Biological and biochemical properties of an isolate of cherry rasp leaf virus from red raspberry

A mechanically transmissible virus obtained from symptomless plants of a red raspberry selection imported into Scotland from Quebec, Canada was indistinguishable serologically from a cherry isolate of cherry rasp leaf virus (CRLV). The raspberry isolate, CRLV-R, was graft transmitted to several virus indicator species and cultivars of Rubus without inducing noticeable symptoms. In Chenopodium quinoa sap, CRLV-R lost infectivity after dilution to 10^-5 or heating for 10 min at 60°C but was infective after 16 days (the longest period tested) at 18°, 4° or - 15°C. The virus particles are isometric, c. 28 nm in diameter, and were purified with difficulty from infected C. murale and C. quinoa plants. The particles comprise two nucleoprotein components with sedimentation coefficients of 89 and 115 S and are prone to aggregate during purification. When centrifuged to equilibrium in CS₂SO₄ solution, purified virus preparations formed two major components with p= 1·28 and 1·36 g/cm³. Virus particles contained two RNA species which, when denatured in glyoxal and electrophoresed in agarose gels, had estimated mol. wt of 2·56 × 10⁶ (RNA-1) and 1·26 × 10⁶ (RNA–2). Infectivity of CRLV-R RNA was abolished by treatment with proteinase K, suggesting that the RNA is linked to protein necessary for infectivity; RNA molecules contained polyadenylate. In reticulocyte lysates, CRLV-R RNA stimulated the incorporation of ³H-leucine, mainly into two polypeptides of estimated mol. wt 200 000 and 102 000. When electrophoresed in polyacrylamide gels, protein obtained from CRLV-R particles purified by centrifugation to equilibrium in Cs₂SO₄ separated into three bands with estimated mol. wt 26 000 , 23 000 and 21 000.     

Properties of broad bean yellow band virus, a possible new tobravirus

A virus was transmitted from broad bean plants in Apulia (Southern Italy) with leaves showing yellow rings, line patterns or yellow vein banding and malformations and necrosis of pods. Symptoms in some, but not all, test plants were similar to those induced by tobraviruses. Purified virus preparations contained two classes of rod-shaped particles containing c. 5% nucleic acid with sedimentation coefficients of 186S and 276S. After centrifugation to equilibrium in CsCl gradients, two components were resolved, with buoyant densities of 1·298 and 1·316 g/cm³. Unfractionated virus preparations contained two species of single-stranded RNA with mol. wts of c. 1·06 × 10⁶ and 2·48 × 10⁶ and one species of coat protein with mol. wt of c. 21 300. The modal lengths of the two classes of particles, both in plant sap and in purified preparations, were 77 nm (S particles) and 202 nm (L particles). L particles accumulated in infected cells in paracrystalline aggregates, whereas S particles were randomly distributed in the cytoplasm of cells. The virus was serologically unrelated to two isolates of tobacco rattle virus and two isolates of pea early-browning virus. The virus, named broad bean yellow band, is considered a distinct tobravirus.     

Properties of a tomato isolate of Pelargonium zonate spot virus

A manually transmissible virus isolated from tomato plants with stunting, unfruitfulness, malformation and yellow rings and line patterns of the leaves was indistinguishable from Pelargonium zonate spot virus (PZSV) in biological, physico-chemical and serological properties. The tomato isolate (PZSV-T) of PZSV was seed transmitted in Nicotiana glutinosa and was detected in the pollen of this host. In sap of N. glutinosa PZSV-T lost infectivity after diluting 10^-1 to 10^-2, heating for 10 min at 35 to 40 °C or storage at 25 °C for 7 h. Virus particles were quasi-spherical with a diameter ranging between 25 and 35 nm with a modal value of 29 nm. Particles sedimented as three components (TV, MV and BV) with sedimentation coefficients of 80S (TV), 90S (MV) and 118S (BV); component BV is probably an aggregate of TV. Particles were unstable in CsCl and CS₂SO₄ but formaldehyde-stabilised particles banded at a common density of 1–268 g/cm³ in Cs₂SO₄. Particles contained a single protein species with mol. wt of c. 23000 and c. 18% single stranded RNA present as two species with mol. wts of c. 1.25 × 10⁶ (RNA-1) and 0.95 × 10⁶ (RNA-2). Mixtures of RNA-1 + RNA-2 were infectious and this infectivity was not enhanced by the addition of coat protein. Virus particles had a Tf (mid point of extinction when heated) of 63 °C and were readily dissociated by 0.1% SDS. PZSV-T was serologically unrelated to alfalfa mosaic and to 32 isometric viruses including five ilarviruses. Some properties of PZSV resemble those of ilarviruses but others are sufficiently different to suggest that it may not be a member of this virus group.     

