Environmental boundary conditions for the origin of life converge to an organo-sulfur metabolism

Published in final edited form as: Nat Ecol Evol. 2019 December ; 3(12): 1715–1724. doi:10.1038/s41559-019-1018-8.It has been suggested that a deep memory of early life is hidden in the architecture of metabolic networks, whose reactions could have been catalyzed by small molecules or minerals before genetically encoded enzymes. A major challenge in unravelling these early steps is assessing the plausibility of a connected, thermodynamically consistent proto-metabolism under different geochemical conditions, which are still surrounded by high uncertainty. Here we combine network-based algorithms with physico-chemical constraints on chemical reaction networks to systematically show how different combinations of parameters (temperature, pH, redox potential and availability of molecular precursors) could have affected the evolution of a proto-metabolism. Our analysis of possible trajectories indicates that a subset of boundary conditions converges to an organo-sulfur-based proto-metabolic network fuelled by a thioester- and redox-driven variant of the reductive tricarboxylic acid cycle that is capable of producing lipids and keto acids. Surprisingly, environmental sources of fixed nitrogen and low-potential electron donors are not necessary for the earliest phases of biochemical evolution. We use one of these networks to build a steady-state dynamical metabolic model of a protocell, and find that different combinations of carbon sources and electron donors can support the continuous production of a minimal ancient 'biomass' composed of putative early biopolymers and fatty acids.80NSSC17K0295 - Intramural NASA; 80NSSC17K0296 - Intramural NASA; T32 GM100842 - NIGMS NIH HHSAccepted manuscrip

The relationship between the professional status of certificated personnel and the size of the elementary school districts in San Joaquin and Stanislaus Counties

This study was conducted for the purpose of determining whether the size of school districts (in terms of the number of teachers they employ) affects the employment of the instructional staff with regard to their academic preparation, experiences, and professional interest. In question form the problem may be stated: What is the relationship of the professional status of the teacher to the size of the district in the elementary schools of San Joaquin and Stanislaus Counties

Factors Preventing Male Teachers From Seeking Employment at the Elementary Level

The purpose of this qualitative study was to explore the perceptions of male middle school educators regarding the prospects of teaching at the elementary level. A semi-structured interview approach was employed in an effort to assess the factors that lead 12 male educators into middle level teaching positions. Subjects were recruited from diverse public school districts in northern New Jersey and each held elementary and middle school certification. The interview instrument for this study was based on both existing literature surrounding the absence of males in the elementary teaching ranks as well as Brown’s (2002) value-based theory of occupational choice and satisfaction. The latter served as the conceptual framework around which this study was designed. Four themes emerged from this research. The theme, nature of manhood, describes the often-cited differences perceived between men and women and how those differences impact subjects’ perceptions of the teaching profession. The theme, nature of students, reflects perceived variation between elementary-age students and the middle school-age pupils currently under the tutelage of the subject pool. The theme, nature of work, refers to the idea that elementary and middle school teaching positions each require unique energies and dissimilar pedagogical skills. Finally, the theme, stigma, speaks to the perceived impact that teaching younger students either could or would have on the reputation of a male in the role of elementary school teacher. This research has implications in the areas of teacher training and teacher recruitment. The findings offer a rare glimpse at the perceptions of an educational minority—male elementary teachers

Factors Preventing Male Teachers From Seeking Employment at the Elementary Level

The purpose of this qualitative study was to explore the perceptions of male middle school educators regarding the prospects of teaching at the elementary level. A semi-structured interview approach was employed in an effort to assess the factors that lead 12 male educators into middle level teaching positions. Subjects were recruited from diverse public school districts in northern New Jersey and each held elementary and middle school certification. The interview instrument for this study was based on both existing literature surrounding the absence of males in the elementary teaching ranks as well as Brown’s (2002) value-based theory of occupational choice and satisfaction. The latter served as the conceptual framework around which this study was designed. Four themes emerged from this research. The theme, nature of manhood, describes the often-cited differences perceived between men and women and how those differences impact subjects’ perceptions of the teaching profession. The theme, nature of students, reflects perceived variation between elementary-age students and the middle school-age pupils currently under the tutelage of the subject pool. The theme, nature of work, refers to the idea that elementary and middle school teaching positions each require unique energies and dissimilar pedagogical skills. Finally, the theme, stigma, speaks to the perceived impact that teaching younger students either could or would have on the reputation of a male in the role of elementary school teacher. This research has implications in the areas of teacher training and teacher recruitment. The findings offer a rare glimpse at the perceptions of an educational minority—male elementary teachers

