Purification, serology and physico-chemical properties of a peanut mottle virus isolate from India

A procedure developed for the purification of peanut mottle virus (PMV) isolated from peanuts in India yielded 30–40 mg of virus/kg of plant tissue. Purified virus sedimented as a single component of 151 S. The virus coat protein migrated as a single component in each of two polyacrylamide gel concentrations and had an estimated molecular weight of 34 000 daltons. The molecular weight of the nucleic acid was 3.10 × 106 daltons. In the precipitin ring interface test (PRIT) PMV showed a serological relationship with soybean mosaic virus (SMV). Using the double antibody sandwich form of ELISA, PMV was shown to be distantly related to adzuki bean mosaic (ABMV), amaranthus leaf mottle (ALMV), clover yellow vein (CYVV) viruses and SMV. Immunosorbent electron microscopy (ISEM) showed PMV to be closely related to ABMV, ALMV, CYVV and SMV. In PRIT, ELISA and ISEM tests no specific serological reaction was noted between PMV and antisera to groundnut eye spot, peanut green mosaic, pepper veinal mottle, potato virus Y, sugarcane mosaic and turnip mosaic viruses

Improved Serological Techniques for the Detection and Identification of Groundnut Viruses

Serology is indispensable for the detection and identification of plant viruses. Recently, the highly sensitive enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) techniques have been developed and may replace some of the conventional serological methods. The direct or standard double-antibody sandwich (DAS) form of ELISA. as first described by Clark and Adams (1977), has wide applications in plant virology. An indirect form of ELISA (I-ELISA) has recently been developed by Barbara and Clark (1982). The ISEM procedure developed by Derrick (1973) combines the specificity of serology with coventional electron microscopy. DAS-ELISA, I-ELISA and ISEM have been adapted for the detection and identification of several groundnut viruses. This paper will provide a description of each technique and its application for the detection and characterization of viruses occurring on groundnut in India

Isolation and characterization of a geminivirus causing yellow mosaic disease of horsegram (Macrotyloma uniflorum (Lam.) Verdc.) in India.

Horsegram yellow mosaic disease was shown to be caused by a geminivirus; horsegram yellow mosaic virus (HYMV). The virus could not be transmitted by mechanical sap inoculation. Leaf dip and purified virus preparations showed geminate virus particles, measuring 15-18 * 30 nm. An antiserum for HYMV was produced and in enzyme-linked immunosorbent assay (ELISA) and immunosorbent electron microscopy (ISEM) tests HYMV was detected in leaf extracts of fieldinfected bambara groundnut, french bean, groundnut, limabean, mungbean, pigeonpea and soybean showing yellow mosaic symptoms. Bemisia tabaci fed on purified HYMV through a parafilm membrane transmitted the virus to all the hosts listed above but not to Ageratum conyzoides, okra, cassava, cowpea, Croton bonplandianus, Lab-lab purpureus, Malvastrum coromandalianum and tomato. No reaction was obtained in ELISA and ISEM tests between HYMV antibodies and extracts of plants diseased by whitefly-transmitted agents in India such as A. conyzoides yellow mosaic, okra yellow vein mosaic, C. bonplandianus, yellow vein mosaic, M. coromandalianum yellow vein mosaic, tomato leaf curl and cassava mosaic. HYMV was also not found to be related serologically to bean golden mosaic, virus

Indian Peanut Clump Virus Isolates: Host Range, Symptomatology, Serological Relationships, and Some Physical Properties