Host range and some properties of potato mop-top virus

Potato mop-top virus (PMTV) was transmitted by inoculation of sap to twenty-six species in the Solanaceae or Chenopodiaceae and to Tetragonia expansa; species in eleven other plant families were not infected. The virus was cultured in inoculated leaves of Nicotiana tabacum cv. Xanthi-nc or in N. debneyi. Diagnostic local lesions were produced in Chenopodium amaranticolor. In winter, ten solanaceous species were slowly invaded systemically but the first leaves infected were those immediately above inoculated leaves. When transmitted to Arran Pilot potato by the vector Spongospora subterranea, PMTV induced all the main types of shoot and tuber symptoms found in naturally infected plants. Isolates of PMTV from different sources differed considerably in virulence. PMTV-containing tobacco sap lost infectivity when heated for 10 min at 80 °C, diluted to 10^-4, or stored at 20 °C for 14 weeks. Infectivity was partially stabilized by 0·02% sodium azide. When sap was centrifuged for 10 min at 8000 g, infectivity was mainly in the sediment. Infective sap contained straight rod-shaped particles about 20 nm wide, with lengths up to 900 nm and crossbands at intervals of 2·5 nm. Many of the particles were aggregated side-to-side, and the ends of most seemed damaged. The slight infectivity of phenol-treated leaf extracts was abolished by pancreatic ribonuclease. The present cryptogram of PMTV is R/*:*/*:E/E:S/Fu.     

Purification and properties of elm mottle virus

A virus obtained commonly from Wych elm (Ulmus glabra) in Scotland showing ringspot and line-pattern leaf symptoms was serologically related to elm mottle virus (EMotV) from East Germany. The virus was seed-borne in elm and was transmitted by inoculation of sap to elm and twenty-one herbaceous species. No symptoms developed in infected elm seedlings kept in the glasshouse. In Chenopodium quinoa sap, EMotV lost infectivity after diluting to 10^-4, after 10 min at 60 ^oC, or 9 days at 18 ^oC. When purified from C. quinoa sap by clarification with n-butanol (8-5 %, v/v) and differential centrifugation, preparations contained quasi-spherical particles mostly 26–29 nm m diameter (mean = 28 nm) which sedimented as three nucleo-protein components with sedimentation coefficients (s^o₂o, w) of 83, 88 and 1 or S; most infectivity was associated with the 101 S component but infectivity was enhanced by adding the slower sedimenting components. When centrifuged to equilibrium in caesium chloride solution at 4 ^oC, purified virus preparations were largely degraded and contained many non-infective particles c. 15–22 nm in diameter, and intact infective particles which formed a band of density c. 1–34 g/cm³. Polyacrylamide gel electrophoresis indicated that EMotV contained a single major protein species of estimated mol. wt. 25000 and five RNA species of estimated mol. wt. 1–30, 1.15, 0–82, 0 39 and 0–30 times10⁶. Gel electrophoresis of RNA extracted from the separated components indicated that the 101 S component contained 1–30 x io⁶ mol. wt. RNA and the 83 S component 0–82 times 10⁶ mol. wt. RNA. In these and other properties, EMotV resembles the serologically unrelated tobacco streak virus.     

Garlic yellow streak virus, a potyvirus infecting garlic in New Zealand

In New Zealand, all garlic (Allium sativum) plants tested were infected by a virus with flexuous filamentous particles 700–800 nm long. This virus, called garlic yellow streak virus (GYSV), infected only two of 12 species tested and was transmitted to garlic by the aphid Myzus persicae in a non-persistent manner. In garlic sap, GYSV was infective at a dilution of 10^-4 but not 10^-3, after heating for 10 min at 60°C but not 65°C, and after 2 days but not 3 days at 25°C. The yield of virus, purified from naturally infected garlic, was 3–4 mg/kg fresh leaf. Preparations had A₂₆₀/A₂₈₀= 1.28 and A_man/A_min= 1.08. The virus particles had a sedimentation coefficient of 149S and a buoyant density in CsCl of 1.334 g/cm³. Mol. wt estimates for the virus nucleic acid were 2.95 × 10⁶ by electrophoresis in polyacrylamide gels and 3.46 × 10⁶ from the sedimentation coefficient (41.4S) in linear-log sucrose density gradients. Two polypeptides were detected in virus preparations; one (mol. wt 30 500) was possibly a breakdown product of the other (mol. wt 33 000). GYSV was serologically distantly related to onion yellow dwarf and leek yellow stripe viruses but was considered to be a separate virus because it differed from them in host range.     

