Inner ear morphology in the Atlantic molly Poecilia mexicana

Fishes show an amazing diversity in hearing abilities, inner ear structures, and otolith morphology. Inner ear morphology, however, has not yet been investigated in detail in any member of the diverse order Cyprinodontiformes. We, therefore, studied the inner ear of the cyprinodontiform freshwater fish Poecilia mexicana by analyzing the position of otoliths in situ, investigating the 3D structure of sensory epithelia, and examining the orientation patterns of ciliary bundles of the sensory hair cells, while combining μ-CT analyses, scanning electron microscopy, and immunocytochemical methods. P. mexicana occurs in different ecotypes, enabling us to study the intra-specific variability (on a qualitative basis) of fish from regular surface streams, and the Cueva del Azufre, a sulfidic cave in southern Mexico. The inner ear of Poecilia mexicana displays a combination of several remarkable features. The utricle is connected rostrally instead of dorso-rostrally to the saccule, and the macula sacculi, therefore, is very close to the utricle. Moreover, the macula sacculi possesses dorsal and ventral bulges. The two studied ecotypes of P. mexicana showed variation mainly in the shape and curvature of the macula lagenae, in the curvature of the macula sacculi, and in the thickness of the otolithic membrane. Our study for the first time provides detailed insights into the auditory periphery of a cyprinodontiform inner ear and thus serves a basis--especially with regard to the application of 3D techniques--for further research on structure-function relationships of inner ears within the species-rich order Cyprinodontiformes. We suggest that other poeciliid taxa, or even other non-poeciliid cyprinodontiforms, may display similar inner ear morphologies as described here

‘My master and Miss … warn’t nothing but poor white trash’ : poor white slaveholders and their slaves in the antebellum South

While the majority of enslaved people lived on large plantations, there were a significant minority who lived on smaller farms where they and their families were the only slaves owned by their master (or mistress). This article uses 22 Works Progress Administration (WPA) interviews conducted in the 1930s with former slaves from across the South to investigate the lives of enslaved people living with masters or mistresses that they described as ‘poor’, and argues that enslaved experiences on small farms owned by poor whites varied widely, but were marked particularly by violence, material deprivation, and intense loneliness

Creating A Scaling Relationship Between Peak Discharge And Drainage Area To Identify Tile Drainage Inputs Into An Agricultural Stream

Tile drains have been shown to contribute to high levels of nitrate in agricultural streams. Locations of tile drains on a watershed scale, however, are often unknown due to tile drains being located on many separate parcels of private property. This study evaluates the ability of a methodology, using scaling relationships between discharge and drainage area, for locating areas of large tile drainage contribution to Money Creek, in McLean County, Illinois. Additionally, this study examines the difference in scaling relationships and physical stream hydrology between tileflow and no-tileflow conditions. Eight stream sites were created in the watershed, that recorded stage every 15 minutes. The drainage area of each stream site was calculated in ArcGIS. Hydrographs were created from rating curves that were developed for each site, and used to create scaling relationships between peak discharge and drainage area for 21 storms throughout the study period. Overall, this method was not effective for detecting tile drain input into Money Creek, because there were no major differences in the outliers of the scaling relationships between the tileflow and no-tileflow periods. The scaling exponent means between the tileflow and no-tileflow period were statistically different. This is likely due to, factors that other studies have shown to cause regional differences in scaling exponents (evapotranspiration, soil moisture storage, and sunshine) are causing seasonal differences in the scaling exponent within the Money Creek watershed. Additionally, this study observed double peaks in storm hydrographs, which were interpreted as being caused from the difference in runoff generation timing between overland flow and tile drainage