The symptomatology of Indian peanut clump virus (IPCV) isolates collected from five different geographical locations, Bapatla (B), Chinnaganjam (C), Hyderabad (H), Ludhiana (L), and Talod (T), differed. B-IPCV and C-IPCV were indistinguishable by host range but could be distinguished from the other isolates by symptoms on Canavalia ensiformis, Nicotiana clevelandii × glutinosa, Phaseolus vulgaris, and Vigna unguiculata. B-IPCV, C-IPCV, and T-IPCV were related serologically, but could be distinguished from H-IPCV and L-IPCV isolates in serological tests. The five isolates could not be distinguished on the basis of particle size. Each isolate contained two RNA species of 1.90 × 106 and 1.65 × 106 Mr estimated under nondenaturing conditions and a single polypeptide of 24 × 103 Mr. Significance of these findings for the diagnosis of IPCV and for screening of peanut genotypes for resistance is discussed

The occurrence of Indian peanut clump, a soil-borne virus disease of groundnuts (Arachis hypogaea) in India

A disease characterised by severely stunted plants with small dark green leaves was found in groundnut (Arachis hypogaea) in sandy soils in Punjab State, India. The disease occurred in patches in the field and reappeared in the same positions in succeeding groundnut crops. Plants infected early did not produce mature pods. Seeds sown in soil collected from infected fields produced plants with typical disease symptoms. Phaseolus vulgaris cv. Local and Chenopodium quinoa were found to be good diagnostic hosts. The disease was shown to be caused by a rod-shaped virus c. 24 nm in diameter with predominant particle lengths of c. 249 and 184 nm when stained in uranyl acetate. The virus, named Indian peanut clump virus (IPCV), resembled peanut clump virus (PCV) reported from W. Africa in symptomatology on groundnuts, particle morphology and soil-borne nature. However, it is not serologically related to two W. African PCV isolates tested, or to tobacco rattle (PRN and CAM strains) or pea early browning virus (Dutch isolate) in microprecipitin, enzyme linked immunosorbent assay and immunosorbent electron microscopy tests

Studies on transmission of Indian peanut clump virus disease by Polymyxa graminis

The plasmodiophoromycete fungus, Polymyxa graminis was observed in the roots of Sorghum bicolor, S. sudanense, Pennisetum glaucum, Triticum aestivum, Cyperus rotundus, Eleucine coracana, Zea mays, Tridax procumbens and Arachis hypogaea collected from Indian peanut clump virus (IPCV)-infested fields. Examination of roots of IPCV-infected S. bicolor, S. sudanense, P. glaucum and T. aestivum grown in previously air dried field soil also showed the presence of cystosori of P. graminis. IPCV-infested soil stored at room temperature for 3 years transmitted the virus to A. hypogaea, T. aestivum and S. bicolor. Roots extracted from IPCV-infected P. glaucum and S. bicolor containing cystosori, and dried root fragments incorporated into sterile soil, transmitted the virus to A. hypogaea and T. aestivum. The root extracts contained primary zoospores of the fungus, presumably arising from cystosori. Utilising root fragments of S. sudanense containing cystosori as inoculum P. graminis was shown to infect both monocotyledonous and dicotyledonous plants. Profuse cystosorus production in rootlets only occurred in monocotyledonous plants. In dicotyledonous plants, in general, only few rootlets showed cystosori. Indian isolates of P. graminis appear to differ from isolates from temperate soils in that they can infect dicotyledonous plants and have a much wider host rang

HIFI detection of HF in the carbon star envelope IRC +10216

We report the detection of emission in the J=1-0 rotational transition of hydrogen fluoride (HF), together with observations of the J=1-0 to J=3-2 rotational lines of H35Cl and H37Cl, towards the envelope of the carbon star IRC +10216. High-sensitivity, high-spectral resolution observations have been carried out with the HIFI instrument on board Herschel, allowing us to resolve the line profiles and providing insights into the spatial distribution of the emission. Our interpretation of the observations, with the use of radiative transfer calculations, indicates that both HF and HCl are formed in the inner regions of the envelope close to the AGB star. Thermochemical equilibrium calculations predict HF and HCl to be the major reservoirs of fluorine and chlorine in the atmospheres of AGB stars. The abundances relative to H2 derived for HF and HCl, 8e-9 and 1e-7 respectively, are substantially lower than those predicted by thermochemical equilibrium, indicating that F and Cl are likely affected by significant depletion onto dust grains, although some chlorine may be in the form of atomic Cl. The H35Cl/H37Cl abundance ratio is 3.3 +/- 0.3. The low abundance derived for HF in IRC +10216 makes it likely that the fluorine abundance is not enhanced over the solar value by nucleosynthesis in the AGB star, although this conclusion may not be robust because the HF abundance we derive is a lower limit to the elemental abundance of F. These observations suggest that both HF and HCl should be detectable through low J rotational transitions in other evolved stars.Comment: Accepted for publication in A&A Letter