Purification and properties of Australian lucerne latent virus, a seed-borne virus having affinities with nepoviruses

An isolate of Australian lucerne latent virus (ALLV) from lucerne in New Zealand was mechanically transmitted to a few herbaceous hosts. It induced diagnostic symptoms in several species of the Chenopodiaceae, but was symptomless in most other hosts including lucerne and Trifolium subterraneum. It was seed transmitted in lucerne. When assayed to Chenopodium quinoa, infective C. quinoa sap lost infectivity after diluting to 10^-4, heating for 10 min at 55°C and storage for 4 days at 4°C. ALLV was purified from infected C. quinoa or pea plants by extracting sap in 0.1 m borate buffer (pH 7) containing 0.2% 2-mercaptoethanol and clarifying with 15% bentonite suspension, high and low speed centrifugation and sucrose density gradient centrifugation. Purified virus preparations contained isometric particles about 25 nm in diameter and sedimented as three virus components with sedimentation coefficients (s_20-w⁰) of 56 S, 128 S and 133 S. The 56 S component appeared to consist of nucleic acid-free protein shells. Polyacrylamide gel electrophoresis of virus preparations showed that ALLV contained a single protein species of mol. wt 55 000 and two RNA species of mol. wt 2.1 × 10⁶ and 2.4 × 10⁶. An antiserum to ALLV had an homologous titre of 1/256 to purified virus but failed to detect ALLV in infective sap of C. quinoa, pea or lucerne. Purified ALLV failed to react to antisera to 28 distinct isometric plant viruses including those to 10 nepoviruses.     

Properties of a carlavirus causing a latent infection of pepino (Solanum muricatum)

Pepino (Solanum muricatum) cuttings imported from Chile contained a latent virus which was transmitted by inoculation of sap to Chenopodium quinoa but not to 21 other species. The virus was transmitted by the aphid, Myzus persicae. In C. quinoa sap, the virus lost infectivity when diluted between 10^-3 and 10^-4, heated for 10 min between 65 and 70 °C, or stored at room temperature for 4 to 6 days. The virus particles were straight or slightly flexuous filaments 660 to 680 nm long. Up to 15 mg virus per 100 g C. quinoa leaves was obtained by clarification with a mixture of chloroform and carbon tetrachloride. Purified preparations had A_max/A_min= 1.11, A₂₆₀/A₂₈₀= 1–30, A^0.₂₆₀^1%= 2.8, and contained a single sedimenting component with a sedimentation coeficient of 149s and a buoyant density in CsCl of 1–318. The virus particles contained 5.5% of single-stranded RNA of mol. wt 2.4×10⁶ (estimated by gel electrophoresis of undenatured RNA) and sedimentation coefficient 38.5S, and a single polypeptide of mol. wt 33 000. The virus is distantly serologically related to potato S and carnation latent viruses and is considered a new member of the carlavirus group. The name pepino latent virus is proposed. The cryptogram for this virus is R/1: 2.4/5–5: E/E: S/Ve/Ap.     

Pepper veinal mottle virus-a new member of the potato virus Y group from peppers (Capsicum annuum L. and C. frutescens L.) in Ghana

