Regulatory Mechanisms of Purinergic Signaling in Plant Growth and Defense

Extracellular ATP (eATP) is a crucial signaling element in both animal physiology and plants. Its role as a purinergic signal for plant growth and defense responses is recognized in the plant biology community. However, a lack of P2K1 receptor interactome and limited methodologies for monitoring eATP responses hindered comprehensive understanding of purinergic signaling mechanisms. This thesis explores eATP's role in plant growth and defense responses, with a focus on P2K1's signaling mechanisms. Following Jewell et al.’s ATP-induced transcriptome, we identified five eATP-responsive genes and studied their expression patterns in response to ATP treatment. The findings suggested the root tip as a critical eATP signaling hub. We investigated the IDR in P2K1's C-terminal tail, revealing its pivotal role in converting eATP sensing into root growth regulation. C-terminal tail deletion caused prolonged eATP signaling, leading to ROS accumulation, and altered cell wall integrity in the root meristem, ceasing root growth due to increased cell death—providing further support for the root tip as a hub for eATP signaling through P2K1. We identified phosphorylation sites in the C-terminal IDR which might regulate P2K1 kinase activity by altering the conformation of P2K1’s C-terminal tail. Last, a P2K1- interactomics study uncovered putative interacting proteins, including CPK28, a negative regulator of P2K1-mediated eATP signaling. CPK28 overexpression alleviated eATP hypersensitivity, promoting plant growth, while CPK28 loss led to stunted growth, like P2K1 overexpression. CPK28 also negatively regulated eATP-induced chlorosis during B. cinerea infection. In conclusion, this thesis illuminates eATP's intricate signaling mechanisms in plants, emphasizing P2K1's crucial role and interactions in integrating eATP-sensing into growth and defense regulation

The preaching of John Newton (1725-1807): a gospel-centric, pastoral homiletic of biblical exposition

This dissertation examines the preaching ministry of John Newton as a model of biblical exposition that was guided by a gospel-centric, pastoral homiletic. Chapter 1 defines the thesis of this dissertation , introduces the subject of this dissertation by surveying the scholarly work that has concentrated on Newton’s life and ministry, and demonstrates the lack of focused study on Newton’s preaching. Chapter 2 is a biographical survey of Newton’s life and ministry. Chapter 3 serves as an introduction to Newton’s preaching by surveying Newton’s sermons and demonstrates that Newton’s preaching should be regarded as expository. Attention is also given to the eighteenth-century historical context in which Newton preached. Chapter 4 argues that Newton’s high view of Scripture served as a foundation of his ministry and preaching. Chapter 5 is a discussion of Newton’s Christ-centered piety with regard to its impact on his life, ministry and preaching. Chapter 6 maintains that Newton’s Christ-centered spirituality is evident in his gospel-centric preaching and the homiletical methods that guided him. Chapter 7 examines Newton’s preaching and his commitment to pastoral ministry. It argues that Newton’s preaching rhetoric was a function of a pastoral homiletic that was deeply concerned with the spiritual welfare of his hearers. The final chapter summarizes the major points of dissertation and reflects on the importance of the use of historical models like Newton for contemporary preaching

Painful Conversions: Reading and Writing Education Reform in Louisiana

In January 2013, the superintendent of a rural Louisiana school system initiated a plan to increase school choice in his district through the implementation of a new virtual magnet school and the conversion of an existing elementary school into a magnet school. Both plans were set into action in April 2013. This study uses performative writing to document the better part of a year spent engaged in this project as a contracted educational consultant. Melding William Blake’s theories of apocalypse and social metonymy with experimental modes of scholarly production as praxis, I theorize education reform as an interactive performance. By exploring themes of documentation, collaboration, and dialogic education, this project identifies the documentation of personal experience in school reform as a temporal mode of generating meaning and offers this mode as a pedagogical model for future scholarship

A histochemical reporter system to study extracellular ATP response in plants

When cells experience acute mechanical distress, they release ATP from their cellular compartment into the surrounding microenvironment. This extracellular ATP (eATP) can then act as a danger signal—signaling cellular damage. In plants, cells adjacent to damage detect rising eATP concentrations through the cell-surface receptor kinase, P2K1. Following eATP perception, P2K1 initiates a signaling cascade mobilizing plant defense. Recent transcriptome analysis revealed a profile of eATP-induced genes sharing pathogen- and wound-response hallmarks—consistent with a working model for eATP as a defense-mobilizing danger signal. To build on the transcriptional footprint and broaden our understanding of dynamic eATP signaling responses in plants, we aimed to i) generate a visual toolkit for eATP-inducible marker genes using a β-glucuronidase (GUS) reporter system and ii) evaluate the spatiotemporal response of these genes to eATP in plant tissues. Here, we demonstrate that the promoter activities of five genes, ATPR1, ATPR2, TAT3, WRKY46, and CNGC19, were highly sensitive to eATP in the primary root meristem and elongation zones with maximal responses at 2 h after treatment. These results suggest the primary root tip as a hub to study eATP-signaling activity and provide a proof-of-concept toward using these reporters to further dissect eATP and damage signaling in plants

