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Dephosphorylation Of Mpk6 And Mpk3 By Phosphatases Modulates Responses To Herbivory In Arabidopsis, Claire Teresa Hann

Theses and Dissertations

As sessile organisms, plants rely on extracellular signals and chemical responses to defend against stressors. Extracellular stress signals inducing defense responses originate both from biotic or abiotic threats, and from products of tissue damage or hormones. In defense against herbivores, essential responses include rapid generation of jasmonic acid (JA) at the wound site, followed by the global expression of genes that impede digestion and growth. Early defense gene expression amplifies JA production, while later JA-responsive gene expression causes the accumulation of defense products. MAP kinase (MAPK) pathways play a central role in mediating the perception of self, non-self, and hormonal …

Modulation Of Eif2Α Signaling And The Integrated Stress Response By Targeted Therapeutic Attenuation Of Pkr Activity Contributes To Protection Of Dyt-Prkra Cells From Apoptosis, Kenneth L. Frederick

Theses and Dissertations

Luteolin is a natural flavonoid present in vegetables, fruits, and medicinal herbs that possesses anti-oxidative, anti-cancer, and anti-inflammatory properties. In this study, we investigated the effect of luteolin on the integrated stress response (ISR), which is an evolutionarily conserved intracellular signaling network essential for adapting to environmental stresses to maintain healthy cells. Dysregulated ISR is involved in the etiology of many human diseases including the movement disorder DYT-PRKRA which is caused by mutations in the PRKRA gene. PRKRA encodes for PACT, the protein activator of interferon-induced, double-stranded RNA (dsRNA)-activated protein kinase PKR.PACT-mediated PKR activation regulates the …

The Effects Of Variations In Light And Nutrient Availability On Phytoplankton And Zooplankton, Jake Anthony Swanson

Theses and Dissertations

Aquatic ecosystems experience a wide range of variation in resource availability; two of the resources that are most essential to phytoplankton and zooplankton are light and nutrients. Light can vary in both its color and intensity; these variations can directly impact phytoplankton by altering the amount and color of light available for photosynthesis. Nutrient variability, particularly increases in nutrient levels, also alter phytoplankton communities by favoring the growth of certain taxa such as cyanobacteria.

To understand whether phytoplankton respond differently to changes in light availability I investigated whether the diversification of cryptophytes, phytoplankton with diverse light-capturing pigments, showed evidence of …

Diversity, Function, And Phenotypic Plasticity Of Cryptophyte Phycobiliproteins, Kristiaän Merritt

Theses and Dissertations

Cryptophytes are a group of unicellular eukaryotic algae that can be found in a wide range of underwater habitats. Part of their ecological success can be attributed to their diverse array of cryptophyte phycobiliproteins (Cr-PBPs), a pigment class that captures wavelengths of light that are poorly absorbed by chlorophylls. Cryptophytes gained photosynthesis via secondary endosymbiosis in which their ancestor engulfed a red algal endosymbiont. Following endosymbiosis, they deconstructed the red algal photosynthetic machinery to form the Cr-PBP. Since then, the Cr-PBPs have diversified into at least 9 spectrally distinct forms. I investigated the diversity of Cr-PBP light absorption across 76 …

Genetic Mechanisms Underlying Maladaptation In Specialized Species Interactions, Nitin Ravikanthachari

Theses and Dissertations

Adaptation has been used as the framework to understand the power of natural selection in structuring biodiversity and driving biological interactions. However, recent examples have indicated that many organisms are maladapted to their local conditions. Maladaptation can result from various causes including rapid environmental change, novel environments, interplay of evolutionary forces (viz: gene flow-selection balance) and anthropogenic disturbance.

To dissect the genetic mechanisms underlying maladaptation, I used the interaction between Pieris macdunnoughii (Remington) (Lepidoptera: Pieridae) which lays eggs on an invasive mustard Thlaspi arvense (L.) (Brassicaceae), which is lethal to the larvae.

First, local adaptation to avoid laying eggs on …