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The behaviour of some isometric plant viruses heated in vitro as determined by particle stabilizing forces
No full textAbsorbance-temperature profiles, at 400 nm, of plant viruses with one or more kinds of isometric particle, were determined. 2 temperatures were determined, Td (the temperature at which E400 begins to increase) and Tf (the temperature at the inflexion point of the curve). The behaviour on heating at these temperatures was of two main types. Heating in vitro appears to be a useful means of making a gross subdivision of isometric plant viruses into 2 groups typified by cucumber mosaic virus and turnip yellow mosaic virus, respectively, in agreement with Kaper's suggestion
Production of RNA and artificial top component from parsley carrot leaf virus heated in vitro
No full textThe extinction temperature profile of parsley carrot leaf virus in 0.02 M (Na K) phosphate buffer, pH 7.2, containing 0.1 M NaCl, was determined. At the Td (dissociation temperature = 65°C), the point at which E260 begins to increase, the virus particles apparently dissociate to form RNA and empty protein shells (top component). At the Tf (temperature at the inflexion point of the curve = 70°C), corresponding to half the maximum increase in E260, the protein denatures and precipitates. Temperatures below Td have little effect on the virus, whereas temperatures higher than Tf also degrade the RNA. The results of the present work seem to suggest that the increase in E260 of PCLV preparations upon heating is mostly attributable to turbidity caused by coat protein denaturation rather than to effects on RNA
Properties of grapevine fanleaf virus
No full textPurified preparations of grapevine fanleaf virus consist of three serologically indistinguishable centrifugal components, T, M and B, with sedimentation coefficients of 50, 86 and 120 S respectively, and containing 0, 30 and 42% RNA. At equilibrium in CsCl gradients, T, M and B components precipitate. Their buoyant densities are 1.31, 1.41 and 1.49 g/ml, respectively. Infectivity is associated mostly with B component. RNA is single stranded and occurs as two species with mol. wt. of 1.4x106 (RNA 2) and 2.4x106 (RNA I). M particles contain only RNA 2 whereas B particles contain both species. RNA 2 is non infective, some infectivity is associated with preparations of RNA I, and infectivity can increase tenfold when RNA I and RNA 2 are mixed. The capsid contains a single protein species with mol. wt. of about 54000. Comparable data for arabis mosaic and raspberry mosaic viruses are similar. The present cryptogram of grapevine fanleaf virus is R/I:2.4/42+1.4/30:S/S:S/Ne
Il virus dell'accartocciamento fogliare del ciliegio nel noce. I. Identificazione e caratterizzazione
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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