The Legal Challenge of Protecting Animal Migrations as Phenomena of Abundance

Animal migrations are as familiar as geese in the sky on a fall afternoon and as mysterious as the peregrinations of sea turtles across thousands of miles of open ocean. This article discusses the distinguishing attributes of animal migrations, why they are important to biodiversity conservation, and the legal challenges posed by migration conservation. In particular, the article focuses on those aspects of migration conservation that existing law, dominated by imperiled species protection, fails to address. It consequently suggests law reforms that would better conserve animal migrations. A step toward serious legal efforts to protect the process and function of migration would represent significant broadening of the current framework for biodiversity protection policy. This article begins by describing animal migrations and explaining the common threats that raise conservation concerns. Any successful strategy for protecting migration will need to address habitat destruction, human-created obstacles, overexploitation (i.e., hunting and fishing), and climate change. The article examines the four key legal elements of a conservation strategy. The first is the establishment of differential thresholds of action responsive to different abundance goals for a migration. Second is transboundary coordination, which may involve international or interstate agreements, depending on the scale of the migration. Third is the protection of migration connectivity. Effective connectivity requires designation of corridors. Within the corridors, legal activity should concentrate on acquisition of habitat as well as activity-based regulation of habitat-disturbing practices. Fourth is controlling commercial and recreational harvests of migrating animals or the species on which the migrations rely. Finally, the article presents a theoretical model that tailors a place-based legal response to both migratory population abundance and the ecological importance of habitat. Application of the model would result in variable levels of legal protection to minimize unnecessary costs and optimize the benefit of conservation efforts. Existing attempts to conserve migrations using variable levels of protection compose a mixed record from which we extract lessons

The Legal Challenge of Protecting Animal Migrations as Phenomena of Abundance

Animal migrations are as familiar as geese in the sky on a fall afternoon and as mysterious as the peregrinations of sea turtles across thousands of miles of open ocean. This article discusses the distinguishing attributes of animal migrations, why they are important to biodiversity conservation, and the legal challenges posed by migration conservation. In particular, the article focuses on those aspects of migration conservation that existing law, dominated by imperiled species protection, fails to address. It consequently suggests law reforms that would better conserve animal migrations. A step toward serious legal efforts to protect the process and function of migration would represent significant broadening of the current framework for biodiversity protection policy. This article begins by describing animal migrations and explaining the common threats that raise conservation concerns. Any successful strategy for protecting migration will need to address habitat destruction, human-created obstacles, overexploitation (i.e., hunting and fishing), and climate change. The article examines the four key legal elements of a conservation strategy. The first is the establishment of differential thresholds of action responsive to different abundance goals for a migration. Second is transboundary coordination, which may involve international or interstate agreements, depending on the scale of the migration. Third is the protection of migration connectivity. Effective connectivity requires designation of corridors. Within the corridors, legal activity should concentrate on acquisition of habitat as well as activity-based regulation of habitat-disturbing practices. Fourth is controlling commercial and recreational harvests of migrating animals or the species on which the migrations rely. Finally, the article presents a theoretical model that tailors a place-based legal response to both migratory population abundance and the ecological importance of habitat. Application of the model would result in variable levels of legal protection to minimize unnecessary costs and optimize the benefit of conservation efforts. Existing attempts to conserve migrations using variable levels of protection compose a mixed record from which we extract lessons

The Legal Challenge of Protecting Animal Migrations as Phenomena of Abundance

Animal migrations are as familiar as geese in the sky on a fall afternoon and as mysterious as the peregrinations of sea turtles across thousands of miles of open ocean. This article discusses the distinguishing attributes of animal migrations, why they are important to biodiversity conservation, and the legal challenges posed by migration conservation. In particular, the article focuses on those aspects of migration conservation that existing law, dominated by imperiled species protection, fails to address. It consequently suggests law reforms that would better conserve animal migrations. A step toward serious legal efforts to protect the process and function of migration would represent significant broadening of the current framework for biodiversity protection policy. This article begins by describing animal migrations and explaining the common threats that raise conservation concerns. Any successful strategy for protecting migration will need to address habitat destruction, human-created obstacles, overexploitation (i.e., hunting and fishing), and climate change. The article examines the four key legal elements of a conservation strategy. The first is the establishment of differential thresholds of action responsive to different abundance goals for a migration. Second is transboundary coordination, which may involve international or interstate agreements, depending on the scale of the migration. Third is the protection of migration connectivity. Effective connectivity requires designation of corridors. Within the corridors, legal activity should concentrate on acquisition of habitat as well as activity-based regulation of habitat-disturbing practices. Fourth is controlling commercial and recreational harvests of migrating animals or the species on which the migrations rely. Finally, the article presents a theoretical model that tailors a place-based legal response to both migratory population abundance and the ecological importance of habitat. Application of the model would result in variable levels of legal protection to minimize unnecessary costs and optimize the benefit of conservation efforts. Existing attempts to conserve migrations using variable levels of protection compose a mixed record from which we extract lessons