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Biomedical subjects

R G Milne

Publications and source records attributed to R G Milne.

At least 37 records · Page 2Linked to original sources
PubMed1987

Cryptic viruses in hop trefoil (Medicago lupulina) and their relationships to other cryptic viruses in legumes.

Three double-stranded (ds) RNA-containing viruses, named hop trefoil cryptic virus (HTCV) 1, 2 and 3, were found in apparently healthy seedlings of hop trefoil (Medicago lupulina). Only 1-2% of plants tested were virus-free. The particles occurred in the cytoplasm, nuclei and nucleoli of parenchyma cells. They were purified as a mixture (HTCV-M) with a mean yield of 50-100 micrograms/kg fresh tissue, and an antiserum was obtained. HTCV1 was serologically related to one component (ACV1) of a mixture of alfalfa cryptic viruses (ACV-M) present in alfalfa (M. sativa), and was separated by immunoprecipitation from HTCV-M; its particles, about 30 nm in diameter, contained two dsRNAs (Mr 1.27 X 10(6) and 1.15 X 10(6)) comigrating in PAGE with two RNAs of ACV-M. Particles of HTCV2, about 38 nm in diameter and with distinct morphological subunits, were serologically closely related to particles of similar morphology (RCCV2) present in a mixture of cryptic viruses (RCCV-M) from red clover (Trifolium pratense), and were distantly related to white clover cryptic virus 2, also of similar morphology. HTCV3 had particles 30 nm in diameter, morphologically similar to those of HTCV1, and reacted with an antiserum to vicia cryptic virus. HTCV2 and 3 could not be individually separated. The RNAs of HTCV-M, in addition to the two bands attributed to HTCV1, gave, upon electrophoresis, three bands of estimated Mr 1.34, 1.08 and 0.95, all X 10(6), and up to five minor bands of Mr ranging from 1.45 to 0.98, all X 10(6).

Fabaceae↗
PubMed1986

Relationships between the cryptic and temperate viruses of alfalfa, beet and white clover.

Small isometric virus particles containing double-stranded RNA have been independently reported in Europe and Japan from apparently healthy alfalfa (Medicago sativa), beet (Beta vulgaris), and white clover (Trifolium repens). They have been called cryptic viruses in Europe and temperate viruses in Japan. Serological comparison using immunoelectron microscopy, and polyacrylamide gel electrophoresis of the RNAs indicate that alfalfa cryptic and temperate viruses are the same, beet cryptic virus is probably a mixture of two different viruses, one of which is similar to or the same as beet temperate virus, and white clover temperate virus is a mixture of at least three different viruses, two of them indistinguishable from white clover cryptic viruses 1 and 2, respectively, and the third very likely the same as white clover cryptic virus 3.

Electrophoresis, Polyacrylamide Gel↗
PubMed1986

Serological relationships between the nucleocapsids of some planthopper-borne rhabdoviruses of cereals.

Leaves infected with barley yellow striate mosaic virus (BYSMV) from Italy, wheat chlorotic streak virus (WCSV) from France, northern cereal mosaic virus (NCMV) from Japan, maize sterile stunt virus (MSSV) from Australia or Shiraz maize rhabdovirus (SMRV) from Iran were homogenized in buffered 1% Nonidet P-40, releasing intact nucleocapsids. These (except SMRV) were trapped on electron microscope grids using appropriate antisera and tested by decoration with serial dilutions of antisera to BYSMV, NCMV, MSSV, Moroccan wheat rhabdovirus (MWRV), wheat rosette stunt virus (WRSV) from China, and maize mosaic virus (MMV) from Venezuela. The results suggest that BYSMV and NCMV, though related, are distinct viruses; MWRV and WCSV are strains of BYSMV; MSSV is intermediate between BYSMV and NCMV but may be considered a strain of BYSMV; WRSV is a strain of NCMV; and MMV and SMRV are unrelated to each other and to the other viruses tested. SMRV was morphologically quite different from BYSMV, NCMV, WCSV and MSSV, all of which had the same morphology.

Animals↗
PubMed1985

Morphology and nucleic acid of rice gall dwarf virus.

In negative stain preparations, the particles of rice gall dwarf virus (RGDV) had the form of angular icosahedra, approximately 65 nm in diameter, and resembled Phytoreovirus particles. The genomic double-stranded RNA of RGDV was fractionated by PAGE into 12 segments similar to those of the RNAs of the phytoreoviruses, wound tumor virus and rice dwarf virus, but of different mobilities. The RNAs were distinct from those of other plant reoviruses. RGDV therefore is confirmed as a new Phytoreovirus.

Molecular Weight↗
PubMed1985

Alternatives to the species concept for virus taxonomy.

