Investigating the Molecular Mechanisms of Spore Killing by Neurospora’s Meiotic Drive Elements

Meiosis is a fundamental and highly conserved biological program that is required for sexual reproduction in eukaryotes. During meiosis, duplicated chromosomes synapse with their homologous partner and undergo a physical exchange of genetic material through recombination. The meiotic products resulting from this program contain novel combinations of alleles that are inherited by individuals in the succeeding generation. The random assortment of alleles during meiotic recombination allows for the chance that any such allelic combination may provide an increase (or decrease) in fitness for an individual. Alleles, or combinations of alleles, that are beneficial to the organism may be retained within a population through evolutionary pressures, while deleterious alleles, by these same pressures, may be selected against and lost from a population. In this way, a population can become more evolutionarily fit through selection of the most advantageous alleles, which are randomly inherited. Indeed, Mendelian genetics dictates that each unlinked allele in a sexual cross has an equal probability of being inherited in the succeeding (F1) generation. This basic assumption gives each allele a fair opportunity to be represented in the F1 population, where it can then be evaluated for fitness by traditional evolutionary pressures.However, some alleles or loci do not follow typical Mendelian inheritance patterns and are preferentially inherited whenever they are present in a meiotic event. These selfish genetic elements are termed Meiotic Drivers (MDs) or Meiotic Drive Elements (MDEs) and can bias their inheritance ratios in their favor at the expense of a competing allele or locus, leading to a \u3e50% inheritance ratio. Meiotic Drivers can persist or even increase within a population, even if they confer an overall fitness cost to their host because they act in their own interests, rather than altruistically. Due to the fitness costs associated with harboring a Meiotic Drive Element, host genomes have evolved antagonistic mechanisms (suppressors) to limit their spread. The resulting molecular arms race between the host genome and the parasitic Meiotic Driver can contribute significantly to reproductive isolation and promote rapid evolution between populations. Understanding the molecular mechanisms of how Meiotic Drivers bias their transmission ratios can ultimately lead to a better understanding of genetic conflict and how it can shape the evolution of a genome. In this dissertation, I will present research that identifies and characterizes two Meiotic Drive Elements found within the genome of the filamentous fungus, Neurospora crassa and will discuss the molecular and evolutionary implications of meiotic drive in this fungus. Fungal meiotic drive most often manifests in spore killing, where spores (fungal meiotic products) that do not inherit the Meiotic Driver (Spore Killer) are eliminated by a ‘toxin’, while spores that do inherit the Meiotic Driver survive because they produce an ‘antidote’. Thus, surviving spores from a heterozygous cross (a cross between a Spore Killer and a non-Spore Killer) almost always inherit the Spore Killer. In Chapter I, I present a summary of spore killing meiotic drive elements in Neurospora and their associated molecular mechanisms. In Chapter II, I identify the gene responsible for spore killing in N. crassa Spore Killer-2 (Sk-2). This gene, rfk-1, is located on the right border of the Sk-2 locus, which allows it to escape detection of Meiotic Silencing of Unpaired DNA (MSUD), an RNAi-mechanism that can suppress Spore Killers. I show that the rfk-1 transcript contains four exons, three introns, and a premature stop codon that undergoes A-to-I mRNA editing exclusively during meiosis to produce a 130-amino acid product that is not produced during vegetative growth. Finally, I present evidence that rfk-1 originated from a partial gene duplication event of ncu07086, which contains a putative AtpF superfamily domain. In Chapter III, I expand upon the previous chapter and identify a functional role for A-to-I mRNA editing in spore killing. Specifically, I show that RNA editing is required for rfk-1 to produce an mRNA transcript that can produce a toxic version of the RFK-1 protein (RFK-1B). In the absence of editing, RFK-1B cannot be produced and spore killing does not occur. Expression of rfk-1B in vegetative tissue is usually prevented because mRNA editing is not known to occur in vegetative cells of Ascomycete fungi. I show that expression of transgenic rfk-1B, but not unedited rfk-1A, in vegetative tissue is toxic to the fungus, suggesting that mRNA editing protects the host organism from the toxic effects of RFK-1B. Finally, we show that co-expression of the resistance gene, rskSk-2, in vegetative tissue can rescue the toxic effects of rfk-1B. In Chapter IV, I identify a mutation that blocks Sk-3-based spore killing and name this mutation rfk-2UV. The rfk-2 mutation was purified through a series of back-crosses. Whole genome sequencing and three-point cross analysis was used to map mutation to a region 15.6cM from mus-52 on Chromosome III. I show that a knockout of this locus prevents spore killing. Interestingly, cloning this locus into a sensitive host is not sufficient for killing, unlike the AH36 locus identified in Chapter II. This chapter provides the molecular groundwork for identification of the killing element of Sk-3, which will in turn help identify the evolutionary trajectories that led to Sk-2 and Sk-3 spore killers

Equality, Trust and Universalism in Europe, Canada and the United States: Implications for Health Care Policy

