Life Sciences Commons^™

Ultrastructural Changes During Pollen Wall Development And Germination In Arabidopsis Thalaiana, Katrina Olsen

Theses and Dissertations

The Arabidopsis thaliana meiotic mutant 6491 has been identified as displaying temperature sensitive male reduced- fertility. It has been determined that callose wall formation is defective, both in temporal and structural areas. There is irregular rippling in the plasma membrane and aberrant formation of the exine portion of the pollen wall. A developmental study using brightfield, epifluorescence, and transmission electron microscopy of the early stages of wall formation in 6491 has been completed, along with a similar study of Arabidopsis thaliana (L.) heynh, ecotype Wassilewskija (WS). Due to the temperature-sensitive nature of the mutant line, a further study of both …

Consequences Of Loss Of An Abundant Pollinator: An Experimental Study, Allysa Hallett

Theses and Dissertations

Pollinator populations are declining worldwide, and this may lower the quantity and quality of pollination services. Since pollinators often compete for floral resources, loss of an abundant pollinator species may release others from competition and potentially alter floral visitation rates. We explored how the removal of a frequent pollinator, bumble bees, influenced pollination success of whorled milkweed (Asclepias verticillata). In three small and three large populations we quantified pollinator visitation rates and pollination success for control plots and for plots where bumble bees were experimentally excluded. We found that exclusion of bumble bees did not reduce A. verticillata pollination success. …

Deciphering The Multi-Tiered Regulatory Network That Links Cyclic-Di-Gmp Signaling To Virulence And Bacterial Behaviors, Xiaochen Yuan

Theses and Dissertations

Bis-(3’-5’)-cyclic dimeric guanosine monophosphate (c-di-GMP) is a bacterial second messenger that regulates multiple cellular behaviors in most major bacterial phyla. C-di-GMP signaling in bacterial often includes enzymes that are responsible for the synthesis and degradation of c-di-GMP, effector proteins or molecules that bind c-di-GMP, and targets that interact with effectors. However, little is known about the specificity of c-di-GMP signaling in controlling virulence and bacterial behaviors. In this work, we have investigated the c-di-GMP signaling network using the model plant pathogen Dickeya dadantii 3937.

In Chapter 2, we characterized two PilZ domain proteins that regulate biofilm formation, swimming motility, Type …