Pepper veinal mottle virus (PVMV), a previously undescribed virus widespread in Capsicum annuum and C. frutescens in the Eastern Region of Ghana, is acquired and inoculated in 2 min feeding periods by aphids (Myzus persicae and Aphis gossypii); it is transmissible by inoculation of sap to eleven of fifteen Solanaceae and to five of forty-six other species within three of seventeen other families. The virus was propagated in Nicotiana clevelandii and Petunia hybrida, and assayed in Chenopodium quinoa, C. amaranticolor and C. murale. Sap from Capsicum annuum was infective after dilution to 10^-3 but not 10^-4, after 10 min at 55 but not 60^oC, and after 7 but not 8 days at 25^oC. Lyophilized sap from P. hybrida was infective after 6 years in vacuo. Yields of 10–25 mg of virus per kg of leaf tissue were consistently obtained from P. hybrida or N. clevelandii by extracting systemically infected leaves in 0.5 M borate (pH 7.8) containing 0.2% mercaptoethanol and chloroform, followed by repeated precipitation with 50 g polyethylene glycol (M.W. 6000) per l, several cycles of differential centrifugation and centrifugation in sucrose density-gradient columns. Virus preparations had ultraviolet absorption spectra typical of a nucleoprotein containing c. 6% nuclei acid (A 260/280 = 1.25; A 260/246 = 1.27) and contained numerous unaggregated and unbroken filamentous particles c. 770 times 12 nm which sedimented as a single component with a sedimentation coefficient (s^o_20,w) of 155 S. PVMV contained RNA (moles %: G = 24, A = 23, C = 27, U = 26), and a single protein species with a molecular weight of 32000–33000 daltons. PVMV was not serologically related to potato virus Y (three strains), or to twelve other morphologically similar viruses, and seems to be a distinct member of the potato virus Y group. The cryptogram of PVMV is R/(I):*/(6):E/E:S/Ap.     

Production of poly-β-hydroxybutyrate (PHB) by <Emphasis Type="Italic">Alcaligenes latus</Emphasis> from maple sap

Maple sap, an abundant natural product especially in Canada, is rich in sucrose and thus may represent an ideal renewable feedstock for the production of a wide variety of value-added products. In the present study, maple sap or sucrose was employed as a carbon source to Alcaligenes latus for the production of poly-β-hydroxybutyrate (PHB). In shake flasks, the biomass obtained from both the sap and sucrose were 4.4 ± 0.5 and 2.9 ± 0.3 g/L, and the PHB contents were 77.6 ± 1.5 and 74.1 ± 2.0%, respectively. Subsequent batch fermentation (10 L sap) resulted in the formation of 4.2 ± 0.3 g/L biomass and a PHB content of 77.0 ± 2.6%. The number average molecular weights of the PHB produced by A. latus from maple sap and pure sucrose media were 300 ± 66 × 10³ and 313 ± 104 × 10³ g/mol, respectively. Near-infrared, ¹H magnetic resonance imaging (MRI), and ¹³C-MRI spectra of the microbially produced PHB completely matched those obtained with a reference material of poly[(R)-3-hydroxybutyric acid]. The polymer was found to be optically active with [α]²⁵ _D equaled to −7.87 in chloroform. The melting point (177.0°C) and enthalpy of fusion (77.2 J/g) of the polymer were also in line with those reported, i.e., 177°C and 81 J/g, respectively.     

Vector relationships and other characteristics of barley yellow striate mosaic virus (BYSMV)

Barley yellow striate mosaic virus (BYSMV) was inoculated by its planthopper vector Laodelphax striatellus (Homoptera, Delphacidae) to 44 species of Gramineae, 26 of which in eight tribes were infected. The virus was not transmitted through wheat seed nor did it infect five dicotyledonous hosts of other rhabdoviruses. The most susceptible species were in the tribes Festuceae and Hordeae. Barley, Bromus spp., oats, Phalaris canariensis, Setaria italica, Sorghum spp., and sweet corn cv. Golden were diagnostic hosts. Electron microscopy of crude sap was also a sensitive diagnostic method. Properties of BYSMV were determined by injecting L. striatellus with crude sap from infected barley. Sap was infectious after 10 min at 50–55 °C but not after 10 min at 60 °C, when diluted with buffer to 10^--² but not to 10^--³, when stored for 2 but not 4 days at 5 °C or when kept for 1 but not 2 days at 22 °C. The planthopper Javesella pellucida was an experimental vector of BYSMV but the virus was not transmitted by the leafhoppers Macrosteles sexnotatus or Psammotettix striatus (Homoptera, Cicadellidae). The latent period of BYSMV in L. striatellus was most commonly 15 or 16 days (minimum, 9 days; maximum, 29 days). The minimum acquisition access period for transmission was between 1 h and 5 h, and the minimum inoculation feeding time was 15 min. After 24 h and 8 day acquisition feeds, 30.4% and 42.8% respectively of L. striatellus transmitted BYSMV. When transferred daily, infective hoppers transmitted virus intermittently. The maximum retention of infectivity by L. striatellus was 36 days. Two of five infective females transmitted BYSMV transovarially. Larvae became infective in the second wk after hatching and transmitted for up to 3 wk.     

