Genetics and Genomics Commons^™

Predators Catalyze An Increase In Chloroviruses By Foraging On The Symbiotic Hosts Of Zoochlorellae, John Delong, Zeina Al-Ameeli, Garry A. Duncan, James L. Van Etten, David D. Dunigan Ph. D.

James Van Etten Publications

Virus population growth depends on contacts between viruses and their hosts. It is often unclear how sufficient contacts are made between viruses and their specific hosts to generate spikes in viral abundance. Here, we show that copepods, acting as predators, can bring aquatic viruses and their algal hosts into contact. Specifically, predation of the protist Paramecium bursaria by copepods resulted in a >100-fold increase in the number of chloroviruses in 1 d. Copepod predation can be seen as an ecological “catalyst” by increasing contacts between chloroviruses and their hosts, zoochlorellae (endosymbiotic algae that live within paramecia), thereby facilitating viral population …

Climate Change And The Integrity Of Science, Peter H. Gleick, James L. Van Etten, Members Of The U.S. National Academy Of Sciences

James Van Etten Publications

We are deeply disturbed by the recent escalation of political assaults on scientists in general and on climate scientists in particular. All citizens should understand some basic scientific facts. There is always some uncertainty associated with scientific conclusions; science never absolutely proves anything. When someone says that society should wait until scientists are absolutely certain before taking any action, it is the same as saying society should never take action. For a problem as potentially catastrophic as climate change, taking no action poses a dangerous risk for our planet.

Scientific conclusions derive from an understanding of basic laws supported by …

Two Complete Mitochondrial Genomes From Praticolella Mexicana Perez, 2011 (Polygyridae) And Gene Order Evolution In Helicoidea (Mollusca, Gastropoda), Russell L. Minton, Marco A. Martinez Cruz, Mark L. Farman, Kathryn E. Perez

Plant Pathology Faculty Publications

Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of P. mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome …

Identification And Characterization Of The Isoflavonoid-Specific Prenyltransferase Gene Family To Prevent Stem And Root Rot In Soybean, Arjun Sukumaran

Electronic Thesis and Dissertation Repository

Soybean is one of the most predominantly grown legumes worldwide, however, one deterrent to maximizing its yield is the pathogen, Phytophthora sojae, which causes stem and root rot disease. Many strategies have been implemented to combat this pathogen such as use of pesticides and certain agricultural practices. However, these have been largely ineffective in completely preventing P. sojae infection. An alternative strategy would be to improve the innate resistance of soybean by promoting increased glyceollin production. Glyceollins are soybean-specific antimicrobial agents which are derived from the isoflavonoid branch of the general phenylpropanoid pathway. Soybeans produce 3 forms of glyceollin: …

Chromosome-End Knockoff Strategy To Reshape Alkaloid Profiles Of A Fungal Endophyte, Simona Florea, Timothy D. Phillips, Daniel G. Panaccione, Mark L. Farman, Christopher L. Schardl

Plant Pathology Faculty Publications

Molecular genetic techniques to precisely eliminate genes in asexual filamentous fungi require the introduction of a marker gene into the target genome. We developed a novel strategy to eliminate genes or gene clusters located in subterminal regions of chromosomes, and then eliminate the marker gene and vector backbone used in the transformation procedure. Because many toxin gene clusters are subterminal, this method is particularly suited to generating nontoxic fungal strains. We tested this technique on Epichloë coenophiala, a seed-transmissible symbiotic fungus (endophyte) of the important forage grass, tall fescue (Lolium arundinaceum). The endophyte is necessary for maximal …

Comparative Genomics, Transcriptomics, And Physiology Distinguish Symbiotic From Free-Living Chlorella Strains, Cristian F. Quispe, Olivia Sonderman, Maya Khasin, Wayne R. Riekhof, James L. Van Etten, Kenneth Nickerson

Kenneth Nickerson Papers

Most animal–microbe symbiotic interactions must be advantageous to the host and provide nutritional benefits to the endosymbiont. When the host provides nutrients, it can gain the capacity to control the interaction, promote self-growth, and increase its fitness. Chlorella-like green algae engage in symbiotic relationships with certain protozoans, a partnership that significantly impacts the physiology of both organisms. Consequently, it is often challenging to grow axenic Chlorella cultures after isolation from the host because they are nutrient fastidious and often susceptible to virus infection. We hypothesize that the establishment of a symbiotic relationship resulted in natural selection for nutritional and metabolic …

Description Of Mesocriconema Ericaceum N. Sp. (Nematoda: Criconematidae) And Notes On Other Nematode Species Discovered In An Ericaceous Heath Bald Community In Great Smoky Mountains National Park, Usa, Thomas O. Powers, Peter Mullin, Rebecca Higgins, Timothy Harris, Kirsten S. Powers