ProcessJ: A process-oriented programming language

Java is a general purpose object-oriented programming language that has been widely adopted. Because of its high adoption rate and its lineage as a C-style language, its syntax is familiar to many programmers. The downside is that Java is not natively concurrent. Volumes have been written about concurrent programming in Java; however, concurrent programming is difficult to reason about within an object-oriented paradigm and so is difficult to get right. occam -π is a general purpose process-oriented programming language. Concurrency is part of the theoretical underpinnings of the language. Concurrency is simple to reason about within an occam -π application because there is never any shared state; also occam -π is based on a process calculus, with algebraic laws for composing processes. It has well-defined semantics regarding how processes interact. The downside is that the syntax is foreign and even archaic to programmers who are used to the Java syntax. This thesis presents a new language, ProcessJ, which is a general purpose, process-oriented programming language meant to bridge the gap between Java and occam -π. ProcessJ does this by combining the familiar syntax of Java with the process semantics of occam -π. This allows for a familiar-looking language that is easy to reason about in concurrent programs. This thesis describes the ProcessJ language, as well as the implementation of a compiler that translates ProcessJ source code to Java with Java Communicating Sequential Processes (JCSP), a library that provides CSP-style communication primitives

Communicating Process Architectures

Abstract. In this paper we consider a refinement of the concept of mobile processes in a process oriented language. More specifically, we investigate the possibility of allowing resumption of suspended mobile processes with different interfaces. This is a refinement of the approach taken currently in languages like occam-π. The goal of this research is to implement varying resumption interfaces in ProcessJ, a process oriented language being developed at UNLV

Identification of kaonashi Mutants Showing Abnormal Pollen Exine Structure in Arabidopsis thaliana

Exine, the outermost architecture of pollen walls, protects male gametes from the environment by virtue of its chemical and physical stability. Although much effort has been devoted to revealing the mechanism of exine construction, still little is known about it. To identify the genes involved in exine formation, we screened for Arabidopsis mutants with pollen grains exhibiting abnormal exine structure using scanning electron microscopy. We isolated 12 mutants, kaonashi1 (kns1) to kns12, and classified them into four types. The type 1 mutants showed a collapsed exine structure resembling a mutant of the callose synthase gene, suggesting that the type 1 genes are involved in callose wall synthesis. The type 2 mutant showed remarkably thin exine structure, presumably due to defective primexine thickening. The type 3 mutants showed defective tectum formation, and thus type 3 genes are required for primordial tectum formation or biosynthesis and deposition of sporopollenin. The type 4 mutants showed densely distributed baculae, suggesting type 4 genes determine the position of probacula formation. All identified kns mutants were recessive, suggesting that these KNS genes are expressed in sporophytic cells. Unlike previously known exine-defective mutants, most of the kns mutants showed normal fertility. Map-based cloning revealed that KNS2, one of the type 4 genes, encodes sucrose phosphate synthase. This enzyme might be required for synthesis of primexine or callose wall, which are both important for probacula positioning. Analysis of kns mutants will provide new knowledge to help understand the mechanism of biosynthesis of exine components and the construction of exine architecture

The polygalacturonase gene BcMF2 from Brassica campestris is associated with intine development

Brassica campestris Male Fertility 2 (BcMF2) is a putative polygalacturonase (PG) gene previously isolated from the flower bud of Chinese cabbage (Brassica campestris L. ssp. chinensis Makino, syn. B. rapa ssp. chinensis). This gene was found to be expressed specifically in tapetum and pollen after the tetrad stage of anther development. Antisense RNA technology was used to study the function of BcMF2 in Chinese cabbage. Scanning and transmission electron microscopy revealed that there were deformities in the transgenic mature pollen grains such as abnormal location of germinal furrows. In addition, the homogeneous pectic exintine layer facing the exterior seemed to be overdeveloped and predominantly occupied the intine, thus reversing the normal proportional distribution of the internal endintine layer and the external exintine layer. Since it is a continuation of the intine layer, the pollen tube wall could not grow normally. This resulted in the formation of a balloon-like swelling structure in the pollen tube tip in nearly 80% of the transgenic pollen grains. Premature degradation of tapetum was also found in these transgenic plants, which displayed decreased expression of the BcMF2 gene. BcMF2 might therefore encode a new PG with an important role in pollen wall development, possibly via regulation of pectin's dynamic metabolism

Evolutionary development of the plant and spore wall

The article provides an overview of the development and structure of spore and pollen walls in the major plant groups and summarises progress in our understanding of the molecular genetics underpinning spore/pollen evolution and development