The effect of glucosinolates (mustard oil glycosides) and products of their enzymic degradation on the infectivity of turnip mosaic virus

The effect of glucosinolates sinigrin, progoitrin, epiprogroitrin, gluconapin, gluconapoleiferin, glucobrassicanapin, glucotropaeolin and gluconasturtiin without and with the glucosinolate-degrading enzyme (myrosinase, EC:3.2.3.1.), on the infectivity of turnip mosaic virus was studied. Little or no effect was observed when the intact glucosinolate (2.5 μmol cm⁻³) was added to the suspension of turnip mosaic virus (TuMV, isolate Ruzyně; 0.2 mg cm⁻³ in 0.01 M potassium phosphate buffer) at both pH 7 and pH 6. A significant decrease of virus infectivity was, however, observed when 0.25, 1.25 and 2.5 μmol cm⁻³ of the glucosinolate together with 0.31, 1.56 and 3.13 mg cm⁻³ of the myrosinase, respectively, was added to the virus suspension of both pH 7 and pH 6. The effect, which was greater at pH 6, was most intense with sinalbin and glucobrassicin substrates.     

Properties of a host range and coat protein variant of broad bean true mosaic comovirus from Vicia faba

Unlike other described isolates of broad bean true mosaic comovirus (BBTMV), a variant, code name SB, infected some non-leguminous plant species and, in N. benthamiana, induced systemic mottling and puckering of the leaves. However, like other described BBTMV isolates, purified SB particle preparations contained isometric particles c. 28 nm in diameter that sedimented as two nucleoprotein components with S_{20, w} values of 90S and 109S; some preparations occasionally contained a component of c. 50S. Virus particles contained two ssRNA species which, when denatured in glyoxal, had estimated M_T values of 2.1 × 10⁶ and 1.3 × 10⁶ and co-electrophoresed with cowpea mosaic virus RNA-1 and RNA-2 respectively. Isolate SB was serologically indistinguishable from British and German isolates of BBTMV. However, SB virus particles contained a major polypeptide (L) of M_r between c. 31 000 and up to three minor ones (S) or M_r between c. 20 000 and 24 000. This contrasts with protein preparations from other BBTMV isolates that typically contain only two polypeptides of M_r c. 37 000 (L) and 21 000 (S). Following isopycnic centrifugation in CsCl, SB particles purified from pea separated into two major components with densities of 1.39 and 1.44 g cm^-3 and a minor component of estimated density 1.43 g cm^-3. In Cs₂SO₄, virus preparations separated into three major components with densities of 1.30, 1.32 and 1.36 g cm^-3 and a minor one of density 1.27 g cm^-3. In CsCl isopycnic gradients, SB particles purified from TV. benthamiana separated into two components with densities of 1.38 and 1.43 g cm^-3. During immuno-electrophoresis in agarose gels, freshly prepared virus and preparations stored for up to 4 days at 4°C contained a single component that migrated rapidly to the anode, whereas similar preparations of an English isolate of BBTMV migrated as a single component that moved only slowly toward the anode but which, within 48 h, contained an additional component with a migration rate similar to that of isolate SB. Isolate SB is therefore a host range variant of BBTMV which, in comparison with previously described isolates of BBTMV, has an increased negative charge of its particles prior to any appreciable degradation of its S protein, and S protein that is degraded less rapidly. These features probably account for the anomalies observed in isopycnic centrifugation.     

Properties of cocksfoot streak and cocksfoot cryptic, two viruses infecting cocksfoot (Dactylis glomerata) in Scotland