Department of Plant Pathology: Faculty Publications

A new species of Mesocriconema and a unique assemblage of plant-parasitic nematodes was discovered in a heath bald atop Brushy Mountain in Great Smoky Mountains National Park. Mesocriconema ericaceum n. sp., a species with males, superficially resembles M. xenoplax. DNA barcoding with the mitochondrial COI gene provided evidence of the new species as a distinct lineage. SEM revealed significant variability in arrangement of labial submedian lobes, plates, and anterior and posterior annuli. Three other nematodes in the family Criconematidae were characterized from the heath bald. Ogma seymouri, when analyzed by statistical parsimony, established connections with isolates from north-eastern Atlantic …

Three-Year Survey Of Abundance, Prevalence And Genetic Diversity Of Chlorovirus Populations In A Small Urban Lake, Cristian F. Quispe, Olivia Sonderman, Anya Seng, Brenna Rasmussen, Garrett Weber, Claire Mueller, David Dunigan, James L. Van Etten

James Van Etten Publications

Inland water environments cover about 2.5 percent of our planet and harbor huge numbers of known and still unknown microorganisms. In this report, we examined water samples for the abundance, prevalence, and genetic diversity of a group of infectious viruses (chloroviruses) that infect symbiotic chlorella-like green algae. Samples were collected on a weekly basis for a period of 24 to 36 months from a recreational freshwater lake in Lincoln, Nebraska, and assayed for infectious viruses by plaque assay. The numbers of infectious virus particles were both host- and site-dependent. The consistent fluctuations in numbers of viruses suggest their impact as …

A Colletotrichum Graminicola Mutant Deficient In The Establishment Of Biotrophy Reveals Early Transcriptional Events In The Maize Anthracnose Disease Interaction, Maria F. Torres, Noushin Ghaffari, Ester A. S. Buiate, Neil Moore, Scott Schwartz, Charles D. Johnson, Lisa J. Vaillancourt

Plant Pathology Faculty Publications

Background: Colletotrichum graminicola is a hemibiotrophic fungal pathogen that causes maize anthracnose disease. It progresses through three recognizable phases of pathogenic development in planta: melanized appressoria on the host surface prior to penetration; biotrophy, characterized by intracellular colonization of living host cells; and necrotrophy, characterized by host cell death and symptom development. A “Mixed Effects” Generalized Linear Model (GLM) was developed and applied to an existing Illumina transcriptome dataset, substantially increasing the statistical power of the analysis of C. graminicola gene expression during infection and colonization. Additionally, the in planta transcriptome of the wild-type was compared with that of …

Inheritance, Differential Expression, And Candidate Gene Analyses For Avr2 In Phytophthora Sojae, Chelsea S. Ishmael

Electronic Thesis and Dissertation Repository

Phytophthora sojae is an oomycete responsible for seed, root and stem rot of soybean plants. Managing this disease relies on growing soybean cultivars with race-specific resistance (Rps) genes that deliver complete host immunity in the presence of corresponding pathogen avirulence (Avr) effector proteins. The aims of this study were to characterize virulence towards Rps2 among different P. sojae strains, track the inheritance of this trait, and attempt to identify an Avr2 gene. Fifteen P. sojae strains were tested for virulence towards Rps2 and crosses were performed between selected virulent and avirulent strains to follow the inheritance of virulence. …

Chloroviruses N-Linked Glycans Share A New Type Of Conserved Core Architecture Unprecedented In Any Form Of Life / [Published As] N-Linked Glycans Of Chloroviruses Sharing A Core Architecture Without Precedent, Cristina De Castro, Immacolata Speciale, Garry Duncan, David Dunigan, Irina Agarkova, Rosa Lanzetta, Luisa Sturiale, Angelo Palmigiano, Domenico Garozzo, Antonio Molinaro, Michela Tonetti, James L. Van Etten

James Van Etten Publications

N-glycosylation is a fundamental modification of proteins that exists in the three domains of life and in some viruses, including the chloroviruses, for which a new type of core N-glycan is described. This N-glycan core structure common to all chloroviruses is a pentasaccharide with a β-glucose linked to an asparagine residue that is not located in the typical sequon N-X-T/S. The glucose is linked to a terminal xylose unit and a hyperbranched fucose, in turn substituted with a terminal galactose and a second xylose residue. The third position of the fucose unit is always linked to a rhamnose, which is …

Virus–Host Interactions: Insights From The Replication Cycle Of The Large Paramecium Bursaria Chlorella Virus, Elad Milrot, Yael Mutsafi, Yael Fridmann-Sirkis, Eyal Shimoni, Katya Rechav, James Gurnon, James L. Van Etten, Abraham Minsky

James Van Etten Publications

The increasing interest in cytoplasmic factories generated by eukaryotic-infecting viruses stems from the realization that these highly ordered assemblies may contribute fundamental novel insights to the functional significance of order in cellular biology. Here, we report the formation process and structural features of the cytoplasmic factories of the large dsDNA virus Paramecium bursaria chlorella virus 1 (PBCV-1). By combining diverse imaging techniques, including scanning transmission electron microscopy tomography and focused ion beam technologies, we show that the architecture and mode of formation of PBCV-1 factories are significantly different from those generated by their evolutionary relatives Vaccinia and Mimivirus. Specifically, PBCV-1 …