Enhanced cytotoxicity without internuclear spread of adenovirus upon cell fusion by measles virus glycoproteins

The efficiency of viruses in cancer therapy is enhanced by proteins that mediate the fusion of infected cells with their neighbors. It was reported that replication-competent adenovirus particles can spread between nuclei within fusion-generated syncytia. To assess this conjecture, we generated fusogenic adenoviruses that express a balanced ratio of the F and H glycoproteins of measles virus. The viruses displayed enhanced cytotoxicity but largely unchanged replication efficiencies compared to a nonfusogenic virus. Most notably, the virus genomes did not spread through fusion-generated multinuclear cells. Hence, adenovirus replication in syncytia remains largely restricted to initially transduced nuclei.     

A multi‐protein complex controls cAMP signalling and filamentation in the fungal pathogen Candida albicans

Candida albicans is an opportunistic fungal pathogen of humans. The ability of the fungus to grow as both yeast and filamentous forms is essential for its pathogenicity. Morphogenesis of C. albicans is largely regulated through the secondary messenger cAMP, produced by the soluble adenylyl cyclase, Cyr1p. Recent evidence suggests that Cyr1p can be directly stimulated by environmental cues to increase cytoplasmic cAMP levels and thus promote hyphal development. In this issue of Molecular Microbiology, Zou et al. demonstrate that, in response to some environmental cues, Cyr1p functions as part of a tripartite complex additionally involving Cap1p and G‐actin. All three proteins in the complex are required to raise cytosolic cAMP levels after stimulation with serum and bacterial peptidoglycan. The formation of such a complex highlights the importance of precise regulation of Cyr1p activity in response to host environmental cues.     

Cell-substratum and cell-cell interactions promote testicular peritubular myoid cell histotypic expression in vitro

Peritubular cells, prepared from seminiferous tubules from testes of 20-day-old-rats, were seeded onto different substrata and cultured under varying conditions. When plated onto polystyrene or glass surfaces, peritubular cells assumed a typical fibroblast-like cell shape and cell association pattern, together with a fibroblast-like migration behavior. They maintained high rates of proliferation even after achieving confluency. In contrast, when peritubular cells were plated onto a seminiferous tubule biomatrix (ST-biomatrix) surface, they spread to form a continuous cell layer having a myoepithelioid histotype similar to that of peritubular myoid cells in the intact seminiferous tubule. The characteristics of the myoepithelioid histotype described include a squamous, polyhedral cell shape; a cobblestone-like cell association pattern, with closely apposing or slightly overlapping cell borders, and a very low mitotic index. When peritubular cells were plated onto laminin, collagen, fibronectin, heparin, or a liver biomatrix, a fibroblast-like pattern resulted, indicating that ECM components listed and liver biomatrix are unable to substitute for ST-biomatrix in maintaining normal myoepithelioid characteristics in vitro. In cocultures of Sertoli cells plated on top of peritubular cells, the peritubular cells directly in contact with Sertoli cell aggregates developed a myoepithelioid histotype, whereas peritubular cells in regions not in direct contact had a fibroblast-like histotype. The data are discussed in relation to the possible role of cell-cell interactions, and cell-substratum interactions, in the acquisition and stabilization of the histotype of peritubular cells in the seminiferous tubule during development.     

Prevalence of Thelohania solenopsae infected Solenopsis invicta newly mated queens within areas of differing social form distributions

Newly mated queens (NMQs) originating from monogyne red imported fire ant (Solenopsis invicta) colonies and following a mating flight, initiate new colonies by sealing themselves in a nuptial chamber and relying solely on their own fat and crop reserves, as well as no longer needed wing muscles to rear their first workers (claustral colony foundation). This method of colony-founding is rarely successful for polygyne-derived NMQs, whose low weight critically limits the number of first workers they are able to produce. However, this observation may be confounded by the parasitic microsporidium, Thelohania solenopsae, thus far found to persist only in association with polygyne colonies. Infections of this microsporidium reduce the weight of female alates and may explain why polygyne NMQs are unlikely to successfully found colonies claustrally. NMQs collected following mating flights in Gainesville and Ocala, Florida were sorted by weight, checked for insemination and T. solenopsae infection. Insemination levels were greater than 90% for all weight classes at both collection sites and were not related to infection. Infection levels were lower in Gainesville than Ocala, averaging 1.67% and 14.14%, respectively. Polygyne-derived NMQs collected in Ocala, defined here as weighing 12mg (social form correctly assigned in 85% of samples examined by PCR), had the highest infection levels, 25.37% (17/67) in 2003 and 21.43% (6/28) in 2004. We conclude that infection by T. solenopsae cannot be completely responsible for the inability of polygyne NMQs to claustrally establish colonies.     

Die Auslese tetraploider Formen von Lupinus angustifolius nach Röntgenbestrahlung und Ergebnisse der vergleichenden Untersuchungen mit den diploiden Ausgangsformen

Zusammenfassung Nach Röntgenbestrahlung wurden aus verschiedenen X₂-Generationen von Lupinus angustifolius mehrere breitblättrige Mutanten ausgelesen. Die stark vom Normalen abweichende Pollenform ließ vermuten, daß eine Erhöhung der Valenzstufe vorlag. Durch vergleichende Untersuchungen mit den Ausgangsformen und durch Chromosomenzählungen wurden sieben Mutantenstämme als Tetraploide bestätigt. Wuchshöhenmessungen und Auszählungen der Ansatzverhältnisse gestatten Schlußfolgerungen über die zu erwartende Leistungsfähigkeit der Tetraploiden.

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Selection of tetraploid forms of Lupinus angustifolius after X-radiation and results of comparative studies with the diploid parental strains

Summary After X-radiation some mutants with broader leaves were selected from different X₂-generations of Lupinus angustifolius. The pollen grains deviated much from their normal form and it was supposed that they were tetraploids. Comparative studies with the parental forms and counting of chromosomes proved seven mutant strains to be tetraploid. Measurements of plant height and counts of seed setting permit drawing a conclusion on the yield capacity of the tetraploids.