Tumour biology: senescence in premalignant tumours

Oncogene-induced senescence is a cellular response that may be crucial for protection against cancer development, but its investigation has so far been restricted to cultured cells that have been manipulated to overexpress an oncogene. Here we analyse tumours initiated by an endogenous oncogene, ras, and show that senescent cells exist in premalignant tumours but not in malignant ones. Senescence is therefore a defining feature of premalignant tumours that could prove valuable in the diagnosis and prognosis of cancer.     

Functional cartography of complex metabolic networks

High-throughput techniques are leading to an explosive growth in the size of biological databases and creating the opportunity to revolutionize our understanding of life and disease. Interpretation of these data remains, however, a major scientific challenge. Here, we propose a methodology that enables us to extract and display information contained in complex networks. Specifically, we demonstrate that we can find functional modules in complex networks, and classify nodes into universal roles according to their pattern of intra- and inter-module connections. The method thus yields a 'cartographic representation' of complex networks. Metabolic networks are among the most challenging biological networks and, arguably, the ones with most potential for immediate applicability. We use our method to analyse the metabolic networks of twelve organisms from three different superkingdoms. We find that, typically, 80% of the nodes are only connected to other nodes within their respective modules, and that nodes with different roles are affected by different evolutionary constraints and pressures. Remarkably, we find that metabolites that participate in only a few reactions but that connect different modules are more conserved than hubs whose links are mostly within a single module.     

Effect of ethidium bromide onDrosophila melanogaster andDrosophila simulans

Summary Ethidium bromide was fed toD. melanogaster andD. simulans males in order to test its toxic capacity and potency for the induction of dominant lethals. Our results show that ethidium bromide has a high toxicity and likewise produces dominant lethals to a significant extent in both species, but more effectively inD. melanogaster.     

Methylhydrazine derivatives,a new class of cytotoxic agents

Zusammenfassung Ausgehend von der Beobachtung, dass 1-Methyl-2-benzyl-hydrazin tumorhemmend wirkt, wurden durch systematische Variationen die für diese Wirkung essentiellen Strukturmerkmale festgelegt. Aus einer grösseren Anzahl von Verbindungen wurden 1-Methyl-2-p-(isopropylcarbamoyl)benzyl-hydrazin-hydrochlorid und 1-Methyl-2-p-allophanoylbenzyl-hydrazin-hydrobromid für ausgedehnte experimentelle und klinische Versuche ausgewählt.     

Cycloheximide-induced ultrastructural changes in the adrenal cortex of the rat

Zusammenfassung Cycloheximid als allgemeiner Inhibitor der Proteinsynthese verursacht submikroskopische Veränderungen in der Nebennierenrinde der Ratte. Kompaktes Material und konzentrische Membranstrukturen im Zytoplasma von Zellen der Zona fasciculata finden sich um Mitochondrien und Lipidtropfen.