A number of theoretical explanations seek to describe the factors that have led to the position of the United States as the last industrialized Western nation without a universal health care program. Theories focus on institutional arrangement, historic precedent, and the influence of the private sector and market forces. This study explores another factor: the role of underlying social values. The research examines differences in values among ten European countries, the United States and Canada, and analyzes the associations between the values that have been seen to contribute the individualism-collectivism dynamic in the United States. The hypothesis that equality and generalized trust are positively associated with universalism is only partially true. Equality is positively associated (B = .301, p \u3c .001), while generalized trust is negatively associated with universalism (B = -.052, p \u3c .001). Not only do Americans show lower levels of support for income equality and universalism than Europeans, but the effect of being American holds even after controlling for socio-demographic and religious variables (B = .044, p \u3c .01). When the model tests the association of equality and trust on universalism in each region, it explains approximately 17 percent of the variance of universalism for the United States, and approximately 13 percent in Europe and Canada

Multiphysics modelling and experimental validation of microelectromechanical resonator dynamics

The modelling of microelectromechanical systems provides a very challenging task in microsystems engineering. This field of research is inherently multiphysics of nature, since different physical phenomena are tightly intertwined at microscale. Typically, up to four different physical domains are usually considered in the analysis of microsystems: mechanical, electrical, thermal and fluidic. For each of these separate domains, well-established modelling and analysis techniques are available. However, one of the main challenges in the field of microsystems engineering is to connect models for the behavior of the device in each of these domains to equivalent lumped or reduced-order models without making unacceptably inaccurate assumptions and simplifications and to couple these domains correctly and efficiently. Such a so-called multiphysics modelling framework is very important for simulation of microdevices, since fast and accurate computational prototyping may greatly shorten the design cycle and thus the time-to-market of new products. This research will focus on a specific class of microsystems: microelectromechanical resonators. MEMS resonators provide a promising alternative for quartz crystals in time reference oscillators, due to their small size and on-chip integrability. However, because of their small size, they have to be driven into nonlinear regimes in order to store enough energy for obtaining an acceptable signal-to-noise ratio in the oscillator. Since these resonators are to be used as a frequency reference in the oscillator circuits, their steady-state (nonlinear) dynamic vibration behaviour is of special interest. A heuristic modelling approach is investigated for two different MEMS resonators, a clamped-clamped beam resonator and a dog-bone resonator. For the clamped-clamped beam resonator, the simulations with the proposed model shows a good agreement with experimental results, but the model is limited in its predictive capabilities. For the dogbone resonator, the proposed heuristic modelling approach does not lead to a match between simulations and experiments. Shortcomings of the heuristic modelling approach serve as a motivation for a first-principles based approach. The main objective of this research is to derive a multiphysics modelling framework for MEMS resonators that is based on first-principles formulations. The framework is intended for fast and accurate simulation of the steady-state nonlinear dynamic behaviour of MEMS resonators. Moreover, the proposed approach is validated by means of experiments. Although the multiphysics modelling framework is proposed for MEMS resonators, it is not restricted to this application field within microsystems engineering. Other fields, such as (resonant) sensors, switches and variable capacitors, allow for a similar modelling approach. In the proposed framework, themechanical, electrical and thermal domains are included. Since the resonators considered are operated in vacuum, the fluidic domain (squeeze film damping) is not included. Starting from a first-principles description, founded on partial differential equations (PDEs), characteristic nonlinear effects from each of the included domains are incorporated. Both flexural and bulk resonators can be considered. Next, Galerkin discretization of the coupled PDEs takes place, to construct reduced-order models while retaining the nonlinear effects. The multiphysics model consists of the combined reduced-order models from the different domains. Designated numerical tools are used to solve for the steady-state nonlinear dynamic behaviour of the combined model. The proposed semi-analytical (i.e. analytical-numerical) multiphysics modeling framework is illustrated for a full case study of an electrostatically actuated single-crystal silicon clamped-clamped beam MEMS resonator. By means of the modelling framework, multiphysics models of varying complexity have been derived for this resonator, including effects like electrostatic actuation, fringing fields, shear deformation, rotary inertia, thermoelastic damping and nonlinear material behaviour. The first-principles based approach allows for addressing the relevance of individual effects in a straightforward way, such that the models can be used as a (pre-)design tool for dynamic response analysis. The method can be considered complementary to conventional finite element simulations. The multiphysics model for the clamped-clamped beam resonator is validated by means of experiments. A good match between the simulations and experiments is obtained, thereby giving confidence in the proposed modelling framework. Finally, next to themodelling approach for MEMS resonators, a technique for using these nonlinear resonators in an oscillator circuit setting is presented. This approach, called phase feedback, allows for operation of the resonator in its nonlinear regime. The closedloop technique enables control of both the frequency of oscillation and the output power of the signal. Additionally, optimal operation points for oscillator circuits incorporating a nonlinear resonator can be defined

An analysis of the relationship between social capital and subjective well-being in four regions of Spain in the mid-1990s

