Pseudomonas syringae is a pathogen of numerous plant species, including several economically important crops. P. syringae pv. syringae B728a is a resident on leaves of common bean, where it utilizes several well-studied virulence factors, including secreted effectors and toxins, to develop a pathogenic interaction with its host. The B728a genome was recently sequenced, revealing the presence of 1,297 genes with unknown function. This dissertation demonstrates that a 29.9-kb cluster of genes in the B728a genome encodes a novel secretion pathway, the type VI secretion system (T6SS), that functions to deliver at least one protein outside of the bacterial cell. Western blot analyses show that this secretion is dependent on clpV, a gene that likely encodes an AAA+ ATPase, and is repressed by retS, which apparently encodes a hybrid sensor kinase. RetS and a similar protein called LadS are shown to collectively modulate several virulence-related activities in addition to the T6SS. Plate assays demonstrate that RetS negatively controls mucoidy, while LadS negatively regulates swarming motility. A mutation in retS affects B728a population levels on the surface of bean leaves. A model for the LadS and RetS control of B728a virulence activities is proposed, and possible roles for the B728a T6SS are addressed.

This study analyzes the evolution and impact of Icelandic mythology surrounding the Yule Lads and their family, with a specific focus on how these stories affected their beliefs and behaviors from the early 1900s to the present. These folklore figures include the thirteen Yule Lads, their mother Grýla, their father Leppalúdi, and their cat. Icelandic texts from the 13th century describe these characters as terrifying, with Grýla renowned as a cannibalistic figure in Icelandic history. The study intends to explore how stories and anxieties about the Yule Lads have evolved throughout time. The main question is how traditions and myths involving Yule Lads and Grýla have changed over the past century. What roles did these personalities play in early twentieth-century Icelandic Christmas traditions, and what changes have happened since? Additional inquiries investigate the causes of these shifts and their influence on modern Icelandic culture. The study combines historical analysis of folklore collections with present-day interviews to get insight into the cultural importance and history of these stories.