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Articles 1 - 22 of 22

Full-Text Articles in Biochemistry, Biophysics, and Structural Biology

A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi Jan 2008

A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi

Retrospective Theses and Dissertations

Programmed Cell Death (PCD) plays a pivotal role in plant development and defense. Pathogen dependent cell-death mutants were used to investigate the complex regulatory pathways between PCD and R-gene mediated resistance. Time-course expression profiles of Blumeria graminis f. sp. hordei (Bgh) challenged C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast-neutron-derived "Bgh-induced tip cell death1" mutant, bcd1, were compared using the 22K Barley1 GeneChip. Contrasts were made to identify genes associated with the cell death phenotype as opposed to R-gene mediated resistance. One hundred eighty-two genes were found in the intersection of these contrasts at a ...


Mechanism Of Cap-Independent Translation By Long Distance Kissing Stem-Loop Interactions In Plant Viral Rnas, Aurélie Mamisoa Rakotondrafara Jan 2007

Mechanism Of Cap-Independent Translation By Long Distance Kissing Stem-Loop Interactions In Plant Viral Rnas, Aurélie Mamisoa Rakotondrafara

Retrospective Theses and Dissertations

While the presence of a 5' cap and a 3' poly(A) tail are key elements for efficient translation of eukaryotic mRNAs, many viral mRNAs lack one or both of such structures and yet translate efficiently. Owing to the absence of a 5' cap, Barley yellow dwarf virus (BYDV, Luteoviridae family) genomic and subgenomic RNA1 rely on a cap-independent translation element (BTE), which is an RNA domain capable of promoting translation. In contrast to an internal ribosome entry site (IRES), the BTE is located at the 3' end of the viral mRNA, while translation initiation occurs at the 5' end ...


Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao Jan 2006

Recognition And Signal Transduction In The Expression Of Phytophthora Resistance In Soybean [Glycine Max (L) Merr] , Hongyu Gao

Retrospective Theses and Dissertations

Phytophthora sojae, a hemibiotrophic oomycete, is the causal pathogen of stem and root rot disease of soybean (Glycine max [L.] Merr). The annual soybean yield loss suffered from this disease is valued at about 300 million dollars. A series of single Rps genes protect soybean from the root and stem rot disease. In the last two decades Rps1-k has been the most stable and widely used Phytophthora resistance gene in the major soybean-producing regions of the United States;Two classes of CC-NB-LRR-type Rps1-k genes were isolated from the Rps1-k locus. Representative members from each gene class were expressed in transgenic ...


Translational Control Of Gene Expression Mediated By The 3' Untranslated Region Of Barley Yellow Dwarf Virus , Elizabeth Lynn Pettit Jan 2005

Translational Control Of Gene Expression Mediated By The 3' Untranslated Region Of Barley Yellow Dwarf Virus , Elizabeth Lynn Pettit

Retrospective Theses and Dissertations

The 869 nt 3' untranslated region (3' UTR) of Barley yellow dwarf luteovirus (BYDV) RNA facilitates cap-independent and poly(A) tail-independent translation. A 105 nt cap-independent translation element (BTE, or BYDV TE) within the 3' UTR was previously defined using wheat germ translation extracts (Guo et al., 2000), but additional 3' UTR sequence is required for translation in plant cells. One domain, nt 4918--5008, confers cap-independent translation in vivo in a discrete and strong manner. Some of this extra sequence places the BTE on a phylogenetically conserved, long double-stranded "stalk", making it more accessible to cellular translational machinery. Another sequence ...


Sooty Blotch And Flyspeck On Apple: Expansion Of The Fungal Complex, Post-Harvest Removal And Heterogeneity Of Apple Canopy Wetness And Its Impact On The Outcome Of A Disease-Warning System , Jean Carlson Batzer Jan 2005

Sooty Blotch And Flyspeck On Apple: Expansion Of The Fungal Complex, Post-Harvest Removal And Heterogeneity Of Apple Canopy Wetness And Its Impact On The Outcome Of A Disease-Warning System , Jean Carlson Batzer

Retrospective Theses and Dissertations

Sooty blotch and flyspeck (SBFS) fungi blemish the cuticle of apples. Previous studies reported that the SBFS complex is comprised of four species. This is study surveyed the SBFS complex from nine orchards in four Midwestern states (USA). The LSU analyses of the rDNA inferred that 30 species were Dothideomycetes; one species was within the Pleosporales, 27 were within Dothideales, and two species could not be placed at the ordinal level. The LSU sequences of 17 Dothideales species clustered with LSU sequences of known species of Mycosphaerella. Post-harvest dips in commercial disinfestants were used to remove SBFS signs. Apples were ...


Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter Jan 2002

Identification And Characterization Of Proteins Expressed In The Nectar Of Ornamental Tobacco , Clay Jeremy Carter

Retrospective Theses and Dissertations

A small set of proteins, termed Nectarins, are secreted into the nectar of ornamental tobacco (Nicotiana langsdorffii x Nicotiana sanderae). The most highly expressed protein, Nectarin I (29 kD monomer), was originally identified as a germin-like protein (GLP) of unknown function. This remarkably stable protein was later shown to possess manganese dependent superoxide dismutase activity. Hydrogen peroxide, the product of SOD activity, was found to accumulate in nectar at levels up to 4 mM. The promoter (1.2 kb) of the Nectarin I gene was fused to the reporter gene chloramphenicol acetyl transferase (CAT) and shown to be expressed in ...


Molecular Mechanisms Of Cap And Poly(A) Independent Translation Of Barley Yellow Dwarf Virus Rna , Edwards M. Allen Jan 2001

Molecular Mechanisms Of Cap And Poly(A) Independent Translation Of Barley Yellow Dwarf Virus Rna , Edwards M. Allen

Retrospective Theses and Dissertations

Barley yellow dwarf virus RNA contains a translation element (3 'TE) that confers efficient cap-independent initiation at the 5 proximal AUG. Direct end-labeling of RNAs verified the absence of a 5 ' modification on virion RNA. Thus BYDV differs from related viruses by having neither a genome-linked protein nor a 5 ' cap. To function in the 3' UTR, the 3 'TE must recruit ribosomes and associated translation factors, and communicate with the 5' end of the mRNA where translation initiates. The communication function is mediated by direct base pairing between the 3'TE and the 5' UTR. We propose that protein ...


Replication Of Barley Yellow Dwarf Virus Rna And Transcriptional Control Of Gene Expression , Guennadi Koev Jan 1999

Replication Of Barley Yellow Dwarf Virus Rna And Transcriptional Control Of Gene Expression , Guennadi Koev

Retrospective Theses and Dissertations

Barley yellow dwarf virus (BYDV) is an important pathogen of cereal crops. It has a single-stranded positive sense genomic RNA (gRNA), 5.7 kilobases. During infection of a plant cell, BYDV generates a nested set of three subgenomic mRNAs (sgRNAs) for expression of its 3'-proximal genes. The goal of this study was to map and characterize cis-acting RNA signals involved in transcription and replication of BYDV RNA. Three sgRNA promoters and the 3' origin of replication were characterized. The sgRNA1 promoter was mapped to a 98 nt region that contains two stem-loop structures. A combination of primary and secondary ...


Potato Lipoxygenase Genes: Their Role In Tuber Formation And Defense Responses Against Pathogens , Mikhailo V. Kolomiets Jan 1998

Potato Lipoxygenase Genes: Their Role In Tuber Formation And Defense Responses Against Pathogens , Mikhailo V. Kolomiets

Retrospective Theses and Dissertations

Lipoxygenase (LOX) is involved in the synthesis of jasmonic acid, methyl jasmonate, traumatin, and C-6 volatile compounds that serve hormone-like regulatory and defense-related roles in plants. To study possible lipoxygenase involvement in potato tuberization and defense responses against pests, we have isolated, sequenced, and characterized three lipoxygenase cDNA clones that represent distinct LOX genes. Two of these genes, designated POTLX-1 and POTLX-2, have been isolated from an early tuber cDNA library. Northern hybridization studies indicated that accumulation of POTLX-1 and POTLX-2 mRNA was specific to developing tubers and roots and correlated positively with tuber growth. Hormonal treatment, pathogen infection, or ...


The Poplar-Leaf Rust Pathosystem: Inheritance Of Resistance And Pathogenic Variability , Girma Melesse Tabor Jan 1998

The Poplar-Leaf Rust Pathosystem: Inheritance Of Resistance And Pathogenic Variability , Girma Melesse Tabor

Retrospective Theses and Dissertations

Among diseases that cause serious yield reduction on Populus deltoides is leaf rust caused by Melampsora medusae. The objectives of this project were to study the pathogenic variability of M. medusae, the genetic basis of inheritance of M. medusae resistance in a family of P. deltoides; and to identify molecular markers linked to a leaf-rust resistant locus. Three pathotypes of M. medusae were identified on the basis of their differential reaction to three Populus clones. Pathotypes D-93, F-93, and IL-48 were compatible with clone 1-488 (P. X euramericana). F-93 and IL48 were also compatible with clone 57-276 (P. deltoides X ...


