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Full-Text Articles in Life Sciences

Phospholipase D- And Phosphatidic Acid-Mediated Signaling In Plant Response To Abscisic Acid And Reactive Oxygen Species, Liang Guo Dec 2013

Phospholipase D- And Phosphatidic Acid-Mediated Signaling In Plant Response To Abscisic Acid And Reactive Oxygen Species, Liang Guo

Dissertations

The Arabidopsis genome has 12 phospholipase D (PLD) genes that are classified into six types, PLDα, PLDβ, PLDγ, PLDδ, PLDε, and PLDζ, based on sequence similarities, domain structures, and biochemical properties. Phosphatidic acids (PA) produced by PLDs have been identified as important lipid signaling molecules in cell growth, development, and stress responses. This study was undertaken to determine the role of PLD and PA in plant response to abscisic acid (ABA) and reactive oxygen species (ROS). The lipid mediator PA was found to interact with sphingosine kinases (SPHKs) in Arabidopsis. Two unique SPHK cDNAs were cloned and expressed. Both SPHKs ...


The Evolution Of Floral Symmetry Across The Plant Order Lamiales, Jinshun Zhong Dec 2013

The Evolution Of Floral Symmetry Across The Plant Order Lamiales, Jinshun Zhong

Dissertations

Bilaterally symmetrical corollas have evolved independently numerous times from radially symmetrical ancestors and are thought to represent adaptation to specific pollinators. However, evolutionary losses of bilateral symmetry have occurred sporadically in different lineages. CYC2-like and RAD-like are genes needed for the normal development of bilateral symmetry in snapdragon corollas. However, exactly how changes in the floral symmetry patterning genes correlate with the origin and loss of floral bilateral remains poorly known. To address this question, a densely sampled phylogeny of CYC2-like genes across the order Lamiales was inferred and calibrated. The expression patterns of these genes in early diverging and ...


Elucidating The Factors That Modulate The Distribution Of Avian Haemosporida Parasites Across A Community Of Hosts, Matthew Christopher Ikaika Medeiros Dec 2013

Elucidating The Factors That Modulate The Distribution Of Avian Haemosporida Parasites Across A Community Of Hosts, Matthew Christopher Ikaika Medeiros

Dissertations

Parasites are heterogeneously distributed across host species, host populations, and host individuals within populations. A primary aim of infectious disease ecology seeks to uncover the factors that drive this heterogeneity. At a fundamental level, host infection is determined by exposure and susceptibility to a pathogen. My dissertation explores how evolutionary and ecological forces associated with these fundamental determinates of infection shape variation in parasite host breadth and host infection status. Here, I focus on a community of vector-borne avian Haemosporida parasites among suburban birds of Chicago, IL. These parasites exhibit strong variation in their distribution among available hosts, and provide ...


Exploring The Local And Regional Effects Of Plant Diversity On Plant Herbivore Interactions, Diego Salazar Dec 2013

Exploring The Local And Regional Effects Of Plant Diversity On Plant Herbivore Interactions, Diego Salazar

Dissertations

The study of biological diversity and its effects on ecosystem functioning and species interactions has always been a fundamental part of biology. The accelerating loss of species in conjunction with an increasing change in the natural environment has underlined the importance of the role that biodiversity has on the evolutionary and ecological dynamics of natural systems. In this dissertation I explore the effect of local and regional patterns of plant diversity in plant-herbivore interactions. Furthermore, this work goes beyond the classical concepts of taxonomical diversity and investigates the role of phylogenetic and chemical diversity on plant-herbivore interactions. In chapter one ...


Middle Mississippi River Islands: Historical Distribution, Restoration Planning, And Biological Importance, Teresa Cecilia Allen Nov 2013

Middle Mississippi River Islands: Historical Distribution, Restoration Planning, And Biological Importance, Teresa Cecilia Allen

Dissertations

The Middle Mississippi River’s (MMR’s) hydrology and sedimentation patterns have been altered. These activities contribute to loss of backwaters, islands, secondary channels, and reduced biodiversity. The Fish and Wildlife Service included reasonable and prudent alternatives (RPAs) in its Biological Opinion for the Operation and Maintenance of the Nine-Foot Channel Navigation Project. These RPAs mandate dike notching and island building to increase habitat diversity. My first goal was to examine changes in the number and relative location of islands from 1797 to 2003. I found that the total number of islands increased, the number of central islands decreased, and ...


Colonization History And Origin Of The Galapagos Flycatcher (Myiarchus Magnirostris) And Its Parasites, Eloisa Helena Reis Sari Aug 2013

Colonization History And Origin Of The Galapagos Flycatcher (Myiarchus Magnirostris) And Its Parasites, Eloisa Helena Reis Sari

Dissertations

The Galápagos flycatcher (Myiarchus magnirostris) is an endemic species to the Galápagos Islands, Ecuador, and is among the least studied Galápagos terrestrial birds. In this work I unveiled the origin and colonization history of the Galápagos flycatcher, and also the origin of the parasites that are currently found in/on this bird species. To determine the origin of the Galápagos flycatcher, I rebuilt the phylogeny of the Myiarchus genus using cytb and ND2, and applied a Bayesian approach to estimate its colonization time. I discovered that the closest living relative of the Galápagos flycatcher is Myiarchus tyrannulus (Brown-crested flycatcher) from ...


Diversification And Coexistence In The Madagascar Olive (Noronhia, Oleaceae), Cynthia Hong-Wa Apr 2013

Diversification And Coexistence In The Madagascar Olive (Noronhia, Oleaceae), Cynthia Hong-Wa

Dissertations

The long-isolated island of Madagascar provides a suitable setting for studying species diversification, with most groups of organisms there both radiating and showing a high level of endemism. Noronhia is one of these groups and represents the most successful radiation of the olive family (Oleaceae) in Madagascar, with ca. 80 species. In this study, using plastid and nuclear DNA sequences obtained from a comprehensive sampling both within Noronhia and the family, I show that Noronhia, together with Indian Ocean species of Chionanthus, form a monophyletic clade sister to African Chionanthus. The diversification of Noronhia followed a likely Cenozoic dispersal from ...