomes therefore reveals the evolutionary diversity of cancers and implicates a larger repertoire of cancer genes than previously anticipated.     

A rather accurate method to determine Vitamine Deficiency from Urine

Zusammenfassung Die Untersuchung der Ausscheidung im Urin nach Vitaminbelastung ist ein zur Bestimmung der Hypovitaminose geeignetes Verfahren, wenn wir die Belastungsdose in Abständen von je 2 Stunden darreichen und die Einzelausscheidungswerte kurvenmäßig darstellen. Die Kurven ermöglichen eine Differenzierung zwischen Hypovitaminose und Ausscheidungsstörung und die Beurteilung des Grades der Hypovitaminose.     

Linderazulene,a new naturally occurring pigment from the gorgonianParamuricea chamaeleon

Summary The purple pigment of the gorgonianParamuricea chamaeleon has been isolated and identified as linderazulene (I).We thank Dr K. Takeda for linderazulene spectra, and NATO for a grant (to S.I. and R.H.T.) in support of this work.     

Uncovering the overlapping community structure of complex networks in nature and society

Many complex systems in nature and society can be described in terms of networks capturing the intricate web of connections among the units they are made of. A key question is how to interpret the global organization of such networks as the coexistence of their structural subunits (communities) associated with more highly interconnected parts. Identifying these a priori unknown building blocks (such as functionally related proteins, industrial sectors and groups of people) is crucial to the understanding of the structural and functional properties of networks. The existing deterministic methods used for large networks find separated communities, whereas most of the actual networks are made of highly overlapping cohesive groups of nodes. Here we introduce an approach to analysing the main statistical features of the interwoven sets of overlapping communities that makes a step towards uncovering the modular structure of complex systems. After defining a set of new characteristic quantities for the statistics of communities, we apply an efficient technique for exploring overlapping communities on a large scale. We find that overlaps are significant, and the distributions we introduce reveal universal features of networks. Our studies of collaboration, word-association and protein interaction graphs show that the web of communities has non-trivial correlations and specific scaling properties.     

Structure of the E. coli signal recognition particle bound to a translating ribosome

The prokaryotic signal recognition particle (SRP) targets membrane proteins into the inner membrane. It binds translating ribosomes and screens the emerging nascent chain for a hydrophobic signal sequence, such as the transmembrane helix of inner membrane proteins. If such a sequence emerges, the SRP binds tightly, allowing the SRP receptor to lock on. This assembly delivers the ribosome-nascent chain complex to the protein translocation machinery in the membrane. Using cryo-electron microscopy and single-particle reconstruction, we obtained a 16 A structure of the Escherichia coli SRP in complex with a translating E. coli ribosome containing a nascent chain with a transmembrane helix anchor. We also obtained structural information on the SRP bound to an empty E. coli ribosome. The latter might share characteristics with a scanning SRP complex, whereas the former represents the next step: the targeting complex ready for receptor binding. High-resolution structures of the bacterial ribosome and of the bacterial SRP components are available, and their fitting explains our electron microscopic density. The structures reveal the regions that are involved in complex formation, provide insight into the conformation of the SRP on the ribosome and indicate the conformational changes that accompany high-affinity SRP binding to ribosome nascent chain complexes upon recognition of the signal sequence.     

癌生长是寄主中的过寄生现象

报道了人乳腺癌细胞MCF7和正常细胞MCF10,MRC5混合培养实验,分析了实验结果．结果表明：在营养物充足条件下癌细胞和正常细胞系寄生共存关系,而在饥饿条件下癌细胞和正常细胞是过寄生-捕食者和食饵的关系．讨论了此结果的生物医学含义．