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Full-Text Articles in Organisms

Fungal Endophytes In A Seed-Free Host: New Species That Demonstrate Unique Community Dynamics, Brett Steven Younginger May 2018

Fungal Endophytes In A Seed-Free Host: New Species That Demonstrate Unique Community Dynamics, Brett Steven Younginger

Dissertations and Theses

Fungal endophytes are highly diverse, cryptic plant endosymbionts that form asymptomatic infections within host tissue. They represent a large fraction of the millions of undescribed fungal taxa on our planet with some demonstrating mutualistic benefits to their hosts including herbivore and pathogen defense and abiotic stress tolerance. Other endophytes are latent saprotrophs or pathogens, awaiting host plant senescence to begin alternative stages of their life cycles. Most, however, are likely plant commensals with no observable benefits to their hosts while under study. Yet, when considering the context-dependence that may determine plant resistance to pathogen attack, the consortium of endophytes present …


Surviving Catastrophe: Resource Allocation And Plant Interactions Among The Mosses Of Mount St. Helens Volcano, Trevor David Williams Dec 2016

Surviving Catastrophe: Resource Allocation And Plant Interactions Among The Mosses Of Mount St. Helens Volcano, Trevor David Williams

Dissertations and Theses

Mosses are some of the first colonizers to disturbed sites, yet their roles in early plant community structuring are not well understood. The primary succession zones of volcanoes provide opportunities to conduct natural experiments into how mosses contribute to early plant community formation, as well as how the unique environments found in such zones affect plant traits, particularly those associated with stress tolerance. Though plant community changes have been well-documented since Mount St. Helens (MSH) volcano erupted in 1980, the volcano's moss assemblages, their influence on other plants, and their potential roles in chemical-mediated competition and biogeochemical cycling have garnered …


Investigating The Origin And Functions Of A Novel Small Rna In Escherichia Coli, Fenil Rashmin Kacharia Jun 2016

Investigating The Origin And Functions Of A Novel Small Rna In Escherichia Coli, Fenil Rashmin Kacharia

Dissertations and Theses

Non-coding small RNAs (sRNAs) regulate various cellular processes in bacteria. They bind to a chaperone protein Hfq for stability and regulate gene expression by base-pairing with target mRNAs. Although the importance of sRNAs in bacteria has been well established, the mode of origination of novel sRNA genes is still elusive, mainly because the rapid rate of evolution of sRNAs obscures their original sources. To overcome this impediment, we identified a recently formed sRNA (EcsR2) in E. coli, and show that it evolved from a degraded bacteriophage gene. Our analyses also revealed that young sRNAs such as EcsR2 are expressed …


Sex-Specific Fungal Communities Of The Dioicous Moss Ceratodon Purpureus, Mehmet Ali Balkan Jan 2016

Sex-Specific Fungal Communities Of The Dioicous Moss Ceratodon Purpureus, Mehmet Ali Balkan

Dissertations and Theses

Mosses display a number of hallmark life history traits that influence their ecology at the population and community level. The long lived separation of sexes observed in the haploid gametophyte (dioicy) is one such feature of particular importance, as it is observed in the majority of bryophytes and creates intraspecific specialization of male and female individuals.

The prevalence of sexually dimorphic mosses raises the possibility of sex-specific interactions with fungi as observed in some vascular plants. Here I investigated how moss sex shapes fungal communities associated with gametophytic tissues of the ubiquitous moss, Ceratodon purpureus. Using greenhouse populations of …


Determination Of Homology Between The Arsenic Resistance Plasmids R45 And R773 In Escherichia Coli, Joshua T. Clark May 1988

Determination Of Homology Between The Arsenic Resistance Plasmids R45 And R773 In Escherichia Coli, Joshua T. Clark

Dissertations and Theses

The resistance transfer factor R45 from Escherichia coli confers inducible arsenate and arsenite resistance in that bacterium. The genes for these resistances were cloned into the EcoR1 - Sph1 multiple cloning site of PGEM3 Blue vector (Promega) to produce a 4.9 kilobase plasmid, pJC1. This recombinant plasmid, pJC1, conferred IPTG induced resistance to arsenite and arsenate. In addition, pJCl was tested for homology with the E. coli plasmid R773, which encodes for arsenic resistance in that bacterium as well.

Through DNA-DNA hybridization the arsenic resistance determinants of R45 and R773 were compared. Under stringent hybridization conditions, R45 demonstrated DNA sequence …


The Absence Of Extrachromosomal Dna In Methanogenic Bacteria, Nancy Ann Kurkinen Jan 1983

The Absence Of Extrachromosomal Dna In Methanogenic Bacteria, Nancy Ann Kurkinen

Dissertations and Theses

Five species of methanogenic bacteria were analyzed for the presence of plasmid DNA. Several procedures for the detection and isolation of covalently closed circular plasmid DNA were modified for use with the methanogens.