Superintendent Leadership in Small, Rural Minnesota Public Schools

The purpose of the research was to investigate the leadership skills of rural Minnesota superintendents alongside the academic achievement of the school district. Through the correlates of school leadership espoused by Waters and Marzano, this research analyzed the leadership characteristics of the superintendents in those districts and the level of educational excellence achieved under them. A multiple case study methodology was used to study nine rural Minnesota school districts and superintendents. Through a written survey, this study considered collaborative goal setting, nonnegotiable goals for academic achievement, board alignment with district goals, monitoring achievement and instruction, and allocating resources to support those academic goals (Waters & Marzano, 2006). Based on the research of this study, the author has concluded that the superintendents did collaborate with faculty, board and public to set goals for academic achievement and classroom instruction; the superintendent and board monitored progress on their goals, and the school boards supported them through their physical support for those goals. Was there a correlation in this study between superintendent leadership and academic achievement and classroom instruction? The answer to that question might depend on the data used to answer that question. According to the Minnesota Comprehensive Assessment (MCA) testing results, there was no noteworthy increase in test scores as a result of superintendent leadership. Considering the narrative responses and the efforts to meet the goals through the World’s Best Workforce, the superintendents of these school districts are actively involved in the education of the children of their districts through their ongoing efforts to set strategic goals across those districts and then monitor and report the progress to the school boards. There was evidence too, that the strategic goals of the districts included more than just the basic tenets of the World’s Best Workforce plan. The superintendents, as well as the staff, administration and school boards of these districts included additional goals that provided the children in their districts the greatest opportunities for a high quality educational experience. Based on this study of these school districts and their superintendents, the leadership of the superintendents did positively impact student achievement and classroom instruction

Geochemical Analysis of Surface Materials Surrounding the Bautsch-Gray Mine Superfund Site Near Galena, Illinois

The Bautsch-Gray zinc and lead mine, near Galena, Ill., was in operation from the early 1900s until closing in 1975. The mine’s tailings pile has documented elevated lead and zinc concentrations in the surface materials surrounding the site. Numerous floods have caused contaminated sediment to migrate off the mine tailings pile, across Blackjack Road and into an outwash basin, and towards Smallpox Creek. Since this site was designated an EPA priority list superfund site in 2010, there have been numerous remediation efforts. This study attempts to develop a better understanding of the contamination within the soils of the outwash basin down-gradient of the mine as well as within the sediment bedload and vegetation of Smallpox Creek. Forty samples were collected, using a shovel or garden trowel, throughout this area and analyzed for lead and zinc contamination using X-ray fluorescence spectrometry. Excluding six samples from the mine tailings (that served as a baseline for contamination levels in mine tailing sediments), 17 samples exceeded the lead contamination limit of 400 ppm for soils near a superfund site and 21 samples exceeded the zinc contamination limit of 7500 ppm for soils near a superfund site. Though there have been mitigation efforts to remove contamination from the outwash area, these results indicate that there is still more work to be done. High concentrations of lead and zinc in the outwash basin indicate that Smallpox Creek is susceptible to continued contamination from this site

Which corporations are likely to engage in LGBTQ+ activism?