The species concept seems to be inescapably based on the occurrence, in a population, of regular genetic interchange which leads to the formation of common gene pools and on the presence of barriers to interchange which distinguish one gene pool from another. Present knowledge indicates that some types of viruses (e.g. Orthomyxoviridae, Reoviridae) may exchange genes and have a gene-pool population structure; application of the species concept here is legitimate and likely to be feasible in practice. However, it seems that other types of viruses (e.g., tobamoviruses, tombusviruses) do not indulge in regular gene exchange and that common gene pools, distinct from each other, do not occur. Rather, there is clonal multiplication, accumulation of variants, and a fanwise radiation of types with little or no genetic exchange across the rays of the fan. Here, the species concept cannot usefully be applied at either the theoretical or the practical level. If viruses within some major groups are not amenable to being classified and named as species, it follows that attempts to apply the species concept to all viruses should be abandoned. An alternative system that can embrace all cases is already used by plant virologists and merits careful examination by others. Adoption of a 'nonspecies' general approach need not exclude the proposition that in some instances virus species do exist and can be identified and named, as special subsets of the general case. If we cease to aim for the universal pigeonholing of viruses into genera and species, binomial latinized names lose their chief justification.(ABSTRACT TRUNCATED AT 250 WORDS)

Genes, Viral↗
PubMed1984

The species problem in plant virology.

The systems currently used to classify and name viruses are discussed. It is concluded that, while the family-genus-species system is widely used for many viruses, the virus group-virus system used for plant viruses has a sounder theoretical basis and is easier to use. Its universal adoption should be considered. For plant viruses, the English vernacular name and the group name could form the basis of a binomial nomenclature.

Methods↗
PubMed1982

Effect of pH and other conditions on immunosorbent electron microscopy of several plant viruses.

The efficiency of trapping, using immunosorbent electron microscopy, of particles of cucumber mosaic virus, lily symptomless virus, potato virus Y, and carnation mottle virus, depended markedly on the pH of the virus extract. Varying the pH of the serum had a smaller, though still significant effect. with potato virus Y, the optimal pH of the virus extract varied with the host plant. It appears that for each virus and host a specific testing procedure is required to find the optimal trapping conditions.

Hydrogen-Ion Concentration↗
PubMed1982

Suggested terminology for virus/antibody interactions observed by electron microscopy.

Six terms are recommended to describe the techniques applied and the effects observed when antibody/virus particle interactions are examined in the electron microscope. These are: immunoelectron microscopy, immunosorbent electron microscopy, antiserum- (or antibody-)coated grids, trapping, clumping and antibody coating. These recommendations are intended to assist authors and editors alike, by decreasing the confusion resulting from the use of a wide variety of alternative terms.

Antibodies, Viral↗
PubMed1981

Enhancement of the immunogenicity of the maize rough dwarf virus outer shell with the cross-linking reagent dithiobis(succinimidyl)propionate.

Injection into rabbits of native or glutaraldehyde (GA)-treated intact particles of the fijivirus maize rough dwarf virus (MRDV) failed to yield antibodies to the outer shell of the virus. After fixation of the particles with the cross-linking reagent dithiobis(succinimidyl)propionate (DSP), antisera were obtained reacting with the outer shell of MRDV (both DSP-fixed and unfixed) to a titre of 1/1024 in immunoelectron microscopic decoration tests, but giving no reaction with another fijivirus, oat sterile dwarf virus, whose subviral particles are known to be unrelated to those of MRDV. Further fixation of the DSP-fixed particles with GA did not appear to enhance immunogenicity. Stabilization with DSP could have further application with viruses the instability of which renders them poor immunogens.

Animals↗
PubMed1980

Electrophoretic fractionation of the double-stranded RNA genome of rice ragged stunt virus.

The genomic nucleic acid of rice ragged stunt virus (RRSV) was purified directly from enations of RRSV-infected plants. Its resistance to DNase and solubility in 2 M LiCl, plus its sharp thermal denaturation transition, with am melting temperature of about 83 degrees C in 0.15 m NaCl - 0.015 M Na citrate buffer, pH 7.0, showed the nucleic acid to be double-stranded RNA. On PAGE in 5% gels the RNA separated into 8 segments which occurred in equimolar amounts and had a total molecular weight of 11.63 x 10(6). RRSV resembles the fijiviruses, but its genome differs somewhat from those of other group members.

Molecular Weight↗
PubMed1980

Does rice ragged stunt virus lack the typical double shell of the Reoviridae?

In rice ragged stunt virus preparations negatively stained with uranyl acetate, particles corresponding to the B-spiked subviral particles (SPVs) but not the double-shelled virions of fijiviruses were seen. The B spikes were broader at the base than those of fijiviruses, but otherwise the particles were similar in size and shape to fijivirus SVPs. In thin sections of infected plants, large numbers of virus-like particles were seen; most resembled the SVPs of fijiviruses but some appeared intermediate between these and complete fijivirus particles. It seems likely that rice ragged stunt virus does not produce a regular outer shell as do the fijiviruses, although the broad-based B spikes may in some profiles have given the appearance of a continuous shell.

Oryza↗