Molecular Characterization of Ti Ringspot Associated Emara Virus and the Development of Assays for Its Detection

M.S. University of Hawaii at Manoa 2016.Includes bibliographical references.Ti ringspot disease (TRD) is an emerging virus-like disease of ti plants (Cordyline fruticosa L.) spreading throughout the Hawaiian Islands. Foliar symptoms include chlorotic lesions constricted by secondary veins or circular ring-spots that can coalesce into amorphous lesions. A degenerate reverse transcription (RT)-PCR assay targeting the polymerase gene of known emaraviruses amplified a product from the RNA of symptomatic but not asymptomatic ti plants. The RT-PCR products were sequenced and found to represent a new virus species, designated ti ringspot associated virus (TiRaV). Next generation sequencing of a double-stranded RNA library provided additional sequence information on TiRaV, allowing the development of detection assays able to reliably detect TiRaV and further associate it with TRD. Phylogenetic analyses of this sequence data revealed that TiRaV forms a clade with the emaraviruses Raspberry leaf blotch virus and High Plains wheat mosaic virus in the unassigned plant virus genus Emaravirus

High Plains wheat mosaic virus: An enigmatic disease of wheat and corn causing the High Plains disease

Brief history: In 1993, severe mosaic and necrosis symptoms were observed on corn (maize) and wheat from several Great Plains states of the USA. Based on the geographical location of infections, the disease was named High Plains disease and the causal agent was tentatively named High Plains virus. Subsequently, researchers renamed this virus as maize red stripe virus and wheat mosaic virus to represent the host and symptom phenotype of the virus. After sequencing the genome of the pathogen, the causal agent of High Plains disease was officially named as High Plains wheat mosaic virus. Hence, High Plains virus, maize red stripe virus, wheat mosaic virus, and High Plains wheat mosaic virus (HPWMoV) are synonyms for the causal agent of High Plains disease. Taxonomy: High Plains wheat mosaic virus is one of the 21 definitive species in the genus Emaravirus in the family Fimoviridae. Virion: The genomic RNAs are encapsidated in thread-like nucleocapsids in double-membrane 80–200 nm spherical or ovoid virions. Genome characterization: The HPWMoV genome consists of eight single-stranded negative-sense RNA segments encoding a single open reading frame (ORF) in each genomic RNA segment. RNA 1 is 6,981-nucleotide (nt) long, coding for a 2,272 amino acid protein of RNA-dependent RNA polymerase. RNA 2 is 2,211-nt long and codes for a 667 amino acid glycoprotein precursor. RNA 3 has two variants of 1,439-and 1,441-nt length that code for 286 and 289 amino acid nucleocapsid proteins, respectively. RNA 4 is 1,682-nt long, coding for a 364 amino acid protein. RNA 5 and RNA 6 are 1,715-and 1,752-nt long, respectively, and code for 478 and 492 amino acid proteins, respectively. RNA 7 and RNA 8 are 1,434-and 1,339-nt long, code for 305 and 176 amino acid proteins, respectively. Biological properties: HPWMoV can infect wheat, corn (maize), barley, rye brome, oat, rye, green foxtail, yellow foxtail, and foxtail barley. HPWMoV is transmitted by the wheat curl mite and through corn seed. Disease management: Genetic resistance against HPWMoV in wheat is not available, but most commercial corn hybrids are resistant while sweet corn varieties remain susceptible. Even though corn hybrids are resistant to virus, it still serves as a green bridge host that enables mites to carry the virus from corn to new crop wheat in the autumn. The main management strategy for High Plains disease in wheat relies on the management of green bridge hosts. Cultural practices such as avoiding early planting can be used to avoi

Absolutely p-summing and strongly q-summing mappings in normed spaces.