Cloning And Characterization Of A Soybean Snf2 Yeast Homolog , Weiping Chen Jan 1997

Cloning And Characterization Of A Soybean Snf2 Yeast Homolog , Weiping Chen

Retrospective Theses and Dissertations

It is of great economic and scientific interest to understand plant disease resistance genes at the molecular level. Phytophthora sojae, a fungal pathogen of soybean is of particular interest since the root and stem rot resulting from its infection causes great economic loss. It is the goal of this project to clone Phytophthora resistance genes from soybean. This was done by designing primers from the conserved regions of known plant disease resistance genes using a modified differential display for near isogenic lines; L85-3044 a resistant line and Williams, a susceptible line. Several polymorphic bands were identified, including a unique 0 ...


Replication Of Barley Yellow Dwarf Luteovirus-Pav Rna , Mohan Bangalore Jan 1997

Replication Of Barley Yellow Dwarf Luteovirus-Pav Rna , Mohan Bangalore

Retrospective Theses and Dissertations

Barley yellow dwarf luteovirus (BYDV)-PAV serotype, an economically important virus of small grain cereals, has a positive-sense RNA genome encoding at least six open reading frames (ORFs). The goal of the research was to determine the genes and sequences involved in the viral replication and to design efficient antiviral strategies to BYDV-PAV. Genetically engineered resistance is essential for BYDV as the natural resistance is inadequate. Antiviral constructs such as sense RNA, antisense RNA and viral polymerase gene were tested for their ability to reduce virus titre in oat protoplasts as monitored by enzyme-linked immunosorbent assay. All antiviral constructs yielded ...


Regulation Of Translation By The 3' Untranslated Region Of Barley Yellow Dwarf Virus-Pav Rna , Shanping Wang Jan 1996

Regulation Of Translation By The 3' Untranslated Region Of Barley Yellow Dwarf Virus-Pav Rna , Shanping Wang

Retrospective Theses and Dissertations

Eukaryotic translation initiation is an important step for gene expression. This process is stimulated by the interaction of 5' cap and 3' poly(A) tail mediated by trans-acting factors. Positive sense viral RNA can differ from the cellular mRNA by lacking either a 5' cap, or 3' poly(A) tail or both. Therefore, various strategies have evolved by the RNA viruses to achieve efficient translation. Barley yellow dwarf virus-PAV serotype (BYDV-PAV) lacks both a 5' cap and 3' poly(A) tail. I found that a sequence (called 3'TE for 3' translation enhancer) at the 3'UTR of barley yellow ...


Biology Of Rpv Barley Yellow Dwarf Virus Satellite Rna , Lada Rasochova Jan 1996

Biology Of Rpv Barley Yellow Dwarf Virus Satellite Rna , Lada Rasochova

Retrospective Theses and Dissertations

Satellite RNAs (satRNAs) depend on their helper viruses for replication, encapsidation and spread. The goal of the research was to determine helper virus specificity and host range of the RPV barley yellow dwarf luteovirus (BYDV-RPV) satRNA (satRPV RNA) and assay satRPV RNA for the ability to affect the accumulation and modulate disease symptoms of its helper viruses in protoplasts and plants. Although similar in structural genes, subgroup I and II luteoviruses have very different polymerases. BYDV-RPV and beet western yellows virus (BWYV), members of subgroup II luteoviruses, supported satRPV RNA replication in monocotyledonous and dicotyledonous hosts, respectively. In contrast, BYDV-PAV ...


Molecular Basis Of Resistance To Soybean Mosaic Virus: Reverse Transcription (Rt)-Pcr And Strain Complementation Analysis In Soybeans , Michael E. Omunyin Jan 1995

Molecular Basis Of Resistance To Soybean Mosaic Virus: Reverse Transcription (Rt)-Pcr And Strain Complementation Analysis In Soybeans , Michael E. Omunyin

Retrospective Theses and Dissertations

Soybean (Glycine max(L.) Merr.) is grown in both developed and developing countries primarily for vegetable oil and protein products. It is the third most widely planted crop in the United States. Soybean mosaic virus (SMV) can affect soybean production by causing reduction in grain yield and quality. The virus is a member of the large and economically important family Potyviridae and several strains have been identified. Soybean lines exist that contain single genes (Rsv) for resistance to SMV. Therefore, SMV and soybean have been used as a model to understand plant resistance to virus disease. One facet of this ...