A Scottish isolate of cocksfoot streak virus (CSV-S) was found to have flexuous filamentous particles which, in sap of infected cocksfoot plants, had a modal length of 712 nm. It was transmitted from infected to healthy cocksfoot plants in a non-persistent manner by Myzus persicae and by mechanical inoculation of infective sap extracts containing an anti-oxidant. Apart from cocksfoot, mechanical inoculation of infective sap succeeded in infecting only four of 22 plant species tested. The infectivity of sap extracts containing 0.2% thioglycerol was lost after heating for 10 min at 55^oC but not 50^oC, storage at room temperature for 48 but not 24 hours, and after diluting 10^-2to 10^-3. Highly purified preparations of CSV-S particles sedimented as a single component with a sedimentation coefficient of 139S and had a buoyant density in rubidium bromide of 1.31 g/cm³. Virus particles were composed of one protein and one ssRNA species with estimated M_r of 31 000 and 3.2 times 10⁶respectively. In ELISA, an antiserum prepared to CSV-S detected the virus in all aerial parts of infected cocksfoot plants and, when present in the ratio of 1 infected leaf: 1000 healthy leaves. Both CSV-S-infected and -uninfected cocksfoot also contained a previously undescribed virus with isometric particles c. 30 nm in diameter. This virus, named cocksfoot cryptic virus (CCV), was seed-borne in two cvs of cocksfoot tested and its particles contained two dsRNA species of estimated M_r of 1.14 times 10⁶and 1.27 times 10⁶. Despite the fact that particles of CSV-S were largely free from CCV particles following exclusion chromatography on agarose beads prior to immunisation, immunoelectron microscopy (IEM) showed that the antiserum prepared to CSV-S also contained some antibodies to CCV. Evidence from IEM suggested a possible distant serological relationship of CCV to ryegrass and beet (BCV 1 or BCV 2, or both) cryptoviruses, all members of sub-group A of crypto viruses.     

Studies on melon necrotic spot virus disease of cucumber and on the control of the fungus vector (Olpidium radicale)

Melon necrotic leaf spot virus (MNSV) caused a major outbreak of a leaf necrosis disease of hydroponically-grown cucumber plants at Humberside in 1983. The virus had c. 33 nm diam. particles which reacted serologically with MNSV antiserum of Dutch or American origin. Virus particles, which contained a single polypeptide (mol. wt 45 × 10³) and a presumed RNA species (mol. wt 1.5 × 10⁶), had a sedimentation coefficient (s_20.w) of 134 S and a buoyant density in caesium chloride of 1.35 g/cm³. The virus was mechanically transmissible, confined to species of Cucurbitaceae, transmitted by zoospores of Olpidium radicale and retained in the resting spores of the fungus. MNSV is thus both water-borne and soil-borne. O. radicale zoospores were killed in <5 min in suspensions containing 20 μg/ml of the surfactant Agral (alkyl phenol ethylene oxide). The disease did not reappear in 1984 when the cucumber crops were fed with nutrients containing 20μg/ml Agral.     

Apple orchard tests on the efficacy of the granulosis virus of the codling moth,Laspeyresia pomonella [Lep.: Olethreutidae]

The protection of apples against damage by the codling moth,Laspeyresia pomonella (L.), by applications of the granulosis virus ofL. pomonella was assessed in apple orchard tests at 4 locations in Canada in 1974–1978. Sprays containing 3×10⁹ to 4×10¹⁰ granules/litre, applied 2 or 3 times per generation of codling moth larvae, reduced injury to apples by 44 to 85% compared to reductions of 72 to 98% by applications of azinphos-methyl or phosmet. Applications of the virus did not reduce numbers of arthropods predaceous on pest insects and mites.

---

Résumé L'efficacité de la protection des pommes contre le carpocapse,Laspeyresia pomonella (L.), par des applications du virus de la granulose deL. pomonella a été évaluée par des assais dans 4 vergers du Canada entre 1974 et 1978. Des pulvérisations contenant de 3×10⁹ à 4×10¹⁰ granules/litre, appliquées 2 ou 3 fois par génération de larves du carpocapse des pommes, ont réduit les dommages aux pommes de 44 à 85% comparé à des réductions de 72 à 98% obtenues avec des pulvérisations d'azinphos-méthyl ou de phosmet. Les applications de virus n'ont pas réduit les populations d'arthropodes prédateurs d'insectes nuisibles et d'acariens.

     

Purification and some properties of Tephrosia symptomless virus

Tephrosia symptomless virus (TSV), isolated from Tephrosia villosa, is widely distributed in coastal districts of Kenya. The virus was readily transmitted by inoculation of sap, but not by Aphis craccivora or Apion sp. (Curculionidae) or through soil. Host range was very restricted and it infected only 10 of 70 species tested in one of nine plant families; susceptible species were confined to five genera within the Papilionaceae. The virus was cultured, propagated and assayed in soybean. TSV remained infective after 10 min at 85°C, 3 wk at 20°C and 26 wk at -12°C; crude infective sap of Glycine max retained infectivity when diluted 10^-6 but not 10^-7. Virus was purified from systemically infected soybean by clarifying sap extracted in 0.06 m phosphate buffer containing 0.001 m EDTA and 0.1% thioglycollic acid (pH 7.5) with equal volumes of 1:1 n-butanol/chloroform followed by two cycles of differential and one of sucrose density gradient centrifugation. Purified preparations contained c. 33 nm isometric particles. TSV contained RNA and one protein of molecular weight 1.53. 10⁶ and c. 42 000, respectively. Analytical centrifugation indicated a single component with a sedimentation coefficient (s.20, w) of 127 S; in Cs₂SO₄ and CsCl isopycnic gradients a single virus band formed; buoyant density in CsCl was 1.361. TSV was not related serologically to any of 44 viruses in nine plant virus groups but it resembled the tombusviruses and other ungrouped viruses such as carnation mottle in some of its properties.     

