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R I Francki

Publications and source records attributed to R I Francki.

At least 37 records · Page 2Linked to original sources
PubMed1984

Differences in the morphology of isometric particles of some plant viruses stained with uranyl acetate as an aid to their identification.

Purified preparations of viruses with small polyhedral particles representing ten distinct taxonomic groups were examined by electron microscopy after negative staining with uranyl acetate. Comparisons of the relative size, shape and surface appearance of the particles established that some of them could be distinguished at the group level. However, the particles of viruses belonging to the bromovirus group could not be distinguished from those of the cucumovirus group, the nepovirus group from those of the comovirus group, and the tombusvirus group from those of the dianthovirus group. Furthermore, the particles of viruses of the sobemovirus, lutoevirus and tobacco necrosis virus groups were indistinguishable. The usefulness of the observed differences in the particle morphologies to virus identification is discussed.

Microscopy, Electron↗
PubMed1981

Immunochemical detection of ds-RNA in healthy and virus-infected plants and specific detection of viral ds-RNA by hybridization to labelled complementary DNA.

Double-stranded (ds) RNA was detected in nucleic acid preparations from virus-free leaf tissues of several plant species by radial double-diffusion tests with antiserum raised against polyinosinic : polycytidylic acid [poly(I) : poly(C)]. No significant differences in the concentrations of ds-RNA were detected by such tests in virus-free French bean leaves and those infected with tobacco mosaic virus or tobacco ringspot virus. However, virus-specific ds-RNAs as well as genomic RNAs of both viruses were readily detected and estimated quantitatively by hybridization to 3H-labelled complementary DNA probes. It is concluded that it is not feasible to screen plant material infected with single-stranded RNA viruses by immunochemical tests for virus-associated ds-RNAs.

Fabaceae↗
PubMed1981

Detection and identification of FIJI disease virus in infected sugarcane by immunodiffusion, immuno-osmophoretic and enzyme-linked immunosorbent assays.

Radial double-immunodiffusion, immuno-osmophoretic and enzyme-linked immunosorbent assay (ELISA) methods have been compared for the detection of Fiji disease virus (FDV) in infected sugarcane tissue extracts using an antiserum containing antibodies specific to FDV proteins and ds-RNA. ELISA was the most sensitive of these tests and detected only FDV-specific proteins byt not ds-RNA. Immuno-osmophoretic tests were less sensitive than ELISA but detected both the protein and ds-RNA antigens as distinct precipitin lines. Immunodiffusion tests were much less sensitive for the detection of FDV antigens than either ELISA or immuno-osmophoretic tests. FDV antigens were detected in leaves of virus-infected sugarcane, but only in tissues of the galls which develop in response to infection. Even ELISA failed to detect any antigens in normal tissues adjacent to galls. It is concluded that for the identification to FDV in infected surgarcane, it is necessary to observe galls which can then be tested for the presence of FDV antigens. Immuno-osmophoresis appears to be a satisfactory method for such tests.

Antigens, Viral↗
PubMed1979

Rhabdoviridae. Report of the Rhabdovirus Study Group, International Committee on Taxonomy of Viruses.

The family Rhabdoviridae comprises approximately 75 viruses infecting vertebrates, invertebrates and plants. The main characteristics of the member viruses are: (i) the viruses infecting vertebrates and invertebrates are bullet-shaped and the viruses infecting plants are usually bacilliform; (ii) the viruses have particle lengths varying from 130 to 380 nm and widths varying from 60 to 95 nm; (iii) the viruses possess unit-membrane envelopes from which protrude spikes 5 to 10 nm long; (iv) the viruses have precisely coiled helical nuecleocapsids with a diameter of approx. 50 nm; (v) most of the viruses which have been studied contain 5 proteins; the prototype, vesicular stomatitis virus, contains proteins designated L (large), G (glycoprotein), N (nucleoprotein), NS (nonstructural) and M (matrix); N or NS is phosphorylated in most members which have been studied; (vi) the viruses contain single-stranded RNA which is transcribed into several messenger RNA species with sizes corresponding to the structural proteins; (vii) the nucleocapsid contains the RNA-dependent RNA polymerase and is infectious; and (viii) many of the viruses produce morphologically distinct defective-interfering (T) particles.

RNA, Viral↗