Thesis (M.Phil.)--Chinese University of Hong Kong.Bibliography: leaf [47

Traitements insecticides à très bas volume (TBV) en culture cotonnière au Cameroun. Premières observations en milieu paysan

La pulvérisation d'insecticide en émulsion concentrée étendue d'eau à raison de 10 litres de solution à l'hectare a été expérimentée sur 500 hectares en 1988. Analyse des aspects pratiques techniques et économiques. Les résultats sont encourageants et la technique TBV est bien accueillie par l'ensemble des paysans. Son extension peut être envisagé

Modeling high resolution MRI: Statistical issues with low SNR

Noise is a common issue for all Magnetic Resonance Imaging (MRI) techniques and obviously leads to variability of the estimates in any model describing the data. A number of special MR sequences as well as increasing spatial resolution in MR experiments further diminish the signal-to-noise ratio (SNR). However, with low SNR the expected signal deviates from its theoretical value. Common modeling approaches therefore lead to a bias in estimated model parameters. Adjustments require an analysis of the data generating process and a characterization of the resulting distribution of the imaging data. We provide an adequate quasi-likelihood approach that employs these characteristics. We elaborate on the effects of typical data preprocessing and analyze the bias effects related to low SNR for the example of the diffusion tensor model in diffusion MRI. We then demonstrate that the problem is relevant even for data from the Human Connectome Project, one of the highest quality diffusion MRI data available so far

Cyclotron maser and plasma wave growth in magnetic loops

Cyclotron maser and plasma wave growth which results from electrons accelerated in magnetic loops are studied. The evolution of the accelerated electron distribution is determined by solving the kinetic equation including Coulomb collisions and magnetic convergence. It is found that for modest values of the column depth of the loop the growth rates of instabilities are significantly reduced and that the reduction is much larger for the cyclotron modes than for the plasma wave modes. The large decrease in the growth rate with column depth suggests that solar coronal densities must be much lower than commonly accepted in order for the cyclotron maser to operate. The density depletion has to be similar to that which occurs during auroral kilometric radiation events in the magnetosphere. The resulting distributions are much more complicated than the idealized distributions used in many theoretical studies, but the fastest growing mode can still simply be determined by the ratio of electron plasma to gyrofrequency, U=omega(sub p)/Omega(sub e). However, the dominant modes are different than for the idealized situations with growth of the z-mode largest for U approximately less than 0.5, and second harmonic x-mode (s=2) or fundamental o-mode (s=1) the dominant modes for 0.5 approximately less than U approximately less than 1. The electron distributions typically contain more than one inverted feature which could give rise to wave growth. It is shown that this can result in simultaneous amplification of more than one mode with each mode driven by a different feature and can be observed, for example, by differences in the rise times of the right and left circularly polarized components of the associated spike bursts

Sequencing studies for the identification and characterization of new and old Rubus viruses

In Europe, raspberry plants are commonly infected with a complex of aphid-transmitted viruses that together cause raspberry mosaic disease (RMD). During the previous 30 years, by grafting and vector transmission to a range of red and black raspberry cultivars, these viruses have been loosely characterized and identified as Raspberry leaf spot virus (RLSV), Raspberry leaf mottle Virus (RLMV), Black raspberry necrosis virus (BRNV) and Rubus yellow net virus. An additional, very widespread virus, Raspberry vein chlorosis virus (RVCV), is spread by a different aphid vector. Recently some sequence data have been obtained for RYNV, BRNV and Raspberry mottle virus (RMoV), a virus found in plants showing RMD symptoms. We have carried out sequencing studies using random amplification and mass analysis approaches and will present information on the relationship between RMoV, RLSV and RLMV, as well as the first data for RVCV and a novel, possibly segmented minus-strand RNA virus infecting raspberry. Keywords: raspberry viruses, RLMV, RLSV, RVCV, RLB

Sequencing studies for the identification and characterization of new and old Rubus viruses

In Europe, raspberry plants are commonly infected with a complex of aphid-transmitted viruses that together cause raspberry mosaic disease (RMD). During the previous 30 years, by grafting and vector transmission to a range of red and black raspberry cultivars, these viruses have been loosely characterized and identified as Raspberry leaf spot virus (RLSV), Raspberry leaf mottle Virus (RLMV), Black raspberry necrosis virus (BRNV) and Rubus yellow net virus. An additional, very widespread virus, Raspberry vein chlorosis virus (RVCV), is spread by a different aphid vector. Recently some sequence data have been obtained for RYNV, BRNV and Raspberry mottle virus (RMoV), a virus found in plants showing RMD symptoms. We have carried out sequencing studies using random amplification and mass analysis approaches and will present information on the relationship between RMoV, RLSV and RLMV, as well as the first data for RVCV and a novel, possibly segmented minus-strand RNA virus infecting raspberry