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Full-Text Articles in Life Sciences

Modeling Effects Of Ecological Factors On Evolution Of Polygenic Pesticide Resistance, C. V. Haridas, Brigitte Tenhumberg Nov 2018

Modeling Effects Of Ecological Factors On Evolution Of Polygenic Pesticide Resistance, C. V. Haridas, Brigitte Tenhumberg

School of Biological Sciences: Faculty Publications

Widespread use of pesticides has resulted in the evolution of resistance in many insect pests worldwide, limiting their use in pest control. Effective pest and resistance management practices require understanding of the genetics of resistance and the life history of the pest. Most models for pesticide resistance assume that resistance is monogenic, conferred by a single gene. However, resistance could evolve as a polygenic quantitative trait resulting from the action of several genes, especially when pesticide dose is low. Further, fitness of the pest could be density dependent and might depend upon abiotic factors such as temperature. It is not …


Generation Of An Attenuated, Cross-Protective Pepino Mosaic Virus Variant Through Alignment-Guided Mutagenesis Of The Viral Capsid Protein, Godwill M. Chewachong, Sally A. Miller, Joshua J. Blakeslee, David M. Francis, Thomas Jack Morris, Feng Qu Jan 2015

Generation Of An Attenuated, Cross-Protective Pepino Mosaic Virus Variant Through Alignment-Guided Mutagenesis Of The Viral Capsid Protein, Godwill M. Chewachong, Sally A. Miller, Joshua J. Blakeslee, David M. Francis, Thomas Jack Morris, Feng Qu

School of Biological Sciences: Faculty Publications

Mild variants of many viruses are able to protect infected plants from subsequent invasion by more severe variants of the same viruses through a process known as cross-protection. In the past, the cross-protective viral variants were commonly derived from mild field isolates that were sometimes genetically heterogeneous, providing variable levels of crossprotection. Here, we report a novel approach to rapidly generate crossprotective variants of the tomato-infecting Pepino mosaic virus (PepMV) independently of the availability of mild field isolates. Our approach sought to attenuate PepMV by mutating less conserved amino acid residues of the abundantly produced capsid protein (CP). These less-conserved …


Estimating The Frequency Of Cry1f Resistance In Field Populations Of The European Corn Borer (Lepidoptera: Crambidae), Blair D. Siegfried, Murugesan Rangasamy, Haichuan Wang, Terence A. Spencer, Chirakkal V. Haridas, Brigitte Tenhumberg, Douglas V. Sumerford, Nicholas P. Storer Jan 2014

Estimating The Frequency Of Cry1f Resistance In Field Populations Of The European Corn Borer (Lepidoptera: Crambidae), Blair D. Siegfried, Murugesan Rangasamy, Haichuan Wang, Terence A. Spencer, Chirakkal V. Haridas, Brigitte Tenhumberg, Douglas V. Sumerford, Nicholas P. Storer

School of Biological Sciences: Faculty Publications

Background: Transgenic corn hybrids that express toxins from Bacillus thuringiensis (Bt) have suppressed European corn borer populations and reduced the pest status of this insect throughout much of the US corn belt. A major assumption of the high-dose/refuge strategy proposed for insect resistance management and Bt corn is that the frequency of resistance alleles is low so that resistant pests surviving exposure to Bt corn will be rare. Results: The frequency of resistance to the Cry1F Bt toxin was estimated using two different screening tools and compared with annual susceptibility monitoring based on diagnostic bioassays and LC50 …


Origin And Evolution Of Defective Interfering Rnas Of Tomato Bushy Stunt Virus, David A. Knorr, Thomas Jack Morris Jan 1991

Origin And Evolution Of Defective Interfering Rnas Of Tomato Bushy Stunt Virus, David A. Knorr, Thomas Jack Morris

School of Biological Sciences: Faculty Publications

Viruses with defective genomes have been identified in association with virtually every major family of viruses and have been widely utilized as tools for investigating virus functions in animal cell culture systems (Perrault, 1981). It is generally thought that defective interfering viruses (DIs) arise through deletion, rearrangement, or recombination of a competent viral genome. DIs tack the ability for independent existence relying on their parental helper viruses to supply factors required for replication, maturation, and/or encapsidation (Huang and Baltimore, 1977). The interference attributed to DIs is thought to result from competition with the helper virus for factors required in trans …


Can Genetically Engineered Crops Become Weeds?, Kathleen H. Keeler Nov 1989

Can Genetically Engineered Crops Become Weeds?, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

There are significant differences if the distribution of weedy characteristics among weeds, normal plants, and crops. The world’s most serious weeds possess on the average 10 or 11 of these characters, a random collection of British plants have an average seven of the traits, and crop plants only five. For the average crop to become as “weedy” as the average weed, it would need to acquire five weedy traits. Even using the unlikely assumption that those traits are single loci in which a dominant mutation would provide the weedy character, this would require the simultaneous acquisition of five gene substitutions. …


Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch Dec 1984

Vegetation Patterns In Relation To Topography And Edaphic Variation Nebraska Sandhills Prairie, P. W. Barnes, A. T. Harrison, S. P. Heinisch

School of Biological Sciences: Faculty Publications

Detailed studies on soil texture and moisture retention indicate a close association between edaphic features and the distribution and composition of plant communities along topographic gradients at Arapaho Prairie, a typical, semi-arid Nebraska Sandhills prairie. The vegetation characteristics of three major habitat types (ridge, slope, and valley) and several minor subtypes (swale, stable ridge, and eroding ridge) are recognized and quantitatively described. Texture analysis indicates that the soils of dune slopes and ridges are largely azonal and are very coarse with substantially lower fine fractions (silt-clay ~ 13-15%) than soils of the more lowland swale and valley sites where surfact …