Protein kinases are an abundant class of enzymes which play important roles in numerous signal transduction systems. Arabidopsis TOUSLED kinase is a serine/threonine kinase which is essential for cell-cell communication within the shoot meristem. TOUSLED is encoded by a single gene in Arabidopsis. Recessive mutants in this gene show mild vegetative defects and severe floral abnormalities including a random reduction in the number of floral organs produced and defects in the formation of the gynoecium. This thesis describes the cloning and characterization of three maize genes with homology to TOUSLED. These genes are known as the TOUSLED-LIKE KINASE (TLK) genes. Partial genomic and cDNA clones of the maize TLK genes have been sequenced and analyzed. These genes show remarkable similarity to each other and to TOUSLED over the region corresponding to the TOUSLED catalytic domain. The TLK genes fall into two distinct classes on the basis of nucleotide and amino acid sequence. Both classes appear to be expressed throughout the plant. In addition, database searches reveal that TOUSLED-like genes are present in a diverse array of other eukaryotes, indicating that the TLK genes are members of a widespread, evolutionarily conserved class. Two approaches have been taken to find mutants in the TLK genes. This thesis describes the tassel-less1 (tls1) mutant, a possible mutant in one of the TLK genes. The tls1 mutation maps to the same chromosomal location as one of the TLK genes, and may represent a lesion in this TLK gene. Characterization of the t1s1 mutant reveals that disruption of the TLS1 gene results in variable, progressive vegetative defects and severe reduction of the reproductive structures. The tls1 phenotype is consistent with the hypothesis that TLS1 plays a role in regulating meristem activity. In addition, TLK sequences have been used in a reverse genetics screen to isolate families which contain Mutator transposable element insertions into the TLK genes. These families are currently being analyzed for phenotype and allelism to tls1. / Graduation date: 1997

Thesis (Ph. D.)--Ohio State University, 2006. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--University of Chicago, Dept. of Neurobiology, Pharmacology and Physiology, June 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph.D.)--Ohio University, August, 2009. / Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 89-107)

Thesis (Ph.D.)--Ohio University, August, 2009. / Title from PDF t.p. Release of full electronic text on OhioLINK has been delayed until September 1, 2012. Includes bibliographical references (leaves 89-107)

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references (leaves 79-99).

Thesis (Ph. D.)--Rutgers University, 2009. / "Graduate Program in Pharmaceutical Science." Includes bibliographical references (p. 138-153).

Thesis (Ph. D.)--University of Chicago, Committee on Virology, 2001. / Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Hong Kong, 2010. / Includes bibliographical references (leaves 182-198). Also available in print.

Dishevelled (Dvl) proteins are key transducers of Wnt signaling and are encoded by members of a multi-gene family in vertebrates. We report here divergent, tissue-specific expression patterns for all three Dvl genes in Xenopus embryos, which contrast dramatically with their expression in the mouse. Moreover, we find that the expression patterns of Dvl genes in the chick diverge significantly from those of Xenopus. In addition, in hemichordates, one of the outgroups to chordates, we find that the one Dvl gene is dynamically expressed in a tissue-specific manner. Using knockdowns, we find that Dvl1 and Dvl2 are required for early neural crest specification and for somite segmentation. Most strikingly, we report a novel role for Dvl3 in the maintenance of differentiated muscle and the development of the Xenopus sclerotome. Together, these data demonstrate that that the expression patterns and developmental functions of specific Dvl genes have diverged significantly during chordate evolution. The planar cell polarity (PCP) signaling pathway is essential for embryonic development because it governs diverse cellular behaviors, and the "core PCP" proteins, such as Dishevelled and Frizzled, have been extensively characterized. By contrast, the "PCP effector" proteins, such as Intu and Fuz, remain largely unstudied. These proteins are essential for PCP signaling, but they have never been investigated in a mammal and their cell biological activities remain entirely unknown. We report here that Fuz mutant mice display neural tube defects, polydactyly, and skeletal dysmorphologies that stem from defective ciliogenesis. Using bioinformatics and imaging of an in vivo mucociliary epithelium, we establish a central role for Fuz in membrane trafficking, showing that Fuz is essential for apical trafficking of ciliogenesis factors in ciliated cells and also for exocytosis in secretory cells. We identify a novel, Rab-related small GTPase as an interaction partner for Fuz, and this GTPase also is essential for ciliogenesis and secretion. These results are significant because they provide novel insights into the mechanisms by which developmental regulatory systems like PCP signaling interface with fundamental cellular systems such as the vesicle trafficking machinery. / text