Toxic equivalency factors (TEFs) for PCBs, PCDDs, PCDFs for humans and wildlife.

An expert meeting was organized by the World Health Organization (WHO) and held in Stockholm on 15-18 June 1997. The objective of this meeting was to derive consensus toxic equivalency factors (TEFs) for polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and dioxinlike polychlorinated biphenyls (PCBs) for both human, fish, and wildlife risk assessment. Based on existing literature data, TEFs were (re)evaluated and either revised (mammals) or established (fish and birds). A few mammalian WHO-TEFs were revised, including 1,2,3,7,8-pentachlorinated DD, octachlorinated DD, octachlorinated DF, and PCB 77. These mammalian TEFs are also considered applicable for humans and wild mammalian species. Furthermore, it was concluded that there was insufficient in vivo evidence to continue the use of TEFs for some di-ortho PCBs, as suggested earlier by Ahlborg et al. [Chemosphere 28:1049-1067 (1994)]. In addition, TEFs for fish and birds were determined. The WHO working group attempted to harmonize TEFs across different taxa to the extent possible. However, total synchronization of TEFs was not feasible, as there were orders of a magnitude difference in TEFs between taxa for some compounds. In this respect, the absent or very low response of fish to mono-ortho PCBs is most noticeable compared to mammals and birds. Uncertainties that could compromise the TEF concept were also reviewed, including nonadditive interactions, differences in shape of the dose-response curve, and species responsiveness. In spite of these uncertainties, it was concluded that the TEF concept is still the most plausible and feasible approach for risk assessment of halogenated aromatic hydrocarbons with dioxinlike properties

The Mycobacterium tuberculosis Phagosome Is a HLA-I Processing Competent Organelle

Mycobacterium tuberculosis (Mtb) resides in a long-lived phagosomal compartment that resists maturation. The manner by which Mtb antigens are processed and presented on MHC Class I molecules is poorly understood. Using human dendritic cells and IFN-γ release by CD8+ T cell clones, we examined the processing and presentation pathway for two Mtb–derived antigens, each presented by a distinct HLA-I allele (HLA-Ia versus HLA-Ib). Presentation of both antigens is blocked by the retrotranslocation inhibitor exotoxin A. Inhibitor studies demonstrate that, after reaching the cytosol, both antigens require proteasomal degradation and TAP transport, but differ in the requirement for ER–golgi egress and new protein synthesis. Specifically, presentation by HLA-B8 but not HLA-E requires newly synthesized HLA-I and transport through the ER–golgi. Phenotypic analysis of the Mtb phagosome by flow organellometry revealed the presence of Class I and loading accessory molecules, including TAP and PDI. Furthermore, loaded HLA-I:peptide complexes are present within the Mtb phagosome, with a pronounced bias towards HLA-E:peptide complexes. In addition, protein analysis also reveals that HLA-E is enriched within the Mtb phagosome compared to HLA-A2. Together, these data suggest that the phagosome, through acquisition of ER–localized machinery and as a site of HLA-I loading, plays a vital role in the presentation of Mtb–derived antigens, similar to that described for presentation of latex bead-associated antigens. This is, to our knowledge, the first description of this presentation pathway for an intracellular pathogen. Moreover, these data suggest that HLA-E may play a unique role in the presentation of phagosomal antigens