In the past decade corporations have increasingly engaged in social activism, even if it does not relate to their core business. Similarly, CEOs have used their influence to publicly address social issues, such as public policy decisions. Therefore, this paper examines the questions which companies engage in social activism, specifically LGBTQ+ activism. Since CEOs have been more vocal, Upper-Echelon Theory, which states that the values and characteristics of CEOs affect the way an organization behaves, served as the motivation for the research design. The paper looks at LGBTQ+ activism in the form of tweets as the dependent variable, made by the companies in the S&P 500 between 2012 and 2019, in relation to the CEOs leading them. Their age, gender, ethnicity, and political orientation served as the demographic characteristics described in Upper Echelon Theory and as the independent variables tested. The analysis revealed that there is a significant positive relationship between corporate LGBTQ+ activism and liberal CEOs, revealing that the personal politics of the CEOs are an indication for which companies are likely to engage in LGBTQ+ activism. Due to the growing divide between Democrats and Republicans in US politics as well as the partisan approach to social issues this provides insight into where corporate and CEO activism might be headed.Na última década, as empresas têm-se empenhado cada vez mais no ativismo social, mesmo que não se relacione com o objetivo principal do seu negócio. De igual modo, os CEOs têm usado a sua influência para responder publicamente a assuntos do foro social, tais como decisões de políticas públicas. Assim, esta tese examina as questões com as quais as empresas lidam, em relação ao ativismo social, especificamente o ativismo LGBTQ+. Desde que os CEOs se tornaram mais vocais, a teoria Upper-Echelon – que afirma que os valores e caraterísticas dos CEOs afetam a forma como uma organização se comporta – serviu de motivação para o design da pesquisa. Este documento olha para o ativismo LGBTQ+ na forma de tweets, como variável dependente, feitos pelas empresas no S&P 500, entre 2012 e 2019, e em relação aos CEOs que as lideram. A sua idade, género, etnia, e orientação política serviram como as caraterísticas demográficas descritas na teoria Upper-Echelon, e como as variáveis independentes testadas. A análise revelou que existe uma relação positiva significativa entre o ativismo LGBTQ+ corporativo e CEOs liberais, revelando que as políticas pessoais dos dirigentes constituem um fator indicativo de que as empresas são mais prováveis de se empenhar no ativismo LGBTQ+. Devido à divergência cada vez maior entre o Partido Democrático e o Partido Republicano nas políticas dos Estados Unidos, bem como a abordagem partidária a assuntos sociais, tal fornece uma observação sobre onde o ativismo corporativo e de CEO se estará a dirigir

Female mating preferences in blind cave tetras Astyanax fasciatus (Characidae, Teleostei).

The Mexican tetra Astyanax fasciatus has evolved a variety of more or less color- and eyeless cave populations. Here we examined the evolution of the female preference for large male body size within different populations of this species, either surface- or cave-dwelling. Given the choice between visual cues from a large and a small male, females from the surface form as well as females from an eyed cave form showed a strong preference for large males. When only non-visual cues were presented in darkness, the surface females did not prefer either males. Among the six cave populations studied, females of the eyed cave form and females of one of the five eyeless cave populations showed a preference for large males. Apparently, not all cave populations of Astyanax have evolved non-visual mating preferences. We discuss the role of selection by benefits of non-visual mate choice for the evolution of non-visual mating preferences

Shared and unique patterns of embryo development in extremophile poeciliids

Background: Closely related lineages of livebearing fishes have independently adapted to two extreme environmental factors: toxic hydrogen sulphide (H2S) and perpetual darkness. Previous work has demonstrated in adult specimens that fish from these extreme habitats convergently evolved drastically increased head and offspring size, while cave fish are further characterized by reduced pigmentation and eye size. Here, we traced the development of these (and other) divergent traits in embryos of Poecilia mexicana from benign surface habitats (“surface mollies”) and a sulphidic cave (“cave mollies”), as well as in embryos of the sister taxon, Poecilia sulphuraria from a sulphidic surface spring (“sulphur mollies”). We asked at which points during development changes in the timing of the involved processes (i.e., heterochrony) would be detectible. Methods and Results: Data were extracted from digital photographs taken of representative embryos for each stage of development and each type of molly. Embryo mass decreased in convergent fashion, but we found patterns of embryonic fat content and ovum/embryo diameter to be divergent among all three types of mollies. The intensity of yellow colouration of the yolk (a proxy for carotenoid content) was significantly lower in cave mollies throughout development. Moreover, while relative head size decreased through development in surface mollies, it increased in both types of extremophile mollies, and eye growth was arrested in mid-stage embryos of cave mollies but not in surface or sulphur mollies. Conclusion: Our results clearly demonstrate that even among sister taxa convergence in phenotypic traits is not always achieved by the same processes during embryo development. Furthermore, teleost development is crucially dependent on sufficient carotenoid stores in the yolk, and so we discuss how the apparent ability of cave mollies to overcome this carotenoid-dependency may represent another potential mechanism explaining the lack of gene flow between surface and cave mollies