scholarly journals Studies on the Transmission and Virus-Vector Relationship of Rice-Tungro Virus (RTV) in Different Rice Genotype

2017 ◽  
Vol 7 (4) ◽  
pp. 321-326
Author(s):  
Ali Azgar et al., Ali Azgar et al., ◽  
Author(s):  
M. Swathi ◽  
Neeta Gaur ◽  
Kamendra Singh

Background: Whitefly is one of the most destructive sucking pest in the tropical and subtropical regions of the world and causing significant crop losses directly by sucking sap from the plants and indirectly through the transmission of viral diseases specifically caused by the genus Begomovirus. The Begomovirus species viz., Mungbean yellow mosaic India virus (MYMIV) and Mungbean yellow mosaic virus (MYMV) are causing yellow mosaic virus disease in soybean, which is transmitted by whiteflies. The disease accounts to 30-70 per cent yield loss and increases up to 80 - 100 per cent during severe incidence. Hence, there is a need for development of integrated pest management strategies against disease and whiteflies, for this the knowledge on virus-vector relationship is required. But, the studies on biological relationship of yellow mosaic virus disease and whitefly in soybean are scarce. At this juncture, considering the importance of disease in soybean, the present investigation was carried out to know the virus -vector relationship of the YMV and whitefly in soybean.Methods: The experiment on virus-vector relationship of yellow mosaic virus and whitefly in soybean was conducted at Department of Entomology, College of Agriculture, G. B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during 2016-17. The data on number of whiteflies per plant, acquisition and inoculation access feeding period and pre and post starvation period required for effective transmission of virus was recorded.Result: A single viruliferous whitefly was able to transmit virus and ten viruliferous whiteflies per plant were required for cent per cent transmission of virus. The minimum acquisition access and inoculation access feeding periods required for virus transmission was 0.25h (15 min) each; while the 100 per cent virus transmission was recorded with acquisition and inoculation period of 12h, each. The per cent transmission was increased with the increase of acquisition and inoculation periods. The rate of transmission was positively correlated with pre-acquisition starvation period and negatively correlated with post- acquisition starvation period.


Author(s):  
N W S Suliartini ◽  
T Wijayanto ◽  
A Madiki ◽  
D Boer ◽  
Muhidin ◽  
...  

2005 ◽  
Vol 40 (1-2) ◽  
pp. 23-30 ◽  
Author(s):  
N. Rajinimala ◽  
R. Rabimdran ◽  
A. A. Kamalakannan ◽  
P. Mareeswari

Paleobiology ◽  
1980 ◽  
Vol 6 (02) ◽  
pp. 146-160 ◽  
Author(s):  
William A. Oliver

The Mesozoic-Cenozoic coral Order Scleractinia has been suggested to have originated or evolved (1) by direct descent from the Paleozoic Order Rugosa or (2) by the development of a skeleton in members of one of the anemone groups that probably have existed throughout Phanerozoic time. In spite of much work on the subject, advocates of the direct descent hypothesis have failed to find convincing evidence of this relationship. Critical points are:(1) Rugosan septal insertion is serial; Scleractinian insertion is cyclic; no intermediate stages have been demonstrated. Apparent intermediates are Scleractinia having bilateral cyclic insertion or teratological Rugosa.(2) There is convincing evidence that the skeletons of many Rugosa were calcitic and none are known to be or to have been aragonitic. In contrast, the skeletons of all living Scleractinia are aragonitic and there is evidence that fossil Scleractinia were aragonitic also. The mineralogic difference is almost certainly due to intrinsic biologic factors.(3) No early Triassic corals of either group are known. This fact is not compelling (by itself) but is important in connection with points 1 and 2, because, given direct descent, both changes took place during this only stage in the history of the two groups in which there are no known corals.


Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.


Author(s):  
Leon Dmochowski

Electron microscopy has proved to be an invaluable discipline in studies on the relationship of viruses to the origin of leukemia, sarcoma, and other types of tumors in animals and man. The successful cell-free transmission of leukemia and sarcoma in mice, rats, hamsters, and cats, interpreted as due to a virus or viruses, was proved to be due to a virus on the basis of electron microscope studies. These studies demonstrated that all the types of neoplasia in animals of the species examined are produced by a virus of certain characteristic morphological properties similar, if not identical, in the mode of development in all types of neoplasia in animals, as shown in Fig. 1.


Author(s):  
J.R. Pfeiffer ◽  
J.C. Seagrave ◽  
C. Wofsy ◽  
J.M. Oliver

In RBL-2H3 rat leukemic mast cells, crosslinking IgE-receptor complexes with anti-IgE antibody leads to degranulation. Receptor crosslinking also stimulates the redistribution of receptors on the cell surface, a process that can be observed by labeling the anti-IgE with 15 nm protein A-gold particles as described in Stump et al. (1989), followed by back-scattered electron imaging (BEI) in the scanning electron microscope. We report that anti-IgE binding stimulates the redistribution of IgE-receptor complexes at 37“C from a dispersed topography (singlets and doublets; S/D) to distributions dominated sequentially by short chains, small clusters and large aggregates of crosslinked receptors. These patterns can be observed (Figure 1), quantified (Figure 2) and analyzed statistically. Cells incubated with 1 μg/ml anti-IgE, a concentration that stimulates maximum net secretion, redistribute receptors as far as chains and small clusters during a 15 min incubation period. At 3 and 10 μg/ml anti-IgE, net secretion is reduced and the majority of receptors redistribute rapidly into clusters and large aggregates.


Author(s):  
D.L. Spector ◽  
S. Huang ◽  
S. Kaurin

We have been interested in the organization of RNA polymerase II transcription and pre-mRNA splicing within the cell nucleus. Several models have been proposed for the functional organization of RNA within the eukaryotic nucleus and for the relationship of this organization to the distribution of pre-mRNA splicing factors. One model suggests that RNAs which must be spliced are capable of recruiting splicing factors to the sites of transcription from storage and/or reassembly sites. When one examines the organization of splicing factors in the nucleus in comparison to the sites of chromatin it is clear that splicing factors are not localized in coincidence with heterochromatin (Fig. 1). Instead, they are distributed in a speckled pattern which is composed of both perichromatin fibrils and interchromatin granule clusters. The perichromatin fibrils are distributed on the periphery of heterochromatin and on the periphery of interchromatin granule clusters as well as being diffusely distributed throughout the nucleoplasm. These nuclear regions have been previously shown to represent initial sites of incorporation of 3H-uridine.


Author(s):  
Kathleen B. Reuter

The reaction rate and efficiency of piperazine to 1,4-diazabicyclo-octane (DABCO) depends on the Si/Al ratio of the MFI topology catalysts. The Al was shown to be the active site, however, in the Si/Al range of 30-200 the reaction rate increases as the Si/Al ratio increases. The objective of this work was to determine the location and concentration of Al to explain this inverse relationship of Al content with reaction rate.Two silicalite catalysts in the form of 1/16 inch SiO2/Al2O3 bonded extrudates were examined: catalyst A with a Si/Al of 83; and catalyst B, the acid/phosphate Al extracted form of catalyst A, with a Si/Al of 175. Five extrudates from each catalyst were fractured in the transverse direction and particles were obtained from the fracture surfaces near the center of the extrudate diameter. Particles were also obtained from the outside surfaces of five extrudates.


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