Myosin motor function: the ins and outs of actin-based membrane protrusions

Cells build plasma membrane protrusions supported by parallel bundles of F-actin to enable a wide variety of biological functions, ranging from motility to host defense. Filopodia, microvilli and stereocilia are three such protrusions that have been the focus of intense biological and biophysical investigation in recent years. While it is evident that actin dynamics play a significant role in the formation of these organelles, members of the myosin superfamily have also been implicated as key players in the maintenance of protrusion architecture and function. Based on a simple analysis of the physical forces that control protrusion formation and morphology, as well as our review of available data, we propose that myosins play two general roles within these structures: (1) as cargo transporters to move critical regulatory components toward distal tips and (2) as mediators of membrane-cytoskeleton adhesion.     

Segregation of bivalents in meiosis induced by chemicals

Zusammenfassung Urethan, Senfgas und Ribose-Nukleat-Natrium scheinen alle die Meiose der Heuschrecke auf eine interessante Art und Weise zu beeinflussen. In Anaphase I verursachen sie eine Abspaltung von zweiwertigen Einheiten, die, anstatt sich in einwertige Einheiten zu teilen, als Ganze nach den Polen wandern.     

Chromosomal translocations among the healthy human population: implications in oncogenesis

Chromosomal translocations are characteristic features of many cancers, especially lymphoma and leukemia. However, recent reports suggest that many chromosomal translocations can be found in healthy individuals, although the significance of this observation is still not clear. In this review, we summarize recent studies on chromosomal translocations in healthy individuals carried out in different geographical areas of the world and discuss the relevance of the observation with respect to oncogenesis.     

Identification of functional genes during Fas-mediated apoptosis using a randomly fragmented cDNA library

We describe a general strategy for the identification of functional genes that, when downregulated, result in a selectable phenotype. This strategy is based on expression selection of cDNA fragments that counteract their cognate genes. A cDNA library containing random fragments expressed in human HepG2, A375 and CLS-354 cells was used to identify functional genes whose inhibition conferred resistance to Fas-induced apoptosis. Thirty-five clones were isolated, 28 of which were derived from unknown genes, that tagged 19 individual genes and 7 of which referred to known genes that tagged the apoptosis-related protein (APR)-1, -2 and indoleamine-pyrrole 2,3,-dioxygenase (IDO). The ability of APR-1-, -2- and IDO-derived antisense RNAs to induce resistance to Fas in HepG2, A375 and CLS-354 cells suggested that APR-1, -2 and IDO genes are involved in the machinery of Fas-mediated apoptosis. Our gene discovery strategy provides a generally applicable procedure to identify functional genes that interfere with apoptosis, and may therefore be clinically relevant for tumor therapy.Received 28 April 2005; received after revision 20 June 2005; accepted 5 July 2005