Patterns of Distribution Along a Salinity Gradient in the Flatback Mud Crab Eurypanopeus depressus

To measure the effect of salinity on estuarine communities, spatial and temporal variations in population distribution were investigated in the flatback mud crab Eurypanopeus depressus (Smith, 1869), a dominant species on oyster reefs in southwest Florida. Eurypanopeus depressus were collected using lift nets (1 m2 ) deployed at three morphologically homologous stations along a salinity gradient in each of three estuaries. They were sampled monthly during three seasonally wet and three seasonally dry months. An analysis of abundance showed that although this species can survive extreme salinities, it is most common in moderate environments. Biomass is also highest at moderate salinities, though mean size is larger at low salinities. Few significant differences in these metrics between seasons were observed. These results suggest that although E. depressus is little affected by normal seasonal changes in salinity, salinity does play a role in its distribution. In light of these findings, changes in the freshwater flow regime of Southwest Florida estuaries as a result of land use changes resulting from human development have the potential to alter oyster-reef community structure

Townscape transformations in dockland areas: case studies in the UK

The dockland redevelopment phenomenon, which first occurred in North America over twenty years ago, has become a significant aspect of urban change. Extensive redevelopment of decaying and moribund dockland sites first began in Britain during the 1970s, continued throughout the 'property boom' years of the 1980s and is still occurring - albeit at a much reduced rate - in the 1990s. However, while extensive research has been carried out on the social and economic aspects of dockland rejuvenation, very little is known about the physical or townscape aspects of this process. The present study addresses this gap in research. The processes of recent townscape change are examined in three dockland areas - London, Cardiff and Bristol. In two of these areas redevelopment was initiated either partly or wholly by Urban Development Corporations, and in the third, redevelopment was initiated by a City Planning Authority. First, there is an analysis of the roles of those who are responsible for creating the built environment, such as developers, architects, planning authorities, Urban Development Corporations and residents of dockland developments. Secondly, there is a dicussion of how the decisions taken by these 'agents of townscape change' affect the physical forms that have resulted in docklands. Thirdly, the views of dockland residents on the cultural and symbolic significance of dockland townscapes are examined. The principal data sources are the Development Control records held by Cardiff and Bristol City Planning Authorities, semi-structured interviews conducted with Urban Development Corporations, developers and architects, and extensive fieldwork. These data are supplemented by a questionnaire survey of dockland residents. The main conclusion of the thesis is threefold. First, it is evident that Urban Development Corporations differ from planning authorities in their approaches to development control and design control. For example, whereas the London Docklands Development Corporation has an extremely flexible, Iaissez faire, approach to planning, Bristol CPA has adopted a far more through-going, interventionist approach. A second conclusion is that developers are primarily concerned with 'profit-maximisation', and if they consider design at all, it is of little overall importance. Developers of dockland sites are without exception national companies who employ 'external' rather than 'in-house' architects. Thirdly, it is evident that residents of docklands generally like both the architectural appearance of the developments in which they live, and in particular the layout and design of waterfront areas. In spite of this, many have difficulty in understanding the more deeply-rooted symbolic or semiotic meanings that are conveyed by some Post-Modern buildings

Poverty, Race and the Contexts of Achievement: Examining Educational Experiences of Children in the American South

This paper reports findings of a study examining child-, classroom-, and school-level factors that effect academic achievement among public school children in the South. Using ECLS-K data, we compare and contrast the learning environments in high/low minority and high/low poverty schools. A sizeable minority of Southern children attend schools that are race and/or class segregated; on multiple dimensions these schools are less desirable than are schools attended by more privileged children, and children attending these schools have lower levels of academic achievement. Results from 3-level random intercepts models show that a range of child and family factors, as well as classrooms with less experienced teachers and with more low-level readers, and rural school location all contribute to lower reading gains during first grade. We find no “race effects” on achievement, net of other variables. Issues of “selection” are discussed, and implications for social work are explored

The bloodstream form of Trypanosoma brucei displays non-canonical gluconeogenesis

Trypanosoma brucei is a causative agent of the Human and Animal African Trypanosomiases. The mammalian stage parasites infect various tissues and organs including the bloodstream, central nervous system, skin, adipose tissue and lungs. They rely on ATP produced in glycolysis, consuming large amounts of glucose, which is readily available in the mammalian host. In addition to glucose, glycerol can also be used as a source of carbon and ATP and as a substrate for gluconeogenesis. However, the physiological relevance of glycerol-fed gluconeogenesis for the mammalian-infective life cycle forms remains elusive. To demonstrate its (in)dispensability, first we must identify the enzyme(s) of the pathway. Loss of the canonical gluconeogenic enzyme, fructose-1,6-bisphosphatase, does not abolish the process hence at least one other enzyme must participate in gluconeogenesis in trypanosomes. Using a combination of CRISPR/Cas9 gene editing and RNA interference, we generated mutants for four enzymes potentially capable of contributing to gluconeogenesis: fructose-1,6-bisphoshatase, sedoheptulose-1,7-bisphosphatase, phosphofructokinase and transaldolase, alone or in various combinations. Metabolomic analyses revealed that flux through gluconeogenesis was maintained irrespective of which of these genes were lost. Our data render unlikely a previously hypothesised role of a reverse phosphofructokinase reaction in gluconeogenesis and preclude the participation of a novel biochemical pathway involving transaldolase in the process. The sustained metabolic flux in gluconeogenesis in our mutants, including a triple-null strain, indicates the presence of a unique enzyme participating in gluconeogenesis. Additionally, the data provide new insights into gluconeogenesis and the pentose phosphate pathway, and improve the current understanding of carbon metabolism of the mammalian-infective stages of T. brucei.</p