This research offers an analysis of two concepts: subjective well-being and social capital. I examine each concept separately, looking at their underlying determinants and characteristics, and I also look at the links between these two notions, as there is theoretical support for their interdependent relationship. I have conducted data analysis of five samples, all part of the World Values Survey 1995-1996. The WVS 1995-1996 offers vast data for Spain and for four autonomous regions - Basque Country, Andalusia, Galicia and Valencia. For the national sample N= 1211. Regional sampling is as follows: Basque Country (N=2205), Andalusia (N=1803), Galicia (N=1200), and Valencia (N=501). The subjects of all the surveys are citizens of both sexes, aged 18 and older

The Chester News March 17, 1925

The Chester News was a semi-weekly, later weekly continuation of the Semi-Weekly News established in 1913. The name changed to the Chester News in September 1917 retaining the number sequence of the Semi-Weekly News. In 1917 it was a semi-weekly Democrat newspaper. About 1942, it became a weekly paper. W. Ward Pegram and Stewart L. Cassells were the owner/publishers. W. Ward Pegram, Jr. took ownership after his father’s death and published the paper until September 1971 when it merged with the Chester Reporter to form the News and Reporter which is still in publication.https://digitalcommons.winthrop.edu/chesternews1925/1022/thumbnail.jp

The Media Representation and Misrepresentation of Refugees: A Comparison between US and French Media

This project is the study of the differences and similarities between news reporting, using specific media frames, in the US and France in regard to the representation of refugees in newspapers. I gathered a total of 213 articles written during the period of January 1, 2017 until September 30, 2018. Those articles were taken from two major newspapers in the US, The New York Times and the Wall Street Journal and two major newspapers in France, Le Monde and Le Figaro. For this research, I used content analysis in order to analyze the news articles reporting on the subject of refugees and to discover if important underlying messages were present. I chose major newspapers in the US and France with different political views, conservative and liberal in order to find out if the political tendency would somewhat be reflected in the choice of frames and the choice of certain words. The analysis revealed that political ideology did not influence the framing of refugees in terms of economic and security threats. While the human-interest frame should have been an important frame if not the most important frame related to refugees, this was not the case and was instead overshadowed by the managerialist frame. Even though labels such as liberal and conservative are subjective, newspapers choose how to report events and where they position the articles. This allows them to point to the readers the importance of the article in question. Nevertheless, the study did not reveal that refugees could be portrayed differently because a newspaper was considered liberal or conservative. In regard to the most used-frames when covering refugees in the news, the newspapers were rather similar in the frequency of using certain frames. They tended to report stories that were consistent with the policies of their host countries and of other countries as well. Both French and US newspapers reported on the refugee crisis both at home and abroad. In contrast, they differed in the use of certain terms, referred to as variables. Those terms were Islam/Muslim, integration/assimilation, and also using the term migrant/immigrant instead of refugee. The frequency of using certain terms were more predominant in the US newspapers and therefore set them apart

Reforming State Electoral College Laws to Depolarize American Politics

Brnovich v. Democratic National Committee involved the Supreme Court gutting the remaining vestiges of the Voting Rights Act (VRA), such that jurisdictions will have free rein to impose partisan burdens on franchise rights that have a disproportionate negative effect on racial minority voters who, based on racial political polarization, prefer Democratic Party candidates over their Republican opponents. Brnovich follows the highly divisive 2020 presidential election that Joe Biden won against former President Trump based on very narrow margins in highly contested swing states, notwithstanding a nationwide popular margin of more than 8 million votes. This blurring of the lines between partisan and racial motivation in the context of pronounced racial political polarization in a highly contested two-party election framework has left ample room for partisans on both sides of the two-party divide to be incentivized to exacerbate the racial, regional, and socioeconomic cleavages that have systematically undermined national cohesion in recent years. Something must be done to remedy the chasm that divides the country. Some reflexively blame the two-party system and argue for its replacement with a multi-party framework as found in western Europe. Many, including myself, blame the country’s reliance on single-member plurality districting, which encourages partisan gerrymandering and vote dilution of minority party votes. Because presidential governance, more than its Congressional counterpart, relies on democratic legitimacy, a potential means of increasing national cohesion is for state legislatures to reform their means of awarding their states’ Electoral College votes from the current “winner-take-all” framework to one that awards Electoral College votes in rough approximation to the percentage of the two-party vote won by the major candidates, with a bonus vote for the state winner where the popular vote result would otherwise indicate an even split of Electoral College votes (Apportionment Proposal). The Apportionment Proposal will also engender national cohesion by depolarizing the legitimacy of the election outcome in each state, thereby disincentivizing voter suppression and foreign election interference in highly contested swing states because the popular vote outcome in each state will be less outcome determinative. Limiting the award of Electoral College votes to the two leading candidates also protects against the proliferation of splinter and regional party candidates that would undermine national cohesion. Finally, unlike replacement of the Electoral College with a French-style nationwide popular vote, or the often mooted proposal to award bonus Electoral College votes to the nationwide popular vote winner, the Apportionment Proposal does not require a constitutional amendment and protects a key advantage of the original Electoral College, namely to encourage nationwide campaigning by candidates in lieu of monographic focus on the country’s major population centers. This also explains its advantage over the national popular vote compact, whereby each state would award its Electoral College votes to the nationwide popular vote winner

Annual report 1984 Northumberland, New Hampshire.

This is an annual report containing vital statistics for a town/city in the state of New Hampshire