Search results
(1 - 3 of 3)
- Title
- UNDERSTANDING THE ROLES OF INTERKINGDOM MICROBIAL INTERACTIONS, MICROBIAL TRAITS, AND HOST FACTORS IN THE ASSEMBLY OF PLANT MICROBIOMES
- Creator
- Liber, Julian Aaron
- Date
- 2021
- Collection
- Electronic Theses & Dissertations
- Description
-
The community of organisms that associate with plants are vital to both the survival of the host plant but also the diseases which may kill it. The processes by which this community, called the microbiome, assemble and function can contribute to the traits of the host, including plants that humans rely on for food, resources, and ecosystems services. This thesis focuses on understanding the assembly of microbiomes at the scale of microbe-microbe interactions and traits of individual microbes,...
Show moreThe community of organisms that associate with plants are vital to both the survival of the host plant but also the diseases which may kill it. The processes by which this community, called the microbiome, assemble and function can contribute to the traits of the host, including plants that humans rely on for food, resources, and ecosystems services. This thesis focuses on understanding the assembly of microbiomes at the scale of microbe-microbe interactions and traits of individual microbes, as well as how characters of the host may change this process. I first address this by examining the in vitro and in planta interactions within small synthetic communities of root-inhabiting bacteria and fungi and with the plant host and viral disease of the host. While intermicrobial interactions in vitro were not predictive of in planta interactions, adding host disease or additional organisms to the system altered the assembly process. I then show the development and applications of the CONSTAX2 classifier, a taxonomic assignment tool for metabarcoding studies, which offers improved accuracy and ease of use for conducting metabarcoding studies exploring the diversity and structure of microbial communities. Last, I present a study testing which factors affected the composition of forest fungal communities to understand the ecology of litter-inhabiting fungi and improve methodologies for sampling leaf-associated fungal communities. The factors affecting the assembly of plant microbiomes are complex and varied but connecting individual interactions to community composition and ultimately function may improve our abilities to predict and manage microbiome processes.
Show less
- Title
- It's both who you are and where you're from : relating vocational interests and socioeconomic status to bias in biodata and SJTs
- Creator
- Prasad, Joshua
- Date
- 2017
- Collection
- Electronic Theses & Dissertations
- Description
-
"Differences in responding to biodata and situational judgement tests (SJTs) based on gender and racial minority group status were evaluated. It was hypothesized that vocational interests and socioeconomic status (SES) could be used to help characterize the differences in experience between groups (e.g. Cottrell, Newman, Roisman, 2015; Nye, Su, Rounds, & Drasgow, 2012). As a result, interests and SES may help explain differences in both the constructs assessed by biodata and SJTs as well as...
Show more"Differences in responding to biodata and situational judgement tests (SJTs) based on gender and racial minority group status were evaluated. It was hypothesized that vocational interests and socioeconomic status (SES) could be used to help characterize the differences in experience between groups (e.g. Cottrell, Newman, Roisman, 2015; Nye, Su, Rounds, & Drasgow, 2012). As a result, interests and SES may help explain differences in both the constructs assessed by biodata and SJTs as well as differences in item functioning (DIF; Drasgow, 1987). Hypotheses were evaluated using multiple-indicator multiple-cause models to simultaneously model latent constructs and item responses (MIMIC; Muthén, 1989). Findings indicate that interests helped explain differences across gender in both the constructs assessed as well as DIF. Interests explained few differences based on minority group status and SES did not seem to meaningfully explain differences in either of the demographic group comparisons. Many items still exhibited DIF as a function of gender or minority group status after accounting for vocational interests and SES, suggesting that further work is needed to identify additional substantive explanations of DIF. Overall, the present work constitutes a thorough examination of differential functioning in noncognitive assessments and establishes a meaningful relationship between the noncognitive constructs assessed here and vocational interests."--Page ii.
Show less
- Title
- Analysis of host transcriptome response to porcine reproductive and respiratory syndrome virus infection
- Creator
- Arceo, Maria Eugenia
- Date
- 2012
- Collection
- Electronic Theses & Dissertations
- Description
-
Porcine Reproductive and Respiratory Syndrome (PRRS) has been affecting commercial populations of pigs in the US for more than 20 years. We evaluated differences in gene expression in pigs from the PRRS Host Genetics Consortium initiative showing a range of responses to PRRS virus infection. Pigs were allocated into four phenotypic groups according to their serum viral level and weight gain. We obtained RNA at several days post-infection and hybridized it to the 20K 70 mer-oligonucleotide...
Show morePorcine Reproductive and Respiratory Syndrome (PRRS) has been affecting commercial populations of pigs in the US for more than 20 years. We evaluated differences in gene expression in pigs from the PRRS Host Genetics Consortium initiative showing a range of responses to PRRS virus infection. Pigs were allocated into four phenotypic groups according to their serum viral level and weight gain. We obtained RNA at several days post-infection and hybridized it to the 20K 70 mer-oligonucleotide Pigoligoarray. We initially used plasmode datasets to select an optimal procedure for analyzing these data. We showed that the random array effects model with the moderated F statistic and significance thresholds obtained by permutation provided the most powerful analysis procedure. We then addressed global differential gene expression between phenotypic groups. We identified cell death as a biological function significantly associated with several gene networks enriched for differentially expressed genes. We found the genes interferon-alpha 1, major histocompatibility complex, class II, DR alpha, and major histocompatibility complex, class II, DQ alpha 1 differentially expressed between phenotypic groups. Finally, we used this study as pilot data to inform the design of future time-course transcriptional profiling experiments. We concluded the best scenario for investigation of early response to PRRSV infection consists of sampling at 4 and 7 days post infection using approximately 30 pigs per phenotypic group.
Show less