Purification and properties of ginger chlorotic fleck virus

A previously undescribed isometric virus, named ginger chlorotic fleck virus (GCFV), was detected in ginger (Zingiber officinale) imported into Australia from a number of countries. The geographical distribution of the virus is uncertain, but is thought to include India, Malaysia and Mauritius. The virus apparently does not occur in Australian commercial ginger plantings. The virus has isometric particles c. 30 nm in diameter, with a sedimentation coefficient of 111 S, and was readily purified from infected ginger with yields of 50–90 mg/kg leaf tissue. Purified preparations contained a major species of single-stranded RNA of mol. wt 1.50 × 10⁶ and a major coat protein species of mol. wt 29.0 × 10³. At pH 7, the particles formed a single zone in both caesium chloride and caesium sulphate gradients, with buoyant densities of 1.355 g cm^-3 (fixed virus) and 1. 297 g cm^-3 (unfixed virus), respectively. The virus particles migrated as two electrophoretic components and were labile when treated with 10 mM EDTA, 1 M NaCI, 10 mM tris pH 8.25 or when negatively stained with potassium phosphotungstate. GCFV was mechanically transmitted only to ginger, and was not transmitted by the aphids Myzus persicae. Pentalonia nigronervosa, Rhopalosiphum maidis or R. padi. Possible affinities of GCFV with the sobemo-virus group are discussed. The present cryptogram of GCFV is ^R/_l: ^1.5/₂₀: ^S/_S: ^S/_*.     

Artichoke latent virus: characterisation, ultrastructure and geographical distribution

An isolate of artichoke latent virus (ALV-I) obtained from a symptomless artichoke plant in Southern Italy was characterised and compared with ALV isolates from other countries. ALV occurs in California and throughout the western part of the Mediterranean basin but of Mediterranean countries east of Italy, it was found only in Israel and Turkey. ALV-I was readily transmissible by inoculation of sap to a moderate range of hosts, was transmitted in a non-persistent manner by Aphis fabae, Brachicaudus cardui and Myzus persicae, but was not seed transmitted. The virus has flexuous rod-shaped particles measuring c. 12 nm × 746 nm with a sedimentation coefficient of 145 S and a buoyant density of 1·31 g/cm³. The particles contain single stranded RNA with a mol. wt of 3 × 10⁶ and protein composed of a single polypeptide species with a mol. wt of 33 000. Cylindrical cytoplasmic inclusions consisting of pinwheels and laminated aggregates were present in cells of naturally and artificially infected plants. ALV isolates from different geographical origin were indistinguishable from ALV-I biologically, morphologically, serologically and ultrastructurally. These properties place ALV in the Potyvirus group, but it was serologically unrelated to 12 other potyviruses 10 of which occur commonly in Italy.     

The effects of air ions on brain levels of serotonin in mice

Mice were maintained in a controlled pollutant-free microenvironment and were exposed for 12, 24, 48 and 72 hr to 3 different concentrations of small positive or negative air ions: 2–4 × 10³ ions/cm³, 3–4 × 10⁴ ions/cm³ or 3.5–5 × 10⁵ ions/cm³. Spectrophotofluorometric assays of brain serotonin levels of air ion-treated mice showed statistically significant differences as early as 12 hours from those of mice kept in untreated pollutant-free air. Essentially no deviation from control values were observed at 24 and 48 hours. After 72 hours of exposure sharp decreases took place in all groups with the single exception of the animals exposed to 3–4 × 10⁴ positive ions/cm³. The hypothesis that alterations in mood and affect associated with certain meteorological conditions, e.g. winds such as the foehn, sirocco, etc. might depend upon air ion-induced changes in brain levels of serotonin was examined in the light of recent advances in neurophysiology and neuropharmacology.