Gene Expression Strategies Of Barley Yellow Dwarf Virus , S. P. Dinesh-Kumar Jan 1993

Gene Expression Strategies Of Barley Yellow Dwarf Virus , S. P. Dinesh-Kumar

Retrospective Theses and Dissertations

Barley yellow dwarf virus (BYDV) has a positive sense, 5.7kb RNA genome encoding at least six open reading frames (ORFs). BYDV uses variety of unusual translational strategies to express its genes. These include frameshifting in the polymerase (60K) ORF, leaky scanning at the AUGs of the overlapping coat protein (CP) and 17K ORFs, and readthrough of the CP stop codon;Full-length cDNA clone of BYDV-PAV has been constructed to understand functions of different viral genes and the roles of specific sequences in translation, replication and encapsidation. Translation in cell-free extracts using in vitro synthesized full-length transcripts resulted in expected ...


In Vitro Analysis Of The Self-Cleaving Satellite Rna Of Barley Yellow Dwarf Virus , Stanley Livingstone Silver Jan 1993

In Vitro Analysis Of The Self-Cleaving Satellite Rna Of Barley Yellow Dwarf Virus , Stanley Livingstone Silver

Retrospective Theses and Dissertations

The goals of this research are to begin to define key biological elements involved in the propagation of the satellite RNA associated with barley yellow dwarf virus, serotype RPV (sBYDV) and to design target-specific ribozymes against BYDV genomic RNA. sBYDV RNA is 322 nucleotides long, contains no significant open reading frames, requires BYDV for replication, encapsidation and spread and self-cleaves in the presence of Mg[superscript]2+ and neutral pH. Sequence comparison of several self-cleaving RNAs revealed the presence of a hammerhead-shaped structure spanning the cleavage site. The hammerhead is composed of 11 highly conserved, predominately single-stranded nucleotides and 3 ...


Translational Frameshifting By Barley Yellow Dwarf Virus Rna , Rong Di Jan 1992

Translational Frameshifting By Barley Yellow Dwarf Virus Rna , Rong Di

Retrospective Theses and Dissertations

Barley yellow dwarf virus is a single-stranded RNA virus, consisting of several serotypes including the PAV serotype which is the focus of this dissertation. The 39K open reading frame (ORF) at the 5[superscript]' end of the 5.7 kb (kilobase) genome overlaps with a downstream 60K ORF by 13 nucleotides. Several approaches were employed to demonstrate that the 60K ORF (putative polymerase gene) is expressed by an unusual minus one (-1) translational frameshifting mechanism. A sequence encompassing this overlap region induces frameshifting in heterologous and native contexts. The efficiency of frameshifting induced by the PAV sequence was approximately 3 ...


A Restriction Fragment Length Polymorphism Map Of Cochliobolus Heterostrophus , Tzy-Hwa Tzeng Jan 1990

A Restriction Fragment Length Polymorphism Map Of Cochliobolus Heterostrophus , Tzy-Hwa Tzeng

Retrospective Theses and Dissertations

An RFLP map was constructed for Cochliobolus heterostrophus, the causal agent of southern corn leaf blight, to facilitate the cloning of pathogenicity genes. A total of 128 RFLP and 4 phenotypic markers were analyzed. Of these, 126 were linked to other markers and delimited 944 cM, or, at a maximum, 58% of the total map length. Several RFLPs were found tightly linked to Tox1, a pathogenicity gene. A previously hypothesized translocation tightly linked to Tox1 was also detected;The numbers and sizes of the chromosomes of the two strains crossed to make the RFLP map were investigated using pulsed field ...


The Combining Ability Of Selected Alfalfa Clones As Related To The Self-Fertility Of The Clones, Their F1 And F2 Progenies , Devere Richard Mcallister Jan 1950

The Combining Ability Of Selected Alfalfa Clones As Related To The Self-Fertility Of The Clones, Their F1 And F2 Progenies , Devere Richard Mcallister

Retrospective Theses and Dissertations

No abstract provided.


The Effect Of Genetic Constitution And Processing Methods On The Ability Of Maize Seed To Germinate In Cold Soil , Loyd Allen Tatum Jan 1942

The Effect Of Genetic Constitution And Processing Methods On The Ability Of Maize Seed To Germinate In Cold Soil , Loyd Allen Tatum

Retrospective Theses and Dissertations

In samples of commercial hybrid seed a highly significant negative correlation (r = -.81) was found between cold-test germination percentages and percentages of the kernels with pericarp injuries over the germ. Highly significant correlations of field stands with cold-test germination percentages were found, indicating that pericarp injuries over the germ are an important cause of poor stands;Pericarp injury was found to occur in shelling and in other steps in processing which involve an impact between the kernels and a hard surface. The moisture content of the seed during shelling and handling was a very important factor in determining the amount ...


Insecticidal Action Of Some Substituted Pyrrolidines , Justus George Kirchner Jan 1939

Insecticidal Action Of Some Substituted Pyrrolidines , Justus George Kirchner

Retrospective Theses and Dissertations

No abstract provided.