The bloodstream form of Trypanosoma brucei displays non-canonical gluconeogenesis

Trypanosoma brucei is a causative agent of the Human and Animal African Trypanosomiases. The mammalian stage parasites infect various tissues and organs including the bloodstream, central nervous system, skin, adipose tissue and lungs. They rely on ATP produced in glycolysis, consuming large amounts of glucose, which is readily available in the mammalian host. In addition to glucose, glycerol can also be used as a source of carbon and ATP and as a substrate for gluconeogenesis. However, the physiological relevance of glycerol-fed gluconeogenesis for the mammalian-infective life cycle forms remains elusive. To demonstrate its (in)dispensability, first we must identify the enzyme(s) of the pathway. Loss of the canonical gluconeogenic enzyme, fructose-1,6-bisphosphatase, does not abolish the process hence at least one other enzyme must participate in gluconeogenesis in trypanosomes. Using a combination of CRISPR/Cas9 gene editing and RNA interference, we generated mutants for four enzymes potentially capable of contributing to gluconeogenesis: fructose-1,6-bisphoshatase, sedoheptulose-1,7-bisphosphatase, phosphofructokinase and transaldolase, alone or in various combinations. Metabolomic analyses revealed that flux through gluconeogenesis was maintained irrespective of which of these genes were lost. Our data render unlikely a previously hypothesised role of a reverse phosphofructokinase reaction in gluconeogenesis and preclude the participation of a novel biochemical pathway involving transaldolase in the process. The sustained metabolic flux in gluconeogenesis in our mutants, including a triple-null strain, indicates the presence of a unique enzyme participating in gluconeogenesis. Additionally, the data provide new insights into gluconeogenesis and the pentose phosphate pathway, and improve the current understanding of carbon metabolism of the mammalian-infective stages of T. brucei.</p

Velvet Brass

Capen Auditorium Edwards Hall Monday Evening March 31, 1997 8:00p.m

Tailings Dust Emissions

Fugitive dust emissions from the storage and handling of mine tailings presents environmental and safety concerns, which must be addressed to promote the land sustainability and the health and safety of individuals around a tailings storage facility (TSF). The investigated dust control methods were agglomeration, binder slurry injection, and topical spray. The Dust Busters determined that pelletizing was the most practical method of agglomeration. In order to produce durable pellets from the mine tailings, which consist primarily of silica, a binder must be added. A variety of binders were considered including magnesium and calcium chloride, bentonite, barite, cement, vinyl polymers, acrylic polymers, starch, carboxymethyl cellulose, and a commercial lignosulfonate/bitumen blend. Portland cement proved to be the most effective binder in regards to the pellet’s cost, structural integrity, and longevity. However, due to the abrasive nature of the tailings, pelletizing is not cost effective in comparison to other dust suppression techniques. Binder slurry injection incorporates a pugmill mixer to inject a binding agent into the tailings slurry. Addition of a binder allows the slurry mixture to form a rigid crust that prevents fugitive dust once dried on the existing tailings dam. While the injected slurry is effective at minimizing dust emissions, it is not economically feasible due to high capital costs. The most effective, environmentally safe, and economically feasible solution to reduce the dust associated with tailings storage facilities is a topical spray solution consisting of a vinyl copolymer. The vinyl copolymer, at relatively low concentrations, produces a robust yet permeable crust along the surface of the tailings, which is unmatched in comparison to the other binding agents. By applying the binder as topical solution rather than injecting the binder into the slurry, the capital cost for effective dust suppression is reduced by eliminating the additional process equipment required for both pelletizing and binder slurry injection. Treating 400 acres per year with a vinyl copolymer application costs $110,000. Existing equipment and personnel are adequate to change from the current magnesium chloride treatment to a vinyl copolymer treatment. Current yearly treatments using the magnesium chloride cost approximately$240,000-$720,000 assuming 1-3 applications per year across the 400 acre area; thus changing to a vinyl copolymer treatment will save$130,000-$390,000 per year

CRISPR/Cas9-based precision tagging of essential genes in bloodstream form African trypanosomes

Proteins of interest are frequently expressed with a fusion-tag to facilitate experimental analysis. In trypanosomatids, which are typically diploid, a tag-encoding DNA fragment is typically fused to one native allele. However, since recombinant cells represent ≪0.1% of the population following transfection, these DNA fragments also incorporate a marker cassette for positive selection. Consequently, native mRNA untranslated regions (UTRs) are replaced, potentially perturbing gene expression; in trypanosomatids, UTRs often impact gene expression in the context of widespread and constitutive polycistronic transcription. We sought to develop a tagging strategy that preserves native UTRs in bloodstream-form African trypanosomes, and here we describe a CRISPR/Cas9-based knock-in approach to drive precise and marker-free tagging of essential genes. Using simple tag-encoding amplicons, we tagged four proteins: a histone acetyltransferase, HAT2; a histone deacetylase, HDAC3; a cleavage and polyadenylation specificity factor, CPSF3; and a variant surface glycoprotein exclusion factor, VEX2. The approach maintained the native UTRs and yielded clonal strains expressing functional recombinant proteins, typically with both alleles tagged. We demonstrate utility for both immunofluorescence-based localisation and for enriching protein complexes; GFPHAT2 or GFPHDAC3 complexes in this case. This precision tagging approach facilitates the assembly of strains expressing essential recombinant genes with their native UTRs preserved

Postpartum lifestyle behaviour among women with prior gestational diabetes mellitus : evidence from the HUNT study

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